Claims
- 1. A process for reducing the nitric oxide content of a combusted gas stream, comprising:
- contacting a varying temperature combusted gas stream which comprises nitric oxide and ammonia with a first catalyst comprising a porous inorganic oxide nitric oxide reduction catalyst in a first reactor to form a first reactor effluent;
- determining the temperature of said first reactor effluent;
- conducting said first reactor effluent to exhaust when said temperature is above a threshold temperature in the range between about 220.degree. C. to about 280.degree. C.;
- cooling said first reactor effluent when said temperature is below the threshold temperature to a temperature which falls within a range from about 170.degree. C. to about 100.degree. C. to form a cooled effluent; and
- contacting said cooled effluent with a catalyst comprising an ammonium halide on a porous solid carrier at a temperature which falls within a range from about 170.degree. C. to about 100.degree. C.
- 2. A process as in claim 1 wherein the conducting of said first reactor effluent to exhaust is when said first reactor effluent temperature is above about 260.degree. C.; and
- the cooling of said first reactor effluent is when said first reactor effluent temperature is below about 260.degree. C.
- 3. Apparatus for reducing the nitric oxide content of a combusted gas stream, comprising:
- means for conducting a varying temperature combusted gas stream from a hydrocarbon burning engine, which gas stream comprises nitric oxide, to a first reactor;
- means for conducting ammonia to said first reactor;
- means within said first reactor for catalyzing the reduction of the nitric oxide with the ammonia to form a first reactor effluent, said first reactor catalyzing means comprising a first catalyst which comprises a porous inorganic oxide reduction catalyst for nitric oxide;
- means for determining the temperature of said first reactor effluent;
- means for conducting said first reactor effluent to exhaust when said temperature is above a threshold temperature in the range between about 220.degree. C. to about 280.degree. C.;
- means for conducting said first reactor effluent to cooling means only when said temperature is below said threshold temperature and thereat cooling said effluent with said cooling means to a temperature which falls within a range of about 170.degree. C. to about 100.degree. C. to form a cooled effluent;
- means for conducting said cooled effluent to a second reactor; and
- means within said second reactor for catalyzing the reduction of the nitric oxide in the cooled effluent with the ammonia therein to form a substantially nitric oxide free exhaust, said second reactor catalyzing means comprising a second catalyst which comprises an ammonium halide on a porous solid carrier at a temperature which falls within a range from about 170.degree. C. to about 100.degree. C.
- 4. An apparatus as in claim 3, including a valve which receives said first reactor effluent and control means receiving a signal representative of temperature of said first reactor effluent and shifting said valve to conduct said first reactor effluent to exhaust when said temperature is above a threshold temperature in the range between about 220.degree. C. to about 280.degree. C. and to conduct said first reactor effluent to said cooling means when said temperature is below said threshold temperature.
- 5. An apparatus as in claim 3 or 4 wherein said threshold temperature is about 260.degree. C.
CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of copending U.S. application, Ser. No. 802,207, filed May 31, 1977.
US Referenced Citations (4)
Foreign Referenced Citations (1)
Number |
Date |
Country |
411377 |
Jun 1934 |
GBX |
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
802207 |
May 1977 |
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