Ball Valve Trim Plates for Erosion Control Under High Pressure
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Solution Overview
Problem
Existing ball valve designs face significant erosion issues in high differential pressure applications due to high fluid velocities and impingement angles, particularly in erosive service conditions, leading to premature wear and inefficiencies.
Innovation Solution
The design incorporates tungsten carbide bushings with adjustable nozzles and convex upstream surfaces, along with offset hole patterns and independently adjustable trim plates, to control fluid velocity and impingement angles, reducing erosion and extending the lifespan of valve components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If small diameter holes are used in the cage to reduce velocity, then erosion is reduced, but the holes clog due to particle accumulation
Solution Approach 1:
The patent applies different surface properties to different parts of the cage. The inner surface of the cage is coated with a non-stick material (PTFE or similar) to prevent particle adhesion, while the outer surface maintains structural integrity. This local differentiation allows small holes to remain unclogged by preventing particle accumulation on the cage surface.
Solution Approach 2:
The cage is constructed as a composite structure combining a structural base material (for strength and pressure containment) with a non-stick coating layer (for anti-adhesion properties). This composite approach allows the cage to simultaneously provide mechanical support and prevent particle accumulation that would cause clogging.
2Stress or pressure
If high differential pressure is controlled through small cross-sectional areas, then pressure control is achieved, but velocity increases causing severe erosion
Solution Approach 1:
The flow path is segmented into multiple stages with progressively larger cross-sectional areas. Instead of a single small hole, the cage contains multiple holes arranged in series, with each subsequent hole being slightly larger. This segmentation allows pressure control to be distributed across multiple elements, reducing the velocity and erosion in each individual hole while maintaining overall pressure differential control.
Solution Approach 2:
The patent varies the hole diameter parameter along the flow path, creating a gradient from smaller to larger holes. This parameter change allows the system to maintain high pressure differential control in the initial stages while progressively reducing velocity and erosion risk in downstream stages.
3Object-affected harmful factors
If tungsten carbide overlay is provided for the entire upstream faces of the trim plates, then erosion resistance is improved, but erosion is greatest at ninety degrees where the overlay is applied
Solution Approach 1:
The patent introduces asymmetric features in the form of angled surfaces and non-perpendicular hole arrangements. The holes in the cage are positioned at angles rather than perpendicular to the flow, and the trim plates incorporate angled surfaces that deflect the flow. This asymmetry prevents the erosive medium from impinging at 90 degrees, the angle at which tungsten carbide is most vulnerable, thereby preserving the overlay's erosion resistance.
Solution Approach 2:
The patent incorporates curved and angled surfaces in the trim plate design, replacing flat perpendicular surfaces. The curved surfaces redirect the flow at oblique angles, preventing direct 90-degree impingement on the tungsten carbide overlay. This curvature strategy exploits the fact that erosion resistance is better at angles other than 90 degrees.
Data Source
AI summary
A ball valve trim apparatus for high differential pressure service that is resistant to erosion includes elements selected from a plurality of stacked impedance trim plates positioned in the passage of the ball portion of the valve; the plates being independently adjustable along transverse axes that are parallel to the axis of rotation of the ball: one or more of the plates having a convex upstream contour, each plate provided with a predetermined pattern of variously sized fluid passageways, the pattern varying from plate-to-plate in the stack; erosion-resistant bushings inserted into the trim plate holes can be independently rotationally adjustable to control the rate of the flowing fluid, the upstream surface of the plate surrounding the orifice of the bushing defining a raised toroidal body.