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Bench-Scale Hot-Gas Filter Vessel

Bench-Scale Hot-Gas Filter Vessel
The bench-scale hot-gas filter vessel (HGFV) was designed to test hot-gas candle filters for their ability to obtain high-temperature, high-pressure operational data on various filter elements. The HGFV can handle all gas flow from the continuous fluid-bed reactor at its nominal design conditions.

Operating Conditions

  • Syngas production: 30 scfm
  • System pressure: 150 psig
  • Nominal temperature: 1550°F (840°C)


  • 10-in. diameter
  • 60 in. long (including cone, vessel, and cap)

Vessel Design

The tube sheet is interchangeable for different-sized filters. The filters are sealed in the tube sheet by a bolted metal plate and Nextel fiber gaskets that counteract the upward force imparted across the candle filter by the filter’s differential pressure. The vessel is sized such that it can house three candle filters up to 18 in. long, with a 2.375-in. outside diameter. This provides candle space of 3.85-in. centerline to centerline and enables filter face velocities as low as 2.5 ft/min to be tested in the CFBR. Higher face velocities can be achieved by using shorter candles or higher gas flow rates. Ports were added in the filter vessel to allow temperature and pressure measurements. The ash letdown station consists of two high-temperature valves, which act as lock hoppers to isolate the ash hopper from the filter vessel.

Nitrogen Backpulse System

The nitrogen backpulse system is designed to supply a minimum of three candle volumes per pulse for the longest candle filters and even higher volumes for the shorter candle filters. It is constructed from existing materials utilized from a previous hot-gas filter test system. The nitrogen is capable of being heated up to 1550°F (840°C) before entering the filter vessel, although most tests utilize room-temperature nitrogen for backpulsing. The volume of nitrogen displaced into the vessel and pulse duration are controlled by the regulated pressure (up to 600 psig) of the cold-nitrogen reservoir and the solenoid valves used to control the timing of the cold-gas pulse (displacing hot nitrogen into the filter vessel), respectively. An electrically heated ½-in. pipe is used to connect the CFBR to the HGFV.