Membrane Separation of VOCs—(Membrane Technology and
Research Inc.)
Description of Technology
These vapor treatment
technologies are based on permselective membranes that separate the organic
components from the vapor stream, producing a VOC-free air stream. The membrane modules are designed with
membranes that are much more permeable to VOCs than air. VOCs and some air permeate the membrane,
thereby producing a nonpermeate, or reject, stream that is depleted of
VOCs. The contaminated air stream
contacts one side of the membrane, which is 10 to 100 times more permeable to
the organic compound than to air. The
separation is accomplished by a “reverse selective” polymeric membrane into
which organic molecules have higher solubility than smaller molecules such as
nitrogen, hydrogen or methane. The
membrane separates the contaminated air into two streams, a permeate stream
containing most of the organic vapor and a clean residual air stream. Then the organic vapor is compressed and
condensed to remove the organic fraction, while the purified air stream may be
vented or recycled into the system.
System capacity can range from 1 to 700 scfm, and are significantly
smaller than carbon adsorption systems of similar capacity. The systems have been tested with air
streams containing concentrations of organic compounds from 100 to more than
10,000 ppm. The VaporSep® system removes from 90 to 99% of
the organic vapor depending on the organic compounds present and the reactor
design, with the purified air stream having an organic concentration that is
generally low enough for discharge to the atmosphere. This VaporSep®
system can treat air streams containing flammable or nonflammable halogenated
and nonhalogenated organic compounds, including chlorinated hydrocarbons,
chloroflurocarbons, and fuel hydrocarbons.
The Membrane Technology
and Research, Inc. (MTR) membrane unit is a perforated pipe bound within a
spirally-wound module and spacers. Feed
gas flows between the membrane leaves, with the preferentially permeable
component spiraling inward to connect in the central permeate collection
pipe. The remainder of the feed flows
across the membrane surface and exits as the residue.
Figure 1. Vendor diagram
of the components of the VaporSep®
system membrane.
For additional details in
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