The Numerical Simulation On The Gas-solid Flow In The Circulating Fluidized Bed Boiler Through The Method Of Secondary Air Correction

Because of the adaptability of fuel, the simple pretreatment of fuel, low pollutant emissions, flexible operability, etc., circulating fluidized bed combustion boiler was widely promoted at home and abroad. The circulating fluidized bed boiler in a power plant is a typical dense gas-solid flow system. The character of its gas-solid flow affects its heat and mass transfer, combustion characteristics.The mechanism of Circulating fluidized bed combustion technology is rather complex. Engineering experience methods are largely dependent on limited data of lots of tests. With the development of computer technology and numerical computing technology, numerical simulation became a new method to compensate for the lack of traditional experimental research methods. The results show that the area of dense phase and dilute phase particle distribution are reasonable. We can find that the particles of central region move upward and the particles of the side wall area move downward. This phenomenon is also in line with the downward movement of the fluidized bed boiler ring-central flow state.In this paper, a new method to correct the secondary air velocity was used to simulate the real three-dimensional numerical gas-solid flow HG-1025/17.5-L.HM37type circulating fluidized bed boiler.Through the circulating fluidized bed boiler furnace gas-solid flow simulation of the particle distribution of the ideal area of dense phase and dilute phase region particle distribution,while the central region of the upward movement of the side wall area is also in line with the downward movement of the fluidized bed boiler flow state. Therefore, by choosing different particle size and operating gas velocity, discussed the impact of changes in a single parameter of the gas-solid flow field. The particles move upward at the center area, and move downward at the area near the wall. This character of movement is also in line with the flow state of the classic CFB boiler. Simulation results show that the method of secondary air velocity correction is correct, and it will provide a theoretical basis to guide the design and operation of similar large circulating fluidized bed unit.