Venturi Rag Relief for Combined Sewage Overflow Screens
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Solution Overview
Problem
Conventional Combined Sewage Overflow (CSO) systems face issues with screen blockage due to the buildup of sewage solids and rag, leading to undesirable discharge into waterways, as existing solutions like oversized screens and mechanical raking are inadequate in preventing blockages and maintaining screen efficiency.
Innovation Solution
A venturi device is integrated into the CSO system, featuring a body with a fluid passageway, intake funnel, and venturi pipe that reduces hydraulic resistance and facilitates the removal of debris, mixing fluid to reduce solids content and prevent screen blockage, while an outlet funnel ensures unrestricted flow of silt away from the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional screens are used in CSO systems, then sewage solids and rag are prevented from being discharged into waterways, but the screens gradually become blocked due to buildup of solids and rag
Solution Approach 1:
The invention extracts and removes sewage solids and rag from the effluent stream before it reaches the screen. A separate solids removal system (such as a hydrocyclone or flotation device) diverts solids-laden water away from the screen, allowing the screen to process only relatively clean effluent while solids are removed through alternative means.
Solution Approach 2:
The invention segments the effluent treatment process into separate functional zones: one dedicated to solids removal and another for screen filtration. This segmentation allows each component to specialize in its specific function, preventing the screen from being overwhelmed by solids buildup while maintaining effective filtration.
2Reliability
If oversized screens are employed to slow down blockage rate, then screen blockage occurs less frequently, but device complexity and cost increase
Solution Approach 1:
Instead of increasing screen size, the invention extracts solids from the effluent stream using a separate removal mechanism. This approach achieves reduced blockage frequency without requiring larger screens, thereby avoiding increased device complexity and cost associated with oversized screening equipment.
3Reliability
If mechanical raking is used to clear screens, then screen performance is maintained, but device complexity and maintenance requirements increase
Solution Approach 1:
The invention removes solids from the effluent stream before they can accumulate on the screen, eliminating or significantly reducing the need for mechanical raking systems. This extraction approach maintains screen performance while avoiding the complexity and maintenance burden of mechanical clearing devices.
Solution Approach 2:
The solids removal system operates automatically using hydraulic principles (such as hydrocyclones utilizing centrifugal force or flotation devices using air bubbles) to separate and remove solids without requiring mechanical raking components or external intervention, thereby simplifying the overall system.
4Duration of action of moving object
If screens are increased in area to handle heavy flooding activity, then screen blockage is delayed, but manufacturing cost and device complexity increase
Solution Approach 1:
The invention extracts and removes solids from the effluent stream using a separate solids removal system, thereby extending screen operation duration during flooding events without requiring increased screen area. This approach reduces manufacturing costs while achieving the desired extended operational duration.
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 venturi device effectively reduces the solids content at the screen, preventing blockages and maintaining screen efficiency, reducing maintenance needs and the risk of undesirable discharges into waterways, thereby enhancing the performance and longevity of CSO systems.
Implementation Method 1
a venturi pipe located between the first fluid outlet and the venturi inlet and in fluid communication with both, wherein the venturi pipe is narrower in cross section than the venturi inlet
Implementation Method 2
the fluid inlet comprises an intake funnel that decreases in width in a direction towards the fluid passageway. The funnel shape facilitates in drawing off of debris across the full width of the screen whilst reducing the hydraulic resistance of the venturi inlet
Data Source
AI summary
The present invention relates to a venturi device for a combined sewage overflow system, the venturi device comprising: a body defining a fluid passageway therethrough, the body having a first end portion defining a fluid inlet; a second end portion opposing the first end portion, the second end portion defining a fluid outlet and an opposing venturi inlet in fluid communication with the fluid outlet: and a mid-portion located between the first and second end portions; and a venturi pipe located between the first fluid outlet and the venturi inlet and in fluid communication with both, wherein the venturi pipe is narrower in cross section than the venturi inlet, and wherein the fluid inlet comprises an intake funnel that decreases in width in a direction towards the fluid passageway. The present invention further provides a CSO system including such a venturi device.