Cryogenic Pump Head Vacuum Insulation and Coolant Jacket
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Solution Overview
Problem
Cryogenic pumps face issues with cavitation due to vaporization of cryogenic liquids, leading to potential damage and hindering the pumping process, particularly during start-up, when handling liquids like hydrogen and helium.
Innovation Solution
A reciprocating cryogenic pump design featuring a pump head surrounded by vacuum insulation and an additional jacket for coolant fluid, which includes a degassing outlet and a filter to manage vaporized gases, reducing thermal exposure and enhancing insulation through the use of a vacuum-insulating jacket and a coolant chamber filled with liquid nitrogen for precooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thermal insulation is used on the pump head, then some thermal protection is provided, but cavitation still occurs during start-up due to insufficient insulation
Solution Approach 1:
The system performs preliminary cooling of the pump head using a coolant jacket before starting the pumping operation. This pre-cooling action reduces the temperature difference between the pump head and the cryogenic liquid, preventing vaporization and cavitation during the critical start-up phase.
Solution Approach 2:
A coolant fluid acts as an intermediary thermal medium between the environment and the pump head. The coolant absorbs heat from the pump head during cooling phase and releases it during heating phase, mediating the thermal interaction to maintain stable operating conditions and prevent cavitation.
2Object-affected harmful factors
If the pump head is heavily insulated to prevent vaporization, then cavitation is reduced, but the system becomes more complex and larger
Solution Approach 1:
The insulation system is nested in multiple layers: an inner vacuum insulation layer surrounds the pump head, while an outer coolant jacket surrounds the vacuum insulation. This nested structure provides enhanced thermal protection while efficiently using space and reducing overall system size compared to a single thick insulation layer.
Solution Approach 2:
The thermal insulation system combines two different insulation mechanisms: vacuum insulation (phase space barrier) and coolant fluid insulation (thermal mass buffer). This composite approach provides superior thermal protection performance while maintaining compact dimensions and manageable system complexity.
3Temperature
If vacuum insulation is added around the pump head, then thermal insulation is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The vacuum insulation chamber is nested within the coolant jacket structure, with the pump head positioned inside the vacuum chamber. This nested configuration allows modular assembly where each component can be manufactured separately and then assembled together, reducing overall manufacturing complexity despite the enhanced insulation requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively minimizes cavitation and maintains efficient pumping by reducing vaporization rates and maintaining thermal insulation, allowing for high-pressure transfer of cryogenic liquids without damage to the pump.
Implementation Method 1
a first jacket retaining vacuum insulation
Implementation Method 2
maintaining thermal insulation
Implementation Method 3
a chamber for receiving a coolant fluid, the second jacket having an inlet and an outlet for the coolant fluid
Implementation Method 4
enhancing insulation through the use of a vacuum-insulating jacket and a coolant chamber filled with liquid nitrogen for precooling
Implementation Method 5
a degassing outlet for evacuating vaporised cryogenic liquid from the reception chamber during cool down
Implementation Method 6
evacuating vaporized cryogenic liquid
Data Source
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AI summary
A reciprocating cryogenic pump 2 comprises a piston reciprocable within a pumping chamber 44. The pumping chamber 44 has an inlet suction valve 48 for cryogenic liquid to be pumped and an outlet 32 for high pressure cryogenic liquid. The inlet valve 48 for the cryogenic liquid communicates with a cryogenic liquid reception chamber 46 in the cold end or head 6 of the pump 2. The pump head 6 is at least partially surrounded by a first jacket 8 retaining primary vacuum insulation. The first jacket 8 is itself at least partly surrounded by a second jacket 10. The jacket 10 defines a chamber for the reception of a coolant fluid such as liquid nitrogen and the second jacket has an inlet 20 and an outlet 22 for the liquid nitrogen. The thermal insulation can be further enhanced by a trapped gas space 73 between the first jacket 8 and an inner sleeve 52, the latter defining with an outer sleeve 50 vacuum insulation for the pumping chamber 44.