Helical Perforated Plug Layout for Smooth Control Valve Flow
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Solution Overview
Problem
Control valves with cup-shaped perforated plugs face challenges in achieving a smooth and reliable flow rate adjustment over a wide range, particularly when handling hazardous substances like oxygen, as existing hole patterns result in irregular flow characteristics and do not meet the required equal percentage dependence on valve position.
Innovation Solution
The arrangement of openings on at least one helical line around the perforated plug, with a specific ratio of maximum to minimum web width, ensures a smooth flow characteristic, allowing for reliable operation at both small and large flow rates, and the number of helical lines is optimized to maintain mechanical stability and efficiency, while the shape and distribution of openings can be adapted to meet specific application requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If openings are arranged in horizontal rows on the perforated plug, then the flow rate increases when a row is being enabled, but this leads to irregular flow characteristics and cannot achieve equal percentage dependence
Solution Approach 1:
The patent applies a helical arrangement of openings instead of horizontal rows, creating a curved/continuous flow path progression. The helical line wraps around the perforated plug, enabling openings sequentially in a smooth, continuous manner rather than in discrete horizontal steps, thereby achieving equal percentage flow characteristics.
2Reliability
If openings are arranged on a helical line, then the flow characteristic becomes smoother, but the distances between openings are relatively large such that the maximum possible flow rate is not reached
Solution Approach 1:
The patent combines multiple helical lines on the same perforated plug, allowing openings from different helical lines to be enabled simultaneously. This merging of multiple helical patterns increases the total number of enabled openings at any given valve position, thereby achieving both smooth flow characteristics and high maximum flow rate.
3Productivity
If the number of helical lines is increased to increase flow rate, then maximum flow rate is improved, but mechanical stability may be compromised due to reduced web width
Solution Approach 1:
The patent optimizes parameters including the number of helical lines, the pitch between openings, and the web width to achieve the desired balance. By carefully selecting these parameters, the design achieves high flow rate capability while maintaining sufficient mechanical strength and stability of the perforated plug structure.
Data Source
AI summary
Control valves find one of their most important applications in control loops of process plants for controlling the flow rate of a gaseous or liquid medium. To this end, it is crucial that the flow rate can be reliably adjusted and that safe operation, especially with hazardous substances, can be guaranteed. To solve this problem, a hole pattern for perforated plugs (300) of control valves is proposed, which allows the densest possible arrangement of openings (220) on helical lines where the height of the helical lines is minimal and, at the same time, advantageous technical specifications and safety regulations can be taken into account. The pattern allows to generate a very smooth flow characteristic, which facilitates a reliable control of the flow rate. Moreover, the flow rate can be optimized such that the size of the moving parts of the control valve can be reduced to a minimum.