Sealed Regulator Trim Assembly for Wide Turndown Control
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Solution Overview
Problem
Conventional regulators struggle to provide stable flow rates at both high and low demand conditions due to insufficient turndown characteristics, leading to disruptions and increased maintenance costs, particularly in natural gas distribution systems where demand changes over time.
Innovation Solution
A regulator design featuring a trim assembly with a moveable plug and annular cage, where the plug has a seal assembly that contacts the cage's inner surface to control flow through a plurality of apertures, reducing clearance and ensuring stable operation across varying demand levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional regulators are designed for high flow rates, then they can meet peak demand, but they cannot provide stable flow at low demand conditions
Solution Approach 1:
The flow path is segmented into multiple cage apertures that can be independently controlled by the plug. The plug can selectively block or open different apertures based on demand, allowing the regulator to maintain stable flow control across a wide range of flow rates by adjusting which segments of the flow path are active.
Solution Approach 2:
The plug is designed to be moveable within the cage, allowing dynamic adjustment of the flow area. This dynamic positioning enables the regulator to adapt to varying demand conditions, transitioning smoothly between high and low flow rate modes while maintaining stable flow control at each operating point.
2Ease of operation
If the plug clearance is increased to allow smooth movement, then operation is easier, but blowby increases and flow control precision deteriorates
Solution Approach 1:
The sealing strategy is applied locally at the interface between the plug and cage. The plug includes a sealing surface that contacts the inner surface of the cage at specific locations to prevent blowby, while maintaining adequate clearance elsewhere for smooth movement. This localized sealing approach preserves both ease of operation and flow control precision.
3Device complexity
If a single flow path is used, then the structure is simple, but turndown ratio is insufficient
Solution Approach 1:
The flow path is extended in the radial dimension by incorporating multiple cage apertures arranged circumferentially. The plug can control the flow area by moving radially within the cage, blocking or opening different apertures. This dimensional approach enables a high turndown ratio without significantly increasing structural complexity, as the apertures are integrated into the cage structure.
Data Source
AI summary
A trim assembly for a regulator can include a cage and a plug assembly. The cage can include a peripheral wall defining an opening and a plurality of cage apertures formed in the peripheral wall. The plug assembly can include a plug and a sealing element and can be configured to be moveably received within the opening so that the sealing element contacts an inner surface of the cage to vary a flow area through the plurality of cage apertures depending on the position of the plug.