Thermodynamic Calculation Of Power Plant Boiler Based On Blended Coal Combustion

In recent years,some new types of low-pollution power generation such as wind power,solar power have been fully developed in China,but the accumulated installed capacity of these mode is so small that thermal power is still major power generation for a long time.With the increasing installed capacity of thermal power units in domestic,the demand of thermal power enter coal is also increasing.However,due to high-quality coal resources are limited,the price is high,in order to reduce the cost of power generation.Many thermal power companies focus on lignite,peat and other low-quality coal whose price is reasonable.It is prohibited to burn lignite,peat and other low-quality coal singly for the safety of boiler in operation,so a way of bring with mixing high-quality coal and low-quality coal together is adopted.It is essential to study effect of blending on the power plant system to ensure the stability and safety in operation.In this paper,the boiler heat calculation model is studied.Firstly,according to the major heat exchanging ways,three types of heat exchangers were proposed,namely furnace heat exchanger(total radiation type),semi-radiation heat exchanger and convection heat exchanger,and studied in detail.The thermodynamic calculation process is based on the Soviet Union 73 standard,and the model was improved to achieve a higher calculation speed and accuracy.Secondly,according to the flue gas flow process,whole radiation,semi-radiation,convection heat exchanger were proposed and simplified,then taking the respective part as heat transfer area individually.A ‘for' statement was used to model them respectively.Thirdly,the model of the heat transfer zone is calculated,whose iterative time is too long and the accuracy is less than expected in the trial process.Therefore,it is necessary to improve the algorithm of the heat transfer area.As the Matlab software,used in this paper,has obvious advantages in matrix operation,the algorithm is optimized by this method.The simulation results showed that the method can greatly improve the calculation speed and the accuracy of the module.Then,modeled system with the optimized heat transfer module above and optimized the outer layer iteration of the heat transfer module by dichotomy.In order to facilitate the input of coal parameters,coal specific information to mat data files was directly loaded,and the mass fraction was directly input through the GUI interface.Finally,to verify the universality of the proposed model,the simulation analysis of the flue gas distribution coefficient of the furnace,the leakage of the furnace,the leakage of the flue and the flue of the tail shaft are carried out.The results are in good agreement with the actual operating experience.Then,two cases that bituminous coal mutual mixing and bituminous coal and lignite mixing were simulated and analyzed to obtain the performance of flue gas side.