Control Valve Cage Flow Path for Flashing and Cavitation Reduction

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Solution Overview

Problem

Control valves experience damage and generate noise and vibration due to flashing and cavitation, which occur when fluid pressure drops below vapor pressure, causing vapor cavities to form and collapse.

Innovation Solution

A control valve design featuring a cylindrical cage with inner, outer, and intermediate walls that create a flow passage with protrusions forming pressure drops, reducing the likelihood of pressure dropping below vapor pressure by gradually increasing the flow area, thus minimizing flashing and cavitation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If fluid flows through a restricted area of the control valve, then flow control is achieved, but pressure drops to or below vapor pressure causing flashing and cavitation

Engineering Contradiction:

Improveflow controlVSAvoidflashing and cavitation

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The cage is divided into multiple sections with intermediate walls creating separate flow paths. These segmented paths allow progressive pressure reduction through multiple stages rather than a single restricted area, preventing pressure from dropping below vapor pressure in any single section while maintaining overall flow control.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The design adds a radial dimension to flow control by creating flow paths that extend radially outward from the central bore through the cage walls. This multi-dimensional flow approach distributes the pressure drop across multiple spatial dimensions rather than concentrating it in a single restricted area.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Stress or pressure

If vapor cavities form and collapse, then pressure regulation occurs, but damage is caused to valve components

Engineering Contradiction:

Improvepressure regulationVSAvoidcomponent damage

Core Design Contradiction:

Stress or pressureVSReliability

Solution Approach 1:

The cage structure pre-establishes multiple flow paths with progressive pressure drops before fluid reaches the valve seat. By preliminarily reducing pressure in controlled stages through the cage walls, the system prevents sudden pressure drops that would cause vapor cavity formation and subsequent cavitation damage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The cage acts as an intermediary element between the inlet and valve seat, mediating the pressure reduction process. The intermediate walls and flow paths within the cage serve as intermediate stages that gradually reduce pressure, preventing direct exposure of the valve seat to extreme pressure differentials that cause cavitation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Stress or pressure

If downstream pressure stays at or below vapor pressure, then vapor cavities expand, but flashing occurs causing noise and vibration

Engineering Contradiction:

Improvedownstream pressureVSAvoidnoise and vibration

Core Design Contradiction:

Stress or pressureVSObject-generated harmful factors

Solution Approach 1:

Different sections of the cage have locally optimized flow path characteristics. The intermediate walls create zones with progressively different flow areas and pressure conditions, ensuring that local pressure in each section remains above vapor pressure while maintaining overall pressure regulation functionality.

Inventive Principle:

Principle #3Local quality

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

The design effectively reduces the occurrence of flashing and cavitation, minimizing damage and noise/vibration by maintaining fluid pressure above vapor pressure through controlled pressure drops along the flow passage.

Implementation Method 1

The protrusions cooperate to form a plurality of pressure drops along the portion of the flow passage

Methodology Applied

Scientific EffectPressure drop: Pressure Drop

Implementation Method 2

When the pressure of the fluid drops to or below a vapor pressure of the fluid, vapor cavities may form in the fluid. When the downstream pressure of the fluid is higher than the vapor pressure, the vapor cavities may collapse in an event referred to as cavitation.

Methodology Applied

Scientific EffectCavitation: Cavitation

Implementation Method 3

When the pressure of the fluid drops to or below a vapor pressure of the fluid, vapor cavities may form in the fluid

Methodology Applied

Scientific EffectVapor pressure: Vapour Pressure

Data Source

PatentUS11703146B2Control valves and cages that are adapted to reduce flashing and cavitation

Publication Date: 2023.07.18 EMERSON PROCESS MANAGEMENT TIANJIN VALVES

AI summary

Control valves and cages that are adapted to reduce flashing and cavitation. A cage for use with a control valve having an inlet, an outlet, and defining a flow passage between the inlet and the outlet. The cage includes a generally cylindrical body and having a central bore, an upper portion, and a lower portion and an inner wall, an outer wall, and an intermediate wall disposed between the inner wall and the outer wall. The inner wall includes an inlet opening and the outer wall including an outlet opening. The inner wall, the outer wall, and the intermediate wall cooperate to define a portion of the flow passage that extends from the inlet opening, through the cage along the inner wall, along the intermediate wall, past a terminal portion of the intermediate wall, along the outer wall, to the outlet opening.