Water–gas shift modeling in coal gasification in an entrained-flow gasifier. Part 1: Development of methodology and model calibration

Abstract

Most of the reaction rates for the water–gas shift (WGS) reaction were obtained from experiments under simplified laboratory conditions with specific catalysts. A few of the reaction rates without catalysts were obtained under supercritical (water) conditions with the pressure much higher than those in a typical gasifier. In either case, it is not clear how the published reaction rates can be used reliably to predict the actual WGS reaction rate in a gasifier without the presence of a catalyst and under different temperature and pressure conditions than those in the laboratory. Part 1 of this study focuses first on reviewing the published WGS reaction rates with and without the presence of catalysts, followed by calibrating the WGS reaction rate to match the experimental data taken from the quench section of an actual gasifier. Three different WGS reaction rates from Jones, Wade, and Sato are employed for calibration. The result shows that all of these published rates cannot work well in simulating the water quench process due to different ranges of temperature and pressure. The calibration is performed by adjusting the pre-exponential rate constant value (A) of each of the three reaction rates to match the experimental data. The advantage of this methodology is to obtain a global WGS reaction rates under water quench condition in less computational intensive way. However, it needs to be emphasized that the calibrated WGS reaction rates can only be applied in the range of water quench operation parameters for which it has been validated in this study. The calibrated results show that all three WGS reaction rates can be modified to match the experimental data within 2% points (or 6%) in both CO conversion rate and H2 generation. After calibrated rates are developed, complete gasification process is simulated, and the results are compared to experimental data taken from Japanese CRIEPI gasifier in Part 2.