compressor[1](compressor), which is a driven fluid machine to lift low-pressure gas into high-pressure gasrefrigeration systemThe heart of.It sucks refrigerant gas of low temperature and pressure from the suction pipe, drives the piston to compress it through the operation of the motor, and then discharges refrigerant gas of high temperature and pressure to the exhaust pipe to provide power for the refrigeration cycle.
Thus, the refrigeration cycle of compression → condensation (heat release) → expansion → evaporation (heat absorption) can be realized.The compressor is divided into piston compressor,screwcompressor,centrifugalCompressor, linear compressor, etc.The entry introduces the working principle, classification, accessories, specifications, operation requirements, compressor production, common faults, environmental protection requirements, selection principles, installation conditions and development trend of the compressor.
The compressor is considered asrefrigeration systemThe special term that best represents the characteristics of compressor is called "steam pump".The actual responsibility of the compressor is to raise the pressure and raise the suction pressure to the discharge pressure[2]。
Compression ratio is a technical expression of pressure difference, which means that the absolute pressure on the high-pressure side is divided by the absolute pressure on the low-pressure side.The absolute pressure value must be used for the calculation of compression ratio.In order to avoid negative value of the calculated compression ratio, absolute pressure must be used instead of gauge pressure when calculating the pressure ratio.Only by using absolute pressure value can the calculated compression ratio be positive, which is meaningful.
There are five types of compressors used in the refrigeration and air conditioning industry: reciprocating, screw, rotary, scroll and centrifugal. Reciprocating is the most widely used compressor in small and medium-sized commercial refrigeration systems.Screw compressorIt is mainly used in large-scale commercial and industrial systems.Rotary compressor、scroll compressor It is mainly used for household and small capacity commercial air conditioning devices,Centrifugal compressorIt is widely used in the air-conditioning system of large buildings.
variousReciprocating compressorGenerally, it is classified according to the form of compressor housing and the setting mode of driving mechanism.According to the shell form, there are open and closed semi closed compressors.Closed type means that the whole compressor is set in a housing.
classification
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Compressor can be divided according to its principle[3]It is a positive displacement compressor and a speed compressor.The volumetric type is divided into: reciprocating compressor, rotary compressor;The speed compressor is divided into axial compressor, centrifugal compressor and mixed flow compressor.
Today's household refrigerators andair conditionerAll compressor types are displacement type, which can be divided into reciprocating type and rotary type.Reciprocating compressors use piston, crank, connecting rod mechanism or piston, crank, sliding tube mechanism, while rotary compressors mostly use rolling rotor compressors.In commercial air conditioners, they are mostly centrifugal, vortex and screw type.
According to the application range, it can be divided into low back pressure type, medium back pressure type and high back pressure type.Low back pressure type (evaporation temperature - 35~- 15 ℃), generally used for household refrigerators, food freezers, etc.Medium back pressure type (evaporation temperature - 20~0 ℃), generally used for cold drinks cabinet, milk refrigerator, etc.High back pressure type (evaporation temperature - 5~15 ℃), generally used forRoom air conditionerDehumidifier, heat pump, etc.
parts
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Compressor accessories are as follows[4]：
Air compressor accessories (gas valve)
Cylinder head
Crosshead
cooler
Air valve
crankshaft
connecting rod
Small head tile
piston rod
seal ring
Oil scraper ring
Support ring
Compressor switch
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working principle
It is mainly used on the air compressor to adjust the start and stop status of the air compressor. It can stop the air compressor for rest by adjusting the pressure in the air tank, which is useful for maintenance of the machine.When debugging the air compressor in the factory, adjust it to the specified pressure according to the customer's needs, and then set a differential pressure.For example, when the compressor starts to pump air into the air storage tank, when the pressure reaches 10kg, the air compressor will stop or unload. When the pressure reaches 7kg, the air compressor will start again. There is a pressure difference between them. This process can allow the compressor to take a break to protect the air compressor[5]。
The motor directly drives the compressor to make the crankshaft rotate and drive the connecting rod to make the piston reciprocate, causing the volume change of the cylinder.Due to the change of the pressure in the cylinder, the air is allowed to enter the cylinder through the air filter (silencer) through the air inlet valve. During the compression stroke, due to the reduction of the cylinder volume, the compressed air passes through the exhaust valve, passes through the exhaust pipe, and the one-way valve (check valve) enters the air reservoir. When the exhaust pressure reaches the rated pressure of 0.7MPa, the pressure switch will control the automatic shutdown.When the pressure of the air tank drops to 0.5-0.6MPa, the pressure switch is automatically connected and started.
Switch structure
For different temperature measurement ranges, temperature switches with different structures should be selected. In the temperature range of 0 ℃~100 ℃, solid expansion type temperature switches are usually used. In the temperature range of 100 ℃~250 ℃, gas expansion type temperature switches are mostly used. For the temperature range above 250 ℃, only thermocouples or thermal resistance thermometers can be used,After the measurement transmitter is converted into analog electrical signal, the electrical signal is converted into switching signal[6]。
The working principle of solid expansion temperature switch is to make use of the difference of length change of different solids after heating to generate displacement, so that the contact can act and output the switching value signal of temperature.For example, there is a temperature switch that usesBimetallic sheet(The brass sheet is stacked on the indium steel sheet). As the linear expansion coefficient of the brass sheet is larger than that of the indium steel sheet, the bimetallic sheet will bend after being heated.When the specified temperature is reached, the free end of the bimetallic sheet (the moving contact of the temperature switch) will produce enough displacement, disconnect from the fixed static contact, and send out the switching value signal.
The gas expansion temperature switch is based on the gasPressure thermometerThe principle of working.It has a temperature measuring package filled with nitrogen, which is connected to the measuring element of the pressure switch through the sealed capillary tube.When the measured temperature reaches the specified value, the inflation pressure in the temperature chamber makes the pressure switch act.
Specifications
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The specifications of the compressor are as followsInput powerTo divide.Generally, the difference between each specification is about 50W.In addition, there are alsoCylinderCubage divided[7]。
main performance
Input and output power, performance coefficient, cooling capacity, starting current, running current, rated voltage, frequency, cylinder volume, noise, etc.To measure the performance of a compressor, we mainly compare the weight, efficiency and noise.
According to Chinese standards, the safety performance inspection is carried out according to the items specified in GB4706.17-2004.The main items are electrical strength, leakage current, locked rotor and overload operation test.
The performance inspection of air conditioner compressor shall be carried out according to the provisions of GB5773-2004.
In addition, when there are major changes that may affect the product performance during the product finalization and production, when the product has been produced continuously for one year or is produced again after more than one year, and when the factory inspection results andType testIn case of large difference, type test must be carried out.
Packaging, storage and transportation
The compressor can be packed and transported according to the contract.Compressors imported in large quantities are usually packed in cartons and then shipped in containers.The compressor shall be firmly fixed in the packing box and provided with moisture-proof and shockproof measures.It shall not be inverted during storage and transportation, and shall be stored in a well ventilated warehouse. The relative humidity shall not exceed 80%, and there shall be no corrosive gas.
Importing country
In the case of insufficient supply of domestic compressors, China still needs to import an appropriate amount every year.The main trading countries are Germany, the United States, Italy, Japan, Denmark, Brazil, South Korea, etc.Equipment modificationThe quality and output of domestic compressors have been greatly improved.
Operation requirements
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The first load operation of the compressor is when the train is emptyworkAnd after purging.The compressor shall operate under load according to the following requirements[8]：
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1. Gradually close the vent valve or oil and water blow off valve after startingRated pressureRun for 1 hour;Operate at 1/2 rated pressure for 4-8 hours.
2. The compressor operates at the minimum pressure, and the pressure can be gradually increased only after there is no abnormal phenomenon;
3. For largeHigh pressure compressorThe operating time under nominal pressure shall not be less than 24 hours;
4. During operation, check the following items:
1. Pressure, temperature and oil supply of lubricating oil.The oil pressure shall not be less than 1kg/cm2 before being fed into the distribution pipe system.The lubricating oil moisture in the crankcase or body shall be: the compressor with crosshead shall not exceed 60 ℃.The temperature without crosshead shall not exceed 70 ℃.
2. The compressor operates stably and the sound of all moving parts should be normal.
3. Measure the inlet and outlet water temperature and check the cooling water supply. The cooling water is not allowed to flow intermittently, with bubbles and blockage.The cooling water drainage temperature shall not exceed 40 ℃.
4. Connectionsflangepart,Shaft seal, inlet and exhaust valvesThe cylinder coverAnd water jacket, etc., without air leakage, oil leakage and water leakage.
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5. The inlet and exhaust valves shall work normally and the safety valve shall be sensitive.
6. All connecting parts shall not be loose.
7. The measured exhaust temperature and pressure values at all levels shall comply with the provisions of various technical conditions.
8. The heating condition and current value of the motor shall comply with the regulations.
5. After operation, disassemble and inspect the following items:
1. Disassemble the air valves at all levels and the front covers of all cylinders, check the friction of the cylinder mirror surface, and find out the cause if there is any friction trace.
2. Check the friction condition of the piston rod surface, and there should be no wear marks and pulleys.
3. Disassemble the air valves at all levels, check the fit between the valve plate and the valve body, and replace them with spare parts in case of cracks in the cutting plate.
4. Check the cross slide plate and the bodyguideFriction condition of friction surface.
5. Remove the connecting rod big end bush and crosshead pin, and check the friction condition of the friction surface.
6. Replace the lubricating oil in the machine body.After the initial operation of the compressor;Due to the running in of parts and the cleaning effect of lubricating oil, a large amount of fine metal powder enters the lubricating oil. Therefore, all lubricating oil should be replaced after the machine works for 24 hours.After 200 hours of operation, change the oil again.After replacement twice, change the oil according to the regular maintenance requirements.
In order to ensure uniform lubrication, sufficient lubricating oil must be available everywhere during the initial operation.
Compressor production
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Compressor is based onAssembly lineIt is produced by.The cylinder block, piston (shaft), valve plate, connecting rodcrankshaft, end cover and other parts;Assemble the rotor in the motor workshopstator；The shell is manufactured in the stamping workshop.Then assembly, welding, cleaning and drying shall be carried out in the general assembly workshop, and finally they shall be packaged and delivered after inspection[9]。
Most compressor manufacturers do not produce starters and thermal protectors, but purchase them from the market as required.Compressor representative enterprises include: Meizhi, Mitsubishi, Embraco, etc.
Environmental requirements
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With the development of industry, the pollution to the earth is becoming more and more serious. Environmental protection has become an important issue of global concernglobal warming, which has attracted the attention of all countries in the world, reached consensus among international governments and signed relevant agreements[7]。
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In the field of refrigeration and air conditioning, the destruction of the atmospheric ozone layer caused by CFCS and HCFCS and the global warming caused by energy consumption are issues that should be paid great attention to when designing compressors.
As we all know, refrigerant selection affectsCompressor designOne of the many factors that should be highly valued.
In order to develop new compressors using alternative refrigerants, the designer first encountered two problems:
First, the size of the compressor's working volume must be redefined to meet the pressure requirements of different flow rates;
Secondly, the compatibility between various materials in contact with refrigerant in the compressor, such as synthetic rubber and lubricating oil, must be solved.
In the past history, more than 50 substances have been used as refrigerants.After World War II, except for ammonia in the range of large cooling capacity, almost all refrigeration and air conditioning fields were dominated by halohydrocarbon CFCS and HCFCS in 1974MontrealThe CFCS substitution specified in the agreement has been realized in industrialized countries, and the HCFCS substitution plan will be completed in 2020;For developing countries, it will be discontinued in 2010 and 2040 respectively.However, in some developed countries, they are prepared to achieve this in advance.Figure 6 shows the application fields of CFC-11, CFC-12, HCFC-22 and R502 commonly used in Europe and their possible substitutes (under the arrow line).
CFC-11
CFC-11 is a low pressure refrigerant, mainly used forCentrifugal chillerThe transition agent is HCFC-123.In addition, HFC-245ca or HFC-245fa are also low pressure refrigerants, but they are flammable, so their flame reduction methods and toxicity need to be studied, and their use is not as efficient as CFC-11 and HCFC-123.Therefore, many enterprises have changed to use HFC-134a in centrifugal chillers.
CFC-12
CFC-12 is widely used inAutomobile air conditionerTherefore, the object to be replaced should be considered first.HFC-134a can be replaced in household refrigerators and automobile air conditioners.HFC-134a has the same refrigerating capacity and efficiency as CFC-12 in the range of medium temperature and high temperature.But when the temperature is lower than - 23 ℃working conditionHowever, it loses its attraction because its cooling capacity and efficiency are lower than CFC-12.Although HFC-134aozoneThe ODP value of the consumption potential is zero, but the GWP value of its global warming potential is as high as 1300 (the comparison value based on the GWP value of CO2), which will also affect its development and use in the long run.
HCFC-22
HCFC-22 has been widely used in commercial refrigeration, commercial and residential air conditioners and heat pumps. Its ODP value is far less than that of CFC-11 and CFC-12, only 0.055.However, its GWP value is quite high, about 1700.Because of these reasons, some European countries, such as Germany, are being eliminated rapidly.Several refrigerant mixtures have been used as alternatives to HCFC-22.The American Refrigeration Association has recommended four kinds of refrigerant alternatives in its refrigerant alternative evaluation plan (AREP): HFC-134a, R407C, R410A and R410B.However, HFC-134a has a smaller refrigerating capacity and pressure than the other three. Using it as refrigerant requires a larger redesign of the system, so it seems to be the least likely to replace HFCF-22, but it is still possible to be used in larger chillers.zeotropic Working mediumR407C is likely to be a "drop in" substitute for existing machines. Because it is the closest to HCFC-22, only minimal changes are required to the equipment of the system after replacement, and acid lubricating oil is used to replace mineral oil. Attention should also be paid to the larger temperature slip of the working medium (up to 5~7 ℃).Near azeotropic refrigerants R410A and R410B are two mixtures of the same HFCS, but the only difference is the mixing ratio.R410A is suitable for small split air conditioners, but its evaporation pressure is about 1.5 times that of HCFC-22. Therefore, the system using this working medium needs to be completely redesigned, so it is only used in new refrigeration and air conditioning systems.The optimized design of this system can increase its efficiency by 5%.
R502
R502 was widely used in low temperaturerefrigeration systemLi.AREP recommends two possible alternatives: R404A and R507.R404A has the same refrigerating capacity and efficiency as R502, but more tests should be carried out on the system components, especially the compressor.One of the mixed components of R507 plays a role of flame retardancy, which is similar to the performance of R502, but the toxicity test continues in the United States;However, in Europe, it has been used in supermarket refrigeration equipment.
natural refrigerant
"Natural refrigerants", such as ammoniahydrocarbon、carbon dioxideEtc.Ammonia has been used for more than one hundred years. So far, many countries have used it in large-scale industrial refrigeration and food refrigeration[10]。
Hydrocarbons have very good thermodynamic properties and heat transfer characteristics, and are completely compatible with all mechanical materials and oils.In fact, this working medium has beenPetrochemical industryFor large refrigeration systems.The resistance affecting the popularization of such refrigerants comes from their combustibility.In Europe, this refrigerant has begun to enter the householdRefrigeration equipmentFor example, Germany has 90% coverage in its products.The Chinese refrigerator industry also has R600a products using isobutane.
The application scope and prospect of combustible refrigerant is a very important issue, and its universal solution still needs a relatively unified international understanding, because it affects the international trade of refrigeration and air conditioning equipment.However, to achieve this step, more experimental research and policies adopted by various countries on this issue are still needed. It seems that it will take quite a while to see the clues.
Because the traditional mineral oil and synthetic oil suitable for CFCS working fluids such as CFC-12 have poor compatibility with HFCS such as new working fluids R134a, people have developed a new type of polar lubricating oil. The base of the lubricating oil is either poly ester POE (called ester oil) orpolyethylene glycolPAG (calledEthylene glycol oil）They have good compatibility with new HFCS working medium, so as to avoidHeat exchangerGather lubricating oil and ensure that the oil can return to the compressor smoothly.
Common faults
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Insufficient air displacement
Insufficient air displacement is one of the most common faults of the compressor, which is mainly caused by the following reasons[8]：
1. Failure of air inlet filter: the scale is blocked, which reduces the exhaust volume;The suction pipe is too long and the pipe diameter is too small, which increases the suction resistance and affects the air volume. The filter should be cleaned regularly.
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2. When the compressor speed decreases, the exhaust volume decreases:Air compressorImproper use. Because the discharge capacity of the air compressor is designed according to a certain altitude, suction temperature and humidity, when it is used on a plateau that exceeds the above standards, the suction pressure will decrease, and the discharge capacity will inevitably decrease.
3. The cylinder, piston and piston ring are severely worn and out of tolerance, which increases the clearance and leakage, affecting the exhaust volume.In case of normal wear, vulnerable parts such as piston rings shall be replaced in time.If the installation is incorrect and the clearance is inappropriate, it should be corrected according to the drawing. If there is no drawing, experience data can be taken. For the circumferential clearance between the piston and the cylinder, if it is a cast iron piston, the clearance value is 0.06/100~0.09/100 of the cylinder diameter;For aluminum alloy piston, the clearance is 0.12/100~0.18/100 of the gas diameter;The smaller value of aluminum alloy piston can be adopted for steel piston.
4. The stuffing box is not tight, resulting in air leakage, which reduces the air volume.The first reason is that the stuffing box itself does not meet the requirements during manufacturing;Secondly, it may be that the piston rod is not well aligned with the center of the stuffing box during installation, resulting in wear, strain, and air leakage;Generally, the stuffing box is filled with lubricating oil, which can play the role of lubrication, sealing and cooling.
5. Impact of compressor suction and exhaust valve failure on the exhaust volume.Metal chips or other sundries fall between the valve seat and the valve plate of the gas valve, resulting in untight closing and air leakage.This not only affects the exhaust volume, but also affects the changes of interstage pressure and temperature;This problem may be caused by manufacturing quality problems, such as warping of valve plates, and air leakage caused by serious wear of valve seats and valve plates.
6. The gas valve spring force does not match the gas force well.If the elastic force is too strong, the valve plate will open slowly, and if the elastic force is too weak, the valve plate will not close in time, which will not only affect the air volume, but also affect the increase of power, as well as the service life of the valve plate and spring.At the same time, it will also affect the change of gas pressure and temperature.
7. The pressing force of the pressing air valve is improper.If the pressing force is small, air leakage will occur. Of course, if it is too tight, the valve cover will be deformed and damaged. Generally, the pressing force can be calculated by the following formula: p=k π/4 D2P2, D is the diameter of the valve chamber, P2 is the maximum gas pressure, K is a value greater than 1, generally taking 1.5~2.5, K=1.5~2.0 at low pressure, and K=1.5~2.5 at high pressure. Practice has proved that it is good to take K in this way.If the gas valve fails, the valve cover must be heated and the pressure is abnormal.
Abnormal temperature
Abnormal exhaust temperature means that it is higher than the design value.Theoretically, the factors affecting the increase of exhaust temperature include intake air temperature, pressure ratio, and compression index (forAir compression indexK=1.4）。The actual situation affects the factors of high suction temperature, such as: low intermediate cooling efficiency, or in the intercoolerIncrustationIf more knots affect the heat exchange, the suction temperature of the later stage must be higher, and the exhaust temperature will also be higher.In addition, air leakage of gas valve and piston ring will not only affect the rise of exhaust temperature, but also change the interstage pressure. As long as the pressure ratio is higher than the normal value, the exhaust temperature will rise.In addition,water-coolingThe exhaust temperature will rise in case of water shortage or insufficient water.
Abnormal pressure
The amount of gas discharged by the compressor cannot meet the user's flow requirements under the rated pressure, thenExhaust pressureIt must be reduced.At this time, another machine with the same exhaust pressure and large exhaust volume has to be replaced.The main reason for the abnormal interstage pressure is the gas leakage of the gas valve or the gas leakage after the piston ring is worn. Therefore, the reasons and measures should be taken from these aspects.
Abnormal sound
If some parts of the compressor fail, it will make an abnormal sound. Generally speaking, the operator can identify the abnormal sound.The clearance between piston and cylinder head is too small, resulting in direct impact;The connecting nut between piston rod and piston is loose or tripped;The plug on the end face of the piston is blocked, and the piston moves upward in series to collide with the cylinder head;Metal chips falling into the cylinder and water accumulated in the cylinder can make knocking sound in the cylinder.Crankcase crankshaft bearing bush bolt, nut, connecting rodBoltThe crosshead bolt is loose, tripped and broken, the shaft diameter is severely worn and the clearance is increased, the crosshead pin and bushing fit clearance is too large or severely worn, etc. All of these can make a crash sound in the crankcase.The exhaust valve plate is broken, the valve spring is soft or damaged, and the load regulator is improperly adjusted.Then find the fault and take measures.
Overheating fault
Overheating occurs when the temperature exceeds the specified value at the friction points between crankshaft and bearing, crosshead and sliding plate, packing and piston rod, etc.The consequences of overheating: one is to accelerate the wear between friction pairs, and the other is that the excessive heat energy continues to accumulate to burn the friction surface, resulting in a major accident of the machine.The main causes of bearing overheating are: uneven fitting of bearing and journal or too small contact area;The bearing is deflected, the crankshaft is bent, the viscosity of lubricating oil is too small, and the oil circuit is blocked,Oil pumpOil cut-off due to fault;During installation, there was no leveling, no clearance, no alignment between the main shaft and the motor shaft, and the two shafts were inclined.
The bearing is worn
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The wear of compressor transmission parts is a common problem, including bearing position, bearing seat, bearing chamberKeywayAnd thread, etcRepair weldingandBrush platingSpraying is the main method, but both of them have certain disadvantages: the thermal stress caused by the high temperature of repair welding cannot be completely eliminated, which is easy to cause material damage and lead to bending or fracture of parts;However, brush plating is subject to the coating thickness, which is easy to peel off, and the above two methods are both metal repair, which cannot change the "hard to hard" coordination relationship, and will still cause re wear under the combined effect of various forces.In contemporary western countries, it is often used to solve the wear problems of compressor transmission partsPolymer compositesThe most mature repair method currently used is the United StatesMeijiahuaTechnical system, with super adhesive force, excellent compressive strength and other comprehensive properties, it can be removed without machining, without the influence of repair welding thermal stress, and the repair thickness is not limited.At the same time, the material has the flexibility that metal does not have, which can absorb the impact and vibration of equipment to avoid the possibility of re wear.
Corrosion erosion type
compressorcorrosionIt can be divided into comprehensive (uniform) corrosion and local corrosion. The former occurs evenly on all surfaces of the compressor, while the latter only occurs locally, such asPitting、Crevice corrosion、Intergranular corrosionStress corrosion, etc.It is one of the effective anti-corrosion measures to apply organic coating on the surface of the compressor with polymer composite materials. It has good chemical resistance, excellent mechanical properties and bonding properties. Compared with the traditional welding repair of pressure vessels, it has the characteristics of simple construction, low cost and good repair effect.
Shell crack and fracture
Due to casting and processing defects, internal stress, overload operation and other reasons, the compressor often causes cracks or fractures in its components.The conventional repair method is welding, but some parts are made ofcast iron, aluminum alloy, titanium alloy, difficult to do welding treatment.There are also some dangerous occasions that are prone to explosion, and it is not easy to use welding repair method.The new "cold welding" technology can avoid thermal stress deformation. At the same time, the materials have good adhesion, compression resistance, corrosion resistance and other comprehensive properties, which can meet the operating requirements of the compressor to the maximum extent, so as to effectively ensure operation at the lowest cost.
Selection principle
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① The compressor capacity shall be determined by multiplying the total mechanical load of each evaporation temperature system by the operating time coefficient.Except for special requirements, generally no machine is used for equipment[11]。
② When piston reciprocating freon compressor is selected, two-stage compressor shall be used when the compression ratio is greater than 10;Single stage compression shall be adopted if it is less than or equal to 10.Freon two-stage compression system should generally adopt one-stage throttling with incomplete middleCooling mode。
③ Some coolers in the cold storageOil separatorCondenser, liquid receiver and other equipment shall be compatible with the refrigeration capacity of Freon refrigeration compressor.
④ The working conditions of Freon refrigeration compressor shall not exceed the limited working conditions specified by Shenzhen refrigerator enterprises.
⑤ In Freon refrigeration system, regenerative cycle shall be adopted generally.
⑥ Operating hours of refrigeration compressor: for Shenzhen cold storage of 5~100t, 12~16h operation per day and night is generally adopted.
Installation conditions
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Compressor installation
The selection of installation site is most ignored by the staff.The compressor is often randomly located after purchase and used immediately after piping, without prior planning.Little did we know that such a hasty result resulted in the difficulty of compressor maintenance and the poor quality of compressed air in the future.Therefore, selecting a good installation site is a prerequisite for the correct use of the air compression system[12]。
1. A wide and well lighted place shall be provided to facilitate operation and maintenance.
2. The relative humidity of the air should be low, with less dust, clean air and good ventilation.
3. The ambient temperature must be lower than 40 ℃, because the higher the ambient temperature, the less the output air of the compressor.
4. If the factory environment is poor and dusty, pre filtering equipment must be installed.
5. Reserve access roads, and install crown block if conditions permit, so as to facilitate maintenance.
6. Reserve maintenance space. The distance between the compressor and the wall must be at least 70cm.
7. The compressor shall be at least one meter away from the top space.
matters needing attention
Precautions for piping, foundation, cooling system and air pipeline[12]：
1. When piping the main pipeline, the pipeline must have a slope of 1 °~2 ° to facilitate the drainage of condensate in the pipeline.
2. The pressure drop of the piping line shall not exceed 5% of the set pressure of the compressor, so it is better to choose a larger pipe diameter when piping.
3. The branch pipeline must be connected from the top of the main pipeline to avoid the condensate in the pipeline flowing down to the gas equipment. The compressor air outlet pipeline should preferably have a one-way valve.
4. When several compressors are installed in series, a ball valve or an automatic drain valve must be installed at the end of the main pipeline to facilitate condensate drainage.
5. The main pipeline shall not be shrunk arbitrarily. If the pipeline must be shrunk or enlarged, the reducer shall be used, otherwise there will be mixed flow at the joint, which will lead to large pressure loss and affect the service life of the pipeline.
6. If there are purification buffer facilities such as gas storage tank and dryer behind the compressor, the ideal piping should be compressor+gas storage tank+front filter+dryer+rear filter+fine filter.In this way, the air storage tank can filter out part of the condensed water, and at the same time, the air storage tank also has the function of reducing the gas exhaust temperature.The air with lower temperature and less water content enters the dryer again, which can reduce the load of the dryer or filter.
7. If the air consumption of the system is very large and the time is very short, and the instantaneous air consumption changes greatly, it is advisable to install an air tank as a buffer (its capacity should be greater than or equal to 20% of the maximum instantaneous air volume), which can reduce the frequency of frequent loading or unloading of the compressor unit, reduce the number of actions of control elements, and have great benefits for maintaining the operating reliability of the compressor.Generally, the air storage tank with a capacity of 20% of the air displacement can be selected.
8. For compressed air with system pressure below 1.5MPa, the flow rate in its delivery pipe must be below 15m/sec to avoid excessive pressure drop.
9. Elbows and valves shall be minimized in the pipeline to reduce pressure loss.
10. The ideal piping is that the main line surrounds the whole plant, so that compressed air from both sides can be obtained at any position.If the gas consumption of a branch line suddenly increases, the pressure drop can be reduced.In addition, appropriate valves shall be provided on the annular trunk line for maintenance and cutting.
Installation foundation
1. The foundation shall be built on a hard floor. Before installation, the foundation plane must be leveled to avoid noise caused by vibration of the compressor.
2. If the compressor is installed upstairs, anti vibration treatment must be done to prevent the vibration from being transmitted to the downstairs or causing resonance, which has potential safety hazards for the compressor and the building itself.
3．screwThe vibration generated by the compressor is very small, so it does not need to be a fixed foundation.However, the ground on which it is placed must be flat, and the underground cannot be soft soil.The bottom of compressor should be paved with cushion or shockproof pad to prevent vibration and noise.
Cooling system
1. When you chooseAir-cooled compressorThe ventilation environment shall be considered.Do not place the compressorHigh temperature equipmentIn order to avoid the normal operation of the unit being affected by the high exhaust temperature caused by the high temperature atmosphere inhaled by the compressor[12]。
2. When the compressor is installed in a small confined space due to the restriction of service conditions, it must be equipped with air extraction and exhaust equipment to facilitate air circulation. The capacity of the air extraction and exhaust equipment must be greater than that of the compressor cooling fanAir volumeAnd the position of the suction inlet shall be suitable for the position of the compressor hot exhaust outlet.
Compliance
The compressor shall be installed in accordance with relevant local laws and regulations, and the following regulations shall be strictly observed:
1. The compressor shall be lifted with lifting equipment with a bearing capacity greater than the unit weight, and the lifting speed and acceleration shall be limited within the allowable range.
2. Try to install the compressor in a cool, clean and well ventilated place to ensure that the air inhaled by the compressor is clean and the moisture content is minimum.
3. The air inhaled by the compressor is not allowed to contain combustible gas and corrosive gas to avoid explosion or internal corrosion.
4. The air-cooled machine should preferably have an exhaust fan or air duct to guide the hot air out of the room to avoid the circulation of hot air to the air inlet.
5. The discharge of compressor sewage and waste oil shall comply with the regulations of local environmental protection department.
6. This machine is used forThree phase AC power supplyThe 380V, 50Hz power supply line of the pilot compressor must match its power and be installed with air switch, fuse and other safety devices. To ensure the reliability and safety of electrical equipment, it must be reliably grounded.
Commissioning
1. New machine commissioning must be carried out by commissioning personnel designated or approved by the company[12]；
2. Before starting the machine, make sure that no one is inside the machine set, check whether there are any leftovers and tools, and close the door of the machine set;When starting up, inform the crew members to pay attention to safety;
3. During the test run, strictly check the running direction of the compressor. In case of reverse rotation, immediately shut down the machine, cut off the power supply, switch any two three-phase lines and restart the machine, otherwise the compressor will be damaged (pay attention to every factory power maintenance!)
4. The compressor cannot work at a discharge pressure higher than that specified on the nameplate, otherwisemotor overload And burnt out;
5. When the compressor is under remote control, the machine may start at any time, and a tag shall be hung to remind;
6. When the compressor fails or unsafe factors exist, do not start it by force. At this time, cut off the power supply and make obvious marks.
Maintenance
Compressor maintenance and repair must be carried out under the guidance of qualified personnel[12]
1. Compressed air and electrical appliances are dangerous. During overhaul or maintenance, confirm that the power supply has been cut off, and hang warning signs such as "overhaul" or "no opening" at the power supply to prevent injuries caused by others' switching on and power transmission;
2. When shutting down for maintenance, it is necessary to wait for the whole compressor to cool down and the system compressed air to be released safely, and the maintenance personnel should try to avoid any air outlet in the compressor system and close the corresponding isolation valve;
3. When cleaning unit parts, non corrosive safety solvents shall be used, and flammable, explosive and volatile cleaning agents are strictly prohibited;
4. After the compressor has operated for a period of time, the safety valve and other protection systems must be inspected regularly to ensure their sensitivity and reliability, which is generally inspected once a year;
5. The spare parts of the compressor must be provided by the factory, and the screw oil must be designated by the companyscrew compressor Special oil, and it is strictly prohibited to mix two brands of oil, otherwise it will cause system coking and cause major accidents.
How to distinguish the old from the new
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How to identify a new compressor from an old compressor or a refurbished compressor.In fact, this is the same as the RMB identification method, which requires some professional knowledge[13]。
1: If you buy two identical machines, please use a meter to measure the winding resistance. If it is a new machine, it must be consistent.
2: If you buy a machine, please smell the peculiar smell at the high pressure port of the machine during pressure test, or use open flame to test whether the exhaust port is discolored (the light of the lighter should be yellow, and discoloration indicates that it has been used and has been filled with fluorine, even if the machine is cleaned with any solvent, it can not be cleaned)
3: The paint of the new original compressor is water-soluble paint or fluorocarbon paint, and the paint surface is uniform and smooth.In high temperature environment, the paint surface is not sticky and has no paint smell. Most of the refurbishing machines are produced by small manufacturers, which is impossible to achieve this level.
4: Then look at the trademark. The trademark of the original machine is clear, the font and pattern proportion is moderate, the edge of the trademark is free of burrs, and the model on the nameplate must match the machine, otherwise it is not ruled out that it is a refurbished machine.
5: The HP and LP pipe orifices of the new compressor are all welded by high-frequency welding on the production line, and the pipes are all new pipes without any welding slag on the inner wall.As long as the above points are achieved, I believe it is not difficult to identify an original brand new compressor.
Professional vocabulary
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Absolute pressure[14]
Absolute temperature
Adiabatic compression
Airpadding
Aluminum
Ammonia synthesis
Antisurge protection
Areas and circumferenceso fcircles
Asphalt production
Autofrettage self enhancement
Barrel compressor (see Vertically split compressor)
Bearing
Development trend
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“In the next ten years, China will transform from a big manufacturing country to a strong manufacturing country, realizing the transformation from "Made in China" to "Created in ChinaThe key period for the transformation of Made in China[1]。”
The linear compressor technology replaces the traditional compressor because of its high efficiency, zero noise, zero pollution and simple structure. It is a real green industrial technology.
Six Embodiments of the Development of China's Manufacturing Industry in the Next Decade
First, the manufacturing industry has become the pillar of China's national economy.manufacturing industryIndustrial added valueIt accounts for about one-third of the national GDP and 80% of the total industry;Tax payment accounts for 90% of the total industry;The export of industrial manufactured products accounts for 90% of the total export volume of China's foreign trade;Employees account for 90% of the total industry."From the perspective of development trend, there will be some changes in the next decade, but the manufacturing industry will still play an important role in the national economy."
Second, China's manufacturing industry will continue to grow at a certain rate in the next decade.
Third, the total volume and scale of China's manufacturing industry has ranked first in the world, and it will be the first in the world in the next ten years.
Fourth, transformation, upgrading and structural adjustment will be the main theme of China's manufacturing industry in the next decade.China's manufacturing industry will face five major changes in the future: from relying on investment to relying mainly on technological progress and improving the quality of workers;From focusing on the expansion of production capacity to focusing on the accumulation of technical capacity;Transform from production oriented manufacturing to service oriented manufacturing;From the low end of the world manufacturing value chain to the high end of the world manufacturing value chain;From squeezing to being environmentally friendly.
Fifth, the integration of information technology and China's manufacturing industry is advancing in depth and breadth.Integration of informatization and industrialization“Manufacturing informatizationIt is the focus and convergence point of the integration of industrialization and industrialization. "The integration of manufacturing, information technology and high-tech can promote the transformation and upgrading of traditional manufacturing to modern manufacturing.Among them, intelligence is very important: the digitalization of products and equipment is to provide intelligent tools to all sectors of the national economy, so as to improve China's social productivity and improve the international competitiveness of China's equipment manufacturing industry.The research centers in this field include the national independent third-party research center for major technical equipment-China Major Machinery and Equipment Network。
Sixth, green manufacturing, intelligent manufacturing and service-oriented manufacturing will become the direction of China's manufacturing industry.Green manufacturing means that in the product and whole life cycle of our manufacturing industry, from design, production to remanufacturing, the concept of green should be permeated.For example, developing energy-saving products, technologies and processes;Develop products and processes with less pollution, no pollution and low emission;Promote low-carbon development and circular economy;Reduce resource consumption and save resources;Protect ecology.The intelligent manufacturing system will eventually transform from a human-machine harmonious system with human as the main decision-making core to an autonomous operation with machine as the main body.
For example, developing intelligent products (smart machine tools);Automation and intelligence of production process;Develop industrial automatic control technology and products (sensing elementsAutomation instrument, PLC, DCS, FCS, fieldbus, CNC system), remote monitoring, detection, diagnosis, etc.Observing the development trend of the industry in the past year, all compressor enterprises have undergone great changes, both in terms of sales channels and internal management, which is also the main reason for the rapid recovery of compressor enterprises.
