Algebraic, multi-zoned radiation model for a two-zoned zero-dimensional cylindrical furnace

Abstract

A simple two-zone zero-dimensional combustion model which estimates the influence of impurities in the fuel on the radiative energy transport has previously been developed based on an overall energy balance coupled with a multi-zoned radiation model. This paper presents the equations of the model, illustrates the method of calculating the radiative exchange areas for the two-zone system, and presents predictions for pulverized-coal and fluidized-bed combustion. The model predicts thermal performance as a function of coal input and furnace operational parameters, steam mass flow rates, and superheated steam temperatures leading to the high pressure turbine. Two wall ash deposit parameters, thermal conductivity and maximum deposit thickness, have been determined by a sensitivity analysis to be critical to furnace performance. These parameters have been obtained experimentally by others. The predictions from the two-zone model have been compared with predictions from an earlier single-zone model. The general trends from both models were the same, although the two-zone model predictions were closer to expected values.