Process Energetics Program
Center for Energy Studies
Regulation of volatile organic compound (VOC) emissions from industrial sources is a major element of the Clean Air Act Amendments of 1990. In the next decade, major investments will be made in VOC abatement equipment by industries using organic solvents. Since 1991 the Process Energetics Program at The University of Texas Center for Energy Studies has been developing a process which uses microwave heating to regenerate adsorbent beds for the purpose of solvent recovery.
Why use microwave heating to regenerate adsorbent beds? First, microwave regeneration facilitates solvent recovery. Conventional regeneration dilutes the desorbed solvent in the regeneration effluent because of the large volume of stripping gas required to adequately heat the bed. Consequently, this stream has a high flow rate and low concentration. It is frequently not cost-effective to then recover the solvent because of the large refrigeration requirements associated with cooling the entire flow stream below the very low dew-point temperature. With microwave heating it is possible to regenerate the bed using a very small amount of stripping gas (or none at all-- in vacuum). The regeneration effluent is therefore highly concentrated and can be condensed using near-ambient temperature cooling water.
Microwave regeneration can also produce much faster heat and mass transfer rates. This can yield substantial savings by increasing throughput (continuous systems) or reducing cycle time (batch systems).
The objective of our research program is to assess the technical and economic feasibility of microwave regeneration as a commercial technology for recovering adsorbed VOCs. It has consisted of 6 major elements:
1. Initial studies focussed on bench-scale experiments (1991-1994) to determine the microwave regeneration kinetics and obtain a better understanding of the underlying physical mechanisms.
2. Dielectric property measurements (1994) were performed for several adsorbent/solvent combinations.
3. Process design studies (1995) were conducted to examine the configuration and performance of proposed full-scale microwave regeneration systems.
4. Comparative economic feasibility studies (1995) evaluated the cost effectiveness of microwave regeneration with 10 conventional VOC control technologies.
5. A laboratory pilot column was constructed in 1996 to demonstrate the operation of a moving-bed microwave desorber for continuous adsorption systems.
6. The focus of our research efforts in 1997 and 1998 will be to design and construct a microwave regeneration field test unit which can be used to demonstrate the process at an industrial site.
For More Information
Please contact:
Philip Schmidt (512) 471-3118
or
David Price (512) 471-6964
Mailing address: 10100 Burnet Rd, Center for Energy Studies, Austin TX 78758.
Sponsors
This research has been sponsored by Borden, Inc., The Gulf Coast Hazardous Substance Research Center, and The University of Texas Environmental Solutions Program.