Osmosis Membrane/Carbon Dioxide Separation Plant


Client:

Quicksilver Resources

Location:

Michigan

Augusta Project Number:

193100

Project Value:

$4,824,392 M

Contract Amount:

Half of Project Value

Joint Venture:

Partnering with EMS

Status:

Front end engineering finished/ beginning design

Description:

Augusta Engineering is currently handling front end engineering design and evaluation of equipment for purchase and/ or rework for the new operating conditions of a gas treatment facility re-design, which will increase the Wilderness Chester plant’s throughput and treating capability.

Currently the membrane osmosis plant treats a natural gas stream with an inlet carbon dioxide content of up to 20 percent. The outlet sales gas stream is treated to levels of two percent or less carbon dioxide. The existing equipment will handle an inlet stream of approximately 30 MMscfd with a pipeline pressure of 1000-1100 Psig. The goal of the re-design is to increase the volume to 100 MMscfd, with the same pipeline pressure range.

In the membrane osmosis process, gas is passed through a number of pre-treatment filters to remove all solids and moisture, before entering the membrane osmosis area. Here, it passes through a series of membrane cells which allow the carbon dioxide to permeate through to a nearly atmospheric pressure side branch, while the natural gas components pass through the run of the vessel relatively freely. The permeate gas, which still contains a significant amount of methane, is re-compressed to pipeline pressure and passes through a second stage of osmosis separation. After this second treatment, the permeate gas is highly concentrated carbon dioxide, while almost all the natural gas has been cleaned and is now pipeline grade fuel.

In re-engineering this plant, nearly every component had to be evaluated for application at the increased flow rates. The inlet gas separation and filtration was not adequate for the increased flow, and was replaced with new skid mounted cleaning components. Plant gas piping had to be re-sized to hold flow velocities in the range of 40-50 feet per second or less. This was necessary both to minimize pressure drops and to avoid noise problems caused by excessive gas velocity.

Increasing the operating pressure of the permeate stream will allow a significant savings in the compression requirement. The current operation has four 1200 Bhp compressors installed. Originally, estimates for expansion called for an addition of up to 4500 HP. With the higher pressure available to the compressor suction, the necessary volumes can be handled with an addition of only 1200 HP.

An expanded emergency shutdown system was designed to provide a balance of station blowdown time together with a controlled depressurization rate to protect the osmosis sections. This station redesign has provided the customer with an optimized expansion giving reliability and quality control on the product gas, while also minimizing the cost of the new and reworked equipment.