Development of a 5 t/d Hydrogen Liquefaction Unit

Hydrogen liquefaction plants are crucial for promoting the large-scale application of hydrogen. The technical features and development progress of the first 5 t/d hydrogen liquefaction unit in China are introduced. The hydrogen liquefaction unit directly uses hydrogen as a refrigerant, employing a dual-pressure Claude cycle with LN₂ precooling to liquefy hydrogen. The ortho-para hydrogen conversion process is facilitated through a combination of isothermal conversion at 80 K using nitrogen as the cooling medium, and continuous ortho-para conversion at temperatures below 80 K. It provides the advantages of high hydrogen liquefaction cycle efficiency, low energy consumption, and high ortho-para conversion efficiency. The main equipment includes two sets of cascade reciprocating oil-free hydrogen compressor units, a vacuum insulated cold box with a diameter of 3.2 meters and a length of 11 meters, and a liquid hydrogen storage tank. The main equipment in the vacuum insulated cold box includes four hydrogen turbine expanders, multi-stage low-temperature heat exchangers, multi-stage ortho-para hydrogen converters, and low-temperature control valves. Through the process optimization design, the hydrogen liquefaction capacity is 5 t/d, and the designed specific energy consumption is 11 kW·h/kg. At present, the hydrogen compressors and hydrogen liquefaction cold box have been manufactured. The system commissioning and operation will be carried out soon.