Gearbox Negative-Pressure Oil Return for Centrifugal Compressors
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Solution Overview
Problem
In gear speed-increasing centrifugal compressor units, inefficient oil discharge from the gearbox leads to power dissipation, mechanical loss, and high lubrication oil temperatures due to poor lubrication and cooling, necessitating rapid and efficient oil return to improve operational efficiency and reduce mechanical loss.
Innovation Solution
A negative-pressure balance system for the gearbox, comprising a respirator connected to a hermetically-sealed low-level oil collecting tank and an oil demister with a ventilation device, creates a negative pressure environment within the gearbox and oil collecting tank to facilitate quick oil return through a U-shaped negative-pressure balance pipe, ensuring balanced pressure and efficient lubrication cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the gearbox operates at high speed with traditional oil discharge systems, then the impeller can achieve high rotation speed, but the lubricating oil accumulates at the bottom of the gearbox causing poor draining and mechanical loss
Solution Approach 1:
The patent applies pneumatic principles by using a vacuum pump to create negative pressure in the oil collecting tank, which actively draws lubricating oil from the gearbox through the oil conduit. This pneumatic suction mechanism replaces traditional gravity-dependent drainage, enabling efficient oil removal even during high-speed operation when centrifugal forces would otherwise cause oil accumulation and poor draining.
2Reliability
If the gearbox is sealed to prevent contamination, then protection against external contaminants is improved, but oil discharge efficiency deteriorates due to pressure buildup
Solution Approach 1:
The patent introduces a respirator as an intermediary device that connects the sealed gearbox to the external environment. The respirator includes a filter that allows air exchange while blocking contaminants, and it communicates with the oil collecting tank to balance pressure. This intermediary enables the gearbox to remain sealed for contamination protection while still allowing efficient oil discharge through the negative pressure system.
3Reliability
If a hermetically-sealed oil collecting tank is used, then contamination is prevented, but negative pressure establishment becomes more difficult
Solution Approach 1:
The patent implements a feedback mechanism where the vacuum pump continuously monitors and maintains negative pressure in the hermetically-sealed oil collecting tank. The pressure difference created by the vacuum pump overcomes the sealing, and the system automatically adjusts to maintain the required negative pressure level, enabling both contamination prevention and efficient oil discharge despite the increased complexity.
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 system achieves rapid oil return at lubricating points, reducing mechanical loss and enhancing operational efficiency by maintaining balanced negative pressure within the gearbox, preventing oil accumulation and ensuring effective lubrication and cooling.
Implementation Method 1
the volume of ventilated air of the oil demister in operation is greater than the leakage amount from the internal space of the gearbox, to establish a negative pressure not only in the low-level oil collecting tank, but also in the internal space of the gearbox
Implementation Method 2
under the combined action of the difference between front and rear oil pressures and the negative pressure in the gearbox, the lubricating oil flows quickly to the bottom of the gearbox and flows back to the low-level oil collecting tank
Implementation Method 3
The filter cylinder is provided with filter material, and the ventilation device is arranged on the filter cylinder
Data Source
AI summary
A negative-pressure balance system for a gearbox of a centrifugal compressor includes the gearbox, a hermetically-sealed low-level oil collecting tank and a U-shaped negative-pressure balance pipe. The gearbox is connected to a respirator, and the back pressure of the respirator is a local ambient atmospheric pressure. The bottom of the gearbox and the low-level oil collecting tank are connected by an oil conduit. An oil demister communicated with the low-level oil collecting tank is mounted at the top of the low-level oil collecting tank. The oil demister at least includes a ventilation device. The respirator is communicated with a front-end lubricating point in the gearbox. One end of the U-shaped negative-pressure balance pipe is communicated with the respirator, and the other end of the U-shaped negative-pressure balance pipe is communicated with a rear-end lubricating point in the gearbox.