Extension of weighted sum of gray gas data to mathematical simulation of radiative heat transfer in a boiler with gas-soot media.

Samira Gharehkhani,Salim Newaz Kazi,Ali Nouri-Borujerdi,Hooman Yarmand

doi:10.1155/2014/504601

Samira Gharehkhani, Salim Newaz Kazi + Show 2 more

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https://doi.org/10.1155/2014/504601

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Abstract

In this study an expression for soot absorption coefficient is introduced to extend the weighted-sum-of-gray gases data to the furnace medium containing gas-soot mixture in a utility boiler 150 MWe. Heat transfer and temperature distribution of walls and within the furnace space are predicted by zone method technique. Analyses have been done considering both cases of presence and absence of soot particles at 100% load. To validate the proposed soot absorption coefficient, the expression is coupled with the Taylor and Foster's data as well as Truelove's data for CO2-H2O mixture and the total emissivities are calculated and compared with the Truelove's parameters for 3-term and 4-term gray gases plus two soot absorption coefficients. In addition, some experiments were conducted at 100% and 75% loads to measure furnace exit gas temperature as well as the rate of steam production. The predicted results show good agreement with the measured data at the power plant site.

Highlights

One of the most important modes of heat transfer in a boiler furnace of a large power plant is radiation
The soot absorption coefficient suggested in (6) can be coupled with available models for nonluminous flam with gray gases and one clear gas to obtain the total emissivities of gas-soot mixture and to be applied in the zone method
The evaluated total emissivities at the different temperatures with soot concentration of 0.0001 Kg/m3 for gas combustion are well compared against benchmark data which are “three-gray gas plus two-soot” and “four-gray gas plus two-soot” models suggested by Truelove (Figure 3)

Summary

Introduction

One of the most important modes of heat transfer in a boiler furnace of a large power plant is radiation. Different models for calculation of the radiative properties of real gases have been proposed by researchers such as statistical narrow band (SNB), the full-spectrum correlated-k (FSCK) distribution, and the weighted-sum-of-gray gases (WSGG) [2,3,4,5,6]. Among these models, the last one is more reasonable in engineering calculations in view of the accuracy and computing time. Larsen and Howell [22] presented a method for calculations related to the

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