Auxiliary Systems for Large Testing Equipment
Solids Feed SystemThe larger gasification systems share a common coal feed system. Solids enter the system in a nonpressurized hopper with a capacity of 2500 lb. The coal is gravity-fed into two pressurized coal lock hoppers, which have a capacity of 1700 lb. A set of valves isolates the pressurized lock hoppers from an auger at the bottom of the pressurized feed hopper that meters the solids. The rotational speed of the auger is controlled to produce various feed rates. The feed auger drops the solids into a high-velocity gas stream of ambient-temperature nitrogen or air. The flow of nitrogen entrains the material into either the carbonizer or transport reactor development unit, depending on which unit is in operation. The solids can also be fast-augured into the carbonizer through a water-cooled nozzle rather than by pneumatic transport if desired.
Gas Quench and Liquid SeparationGas quench and liquid separation systems are also shared by the larger systems. Gas passes through the sieve tower and then the two water scrubbers. The gas stream enters the bottom of the sieve tower, where it passes through a series of perforated plates. The plates in the sieve tower are connected for easy removal for inspection and maintenance. In the sieve tower, recycled fluid from the bottom of the tower is cooled and used to quench the incoming gas. Heat exchangers are used to cool the recycle streams in the sieve tower, with the sieve tower outlet temperature at approximately 212°F (100°C). The water condensate product is placed in 55-gal barrels for storage and/or analysis. Next is a series of two direct-contact water scrubbers (venturi scrubbers/cyclones) that are used when the gas stream contains minimal amounts of vaporized organic liquids. The gas stream is cooled to between 86°F (30°C) and 105°F (40°C) in the first water scrubber and to below 70°F (20°C) in the second scrubber. Heat is removed from the recirculating water/oil-cooling fluid by a bank of water-cooled tube-and-shell heat exchangers. The gas from the second venturi is depressurized and flared, and the liquid products are stored in 55-gal barrels.
Thermal Oxidizer/FlareBoth the carbonizer and the transport reactor development unit have access to a thermal oxidizer/flare. Product gas can be vented to the thermal oxidizer before passing through the quench system, or it can be vented to an activated carbon bed for removing any trace contaminants from the product gas before the flare. The thermal oxidizer or the flare operates at temperatures up to 1800°F (982°C) to combust the syngas before it is vented to the atmosphere.
Useful LinksTransport Reactor Development Unit