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Over the past four decades, fluidization technology has been widely applied in industrial processes. The traditional fields of application for fluidized beds are the chemical industry and the petroleum industry. However, in recent years, their scope of use has expanded to coal combustion and conversion, metal extraction and processing, environmental treatment and the energy industry, as well as various other fields that require solid handling. A preliminary analysis of the aforementioned application areas shows that a major field for the use of fluidization technology is chemical reaction engineering, which is why terms such as \"fluidized reaction engineering\" or \"fluidized bed reactor\" came into use. The fluidized reaction of gases can be conveniently divided into gas-phase reactions and gas-solid reactions. The former can be further divided into catalytic reactions and non-catalytic reactions. In terms of gas-phase reactions, fluidized catalytic reactors are used for petroleum cracking, hydrogenation reactions, acrylonitrile production, the oxychlorination of olefins, the oxidative dehydrogenation of butenes, ethylene oxide production, vinyl acetate production, the ammonia oxidation of toluene and xylene, as well as the production of high-density and low-density polyethylene. Examples of uncatalyzed gas-phase fluidized reactions include thermal cracking and the combustion of fuel gases. Examples of gas-solid fluidized bed reactors include the production of dimethyldichlorosilane, coal combustion, coal carbonization, coal gasification, incineration of solid waste, uranium processing, roasting of sulfide ores, reduction of iron ores, and wastewater treatment. The increasing widespread use of fluidized bed reactors demonstrates their following advantages: (1) The fluidized state of the material in the bed facilitates continuous flow and cyclic operation ； (2) The rapid circulation of solid particles within the bed and the agitation caused by bubbles result in good heat transfer between gas and solids, as well as isothermal conditions within the bed and its internal components. Generally, fluidized bed reactors require a smaller heat transfer area ； (3) The structure of the fluidized bed is relatively simple and compact, hence it is suitable for large-scale operations ； (4) The mass transfer rate between gas and solid is high. The advantages listed above demonstrate the potential of using fluidization technology. However, what causes advantages can sometimes also be the source of disadvantages. Practice has shown that fluidized bed reactors have the following limitations: (1) Under continuous flow conditions, the rapid circulation of solid particles and the agitation caused by bubbles result in an unfavorable residence time distribution for these solid particles ； (2) Some of the gas passes through the bed in the form of bubbles, severely reducing the gas-solid contact efficiency and resulting in an improper product distribution ； (3) Near the bottom of the bed layer, there is usually a significant temperature gradient. This phenomenon undoubtedly exacerbates the inappropriate conversion rate distribution and product distribution within the bed, and sometimes even leads to sintering of the distribution plate ； (4) Compared with other types of gas-solid contact equipment, fluidized bed reactors suffer from particle loss and wear due to the circulation of large amounts of solids and the movement of solids within the bed ； (5) Scaling up from the laboratory to industrial scale is quite difficult, as the fluidization types of fluidized beds at different scales belong to distinct fluidization systems.