A solids stream is withdrawn from the standpipe via a cooling auger system to provide a means of removing accumulated ash and spent sorbents. The rate at which solids are removed from the system is determined by the level of solids inventory in the standpipe. The TRDU is fully instrumented with an array of internal thermocouples, pressure and differential pressure transmitters, and gas flowmeters. All measured process variables are controlled and recorded by a personal computer-based process control and data acquisition system. Area 500 - Gas Quench and Liquid Separation Area 500 contains the carbonizer and TRDU condensation trains.
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, recycle 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. The Dowtherm on the shell side of this heat exchanger can be heated electrically or cooled by passing through the tube side of a water-cooled heat exchanger, removing heat from the overall system.