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Prototype of small-scale LNG production device funded DOE providing $350,000 to Cryenco of Denver for liquefier expected to be economic at volumes of 1-4 million cubic feet per day of natural gas Petroleum News Alaska Staff
The U.S. Department of Energy is co-funding the construction and testing of a portable refrigerator which uses sound waves to cool natural gas to the point where it liquefies.
The department said the device could help producers market gas that is often wasted or left behind in today’s oil fields.
The department will provide $350,000 to Cryenco Inc., a Denver-based company that specializes in cryogenic vessels, to develop a small-scale liquefied natural gas production device. Cryenco will contribute $200,000 to the effort.
Sound waves drive refrigeration The natural gas liquefier will operate on a novel concept that burns natural gas to generate sound waves that, in turn, drive natural gas refrigerators.
Conventional production of LNG requires compression and cooling, and typically has required sophisticated large-scale refrigeration machinery to be cost efficient, with modern plants costing a billion dollars or more, DOE said, and requiring volumes of upwards of a billion cubic feet of gas per day to be economic.
Currently, no commercially available, economical, small-scale LNG production technology exists for remote gas fields.
Cryenco’s new LNG process, at commercial scales, is expected to be economical at rates of 1 million to 4 million cubic feet per day and cost significantly less than traditional refrigeration processes of similar scale.
No moving parts, minimal electric power Although the technology has the name ThermoAcoustic Stirling Heat Engine and Refrigeration, Tasher for short, its basic process is relatively simple. There are no moving parts and only minimal electric power requirements. The device is expected to be maintenance-free, environmentally benign and boast operation efficiencies approaching conventional large-scale LNG plants.
With the Energy Department’s funding, Cryenco will build a 500 gallon per day prototype model of a Tasher unit at its principal cryogenic manufacturing plant in Denver.
The liquefier will have three steps. First, some of the natural gas will be burned to provide a power source. Second, a thermoacoustic Stirling heat engine will convert the thermal power into acoustic power (sound waves) by alternately compressing and decompressing helium. Third, refrigerators will convert the acoustic power to draw off heat from a second supply of natural gas. The prototype model will use three refrigerators in series, each taking the gas down to a cooler level until it liquefies. About 70 percent of the initial gas feed is converted to LNG while 30 percent will be burned to generate the acoustic power.
DOE’s Los Alamos National Laboratory will provide technical assistance in scaling up a laboratory model. Los Alamos first developed the novel cryogenic concept in early laboratory work with Cryenco and others, in part with the support of DOE’s Office of Fossil Energy program.
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