| 摘要 |
<p>The recovery of soda liquor from Na contg. wash soln. of a waste gas purification plant comprises neutralizing a Na was soln. contg. 1,020 mg/l Na with an acid gas which produces Na sulphate of pH is approx 5, mixing the water-soluble Na sulphate with Ca hydroxide, introducing CO2 contg. air at 110 degrees C via a ring blower into the wash soln. whereby (a) 2NaOH, (b) CaCO3 and (c) CaSO4 are formed, removing CaSO4 by filtering and converting CaCO3 to difficult-to-dissolve Ca salts by means of CO2, and removing the Ca salts by filtering. The NaOH is recycled to the wash plant for adjusting the alkalinity of the wash soln. Process avoids blocking of the filter plant usually caused by crystallization of excess amts. of Na sulphate and because of a too high Ca content. The quantity of NaOH is kept at a minimum.</p> |
