The HFB gasifier

Pressurized gasification poses new challenges to the process not found in atmospheric gasifiers. With increased pressure, the viscosity of gases changes, they become “less fluid” and affects the movement of particles in the reactor. The two leading principles for fluidized bed gasifiers, Bubbling Fluidized Bed (BFB) and Circulating Fluidized Bed (CFB), are affected differently by pressure.

For BFB gasifiers, the reactor height increases significantly with pressure. The reactor for a standard 10 MWe BTC would be more than 2X as high as our own HFB gasifier. For CFB gasifiers, the reactor diameter becomes so narrow that feeding the fuel becomes very challenging.

To address these main challenges for BFB and CFB technologies, Phoenix BioPower has developed the HFB – Hybrid Fluidized Bed gasifier. It is, as the name indicates, a hybrid between the bubbling and circulating fluidized bed technologies. With the specific design of the gasifier, coupled with dual particle size bed materials, the benefits for both technologies are reached and the challenges for the technologies from higher pressure are addressed.

The combination of the design and dual bed particle size allows some particles (the bigger ones) to stay in the fluidized bed and the smaller particles to travel up through the cyclone to be returned to the bottom of the bed. This allows for a high conversion of the biomass to Syngas. With the design and the high pressure, the size of the reactor and plant is kept much smaller than an equal capacity BFB or CFB at atmospheric pressure.

Another benefit of pressurized gasification is for production of industrial gases. Such gases are typically upgraded or reformed in pressurized systems. By gasifying at pressure, the need for a capital intensive and complicated gas compressor is excluded, reducing both CapEx and OpEx of a plant.