Answer SSEP Question 18
Q18.
A. State the instructions you as Second Engineer will give to watch
keepers with respect to boiler uptake fire;
Answer: A. Standing Instruction for EGB uptake Fire
(1) Reduce the speed of the engine and inform the bridge about the same.
(2) Stop the engine after getting clearance from the bridge
(3) Stop the auxiliary blowers. Cover T/C air inlet with canvas.
(4) Keep the boiler water circulating P/P running as it helps to cool down the tubes.
(5) Keeping an eye on pump pressure and economizer tube stack temperature.
(6) Dump steam if necessary
(7) Never use soot blowers to fight uptake fires as it may result in $\displaystyle \mathrm{H_2}$ fire.
(8) Start boundary cooling till temperature starts decreasing.
(9) If possible then inject fresh water Jet from top of EGB. 10) If heavy water loss is noted stop circulating p/p
Standing Instruction for Aux. Boiler Uptake Fire
(1) Amount of feed heating should be reduced to lower the feed temperature
(2) Reduce the excess air on shut off the boiler FO fan.
(3) The safety valve should be lifted to keep a high steam flow and hence high feed flow requirements (because the boiler is now fired by the uptake fire)
(4) Lifting the safety v/v gains the added advantage of reducing the boiler pressure and hence corresponding saturation temperature of the water gives the cooling effect.
(5) Direct attack can be made on non-pressurized parts. The nozzle of fire hose should be set to solid jet and aimed for the seat of the fire.
(6) This should not be carded out on hot pressurized parts due to risk of steam explosions.
(7) Dry powder can beilved is suitable extinguishing media.
B. Minimizing Uptake Fire
(1) Regular soot blowing (at least 3 times a day) to avoid deposition of soot.
(2) Maintain correct exhaust gas pressure difference to maintain good gas velocity, so that soot can be carried away by gas.
(3) Regular inspection and cleaning of EGB to be done.
(4) Soot blow, the economizer before and after maneuvering
(5) If possible bypass EGB during maneuvering
(6) Continue running boiler water circulating P/P at least for 12 hours before starting and after stopping the main engine.
(7) Avoid low load operation of main engine in order to reduce soot deposition.
(8) Ensure proper engine operating condition (Proper combustion no carryover of exhaust fuel via exhaust gas)
(9) If it is necessary to stop circulation for any reason, the unit should be blown prior to shut down.
(10) If soot release chemical is available then inject as per the manufacturer instruction.
(11) When M/E speed is increased after period of shut down or slow steaming, soot blowing should be increased and engine power increased very slowly whilst monitoring the economizer parameters.
C. Reasons for Blow Back
A blow back can occur when there is sudden change in pressure in the furnace (Pr. Of air supplied by F.D Fan). It causes a pressure wave travel where there is less pressure as towards the uptake side on F.D fan side.
Reasons
(1) Insufficient purging of furnace during burner firing
(2) Accumulation of oil and oil vapor in furnace which is ignited by re-lit burner, i.e., sudden application of heat.
(3) Sudden admission of air into fuel rich mixture
(4) Water in fuel will cause abrupt intermittent firing, generating a pulse of Pr. Wave inside the furnace which leads to blow back.
(5) Low oil temperature, improper functioning of burner, poor penetration, and poor atomization of oil causes accumulation of oil.
(6) Smoke tubes choked with heavy soot deposits. They cause resistance to free now of exhaust gas which exerts back pressure in the furnace.
D. Standing Instruction w.r.t Avoidance of Furnace Blow Back
(1) Maintain burning equipment/burners per PMS
(2) All parameters such as oil pressure. Water Pr. Steam Pr., air amount, etc. to be closely monitored.
(3) Regular inspection of flame.
(4) Boiler should be fired and maintained by qualified engineer
(5) Adequate pre-ignition purging
(6) If flame failure occurs or for any other reason boiler trip then do not forget to pre-purge the furnace at least for 3 min before firing in manual mode.
(7) Do not by pass any safety feature of the boiler combustion control.
B. State how the incidence
of uptake fires may be minimized
C. State the reasons for blow-back from
the furnace of an auxiliary boiler
D. State the standing instructions
you might have received from your Chief Engineer With respect to the
avoidance of boiler furnace blow-back.Answer: A. Standing Instruction for EGB uptake Fire
(1) Reduce the speed of the engine and inform the bridge about the same.
(2) Stop the engine after getting clearance from the bridge
(3) Stop the auxiliary blowers. Cover T/C air inlet with canvas.
(4) Keep the boiler water circulating P/P running as it helps to cool down the tubes.
(5) Keeping an eye on pump pressure and economizer tube stack temperature.
(6) Dump steam if necessary
(7) Never use soot blowers to fight uptake fires as it may result in $\displaystyle \mathrm{H_2}$ fire.
(8) Start boundary cooling till temperature starts decreasing.
(9) If possible then inject fresh water Jet from top of EGB. 10) If heavy water loss is noted stop circulating p/p
Standing Instruction for Aux. Boiler Uptake Fire
(1) Amount of feed heating should be reduced to lower the feed temperature
(2) Reduce the excess air on shut off the boiler FO fan.
(3) The safety valve should be lifted to keep a high steam flow and hence high feed flow requirements (because the boiler is now fired by the uptake fire)
(4) Lifting the safety v/v gains the added advantage of reducing the boiler pressure and hence corresponding saturation temperature of the water gives the cooling effect.
(5) Direct attack can be made on non-pressurized parts. The nozzle of fire hose should be set to solid jet and aimed for the seat of the fire.
(6) This should not be carded out on hot pressurized parts due to risk of steam explosions.
(7) Dry powder can beilved is suitable extinguishing media.
B. Minimizing Uptake Fire
(1) Regular soot blowing (at least 3 times a day) to avoid deposition of soot.
(2) Maintain correct exhaust gas pressure difference to maintain good gas velocity, so that soot can be carried away by gas.
(3) Regular inspection and cleaning of EGB to be done.
(4) Soot blow, the economizer before and after maneuvering
(5) If possible bypass EGB during maneuvering
(6) Continue running boiler water circulating P/P at least for 12 hours before starting and after stopping the main engine.
(7) Avoid low load operation of main engine in order to reduce soot deposition.
(8) Ensure proper engine operating condition (Proper combustion no carryover of exhaust fuel via exhaust gas)
(9) If it is necessary to stop circulation for any reason, the unit should be blown prior to shut down.
(10) If soot release chemical is available then inject as per the manufacturer instruction.
(11) When M/E speed is increased after period of shut down or slow steaming, soot blowing should be increased and engine power increased very slowly whilst monitoring the economizer parameters.
C. Reasons for Blow Back
A blow back can occur when there is sudden change in pressure in the furnace (Pr. Of air supplied by F.D Fan). It causes a pressure wave travel where there is less pressure as towards the uptake side on F.D fan side.
Reasons
(1) Insufficient purging of furnace during burner firing
(2) Accumulation of oil and oil vapor in furnace which is ignited by re-lit burner, i.e., sudden application of heat.
(3) Sudden admission of air into fuel rich mixture
(4) Water in fuel will cause abrupt intermittent firing, generating a pulse of Pr. Wave inside the furnace which leads to blow back.
(5) Low oil temperature, improper functioning of burner, poor penetration, and poor atomization of oil causes accumulation of oil.
(6) Smoke tubes choked with heavy soot deposits. They cause resistance to free now of exhaust gas which exerts back pressure in the furnace.
D. Standing Instruction w.r.t Avoidance of Furnace Blow Back
(1) Maintain burning equipment/burners per PMS
(2) All parameters such as oil pressure. Water Pr. Steam Pr., air amount, etc. to be closely monitored.
(3) Regular inspection of flame.
(4) Boiler should be fired and maintained by qualified engineer
(5) Adequate pre-ignition purging
(6) If flame failure occurs or for any other reason boiler trip then do not forget to pre-purge the furnace at least for 3 min before firing in manual mode.
(7) Do not by pass any safety feature of the boiler combustion control.
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