Redundant Isolation Valve for Cryogenic Tank Pump
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Solution Overview
Problem
Existing isolation mechanisms for cryogenic storage tanks lack redundancy and proper venting and purging methods, leading to potential loss of fluid, safety concerns, and introduction of impurities during pump removal, with unreliable actuation mechanisms and precarious sealing.
Innovation Solution
A redundant isolation mechanism with a primary and secondary valve member, actuated by hollow tubes for safe depressurization and purging, ensuring fail-closed positions for safe operation, and allowing external manual or pneumatic actuation for emergency situations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single isolation valve with manual actuation is used, then the device complexity is reduced, but the reliability of isolation is compromised
Solution Approach 1:
The isolation mechanism is segmented into two separate valve members (first and second isolation valve members) that operate independently. Each valve member provides a separate isolation path, so that if one valve fails or leaks, the other continues to provide isolation. This segmentation increases reliability without requiring a single complex redundant system.
Solution Approach 2:
A cable connects the external actuator to the first valve member, serving as an intermediary that transmits actuation force through the tank wall. This allows reliable external control of the isolation valves while maintaining the simplicity of manual actuation from outside the tank.
2Loss of substance
If the pump is removed without proper isolation and purging, then the operation time is reduced, but fluid loss and safety risks increase
Solution Approach 1:
The system performs preliminary actions before pump removal by automatically closing both isolation valve members when the pump is raised, and providing purging capability through the hollow actuator tube. This preliminary isolation and purging prevents fluid loss and safety hazards, while the automated valve closure reduces the time required compared to manual procedures.
Solution Approach 2:
The isolation mechanism provides self-service by automatically closing the valve members when the pump is raised, eliminating the need for manual valve operation during pump removal. The system uses the pump's own movement (raising) to trigger the isolation action, reducing operational complexity and time.
3Ease of operation
If purging gas is supplied to force the foot valve open, then the pump can be removed, but impurities are introduced into the storage tank
Solution Approach 1:
The purging function is extracted from the storage tank environment and relocated to the external actuator system. The hollow actuator tube serves as a dedicated purging pathway that is isolated from the tank interior, allowing purging gas to be supplied and vented without introducing impurities into the stored cryogenic fluid.
Solution Approach 2:
The hollow actuator tube serves as an intermediary pathway that separates the purging operation from the storage tank. It allows purging gas to be supplied to open the valve and provides a dedicated exhaust path, preventing contamination of the stored fluid while maintaining ease of pump removal operation.
4Reliability
If the isolation valve is biased closed with spring and gravity, then the fail-safe position is achieved, but the actuation force required increases
Solution Approach 1:
The valve members are biased closed using spring forces and gravity (weight of the valve members themselves). This anti-weight approach uses the natural forces of spring tension and gravitational pull to maintain the fail-closed position, ensuring reliability without requiring complex locking mechanisms or excessive actuation forces.
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 provides safe and reliable isolation and purging of cryogenic storage tanks, preventing fluid loss and impurity introduction, while ensuring safe pump removal and installation, with a redundant sealing mechanism to maintain tank integrity.
Implementation Method 1
actuators that are hollow tubes configured to provide venting and purging for depressurization and clearing of any residual liquid or vapor
Implementation Method 2
a primary valve member provided at one end of the pump housing near a bottom of the storage vessel in the fluid, said primary valve member configured to be biased in a fail-closed position
Implementation Method 3
said primary valve member configured to be biased in a fail-closed position
Data Source
AI summary
An isolation mechanism for isolating a submerged pump in a storage vessel, where the isolation mechanism comprises a primary valve member and a secondary valve member, which are both biased in a fail-closed position. The isolation mechanism allows for redundancy for safety and reliability, and can be operated externally of the storage vessel. Furthermore, the isolation mechanism comprises venting and purging devices for safe operation of removal and installation of the pump in the storage vessel.