Divided-Bonnet Valve Backseat Structure for Cryogenic Pressure Relief
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional valves for ultralow-temperature fluids like LNG face challenges in maintaining structural accuracy and preventing pressure increases due to complex inner structures and difficulties in processing sealed surfaces, particularly in longneck structures with integral bonnets, which can lead to leakage and material limitations.
Innovation Solution
A valve design with a divided bonnet structure, where the bonnet is split into an upper and lower bonnet, allowing for easy processing and adjustment of the fixed-side and movable-side seal surfaces, preventing fluid penetration and pressure increases by positioning the backseat mechanism above the fluid's liquid state, thereby reducing the risk of gasification and leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a backseat mechanism is provided at a lower part of the bonnet to release pressure, then pressure release function is improved, but the structure becomes complicated and processing difficulty increases
Solution Approach 1:
The bonnet is divided into an upper bonnet and a lower bonnet as separate components. The backseat mechanism is integrated into the upper bonnet, which is then assembled onto the lower bonnet. This segmentation allows the backseat mechanism to be positioned higher (in the upper bonnet) rather than lower, simplifying the overall structure while maintaining the pressure release function, as the upper bonnet can be designed with easier access for tool insertion and processing.
Solution Approach 2:
The upper bonnet is prepared in advance with the backseat mechanism integrated into its design before assembly with the lower bonnet. This preliminary integration allows for pre-processing and pre-positioning of sealing surfaces and other critical features, reducing on-site complexity and enabling the backseat to function effectively at a higher position without complicating the overall structure.
2Reliability
If a backseat mechanism is provided at a high position inside the bonnet, then liquid penetration is prevented, but processing accuracy decreases due to difficulty in accessing the sealed surface
Solution Approach 1:
By dividing the bonnet into upper and lower sections, the sealed surface of the backseat mechanism in the upper bonnet becomes more accessible. The segmentation allows tools to be inserted from the top or side of the upper bonnet, enabling accurate machining and hard-facing of the sealing surface without the constraints of working from the bottom of an integral bonnet structure.
Solution Approach 2:
The upper bonnet acts as an intermediary structure that provides access to the backseat sealing surface. This intermediate component allows processing tools to reach the sealed surface from a convenient direction, ensuring high processing accuracy while maintaining the backseat's elevated position for effective liquid penetration prevention.
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 divided bonnet structure enables high-accuracy processing and assembly, reduces the risk of leakage, and allows for the use of materials that can withstand higher temperatures, ensuring reliable operation and preventing damage from pressure increases and gasification of ultralow-temperature fluids.
Implementation Method 1
a backseat mechanism having a fixed-side seal surface formed on a lower end side of the upper bonnet and a movable-side seal surface formed on an outer peripheral surface of the stem and forms abutting sealing by the movable-side seal surface and the fixed-side seal surface when the valve body is open
Implementation Method 2
positioning the backseat mechanism above the fluid's liquid state, thereby reducing the risk of gasification and leakage
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
The present invention provides a valve in which a backseat structure is formed at a height for easily preventing penetration of the fluid with high accuracy from outside a bonnet to reliably inhibit an increase in internal pressure. In a state in which a packing for sealing (5) is attached inside a bonnet (10) in a longneck structure, a stem (3) is axially inserted so as to freely ascend and descend and a flow path (13) inside a valve box (2) is provided so as to be freely opened and closed by a valve body (4) provided at a lower end of this stem (3). The bonnet (10) is integrally provided in a state of being divided into an upper bonnet (11) and a lower bonnet (12) at a position higher than a position at which a fluid flowing inside the valve box (2) ascends in a liquid state. A backseat mechanism (42) has a fixed-side seal surface (21) formed on a lower end side of the upper bonnet (11) and a movable-side seal surface (41) on an outer peripheral surface of the stem (3) and forms abutting sealing by the movable-side seal surface (41) and the fixed-side seal surface (21) when the valve body (4) is open.