Integrated Fill and Vent Assembly for Cryogenic Storage Tanks
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Solution Overview
Problem
Conventional storage tanks for cryogenic liquids have separate pipes for filling and venting, leading to increased heat leak and inefficiency in refilling, as the fill line is not suitable for venting and cannot effectively condense vapor, resulting in unnecessary vaporization of cryogenic liquid during the refilling process.
Innovation Solution
A combined fill and vent assembly with a conduit and by-pass line that allows for both filling and venting, featuring a check valve and a pressure relief valve, where vapor is vented through the fill line to pre-cool it before refilling, reducing heat leak and extending storage time by minimizing vaporization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate pipes are used for filling and venting, then safety is improved through dedicated vent lines with pressure relief valves, but heat leak increases due to additional thermal conduction paths through the insulating space
Solution Approach 1:
The patent combines the fill pipe and vent pipe into a single integrated conduit that serves both functions. The conduit includes a check valve to prevent reverse flow during filling and a pressure relief valve to provide venting capability, eliminating the need for separate pipes and reducing thermal conduction paths through the insulation.
Solution Approach 2:
The single conduit performs multiple functions: it acts as both a fill line for introducing cryogenic liquid and a vent line for releasing vapor. The check valve ensures one-way flow during filling while the pressure relief valve provides safety venting, making the conduit a multi-functional component that reduces overall system complexity and heat leak.
2Loss of energy
If the fill line is used for venting, then heat leak is reduced by eliminating separate vent pipes, but the check valve prevents effective vapor condensation during refilling
Solution Approach 1:
The system dynamically switches between filling and venting modes based on operational requirements. During filling, the check valve opens to allow liquid flow while closing to prevent vapor backflow. During venting, the pressure relief valve opens to release vapor while the check valve closes to maintain liquid flow directionality. This dynamic operation allows the same conduit to efficiently perform both functions without the limitations of conventional designs.
3Reliability
If conventional fill pipes with check valves are used, then cryogenic liquid leakage is prevented, but the fill line becomes unsuitable for venting operations
Solution Approach 1:
The patent merges the filling and venting functions into a single conduit system. The check valve maintains its leak-prevention capability while the integrated pressure relief valve provides venting functionality. This combination allows the fill line to adapt to both filling and venting operations without compromising either function.
Solution Approach 2:
The conduit is designed as a universal component that can perform both filling and venting operations. The check valve ensures reliable liquid flow control during filling, while the pressure relief valve enables safe venting during operations requiring vapor release. This multi-functionality eliminates the need for separate dedicated pipes for each function.
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 integrated fill and vent system reduces heat transfer paths, allows for efficient vapor condensation during refilling, and simplifies the piping arrangement, thereby reducing manufacturing costs and the likelihood of leaks, while maintaining safety features to prevent cryogenic liquid leakage.
Implementation Method 1
A check valve is disposed in the conduit, allowing flow only in the direction of filling the cryogen space with cryogenic liquid from the receptacle
Implementation Method 2
a valve disposed in the by-pass line that is operable to an open position wherein fluid is allowed to flow through the by-pass line and a closed position wherein fluid is blocked from flowing through the by-pass line
Implementation Method 3
The inner vessel defines the cryogen space in which a cryogenic liquid can be stored. Such an arrangement reduces the transfer of heat from the ambient environment to the cryogenic liquid stored within the cryogen space
Implementation Method 4
If the vapor pressure in the cryogen space rises above the set point of the pressure relief valve, vapor is vented to atmosphere
Data Source
AI summary
A storage tank defines a cryogen space for storing a cryogenic liquid. The storage tank comprises a combined fill and vent assembly, which comprises a conduit having a first end with an opening disposed within an upper part of the cryogen space, and a second end outside of the cryogen space that is connected to a receptacle, to which a re-filling nozzle can be attached. A check valve disposed in the conduit allows flow only in the direction of filling the cryogen space with cryogenic liquid from the receptacle. A by-pass line is provided around the check valve with a valve disposed in the by-pass line that is operable to open or close to control flow through the by-pass line. The method comprises attaching a re-filling nozzle to the receptacle and opening the by-pass valve to vent vapor from the cryogen space to reduce vapor pressure therein and to cool the conduit, receptacle, re-filling nozzle, and fill line. After venting the storage tank, the by-pass valve is closed, and the storage tank can be re-filled through the receptacle and conduit.