Gas prodn. for gas turbine operation - in combined gas and steam turbine power station

摘要

Prodn. of gases for operating a gas turbine in a combined gas and steam turbine power station is carried out by almost completely combusting coal fines at above 1 bar pressure and above 1000 deg.C with (oxygen-enriched) air or pure oxygen opt. mixed with recirculate off-gas to produce a combustion gas consisting of SO2, H2O and opt. N2 (if air is used), this combustion gas being cleaned to remove dust (including alkali metal cpds. and opt. CO2 and NOx and then passed successively through a gas turbine and a waste heat boiler in which water is preheated, evapd. and superheated for operating a steam turbine with one or more pressure stages. The novelty is that the combustion gas (dirty gas, leaving the combustion chamber (1), is subjected to (i) cooling to 850-950 deg. C by heat transfer to the clean gas and by subsequent mixing with recirculated off-gas or a gas similar so that used in combustion, supplied by an injection pipe (30), (ii) cleaning to remove dust (including alkali metal cpds.,) e.g. in a cyclone or ceramic filter, and opt. SO2 and NOx, e.g. by addn. of lime dust (dry additive process) and ammonia (SNOP process), and (iii) reheating as clean gas to the gas turbine entry temp. by heat transfer from the dirty gas. ADVANTAGE - The process provides improved efficiency of electricity generation from coal by producing a higher clean gas temp. (1200-1400 deg.C), reducing heat losses, allowing the gas turbines to operate with a single flue and using the internal insulation of the pressure vessel and connection lines as a heat exchanger.