Experimental Study On Gasification Reaction Characteristic Of Coal Char With Autothermal Solid Heat Carrier

The energy crisis of the21st century is a big issue which has caused the attention of the whole world. The energy is the foundation of the development of economic and technology. China, which has a urgent demand for energy, is at the stage of rapid development as the largest developing country. Facing the present energy crisis and environmental pollution, the only way to maintain the rapid development of economy and technology is to finish the following two aspects:Firstly, the coal resources should bp used fully and rationally. With the depletion of oil and gas, coal gasification technology has become the energy buffer which can produce the new energy to replace the old one. The coal gasification is the brige of the energy transition period because its development has a direct influence on the stability of this transition. Secondly, the waste heat should be recycled effectively. The recycling of the waste heat in the steel industry of china has a extensive prospect due to the first rank of annual steel output of china in the world. So large amounts of waste heat, which includes the waste heat of blast furnace slag mainly, will be produced in the steel industry. In this work, the experimrntal design of utilising the waste heat of blast furnace slag to realize the coal gasification is proposed. This design can not also realize the the full use of the coal resources, but also recycle the waste heat of blast furnace slag effectively.The characteristics of the coal gasification reaction with self-heating solid heat carrier, which is made of the blast furnace slag, are studied experimentally to provide guidance for the industrial production. The main contents are as follows:(1) According to the physical and chemical characteristics of the solid slag and the pulverized, the experimental studies of gasification for different coals by using the heat carrier in fixed bed system are made. The experimental design has advantages of low requirement for laboratory equipment, simple operational processes, high feasibility and high operbility. On the other hand, the objective of instant pyrolysis and gasification can be easily achieved utilizing the rapid heat trasfer between the blast furnace slag and the the pulverized.(2) The non-isothermal thermogravimetry is used in the experiments for different mass ratios between the blast furnace slag and the pulverized by STA409PC thermal analyzer. The initial temperatures and chemical properties of coal gasification are compared for different ratios of slag and coal, different coals and different gasification reaction rates. The results show that:The blast furnace slag can catalyze the coal gasification; the catalytic effect is best when the ratio of slag and coal is3:1; the gasification reaction increases as the heating rate increasing.(3) The experimental datas obtained from STA409PC thermal analyzer are analyzed using the Li Chung-Hsiung integral method, the optimal reaction mechanism functions from the21kinds of existing gas-solid reaction mechanism models is found, and A5model is generally applicable for reaction mechanism of different gasification conditions. The activation energy and preexponential factor of coal gasfication are obtained using the Satava-Sestak method. The results show that activation energy and pre-exponential factor decrease with the heating rate increasing, but the influence of blast furnace slag on activation energy and pre-exponential factor is irregular. The compensation effect between the activation energy and the preexponential factor is found on the basis of obtaining the kinetics equations of different reactions.(4) A miniature-testing fixed bed device with heat carrier is designed for coal gasification, and a deep research of the coal gasification characteristics for different coals, pulverized coal particle sizes, reaction temperatures and flows of CO2. The conclusions are as follows:The coal gasification technology by using the blast furnace slag as the heat carrier is applied to varies coals. When the reaction temperature reaches1100℃, the conversion rate can reach more than80%and the gas calorific value can reach8000KJ/m3even for inferior Sherman coals and Fuxin Coals; The blast furnace slag, which are used as the heat carrier, are both the heat source and the catalyst for gasification reaction;1100℃is the best temperature for coal gasfication. Further heating will lead to a certain adhesion for blast furnace slag, which is not conducive to heat and mass transfer in the fixed bed; This experimental system has a strong adaptability to pulverized particle sizes. The particle sizes of coals ranging from80to100mesh have a good gasification characteristics in the experiments; When the flow of CO2is 0.35m3/h, the gasification characteristics is the best; There are almost not CH4in the gasification products by using the blast furnace slag as the carrier. So the combustible gas are only CO and H2in the gasification products, which can promote the gasification products to be used in the chemical industry.