NETL is developing a technology base for tomorrow's highly efficient, near-zero-emissions power plants including FutureGen. One of the promising technologies NETL is pursuing is advanced fluidized-bed combustion (FBC). Pressurized FBC (PFBC) systems use a mixture of burning coal, a sorbent such as limestone or dolomite, and jets of air to produce a high-pressure gas stream at temperatures that can drive a gas turbine. Steam generated from the heat in the fluidized bed may be sent to a steam turbine, creating a highly efficient combined-cycle system. Removing and recovering particulates and contaminants from the gas and steam are accomplished in treatment vessels once combustion has occurred. PFBC may also play a role in hydrogen fuel production.

NETL's integrated Fluid-Bed Gasifier/Modular Gas Cleanup Rig is helping to demonstrate advanced features of FBC. Researchers are developing the technology base needed to lower capital and production costs to levels that are commercially feasible, leading to systems with near-zero emissions, including capture and subsequent storage of CO 2 in suitable geological formations. In the Fluid-Bed Gasifier/Modular Gas Cleanup Rig, a fluidized-bed gasifier provides fuel gas for testing and developing high-temperature, high-pressure components and processes in a gasification and combustion (reducing and oxidizing) environment. Operated mainly as a gasifier, the reactor vessel produces coal gas that is tested downstream. The raw coal gas is sampled for major and trace elements, and is sent to a filter vessel where particulates are removed.

After particulates are removed, the gas can be transported to any of five sampling or reaction vessels for fluid-bed desulfurization; transport desulfurization; chloride, alkali, or other contaminant removal; or recovery processes. The fluid-bed desulfurizer is used for sorbent regeneration or other oxidation reaction. Isokinetic sampling of hazardous air pollutants (HAPS) is provided upstream and downstream of particulate removal.

NETL has the following equipment and diagnostic resources to support these efforts.

Fluidized-Bed Gasifier

• Diameter: 0.25-m
  (10-inch)
• Capacity: 907 kg
  (1 ton) coal/day
• Produces up to 227 kg/hr
  (300 lb/hr) of coal gas at 1,200 K (1,700°F) and
  30 atmospheres (425 psig)
  of pressure

Filter Vessel

• Operates at 894 K (1,150°F)
• Operates at 20 atmospheres (300 psig) of pressure

Treatment Vessels

• Fluid-bed desulfurization
• Transport desulfurization
• Chloride removal or recovery
• Alkali removal or recovery
• Removal of other contaminants

Related Diagnostics and Instrumentation

• Sampling systems
• Test modules

For more information contact: T. Robert McLendon