Centrifugal Pump Impeller Balancing Conduit Design
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Solution Overview
Problem
Centrifugal pumps face challenges in maintaining reliable pressure balance and preventing seal damage when pumping liquids with solids, as existing balancing methods are not effective across the entire operating range and can lead to seal drying and increased stress on bearings.
Innovation Solution
The impeller design features balancing conduits with inlet openings inside the leading edges of the working vanes, ensuring they are insensitive to vane pressure, and outlet openings at a smaller radius, promoting flow from the impeller eye to the rear side, reducing recirculation and enhancing heat transfer, while allowing the balancing conduits to be positioned closer to the axis for improved hydraulic efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional balancing holes are used with linear axis parallel to pump axis, then liquid flow from high pressure side to low pressure side is enabled, but pressure balance is not maintained across entire operating range and seal damage occurs
Solution Approach 1:
The balancing hole axis is arranged to be substantially perpendicular to the pump axis, creating a curved flow path through the impeller hub. This curved configuration enables the balancing hole to effectively equalize pressure between the front and rear sides of the impeller across the entire operating range, preventing seal damage while maintaining reliability under varying operating conditions.
Solution Approach 2:
The invention changes the orientation of the balancing hole axis from parallel to perpendicular relative to the pump axis. This dimensional change in the hole's spatial arrangement allows the balancing hole to effectively counteract axial forces and maintain pressure balance across different operating conditions, resolving the contradiction between seal reliability and operating range adaptability.
2Force
If rear vanes are arranged on impeller shroud to reduce axial force, then pressure distribution at both sides of shroud is equalized, but negative pressure is generated at high output and stress increases at low capacity
Solution Approach 1:
The invention extracts the pressure balancing function from the rear vanes and relocates it to balancing holes with perpendicular axes. By removing the reliance on rear vanes for pressure equalization, the system eliminates the generation of negative pressure at high output and excessive stress at low capacity, while still achieving axial force reduction and improving seal and bearing reliability.
Solution Approach 2:
The invention changes the operational parameters of pressure balancing by modifying the balancing hole orientation to be perpendicular to the pump axis. This parameter change enables effective pressure equalization across the entire operating range without the adverse effects of negative pressure generation or excessive stress, thereby improving reliability while managing axial forces.
3Productivity
If balancing holes are positioned closer to impeller eye, then hydraulic efficiency is improved, but pressure balance effectiveness may be reduced
Solution Approach 1:
The perpendicular orientation of the balancing hole axis creates a curved flow path that efficiently connects the front and rear sides of the impeller. This curved configuration allows the balancing hole to be positioned closer to the impeller eye, improving hydraulic efficiency by reducing recirculation, while maintaining pressure balance effectiveness through the optimized perpendicular geometry that ensures proper pressure equalization.
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 minimizes pressure fluctuations, prevents seal drying, ensures reliable heat transfer, and maintains efficient operation across varying capacities, including when pumping solids-containing liquids, by maintaining positive pressure in the sealing space and optimizing hydraulic efficiency.
Implementation Method 1
the liquid or suspension is allowed to flow from the side of the impeller where the pressure is higher to the area of the lower pressure
Implementation Method 2
working vanes of the impeller increase the pressure of the liquid while pumping such from in front of the impeller to the volute radially outside the impeller
Implementation Method 3
the rotating impeller creates suction in the impeller eye tending to move the impeller towards the pump inlet
Implementation Method 4
the liquid between the impeller and the rear wall of the pump rotates, on the average, half the speed of the impeller... while generating centrifugal force, reduces to a certain extent the pressure prevailing in the sealing space behind the impeller
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The present invention relates to an impeller and a centrifugal pump using such. The present invention especially relates to modifying an impeller of a centrifugal pump in such a way that said pump may be used without a risk of damaging a shaft seal or like at capacities higher than that at the optimal operating point. The impeller comprises at least a hub (52) extending radially outwardly in the form of a shroud (54), at least one working vane (56) arranged on the front surface of the hub (52) and the shroud (54), at least one rear vane (60) on the rear surface of the shroud (54), and at least one balancing conduit (58) extending through said hub (52) and shroud (54), the first opening (64) of the balancing conduit (58) in the first face of the impeller hub (52) being located within the circle C formed by the radially innermost part (56e) of the at least one working vane (56), while the impeller (50) is rotated about the axis (8).