New Gas Process Means Cost Savings

18 May 2015

Costain has developed a process which integrates natural gas liquids (NGL) extraction from natural gas with nitrogen removal, which gives significant cost savings.

Natural gas conditioning often requires the extraction of heavier hydrocarbons to meet sales gas specifications before it is piped to end-user markets. In addition, the increased recovery of these heavier hydrocarbons can be justified if their value as liquid products exceeds their value as sales gas. Cryogenic turboexpander technology is the optimal processing technology to achieve high recovery levels of propane and especially ethane.

Costain has patented process technology which results in these gas processing applications incurring lower capital and operating costs.

The sales gas produced by natural gas liquids (NGL) extraction may contain excessive nitrogen which, as an inert, reduces heating value. Nitrogen is typically removed by cryogenic technology as this is the only way to produce pure nitrogen for disposal, and to achieve high hydrocarbon recoveries. Costain has extensive experience in cryogenic nitrogen removal having installed a number of major plants around the world.

For NGL extraction and nitrogen rejection, separate plants are normally used. However, warming the processed gas to ambient temperature, only to then cool it again for further processing, can incur significant energy and cost penalties.

“Not only does this increase operating costs, the configuration of the plant machinery for sales gas compression is often complex and costly,” said Adrian Finn, Process Technology Manager.

Costain has used existing, established patented processes to develop a process which efficiently integrates natural gas liquids extraction technology with nitrogen removal. Modern process simulation techniques enable both plant design and process control system design to be optimised.

Costain’s innovative integrated process has less plant items, smaller heat exchangers, lower power consumption and a simpler machinery configuration, which significantly reduces capital and operating costs.

“This integrated process technology incurs lower capital and operating costs. By amalgamating multiple existing patents and using proven gas processing technology, process equipment is conventional and plant operation is comparable with conventional gas processing technology. Cost savings of over 10% are feasible,” said Adrian.

The use of Costain’s existing intellectual property means this licensed process is immediately available for integrated gas conditioning projects for recovery of NGL and rejection of nitrogen from natural gas.

“Costain’s project and operating experience, and extensive technical knowledge in the design of cryogenic plants, ensures plant performance will be efficient and reliable,” said Adrian.

For more information about this innovation, contact Adrian Finn at




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