| Leather industrial waste generated in one year amounts up to about 1.4 million tons in our country. Due to the lack in effective processing technology, the waste has accumulated and taken up valuable land resources, and polluted the soil, groundwater and others in environment. This paper investigates the combustion of gas produced by gasification of crushed leather waste under anaerobic conditions within the gasifier in the second combustion chamber, to generate electricity or heat with heat energy released by the waste heat boiler, and to achieve the reduction and treatment of leather waste. This paper studies the gasification characteristics and combustion characteristics of leather waste with experiments, also uses CFD numerical simulation technology for the calculation of gasification and combustion process, designs gasifier head with the calculation results, and finally establishes an experimental platform for authentication.Firstly, the elemental analysis and industry analysis leather industrial waste are conducted. Thermal analysis technique is applied to the study on gasification characteristics and combustion characteristics of leather waste. The main content is the study of components of PU leather scrap tape, the gasification and combustion characteristics of different components of the fabric components in air, and the characteristics at different oxygen concentrations. The study found two phases in glial component combustion process of PU leather waste, in contrast to only one stage in the combustion process of fabric components. And the ignition temperature of glial component is lower than that of the fabric component, but the burnout temperature is higher than that of the fabric component, while the glia component is easy to get burned but not easy to burn completely. In air, when PU leather waste has less glial component content, the ignition characteristics and burnout characteristics are close to those of fabric components, and the PU leather is easy to get burn completely but not easy to get burned. The combustion characteristics index of PU leather waste decreases with the increase of glial component and it increases with the increase in oxygen concentration in the air.Secondly, the CFD numerical simulation technology is used to simulate and calculate the process with gasifier head of three different lengths (500mm,1000mm,2000mm) to generate its CO, CO2-sectional concentration and sections speed, and also to study the trajectory distribution of particles of leather scraps, and to optimize the design of the structure of gasifier head. The study found that with the increase of the gasification chamber length, CO and CO2 concentration distribution at the outlet of the gasification chamber tends to be uniform, leather waste mixture with air in the gasification chamber tends to be uniform, and residence time of the particles in the gasification chamber donut tends to be longer. The burnout rates of leather waste in gasification chamber with three different lengths all exceed 99%.Based on the results of numerical simulation and optimization, the overall layout of the gasifier head is proposed, with structure parameters calculated. Thereafter thermodynamic calculations are made and insulation structure of gastifier head and the pre-combustion power of electrical heating were checked.Finally, a small experimental system is established to conduct leather gasification combustion experiments. Experiments show that gasifier combustion zone temperature of the gasification chamber is below the design requirements, but stable combustion and gasification can be achieved in the second combustion chamber; burnout rate of leather approximates 100%. Experimental system can achieve system thermal efficiency 90.38% with a low rate in feeder, running at 28.8 percent of design load, with nitrogen oxide emissions concentration of about 400ppm. |
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