Nitrogen oxide and sulphur oxide removal from combustion gas - by treatment with lime suspension contg. ferrous chelate and oxidn. of calcium sulphite formed

摘要

Treatment of NOx (I) and SOx (II) in waste combustion gases involves contact with an absorbent soln. (III) contg. suspended lime and an Fe (II) chelate cpd. (IV) to absorb (I) and (II), with formaton of CaSO3. The CaSO3 is oxidised to CaSO4 and this and (IV) are sepd. from the soln., then the soln. is hydrolysed to form (NH4)2SO4. (NH4)2SO4 and CaSO4 can be recovered without the formation of any undesirable or harmful substances. In an example, (I) contg. 10% water, 5% O2, 11% CO, 200 ppm NO and 500 ppm SO2 was 80% denitrified and 95% desulphurised by absorption in (II) contg. 50-200 g/l limestone and 0.01-0.2 mole/l Fe(II) EDTA complex.