REACTION TUBE OR VESSEL FOR AN EXOTHERMIC CATALYTIC GAS REACTION OF A HETEROGENEOUS GAS MIXTURE, ESPECIALLY FOR METHANATION

摘要

A methanation reaction of a gas containing hydrogen, carbon monoxide and carbon dioxide which is exothermic and takes place in a bed of solid catalyst particles in a reaction vessel through which the reaction gas flows is substantially improved by the use of an apparatus in which an upstream section and a downstream section, both containing particles of the same catalyst, are provided, the sections having different cross-sectional dimensions and appropriate lengths. The reaction vessel is cooled by pressurized water confined by an external pressure container. The ratio of the hydraulic diameter of the first section to the equivalent diameter of the catalyst particles therein is less than the corresponding ratio for the second section; and the length of the first section is such that the reaction gas, after having reached a maximum temperature, is cooled down, before the gas passes into the second section, to a temperature low enough for the temperature in the second section to remain below the maximum permissible temperature. The length of the second section needs to be only enough to establish thermodynamic equilibirum at a temperature corresponding to the desired product gas quality, preferably between the range between 311.degree. and 370.degree.C. For reduction of the hydraulic diameter in a tube of given dimensions, inert particles or confining bodies can be put in the tube along with the catalyst particles.