Product characteristics of supercritical water gasification via the preheating of hydrothermal flames: A detailed chemical kinetic simulation

Abstract

A detailed chemical kinetic model was developed for supercritical water gasification (SCWG) of methanol via the preheating of hydrothermal flames, and simulated with Chemkin. The simulation model is validated by comparisons with experimental COD removal efficiencies and gas ratios. The SCWG reaction can be divided into three stages. At the first stage, methanol mainly undergoes the steam reforming reaction to produce H₂ and CO. The water gas shift reaction that peaks H₂ yield is the dominant chemical reaction at the second stage. At the third stage, the methanation reaction becomes active and consumes H₂. The carbon dioxide promotes the methanation reaction at the third stage. The oxygen content accelerates the methanol decomposition and hydrogen formation at the beginning of the first stage, but results in lower peak values of H₂ yield. The hot water and the direct preheating have the highest and lowest peaks for H₂ yield, and higher peak values of H₂ yield are present at higher ratios of fuel to feed flow via the preheating of hydrothermal flames. The peak of H₂ yield under the preheating of hydrothermal flames is not sensitive to the reaction temperature, but higher heating values can be obtained at higher reaction temperatures.