| The boiler is the main equipment of the thermal power plant,and its energy utilization efficiency affects the efficiency of the entire thermal power plant.The effective analysis and evaluation of the energy efficiency of the boiler system is of great value for guiding operation adjustment and energy-saving transformation.To carry out the energy efficiency analysis and evaluation of the boiler system according to the unit consumption analysis theory,it is necessary to master the boiler heat balance data and related information.However,the actual situation is that the data such as the calorific value of the fuel and the composition of the fuel are missing or incomplete,which makes the calculation impossible or insufficient in accuracy.It is necessary to estimate fuel calorific value based on fuel composition,or to construct a suitable fuel composition based on fuel calorific value and coal type.In addition,there is an inherent logical relationship between the change of boiler thermal efficiency caused by the CO concentration in the flue gas and the carbon content of the ash,and the fuel composition,calorific value,coal consumption,and excess air coefficient,which is very important for accurately grasping the energy efficiency characteristics of the boiler.Whether it is fuel,air or flue gas and ash,they are all mixtures,which cause troubles to the accurate analysis and evaluation of boiler energy efficiency.This paper intends to discuss the above two problems based on the analysis and calculation of the thermophysical properties of the mixture,and propose corresponding detailed solutions.In this paper,the method of error analysis,data fitting and case demonstration is used to analyze and solve the problem of missing fuel calorific value or composition.For the missing calorific value of known fuel components,data collection and elemental calorific value estimation were carried out.The error in the estimated calorific value was analyzed because the decomposition enthalpy of coal organic matter was not considered.The dry ash-free basis was selected as the correction basis for volatile points,and the dry ash-free basis The error of volatile matter and estimated calorific value of elements is fitted to obtain the formula of correction coefficient of volatile matter,and the corrected predicted calorific value with higher accuracy is obtained by using element estimated calorific value and correction coefficient,and the prediction accuracy of the prediction method is verified by the verification team.For the known fuel coal type,calorific value and missing element composition of volatile matter,based on the modified prediction calorific value method,the initial parameters of composition inversion are set up according to the coal type,and the calculation is carried out to ensure that the proportion of relevant components is constant.Calculated according to the fuel calorific value and formula Inversion composition.Solve the starting point of energy efficiency evaluation,that is,the problem of fuel calorific value and composition,so as to carry out subsequent energy efficiency evaluation calculations.In this paper,the method of formula derivation and case demonstration is used to analyze the trend and predict the change of boiler thermal efficiency and heat loss caused by the degree of incomplete combustion of fuel.According to the definition of heat loss,the relationship between the volume fraction of flue gas CO and the carbon content of ash was deduced,and the thermal efficiency and heat loss trend and results caused by variable changes were analyzed from the two aspects of reaction principle and formula.The analysis shows that the CO volume fraction of the flue gas is inversely proportional to the thermal efficiency of the boiler,and is directly proportional to the heat loss of the exhaust gas and the heat loss of chemical incomplete combustion.It has a linear relationship within a certain range and basically has no effect on other losses;the carbon content of the ash and the boiler The thermal efficiency is inversely proportional to the exhaust heat loss,directly proportional to the mechanical incomplete combustion heat loss and the ash physical heat loss,and has a linear relationship within a certain range,and basically has no effect on other heat losses;the relationship coefficient is related to fuel composition,excess air The coefficient,exhaust gas temperature and ash temperature are related,and can be adjusted according to the actual operating parameters of the boiler,which is used to predict the energy efficiency index of variable changes,simplify calculations and save time. |
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