1. Increased clearance
A. The distance between the yin and yang rotors of the main engine increases. The direct consequence is that the leakage (i.e. back leakage) of the compressor increases during the compression process, and the volume of compressed air discharged from the machine becomes smaller. In terms of efficiency, the compression efficiency of the compressor is reduced.
B. The increase in the gap between the yin and yang rotors and the rear end cover and bearing will mainly affect the sealing and compression efficiency of the compressor, and will also have a great impact on the service life of the yin and yang rotors, because many mechanical failures are initially caused by the gap between the bearing and the main shaft.
2. Increased wear
It is well known that as long as the machine is running, there will be wear. Under normal circumstances, the wear will be reduced a lot because of the lubrication of the lubricant, but the wear will slowly increase with long-term high-speed operation. Take high-end bearings as an example: under almost impossible conditions (such as long-term idling, the lubricant is clean enough, the cooling system is good enough, and the temperature and humidity of the operating environment, etc.), it can only be guaranteed for a few years. As for the main engine of the compressor, in addition to the bearings, there are also wears of other parts. If the correct preventive measures are not taken for slight wear, it is easy to cause increased wear and damage and wear of other major components.
3. Component deformation
The main engine of the air compressor is the core compression component of the compressor. Its internal components are in a high temperature and high pressure environment for a long time. Coupled with high-speed operation, the deformation of the components will inevitably occur over time. At the same time, the cause of deformation is also the use environment factor. The air in the environment where the air compressor is generally used will have dust and impurities. After these fine solid substances enter the machine, if they accumulate over time and form larger solid blocks, they may cause the yin and yang rotors to deform and the gap to increase. In severe cases, the main engine will be stuck.
4. Component damage
The vulnerable parts of the main engine of the air compressor are mainly: various gaskets, sealing rings, shaft oil seals, etc., especially the shaft oil seal, which is in a high temperature, high pressure, and high-speed operation environment for a long time, and its service life is greatly shortened. The direct consequence of its damage is oil leakage in the compressor. If it is not discovered in time, the yin and yang rotors and bearings will burn due to lack of lubrication.
5. Increased costs
The cost here refers to maintenance costs and electricity costs. Since the air compressor main engine has not been overhauled for a long time, the parts are worn out and some impurities are left in the main engine cavity, which will shorten the life of the lubricant. At the same time, due to impurities, the service life of the oil-gas separator core and the oil filter period is greatly shortened, resulting in increased maintenance costs. In terms of electricity costs, due to increased friction and reduced compression efficiency, electricity costs will inevitably increase. In addition, the decrease in gas volume and compressed air quality caused by the compressor main engine will also indirectly increase production costs.
Therefore, the consequences of the air compressor main engine not being overhauled after long-term operation may not only cause serious damage to the compressor body, but also pose serious safety hazards. At the same time, it will cause serious direct and indirect economic losses to production. Therefore, it is necessary and necessary to carry out preventive overhaul of the air compressor main engine after a certain period of operation.
6. Judgment and specific content of air compressor overhaul
The general life of screw air compressors is about 30 years, but in actual production, due to long-term maintenance and inadequate repair, many screw machines that have only been used for 10 years or even shorter not only have poor operating conditions, huge power consumption, constant failures, and high operating costs, but many users even classify them as "units to be scrapped". At present, there are two main methods for judging the main engine overhaul in the air compressor industry:
Judgment based on the running time of the unit: the main engine must be overhauled after the running time of the air compressor unit reaches 20,000 hours or it has been put into operation for 4 years.
Judgment based on the actual operation detection and analysis of the unit: By conducting corresponding data detection and analysis on the unit's operating parameters such as noise, operating current, operating temperature, exhaust volume, main engine vibration, etc., it is determined whether the main engine overhaul is required.