Centrifugal Pump Balancing Layout for Axial Thrust and Leakage
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Solution Overview
Problem
Centrifugal pumps face challenges with axial thrust bearings experiencing increased friction, wear, complex construction, misalignment vulnerabilities, limited shock and vibration absorption, and high costs, particularly in applications requiring large head and high efficiency, such as seawater desalination by reverse osmosis.
Innovation Solution
A centrifugal pump design featuring a balance drum at the drive end and a balance disk at the non-drive end, with a reduced diameter balance disk and product lubricated bearings, minimizing friction losses and leakage, and utilizing a rotating bushing and stationary bushing for radial bearing support, reducing the need for external lubrication and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If axial thrust bearings are used to handle axial thrust, then axial thrust is compensated, but friction and wear increase
Solution Approach 1:
The patent uses hydraulic principles by introducing a balance disk with a chamber that collects fluid under pressure from the impeller outlet. This fluid pressure acts on the balance disk to generate a counteracting force against the axial thrust, replacing mechanical bearing contact with a fluid-pressure-based compensation mechanism, thereby reducing friction and wear.
Solution Approach 2:
The balance disk acts as an intermediary element between the impeller and the axial thrust bearing. Instead of directly loading the bearing with axial thrust, the balance disk intercepts this force through hydraulic pressure and transfers it to a reaction mass, effectively mediating the thrust compensation and reducing direct mechanical contact.
2Reliability
If axial thrust bearings are used to handle axial thrust, then axial thrust is compensated, but construction complexity increases
Solution Approach 1:
The patent extracts the thrust compensation function from the axial thrust bearing and relocates it to a separate balance disk mechanism. This separates the balancing function from the supporting function, allowing the bearing to focus on support while the balance disk handles thrust compensation, thereby simplifying the overall construction.
Solution Approach 2:
By using hydraulic pressure from the pumped fluid to generate the counteracting force on the balance disk, the system replaces complex mechanical thrust bearing construction with a simpler hydraulic balancing mechanism, reducing the number of moving parts and assembly complexity.
3Reliability
If balance disk diameter is increased to ensure high operational reliability, then thrust compensation improves, but leakage flow increases
Solution Approach 1:
The patent applies partial action by using a balance disk with a diameter that provides sufficient thrust compensation without excessively large dimensions. The balance disk is designed to handle the axial thrust through optimized hydraulic pressure distribution, avoiding the need for oversized disks that would cause excessive leakage and efficiency losses.
4Reliability
If balance disk diameter is increased to ensure high operational reliability, then thrust compensation improves, but pump efficiency decreases
Solution Approach 1:
The patent uses partial action by optimizing the balance disk diameter to provide adequate thrust compensation without excessive size. This optimized sizing minimizes the radial gap and associated friction losses while maintaining sufficient counteracting force, thereby preserving pump efficiency while ensuring operational reliability.
Data Source
AI summary
A centrifugal pump includes a housing including a pump inlet and a pump outlet, a rotor arranged in the housing, and including an impeller to convey fluid from the inlet to the outlet and a pump shaft extending from a first end to a second end, the impeller fixedly connected to the pump shaft, a balance disk fixedly connected to the first end of the pump shaft and cooperating with a stationary counter ring, to provide a radial gap between the balance disk and the counter ring, so that a movement of the pump shaft in the axial direction closes or opens the radial gap, and a balance drum fixedly connected to the pump shaft adjacent the second end of the pump shaft and cooperating with a stationary counterpart to provide an axial gap between the balance drum and the counterpart.