METHOD AND APPARATUS FOR GAS PURIFYING COMBINED WITH HEAT UTILIZATION

The equipment removes dust from gas as well as gaseous pollutants such as sulphur and nitrogen oxides. The gas is cooled, using a heat exchange medium, to a temp. above the dew point. Dust and gaseous pollutants are removed by scrubbing. The clean, saturated gas is heated to a temp. above the dew point, using a portion of the heat transfer medium used previously to cool the dirty gas. The unused heat content of the heat transfer medium is also utilised, in another heat exchanger. Dust and polluting gases are removed in one step by passing the gas through an aq. solution of sodium sulphite. This soln. is regenerated by mixing with slaked lime and then recirculated. The diluted soln. is strengthened by the addition of calcined soda. The proposed equipment is based on a scrubbing column with a gas cooling heat exchanger in the gas inlet pipework and a gas heating heat exchanger in the discharge pipework. The two heat exchangers are inter-connected with suitable pipework which should preferably be provided with a branch to a heat recovery unit. The column is provided with a scrubbing solution collector, which is piped to a spray head in the column. The scrubbing solution is regenerated in a closed circuit, comprising the collector, lime addition tank and settler unit, with inter-connecting pipework. A calcined soda proportioning unit is also connected to the collector.