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  • 7/27/2019 ABS Bulletin - ABS Pub21 Coal Burning Ships

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    Guide forShips Burning Coal

    1980

    American Bureau of ShippingIncorporated by Act of the Legislature ofThe State of New York 1862

    1980 American Bureau of Shipping65 BroadwayNew York, New York 10006, U.S.A.

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    Contents

    1. 0 Application2.0 Plans and Data3.0 Operating and Maintenance Manual4.0 General5.0 Coal Conditions6.0 Environmental Conditions7.0 Bunkers8.0 Independent Manual Control9.0 Coal Transfer and Preparation

    10.0 Boiler Control11.0 Boiler Protection System12.0 Dual Fuel13.0 Ash Handling and Storage14.0 Ventilation15.0 Fire Protection16.0 Electrica l Installations17.0 Tests and Trials

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    Foreword

    This Guide has been prepared to make available the Bureau rec-ommendations for handling and burning coal as a primary source ofpower for ships. Burning coal in ships is not new: indeed coal wasused more than a century ago. Modern coal handling on ships, whilerelatively new, is of proven technology as evidenced by the self-unloading bulk carriers. What is new, however, is the use of moderncoal burning technology on ships and the operation of modernmechanized coal handling systems while at sea.

    When coal burning systems are installed in a vessel classedwith the Bureau, details of the systems are to be submitted to theBureau and they are generally expected to be fitted in accordancewith this Guide.

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    Guide for Ships Burning Coal1.0 Application

    This Guide is intended to apply to ships burning coal in boilershaving stoker and grate arrangements. Other forms of coal burningsuch as pulverized fuel, underfeed firing, and fluidized beds requirespecial consideration. It is expected that pulverized fuel systemswill be of he direct firing type (the bin system is not to be employed)and that the provisions ofNFPA 85E, 85F, and 85G will be followedfor such installations.

    2.0 Plans and DataTh e following plans and data are to be submitted in triplicate forreview.Coal specifications including size, grindability, volatility, moisture,ash content and foreign matterMachinery ArrangementOperating and Maintenance ManualArrangement plans showingcoal bunkers, transfer system, prepara-

    tion equipment, boilers and ash handling systemPlans of bunkersDetails of control, safety, instrumentation and alarm systems in-cluding arrangements, schematics, panel layouts and descriptionof operationCoal transfer system

    Details of stokers and gratesAsh handling systemPlans of ventilation systems for bunkers and spaces where coal ishandledPlans showing hazardous locations and electrical equipment inthese locations together with the manufacturer, model and enclo-sure type

    3.0 Operating and Maintenance Manual

    1

    An Operating and Maintenance Manual is to be provided. TheManual is to contain plans and descriptions of coal bunkers,handling systems, preparation systems, burning systems and ashremoval systems, together with operating instructions for light-ing off, normal, and emergency conditions, and recommendedmaintenance.

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    4.0 GeneralCoal storage, transfe1; preparation, burning, and ash removal sys-tems are to be arranged so that a single failure ofany active compo-nent or a bunker fire will not cause loss of more than 50% of steamproduction necessary for the propulsion and safety of the ship andpreservation of the cargo. Generally, this will necessitate at leasttwo storage bunkers, two transfer systems, duplicate coal prepara-tion equipment, two service bunkers, two boilers, and duplicateash removal equipment. Two boilers need no t be fitted where aboiler is provided with burning equipment, including draft fans,and ash removal systems which satisfy th e single failure principle.

    5.0 Coal ConditionsCoal transfer, preparation and burning equipment, furnaces, andboiler, superheater and economizer tube spacing are to be designedfor satisfactory operation over the full range of coal conditionsspecified by the Owner.

    6.0 Environmental ConditionsCoal transfer, preparation, burning, and ash removal systems are tobe able to operate satisfactorily when inclined at angles of list upto and including 15 degrees and angles ofroll up to and including 22Vzdegrees together with pitch angles up to and including 72 degrees.

    7.0 Bunkers

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    Bunkers are to be in locations which will no t cause heating of thecoal from such sources as steam boilers and elevated temperaturecargo. Generally, the internal surfaces of bunkers are to be smooth;structural members are to be outside of bunker plating in order toprevent accumulation ofcoal an d dust within the bunker. Consider-ation will be given to structural members inside of bunkers wherethe arrangements are such that th e flow of coal will not be impeded,e.g. smooth vertical members and horizontal members arranged inshedding manner. The thickness of plating in bunkers is to beincreased by 1.5mm (0.06 in.) above that required by the Rules andis no t to be less than 9.5mm (0.375 in.) in bottoms and sides ofbunkers.

    Bunkers and coal handling systems are to be designed so thatthere are no dead spots in the bunker, i.e., the coal flow will be suchas to enable the bunker to be completely emptied. In order tocomply with this requirement it is generally expected that bunkerswill have sloped bottoms, the angle of th e sloped bottom relative tothe horizontal being not less than 45 degrees for bunkers with lowfriction linings and 70 degrees where such linings are not provided.

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    Gates, valves, or other suitable means of closure are to be in-stalled in bunker outlets to provide a tight seal.Effective drainage ofbunkers is to be provided. Drainage may beto the bilges in compartments below bunkers or may be provided bythe ship's bilge main. Non-return valves with positive means forclosing are to be provided in bilge and drain pipes to prevent ingressof water from the bilge system or from one bunker to another.Arrangements are to be fitted for the offloading of storagebunkers.

    8.0 Independent Manual ControlMeans are to be provided for independent manual control in theevent of failure of a particular control in the coal transfer, preparation, burning, ash removal, and boiler control systems. Necessaryinstrumentation and communications are to be provided so thatsatisfactory operation under independent manual control can beexercised for lengthy periods. Independent manual control is to bedemonstrated during tests or trials to the satisfaction of the Sur-veyor. This is to include demonstration of independent manualcontrol through the full maneuvering range and transfer from au-tomatic control.

    9.0 Coal Transfer Preparation

    3

    Except for tunnel spaces dedicated to coal transfer facilities, coaltransfer and preparation is to take place in enclosed air tight ducts,pipes or equipment. Tunnel spaces for coal transfer are to be separated from other spaces by air tight boundaries. Means are to beprovided for observation of the coal flow. Accesses are to be provided to facilitate servicing of enclosed equipment, cleaning, clear-ing obstructions and sampling coal. Pipes and ducts are to be no lessthan 9. 5mm (0.375 in.) thick except for pipes ofnominal size 254mm(10 in.) and smaller which may have a thickness corresponding toANSI Schedule 40. Where automatic transfer to a day bunker isprovided, the transfer is to be stopped automatically when thebunker is full. All metallic components of the coal transfer andpreparation systems are to be effectively bonded (grounded) to theship's hull. Upon failure of one section of a transfer system theupstream portions of the system which are in series with the failedsection are to stop automatically. The transfer system is to be provided with means to prevent foreign substances from entering transfer, preparation or burning equipment which could be damaged bysuch foreign substances. Means for removing foreign substancesneed no t be provided if the coal specifications preclude foreignmaterial which can stop flow or damage equipment. Considerationis to be given to provisions for breaking coal bridges in bunkers andblockages in the transfer and preparation systems.

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    10.0 Boiler ControlControl of coal feed from day bunkers, spreaders, draft fans an ddampers, overfire ai r flow, ash removal an d feedwater is to beprovided in the vicinity of the boiler front together with adequateinstrumentation to permit effective utilization of these controls.Flue gas oxygen content monitors and grate temperature monitoring systems are to be provided. Boilers intended to operate withoutmanual supervision are to comply witb th e applicable requirementsof 41.41 through 41.51 of the "Rules for Building and Classing SteelVessels" an d the boiler control system, including the steam dumpsystem, is to operate automatically. The boiler controls are to provide the capability to safely satisfy the steam requirements demanded from the boiler under all conditions ranging from maximumsteam generation to maneuvering while maintaining the fuel-airmixture within the limits required for continuous combustion. Theboiler control system is to be capable ofoperation during maneuvering such that the safety valves will not lift; it is generally expectedthat a steam dump system will be fitted to provide this capability.Means are to be provided to prevent backflow of furnace gases tostokers which are no t in operation.

    11.0 Boiler Protection SystemA boiler protection system is to be provided. Interlocks are to beprovided to prevent operation of induced draft (I. D.) fans withoutproper operation offorced draft (F. D.) fans and their dampers. Inthe case of low boiler water level, the coal feed is to be automatically stopped. Failure alarms are to be provided for feed systems fromday bunkers, coal supply controllers, spreader motors and gratedrive motors. Low level alarms are to be provided for day bunkers.Additionally, the protection system is to provide the following automatic safety actions which are to be alarmed.

    ConditionHigh furnace pressure'Low furnace pressure'F. D. fan malfunctionF. D. fan damper no t openI. D. fim malfunctionI. D. damper not openNotes

    Safety action 2Trip coal feed & F. D. & I. D. fansTrip coal feed & F. D. & I. D. fansTrip coal feed & I. D. fanTrip coal feed & F. D & I. D. fansTrip coal feed & F. D. fanTrip coal & F. D. & I. D. fans

    1 A suitable time delay is to be provided to prevent tripping of the boiler du e totransients which do not present a hazard.2 Tripping ofLD. and F. D. fans is to be properly programmed to avoid high orlow furnace pressure conditions. Limits may be different for tripping the fuelsupply and tripping th e f ~ m s .

    12.0 Dual Fuel

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    Systems designed to burn both oil and coal, either separately orsimultaneously, are to be provided with indications showing what

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    h1el is being fired. Automatic oil systems used to ignite coal are tocomply with Section 41 of the "Rules for Building and Classing SteelVessels.'"

    13.0 Ash Handling an d StorageAsh handling systems having th e capability to remove th e maximumquantity of ash which may be produced are to be provided. Han-cUing and storage systems are to he arranged so that heat is nottransmitted to bunkers. Materials used for wet handling and storagesystems are to be corrosion resistant or protected from corrosion.

    14.0 VentilationDucts and pipes for ventilation of bunkers, coal handling spaces,ducts for coal transfer systems and other spaces where coal dust isexpected to be present are to be independent of any other ventila-tion system. Exhaust ducts of such systems are to terminate on th eopen deck. \Vhere a mechanical exhaust is provided, a filter is to beplaced in the system before th e fan and as close as practicable to thesource ofdust. Natural exhaust ducts are to he arranged as verticallyas practicable with no angle being greater than twenty degrees fromthe vertical in order to avoid accumulation of coal dust in the vents.

    Bunkers are to be effectively ventilated with unrestricted ai r flowover the entire coal surface. The ventilation and structural ar-rangements are to be such that there are no dead spots where gasmay accumulate. A ventilation system is to be provided for eachbunker. Ventilation openings are to be fitted with permanent meansfor closure and the position of th e closure devices are to be clearlyindicated.

    15.0 Fire ProtectionThe fire main system is to be such that at least two jets ofwater canreach any part of an empty bunker space, an d any coal handlingspace. Two readily accessible easily operable air tight accesses are tobe provided at the top of each bunker.

    16.0 Electrical Installations

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    Electrical installations in hazardous locations are to be limited tothose considered essential for operational purposes. Hazardous lo-cations are subdivided into Category A, Category B, and CategoryC locations. Category A locations are those where both coal dust andmethane may be present. Category B locations are those where coaldust is expected to be present in th e atmosphere but methane is notexpected. Category C locations are those where coal dust will not beexpected in the air in ignitable or explosive quantities but wheresome accumulations of such dust are expected. Electrical cable

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    installed in these locations is to be armored or MI type. Electricalequipment in hazardous locations is to comply with the following.Category ALocationCoal bunkers, ventilation ducts from coal bunkers and preparationequipment and within 3m (10ft) of outlets of such ductsEquipmentTo be certified for use in coal dust and methane atmospheresCategoryBLocationCompartments where coal is dropped or dumped; open locationswithin 3m (10 ft) of a coal transfer point where coal is dropped ordumped; inside closed conveyorsEquipmentTo be certified for use in coal dust atmospheresCategory CLocationCompartments containing open conveyorsEquipmentWatertight equipment having an enclosure whose maximum tem-perature does not exceed l65C (329F) for equipment not subject tooverloading, and l20C (248F) for equipment subject to overloading;receptacles are to be of a type that prevents making or breakingcontact with live parts exposed

    17.0 Tests and Trials

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    Satisfactory operation of the complete installation is to be demon-strated to th e Surveyor during trials. This is to include all coalhandling and utiliza tion systems as well as ash handling systems. I tis to be demonstrated that a single failure of an active component ofthese systems will not cause loss ofmore than 50% of steam produc-tion necessary for propulsion and safety of the ship and preservationof cargo. Satisfactory operation of the systems du ring maneuveringis to be demonstrated.