Control of NO/sub x/ and SO/sub 2/ emissions by gas reburning-sorbent injection technology

Emissions of oxides of sulfur and nitrogen are thought to be responsible for acid rain deposition. A large number of existing pre-NSPS electric utility boilers fired with Midwestern and Eastern coals would be affected if acid rain control legislation is promulgated. To allow such boilers to meet potential emissions regulations with fuel flexibility and good operability, cost effective retrofit emission control technology is required. Gas Reburning-Sorbent Injection (GR-SI), a combination control technology that could be retrofitted to coal fired utility boilers, could reduce NO/sub x/ and SO/sub 2/ emissions by 60% and 50%, respectively. A field test project has been initiated as part of the DOE's Clean Coal Technology program to demonstrate GR-SI on three pre-NSPS coal fired utility boilers in Illinois. The Gas Research Institute and the State of Illinois are the other participants in this project. The boilers selected are representative of pre-NSPS design types: one each of tangentially, wall, and cyclone fired units will be tested. Gas reburning consists of the staged introduction of fuel, with coal fired in the main heat release zone, and 15-20% of the heat input added as natural gas in the downstream reburn zone. This is followed by the burn-out zone wheremore » a dry, calcium based sorbent can also be injected for SO/sub 2/ pick-up. Alternatively, the sorbent may be injected further downstream in the boiler, or into the flue gas duct between the air heater and the precipitator. Following baseline and optimization testing, the GR-SI technology will be demonstrated in one-year field tests at each host site for a total project duration of fifty-four months.« less