Multistage Centrifugal Grinder Pump Semi-Open Diffuser Design
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Solution Overview
Problem
Centrifugal grinder pumps face efficiency reduction and potential clogging due to fibrous and solid materials in sewage, requiring measures to prevent blockages and maintain hydraulic efficiency, especially when high head and flow rates are needed.
Innovation Solution
A multistage centrifugal grinder pump design with two impellers in series and a semi-open diffuser to guide fluid flow, eliminating the need for an external interstage conduit, enhancing compactness and preventing clogging by ensuring an open path for fluid flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If an external interstage conduit is used to guide fluid from the first stage volute to the second stage volute, then the pump can achieve high head, but the device occupies a lot of space
Solution Approach 1:
The patent merges the interstage conduit function into the pump housing structure itself. The housing integrates the fluid passage from the first stage volute discharge to the second stage volute inlet, eliminating the need for a separate external conduit and reducing overall device footprint while maintaining high head capability
Solution Approach 2:
The pump housing serves multiple functions: it contains the impellers, provides structural support, and acts as the interstage conduit for fluid flow. This multi-functional design eliminates the need for dedicated external piping between stages, compacting the overall device
2Reliability
If a closed diffusor is used to guide fluid between impellers, then the structure is complete, but solid constituents may get stuck and cause clogging
Solution Approach 1:
The patent removes the bottom closure of the diffusor, creating an open-bottom design. This extraction of the closing element prevents solid constituents from becoming trapped in the diffusor, allowing them to pass through freely while the diffusor still performs its fluid guidance function
Solution Approach 2:
The diffusor is designed as a semi-open structure with discrete walls (side walls and top wall) rather than a complete enclosure. This segmented approach maintains the necessary fluid guidance functionality while creating open passages that prevent clogging by solids
3Stress or pressure
If a single impeller is used, then the device is simple, but the head-flow range is limited and cannot achieve high head
Solution Approach 1:
The pump uses two separate impellers arranged in series, each contributing to the total head generation. This segmentation of the pumping function across multiple stages enables high head achievement while maintaining reasonable flow rates, as each impeller handles a portion of the total head requirement
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 significantly increases the pump's head-flow range, allowing operation with high heads up to 200 feet while maintaining efficiency and preventing clogging, making it suitable for applications requiring high head and flow rates.
Implementation Method 1
a first stage impeller for rotating about an axial direction, a second stage impeller for rotating about the axial direction
Implementation Method 2
a stationary diffusor arranged with respect to the axial direction between the first stage impeller and the second stage impeller for guiding the fluid from the first stage impeller to the second stage impeller
Data Source
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AI summary
A multistage centrifugal grinder pump is proposed, comprising a housing (2) with a pump inlet (3) for a fluid to be conveyed, and a pump outlet (4) for discharging the fluid, further comprising a grinder (5) arranged at the pump inlet (3) for grinding constituents of the fluid, a first stage impeller (6) for rotating about an axial direction (A), a second stage impeller (7) for rotating about the axial direction (A), a stationary diffusor (9) arranged with respect to the axial direction between the first stage impeller (6) and the second stage impeller (7) for guiding the fluid from the first stage impeller (6) to the second stage impeller (7), and a shaft (8) for rotating the first stage impeller (6), the second stage impeller (7) and the grinder (5), wherein the first stage impeller (6) and the second stage impeller (7) are arranged in series and are connected to the shaft (8) in a torque-proof manner, wherein the diffusor (9) is designed as a semi-open diffusor (9) having a top wall (92), a radially outer annular side wall (93), and an open bottom side (91) facing the first stage impeller (6), wherein the top wall (92) is arranged adjacently to the second stage impeller (7), wherein the top wall (92) has a central outlet opening (97) surrounding the shaft (8), and wherein the open bottom side (91) extends beyond the first stage impeller (6) with respect to a radial direction.