How to select lubricate oil for compressor--Application of oil in compressor
Application of synthetic oil in compressor
The compression medium of the compressor includes air, hydrocarbon gas, chemical processing gas, inert gas, industrial gas and refrigerant gas. The synthetic oil for gas compressor is introduced according to different compression medium.
(1) Centrifugal air compressor
Synthetic and hydrocracked saturated hydrocarbons are used for lubrication of seals, gears and bearings of centrifugal air compressors. The main purpose of using synthetic oil in this kind of compressor is to save energy. Some industrial gas plants use high-power (up to 5.88mw) centrifugal air compressors with a total power consumption of 43800 USD / month.
Pao has long hydrolytic stability and excellent water separation. With Pao, the annual energy-saving cost can compensate for the increased cost of 9 months due to the use of synthetic oil. In addition, it can extend the oil change cycle, extend the service life and maintenance interval of oil filter, and reduce the downtime.
Based on safety factors, synthetic oil is selected in explosive plant. The special Pao has good chemical stability, can prevent nitrification and make the compressor safe. Chinese style
(2) Rotary vane air compressor
ISO 68 viscosity polyol ester can be used in high temperature rotary vane air compressor. This kind of compressor operates continuously at low pressure and 315.6 ℃. The working temperature of lubricating oil is 148.9 ℃.
(3) Screw air compressor
Use food grade Pao base oil to prepare air compressor lubricating oil in contact with food, which complies with FDA regulation 21cfr178.3570. The service life of the original food grade screw air compressor lubricating oil is 4000H. After adding FDA compliant additives, the lubrication life of food grade Pao in compressor is up to 8000h.
For multi-stage high-pressure screw air compressor with continuous heavy load and working temperature higher than 93 ℃, polyol ester is better than Pao, and its working life can be prolonged by one time.
Dimethylsiloxane oil has excellent viscosity index (VI = 400), thermal oxidation stability and hydrolysis stability, but the metal to metal lubricity is poor, and additives for improving lubricity have been developed. The improved dimethylsilicone oil has been introduced into the market in the 1970s, and the service time of the compressor has exceeded 40000 hours. The service result is satisfactory. The biggest problem is the high cost of lubricating oil replacement, the key is the high cost of design and maintenance of gas oil separator.
(4) Reciprocating air compressor
One of the main reasons for using synthetic oil in air compressors is cleaning, that is, reducing sludge, precipitation and carbon deposition. The use of organic ester as crankcase lubricant can improve the cleanliness, good heat transfer, reduce the friction and resistance of moving parts, thus reducing the maintenance and shutdown time, and reducing the power consumption by 7.2%. The use of synthetic oil in the crankcase saves 3% of the power, and the power cost is calculated at US $0.04/1500 hours. The saved cost can offset the additional cost of at least 6 months due to the use of synthetic oil.
For the lubrication of one-way cylinder of large reciprocating air compressor, the common problem is the formation of carbon residue and sludge in the cylinder and exhaust valve, which causes frequent maintenance and shutdown. In addition, carbon residue, corrosion, excessive lubricant and high pressure make the compression system automatically ignite and even cause explosion when the temperature is lower than 149 ℃. Using polyol ester can solve these problems. After changing to synthetic oil, the saved cost can offset the additional cost of 1.6 years due to changing to synthetic oil.
(5) Synthetic oil of chemical process gas compressor successfully solves the lubrication problem of chemical process gas compressor. Chemical processing gas may react with general mineral oil. Due to the tendency of mineral oil to inhibit catalyst, many chemical plants prohibit the use of such lubricating oil. Typical chemical processing gases include chloromethane, sulfur dioxide, hydrogen chloride, ammonia, and mixed processing gases such as CO2, chlorosiloxane, chlorinated hydrocarbon, and gases containing trace mineral acids. When the reactive gas is compressed, the compressor equipment and lubricating oil are chemically corroded, which increases with the temperature and pressure. The suitable lubricants are PAO, silicone oil and hydrocracking saturated hydrocarbon. C
PAO and hydrocracked saturated hydrocarbon have excellent chemical corrosion resistance. Choosing suitable base oil can solve the lubrication problem of compressor when acid and other reactive compounds meet, but only perfluorocarbon oil and chlorinated hydrocarbon oil can be used in pure oxygen compressor.
Hydrocracking saturated hydrocarbon is a new type of lubricating oil. The crude oil fraction was hydrotreated at 300 ℃ and 20785kpa. The sulfur, nitrogen and oxygen compounds were completely decomposed, and the aromatic compounds were converted into saturated naphthenic hydrocarbons. Carry out two more vacuum distillation to remove volatiles and other impurities. Dewaxing and second hydrogen treatment to remove residual impurities. Base oil is a stable mixture of isoalkanes and cycloalkanes, and its lubricity is similar to Pao. Mixing with other synthetic oil can further improve the lubricating performance of the oil.
Fluorinated silicone oil is a partially fluorinated polysiloxane. Except for pure oxygen and some strong oxidants, it is completely inert to almost all compounds. It is used as a compressor for the treatment of chloromethane, chlorine and HCl. But silicofluoride oil is too expensive (more than $800 per gallon) to use.
Alkyl methyl silicone oil forms a tough thick film in use, which has natural lubricity. The oil provides a long-term protective oil film on the surface of metal parts and provides effective lubrication in HCl, CO2 and chloromethane containing a small amount of sulfuric acid applications.
(6) Inert gas and industrial gas compressor the purity of the gas in the application of inert gas and industrial gas compressor is very important, and it should be considered that the lubricant may have the effect of inhibiting the activity of catalyst. Only the base oil with the best quality can lubricate the inert gases such as N2, he, CO2 and industrial gas compressors such as H2.
PAO, hydrocracking saturated hydrocarbon and PAG are immiscible with the above-mentioned gases, providing better volume efficiency in rotary compressor and satisfying use for industrial gas compressor.
(7) Hydrocarbon gas compressor
In addition to the above hydrocarbon refrigerant, hydrocarbon gas also includes natural gas, oil well gas and waste gas.
In light hydrocarbon gas compressor, mineral oil can also be used as lubricant due to low dilution. However, synthetic lubricants have reliability in these applications, and their unique viscosity characteristics and compatibility with hydrocarbons improve the working efficiency of the system. Many heavy hydrocarbon gas compressors must use synthetic oil.
Hydrocarbon and most lubricants are completely soluble, and the solubility depends on the working pressure and temperature of the compressor.
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