|
|
|
How It Works
This technology uses activated-carbon fiber cloth (ACFC) as an alternative adsorbent to traditional granular activated carbon (GAC) to remove and recover organic vapors from gas streams. The ACFC is microporous, has up to 250% of the adsorption capacity of GAC, has faster mass and heat transfer properties than GAC, and is ash free to inhibit chemical reactions between the ACFC and the adsorbed vapors.
Electrothermal desorption can be used to rapidly regenerate the ACFC with lower energy requirements than steam- or heated nitrogenbased regeneration. ED also eliminates the need for an adsorbent drying step and the recovered solvent/water separation processes usually required with conventional steam regeneration technology.
As shown in Figure 1, this technology consists of two adsorption/desorption units that enclose hollow elements containing ACFC and provide gas ports at either end. The compounds are adsorbed onto ACFC cartridges (Figure 2) that are electrothermally regenerated at a very rapid rate, causing the adsorbate to condense within the adsorption vessel itself and produce two-phase flow of the effluent during regeneration. The ACFC elements provide controlled electrical resistance, allowing for direct electrothermal heating and rapid regeneration of the ACFC and recovery of the VOCs/HAPs. Rapid ED with in-vessel condensation results in significant reductions in system complexity, cycle times, and nitrogen consumption. This new system also operates without the use of steam, heated inert gas, vacuum, or a refrigeration system. The pilot-scale system regenerates the ACFC within 40 minutes.
Figure 1: Overall Schematic of the ACFC AdsorptionRapid Electrothermal Desorption System

Figure 2: ACFC Adsorber

Performance in the Lab
Continuous VOC/HAP capture and recovery tests were performed with the bench-scale unit (125 mm diameter) while removing an array of solvents at a total gas flow rate ranging from 585 sLpm. The adsorption vessel contained 128 grams of ACFC. Single-component organic vapor tests were performed with MIBK; toluene; n-hexane, 2-pentanone (MPK); MEK; and n-hexane with controlled concentrations ranging from 100 to 10,000 ppmv in air. Overall removal efficiencies of greater than 99% were measured during the experiments.

Patents
[Links open new browser windows.]
- U.S. Patent #6,364,936: Selective sorption and desorption of gases with electrically heated activated carbon fiber cloth element (issued April 2, 2002)
- WIPO Application #WO 01/87461 A1: Selective sorption and desorption of gases with electrically heated activated carbon fiber cloth element (filed April 24, 2001)

Technical Papers
[Links open new browser windows.]
- "Capture and Recovery of Organic Compounds Using Adsorption and Electrothermal Regeneration," by P.D. Sullivan, M.J. Rood, K.D. Dombrowski, and K.J. James. Submitted in 2002 to Journal of Environmental Engineering.
- "Equilibrium Adsorption of Organic Vapors on Phenol-, Tire- and Coal- Derived Activated Carbons," by D. Ramirez, P.D. Sullivan, M.J. Rood, and K.J. James. Submitted in 2002 to Journal of Environmental Engineering.
- "Solvent Recovery and Energy Efficiency During Electric Regeneration of an ACF Adsorber," by K.D. Dombrowski, C.M.B. Lehmann, P.D. Sullivan, D. Ramirez, M.J. Rood, and K.J. James. Submitted in 2002 to Journal of Environmental Engineering.
- "Mercury Adsorption Properties of Sulfur Impregnated Adsorbents," by H.-C. Hsi, M.J. Rood, M. Rostam-Abadi, S. Chen, and R. Chang (2002). Published in Journal of Environmental Engineering, 128(11):1080-1089
- "Effects of Sulfur Impregnation Temperature on the Properties and Mercury Adsorption Capacities of Activated Carbon Fibers (ACFs)," by H.-C. Hsi, M. Rostam-Abadi, M.J. Rood, S. Chen, and R. Chang (2001). Published in Environmental Science & Technology, 35(13):2785-2791.
- "Development of an Activated Carbon Fiber Cloth Adsorption/Regeneration System to Recover and Reuse Toxic Volatile Organic Compounds," by Mehrdad Lordgooei, Kelly R. Carmichael, Mark J. Rood, and Susan Larson. Final Report for Project HWR 94115. Prepared for the Illinois Department of Natural Resources, December 1, 1998. Available via the North Carolina Dept. of Environment and Natural Resources, Division of Pollution Prevention and Environmental Assistance.
- "Adsorption and Electrothermal Desorption of Hazardous Organic Vapors," Sullivan, P.D., Rood, M.J., Hay, K.J., and Qi, S (2001). Published in Journal of Environmental Engineering, 127(3): 217-223.
- "Modeling Effective Diffusivity of Volatile Organic Compounds in Activated Carbon Fiber," Lordgooei, M., M. J. Rood, M. Rostam-Abadi (2001). Published in Environmental Science & Technology, 35: 613-619.
- "Carbon Fiber Adsorption Using Quantitative Structure-Activity Relationship," Qi, S., Hay, K.J., Rood, M.J., Cal, M.P. (2000). Published in Journal of Environmental Engineering, 126(9): 865-868.
- "Equilibrium and Heat of Adsorption for Water Vapor and Activated Carbon," Qi, S., Hay, K.J., Rood, M.J. and Cal, M. (2000). Published in Journal of Environmental Engineering, 126(3): 267-271.
- "Preparation and Evaluation of Coal-Derived Activated Carbons for Removal of Mercury Vapor from Simulated Flue Gases," Hsi, H-C., Chen, S., Rostam-Abadi, M., Rood, M.J., Richardson, C.F., Carey, T. R., Chang, R., (1998). Published in Energy & Fuels, 12(6): 1061-1070.
- "Isotherm Equation for Water Vapor Adsorption onto Microporous Activated Carbon," Qi, S., Hay, K.J., Rood, M.J. (1998). Published in Journal of Environmental Engineering, 124(11): 1130-1134.
- "Sorption and Mass Transfer of Toxic Chemical Vapors in Activated Carbon Fiber Cloth Fixed Bed Adsorbers," Lordgooei, M., Sagen, J., Rood, M.J., Rostam-Abadi, M., (1998). Published in Energy & Fuels, 12(6): 1079-1088.
- "Gas Phase Adsorption of VOCs and Water Vapor on Activated Carbon Cloth," Cal, M.P., Rood, M.J., and Larson, S.M. (1997). Published in Energy & Fuels,11: 311-315.
- "Activated Carbon Cloth Adsorption Cryogenic System to Recover Toxic Volatile Organic Compounds," Lordgooei, M., Carmichael, K.R., Kelly, T.W., Rood, M.J., and Larson, S.M. (1996). Published in Gas Separation and Purification, 10(2): 123-130.
- "Removal of VOCs from Humidified Gas Streams Using Activated Carbon Cloth," Cal, M.P., Rood, M.J., and Larson, S.M. (1995). Published in Gas Separation and Purification, 10(2): 117-121.
- "Chemically Treated Activated Carbon Cloths (ACCs) for Removal of Volatile Organic Carbons from Gas Streams: Evidence for Enhance Physical Adsorption," Dimotakis, E., Cal, M.P., Economy, J., Rood, M.J., and Larson, S. (1995). Published in Environmental Science and Technology, 29(7): 1876-1880.
- "Water Vapor Adsorption on Chemically Treated Activated Carbon Cloths," Dimotakis, E., Cal, M.P., Economy, J., Rood, M. and Larson, S. (1995). Published in Chemistry of Materials, 7(12): 2269-2272.
- "Experimental and Modeled Results Describing the Adsorption of Acetone and Benzene onto Activated Carbon Fibers: Comparison of Experimental and Modeled Isotherms," Cal, M.P., Larson, S.M., and Rood, M.J. (1994). Published in Environmental Progress, 13(1): 26-30.
- "Adsorption Characteristics of Trace Volatile Organic Compounds in Gas Streams onto Activated Carbon Fibers," Foster, K.L., Fuerman, R.G., Economy J., Larson, S.M., and Rood, M.J. (1992). Published in Chemistry of Materials, 4(5): 1068-1073.

Press Coverage
[Links open new browser windows.]
- "Vapor Recovery System to Capture and Recycle Air Pollutants," press release posted on the University News Bureau site and picked up by many online publications
- "Filter Designed to Help Environment," article published October 12, 2000, at The Daily Illini Online

Demonstration
[Links open new browser windows.]
- Video: Electrothermal Regeneration of Activated Carbon Fiber Cloth (ACFC) (3 Mb)

Presentations
[Links open new browser windows.]
- "Evaluation of Bench- and Pilot-Scale Adsorption Systems to Capture and Recover Organic Vapors via Electrothermal Desorption" by C.M.B. Lehmann, D. Ramirez, S. Lo, K.D. Dombrowski, P.D. Sullivan, M.J. Rood, and K.J. Hay. Presentation (No. 43046) at the 2002 Annual Meeting of the Air & Waste Management Association, Baltimore, Maryland.
- "Characterization of the Physical and Thermal Properties of a Series of Activated Carbon Fiber Cloths," by S. Lo, D. Ramirez, M.J. Rood, and K.J. Hay. Presentation (No. 43166) at the 2002 Annual Meeting of the Air & Waste Management Association, Baltimore, Maryland.


|
|