Posted by Clifford Weir on November 13, 2001 at 22:49:46:
In Reply to: SO2 in flue gas remains high posted by Susovan on October 29, 2001 at 08:29:09:
: We have 20 year old BHEL make VU-40 boiler. In this boiler the SO2 in flue gas remains high (Against the permissible limit 100 ppm, it remains 200 ppm due to high sulphur in coal.
: Is there any feasible solution keeping in view the high cost, space limitation and ageing of boilers?
: A reply will be greatly appreciated.
I never ran a coal fired boiler but I have ran chemical recovery boilers and there were a few things that we tried and were successful at reducing both T.R.S. (Total Reduced Solids) and SO2.
1) We reduced the amount of moisture in the fuel by removing as much moisture as possible. In your case this would mean a preheater chamber for your fuel, is you coal crushed on site? If so do you use combustion air from the ID fan as a preheater in your crusher. Do you have a means of prehandling the coal after in leaves the bunkers.
2) What about reducing the firing rate of the coal, the only problem the increase of auxilary fuel may make this uneconomical for the same desired steam load.
When balancing the plant the numbers my show where you can cut, either on turbine production in KW or on steam consumption from some other user. Unfortunately these solution come at a cost to the user and thats you, efficency comes only when you look at all your options.
3. Another thing that you may look at is, if your burning auxilary fuel, how contaminated is it and what are the btu's available when analized.
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