Instrument Access Shuttle for Cryogenic Tank Sealing
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Solution Overview
Problem
The introduction or removal of instruments from cryogenic tanks, such as LNG storage tanks, poses risks due to high internal pressure and low temperatures, leading to potential gas leaks, ignition hazards, and frost formation, which complicates maintaining tank tightness.
Innovation Solution
A method utilizing a shuttle and guide system with a tubular recess that maintains pressure greater than or equal to the tank pressure by injecting inert gas, preventing leaks and ensuring tightness during instrument entry or exit, using a chamber formed between the guide and shuttle with seals to minimize gas escape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an instrument is introduced or removed from a cryogenic tank under pressure, then the instrument can be accessed for maintenance or replacement, but gas leaks and frost formation occur compromising tank tightness
Solution Approach 1:
The tank wall is segmented into multiple sections: a fixed guide portion and a movable shuttle portion. The guide contains a passage through which the shuttle moves, creating separate zones (first zone inside tank, second zone outside tank, third zone interface). This segmentation allows the instrument to be accessed via the movable shuttle while the main tank structure remains sealed and pressurized.
Solution Approach 2:
The shuttle acts as an intermediary element between the instrument and the external environment. It moves within the guide passage, providing a controlled interface that allows instrument insertion/removal while maintaining the pressure differential. The shuttle seal creates a dynamic barrier that prevents gas leakage during instrument access operations.
2Quantity of substance
If the tank maintains high internal pressure for fluid storage, then storage capacity is optimized, but gas leakage through the instrument passage becomes hazardous
Solution Approach 1:
The system is pre-configured with a sealed guide passage and movable shuttle assembly before instrument access is needed. The guide passage is designed with sealing surfaces and the shuttle includes sealing elements that create pressure-resistant barriers. This preliminary preparation ensures that when instrument access is required, the high-pressure fluid cannot leak through the passage, as the sealing system is already in place.
Solution Approach 2:
The system maintains an inert or controlled atmosphere within the tank by preventing the escape of pressurized gas through the instrument passage. The sealed guide and movable shuttle create a barrier that keeps the high-pressure gas environment contained, eliminating the hazard of gas leakage to the external atmosphere during instrument operations.
3Reliability
If a sealed passage is used for instrument access, then tank tightness is maintained, but the instrument cannot be introduced or removed
Solution Approach 1:
The passage is designed with dynamic components: a movable shuttle that can translate along the guide passage. The shuttle moves between retracted and extended positions, allowing it to clear the way for instrument insertion while maintaining sealing contact with the guide walls. This dynamic mechanism enables the passage to transition between sealed and accessible states, resolving the contradiction between maintaining tightness and enabling instrument access.
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
This method effectively prevents gas leaks and ensures safe instrument entry/exit by maintaining a controlled pressure environment, reducing the risk of ignition and frost-related issues while minimizing inert gas consumption.
Implementation Method 1
maintaining in the recess a pressure greater than or equal to the pressure of the fluid contained in the reservoir, the pressure being maintained by injecting an inert gas into the recess
Data Source
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AI summary
A method for achieving the entry/exit of an instrument (2) in a reservoir (1) intended to contain a fluid (1a) at a pressure greater than atmospheric pressure, employing a shuttle (3) to receive the instrument and a guide (4) for the shuttle in the reservoir, the method being characterized in that it comprises the steps: - providing a cooperation zone of the guide (4) with the shuttle (3) comprising a tubular recess surrounding the shuttle (3), the recess being delimited: * laterally, by an internal surface of the guide and an external surface of the shuttle, and * longitudinally, by at least two contact zones, upper and lower, between said external surface of the shuttle and respective extensions of said internal surface of the guide, and - during movement of the shuttle in the guide, maintaining in the recess a pressure greater than or equal to the pressure of the fluid contained in the reservoir,The pressure is maintained by injecting an inert gas into the cavity.