Equilibrium of water gas with carbon

Abstract

The calculated possible parameters of equilibrium of water gas with carbon are presented in the form of spatial (3-dimensional) diagram in coordinates “ xCO – xH2 – T ”,. It can be supplemented with a graph of isothermal projections of isothermal section surfaces onto the plane “ xCO – xH2 ”. Different ways of obtaining gas atmosphere with oxygen potential sufficient to reduce metal oxides are explored. The most technological method of obtaining gas mixture capable of reducing metal oxides is heating water vapour in contact with carbon. In this case the resulting water gas composition is determined by heating temperature only. Maximum concentration of hydrogen xH2 reaches 0.5 when “H2O – C” is heated to ~ 900 K, and heating to temperatures above 1100 K produces a mixture of reducing gas agents with equal concentrations xCO = xH2 = 0.5. Heating gas mixtures “H2O – CO2” in contact with carbon produces water gas with reduced concentration of H2 and increased concentration of CO. Gas atmosphere (H2 – H2O – CO – CO2) of any composition can be obtained by heating mixtures “H2 – CO” in contact with carbon. Formation of CO2 occurs as a result of the dissociation reaction of CO and water vapor by the reaction H2O + CO = H2 + CO2.

A technique of quantification of the carbon gasification with water vapor H2O carbon dioxide CO2 is presented. Calculations showed that gasification reactions C + CO2 = 2CO and C + H2O = CO + H2 can occur both forth and back depending on the composition of the initial gas mixtures and temperature.