Process of decreasing NO.sub.x content of exhaust gases
AssigneeMetallgesellschaft Aktiengesellschaft
InventorJochim Eschenburg
Life of this patent
Estimating the term…
Abstract
For a decrease of NO.sub.x content in the exhaust gases from cement-burning kilns by an addition of ammonia and/or ammonia-containing substances to hot exhaust gases, the exhaust gases are desulfurized at a temperature from 50.degree. to 100.degree. C. in a dry or semidry process by a mixture of raw cement powder and calcium hydroxide, and the mixed solids which have been removed the exhaust gas in a dry state in the desulfurizing stage are returned to the exhaust gas stream when it is at a temperature from 850.degree. to 1,000.degree. C.
Claims5
A process of decreasing NO.sub.x content of exhaust gases of a cement-burning kiln, comprising the steps of:
- a) adding a substance selected from the group consisting of ammonia, ammonia-containing compounds and mixtures thereof to the exhaust gases of the cement-burning kiln at a temperature from 850 .degree. to 1000.degree. C.;
- b) subsequently cooling the exhaust gases with transfer of heat to ground raw materials;
- c) dedusting the exhaust gases;
- d) desulfurizing the exhaust gases at 50.degree. to 100.degree. C. with a mixture of 30 to 75% raw cement powder and 70 to 25% calcium hydroxide to form mixed solids and desulfurized exhaust gas;
- e) removing the mixed solids from the exhaust gases in a dry state in desulfurizing step d);
- and
- f) returning the mixed solids removed in step e) to the exhaust gases prior to step d) and when the exhaust gases are at a temperature from 850.degree. to 1,000.degree. C.
A process of decreasing NO.sub.x content of exhaust gases from a power plant boiler, comprising the steps of adding a substance selected from the group consisting of ammonia, ammonia-containing compounds and mixtures thereof to the exhaust gases at a temperature from 850.degree. to 1000.degree. C.;
- subsequently cooling the exhaust gases with transfer of heat to combustion air, dedusting the exhaust gases;
- desulfurizing the exhaust gases in excess of 130.degree. C. with a mixture of 30 to 75% raw cement powder and 70 to 25% calcium hydroxide to form mixed solids and desulfurized exhaust gases;
- removing the mixed solids from the exhaust gases in a dry state during the desulfurizing;
- and returning the mixed solids so removed to the exhaust gases when the exhaust gases are at a temperature of from 850.degree. to 1,000.degree. C.
A process of decreasing NO.sub.x content of exhaust gases from a garbage-incinerating plant, comprising the steps of adding a substance selected from the group consisting of ammonia, ammonia-containing compounds and mixtures thereof to the exhaust gases at a temperature from 850.degree. to 1000.degree. C.;
- subsequently cooling the exhaust gases with transfer of heat to combustion air, dedusting the exhaust gases;
- desulfurizing the exhaust gases in excess of 130.degree. C. a mixture of 30 to 75% raw cement powder and 70 to 25% calcium hydroxide to form mixed solids and desulfurized exhaust gases;
- removing the mixed solids from the exhaust gases in a dry state during the desulfurizing;
- and returning the mixed solids so removed to the exhaust gases when the exhaust gases are at a temperature of from 850.degree. to 1,000.degree. C.
Dependencies are inferred from the claim text.