Waste heat recovery system
AssigneeW. R. Grace & Co.-Conn.
InventorsEdward M. Smith, Richard C. Cornelison
Life of this patent
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Abstract
There is provided a waste heat recovery system characterized by a boiler assembly including a heat recovery steam generator through which exhaust gas is flowed. The boiler assembly includes a high temperature steam tube heat exchanger, or superheater, and at a location downstream therefrom a water tube boiler. An ammonia gas injector is utilized for injecting ammonia into the exhaust gas stream which injector is located upstream of the superheater and water tube boiler. Finally, there is provided a low temperature selective catalytic reduction unit located downstream of the low temperature water tube boiler or evaporator. This arrangement simplifies retrofitting of existing heat recovery systems.
Claims16
A waste heat recovery system comprising in combination:
- (a) a conduit for conveying an exhaust gas stream;
- (b) a boiler assembly connected to said conduit including a heat recovery steam generator through which said exhaust gas is flowed, and characterized by a high temperature steam tube heat exchanger and, at a downstream location relative thereto, a water-tube boiler;
- (c) an ammonia gas injector for injecting ammonia gas into the exhaust gas stream and located upstream of the water-tube boiler in juxtaposition to the exhaust gas source;
- and
- (d) a low temperature selective catalytic reduction unit located downstream of the water-tube boiler.
A waste heat recovery system comprising in combination:
- (a) a conduit for conveying an exhaust gas stream from a gas turbine generator;
- (b) a boiler assembly connected to said conduit including a heat recovery steam generator through which the exhaust gas is flowed and characterized by a superheated steam generator, a primary evaporator and a secondary evaporator in that order;
- (c) an ammonia gas injector for injecting ammonia gas into the exhaust gas stream and located ahead of or upstream from the superheated steam generator and the primary evaporator;
- and
- (d) a low temperature selective catalytic reduction unit located downstream of the secondary evaporator for removing substantially all of the NO.sub.x from the exhaust gas stream by catalyzed reaction of the ammonia with the NO.sub.x in said exhaust gas stream.
Dependencies are inferred from the claim text.