Research And Application Of Exergy Efficiency Measurement Method For Industrial Boilers

Industrial boiler is a kind of energy transition equipment.The energy consumption of industrial boiler is in the second place in China,just behind power station boiler.Scientific and reliable energy efficiency measurement is one of the prerequisite works to realize energy high-efficiency utilization of industrial boilers.In China,TSG G0003-2010,GB/T 10180-2003 and TSG G0002-201 are current measurement methods,which are all based on thermal equilibrium analysis methods.The methods above just consider the conservation of energy in quantities ignoring the difference of energy quality.Thermal efficiency can’t precipitate the energy conversation process comprehensively and some effective improvement measures can’t be carried out consequently.The present criteria and principle measurement methods were analyzed and the shortages were found in this paper.Exergy measurement methods of industrial boiler were constructed.Provincial standard(DB21/T2567-2016)was formulated based on this method.The improvement methods and direction were put forward from the exergy efficiency view.The main conclusions and innovation points are as follow.(1)As the supplement of exergy measurement methods for industrial boilers,the core of exergy measurement methods is introduction of exergy concept,which considering the matching of quantity and quality in energy conversion process.The key point of exergy measurement method is the definition and calculation of exergy efficiency and calculation.In this paper,exergy efficiency is based on anti-equilibrium measurement methods.Exergy efficiency(η)is defined as the following equation,where ei is exergy loss percentage.#12(2)Variation trendency of boiler exergy efficiency is the same as thermal efficiency.However,the exergy efficiency is only a third to quarter as thermal efficiency.Therefore,energy saving potential of high thermal efficiency boiler should be sought from the view of exergy efficiency.Energy saving potential of low thermal efficiency boiler should be sought from the view of exergy and thermal efficiency simultaneously.Exergy efficiency and thermal efficiency make up a more scientific evaluation system of industry boiler together.(3)The main factors that affect the efficiency of the boiler are the irreversible exergy loss of combustion and heat transfer.These 2 kinds of exergy losses accounted for 88%to 92%of the total exergy loss for the fuel or gas boiler and accounted for 81%to 85%for coal or burning biomass boiler.Thus,reducing the irreversible loss of combustion and irreversible loss of heat transfer is an effective way to improve the exergy efficiency of the boiler.This method change the single idea of improving the efficiency of the boiler blindly reducing the irreversible loss of discharge smoke.(4)Controlling an appropriate excess air coefficient,reasonable wind distribution and reducing air leakage to improve the furnace temperature are the main ways to reduce the irreversible exergy loss of combustion.Improving the working parameters and controlling load fluctuations and avoid low load operation are the ways to reduce irreversible exergy loss of heat transfer.