Amine Plant Operation
The amine treating facility and amine equipment required for each plant can vary. An amine solution is employed by each plant for carbon dioxide removal and hydrogen sulfide removal through chemical reaction and absorption.
A filter coalesce is used to pre-treat the feed gas and remove any entrained liquids and/or solids from the feed stream. At this point, the gas will make its way through the contractor column. While in the contractor column, H2S and CO2 (acid gasses) are removed. This is referred to as the amine sweetening process.
Amine sweetened gas then proceeds through the Sweet Gas Cooler. There, it is cooled prior to making its way to the Overhead Scrubber. Any liquid that has become condensed by the exchanger will be removed by the scrubber prior to the sweet gas being processed downstream.
The lean amine is transferred into the top of the contractor and will then flow countercurrent to the gas via trays. This is where contact with the gas will take place. At this point, the rich amine will be collected within the tower bottom. A level transmitter is utilized for maintaining the level while a control valve dumps the rich amine into a flash tank.
Hydrocarbon gasses that are entrained in the amine will be flashed off in the flash tank and will then be directed for disposal purposes. If there is any hydrocarbon liquid present, it will then rise to the top of the amine solution within the flash tank. There, it can be removed through an internal collection container and then disposed of through drainage.
The rich amine will then progress through a filtration process in the flash tank. Part of the rich amine will be directed through a carbon filter for the adsorption of degraded products and hydrocarbons from the amine. Any solid contaminants that may remain will then be removed in the particulate filter.
At this point, the rich amine will continue on to the Rich/Lean Exchanger. There, it will be heated. The amine will then enter the Amine Still Tower and flow downward through the trays where it will come into contact with steam, which will strip the gases from the amine. A draw off pan is then used for collecting the amine. The amine will then be gravity fed into a horizontal thermo siphon reboiler using direct-fired reboilers. From this point, it will flow into the reboiler bottom. The solution will then be heated in the reboiler until part of the solution is vaporized. The resulting steam mixture is then piped into the still column sump beneath the trays. As the steam makes its way up the trays, acid gas components will be stripped from the amine.
Water within the vapor that exits the still top is condensed within the Reflux Condenser. It will then collect within the Reflux Accumulator. At this point, the water is returned to the tower top utilizing the Still Reflux Pumps. There, it will be blended with the rich amine or still feed liquid. Vapor that is not condensed within the Reflux Condenser will be primarily comprised of hydrogen sulfide, water vapor, and carbon dioxide. The acid gasses will then flow through the system backpressure valve to reach disposal.
Amine remaining in the still column sump is referred to as regenerated. At this point, it is called ‘lean amine’ and is gravity fed through the Rich/Lean Exchanger to the Booster Pumps.
The lean amine will then be cooled further within the Lean Amine Cooler or air-fin and finally delivered to the Solution Pumps. The pump will increase pressure in the amine to a level sufficient enough for it to enter the top of the Amine Contractor and begin the amine treating process once again.
For Blue Sky Midstream's complete Amine Plant Operations Manual, Click Here.