A gas bearing centrifugal compressor

Abstract

The invention discloses a gas bearing and a gas bearing centrifugal compressor, which relate to the technical field of compressors. The centrifugal compressor is a semi-hermetic centrifugal compressor with gas bearings. The gas radial bearings are distributed on both sides of the span of the motor rotor or shaft. The radial bearings at the impeller end and the gas radial bearings at the non-impeller end provide radial load. The gas thrust bearing provides a positive thrust towards the impeller end. When the centrifugal compressor operates stably under various high and low pressure differential conditions, the direction of the shafting force caused by the gas is towards the non-impeller end, so the thrust bearing provides In order for the thrust force to overcome the gas force of the shaft system, the pressure of the oil tank is balanced to the low-pressure evaporation pressure side through the balance pipe, and the low-pressure lubricating oil is raised to a higher pressure through the action of the oil pump to realize the oil supply of the oil film bearing. The differential oil supply pressure is the difference between the oil supply pressure and the evaporation pressure.

Description

technical field [0001] The invention relates to the technical field of compressors, in particular to a gas bearing centrifugal compressor. Background technique [0002] Gas bearings have been used in the design of centrifugal compressors in refrigeration systems. Gas bearings can be equipped with land bearings, such as corrugated landing bearings, ball landing bearings, wear-resistant bushings, etc., when the shaft system rotates to low speed before and at the beginning At this time, the compressor and the refrigeration system have not yet established a large enough high and low pressure difference, and there is mechanical dry friction between the landing bearings such as the wear-resistant bearing bushes supported by corrugated sheets and the rotating shaft. When the shaft system of the centrifugal compressor rotates The speed gradually increases, and after the centrifugal compressor establishes a large enough high-low pressure difference, then part of the refrigerant gas d...

AI Technical Summary

Problems solved by technology

[0007] (1) The gas supply source of the gas bearing is to draw gas directly from the high-pressure side of the exhaust pressure of the refrigeration system, the intermediate pressure side of the economizer, or the low-pressure side of the evaporator, and then pressurized by the gas pump and then pumped into the gas bearing. And the inertness is small, the temperature, pressure, and flow of the gas supply cannot be controlled constantly; because the fluctuations of the temperature, pressure, and flow of the gas are much larger than the fluctuations of the liquid, the unstable state of the gas intake can easily lead to an unstable state of the gas output. Stablize

[0008] (2) In some designs, the gas pump only runs for a certain period of time when the pressure difference is established after starting and starting. Once the compressor is started, the operation of the refrigeration system is stable, and the gas pump is not put into operation after the high and low pressure difference is stable. At this time, the amount of gas introduced into the gas bearing, gas temperature and pressure all change with the operating conditions and load of the refrigeration system, so the operation of the gas dynamic pressure bearing is not stable, resulting in reliability, stability and adaptability many problems

[0009] (3) The density of the gas is low and the volumetric flow rate is small. When the inlet pressure and flow rate of the gas pump change greatly, the exhaust pressure control of the gas pump is not stable by changing the speed and flow rate of the gas pump, which is affected by the back pressure. ;Once the flow rate of the suction port is small and the back pressure is high, no matter the operation of the gas pump is changed, the exhaust pressure will fluctuate periodically and return;

[0010] (4) The density of the gas is small, and sometimes it is necessary to configure a large-volume gas pump to pressurize the gas with a large flow rate, resulting in larger pipelines and volume of the unit, and poor economy

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