NEWS
Recovery and Utilization of Helium for Cryogenic Valve Cryogenic Test
Release time:
2023-02-18 10:03
During the low temperature performance test of the valve, helium in the cylinder passes through the high pressure pipeline and enters the valve chamber to be tested. After the test, the cryogenic helium in the valve chamber is recovered into the cylinder through the original pressure pipeline, and the process of helium utilization and recovery is completed. Valve cryogenic test requires that the test valve be cooled in the refrigerant for a certain period of time, enough to condensate or solidify most of the impurity gases, so as to improve the purity of helium. Therefore, the purity of helium will not decrease significantly after cryogenic test, which meets the conditions of recovery and reuse.
1. Overview
Low temperature valves are widely used in the fields of air separation, LNG and ethylene Petrochemical because their service temperature is below - 29 C. The inspection and test of cryogenic valves need to be carried out in low temperature environment. According to the test temperature requirements, the cryogenic refrigerant of the cooling valve can be dry ice, liquid nitrogen or mixed with alcohol to achieve the appropriate temperature. When the test temperature is higher than - 110 C, nitrogen can be used as test medium, which is not only clean and pollution-free, but also economical. When the test temperature is below - 110 C, helium can be selected as the test medium.
Because of the high price of helium, the test cost is high. At the price of 1,000 yuan per bottle of high purity helium, the price of helium is as high as 200 yuan/m3 (standard condition). Taking the 12 in. - Class 900 ball valve commonly used in LNG gasification station as an example, at least 60 m3 of helium is consumed in each cryogenic test. Through reasonable design, the helium in the valve chamber can be recovered after the test, which can save a lot of cost, reduce the test cost and enhance the market competitiveness of the product.
2. Low Temperature Test
Cryogenic valve cryogenic test is an important part of cryogenic valve performance test, and it is an indispensable link to test its performance. Standards for cryogenic test of cryogenic valves include GB/T 24925, BS6364, MESC SPE 77/200, MSS SP-134, etc. BS6364 is widely accepted, and MSESC SPE 77/200 is more operable as Shell's enterprise standard.
The performance tests of cryogenic valves include cryogenic operation test, sealing performance test, micro-leakage test and middle chamber pressure relief test.
(1) Low-temperature action test switch valve and record the moment many times.
(2) Sealing performance test of valve disc.
(3) Microleakage test was used to test the sealing performance of filler and flange joint.
(4) The middle chamber pressure relief test tests the ability of upstream pressure relief when the pressure in the middle chamber of the ball valve rises.
In valve test, the volume of helium required for cryogenic operation test and micro-leakage test is at least equal to the sum of the volume of the valve chamber when the valve is opened and the volume of the lengthened stem cavity when the valve is opened at the test temperature and pressure.
Cryogenic Valve,recycle
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