Steam gasification of municipal solid waste with subsequent tar cracking for ultra-low tar, hydrogen-rich syngas production

The uptrend in municipal solid waste (MSW) generation poses a serious threat to human wellbeing and the environment, also having added economic penalties for its handling and storage. The problems associated with MSW can be addressed by employing effective waste management techniques, and if the generated wastes are utilized to produce syngas or other value-added products, this will also help to cater to the ever-increasing energy need for the modern world. In this article, a novel MSW to H₂-rich syngas system has been proposed, validated with different experimental works, and analyzed through parametric variation and three-step sequential parametric optimization. A comprehensive steam gasification model has been developed that includes the formation of tar as well, and the subsequent tar cracking sub-system has been developed and integrated to the main unit, i.e., steam gasification process, to have a complete, realistic steam gasification model. The syngas produced by the steam gasification process has been mixed with the tar-cracked syngas to analyze the stage-wise syngas quality, and finally, process optimization has been performed for multiple output parameters considering a three-step optimization approach. It is observed that the model yields clean and dry H₂-rich syngas having an LHV of 17.05 MJ/kg with a combined system efficiency of 83.02%, 20-35% higher than conventional setups under comparable operating trends. On the other hand, the H₂ content at this condition is about 54%. However, H₂ content as high as 63% is achievable from the developed model at higher steam to MSW ratio operations.