In what researchers claim is a “step-change in efficiency,” ExxonMobil Corp. has unveiled an in-line technology to dehydrate natural gas, which could reduce costs for pipeline transport in land-based and offshore operations.
The cMist technology, developed and field-tested by ExxonMobil, removes water vapor present during natural gas production. The absorption system deployed inside pipelines could replace the need for conventional dehydration tower technology, Houston researchers said.
“Removing water vapor through the use of dehydration technology, typically accomplished using large and expensive dehydration towers, reduces corrosion and equipment interference helping to ensure the safe and efficient transport of natural gas through the supply infrastructure and ultimately to consumers,” according to the upstream research arm.
The technology is said to reduce the size, weight and cost of dehydration, which could result in a 70% reduction in the surface footprint. The overall dehydration system’s weight was reduced by half using cMist, which could be a big benefit in offshore applications.
“By leveraging our industry-leading experience with upstream applications, our researchers were able to create this advanced natural gas dehydration technology, which represents a step-change in operational efficiency and a significant reduction in footprint,” said Tom Schuessler, president of ExxonMobil Upstream Research Co.
ExxonMobil long has been a technology leader among global oil and gas operators. Its annual Outlook for Energy, A View to 2040, which was most recently published in December, forecast natural gas resource estimates to continue to increase because of technology breakthroughs.
Gas hydrate technology is a big driver for many operators. Gas hydrates, which can accumulate in the pipeline, may choke or block the pipe and damage operations. When large gas volumes are transported via a pipeline, dehydration is considered the most efficient way to prevent hydrate formation. Dehydration is considered essential for gas transported from the offshore to avoid dangers associated with transporting/processing wet gas, including corrosion, water condensation and plugs created by ice or gas hydrates.
Gas dehydration in the oil and gas industry generally falls into two groups. Absorption, the most widely used method, dehydrates using liquid media, while adsorption relies on solid media.
ExxonMobil’s cMist technology uses a proprietary droplet generator to break up conventional solvent into tiny droplets that become dispersed in the gas flow, thereby increasing the surface area for absorbing water from the gas. That process is followed by an inline separator that coalesces the water-rich glycol droplets and moves them to the outside wall of the pipe to separate them from the dehydrated natural gas. The water-rich glycol is regenerated using a conventional system and is sent back to the droplet generator to be used again. The droplet generator uses the energy from the flowing natural gas to create droplets of the “right size,” the researchers said.
ExxonMobil has licensed cMIST technology to the Chemtech division of Sulzer, a separation technology specialist, to deploy across the oil and gas industry. Sulzer, headquartered in Switzerland, specializes in pumping solutions, rotating equipment maintenance and services, along with separation, reaction and mixing technology.
The cMist technology uses Sulzer’s patented HiPer inline separator.
The “unique technology” allows “for much needed reductions in capital expenditures for both greenfield projects and existing facilities seeking brownfield debottlenecking opportunities,” said Chemtech President Torsten Wintergerste.
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