Abstract
Abstract
This paper is focused on the effects of some controllable operating parameters on the robustness of the coke/coal entrained flow cogasification process considering some uncertainties in it. In the present work, the operating variables were categorized into controllable parameters (CPs) (oxygen and steam concentrations, OC and SC) and hard-to-control parameters (temperature and coal/coke blending ratio) according to the actual modes during the cogasification process. Then, some robust response surface methodology (RSM) models, that is, mean RSM model and variance RSM model, for some important performance indexes [H2, CO, and (H2 + CO) production] with the CPs as independent variables, were found using combined array methodology. Then, the effects of OC and SC not only on the mean but also on the variance of each performance index were systematically investigated. Finally, the cogasification process was robustly optimized using the mean square criterion and desirability function. The result shows that the average production of H2 and that of (H2+ CO) increases with increasing OC but decreases with increasing SC. Additionally, higher OC suppresses the fluctuations in H2 and (H2 + CO) production, while higher SC enlarges the fluctuations in H2 production. Assuming that the variance of temperature in a gasifier is 20 °C and the variance of the coal/coke blending ratio is 5%, the multiobjective robust optimization solutions of OC and SC are 1.56 and 50%, respectively, and a satisfactory performance for high syngas production with low fluctuation can be gained.