TI EcoStream

EcoStream

Technical information for bilge water treatment

Inside view

3 Summary

4 The EcoStream bilge water treatment systemOverviewSystem requirementsSystem benefits

6 Towards cleaner oceansWhat is bilge water?Bilge water treatmentBilge water legislation

8 Stable emulsions in bilge waterWhat are emulsions and suspensions?Chemical usage aids stabilizationEffect on separation performanceMechanisms for emulsion breakdown

10 EquipmentOperating principleKey components

13 Optional components

14 Flow diagram

16 Retrofitting

16 Documentation

16 Classification

16 Spare parts, service and support

The EcoStream bilge water treatment system from Alfa Laval is a reliablefully automated, single-stage centrifugal separation system to clean oilywastewater on board vessels at sea and at land-based power plants.

Alfa Laval EcoStream

2 Alfa Laval Marine & Diesel Equipment

SummaryBilge water must be treated to reduce the oil content to levels that meetinternational regulations for release into the environment. This is critical to keeping the world’s oceans and their vast marine ecosystems healthy and productive.

The Alfa Laval EcoStream bilge water treatment system is a centrifugal separation system for bilge water treatmentthat has been approved by the International MaritimeOrganization.

This system generally cleans bilge water to less than fiveparts per million (ppm) oil in water. It operates at flow rates ofup to 2,000 liters per hour to meet even the toughest bilgewater treatment applications.

As a major equipment and technology supplier to the marine industry, Alfa Laval understands the requirements of all treatment systems on board vessels.

We use equipment and technology know-how to buildsolutions of all kinds for cost-effective and efficient operationof vessels – from engine room applications including oil treat-ment and fuel conditioning to waste disposal applications,including bilge water treatment.

Our aim is to work continuously to improve customerprocesses – time and time again.

This document provides technical information about the Alfa Laval EcoStream bilge water treatment system. It includes information about the bilge water separationprocess, advances in system design, system benefits and a description of equipment.

Benefits for owners and operators• Reduced operating costs thanks to low maintenance,

automated control, no waste disposal and an absence of filter elements that require replacement.

• Reliable, always-available system. Operates continuously,regardless of variations in feed, oil shocks and roughweather conditions.

• Easy to operate. Automated control and monitoring systemintegrates with existing Alfa Laval systems, providing asingle user-friendly interface.

• Safe operation. A key lock switch can be set in manual or locked position to ensure that only the individualresponsible for environmental compliance may authorizeoverboard discharge.

Benefits for designers of ships and power plants• Compact, modular, easy-to-install system saves time,

space and money.

• Continuous, single-stage operation requires less holdingtank volume and provides more space for payload.

• Easy integration with existing communications systems on board.

Alfa Laval Marine & Diesel Equipment 3


The Queen Mary 2 is equipped with two EcoStream bilge water treatment systems.



Alfa Laval EcoStream.

The Alfa Laval EcoStream bilge water treatment systemCleaning of bilge water poses distinct challenges. Not only does the composition and flow of bilge water constantly change, making continuous and efficient treatment difficult, but treatment on board also presents another set of constraints.

Treatment methods must meet individual ship requirementsand demands for safety, reliability, compactness, automation,low maintenance and the ability to withstand rough weatherconditions. In addition, performance of the treatment systemcan vary depending on the oil content and the size of thedroplets or particles present in the water and on variousoperating conditions.

Centrifugal separation has proven to be a reliable, efficientand flexible method for continuous removal of oil and othercontaminants suspended in the bilge water on board shipsand at land-based power plants.

OverviewThe EcoStream bilge water treatment system from Alfa Lavalis a centrifugal separation system for treatment of large bilgewater volumes at sea. EcoStream operates at flow rates ofbetween 1,500 and 2,000 liters per hour and usually cleansbilge water to less than 5 ppm.

EcoStream is easy to install for any new or existinginstallation. It does not require large bilge water holding tanks. This increases payload capacity. Compared to con-ventional bilge water systems, EcoStream significantlyreduces operating costs, thanks to automation and remotecontrol. In addition, there is no expensive filter elementreplacement required.

EcoStream enables cleaning of bilge water under a widerange of real operating conditions. It complies with the Marine Environment Protection Committee Resolution, MEPC 107(49), of the International Maritime Organization(IMO), MED 96/98/EC. EcoStream is not only certified bythese organizations, but has proven its high level of per-formance under real operating conditions, normally below5 ppm – even when subjected to oil shock or rough weather.

System benefitsCompact, modular and flexible designThis provides great flexibility to install the unit in a convenientlocation. A wide range of options for functionality, remotecontrol and other features adds more flexibility.

Easy to installThis simple, plug-and-play installation of this factory-testedmodule makes it easy to install. Pipe connections locatedunderneath the unit make EcoStream easy to install.

Faster, more secure commissioningPre-tested, pre-installed and pre-approved components for allsystem functions make commissioning quick, easy and muchless expensive than buying separate components anddesigning a bilge water treatment system.

Easy to operateAutomation and remote control make EcoStream a user-friendly, start-and-forget system. The process controller also shares the same user interface as the Alfa Laval Fuel

Conditioning Module and Separation Unit controllers,facilitating ease of operation.

Easy to access and maintainBuilt-in service areas facilitate inspection and maintenance. A central pillar houses all motor starters and the advancedprocess controller, making the EcoStream unit easier toservice and easier to operate than other units available.

More uptime, less maintenanceMaintenance-free components, automation and remote con-trol increase operating time and decrease service disruptions.Durable components contribute to longer service intervalsbetween inspections.

Lower installation and operating costsThanks to pre-testing, installation requires less time andmoney than installation of separate components. Automationand remote control reduce operating costs.

Technical supportAll spares, service and sales engineers are available throughthe Alfa Laval International Service Network.



Dimensions

1768

mm

750 mm

1070 mm

1810 mm

1450

mm

635

mm

Access area

Towards cleaner oceansBilge water generated on board ships is a major environmental concern for the shipping industry.

Regardless of its source, bilge water must be treated toreduce the oil content to levels that meet international regula-tions for release into the environment. This is critical tokeeping the world’s oceans and their vast marine ecosystemshealthy and productive.

Efficient bilge water treatment minimizes the impact of shippropulsion on the marine environment as well as the heavyfines that ship operators can face for pumping oily bilge wateroverboard.

Efficient treatment also reduces the need for and cost ofwaste disposal ashore. Over the years, waste disposal costshave continued to climb as local authorities enforce stricterlaws for the land-based companies that process this waste.

Alfa Laval’s bilge water treatment solution is superior to manycompeting technologies with respect to the volumes of wastegenerated.

What is bilge water?Bilge water collects in a ship’s bilge wells, which are locatedin the lowermost part of the vessel just above the hull. Thewells receive water and mechanical fluids from operationalsources, such as technical rooms, propulsion systems anddifferent machinery.

Bilge water also contains fluids from machinery spaces, internal drainage systems, sludge tanks and various othersources.



Cleaning andmaintenance

Drainsand leaks

Water from purifiersludge tanks

Water from wasteoil tank

Condensatefrom air coolers

Bilgepump

Tankoverflows

Incidents

Bilge well

Clean wateroverboard

Bilge water tanks Bilge watertreatment

Bilge well

Bilge water containsa mixture of waterand fluids from various sources onboard that is treatedfor clean waterdischarge overboard.

The definition of bilge water is thus much wider in scope than merely the contents of a ship’s bilge, the enclosed areabetween the frames where the sides of the vessel curve in toform the bottom.

In simple terms, bilge water contains two types of sub-streams: (1) flows that are reasonably continuous and pre-dictable, and (2) flows that are intermittent in nature and diffi-cult to foresee. The first category includes water from theseparator sludge tank and water from cleaning activities inthe ship’s engine room. The second category may includesoot water, leakage and incident spills from tanks andmachinery spaces.

Bilge water is thus composed of a mixture of water, deter-gents and other chemicals, fuel oil, lubricating oil, hydraulicoil, cat fines, oil additives, soot and dirt. This mixture is col-lected in the bilge water holding tank, which generally ismaintained at an elevated temperature. This high temperaturefacilitates primary gravity separation, preferably of the two- orthree-stage type, in the bilge water tank. Here, oil rises to thetop and particles settle on the tank bottom, generally dividingbilge water into three distinct layers in the tank:

• Top layerThis contains most of the oil and organic solvents and con-stitutes a small portion of the total tank volume. Skimmingthis top layer for separate treatment is recommended.

• Middle, or main, layer This aqueous phase contains water polluted by oil, chemi-cals and particles in emulsified form. This is fed to the bilgewater treatment system.

• Bottom layerThis contains solids and heavy sludge, which should alsobe removed for separate treatment.

Bilge water legislationBilge water treatment is an environmental application thatmust meet stringent requirements of international legislation.Disposal of untreated bilge water into our oceans is strictlyprohibited by international law and subject to heavy fines,especially in sensitive waters.

Current MARPOL legislation stipulates that separated bilgewater containing 15 ppm or below oil in water can be dis-posed into international waters. Some national, regional andlocal authorities, especially those governing sensitive waters,have more stringent regulations. In the United States and inthe Baltic and North Seas, for instance, disposal of separatedbilge water is only permitted at least 12 nautical miles fromshore.

The International Maritime Organization (IMO) resolutionMEPC 107(49) specifies how to type approve equipment used on board ships. The resolution complies with theEuropean Marine Equipment Directive, MED 96/98/EC.

Many manufacturers have succeeded in meeting the speci-fied requirements for equipment certification, but much of this equipment falls short of delivering the high separationefficiency required under real operating conditions for bilgewater discharge.



Water

Oil

Particles

Fresh water

Seawater

Heavy fuel oil

Lube oil

Hydraulic oil

Organic

Inorganic

Emulsifying, corrosive

Other

Emulsions,suspensions

Chemicals

Bilge watercomposition.

What are emulsions and suspensions?By definition, an emulsion is a mixture of two immiscibleliquids. An oil-in-water emulsion consists of small oil dropletsdispersed in a continuous water phase. A suspension is amixture in which solid particles are dispersed in the con-tinuous water phase.

Emulsions, or small droplets of one liquid (the dispersedphase), can form in the other liquid (the continuous phase)under agitation, such as during pumping or throttling invalves. Droplets of oil dispersed in water generally coalesce,or combine, into larger droplets because oil is not soluble in water.

Increasing the droplet size helps facilitate separation. The presence of surfactants, such as detergents, soaps and other surface-active compounds, however, maycontribute to stabilization of small oil droplets. This makes separation very challenging. High centrifugal force is then required to separate the small droplets that do not spontaneously separate when subjected to gravita-tional force.

Emulsion stabilizers may consist of:

• Low molecular weight surface-active compounds, orsurfactants, that reduce the surface tension of the oil-waterinterface and thereby create small droplets that contributeto emulsification.

• Polymers and other macromolecules form a film around the emulsion droplet to establish a physical barrier tocoalescence and thereby stabilize emulsions further.

• Fine particles can accumulate and adsorb at the oil-waterinterface to form a physical barrier around the emulsiondroplets.

Chemicals usage aids stabilizationEmulsion stabilizers may originate from a variety of sources inthe engine room – from the use of cleaning detergents, fromlube oil additives and so on. Clearly, the use of chemical sub-stances on board is excessive.

Chemicals on board are used for: cleaning and maintenance,treatment of water, improving fuel quality, and improving thequality of lubricating oil.

What used to be lubricating and hydraulic oils of relativelyelemental composition, based on simple mineral oils, are nowcomplex formulations, sometimes based on synthetic oils andincorporating a variety of additives.

Modern lubricating and hydraulic oils have a greater ability totake up water due to the action of detergents. Likewise,cleaning chemicals have a great ability for oil and dirt uptake.

Stabilizers may also occur naturally in the oil. These stabilizersconcentrate at the oil-water interface and lower the interfacialtension, thus stabilizing the liquid mixture.

Some chemical residuals generally end up in a vessel’s wastetreatment system or holding tank. The bilge water treatmentsystem, in particular, processes a heavy load of chemicalresiduals.

Chemical usage in the engine room inevitably causes the for-mation of stable emulsions and suspensions as well as someform of environmental impact. Most chemical manufacturersclaim that their products do not stabilize emulsions in bilgewater. But the use of surface-active chemicals make manyproducts contribute to the formation of stable emulsions.

Usage of chemicals always causes some type of compromisebetween cleaning efficiency and separation efficiency on theone hand and environmental friendliness on the other.

Alfa Laval strongly recommends the use of quick-separating,environmentally friendly and non-toxic detergents. Choosingchemicals that are compatible, non-toxic, biodegradable andnon-emulsifying, helps prevent problems downstream.

Effect on separation performanceThe formation of stable emulsions and suspensions affectsseparation efficiency. Many conventional technologies fail tosplit stable emulsions and remove suspended colloidal parti-cles from the water phase. This often results in equipmentmalfunction because separation of oil below 15 ppm is notachieved or because of clogging from excessive solids.

Understanding the factors that contribute to the formationand breakdown of stable emulsions is essential to under-standing why centrifugal bilge water treatment systems canefficiently separate bilge water, despite a high concentrationof stable emulsions.

Stable emulsions in bilge waterSeparation of oil and particles from bilge water is becoming increasinglychallenging, due to the presence of stable emulsions and suspensions. Emulsion and suspension formation and stability are of major concern in the context of bilge water treatment.



Mechanisms for emulsion breakdownThere are different mechanisms for emulsion destabilizationand breakdown, including coalescence and flocculation.

• Coalescence is a process where two or more dropletscollide, resulting in the formation of one larger droplet.

– A high centrifugal force induced in a centrifugal separatorgreatly contributes to the coalescence of small droplets.

– Elevated temperature accelerates the rate of coalescenceby increasing the probability of the droplets to collide andby decreasing the viscosity of the continuous phase.

– Chemical demulsifiers decrease or cancel the repulsiveelectrostatic forces between droplets in an emulsion,causing droplet coalescence.

• Flocculation is a process by which two or more particlesaggregate without losing their individual identities.

– A high centrifugal force induced in a centrifugal separatorgreatly contributes to the flocculation of small particles.

– A high alkaline pH value promotes flocculation. The pHvalue provides a measure on a scale from 0 to 14 of theacidity or alkalinity of a solution.

– Chemical flocculants decrease or cancel the repulsiveelectrostatic forces between particles in a suspension,thus promoting flocculation.



What parameters affect separation efficiency?Centrifugal separation relies on the difference in density amongthe various components present in emulsions or suspensions.

Stokes’ Law (below) describes the settling velocity (vg) of aparticle or droplet when subjected to gravitational force, such asstatic settling in a tank, which in turn determines the separationefficiency. The general formula is:

νg = d2 (ρd – ρc)

g18 µc

νg the sedimentation velocity due to gravity

d the diameter of the dispersed droplet/particle

ρd the density of the dispersed phase

ρc the density of the continuous phase

µc the viscosity of the continuous phase

g the gravitational acceleration

The expression states that the greater the difference in density,the greater the efficiency. However, the density difference is notthe most important parameter affecting the separation efficiency.

The sedimentation velocity increases exponentially with thedroplet, or particle, size. This means that the smaller the dropletor particle, the more challenging the separation task.

For separation of small droplets and particles, which are found in the stable emulsions and suspensions in bilge water, gravityalone is not sufficient. In a centrifuge, the term (g) in the expres-sion is replaced by (w2r), the centrifugal force, which is severalthousand times greater than the acceleration due to gravity.Therefore, even droplets and particles that are only a fewmicrometers in size can be efficiently separated.

Another important factor that has a positive effect on separationefficiency is low viscosity. The viscosity of the continuous phaseaffects sedimentation velocity, which increases in inverse propor-tion to the viscosity. Therefore, any medium with low viscosity,such as a continuous water phase, facilitates separation.

Flocculation of particles Coalescence of droplets

Feed

Water

Solids

Oil

High centrifugal force inthe separator contributesto coalescence andflocculation, which aidemulsion breakdown.

EquipmentEnvironmental protection requires reliability. This is how Alfa Laval has met the bilge water treatment challenge.

Operating principleA positive displacement feed pump with variable frequencydrive control directs oily water from the bilge water settlingtank or equivalent to the system. The pump provides a feedrange of between 1,500 and 2,000 liters per hour. Theprocess liquid should always maintain a pH value above five.An optional chemical dosing unit can be connected after thepumping stage although chemicals usually are not required to accomplish efficient bilge water treatment.

Bilge water then passes through a dual basket strainer whichtraps large particles from the fluid before entering a heatexchanger, which raises the fluid temperature to requiredlevels, generally between 60° and 95°C, for optimum separa-tion efficiency.

A three-way changeover valve then directs the fluid to theseparation stage if all process conditions, such as feedtemperature, feed pressure and separator speed, fall withinpreset process values. If any process condition is not met,the valve re-circulates the fluid back to the bilge water settling tank.

A high-speed centrifugal separator continuously processeslarge volumes of bilge water. The oil outlet continuously dis-charges out-separated oil and emulsions. Solids that collectat the separator bowl periphery are discharged intermittentlyto a cyclone, which reduces the velocity and energy of thedischarged volume. Discharge occurs at preset intervals,which is generally set at 20 minutes, depending on theinstallation. Solids are then directed to a sludge, or waste oil, collecting tank.

A built-in water pump, or paring disc, continuously dis-charges separated bilge water through the water outlet. The destination of the separated bilge water depends uponits oil content, which is continuously monitored at an iso-kinetic sampling point by an oil-in-water monitor.

If oil content is less than or equal to 15 ppm, the separatedbilge water can be pumped either directly overboard or to a‘clean’ bilge water holding tank for discharge overboard later.If oil content exceeds 15 ppm, the effluent is re-circulated,preferably to the cleanest part of, the bilge water settling tankfor re-processing.

As an alternative, separated bilge water with an oil contentjust above 15 ppm can be directed to an ‘almost’ clean bilge

water holding tank in order to avoid re-contamination. Thishelps make bilge water handling more efficient.

Key componentsEcoStream makes the best use of available space andprovides flexibility and easy access for operation and main-tenance. These key EcoStream components are more fullydetailed later in this section:

Forwarding pumpAn eccentric screw pump with variable frequency drivecontrol.

StrainerA dual basket strainer of mesh size 1.5 mm.

Heat exchangerA shell-and-tube heat exchanger using steam as its heatingmedium.

Three-way changeover valvesTwo three-way changeover valves handle bilge water atcritical junctions.

Constant pressure valveA fast-acting, high-precision constant pressure modulatingvalve handles the required backpressure with accuracy.

TransmittersElectronic transmitters monitor temperature and pressure.

SeparatorThe BWPX 307 high-speed centrifuge uses the most modernfluid dynamics technology for high separation efficiency.

Control cabinetTwo separate compartments houses the process controllerand the electric power functions.

Process controllerThe EPC 50 process controller facilitates monitoring andcontrol of all EcoStream functions, which are displayed inclear text and on a mimic display.

Oil-in-water monitorCertified according to IMO resolution MEPC 107(49), this in-line unit accurately measures the content of oil in water.



Components in the system

Pump unitThe pump unit consists of a stand-alone compact pumpmodule, which is designed for ease of installation and ease of accessibility for maintenance.

Thanks to its variable speed control, this screw pump easilyhandles changing fluid capacities and enables adjustment ofthe feed rate setting during operation. The feed rate rangesbetween 1,500 and 2,000 liters per hour.

To protect the pump from dry running, the unit is equippedwith a water-priming device, which is automatically activatedupon startup. This water-priming device may also be acti-vated manually, whenever necessary. The pump has a pres-sure relief valve, pressure gauges and a non-return valve onthe discharge side.

StrainerTo trap large foreign particles suspended in the bilge waterthat may cause unnecessary operational disturbances, a dualbasket strainer with a mesh size of 1.5 mm is installed as asafety measure.

Heat exchangerThis shell-and-tube heat exchanger uses steam as theheating medium. All heater parts that come into contact withthe bilge water are made of cupronickel, a corrosion-resistantalloy. A proportional integral (PI) temperature controller accu-rately maintains the temperature set point within ± 2°C, evenunder variable bilge water feed conditions. This is especiallyimportant to achieve high separation efficiency. Installation ina horizontal position reduces the risk for build up of conden-sate and provides easy access for maintenance.

Separation unitThe BWPX 307 high-speed centrifuge utilizes the latestachievements in modern fluid dynamics technology. Designedfor continuous, high-efficiency separation of large bilge watervolumes, the centrifuge handles throughput capacities of1,500 to 2,000 liters per hour. Its unique design providesreliable operations, even when subject to oil shocks andrough weather conditions.

The patented Alfa Laval disc inlet, Optiflow, gently acceleratesbilge water into the separator bowl with a minimum ofshearing and foaming. This greatly improves separation effi-ciency by preventing the splitting of drops and the formationof further emulsions.

The new disc-stack design provides the maximum surfacearea possible for separation. Specially designed concentratordistribution holes and caulk configuration further optimizeseparation efficiency.

A speed sensor and an optional unbalance sensor monitorthe mechanical status of the separator. A cyclone, installed in the sludge outlet, provides ventilation and reduces thevelocity and energy of the discharge volume.

Oil-in-water monitorThis in-line unit monitors the oil content of separated bilgewater in compliance with IMO Resolution MEPC 107(49). It is capable of monitoring oil content from zero to 30 ppm at sample temperatures of up to 65°C.

To minimize response time, the iso-kinetic sampling point ofthe monitor is located as close as possible to the separationstage. Before processing occurs through the monitor, thesample passes through a cooler, which is used when separa-tion temperature exceeds 65°C, to prevent damage to themonitor from excessive heat.

Two independent alarm circuits come with a factory setting of15 ppm, but may be set independently to indicate oil contentin water ranging from two to 15 ppm. An alarm setting above15 ppm is impossible.

Three-way changeover valvesTwo pneumatically activated three-way changeover valvesregulate bilge water at critical junctions. The first directs bilgewater to the separation stage for treatment, and then re-circulates bilge water that does not meet pre-set conditionsback to the bilge water settling tank. The second routesseparated bilge water with oil content that is less than orequal to 15 ppm to a holding tank for discharge overboardlater or pumps the water directly overboard.

During an alarm situation when any preset condition is notmet, loss of operating air pressure or power failure, the three-way changeover valves automatically shift to re-circulationmode, thus preventing overboard discharge of any bilgewater with oil content exceeding 15 ppm.

Constant pressure valveThis fast-acting, high-precision constant pressure modulatingvalve prevents the formation of air bubbles during the separa-tion stage and thereby helps insure the accuracy of the oil-in-water monitor. It is installed after the separator.

Whenever solids or sludge are discharged from the separatorbowl, additional air pressure is applied to the valve to preventany untreated bilge water from penetrating and polluting thesystem downstream.



Oil-in-water monitor according to IMO resolution MEPC 107(49).

TransmittersElectronic transmitters provide accurate readings for pressureand temperature and improve control to achieve high separa-tion efficiency.

Sampling cocksSituated before the separation stage and after the three-waychangeover valves, these sampling cocks enable analysis of bilge water samples and provide an alternative way tomeasure the accuracy of the oil-in-water monitor.

Control cabinetCentrally located to monitor all EcoStream functions, thecontrol cabinet has two separate compartments. The lowercompartment contains all electric power functions, such as amulti-transformer, for power supplies in the range of 230 to690 V, all motor starters, pump unit speed control, powersupply for the optional chemical dosing unit and all pneumaticcontrol devices. The upper compartment contains theAlfa Laval EPC 50 computer-based process controller andoperator panels.

Process controllerThe EPC 50 is the latest generation of the Alfa Laval com-puter-based process controller. Easy to operate, the unit pro-vides fully automated advanced monitoring and control of allEcoStream functions. To assist with trouble tracing, an alarmlog registers the last 31 alarms. It also records time when thealarm appeared, time until the alarm was reset and thesludge discharge time interval.

The process controller has several built-in self-cure functionsthat automatically activate to ensure continued operationshould a system problem occur. A proportional integral (PI)temperature controller accurately maintains the temperatureset point for separation within ± 2°C, even under variablebilge water feed conditions.

Standard hardwired input and output signals include:• Emergency stop button,• Emergency shut down (ESD),• Process shut down (PSD),• Common alarm indication, and,• Process status indication.

The EPC 50 process controller is based on the same hard-ware used in other Alfa Laval units, making it easy to use foroperators who are already familiar with this equipment.

Operator panelsA push button and light-emitting diode station displays thestatus of cleaned bilge water for discharge overboard and forre-circulation, the pumping stage, the electric motors,optional chemical dosing units and optional automaticcleaning unit for the oil-in-water monitor.

A mimic display continuously indicates the operation mode of:• Feed to the separation unit or re-circulation,• Cleaned water for discharge overboard or re-circulation,• Pressure and temperature transmitters.

More process data are easily accessible by simply pressing a button. These include feed temperature, feed pressure,water outlet pressure, oil content in cleaned water, separatorbowl speed and total operating hours. All critical processparameters and operation mode, including start-up, standby,pre-production, production and stop, are displayed in clear text.

A key lock switch that controls discharge of separated wateris also located on the panel. Bypass, or locked, position re-circulates separated bilge water, regardless of its oil in watercontent. Inserting the key enables selection of automaticposition, which directs bilge water with oil content of 15 ppmfor discharge overboard.

It is also possible to set the limit for overboard dischargelower than 15 ppm – at five ppm, for instance. This enablessafe discharge in environmentally sensitive waters, wherelower oil in water content is required by regulatory bodies.

Located next to the LED panel, the operator panel controlsthe feed rate of the variable frequency drive feed pump.



EPC 50 process controller.

Optional equipmentThe EcoStream system offers these equipment options to provide greater flexibility.

• Chemical dosing unitUnder extreme conditions, centrifugal force alone may notbe sufficient to deliver high separation efficiency for satis-factory treatment of the bilge water. This is usually the casewhen large quantities of suspended solids, such as soot ordetergents, are present in bilge water.

For these conditions, an optional chemical dosing unit effi-ciently handles strongly emulsified oil as well as suspendedcolloids.

Chemicals should only be added when a combination of high separation temperature (95°C) and low flow rate(1,500 liters per hour) is insufficient to separate bilge waterto contain 15 ppm or less oil in water.

Alfa Laval recommends the use of safe and environmentallyfriendly Alpacon chemicals, MP 300/302. The combinationof these water-based additives promotes demulsificationand flocculation to achieve clean water with less than15 ppm for more difficult feed compositions.

• Automatic self-cleaning filterIf the feed water is expected to have a high solids or fibercontent, installation of an automatic, self-cleaning filter isrecommended. This may be necessary, for instance, if therisk of overflow from black and grey water tanks into thebilge wells exists.

Removing fibers and other coarse solids helps preventclogging of passages, such as the distribution holes in theseparator disc stack. This prolongs service and maintenanceintervals, which may otherwise be unacceptably short.

• Sludge removal kit (SRK)When installation of EcoStream on top of a sludge-collecting tank is impossible, an optional sludge removal kit(SRK) is available.

As part of the oily water pre-treatment stage, this small,intermediate sludge tank comes equipped with a pneu-matically driven sludge removal pump, level controller and level switch.

• Cleaning-in-place unitAn optional cleaning-in-place (CIP) unit is available toenable cleaning of separator bowl parts without dis-mantling the separator.

The CIP unit reduces downtime and maintenance man-hours and saves money. It also minimizes the potential riskfor mechanical damage of vital bowl parts.

• Automatic cleaning device for the oil-in-water monitorAn automatic pneumatic cleaning device for the oil-in-watermonitor is available as an alternative to manual cleaning ofthe measuring cell in the oil monitor.

The cleaning device activates at every sludge discharge,ensuring accurate monitoring of oil content by continuouslycleaning the measuring cell in the oil monitor.

• Serial bus connectionFully remote operation of the EcoStream is possible byconnecting the process controller via serial bus to anexternal computer or communications system.

This provides complete coordination with a Central ControlSystem (CCS) or a plant’s Integrated Administration andControl System (IACS). Proprietary field bus interfaceboards, according to Profibus DP or Modbus RTU stan-dards, are installed in the process controller. This enablescommunication to external automation systems. Most localfunctions can be replicated with the use of the field bus in-terface boards.

Please contact Alfa Laval if other protocol boards, such as CANopen, DeviceNet or InterBus, are required.Customers assume responsibility for coordination of pro-gramming on the remote side through their automationproviders. Alfa Laval provides documentation describing the protocol for the system developers.





Flow diagram� Two-stage bilge water

settling tankPre-heats the bilge water.

� Chemical dosing units (optional)Enhances separation efficiency ifstable emulsions are present.

� Feed pump with variable speed controlTransfers liquid to the steam pre-heater.

� Automatic self-cleaning filter(optional)Removes coarse solids and fibers.

� Pressure transmittersMeasures the pressure in the waterinlet and outlet and signals this in-formation to the process controller,which monitors pressure to ensureremains within acceptable limits.

� Dual basket strainerTraps large particles from the fluidbefore entering the heater.

� Steam pre-heaterRaises temperature of the liquid to the required treatment tem-perature.

� Temperature transmittersMeasures the temperature of theliquid from the pre-heater andsignals the process controller.

Temperature controllerAlerts operator when the tempera-ture exceeds, or falls below, a pre-set limit and acts as a backup toprovide temperature control shouldthe temperature transmitter fail.

PT

Feed inlet

Recycling to tank

Feed recycling

Frombilge wells

From drainsand leaks

AlpaconMP 300

AlpaconMP 302

VFD

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�

�

�

�

�



Three-way changeover valvesDirects bilge water from the tank to the separation stage and fromthe separation stage either to pump for discharge overboard if it contains less than 15 ppm oil in water or back to the bilge watersettling tank if these conditions are not met.

� CycloneReduces the velocity and energy ofthe discharged volume of solidsbefore reaching the sludge outlet.

� BWPX 307 high speed centrifugal separatorContinuously separates largevolumes of bilge water.

� Oil-in-water monitorContinuously measures oil contentof cleaned bilge water and com-pares these measurements to apre-set value.

� Constant pressure modulating valvePrevents the formation of air bub-bles during the separation stageand thereby helps insure the accu-racy of the oil-in-water monitor.

Intermediate sludge tank withsludge pump (optional)Temporarily stores sludge for wasteprocessing on shore.

Sludge outlet

PT Clean wateroutlet

QC

Ventilation QT

TT

TC

TT

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�

�

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EcoStream is ideal for replacing older bilge watertreatment systems. Its compact size easily fits into any available space.

To facilitate transport through small passageways,EcoStream can also be divided into four parts:

• A separator with a frame,• Valve and piping rack, • Feed pump, and,• Control cabinet.

Alfa Laval supplies each EcoStream bilge water treat-ment system with full documentation either as papercopies or as PDF (Portable Document Format) files ona CD-ROM. The instruction manual, which can alsobe made available in most major languages, covers:

• Safety• System description• Operating instruction• Parameter list • Alarms and fault finding• System reference/installation instructions• Separator manual• Spare parts catalogue• Component descriptions

Documentation

Alfa Laval ensures that the EcoStream fulfils therequirements of all major classification societies. Upon request, Alfa Laval delivers the EcoStream withan individual test certificate. This includes approval bythe society of the main components as well as work-shop testing of the complete module. Several keycomponents are also type approved by the leadingclassification societies.

Alfa Laval provides spare parts kits for all service andmaintenance needs. Global technical service, trainingand support are available throughout the lifetime of the EcoStream.

Retrofitting

Classificationsociety approval

Spare parts,service andsupport

Alfa Laval reserves the right to make changes at any time without prior notice.

Any comments regarding possible errors and omissions or suggestions for improvementof this publication would be gratefully appreciated.

Copies of this publication can be ordered from your local Alfa Laval company.

Published by: Alfa Laval Tumba ABMarine & Diesel EquipmentSE-147 80 TumbaSweden

© Copyright Alfa Laval Tumba AB 2004.

EMD00050EN 0412

Alfa Laval in brief

Alfa Laval is a leading global providerof specialized products and engi-neering solutions.

Our equipment, systems and servicesare dedicated to helping customersto optimize the performance of theirprocesses. Time and time again.We help our customers to heat, cool,separate and transport productssuch as oil, water, chemicals, bever-ages, foodstuff, starch and pharma-ceuticals.

Our worldwide organization worksclosely with customers in almost 100countries to help them stay ahead.

How to contact Alfa Laval

Contact details for all countries arecontinually updated on our web site.Please visit www.alfalaval.com toaccess the information.

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TI EcoStream

Documents

Transcript of TI EcoStream