Reclaiming Converter Gases for Producing Hydrogen

Abstract

Ways of reducing the consumption of natural gas for the existing methods of producing hydrogen by subjecting natural gas to steam-water conversion are analyzed. The basic process flow scheme for producing hydrogen according to the above-mentioned method is developed and analyzed under the conditions of an ideal thermodynamic model adopted proceeding from the intensive energy conservation theory. It is shown that the specific consumption of natural gas for producing hydrogen under the conditions of a thermodynamically ideal model is 0.327 m3/m3 H2 that is 29 % lower than that achieved in the best methods for producing hydrogen from natural gas. A way to reduce the consumption of natural gas is proposed which involves the use of high-temperature secondary resources, specifically, converter gases of steelmaking production. Good prospects expected from using converter gases for these purposes are stemming from the fact that these gases are reclaimed to a poor degree, and that there is a need to increase hydrogen production at metallurgical plants. A hydrogen production method involving utilization of the thermal and chemical potential of converter gases is proposed. According to the proposed method converter gases are subjected to energy-chemical accumulation by natural gas which gives rise to a larger amount of carbon monoxide along with generation of hydrogen. After finishing the energy-chemical accumulation stage the obtained gas is mixed with steam and forwarded to the reactor in which carbon monoxide is subjected to steam-water conversion, which contributes to increasing the content of hydrogen in the gas mixture. After that the gas mixture is cooled again, the process condensate is separated and hydrogen is extracted by using the short-cycle adsorption method. The proposed technology allows a continuous hydrogen production process to be organized. When there is no yield of converter gases, hydrogen-containing gas produced by steam-water conversion of natural gas is used. An analysis of the proposed hydrogen production method shows that the consumption of natural gas can be reduced down to 0.148 m3/m3 H2 that is 68 % lower than in the best methods for producing hydrogen from natural gas.