Integrated mathematical modelling of a 105 t/h biomass fired industrial watertube boiler system with varying fuel moisture content

Abstract

In this paper, a steady-state 1D computer model of a complete sugarcane bagasse-fired boiler system is presented, which pays special attention to the different heat transfer phenomena encountered in the boiler heat exchangers. The model solves the mass, momentum and energy balance equations for water, flue gas and air streams in an integrated manner which utilizes fundamental equations and empirical correlations for pressure drop, radiative heat transfer and convection. The integrated model is successfully applied to model a 105 t/h industrial watertube boiler at three different load cases namely 100 t/h, 65 t/h and 35 t/h. The model results are validated using typical plant measurements. The mean relative predicted gas temperature errors are 1.47%, 0.58% and 4.84% respectively for the different load cases simulated, and for the water circuit temperature predictions the mean errors are 1.48%, 0.85% and 5.31% respectively. Additionally, a sensitivity analysis is performed on the integrated model, which investigates the influence of selected modelling parameters such as flame height on key boiler output variables such as the furnace exit gas temperature.