Online simplified model and experimental comparison of CFB boiler thermal efficiency

Abstract

In recent years, circulating fluidized bed boiler (CFB) combustion technology, which is used as a purification technology in coal combustion, has been widely studied. Some studies have conducted simplified investigations into calculating the standard boiler thermal efficiency. However, these studies are mainly aimed at simplified calculations of the boiler’s heat balance and data correction, and an online prediction model based on the core influential parameters have not been developed.To solve this problem, this study first calculates the boiler heat balance and thermal efficiency calculation to analyze thermal efficiency calculation factors. The exhaust heat loss q2 and the incomplete combustion heat loss of gas q3 decrease as the slag carbon content increases. For every 1% increase in the slag carbon content, the thermal efficiency is reduced by 1.95%; for every 5 °C increase in the exhaust gas temperature, the thermal efficiency is reduced by 0.26%.Then a simplified boiler thermal efficiency model, based on the slag carbon content and exhaust gas temperature determined to be the core parameters, is derived and compared with the measured results. The functional relationship is derived as follows: η=98.012–0.053tpy-1.944Clz (tpy < 200 °C, Clz < 2%).