| 摘要 |
<p>PURPOSE:To reduce the consumption of an absorption assistant when performing wet treatment of waste gas containing SO2 using limestone as an absorbent by feeding gaseous NH3 into the waste gas and heating a part of the liquid absorbent in a stage where it is discharged to outside the system to recover and recycle NH3 as gas. CONSTITUTION:Gaseous NH3 is fed from lines (a), (b) into a flue 1 into which coal-fired waste gas is introduced. In an absorber 4, a slurry circulated by a line (c) comes into contact with the waste gas to absorb and remove SO2 and most of gaseous NH3. In an absorber tank 6, air is fed from a line (d) to the bottom part and sulfite ions formed by SO2 absorption is oxidized to form gypsum. A part of the circulated slurry is drawn out as drainage by a line (i). The drawn-out drainage is first fed to a pH conditioning tank 11, and strong alkali is added there by a line(j). After adjusted to >=pH 10, the drainage is sent to a heater 12, where ammonium salt in the liquid is recovered as gaseous NH3 which is fed again into the waste gas by the line (b).</p> |
