GB947165A - Improvements in or relating to methods and apparatus for the production of combustible gas - Google Patents

Abstract

A cyclic process for producing combustible gas by a catalytic reforming of fluid hydrocarbons includes in each cycle a plant-heating period in which a hot gaseous medium is passed in one direction through a bed of catalyst and then through a boiler or vaporizer to raise steam without passing through a regenerator, and further hot gaseous medium is passed in a direction opposite to said one direction through the regenerator to heat the latter without passing through the catalyst material, and a gas-making period in which a gasification medium (e.g. steam which may contain air and CO2) is passed in one direction through the preheated regenerator, mixed with at least one hydrocarbon, and the resulting mixture is passed through the preheated catalyst bed to provide a hot combustible gas which is cooled by passage through the boiler or vaporizer. The hydrocarbon may be a distillate oil or propane, butane, or a mixture thereof. The apparatus consists of a catalyst vessel 1 containing a bed of catalyst 2 consisting, for example, of lime or nickel supported on alumina or magnesia, a regenerator vessel 7, a waste-heat boiler 28, a wash-box 38, two stack valves 13 and 36, and a washer-cooler vessel 41. During the gas-making period both the stack valves are closed and while steam enters vessel 7 at 51, gaseous or liquid hydrocarbon feedstock is fed into the injector 22, the superheated steam and hydrocarbon mix in the upper end of vessel 9 and pass through the catalyst bed 2 where the hydrocarbons are reformed into combustible gas. The combustible gas passes through the tubes of the boiler 28 to the wash-box 38, and is finally washed and cooled in the vessel 41. At the end of the make-period, the supply of hydrocarbon is stopped and the plant is purged with steam to sweep out the combustible gas into wash-box 38. For the reverse-flow plant heating, the stack valve 36 is closed and stack valve 13 is opened. Hot combustion products of fuel and <PICT:0947165/C3/1> air admitted at 15 pass downwardly through heat-storage elements 8 and pass to waste through stack 12. For the forward-flow plant heating, the stack valve 13 is then closed and stack valve 36 is opened, combustion products from the burner 15 pass through the catalyst bed 1, to the boiler 28, and to waste through the stack 35. At the end of the forward flow plant-heating period the supply of fuel and air is stopped and steam is passed into vessel 7 at 51 to pass through the plant and discharge at stack 35. The temperature of the mixture in the make-period is below 1200 DEG C., and the oxygen content of the mixture is preferably below 8% by volume. An alternative form of the invention describes the forward and reverse flow heating taking place simultaneously with both stack valves open. In this case the flows are controlled relatively to one another by a throttle valve, e.g. a butterfly valve, in the conduit 11. Specification 947,164 is referred to.