Parallel Lubricant Pump System Motor Overload Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Large-sized steam turbines require increased lubricant supply, leading to vibration and delayed response in lubricant systems due to high moment of inertia, and parallel operation of main oil pumps can cause motor overload and shutdown, risking turbine bearing damage.
Innovation Solution
A lubricant system with multiple motor-driven pumps operating in parallel, featuring an error detector and pressure loss addition unit that adjusts the working point of operational pumps to a lower flow side when an error is detected, preventing motor overload and ensuring continuous lubrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a large capacity main oil pump is used to increase lubricant supply, then the lubricant flow to turbine bearings is improved, but vibration increases and response time deteriorates due to increased moment of inertia
Solution Approach 1:
The system divides a single large capacity pump into multiple small capacity pumps operating in parallel. Each pump handles a portion of the total lubricant flow requirement, thereby reducing the moment of inertia of each individual pump while collectively maintaining the required lubricant supply quantity to the turbine bearings.
2Speed
If multiple small capacity main oil pumps operate in parallel to increase lubricant flow, then response time is improved, but motor overload occurs when one pump stops due to error
Solution Approach 1:
The system incorporates an error detector that monitors the operating state of each motor and provides feedback to the controller. When an error is detected in one motor, the controller adjusts the operating conditions of the remaining motors to prevent overload, ensuring continuous reliable operation.
Solution Approach 2:
The controller changes the operating parameters (flow rate and head) of the remaining healthy pumps when one pump fails. By adjusting these parameters, the system prevents the remaining motors from exceeding their rated power while maintaining sufficient lubricant supply.
3Stress or pressure
If one main oil pump stops due to error in a parallel system, then the remaining pumps increase flow to balance head, but motor power exceeds rated power causing shutdown
Solution Approach 1:
The error detector continuously monitors motor operating states and provides feedback to the controller. When one pump stops, the controller receives this feedback and immediately adjusts the operating parameters of the remaining pumps to prevent motor overload while maintaining head balance.
Solution Approach 2:
The controller dynamically changes the operating parameters of the remaining healthy pumps when a pump failure occurs. By adjusting flow rate and head parameters, the system maintains head balance without causing the motor power to exceed rated power, preventing motor shutdown.
Data Source
AI summary
There is proposed a lubricant system having a plurality of motor-driven pumps operating in parallel as main oil pumps, wherein even if at least one of the main oil pumps stops, the other normally operating main oil pumps do not stop due to overload of a motor. A lubricant system 7 comprises a hydraulic pressure piping 9, a plurality of lubricant pumps 10 arranged in parallel, a plurality of AC motors 11 driving each of the lubricant pumps 10, an error detector 24 detecting a presence or absence of an error in an operating state of each of the AC motors 11, a pressure loss addition unit 25 configured to increase pressure loss in the hydraulic pressure piping 9, and a controller 26 causing the pressure loss addition unit 25 to increase pressure loss when the error detector 24 detects an error in at least one of the AC motors 11. When an error occurs in at least one of the AC motors 11, the lubricant system 7 changes each working point of the lubricant pumps 10 driven by another AC motor 11 to a lower flow side than that in a steady operation.