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U.S. Department of Energy
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Enhancing the use of coals by gas reburning-sorbent injection

Technical Report ·
DOI:https://doi.org/10.2172/6935667· OSTI ID:6935667

Clean Coal Technology implies the use of coal in an environmentally acceptable manner. Coal combustion results in the emission of two types of acid rain precursors: oxides of sulfur (sox) and oxides of nitrogen (NO[sub x]). This Clean Coal Technology project will demonstrate a combination of two developed technologies to reduce both NO[sub x] and SO[sub x] emissions. Gas reburning and calcium based dry sorbent injection. The demonstrations will be conducted on two pre-NSPS utility boilers representative of the US boilers which contribute significantly to the inventory of acid rain precursor emissions. Gas reburning is a combustion modification technique that consists of firing 80--85 percent of the fuel (corresponding to the total heat release) in the lower furnace. Reduction of NO[sub x] to molecular nitrogen (N[sub 2]) is accomplished via the downstream injection of the remaining fuel requirement in the form of natural gas (which also reduces the total SO[sub x] emissions). In a third stage, burnout air is injected at lower temperatures in the upper furnace to complete the combustion process without generating significant additional NO[sub x]. Dry sorbent injection consists of injecting calcium based sorbents (such as limestone, dolomite, or hydrated lime) into the combustion products. For sulfation of the sorbent to CaSO[sub 4], an injection temperature of about 1230[degrees]C is optimum, but calcium-sulfur reactions can also take place at lower temperatures. Thus, the sorbent may be injected at different locations, such as with the burnout air, at the exit from the superheater, or into the ducting downstream of the air heater with H[sub 2]O added for humidification. The specific goal of this project is to demonstrate NO[sub x] and SO[sub x] emission reductions of 60 percent and 50 percent, respectively, on two coal fired utility boilers having the design characteristics mentioned above.

Research Organization:
Energy and Environmental Research Corp., Irvine, CA (United States)
Sponsoring Organization:
DOE; USDOE, Washington, DC (United States)
DOE Contract Number:
FC22-87PC79796
OSTI ID:
6935667
Report Number(s):
DOE/PC/79796-T28; ON: DE92041299
Country of Publication:
United States
Language:
English