Recycling exhaust emissions of internal combustion engines within the gasification systems: Performance and analysis
Ahmed M. Salem
Abstract
The current research presents a proposed system for the recycling of the exhaust emissions from internal combustion engines (ICE) inside the air-blown gasification system. A 2D Computational Fluid Dynamics (CFD) model is investigating the novel research idea and further study the combined effects on the gasifier performance. To this end, the numerical model will be validated against wide range of operating conditions. Additionally, the effect of exhaust emissions injection along with air (the gasifying medium) on gasification, carbon conversion, system performance, syngas composition, and yield will be investigated. A new parameter – CB ratio – is defined, which is the exhaust/emissions from ICE gases to the feedstock mass ratio. Optimum values of CB are recommended between (0.05–0.25). The research idea resulted in boosting the yield of H2, and CO by 10.3, and 3.3 mol.% respectively, and correspondingly, higher heating values by 5.8% within the optimum range of CB. For the same range, N2, and CO2 emissions are found to decrease within the gasifier. The exhaust emissions stream with high temperature and rich content of CO2, and H2O resulted in higher turbulence, velocity, and mixing inside the gasifier. Thus, enhanced the gasification reactions i.e., boudouard, and water gas reactions. Moreover, producer gas yield, carbon conversion and gasification efficiencies are found to be 28, 10, and 11% higher than air gasification under the same working conditions respectively. The proposed design (20 kW gasifier) – i.e., small scale industrial gasification unit – is found to consume around 3.5 kg/hr of the ICE emissions. Thus, preserving the environment, reducing CO2 and GHG emissions, and increasing the gasifier performance. The significant outcomes of the study are applicable for different scales of air-blown gasifiers.