Pump Hydraulic Unit Cutwater Geometry for Clog Prevention
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Solution Overview
Problem
Pumps designed to handle sewage/wastewater often clog due to solid matter like polymers, hygiene articles, and long fibers, which obstruct the impeller and reduce pump efficiency, leading to costly and unplanned maintenance.
Innovation Solution
A hydraulic unit with a cutwater wedge angle of 80-150 degrees and cutwater angle of 15-70 degrees, combined with an axially displaceable impeller, minimizes the risk of solid matter getting caught over the cutwater, allowing undivided solid matter to pass through without disintegration, thus reducing clogging and maintaining pump efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the impeller and impeller seat are positioned at a fixed distance from each other, then the pump structure is simple and reliable, but solid matter obstructs the pump and prevents the impeller from rotating
Solution Approach 1:
The impeller is made axially displaceable relative to the impeller seat through a guide pin mechanism that allows the impeller to move axially within the volute. This dynamic adjustment enables the impeller to accommodate solid matter passage while maintaining reliable operation, resolving the contradiction between fixed structure reliability and operational flexibility for solid matter handling
2Ease of operation
If the impeller is displaceable in the axial direction to allow larger solid matter to pass through, then the pump can handle larger solid matter, but solid matter gets caught over the cutwater and blocks the volute
Solution Approach 1:
The cutwater geometry is optimized with specific angle parameters (cutwater wedge angle ω between 80-150 degrees and cutwater angle Y between 15-70 degrees) to prevent solid matter from catching over the cutwater. This parameter optimization allows the displaceable impeller to handle larger solid matter without causing volute blockage, resolving the contradiction between solid matter passage capability and blockage resistance
3Reliability
If solid matter is disintegrated at the inlet of the pump, then the risk of clogging is reduced, but the energy consumption increases and pump efficiency decreases
Solution Approach 1:
The pump enables solid matter to pass through undivided by providing adequate axial displacement space between the impeller and impeller seat, eliminating the need for preliminary disintegration actions. This approach maintains pump efficiency and reduces energy consumption while preventing clogging, as the solid matter naturally passes through without requiring energy-intensive cutting or tearing operations
Data Source
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AI summary
The invention relates to a hydraualic unit for a pump (1) configured for pumping liquid comprising solid matter, wherein the hydraulic unit comprises an channel impeller (8) and a housing (6) having an axial inlet (2) and a radial outlet (3), the housing (6) defining a volute (4) having a cutwater (16), a cutwater wedge angle (ω) and a cutwater angle (Y), wherein a smallest cross-sectional area of the volute (4) is located in an axial geometrical plane that comprises an axially extending center axis of the inlet (2) of the housing (6) and that extends radially outwards to an upstream end of the cutwater (16). The hydraulic unit is characterized in that in a radial geometrical plane that is perpendicular to an axially extending center axis of the inlet (2) of the housing (6) and that comprises the longest radius of the volute (4) at the smallest cross-sectional area of the volute (4), the cutwater wedge angle (ω) is equal to or greater than 80 degrees and equal to or less than 150 degrees, and the cutwater angle (Y) is equal to or greater than 15 degrees and equal to or less than 70 degrees.