Dual-Plug Valve Flow Control for Wide Turndown Precision
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Solution Overview
Problem
Conventional flow control devices struggle to manage both high and low flow rates effectively, as they require large valve/port sizes for high-capacity flow, leading to increased minimum controllable capacity and inability to address varying flow conditions.
Innovation Solution
The proposed flow control system includes a cage, a first plug, and a second plug, where the first plug forms a seal with an outer seat ring and the second plug forms a seal with an inner seat ring, allowing for independent movement to control flow rates across a wide range, from 1% to 100% of the maximum rated flow capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large valve/port size is used to achieve high flow capacity, then the maximum flow rate is improved, but the minimum controllable flow rate increases and precision is lost
Solution Approach 1:
The valve is divided into two independent flow control systems: an outer valve with a first plug and seat for high flow rates, and an inner valve with a second plug and seat for low flow rates. Each valve can operate independently, allowing the system to handle both high and low flow rates with appropriate precision without requiring a single large valve that would compromise minimum controllable capacity.
Solution Approach 2:
The inner valve assembly (second plug, second seat, and associated components) is nested within the outer valve body. The second plug is disposed within a flow cavity of the first plug, and the second seat is fixed to the first plug. This nested configuration allows both valves to occupy the same spatial envelope, enabling high flow capacity through the outer valve while maintaining precise low flow control through the inner valve.
2Adaptability or versatility
If a single valve design is used to cover all flow rates, then device simplicity is maintained, but the ability to control varying flow conditions effectively is lost
Solution Approach 1:
The flow control function is segmented into two independent valves: the outer valve for high flow rates and the inner valve for low flow rates. This segmentation allows each valve to be optimized for its specific flow range, improving overall adaptability across varying flow conditions.
Solution Approach 2:
The nested dual-valve design provides multi-functionality within a single valve body. The outer valve handles high flow rates while the inner valve handles low flow rates, and both can operate simultaneously or independently. This universal design allows a single valve assembly to replace what would traditionally require multiple separate valves or complex adjustable mechanisms.
Data Source
AI summary
A plug assembly for a valve can include a valve cage, an outer plug, an inner plug, and respective outer and inner seat rings. The outer seat ring can be fixed relative to the cage and the inner seat ring can be fixed relative to the outer plug. The inner plug can be disposed within a flow cavity formed in the outer plug and fixed to a valve stem of the valve. In use, during a relatively low range of flow rates, the outer plug can remain seated on the outer seat ring and the inner plug can move axially away from the inner seat ring and within the flow cavity to provide a low flow rate control. During a relatively high range of flow rates, each of the inner and outer plugs can lift off their respective seat rings to provide a higher flow rate control.