Study On Supercritical Water Gasification Mechanism Of Typical Organic Waste With High Water Content

The output of organic waste high-water content is huge,which causes serious environmental pollution.On the other hand,organic waste with high water content has high energy utilization value and great potential to transform it into fuel.Therefore,the development of an organic waste with high-water content harmless and resource treatment technology is extremely urgent.Supercritical water technology has developed rapidly in recent years and is an ideal technology for the treatment of organic wastes with high water content.In supercritical water,organic waste with moisture content over 90% can be treated without high energy consumption in the drying process,with short treatment time,high gasification efficiency and bright application prospects.The food waste and black liquor were used as the representative organic wastes with high-water content.The effect of the key operation parameters on the gasification reaction was studied.The response surface methodology was used to design experiments and predict experimental results.A two-step gasification process assisted by ionic liquids was put forward.Finally,the reaction kinetics and reaction mechanisms of food waste were studied.The research contents and innovation points are presented as follows:(1)In the supercritical water quartz tube reactor with high temperature and high pressure,the gasification characteristics of alkali lignin,a model compound of papermaking black liquor,in supercritical water under different conditions were studied.(2)The effect analysis of supercritical water gasification of food waste under different conditions was conducted.Through the response surface method,the functional relationships between the three most important index(the temperature,concentration and residence time)and the responses(carbon gasification and gas yield)were obtained.A new the two-step supercritical water gasification method assisted by ionic liquid was proposed.In this way,the gasification efficiency and methane yield of the food waste were significantly improved.(3)The gasification kinetics of supercritical water gasification of food waste were studied,and more than 20 reaction kinetics models were analyzed and compared.The results show that all the classical kinetic models underestimate the experimental results.Therefore,a semi-empirically modified random pore model(MRPM)was proposed to predict the influence of metal elements on the kinetic behavior of supercritical water gasification of food waste.MRPM can precisely predict the gasification results.Finally,the reaction mechanisms were concluded.