PLAN RECORD REVISIONS

ISO METRIC SCREW THREADS NO. D E S C R I P T I O N ( D A T E )

SAMSUNG H.NO.1451/2/3/4/75/1506/7

APPROVED T.Yuki CHECKED

DRAWN S.SuenoCONFERRED SCALE

ORDER ITEM DRAWING NO. REV.NO.

F1562/3/4/5/K1A25/6/7 - N57-30M-M500(1) 0

MITSUBISHI HEAVY INDUSTRIES, LTD.MITSUBISHI HEAVY INDUSTRIES, LTD.MITSUBISHI HEAVY INDUSTRIES, LTD.MITSUBISHI HEAVY INDUSTRIES, LTD.NAGASAKI SHIPYARD & MACHINERY WORKSNAGASAKI SHIPYARD & MACHINERY WORKSNAGASAKI SHIPYARD & MACHINERY WORKSNAGASAKI SHIPYARD & MACHINERY WORKS

DRAWN Oct. 2, 2003. ISSUED

AUX. BOILER (MAC-30B)

OPERATION AND MAINTENANCE INSTRUCTIONS(1)

DR

AW

ING

NO

.

N57

-30M

-M50

0(1)

RP0

CHECK-ED

AP-PROVED

SHEET(S) WITH COVER

7 5

SZ

G

G

7 5

MARINE BOILER DESIGNING SEC.

TURBO&MARINE MACHIN.DESIG.DEPT

A34

A4447 total 451

MAC TYPE AUX. BOILER

OPERATION AND MAINTENANCE INSTRUCTIONS(1)

Y.Ono

FOREWORD

This instruction manual treats of affairs requiring attentions of workers incharge of this boiler with a view to giving them a guidance for properoperation to make the most of the boiler, to prevent injuries of damages thatmay be caused by improper handling and to ensure high-efficiency service andperfect safety for a long time.

However, this instruction manual refers to only fundamental rules necessaryfor operating handling the boiler.Consequently, those who are in charge of handling the boiler are expected tolearn completely the subjects included in this manual and get well versed in allrelated appliances including pippins and fittings as well as the boiler itself sothat they can handle the equipment perfectly.

WarningPlease strictly refrain from copying the contents of this manual or making anextract from them and revealing them to others.

A-0

(1)

TABLE CONTENTSECTION

A. INTRODUCTION

1. PRINCIPAL PART A-1

2. DESIGN DATA A-2

3. PERFORMANCE DATA A-3

4. BOILER ACCESSORIES A-4

5. CONSTRUCTION A-5

6. OPERATING PROCEDURE A-6

7. MAINTENANCE A-7

8. CHECK LIST A-8

B. OPERATING PROCEDURES

1. INTRODUCTION B-1

2. OPERATING OF AUXILIARY BOILER B-2

3. BOILER HEATER OPEATION PROCEDURE B-3

C. GENERAL MAINTENANCE

1. FEED WATER AND BOILER WATER TREATMENT C-1

2. CARE OF BOILER OUT OF SERVICE C-2

3. HYDROSTATIC TESTS C-3

4. BOILER OUT C-4

5. WATER WASHING FIRESIDES C-5

6. ACID CLEANING C-6

A-0

(2)

D. MAINTENANCE AND REPAIR

1. MAINTENANCE OF REFRACTORY D-1

2. BOILER PRESSURE PART D-2

3. HEADER END PLATE D-3

4. FLANGED JOINT D-4

5. SLIDING SADDLE D-5

6. TUBE PLUGS D-6

7. REFERENCE DRAWINGS D-7

E. BOILER ACCESSORIES

1. AUTOMATIC BOILER CONTROL SYSTEM E-1

2. OIL BURNER E-2

3. SOOT BLOWER E-3

4. WATER GAUGES E-4

5. SAFETY VALVE E-5

8. CHEMICAL DOSING EQUIPMENT E-8

10. F.D. FAN E-10

18. PISTON VALVE E-18

AA. INTRODUCTION

PRINCIPAL PART A-1

DESIGN DATA A-2

PERFORMANCE CURVE A-3

BOILER ACCESSORIES A-4

CONSTRUCTION A-5

OPERATING PROCEDURE A-6

MAINTENANCE A-7

CHECK LIST A-8

A-1

1. PRINCIPAL PARTMITSUBISHI MAC-B AUX. BOILER

A-2

(1)

2. DESIGN DATA FOR 1 BOILER

PRESSURE Kg/cm2g

Design 18.0

Operation 16.0

Hydrostatic test 27.0

Safety valve setting 18.0

TEMPERATURE

Steam (at drum) 203.4 (Saturated)

Feed water 80.0

Air to Burner 45

EVAPORATION Kg/h

Boiler Max 16 k MODE 26,000

HEATING SURFACE m2 328

FURNACE VOLUME m3 20

BOILER WATER WEIGHT kg

Total cold water fill the unit completely 12,500

Cold water to fill boiler to normal water level 9,500

Water at operation 8,200

BOILER WEIGHT kg

Boiler dry (with burner & soot blower) 31,400

Total operation 39,600

A-2

(2)

THE DATE

Location No. Tubes O.D.(mm) Thickness(mm)

Rear Bank Tubes 372 45.0 2.9

Front Water Wall Tubes 24 76.2 4.0

Rear Water Wall Tubes 24 76.2 4.0

Front Bank Tubes 23 76.2 4.5

Floor, Side, Roof, Wall Tubes 23 76.2 4.5

Rear Bank Front Wall Tubes 15 76.2 4.0

Rear Bank Rear Wall Tubes 15 76.2 4.0

Gas Outlet Water Wall Tubes 15 76.2 4.5

A-2(3)

AUX. BOILER MAC TYPE

LEVEL - ALARM AND FUEL OIL CUT

A-3(1)

BOILER EXPECTED PEFORMANCE DATA (16.0K26T/H

LOAD 25% 50% 75% 100%

EVAPORATION kg/h 6,500 13,000 19,500 26,000

DRUM PRESSURE kg/cm2 16.0 16.0 16.0 16.0

FEED WATER TEMP. deg.C 85.0 85.0 85.0 85.0

SATURATED STEAM TEMP. deg.C 203.4 203.4 203.4 203.4

BOILER EFFICIENCY (LHV BASE) 82.1 82.8 81.9 80.5

CALORIFIC HHV kcal/kg 10,280 10,280 10,280 10,280

VALUE LHV kcal/kg 9,713 9,713 9,713 9,713

FUEL OIL CONSUMPTION kg/h 475 941 1,427 1,935

EXCESS AIR RATE 31 16 15 15

O2 RATE 5.0 3.0 2.9 2.9

COMBUSTION AIR FLOW kg/h 8,720 15,290 22,980 31,160

FLUE GAS FLOW kg/h 9,190 16,230 24,410 33,090

AMBIENT AIR TEMP. deg.C 45 45 45 45

A-3(2)

MAC-30B BOILER EXPECTED PERFORMANCE CURVE

79

80

81

82

83

0 10 20 30 40 50 60 70 80 90 100

EFF

ICIE

NC

Y (%

)

EFFICIENCY CURVE (L.H.V. BASE)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

2.2

0 10 20 30 40 50 60 70 80 90 100

F.O.C. CURVE ( * 1,000 kg/h)

F.O

.C.

0

1

2

3

4

5

6

7

8

9

10

0 10 20 30 40 50 60 70 80 90 100

O2

RA

TE

BOILER LOAD %

O2 RATE CURVE (% BY VOLUME)

A-4

4. BOILER ACCESSORIES

EQUIPMENT MANUFACTURER

(1) COMBUSTION CONTROL MITSUBISHI HEAVY IND.

Electronic operated

(2) FEED WATER REGULATOR MITSUBISHI HEAVY IND.

Electronic/air operated

(3) DRUM LEVEL SAFETY SYSTEM YAMATAKE CO., LTD.

Electronic operated

(4) OIL BURNER VOLCANO CO., LTD.

Steam atomizing venture type

(5) SOOT BLOWER KIKAN BUHIN CO., LTD.

Rotary type

(6) WATER LEVEL GAUGE SAWADA SEISAKUSHO CO., LTD.

Transparent type

(7) SAFETY VALVE FUKUI SEISAKUSHO CO., LTD.

(8) F.D. FAN TONG YANG MAGIC CO., LTD.

(9) CHEMICAL DOSING EQUIPMENT I.T.I CO., LTD.

(10) PISTON VALVE KONAN VALVE CO., LTD.

A-5

(1)

5. CONSTRUCTION

The boiler is named MITSUBISHI MARINE WATER TUBE BOILER. The description

given below is an outline of its construction. For its further details, you are referred to the

reference drawings for the ship equipment.

1. General construction

The boiler is of two-drum construction with one steam drum and one water drum, and

mainly consists of boiler proper, boiler casing, fuel firing equipment, mountings,

fittings and other accessories.

The boiler structure is supported with a water drum water wall lower headers as

supporting bases. The whole boiler constructions is so designed as to be able to

withstand the rolling, pitching and the shock of the ship. Careful consideration is also

given to the movement by thermal expansion of the boiler.

Combustion gas flows through the boiler in a return flow path where necessary,

manholes, peep hole are provided for easy access and inspection.

2. Furnace

Closely spaced water wall tubes of 76.2 mm outside diameter are provided to the

furnace side, rear, roof except burner opening and front wall in order to increase the

heat absorption in the furnace and form it strong enough to withstand vibration, etc.

A-5

(2)

At the top and bottom of the front and rear walls are provided water wall headers

respectively. The water that entered the bottom headers rises through the wall tubes to

the top headers. As it rises, it is heated to saturation temperature and begins

evaporating and from the top headers this water-steam mixture is led to the steam

drum.

One end of each top header is directly connected to the steam drum and one end of

each bottom header is directly connected to the water drum.

The roof, side and bottom water walls of the furnace are formed with welded water

wall tubes connecting the water drum to the steam drum. No headers are provided for

them.

3. Boiler casing

The furnace of the boiler is made completely gas-tight by the adoption of welded water

wall construction. The welded water wall construction is also adopted to the front and

rear walls of the rear evaporating tube section where tubes are exposed to the

combustion gas.

On the outer surface of the furnace water walls, insulation are provided.

Insulations are applied to the outer surface of the water walls and the outermost

surface of the furnace is covered with galvanized steel casing except furnace roof and

floor.

A-5

(3)

4. Steam Drum

The steam drum and water drum are to be fabricated using boiler steel plate approved

by applicable ship classification society. They are to be of all-welded construction, and

welded joints are to be produced in accordance with the procedures approved by

applicable ship classification society and then given the post-weld stress relieving.

In the steam drum, a multi-perforated baffle plate covering the entire steam evaporation

surface is provided to prevent the generation of water-saturated steam. Also, in the

steam compartment the steam separator is provided to completely remove the moisture.

The water compartment is provided with the feed water internal pipe, surface blow-off

internal pipe, chemical feed internal pipe, and sampling pipe.

The baffle plate and steam separator in the steam compartment are of built-up type,

permitting to be disassembled for bringing in and out of the drum by way of the

manhole.

A-6

(1)

6. OPERATING PROCEDURE

1.Preparation

Prior to beginning operation, check and prepare for the following.

(1) Boiler proper

Refractoriness, manhole covers, Header end plate covers and oil residue in the burner

wind box

(2) Valve settings

Water level gauge root valves, drum vent valves, safety valves, pressure gauge root

valves, blow-off valves, and pressure detecting root valves for ACC.

(3) Burners and accessories

Heavy oil lines and atomizing steam lines and valves.

Opening and closing of F.D. FAN inlet vane.

Kind of fuel oil (Diesel oil or heavy oil C).

(4) Ancillary equipment

Proper functioning of automatic combustion control equipment, automatic feed water

regulator, soot blowers and remote water level indicator.

(5) Filling the boiler

Fill the boiler up to the normal water level with distilled water or demineralized water.

Check feed water system.

(6) Starting the forced draft fan

Start the forced draft fan with inlet vane fully closed.

(7) Starting the fuel oil burning pump

Start the pump. In case of hot start, clean the oil line of cold heavy oil and warm-up the

line with oil flow through the recirculation line. In case of cold start, discharge oil

remaining in the line and fill it with diesel oil.

A-6

(2)

2. Lighting off and pressure raising

Proceed in the following order.

(1) Confirmation of response of water level gauges.

(2) Purging the furnace

Operate the fan with inlet vanes opened 100 % for more than 1.0 minute.

(3) Lighting off the burner

Use a nor tip for the burner, and light off it with a pilot burner. After lighting off,

observe combustion condition.

(4) Pressure raising

Note drain discharge, air venting and water level fluctuation.

(5) Inspection after completion of pressure raising

Confirm response of water level gauges. Check indication of pressure gauges and

functioning of safety valves.

3. Operation notes during normal service operation

(1) Change load as slowly as possible when load is high.

(2) Lower the steam pressure set point to prevent popping off of safety valves when the

load fluctuation is severe.

(3) Check various parts referring to the check list.

(4) Check combustion condition and make a necessary adjustment to obtain good

combustion. Reduce excess air as much as possible.

(5) Analyze boiler water and feed water, and maintain proper condition of them.

(6) Blow soot blowers to maintain heating surfaces clean.

Operate the fan with inlet vanes opened 100 % formore than 1.0 minute.

Caution

A-6

(3)

4. Boiler shut-down

Shut down the boiler in the following order.

(1) Blow soot blowers.

It should be made while the boiler is carrying not less than 50 % load.

(2) Shut-down burner, one at a time.

(3) Purge the furnace.

(4) stop the fan.

(5) In case of boiler stand-by

Burn a burner at times and maintain the boiler at about normal pressure with boiler

water at normal level.

(6) In case of complete shut down;

Close the feed water valve and the steam stop valve.

Open the drum vent to release steam to lower the pressure.

After that, laid-up the boiler dry or wet.(Refer to C-2.)

A-6

(4)

5. Operation of ancillary equipment

(1) Burner

Pay attention to excess air ratio, oil pressure and temperature atomizing steam pressure,

and cleanness of burner tips to maintain good combustion. Never fail to purge the

furnace before lighting off and after shutting down burner.

(2) Automatic combustion control equipment

Operators are requested to be well versed in change-over operation of the boiler control

mode AUTO to and from MANUAL so as to be able to change control mode smoothly.

Pay attention to indications of various controls and see whether they are all functioning

properly or not.

Blow off drain from supply air lines every 4 hours.

(3) Automatic feed water regulator

Pay attention to water level fluctuation and see whether the feed water regulator is

functioning properly or not.

(4) Soot blowers

Soot blower shall be operated by the MANUAL and must not be operated in IGS mode.

A-7

(1)

7. MAINTENANCE

1. Feed water and boiler water treatment (refer to C-1)

Feed water and boiler water shall be analyzed at least once a day. Amount of chemicals

to be added and amount of boiler water to be blow down shall be controlled referring to

the results of the analysis so as to maintain each chemical content of the water within

the prescribed limit. Operators are requested to have correct understanding about the

action and effect of each chemical and calculation method of required quantity of it.

Recommended chemicals are as follows.

For raising pH value AMEROID/GC

For raising PO43- ADJUNCT "B"

2. Maintenance during shutdown

There are two ways of laying up the boiler, dry and wet. Either way may be adopted as

the case may be. When the boiler is laid-up wet, care should be taken to the

concentration of chemicals in the boiler water, and when the boiler is laid-up dry, care

should be taken to the effectiveness of the drying agent.

A-7

(2)

3. Hydrostatic test

There are two kinds of hydrostatic test one for checking water tightness of pressure

parts and the other for checking strength of the same.

Test pressure should be determined to suit the case.

4. Boiling out

Boiling out is intended to cleanse the boiler internal surface of oil and grease. The

boiler is filled with high alkaline solution and is heated for a predetermined duration by

means of steam or by burning oil whichever the occasion demands.

Boiling out burning oil is often made to serve as burning and drying out refractory used

in the boiler setting, too.

Recommended duration of boiling out for a new boiler is 2 to 3 days.

5. Hot water washing

Hot water washing is intended to remove sludges sticking to the gas side of the boiler

that can not be blown off by soot blowing. There are two ways for hot water washing,

one by use of soot blowers and the other by use of a temporary hand nozzle, Both ways

have their own merits, either way may be adopted as the case may be.

Recommended hot water temperature is about 80 .

A-7

(3)

6. Acid cleaning

Acid cleaning is intended to remove scales on the water side of the boiler. Inhibited

hydrochloric acid solution is generally used for this purpose. But it is important to

consult with the professional expert as to the details of cleaning job so as to take most

suitable measures to the actual case and to prevent damage that may result otherwise.

7. Refractory

Two kinds of refractory used are for this boiler, one is plastic refractory and the other is

castable refractory. Both refractory are often used for repairing work, too. As the plastic

refractory needs to be burned after placed, it is not used on the boiler pressure parts,

where the castable refractory should be used instead.

When the castable refractory is to be used on the pressure parts, it should be given

necessary clearances for thermal expansion.

After repairing refractory work. never fail to dry it out by firing.

8. Boiler proper and water walls

Inspect both gas and water sides of the boiler whenever the opportunity is afforded and

see whether it is necessary or not to clean the gas side, to acid-wash the water side or to

replace tubes. Results of these inspections should be referred to in the subsequent

burner operation, feed water control, etc.

9. Boiler drum support legs

The water drum support legs on the boiler rear side are the only fixed legs, and all the

other legs are of sliding type requiring the injection of grease once a year (Grease:

SHELL ALVANIA EP NO.2, MOBILUX 2 or equivalent).

10. Boiler repair

The boiler repair work includes the tube plugging, header end plate renewal, removal

of manhole cover, tube renewal, expander renewal, packing renewal, etc. It is required

that the boiler operator be familiar with the working procedures there in involved.

A-7

(4)

11. Maintenance of accessories

(1) Burner

The burner tip is to be cleaned periodically and examined for disorder. The swirler is to

be maintained as clean as practicable, and also the burner throat area is to be always

kept in good working order.

(2) Soot blower

The soot blower steam line drain discharge, smoothness of rotary motion, and adequacy

of lubrication are to be monitored. In the process of boiler open-up inspection, the

element nozzle is to be examined for disorder and also the element for bend.

(3) Automatic Combustion Control System and Automatic Feed water Regulator.

By taking the control unit indicator reading, the control performance of each system is

to be monitored.

The air supply line drain is to be blown out once every four hours.

The moving parts of every equipment are to kept always clean.

(4) Water level gauge

The transparent gauge glass is to be blown clear at least once a day to ascertain its

responsiveness.

The remote-reading level gauge reading is to be compared with the transparent gauge

glass reading (once a day) to ascertain its reliability.

A-8

(1)

8. CHECK LISTFor the safety of the boiler operation, at least the following items should be checked

periodically.

Item Checking method Frequency

Water level Open and close the drain valve and see Once a day

gauge the response of the water level in the

gauge.

Boiler water Measure concentration of chemicals in Once a day

boiler water and check water quality.

Remote water Lower the drum water level down to Once per

level indicator -100 mm by operating the feed water two weeks

regulator by hand and compare the

indication of the remote water level

indicator with that of the transparent

water level gauge.

Burner When the burner only is in service, Once per

flame-eye shut it down and see that the indicator six months

lamp for loss of fire goes on.

Water level When the boiler is running under low Once per

alarm load, change the drum water level. two weeks

F.O. cut-off When the boiler is stopping, change the Once Per

condition drum level (low-low), stop the F.D. FAN, three months

and stop the F.O. PUMP.

Steam leakage Check the boiler press, parts, flanges, Once a day

water leakage and valves.

BB. OPERATING PROCEDURES

INTRODUCTION B-1

OPERATION OF AUXILIARY BOILER B-2

BOILER HEATER OPERATION PROCEDURE B-3

B-1

(1)

INTRODUCTION

The auxiliary boiler generates steam required for tanker service.

When the main engine is out of service, the steam necessary for tanker service is supplied by the

auxiliary boiler only.

As the engine load increases, the exhaust gas economizer evaporated more steam and the

auxiliary boiler is placed out of service.

When inert gas is necessary at normal sea going, boiler should be operated in order that O2

content in boiler exhaust gas is less than allowable limited value (abt. 5%).

At the above operation, the burner mode becomes manual mode and boiler minimum load is

limited in order that exhaust gas O2 content is less than allowable limited value.

Therefore, there are three kinds of boiler operation modes as shown below.

1) Auxiliary boiler to be operated : TANKER SERVICE MODE

2) Auxiliary boiler to be operated : IGS TOP UP MODE

when inert gas is necessary.

3) Exhaust gas economizer alone to be operated : REPOSE MODE

B-2

(1)

OPERATION OF AUXILIARY BOILER

1. General notes on boiler operation

(1) Introduction

The following notes on boiler operation are of general nature to be observed by the boiler

operators.

Although some basic rules must be strictly followed in operation and maintenance of the

boiler and ancillary equipment, it is up to the operators familiarize themselves with

characteristics of individual equipment.

This can only be accomplished by diligently observing, recording, checking and comparing

data and details.

Such attentions and proper measures promptly taken by the operators often prevent boiler

outages and repairs.

(2) Performance

a) The boiler is designed to deliver steam at required pressure and temperature when

supplied with feed water at the specified temperature. Operating conditions exceeding

the design limitations will shorten the life of the boiler and component parts.

b) The concentration of solids entrained in the steam leaving the steam drum depends to a

great extend upon the quality of the feed water.

Suitable feed water treatment and adequate blow down should be used to maintain the

boiler water alkalinity and concentration of total solids below a predetermined point.

B-2

(2)

c) If each heating surface of the unit is kept clean, the temperature of the gas leaving the

boiler and the draft loss through the boiler will normally be constant for a given load and

excess air ratio.

This illustrates the desirability of keeping records of boiler performance from the start of

operation. If a standard is set up when the boiler is new, the deviation from it will serve

as an indicator that shows the operating condition of the boiler as well as its own

condition.

Then, steps may be taken to determine and correct the cause for the discrepancy and

often avoid the development of difficulties.

It is desirable to keep records of operating data in a form that facilitates comparison of

similar operating conditions.

d) The amount of fuel oil consumed should be measured.

Fuel oil should also be periodically sampled and analyzed to check calorific value,

chemical composition, etc.

e) The temperature and analysis of gases leaving the boiler are invaluable as an index of

complete and economical combustion.

The best percentage of excess air to use depends upon the nature of the fuel, the

design of the fuel burning equipment and other factors. The most desirable conditions

for different rates of evaporation should be established through the diligent study of the

performance of the boiler.

B-2

(3)

(3) Operation

a) When hot water is used to fill the boiler, care should be exercised to feed slowly to avoid

severe temperature strains on drums, headers, etc. Always see that each part of the unit

is properly vented, and fill it till water level appears in the level gauge.

The vent valve of the steam drum should be kept open during the filling operation and

should not be closed till all the air is vented from the unit.

The unit will have been completely vented by the time when the drum pressure reaches

approximately 2 kg/cm2g.

b) The time required to bring the boiler up to pressure and temperature depends upon the

pressure and temperature at which it is to operate. During initial start-up of a new boiler,

the longer time then the standard must be used for heating up and pressure raising so as

to allow careful inspection of expansion movements and clearances of various parts.

Increase of firing rate should not exceed a saturation temperature rise of 67C (120F)

per hour for a natural circulation boiler.

Ordinary start-up can be done at faster rate than the above. But, the operating

procedure for starting up the boiler safety should be established through measurements

of metal temperatures of important parts of the boiler, and the boiler should be started

accordingly.

B-2

(4)

(4) Water level

a) When the boiler is to be filled for operation, slowly feed water till the water appears 25

to 50 mm high in the level gauge. This is a precaution against the swell that occurs when

the boiler water is heated and begins evaporating and also against the sudden fall of the

boiler pressure when feeding comparatively cold water.

b) Before lighting a fire, the operator should check the water level in the boiler by blowing

down the water level gauge. Usually, slowly cracking the drain valve on the level gauge

will suffice. A liberal blow down will serve to clear the drain valve seat of any foreign

matter that may be present.

When the new boiler is in operation, routine check of the water level gauge should be

made at least once a day. If the action of the water in the gauge is sluggish when the

drain valve is opened or closed, investigation should be made of the cause and the

condition should be corrected immediately.

c) Even though the boiler is equipped with the reliable automatic feed water regulator and

the remote water level indicator, the water level in the level gauge should be observed

periodically during normal operation.

Never shut off the feed water supply completely to the steaming boiler even for only a

short period.

B-2

(5)

d) Unless otherwise instructed, the water level should be carried near the center of the

gauge glass. Any adjustment of the water level should be gradual. If the water level is

too high, priming may occur, especially when the steam demand is large or rapidly

fluctuating.

If priming occurs, blow down the boiler water and changing over the feed control to

manual operation, reduce the water level.

But, the water level should be maintained as such that is just sufficient to take care of a

drop in level that may occur in the subsequent change in steam demand. Reduce the

steaming rate if necessary. Investigate the condition of the boiler water with regard to

concentration of alkalinity and total solids, and examine the condition of the drum

internals when the opportunity is afforded.

e) While the boiler is being brought up to pressure, gradually heat and properly drain all

cold steam piping.

f) During the pressure raising operation, the drum water level often rises higher than the

normal level due to the expansion of water. If it is desired to keep the water level visible

in the level gauge at this time, boiler water should be blow down.

g) Observe the drum water level at times to confirm the proper functioning of the automatic

feed water regulator.

B-2

(6)

(5) Others

a) When re-igniting the burner to bring the boiler back into service from the standby state,

the furnace still remains hot, filled with unburned fuel particles and unburned gas, and

thus requires internal purging by means of forced draft fan (this is an exceptional

instance in which the furnace, still hot, may be air-purged).

b) In case of relighting the burner, an igniter must be used. Never attempt to light the burner

with hot refractory in the furnace.

c) Check chemical contents of the boiler water at least once a day. Add chemicals or blow

down the boiler water as required to maintain proper concentration of chemicals in the

boiler water.

d) Frequently check the smoke indicator to maintaining efficient combustion.

e) Keep burner tips clean as they are adopt to be fouled with dirt and soot.

Note : Be absolutely sure to use the steam drum surface blow off valve when blowing

boiler water during boiler operation and to blow boiler water using the water

drum bottom blow off valve only during boiler outage.

B-2

(7)

2. Preparations

Prior to starting the boiler, attention should be paid to the following items and thorough

checking should be made on them.

Boiler

(1) All foreign materials have been remove from pressure parts.

(2) All gas side heating surface are clean and all refractory are in good condition.

(3) The furnace bottom and the burner wind box have been cleaned of oil and others.

(4) All personnel are clear.

(5) All manhole covers are securely tightened.

(6) Inspect safety valves and see that gags have been removed and easing levers are in

good condition.

(7) Open root valves for all instruments and controls connected to the boiler.

(8) Open the vent valve of the steam drum.

(9) Open all pressure gauge valves and check and see all valves on the pressure gauge

piping are open.

(10) Check and close all blow-off valves and drain valves.

(11) Fill the boiler till water level appears 25 to 50 mm high in the gauge glass.

B-2

(8)

The boiler shall be filled in the following procedure and the feed water line shall be inspected

simultaneously.

(a) When the boiler was laid up wet (Refer to "Protection of the boiler during shutdown".),

drain the boiler till the water level falls down to the bottom of the gauge glass, and bring

the water level up again to about 25 mm high in the gauge glass feeding through the

auxiliary feed water line.

Then, bring the water level up further by about 25 mm feeding through the main feed

water line.

(b) When the boiler was laid up dry, first fill the boiler feeding through the auxiliary feed water

line till the water level just appears at the bottom of the gauge glass. Then, raise the water

level feeding through the main feed water line up to about 25 to 50 mm higher then the

normal water level. This practice serves to check that both the auxiliary and the main

feed water lines are ready for service. Use distilled water for feed water whenever

possible. Boiler compound shall be added as instructed by the expert of boiler water

treatment.

Fuel burning equipment

(1) Make sure that all fuel oil lines including oil filters, etc. are in good condition.

(2) Make sure that no oil residue is in the burner wind box.

(3) Make sure that F.D.FAN inlet vane is clean and moves smoothly.

B-2

(9)

3. Lighting off and pressure raising

(1) Make sure of the drum water level by the water level gauge.

That is, the water level should fall when the drain valve of the water level gauge is

opened, and it should return to the previous level when the valve is closed.

Attention must be paid not to take the empty level gauge for full of water or stains on the

gauge glass for water level.

(2) Start the forced draft fan

Prior to lighting off, place the forced draft fan with inlet damper fully opened and purge

the furnace for at least one minute.

(3) Start the fuel oil burning pump and begin the use of the fuel oil heater, using heavy fuel oil

with normal tip which condition is operated by H.F.O. mode, MADIC auto mode.

Start the fuel oil firing pump and open the oil recirculation valve to recirculate oil through

the oil heater and burner manifold discharging cold heavy oil in the line.

(4) When the oil in the burner manifold has reached a proper temperature, burner ignition

sequence start.

(5) Reduce air pressure at WIND BOX to 20 to 40 mmAq. And securely close the oil

recirculation valve. Check the fuel oil control valve opening by the output signal of

MADIC to ensure it is ready for service.

B-2

(10)

(6) Light on the burner and immediately make a necessary adjustment of oil pressure and air

pressure to ensure a stabilized combustion of the fuel.

At this time, care should be taken to obtain such a burning condition that the fuel oil

burns completely without scattering unburned practices or producing heavy smoke.

Frequently check the indication of the smoke indicator and the flame through the

observation holes, especially after making any change in firing rate or burner inlet air

pressure.

(7) When raising the pressure, keep the burner firing five minutes and out of service 15

minutes repeatedly at the lowest oil pressure (2.5 kg/cm2g) for one hour and then again

repeatedly light off and shut down the burner to raise the steam pressure at the rate

indicated in Fig. 2-1 or less.

(8) When the drum pressure has risen to about 2 kg/cm2g, close the drum vent valve.

(9) Close the valve of the pressure gauge and remove the gauge. Then, open the valve a crack

and release steam to make sure the tubing for the gauge is clear.

Reinstall the pressure gauge and see that it works as soon as the valve is opened. In this

case, care should be taken to allow several minutes to cool the line before opening the

valve.

B-2

(11)

(10) Check the water level gauge to see nothing is the matter with it by opening and closing its

drain valve, and make sure of the drum water level again.

(11) Drain and warm all steam supply lines to the ancillary equipment and devices. It is very

important to discharge drain water from these lines and warm them up to near the

operating temperature before loading the boiler.

(12) When the drum pressure is raised to about 3 to 4 kg/cm2g below the normal operating

pressure, check the safety valves with the easing gear. Care must be taken to open and

close the valve quickly so as to prevent damaging the disc and the seat of the valve.

Fig..2-1 RECOMMENDED PRESSURE RISE

0

2

4

6

8

10

12

14

16

0 0.5 1 1.5 2 2.5

Time (hr)

Dru

m P

ress

(kg/

cm2 g

)

B-2

(12)

4. Cold Start-up

(1) When the boiler is to be started from the cold state in which no steam is available from the

land , use the starting diesel oil for fuel till the steam necessary for the oil heater becomes

available.

(2) Fill the boiler with the best water available. For this, purpose, feed water tank as much as

necessary to start the boiler before shutting down the boiler.

It is advisable to fill the boiler up to 50 to 80 mm above the normal water level so that no

additional feed water is required till the feed water pump is placed in service.

(3) Start the diesel generator and light off the burner using diesel oil with the nor tip which

condition is operated by AIR ATOMIZING with F.O.TEMP. BY-PASS MODE and

burner manual mode.

Before lighting off, never fail to purge the furnace adequately.

(4) Take necessary measures as described in "PREPARATION".

(5) Close valves of the heavy oil lines from the fuel oil tank to the burner manifold and open

valves of the diesel oil line from the diesel oil tank.

(6) Start the FUEL oil pump and open the oil recirculation valve to discharge heavy oil

remaining in the line, burner manifold and oil inlet pipes to burners thoroughly.

B-2

(13)

(7) Set the atomizing air pressure at 5 K and fuel oil pressure at 3 K.

(8) Run the forced draft fan and ignite the burner using the pilot burner.

(9) When the steam pressure has risen to about 2 kg/cm2g, start warming the steam pipe lines

and the feed water pump pipe lines, ant turn on steam to the settling tank.

(10) When the heavy oil in the settling tank has been heated enough to be pumped by the F.O.

pump, turn on steam supply to the oil heater in preparation for changeover from diesel

oil firing to heavy oil firing.

(11) Circulate oil through the oil heater and the oil recirculation line till the oil of the proper

temperature is available in the burner manifold. Then, switch diesel oil firing to heavy oil

C firing and continue pressure raising.

(12) Start the feed water pump as early as possible so that it can feed water to the boiler

immediately when the drum water level should fall.

B-2

(14)

5. Shutting down

(1) Blow all soot blowers before shutting down the boiler whenever possible.

(2) Shut down one burner at a time.

(3) Continue operation of the forced draft fan for a while after shutting down, keeping air

pressure of about 150 mmAq at burner inlet and then stop the forced draft fan and close

the inlet damper

(4) Maintain the drum water level visible about 50 mm in the gauge glass.

(5)When it is necessary to stop the boiler temporarily and keep it in the standby state, ignite

the burner from time to time for sporadic firing to maintain the steam pressure at 5 to 7

kg/cm2g which is lower than the normal working pressure.

(6) In order to maintain drum water level visible about 50 mm in the gauge glass even when

the boiler in cold, raise the water level 70 to 120 mm above the normal water level

before closing the feed water valve.

(7) When the boiler is to be shut down completely, close the steam stop valve immediately

after the boiler stops steaming.

(8) When the boiler pressure has fallen to the atmospheric pressure, open the drum vent

valve.

(9) If it is 4 hours after shut down, the boiler may be cooled with the forced draft fan

operation as the case may require.

But, if possible, such a forced air cooling should be avoided not damage refractory in the

furnace. Do not attempt to cool the boiler by blowing down the hot boiler water or by

refilling the boiler with cold water after blowing down.

B-2

(15)

6. Emergency operation

Water level low

If the water level falls down to 200 mm or more below the normal water level due to failure of

the feed water supply or neglect of the operator, the alarm lamp on the boiler control panel

goes on and simultaneously the alarm buzzer sounds. If the level falls further down to 240 mm

or more below the normal water level, the fuel oil emergency trip valve fully closes cutting of

the fuel supply to the boiler automatically. Then, fully close the feed water valve and the steam

stop valve and shut down a burner completely and stop the forced draft fan.

In this case, never attempt to feed water to the boiler till the boiler has cooled sufficiently,

since, otherwise, there may be a danger of quenching the hot pressure parts with

comparatively cold feed water.

Flame out

In the event of a flame out, immediately close the oil inlet valves and reduce air pressure at

burner inlet so as to present overcooling the furnace.

Prior to relighting burner, purge the furnace adequately following the procedure mentioned in

"Lighting off and pressure raising".

A pilot burner must be used for relighting a burner. Never attempt to light a burner by the heat

from the hot refractory in the furnace.

B-2

(16)

Failure of evaporating tube

A. In case of a tube failure which results in a loss of water so great that the water level can not

be maintained, use the method outlined below.

(1) Shut off oil supply to burner to extinguish the fire. When the tube failure is resulted from

low water, shut off feed water to the boiler closing the feed water valve and the steam

stop valve. This is to avoid the damage that may be caused by quenching hot pressure

parts other than the failed tube with comparatively cold feed water. Refer to "Water

level low".

(2) When the failure of the evaporating tube is resulted from the cause other than low water,

maintain the water level, if possible, at the normal level till the boiler has cooled

enough and then close the steam stop valve and open the drum vent valve.

(3) In either case of the above, keep the forced draft fan in operation to maintain sufficient

air flow to carry the escaping steam out through the stack, adjusting the F.D.FAN

INLET VALVE to such an opening so as to avoid damaging refractory by quick

cooling.

(4) Do not blow down the boiler to lower the pressure rapidly unless the failure is so severe

as to endanger the personnel near the boiler.

(5) Dump the boiler water overboard through the bottom blow valve after cooled enough.

(6) When the furnace has cooled enough to permit a man to enter it, make a thorough

inspection of all pressure parts for any indication of damage. After necessary repairs

have made, apply a hydrostatic test to see whether the unit may be put back in service

or not.

B-2

(17)

B. In case of a leak which does not involve a serious difficulty, the water level should be

maintained and the boiler taken out of service in the normal manner.

(1) Blow soot blowers if circumstances permit.

(2) Switch the combustion control equipment to manual control and reduce combustion rate

following the normal procedure.

(3) Continue air flow through the unit at reduced rate till all combustible gases, vapors, etc.

have been removed.

(4) Feed water to the boiler manually ,maintaining a high level in the water gauge. When the

boiler stops steaming ,open the drum outlet drain valve to drain enough to reduce the

saturation temperature by approximately 65 per hour. When the drum pressure

has fallen to 2 kg/cm2g,open the drum vent valve and when the boiler water has

cooled to about 65, drain the boiler.

Fire inside the casing

Shut off oil supply to the burners immediately and close the forced draft fan inlet vane.

Failure of forced draft fan

In case of a failure of the forced draft fan, oil supply to the burners is stopped automatically

with the fuel oil emergency trip valve.

Close oil inlet valves to the burner.

B-2

(18)

7. Emergency case and measures to be taken

Case Measures to be taken Causes

Drum water level (1) Close F.O. emergency trip

valve.

Shut down burner.

(2) Stop feeding water.

Too low feed water pressure

Improper functioning of feed

water control valve

Improper functioning of feed

water regulator

Faulty water level indication

Boiler tube failure

Flame out (1) Close F.O. emergency trip

valve.

Shut down burner.

(2) Purge furnace and relight off.

Too low oil pressure valve

Too high excess air

Faulty flame eye

Fouled burner tip

Improper atomizing steam

pressure

Drain in atomizing steam

Tube failure (1) Close F.O. emergency trip

valve.

Shut down burner.

(2) In case of low water

-Stop feeding water.

In case of not low water

- Maintain normal water level.

(3) Keep forced draft fan in

operation and reduce pressure

gradually.

(4) Start blowing down at 10

kg/cm2g or less.

(5) Plug off or replace tube.

Too low water level

Tube corrosion

(Improper water treatment)

Tube overheat

(Scale deposit, poor boiler

water circulation)

Too high combustion rate

B-2

(19)

Case Measures to be taken Causes

Fire inside the casing (1) Close F.O. emergency trip

valve.

Shut down burner.

(2) Stop forced draft fan and fully

close inlet vane.

Oil leak from burner

Unburned oil in furnace

Incomplete combustion on

burner

Fire inside the casing (1) Close F.O. emergency trip

valve.

Shut down burner.

(2) Stop forced draft fan and fully

close inlet vane.

Oil leak from burner

Unburned oil in furnace

Incomplete combustion on

burner

Failure of forced draft

fan

(1) Close F.O. emergency trip

valve.

Shut down burner.

(2) Restart forced draft fan.

(3) Purge furnace and relight off.

Failure in electric circuit

Failure of electric motor

Sea water leakage

into feed water line

(1) Reduce boiler load.

(2) Raise pH value and PO43- to

upper limit of allowable range.

(3) Analyze feed water and boiler

water every two hours.

(4) Blown down boiler so as to

maintain chlorine content within

limitation.

(5) Inspect inside of boiler, etc. at

earliest opportunity.

Apply acid cleaning if

necessary.

Leakage in condenser

Faulty water-making equipment

B-3

(1)

BOILER HEATER OPERATION PROCEDURE

The subject ship is equipped with 2 auxiliary boilers. When only one boiler is in service, be sure

that the internal pressure of the other boiler in the stand-by mode will not go down below

atmospheric pressure. If the boiler should be brought into the cold state while still at pressure

and with the steam valve kept closing. The steam drum would turn vacuum and draw in air to

probably suffer the internal corrosion. For the stand-by boiler. use the boiler heater to keep the

boiler internal pressure higher than atmospheric pressure.

1.When Using Exhaust Gas Economizer

Operate the valve so that heating steam flows into the boiler heater for the stand-by boiler.

See following Table 1.

Keep the pressure at 0.5kg/cm2g and above.

Table 1

Valve name Stand-by

boiler

Stand-by

boiler

Boiler heater inlet valve 41B open open

Boiler heater outlet valve 42B open open

Boiler heater leak test valve 43B close close

B-7

(2)

2.When Using Boiler Alone

Be sure that the stand-by boiler pressure is maintained at 2 kg/cm2g and above by

switching on and off the burner. The stand-by boiler will be starting and stopping

automatically. However, keep the boiler pressure at 0.5kg/cm2g and above. Do not use the

boiler heater. See following Table 1 for valve operation.

Table 2

Valve name Boiler in

service

Stand-by

boiler

Boiler heater inlet valve 41B close close

Boiler heater outlet valve 42B close close

Boiler heater leak test valve 43B open open

CC. GENERAL MAINTENANCE

FEED WATER AND BOILER WATER TREATMENT C-1

CARE OF BOILER OUT OF SERVICE C-2

HYDROSTATIC TESTS C-3

BOILING OUT

C-4

WATER WASHING FIRESIDES

C-5

ACID CLEANING C-6

C-1

(1)

1. TREATMENT OF FEEDWATER AND BOILER WATER

Mitsubishi Heavy Industries Nagasaki Shipyard & Machinery Works has a wealth of experience

and excellent industrial research laboratory facilities to bank on as regards the treatment of feed

water and boiler water. It therefore is recommended that any questions or difficulties

experienced as regards the treatment of feed water and boiler water be referred to the Company

for advice.

Control of Feed water and Boiler-water Impurities

With boilers in service, it is recommended that at least once everyday feed water and boiler

water be sampled for analysis and appropriate measures taken for qualitative control. When

sampling boiler water, care is to be exercised so as to take the sample that truly represents boiler

water, by for example cleaning the sampling vessel twice to three times with boiler water

beforehand.

Feed water and boiler water sampled are to be thoroughly and carefully analyzed using an

appropriate analysis equipment, it accordance with instruction given on the use of the equipment.

Every effort is to be made to control oxygen, pH, salt, dissolved solids, phosphoric acid, etc. in

feed water and boiler water to within the specified limits.

Requirements specified for the ships boiler as regards the control of feed water and boiler-

water impurities follow.

C-1

(2)

Feedwater

(1) Oxygen : The oxygen content of feedwater is to be controlled to below 0.5 ppm.

(2) pH : The recommended pH value is 7.0 to 9.0. For the pH control purpose,

however, it is recommended that the target be set at 8.5 to 9.0.

Boiler Water

(1) pH : pH of boiler water requires to be controlled to 10.8 to 11.3.

(2) Salt : The salt content of boiler water (as C1-) requires to be controlled

to 300 ppm as far below as possible, preferably below 150 ppm.

(3) Dissolved solids : Dissolved solids in boiler water require to be controlled to 2000

ppm and as far below as possible.

(4) Phosphoric acid : Phosphoric acid of boiler water (as PO43-) requires to be

controlled to 20 to 40 ppm.

C-1

(3)

1. FEED WATER AND BOILER WATER TREATMENT

Limits of Chemical Concentration

Item Unit Boiler Water Feed Water to Boiler

pH (at 25) - 10.8 - 11.3 7.0 - 9.0

Phenolphthalein

Alkalinity (CaCO3)

ppm Max.500 -

Total

Alkalinity (CaCO3)

ppm Max.600 -

Chloride (C1-) ppm Max.300 -

Total Solid ppm Max.2000 -

Excess

Phosphate (PO43-)

ppm 20 - 40 -

Hardness (CaCO3) ppm - Max.1.0

Oxygen mg/l - Max.0.5Hydrazine mg/l -

(Note) :

(1) Feed water in this table means the mixture of condensate and distilled water to supply

into the boiler.

(2) When only the exhaust-gas economizer is in operation, perform the boiler-water

treatment based on the results of circulating-water analysis.

C-1

(4)

(3) Estimate the pH value from alkalinity tends to give pH readings varying with silica, Ca,

Mg, and other salt contents of boiler water and hence is not necessarily deemed

appropriate : resort to this method only as a means to obtain a rough guide (alkalinity

serves merely as an auxiliary means in determining the pH level).

Also, be sure to control pH to the target value while, on the other hand, keeping

alkalinity at the minimum necessary level.

Limiting the P alkalinity to within a certain range would make it possible to inhibit the

alkali corrosion even if boiler water concentration should take place on the heating

surface, etc.

C-1

(5)

BOILER ANTISCALES AND THEIR INJECTION QUANTITIES (EX.)

1. Boiler Antiscale

The following chemicals of Ameroid Co., ltd. manufacture are to be used.

pH enchanting agent (GC) or KALGEN 459

PO4 enchanting agent (ADJUNCT B) or ALCON 401

(1) GC

Containing sodium hydroxide as its principal ingredient, this chemical is used for controlling

pH of boiler water.

(2) ADJUNCT B

This chemical, the alkaline anti scale with tri-sodium phosphate as its principal ingredient, is

used for controlling PO4 content of boiler water. It serves to prevent the accumulation of

scale deposits as well as to inhibit the boiler steel corrosion.

2. Injection Quantity

(1) Initial injection

Antiscale Initial injection quantity (g/ton) pH & PO4 values

ADJUNCT B Approx.80 PO4 : 20ppm

GC Approx.25 pH : 10.8

(Notes)

1) The injection quantities indicated are calculated with feedwater hardness at zero.

2) In the initial phase of operation, reaction with iron content of boiler steel produces

iron phosphate film on the steel surfaces causing phosphoric acid to remain below

the specified limit. In such an instance, inject additional doses of ADJUNCT B.

C-1

(6)

(2) Makeup injection

According to the results of boiler-water analysis, makeup dose of antiscales are to be

injected with the values indicated in the following table as reference targets.

Antiscale Qty required to raise

P alkalinity

(as CaCO3 ppm) by

10ppm, g/ton

Qty required to raise

Phosphoric acid radical

(as PO43- ppm) by

10ppm, g/ton

ADJUNCT B - Approx.40

GC Approx.8 -

(Notes)

1) The injection quantities indicated are calculated assuming distilled water to be used

as boiler feedwater.

2) The values given are mere theoretical targets and hence require to be controlled as

appropriate for actual boiler load and feedwater quality so that the desired boiler

water quality can be ensured in each particular application.

3. Deoxidizing Agent

For removal and deactivation of residual oxygen in the feed water system, hydrazine (N2H4) is

to be injected into the cascade tank outlet (or feed pump suction inlet) by means of drip-

injection device.

Injection Quantity

In case of 10% concentration of hydrazine solution.

Initial injection : Approx.70 g/ton (at 30deg.C and atm. press.)

Makeup injection : Approx.45 g/ton (at 60deg.C and atm. press.)

C-1

(7)

Boiler Blow down

Blowing down boiler water by operating the blow down valve and replenishing the amount of

water blown down with fresh water is of vital importance of reducing the concentration of

boiler water to satisfactory level for operation. Also, the boiler blow down is just as

important to discharging sludge, oily substance, and other impurities accumulated in the boiler.

The amount of boiler water to blow down and how often to blow down are to be decided

based of factual data, such as the results of boiler-water analysis, turgidity of sampled boiler

water, etc., so that the aforementioned requirements on boiler-water chemistry can be

satisfied.

Makeup-water and Boiler-water Treatment

The boiler disorders caused by inadequate control of boiler water and feed water may be

broadly defined as follows.

(1) Overheating of heat-transfer surfaces due to accumulation of scale and oil/grease

deposits

(2) Corrosion (and caustic embattlement)

(3) Turbine and other associated equipment disorders due to carryover.

Some restrictions, therefore, require to be imposed as follows in order to prevent the above

disorders.

* To cope with (1) above, the hardness and oil/grease content of feedwater require to be

controlled to within allowable limits, as does silicic acid contained in boiler water.

* To deal with (2) above, feedwater pH and boiler-water pH require to be controlled to

allowable levels.

* Salts defy the generalization, some serving to inhibit the corrosion and some promoting the

corrosion. Chlorine (chloride), however, generally promotes the corrosion when present in

a large amount and hence requires to be controlled to as low a level as is practicable.

* To prevent the problem (3), dissolved solids and oil/grease contained in boiler water

require to be controlled to within allowable limits.

C-1

(8)

Restriction of Individual Impurities

(1) Hardness

The formation of scale deposits on the boiler drum and evaporating tube internal surfaces

and the accumulation of sludge within the boiler are attributable, principally, to hardness-

constituting elements carried into the boiler by feedwater.

Leaving the feedwater supply as it is while obviously high in hardness and treating it in the

boiler has potential of having the impurities adhere to heat-absorbing surfaces and also can

cause the rise in antiscale consumption and quantity of dissolved solids.

The best practice dictates, therefore, that the hardness of feedwater be restricted to within

an allowable limit and what is left of the hardness removed through boiler-water treatment

in the boiler.

Specifically, the hardness of feedwater for a 16.0 kg/cm2g boiler is to be controlled to 1

ppm. With makeup water produced by distilling seawater in a desalination plant, assuming

impurities carried over through evaporation to be same as those in raw seawater (of total

salts, Cl=55%,Ca=1.2%,and Mg=3.7%),the hardness brought in per 1 ppm of chlorine

(C) is 0.34 ppm. Then, even with the allowable limit of chlorine at 5 ppm, the hardness

upon evaporation is 1.7 ppm, which suggests that judging from the rate of makeup feed,

restricting the feedwater hardness to within the above mentioned limit is not difficult.

In cases where the distilled-water tank is coated with water cement (definitely not

encouraged) or where there is leakage in the condenser, however, large amounts of calcium

and magnesium can eventually enter the boiler, warranting due precaution.

In some instances the required hardness is specified for boiler water. The hardness values

suggested for boiler water are prone to error and often turn out to be unrealistic. For this

reason and also since the boiler-water hardness should remain about 1 ppm as long as

excess phosphoric acid and pH of boiler water are controlled to the values given in Table 1,

MHI does not make it its practice to specify the hardness requirements.

C-1

(9)

(2) pH Value (Alkalinity)

The boilers are made almost entirely of steel, and iron, beside being susceptible to heavy

corrosion in acidic environments, dissolves in neutral pure water to produce iron

hydroxide as follows.

Fe + 2H2O = Fe(OH)2 + H2

Iron Water Iron-hydroxide Hydrogen

When iron has dissolved in pure water, pH with Fe(OH)2 at the saturation point is 0.9.

The larger the pH value, I.e., the higher the alkalinity, the more sharply the amount of

iron dissolution goes down. It therefore is necessary for the pH value to be maintained

constantly at a high level in order for iron being prevented from becoming corroded. A

word of caution is deemed in order because pH at too high a level can backfire in the

from of caustic corrosion or caustic embattlement or carryover.

Also, it is known that boiler water is not uniform in concentration throughout its body.

So, everything considered, the reasonable proposition is that pH of boiler water should

be maintained at 10.8 to 11.3.

Alkalinity may be deviled into total alkalinity and active alkalinity. Included in the total

alkalinity reading are caustic soda, potassium carbonate, and potassium bicarbonate, all

these being put together. The active alkalinity, on the other hand, called phenolphthalein

alkalinity (or P alkali, in short), represents the amount of alkali high enough in strength to

turn phenolphthalein indicator in color.

It is the active alkalinity that serves as a rough guide to the pH level.

With all the foregoing in consideration, therefore, the phenolphthalein alkalinity as

CaCO3 is to be controlled to about 50 to 300 ppm when boiler water is in excess of

1000 ppm in concentration and to about 30 to 100 ppm when boiler water

concentration is below 1000 ppm.

C-1

(10)

(3) Dissolved Oxygen

The dissolved oxygen constitutes a single greatest factor in causing corrosion, being

responsible for boiler steel corrosion in well more than 50% of the time.

In reaction between water and iron, which is defined as Fe + 2H2O = Fe(OH) 2 + H2,

hydrogen thereby produced is absorbed in metal surface to serve as a negative factor in the

reaction. When oxygen is present, however, it causes hydrogen to disappear by oxidation,

so the reaction progresses toward the right term of the formula with the dissolution of iron

taking place continuously. In addition, iron hydroxide turns into ferric hydroxide by being

oxidized by oxygen, ferric hydroxide settling down to produce rust, thereby causing the

corrosion of iron to progress intermittently.

2Fe(OH)2 + 1/2 O2 + H2O = 2Fe(OH)2

Iron Ferric

hydroxide hydroxide

The pitting corrosion, found concentrated under the drum waterline, is attributable to the

dissolved oxygen. Iron transported from the feedwater piping into the drum, plus iron oxide

produced within the drum, accumulates as deposits or settles down to cause the pitting.

The presence of carbon dioxide gas together with dissolved oxygen in saturated-steam

piping or condensate piping can cause a total corrosion. Carbon dioxide gas is produced

by dissolution of bicarbonate in makeup feed as well as by dissolution of sodium carbonate

within the boiler.

2NaHCO2 Na2CO3 + H2O + CO2Sodium Sodium Carbon

bicarbonate carbonate dioxide gas

Na2CO3 + H2O 2NaOH + CO2Sodium Caustic Carbon

carbonate soda dioxide gas

C-1

(11)

The use of sodium carbonate as boiler antiscale, therefore, is not recommendable.

Carbon dioxide gas dissolves in water and acts as carbonic acid but does not cause by

itself so heavy corrosion. If there is oxygen together, however, the effect of the dissolved

carbon dioxide gas becomes pronounced, as it to play a role of some oxidizing medium as

indicated by the following reaction formulas.

Fe + 2H2CO3 = Fe(HCO3) + H2 (1)

Carbonic Ferrous

acid bicarbonate

2Fe(HCO3)2 + 1/2 O2 + 5H2O = 2Fe(HCO3) + 4H2CO3 (2)

Ferric

hydroxide

The dissolved oxygen in feedwater, therefore, requires to be strictly controlled, preferably

to below 0.25 ppm for 16.0 kg/cm2g boiler even though it is specified to be 0.5 ppm.

For removal of dissolved oxygen, it is recommended that volatile hydrazine be continuously

added to feedwater. Hydrazine reacts as follows

N2H4 + O2 N2 + 2H2O

C-1

(12)

(4) Chlorine (Chloride)

Salts, when present in large quantity, raise the electric conductivity of liquid to promote the

corrosion and hence require to be controlled to as low a level in quantity as is practicable.

Feedwater containing too large an amount of magnesium salt can produce the sediment of

magnesium hydroxide upon entering the boiler, and this is said to raise the corrosiveness of

boiler water by bringing down the boiler water pH value.

All the same pH and oxygen remain the greatest factors in causing the corrosion. and the

measurement of chloride is performed more or less to obtain a rough idea as to the amount

of dissolved solids contained.

The relation between the dissolved solids and chlorine ion, though subject to some

variations depending on the water quality or performance of the water-making device, can

be established by measuring these elements in boiler water of each individual boiler

beforehand. Then, it is possible, as well as does no harm for practical purposes, to estimate

the amount of dissolved solids. It is assumed that the concentration of boiler water, as long

as it is controlled using the amount of dissolved solids as a yardstick, can not rise to such a

level as to greatly promote the corrosion except in special instances. The feedwater

Committee, therefore, sets forth no requirements in particular as to the allowable limit of

chlorine.

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(5) Oil/Grease

Oil/grease coming out of auxiliary machinery, especially those started in reciprocating

motions, enters feedwater and then adheres to the boiler heat-absorbing surfaces to cause

the overheating trouble there upon oxidation.

Also, since boiler water is alkaline, both animal and vegetable oils are liable to be emulsified

in it. The results are foaming of boiler water and degradation in steam purity.

Although the allowable limit is specified for the amount of oil/grease in boiler water in some

instances, it seems highly likely that such an oil/grease will be several-hundreds fold greater

in concentration at the boiler-water surface than the mean oil/grease content. As

specifying such a limit is deemed to make not so much of sense, it is only requested that

feedwater and boiler water should be controlled so that the amount of oil/grease can be

kept to zero as far as is practicable.

(6) Silica (Silicic Acid)

The scale that contains silica is the poorest in heat transfer and thus the most harmful to

boiler operation.

Also, what is called the silica carryover takes place, in which silica carried in steam enters

the turbine and deposits itself on the turbine blades as hard scale encrustation. This is the

single most nettlesome phenomenon, which warrants a serious consideration in connection

with the care of high-pressure boilers.

For a 16.0 kg/cm2g boiler, it is recommended that the silica content of boiler water be

controlled to below 50 ppm to cope with both the scale formation and silica carryover.

Silica acid should be no cause of concern so long as distilled water produced from

seawater is used as makeup feed in nearly all the instances. When water is obtained from

land, however, necessary precautions are to be taken in this respect.

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(7) Dissolved solids

The larger the amount of dissolved solids in boiler water, the more dampened the steam

becomes, to the point where a large amount of solids are carried in steam as carryover to

the turbine.

The tendency of such a carryover varies with the steam evaporation rate, boiler type, and

performance of the steam separator in the steam drum, as well as with constituents of solids

even if the solids are same in quantity.

Although the relation between these factors still defies quantitative definition, at least a

rough standard can be given for safe and practical operational purposes from the past

experience. In normal operation, the amount of dissolved solids is to be kept to below

2000 ppm.

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2. CARE OF BOILER OUT OF SERVICE

For the out-of-service boiler, exercise adequate care to minimize the corrosion of its pressure

part and also inspect it closely.

In cases where the boiler is put out of service for 24 hours or more, either fill the boiler

completely with water (wet storage) or drain the boiler of water and thoroughly dry it (dry

storage). Whether it is the wet storage or the dry storage, the purpose is to eliminate air and

dissolved gas from within the boiler for prevention of boiler internal surface corrosion.

Also, when placing the boiler in storage, be sure to keep the gas side completely clean. Any

residual soot deposits on evaporating tube surfaces could absorb moisture from air and cause

the surface corrosion.

Wet Lay-up Method

The wet lay-up is preferable as it requires less preparation, the boiler can quickly be returned to

service, and protection of the waterside is adequate. This method can be safely used for a lay-

up of any length of time, if the fire room temperature is not below freezing.

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(1) When the boiler is being cooled down after shutting off firing ,boiler compound

(Na/PO4=2.8 mole ration) of trisodium phosphate (Na3PO4) and dosodium phosphate

(Na2HPO4) ,and hydrazine shall be added to the boiler water by the chemical injection

system in such a manner as to make the boiler water of phosphoric acid (PO43-) of about

50 ppm and hydrazine (N2H4) of 100 - 200 ppm (pH is about 10.510.6). The

boiler water should be kept in high alkalinity to protect the boiler from corrosion. Since

the boiler water density during the wet laid-up period is very high compare with that of

ordinary operating condition.

The boiler should be carefully blown down when starting operating to bring the boiler

water concentration down to the normal value (with the boiler water treating limits).

For this ,some amount of make-up water is necessary and the distilled water should be

prepared beforehand accordingly.

(2) When the pressure has gone down to nearly zero, open the steam drum air-vent valve.

(3) When the pressure is almost off the boiler, fill the boiler with distilled water until it issues

from the air vent valves, then close the valve.

(4) Put a hydrostatic pressure of 3.5 to 5 kg/cm2g on the boiler. Hold this pressure until

the boiler has cooled to fire room temperature, then bleed the boiler, using the air vent

valve, to be sure all air is out. Hold a hydrostatic pressure of about 2 to 3.5 kg/cm2g

on the boiler.

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(5) Maintaining the alkalinity at a uniform level throughout respective boiler parts is an

important consideration, so periodically sample boiler water for analysis during the

storage and replenish what have been spent of alkalinity and sodium sulfite.

(6) In case the atmospheric temperature threatens to fall below the freezing point, take care

to maintain the boiler room temperature at higher than 5 so as to prevent the boiler

water from freezing.

(7) When interrupting the wet storage to put the boiler back into service, bring down the

steam drum water level.

Dry Lay-up Method

In case the wet lay-up method cannot be performed, resort to the dry lay-up method.

(1) While the boiler still remains warm, drain out boiler water and open up the boiler for

ventilation until completely dried internally.

(2) Remove the end plate of the water wall lower header, to check and make sure that no

residual water remains collected inside the header.

(3) If necessary, burn coke or charcoal in a container within the furnace to promote the

internal surface drying.

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(4) When completely dried, put quick line or calcium chloride in a shallow dish for

placement in the drum and header and then close the end plate and manhole cover.

Use 2 to 5 kg of moisture absorbent for 1000 kg of boiler water when quick line is

employed and 1.8 kg of silica gel for 1000 kg of boiler water, as a matter of standard

practice.

(5) Be sure to close securely all the air-inlet openings into the furnace and provide the cover

on the stack.

(6) Check the moisture absorbent every one to two weeks at the beginning and every one to

three months thereafter at the circumstances call for and renew deteriorated absorbent.

Other Cares for Protection

Do not forget the protection for the gas side, as well as for the boiler-water side. Have the

gas side cleaned of soot or dust while in preparation for the storage.

Soot or slug becoming moistened by moisture of air can cause the corrosion the gas side.

Be absolutely sure to close the furnace and F.D.F. inlet vane and cover up the stack to

prevent the ingress of air or moisture.

Periodically open and close the F.D.F. inlet vane to make sure that it can operate successfully.

Maintain the boiler gas side and casing in the dry state as far as is practicable.

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3. HYDROSTATIC TESTS

Hydrostatic test pressure should not be higher than necessary to prove the intended test. The

maximum allowable hydrostatic test pressure should be carried out only for design pressure.

See the hydrostatic test planning particulars included in this Manual for the maximum test

pressure to employ. The specified pressure is to be applied to ensure the boiler structural

integrity, only for inspection by applicable ship classification society surveyor.

(1) To check the boiler and fittings for leaks, a test pressure of about 85 percent of the safety

valve popping pressure is sufficient. Caution should be used to avoid accidentally raising

the pressure enough to open a safety valve.

(2) Hydrostatic tests up to normal feed line pressure may be applied with the feed pump if

handled carefully to avoid sudden changes in pressure, producing shock or impact stresses

in the boiler. For maximum test pressure use the test pump.

(3) A commonly used chemical injector has a pressure connection from the feed line to the

boiler compound vessel and a discharge line from the vessel to the boiler. This type of

chemical injector can be used to apply hydrostatic pressure from the feed line. Ordinarily

the lines are O.D. 12 to 20 mm lines. It is easier to control the pressure with the small

valves than with the larger feed valves.

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(4) Before applying a hydrostatic pressure, it is advisable to cool the boiler to approximately

fire room temperature. The water used for filling should be warmer than the boiler metal, to

avoid moisture condensation on the fireside. Hydrostatic pressure should not be applied if

the temperature of the boiler and filling water is less than 20 deg. C.

(5) Place test clamps (gags) on all safety valves, if the test pressure is to be higher than 85

percent of the safety valve popping pressure. Safety valves should never be opened by

hydrostatic pressure.

(6) The pressure gauge to be used should be checked, before applying the maximum test

pressure.

(7) When filling the boiler open the vent valves on the boiler drum, to bleed off all air, close the

valves when water runs out.

(8) Before lowering the pressure, take up the slack on the nuts of the inspection hole and

manhole fittings, were new gaskets have been fitted. The nuts should be pulled just snug

with the wrenches supplied for the purpose. Do not use a pipe or other extension on the

wrench handle.

(9) When inspection is completed, open the vent valves and lower the pressure slowly by

cracking a drain valve.

(10) Remove the safety valve gags, replace the lifting lever and easing gear.

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4. BOILING OUT

If the presence of oil is found on the waterside of the boiler, it must be removed by boiling out.

This is necessary after assembly of a new boiler, after completion of repairs requiring extensive

replacement of tubes, or if oil has entered the feed water from some other source.

Boiling out is also a quick and efficient method of removing various types of scale. The

chemicals to be used and the strength of solution required, depends on the character of the scale.

Consult the boiler water chemist.

Boiling out to remove oil requires the use of a fairly strong caustic solution. One such solution

is 1 kg of caustic soda and 1 kg of tri-sodium phosphate, for each 1000 kg of cold water

required to fill the boiler. This chemical solution is sufficient to remove ordinarily compounded

lubricating oils or the usual protective oil coating applied to tubes before shipment.

Straight mineral lubricating oils used for high temperature engines requires stronger solutions. If

such oil is present in the boiler used 4 kg tri-sodium phosphate and 4 to 5 kg caustic soda per

1000 kg of water. In addition it is advisable to add detergent (wetting agent) amounting to

about 0.5 percent of the boiler water. There are other chemical solutions which can be used.

There are many satisfactory compounds for boiling out, they are sold under various trade names

by reputable firms. When such compounds are used, follow the manufactures instructions.

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Steaming Method

This is a method in which steam is injected by way of a temporary piping externally connected to

the air-vent valve, for soda boiling. Water is to be discharged by way of the bottom blow-

down valve and through a temporary discharge piping. The discharge piping is to be connected

to the boiler water sampling tank, which is requires for inspection or analysis of boiler water.

(1) Inject chemicals into the water wall tubing as required, using the chemical injection device.

Dissolve the chemicals in clean water, in proportion to the weight of water required to

completely fill respective boiler parts, for injection. See the planning particulars included

in this Manual for the weight of water required to fill each of the boiler parts.

(2) Upon finishing the injection of chemical solution, gradually blow in steam in such a manner

as to permit condensed water to collect until the boiler is completely filled with water to the

point where water begins to overflow by way of the air-vent valve.

(3) Maintain the boiler pressure at about 3.5 kg/cm2g and adjust each air-vent valve so that the

quantity of overflowing water from each individual air-vent valve and bottom blow-down

valve will be approximately in proportion to the quantity of water in each corresponding

boiler part.

(4) Determine the progress in removal of oil through test of sample water taken from the

discharge piping. Analyze the sample water for alkalinity and then add chemicals required

to maintain the chemical concentration at the specified level : by so doing, continue the soda

boiling until no trance of oil can be seen in the sampled water. The oil content can be

detected by examining the surface of cooled sample water for sign of oil. If possible

however, analysis by ether method, etc. should be in order.

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Firing Method

If steam and electric power are available and the auxiliaries are ready for service a boiler can be

boiled out using a light fire. When the firing method can be used, it is much simpler and does

not require temporary piping.

The quantity of solution to use should be figures for the weight of cold water required to fill the

boiler to normal steaming level.

(See Design Data.)

(1) Dissolve the chemicals in water and inject into the boiler with the compound ejector.

(2) Close the boiler and fill to the normal starting level.

(3) In cases where the boiler is of new construction with new refractory in it, avoid the sharp

thermal expansion of the refractory by preheating the furnace internals by burning firewood

inside the furnace for 3 to 4 hours or by firing the burner intermittently.

(4) Ignite and shut down one burner using the smallest-capacity burner tip, repeatedly until the

pressure is gradually raised to the level corresponding to 85 to 88% of normal operating

pressure. Maintain the pressure at that level, for soda boiling. If necessary to maintain

the pressure, intermittently fire the burner.

(5) If the refractory is new, alternate the burner at fifteen minute intervals.

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(6) When the boiler is thoroughly heated, raise the water level slowly to about 75 to 100 mm

above normal operating level, then give a surface blow followed by several short bottom

blows to bring the water level 30 to 50 mm below normal.

(7) Refill the boiler slowly, until the water level is reached to about 75 to 100 mm above

normal, and additional chemical based on the approximate amount of water blown down.

(8) Perform the soda boiling continuously for 24 to 48 hours, blowing down boiler water every

6 to 8 hours through the blow-down valve by 100 to 150 mm on the level gauge each time.

3.2 Wash and Inspect

(1) After boiling out is completed by the firing method, blow down the boiler through the

water drum bottom blow off valve while the boiler is fairly warm. Discharge the water

overboard, to avoid damaging paint in the bilge by the strong caustic solution.

(2) Open up the boiler and wash it down with a high pressure water hose, playing the hose

into all tubes.

(3) Carefully inspect the boiler, and if any trace of oil remains, repeat the boiling out process.

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5. WATER WASHING FIRESIDES

Slag is a mixture composed of sodium sulfate or a mixture of sodium sulfate and vanadium oxide,

and lesser amounts of the oxides of other impurities.

When burner is kept in proper adjustment, the burner tip kept clean and in good condition, and

the soot blowers operated at correct intervals, slag formation may be slowed down. However

slag formation will eventually accumulate on the tubes and should be removed before it has

bridged over between tubes.

A water washing schedule should be set to coincide with normal fireside cleaning. Operating

practice will indicate at what intervals of fireside cleanings water washing is necessary.

Since slag is soluble in hot fresh water, hot fresh water is sprayed on the slag encrusted tubes

with a lace, using sufficient force to soften the slag and knock it off the tubes.

There are two methods in water washing. One is to use a hand nozzle and the other is to utilize

the soot blower in spraying hot water.

The former permits concentrated washing of important points so that effective washing can be

done with relatively small quantity of water resulting in less moisture of the boiler ; but much time

and labor is required. With the latter, washing can be done easily in a short space of time but it

requires relatively much water resulting in larger moisture of the boiler.

Water washing is usually carried out at a dock. A member of the crew can do it quite easily.

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If preparation has been made in advance while the boiler is cooling, water washing will be done

in 6 - 8 hours although it depends on the extent of dirtiness.

The following is the order of process of water washing the fireside with a hand nozzle.

(1) Prepare an apparatus to supply adequate quantity of hot water and a hose and nozzle for

spouting hot water.

(2) Remove casing access doors and dusting panels to facilitate the work.

(3) Provide a means for immediate and constant draining of the waters and the removal of the

sludge, resulting from washing down.

(4) Water under 5 kg/cm2g and at a temperature of 80 deg. C should be sprayed on to the

tubes, using an armored hose. Work from the top of the boiler down, in cases where slag

removal is extremely difficult, secure from washing, and allow the water to soak into the

slag for a period of 30 minutes to one hour. Then continue washing down the tubes.

(5) Attention should be paid not to let washing water penetrate behind the refractory. It will

be effective to lay a sheet of canvas on the furnace floor. If small quantity of water is

absorbed by refractory and heat-insulating materials, the bad effect will be removed by

slowly drying soon after finish of washing.

(6) Preferably complete the washing with warm water in short time : it is not desirable to

continue the washing over 8 hours.

(7) As soon as possible after washing is completed, light off the boiler at minimum F.O. press.

The drying out operation should be done very slowly and should be continued until the

boiler is thoroughly dried out. When the boiler has entirely been washed, the drying

should be made at least for 12 hours.

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6. ACID CLEANING

Thanks to development of good inhibitors, it has become possible to effectively remove scale on

the waterside of the boiler by acid cleaning.

However, acid cleaning requires a suitable treatment according to actual conditions of the boiler,

otherwise it will not only damage the boiler but also be attended by dangers. So this work

should be done by specialized constructors having experienced and competent personal with

proper equipment. It is desirable for the work to be done under the leadership of Mitsubishi,

Nagasaki Shipyard, if possible.

Boiler operators should have a knowledge of the following general items.

6.1 Equipment

The following devices should be prepared for the acid cleaning.

(1) An acid filling tank of sufficient capacity to hold the prescribed amount of acid and

inhibitor.

(2) One centrifugal acid filling and circulating pump with bronze impeller designed to deliver

a minimum of from 0.2 to 0.4 m3/min at 35 mth. or of such capacity as so fill the unit in

not more than 2 hours.

(3) Suitable temporary piping and fittings to connect both the pump and tank to the boiler.

(4) A typical cleaning solution would contain 28 percent to 34 percent hydrochloric

(muriatio) acid, an inhibitor and water. The amount of acid used would be roughly 10

to 20 percent by volume of the volume of water necessary to fill the component to be

cleaned. See Design Data.

Selection of the concentration of acid used (one to six percent by weight for any one

unit) depends upon the type and amount of scale or rust and other impurities to be

removed.

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Special attention must be given to ensure that the acid solution is not enriched by ferric or

cupric ion, which can be caused from the removed scale or deposits containing a large

portion of ferric or cupric oxide.

This will impair the effect of the inhibitor. In such a condition, keep the acid solution

below the