PROCESS FOR PRODUCING SUPERHEATED STEAM IN HEAT EXCHANGE WITH A SYNTHESIS GAS WHICH CONTAINS CARBON MONOXIDE, CARBON DIOXIDE AND HYDROGEN AND WHICH IS TO BE CATALYTICALLY METHANISED, AND APPARATUS FOR CARRYING OUT THE PROCESS

摘要

Only a part of the synthesis gas supply is passed through a first internally cooled catalytic reactor (1) and the hotter gas coming out of it is reunited with the remaining gas supply for passing through an adiabatic reactor (2) that is followed by a heat exchanger (3) on its way to a second internally cooled reactor (4) in which the methanization reaction is completed. Water is heated up to practically the saturated steam temperature in the cooling system of the last mentioned reactor and is converted to saturated steam in the cooling system of the first internally cooled reactor. The saturated steam is superheated in the above-mentioned heat exchanger. To make the process run more smoothly a steam drum is provided through which the hot water piping between the cooling systems of the two internally cooled reactors runs and the saturated steam is brought into the steam drum and from it to the heat exchanger before it is superheated. Additional heat exchangers are used for first preheating of the water and for two stages of preheating the synthesis gas. Adjustments of the proportion of the synthesis gas that goes through the first internally cooled reactor makes possible a control that assures that the outlet temperature of the adiabatic reactor will not exceed a safety limit required for the stability of the catalyst. No mechanical propulsion, nor compression, of the gas is necessary at any stage, nor any recycling, nor introduction of steam for control of the process.