2006, Volume 9, Issue 17+18
Acquisition System for the Liquid Helium L5 Plant
National Institute of Cryogenics & Isotopic Technologies, Rm. Valcea
The technology of low temperature at the beginning of this century, developed for the production of oxygen, nitrogen and rare gases, was the basis for settings up the cryogenic technology in all the companies with these activity fields. The cryogenics section of today comprises engineering and construction of cryogenic plants for: science, research and development; space technology; nuclear power technique. An important section in this field is the helium liquefier Type L5. This fully automatic cryoliqufier operates for purification, liquefaction as well as reliquefaction of helium-gas, evaporated in cryostat systems. This helium plant consists mainly of cold box with aluminium heat exchangers, two gas-lubricated turbo-expanders, instrumentation and a programmable controller as well an oil-injected screw-compressor. Cold helium with 4.5K is transferred in a special vacuum and super insulated transfer line to the tank. In liquefaction mode without LN2-precooling the performance data of this plant is 5l/hour at 4.5 Kelvin.
In the paper are presented the work out to design and developed a performant liquid helium delivery system according with all the basic equipment and accessories consist the L5 type, helium liquefactor.
The process software of LINDE L5 installation was updated and adapted to our technical conditions from our cryogenic laboratory. Therefore the new programme, based on Lab-View derived from the functions command protocol, allowed a performant control on the technological process and induce several determinations on the performance of the process as following:
• Verification of the theoretical models of the cryogenic cycle energetic dimensions;
• Increasing thermodynamically performances of different components of the cryogenic cycle by remodelling the geometrical flowing zones, based on gas dynamics studies, in concordance with the termophysics characteristics of the gas;
Study of the dynamic comportment of the installation by the transitory process influence evaluation.
Acquisition system, liquid helium.
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