| Nowadays, the demand of calcium carbide(CaC2) industry for production of acetylene is larger, so it has important significance to the use of various carbon sources. In view of the disadvantages of the low output while high consumption during the CaC2 production by electricity-heating technology, oxygen-heating technology for CaC2 has made significant progress. This paper relies on the study about the combined-moving bed reactor of oxygen-heating synthesis process developed by BUCT, granulates composite particle by coal and hydrated lime powder which is suitable for the oxygen-heating synthesis process, provides the granulation method、geometry and operating parameters of the reactor design as the reference for industrialization.One of the composition of particle is coal, which mass transfer and reaction behavior is so complicated that it directly affects the combustion and reaction of composite particle. A method of optimizing the mathematical modeling based on the Distributed Activation Energy Model (DAEM) of the coal pyrolysis has been developed.Based on the Modified Gauss-Hermite Quadrature(MGHQ),the paper discusses the temperature integral under the condition of the typical linear and nonlinear temperature of the DAEM. The optimization greatly reduces the computational time and cost. The model prediction can be incorporated more efficiently in a CFD code and fitted well with the biomass and coal pyrolysis experiment data.Secondly, simulate the pyrolysis process of the composite particle after heat transfer with high temperature of CO from the burning zone in the moving bed furnace. The influence of different particle structure, composition and gas velocity on pyrolysis behavior of composite particle with mass and heat transfer was studied.(1) The reaction time of complete pyrolysis of three pillow, spherical, eggshell shape at 1280K is 115s,180s and 350s respectively. Homogeneous composite particle can promote the pyrolysis reaction. Pillow shape has the best reaction performance.(2) The decomposition of Ca(OH)2 is the step control. The moisture in coal delays the pyrolysis process greatly.(3) As the gas velocity increases,the heat convection effect is relatively obvious, while the extent of the heat convection effect drops off.In the end, simulate the combustion reaction of pyrolysis production of the composite particle at the O2 atmosphere. Radiation effect, structure of particle, inert component and operating temperature were studied for the reaction system.(1) Compared modeling results without consideration of radiation model, verify the radiation has a large effect on the heat transfer so that it can’t be ignored.(2) When the carbon content of composite particle dropped to the demand of preparing for the calcium carbide, the combustion time of pillow, spherical, eggshell shaped particles at 1400K is 155s,476s and 110s, which shows grain structure has a great influence on combustion reaction. The pillow particle has the best combustion performance. The temperature at the carbon-calcium contact surface of the eggshell shaped particle is below the calcium carbide formation temperature at the end of the reaction.(3) At the operating temperature of 1400K, porosity is the main factor of affecting the combustion reaction rate. The coal with low moisture and high porosity is better for the pyrolysis and combustion process of composite particle.(4) At the operating temperature of 1600K and 1400K, the reaction was diffusion controlled. At 1200K, chemical reaction was rate controlling at the beginning, while the O2 inside particle has reacted completely at 20s, changing to the diffusion controlled. So the transition temperature is around 1200K. The operating temperature of 1200K can’t met the demand of the calcium carbide synthesis. Since the reaction rate were similar at 1600K and 1400K, the optimal operating temperature is 1400K. |
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