Hydrogen-Free Liquid-Helium Recovery Plants: The Solution for Low-Temperature Flow Impedance Blocking

Gabal, M. ; Arauzo, A. (Universidad de Zaragoza) ; Camón, A. (Universidad de Zaragoza) ; Castrillo, M. ; Guerrero, E. ; Lozano, M.P. ; Pina, M.P. (Universidad de Zaragoza) ; Sesé, J. (Universidad de Zaragoza) ; Spagna, S. ; Diederichs, J. ; Rayner, G. ; Sloan, J. ; Galli, F. ; Van, Der Geest ; Haberstroh, C. ; Dittmar, N. ; Oca, A. ; Grau, F. ; Fernandes, A. ; Rillo, C. (Universidad de Zaragoza)

Resumen: The blocking of fine-capillary tubes used as flow impedances in He4 evaporation cryostats to achieve temperatures below 4.2 K is generally attributed to nitrogen or air impurities entering these tubes from the main bath. The failure of even the most rigorous low-temperature laboratory best practices aimed at eliminating the problem by maintaining the cleanliness of the helium bath and preventing impurities from entering the capillary tubes suggests that a different cause is responsible for the inexplicable reduction of impedance flow. Many low-temperature research laboratories around the world have suffered this nuisance at a considerable financial cost due to the fact that the affected systems have to be warmed to room temperature in order to recover their normal low-temperature operation performance. Here, we propose an underlying physical mechanism responsible for the blockages based upon the freezing of molecular H2 traces present in the liquid-helium bath. Solid H2 accumulates at the impedance low-pressure side, and, after some time, it produces a total impedance blockage. The presence of H2 traces is unavoidable due its occurrence in the natural gas wells where helium is harvested, forcing gas suppliers to specify a lower bound for impurity levels at about 100 ppb even in high-grade helium. In this paper, we present a simple apparatus to detect hydrogen traces present in liquid helium and easily check the quality of the liquid. Finally, we propose a solution to eliminate the hydrogen impurities in small- and large-scale helium recovery plants. The solution has been implemented in several laboratories that previously experienced a chronic occurrence of blocking, eliminating similar occurrences for more than one year.

Idioma: Inglés

DOI: 10.1103/PhysRevApplied.6.024017

Año: 2016

Publicado en: Physical review applied 6, 2 (2016), 024017 [11 pp]
ISSN: 2331-7019

Factor impacto JCR: 4.808 (2016)

Categ. JCR: PHYSICS, APPLIED rank: 21 / 147 = 0.143 (2016) - Q1 - T1

Factor impacto SCIMAGO: 2.448 - Physics and Astronomy (miscellaneous) (Q1)

Financiación: info:eu-repo/grantAgreement/ES/MINECO/IPT-2012-0442-420000
Financiación: info:eu-repo/grantAgreement/ES/MINECO/MAT2015-64083-R

Tipo y forma: Artículo (Versión definitiva)

Área (Departamento): Área Ingeniería Química (Dpto. Ing.Quím.Tecnol.Med.Amb.)
Área (Departamento): Servicios. Div.Caract.Físi.Quí (Serv.Gral. Apoyo Investigación)
Área (Departamento): Área Física Materia Condensada (Dpto. Física Materia Condensa.)