Reciprocating Cryogenic Pumps and Pump Installations for Hydrogen and Liquefied Natural Gas
CGA recently issued a new publication CGA P-96, Reciprocating Cryogenic Pumps and Pump Installations for Hydrogen and Liquefied Natural Gas. The scope of CGA P-96 covers pumps in liquid hydrogen and liquefied natural gas, but this article will focus on cryogenic liquid hydrogen.
Fuel cell electric vehicles (FCEVs) have on-board storage of high pressure gaseous hydrogen to power the vehicle fuel cell. The on-board gaseous hydrogen is taken from a hydrogen supply system. As the FCEV sizes and range increase, the gaseous hydrogen at the supply system must be stored in larger volumes and higher pressures to support the FCEV on-board storage. Other applications for gaseous hydrogen also require higher pressure and higher flow of gaseous hydrogen.
Many hydrogen supply systems use gas compressors to develop the higher pressure gaseous hydrogen storage. The compressor starts with lower-pressure gaseous hydrogen that is delivered to the supply system. However, a more efficient method to generate high pressure hydrogen is to use stored liquid hydrogen that is pumped through a positive displacement reciprocating pump, vaporized, and then stored at high pressure. A liquid pump and its associated equipment is less costly in terms of capital and operating costs, including electricity, than a gas compressor for the same flow and pressure. Delivered liquid hydrogen is also less costly than delivered gaseous hydrogen. A hydrogen supply system with a liquid pump takes up less room than a hydrogen supply system with a compressor.
Typically a hydrogen supply system has an installed spare pump or compressor. In this case, the cost and space differences become more pronounced.
CGA P-96 has been developed to provide details on selecting, installing, operating, and maintaining a liquid hydrogen reciprocating pump and its associated components for these applications. This standard supplements the material found in CGA H-5, Standard for Bulk Hydrogen Supply Systems. Those who are installing and operating hydrogen supply systems will find P-96 and H-5 useful, particularly for systems that use reciprocating pumps.