Process Analysis And System Optimization Of Hydrogen Production By Gasification Of Organic Solid Waste

With the rapid development of the social economy,organic solid waste increases accordingly,so it is concerned by the public to recycle organic solid waste and reduce its environmental impact.Focusing on the resource utilization of organic solid wastes such as kitchen waste,the exergy efficiency,economic benefit and environmental impact of kitchen waste gas gasification process,plasma gasification process and plasma gasification syngas coupling chemical chain process were investigated respectively.In addition,the carbon footprint and water footprint distribution of municipal sludge plasma gasification process were analyzed on the basis of previous studies.This work provides an alternative idea for hydrogen production from organic solid waste.In order to realize the effective disposal of organic solid waste,the gasification process of food waste by entrained-flow bed gasification,plasma gasification process and plasma gasification coupling chemical looping process were simulated and analyzed comprehensively by using steam as gasification agent.A gasifier model was established based on the Gibbs free energy minimization principle,and the analysis of the simulation data showed that the hydrogen production capacity of the entrained-flow bed gasification process increases with the increase of temperature,and the regional raw material composition difference has no significant effect on the hydrogen production capacity.Exergy efficiency,economic benefit and environmental impact analysis further discussed the overall feasibility of the above processes.Overall exergy efficiency of food waste entrained-flow bed gasification for hydrogen production was 64.86%.Exergy efficiency of plasma gasification was the lowest,only 31.44%.The production cost of plasma gasification technology is the highest,which is 2449.82 USD/t H2,according to the economic indexes such as raw material consumption,production cost and total capital investment.High energy consumption of plasma torches is one of the key factors affecting the production cost.Plasma gasification coupled chemical looping process can use high temperature gas to generate electricity,which can reduce part of energy consumption.Using global warming potential and acidification potential to analyze the environment of hydrogen production process of food waste,carbon dioxide directly or indirectly generated from acid gas removal unit still has a high global warming potential,and adopting more efficient absorbent is helpful to slow down this trend.To further quantify the environmental impact of municipal sludge plasma gasification process.Life cycle carbon footprint and water footprint of municipal sludge plasma gasification process for hydrogen production were analyzed by life cycle evaluation method.In the basic scenario,the process has a carbon footprint of 950 kg/GJ H2 and a water footprint of 3.21 m~3/GJ H2.The acid gas removal unit had the highest carbon footprint,accounting for 24.04%of the total emissions.Using low-pressure nitrogen for acid gas desorption is helpful to reduce carbon emission.Life cycle water consumption mainly comes from power consumption and optimizing power structure helps to reduce water footprint.The regional analysis of the power structure show that the carbon footprint of the regions dominated by hydropower(Sichuan,Qinghai,Tibet and Yunnan)is only 20%of that of the basic scenario,while the water footprint is about three times that of the basic scenario.With the help of sensitivity analysis,the fluctuation of carbon footprint and water footprint under 24 scenarios was studied.It was found that improving hydrogen production efficiency or reducing energy consumption could significantly improve environmental performance.In this paper,through the study of the resource treatment technology of food waste,the potential value of using food waste as raw material to produce hydrogen is expounded,which provides a novel idea for the effective treatment of food waste.The evaluation of the life cycle of municipal sludge plasma gasification process is helpful to clarify the carbon emission and water resources consumption during the operation of municipal sludge plasma gasification process,and provide data support for the further development of the process.Overall,the series of this work for organic solid waste resources treatment in the process of exploration,carbon footprint and water footprint assessment,to optimize our existing energy structure is of great significance.