Subsea Chemical Injection Valve with Pressure Compensation
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Solution Overview
Problem
Existing subsea valves require manual adjustment for setting opening pressure and do not compensate for hydrostatic pressure, nor do they prevent backflow when outlet pressure exceeds inlet pressure.
Innovation Solution
A pressure-compensated relief gate valve with a check valve, such as a poppet valve, and a valve actuator mechanism that uses both hydraulic and mechanical forces to manage pressure, ensuring the valve opens with sufficient inlet pressure and closes to prevent backflow, featuring a replaceable valve seat and a design that allows for easy assembly and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If manual adjustment is used for setting opening pressure, then the valve can be operated, but it requires manual intervention and does not compensate for hydrostatic pressure
Solution Approach 1:
The pressure compensator uses the ambient hydrostatic pressure itself to automatically adjust the opening pressure of the valve. The piston moves in response to pressure differential, automatically compressing or relaxing the elastic member to compensate for hydrostatic pressure changes without external intervention.
Solution Approach 2:
The pressure compensator utilizes hydraulic principles where a piston exposed to ambient pressure through an orifice balances hydrostatic pressure forces. This hydraulic mechanism automatically adjusts the mechanical spring pressure to compensate for depth-related pressure changes in subsea environments.
2Reliability
If the valve structure is simple, then manufacturing is easier, but it cannot prevent backflow when outlet pressure exceeds inlet pressure
Solution Approach 1:
The check valve functionality is integrated into the existing valve structure by positioning a check valve within the lateral passage. This combines the relief valve function with backflow prevention in a single integrated device, achieving both functions without requiring completely separate systems.
Solution Approach 2:
The check valve acts as an intermediary component that allows forward flow when inlet pressure exceeds outlet pressure but prevents reverse flow when outlet pressure exceeds inlet pressure. This intermediary element adds backflow prevention capability to the valve system.
3Adaptability or versatility
If the valve is designed for subsea environment, then it can operate under high pressure, but it requires compensation for hydrostatic pressure variations
Solution Approach 1:
The pressure compensator acts as a counterbalancing mechanism that offsets hydrostatic pressure forces. The piston exposed to ambient pressure creates a counteracting force that balances the hydrostatic pressure acting on the valve components, allowing the valve to operate correctly at various depths.
Solution Approach 2:
The pressure compensator dynamically changes the effective pressure parameters by allowing the piston to move and the elastic member to compress or relax. This adjusts the opening pressure of the valve in real-time to compensate for changing hydrostatic pressure conditions in the subsea environment.
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 automatic pressure compensation and prevents backflow, ensuring reliable operation in subsea environments with high fluid pressures, reducing the risk of malfunction due to contamination or corrosion, and allowing for easy maintenance and replacement of components.
Implementation Method 1
The other side of the bearing plate may be engaged by one or more elastic members which, in one preferred embodiment, are helical compression load springs
Implementation Method 2
The spring bears at one end against the terminus of the cavity and, at the other end, presses against a seal disc or gate
Implementation Method 3
One side of the piston is in fluid communication with the environment via an orifice and is therefore subject to ambient pressure. The stem of the valve actuator is also in fluid communication with this cavity such that the ambient pressure may act on the cross-sectional area of the stem, urging it towards the closed position
Implementation Method 4
A check valve is positioned within the lateral passage for preventing backflow of fluid through the valve
Data Source
AI summary
A backpressure-protected valve suitable for subsea well treatment chemical injection applications includes an improved gate valve, a check valve and a pressure compensator responsive to ambient hydrostatic pressure. The check valve may comprise a poppet valve in a detachable outlet body. The pressure compensator comprises a free piston in a cylinder. The portion of the cylinder on one side of the piston is exposed to seawater whereas the portion of the cylinder on the opposing side of the piston is filled with a selected hydraulic fluid. In this way the valve actuator is not exposed to the corrosive and/or contaminating effects of seawater.