The performance parameters of the pump mark the performance of the pump. The performance parameters of the pump and the relationship between each other are the basis for pump selection and flow regulation. The performance differences of various types of pumps play a very important role in the selection and use.
First, centrifugal pump
The liquid fills the pump casing, the impeller rotates at high speed, the liquid produces a high speed under the action of centrifugal force, and the high-speed liquid passes through the gradually expanding pump casing channel, and the moving indenter is transformed into a static indenter. Attention should be paid to preventing the occurrence of cavitation and gas binding.
Performance characteristics:
The flow range of centrifugal pumps is very large, the flow and pressure are smooth, and there is no fluctuation.
Centrifugal pumps have a high number of revolutions and can be directly connected to electric motors and steam turbines, and the transmission mechanism is simple and compact.
Easy to operate and reliable, easy to adjust and maintain, and easy to automate and operate over long distances.
Compared with the reciprocating pump of the same index, the centrifugal pump has a simple and compact structure, small size, light weight, few parts, convenient manufacturing, low cost, and small footprint, so its equipment and repair costs are low.
Centrifugal pumps have the following main disadvantages:
In general, the centrifugal pump needs to be filled with a pump or the air in the pump is pumped out with a vacuum pump before starting. Although the self-priming centrifugal pump does not have to be filled before starting, there are still limitations in use.
The viscosity of the liquid has a greater impact on the performance of the pump. When the viscosity of the liquid increases, the flow, head, suction and efficiency of the pump are significantly reduced.
Centrifugal pumps are applied in the case of small flow rates and high head, which are subject to certain limitations. Because the pump body runner of the small flow centrifugal pump is very narrow, it is difficult to manufacture and at the same time the efficiency is very low.
Second, multi-stage centrifugal pump
Equivalent to multiple centrifugal pumps in series, one stage of pressurization, can obtain a higher pressure head.
Compared with single-stage pumps, the difference between multi-stage centrifugal pumps and single-stage pumps is that multi-stage pumps have more than two impellers, which can absorb water and pressurized water in multiple stages in stages, so as to raise the water to a very high position, and the head can increase or decrease the number of stages of the pump impeller as needed. Multi-stage pumps are mainly used for mine drainage, urban and factory water supply, agricultural irrigation is very small, only suitable for high lift, small flow of high mountain areas to solve the difficulty of drinking water for people and livestock.
Multi-stage high-core pump has two types of vertical and horizontal multi-stage centrifugal pumps The pump shaft is equipped with two impellers connected in series, which can also achieve higher head than the general single-stage centrifugal pump; compared with piston pumps, diaphragm pumps and other reciprocating pumps, can also pump a larger flow. Multi-stage centrifugal pump has high efficiency, can meet the needs of high head, high flow conditions, and has been widely used in petrochemical, chemical, electric power, construction, fire and other industries.
Due to its own particularity, compared with single-stage centrifugal pumps, multi-stage centrifugal pumps have different and higher technical requirements in terms of design, use and maintenance. It is often people's negligence or poor consideration in some details, which makes the multi-stage centrifugal pump frequently occur abnormal wear, vibration, shaft holding and other failures after it is put into use, which also causes downtime.
Third, the gear pump
The teeth of the two gears are separated from each other, forming a low pressure, the liquid is sucked in, and the shell wall is sent to the other side. On the other side, the two gears close together to form a high pressure to discharge the liquid.
merit:
Simple and compact structure, small size, light weight, good craftsmanship, cheap price, strong self-priming, insensitive to oil pollution, large speed range, impact resistance to load, easy maintenance, reliable work.
shortcoming:
The radial force is unbalanced, the flow artery is large, the noise is large, the efficiency is low, the interchangeability of the parts is poor, it is not easy to repair after wear, and it cannot be used as a variable pump.
Fourth, the screw pump
The twin screw pump is very similar to the gear pump, one screw rotates, driving the other screw, the liquid is intercepted in the mesh chamber, pushed along the rod axis, and then squeezed to the center for discharge.
1) Wide range of pressure and flow;
2) The type and viscosity range of the transported liquid are wide;
3) Because the inertia force of the rotary parts in the pump is low, a high speed can be used;
4) Good suction performance, with self-priming ability;
5) The flow rate is uniform and continuous, the vibration is small, and the noise is low;
6) Compared with other rotary pumps, it is less sensitive to incoming gases and dirt;
7) Solid structure, easy installation and maintenance.
The processing and assembly requirements of the screw are high; the performance of the pump is sensitive to changes in the viscosity of the liquid.
Fifth, reciprocating pump
Reciprocating pumps are positive displacement pumps. When the flow rate provided by the pump is greater than the demand flow of the pipeline, a part of the flow is required to be returned to the reciprocating pump inlet and bypass adjustment.
(1) Can obtain a high discharge pressure, and the flow rate is not related to the pressure, good suction performance, high efficiency, of which the steam reciprocating pump can reach 80% ~ 95%;
(2) In principle, any medium can be transported, almost not limited by the physical or chemical properties of the medium;
(3) The performance of the pump does not change with the change of pressure and viscosity of the conveying medium.
Other pumps do not have the above outstanding advantages of reciprocating pumps, but their structure is relatively simple, the use of operation is more convenient, and there are small size, light weight, uniform flow, and can be serialized in mass production advantages.
The flow is not very stable. Under the same flow rate, it is larger than the centrifugal pump; the mechanism is complex; the amount of funds is large; it is not easy to maintain.
Sixth, double-action reciprocating pump
The piston moves to the right, sucks the liquid from the lower left and drains the liquid from the upper right. The piston moves left, the right lowers to aspirate, and the upper left drains. The piston reciprocates once, and there are two suction and discharge of liquid, and the flow rate is more uniform.
Seven, pneumatic diaphragm pump
In order to make the live column not in direct contact with the corrosive liquid, the cylinder cavity and the liquid material are separated by a diaphragm, which is also the principle of reciprocating pump.
Pneumatic diaphragm pump is a new type of conveying machinery, which is currently the most novel pump in China. Compressed air is used as the power source for a variety of corrosive liquids. Pneumatic diaphragm pumps are available in four materials: engineering plastics, aluminum alloys, cast iron, and stainless steel. Air-operated diaphragm pump according to different liquid media are nitrile rubber, neoprene rubber, fluoro rubber, PTFE, polytetrafluoroethylene, polytetrafluoroethylene. to meet the needs of different users. Placed in a variety of special occasions, used to pump a kind of conventional pump can not be sucked of the medium, have achieved satisfactory results.
(1) The pump will not overheat: compressed air as a power, in the exhaust is an expansion and heat absorption process, the pneumatic pump when working temperature is reduced, no harmful gas discharge.
(2) No electric spark will be generated: the pneumatic diaphragm pump does not use electricity as a power, and after grounding, it prevents static sparks
(3) It can be passed by liquid containing particles: because the volumetric type works and the inlet is a ball valve, it is not easy to be blocked.
(4) The shear force of the material is extremely low: how to suck in and how to spit out when working, so the agitation of the material is minimal, suitable for the transportation of unstable substances
(5) The flow rate can be adjusted, and a throttle valve can be installed at the outlet of the material to adjust the flow.
(6) It has the function of self-priming.
(7) It can be run empty without danger.
(8) Can work diving.
(9) The fluids that can be transported are extremely extensive, from low viscosity to high viscosity, and from corrosive to viscous.
(10) There is no complex control system, no cables, fuses, etc.
(11) Small size, light weight, easy to move.
(12) No lubrication is required, so the maintenance is simple, and the working environment will not be polluted due to drip.
(13) The pump can always remain efficient and will not be reduced due to wear.
(14) 100% energy utilization, when the outlet is closed, the pump automatically stops, the equipment moves, wears, overloads, and heats up
(15) There is no moving seal, and the maintenance is simple to avoid leakage. There are no dead spots when working.
8. Magnetic pump
The magnetic pump is composed of three parts: a pump, a magnetic coupling and a drive motor. The left end of the pump shaft is equipped with an impeller, the right end is equipped with an internal magnetic rotor, and the pump shaft is supported by plain bearings. The bracket connects the pump and motor and guarantees the position accuracy of the internal and external magnetic rotors. When the motor drives the external magnetic rotor to rotate, the magnetic field drives the internal magnetic rotor to rotate synchronously through the air gap and isolation sleeve, thus driving the impeller to rotate.
Compared with centrifugal pumps that use mechanical seals or packing seals, magnetic pumps have the following advantages:
1. The pump shaft changes from a dynamic seal to a closed static seal, which completely avoids the leakage of the medium.
2. No need for independent lubrication and cooling water, reducing energy consumption.
3. Driven by coupling to synchronous dragging, there is no contact and friction. Low power consumption, high efficiency, and damping and vibration damping effect, reducing the impact of motor vibration on the pump and the impact of cavitation vibration on the motor when the pump occurs.
4. When overloaded, the internal and external magnetic rotors are relatively slipped off, which has a protective effect on the motor and pump.
The impeller is eccentric with the pump casing, and the pump casing is filled with a certain amount of water, and the impeller rotates to form a water ring. When the adjacent blades (the red blades in the figure) rotate, the space (air chamber) formed with the water ring becomes larger, that is, the intake air, and the air (air chamber) gradually becomes smaller, that is, the air is compressed. Multiple sets of adjacent blades, that is, multiple sets of reciprocating compression. Compact structure, reliable working balance and uniform flow rate, so chemical production is often used to transport or suck flammable, explosive and corrosive gases. The water ring vacuum pump has a low efficiency due to the large loss of energy due to the impeller stirring the liquid.
Nine, water ring vacuum pump
merit::
The structure is simple, the manufacturing accuracy requirements are not high, and it is easy to process.
Compact structure, the number of revolutions of the pump is high, generally can be directly connected with the motor, without the need for deceleration device. Therefore, with a small structural size, you can obtain a large exhaust volume and a small footprint.
The compressed gas is essentially isothermal, that is, the temperature change of the compressed gas process is very small.
Since there is no metal friction surface in the pump chamber, there is no need to lubricate the pump and there is little wear. The seal between the rotating part and the fixture can be completed directly by the water seal.
The suction is uniform, the work is smooth and reliable, the operation is simple, and the maintenance is convenient.
The efficiency is low, generally around 30%, and the better one can reach 50%.
The vacuum is low, not only because it is limited by the structure, but more importantly, it is limited by the saturated vapor pressure of the working liquid. With water as a working fluid, the ultimate pressure can only reach 2000 ~ 4000Pa. Use oil as a working liquid, up to 130Pa.
In short, because the gas compression in the water ring pump is isothermal, flammable and explosive gases can be extracted. Due to the absence of an exhaust valve and friction surface, dust-stained gases, condensable gases and gas-water mixtures can be removed. With these outstanding features, it is still widely used despite its low efficiency.
10. Vortex pump
W type single-stage direct connection vortex pump is for suction and delivery of clean water or physical and chemical properties similar to water liquid, the use of liquid temperature does not exceed 60, often used in boiler feed water supporting, in shipbuilding, textile, chemical, metallurgy, machinery manufacturing, aquaculture, fixed fire stabilization, heat exchange group, agricultural remote sprinkler irrigation and other departments have a wide range of applications.
The characteristics of the small size and light weight of the vortex pump have great advantages in the ship's installation.
Self-priming ability or self-priming with the help of simple devices.
The head characteristic curve with steep drops, therefore, is insensitive to pressure fluctuations in the system.
Some vortex pumps enable mixed vapor-liquid transport. This is important for pumping volatile liquids containing gases and high-temperature liquids with high vaporization pressures.
The structure of the vortex pump is simple, the casting and processing technology are easy to achieve, and some vortex pump parts can also use non-metallic materials, such as plastic, nylon molded impeller, etc.
shortcoming:
1 The efficiency is low, up to 55%, and most vortex pumps have an efficiency of 20-40%, thus hindering its development in the direction of high power.
2 Vortex pumps have poor cavitation performance.
3 Vortex pumps cannot be used to pump viscous media. As the viscosity of the liquid increases, the head and efficiency of the pump decrease sharply, and the viscosity of the medium is limited to 114 centipoise.
4 The strict requirements of radial clearance and axial clearance between the vortex pump impeller and the pump body bring certain difficulties to the processing and assembly process.
5 The media pumped is limited to pure liquids. When the liquid contains solid particles, the axial and radial clearances caused by wear will decrease the performance of the pump or cause the vortex pump to fail.
11. Vane pump
Because the history of vane pumps varies according to the type in which there are two types:
A) specifically refers to the sliding vane pump in the positive displacement pump.
2) refers to the three pumps of the power pump (centrifugal pump, mixed current pump, axial flow pump) or other special pumps.
This type of pump product is generally not called a vane pump. However, as a monograph, vane pumps almost all refer to centrifugal pumps, mixed-flow pumps, axial pumps, etc. (the first-class builder's 2014 "Mechanical and Electrical Engineering and Management Practice" called these three types of impeller pumps). According to whether its theoretical displacement per revolution is fixed or variable, it can be divided into vane variable pump and vane type quantitative pump.
(1) The output flow is uniform than the gear pump, the operation is smooth, and the noise is small.
(2) The working pressure is higher and the volumetric efficiency is also higher.
(3) Single-acting vane pump (Tokimec Tokyo meter vane pump) is easy to achieve flow regulation, while double-acting vane pump has a long service life due to the radial fluid pressure balance received by the rotor.
(4) Compact structure, small contour size and large flow rate.
(1) The self-priming performance is worse than that of the gear pump, and the requirements for oil absorption conditions are stricter, and the speed range must be within 500~1500 r/min. (2) It is more sensitive to oil pollution, and the leaves are easily bitten by impurities in the oil, and the reliability of the work is poor.
(3) The structure is more complex, the manufacturing accuracy of parts is higher, and the price is higher. Vane pumps are generally used in medium pressure (6.3 MPa) hydraulic systems, mainly used for machine tool control, especially double-acting vane pumps (Tokyo Meter SQP vane pumps) because the flow rate is very small, so it is widely used in precision machine tools.
12. Steam injection pump
After the steam enters the nozzle, it is sprayed out at high speed, generating a low pressure, sucking the gas in and mixing in the mixing chamber, and after the expansion of the tube, the kinetic energy is converted into pressure energy. If the inhaled gas comes from the vessel, the vessel is decompressed, which can be called a jet vacuum pump.
(1) The pump has no mechanical movement part, is not limited by friction, lubrication, vibration and other conditions, so it can be made into a pump with great pumping capacity. As long as the structural material of the pump is properly selected, it is extremely advantageous for eliminating corrosive gases, gases containing mechanical impurities, and water steaming.
(2) The structure is simple, the weight is light, and the footprint is small.
(3) The working steam pressure is 4 to 9× 10^5Pa, and such a water vapor source is available in general metallurgical, chemical, pharmaceutical and other enterprises.
Because the water vapor injection pump has the above characteristics, it is widely used in metallurgy, chemical industry, medicine, petroleum and food and other industrial sectors.
Thirteen, axial pipeline pump
The impeller is designed as an axial flow type. The speed is very high, if the motor power, impeller diameter, pipe diameter is large enough, the flow rate can be large.
1. The pipeline pump is compact in structure, the machine pump is integrated, and the volume is small. Its vertical structure has a small installation footprint, smooth operation, and no adjustment is required for installation
2, the pump inlet and outlet is designed as the same specifications of the flange, and located in the same center line, can be directly installed on the pipeline like a valve, and the center is low, easy to arrange the pipeline, easy to install.
3. The pump is coaxial with the motor, and the axial size is short, which makes the pump run more smoothly and the noise is low.
4. Cancel the traditional shaft sealing method, avoid the leakage of the conveying medium, so it has the significant characteristics of completely no leakage.
14. Self-priming pump single stage single suction
The working principle of the self-priming pump is that the pump is filled with water in the pump housing (or there is water stored in the pump housing itself) before the pump is started. After starting, the high-speed rotation of the impeller makes the water in the impeller channel flow to the vortex shell, at which time the inlet forms a vacuum, so that the inlet reverse stop door is opened, the air in the suction pipe enters the pump, and reaches the outer edge through the impeller channel.
Self-priming pump is a self-priming centrifugal pump, which has the advantages of compact structure, convenient operation, smooth operation, easy maintenance, high efficiency, long life, and strong self-priming ability. The pipeline does not need to install a bottom valve, and only needs to ensure that there is a quantitative drainage in the pump body before working. Different liquids can be used with different materials of self-priming pumps.
1, strong sewage discharge capacity: special impeller anti-blocking design, to ensure that the pump efficient and non-clogging.
2, high efficiency and energy saving: the use of excellent hydraulic model, the efficiency is 3 to 5% higher than the general self-priming pump.
3, self-priming performance is good: the self-priming height is 1 meter higher than the general self-priming pump, and the self-priming time is shorter.
Fifteen, piston pump
The reciprocating action of the piston in the cylinder makes the cylinder volume change repeatedly to suck in and discharge the fluid.
The piston pump, also known as the electric reciprocating pump, is divided into single cylinder and multi-cylinder from the structure, which is characterized by a higher head. Suitable for conveying oil emulsions without solid particles at room temperature. It is used for oil field, coal seam water injection, oil injection, oil production, the power pump of the chamber press hydraulic press, the hydraulic sand cleaning, the fertilizer plant to transport ammonia liquid, etc. If the overcurrent part is stainless steel, corrosive liquids can be transported. In addition, according to the different structural materials, it can also transport high-temperature tar, mineral mud, high-concentration mortar, high-viscosity liquids, etc.
The piston pump is suitable for high pressure, small flow occasions, especially when the flow rate is less than 100m/h and the discharge pressure is greater than 9.8 MPa, which shows its high efficiency and good running performance. It has good suction performance and can suck up a variety of different media and different viscosities of liquids. Therefore, it is widely used in petrochemical industry, machinery manufacturing industry, papermaking, food processing, pharmaceutical production and so on. Low medium speed piston pump low speed, can be operated by human and animal power tow, suitable for rural water supply and small irrigation.
Sixteen, Roots vacuum pump
Roots pumps work similarly to Roots blowers. Due to the continuous rotation of the rotor, the pumped gas is sucked from the inlet into the space v0 between the rotor and the pump housing, and then discharged through the exhaust port. Since the v0 space is fully enclosed after suction, the gas is not compressed and expanded in the pump chamber. However, when the top of the rotor is turned over the edge of the exhaust port, the v0 space communicates with the exhaust side, due to the high pressure of the exhaust side gas, a part of the gas is rushed back into the space v0, so that the gas pressure suddenly increases. When the rotor continues to rotate, the gas is discharged out of the pump.
Larger pumping speeds over a wide pressure range;
Fast start-up and immediate work;
Insensitive to dust and water vapor contained in the pumped gas;
The rotor does not have to be lubricated, and there is no oil in the pump chamber;
Small vibration, good rotor dynamic balance conditions, no exhaust valve;
Small drive power, small mechanical friction loss;
Compact structure, small footprint;
Low operating and maintenance costs.
Therefore, Roots pumps are widely used in the metallurgical, petrochemical, paper, food, and electronic industries.
17. Rotary vane vacuum pump
The rotary vane of the rotary vane divides the crescent-shaped space enclosed by the rotor, the pump chamber and the two end caps into three parts: A, B and C.
Rotary vane vacuum pump (referred to as rotary vane pump) is an oil-sealed mechanical vacuum pump. Its working pressure range is 101325 ~ 1.33× 10-2 (Pa) is a low vacuum pump. It can be used alone or as a backing pump for other high vacuum pumps or ultra-high vacuum pumps. It has been widely used in metallurgy, machinery, military, electronics, chemical, light industry, petroleum and medicine and other production and scientific research departments.
1. Small size, light weight, low noise;
2. Equipped with a gas ballast valve, which can extract a small amount of water vapor; in the ambient temperature range of 5 degrees Celsius to 40 degrees Celsius, the pressure of the inlet is less than 1.3X10^3 Pa to allow long-term continuous operation, and when the relative humidity of the pumped gas is greater than 90%, the gas town valve should be opened.
3. With automatic anti-return oil check valve, easy to start;
4. The continuous and smooth atmospheric operation of the air inlet shall not exceed one species;
5. It is not suitable for the extraction of gases that have corrosion to metals, chemical reactions to pump oil, contain particulate dust, and gases with excessive oxygen content, explosive and toxic.
Slurry pump refers to the machinery that transports rinsing liquid such as mud or water to the drill hole during the drilling process. Mud pumps are an important part of drilling equipment. In the commonly used positive cycle drilling, it is the surface washing medium - clear water, mud or polymer flushing liquid under a certain pressure, through the high-pressure hose, faucet and drill pipe column center hole directly to the bottom end of the drill bit, in order to achieve the purpose of cooling the drill bit, removing the cut chips and transporting them to the surface. The commonly used mud pump is piston type or plunger type, driven by the power machine to drive the crankshaft of the pump, the crankshaft through the crosshead and then drive the piston or plunger in the pump cylinder to do reciprocating motion. Under the alternating action of the suction and discharge valves, the purpose of pressure transmission and circulation of flushing liquid is realized.
18. Mud pump
1. It can convey high concentration and high viscosity
2. The conveying liquid flow is stable, there is no overcurrent, pulsation and stirring, shear slurry phenomenon.
3, the discharge pressure is not related to the speed, low flow can also maintain a high discharge pressure.
4, the flow rate is proportional to the speed, through the speed mechanism or speed regulation motor can achieve flow adjustment.
5. Strong self-priming ability, no bottom valve can directly suck the liquid.
6. The pump can be reversed, and the liquid flow direction is changed by the direction of rotation of the pump, which is suitable for the occasion when the pipeline needs to be flushed in the opposite direction.
7, smooth operation, vibration, noise is small.
8. Simple structure, easy disassembly and maintenance.
I-1B type thick slurry pump is widely used in chemical, pharmaceutical, brewing, paper, food and other units.
19. Gas booster pump
Driven by compressed air, the low-pressure gas pressure is increased continuously, and the final output pressure can be increased to twice or even dozens of times the pressure of the power source, which is a pollution-free gas booster device. According to the output pressure and structural form, it is divided into low pressure pump and high pressure pump. The low-pressure pump is mainly used to maintain the normal operation of the pneumatic device when the on-site air source pressure is insufficient or unstable, and the minimum use pressure of the pneumatic device cannot be guaranteed, so as to meet the local high-pressure gas requirements of the equipment. The high-pressure pump is mainly used to pressurize non-ordinary compressed air occasions, such as increasing nitrogen, helium, argon, etc. to tens of megapascals and loading into high-pressure gas storage tanks.
(1) The working pressure range is large, and different pressure areas can be obtained by using different types of pumps.
Adjusting the input air pressure and the output air pressure is adjusted accordingly. Extremely high pressures can be achieved, gas 90Mpa
(2) Wide flow range, for all models of pumps only 0.1Kg air pressure can work smoothly, at this time to obtain the minimum flow, adjust the intake volume can get different flow rates.
(3) Easy to control, from simple manual control to complete automatic control can meet the requirements.
(4) Automatic restart, no matter what the reason causes the pressure of the holding circuit to drop, it will automatically restart, replenish the leakage pressure, and keep the circuit pressure constant.
(5) Safe operation, gas drive, no arc and spark, can be used in dangerous occasions.
(6) The maximum energy saving can reach 70%, because it does not consume any energy to maintain the holding pressure.
20. Gas-liquid booster pump
The high-pressure plunger controlled by the check valve continuously discharges the liquid, and the outlet pressure of the booster pump is related to the air-driven pressure. When the pressure between the drive section and the output liquid section is balanced, the booster pump stops running and no longer consumes air. When the output pressure drops or the air-driven pressure increases, the booster pump automatically starts running until it automatically stops after the pressure balance is reached again. A single pneumatically controlled unbalanced gas distribution valve is adopted to realize the automatic reciprocating movement of the pump, and the air drive part of the pump body is made of aluminum alloy. The wetted part is selected according to the different mediums of carbon steel or stainless steel, and the full set of seals of the pump are imported high-quality products, thus ensuring the performance of the gas-liquid booster pump.
(1) High output pressure: the maximum liquid pump can reach 640MPa, and the air pump can be up to 200MPa
(2) Wide range of use: the working medium can be hydraulic oil. Water and most chemically aggressive liquids, and high reliability, maintenance-free life and long life.
(3) Wide range of output flow: for all types of pumps only need a small drive air pressure to work smoothly, at this time to obtain a small flow rate, adjust the drive inlet volume can obtain different flow rates.
(4) Flexible application: different types of pumps can be selected to obtain different pressure areas.
(5) Easy to adjust: within the pressure range of the pump, adjust the regulating valve to adjust the inlet pressure, and the output hydraulic pressure is adjusted accordingly.
(6) Automatic pressure packing: No matter what the reason causes the pressure of the packing circuit to drop, it will be automatically started to supplement the leakage pressure and keep the circuit pressure constant.
(7) Operation safety: gas drive, no arc and spark, can be used in dangerous places.
Source: Chemical 707, New Horizons in Water Treatment. (For sharing and communication only and not for commercial purposes, copyright belongs to the original author and the original author.) If there is infringement, please leave a message in the background, we will delete it at the first time)