Volume IV, Issue XI, November 2015 IJLTEMAS ISSN 2278 - 2540 www.ijltemas.in Page 66 Prediction of Flue Gas Composition in Coal Combustor: CFD Approach Deeksha Gupta * , Dr. S Prasad ** *PG Scholar, Madhav Institute of Technology & Science, Gwalior (MP) **Associate Professor, Department of Chemical Engineering, M.I.T.S. Gwalior (MP) Abstract:The present work is based on the software ANSYS FLUENT Workbench 15.0. This approach aims to provide an improved prediction of flue gases composition from combustion of pulverized coal when the coal was injected pneumatically. The mathematical models used for the combustion of pulverized coal includes realizable K-ɛ model for turbulent flow, species transport model and discrete phase model. For the purpose of simulating the combustion process, 2D mesh was adapted. The composition of O 2 and CO 2 is good agreement with literature. Key Words :CFD, pulverized coal, speciestransport model I. INTRODUCTION eliable, efficient and clean energy supply is one of the basic needs of humankind. Today our energy supply system is under-going a long term transition from its conventional form to a more sustainable and low carbon style, especially addressing greenhouse gas (H 2 O, CO 2 , CH 4 , Nitrogen oxide, CFC & aerosol) emissions into the atmosphere. Pulverized coal is an important fuel for electricity production and will continue to be important for decades. [1] Pulverized coal combustion is a very complicated physical and chemical process, which is related to gaseous turbulent two-phase flow involving solid particles, homogenous gaseous reactions, heterogeneous surface reactions, radiation heat-transfer, etc. [2]Combustion chamber designers endeavor to achieve optimum operating conditions that give maximum combustion efficiency together with minimum pollutant formation rate. [1] The application of CFD technology and other advanced mathematical methods offer opportunities for analysis, optimization and options examination in order to increase the overall efficiency of the energy facilities. This method, in which the governing equation of the combustion field are developed using a computer is capable to provide the detailed information on the distributions of temperature and chemical species and the behavior of pulverized coal particles over entire combustion field that cannot be obtained by experiments. In addition, it facilitates the repeated review in arbitrary conditions for the properties of pulverized coal and the flow field at a relatively low cost. It is therefore strongly expected that the CFD becomes a tool for the development and design of combustion furnaces and burners. II. MECHANISM OF COMBUSTION OF PULVERIZED COAL The ignition temperatures of the naturally occurring solid fuels, namely, wood, peat, lignite, coal, etc. are appreciable higher than the initial temperature of active decomposition. These fuels also contain appreciable quantities of moisture. Therefore, they undergo drying and decomposition before actual combustion takes place. The volatile matter, thus evolved, contains combustible gases, vapors, and also minute droplets of tarry substances. The combustion of these solid fuels consequently involves the combustion of the volatile matter and the combustion of the solid carbonaceous residue. The composition of the volatile matter and hence its burning process, varies widely. The residue is essentially carbon. However, its reactivity depends on the type of fuel and hence its ignition characteristics also vary. The flame of a solid fuel is due to the combustion of the volatile matter and the carbon monoxide produced during the combustion of carbon. The visible indication of the combustion of carbon is a bright glow of the burning piece. Carbon furnishes a typical case of heterogeneous combustion, i.e. combustion between two different phases. The fuel is in the solid state and the oxidant in the gaseous state. This heterogeneous process has two basic components: (i) delivery of the gaseous reactant to the surface of the solid by diffusion and (ii) chemical reaction of the solid and gas at the surface. The combustion of pulverized fuel is simulated by the combustion of carbon particles; the overall kinetics of a single particle is given by 1  ݐ = 1  0 ݌ ݋ + 1  2 ݌ ݋ ( ) Where,  0 =   This bears out the enormous effect of size reduction in accelerating the process. [4] R