Cryogenic Pump Hydraulic Drive for LNG Delivery
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Solution Overview
Problem
Existing cryogenic pump systems for delivering liquefied natural gas (LNG) to internal combustion engines face challenges in efficiently maintaining cryogenic temperatures and preventing premature evaporation, requiring specialized storage tanks and delivery systems.
Innovation Solution
A cryogenic pump with a hydraulic drive system, comprising a pump assembly submerged in the LNG tank and a drive assembly with spool valves, tappet bores, and pushrod springs, which uses high-pressure hydraulic fluid to drive the pumping elements and maintain the LNG in a liquid state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a cryogenic pump is used to deliver LNG from a cryogenic tank, then the LNG can be transported to the internal combustion engine, but the system complexity increases due to the need for specialized storage tanks and delivery systems
Solution Approach 1:
The pump assembly is merged with the drive assembly into a single integrated cryogenic pump unit. The drive assembly includes spool valves, tappet bores, and pushrod springs that are directly coupled to the pump assembly, eliminating the need for separate drive mechanisms and reducing overall system complexity while maintaining LNG delivery capability
Solution Approach 2:
The hydraulic fluid in the drive assembly serves multiple functions: it actuates the spool valves to control fluid flow, provides hydraulic pressure to move the tappets, and absorbs shock loads through the spring mechanism. This multi-functional use of hydraulic fluid reduces the need for separate control systems and components
2Temperature
If the pump assembly is submersed within the cryogenic tank, then the cryogenic temperatures are maintained within the tank, but the drive assembly requires a complex hydraulic system to operate the pump
Solution Approach 1:
The drive assembly uses a hydraulic system with spool valves and tappet bores to transmit power to the pump assembly. High-pressure hydraulic fluid is directed through the spool valves into the tappet bores, where it actuates the tappets and pushrod springs to drive the pump. This hydraulic mechanism provides reliable power transmission while allowing the pump assembly to remain submersed in the cryogenic tank
Solution Approach 2:
The hydraulic fluid acts as an intermediary between the power source and the pump assembly. It transmits mechanical energy through the spool valves and tappet bores to drive the pump, while allowing thermal isolation between the warm drive assembly and the cold pump assembly submerged in the cryogenic tank
3Reliability
If the pump assembly is designed to maintain liquid state of LNG, then premature evaporation is prevented, but the energy consumption increases to maintain cryogenic conditions
Solution Approach 1:
The pump assembly is designed to be submersed directly in the cryogenic tank, allowing it to utilize the ambient cryogenic temperature of the tank for cooling during operation. The hydraulic drive system provides the necessary mechanical work while the surrounding cryogenic environment provides passive cooling, reducing the need for active energy-intensive cooling systems
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 system effectively delivers LNG from the cryogenic tank to the internal combustion engine while maintaining the liquid state, ensuring efficient energy conversion and reducing the risk of premature evaporation.
Implementation Method 1
hydraulic fluid moves a tappet slidably disposed in the tappet bore
Implementation Method 2
Spool valves are then actuated to direct hydraulic fluid from the hydraulic fluid inlet to a tappet bore
Implementation Method 3
The pushrods are operatively associated with a pushrod spring in the spring housing to normally urge the first end into the tappet bore
Implementation Method 4
Spool valves are then actuated to direct hydraulic fluid from the hydraulic fluid inlet to a tappet bore
Implementation Method 5
The cryogenic pump may have a pump assembly submersed within a cryogenic tank storing liquefied natural gas
Implementation Method 6
a drive assembly configured to hydraulically drive the pump assembly to pump the liquefied natural gas from the tank
Data Source
AI summary
A cryogenic pump for pumping liquefied natural gas (LNG) from a cryogenic tank storing LNG includes a drive assembly and a pump assembly disposed along a pump axis. The drive assembly includes a spool housing having a plurality of spool valves arranged around the pump axis, a tappet housing having a plurality of tappet bores with slidable tappets arranged around the pump axis, and spring housing including a plurality of movably disposed pushrods urged upward by a plurality of associated pushrod springs. Hydraulic fluid received by a hydraulic fluid inlet in the drive assembly is directed by the spool valves to the tappet bores to move the tappets downward against the pushrods. To collect the hydraulic fluid, the lowermost spring housing also includes a collection cavity formed therein that can return the hydraulic fluid to a hydraulic fluid outlet.