Rock Shear Box Sealing Structure for ScCO2 Corrosion Resistance
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Solution Overview
Problem
Existing shear boxes for testing shear-seepage coupling characteristics of rock mass under supercritical carbon dioxide conditions fail to provide adequate sealing and corrosion resistance due to high pressure and acidic environments, which are not adequately addressed by prior technologies.
Innovation Solution
A shear box design featuring an upper fixed shear box, a lower movable shear box, and a connection limiting part with inverted U-shaped frames, extrusion blocks, elastic sealing elements, and corrosion-resistant elastic capsules, along with a mechanism for adjusting the wheel shaft position, to ensure strong sealing and corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional shear box structures are used, then the device complexity is low, but the sealing performance and corrosion resistance are insufficient under high pressure and acidic environments
Solution Approach 1:
The patent employs composite sealing structures combining multiple materials with different properties. The sealing system integrates O-type rubber seals (providing elastic sealing) with PTFE (Teflon) lining (providing corrosion resistance and low friction). This composite approach allows the sealing components to simultaneously withstand high pressure, resist acidic corrosion from ScCO2, and maintain effective sealing, resolving the contradiction between reliability and structural simplicity.
Solution Approach 2:
The patent utilizes flexible sealing elements including O-type rubber seals and PTFE thin film lining. The O-type seals deform elastically under pressure to maintain contact and sealing, while the PTFE lining provides a flexible yet corrosion-resistant barrier. These flexible components adapt to pressure changes and surface irregularities, achieving reliable sealing without requiring complex rigid sealing mechanisms.
2Reliability
If traditional shear box structures are used, then the device complexity is low, but the corrosion resistance under acidic ScCO2 environment is insufficient
Solution Approach 1:
The patent applies PTFE (Teflon) as a thin film lining on the shear box surfaces that contact ScCO2 and rock samples. PTFE provides exceptional chemical inertness and corrosion resistance to acidic environments while maintaining flexibility and low friction. This thin film barrier protects the underlying metal structure from corrosion without requiring complete replacement of the shear box with corrosion-resistant materials, thus achieving high reliability with moderate structural complexity.
Solution Approach 2:
The sealing system combines rubber materials (providing elasticity and sealing) with PTFE coating (providing corrosion resistance). This composite material approach allows each material to contribute its superior properties: the rubber ensures sealing under pressure while the PTFE layer protects against acidic corrosion from supercritical CO2, achieving reliable corrosion resistance without overly complex structure.
3Reliability
If elastic capsules are added for sealing, then the sealing performance is improved, but the device complexity increases
Solution Approach 1:
The patent incorporates elastic capsules (hollow rubber or elastomeric membranes) within the shear box assembly. These capsules can be inflated with fluid or gas to expand and conform to the sealing surfaces, creating a positive seal that adapts to pressure changes and surface variations. The flexible nature of these capsules allows them to provide reliable sealing without requiring complex mechanical sealing systems, resolving the contradiction between sealing performance and structural complexity.
4Ease of operation
If inverted U-shaped frames with wheel shafts are used for connection, then the friction resistance is reduced, but the device complexity increases
Solution Approach 1:
The patent replaces traditional sliding friction interfaces with rolling friction by introducing wheel shafts (rotating rollers) in the inverted U-shaped frame connection structure. The wheel shafts rotate as the shear box moves, converting sliding friction into much lower rolling friction. This mechanical substitution dramatically reduces friction resistance and improves ease of operation, while the modular wheel shaft design keeps the added structural complexity manageable.
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 design provides effective sealing and corrosion resistance, ensuring accurate and reliable shear-seepage coupling tests under harsh conditions, with improved sealing and reduced friction resistance, while maintaining test stability and accuracy.
Implementation Method 1
a fluid can be injected into the elastic capsule to make the elastic capsule deform elastically with the injection of the fluid
Implementation Method 2
The first extrusion block includes a first small wedge, a first big wedge, and a first adjusting bolt arranged in sequence in the first direction... a surface joint of the first small wedge and the first big wedge is a first inclined plane
Data Source
AI summary
A shear box for testing shear-seepage coupling characteristics of rock mass, and a method of using the shear box are provided, including an upper fixed shear box, and a lower movable shear box. A first extrusion block and an upper rock mass sample are arranged in a first placement groove of the upper fixed shear box. A second extrusion block and a lower rock mass sample are arranged in a second placement groove of the lower fixed shear box. A first elastic sealing member is arranged on each of both sides of the upper rock mass sample and the lower rock mass sample, and an elastic capsule is arranged on each of inner walls of both sides of the first placement groove and the second placement groove. An upper pressure head device for applying a force in a third direction is arranged on the upper fixed shear box.