oxygen separation

1. 1
Group Members:
 Ahmed Alsaggaf (G202391230)
 Taha Najam (G202308870)
 Abdullah Yahya (G202301210)
 Abdisalam Mohamed(g202309790)

2. 2
Introduction
Types of Polymeric Membranes
Polymeric Membrane Structure
Transport Coefficients for gas separation with membranes
Applications of Oxygen-Enriched Air
Feasibility Analysis of OEA with Polymeric Membranes
References

3. 3
Air contains about 21% oxygen, 78% nitrogen, and trace
amounts of other gases.
The implementation of membrane systems is growing in
the industry because of their versatile field of use[1].
Membranes are fundamentally categorized into metallic,
inorganic, and polymeric membranes.
Using the polymeric membrane for producing oxygen-
enriched air (OEA) production is superior [1].

4. • Polymeric membranes are thin,
selective barriers made from various
synthetic or natural polymers.
• This Allows only certain substances to
pass through while blocking others.
• They are crucial components in
applications such:
• Water Treatment
• Gas Separation
• Biomedical Devices
• Food Processing
4
Various Applications based on pore sizes [2].

5. • Theory of Gas Permeation
5
• Transport Mechanism
• Quantitative Description
• Membranes are separate gas mixture components based
on permeation rates.
• High-purity permeate requires a high partial pressure of
the faster permeating gas in the feed stream
• Feed gas passes through the membrane under pressure,
yielding permeate and retentate.
• Membranes are classified as porous (pore sizes: 5-100
nm) or nonporous (0.3-1 nm).

6. • Theory of Gas Permeation
6
• Transport Mechanism
• Quantitative Description
• Knudsen diffusion operates in pores smaller than 0.1
μm, facilitating gas separation based on molecular
weight
• Molecular sieving prevents larger molecules from
passing through small pores.
• The solution-diffusion involves three steps: absorption,
diffusion, and desorption on the other side. Separation
is based on concentration gradients and solubility
differences.

7. • Theory of Gas Permeation
7
• Transport Mechanism
• Quantitative Description
 The permeability coefficient:
 The ideal separation factor (Selectivity):
• PX : Permeability coefficient
• l : Membrane Thickness
• (Ph-Pl): Upstream and downstream Pressure
difference
 Fick’s 1st law:
• Sx : Solubility
• Dx : Diffusivity

8. • Copolymer and blended polymeric
membrane
8
• Polymer of intrinsic microporosity
• Asymmetric Membranes
 Asymmetric membranes consist of a thin, dense top
layer (skin or active layer) supported by a thicker
porous substrate layer.
 Top layers are categorized as ultrathin (1000–5000 Å)
or hyper-thin (<1000 Å), with defect-free layers crucial
for effective gas separation.
 The bottom layer primarily provides mechanical
support and structural integrity to the membrane.
 Interfacial Polymerization is the manufacturing
technique.

9. • Copolymer and blended
polymeric membrane
9
• Polymer of intrinsic microporosity
• Asymmetric Membranes  Copolymer membranes combine multiple monomers,
while blended polymeric membranes contain
homopolymers formed post-synthesis.
 Block copolymer-based membranes, like (TMHF-NPSF),
offer high selectivity and permeability for O2/N2
separation due to their structural properties.
 The cavity size in block copolymer membranes
influences gas separation performance; larger cavities
generally enhance permeability but decrease selectivity.
 Polymer Blending is the manufacturing technique.

10. • Copolymer and blended polymeric
membrane
10
• Polymer of intrinsic
microporosity
• Asymmetric Membranes  A novel type of polymer characterized by its amorphous
structure with twisted or bending features and a porous,
rigid polymeric network.
 PIM exhibits high surface area and large free volume,
leading to exceptional O2 permeability and O2/N2
selectivity.
 Specifically, PIM ladder polymers demonstrate remarkable
selectivity for O2/N2 while maintaining high O2
permeability due to their extensive surface area and free
volume.
 Step-growth Polymerization is the manufacturing method.

11.  Asymmetric Membranes:
11
 Copolymer and blended polymeric membrane:
 Microporous Polymers:

12.  Interfacial Polymerization:
 Interfacial polymerization involves
the reaction of two immiscible
monomer solutions at a liquid-liquid
interface.
 The reaction forms a thin, dense
polymer film, typically consisting of
a selective top layer and a porous
substrate layer.
12
 Polymer Blending:
 Polymer blending combines different
homopolymers to form copolymers
with unique chemical and physical
properties.
 Blending allows for the incorporation
of multiple monomers, enabling the
creation of copolymers with desired
characteristics such as improved
flexibility, strength, or chemical
resistance.
 Step-Growth Polymerization :
 Step-growth polymerization involves
multifunctional monomers reacting in
pairs to form covalent bonds, leading
to the gradual growth of polymer
chains.
 It proceeds through stepwise addition
of monomers, allowing for the
formation of diverse polymer
structures and compositions.

13. Schematic representation of the membrane
separation process [3].
13
Two-stage cascade
membrane unit for
production of O2
from air.
Two-stage cascade
membrane unit with
recycle.

14.  There are other processes for
oxygen separation such as:
Cryogenic Distillation (common)
Pressure Swing Adsorption
 However, Polymeric membranes
are found to be good for selective
applications for the following
general reasons[1]:
14
BENEFITS:
 Lower Energy Consumption
 Simplified Process
 Compact Footprint
 Continuous Operation
 Selective Separation
 Cost-Effectiveness

15. • Pressure Swing Adsorption
15
• Cryogenic Distillation
 Cryogenic distillation separates oxygen by exploiting
differences in boiling points between oxygen and nitrogen.
 The air is cooled to very low temperatures, typically below
the boiling point of nitrogen but above that of oxygen,
causing nitrogen to liquefy while oxygen remains gaseous.
 The liquid nitrogen is then removed, leaving behind
enriched oxygen, which can be further purified if necessary.
 Cryogenic distillation is energy-intensive but highly
efficient, especially for large-scale oxygen production.

16. • Pressure Swing Adsorption
16
• Cryogenic Distillation
 Pressure swing adsorption (PSA) separates oxygen by
selectively adsorbing nitrogen onto a solid material while
allowing oxygen to pass through.
 It operates in cycles, with adsorption and desorption steps.
 During adsorption, nitrogen is captured at high pressure,
while during desorption, nitrogen is released at reduced
pressure.
 The cyclic variation in pressure allows for continuous oxygen
production.

17. Combustion
enhancement.
Enhancement of
fuel cell
processes.
Medical
applications.
Underwater
breathing.
Chemical
industry,
refineries.
Production of
peroxides.
Wastewater
treatment.
Welding.
Glass production
Fermentation
Processes
17
Applications of OEA
Application Distribution [5]

18.  Coal Gasification market is to grow by 16%.
 Coal gasification is a thermochemical process that
transforms coal into syngas by reacting it with
steam and oxygen or air. The syngas produced
contains carbon monoxide, hydrogen, carbon
dioxide, methane, and other gases.
 It offers higher efficiency due to better control over
the combustion process. It also results in lower
emissions. Additionally, coal gasification enables
the potential for carbon capture and storage
(CCS).
 Oxygen is a crucial component in C.G as it
enhances the efficiency of the process by
facilitating cleaner combustion.
 Oxygen purity required is greater than 90%.
18

19.  O2 concentration required is at 30%.
 Single Stage System can achieve this.
 Types include: Feed Compression
 Comparison needs to be established
19
OVERVIEW
Process Flow Diagram
Single Stage
Double Stage
Triple Stage

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Cost Of Seperation Based On Membrane Material:

21. 21
Cost Of Seperation Based On Membrane Material:

22.  Selectivity
22
DOUBLE-STAGE SYSTEM
 Permeability = 100
GPU
2 10
 Purity
54.5% 96.8%
 Cost
0.22 $/kg 0.21 $/kg
 Selectivity
TRIPLE-STAGE SYSTEM
 Permeability = 100 GPU
2 10
 Purity
95% 99.7%
 Cost
0.38 $/kg 0.31 $/kg
A conclusion from this analysis is that improvement in
permeance appears to have a greater impact on the gas
cost than does increasing selectivity.
Polyimide Carbon membrane with selectivity of 15
and permeability of 200 Barrer has a very low cost
of production of US$0.033/kg and purity of 98.5%.
Polyimide based Carbon membrane with selectivity
of 15 and permeability of 200 Barrer has a
relatively low cost of production of US $0.039/kg
with a purity of 99.9%.

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Cost of Electricity
Module Material Cost
SUMMARY:
- Cost changes with electricity cost:
 Single stage: US$0.085/kg to US$0.1/kg
 Double stage: US$0.22/kg to US$0.27/kg
 Triple stage: US$0.34/kg to US$0.4/kg
- Based on membrane parameters:
 Permeance: 100 GPU
 Selectivity: 4

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Cost of Electricity
Module Material Cost
SUMMARY:
- Cost changes with electricity cost:
 Single stage: US$0.085/kg to US$0.1/kg
 Double stage: US$0.22/kg to US$0.27/kg
 Triple stage: US$0.34/kg to US$0.4/kg
- Based on membrane parameters:
 Permeance: 100 GPU
 Selectivity: 4

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DOUBLE-STAGE SYSTEM TRIPLE-STAGE SYSTEM
Final Cost: 0.05$/kg Final Cost: 0.071$/kg
COMPARISON
Cryogenic Distillation
Pressure-Swing Adsorption

26. 26
DOUBLE-STAGE SYSTEM
Final Cost: 0.05$/kg
COMMENTS
CRYOGENIC DISTILLATION
PRESSURE-SWING
ADSORPTION
Final Cost: 0.045$/kg
Final Cost: 0.065$/kg
Potential cost reduction strategies:
 Improve membrane cost and material used.
 Enhance both permeability and selectivity
simultaneously.
Cryogenic distillation technology:
 Cryogenic distillation's economics optimized
for large-scale systems.
 Cost increases with decreased scale.

27.  Combined cycle plants outperform
traditional natural gas combustion by
achieving efficiencies of 50% or higher,
compared to 30-40%.
 NGCC plants have higher initial costs, their
efficiency leads to lower long-term fuel
expenses, potentially making them more
economically viable over time.
 Oxygen is a crucial component in N.G.C.C as
it enhances the efficiency of the process by
facilitating cleaner combustion.
 Oxygen purity required is around 30%.
27

28.  Single Stage System can achieve this.
 Feed Compression, Permeate Vacuum can achieve 30% purity.
 Vacuum operation is preferred for its lower energy demand compared to feed gas compression.
 These membrane processes remain economically uncompetitive with cryogenic distillation or
pressure swing adsorption at industrial scales.
28
OVERVIEW
Process Flow Diagram
Permeate Vacuum
Feed Compression
NEED A BETTER PROCESS TO COMPETE

29.  A turboexpander that improves energy
efficiency and
 A countercurrent/sweep membrane design
that improves separation efficiency.
 The process produces 7.1 m3(STP)/s of 30%
oxygen-enriched air,
 This is 262 tons O2/day or 100 tons/day EPO2
 Membrane needs an oxygen permeance of
1200 gpu and an O2/N2 selectivity of 3.0.
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COUNTERCURRENT/SWEEP OPERATION

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COMPARISON WITH OTHER METHODS

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MEMBRANE MATERIAL
• High Permeance
• Low Selectivity
Per-fluoropolymer (PFP)
Based Composite Membrane
EXPERIMENTAL SETUP

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MEMBRANE OPTIMIZATION STUDIES
PFP wt% variation
PFP layer Thickness Variation

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SYSTEM OPTIMIZATION STUDIES
Feed Flow Variation at constant
Pressure
Feed Flow Variation at Varying Pressures

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COST COMPARISON TO OTHER
TECHNIQUES
N.G.C.C EFFICIENCY

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COMMENTS
 At an exhaust gas temperature of 1649 °C,
using oxygen-enriched air containing 30%
oxygen can save 35% fuel compared to air
combustion.
 Membrane-based oxygen-enriched
combustion offers significant energy savings
and economic benefits compared to
cryogenic distillation, VSA, and PSA.
PFP MEMBRANE VS CONVENTIONAL

36.  Magnetohydrodynamic (MHD)
Power Generation (up to 1000
MW)
 PC (Pulverized Coal Combustion)
 Iron Blast Furnace
 Liquid Burner Applications
36
Applications include:
• The membrane technology is better than cryogenic
distillation for producing oxygen enriched air.
• The estimated capital advantage is 3.8-4.1 million
dollars for 300 Ton O2.
• The bottom-line cost advantage is $2.11 to $3.68 per
ton O2.
• Existing carbon capture technology yields greater
efficiency.
• Blast furnace capacity would be increased by
about 16%
• Energy savings, due to elimination of heat
would be about 0.7 Btu/ton iron (equal to cost
of enrichment). Therefore, making it
feasible..
• Oxygen enrichment boosts fuel burning, achieving
51% power increase.
• Stable air flow crucial for maintaining optimal
burner performance.
• Oxygen enrichment aids combustion engineers in
enhancing power output.

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Pulverized Coal Power Plant with OEA [8].
Polymeric Membranes with a small pore size
contribute to Gas Separation.
Membrane Technology is effective for production of
Oxygen Enriched Air when compared to selective
other methods.
Oxygen Enriched Air has a wide variety of
applications, but production is not limited to
polymeric membranes.
Feasibility Analysis shows Power Plant application
yield a techno-economic benefit compared to other
applications.
Existing Literature point towards Pulverized Coal
Power Plants as they are made more efficient with
oxy-combustion; as well as more eco-friendly.

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