All the basic knowledge of screw air compressor

The full name of the air compressor is air compressor; a machine designed according to the working principle that the rotation of the twin screw (also called the yin and yang rotor) causes the gas to produce volume changes. It can inhale natural air and then complete the work through several internal processes. Finally, the compressed air that meets the pressure requirements is discharged. This machine is called a screw air compressor.

Basic knowledge of 1. screw air compressor

1. Working pressure of air compressor

there are many representations of pressure units, which are mainly used in screw air compressors;

① working pressure, domestic users often called exhaust pressure. Working pressure refers to the highest pressure of the air compressor discharge gas;

the commonly used working pressure unit is: bar or Mpa ,1 bar = 0.1 Mpa;

in general, users usually call the pressure unit: Kg (kg),1 bar = 1Kg.

2. Volume flow of air compressor

① volume flow, domestic users often called displacement. The volume flow refers to the volume of gas discharged by the air compressor per unit time under the required exhaust pressure, which is converted to the intake state.

② Volume flow unit: m & sup3;/min (cubic/minute) or L/ min (liter/minute),1m & sup3;(cubic) = 1000L (liter);

③ General, the commonly used flow unit is: m & sup3;/min (cubic/minute);

the volume flow in our country is also known as the displacement or nameplate flow.

3. Power of air compressor

① Generally, the power of the air compressor refers to the nameplate power of the matching drive motor or diesel engine;

② The unit of power is: KW (kilowatt) or HP (horse/horsepower),1KW & asynmp; 1.333HP.

4. Selection Guide for Air Compressor

selection of working pressure (exhaust pressure):

when the user is going to buy air compressor, first determine the working pressure required by the gas end, plus 1-2

bar margin, and then select the pressure of the air compressor, (the margin is to consider the pressure loss from the installation site of the air compressor to the actual gas end pipeline distance, according to the length of the distance in 1-2

appropriate consideration of the pressure margin between bar). Of course, the size of the pipeline diameter and the number of turning points are also factors that affect the pressure loss. The larger the pipeline diameter and the fewer turning points, the smaller the pressure loss; on the contrary, the greater the pressure loss.

Therefore, when the distance between the air compressor and each gas end pipeline is too far, the main pipe diameter should be appropriately enlarged. If the environmental conditions meet the installation requirements of the air compressor and the working conditions permit, it can be installed nearby at the gas end.

Selection of volume flow:

when selecting the volume flow of the air compressor, you should first understand the volume flow of all the gas-using equipment, and multiply the total flow by 1. maintenance items. In addition to the three-level maintenance items, you need:

1. Check the joint contact and insulation resistance of the electrical part of the screw air compressor;

2. Replace the motor grease (once every 8000 hours of operation). If there are parameters in the equipment manual, the manual shall prevail;

3. Clean the relief valve (intake valve);

4. Clean the minimum pressure valve (pressure maintenance valve);

5. Clean the return check valve;

6. Clean the temperature control valve;

7. Clean the cooler;

8. Clean the water-gas separator;

9. Correct all parameters.

Note: The above maintenance shall be carried out after the equipment is confirmed to be free of electricity and pressure.

2. operation method:

1. Check the joint contact and insulation resistance of the electrical part of the screw air compressor:

the electrical part of the air compressor is divided into the main circuit, control circuit and signal transmission (temperature, pressure sensor) circuit. Due to the vibration generated during operation of the air compressor, some wire joints will loosen after normal time. The loosening of the wire joints will cause the unit to fail to start in light, and will cause serious disasters such as protection function failure, arc short circuit, electric shock, etc. Therefore, the electrical part should be checked regularly.

During the inspection, the wires can be swung one by one by hand to feel the tightness of the thread ends, and the loose thread ends should be tightened;

in addition, it is necessary to use a shaking table to detect the insulation between the motor, equipment and the ground. The insulation resistance should be controlled above 500 megohm, otherwise it should be dried or repaired.

2. Replace the motor grease:

the front end and rear end of the motor can ensure the life and normal operation under proper lubrication. Therefore, grease should be injected regularly. The type of grease should be selected according to the parameters provided by each manufacturer.

3, screw air compressor cleaning relief valve (also known as intake valve):

(1) relief valve composition: relief valve by the valve body, valve core (piston), gas manifold block, solenoid valve and proportional valve (capacity valve) and other components.

(2) The function of the relief valve: the relief valve mainly controls the loading (screw air compressor heavy truck), unloading (empty truck) and proportional (capacity adjustment) control functions of the air compressor, and can prevent lubricating oil from being sprayed from the main engine when the air compressor is stopped.

(3) Removal of relief valve: 1 Remove the hose connecting the relief valve and the air filter; 2 Remove the air pipe connected to the relief valve by all other components; 3 Remove the solenoid valve coil; 4 Remove the nut assembled by the relief valve and the main engine and remove it; 5 Move the relief valve to the ground covered with clean paper or related clean laying.

(4) cleaning relief valve: (screw air compressor cleaning agent should be selected soapy water, diesel, clean gasoline, TianNa water, etc., should be selected according to the degree of dirt cleaning agent, generally recommended to use soapy water or diesel cleaning)

remove the solenoid valve: remove the solenoid valve and check whether the O-ring and sealing plate in the solenoid valve need to be replaced (reminder: if you are not familiar with the intake valve, please write down the position of the removed component to avoid errors during assembly). if it is not necessary to replace, put the removed screws, O-ring, sealing plate, electromagnetic rod, core and other components into the prepared container and soak them in appropriate cleaning agent (note: please do not soak O-rings and other rubber products for too long to avoid corrosion when using gasoline and Tina water as cleaning agents.);

dismantling proportional valve: remove the proportional valve from the valve body, then screw out the adjusting nut (it is better to make a mark on the nut before screwing to avoid too large deviation of proportional value when installing), take out the valve core, O-ring, U-ring and spring, and check whether the O and U-ring need to be replaced (all sealing rings and springs removed from the screw air compressor must be checked, which will not be repeated in the following description), soak the removed components in the cleaning agent.

Dismantling the integrated block of the air circuit: remove the integrated block from the valve body. There are air holes on the four sides of the integrated block (the hole of the screw air compressor plays a role in dredging when the integrated air circuit is blocked). Screw out the sealing nut on the air hole and put the integrated block together into the cleaning agent to soak.

Dismantling the valve core of the load-reducing valve: remove the circlip located at the connection between the valve core and the valve body with circlip pliers, screw out the valve core with pipe pliers, take out the cylinder, valve plate, O-ring, U-ring and spring inside and soak them in the cleaning agent, then remove the air inlet on the valve body and soak the whole valve body. At this time, the disassembly process of the load-reducing valve has been completed.

Cleaning: if the dirt on the intake valve is serious, replace it with a new cleaning agent. In the cleaning process, the cleaner parts should be washed first and then the dirt parts should be washed. The cleaned parts should be rinsed again with clean water to avoid corrosion and shorten the service life of the parts. The parts washed with clean water should be placed in a clean place to dry to avoid rusting iron-containing parts.

Pay attention to the smoothness of the surface when cleaning the valve plate and the contact place between the valve body and the valve plate, and clean it, and replace it if necessary, otherwise it will cause the air compressor to start with load (screw air compressor large unit with load will not start the phenomenon).

Installation of components: the installation of components is carried out according to the reverse steps of disassembly. It should be pointed out that when installing components, the position of the sealing ring and the movable components should be coated with appropriate amount of oil, which can make the sealing ring better installed and the movable parts more flexible.

Note: Since there are many parts of the relief valve, if you are not sure to remember the position of each part, you can remove each part and clean it before installing it. However, the parts should not be installed on the valve body first. After all the parts are cleaned, they can be assembled together to the valve body.

After the whole cleaning process of the relief valve is completed, put it aside to be loaded into the air compressor.

4. Clean the minimum pressure valve (screw air compressor is also called pressure maintenance valve):

(1) minimum pressure valve composition: minimum pressure valve by the valve body, valve core, adjusting nut, spring, sealing components, etc.

(2) The role of the minimum pressure valve: The minimum pressure valve mainly establishes the internal pressure of the unit, promotes the circulation of lubricating oil, and meets the working pressure of the relief valve. In addition, the minimum pressure valve also plays the role of a one-way valve to prevent the unit from unloading. When the compressed air in the air storage tank flows back to the air compressor.

(3) Disassembly of the minimum pressure valve: The structure of the minimum pressure valve is very simple. The components inside can be removed by unscrewing the nut of the screw air compressor between the valve core and the valve body. The minimum pressure valve core of the small unit is built into the valve body, and all internal components can be removed by disassembling the valve body cover.

(4) Clean the minimum pressure valve: clean the minimum pressure valve according to the method of cleaning the unloader valve.

(5) Assembly of the minimum pressure valve: assemble the components according to the reverse steps of disassembly. Because the structure of the minimum pressure valve is very simple, the assembly process will not be described one by one, but it should be noted that if there is a U-shaped ring inside, pay attention to the direction of the U-shaped ring.

(6) The minimum pressure valve of the screw air compressor shall be put aside to be loaded into the air compressor after the whole cleaning process is completed.

5. Clean the return check valve

(1) The composition of the one-way valve: the one-way valve is composed of valve body, steel ball, steel ball seat, spring and other components.

(2) The function of the oil return check valve: the oil-gas mixture compressed by the main engine is initially separated by centrifugal force in the oil-gas tank. As the weight of oil is greater than that of air, most of the oil in the solid oil-gas mixture falls to the oil tank by centrifugal force. The screw air compressor returns to the main engine under the action of internal pressure for a lubrication cycle, and the compressed air containing a small amount of oil is separated again by the oil separator, at this time, the lubricating oil separated by the oil-gas separator will fall to the bottom of the oil-gas separator. In order to prevent this part of oil from being taken away with the compressed air, the unit is designed to insert an oil pipe into the bottom of the oil-gas separator and directly introduce this part of oil into the main engine for lubrication through internal pressure. There is a one-way valve on the oil pipe, and the screw air compressor is called oil return single valve,

its function is to smoothly recover the oil from the oil and gas separator to the host without allowing the oil from the host to flow back to the oil and gas separator.

(3) Disassembly of oil return single valve: there is a connection in the valve body, unscrew it from there, and take out the spring, steel ball and steel ball seat.

(4) Clean the oil return check valve: clean the valve body, spring, steel ball and steel ball seat with cleaning agent. There is also a filter screen inside some check valves. If there is one, clean it together.

(5) Assembly of return check valve: Install the check valve according to the reverse steps of removal.

(6) After the whole cleaning process of the check valve is completed, put it aside to be loaded into the air compressor.

6. Screw air compressor cleaning temperature control valve

(1) The composition of the temperature control valve: the temperature control valve is composed of a valve body, a valve core, a temperature sensing element, a spring, etc.

(2) The function of the temperature control valve: the temperature control valve plays the role of constant temperature control. When the oil temperature measured by the temperature sensing element of the temperature control valve is lower than the action value (the action value of the temperature sensing element is generally 71 degrees), the lubricating oil directly returns to the main engine from the oil and gas barrel. When the oil temperature measured by the temperature sensing element of the temperature control valve is higher than the action value, the thimble of the temperature control valve temperature sensing element acts to push valve to open the valve core, let the lubricating oil enter the cooler for cooling (if the temperature measured by the temperature sensing element is higher, the bypass valve opens more), and the cooled lubricating oil returns to the main engine.

(3) Disassembly of temperature control valve: There is a cover on the surface of the temperature control valve of the screw air compressor, and there is a screw hole on the cover. Find a suitable nut to screw into the cover, then use the circlip pliers to take out the circlip fixing the cover, and then use the pliers to pull the nut just screwed in to remove the cover and all internal parts.

(4) cleaning temperature control valve: according to the method of cleaning unload valve cleaning temperature control valve all parts.

(5) the assembly of temperature control valve: according to the disassembly of the reverse steps to install the temperature control valve.

(6) screw air compressor temperature control valve after the completion of the whole cleaning process to be put aside to be loaded into the air compressor.

7. Clean the cooler:

(1) The cooler is divided into two types: air-cooled and water-cooled. Cleaning of 7.2 cooler:

air-cooled cooler

open the air shroud cleaning cover, or remove the cooling fan.

Blow down the dirt with compressed air, and then take the dirt out of the wind deflector; if it is dirty, spray some

blow the degreaser again. When the screw air compressor cannot be cleaned by the above methods, the cooler needs to be removed, soaked or sprayed with cleaning solution and cleaned with a brush (wire brush is strictly prohibited).

Install cover or cooling fan

water-cooled cooler

disconnect the cooling water inlet and outlet pipes.

Inject the cleaning solution to soak or use the pump cycle to wash (recoil effect is better).

Rinse with clean water.

Install the cooling water inlet and outlet pipes.

When the oil cooler fouling is more serious, with the above method to clean is not ideal, you can remove the oil cooler alone, open the two end covers, with a special cleaning steel brush or other tools to remove the scale. When the temperature cannot be effectively reduced by cleaning the medium side of the cooler, the screw air compressor needs to clean the oil side. The method is as follows:

disconnect the inlet and outlet tubing.

Inject the cleaning solution to soak or use the pump cycle to wash (recoil effect is better).

Rinse with clean water.

Dry with dry air or remove water with dehydrated oil.

Install the inlet and outlet tubing

8. Clean the water-gas separator

the structure of the water-gas separator of the screw air compressor is similar to that of the oil-gas tank. The air inlet is designed by the wall, and the centrifugal force is formed. Due to the weight factor of water and gas, the water in the compressed air can be effectively separated.

Cleaning of the water vapor separator: disassemble the cover of the water vapor separator, and then use the cleaning agent to invade and clean.

9. Correct all parameters

after all the above components are cleaned and dried, they will be installed in the air compressor. After all the components are installed in the air compressor, check again for omissions and clean up the tools and other items used during installation.

The operating parameters of the air compressor can be adjusted according to the following data: () Preparation before starting the screw air compressor:

() belt (coupling) correction: if the air compressor is driven by belt, the belt tightness should be between 10~20mm. If the air compressor is driven by a coupling, after installation, the motor and the host should be manually rotated and the balance of the coupling should be checked. The coupling of screw air compressor basically adopts elastic coupling, which can be ignored when the deviation of solid balance is small.

(1) Steering correction of the main engine of the screw air compressor: if the main power supply is removed during maintenance, the forward and reverse rotation of the motor should be paid attention to after the power supply is connected back. The steering of the motor should be based on the steering of the main engine. Please check the steering icon marked on the main engine for the correct steering of the main engine.

Correction method: exchange any two power lines in the three-phase power can be.

(2) Loading, unloading and proportional value validity: when setting the three parameters, the unloading value shall be determined first. The unloading value shall be determined according to the combination of the rated pressure of the air compressor and the pressure required by the gas end. After the unloading value is determined, the loading value shall be set. The pressure difference between the two shall be between 0.1 and 0.2Mpa. After the unloading and loading values are set, the proportional value shall be finally set, the proportional value should be set between the unloading value and the loading value. The screw air compressor gives an example: if a factory needs the air supply pressure of the air compressor to be 0.8Mpa and the air supply requirement is relatively stable, three parameters should be set as follows: the unloading pressure is set at 0.8Mpa, the loading pressure is set at 0.65Mpa, and the proportional control pressure is set at 0.73 ~ 0.75Mpa.

Screw air compressor calibration method: set the parameter in the microcomputer controller (if the air compressor is controlled by button control, the loading and unloading parameters shall be adjusted from the pressure switch, and the proportional value shall be adjusted at the adjusting nut of the proportional valve on the relief valve).

(3) The internal pressure of the unit is effective: the internal pressure of the unit should be between 0.2 ~ 0.45Mpa.

Correction method: the pressure value shall be carried out during the unloading operation of the unit, and the value shall be adjusted on the adjusting nut of the minimum pressure valve. In order to facilitate reading of the set value, the pressure detection point shall be taken before the minimum pressure valve and a pressure gauge shall be installed (some microcomputer controllers have the function of displaying internal pressure parameters; if there is no such function, a pressure gauge shall be installed before the minimum pressure valve).

(4) high temperature protection value: when the screw air compressor is working normally, its temperature should be between 65~98 ℃. The automatic shutdown temperature for over-temperature protection shall not exceed 105°C.

Correction method:

adjust the high-temperature automatic shutdown temperature value in the controller. 1.2 (I. e. 20% margin);

the new project will be selected according to the flow value provided by the design institute;

learn about the volumetric flow parameters of the gas-using equipment from the gas-using equipment supplier for selection;

air compressor station modification can refer to the original parameter value combined with the actual gas situation for selection;

appropriate selection is beneficial to the user himself and the air compressor equipment. Excessive selection is wasteful, and too small selection may cause the air compressor to be in a loading state for a long time or use insufficient gas or pressure cannot be used.

The relationship between power and working pressure and volume flow

under the condition of constant power, when the speed changes, the volume flow and working pressure also change accordingly; for example: a 22KW air compressor, the working pressure is determined to be 7bar during manufacture, and the technical curve of the compressor host Calculate the speed, the displacement is 3.8 m3/min;

when the working pressure is determined to be 8bar, the speed must be reduced (otherwise the drive motor will be overloaded). At this time, the displacement is 3.6 m3/min; because the speed is reduced, the exhaust is reduced accordingly, and so on.

The selection of power is to meet the working pressure and volume flow conditions, the power supply capacity can meet the matching drive motor power can be.

Therefore, the steps of the optional air compressor are: first determine the working pressure, then set the corresponding volume flow, and finally the power supply capacity.