Application details and installation precautions of screw air compressor oil and gas separator

Application technology of oil-gas separator core

The oil content of the air outlet of the air compressor is not only related to the quality of the oil-gas separator core, but also related to the design of the oil drum. The matching of the air outlet flow of the air compressor and the processing flow of the oil-gas separator core is also very important.

1. Matching of oil-gas separator core and air compressor

Under normal circumstances, the oil-air separator core of the air compressor must be selected to be greater than or equal to the air outlet flow rate of the air compressor, so as to prevent the fine dust that cannot be filtered by the air filter inhaled during use from damaging the fine separation layer of the oil-air separator core. The upper blockage, thereby reducing the treatment flow of the oil-gas separator core, causes the early pressure difference of the oil-gas separator core to be too large. The most suitable for supporting the oil-gas separator core is more than 105% of the compressed air outlet flow.

2. The service life of the oil-gas separator core

Aging oil deposits, airborne pollutants and particles from wear will all affect the service life of the oil separator core. The user’s working conditions are different, and the required final pressure difference is also different. In actual use, the final pressure difference of the oil-gas separator core for the compressor is 0.8-1 bar, and that of the vacuum pump is 0.5 bar. The accumulation of dirt on the oil separator core also increases at higher oil flow rates. This can be measured by blowdown flow. The amount of blowdown is directly related to the pre-separation structure design of the compressor. The best value of sewage discharge is usually about 1 gram per cubic meter of oil. Therefore, the service life of the oil-gas separator core cannot be measured completely by time, and only the final pressure difference of the oil-gas separator core is used to determine the service life.

3. Ensure the service life of the oil-gas separator core

Correct maintenance of lubricating oil is an important condition to ensure a satisfactory service life of the oil-gas separator core. In general, the service life of the oil and gas separator core is only limited by the solid particle deposits (oil oxides, particles produced by wear, etc.) on the fine separation layer, which eventually leads to a large pressure difference. Contamination in lubricating oil can be reduced by changing air filters, oil filters and observing oil change intervals. In this way, the dirt entering the core of the oil-gas separator can be kept at a minimum level, which is beneficial to prolonging the period of maintenance and maintenance. The selection of oil has a great relationship with the service life of the oil-gas separator core. Use only those approved, age-resistant and water-insensitive lubricants. Lubricating oil with poor oxidation resistance is not suitable. Even if the working time is short, a viscous sediment similar to jelly will be produced, which will block the core of the oil and gas separator. Higher working temperature will accelerate the aging of lubricating oil, so sufficient attention must be paid to the cooling air volume and the dirt of the cooler. When changing the engine oil, the used oil must be completely drained to avoid contamination of the new engine oil or incompatibility between new and old engine oil. In rare cases, premature oil aging due to gaseous impurities in the ambient air can also occur.

4. Fuel consumption of air compressor

Some working conditions and critical conditions that affect the oil level of the air compressor oil storage tank, such as the volatilization process of oil, the effect of pre-separation and oil return system, will cause short-term or long-term increase in oil consumption.

Excessive oil level in the oil storage tank will have similar results, if there is no obvious separation area between oil and gas temporarily or permanently, it will impair the pre-separation of oil droplet effect, and it will also increase the air downstream of the oil-air separator core. residual oil in.

When the oil temperature is low or slow volatilizing lubricating oil is used, excessive refueling will also cause a large amount of oil foam to pass through the oil separation core, and the oil and gas separator core will inevitably increase oil consumption. Under the condition of normal operating temperature of 800C, the soot content of some types or brands of lubricating oil can reach 10mg/m3.

5. Design of oil storage tank

The role of the oil storage tank in the air compressor system is to store the oil of the compressor, and at the same time buffer the flow rate of the compressed air, and it is the separation of the front-stage liquid oil of the oil-gas separator core. The oil storage tank is the decisive factor for the oil-gas separator core to deal with the oil content. The rational design of the oil storage tank is to reduce the oil content of the compressed air. If the design is improper, the oil content of the exhaust gas will increase, and the loss of energy will be increased at the same time. So, how can the equipment of the air compressor reduce the loss of energy, and how can the design of the oil storage tank be considered reasonable? The oil storage tanks designed for different brands of air compressors are different. In the design of the oil storage tank, the following parameters should be paid attention to:

(1) Understand the air outlet flow rate of the compressor head and the oil injection flow rate required by the compressor head. The parameters can be obtained from the compressor head manufacturer.

(2) The flow rate of the compressed air before entering the oil storage tank at 7 bar pressure is required to be in the range of V=15-25m/s. At this time, it is necessary to calculate the diameter of the pipe from the compressor head to the oil storage tank.

(3) When the compressed air is at a pressure of 7bar, the maximum flow velocity in the oil storage tank is required to be V1=5m/s. At this time, the pipe diameter required for the flow velocity before entering the oil storage tank and the flow velocity in the oil storage tank must be calculated. What is needed is the diameter of the oil storage tank. The centrifugal force, speed and direction generated by the compressed air with liquid oil entering the oil storage tank are used to calculate the remaining oil content of the compressed air.

(4) The flow rate of the compressed air entering the oil-gas separator core in the oil storage tank is controlled at V2=0.7m/s, and the oil content of the compressed air entering the oil-gas separator core is within 5-10g/m3, which can be The amount of oil collected on the oil return line is used to measure the oil content of the compressed air entering the oil separator core.

(5) Calculate the oil injection quantity required by the air compressor, and the distance from the oil surface of the oil in the oil storage tank to the bottom of the oil-gas separator core should not be less than 30cm. Otherwise, the oil treatment of the oil-air separator core will be increased, resulting in an increase in the oil content of the compressed air.

The design parameters of the oil storage tank are calculated by referring to the treatment flow rate and oil content of the oil-gas separator core of a certain foreign group, and the flow rate is calculated according to the DIN1945 standard (under 7bar working pressure).

Summary and analysis of problems that should be paid attention to during use

1. The core pressure difference of the oil-gas separator exceeds 1bar

During the use of the oil-air separator core, the normal pressure difference of the newly installed oil-air separator core for the first use should be 0.17-0.3bar, and it is abnormal if it exceeds 0.3bar. At this time, check the minimum pressure valve of the air compressor or other air systems. Whether the spare parts are damaged.

In the process of using the oil-gas separator core, the pressure difference is too large in a short period of time. It is not normal for the pressure difference of the oil-gas separator core to be greater than 0.8 bar. At this time, check whether the air system of the air compressor has In case of short circuit, check whether the air filter used in the air compressor can filter 95% of 5-6um impurities and 99.8% of 7-10um impurities, otherwise the oil-gas separator core will appear early in use Pressure difference > 0.8bar or more. In addition, whether the air compressor has cleaned the compressed air system and the oil circuit system after the overhaul, and the two major systems of the air compressor have no obvious faults, which will cause the early pressure difference of the oil-gas separator core to be too large during use.

In the process of using the oil-gas separator core, the separation layer can have a certain amount of dust. When the air compressor is continuously used, there are many dust particles less than 5um entering the fine separation layer of the oil-gas separator core. Not only the treatment flow rate of the fine separation layer is constantly decreasing, but also the pressure difference of the oil-gas separator core is constantly increasing. The oil-gas separator core reaches a pressure difference of 1 bar in normal use, and the oil-gas separator core needs to be replaced at this time.

Whether the anti-oxidation ability of lubricating oil meets the standard, whether it has excellent thermal stability and oxidation stability, and resists oil decomposition and sludge generation. Improper use of lubricating oil will also increase the pressure difference of the oil-gas separator core.

2. The oil-gas separator core handles oil content greater than 10ppm

During the use of the oil-gas separator core, the compressed air containing liquid oil filtered by the oil-gas separator core should have an ideal oil content within 3ppm. Before using the oil-gas separator core, it is necessary to know whether the outlet air flow of the air compressor matches the treatment flow of the oil-air separator core. The configuration of the oil-air separator core must be greater than or equal to the air compressor outlet air flow. The same type of oil-gas separator core is used on different brands of air compressors, and the oil content of the oil-gas separator core is different. Because the air compressor brand is different, the design of its oil storage tank is also different, and the oil content of the oil-gas separator core is related to the design of the oil storage tank.

If the oil content of the compressed air is more than 10ppm/m3min, attention must be paid to the amount of oil in the oil storage tank and the temperature of the oil in the air compressor, and stop the air compressor for inspection if necessary. Check whether the oil return pipe of the air compressor is blocked, whether the seal is damaged and whether the oil volume of the oil storage tank is in a reasonable position, etc. Usually the oil content of the compressed air can be clearly seen from the sewage.

Whether the lubricating oil used has good air release property, avoids cavitation, and maintains the maximum compression rate. Whether there is low foam, carefully selected additives to ensure rapid separation of air, will not form excessive foam layer, whether it has excellent water separation.

3. Combustion and explosion occurred in the oil-gas separator core

In the process of using the oil-gas separator core, occasionally there will be combustion or explosion in the oil storage tank, which is not caused by the oil-gas separator core. Since the core of the oil-gas separator itself will not ignite spontaneously, it will burn and explode only if the two factors of fire and combustion-supporting gas exist at the same time. In addition, the friction of the oil-gas separator core through the flow velocity of the gas will generate static electricity. The greater the static electricity, the greater the danger. bigger. Therefore, manufacturers who produce oil and gas separator cores will install conductive sheets. Unless there is no reinforced electrostatic sheet on the flange gasket of the oil-gas separator core to conduct electricity during installation, the resulting static electricity cannot be dissipated.

In the process of using the oil and gas separator core, it is necessary to prevent fire in the oil storage tank. First of all, the conductive sheet is reinforced on the flange gasket of the oil-gas separator core, and the performance of the vaporization amount of the compressor lubricating oil used must meet the international standard. Secondly, before installing the oil-gas separator core, the impurities of the two major systems and the welding slag on the welding seam must be cleaned, especially the welding slag on the welding seam of the new machine must be cleaned. Because the air compressor will generate high temperature and high pressure during operation, and the high-speed gas circulation will easily separate the clean and unclean welding slag, and produce sparks through collision with metal parts. Again, it is necessary to always pay attention to whether the noise from the air compressor is normal during operation, and prevent the sparks caused by the collision of metal particles and metal parts produced by the wear and tear of the moving parts of the air compressor.

Does the lubricating oil have outstanding oxidation stability to prevent valves and other components from forming carbon deposits and varnish, which are by-products of oxidation reactions under high temperature and pressure conditions (such as iron oxides and hydroxides). These deposits can cause serious damage to air compressors, reducing efficiency and increasing maintenance costs.

Whether the lubricating oil prevents fire and explosion accidents. In the exhaust pipe of the compressor head, the mixture of carbon deposits and rust particles can undergo exothermic reaction under the action of compressed air heat, resulting in fire and explosion.

4. The normal adaptation pressure is greater than 5bar

The air pressure normally used in the factory cannot be <5bar, because the treatment flow of the oil-gas separator core is calculated according to the standard 7bar pressure, and the treatment flow of the oil-gas separator core is calculated according to the DIN1945 standard. Generally speaking, the selection of the oil-gas separator core must be configured according to more than 105% of the output air flow of the air compressor, and the processing capacity of the oil-gas separator core is related to the pressure and flow rate of the compressed air used. In the matching oil-gas separator The lower the core down pressure, the worse the treatment effect of the oil-gas separator core. Therefore, the oil-gas separator core must be used above 5.5bar for a long time, otherwise the oil content of the air treated by the oil-gas separator core will hardly reach the effect of 3ppm.

Precautions for installation three

a) When installing the oil-air separator core, apply a small amount of lubricating oil on the surface of the seal.

b) To install the spin-on oil-gas separator core, just tighten it clockwise by hand.

c) When installing the built-in oil-gas separator core, the flange gasket of the oil-gas separator core must be equipped with conductive sheets or graphite gaskets.

d) When installing the built-in oil-gas separator core, pay attention to whether the oil return pipe extends 2-3mm from the center bottom of the oil-gas separator core.

e) Pay attention to whether there is residual pressure inside when removing the oil-air separator core.

f) Compressed air containing oil must not be directly sprayed against the core of the oil-air separator.

Sollant Group-Professional Compressed Gas Solutions Provider