2012 GlobalMining LoRes

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ENGINEERING EXCELLENCE

ULTIMATE RELIABILITYGLOBAL SOLUTIONS FOR MINING AND PRIMARY PROCESSING

www.howden.com



HOWDEN, A GLOBAL SUPPLIER

TO THE RESOURCE INDUSTRY

We engineer and construct large turnkey

ventilation, refrigeration and gas cleaning

systems, integrate equipment into existing plant,

or supply stand-alone units for user-defined

duties. With nearly 160 years’ experience it is

little wonder that the world’s major commoditiesproducers trust us to design, build, install and

commission engineered solutions that offer the

user exceptional performance and dependability,

even in the harshest operating conditions.

Our success follows from our professional

engineers’ enduring quest to design the optimum

solution for each customer, supported by a shared

worldwide institutional knowledge base that is the

envy of our competitors. We use sophisticated

computer software and our international

experience to examine multiple solutions for the

customer’s application. The best option is selected

for each mining or processing requirement, and

then designed using sophisticated ComputerAided Design (CAD) programs. Tests with flow

modelling software ensure the performance and

efficiency of the design is optimised for the task.

Howden products are manufactured in

world-class facilities under quality assurance

management systems certified to international

standards. Our artisans have years’ of experience

in fabricating hardware that has stood the test of

time at site, where it matters most.

The equipment is inst alled and commissioned

by site service staff led by experienced project

managers, and serviced and supported by

skilled maintenance engineers. Howden

understands the production, efficiency and

system availability priorities of the resourcesindustry; we have the intellectual capital to

match these requirements, the capacity to

build and supply them world-wide and the

commitment and passion to support them

throughout their extended operational lives.

HOWDEN’S VENTILATION, COOLING, GAS CLEANING EQUIPMENT AND OTHER KNOW-HOW

ARE USED TO HELP WREST AND PROCESS PRECIOUS AND BASE METALS, COAL ENERGY AND

MINERALS FROM THE WORLD’S MOST DEMANDING MINING ENVIRONMENTS.



1

CONTENTSAPPLICATIONS

Hard Rock Mining 4

Coal Mining 6

Copper Processing 8

Iron Pelletising 10

Mineral Sands 12

Nickel Processing 14

Alumina Production 16

Uranium Processing 18

Base Metals Refining 20

Platinum Extraction and Concentration 22

Gold Concentrating and Refining 24

Potash and Fertiliser 26

PRODUCTS

Heavy Duty Centrifugal Fans 30

Medium Duty Centrifugal Fans 32

Adjustable Pitch Axial Flow Fans 34

Auto Variable Pitch Axial Flow Fans 36

Heavy Duty Mixed Flow Fans 38

Auxiliary and Portable Fans 40

Cooling Fans 42

Electrical, Instrumentation and Control Systems 44

Compressors 46

Attenuators 48

Centrifugal Blowers 50

Hard Ice Plants & Thermal Ice Storage 52

Dust Collection and Flue Ga s Cleaning 54

Chillers 56

Portable Cooling Plant 58

Furnaces and Industrial Combustion 60

Furnace Off-gas Recovery Plant 61

Rotary Heat E xchangers 62

Dust Scrubbers 64

SERVICES

Howden Legacy Brands 68

Howden Mining Products Capabilities 70

Turnkey Installations 72

Lifetime Maintenance 74

HOWDEN KNOW HOW

Content for Knowledge and Information Section

Fan Blades 31

Fan Design 33

Fan Laws 35

Fan Power & Speed 37

Fan Choices 39

Fan Stall 41

Fan Noise Levels 43

Fan Systems 45

Compressors 47

Acoustics 49

Compressor Assessment 51

Fan Bids 53

Fan Maintenance 55Fan Increasing Output 57

Fan Pressure 59

Rotary Air Heater Bids 60

Rotary Air Heaters 63

Rotary Air Heater Elements 65



2



3

APPLICATION OF PRODUCTSFOR ALL MINING AND MINERAL PROCESSING

IN THIS SECTION

Hard Rock Mining 4

Coal Mining 6

Copper Processing 8

Iron Pelletising 10

Mineral Sands 12

Nickel Processing 14

Alumina Production 16

Uranium Processing 18

Base Metals Refining 20

Platinum Extraction and Concentration 22

Gold Concentrating and Refining 24

Potash and Fer tiliser 26



4

HARD ROCK MINING PRESENTS ONE OF THE HOTTEST AND MOST

DIFFICULT WORKPLACE ENVIRONMENTS IN THE WORLD. HOWDEN

TRANSFERS COOLED, FRESH AIR KILOMETRES BENEATH THE

SURFACE OF DEEP-LEVEL MINES SO THAT MINING OPERATIONS

CAN BE MAINTAINED AND INVESTMENT RETURNS MAXIMISED.

HARD ROCK MINING

OUR EQUIPMENT AND SERVICES INCLUDE

• Turnkey design, fabrication and installation

of main surface fans

• Design and installation of underground

booster fans

• Auxiliary fans

• Turnkey mine cooling plant

• Cooling fans for heat exchangers

• Electrical instrumentation and control systems

• Fan noise attenuation Methane gas abatement

Low pressure, high volume rock fans



5

APPLICATION OF PRODUCTS



6

HOWDEN HAS A RANGE OF SOLUTIONS AND EQUIPMENT DESIGNED

SPECIFICALLY FOR COAL MINERS. A RELIABLE SUPPLY OF FRESH AIR ISSUPPLIED UNDERGROUND AND COAL DUST IS REMOVED FROM THE

ATMOSPHERE TO IMPROVE SAFETY AND HEALTH.

COAL MINING


• Turnkey design, fabrication and insta llation

of main surface fans

• Design and installation of underground

booster fans

• Auxiliary fans

• Dust scrubbers

• Dust collectors supplied on a turnkey basis


• Fan noise attenuation

• Portable Cooling Plant

• Methane gas abatement

• Underground Coal Gasification

(UCG) Processes



8

COPPER PROCESSING


• Turnkey axial fan installations

• Turnkey wet dust scrubbing and dry dust collecting

• Efficient, two-stage centrifugal flotation blowers

• Turnkey flue gas cleaning for furnaces

• Turbo and multi-stage centrifugal blowers


• Electrical control and instrumentation systems

• Cooling Plant

• Preheaters

SPECIALISED SYSTEMS AND EQUIPMENT ARE DESIGNED FOR

THE COPPER RECOVERY PROCESS, AND ARE SUPPLIED EITHER

ON A TURNKEY BASIS OR AS STAND-ALONE SYSTEMS ENGINEERED

TO INDIVIDUAL REQUIREMENTS.



9




11




12

MINERAL SANDS


• Fluidising and combustion air fans

• Calcining kiln induced draft fans

• Multi-stage centrifugal blowers


• Turnkey furnace off-gas recovery plant

FOR MINERALS SANDS PROCESS PLANTS HOWDEN ENGINEERS

CUSTOMER-SPECIFIED FANS AND ANCILLARY SYSTEMS.



13




14

NICKEL PROCESSING


• Design and installation of hot gas fans

• Efficient, two-stage centrifugal flotation blowers

• Turnkey wet dust scrubbing and dry

dust collecting

• Turnkey flue gas cleaning • Cooling fans for heat exchangers



SEVERAL DIFFERENT PRODUCTS AND SYSTEMS ARE SUPPLIED

FOR USE THROUGHOUT THE NICKEL SMELTING PROCESS.

THESE ARE ENGINEERED EITHER ON A TURNKEY BASIS, OR

SUPPLIED ACCORDING TO THE UNIQUE SPECIFICATIONS

OF EACH CUSTOMER.



15




16

ALUMINA PRODUCTION

HOWDEN IS EXPERIENCED IN DESIGNING SYSTEMS USED BY THE WORLD’SLEADING ALUMINIUM PRODUCERS WHERE ITS EQUIPMENT IS USED

EXTENSIVELY IN THE PROCESS TO CONVERT BAUXITE TO ALUMINA.


• Design and installation of calciner forced and

induced draft fans

• Design and installation of liquor burning induced

draft fans



dust collecting

• Turnkey flue gas cleaning


• Packaged air heater solutions





17




18

URANIUM PROCESSING



dust collecting

• Design and installation of calciner fans


• Cooling fans for heat exchangers• Electrical instrumentation and control systems

• Flotation blowers


URANIUM PROCESSING IS SUPPORTED THROUGH THE SUPPLY OF

SYSTEMS AND CUSTOMER-SPECIFIED EQUIPMENT, STARTING AT

CRUSHING AND MILLING AND EXTENDING TO THE PRODUCTION

OF YELLOW CAKE.



19




20

BASE METALS REFINING


• Turnkey axial fan installations

• Design and installation of hot gas fans







• Furnaces

A SELECTION OF EQUIPMENT IS SUPPLIED FOR USE ON BASE METALS

PROCESSING PLANTS SUCH AS THOSE FOR CHROMIUM, COBALT,

LEAD, MAGNESIUM, TIN AND ZINC. ALL SYSTEMS ARE ENGINEERED

ACCORDING TO THE CUSTOMER’S SPECIFICATIONS AND OFFERED

WITH LONG-TERM MAINTENANCE AND ENGINEERING SUPPORT.



21




22

PLATINUM EXTRACTIONAND CONCENTRATION



• Efficient, multi-stage centrifugal flotation blowers

• Air blowers

• Turnkey flue gas cleaning




• Furnace off-gas recovery


HOWDEN HAS AN ESTABLISHED REPUTATION FOR

SUPPLYING A RANGE OF RELIABLE EQUIPMENT USED

DURING THE EXTRACTION AND CONCENTRATION

STAGES OF THE PLATINUM RECOVERY PROCESS.



23




24

GOLD CONCENTRATING AND REFINING



dust collecting

• Efficient, multi-stage centrifugal flotation blowers


• Electrical control and instrumentation• Gold room ventilation and gas cleaning

HOWDEN HAS A LONG HISTORY IN GOLD CONCENTRATING AND

REFINING, AND IS ABLE TO ADAPT ITS EQUIPMENT AND SYSTEMS

INTO A RANGE OF FIT-FOR-PURPOSE SOLUTIONS FOR USE IN

DIFFERENT GOLD EXTRACTION PROCESSES.



25




26

POTASH AND FERTILISER


• Dust scrubbers and dust collectors supplied

on a turnkey basis

• Furnaces

• Combustion air fans

• Design and installation of calciner fans• Electrical control and instrumentation


• Airheaters

• Rotary air-preheaters

HOWDEN SUPPLIES SEVERAL SYSTEMS TO THE POTASH

AND FERTILISER INDUSTRIES FOR USE DURING RECOVERY

AND PROCESSING. ALL SYSTEMS ARE SUPPLIED TO

CUSTOMER SPECIFICATION.



27




28



29

HOWDEN PRODUCTSAN EXTENSIVE RANGE AND A GLOBAL REACH

IN THIS SECTION

Heavy Duty Centrifugal Fans 30

Medium Duty Centrifugal Fans 32

Adjustable Pitch Axial Flow Fans 34

Auto Variable Pitch Axial Flow Fans 36

Heavy Duty Mixed Flow Fans 38

Auxiliary and Portable Fans 40

Cooling Fans 42

Electrical, Instrumentation and Control Systems 44

Compressors 46

Attenuators 48

Centrifugal Blowers 50

Hard Ice Plants & Thermal Ice Storage 52

Dust Collection and Flue Ga s Cleaning 54

Chillers 56

Portable Cooling Plant 58

Furnaces and Industrial Combustion 60

Furnace Off-gas Recovery Plant 61

Rotary Heat E xchangers 62

Dust Scrubbers 64

HOWDEN KNOW HOW

Content for Knowledge and Information Section

Fan Blades 31

Fan Design 33

Fan Laws 35

Fan Power & Speed 37

Fan Choices 39

Fan Stall 41

Fan Noise Levels 43

Fan Systems 45

Compressors 47

Acoustics 49

Compressor Assessment 51

Fan Bids 53

Fan Maintenance 55

Fan Increasing Output 57

Fan Pressure 59

Rotary Air Heater Bids 60

Rotary Air Heaters 63

Rotary Air Heater Elements 65



30

HOWDEN OFFERS A WIDE RANGE OF CUSTOM DESIGNED CENTRIFUGAL FANS TO PRECISELY MEET THE

APPLICATION REQUIREMENTS OF THE MOST DEMANDING SPECIFICATIONS, INCLUDING MAIN SURFACE

FANS FOR MINES.

Our scope of supply can extend to complete turnkey

installations that comprise civil works, high voltage

equipment, electrical panels, acoustic components,

instrumentation and telemetry.

Various output control methods a re offered to

provide our customers with flexible and efficient

performance. These output control methods

include inlet radial vanes, inlet louvre dampers

and variable speed drives. In the instances where

variable speed drives are required, we can provide

a complete fatigue analysis and life estimate.

Proprietary Howden rotor dynamics software

allows for the precise calculation of forward whirl

and reverse whirl critical speed margins, taking into

account the stiffness of every single element in

the rotor support system.

In addition to conventional bearing types, we

can offer specialised bearing designs such as

multi-lobed sleeve or pressure fed sleeve bearings.

This enables our designers to optimise the b earing

selection for every application. Shaft seals are

custom designed to accommodate the most

demanding requirements for seal effectiveness,

and can include double carbon ring typ es with

air or inert ga s sealing and purging. Mechanical

type and gas tight water seals can also be provided

for hazardous fluid applications.

Impeller designs offered include radial, radial tip,

laminar backward curved or inclined, and a range

of aerofoil blade types. All blade designs can be

fitted with wear protection to suit the application

requirements.

Howden centrifugal fans are manufactured using

the latest technology and materials to ensure

structural integrity and strength, fatigue, corrosion

and erosion resistance. All fans are constructed in

accordance with the Howden design rules which

we have evolved and refined over many decades

of industry experience.

Materials ranging from high tensile steel to titanium

and duplex stainless steels and composites can be

used. Specialised coatings and hardening processes

result in fans that are rugged, reliable and efficient.

HEAVY DUTYCENTRIFUGAL FANS



31

BACKWARD CURVED BLADES

A highly efficient shape, which is inherently strongand can carry liners if required.

BACKWARD INCLINED BLADES

An efficient and strong shape, which is simpler

to manufacture than the backward curved blade,

particularly when linered.

AEROFOIL BLADES

A highly-efficient design, used primarily for wide

impellers with large inlets.

RADIAL BLADES

A relatively low effi ciency, mechanically-strongdesign used in high dust environments. The radial

blades can carry heavy liners and dust cannot

become trapped on the underside of the blade.

BACKWARD INCLINED FORWARD

CURVED BLADES

This design combines good efficiency with a

resistance to dust fouling the underside of the blade.

HOWDEN KNOW HOW

FAN BLADES

CENTRIFUGAL FAN BLADE TYPESVirtually all Howden centrifugal fans have backward inclined blades as this is inherently the most efficient

aerodynamic design. Some are flat and others are curved and the suitability of a pa rticular shape is defined

first by the aerodynamic duty and then by the application.

HOWDEN PRODUCTS



32

MEDIUM DUTYCENTRIFUGAL FANS

HOWDEN OFFERS A WIDE RANGE OF CUSTOM ENGINEERED CENTRIFUGAL FANS TO SATISFY THE NEEDS

OF A DIVERSE RANGE OF APPLICATIONS.

These fans differ from the heavy duty range in that,

being smaller and lighter, they can be pre-engineered,

and as such are a more cost effective solution for

many mining applications. Our scope of supply can

extend to complete turnkey installations that include

civil works, high-voltage equipment, electrical panels,

acoustic components, instrumentation and telemetry.

Various output control methods are available to

achieve flexible and efficient per formance. These

output control methods include inlet radial vanes,

inlet louvre dampers and variable speed fans. For

variable speed drives, we can provide a complete

fatigue analysis and life assessment.

Bearings are normally rolling element typ e.

Shaft seals are custom designed to accommodate

the most demanding requirements for seal

effectiveness, and can include double carbon

ring types with air or inert ga s sealing and purging.

Mechanical type and ga s tight water seals can

also be provided for hazardous fluid applications.

Impeller designs offered include radial, radial tip,

laminar backward curved or inclined, and a range

of aerofoil blade types.

Howden centrifugal fans are manufactured using the

latest technology and materials to ensure structural

integrity and strength, and resistance to fatigue,

corrosion and erosion. All fans are constructed in

accordance with our design rules, which have

evolved over many decades of industry experience.



33

UPGRADING FANS –DESIGN CONSIDERATIONSAll fans are designed, manufactured and tested to a

standard that achieves the customer’s specification

in terms of pressure, volume, absorbed power etc.

However during the lifetime of the fan the

requirements sometimes change. To upgrade

fans, the following is relevant:

EROSION

Consider change to liner or hard-surfacing if

erosion is excessive

CORROSION

An alternative impeller material will improve

availability if corrosion is excessive

FOULING

Excessive fouling will unbalance the impeller leading

to excessive vibration. Different blade shapes and

impeller types offer a solution to fouling.

BEARINGS

Considering a change to sleeve bearings is worth

noting if there is excessive maintenance on existing

roller element bearings.

UPGRADING FANS

REDUCING NOISE

Identifying the source of noise is a complex task in

a real plant environment. Measurements may be

affected by other noise sources or by reflections

from nearby surfaces. Experience counts a great

deal in making noise measurements. If a fan has

been identified as the source of high sound levels

then the next s tep is to identify where the noiseis coming from.

INLET/DISCHARGE

Silencers can be fitted in the inlet or discharge

ducting, and are effective at reducing noise

emissions. There is however a penalty to pay in

the fan power a ssociated with the pressure drop

only suited for clean applications. If there is a

significant amount of dust or moisture in the gas

stream then dust may accumulate in the plate

perforations and absorptive material and result

in a rapid deterioration of attenuation. In that case

a reactive silencer is the more suitable option.

FAN CASING

Insulating the fan with absorptive material can

reduce noise emanating from the fan ca sing.

SHAFT SEAL

What may at first appea r to be noise transmitted

through the casing could in fact be escaping

through the seal between the fan shaft and casing.

Repairing the seal or fitting a more effective one c an

reduce noise round the fan significantly.

FLEXIBLE JOINTS

The flexible joints between the fan casing and

ducting can be an acoustic weak p oint. Noise can

be reduced either by fitting new joints made of a

material which has better attenuation properties.

The most ef fective joints incorporate a flow liner,

bolster and a flexible fabric as the outer layer.

STANDARD FAN RANGE ORCUSTOM ENGINEERED FAN?Many medium industrial fans available today are

selected from standard ranges of pre-engineered

designs and sizes. The manufacturing process

economies resulting from the limited engineering

and design requirements for standard fans aresubstantial, and allow the cost of manufacture

and delivery period to be greatly reduced.

The concept of a pre-engineered standard fan range

may lead to technical compromise in the interests of

maintaining a ‘standard’ product. Applications that

are unusual, or are critical to plant operation, should

be subjected to careful ex amination.

The compromises that have been built into the

pre-engineered fan can include high power

consumption, mechanical unreliability, e xcessive

noise and sensitivity to out of balance forces that

will result in frequent and costly nuisance trips. A

custom engineered fan ensures that every elementof the unit is precisely designed and optimized to

meet detailed specifications for stress, corrosion,

erosion, equipment life requirements, safety and

material properties.

The design of fan shafts takes into account the

stiffness of all elements of the rotor support sy stem,

including the client’s foundations. This ensures that

the rotor is not sensitive to ou t of balance forces.

A detailed impeller stress analysis is carried ou t

to ensure that safety considerations are satisfied.

This includes fatigue analysis to ensure adequate

stop/start cycles for the proposed operating

regime. Material selections and weld proceduresappropriate for the application. Bearings are

selected to suit the exact requirements for

each application.

HOWDEN PRODUCTS

HOWDEN KNOW HOW

FAN DESIGN



34

ADJUSTABLE PITCHAXIAL FLOW FANS

A FIXED OR ADJUSTABLE PITCH AXIAL FLOW FAN OFFERS A COST EFFECTIVE LOW-MAINTENANCE

SOLUTION IN APPLICATIONS WHERE FREQUENT FLOW CONTROL IS NOT REQUIRED. TYPICAL

APPLICATIONS INCLUDE MINE VENTILATION AND FUME EXHAUST FANS.

Howden fixed pitch axial flow fans combine the

proven technology of high efficiency Howden

blade designs with aerodynamically optimised

inlet and discharge geometry to give exceptionally

high operating efficiencies.

Blade pitch can be adjusted when the fan is stopped

to take account of changing process conditions.

It is vitally important in the purchase of a manually

adjustable axial fan that the range of possible

operating conditions is considered carefully. We

understand that it is especially important to decideon the maximum operating point so that the fan’s

motor size is selected to cover all operating

conditions up to that point.

Our fans are designed individually to meet each

specification and are supplied as a complete

package with all necessary accessories including:

• Shaft top connector or portal connecter

(for mine ventilation)

• Drive including motor and controls

• Parallel fan system, including adaptor

to vent shaft

• Flow measurement system

• Stall warning and/or prevention systems

• Vibration, temperature and pressure

measurement

• Silencers and insulation.



35

THE FAN LAWSThe performance of a series of geometrically similar

fans (ones which have all leading dimensions in the

same proportions) is related by a relatively simple

series of equations.

• Flow is proportional to diameter cubed and

to speed

Qα D3 N

• Pressure is proportional to density, diameter

squared and to speed squared

Pαρ D2 N2

• Power is proportional to the combination

of these two

Wαρ D5 N3

The sound power generated by a fan (Lw) is

proportional to diameter, speed and density

as indicated by the following formula

Lω α70 log D + 50 log N + 20 log p

These laws are used to predict the performance of

a full size fan from a set of model test results. They

can also be used a s a rough guide to estimate the

performance resulting from a modification to a fan

on site.

SYSTEM RESISTANCE LAWS

When air is moved through a ducted system, the

energy transferred to air by the fan is progressively

lost by:

• Friction of the air against the ducted walls

• Turbulence at bends, dampers and changesof duct section

• Through heaters, filters or other items of

equipment in the system.

The loss of pressure due to all these sources, known

as the system resistance, is for all practical purposes

proportional to the square of the velocity at the

point of the loss.

Therefore, for a fixed sys tem, it may be said that the

pressure (p) required to pass a given volume of air

(Q) through the system will vary a s the square of

the volume flow rate, i.e. p Q2. This means that,

for a fixed system, the greater the airflow, the morepressure is required. Hence, to double the airflow,

four times as much pressure has to be produced

by the fan.

For example, if the initial flow rate is 6m3/second at

a pressure of 3kPa and it is required to double this

to 12m3/second:

p1 = (Q

1)

P2 (Q

2)

P2 = P

1 (Q

2) i.e. P

2 = 3 x 12 = 12kPa

(Q1) 6

This is true only for a fixed system and a constant air

density. Should the system be altered (for example

by closure of a damper), the above laws do not

apply directly.

OCTAVE BANDSA fan generates noise over a wide range of

frequencies. It is important to know how the power

or pressure level is spread over this range to predict

accurately the sound propagation. By convention

the frequencies are divided into octave ba nds which

range from 31 to 16000 and the power or pressure

in each of the bands is measured or calculated

separately. A total sound or pressure level can then

be obtained by logarithmically adding together the

values in each of the frequency bands. Two fans

generating the same total p ower will sound entirely

different to a listener if the energy is spread

differently over the octave bands. To take account

of this the ‘A weighted’ scale has been devised to

simulate the sensitivity of the human ear.

Corrections to each octave band, below, are

applied, and then the resultant levels are totalled

logarithmically to give and ‘A weighted’ total in dBA.

FAN SHAPE/OUTPUTAerodynamically any impeller type (shape) can be

designed to perform any duty. However, mechanical

considerations will dictate that each fan ty pe is most

suited for a particular combination of flow and

pressure.

Centrifugal impellers are most suited to low specific

speed duties i.e. lower flow to pressure ratio. A

narrow impeller is an inherently strong impeller

design, which can run at ver y high speeds

producing the greatest pressure rise. Wider

impellers can produce more flow but mechanical

stresses limit the speed and thus the pressure rise.

Axial fans tend to be suited to higher flow relative to

pressure i.e. higher specific speed duties. Mixedflow is historically selected for an intermediate

range, but there is a considerable area of overlap.

HOWDEN PRODUCTS

HOWDEN KNOW HOW

FAN LAWS



36

AUTO VARIABLEPITCH AXIAL FLOW FANS

A VARIABLE PITCH AXIAL FLOW FAN OPERATES AT HIGH EFFICIENCY OVER A WIDE RANGE OF DUTIES

PROVIDING A COST EFFECTIVE SOLUTION IN APPLICATIONS WHERE THE FAN OUTPUT MUST BE

CHANGED FREQUENTLY TO MEET THE NEEDS OF THE PROCESS.

Howden introduced the first variable pitch axial

flow fan for power generation in 1951. Since then

the company has manufactured more than 2500 VP

axials ranging from 100 to 12000 kW and from

1000 mm to 5300mm diameter. Extensive model

testing in the Howden internationally accredited

laboratory, backed up by years of testing in the field

have enabled Howden to develop the most efficient

fans on the market. Modern high-pressure blade

profiles have significantly reduced the size of the

fan needed to satisfy a given duty and can be

retrofitted to existing fans to increase output.Blades can be supplied in a variety of materials,

to suit the operating conditions, in par ticular the

temperature and the type and quantity of dust

in the gas.

A hydraulic control system provides vir tually

hysteresis free flow control and is fail-safe – the

blades will remain in position if loss of hydraulic

power occurs. Howden axial fans are designed to

minimise maintenance. All impeller components

can be serviced or replaced in-situ without

removing the rotor from the fan. Each blade is

balanced individually and can be replaced on site

without rebalancing the complete rotor. A patented

counter rotating blade support bea ring distributes

wear evenly over the full circumference of the race,

greatly increasing the life of this key component.The outlet casing can be rolled away from the fan

to allow access to the bearing assembly.



37

UPGRADING FANS:

REDUCING POWER CONSUMPTION

For many reasons, a fan may be absorbing more

power than it ne eds to perform the required duty.

The fan may be an inef ficient design, it may not be

matched to the system or it may not have the most

appropriate method of flow control.

MORE EFFICIENT IMPELLER

An inefficient impeller can be replaced by a higher

efficiency design, producing the same output with

a lower power consumption. Some mo difications

to the fan inlet casing may be required.

MATCHING FAN AND SYSTEM

If a fan is oversized and is running with inlet vanes

partially closed, a new impeller, providing the

flow that the system needs, will reduce power

consumption.

CHANGE FAN SPEED

Similarly, it may be possible to reduce the fan speedand still provide the flow required when the inlet

vanes are opened up.

REDUCE IMPELLER DIAMETER

(CENTRIFUGAL FANS)

In some cases it w ill be possible to modify the

existing impeller, eg by shortening the blades, to

reduce its output. This can be carried out without

significantly affecting the basic fan efficiency,

therefore the fan can run with vanes fully open,

at peak efficiency.

MODIFY THE SYSTEM

Reducing the pressure drop in the system will

reduce the fan power consumption A thorough

survey of the system (the ducting and other

components such as dampers and silencers)

can in many instances identify improvements

which will reduce the overall resistance in the

system. Ductwork bends in par ticular are a prime

source of pressure drop, and techniques such as

smoothing the curves, installing a set of specially

designed vanes or altering the layout can produce

useful results.

CHANGE FLOW CONTROL

If the fan duty varies regularly then it may be

economically viable to fit a variable speed control

to the fan, though in many cases the capita l costwill outweigh the power savings.

UPGRADING FANS

VARYING OUTPUT

In most applications it is necessary to var y the

output of the fan on a regular, or even continuous

basis, as the nee ds of the process change. There

are a number of ways to do this.

The simplest way to vary outpu t is to use a dampersomewhere in the system. This however is an

extremely inefficient means of output control as

the pressure drop across the damper wastes power.

There is also a risk that the fan could be forced

into stall operation.

SPEED VARIATION

Speed variation is a very effective me ans of

reducing power consumption at lower loads.

VARIABLE SPEED DRIVE

A variable speed motor or turbine allows the fan to

operate at high efficiency at all duties, however the

capital cost is high compared to other alternatives.

HYDRAULIC COUPLING

A variable speed hydraulic coupling allows the fan

speed to change while being driven by a constant speed

driver. However as the fan speed drops slip losses in the

coupling become greater and overall efficiency is lower

than when using a variable speed driver.

BLADE PITCH VARIATION (AXIAL FANS)

Varying the blade pitch of an axial flow fan is also a

very effective way of vary ing fan output. At lower

loads it is not quite as efficient as variable speed

but it is significantly cheaper on large fans.

INLET VANE CONTROL (CENTRIFUGALAND MIXED FLOW FANS)

This is a relatively low cost method of varying output,

but the power consumed is higher that the variable

speed alternative. This method can vary flow over a

wide range but cannot reduce it to zero due to leakage

through the vanes. At high turndown the inlet vane

controls on larger fans will excite high levels of vibration

in the impeller structure that may result in fatigue

damage to the impeller. It is not suitable for applications

with high quantities of erosive dust as the high velocities

over the vanes result in a high rate of wear.

INLET LOUVRE DAMPERS (CENTRIFUGAL FANS)

These work in a similar way to inlet vane control, butare situated in the inlet box rather than the fan inlet.

Inlet louvre dampers are less effective than inlet radial

vane controls but are better suited to applications that

involve high levels of erosive dust as gas velocities are

much lower than radial vane controls.

HOWDEN PRODUCTS

HOWDEN KNOW HOW

FAN POWER & SPEED



38

HEAVY DUTYMIXED FLOW FANS

THE MIXED FLOW (OR AXIAL IMPULSE) FAN IS A COST-EFFECTIVE ALTERNATIVE TO AN AXIAL FLOW

FAN IN SITUATIONS WHERE CAPITAL COST AND RESISTANCE TO EROSION ARE AS IMPORTANT AS

POWER CONSUMPTION.

The impeller consists of curved steel plate blades,

which are welded to a conical hub. This simple

robust impeller is ideal for handling dust-laden

gases at e levated temperatures. Impulse bladed

mixed flow fans are controlled by inlet radial vane

controls similar to those used with centrifugal fans.

This form of control is extremely ef fective, and

allows rapid changes in fan output in response to

process demands. The inherently low velocities

within the impeller result in low wear rates in dusty

environments. As the aerodynamic performance of

the fan is not sensitive to wear on the blade profile,the fan output is not noticeably degraded by

erosion or corrosion, and the fan will maintain high

operational efficiencies over a long period of time

without the need to replace the blades.

If required, the fan can be supplied with a passive

stabilizing chamber which modifies the fan

performance characteristic, and eliminates the

stall characteristic. The aerodynamic design of the

stabilising chamber can be adjusted to allow the

available pressure at low flow to be controlled to

suit specific process requirements. Howden has

supplied a large number of mixed flow fans; up

to 500 0mm diameter, with motor powers ranging

from 350kW to over 9000kW.

The main applications for mixed flow fans are:

• Boiler draught: In situations where dust in the flue

gas precludes the use of an axial fan and where theflows are too high for a double inlet centrifugal fan.

• Mine ventilation, where its compact, robust design

can be the most technically effective for primary

ventilation and underground booster applications.



39

Pressure(kPa)

Flowm3/sec

100

100 100010

10

5

1

Centrifugal

Axial

Mixed Flow

AXIAL, CENTRIFUGALOR MIXED FLOW FANThe choice of fan type for any par ticular duty has

necessarily to address issues beyond those of impeller

type as the operating range of centrifugal fans by

example, largely envelops axial and mixed flow.

CENTRIFUGALCentrifugal fans can handle a wide range of volume

and pressures. As volume increases pressure

decreases due to mechanical design limitations of

the impeller (larger diameter, wide fans, have lower

maximum tip speeds). Fan geometry is flexible

allowing for double inlet with wide impellers and

aerofoil blades to maximise ef ficiency. Where larger

pressure rises are needed narrow impellers with

longer blades are available. Generally a fan should

be selected at a s fast a speed a s possible to reduce

size and capital cost, however centrifugal fans

running at a slower speed may give a better

efficiency. Where erosion of the fan blades due

to dust burden is a problem the slower running

centrifugal fan is best.

AXIAL

Axial fans are able to handle large gas volumes at

lower pressures. Maximum rotational speeds higher

than centrifugal fans and only limited by centrifugal

load on the blade support bearings. Gen erally larger

volumes have the largest hubs and each hub size

can be fit ted with various lengths of blades. The hub

speed sets the pressure rise and the blade length

determines the volume flow. Two stage axial fans

develop higher pressures but at an increased ca pital

cost. Aerofoil blades and auto-variable pitch control

enable performance over a wide range of duties

at high efficiency. Best suited to clean gas

environments, but will operate in moderate

dust environments if fitted with s teel blades.

Not suited to ‘dirty’ gases.

MIXED FLOW

As the name suggest s combines the features of an

axial and a centrifugal fan, although the impeller

looks more like fixed bladed axial type. Efficiency

can match other types of fan, within its optimum

operating envelope. Impeller design is robust and

the plate blades are ideal for handling dust laden

gases at elevated temperatures. Fan performance

is less degraded by erosion or corrosion, and the

blades are easily weld repaired.

HOWDEN PRODUCTS

HOWDEN KNOW HOW

FAN CHOICES



40

AUXILIARY ANDPORTABLE FANS

AS PART OF OUR COMPREHENSIVE FAN OFFERING TO THE MINING INDUSTRY, HOWDEN HAS A RANGE

OF LOW AND MEDIUM PRESSURE/VOLUME MINE AUXILIARY AND IN-LINE JET FANS FOR TAKING FRESH

AIR WHERE IT IS NEEDED MOST ON A MINE, THE WORKFACE.

Our auxiliary fans are designed to convey air at flow

rates of up to 26m3 per second, and are available in

two, and four-pole design configurations.

Four-pole fan technology has been employed to

develop a hard-wearing, robust fan that overcomes

the drawbacks of traditional auxiliary mine fans.

Howden auxiliary fans therefore offer increased

bearing life and lubrication intervals and better

maintenance performance, lowering fan operating

costs and reduced fan inventories result. As

standard supply, noise levels are reduced to

within 16dB(A) SPL, without the ne ed for

silencing equipment. Depending on the customer

requirement, our auxiliary and jet fans can be

mounted on skids for excellent por tability.

Applications:

• Return air ducting

• Brattice wall boosting

• Cooling car forced draught.

RKFACE.

ught.



41

STALL PREVENTION AND MITIGATIONAll high efficiency fans exhibit an aerodynamic

stall. As the fan is throttled back i.e. as the system

resistance increases a point will be reached where

flow separates from the blades and stall occurs.

When a fan is in stall, the blades a re shaken.

Axial fan blades are only supported at one end,

so are inherently fl exible, resulting in excessive

blade vibration and eventual b lade failure at the

blade root.

For centrifugal fans the blades are much stiffer and

stronger, due to being suppor ted at both en ds, so

stall is not as severe a problem. The main exception

is paddle bladed fans, which, like mixed flow and

axial fans, have the blade only supported at one

end, so will more readily fail in stall. Regardless of

the integrity of the impeller, stall will induce high

duct vibration increased noise. It has been known to

lead to duct and silencer failure due to weld fatigue.

Stall prevention starts at the fan selection stage:

Avoid selecting too large a fan for the app lication

as may result in operation in the undesirable part

of the fan curve where stall and surge can occur.

Better select a higher class of fan that can be run

at a higher speed should the system resistance

calculation be in error. On variable pitch axial fl ow

fans, reducing the blade angle and increasing the

speed can help avoid stall. An anti-stall impeller

casing can be fitted to axial fans on the suction

side of the impeller in order to absorb and turn

the turbulent airflows produced at the tips of the

blades when the fan is operating in the stall area.

Alternatively, stall monitoring devices can be fit ted

close to the blade inlet to register the pressure

difference in the airflow. These can be used to send

an alarm signal to a control room b efore the fan stalls

or activate a control device which, in connection

with variable blades, will automatically get the fan

out of the stalling condition.

HOWDEN PRODUCTS

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FAN STALL



42

COOLING FANS

HOWDEN’S COOLING TOWER AND DRY COOLING FANS ARE SUITABLE FOR USE ON LARGE BOILER

HOUSES AT MINES AND ON PROCESS PLANTS.

Whether they are used for wet or dry a pplications,our well-specified and engineered fans produce a

combination of performance and efficiency for the

lifetime of project for which they are designed.

Howden cooling fans provide the highest flow

of air, and also maximise energy ef ficiency.

Modern fan selection software is employed to help

determine the correct shape and rotational speed of the

fan blades necessary to produce more pressure, and

therefore a better flow of air, be it for dry or wet cooling.

All fan systems a re matched to individual

applications. Where Howden cooling fans are

prescribed for use in wet or hostile environmentsin which blades are exposed to aggressive attack

by fluorine compounds, a low-porosity material

is applied to blade surfaces to improve their

durability. These fans have significant advantages

over alternative materials used for fan blades,

for instance aluminium, which corrodes and pits

in environments with exp osure to acid water.

Each of our fan types has its own uniquecharacteristics in terms of efficiency, noise

levels and areas of use.

E-SERIES

This is a classic straight aerofoil fan with a highly-

efficient impeller and/or low noise. This is the most

widely-used fan in the range and it is available in

three different blade profiles:

• ENF – low noise

• ELF – extra low noise

• ELFA – designed for clockwise rotation

in the horizontal or vertical planes.

K SERIES

K Series axial fans are designed for use in factory-

assembled cooling towers and air-cooled heat

exchangers, with superior performance at lowest

power consumption and with time-saving features.

Fan blades with the innovative Howden-patented

“Aerotip” and the radius-cut inboard edge; havebeen designed for a high power recovery, providing

excellent aerodynamic performance.

SX SERIES

Howden SX axial cooling fans are among the best

low-noise fans available for use in evaporative cooling

systems and ventilation systems where strict fan noise

levels apply. Their specially-shaped aerofoil shape is

designed for ultra-low noise applications for clockwise

rotation in the horizontal or vertical positions.

Z SERIES

Z Series axial cooling fans are the latest in axial

fan development, being specifically designed to

operate at peak efficiency at the most common

duty points in field e rected cooling towers and

air-cooled steam condensers. They include

Howden’s innovative, patented “Aerotip” blades

which enhance the aerodynamic performance

and significantly reduce the “pressure pulse”

transmitted to the fan ring.



43

NOISE LEVELS AND MEASUREMENTAt noise levels in excess of 75dB, noise significantly

impedes communication, causes stress and can

cause permanent mea surable hearing damage.

However, the acceptable noise level is a

compromise between the effect of the noise

and the cost of reducing it. Currently in industrial

environments 85dBA is seen as the ma ximumacceptable noise level.

Noise is seen to act over time, so 85dBA is the

maximum for an eight-hour day. For shorter times,

higher noise levels are acceptable, each halving

of the time increasing the acceptable level by 3dB.

For a two-hour period an acceptable level would

be 91dBA. This can be referred to as 85dBAeq.

The location for mea suring industrial noise is

1m from a machine surface. This should be where

people are expected to work.

For environmental noise the acceptable levels are

much lower. Higher noise is acceptable during the

day because the overall background noise is higher

and people, being more active, pay less attention

to noise. In addition to dBAeq, which is the average

over the sampling time, the time variation of

environmental noise is importan t. This is expressed

in terms of the percentage of the time the noise

is above a cer tain level. For example dBA10 is

the level the noise is above for 10% of the time.

The location for measuring environmental noise

is the plant boundary.

ENVIRONMENTAL EFFECT

For machinery the predicted sound pressure levels

are with the machine placed in an open environment.This is referred to as free field. It is required because

the machine supplier does not know the environment

in which the machine would be placed.

The effect of the environment is very important on

the sound pressure level. It can affect the sound

pressure level by over 10dB. This means that for a

fan with a predicted c asing breakout sound pressure

level of 85dBA the on-site level may be in excess of

95dBA. This is because of:

LOCAL EFFECTS

Against a wall, the noise has 50% of the original area

to escape through giving a 3dB increase in sound

pressure. Against a corner, the noise has only 25%

of the original area to escape through, giving a 6dB

increase in sound pressure.

GLOBAL EFFECTS

This depends on the size of the machine relative to

the room it is in and on the sound absorption in the

room. A large machine in a small room with hard

walls would have a much higher sound pressure

level at 1m than the same machine in free field

conditions.

Some end users get round this problem by assumingan environmental factor of 5dB, requesting that

equipment meets 8 0dBA free field. In addition to

the manner sound propagates in the environment,

there are other noise sources. A t ypical installation

has two of the same machines located side by side.

This gives a 3dB increase in the sound pressure. Of

greater importance to fans is duct breakout noise.

Due to the large area of duct in typical applications,

this can be the dominant noise source and can give

high noise at areas remote from the fan.

MEASURING NOISE

There are two types of instrument s for measuring

machinery noise. Standard microphones measuresound pressure and are good where the machine’s

direct noise is dominant (i.e. no more than 3dB

below the total noise). Sound intensity microphones

measure the amplitude and direction of sound

pressure and are good w here the machine’s direct

noise is at least significant (i.e. no more than 10dB

below the total noise).

The bigger the machine and the more accurate

the result required, the longer the test will take.

Environmental noise is normally measured at

one location with the sound meter lef t running

for between one hour and eight hours to get

a statistical measure of the noise.

HOWDEN PRODUCTS

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FAN NOISE LEVELS



44

ELECTRICAL, INSTRUMENTATIONAND CONTROL SYSTEMS

HOWDEN OFFERS TURNKEY ELECTRICAL CONTROL AND AUTOMATION PRODUCTS THAT ARE

ENGINEERED FOR THE CUSTOMER’S PROCESS SPECIFICATIONS. WE MANAGE THE COMPLETE

AUTOMATION OF LARGE PROJECTS, FROM THE TENDER STAGE, THROUGH TO FINAL COMMISSIONING.

Besides automatic electrical control and

instrumentation systems for new plants, these

systems can also be retrofitted to existing plants,

or existing systems can be upgraded.

Howden has ex tensive experience covering

combustion systems, fans, fabric filter plants, dust

control, scrubber plants, waste gas extraction

systems, automated wire paten ting lines, (including

lead treatment and galvanising baths) automated

aluminium solution treatment and a ge hardening

furnaces, combustion systems for sinter plants,

carbon baking furnaces and incinerators.

All electrical and instrumentation projects a re

executed with a pe rsonal touch, regardless of

size and value.

MOTOR CONTROL EQUIPMENT

Supply, install and engineer Motor Control

Equipment (MCCs) for all types and equipment.

Capabilities include MV and LV turnkey systems.

Containerised systems for remote locations are

engineered and supplied as per customer needs.

FIELD CABLING

Supply, install and engineer electrical and

instrumentation cabling to local electrical

standards, and certificates of compliance testing

are submitted by H owden for all installations.

PROGRAMMABLE LOGIC CONTROLLER

SYSTEMS

Howden’s in-house programmers design

Programmable Logic Controller (PLC) software

for the major types and brands of PLC and SCADA

systems. PLC panels, complete with PLC systems,

are supplied and designed.

FIELD INSTRUMENTATION

Fit-for-purpose instrumentation is designed,

supplied and installed on all projects as per

customer requirement.



45

MATCHING THE FAN TOTHE SYSTEMFan performance, which is defined as the possible

combinations of flow and pressure that a given fan

can produce can be graphed, conventionally with

flow on the horizontal and pressure on the vertical

axis. The characteristic of the system, which in most

cases takes the form of a parabola where pressure isproportional to the square of the flow, can also be

drawn on this graph. The point where these two

curves intersect is the only one at which the fan can

operate with this system. To vary to flow of gas in

the system, either the fan characteristic or the

system characteristic must be altered.

The fan characteristic can be changed by

techniques such as:

• Varying the speed,

• Using an inlet control device such as inlet vane

control or by

• Varying the blade angle (axial flow fans).

System changes are most commonly carried outby adjusting dampers or by changing a feature of

a system. If the system resistance changes over

time, or has been incorrectly calculated then the

performance of the fan will change. A higher

resistance will result in lower flow, and if high

enough could put the fan into stall. A lower

resistance will result in greater flow and

increased shaft power.

HOWDEN PRODUCTS

HOWDEN KNOW HOW

FAN SYSTEMS

F a n S t a t i c P r e s s u r e k P a

0

0

1

2

3

4

5

6

20 40 60 80 100 120 140 160 18

Fan Operating Point

Fan OutputCharacteristicat 100% Speed



46

COMPRESSORS

HOWDEN HAS A DIVERSE RANGE OF TOP-QUALITY COMPRESSOR PRODUCTS AND SYSTEMS WHICH

HAVE BEEN DEVELOPED TO CATER TO DIFFERENT INDUSTRY AND PERFORMANCE REQUIREMENTS.

We are therefore well-placed to support several

mine-focused practices, including Underground

Coal Gasification (UCG) processes. Here our

multi-stage high flow a xial compressors are

engineered and manufactured to deliver

combustion air to injection wells prior to

the gasification process.

Howden has also developed a methane gas abatement

solution for coal mines, and some gold mines, where

we supply gas compressors to return collected high

concentration methane gas to the sur face at pressures

suitable for fuelling internal combustion engines, or

for heating and cooling applications.

TURBO COMPRESSORS

The Howden Donkin range of integrally geared,high efficiency single stage turbo compressors

has been developed for use in a broad range

of process applications.

The integration of overhung high efficiency impeller,

precision gears and high stability bearings result in

smooth, minimum power loss transmission.

Pressurised oil lubrication with high integrity

protection systems ensures maximum availability

of equipment.

LOW PRESSURE GAS BOOSTERS

The robust V Series of pressure gas boosters is

designed for fuel gases such a s landfill gas, coke

oven gas, natural gas and propane/air mixtures.

These reliable units have a vir tually infinite life span.

PISTON GAS COMPRESSORS

Howden offers a full range of piston compressors

custom designed to process applications. The

Burton Corblin range provides pressures up to

350bar, flows to 22,000 sm3/hr and powers to

2.5 MW. These small to medium size compressorshave a number of additional features including

complete separation of the product from the

crankcase, purged packing and double distance

pieces for leakage prevention, and lined cylinders

for longevity and corrosion resistance.

Thomassen supply large piston compressors with

drives up to 25MW for special ap plications. These

compressors can be provided with additional

patented features such as the Free Floating piston

technology which considerably increases the life

of piston rider and compression rings.

ROTARY COMPRESSORS

The Periflow® gas compressor is a rotary

regenerative compressor that offers the same

performance as low-flow-rate centrifugal

compressors, but at a much lower speed and with

surge-free operation. It is ideal for applications

calling for high pressure and relatively low flow rates.

DIAPHRAGM GAS COMPRESSORS

Burton Corblin diaphragm compressors maintaingas purity during compression with no leakage.

All gases can be handled, including light or heavy,

high purity, rare, toxic, flammable, corrosive,

explosive, and radioactive.



47

TWIN SCREW COMPRESSORSPRINCIPLES OF OPERATIONCompression is achieved by the intermeshing of

two helical rotors contained in a suitable casing.

Figures 1–4 give details of the compression cycle.

The Howden twin screw compressor is a positive

displacement rotary design. As such it has the

characteristics and stability of reciprocatingcompressors but in addition offers par ticular

advantages:

• Reduced physical size

• Fewer moving parts

• Low vibration

• Extended operating life cycle.

OPTIONS

Our compressors have a range of design options.

Typical ones are:

• Twin wall construction with sleeve bearings

• Single wall construction with roller bearings

• Slide valve capacity control from 100% to

10% nominal

• Inverter speed control

• Variable volume ratio

• Superfeed

• Oil cooling

• Liquid refrigeration injection

• Specialist sealing systems.

FEATURES AND BENEFITS

Positive displacement

• Cannot surge. High compression ratios per stage.

Rotary action

• Vibration free running.

• Extreme reliability & on-line availability.

• Smooth gas flow, low pulsation.

• Lightweight foundations.

Stiff action rotors

• Ability to withstand high pressure differences.

No inlet or outlet valves

• Lower maintenance costs.

Compact size & light weight

• Minimal space and foundation requirement,

resulting in low installation costs.

Designed for long periods of continuous running

• Maximum on-line availability.

• Minimal service requirements.

HOWDEN PRODUCTS

HOWDEN KNOW HOW

COMPRESSORS



48

ATTENUATORS

THE HOWDEN FAMILY OF ATTENUATORS OR REACTIVE SILENCERS HAS BEEN DEVELOPED SPECIFICALLY

FOR APPLICATIONS WHERE DUST OR MOISTURE AFFECT THE ATTENUATION PROPERTIES OF

CONVENTIONAL ABSORPTIVE SILENCERS.

This can lead to the accumulation of dust in the

plate perforations and absorptive material, resulting

in a rapid deterioration of at tenuation performance.

REACTIVE ATTENUATORS

Our pure reactive attenuators, based on the

Helmholtz resonator principle, are ideally suited for

operation in contaminated air and gases, especially

where moisture carry-over is a problem.

Within a specifically tuned acoustic chamber, sound

waves corresponding to the tuned frequency are

reflected out-of-phase with the incoming sound

waves, and therefore have a cancelling effect on

each other, reducing noise levels.

With its reactive-dissipative attenuators Howden

has extended this concept to produce a silencer

that attenuates over a wider range of frequencies

that have previously restricted the use of these

types of silencers.

A series of resonator cavities, tuned to the specific

application, attenuates noise over a range of

frequencies. Special materials are available for

corrosive or high-temperature applications.

Compared to an absorptive silencer, life is

extended and maintenance is minimised due

to the lack of light gauge per forated plates and

absorptive material.

REACTIVE-DISSIPATIVE ATTENUATORS

Howden reactive dissipative attenuators extend

the concept further by incorporating absorptive

fill material within the acoustic chambers to w iden

the attenuation range of each cell. The fibreglass

fill is situated out of the air stream, shielding it

from contamination by par ticulate matter.

Contamination of the fibreglass with dust ormoisture can be tolerated with only a minimal

change in acoustic performance.

PURE REACTIVE ATTENUATORS

Features

• Long service life• Non-fouling design

• Minimum maintenance

• Easy cleaning

• Low pressure drop

• Flexibility of design

• Suitable for high temperatures

• Broad attenuation range

• Available in various materials

Applications

• Mine ventilation

• Induced draught fan systems

• Contaminated gas streams

• Saturated gas streams

• Corrosive gas streams

• High temperatures

• Steam vent systems



49

ENVIRONMENTAL NOISEREDUCTIONThe propagation of noise from mine ventilation fans

and exhaust stacks to nearby residential dwellings

will be affected by local meteorological conditions.

The intrusive noise level at the noise sensitive

receiver will fluctuate due to w ind direction and

atmospheric temperature gradients. These effectsaccount for significant noise level fluctuations at the

receiver. Excursions in predicted noise levels can be

in the order of +10dB (over neutral meteorological

conditions). Additionally, the acoustic character of

tonal noise sources such as vent fans and stacks

creates greater annoyance at residences. These

tones are related to the Fan Blade Pass frequency

and are a focus for ef ficient silencer design.

Performance testing on absorptive silencers fitted

on coal fired boilers has shown a reduction in

attenuation of around 60% after 15 000 hours

operation. Even following costly cleaning, these

silencers seldom return to their original performance.

A reactive dissipative stack silencer can provide aneffective long term performance solution in the

contaminated gas stream and can be tuned to focus

attenuation on the blade passing tones.

The main section of a reactive dissipative stack silencer

are the splitters which comprise a number of chambers,

the depth of which are approximately one quarter of the

wavelength of the frequency the chamber is designed to

attenuate. Sound waves entering these chambers are

reflected with a phase change of 180˚ which partially

cancel the entering waves.

Absorptive material is fitted to the downstream

faces of the elements to broaden the attenuation

characteristics. A pure reactive section at the rear of

the splitters, designed on the Helmholtz resonator

principle, consists of a number of tuned cavities to

enhance attenuation at frequencies below 125Hz.

With this type of device blade pa ssing tones can

be reduced by 30dB.

BASIC ACOUSTICSSound power level is the acoustic energy emitted by

a source such as a fan and is ty pically measured in

Watts (W ). Sound pressure level is the pressure the

acoustic wave generates at a particular point and is

typically measured in Pascals (N/m2).

Sound pressure level is a function of the sound

power level, distance from the source and of the

attenuation between source and measuring point.

Pressure and power are connected by the formula:

W = P2 . A

ρC

W = Sound Power Level/Watts

P = Sound Pressure Level: Pa

A = Area of Sound Wave: m2

ρ = Gas Density: kg/m2

C = Velocity of sound in gas: m/s

The human ear is an extremely sensitive instrument

and can detec t sound pressure levels ranging from

0.0002Pa to 60Pa. The decibel scale has been

devised to make the numbers more manageable.

Firstly a reference level, W 0, is chosen for sound

power (10¯12W). Any other sound p ower level is

ratioed to the reference value, and to reduce the

range of numbers the logarithm to the base 10 is

calculated. As this unit, the B el, is rather large, it

is subdivided into tenths, ie decibels, (dB):

Lw = 10 log (W/W 0) dB

If a sound source doubles in power the decibel level

will increase by 3dB. Similarly, the reference level PO

for sound pressure is 2 x 10¯5 Pa and in this case the

formula is:

Lp = 20 log (P/Pø) dB

If a noise measurement doubles in pressure the

decibel level will increase by 6dB.

OCTAVE BANDS

A fan generates noise over a wide range of

frequencies. It is important to know how the power

or pressure level is spread over this range to predictaccurately the sound propagation. By convention

the frequencies are divided into octave ba nds which

range from 31 to 16000 and the power or pressure

in each of the bands is measured or calculated

separately. A total sound or pressure level can then

be obtained by logarithmically adding together the

values in each of the frequency bands. Two fans

generating the same total p ower will sound entirely

different to a listener if the energy is spread

differently over the octave bands.

The ‘A weighted’ scale has been devised to simulate

the sensitivity of the human ear. Corrections to each

octave band are applied and then the resultantlevels are totalled logarithmically to give and

‘A weighted’ total in dBA.

HOWDEN PRODUCTS

HOWDEN KNOW HOW

ACOUSTICS



50

CENTRIFUGAL BLOWERS

HOWDEN SINGLE AND MULTI-STAGE CENTRIFUGAL BLOWERS SUPPLY LOW VOLUMES OF AIR AT HIGH

PRESSURE, PROVIDING A COST EFFECTIVE, HIGHLY RELIABLE AND EFFICIENT, LOW NOISE ALTERNATIVE

TO A COMPRESSOR.

TYPE RRO CENTRIFUGAL BLOWERS

Type RRO single and two stage blowers are

machined from solid forgings, and the casings are

manufactured from heavy castings to give a strong

rigid construction. They are supplied in a wide range

of corrosion, abrasion and temperature resistant

materials to satisfy specific process conditions, and

can also be supplied to API Standards if required.

High efficiency open t ype radial bladed or backward

curved blade impeller designs are available.

Blowers are fitted with inlet inducer vanes, inlet

radial vane controls and optional variable vanediffuser controls to operate at very high efficiency

over an extremely wider flow range.

The rotor and integral gearbox are engineered

together to ensure that all bearing, stress and

rotor dynamic considerations are satisfied.

Depending on application requirements, anti-

friction bearings or advanced technology tilting pad

thrust bearings and tilting pad journal bearings are

supplied for the high-speed rotor. The complete unit

is composed of blower, gearbox, control panel, drive

motor and integral lubrication unit are skid mounted

for ease of transport and installation.

TYPE RRC CENTRIFUGAL BLOWERS

Type RRC multi stage centrifugal blowers are used

in the mineral processing and chemical industries.

Typical applications include flotation cells, waste

water treatment, fluidising blowers and combustion

air blowers. Directly coupled to two pole induction

motors, they provide a cheaper, more efficient and

quieter alternative to positive displacement blowers.

The blowers incorporate fully-fabricated impellers

and casings. This allows for an extremely wide

range of readily welded materials to be considered

for construction.

The impeller inlets and stationary inlet cones

are machined to ensure optimum aerodynamic

performance, and each impeller stage is provided

with a set of inlet control vanes that provide high

efficiencies over a wide operating range.

The complete blower assembly and drive motor are

carried on a single integral base unit which simplifies

transport and installation.

Maintenance is simplified. These units do not

require any special skills other than those normally

associated with fan maintenance and service.



51

ASSESSMENT OF PLANTThe assessment of compliance of process screw

chillers, ice plants and turbo blowers with specification

can be difficult. Asking some relevant questions, or

considering certain design aspects within an offer,

will assist with the assessment process.

Checklist for Process Screw Chiller Technologies

• Is the evaporator and condenser material

compatible with the quality of water to be used,

and has adequate allowance been made for

fouling factors likely in the relevant application?

• Are the pressure vessels manufactured in

accordance with recognised codes?

• Does the chiller comply with local refrigeration

plant standards?

• Does the compressor have sleeve bearings and

a double-wall casing for long service life and

low noise levels?

• Does the oil tank have both demisters

and coalescing cartridges for optimumoil separation?

• Does the package include dual lube oil systems

that permit standby capacity for emergencies

or allow for on-line servicing?

Checklist for Ice Plant Technologies

• Ice mass fraction to be specified, which is

dependent on the Total Dissolved Solids (TDS)

in the feed water, and the concentration in

the sump.

• Sump blowdown rate will determine the build-up

of TDS and chlorides in the sump.

• Materials of construction for the ice plates willdepend on the corrosiveness of the feed water –

especially the chloride concentrations.

• Cycle time will depend on the defrost system

employed and the mass of material in the

ice-making plates.

• Refrigeration compressors’ absorbed power can

be reduced by employing refrigerant sub-coolers

and/or economisers.

• The ice plant performance coefficient should

include the total system, since looking at system

components only will reflect misleading

efficiencies.

• Is the ice plant contained within an insulated

building to reduce heat gain?

• Is the refrigerant used in the system

environmentally friendly?

HOWDEN DONKIN TURBO BLOWERS

• What is the duty turndown capacity of the blower

to achieve optimum efficiency over the entire

operating range?

• Does the gearbox incorporate a split casing

design to allow easy access to gears and bearings?

• What fail-safe features are incorporated into the

blower lube oil system design?

• Is the blower equipped with a dual oil filter system

for on-line servicing?

• Does the blower design guarantee oil free process

gas delivery, if required by the application?

• Does the blower come with a fully-automatic

PLC based control incorporating anti-surge

features and simultaneous “multi-blower

installation” control?

HOWDEN PRODUCTS

HOWDEN KNOW HOW

COMPRESSOR ASSESSMENT



52

HARD ICE PLANTS &THERMAL ICE STORAGE

THE DEVELOPMENT OF DEEP-LEVEL MINES TO BEYOND 2000M BELOW THE SHAFT COLLAR, AND

A GROWING PRE-OCCUPATION WITH THE COST OF MINE ENERGY, HAS GIVEN IMPETUS TO THE

DEVELOPMENT OF HOWDEN’S TURNKEY HARD ICE AND THERMAL ICE STORAGE TECHNOLOGIES.

HARD ICE

Howden’s efforts to provide cooling to deep mineswhere the efficiency of traditional chillers and bulk

air coolers is compromised has seen us emerge as

the global market leader in the design, build and

installation of hard ice plants.

The scope of work typically includes all civil work,

ammonia compressor plant, ice makers, cooling

towers, ice conveyors and the electrical and control

system to deliver hard ice to the mine shaft.

Our plate ice technology can be used with normal

mine service water to produce ice with an Ice Ma ss

Fraction (IMF) of up to 98%. Howden oil injected

screw compressors are used with environmentally-

friendly ammonia refrigerant to provide the icefreezing capacity, and a de-superheated hot ga s

defrost cycle is used to release the hard ice.

The ice is transported underground in HDPE pipes

and is utilised in underground melting dams, with

the very cold water being distributed to the various

cooling stations with resulting enhanced thermal

performance of underground Bulk Air Coolers

(BACs) and spot coolers.

The overall cooling system energy efficiency of a

hard ice plant exceeds that of a chilled service water

cooling system; primarily due to the saving in return

water pumping energy (hard ice has a cooling

capacity four times greater than water, resulting in

a large reduction in return water to be pumped back

to the surface). The reduction in required pumping

capacity also reduces distribution infrastructure

and shaft space requirements.

THERMAL ICE STORAGE

Howden can supply ice-making technology with

which either “ice water” or “solid ice” is produced

as required during any specific 24-hour p eriod,

making major power and demand savings possible

when it is used in combination with good water

management systems.

The water management philosophy, including ice

melting, storage, and ice and ice water blending,

can be structured to allow the entire mine

refrigeration plant (excluding the pumping of the

chilled water) to be stopped during a power peakdemand period per week.

Our plant will run at maximum load at all times

thus delivering complete efficiency. As the system

is designed as a standalone operation, it will not

reduce dam storage volumes, and can operate

even if the main cooling plant is out of operation.

Minimal additional pumping costs are required.

Safety is an integral part to the design. All the

icemakers are above water level and can be

individually isolated, thus ensuring the system

is safe. Icemakers are also grouped in modules

which can be isolated if necessary, for both

safety and service reasons.

Our plant typically consists of an ammonia screw

compressor and modular ice water maker, but

could also include submerged coils for hard ice

production. A typical modular size plant is

designed to deliver about 5MWR per unit.



53

FAN BID ASSESSMENTBids received from a number of suppliers can seem,

at first sight, to be indistinguishable. Asking a

number of simple questions can help to ensure that

the fan bids all comply with the specification.

LAYOUT

• Does the fan inlet and discharge cross-sectionmatch the ductwork, or must a transition piece

be supplied?

• If there is a bend in the ductwork close to the

fan discharge it may significantly affect the fan

performance. Has that been factored in?

DUTY AND PERFORMANCE

• The upstream ducting layout may affect the

fan performance. Has this been assessed?

• Has the same definition of fan pressure been

used? ‘Fan total pressure’, ‘fan static pressure’ and

‘static pressure rise’ are all different quantities.

• What is the margin between motor name-platerating and fan absor bed power? If it is too small

there may be insufficient safety margin. If it is too

large it may indicate that the supplier is unsure of

the fan’s performance.

There are a number of different ways in which fan

efficiency can be specified, so it is better to assess

fans on the basis of shaft power.

• Is there enough reserve between the operating

point and the fan peak pressure point to allow

some increases in fan system resistance?

• Is the fan operating in parallel with another one

or more? If so can the fans start up with all the

others running?

• Is the performance based on an international

standard?

FAN SELECTION

• Is the blade shape suitable for the application?

• Does the erosion protection, if used, match the

dust type and quantity in the air or gas stream.

• Inlet control – Are the vanes in the eye of the fan,

where they control flow more efficiently, or in the

inlet box where they will wear less if there is a

significant amount of dust in the air or gas stream.

• Has the manufacturer supplied a fan of this size

and speed before?

• Fans which operate at very high temperatures

may require special materials with acceptable

creep rupture properties.

• Has the predicted number of stop/starts been

factored into the mechanical design?

• Fan speed. In dusty conditions too high a speed

may reduce fan life considerably.

• What is the margin between running and first

critical speed of the impeller

• Has the support and foundation stiffness been

factored into the critical speed calculation?

HOWDEN PRODUCTS

HOWDEN KNOW HOW

FAN BIDS



54

DUST COLLECTION ANDFLUE GAS CLEANING

HOWDEN BOASTS A SELECTION OF DRY DUST COLLECTION AND SCRUBBER TECHNOLOGIES WHICH

CAN BE EMPLOYED AS SPECIFIED BY THE CUSTOMER.

Most of our gas cleaning systems are supplied

on a turnkey basis, and include design and detail

engineering, supply and manufacture, electrical

control and instrumentation, plant erection,

commissioning and handover to the customer.

Howden’s engineers also provide technical advice

and support on the technologies and systems

needed for individual ap plications. Whichever

solution is selected, our gas cleaning systems are

designed to meet the most stringent requirements:

• Compliance with relevant environmental legislation

• Cost effective, efficient solutions

• Minimal space requirements

• Low maintenance

• Energy efficient

• Minimal water requirements.

DRY DUST COLLECTORS

Howden can supply mechanical dust collectors or

fabric filter solutions, depending on the application

requirement.

MECHANICAL DUST COLLECTORS

Mechanical cyclone collectors represent the

most simple and economical method of dry

dust collection, and we can offer the mechanical

collector best suited to the customer’s operation.

Howden mechanical cyclones and multi-cyclones

are designed to deliver high and medium efficiencies,

depending on the application for which they

are employed.

In step with modern outlet emission requirements,

our mechanical collectors are used primarily a s

pre-collectors before secondary collectors, for

instance electrostatic precipitators, or before

fans in forced draught systems.

FABRIC FILTER PLANT

Our fabric filter plant is suitable for application

requirements where emissions below 10mg /m3 are

required. Two bag filter technologies are offered,

either high pressure reverse pulse jet, or low

pressure reverse flow.

Reverse pulse filter technology is par ticularly

appropriate to applications where space for the

plant is limited, for instance installations betwee n

the boiler and outlet stack of an existing plant.

Cleaning of our reverse flow designs is by means of

a high-volume pulse through a rotating manifold,

which enables a better release of the dust cake,

for lower cleaning frequency and longer bag life.

The reverse pulse jet filter offers high performance

and a low operating cost, making it a popular choicein many demanding industrial applications.

SCRUBBERS

Howden’s wet, dry, and semi-dry scrubbing

solutions are proven options for gaseous emission

and particulate control, and are suitable for use on

high-temperature applications.

A choice of wet scrubbers is available – the

highly-efficient Venturi design, and the lower

energy Cyclonic scrubber.

VENTURI SCRUBBERS

Venturi scrubbers have a particulate collection

efficiency of up to 99 %. They are suitable for

high-temperature processes and applications

with a pressure drop of up to 30kPa.

Howden’s Venturi scrubbers are especially good

for simultaneous gaseous and particulate pollutant

removal when scaling is a problem, and w here there

is a high concentration of dust in the inlet stream.

CYCLONIC SCRUBBERS

These scrubbers have a lower p ower requirement

for removing particulates and gases from the flue

gas stream. They are suitable for pressure drops

of up to 2.5kPa.

DRY SCRUBBING

Dry injection in conjunction with fabric filtration is

an economical, reliable choice for removing low

levels of SO2 and tars in suspension.

GAS COOLINGHowden also offers a range of ga s cooling solutions,

including dilution air, high temperature quench,

radiant and forced draught cooling. These are

supplied as turnkey solutions to customer

specification.



55

BASIC FAN DESIGN AND EFFICIENCYFan design is both an art and a science. Our skilled

and experienced engineers are dedicated to

carefully analysing and solving each industry’s

specialised needs. When designing efficient

impellers, most manufacturers start out by testing

a series of impellers with the aim of producing a

set of aerodynamic shapes that:• Cover the required pressure/volume envelope

• Develop a good efficiency across as wide a zone

as possible

• Are not sensitive to small geometrical changes

• Preferably have a non-overloading power curve

(where the impeller design permits)

• Are relatively easy to manufacture with a

minimum cost (probably the most important

to the manufacturer).

Although it is relatively easy to design an impeller

to satisfy a par ticular pressure/volume duty, it is

difficult to achieve this with a high efficiency whilemaking it cost-effective to manufacture. This means

that one manufacturer’s fan may satisfy the duty

requirements with a much higher efficiency than

another manufacturer’s. The way to save energy

when using fans appears simple – use more efficient

fans. However, it is not that straightforward.

Modern higher efficiency motors have a relatively

flat efficiency curve with load, and improving the

motor efficiency means improving the efficiency

over the whole operating field. The same does not

apply to fans – the efficiency curve is far from

constant and there can be a difference of 30%

between peak and low efficiency in the fan’s

working range. In addition, the energy use of similarfans performing the same duty, but from different

manufacturers, can vary by up to 3 0%. It is therefore

important to select a fan that is operating as near to

its peak efficiency as possible.

Fan specifications should stipulate the use of both

a high efficiency fan and a higher efficiency motor

to achieve maximum energy savings during the

operational life of the equipment. When selecting

a fan and specifying a fan installation, it is also

important to consider whole life costs. These consist

of the initial cost of the fan, energy costs, plant life

expectancy, the cost of maintenance and other

operational issues, and disposal costs.

MINIMISING MAINTENANCEMaintenance is required for fans, even if they are

balanced and operating faultlessly, maintenance is

required. For all larger fans this will include

assessing the impeller structural integrity

(inspection for cracks, excessive erosion or

corrosion), checking and changing the oil.

AXIAL AUTO VARIABLE PITCH

Inspection of impeller, bearings, shaft seals and

control system. Refurbish as necessary.

Replacement of main bearings, blade support

bearings, hydraulic actuator and AVP thrust blocks.

This will not be required at every outage as the

operating life of each of these components will vary

depending on the fan speed and dut y. The Variax

Axial Fan has a number of features to minimise

outage time for maintenance and to allow extended

operation. Each individual blade is balanced and the

blades can be replaced on site without rebalancing

of the complete rotor. The diffuser is mounted on

travel rails and is displaceable. Blade replacement is

possible through an inspection cover in the impeller

casing, and impeller overhauls can be made without

dismantling the fan ca sing.

The blade bearings use oversize balls to create a

larger contact surface and the greater load-carrying

capability extends bearing life.

CENTRIFUGAL



MIXED FLOW



For providing easy access when inspecting the

impeller and main bearing assembly. The impeller

can be inspected from inside the fan, and there is an

access door to the inner tube of the fan diffuser end.

Service intervals can be increased to between 4 and

6 years.

HOWDEN PRODUCTS

HOWDEN KNOW HOW

FAN MAINTENANCE



56

CHILLERS

HOWDEN OFFERS TURNKEY AMMONIA CHILLER PLANT INSTALLATIONS, INCLUDING CIVILS WORK,

PERIPHERAL PLANT, AND ELECTRICAL AND CONTROL SYSTEMS, FOR MINE COOLING REQUIREMENTS.

Our chiller plants are custom designed to thespecifications of each client and can be adapted

to the requirements of individual country or

jurisdic tional requirement s.

Howden chillers are based on the Howden WRV

range of screw compressors, of which more than

20 000 are in service worldwide. They are employed

in conjunction with proven type heat exchangers,

pressure vessels and cooling towers. All pressure

components are built and certified to relevant

statutory and industry codes.

Output control is t ypically Programmable Logic

Controller (PLC) based and integrated with the

overall mine cooling requirement to optimisesystem efficiencies.

Howden chiller plants are designed and developed

in-house, and packaged units are based on simplified

refrigeration processes, thereby eliminating the

need for economisers or gearboxes for duties up

to 9,5MW(R). No refrigerant pumps or refrigerant

pump-out facilities are required and the refrigerationprocess design eliminates the possibility of the

corrosion of the internal components of the plant.

Typical ammonia water chiller performance data for

mine cooling applications, based on an evaporating

temperature of -1,5˚C and a condensing temperature

of 30˚C, are:

Ammonia is an efficient natural refrigerant with

zero Global Warming Potential (GWP) and

long-term availability.

For enhanced safety, Howden ammonia chiller plants

are built to strict industry and statutory codes to

ensure plant safety. Plant design is such that safetyrelief valves should not discharge under any

condition, except possibly fire. The ammonia leakage

detection and emergency shut-down process is

automated, and each plant is sectionalised so that

only part of the ammonia charge is safely released

via scrubbers in the event of catastrophic failure.

BULK AIR COOLERSHowden can supply large horizontal bulk air

coolers (BACs), with capacities of up to 15MWR,

for pre-cooling mine downcast air. Our unique

counter-flow design results in a higher thermal

efficiency and smaller footprint than conventional

cross-flow designs.

Refrigeration

Cap kW(R)

Absorbed

Power kW(E)

321/193 4900 850

321/220 5800 990

365/165 6100 1110

365/193 7200 1300

510/165 8500 1430

510/193 9500 1600



57

UPGRADING FANS:

INCREASING OUTPUT

Throughout the life of a plant it is possible that a

fan will be required to compensate for a change in

operating conditions, perhaps because of a need

to increase process output (greater flow) or due to

changes in the plant layout (greater pressure drop).

Increased output will mean increased absorbed

power and unless the original driver has substantial

design margins built in, it may have to be replaced

with a higher rated machine. Noise generated by the

uprated fan will also increase, roughly in proportion

the increase in shaft power.

INCREASE THE FAN SPEED

Increasing fan speed is a very effective way of

improving fan output. It is however only possible to

increase output in this way if the impeller can accept

the higher stresses. Finite Element Analysis will be

able to assess the basic strength of the impeller and

its residual life operating under the new conditions.

GEARBOX/BELT DRIVE

If the fan already has a gearbox or belt drive

installed, then it is a relatively simple matter to

replace the gearbox internals, or the pulleys with

a ratio which produces the desired fan speed.

Otherwise a gearbox or belt drive will need to b e

installed, provided sufficient space is available.

HIGHER SPEED MOTOR

A new electric motor running at one pole- speed

higher than the existing one will provide a step in

output. This will probably be excessive. However

the fan can be throttled back by the fan control

system to provide the desired output.

MODIFY THE SYSTEM

Reducing the pressure drop in the system could

balance the addition of ex tra pressure drop

elsewhere or allow a fan to produce a compensatory

increase in flow. A particularly important area is the

ducting immediately upstream of the fan inlet. A

layout which induces spin in the ga s flow, or biases

the flow to one side of the inlet can reduce the fan

output considerably.

TIP THE BLADES (CENTRIFUGAL FANS ONLY)

A modification to the blade tips can increase the

pressure generated by a centrifugal fan. This can be

achieved either by increasing the length of the blade

(tipping) or by changing the shape of the blade at

the fan outer diameter (wedging). As impeller

stresses will be increased due to the extra load,

a thorough inspection of the fan and analysis

of its strength must be carried out before any

modifications are made.

REPLACE THE ROTOR (CENTRIFUGAL FANS)

Replacing the rotor with a new one designed for the

new operating conditions can be a cost effective

method of changing output. There is a limit imposed

by the casing on the maximum size of impeller

which can be accepted. Modifications to the casing‘cut-off’ and to the inlet cones will almost cer tainly

be required.

REPLACE THE ROTOR (AXIAL FANS)

Within the bounds of the fan tip diameter, a new

impeller can be fitted to an axial fan with a different

size of hub. A larger hub will increase the pressure

that the fan generates.

INSTALL A NEW FAN

In instances involving a substantial increase in

output a new fan may be the only option. Whilst

expensive, the through life cost analysis will indicate

if the benefits are wor thwhile. The space availablemay dictate that a centrifugal fan can only be

replaced by a centrifugal fan. Although it may be

possible to replace an axial fan with a mixed flow

fan and vice versa.

HOWDEN PRODUCTS

HOWDEN KNOW HOW

FAN INCREASING OUTPUT



58

PORTABLE COOLING PLANT

HOWDEN OFFERS CUSTOM-DESIGNED MINE AIR COOLING PACKAGES READY FOR INSTALLATION,

EITHER AS UNDERGROUND OR SURFACE UNITS.

Each Howden screw compressor is supplied as a

skid-mounted package, precisely tailored to the

requirements of each customer and a pplication,

and including a compressor, compressor driver,

oil separator, condenser and evaporator.

Plant configurations allow for many variations in

design, including single or multiple compressors,

electric motor or gas engine drivers, air or

water-cooled condensers and plate, kettle, shell

and tube, or shell and plate evaporators. The

process chosen will optimise the capital and

power cost within the design parameters.

Howden’s mine air cooling packages are equipped

with the required components and systems, ready

for rapid connection on site.

A complete turnkey service is offered, starting with

initial consultation, commissioning and extending

to full aftermarket care.



59

FAN PRESSURESThe pressure rise across a fan can be defined in

a number of ways.

The most useful definition is Fan Total Pressure

which is the difference between the total pressure

at the fan outlet a nd the total pressure at the fan

inlet. This is Fan Pressure as defined in ISO 5801

for the conditions found in most systems

applications (M<0.15).

Fan Static Pressure is also used. This is the Fan Total

Pressure less the fan discharge velocity pressure.

Historically this has been used when the fan is the

last component in the sy stem and the fan supplier

will control the velocity pressure discharged.

The fan pressure can also be defined as St atic

Pressure Rise. This is the difference between the

static pressure at the fan discharge and the static

pressure at the fan inlet. For this definition to be of

any use the system designer must know what these

areas are as different fan suppliers offer different

geometries for fan inlet and discharge ductwork.

The required Static Pressure Rise will need

adjustment to compensate for any mismatch

between the fan inlet and discharge areas and the

proposed system ductwork.

The total pressure at any point in a flow system is

the sum of the static and velocity pressures. This fact

must be kept in mind whenever static pressures are

specified as any change in flow area will affect the

velocity and hence the static pressure component.

For this reason the use of Fan Static Pressure or Static

Pressure Rise should be discouraged as both are

dependent on the flow passage areas and can lead to

misunderstandings regarding the required fan duty.

VIBRATION MEASUREMENTFan vibration can be mea sured using either:

SEISMIC INSTRUMENTS

These are instruments that measure the vibration

relative to the ground. They are the accelerometers

and velocity transducers among others, and can be

seen attached to bearing housings, or

PROXIMITY PROBES

These are used for measuring the shaft vibration

relative to the housing. Vibration levels for new

machines, alarm and trip can be obtained from the

manufacturer, and all alarm and trip levels should

not be more than the stan dards specify.

Eddy current probes are being applied to fans and

are applied to blowers. They are the only means of

correctly monitoring machines where the bearing oil

film is much softer than the support. Hence they are

predominantly used for machines operating above

300 0rpm. In addition, such probes are sensitive to

local shaft effects such a s out of roundness or evendifferent electrical properties. These effects are

known as mechanical or electrical run-out and

must be taken into account by the v ibration systems

electronic system in an attempt to c ancel their

influence. As such shaft proximity vibration probes

should be treated with caution when applied to fans

running below 1500rpm.

HOWDEN PRODUCTS

HOWDEN KNOW HOW

FAN PRESSURE



60

FURNACES ANDINDUSTRIAL COMBUSTION

HOWDEN MARKETS A WIDE RANGE OF INDUSTRIAL FURNACES AND BURNERS WHICH ARE SUPPLIED

AS TURNKEY PACKAGES DESIGNED TO THE CUSTOMER’S REQUIREMENT.

INDUSTRIAL FURNACESOur industrial furnaces can be supported by all

types of firing – gas, oil or electricity – and can be

supplied as complete systems for general plant

requirements, dependent on the application

and customer specification.

INDUSTRIAL COMBUSTIONBurners suitable for different customer-specified

applications are produced. These include:

Kiln Burners – these systems number a mong the

most fuel–efficient burners of their type available,

and can be designed to fire oil, coal, gas, wood

waste, producer gas or combination fuel.

Producer Gas/Solid Fuel Burner Systems – lowcalorific value gas or any combustible fines c an be

used to replace more traditional fuels. We engineer

total systems for producer gas, blast furnace gas,

agricultural waste fines and sawdust, as well as

pulverised coal.

Air Heaters – Hot gas generation systems for thermal

driers or any application requiring process heat.

HOWDEN KNOW HOW

ROTARY AIR HEATER BIDS

ASSESSING HEATER BIDSWhen assessing heater bids there are key items that need

to be addressed: layout, duty, selection, performance.

LAYOUT

Ensure that the inlet and exit flow profiles maximise

heater performance and ensure good mixing of outlet

gas. A vertical shaft arrangement is preferred in order

to reduce cyclic stress. Give consideration to the need

for more frequent replacement of cold end elements.

Horizontal replacement eliminates the need to remove

intermediate and hot-end baskets.

DUTYThere must always be a reasonable temperature

difference between hot and cold streams for

heat transfer to take place, thus the maximum

temperature of the air leaving the preheater is

limited by the temperatures of the air and gas

entering it. Typically there should be about 20 -25˚C

difference between gas in and air out temperatures.

SELECTION

Howden has a large number of element profiles,

with different characteristics, available for use in

air preheaters. The most appropriate elements

are selected from an optimised range for each

and every application.

Generally it is necessary to control the primary air

temperature to suit varying coals and to control the

metal temperature at the cold end of the preheater to

keep corrosion and fouling within acceptable limits.

PERFORMANCE

Air leakage can be calculated from either the

difference in gas mass flow entering and leaving the

preheater, or from the difference between diluted

and undiluted gas temperatures. Many air preheater

designs develop leakage drift, where air leakage

increases substantially over a period of time. Margins

have to be added to the draught fan duties to account

for this. The advanced VN sealing system supplied

by Howden does not exhibit leakage drift, resulting

in lower fan margins and reduced capital cost.

ROTATING HOOD AIR PREHEATERS

The rotary hood air heater is an alternative to the

Ljungström design. The rotor (stator) is stationary

and the ducts (hoods) rotate to create the alternative

air and gas flows. This requires a multitude of sealing

and movable parts that are prone to wear and

damage unlike the Ljungström design does not needcontact seals between the rotating and stationary

parts, resulting in lower leakage and maintenance.

The rotary design can maintain low leakage but

requires short, frequent skilled maintenance

and replacement spares. Howden companies



61

HOWDEN PRODUCTS

FURNACE OFF-GASRECOVERY PLANT

HOWDEN SUPPLY TURNKEY FURNACE OFF-GAS RECOVERY SYSTEMS FOR PURPOSES OF ENERGY

RECOVERY AND GAS SYSTEM PRESSURE BOOSTING.

The main purpose of an off-gas recovery anddistribution system is to cap ture off-gas from

smelter furnaces and to distribute the off-gas to

various users on the plant. The gas from the furnace

is collected at low pressure and boos ted for supply

to the various users a t their specified required flows

and p ressures.

Our off-gas distribution system utilises liquidring compressors to increase the pressure to the

desired user requirement, where it is used as a n

alternative to fuel gas and electric power, thereby

reducing operating costs. User burners are

equipped to accommodate either fuel gas or

furnace off-gas. Typical applications are the

pre-heaters at each furnace, slag treatment plant

burners, metal treatment burners, or any otherplant burners equipped with dual gas burners.

Due to the potential hazards associated with

carbon monoxide (CO gas), plant design and

control philosophies include safety devices and

operational checks and procedures recommended

for safe plant operation.

manufactured several dozen of these large rotating

hood heaters, and if a total replacement to a modern

Howden Ljungström air preheater is impossible

Howden has the skills and expertise do actively

service, supply spares, upgrade and provide all

“solutions” engineering.

WHEN TO REPLACE ELEMENTSThe decision to replace elements is generally based

on a v isual inspection, which involves identifying:

• Relaxation of elements

• Decrease in thickness

• Overall corrosion and surface loss.

However, as most plants have limited access

to inspect the heater element condition, once

evidence of material loss is seen, accelerating

deterioration will follow, this should be taken

seriously and plans made to replace the baskets

at the next ou tage window, even if there might

be some extra operation hours left.

Deterioration of the elements generally follows

the following pat tern:

Firstly the element plates reduce in material

thickness. Thereafter the profile loses its s tructural

strength that in turn allows deformation of the

element profile and consequently loosens the

original basket compression. The loose plates

vibrate continuously, due to air and gas pa ssing

and soot blowing, which then causes fatigue and

consequently breakouts of large element p latepieces. The breakout process continuously

accelerates which causes more severe vibration

to the point of total basket disintegration.

In addition, cold end baskets often suffer severe

corrosion, which causes, material thinning, cold spot

blockage, fouling and uneven material loss areas.

The subsequently uneven flow and heat exchange

causes reduced thermal efficiency and high flow

volume through low-pressure resistant areas and low

flow volume through high-pressure resistant areas.

Consequently upper element layers and the

surrounding rotor housing and seals experience

premature accelerated high spot erosion and

vibration damage and other upper layer areas

suffer from accelerated cold spot corrosion which

creeps upwards.

In general, boiler operation can adapt to gradualheater thermal efficiency changes within some

limits with the consequence of efficiency reduction.

However, accelerated hot-end damage rapidly

exceeds the limits.



62

ROTARY HEAT EXCHANGERS

HOWDEN IS ABLE TO APPLY MORE THAN 80 YEARS’ OF EXPERIENCE IN AIR PREHEATER DESIGN

AND MANUFACTURE TO BOILER APPLICATIONS RANGING FROM LARGE 500 TON UNITS TO SMALL

5 TON PACKAGES.

This enables us to customise air p reheater solutions

for mines and process plant ne eding to generate

their own power. The result is a compact,

cost-effective and reliable solution for heat

recovery and, where necessary, flue gas

desulphurisation systems.

The design principle of the Howden rotary air

preheater is to allow hot gas to pass through a matrix

composed of multiple metals plates (elements). The

hot gas, usually at a temperature of 350˚C, passes

across the surface of the metallic elements, raising

the temperature very rapidly. As the rotor turns

slowly, typically at one revolution per minute, the

heated elements are transferred into the airside.

Here cold air flows between the spaces formed by

the element plates, extracting significant amounts

of heat and raising the air temperature to 300˚C.

The vast quantity of heat transfer elements required

is of a special form which promotes turbulence in the

gas and air streams to maximise heat transfer without

encouraging pressure drop in the air and gas stream.

We have developed a large range of element s, with

differing thermal and pressure drop characteristics

to match the application. Proprietary Howden

sealing elements are used to separate the air and

gas streams.

When handling large quantities of hot gas and cold

air, this type of heat exchanger is the most efficientand compact available. The reason is that both

surfaces of the element plates are used for heat

transfer simultaneously, with the sam e plates, or

heat transfer surfaces, being used in both the gas

and air side of the rotary air preheater, which

improves boiler efficiency by up to 10%.



63

ROTARY REGENERATIVE VS RECUPERATIVEThere are two main types of preheaters in boilers and steam generators – recuperative and regenerative.

For power plants a nd similar applications, a rotary

regenerative heater will always be significantly

smaller and lighter than a recuperator. The reason

for this is simple. With a rotary regenerative type,

both sides of the heat-transfer plates are used for

active heat-transfer (either heat in or out), and the

same plates are used in both sides of the heater.

With a recuperator, only one side of the tube

surface is used for the heat input, with the other side

only being used for heat output. This means that a

recuperator requires significantly more surface area

than a rotary heater.

In addition, a rotary regenerative type, where the

thermal energy is stored within the mass of the

heat-transfer plates, build-up of dust on the surfaces

will have a minimal effect on the heater’s thermal

performance. This is due to the fact that the dust

has mass and will also store thermal energy in much

the same way that the met al in the heat-transfer

plate will store energy.

With a tubular recuperator, the heat transfer is by

conduction from the outside of the tube to the

inside. That means that the he at transfer will take

place through any dust layer before it can flow

across the tube wall. In this type of heater the dust

will be an additional resistance to heat transfer.

HOWDEN PRODUCTS

HOWDEN KNOW HOW

ROTARY AIR HEATERS

Hot Air Hot AirHot Gas Hot Gas

Cold Air Cold AirCooled Gas Cooled Gas

Regenerative Recuperative

HeatTransfer

HeatTransfer

Heating Elementphysically moved

from air to gas

Heating elementphysically moved

from gas to air

EXAMPLES OF PACKAGE HEATERS



64

DUST SCRUBBERS

ENGART DUST SCRUBBERS NUMBER AMONG THE LEADING DUST COLLECTION SYSTEMS IN THE

COAL MINING INDUSTRY AND IN OTHER ENVIRONMENTS WHERE AIRBORNE DUST IS A RISK TO

HEALTH AND SAFETY.

The range offers an excellent combination of compact,

robust design and economy. Engart can be mounted

on a continuous miner underground, or in a ducted

system on the surface for controlling dust at transfer

points, coal silos or railcar tipping points.

Dust-laden air is drawn into the dust extractor

and mixed with water at the impeller and in the

chamber. The dust/air/water mixture is then drawn

around the motor and then caught in a steel woven

mesh which is continually washed by a multi-nozzle

spray bank. The sludge is pumped away and

dust-free air is exhausted.

Our products are sold and supported by experienced

sales engineers who understand their products and

are qualified to specify, install and service our Engart

systems at site.

Whatever the task, Engart dust scrubbers attain

unsurpassed levels of performance levels. Dust

capture and scrubbing efficiencies of 99% of total

dust are achieved.

Engart dust scrubbers have:

• High collection efficiencies

• Energy efficiency

• Low maintenance costs

• Robust construction

• Ease of operation

• A safe, flame-proof electric motor

out of the air stream

• An anti-spark impeller track.



65

SELECTING THE CORRECT ELEMENTThe satisfactory performance of both rotary air heaters

and gas heaters is greatly dependent upon the selection

and use of the most appropriate design profile of heat

transfer element for the chosen application.

Any particular element profile may appear to have an

excellent combination of performance parameters.

However the mechanical and dimensional integrity of

the element pack must be maintained at the required

level during manufacture, installation and subsequent

operation. Otherwise, any element looseness would

result in rapid fatigue damage to the pack, while

uneven element spacing may compromise the

element fouling characteristics.

Thermal and pressure drop performance have similar

levels of importance. On-going element development

activities invariably involve a continuous search for an

element profile that produces either:

• The same thermal performance for a lower

pressure drop or

• A better thermal performance for the same

pressure drop and/or

• The achievement of either of the above objectives

while using less total surface (i.e. at minimum

weight and hence cost).

Such detailed differences between element

geometries have been thoroughly researched

and applied by Howden.

It is paramount to minimise the clean plate pressure

drop in order to achieve either the lowest fan power

(for new installations), or the maximum fan margin

(for retrofits on existing installations). The nex t most

important pressure drop parameter is the fouling

resistance of the element. This may be considered

to be the rate at which fouling and pressure drop

drift might be expected to o ccur for any given set

of adverse operating conditions. The final most

important factor is the ea se of cleaning of the profile

– both by means of conventional soot blowing and

high pressure water washing.

With regards to thermal performance, the factor

of primary importance is inevitably the ability to

achieve the required thermal per formance using

the selected element profiles.

While original equipment might readily be designedto meet a given thermal performance with any

selected combination of elements simply by making

the heater deeper or larger, with retrofits in a n

existing heater, it can be even more important to try

to achieve the maximum thermal performance

within the existing volume of the heater. This is why

the maximum thermal p erformance (for a given

volume) is the next selec tion criterion. While this is a

parameter or requirement that inevitably must be

considered in any selection of original equipment or

retrofit, in many cases, the retrofit of a combination

of higher performance elements in an older unit can

make this requirement slightly less stringent.

Equally in many installations it is also important that

there is a suitable element metal temperature

distribution through the depth of the rotor to

minimise any dew point condensation p henomena

straddling across two tiers of elements.

Minimum weight represents the least considered

technical requirement, but from a commercial

viewpoint, the element weight has a direct impact

on cost, and must therefore always be considered.

Howden offers unrivalled advice in element

selection, particularly where operating conditions

have changed since the original elements were

supplied, and can recommend alternatives to a ssistin optimising plant operation.

It is important to note that copied and wrongly

manufactured element plates may very inefficient

and/or and sensitive to blockage and fouling.

HOWDEN PRODUCTS

HOWDEN KNOW HOW

ROTARY AIR HEATER ELEMENTS

Mechanical &Dimensional

Integrity

MinimumPressure Drop(Clean Plate)

Fouling Resistance

Ease of Cleaning

MinimumWeight(Cost)

SuitableElement MetalTemperatureDistribution

Maximum ThermalPerformance

(For given volume)

RequiredThermal

Performance

T H E

R M A L

F a c t o r s o f d e c r e a s i n g i m p o r t a n c e

P R E S S UR E DR OP

F a c t or s of d e c r e a

s i n gi m p or t an c e

OptimisedElement

Profile



66



67

INDIVIDUALLY TAILORED SERVICES LIFETIME SUPPORT FOR ALL PRODUCTS

IN THIS SECTION

Howden Legacy Brands 68

Howden Mining Products Capabilities 70

Turnkey Installations 72

Lifetime Maintenance 74



68

WESTINGHHOWDEN

HOWDEN LEGACY BRANDS

AEREX®

FANS

AERODYNE FANS

DONKIN BLOWERS

GODFREY

HOWDEN SIROCCO

JOY FANS

PHOENIX FANS

VENTILATEURS NEU FANS

VARIAX® FANS

CARTER FANS

VOITH

FANS

BURTON CORBLIN

COMPRESSORS

DAVIDSON® FANS

ENGART FANS

HOWDENCOMPR

MAJAX FANS

PITSTOCK FANS

TURBOWERKE MEISSEN FANS

VENTILATOREN SIROCCO FANS

BERRY FANSBUFFALO® FANS

JAMES HOWDEN (BELOW) WAS NOT ONLY AN INNOVATOR AND INVENTOR WHO REVOLUTIONISED

THE WAY THE WORLD THOUGHT ABOUT GENERATING POWER, HE WAS ALSO AN INTERNATIONAL

BUSINESSMAN WHO FORGED NEW RELATIONSHIPS AND PARTNERSHIPS WITH LIKE MINDED ENGINEERS

AND BUSINESSMEN AROUND THE WORLD.

As early as the 1920s his negotiations with A/B

Ljungströms Angeturbin (ALA) resulted in the

formation of a joint venture company – Howden

Ljungström Preheaters (Land) Limited based

in Glasgow and Wellsville.

This company developed and manufactured the

rotary air preheater which remains a prevalenttechnology in air and gas handling, and a key

product in the Howden portfolio. James Howden

& Co Ltd also licensed the screw compressor from

SRM in Sweden and became the first company

to commercialise the technology.

This international vision has been part of Howden’s

strength over the last 160 years and throughout this

time we have created, partnered, developed and

acquired many well-known technologies, companies

and/or brands in air & gas handling.

Customers who own legacy branded products can

rely on Howden to provide comprehensive andprofessional sales and service support throughout

the life of the equipment.



69

OUSE FANS GREEN

FANS®

FANS

INDIVIDUALLYTAILORED SERVICES

CANADIAN

BLOWER

BUFFALOFORGE®

AMERICAN BLOWER®

FANTECNIC FANS

BLOWERS

FANS & HEATERS

JOY GREEN FANS

WOLF FANS

MEISSEN FANS

SIROCCO® FANS

STURTEVANT® FANS

JAMES HOWDEN FANS

AIRTECHFANS

DONKIN FANS

WHEELER FANS

PROCESSESSORS

POWERMAX FANS

SHELDON FANS

TAILARES SANCHEZ LUENGO (TSL) ELEMENTS

NEU FANS

Howden® is a registered trademark of Howden Group Ltd. All rights reserved.

Variax® is a registered trademark of Howden Denmark. All rights reserved.

Sturtevant®, Green Fans®, Buffalo® Fans, Davidson®, Sirocco®, Buffalo Forge®, Aerex®,

and American Blower® are registered trademarks of Howden North America Inc.

All rights reserved.

All other trademarks are the property of their respective owners.



70

HOWDEN MINING PRODUCTS CAPABILITIES

HOWDEN HAS A WORLDWIDE FOOTPRINT THAT ENABLES THE COMPANY TO SUPPORT MININGCUSTOMERS WHEREVER THEY ARE LOCATED ON THE GLOBE.

All aspects of the value chain are catered for in

a well-balanced mix starting at the engineering

concept and stretching to the supply and support

of the finished product.

Our core research and consultancy arm is based

at our headquarters in Renfrew in the United

Kingdom. These facilities are staffed by specialists

in disciplines such as creep analysis, advanced

acoustics and Computational Flow Dynamics

(CFD). Efficient, modern communication brings this

sophisticated technical consultancy service to other

Howden companies, and to Howden customers,

ensuring they always have access to optimised,

efficient, durable equipment and solutions for

the mining and mine-related industries.

We have companies in 17 countries on six

continents; providing superior engineering and

manufacturing, backed by a comprehensive

network of operational, sales and service

personnel, all in close proximity to v irtually all

the world’s major metals and minerals deposits.

Through these companies our customers are able

to access our market-leading technologies, and

comprehensive local knowledge and insight

from our experienced engineers and site service

personnel. Wherever a new mine or plant islocated, Howden invariably delivers the best

possible solution to site, no matter how remote

the location. Rapid local support is also available

for sophisticated solutions on which 24/7

production schedules are dependent.

This worldwide network ensures that multi-national

resources companies can be confident that Howden

will remain their single, consistent and reliable globa l

supplier of mine and mine-related engineered

solutions; anywhere in the world their operations

are located.

Howden’s global reach and applications experience

over a wide range of products enable us to provide

packaged solutions for any mission critical customer

specification.



71

INDIVIDUALLY TAILORED SERVICES

Renfrew, Glasgow

New Philadelphia

Howden North America Inc.

Howden UK (Group headquaters)

Sao Paulo

Howden South America

Johannesburg

Howden Africa Holdings

Beijing

Howden Hua

Moscow

Sydney

Howden Australia

Haryana

Howden Air & Gas India Pvt. Ltd

Heidenheim

Howden Ventilatoren

Howden LLC

HOWDEN’S MINING FOCUSED BUSINESS LOCATIONSHowden has engineers with extensive exper tiseof local customer requirements in each of the key

global mining markets:

• Australia and South East Asia

• China

• Europe/Russia (FSU)

• India, Central Asia and Middle East

• North America

• South America

• Africa.



72

TURNKEY INSTALLATIONS

HOWDEN’S PROJECTS INVOLVEMENT STRETCHES BEYOND THE DESIGN AND MANUFACTURE OFWORLD-CLASS PLANT AND EQUIPMENT. WE OFFER A TURNKEY SERVICE THAT TAKES A PROJECT FROM

CONCEPTUALISATION, THROUGH DESIGN AND MANUFACTURE, TO INSTALLATION AND COMMISSIONING.

The comprehensive Howden package includes

customised engineering, manufacture, project

management, supply, service solution engineering

and site management service, to the satisfaction

of the customer and local regulatory authorities.

ENGINEERING

Sophisticated computer programs are used to

examine multiple solutions for each ap plication.

Where required, feasibility stu dies, including

commercial evaluations, are completed. Howden’s

experienced professional mechanical and structural

engineers use modern design techniques and

systems such as Finite Element A nalysis (FEA),

Computer Aided Design (CAD) and Computational

Fluid Dynamics (CFD) that ensure that all our products

perform to the highest specifications. The end result

is custom-engineered products for each application,

tested at specialised facilities using either full-size

systems or scale models. We also have equipment

for stress, acoustic and vibration measurement, and

on-site performance testing can be conducted to

internationally recognised standards.

MANUFACTURING

Howden equipment is manufactured to world classstandards in its own factories, or at third party

supplier facilities. Our factories are staffed by

experienced teams with access to a decades-long

institutional knowledge base that provides us with

the capability to produce products with a proven

track record. Procedures developed specifically to

suit the Howden product range are used to optimise

efficiency and performance.

Established suppliers with proven quality records

are registered on the Howden approved vendor list

and their performance is regularly reviewed. Our

sub-contractors are selected on the basis of their

ability to deliver a quality product or service on time.

PROJECT CAPABILITYThe Howden project capability includes the supply

of complete end-to-end solutions. This includes civil

works and associated buildings, ductwork, main drive

motors, electrical switchboards and control panels,

instrumentation and condition monitoring. Major

rehabilitation works are engineered and managed.



73


OUR TURNKEY SERVICE INCLUDES:

• Site surveys, inspection and plant evaluation

• Planning and scheduling using the latest computer techniques

• Engineering, design, and drafting

• Procurement

• Negotiation and control of sub-contracts

• Manufacture, testing and supply of equipment

• Where appropriate, re-work of existing equipment

• Site management and supervision of erection and commissioning

• Plant noise level evaluations and solutions

• Performance testing and upgrading

• Failure investigation

• Fan system variable speed conversion evaluation and design

• Improvement in fan and blower reliability.



74

LIFETIME MAINTENANCE

OUR COMMITMENT TO SUSTAINABLE CUSTOMER SERVICE

EXCELLENCE HAS BECOME PART OF OUR CORPORATE CULTURE.

THIS EXTENDS TO SUPPORT FOR OUR EQUIPMENT THROUGHOUT

ITS LIFETIME AT SITE AND REPRESENTS MORE THAN ONCE-OFF

MAINTENANCE; EXTENDING TO INCORPORATE TOTAL PLANT

MAINTENANCE OWNERSHIP AND, WHERE NECESSARY, ON-LINE

ROUTINE MAINTENANCE WHERE DEDICATED TEAMS ARE

PERMANENTLY PLACED ON SITE.

LIFETIME MAINTENANCE

• Planned routine and preventative maintenance

• Monthly check and cleaning/adjusting

• Minor overhauls

• Major overhauls (every five years)

UNPLANNED MAINTENANCE

• Emergency breakdown with a 24 hour

response availability• Overhaul at longer off-load periods on

an 24 hour/round the clock basis

• Dynamic balance and laser alignment

• Off-site maintenance

• Overhaul equipment

SPARES SUPPLY

• Supply of all planned (routine or preventative)

fan spares

• Supply of emergency spares• Stock management of spares off or/and on site

SITE SERVICES

All Howden equipment and systems have operating

lives of between 20 and 40 years, and beyond.

Equipment in service for extended periods of time

gets worn o ut, requiring refurbishment. In addition,

over time systems and requirements change,

meaning that existing equipment often needs

to be made more efficient and p roductive.

We recognise this need, and constantly endeavour

to upgrade our installed base of equipment to keep

pace with evolving customer requirements and

specifications. We offer our customers the option of:

• Re-builds to original specification and upgrade

of any air and gas movement equipment to the

equivalent of the latest technology

• Upgrade for different output and changed

gas medium

• Performance upgrades

• Turnkey supply of design, material, site

management, site installation

• Site surveys, inspection and plant evaluation

• Performance and function tests and the relevant

problem solution/implementation.




75



Howden Australia

Unit 23, 38-46 South Street

Rydalmere

NSW 2116

Australia

Tel: + 61 2 8844 9100

Fax: + 61 2 8844 9101

E mail: sales@howden com au

Howden Ventilatoren

Stubentalstraße 44

D-89518 Heidenheim

Germany

Tel: +49 7321 3520

Fax: +49 7321 35230

Email: [email protected]

Howden LLC

127030 Russia,

Moscow,

Novoslobodskaya Str., 21

Tel: +7 495 933 70 79

Fax: + 7 495 933 70 79

Email: [email protected]

Howden North America Inc.

New Philadelphia Division

338 South Broadway St.

New Philadelphia, OH 44663

Tel: +1 330-308-7000

Toll Free: +1 800-431-4880

Fax: +1 330-339-8210

Email: sales@howdenbuffalo com

ENGINEERING EXCELLENCE WORLDWIDE

Focusing on its global expertise in mining and primary processing plant,Howden delivers first class technology, project management and customersupport. Wherever our customers are located, a Howden office is close at

hand. With engineering, manufacturing and sales offices throughout the

world, we understand and satisfy local market needs.

www.howden.com

MINING FOCUSED BUSINESSES

2012 GlobalMining LoRes

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Transcript of 2012 GlobalMining LoRes