Ball Valve Port Geometry for Accurate Low-Flow Control
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Solution Overview
Problem
Conventional ball valves struggle with achieving a combination of high flow capacity and high flow accuracy at low flow rates, particularly in applications requiring precise control over a wide range of fluid flow rates, such as low emissions industrial gas turbines.
Innovation Solution
A ball valve design featuring a hole profile with distinct regions of controlled flow area expansion, including a first channel with minimal width and divergence, allowing for precise control at low flows and high flow capacity when fully open, actuated by an electric motor with reduced hysteresis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a full circular cutout is used in the ball, then high flow capacity is achieved, but flow accuracy at low flow rates deteriorates
Solution Approach 1:
The circular cutout is segmented into multiple distinct regions: a first region with a first radius providing high flow capacity, and a second region with a second radius providing precise low flow control. This segmentation allows each region to optimize for its specific function, resolving the contradiction between high flow capacity and low flow accuracy.
Solution Approach 2:
Different regions of the ball's cutout are given different local qualities - the first region has a larger radius optimized for high flow capacity, while the second region has a smaller radius optimized for precise low flow control. This local differentiation allows the single ball component to simultaneously achieve both high flow capacity and high flow accuracy at low flow rates.
2Measurement precision
If a V-port with small cutout angle (e.g., 15 degrees) is used, then flow accuracy at low flow rates is improved, but flow capacity at high flow rates is reduced
Solution Approach 1:
Instead of using a single V-port geometry, the invention segments the cutout into multiple regions with different characteristics. The first region provides the flow capacity needed for high flow rates, while the second region provides the precision needed for low flow rates, eliminating the trade-off present in single-geometry V-port designs.
3Quantity of substance
If a V-port with large cutout angle (e.g., 60 degrees) is used, then flow capacity is improved, but flow accuracy at low flow rates deteriorates
Solution Approach 1:
The invention segments the cutout geometry so that the first region can provide high flow capacity similar to a large-angle V-port, while the second region provides precise low flow control similar to a small-angle V-port. This segmentation resolves the contradiction by combining the advantages of both large and small cutout angles in a single ball design.
4Ease of operation
If actuator positioning has slight unrepeatability, then positioning flexibility is maintained, but flow rate consistency deteriorates
Solution Approach 1:
The dual-region cutout design provides a cushioning effect against positioning inaccuracies. The transition between the first and second regions creates a flow characteristic that is less sensitive to small variations in ball position, thereby compensating for actuator unrepeatability and maintaining consistent flow rates despite positioning flexibility.
Data Source
AI summary
An example valve includes: a housing having a first port and a second port; a stem disposed and rotatable within the housing; and a ball disposed within the housing and rotatable by the stem, wherein the ball has a hole therethrough to control fluid flow from the first port to the second port, wherein the hole has a profile comprising: a first opening at a base of the hole, a first channel connected to and extending from the first opening, wherein the first channel has a width that is less than a respective width of the first opening such that a neck portion is formed at a connection of the first channel with the first opening, a second channel extending from the first channel and diverging by a particular angle, and a second opening connected to the second channel.