Project Title:
Removal of Nitrogen from Carbon-Dioxide-Rich Streams
12.04-2228
910202
Removal of Nitrogen from Carbon-Dioxide-Rich Streams
Membrane Technology & Research, Inc.
1360 Willow Road, Suite 103
Menlo Park
CA
94025
Richard W.
Baker
415-328-2228
JSC
NAS9-18695
245
12.04-2228
910202
Abstract:
Removal of Nitrogen from Carbon-Dioxide-Rich Streams
The objective of this project is to develop a membrane process for removing nitrogen
from carbon-dioxide-rich gas streams. Manned space vehicles on long missions must
use regenerative life-support systems. Although a variety of techniques exist for
converting carbon dioxide back into oxygen, they require that the nitrogen content
of the carbon dioxide feed stream be reduced to less than 0.2 percent. Current separation
techniques are energy-intensive and unsuited for spacecrafts because of their bulk,
weight, and complexity. A membrane process would be compact and lightweight, and
use less energy. The membrane process to be developed is based on composite membranes
prepared with rubbery materials like the perm-selective layer. The selective materials
of choice will have a low permeability for nitrogen and a high permeability for carbon
dioxide. The composite membranes will be tested with pressurized mixtures of carbon
dioxide and nitrogen. In preliminary work, a membrane has already been established
that has a selectivity value for carbon dioxide from nitrogen of 60 and a carbon
dioxide normalized flux of 3x10-4cm3(STP)/cm2 sec cmHg. These values would make a
small, lightweight membrane system that could deliver purified carbon dioxide at
a recovery rate of 97.5 percent possible. Phase I will prepare and evaluate membranes,
first as discs in laboratory cells, later as small spiral-wound membrane modules.
Based on the results, an engineering analysis of the nitrogen removal process will
be performed, and its suitability for development into a prototype system in Phase
II program will be determined.
Besides its use in spacecraft, a membrane system that could separate carbon dioxide
efficiently from other gases would have an enormous potential in natural gas processing.
air regeneration, nitrogen, carbon dioxide, membrane spacecraft