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Small Laboratory-Scale Fixed-Bed Gasifier Reactor

Small Laboratory-Scale Fixed-Bed Gasifier Reactor
The laboratory scale FBG simulates the range of operating conditions from self-sustained gasification to fully heat-assisted gasification. It has been designed primarily for a biomass feedstock. Gas sampling and analysis are conducted online.

Operating Conditions

  • Nominal feed rate: 5 lb/hr (2.27 kg/hr)
  • Syngas production: 4 scfm
  • System pressure: atmospheric or slight vacuum
  • Gasifier nominal temperature: 1000°F (540°C)
  • Warm-gas cleanup capability: full stream

Process

The biomass feedstock (typically wood chips) enters a packed-bed gasifier at the top of the reactor. Ash and char are extracted through an auger at the bottom of the reactor and transported to a smaller extraction hopper. For reactor start-up and to simulate heat assist of the gasification zone, a natural gas combustor is used. The combustor effluent convectively heats the gasification zone of the reactor and is exhausted to the atmosphere. Primary air is injected through the top of the reactor for the gasification reactions. Nitrogen purge is introduced to the reactor through the top of the gasification reactor and feed hopper. The output of the gasification reactor passes through two particulate cyclone filters in series. At this point, the bulk of the gas passes through a series of cold-water condensers before being injected into the hot zone of the combustor. The gas flow rate is measured between the condensers and the combustor.

A slipstream of producer gas is isokinetically extracted from the bulk producer gas between the cyclone train and the cold-water condenser train. The producer gas sample immediately passes through a hot ceramic filter maintained at 840°F (450°C) to quantify the particulate levels. The producer gas sample is then cooled by a cold-water condenser and passed through a series of anisole impingers for tar quantification. After the tars are extracted, the producer gas sample is passed through a calcium chloride bed to remove moisture before passing it through a gas analyzer. The gas analyzer determines the percentage of H2, CO, CO2, CH4, and O2 in the dry gas sample. Nitrogen levels in the dry gas sample are calculated by difference.