Double-Seat Valve Cleaning System with Ejector Effect
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Solution Overview
Problem
Double-seat mixproof valves in the food processing and dairy industries face challenges in preventing cleaning fluid from reaching the opposite cavity during mechanical cleaning, especially when the communication passage fails to block properly, which is a regulatory concern.
Innovation Solution
The double-seat mixproof valve employs a cleaning system with a leading surface on the first valve plug and a trailing surface on the second valve plug, where the leading surface has a sharp edge and is substantially tangential to the trailing surface, creating an ejector effect that directs cleaning fluid away from the production cavity, ensuring that even during seal failure, production fluid enters the vent cavity instead of cleaning fluid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mechanical cleaning is performed on one cavity while process liquid remains in the opposite cavity, then cleaning effectiveness is improved, but risk of cleaning fluid contamination to the opposite cavity increases
Solution Approach 1:
The valve is segmented into two separate cavities (first cavity and second cavity) with independent valve plugs and seats, allowing one cavity to be cleaned while the other remains isolated and maintains production. The communication passage between cavities can be selectively blocked by either valve plug, creating physical separation that enables safe cleaning operations.
Solution Approach 2:
The vent cavity acts as an intermediary chamber between the two process cavities. During cleaning of one cavity, the vent cavity serves as a buffer zone that receives cleaning fluid while preventing it from reaching the opposite production cavity. The self-draining opening to atmosphere in the vent cavity ensures any cleaning fluid that enters is safely discharged.
2Reliability
If the communication passage between cavities is blocked by valve plugs, then cross-contamination is prevented, but reliability upon seal failure is worsened
Solution Approach 1:
The leading surface with sharp edge creates a preliminary protective barrier that prevents cleaning fluid from directly impinging on the seal between the valve plug and valve seat. The sharp edge detaches the cleaning fluid flow before it can reach the seal, and the tangential arrangement maintains suction on the seal during cleaning operations. This preliminary anti-action ensures that even if the seal fails, cleaning fluid cannot penetrate into the production cavity.
Solution Approach 2:
The design converts the potential harmful effect of seal failure into a beneficial outcome. By positioning the leading surface and sharp edge to create suction on the seal during cleaning, any seal failure causes production fluid to leak into the vent cavity (which then drains to atmosphere) rather than allowing cleaning fluid to enter the production cavity. The harmful scenario of seal failure is thus converted into a fail-safe condition.
3Ease of manufacture
If cleaning fluid flow is directed towards valve seats and seals, then cleaning coverage is improved, but backflow into production cavity is caused
Solution Approach 1:
The leading surface is designed with a sharp edge at its termination, creating a localized flow detachment point. This local geometric feature causes the cleaning fluid flow to detach from the leading surface and become airborne before reaching the valve seats and seals. The sharp edge creates a specific local condition that prevents backflow while maintaining effective cleaning coverage on the intended surfaces.
Solution Approach 2:
The leading surface and trailing surface are arranged to be substantially tangential at the point of attack, creating a three-dimensional flow path that directs cleaning fluid away from the production cavity. The tangential arrangement in 3D space ensures cleaning fluid flows along the surface rather than impinging perpendicular to it, preventing backflow towards seals while maintaining cleaning effectiveness.
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 effectively prevents backflow of cleaning fluid into the production cavity, maintaining a fail-safe condition during cleaning operations, allowing for regular valve maintenance without contaminating the production fluid, even when the communication passage is unsealed.
Implementation Method 1
The flow of cleaning fluid is spanning the gap between the two or more valve parts and becomes airborne over the gab. This causes an ejector effect, such that suction is established at the valve seat.
Data Source
Figure 1
Figure 2a~2b
Figure 3a~3b
AI summary
A double-seat mixproof valve (10) having a plurality of valve parts, where said valve parts comprise a body (12) having a first cavity (18) with a first valve seat (22), a second cavity (20) with a second valve seat (24), and a vent cavity (26) between the valve seats (22, 24), a first valve plug (14) with a first stem (30), for selectively blocking the first valve seat (22), a second valve plug (16) with a second stem (32), for selectively blocking the second valve seat (24), the second valve stem (32) having a hollow central part (34) for guiding the first stem (30) a cleaning system, for selectively applying a flow of cleaning fluid (48) to the valve parts, where the cleaning system comprise a leading surface (50, 66) on one valve part and a trailing surface (56, 68) on an adjacent valve part, said leading surface (50, 66) is adapted for guiding the flow of cleaning fluid (48) towards a point of attack (60, 72) on the trailing surface (56, 68), said trailing surface (56, 68) being adapted for receiving the flow of cleaning fluid (48) from the leading surface (50, 66), wherein the leading surface (50, 60) has a sharp edge at its termination (58 ,70).