Flow regime distinguish in a circulating fluidized bed gasifier based on wavelet modulus maxima

Abstract

Pressure fluctuation is often used to analyze the dynamic changes of the gas-solid fluidized beds. In this paper, cold tests were carried out to study the gasification system of circulating fluidized beds gasifier, to find out the change law of the solid circulation rate Gs and the holdup by altering such parameters as air velocity, particle size and integrated particle, and recognize the flow regime in the boiler through analysis of the differential pressure fluctuation signals with wavelet transform modulus maximum method. Results indicate that Gs increases with the increase of the superficial gas velocity. When the superficial gas velocity is higher than 2m/s, the three kinds of particles with higher distribution concentration of particle size exhibit characteristics of fast fluidization at the bottom of the riser, and the number of modulus maxima lines is almost the same as that in the top area. Change the distribution range of particle sizes of bed materials, and the larger particles in the riser after particle separation exhibit characteristics of both the turbulence region at the bottom and the fast region on the top, prolonging their residence time in the bed. There are more modulus maxima lines for the differential pressure fluctuation signals at the bottom than on the top. The regime recognition method based on modulus maximum and its experimental results will help us learn more about the design, enlargement and operation of circulating fluidized beds.