A liquefaction system produces a liquid product stream from a warm gas feed stream. The feed gas is cooled from ambient temperature to final product temperature by work expansion of a recycle stream of the same composition as the feed gas. JT expansion and cooling with an external refrigerant may also be used to provide refrigeration. A complete liquefaction system includes recycle compression and oil removal; a cold box containing valves, heat exchangers, adsorbers, and expanders; product storage and distribution; and controls.
The net refrigeration requirements for a liquefier are much higher than for a refrigerator of comparable recycle flow. Therefore, a liquefier will have higher expander power and will often include more expanders to improve process efficiency. Use of an external refrigerant is quite common in liquefier applications since it will substantially reduce the recycle flow requirements. For instance, liquid nitrogen can be used to provide about 75% of the refrigeration required by a helium liquefier, resulting in elimination of one or more turbines and downsizing of compressors.
The feed to a liquefier may be produced by upstream equipment in a production facility or may be recovered from various sources in other applications. In either case, it is typical for the feed stream to contain minor amounts of contamination which will be continually introduced to the system. Therefore a liquefier will often incorporate dual adsorber beds at one or more temperature levels, depending upon the application and the impurities to be removed.
Cryo Technologies provides helium liquefiers in the range of 25 l/hr to over 2500 l/hr. Refrigeration is provided by turbines, expansion engines, or both, depending upon the application. Units can be designed with or without liquid nitrogen precooling depending upon the availability and cost of liquid nitrogen. Adsorbers are typically provided at the 80K and 20K levels, with production liquefiers usually incorporating dual feed adsorbers at both temperature levels as well as one or more recycle adsorbers depending upon the application. Computer control is standard, and systems are automated in accordance with customer preferences, including fully automatic startup and shutdown where applicable.
Our helium liquefier designs incorporate many years of experience in industrial production applications. We are familiar with the unique dynamic behavior of helium storage tanks and transport containers and account for this in our designs, so that our systems are stable and efficient across a wide range of cold end conditions. A Cryo Technologies helium liquefier is customized in accordance with the specific requirements of the customer, taking into account the unique operating requirements and economic constraints of each application. We will provide the liquefier that you need, not the one we designed for another customer.
Cryo Technologies also supplies nitrogen liquefiers for specific applications. We have incorporated nitrogen liquefaction services into cryogenic purifiers to provide cooling to an associated helium liquefier and to meet other facility requirements for liquid nitrogen. We will also retrofit or customize an existing nitrogen liquefier to increase capacity or improve operation.
The helium liquefier pictured is a good example of our capabilities. This unit was a new design, twice the size of our previous largest system. We started with a clean sheet of paper and delivered the system 49 weeks later. Three weeks after that we had met our performance guarantee. We won this project on a competitive bid in which we were the lowest price, the best efficiency, and the shortest schedule.