【 Weak current College 】 compressors, refrigeration of lubrication features

1. compressor lubrication features
1. Overview
Gas compressor is the mechanical energy is converted to gas pressure energy of a power plant, commonly used to provide gas power, pneumatic tools in the petrochemical industry, drilling and metallurgical industries are also commonly used in pressure oxygen, ammonia, hydrogen, natural gas, coke oven gas, inert gas, and other media.
Press exhaust pressure different compressors can be divided into low pressure compressor — the exhaust pressure is less than 1.0MPa; medium pressure compressors-exhaust pressure 1.0-10MPa; high-pressure compressor — 10-100MPa exhaust pressure; pressure compressor-100MPa discharge pressure is greater than, and so on. Low-voltage, single-compressor, medium pressure and high pressure and high pressure compressors for multistage type, maximum machine number can be up to 8 levels, the current foreign manufactured pressure up to the high pressure polyethylene 343MPa compressor. By compressing media, General compressors can also be called: air compressor, oxygen compressor, nitrogen compressor, hydrogen compressors and so on.
Compressor structure works can be broadly categorized as follows:
Hydrocarbon gas, petroleum cracking gas and oil from the main ingredients for hydrogen, methane, butane, ethylene, propylene, coke oven gas and city gas's main components are hydrogen, methane, carbon monoxide, carbon dioxide and nitrogen; major component of natural gas is methane. Hydrocarbon gases can act as a single component of the gas was producing and pressure, can also be used as a blending component of the gas was producing and pressure. In gas compressors, compressed media components and properties will be used by the lubrication and lubricant materials selection.
2, gas compressor lubrication and characteristics
Not only in the compressor lubrication to reduce friction and wear of the machine, but can also serve to seal, cooling, and reduce operating noise, good lubrication conditions is a compressor of long-term reliability. But on some types of compressors as roots compressor, for rotor mutual and rotor and shell can often keep a certain gap without sliding contact the lubrication oil-free screw; the small dry rotary vane compressor is also available and without lubrication conditions; in very low temperatures (-20--50 degrees or lower) or compressed high-purity gas piston compressors, to prevent condensation or lubrication lubricant mixed with the pressure in the gas or oil lubrication, but when the piston and piston rod or a labyrinth seal structure, or with graphite or PTFE, wear-resistant materials for manufacture of piston rings or sealing packing. This section highlights the "oil" lubricating compressor lubrication.
Gas compressor lubricating parts of principle can be divided into two classes, one for oil and compressed gas in direct contact with the internal parts, such as reciprocating compressor cylinder, piston, piston, piston rod, exhaust valve, seal packing; rotary compressor for air cavities and rotor (Rotator), exhaust valve, etc. Second, as the oil is not compressed gases in contact with external drive mechanism, such as reciprocating compressor crankcase parts, crank pin, crank bearings, connecting rod slider, ramp, cross head, Rotary and speed compressor bearing, speed gears, etc. Non-oil-gas compressor you must consider when gas leakage on the external influence of the lubrication system.
Typically large, medium-capacity, multi-level, belt cross head drive in, high pressure compressor, the above said part of internal and external parts of lubrication are separated from each other, independent system can adopt the respective requirements of lubrication or Lube. External parts lubricating oil supply for the pump pressure forced circulating lubrication systems. The system can be individually adjusted and assign all lubrication points, fuel supply and an independent of oil pump, fuel tank, cooler and filters, etc., canbe fully lubricating liquid cooling and filtering, thereby keeping the oil for a long time to clean and relatively constant oil temperature. Internal part of multi use lubricating oil-pressure oil is forced into the cylinder and the piston rod seal.
Oiler is actually a small piston pump, usually it's sucking (pressure) oil piston compressor through machinery such as crankshaft of cam-driven, so when the compressor is stopped working, Oiler also stop oil supply. Oiler can directly from the oil tank oil, lubrication oil to the point that the fuel supply is intermittent, by regulating the plunger of the working stroke, you can easily adjust Oiler each of fuel supply. Oiler can individually or combine several Oiler together set for oil.
Use Oiler forced to oil, you should be aware of the cylinder on the location of the oil supply tie-in, it should be placed in the dead center of the piston position near the cylinder head first line second line of piston and piston ring, not only in the full itinerary on lubrication full and beneficial to the seal.
The cylinder lubricating oil quantity required can be broadly according to the following formula:
Q＝120kDLN
-Q — lubricating oil quantity (g/h);
D-cylinder diameter (m);
L-cylinder stroke (m);
N-crankshaft rotation speed (r/min);
K-a unit of surface area of lubricating oil consumption (g/m²), on a horizontal cylinder, desirable k = 0.025, vertical cylinder, desirable k = 0.02.
The calculated value of Q is only an approximate value of lubricating oil content, the actual fuel level according to the operation of the compressor (such as noise, heat, wear, etc.) and the type of media with the lubrication, operating temperature, the number of the condensate is mixed, and so be adjusted forward and to stop checking cylinder internal and extent of the moist air valve is appropriate.
The multi-stage piston-type compressors, usually just the initial first or second class cylinder subjected to lubrication. As a multi-stage cylinder each level are equipped with intercooler and oil and gas separator absorption gas contained oil, each level would need a separate cylinder lubrication, but after the class cylinder lubricant quantity needed than primary air cylinder.
3. selection of lubricants
1) choice of lubricant type
In oxygen compressor, oxygen makes mineral oil oxidation and cause severe burning and detonation of compressorFried, so avoid using oil lubrication, or lubrication oil-free manner, or with water-based emulsion or distilled water add quality score 6-8% of industrial lubricant; glycerol in chlorine-compressor, hydrocarbon-based lubricants can be used with the combination to generate hydrogen chloride, chlorine gas on metal (cast iron and steel) with a strong corrosive effect, generally with no oil or solid (graphite) lubrication. High-purity gases for compression of ethylene compressor, etc. to prevent oil mixed with gas to affect product quality and performance, you typically do not use mineral oil lubrication, and many medical white oil or liquid paraffin lubrication etc. Just in general air, inert gas, hydrocarbons (hydrocarbons) gas, nitrogen, hydrogen, and other types of gas compressor, a large number of widely used mineral oil lubrication.
Compressor pressure different gas lubricant selection reference "grease selection" compressor oil selection section.
2) selection of lubricating oil viscosity
In multi-stage air compressor, the level of the compressed gas cylinder output usually after cooled back-to-slightly higher than the inlet air temperature was admitted to the next level, as a result of the gas cylinder is compressed so the relative humidity is high, when over saturation point, gas condensation of moisture will likely have the water wash effect, makes the loss of lubricating oil on the surface of the cylinder; in the second place in hydrocarbon gas compressor, it not only can be dissolved in lubrication oil viscosity is reduced, and condensation of liquid hydrocarbons with water as on steel wall with washing effect, outline, high pressure, exhaust temperature higher hydrocarbon gas compressor and air humidity larger air compressor easy selection of viscosity higher oil, high viscosity of the oil on the metal attachment is good, and seal. As low-pressure hydrocarbon gases and air compressor used L-DAA100 of high-pressure multistage compressor oil, preferably L-DAA150 compressor oil. Spray oil rotary compressor selection of viscosity is similarly, selection pressure low 100 ℃ kinematic viscosity as 5mm2/s N32 rotary compressor oil, pressure higher selection 100 ℃ kinematic viscosity is 11-14mm2/s N100 rotary compressor oil.
Secondly, to prevent condensation of liquid hydrocarbons and air moisture on the wash effect of lubricating oil, can adopt quality score is 3-5% of the animal oils (such as lard or butter) and blended lubricating oil, animal oil and metal adhesion strength, easy to wash, "resistance" to prevent the loss of lubricating oil.
3) oil substitute
In using oil lubrication of reciprocating Rotary positive displacement compressors in addition to using the corresponding grade compressor oil, you can use the antirust antioxidant, aviation turbine oil cylinder oil for lubricating oil, etc. as a substitute for oil, but these alternative fuel performance should not be lower than the corresponding compressor oil quality indicators, or should meet the specific conditions of use requirements. When the gas compressor with oil lubrication, the external parts and internal parts of the same grade lubricating oils available, can also be used with different grades of lubricating oil, but regardless of the internal parts of the type of lubrication media, while external gearbox parts lubrication should use mineral lubricating oils.
4, gas compressor lubrication system for the use and maintenance
Gas compressor in the most common failure is the piston and piston ring, rotor parts, sliding bearing Department of abnormal wear and glued, the bite of the cross head slider, and abnormal heating, etc. These failures are directly or indirectly, and lubrication system and the maintenance of lubricating device incorrectly. As the use of maintenance personnel should learn the lubrication system and device architecture, performance, structure and use requirements of General knowledge, but also in practice continued to sum up experience, strengthen routine maintenance work, in order to ensure the compressor and lubrication system to keep running. In the daily inspection and maintenance of the following:
(1) keep the lubricant fluid cleanliness: dirty oil or deterioration of the oil will cause a vicious cycle of accelerated parts wear, the forced-circulation type of lubrication system should pay attention to the timely replacement and cleaning of blockage of the oil filter in the filter; you should avoid fuel tank or oil pooled oil exposed to air, to prevent dust and dirt, and other mixed with oil, non-pressure tank and oil tank General can adopt air filters communicate with the atmosphere; in, overhaul should be from oil sampling tests its constituents, such as reach or exceed oil change indicator, should, in whole or in part to replace and supplement the new oil. Usually every 3 months and a half years (or work 2000-4000 hours) can be replaced once the new oil.
(2) shall periodically check: should periodically check the cylinder, valve, and whether such as exhaust pipe to the accumulation of carbon particles are solid and cement, once discovered shall promptly purge, or may be causing the cylinder combustion and explosion, intensify the exhaust heat resistance, causing the exception.
(3) it should be noted that the work of the compressor should observe the State: the compressor working state, periodically check the cylinder valve lubrication and wear, adjust the amount of lubricant to prevent too much oil and lubricating oil levels are low. On the forced circulation system, lubrication pressure indicates too low or decreased significantly, tend to make the oil levels are low, you should promptly downtime maintenance, time the necessity should replace the spare parts and spare parts.
(4) should pay attention to maintain the temperature of the lubricating system: oil or oil pool of normal temperature of hydraulic oil to 40-50 ¡æ suitable, high oil temperature, oil viscosity lower oil oxidation, oil temperature is too low, increase the viscosity, poor liquidity, which will cause insufficient lubrication. Oil temperature may from thermometers (meter) are directly observing indicators from cylinder cooling circulating water or oil cooler cooling water temperature can be indirect reaction, cooling water temperature too high or too low will affect oil working temperature and viscosity of the lubricant.
Second, the lubrication features refrigerator
1. Overview
Freezer means compression refrigeration mode used by the compressor, the conditions for its use and compressed working medium, it is different from the normal air compressor. By freezer structure and working principle differences, it is similar with the air compressor, can also be divided into the piston, screw, centrifugal, and so on several different forms. Freezer is compression refrigeration equipment in one of the most important part.
Freezer work media is a refrigeration system responsible for the delivery of refrigerant heat task, commonly used refrigerants are: freon, ammonia, lithium bromide, Methyl chloride, which freon by gasification temperature and chemical formula of a fluorine 11 (R-11), fluorine 12 (R-12), fluorine 13 (R-13), f 21 (R-21), f-22 (R-22), fluorine 113 (R-113), fluorine 114 (R-114), fluorine 142 (R-142) etc. The refrigerant can be used for low pressure (condensing pressure is less than 0.3-0.3MPa) high temperature (evaporation temperature greater than 0 ℃), MV (condensing pressure 1-2MPa) temperature (evaporationtemperature 0-50 ℃-) and high pressure (condensing pressure greater than 2MPa) low temperature (evaporation temperature is less than-50 ° c) of the refrigeration system.
2, the freezer lubrication features
1) piston refrigeration
In piston refrigeration, need lubrication of friction parts are: piston and cylinder wall; connecting rod bearing shell and crank pin head; connecting rod bearing shell small head and piston pins; piston pin and piston pin block; front and rear sliding bearing bushing and shaft neck and spindle shaft seal of static and dynamic friction sealing surfaces, etc.
In a small low freezer the simplest of lubrication is splash lubrication, i.e. in the freezer of the crankcase, with the help of the crankshaft and connecting rod head rotation agitation oil surface, the lubricating oil to lubricate friction surface, but for some, it is difficult to achieve the friction surface lubricants, insufficient lubrication, causing large friction and wear, so this poor lubrication reliability, is rarely used alone.
In the new and old series of freezer in most of the mandatory circulating lubrication, namely, the use of force transmission oil pump the oil to the lubrication point. Piston refrigeration lubricant to the transmission system, namely the lubrication system is not a separate tank and pump station, instead of using the crankcase as refrigeration lubricants, special lubricating pump attached to one end of the crankshaft, lubrication equipment and refrigerating machine form a whole.
Oil pump through hole 0.28-0.154mm mesh coarse filter from the crankcase oil absorption, followed by filtration precision is 10-20 μ m paper or powder metallurgy-fine oil filter out of the freezer lubricating oil pressure, the way the lubricating oil was sent to the front end of the crankshaft seal lubricated, the former main bearings and connecting rod and crank pin and the other small head all the way to the pressure oil into the back end of the crankshaft, after the main bearing lubrication, crank pin and connecting small head, moreover the pressure oil also is taken to the oil distribution valve used to control the structure of energy regulation. Lubrication system also comes with pressure gauge, pressure regulating valve and other essential components, pressure regulating valve is used to adjust the lubricating oil pressure and allow extra lubricant flow back into the crankcase. In this system is to use the connecting-rod cylinder surface small head extruder of oil and the connecting rod head thrown for friction surfaces of the lubrication oil.
Freezer in lubricating pump usually have external gear-type pumps, gear-type pumps (commonly known as Crescent pump) and cycloidal rotor type oil pumps (commonly known as the plum blossom pump), 3. For external gear pump xiya oil port location OK, pump rotation direction is certain, irreversible, totally enclosed and semi-enclosed refrigerating machine, freezer cabinets and the integration of the motor casing, indistinguishable from external pump, steering pump, easily lead to bugs and make lubrication failure, external gear pump in freezer application in less time. Internal gear pump, the Crescent Moon (separate from sucking, pressure oil cavity, ensure internal and external gear top seal members) can be made with the automatic positioning of the structure, irrespective of the direction of rotation of the gears do not change the suction, the location of the mouth of the pressure oil, the oil pump to unlimited, the new series of enclosed and semi-enclosed refrigerating machine widely applied. Cycloidal rotor pumps and similar internal gear pump, can also be done on the direction of rotation of the pump without limit, in addition the cycloidal rotor pump tooth shape simple processing is easy, compact structure, in the freezer has a broad application prospects.
2) screw chillers
Screw chiller of lubricating parts are: toout screw (also known as Yin Yang rotor) rotation of engagement; rotating screw and the relative sliding surface of the shell; screw and sliding bearings; active balance piston and screw shaft-end mechanical seal friction surface. In these parts are lubricated having empathy with the pressure oil nozzle. In the energy regulator or shell on different sizes, separated by a distance of oil hole allows the lubrication pressure oil spray directly onto the rotor to cooling lubrication rotor and shell, and on the campaign site for sealing of gaps to reduce leakage of compressed gases and reduce running noise.
Because of the pressure regulating valve adjustment of lubricating oil pressure usually condensation pressure 0.2-0.3MPA, lubricant capacity equivalent to freezer 1% of the exports volume-2%. Lubrication pumps can be driven directly from the rotor itself, and can also be made into the external drive. Usually the oil separator as lubrication system for the fuel tank. Current application of the broader is gravity and centrifugal — — gravity filler type oil separator.
In addition to screw chillers also use secondary oil separator, secondary oil separator for separating out the lubricant can use suction and discharge air pressure difference, without oil pump directly be sent to the suction chamber pressure, the balance of the bearings, lubricated piston etc. In this type of lubrication system commonly used in a tube oil cooler, oil temperature maintained at 20-50 ℃, cooling medium available water or refrigeration own refrigerant to evaporative cooling lubricants. Lubrication system of import and export of fine filters should not exceed the pressure difference 0.1MPa, clean or replace the filter element.
3) centrifugal chillers
The main centrifugal chillers is speed gear lubrication of parts, main bearing and shaft-end mechanical seal. Usually the gearbox can be cum do oil tank, fitted with electric heater for lubricating oil, oil pump for preheated oil pumping to the dedicated high tank, then by the high fuel oil to lubricate parts required, this method can prevent the pump oil supply system suddenly fails or loses power outage refrigerator suddenly, pump oil supply and freezer remains running or borrow a high-speed rotary inertia continues, no friction and lubrication equipment caused by the site's "burn" or "bite" accident.
3. refrigerating machine lubricationSelection of oil
Given the special nature of the work of the refrigerator, on lubricated media also raised some specific requirements for the development of the chiller.
In the selection of lubricating oil, according to the freezer of the type, the type of refrigerant used and its evaporation temperature, as well as the specific working conditions in the refrigerator (such as speed and low, load size, work environment, etc.) to comprehensive comparative analysis, in order to determine the specific requirements of refrigerating oils or to brands.
On small low-speed (average speed is less than 2m/s)-cylinder piston refrigeration can choose N15 or N22, refrigeration oil, on large and medium speed (average speed greater than 3m/s) multi cylinder piston refrigeration can choose N32 or the refrigeration oil N46, exhaust temperature, load weight, the conditions for the use of particularly bad choice of piston refrigeration refrigeration oil N68; on spray oil lubricated screw chiller can choose N32, or refrigeration oil N46; on small dry (non-spray oil lubrication) and screw chillers, centrifugal chillers for lubricating oil can not contact with refrigerant, gearbox and main bearing selection of load conditions N32 or frozen oil N46, it can also select the viscosity and a equivalent L-TSA32 or L-TSA46 of engine oil.
4, freezer lubrication system failures and maintenance
Freezer lubrication system works is:
1) oil pressure table specified stability indicating pressure to the piston or freezer should be higher than the inlet pressure, 0.05-0.3MPA than screw refrigeration condensing 0.2-0.3MPa.
2)crankcase oil temperature should be kept in the 10-65 ℃, the most suitable working temperature of 35-55 ℃.
3) crankcase oil should be sufficient, and long-term stability.
4) oil filter clogging of filters should not, to bring pressure sender's fine oil filter should have blocked sender indicates.
Lubrication system is the most common fault introduction：0il no pressure, pressure failure and pressure gauge pointer violent swinging. The main reason for this is:
1) crankcase oil temperature too low viscosity of the lubricant, frozen, pump inlet oil filter filters too dense, the filter is blocked, and the oil level is too low, pump oil absorption difficulties, suction air phenomenon.
2) pump long-term work, pump wear, excessive leakage within the volume effect markedly lower.
3) regulating valve is stuck in the open position or regulating valve spring failure.
4) system serious leakage.
Freezer failure of lubricating parts of non-lubrication system itself, but also will result in system failure. If the cylinder Department piston ring structure selection, processing and assembling incorrectly can cause large amounts of oil leakage, and shaft seal leakage at the exception will allow crankcase oil surface decreased significantly, resulting in the phenomenon of suction air pumps; then if connecting rod size head bearing and bearing Assembly clearance before and after the primary was too small, the lubricating oil is too dirty and long-term use lubricating oil deterioration, etc will intensify the moving parts of friction and wear, or at the same time because of the serious high cylinder wear blowby, low pressure will cause the crankcase fever, high oil temperature, oil viscosity is reduced, thereby creating a vicious cycle of lubrication conditions and lubrication systems. Therefore, the fault of the lubrication system should be comprehensive, i.e., in addition to the lubrication system of their own issues, also from freezer health inspection, analysis and judgement, as there are no abnormal vibration, noise, heat and leakage, etc.
Lubrication system maintenance should note the following:
1) provided by frozen lubricant oil change indicator periodically check the oil, replace or supplement the filtered fresh oil.
2) replace or clean the filter regularly, pipeline and crankcase.
3) daily observe the inspection of oil, oil temperature, oil pressure is normal.
4), overhaul of attention to check and adjust the pump side clearance, if necessary, should be replaced. Pump end gap depending on the size specifications about 0.03-0.08mm, please refer to the specific values for the pump Assembly technology requirements and factory.
III. common synthetic compressor oil
Synthetic compressor oil types, according to actual needs, the choice of different types of synthetic compressor oils that meet the needs of different types of compressors compress different media technology requirements. Choice than fossil-based compressor oils. Therefore synthetic lubricant development widened scope of application of the compressor.
1. ester compressor oil
Ester oil performance is closely related to its structure, the structure is designed to achieve the desired performance. In General, Ester oil viscosity-temperature performance is good, lengthen the main chains of molecules, viscosity, high viscosity index; the same length as the main chain, with side chain of viscosity, relatively low viscosity index; with aromatic side chain, viscosity index is lower. Branched alcohols diester typically has a low freezing point. The same type of ester, with the increase of molecular weight of low viscosity.
Ester oil thermal stability than mineral oil much higher thermal stability, oxidation stability and mineral oil similar to join the right amount of antioxidant and metal passivator can greatly improve its oxidation stability.
Currently there are 15 per cent of ester oil for compressor oil. Compared with the mineral oil, they also have a high flash point, high-lighted, low volatile, low deposition tendencies, good boundary lubrication, and on additives and products of combustion of Rao has good solubility, etc. Ester-type compressor oil long life, can greatly reduce maintenance costs. In addition, Ester oil also has good biodegradability, low toxicity, biodegradation test CEC mostly in 80 per cent, so environmental protection organizations are strongly recommended to use ester oil. Because of the higher viscosity index, select a lower viscosity grade can meet use requirement to receive energy saving effect.
Ester-type compressor oil is typically used for dynamic compressors, compressed air is the media. Should avoid the use of chlorine gas, oxygen, hydrogen and ammonia compressor lubrication. Can be used with Viton or nitrile rubber seal. Production ester-type compressor oilOf the company and its product brands are:
AGIP company Dicrea100
ANDEROL Andrew company screw compressor 496 (46), repeated compressor 500 (100), for hydrogen compression 555 (100)