Method for simulating fluidized bed with dynamic changes of grain density and particle size

Abstract

The invention discloses a method for simulating a fluidized bed with dynamic changes of grain density and particle size. The method comprises the following steps: 1, establishing a basic flow reaction model in the fluidized bed; 2, establishing a mathematical model for describing a change rule of the grain phase density and particle size; 3, establishing a particle type sectioned drag model; and 4, predicting flow reaction characteristics in the fluidized bed. According to the method disclosed by the invention, the fluidized bed with dynamic changes of grain density and particle size is subjected to simulation study by adopting a computational fluid mechanics method, the mathematical model for describing a change rule of the grain phase density and particle size is combined to perform real-time correction on the density and particle size of the particles, and the acting force between gas-particle phases in a coexisting system of multiple particle types through the particle type sectioned drag model, so that the flow reaction characteristics in the fluidized bed with the dynamic changes of grain density and particle size are accurately predicted. According to the method, lots of complicated and expensive experiment researches are not needed, and lots of manpower and material resources and time cost can be saved.

Description

technical field [0001] The invention relates to the field of fluid mechanics, in particular to a simulation method for predicting dynamic changes in particle density and particle size of a fluidized bed based on computational fluid dynamics. Background technique [0002] The solid particles in the fluidized bed have some apparent characteristics of the fluid under the action of the fluid, and the surface of the particles is all exposed to the surrounding violently turbulent fluid, thereby enhancing heat transfer, mass transfer and chemical reactions, so it is widely used in industry Fields such as pyrolysis, combustion or gasification of solid fuels such as biomass and coal. The density and particle size of biomass or coal particles in the fluidized bed often change dynamically with the progress of heterogeneous chemical reactions such as pyrolysis, combustion or gasification, showing a certain density and particle size change law, which affects the Flow reaction characteri...

AI Technical Summary

Problems solved by technology

For different types of particles, there are large differences in the calculation methods of the gas-particle interphase force (drag force)

However, the current simulation work has not taken into account possible changes in particle types. For a specified fluidized bed reactor, only a single type of particle drag force model is used, and it is difficult to accurately describe the gas-particle interphase force in a system where multiple particle types coexist.

[0006] Therefore, the existing simulation methods are difficult to accurately predict the flow reaction characteristics in a fluidized bed with dynamic changes in particle density and particle size, and cannot provide a theoretical basis for the precise regulation, optimal design, and process scale-up of such reactors.

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