Emissions of hazardous air pollutants (HAPs) and volatile organic compounds (VOCs) to the atmosphere are serious environmental issues. There were 0.53 billion kg of HAPs and 15 billion kg of VOCs emitted to the atmosphere from anthropogenic sources during 2004 and 2002, respectively. Eighty-nine percent of those HAPs were emitted from point sources that can be readily captured by techniques such as adsorption. The cost to meet regulations for VOC control during 2010 was estimated at $2.3 billion/yr. Environmental regulations encourage the development of new technologies to more effectively remove HAPs/VOCs from gas streams at lower cost. Electrothermal Swing Adsorption (ESA), as described here, is a desirable means to control these emissions as it allows for capture, recovery and reuse or disposal of these materials while providing for a more sustainable form of technological development. The Vapor Phase Removal and Recovery System (VaPRRS or ESA-R)) was initially evaluated for possible improvements. An automated bench-scale adsorption device using activated carbon fiber cloth (ACFC) was designed and built to study effects of select independent engineering parameters on the ability of the system to capture and recover an organic vapor (e.g., methyl ethyl ketone, MEK) from air streams. Factors that can increase the adsorbate liquid recovery with low energy costs were investigated using sequentially designed sets of laboratory experiments. Initially, the screening experiments were conducted to determine significant factors influencing the energy efficiency of the desorption process. It was determined that 0́−concentration of organic vapor0́+, 0́−packing density0́+, and 0́−maximum heating temperature0́+ are significant factors while 0́−nitrogen flow0́+ and 0́−heating algorithm0́+ are insignificant factors in the ranges of values that were evaluated. Experimental data provided from this work were then used as inputs by Kaldate (2005) to complete a response surface methodology using Central Composite Design to optimize the operation of the ESA system in a region where efficient liquid recovery can be achieved. These results were used by Kaldate (2005) to reduce the amount of power applied per unit mass of ACFC in the vessel and provide a scale-up model of the ESA system. A comparison between experimental bench-scale VaPRRS and a pilot-scale VaPRRS was also completed as part of this research. Results from this effort demonstrated that both the bench-scale and pilot-scale ESA systems had removal efficiencies of MEK > 98%. The average electrical energy per unit mass of recovered liquid MEK was 4.6 kJ/g and 18.3 kJ/g for the bench unit and pilot unit, respectively. A new concentration controlled desorption device, known as ESA-Steady State Tracking (ESA-SS) desorption, was also designed and built as a bench-scale laboratory device as part of this research. This new system was demonstrated to operate over a wide range of conditions (i.e., type of organic vapor, concentration of organic vapor, ratio of desorption/adsorption cycle gas flow rates, fixed and dynamic desorption concentration set-points, constant and variable inlet concentration of organic vapor, batch and cyclic modes, and with dry and humid gas streams). It was shown that concentration of organic vapor that is generated during regeneration cycles can readily be controlled at concentration set-points for three organic compounds (MEK, acetone, and toluene). The average absolute errors (AAEs) were

Capture and recovery of hazardous air pollutants (HAPs) and volatile organic compounds (VOCs) from gas streams using physical adsorption onto activated carbon fiber cloth (ACFC) is demonstrated on the bench-scale. This system is regenerated electrothermally, by passing an electric current directly through the ACFC. The adsorbate desorbs from the ACFC, rapidly condenses on the inside walls of the adsorber, and then drains from the adsorber as a pure liquid. Rapid electrothermal desorption exhibits such unique characteristics as extremely low purge gas flow rate, rapid rate of ADFC heating, rapid mass transfer kinetics inherent to ACFC, and in-vessel condensation. An existing system was scaled up 500%, and the new system was modeled using material and energy balances. ... These results allow the modeling of electrothermal desorption of organic vapors from gas streams with in-vessel condensation to optimize operating conditions of the system during regeneration of the adsorbent.

Abatement of toxic volatile organic compounds (TVOCs) emitted to the atmosphere has become a concern because of the magnitude of the emissions and their potential health effects to humans and deleterious effects to the environment. New control technologies are being developed to separate and remove those toxic compounds from gas streams for reuse of the TVOCs in the process that generated them. This project evaluated the ability of an activated carbon fiber cloth (ACFC) adsorption, electrothermal desorption, cryogenic-condensation system to remove 10 cu cm/min containing 1000 ppmv of methyl ethyl ketone (MEK) or toluene from air streams that are dry or at 90 percent relative humidity. Results indicate that MEK and toluene are readily adsorbed from the carrier gas streams with the ACFC adsorber. Electrothermal desorption is also effective at desorbing the TVOCs and water from the ACFC. Cryogenic condensation is also effective for the dry MEK and toluene desorption conditions. Economic analysis shows that capitol costs for a conventional thermal swing GAC adsorption system will be 1.7 times greater than this system for the toluene dry air stream. The MEK recovery credit will be approximately four times greater than the annual operating costs for the MEK dry air stream.

Advances in Natural Gas: Formation, Processing, and Applications is a comprehensive eight-volume set of books that discusses in detail the theoretical basics and practical methods of various aspects of natural gas from exploration and extraction, to synthesizing, processing and purifying, producing valuable chemicals and energy. The volumes introduce transportation and storage challenges as well as hydrates formation, extraction, and prevention. Volume 2 titled Natural Gas Sweetening introduces in detail different natural gas sweetening methods. The book covers absorption with different solvents such as alkalis, amin blends, ionic liquids, etc. which is one of the important sweetening techniques, as well as natural gas sweetening with adsorption-based technologies utilizing various materials including zeolites, carbonaceous sorbents, metal oxides, etc. Is also discusses membrane-based processes with various types (such as ionic liquid, polymeric, MOF mixed matrix, dense metal membranes) and includes novel technologies for sweetening natural gas by using plasma and supersonic separators. - Introduces natural gas sweetening concepts and challenges - Describes various absorption and adsorption processes for natural gas sweetening - Includes various membrane technologies for natural gas sweetening