Hydrogen sulfide, carbon dioxide,mercaptans and other contaminants areoften found in natural gas streams. H2S is ahighly toxic gas that is corrosive to carbonsteels. CO2 is also corrosive to equipmentand reduces the Btu value of gas. Gassweetening processes remove thesecontaminants so the gas is suitable fortransportation and use.

NATCO designs and manufactures avariety of gas sweetening systems,including amine systems. NATCO offers anumber of amine solvents, that remove thecontaminants by chemical reaction.Custom and standard designs are availableto meet any gas sweetening challenge,and lease/purchase options are available.

Amine Sweetening ProcessNATCO amine sweetening systems are basedon proven gas sweetening technology. The systems are efficient and effective. The following step-by-step explanation refersto Figure 1.1 Sour gas enters the contactor tower and

rises through the descending amine solution.

2 Purified gas flows from the top of thetower.

3 The amine solution, carrying absorbed acidgases, leaves the tower for the heatexchanger or optional flash tank.

4 Rich amine is heated by hot regeneratedlean amine in the heat exchanger.

5 Rich amine is further heated in the regener-ation still column, by heat supplied fromthe reboiler. The steam rising through thestill liberates H22 and CO2 regenerating theamine.

6 Steam and acid gases separated from therich amine are condensed and cooled,respectively, in the reflux condenser.

7 Condensed steam is separated in the refluxaccumulator and returned to the still. Acidgases may be vented, or directed to a sulfur recovery system.

8 Hot regenerated lean amine is cooled in asolvent aerial cooler and circulated to thecontactor tower, completing the cycle.

9 A variety of heat sources may be used forthe still reboiler: direct-fired, waste heat,hot oil and steam systems.

Amine Gas Sweetening Systems

Field Proven Gas Sweetening System

Issue 7 July 2002 Page 531-A1

Figure 1 Typical Amine Systems Flow Diagram

Amine Gas Sweetening Systems

Issue 7 July 2002 Page 531-A2

NATCO Group Head OfficeHouston, USATel: +(1) 713 683 9292Email: sales@natco-us.com

NATCO CanadaCalgary, CanadaTel: +(1) 403 236 1850Email: sales@natco.ab.ca

NATCO JapanTokyo, JapanTel: +(81) 33288 1901Email: natco1@natcojapan.com

Axsia GroupGloucester, EnglandTel: +(44) 1452 833800Email: asbl@axsia.com

Axsia HowmarCamberley, EnglandTel: +(44) 1276 681101Email: ahl@axsia.com

www.natcogroup.com

For more information on NATCO Amine Gas SweeteningSystems or other NATCO Group products contact:

Custom-Designed Gas SweeteningPlants

Systems engineered to suit yourneedsNATCO custom designs and manufacturesamine sweetening plants for any particu-lar application. Our specially engineeredsystems adapt the basic amine process toyour gas flow rates, stream composition,desired outlet quality and more. Theamine plant may stand alone or work aspart of an integrated processing installa-tion, offshore or onshore. Sizes rangefrom 125 gpm to 2000 gpm and higher,with contaminants in any concentration.Below 125 gpm circulation rates, NATCOoffers six standardized designs.

Custom performance from astandard designNATCO has put years of gas sweeteningexpertise into the design and engineeringof six standardized gas plants. You get thekind of performance with these standardplants that you expect from a custom-designed sweetening plant.

Standardized Amine Plants

Standardized plants save you timeand moneyBy standardising the gas sweeteningdesign, we are able to provide fastdelivery and a savings in engineering cost.

Six complete gas sweeteningpackagesNATCOs standardized plant is designedin six sizes for the most frequentlyrequired solvent circulation rates.

The standard plants are shop-fabricatedmodular packages. They are skid-mountedand include all piping and controls. Theplants are designed to use a variety ofsolvents, as well as MEA, DEA, MDEA, DGAand Sulfinol.

Equipment included in each plant: Amine contactor tower Reboiler/surge tank Reflux condenser/solution cooler in a

common aerial cooler package Reflux accumulator Reflux pump(s) Main solvent pump(s) Solvent booster pump(s) Full flow filter for rich solvent Charcoal filter Control panel/motor startersThe 1-3gpm unit has the reflux system integral with the still column.This unit does not require reflux pumps or booster pumps.

Except for the gas contact tower the 1-3gpm, 3-10 gpm and 10-20 gpm plants arecomplete on one skid. The reboiler andaerial cooler are mounted off-skid on the20-40 gpm plant. The reboiler, still, andsolvent aerial cooler are off-skid on thelarger plants.

Select options to suit special needsThese plants are designed so that they canbe customized to meet your special needswhile maintaining fast delivery. These options include: Outlet scrubber and accessories Flash tank and accessories NACE accessories Instrument options Control panel options Reclaimer and accessories

Size 0 1 to 3 gpmSize 1 3 to 10 gpmSize 2 10 to 20 gpmSize 3 20 to 40 gpmSize 4 40 to 80 gpmSize 5 80 to 120 gpm

Standard Amine Plants

1-3 3-10 10-20 20-40 40-80 80-120gpm gpm gpm gpm gpm gpm

Contractor Tower

O.D. (in) 12.75 18 18 24 30 36

Length (ft) 42 52.5 52.5 52.5 52.5 52.5

Trays 20 20 20 20 20 20

Reboiler

O.D. (in) 24 36 60 72 96 120

Length (ft) 10 25 30 30 40 40

Duty (MMbtu/hr) .23 .75 1.25 2.75 5.5 8.6

Still Column

O.D. (in) 10.75 14 18 24 36 42

Length (ft) 23 48 50 50 50 50

Trays Pack 20 20 20 20 20

Reflux Accumulator

O.D. (in) 14 16 18 24 36 42

Length (ft) 6 5 7.5 7.5 7.5 52.5

Circulation Pump (2)

Rate (gpm) max 3 10 20 40 80 120

Horsepower 3 10 20 40 75 100

Reflux Pump (2)

Rate (gpm) max N/A .75 1.5 3 6 9

Horsepower N/A 1.0 1.0 1.0 1.0 1.0

Booster Pump

Rate (gpm) max N/A 10 20 40 80 120

Horsepower N/A 2.0 2.0 5 10 10

Reflux Condenser

Duty (MMbtu/hr) .15 0.525 1.05 2.10 4.20 6.30

Heat Exchanger

Duty (MMbtu/hr) .95 0.315 .63 1.26 2.52 3.78

Cooler

Duty (MMbtu/hr) .10 0.325 0.65 1.30 2.60 3.90

Charcoal Filter

Rate (gpm) 3 7.5 7.5 7.5 16 25