| 摘要 |
<p>PROBLEM TO BE SOLVED: To discharge a treated gas at an outlet of a desulfurizing system at a high temp. state to miniaturize a gas heater by recovering a pH of an absorbing soln. after contacting with surface oxide with calcium carbonate and moreover making the pH higher with calcium hydroxide or adding an org. acid or its salt to the absorbing soln. or using both. SOLUTION: SO2 is selectively absorbed to the absorbing soln. 6 by subjecting the absorbing soln. 6 to a gas-liq. contacting with a waste gas A at an absorbing tower 1, and after forming calcium sulfite, the absorbing soln. is stored in a circulation tank 7, and the calcium sulfite is oxidized with air (B) for oxidation from an air blowing device 11 to form gypsum. The soln. temp. of the absorbing son. 6 is made higher and an amount of heat exchange with the gas heater is reduced and the gas heater is miniaturize since the absorbing soln. 6 is passed through a parting plate 10 and neutralized with a calcium hydroxide (D) from the feed pipe 9 at the outlet of the circulation tank 7 to make higher the pH, and the absorbing soln. 6 is sent again to an spray nozzle 4 with the pump 5 from an absorbing soln. discharging pipe 14 after recovering the pH of the absorbing soln. 6 by adding the calcium carbonate (C) from a feed pipe 8 to the absorbing soln. 6 in the circulation tank.</p> |
