GB498223A - Removal of nitrogen oxides from gaseous combustion products - Google Patents

Abstract

<PICT:0498223/III/1> Nitrogen oxides are eliminated from an inert gaseous combustion product resulting from the combustion of carbonaceous material by compressing the inert gas at a pressure and for a time which are co-ordinated in order to effect the oxidation of lower oxides of nitrogen to render them soluble in water and thereafter removing the nitrogen oxides by washing or scrubbing with water. The time required for the reaction is inversely proportional to the cube of the gas pressure; the conversion is complete if gases containing 0,8-1,0 per cent of oxygen are subjected to a pressure of 300 lb. per sq. inch for 1 1/2 minutes. Stack gases, combustion gases from chambers fired by oil, petroleum gases, gasolines or coke and exhaust gases from internal-combustion engines may be treated by the process. Exhaust gases from an internal-combustion engine 1 pass through a pipe 5a, to a preliminary cleansing scrubber 3 and then through a pipe 6a to a compressor 2 which is coupled to the engine 1. The compressed gases are cooled in a cooler 19 and are then scrubbed in a scrubber 18 under high pressure by means of water. By a co-ordination of the speed of flow of gases and the size of the conduit system between the compressor and the high-pressure scrubber, the oxidation of the nitric oxide in the moving inert gas is completed before the scrubber is reached. The gases pass from the high pressure scrubber through one or other of the activated carbon filters 20, 21 to the delivery conduit 12. The pressure in the high pressure system is controlled by a constant pressure valve 41. A constant pressure is maintained in the scrubber 3 by means of a valve 15 inserted between the scrubber 3 and the compressor, and a constant pressure at the compressor intake is maintained by reintroducing some of the inert gas from the conduit 12 through conduit 6b and valve 16. The flow of cooling water to the cooler 19 and the flow of water to the scrubbers 3 and 18 is controlled by a valve 31 actuated by a relay 31a in an electric circuit 32 including a fluid pressure control switch 33 arranged in the oil feed line 34 of the engine 1. A two way valve 11 is operated by a relay 10 so as either to discard the gases or deliver them for use through a conduit 14a depending on the thermal conductivity measurements made by the analysis board 8. A two-way valve 42 controlled by a relay 42a releases the pressure under starting conditions, being controlled by an electric circuit 44 including the fluid-pressure control switch 33 and a thermostatic switch 45 in the cooling-water outlet from the engine. The flow of water cooling the engine and the compressor is controlled by a valve 35 and relay 35a which is operated by a thermostatic switch 38 in the cooling-water outlet. Specification 390,551, [Group XXVII], is referred to. The Specification as open to inspection under Sect. 91 comprises also a thermostatic switch 46 which grounds the magnets 48 when the cooling water overheats and thus stops the engine. This subject-matter does not appear in the Specification as accepted.