Mathematical Modeling of Waste Engine Oil Gasification for Synthesis Gas Production; Operating Parameters and Simulation

Abstract

The release of waste oil into the environment will have destructive effects. Gasification is an advanced and environmentally friendly process for converting waste oils into clean combustible gas products. Thermochemical equilibrium modeling has been used in this method to predict the performance of a downdraft gasifier. This model uses the thermodynamic equilibrium of gasification reactions to predict the gases produced in the gas mixture. Having the percentage of gas components produced, different characteristics of the produced gas including H2:CO ratio, process temperature and calorific value of the produced gas, Cold gas efficiencies and carbon conversion efficiency are also obtained. The effect of equivalence ratio, oxygen enrichment and pressure on gasification properties is analyzed. The simulation results are compared with the reported experimental measurements through which the numerical model is confirmed. The results indicated that the equivalence ratio (mole of air in gasification per mole of air in combustion) between 0.4 and 0.42 had the potential to yield the highest calorific value about 10.5 Mj.m-3. The temperature of gaseous mixture in this range will be 2000 K that can be used for other processes such as steam generation. Using pure oxygen instead of air reduces the efficiency of the gasifier from 78% to 55%. Pressure changes from 10 to 65 bar cause gas mixture temperature changes from 1684 to 1690 Kelvin. The H2:CO ratio decreases from 1.6 to 0.6 with increasing equivalence ratio and increases from 1.2 to 1.6 with changes in oxygen enrichment.