Hi.Can somebody please help me on this matter.I am working at a 600MW coal-fired power station and we are currently experiencing a problem with our furnace pressure going into positive. The system is designed to maintain the furnace pressure just slightly below atmospheric pressure to prevent flue gas leakages to the surroundings.this is the balanced draft system ie FD(forced draft) and ID(induced draft).
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furnace pressure control in a coal fired power station 2
- Thread starter brendam
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a) lower the setpoint from -.25 in wc to -.75 in wc
b)check the action of the ID fan damper actuator to comfirm its not bound up or other control element issues
c) You may be running out of ID fan capability. If you are at full load other issues may cause you to run out of fan margin- such as HP heater out of service, high excess air operation, out of spec coal being fired, pluggage of convective pass or air heater or scr with ash
b)check the action of the ID fan damper actuator to comfirm its not bound up or other control element issues
c) You may be running out of ID fan capability. If you are at full load other issues may cause you to run out of fan margin- such as HP heater out of service, high excess air operation, out of spec coal being fired, pluggage of convective pass or air heater or scr with ash
- Thread starter
- #3
Thanks davefitz for the info. up to so far we have checked excess air and its within the spec, all Hp heaters are in service. The only thing that is still confusing us is coal qualities, we cant draw a conclusion in terms of this cos at some point we were running with good coal qualities and thats when we experienced lots of problems with this pressure. In terms of airheater leakege test, we found out that there is leakage of 10% whereas the spec is 7% but my concern here is the other unit we are running with a leakage of 13% but we are not experiencing the same problem.
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Air heater leakage of 10 and 13% respectively is still pretty good especially for a device invented in 1906 and not improved much since. How about the baskets, are they plugged?
That much leakage means that your ID fans are handling more leakage and less furnace draft and, cold leakage air is more dense than flue gasses so the ID Fan may be loaded up as Dave Fitz has stated.
Check your instrumentation; the connection to the furnace to make sure it is clear (not plugged with ash) and that the loop is tuned properly. Too much or too little of several different factors in your PID loop could give the symptoms that you describe.
Davefitz recommends checking the FD fan damper actuator and I recommend checking the damper blades themselves to make sure that they aren't bound up, frozen or loose on their shafts. I've seen all of each of those as a problem.
Also, check the instrumentation loops on your PA fans and FD fans as those too could be affecting your furnace pressure.
rmw
rmw
That much leakage means that your ID fans are handling more leakage and less furnace draft and, cold leakage air is more dense than flue gasses so the ID Fan may be loaded up as Dave Fitz has stated.
Check your instrumentation; the connection to the furnace to make sure it is clear (not plugged with ash) and that the loop is tuned properly. Too much or too little of several different factors in your PID loop could give the symptoms that you describe.
Davefitz recommends checking the FD fan damper actuator and I recommend checking the damper blades themselves to make sure that they aren't bound up, frozen or loose on their shafts. I've seen all of each of those as a problem.
Also, check the instrumentation loops on your PA fans and FD fans as those too could be affecting your furnace pressure.
rmw
rmw
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