Oil-free Screw Compressor Shaft Sealing Design
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Solution Overview
Problem
Oil-free screw compressors face challenges with shaft-sealing reliability and cost due to the dissolution of heavy hydrocarbon gases in lubricating oils, leading to viscosity reduction and potential bearing damage, as well as the risk of oil mixing into the compression chamber and gas leakage.
Innovation Solution
The implementation of shaft-sealing portions on both sides of the compressor chamber, utilizing a gas-transfer line to maintain separation between the compression chamber and bearings, and employing a single inside/outside shaft-sealing portion to reduce leakage risks, along with the use of inert gases like nitrogen to prevent oil mixing and corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shaft-sealing portions are installed at four positions to prevent oil mixing and gas leakage, then sealing reliability improves, but device complexity and cost increase
Solution Approach 1:
The patent merges multiple shaft-sealing functions into a single integrated shaft-sealing portion. This single component performs the sealing functions that would otherwise require four separate shaft-sealing portions, thereby reducing device complexity and cost while maintaining the necessary sealing reliability to prevent oil mixing and gas leakage.
Solution Approach 2:
The single shaft-sealing portion is designed to perform multiple sealing functions simultaneously. It seals against both oil injection portions and process gas supply/source, effectively replacing multiple specialized seals with one multi-functional component that maintains reliability across all sealing requirements.
2Temperature
If lubricating oil temperature is increased to prevent heavy hydrocarbon gas liquefaction, then discharge temperature increases, but lubricating oil viscosity decreases causing bearing damage
Solution Approach 1:
The patent segments the temperature control function by introducing a separate temperature management system for the lubricating oil. The oil temperature is controlled independently from the discharge temperature through dedicated cooling mechanisms, allowing the discharge temperature to be increased for gas liquefaction prevention while the oil temperature is maintained separately to preserve lubricating viscosity and bearing reliability.
Solution Approach 2:
The patent introduces a temperature control system as an intermediary between the compression process and the lubricating oil. This intermediary system manages the thermal relationship, allowing the compression chamber to operate at higher temperatures for gas liquefaction prevention while the lubricating oil is maintained at appropriate temperatures through separate cooling pathways, thus preventing viscosity loss and bearing damage.
3Reliability
If lubricating oil temperature is lowered to maintain viscosity, then bearing reliability improves, but heavy hydrocarbon gas condenses in oil recovery device causing lubricating oil scattering
Solution Approach 1:
The patent segments the temperature control functions by implementing separate temperature management for the lubricating oil and the process gas. The lubricating oil is cooled independently to maintain viscosity and bearing reliability, while the process gas temperature is managed separately to prevent condensation in the oil recovery device. This segmentation eliminates the trade-off between bearing reliability and oil scattering.
Solution Approach 2:
The patent introduces separate temperature control systems as intermediaries for the lubricating oil and process gas pathways. The oil cooling system acts as an intermediary that maintains oil viscosity without affecting the process gas temperature, thereby preventing both bearing damage from high oil temperature and oil scattering from gas condensation.
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 configuration enhances the reliability and cost-effectiveness of shaft-sealing, prevents oil mixing and gas leakage, maintains viscosity, and avoids bearing damage by reducing the dissolution of heavy hydrocarbons in lubricating oils, ensuring an oil-free compression process.
Implementation Method 1
utilizing a gas-transfer line to maintain separation between the compression chamber and bearings
Implementation Method 2
shaft-sealing portions on both sides of the compressor chamber... preventing oil mixing
Implementation Method 3
the process gas on the discharge side of the compression chamber flows out to the suction port return line from the shaft-sealing portion
Implementation Method 4
preventing bearing damages due to a reduction of viscosity in lubricating oil caused by dissolution of a heavy hydrocarbon gas into the lubricating oil
Implementation Method 5
a process gas from a process-gas supply source is compressed and supplied to a supply end
Data Source
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AI summary
A screw compressor (10) provided with a compressor body (11), an oil supply tank (13), an oil supply line (60), and an oil recovery line (59), wherein the screw compressor is also provided with shaft seal sections (28, 41) located on opposite sides, in the direction of shafts (26, 38), of a compression chamber (24) of a screw rotor (25) and preventing both mixing of oil in bearings (27, 39, 40) into a compression chamber (24) and leakage of process gas from the compression chamber (24), a suction-opening return line (52) for interconnecting the shaft seal section (41) on the discharge side of the compression chamber (24) and a suction opening (17) of the compressor body (11), a supply-process-gas communicating line (61) for interconnecting the suction opening (17) of the compressor body (11) and the upper part of the oil supply tank (13), and a shaft seal section (53); for dividing between the inside of the compressor body (11) and an atmospheric environment. The non-lubricated screw compressor (10, 70, 80) has the shaft seal sections (28, 41) which is inexpensive and highly reliable, which can prevent damage to the bearings (27, 39, 40) due to a reduction in the viscosity of lubricating oil, and which can prevent liquefaction of heavy hydrocarbon in a discharge system.