1. Emerging Technology Acid Gas Removal
EPA’s Natural Gas STAR Program,
Pioneer Natural Resources USA, Inc., and
The Gas Processors Association
June 17, 2003

2. New Developments in Acid Gas Removal Technologies
Typical Amine Process
IGT & Uhde Morphysorb® Process
Engelhard Molecular Gate® Process
Comparison

3. Typical Amine Process Acid Gas Sweet Gas Lean Amine Stripper (Steel)
Condenser
Contractor (Adsorber)
Reflux Pump
Reboiler
Sour Gas
Fuel
Rich Amine
Heating Medium
Flash Tank
Exchanger
Booster Pump
Filter

4. CO2 REMOVAL PIPELINE QUALITY
Morphysorb® Process
Clean Gas
Lean Solvent
Semi Lean
Sour Gas
Absorber
Crude Gas
Flash 1
Flash 2
CO2 REMOVAL PIPELINE QUALITY
High CO2 containing natural gas can be upgraded to pipeline quality by operating at normal temperatures with only flash regeneration of the solvent.
The flash gas out of the first flash stage is recycled to the inlet of the absorber to minimize the losses of methane. In the second flash stage, the semi-lean solution is regenerated by means of pressure decrease. The semi-lean solution then is fed after cooling to the lower section of the absorber. The third flash stage is a vacuum flash, generating lean solution which is fed to the top of the absorber.
High CO2 containing natural gas can be upgraded to LNG quality by incorporating thermal regeneration. The Figure shows a concept designed to remove CO2 to LNG quality which incorporates three flash stages at different pressures and thermal regeneration of the solvent NFM. The flash gas released from the first flash is recycled to the natural gas feed upstream absorber.
Flash 3
Flash Recycle
c. w.
c. w.

5. Morphysorb® Field Test Unit
The process is ready for commercial-scale application
One field test unit at Shell's Exploration and Production facilities in Fandango, Texas, USA
Feed capacity: 1 MMscfd
Technology Highlights
High CO2 and H2S loadings, further increased at low absorption temperatures
Selective H2S removal, facilitating sculpture recovery without further enrichment of H2S
Simultaneous absorption of organic sulphur compounds and water, thus avoiding additional treatment units
Small recycle gas flow due to low co-absorption of CH4
Low capital investment, mainly carbon steel equipment
Source: Morphysorb® Process. IGT & Uhde Technology Profile

6. Pressure Swing Absorption
Molecular Gate® CO2
Feed Compressor
Enriched CH4
30 psia
10 psi pressure drop
PRODUCT
C1, C2
Pressure Swing Absorption
FEED High Pressure
C1, C2, C3, C4+ CO2, H2O
5 psia
Molecular Gate Adsorbent for Carbon Dioxide Removal
In the removal of carbon dioxide from natural gas, carbon dioxide is both a smaller molecule than methane and one that is adsorbed more strongly. The combination of pore size optimization and adsorbent attraction results in the ability to remove carbon dioxide with minimal adsorbent inventories and high methane recoveries.
Since carbon dioxide is strongly adsorbed, the adsorbent properties can be tailored so that the adsorbent can also remove water vapor. This eliminates the need for glycol dehydration, as is the case with nitrogen rejection, and is an operation and cost benefit.
Pressure Swing Adsorption
As with nitrogen rejection, the carbon dioxide removal process utilizes a pressure swing adsorption (PSA) system. In the system, carbon dioxide is adsorbed at high-pressure and removed from the adsorbent at low-pressure.
In addition to the operational advantages of a dry system for carbon dioxide removal, the PSA process eliminates the need for glycol dehydration. The system cost is considerably lower than nitrogen rejection PSA systems because the workable adsorbent capacity is higher. The system also is fully regenerable in the pressure swing process, and no thermal regeneration is required.
The net effect of the relative ease of removing carbon dioxide is that a rather simple three-vessel cycle can be applied, even for relatively large flow rates.
TAIL GAS
CO2, H2O, C3+,
Lost HCs
Vacuum Compressor

7. Tidelands Molecular Gate Unit
First commercial unit started on May 2002
Separate recycle compressor is required
No glycol system is required
Heavy HC removed with the CO2
Tail gas used for fuel is a key optimization
18% CO2 removed to pipeline specifications
C2 + losses makes the applicability site specific
Engelhard's new Molecular Gate® CO2
First commercial unit started on May 2002
Separate recycle compressor is required
No glycol system is required
Heavy HC removed with the CO2
Tail gas used for fuel is a key optimization
18% CO2 removed to pipeline specifications
C2 + losses makes the applicability site specific
Source:

8. Morpholine Derivatives Reduce Pressure to Vacuum
Comparison
Amine Process
Morphysorb® Process
Molecular Gate® CO2
Absorbent or
Adsorbent
Water & Amine
Morpholine Derivatives
Titanium Silicate
Regeneration
Reduce Pressure & Heat
Reduce Pressure to Vacuum
Primary Operating Costs
Amine & Steam
Electricity
Amine process
Costs. A higher feed pressure would have a benefit for the amine unit due to higher loading of the carbon dioxin
Molecular Gate CO2:
Recovery rate(RR) 75% acceptable for tidelands but insufficient for other fields where a RR of 95% is expected
Costs. The capital advantages for the Molecular gate system are case specific. A feed pressure of psig is about optimum
Operations. PSA Easy operations with credits for unattended operations, easier permit and no losses of solvent from the system