GB840699A - Method of gasifying pulverised coal in vortex flow - Google Patents

Abstract

840,699. Gasifying powdered coal; nozzles. SUMITOMO CHEMICAL CO. Ltd. June 20, 1958, No. 19772/58. Classes 51 (1) and 55 (1). Pulverized coal homogeneously mixed with a flux of an iron compound, such as pyrites cylinders, is gasified by a process in which the coal, entrained in a stream of air or oxygen and steam, is injected into a reaction furnace in a downwardly oblique direction tangential to an imaginary cylindrical surface coaxial with the reaction furnace, fused slag being removed from the furnace bottom while maintaining such a composition of the gas in the furnace that iron exists in the ferrous state in the vicinity of the furnace bottom; the vortex flow is made convergent in an upward direction by the exit orifice in the furnace ceiling, as a result of which a dead space is formed in the region near the conjunction of the walls and ceiling into which some of the coal particles pass, gasification thereof being thereby furthered. As shown in Fig. 1, pulverized coal entrained in air or oxygen 3 is mixed with steam 4 and passed into furnace 1 through nozzles 2 (see also Fig. 2), in such a manner that the stream impinges on the coal particles and liquid slag at the bottom of the furnace so that the whirling motion so imparted to the slag forces the slag to the outside of the furnace and so minimizes loss of coal. Drops of slag eventually fall into quenching chamber 7 where they are sprayed with water through 25, the solidified particles then falling on to a conveyer 27 immersed in water contained in trough 26. The gasifying stream in the furnace rises from the furnace floor in an ascending vortex which converges as it approaches discharge pipe 9, thereby forming dead spaces 10, into which coal still remaining as particles of more than a certain size is thrown. These particles circulate therein along paths 11 until the particle size is sufficiently reduced, whereupon the particles once more become entrained in the main stream and pass out through 9. In order to prevent a stagnant zone forming in discharge pipe 9, as a result of which solidified molten ash would build up and create a blockage, water 12 is sprayed into the pipe downstream of the orifice 22 in an upwardly oblique whirling manner through a number of sprays. The furnace feed nozzles (see Fig. 5) comprise a water-cooling jacket 14 containing steam induction chamber 18 into which passes pipe 3 for transporting pulverized coal and oxygen, and insulated pipe 4 through which steam is fed. The coal pipe 3 is tapered at 15, and straight portion 16 is detachably connected to induction chamber 18, portions 3 and 15 being mounted in auxiliary jacket pipe 21, and portion 16 being shorter than the distance between gasket 20a and slide valve 20b. To replace the pipe, the pipe and jacket are drawn through gasket 20a until end 16 has cleared slide valve 20b, which is then closed. The entire pipe may then be removed and replaced by reversing the procedure without interrupting the operation of the furnace and without loss of steam. Specification 840,700 is referred to.