| 摘要 |
<p>PROBLEM TO BE SOLVED: To make the concentration of an absorbent for obtaining an objective denitrification performance easily controllable by adopting an oxidation-reduction potential as a means to adjust the concentration of the absorbent in compliance with the load of a nitrogen oxide, when the nitrogen oxide in the gas phase is wet-absorbed and removed. SOLUTION: A ventilation gas 1 generated in an automobile tunnel or the like is first absorbed by a blower 2 and dust is removed from the gas 1 using an electric dust collector 3, and further the gas is brought into contact with an ozone with the help of an ozonizer 4 to oxidize NO contained in the ventilation gas 1 into NO2 . Next the ventilation gas 1 is introduced into an absorption column 5, so that the NO2 is brought into contact with an absorbing solution in a gas and liquid contact mode to absorb the NO2 from the gas phase to the liquid phase and remove the NO2 . The ventilation gas 10 cleaned after the removal of the NO2 is emitted into an atmosphere. In this case, a calculation device 17 drives under control a feed pump 19 for an absorbent based on the oxidation-reduction potential of a storage tank liquid 9 measured by an ORP meter 16 and the concentration of NOx in the gas phase measured by an NOx analytical gauge 14, so that the oxidation-reduction potential complying with the load of the concentration of the NOx at the inlet of the absorption column 5 is obtained.</p> |
