Cylindrical Cage Flow Control for Dead Band Elimination
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Solution Overview
Problem
Existing flow control devices with nested cylindrical cages and perforations suffer from dead bands, leading to non-linear control over fluid flow, making accurate control difficult, especially when the valve is close to these dead band positions.
Innovation Solution
The flow control device features a cylindrical cage with convoluted flow paths and fences shaped with a first and second section, along with interconnecting sections, ensuring that each perforation is surrounded by a flat land, allowing for a more linear relationship between plug movement and flow restriction, reducing or eliminating dead bands and enhancing turbulence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional straight fences are used in flow control devices, then the structure is simple, but dead bands appear causing non-linear flow control
Solution Approach 1:
The fence is segmented into multiple sections (first section, second section, and interconnecting sections) positioned at different axial locations. This segmentation allows the fence to create overlapping flow path restrictions that eliminate dead bands, ensuring continuous flow control as the plug moves through the device.
Solution Approach 2:
The fence design extends in the axial dimension with multiple sections spaced apart, creating a three-dimensional flow restriction pattern. This multi-dimensional approach ensures that as the plug moves axially, it continuously interacts with fence sections, eliminating the dead bands that occur with simple two-dimensional straight fences.
2Measurement precision
If perforations are positioned close to straight fences, then the device structure is compact, but dead bands occur reducing control accuracy
Solution Approach 1:
The fence structure is designed with different sections at different axial positions, creating local variations in flow restriction. The first and second sections are positioned to work with specific rows of perforations, while interconnecting sections bridge the gaps, ensuring that each local region contributes to eliminating dead bands without requiring excessive overall device volume.
3Adaptability or versatility
If multiple rows of perforations are used with straight fences, then flow control capability is enhanced, but dead bands increase making precise positioning difficult
Solution Approach 1:
The fence is divided into multiple segments positioned at different axial locations to correspond with different rows of perforations. This segmentation ensures that as the plug moves through the device, it continuously interacts with fence sections, maintaining flow control versatility while eliminating dead bands that would prevent precise positioning.
Solution Approach 2:
The interconnecting sections between the first and second fence sections ensure continuous flow restriction throughout the axial movement of the plug. This continuity eliminates dead bands where no flow control action would occur, ensuring that the valve provides precise control across its entire range of motion.
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
This design ensures continuous control over fluid flow, reduces the impact of dead bands, and increases turbulence, resulting in improved flow control and pressure reduction.
Implementation Method 1
The cages are positioned relative to one another such that the perforations provided in one of the cages are out of alignment with the perforations provided in the other of the cages. Accordingly, fluid flowing through the flow control device between an inner periphery and an outer periphery thereof is forced to undergo a series of changes in flow direction.
Implementation Method 2
controlling the fluid flow rate and/or pressure drop within the device
Data Source
Figure 1~4
Figure 5a~7c
AI summary
A flow control device is described comprising a generally cylindrical cage (12) including a series of perforations (14) defining, in part, convoluted flow paths between inner and outer peripheries of the device (10), and fences (18) restricting axial flow along at least one of the inner and outer periphery of the cage, wherein at least one of the fences is shaped to include a first section (18a) at a first axial position, a second section (18b) at an axial position spaced from the first section (18a), and interconnecting sections (18c) interconnecting the first and second sections, wherein the perforations are spaced from the fences so that a flat land (15) is present surrounding each perforation.