| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent in a simple structure an abnormal temperature rise originated in combustion caused by adsorption of hydrocarbon components to a denitration catalyst. <P>SOLUTION: In a method for protecting a denitration catalyst by preventing the abnormal temperature rise of the nitrification catalyst for reducing nitrogen oxides in an exhaust gas containing the nitrogen oxides into which ammonia or urea is blown as a reduction agent, the amount of hydrocarbon adsorbed to the nitrification catalyst is sought by integrating for a predetermined time a product signal 108 obtained by multiplying the signal 106 of the total flow rate of an exhaust gas by the difference between hydrocarbon concentration signals 100, 102 of an exhaust gas inlet and an exhaust gas outlet of the denitration catalyst, and when the amount of hydrocarbon sought exceeds a predetermined set threshold value 112, the flow rate of the exhaust gas is controlled corresponding to the temperature signal 116 of the nitrification catalyst. Thus, the denitration catalyst is prevented from an abnormal temperature rise by vaporizing or even by burning the hydrocarbon adsorbed to the nitrification catalyst to increase the quantity of heat absorbed by the exhaust gas. <P>COPYRIGHT: (C)2010,JPO&INPIT |
