Abstract Flue gas is desulfurized by absorption in aqueous ammonium sulfite in a multiple-stage countercurrent absorber. The absorber effluent solution is regenerated by acidifying a portion thereof with ammonium bisulfate to liberate sulfur dioxide decomposing the resulting ammonium sulfate at high temperature by direct contact with hot combustion gases, and by reacting the ammonia thus formed with a second portion of the absorber effluent solution to prepare fresh ammonium sulfite absorbent solution. Regeneration is carried out at constant rate regardless of variations in the flow rates of flue gas and absorbent solution in the absorber; this is accomplished by use of surge tanks for storage of both absorbent and absorber effluent solutions.
A process according to claim 1 in which said ammonium bisulfate in step (f) is molten, whereby a substantial quantity of water is vaporized and said ammonium sulfate is formed as an aqueous slurry.
Claim 2
Dependent Claim
24 words
A process according to claim 2 in which said aqueous slurry contains from about 15 to about 30 percent by weight of undissolved solids.
Claim 3
Dependent Claim
27 words
A process according to claim 1 in which said ammonium sulfate is decomposed at a temperature in the range of about 600* F. to about 900* F.
Claim 4
Dependent Claim
27 words
A process according to claim 1 in which said ammonium sulfate is decomposed at a temperature in the range of about 700* F. to about 850* F.
Claim 5
Dependent Claim
29 words
A process according to claim 2 in which said aqueous slurry is introduced into said decomposition zone and ammonium sulfate therein is decomposed by contact with hot combustion gases.
Claim 6
Dependent Claim
39 words
A process according to claim 1 in which said flue gas stream and said absorbent solution flow at variable rates in said absorption zone, and in which the flow rates in steps (F), (g), and (h) are substantially constant.
Claim 7
Dependent Claim
36 words
A process according to claim 1 in which said fresh absorbent solution is introduced into said absorption zone at a rate which is substantially proportional to the rate of flue gas flow through said absorption zone.