Study On The Degradation Characteristics And Evaluation Of Waste Plastics In Supercritical Water

Various plastic products are widely used in people's life and production.With the increasing use of plastic products,the total amount of plastic waste is also increasing.Improper disposal will not only cause a waste of resources but also harm the environment.At present,the traditional plastic treatment technology,such as landfill and incineration,still causes harm to the environment and can not meet the requirements of clean and environmental protection.Based on the research and development of science and technology plan of Hunan province key plan: black smelly water sediment efficient hydrothermal gasification technology development and system integration based on [2018k2019],combining with the relevant basic theory of supercritical water and existing research results of supercritical water gasification of polymer,composite by using the combined method of process model and the experiment,studies the plastic in supercritical water gasification characteristics,environmental impact analysis and thermodynamic analysis.The research on the gasification characteristics of plastics in supercritical water,as well as the thermodynamic effect and environmental impact analysis of supercritical water gasification system has high guiding significance and application value.In this paper,the gasification characteristics of plastics were studied by the method of simulation and experiment,and the environmental impact and thermodynamic analysis of the supercritical water gasification system were carried out.The main work and innovation of this paper are as follows:(1)In supercritical water gasification the existing research,on the basis of using can satisfy the quartz tube of high temperature and high pressure supercritical water gasification reactor,the four kinds of single plastic mixing plastic model and a water bottles in supercritical water gasification characteristics under different working conditions are studied.At the same time,using the orthogonal experiment method to design the about the reaction temperature,reaction time and mass concentration of three factors,four levels orthogonal experiment table,the test scheme is designed.At the same time,a continuous supercritical water gasification system was designed and built,with a rated working pressure of 25 MPa and a maximum working flow of 18kg/h.The key components of the system,including heat exchanger,cooler and preheater,were independently designed and manufactured.(2)Based on the plastic quartz tube in supercritical water gasification system of orthogonal experimental results,the first to use to compare average analysis respectively analysis of reaction temperature,reaction time and concentration on the properties of supercritical water gasification,the supercritical water gasification reaction regularity of various plastic and obtain the best effect of gasification parameters,and then use the poor analysis and variance analysis of the quantitative calculation and analysis of the various factors of influencing the gasification for primary and secondary status and influence,and finally compares the gasification characteristics of different kinds of plastic analysis,summarizes the reaction mechanism of plastic in supercritical water.(3)Based on supercritical water gasification of the continuous system built using Aspen plus software process model,study the system enlarged the supercritical water gasification performance,on the continuous system of supercritical water gasification of plastic process simulation analysis,compare the experimental results with simulation results comprehensive analysis gasification characteristics of continuous system is obtained.At the same time,the environmental impact analysis and thermodynamic analysis of the process results were carried out,and the prospect of large-scale application of the continuous system in supercritical water gasification treatment of plastic waste was obtained.