Compensation of efficiency loss in pulverized coal boiler co-firing biomass derived low calorific gases

The paper presents an analysis of the possibility of compensating the loss of efficiency for pulverized coal-fired boiler co-firing large thermal shares of low-calorific gas from gasification of biomass. Such co-firing always leads to a substantial loss of efficiency. In the case of pulverized coal boiler with a capacity of 230 t/h, co-firing of low-calorific gas (2000 kJ/m ³ _n) at 40% of the boiler load, caused a decrease in efficiency of over 10% compared to coal-fired boiler. The study indicated the possibility of compensating the loss of efficiency through the modernization of the economizer and implementation of the developed heating surfaces, such as longitudinally finned and transverse finned tube banks. The analyzed modernization leads to permanent gain of efficiency by about 5%. In addition, an impact of a simple operating changes, such as reduction of tempering air flow before milling unit, to compensate for the loss of boiler efficiency is also described. Such control of tempering air may lead to the gain of efficiency at the level of 0.5%.