Superconducting Cable Rupture Disk Pressure Relief
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Solution Overview
Problem
Superconducting cable systems face pressure increases due to heat load after vacuum insulation damage, leading to potential inner container damage, as pressure relief devices may not dissipate pressure quickly enough, and existing solutions either increase cable diameter or risk contamination.
Innovation Solution
A superconducting cable system with a rupture disk connection between coolant-carrying interior spaces of cable cryostats, allowing excess pressure to be diverted through increased hydraulic cross section, with two rupture disks and a cavity at atmospheric pressure to precisely control triggering pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the hydraulic cross section of the inner container is increased to reduce pressure drop along the cable, then the pressure drop is reduced and pressure at fault location is controlled, but the diameter of the superconducting cable increases and installation effort increases
Solution Approach 1:
The cable system is divided into multiple independent vacuum sections separated by vacuum breaks. Each section has its own pressure containment capability through the inner container, allowing localized pressure management without requiring the entire cable to have increased diameter. The segmentation enables pressure relief to be contained within specific sections rather than affecting the whole system.
Solution Approach 2:
A rupture disk is introduced as an intermediary pressure relief device between the coolant-carrying interior space and the vacuum space. This rupture disk provides a controlled failure mechanism that releases excess pressure locally when the pressure differential exceeds a predetermined threshold, preventing the need to increase the overall cable diameter to manage pressure drops.
2Reliability
If additional pressure relief devices are attached to the outside along the cable route, then pressure relief capability is improved, but contaminants can penetrate into the interior of the cable cryostat and cause malfunctions
Solution Approach 1:
The rupture disk serves as a sealed intermediary that provides pressure relief while maintaining containment. It is positioned inside the inner container and provides a controlled release mechanism that prevents external contaminants from entering the coolant space, thus improving reliability without introducing contamination risks.
Solution Approach 2:
The pressure relief function is extracted from external devices and integrated into the inner container itself through the rupture disk. This internal integration eliminates the need for external pressure relief devices that would be vulnerable to contaminant penetration, while maintaining effective pressure relief capability.
3Reliability
If pressure relief devices are positioned at both ends of the system, then pressure relief is provided, but significant pressure drop in the nitrogen flow from fault location to pressure relief device can occur leading to damage
Solution Approach 1:
The system is segmented into multiple vacuum sections with each section capable of independent pressure management. By placing rupture disks at strategic locations within each section, the distance any pressure wave must travel is limited, preventing excessive pressure drops that would occur in long uninterrupted sections.
Solution Approach 2:
The rupture disk is pre-positioned within the inner container at locations that anticipate potential fault zones. This preliminary placement ensures that when a pressure event occurs, the rupture disk is already in position to provide immediate local relief, eliminating the need for pressure to travel long distances to reach end-based relief devices.
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
Effectively limits pressure increases in the affected cable cryostat to prevent damage, maintaining insulation integrity and avoiding cable diameter increase or contamination risks.
Implementation Method 1
A connection (308) is arranged between the coolant-carrying interior spaces (404) of the cable cryostats (103), which is closed with a rupture disk (406, 407) during normal operation, in particular in such a way that in the event of a fault, the rupture disk (406, 407) bursts at a pressure which exceeds a predetermined pressure threshold
Implementation Method 2
two rupture disks (406, 407) are arranged in the connection (308), between which a cavity (408) is enclosed. During normal operation of the cable system, there is expediently a pressure in the cavity (408) between the two rupture disks (406, 407) that is lower than the pressure in the interior of the cable cryostat
Implementation Method 3
a vacuum-insulated cable cryostat (103). The cable cryostat (103) contains coolant which keeps the superconducting conductor (202) at temperatures below a transition temperature of the superconducting conductor
Implementation Method 4
One of the properties of superconducting material is that its electrical resistance drops to zero when it is cooled to temperatures below the so-called transition temperature
Data Source
Figure 1~2
Figure 3
Figure 4A~4B
AI summary
A cable system with several superconducting cables (302, 303) is proposed, each having a superconducting conductor housed within an interior space of a vacuum-insulated cable cryostat. A connection (308) is arranged between the coolant-carrying interior spaces of the cable cryostats. Under normal operating conditions, this connection is sealed by a rupture disc (406, 407), thus separating the interior spaces of the cable cryostats from one another. If, in the event of a fault, an unacceptably high pressure develops within the interior of a cable cryostat, which cannot be dissipated quickly enough via pressure relief devices at the ends of the superconducting cable in question, the rupture disc (406, 407) ruptures, creating a flow connection between the interior spaces of two superconducting cables.This increases the hydraulic cross-section of the cable system, through which the excess pressure can be discharged to the pressure relief devices.