| 摘要 |
673,165. Gasifying powdered fuel. KOPPERS CO., Inc. Dec. 7, 1949 [Dec. 7, 1948], No. 31421/49. Classes 55 (i) and 55 (ii). A combustible gas containing methane is produced by forming a suspension in oxygen under pressure of a finely-divided solid fuel such as coal or lignite, injecting the suspension in the form of a jet into an internally heated chamber where the fuel ignites and is partly burnt, introducing steam under pressure into the space between the jet and the walls of the chamber, the steam reacting with the combustion gases and unburnt fuel from the jet to give a gas containing carbon monoxide and hydrogen and finally bringing this gas under increased pressure into contact with low temperature coke which acts as a catalyst to cause conversion of some of the CO and H 2 into methane. The gasifying step in this process is the same as that described in Specification 673,164, but the other process omits the methane synthesis. In the form shown, the apparatus consists of a reaction chamber 8, a catalyst shaft 21, a dust extractor 29 and a washer 31, each unit being constructed to withstand high pressures. Finely divided solid fuel (10-25 per cent on a 4900 meshes per sq. cm. sieve) is charged into bins 1 and 2 and fed to a mixer 5 by conveyers 3 and 4. Oxygen or oxygen enriched air enters the mixer through a pipe 6 to form a suspension with the fuel, the suspension passing through a pipe 7 into the smaller end of the conical gasification or reaction chamber 8. Surrounding the pipe 7 is an annular jet through which steam, under the same pressure, enters the chambers, the steam being superheated to 400-600‹ C. by combustion of gas from burners 15. The fuel is partially burnt in the oxygen in a jet-like primary zone 12, a flowing envelope of steam surrounding this zone and serving to protect the chamber walls from its high temperature, and preventing the deposition thereon of fused ash. The gases and remaining fuel from zone 12 react with the steam lower in chamber 8 to form a gas consisting mainly of CO and H 2' which leaves the chamber at about 1200‹ C. It is cooled to about 800‹ C. by admission of cold gas at 16 and by passing into a chamber surrounded by a water jacket 17 connected with a steam boiler, the solid fuel residues depositing at 18 for periodic removal through valve device 19, whilst the gas passes through a duct 20 to shaft 21. This shaft is fed with low temperature coke through which the gas passes upwardly, the coke acting catalytically to cause methane formation by part combination of the CO and H 2 constituents. The gases then pass through the dust extractor 29 and washer 31 to outlet 32. Operating with pressures of 8-10 atmospheres, a gas with 8-12 per cent methane is obtained, whilst 40 atmospheres gives a gas containing 40 per cent methane.
|
