To avoid furnace explosion you must ensure that ther must not be leakage of oil into boiler furnace and trip the boiler immdiately if flame disappears.Purging of boiler is necessary after every tip out.
There is one more precaution which is if at the start of ignitors or oil rows the flame is not established immediately then purge the furnace and relight again.
Sunday, July 11, 2010
Acoustic Instruments can detect early Boiler Tube Leakage to avoid secondary Damage
Boiler Tube Leakage Detect Early to avoid Secondary Damage
Superheater WaterWall Economiser Tube Leakage detection by Acoustic Instruments to avoid secondary damage.BTL may damage boiler tubes refractory structure beams and choke Airheater tubes so it must be watched carefully
Detect Boiler Tube Leakage Early to avoid secondary Damage
There must be constant vigil on possibility of Boiler Tube Leakage because small negligence may result into heavy leakage to pressure parts of Boiler,its refractories and even to its Structure Beams etc.We must constatly watch furnace vaccum which must be maintained -10 to -20 mmwl.If furnace vaccum is disturbed then we must physically inspect boiler for hissing sound of leakage of steam.Nowadays some Acoustic Instruments also available which may detect steam leakage from boiler tube.Feed water flow is another parameter which must be watched carefully to judge boiler tube leakage.Any increase of feed water flow and decreasing of deaerator level must be seriously examined.
There are several type of boiler tube leakage such as Super Heater Leakage,Wter Wall Leakage and Economiser Tube Leakage,all type of boiler tube leakage are seriously dangerous for Boiler.In some cases I have seen that Economiser leakage not taken seriously and unit allowed to run for some time which resulted into chocking of Air Heater Tube which resulted into pressurisation on Boiler Furnace.
Superheater WaterWall Economiser Tube Leakage detection by Acoustic Instruments to avoid secondary damage.BTL may damage boiler tubes refractory structure beams and choke Airheater tubes so it must be watched carefully
Detect Boiler Tube Leakage Early to avoid secondary Damage
There must be constant vigil on possibility of Boiler Tube Leakage because small negligence may result into heavy leakage to pressure parts of Boiler,its refractories and even to its Structure Beams etc.We must constatly watch furnace vaccum which must be maintained -10 to -20 mmwl.If furnace vaccum is disturbed then we must physically inspect boiler for hissing sound of leakage of steam.Nowadays some Acoustic Instruments also available which may detect steam leakage from boiler tube.Feed water flow is another parameter which must be watched carefully to judge boiler tube leakage.Any increase of feed water flow and decreasing of deaerator level must be seriously examined.
There are several type of boiler tube leakage such as Super Heater Leakage,Wter Wall Leakage and Economiser Tube Leakage,all type of boiler tube leakage are seriously dangerous for Boiler.In some cases I have seen that Economiser leakage not taken seriously and unit allowed to run for some time which resulted into chocking of Air Heater Tube which resulted into pressurisation on Boiler Furnace.
Clinker Formation in Boiler Causes and how to avoid it ?
Cause of Clinker formation is high ash content,low GCV and high mineral content in coal but precaution is solution.
In India Coal used in Power Plant is of often low quality which has high ash content and low GCV.Mineral content present in coal may increase this problem.In Water Wall ash is fused and stick on it.Presence of minerals content in coal produce very hard lumps of clinker which are very difficult to remove.Such clinkers are removed by pneumatic hammer during shutdown of unit.
To avoid clinker formation we must use good quality of coal which has less ash,more GCV and less mineral content.
If the quality of coal is low then it is not possible to stop clinker formation but we can stop its accumulation in furnace to some extent by proper poking at ash hoppers and providing sufficient amount of water which may flush out fused slag.Precaution is key which may reduce down time of unit.
We must not blame coal quality for clinker formation but our vigilant attitude may stop its accumulation in Furnace.
Always keep watch on regular poking.
Provide sufficient amount of water in hopper which may flush out fused slag.
Firing in Boiler must be proper so there may not be unburnt coal by using right proportion of primary and secondary air.
Fuel oil burners must be properly so there may not be unburnt oil in furnace.Fuel oil firing must be proper.Fuel oil must be properly atomized and steam must be properly charged into oil gun.
Above precaution may avoid chances of clinker formation and its deposition which may result into higher plant load factor.
For national interest we must check fuel firing to avoid unburnt fuel.
In India Coal used in Power Plant is of often low quality which has high ash content and low GCV.Mineral content present in coal may increase this problem.In Water Wall ash is fused and stick on it.Presence of minerals content in coal produce very hard lumps of clinker which are very difficult to remove.Such clinkers are removed by pneumatic hammer during shutdown of unit.
To avoid clinker formation we must use good quality of coal which has less ash,more GCV and less mineral content.
If the quality of coal is low then it is not possible to stop clinker formation but we can stop its accumulation in furnace to some extent by proper poking at ash hoppers and providing sufficient amount of water which may flush out fused slag.Precaution is key which may reduce down time of unit.
We must not blame coal quality for clinker formation but our vigilant attitude may stop its accumulation in Furnace.
Always keep watch on regular poking.
Provide sufficient amount of water in hopper which may flush out fused slag.
Firing in Boiler must be proper so there may not be unburnt coal by using right proportion of primary and secondary air.
Fuel oil burners must be properly so there may not be unburnt oil in furnace.Fuel oil firing must be proper.Fuel oil must be properly atomized and steam must be properly charged into oil gun.
Above precaution may avoid chances of clinker formation and its deposition which may result into higher plant load factor.
For national interest we must check fuel firing to avoid unburnt fuel.
Boiler Turbine Turbogenerator ID FD PA Fan BFP LPH HPH Deaerator GT Air heaters Economisers EP ABT FSS Scanners
Introduction and some facts about large thermal power station.
Boiler is used for steam generation.
Ball Mill or Bowl mills are used for pulverisation of coal in powder form for efficient firing in boiler.
Raw Coal Feeders are used to supply coal to ball mills in controlled quantity.
PA Fan are used to transport and preheat pulverised coal to burners.
ID Fan are used to exhaust flue gases to chimeny and create vaccum in Furnace.
Electrostatic Precipitators are used to separate ash particles from flue gases to control pollution.Here collecting electrode,emmiting electrode and rapping mechanism used.
FD Fan used to provide air to boiler for help in firing.
Steam produced in boiler is further superheated in Superheaters.There are lot superheaters such as platen,pendent,convection and final superheaters.
Boiler drum used for separation of staem from water.
Boiler circulation pump used for forced circulation of water in water wall because at high pressure natural circulation is not possible.
Ash slurry pumps are used to flush ash with water.
Boiler Feed Pump used to provide water to boiler.
Deaerator used to separate dissolved air from water.
In Turbine heat energy of steam is converted into mechanical energy.
ESV which is called emergency stop valve used to stop supply of steam to turbine when unit trips.
Barring gear or shaft turning gear is used to ratate turbinr rotor at 3.15 rpm when turbine is not running to check bending of rotor due to its own weight.
LP Heaters and HP Heaters are used to heat condensate and feed water supplied to boiler to increase efficiency by steam bled from turbine extraction.
Economiser are used to heat feed water by flue gages to increase efficiency. Heat of waste flue gas is utilised here.
Air Heaters uses heat of waste flue gases to preheat primary and secondary air.There are two types of air heaters tubular and rotary.
Condenser used to condence steam exhausted from turbine.
Condensate Pump are used to supply water to Deaerator from condensers.
CW Pump used to cool steam in condensers.
Turbogenerator converts mechanical energy into electrical energy.
H2 Gas used in generators used for cooling of generators.
Seal Oil system used to seal hydrogen gas from escape from generator.
Stator Water Cooling system provides demineralised water into hollow stator conductor of generator for its cooling.
Generating Tansformer steps up volatage for transmission.
Water Treatment Plant is used to produce demineralised water for steam generation. Cation anion and degassifier tower used to separate mineral and gases from water.PAC or alum used to separate mud and silica from water.
Coal Handling Plant supplies Coal to Boiler.Merry go round system or wagon trippler used to unload coal into hoppers. Coal is crused in crusher to crush it in 25mm size.Magnetic separators used to separate metalic particles from coal.
ABCB,SF6,OCB,MOCB and VCB are circuit breakers used to make or break electricity contact at load.
Isolators are used to make or break contact at no loads.
ABT is availability based tarrif system to maintain grid discipline.
Purging is done to clean furnace from combustible gases by running IDF and FDF at atleast 30% load for 5 minutes.
Furnace explosion may be checked by timely purging and adjusting firing properly using right quantity primary and secondary air and timely oil support.
Flame scanners used to sence flame in boiler.
FSS is furnace safeguards supervisory system to safeguard boiler.
Clinker formation which caused by more ash content and mineral in poor quality coal may be checked by proper poking and using more water for flushing and use of clinker grinder.
Acoustic Instruments used to detect early boilker tube leakage to avoid secondary damage to pressure parts.
Boiler is used for steam generation.
Ball Mill or Bowl mills are used for pulverisation of coal in powder form for efficient firing in boiler.
Raw Coal Feeders are used to supply coal to ball mills in controlled quantity.
PA Fan are used to transport and preheat pulverised coal to burners.
ID Fan are used to exhaust flue gases to chimeny and create vaccum in Furnace.
Electrostatic Precipitators are used to separate ash particles from flue gases to control pollution.Here collecting electrode,emmiting electrode and rapping mechanism used.
FD Fan used to provide air to boiler for help in firing.
Steam produced in boiler is further superheated in Superheaters.There are lot superheaters such as platen,pendent,convection and final superheaters.
Boiler drum used for separation of staem from water.
Boiler circulation pump used for forced circulation of water in water wall because at high pressure natural circulation is not possible.
Ash slurry pumps are used to flush ash with water.
Boiler Feed Pump used to provide water to boiler.
Deaerator used to separate dissolved air from water.
In Turbine heat energy of steam is converted into mechanical energy.
ESV which is called emergency stop valve used to stop supply of steam to turbine when unit trips.
Barring gear or shaft turning gear is used to ratate turbinr rotor at 3.15 rpm when turbine is not running to check bending of rotor due to its own weight.
LP Heaters and HP Heaters are used to heat condensate and feed water supplied to boiler to increase efficiency by steam bled from turbine extraction.
Economiser are used to heat feed water by flue gages to increase efficiency. Heat of waste flue gas is utilised here.
Air Heaters uses heat of waste flue gases to preheat primary and secondary air.There are two types of air heaters tubular and rotary.
Condenser used to condence steam exhausted from turbine.
Condensate Pump are used to supply water to Deaerator from condensers.
CW Pump used to cool steam in condensers.
Turbogenerator converts mechanical energy into electrical energy.
H2 Gas used in generators used for cooling of generators.
Seal Oil system used to seal hydrogen gas from escape from generator.
Stator Water Cooling system provides demineralised water into hollow stator conductor of generator for its cooling.
Generating Tansformer steps up volatage for transmission.
Water Treatment Plant is used to produce demineralised water for steam generation. Cation anion and degassifier tower used to separate mineral and gases from water.PAC or alum used to separate mud and silica from water.
Coal Handling Plant supplies Coal to Boiler.Merry go round system or wagon trippler used to unload coal into hoppers. Coal is crused in crusher to crush it in 25mm size.Magnetic separators used to separate metalic particles from coal.
ABCB,SF6,OCB,MOCB and VCB are circuit breakers used to make or break electricity contact at load.
Isolators are used to make or break contact at no loads.
ABT is availability based tarrif system to maintain grid discipline.
Purging is done to clean furnace from combustible gases by running IDF and FDF at atleast 30% load for 5 minutes.
Furnace explosion may be checked by timely purging and adjusting firing properly using right quantity primary and secondary air and timely oil support.
Flame scanners used to sence flame in boiler.
FSS is furnace safeguards supervisory system to safeguard boiler.
Clinker formation which caused by more ash content and mineral in poor quality coal may be checked by proper poking and using more water for flushing and use of clinker grinder.
Acoustic Instruments used to detect early boilker tube leakage to avoid secondary damage to pressure parts.
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