United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/S2-90/016 June 1990
©EPA Project Summary
Test and Evaluation of a
Polymer Membrane
Preconcentrator
Kirk E. Hummel and Thomas P. Nelson
The report gives results of art
evaluation of the applicability of
membrane systems as a
preconcentrator and defines
operating parameters of a membrane
system. Advantages of such a system
is a potential reduction in cost for
subsequent control systems. The
evaluation is part of a joint
EPA/California Air Resources Board
investigation of the potential of
membrane technology on volatile
organic compound (VOC) emissions
Tests of various membrane materials
and configurations have been
conducted. A potentially innovative
application of membrane technology
may be to concentrate VOCs from
exhaust gases such as solvent oven-
drying exhaust. A preconcentrator
membrane could be used to reduce
the size and, in turn, the capital and
operating costs of a conventional
VOC control device such as a carbon
adsorber or incinerator. Study results
do not, however, verify that a
membrane preconcentrator is a
viable option to reduce overall
pollution control costs.
This Project Summary was
developed by EPA's Air and Energy
Engineering Research Laboratory,
Research Triangle Park, NC, to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
The polymeric membrane has been
used for a number of years as a
concentrating step for various liquid and
gaseous streams, including removal of
large molecule organics from waste water
streams, hydrogen separation, and CO2
recovery. A polymer membrane is an
ultrathin layer of a selective polymer,
supported on a porous sublayer. The
membrane (active layer) selectively filters
the pollutant molecules. Figure 1 is a
diagram of a bench scale membrane
system. A potentially innovative
application of membrane technology may
be the concentrating of volatile organic
compounds (VOCs) from exhaust gases
such as solvent oven-drying exhaust. A
preconcentrator membrane could be
used to reduce the size and, in turn, the
capital and operating costs of a
conventional VOC control device such as
a carbon adsorber or incinerator. The
overall result' would be capital and,
operating cost savings, possible;
performance improvements,' and reduced;
energy requirements.
The U.S. EPA and the California Air
Resources Board initiated a joint program
to investigate the potential of membrane
technology on VOC emissions. Tests of
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various membrane materials and of the membrane and associated
configurations have been conducted. equipment.
Objectives of those studies were to
evaluate the applicability of membrane
systems as a preconcentrator and to
define operating parameters of a
membrane system. The advantage of
such a system is a potential reduction in
cost for subsequent control systems.
Program Approach
Tasks completed for the study include: •
(a) A detailed literature review of
available data on membrane
recovery of hydrocarbon vapors
and gases. Relevant data and
articles on the subject of
membrane technologies are
discussed in the report.
(b) Bench scale membrane modules
were tested using six common " ~ ~ """•""
solvents to define capability of
membrane to retain solvents and
to develop system operating
parameters.
(c) Preliminary conceptual designs
were developed from laboratory
studies.
(d) Preliminary capital and operating
cost projections for membrane
augmented control options were
developed.
To support these tasks a bench-scale
polymeric system was designed and
constructed. The spiral-wound membrane
was supplied by a commercial
membrane manufacturer. The bench-
scale test processed dilute gas streams
containing 20 to 2000 ppmv solvent.
Results and Conclusions
The membrane was shown capable of
removing about 60% of the incoming
solvent, and generated a permeate
stream about 3 times as concentrated as
the original feed. It was equally effective
on all six solvents tested. No noticeable
degradation in performance of the
module was apparent after the tests,
although an extended performance
evaluation was not conducted.
Based on the test data and available
cost data for two simple configurations,
membrane technology does not appear
to be a good alternative to carbon
adsorption or other classical control
options for low concentration (e.g., 100
ppmv) solvent-laden air streams at this
time. The capital and annualized costs of
the membrane-augmented system were
consistently higher than for the carbon
adsorber alone. Cost reductions for the
membrane-augmented carbon adsorber
(due to the reduced volume flow) were
not sufficient to cover the added expense
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i (To Vent)
(Recycle)
j ! Clean Air
(To Vent)
VOC
Emissions
Stripped
Off-gas
VOC Source
Membrane
Preconcentrator
Concentrated
- VOC
Final VOC
Control Device
Recovered VOC
(Solvent)
Figure 1. Membrane preconcentrator system..
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K. Hummel and T. Nelson are with Radian Corp., Austin, TX 78720-1088.
Charles H. Darvin is the EPA Project Officer (see below).
The complete report, entitled "Test and Evaluation of a Polymer Membrane
Preconcentrator," (Order No. PS 90-188 905/AS; Cost: $23.00, subject to
change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States Center for Environmental Research
Environmental Protection Information
Agency Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S2-90/016
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