| 摘要 |
PURPOSE:To provide an apparatus and method for converting efficiently NOx in exhaust gas, the temperature of which ranges from room temperature to a high temperature, into harmless compounds. CONSTITUTION:An adsorption column 5 filled with an adsorbent for NOx is installed in front of a reaction column filled with a denitration catalyst 14. When the temperature of exhaust gas is low, the gas is fed to the adsorption column 5; when the temperature is high, the gas is fed directly to the reaction column from a bypass 8 without passing through the adsorption column 5. For low temperature exhaust gas with its NOx concentration being a defined value or below, a part or all of the exhaust gas which passed through the adsorption column 5 can bypass the reaction column. The addition of a reductant for NOx is controlled on the basis of the measured value of a concentration sensor for NOx in the exhaust gas between the adsorption column 5 and the reaction column. A NOx concentration sensor 9 and a means for measuring the rate of change of NOx concentration by time are installed downstream from the reaction column, and the addition of the reductant can also be controlled based on the measured values. |
