The Effect Of Coal Combustion On High Temperature Corrosion Factors Of 660MW "W" Flame Boiler

Since the beginning of 2021,the ex-factory price of thermal coal has been showing a rapid upward trend,and the price of high-quality coal such as anthracite has remained high.For "W" flame boilers designed with anthracite coal,in order to reduce the cost of coal combustion,a certain proportion of low-priced inferior coal,such as bituminous coal or lignite,is generally selected.Although mixing inferior coal can reduce the cost of coal combustion,its disadvantages are also very obvious.The fixed carbon content of inferior coal is low.In order to ensure the rated calorific value of the boiler,it is necessary to increase the amount of coal burning of inferior coal,which may increase the high temperature corrosion in the furnace.This paper takes a 660 MW "W" flame coal-fired boiler as the research object,and uses the method of numerical simulation to study the effect of changing the coal blending method on the high temperature corrosion factors.For sulfide type high temperature corrosion,the influencing factors mainly include: temperature,carbon monoxide concentration and hydrogen sulfide concentration;for sulfate type high temperature corrosion,the influencing factors mainly include: temperature,sulfur dioxide concentration and carbon monoxide concentration.In the process of numerical simulation,based on the turbine heat acceptance,3 representative boiler load conditions were set up.Finally,the distribution cloud map of the influencing factors of high temperature corrosion at different heating surfaces is obtained.After a comprehensive comparison,the trend of high temperature corrosion was judged,and the best choice among the studied coal-burning methods was obtained,which provided a reference for the actual operation of the boiler in the future.Finally,by analyzing the research results of controlling high temperature corrosion in coal-fired boilers at home and abroad in recent years,the author analyzes the special combustion mode and air distribution structure of "W" flame boilers,and summarizes three measures to prevent corrosion.Among them,the measures involving equipment transformation are: arranging the wall-mounted air in the combustion chamber of the furnace,and the measures involving operation adjustment are adjusting the pulverized coal distribution ratio of the main pulverized coal nozzle and the spent gas nozzle of the burner,and reducing the air volume distribution of the burnout air nozzle.Compare.Under different boiler loads,two working conditions with severe high-temperature corrosion were selected,and the corresponding simulated boundary conditions were changed,and the distribution cloud map of the high-temperature corrosion influencing factors at the same position was obtained again.By comparing the changes of high temperature corrosion before and after reconstruction,the preventive effect of these measures was evaluated.