In a fixed-bed gasifier, the gasification reaction is carried out in a relatively stationary material bed, that is, the material is in a stationary state relative to the air flow, so it is called a fixed bed. The structural features of a fixed-bed reactor are a furnace chamber that houses the raw material and a grate that supports the reactor layer. Fixed-bed vaporizer is a traditional gasification equipment, which has many applications due to its simple and compact structure, simple design and manufacturing, easy operation, and high thermal efficiency. According to the direction of the air flow movement in the fixed-bed gasifier, the fixed-bed vaporizer can be divided into three types: down-suction vaporizer, up-suction vaporizer and flat-suction vaporizer, as well as the variants of these three types and their combination with each other to form a composite gasification reactor.
Fluidized bed combustion technology is an advanced combustion technology. The temperature of the fluidized bed gasifier is generally 750~800°C. This kind of gasifier is suitable for gasification of biomass materials with large moisture content, low calorific value and difficult ignition, but the raw materials require a fairly small particle size, and can use biomass energy on a large scale and efficiently. According to the different gas-solid flow characteristics, fluidized bed gasifiers are divided into bubbling bed gasifiers, circulating fluidized bed gasifiers, double fluidized bed gasifiers and carry bed gasifiers.