Study of Polythermal Ortho-Para Hydrogen Conversion Process and its Industrial Implementation

The results of theoretical and experimental studies of polythermal ortho-para hydrogen conversion process, which allowed identification of several important factors that affect the conversion apparatus operation, are presented. The experiments were conducted on a 20 kg/h pilot hydrogen liquefaction plant. Comparison of the obtained data showed good agreement between theoretical and experimental results throughout the studied area. It was shown that the ortho-para conversion process could be continuous in the 63-34 K temperature range with attainment of equilibrium parahydrogen concentration of 90%. Based on the experimental data, the low-temperature units of the industrial high-pressure hydrogen liquefier were updated, which made it possible to produce 500 kg of liquid parahydrogen per hour and to solve the task of doubling the production capacity of the existing plant.