Gasifier Classifications
Biomass gasifiers can be classified into two main types based on their design and operation:
- Fixed Bed Gasifiers:
- In these gasifiers, biomass fuels move either counter currently or concurrently to the flow of the gasification medium (steam, air, or oxygen). They are relatively simple to operate and have reduced erosion.
The fixed bed gasifiers can be further classified into three types based on the direction of air or oxygen flow:
- Downdraft Gasifiers: Air is introduced from the top and passes down through the biomass. The combustible gases are drawn out from the bottom. This type is commonly used for stationary applications.
- Updraft Gasifiers: Air enters from the bottom, and the combustible gases are collected from the top. This design promotes better heat exchange.
- Cross-Draft Gasifiers: Air flows horizontally across the biomass. These are simple and suitable for small outputs.
2. Fluidized Bed Gasifiers:
- These gasifiers use an inert material (such as sand, ash, or char) to create a fluidized bed that acts as a heat transfer medium.
- This design allows for better mixing and heat transfer, leading to improved gasification efficiency.
