(709c) Short TSA Cycles Using A Novel Bed Design

A novel TSA bed design has been developed as part of an ongoing effort to provide continuous air purification for military and government applications. The new bed design permits cooling and heating fluid to be circulated within the bed to greatly reduce the cycle time of a TSA system. Short cycle times are critical for efficient removal of volatile toxic vapors. In addition, when integrated with an Environmental Control Unit (ECU) the new bed design permits the adsorbent to be cooled to further enhance the volatile gas removal efficiently.

Several different bed designs have been built and tested. Test results for simulated cycles using single and layered beds have shown that a 10-minute 1/2 cycle time is achievable. Two feed chemical vapors are tested used to evaluate the ability of the beds to provide chemical protection, namely; (1) Ammonia fed at 2650 ppm and (2) R134a at 250 ppm . A schematic of the test TSA test system as well as temperature and concentration data for the ammonia and R134a experiments will be presented.

There are several potential advantages that the novel bed design may provide in industrial applications where it is desired to remove more weakly adsorbed vapors. Some of these advantages include:

1. In-bed heating and cooling greatly reduce the purge gas requirements for regeneration. In cases where the purge gas is valuable, this could reduce operating costs.

2. Cooling the bed during the feed step provides at least two benefits. First, it can reduce adsorbent inventory. Second, it can reduce the purge temperature needed for regeneration since it is the differential between feed and purge temperatures that is important for more weakly adsorbed gases. Low temperature purge may be particularly useful for flammable adsorbates such as methyl , ethylketone (MEK).

3. Overall size and power can be greatly reduced if the new bed deign is integrated with an ECU. For example, waste heat that is normally rejected off of the air conditioning condenser can be recovered to regenerate the adsorbent beds.