PTX Technologies Inc. has developed refrigeration/liquefication technology for the LNG market at the Talbot Lake LNG Project, located in northern Alberta. The technology is based on modified aqua-ammonia absorption technology.
Aqua-ammonia, a mixture of water and ammonia, is pumped to pressure then heated to release ammonia vapour from the solution. The ammonia is then further concentrated through distillation and condensing to produce an ammonia refrigerant.
The new technology is capable of providing ammonia refrigerant chilling down to -75°c at a chiller operating pressure of 5 kPa absolute.
gasworld spoke to Colin Nikiforuk, President and CEO of PTX Technologies to find out more about the technology, “For LNG production the refrigeration of the natural gas is conducted at higher pressures than conventional liquefication process.”
“The chilled high-pressure gas is flashed to a lower pressure, producing roughly half of the product into LNG and the remainder as a cold recycle stream which provides a portion of the refrigeration, in addition to the refrigeration provided by PTX’s modified aqua-ammonia absorption system,” Nikiforuk continued.
The new refrigeration process reduces the scope of overall mechanical rotating equipment required. There are no cryogenic rotating equipment components required in the process, only static equipment such as heat exchangers, pressure vessels and piping are exposed to cryogenic cold temperatures.
The technology is suited for the small to large-scale markets with an estimated upper end of processing train estimated to be approximately 100 MMscfd of capacity.
“What is different with PTX’s version of the technology is we have developed innovate patented methods to create very low sub-atmospheric pressures (5 kPa absolute, sea level atmospheric pressure is roughly 100kPa absolute) and multi-stages that result in much lower ammonia chiller operating temperatures than conventional refrigeration systems might achieve,” Nikiforuk told gasworld.
“This results in much broader industrial application due to the lower chiller operating pressures and therefore lower refrigeration chiller operating temperature,” Nikiforuk said.
The refrigeration technology is thermally driven providing opportunities to co-locate at industrial locations with waste heat and a gas supply. Co-locating would reduce required capital and operating cost for LNG production, an example of a potential location would be a small to mid-scale LNG facility beside a large natural gas fired power generation facility.
Nikiforuk told gasworld, “It is important to achieve implementation of the technology at the Talbot Lake LNG facility or alternate project in the near term to advance the technology to the next stage of commercial application.”
“PTX plans to licence the use of the technology with select equipment suppliers/fabricators or end use customers depending on application specifics,” Nikiforuk continued.
Liquefaction of CO2 is another application where PTX’s thermally drive aqua-ammonia absorption refrigeration could be implemented opposed to a conventional mechanical ammonia refrigeration system.