Combustion of Coal in Pressurized Fluidized Bed Reactors
The combustion of coal in fluidized bed boilers represents the state of modern power plant engineering. Due to the migration from atmospheric to pressurized operating conditions, the modelling and the simulation of this reactor type is of on-going interest. Therefore, a two dimensional model is presented which consists of two mass balances for the carbon and the oxygen concentration and an enthalpy balance for the temperature, respectively. The solution of this coupled system of nonlinear PDEs is split up into the two subproblems “solution of the two mass balances” and “solution of the enthalpy balance”. Finally, an appropriate coupling algorithm has to be used to get a solution of the entire system. For the latter an iterative Newton type method has been developed which only requires successive solution steps for the single subproblems. No computation of the Jacobian of the whole system is necessary. Therefore, this method may generally be an interesting tool for the solution of coupled systems in the engineering sciences. The numerical results deal with the combustor model and point at the influence of the fuel feed system on the temperature homogeneity of the reactor. With this intention an enlargement of the above model is presented which takes into account the technical relevant fuel feed in the form of coal water mixtures.
KeywordsHeat Exchanger Tube Fixed Point Iteration Enthalpy Balance Fuel Feed Carbon Mass Balance
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