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Amine Pump RecirculationApplication Discussion

AD124June 15, 2003

The purpose of this process is to remove Acid Gases (H2S, CO2, COS)from a raw

natural gas stream to make the gas composition meet Sales Gas requirements. TheAmine Treating Unit removes CO2 and H2S from sour gas and hydrocarbon streams inthe Amine Contactor. Counter flowing the amine solution hydrocarbon stream absorbsthe acid contaminants. The stripped gas is removed overhead, and the amine is sent tothe regenerator. In the regenerator, the acidic components are stripped by heat andreboiling action and disposed of, and the amine is recycled.

The sour gas streams enter the bottom of the Amine Contactor. The cooled lean amineenters the top of the contactor column. The sour gas flows upward counter-current to thelean amine solution. An acid-gas-rich-amine solution leaves the bottom of the column atan elevated temperature, due to the exothermic absorption reaction. The sweet gas,after absorption of H2S by the amine solution, flows overhead from the Amine Contactor.

There are two severe service valves associated with the Amine Treatment process. Thelevel valve controls the level in the tower as to not flood the overhead section or allowthe level to drop too low which causes inefficient absorption as the gas stream flowsfrom bottom to top of the tower. The other valve is the liquid pump bypass valve, whichis used as a minimum flow bypass valve to protect the pump. This valve may not existdue to a variable speed pump driver.

The fluid is a water/amine solution that should not have sour components remaining in itbut some specifications require this valve to meet NACE guidelines. For the purposes offluid flow the valve acts like water so expect cavitation and related problems.

Typically, inlet pressure range from 500 PSI to 1000 PSI with outlet pressures around

Minimum Flow

Pump Bypass

Lean

Liquid

Flow

Control

Sweet Gas

Sour Gas

Rich

Liquid

Level

Letdown

Contactor

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