Understanding the quality of flame in any boiler furnace is very important in tuning the boiler to the optimal level of performance. The aspects of combustion tuning involve looking at the boiler furnace and making sure the quality of flame is acceptable and good.The gas and oil fired boilers do not pose much problem in establishing a good flame in the furnace. The available instruments like flame scanners, CO monitors and oxygen indicators, along with the exit gas temperature, give a good indication to perceive if the quality of the flame is good. In coal fired boilers and mainly in tangential fired boilers, the furnace acts as a single burner, so it is required to look at the flame and understand the quality of the flame.
It is necessary to start from the control room of boiler then go to the mill area, to the furnace, and then to the bottom ash and fly ash area to fully make sure of combustion quality in furnace.
The control room of the boiler
- Look at the load at which the boiler is operating, availability of support fuel, SH & RH parameter
- Look at the number of mills operating
- Note the load, air flow, and outlet temperature on each mill
- Check the oxygen level at Eco / APH outlet
- Check the furnace pressure, scanner performance- watch for a few minutes for any fluctuations
- Look at the coal proximate analysis within 8 hours- if not available then at the max 24 hrs
- Check the PC fineness reading of each running mill if available
- Keep a note of those mills which have plus 50 more than 2% and minus 200 below 65%
Check each running mill in the mills area
- Bowl mills
- Check each spring loading by feeling the bumping of the pressure spring shaft
- Regular bump indicate the springs are loaded - how much cannot be estimated by feel - low minus 200 & or mill reject can be an indicator
- Watch for any abnormal sound
- Check the level of mill reject - look for coal in rejects - if nil or very low then ok
- Look at classifier vane position – check if they are equal in each mill. Close further to improve fineness - if needed
- Ball mills
- Check for ball noise in the mill area - high noise indicates low coal levels or low speed
- Check the mill speed and by-pass air
- Check classifier settings
- Look for any gear box noise
