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Show Gases t air F~9. 2 Gases ~a o f air Flame Source ~a 3 J IDf 3 Flan~ Source ~a 4 J mf 4 ~ J ~ 2 2 by the combustion model of Khalil,(1,6). The model solves transport equations for the mass fraction of the fuel M ,while the sink term in the equation i~Ugiven as; Sf u =-p- A Mf u Mo x exp(-E/RT) [l+F] ...... (4) where A is thepreexponential factor=lOlO, and E is the activation energy with E/R =18400. The factor F represents the effects of turbulence on combustion and is a function of the species fluctuations correlations,temperature fluctuations and temperature-species fluctuations correlations. The value of F can be as large as 30,ref.7 which indicated the strong influence of turbulence on combustion rates. The assessment of the model validity was reported earlier,(1,2,6 &7) for complex flames in furnaces. Heat transfer characteristics can be well represented by an eddy diffusivity model where the heat flux is given by the product of an exchange coefficient and an enthalpy gradient,ref.l. SOLUTION PROCEDURE- The above-mentioned eq.l is expressed in the finite difference form and is solved by an iterative procedure that is based on guess and correct approach. The SIMPLE, Semi Implicit Line by line method is adapted here. The finite difference counterpart of eq.l is solved at discritized locations in the flow field. A non-uniform orthogonal grid line arrangement is superimposed on the half-section of the furnace as shown in figure 2. Figures 3 and 4 indicated the distributed resistance due to solids in the furnace and the boundary conditions respectively. EXPERIMENTAL INVESTIGATION This section describes the experimental facilities together with the various instrumentation which were used to measure the gas temperature, flame and heat transfer characteristics. The present set of measurements, include those of local gas concentrations, and temperature as well as the wall temperature for the vertical lime kiln number 4 at the Egyptian Iron and Steel Complex at Helwan. EXPERIMENTAL FACILITY - The general layout of the present vertical lime kiln is shown in figure 1. The experimental data were obtained during the normal operation of the furnace and were repeated to verify the reproducibility of the results. The furnace diameter is 4.99m and about 30 m long,it was fired by two sets |