Method of removing oxides of nitrogen from flue gas
AssigneeSteag Aktiengesellschaft
InventorsHans A. Eichholtz, Helmut A. Weiler
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Abstract
A flue gas stream having passed a flue gas desulfurization plant 2 enters a reactor 6 flowing through an activated carbon bed. The flue gas entering the reactor continuously is discontinuously blended with ammonia, thereby achieving a low ammonia content of the flue gas leaving the reactor, while maintaining a high efficiency of nitrogen oxide removal. The duration of ammonia addition and the rate of flow at which ammonia is added to the flue gas stream are controlled as a function of the desired efficiency of nitrogen oxide removal and the ammonia concentration measured in the reactor.
Claims16
A method of removing oxides of nitrogen from a continuous flue gas stream, said method comprising the steps of:
- providing a reactor with an adsorbent
- discontinuously adding ammonia as a reducing agent to said continuous flue gas stream, said discontinuous additions of ammonia to said flue gas stream comprising alternating first and second phases at different rates of ammonia addition, the rate of said ammonia addition, during each said first phase and being reduced to, at most, half the rate of ammonia addition during the immediately preceding second phase;
- passing said continuous flue gas stream through said adsorbent in said reactor thereby causing said oxides of nitrogen to react with said ammonia in the presence of said adsorbent which acts as a catalyst;
- and
- discharging the flue gas so treated from said reactor.
A method of removing oxides of nitrogen from flue gas in a reactor with an adsorbent, said method comprising the steps of:
- discontinuously adding ammonia as a reducing agent at at least one point upstream of said reactor to a continuous flue of said flue gas from which said oxides of nitrogen are to be removed, said discontinuous addition of ammonia comprising alternating first and second phases at different rates of ammonia addition, comprising regular cycles having first and second phases such that during said first phase of each such cycle a substantial quantity of ammonia is so added, and during said second phase of each such cycle substantially no ammonia is so added;
- passing said continuous flue gas stream in at least one direction of flow through said reactor containing said adsorbent;
- and
- discharging the flue gas from which said oxides of nitrogen have been so removed from said reactor.
Dependencies are inferred from the claim text.