boiler operation and safety precaution

8/9/2019 Boiler Operation and Safety Precaution

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Principles of OperationMain Components

Safe Operation


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PRINCIPLES OF

OPERATION


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USE OF BOILERS ON BOARD

In ships using diesel engines as main propulsion,the auxiliary boilers fitted onboard are normally usedfor air conditioning and heating purposes such asfuel oil heating, fuel tanks heating, lubricating oilsump tank heating, purifiers heater, domestic hotwater system etc.

Steam turbine dri en cargo pumps and boiler feedpumps are also commonly used on board tankers.


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Cochran Boiler


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Cochran Boiler

!he boiler onboard our essel is a hori"ontal smoketube COCHRAN type ertical boiler, which employs

forced draft oil burning, and is capable of generatingsaturated steam of #bar with a production rate of $t%hr.

!he boiler construction is ertical steel type, ha ingfire hole and hemi&spherical and tubular combustionchambers at the lower portion.


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Combustion gas enters the smoke chamber fromthe combustion chamber, and escapes into thechimney from the smoke box after passing througha group of stacks.

!he boiler shell is di ided into a water drum at itscentral portion and a steam drum at its upperportion, and calories are transmitted to the boilerfrom the combustion chamber, rear tube plates, anda group of stacks, all of which are heated bycombustion gas.

Cochran Boiler


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COMPONENTS OF

BOILER


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Burners


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Steam Drum & Boiler Tubes

!he Steam drum pro ides the space for the separation of steamand water mixture.In smoke tube boilers the water mixture is at the bottom of thedrum and the steam is at the top of the drum.!he steam from the steam drum is supplied to the necessaryser ices by means of a Main Steam Stop 'al e.

Smoke from the boiler furnace passes through the smoke

chamber and enters through the smoke tubes of the boiler andescapes through the smoke box to the chimney.(ater to be apori"ed lies outside these tubes.!hese tubes are approx. )*mm diameter welded to the flat tubeplates.


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Safety Valve


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!he function of a safety al e is to pre entexcessi e pressure from building up in a steamboiler.

It pre ents boiler pressure from rising abo e acertain predetermined pressure by opening to allowexcess steam to escape into the atmosphere whenthat point is reached, thus guarding the boileragainst possible explosion. !he SO+ S regulationsays that there should be minimum two safety

al es on a boiler.

Safety Valve


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Level Condenser


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Main Steam Stop Valve


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!his is mounted on the top of the boiler andenables the steam from boiler to be supplied to

arious heating de ices.

Main Steam Stop Valve


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Scum Valve


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Scum Valve

!hey are mounted on steam drum ha ing aninternal fitting in the form of shallow pan situated

ust below the normal water le el with which anyoil or scum which is floating on surface of watercan be remo ed.!hese al es discharge into the bottom blow

down line to o erboard discharge al e.


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Soot blower


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Soot Blower

In order to maintain the gas side heating surfaces ofa boiler in a clean condition and so as to pre ent an

undue build up of deposits which can lead tocorrosion or uptake fires, soot blowers are fitted.!hey may be operated by steam or compressed air.


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ir Vent


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ir Vent

!hey are fitted on the top of the boiler to

release air when filling the boiler or wheninitially raising steam.


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!eed Chec" Valve


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!eed Chec" Valve

!hese are fitted to gi e final control o er the entry offeed water into the boiler.

!hey must be screw down non return al e so thatin the e ent of loss of feed pressure the boiler watercan not blow back into the feed line.Main and auxiliary feed checks are fitted .


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Bottom Blow Valve


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Blow down valve

!hey are fitted to the water drum to enable water to

be blown from boiler when the boiler is shut down.!hey can also be used to lower the density byblowing down the settled salts.


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utomatic feed water regulator are fitted in the feedline prior to main check line.It is fitted to maintain the flow of water into the boilerand maintain the water le el at its desired alueduring all load conditions.

/oiler 0eed (ater 1egulator


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$'M $(

S)C*+D$(

!orced Draft !an


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0orced 2raft 0an

/oth the fans are dri en by a single by&axial motor.Priming air from the priming fan is mixed with oilparticles at an early phase of combustion and thesecondary air from the secondary fan shares asubstantial percentage of combustion air.

!he dampers of both the fans are coupled with spillcontrol al e in the fuel line so that an appropriateair fuel mixture can be obtained through out thecombustion.


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Manhole Door


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Manhole 2oor

Internal access to the boiler is pro ided bythe manhole door in the top of the shell for

cleaning and inspection.3and holes in the lower section of the shellpro ide access to the lower part of the waterspace for cleaning and inspection.


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Cascade Tan"


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*bservation Tan"


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Control panel


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Manifold Valve


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Valve positioner


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,(- Type Strainer


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$educer


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Burner ssembly


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M .+)T V LV)

S*L)+*'D

V LV)


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S 'LLC*+T$*LV LV)

C M).


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!* Strainer


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!* ump


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!* 0eater


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0eater $elief Valve


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ressure Transmitters


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SAFE OPERATION


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Safety recautions


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Safety recautions


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Safety recautions


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Safety recautions


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Safety recautions


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t least two safety al es ha e to be fitted to theboiler as per SO+ S regulation.BL*#D*#+ 1 -

!he pressure drop below the lifting pressure for asafety al e is set at 45 by regulation although it ismore normal to set al e at 65 to pre ent excessi eloss of steam. 0or boilers with a superheater it isimportant that the superheater al e not only liftsfirst but closes last.

Safety Valves


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Safety valve settin%Must be set with the sur eyor present except when on the wasteheat unit. chief engineer with three years experience may then setthe safety al e but must submit information to sur eyor for issue ofcertificate.Superheated steam safety al es should be set as close tooperating temperature as possible as expansion can alter the

relationships between al e trim and guide%no""le rings which caneffect the correct operation of the al e.!wo safety al es& each set independently7ach safety al e must release entire steam flow in pressure accumulation testSur eyor uses specially checked gaugeOne al e gagged

al e initially set to approximately the correct position then steam pressureincreased to set pressuread ust al e to liftraise and lower pressure to checkfit locks to both al es on completion


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Safety valve settin%

7asing gear to be checked free before setting al es. Steamshould not be released as this can damage seat.

d ustment by compression nut on top spring plateCompression spring o er nut&no mo ementCap with cotter 8pre ent unauthori"ed person7asing gear for manual operation


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repared by 1-


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boiler operation and safety precaution

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