Pump is to transport fluid or pressurized fluid machinery, mainly used to transport water, oil, slurry, acid lye, emulsion, suspension emulsion, gas mixture and liquid metal, etc., is a common transportation equipment in mining, chemical and metallurgical industries. The following are the dynamic working principles and characteristics of 19 kinds of pumps (gear pump, centrifugal pump, screw pump, reciprocating pump, piston pump, hydraulic plunger pump, mud pump, pneumatic diaphragm pump, axial flow pipeline pump, self-priming pump, vortex pump, water ring vacuum pump, Roots vacuum pump, rotary vane vacuum pump, gas booster pump, gas hydraulic booster pump, steam jet pump). In order to everyone in the selection and use of the pump has a certain help.
1, gear pump
Working principle: The teeth of the two gears of the gear pump separate from each other, forming a low pressure, and the liquid is inhaled and sent to the other side along the shell wall. The other side of the two gears close each other, forming a high pressure to discharge the liquid.
Advantages: simple and compact structure, small size, light weight, good process, cheap price, strong self-suction, insensitive to oil pollution, large speed range, impact load resistance, easy maintenance, reliable work.
Disadvantages: radial force imbalance, large flow pulsation, loud noise, low efficiency, poor interchangeability of parts, not easy to repair after wear, can not be used as variable pump.
2, centrifugal pump
Working principle: When the centrifugal pump works, the liquid fills the pump shell, the impeller rotates at high speed, the liquid produces high speed under the action of centrifugal force, and the high-speed liquid passes through the gradually expanded pump shell channel, and the dynamic pressure head is transformed into the static pressure head.
High efficiency and energy saving: the pump has a high efficiency hydraulic shape line, high efficiency.
Easy installation and maintenance: vertical pipe structure, pump inlet and outlet can be installed in any position and any direction of the pipeline like a valve, installation and maintenance is very convenient.
Stable operation, safe and reliable: motor shaft and pump shaft are coaxial direct connection, high concentricity, stable operation, safe and reliable.
Stainless steel shaft sleeve: the sealing position of the shaft is relatively easy to be rusted, and once the direct-connected pump shaft is rusted, it is easy to cause mechanical seal failure. Stainless steel shaft sleeve is used to avoid rust, increase shaft life and reduce operation and maintenance costs.
Bearing: The lower shaft extension bearing of the motor equipped with the pump adopts a closed bearing, which is free from the maintenance of the motor bearing during normal use.
Mechanical seal: mechanical seal base parts generally use rubber bellows structure, the traditional mechanical seal shaft seal from the O-ring line seal to rubber parts of the two face seal, in the water medium to improve the sealing effect.
3, multistage centrifugal pump
Working principle: Multi-stage centrifugal pump compared with a single stage pump, the difference is that the multi-stage pump has more than two impingers, which can absorb water and pressure water in different stages, so as to lift the water to a high position, and the head can be increased or decreased according to the needs of the pump impeller.
Multistage centrifugal pump has vertical and horizontal two types, the pump shaft of the multistage centrifugal pump is equipped with two cascaded impeller, it is relative to the general single-stage centrifugal pump, can also achieve higher head.
Performance characteristics: multistage pump is mainly used for mine drainage, city and factory water supply. Compared with reciprocating pumps such as piston pumps and diaphragm pumps, it can also pump a larger flow rate. The multi-stage centrifugal pump has high efficiency and can meet the needs of high head and 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, multistage centrifugal pumps have different and higher technical requirements in terms of design, use and maintenance.
4, screw pump
Working principle: double screw pump and gear pump is very similar, a screw rotation, drive another screw, the liquid is intercepted in the meshing chamber, along the direction of the shaft, and then squeezed to the center discharge.
Advantages of screw pump:
Wide range of pressure and flow. The pressure is about 3.4-340 kg force /cm2, and the flow rate can reach 100cm3/ min.
The type and viscosity range of the transported liquid is wide, and the concentrator can be used to transport collectors, flocculants, etc.
Because the inertia force of the rotating parts in the pump is low, it can use a high speed;
Good suction ability, with self-imbibition ability;
The flow rate is uniform and continuous, the vibration is small, the noise is low;
Compared with other rotary pumps, it is less sensitive to incoming gas and dirt;
Solid structure, easy installation and maintenance.
Disadvantages of screw pump: screw processing and assembly requirements are higher; The performance of the pump is more sensitive to changes in the viscosity of the liquid.
5, reciprocating pump
Working principle: When the reciprocating pump works, the piston moves to the right, the pressure in the cavity is reduced, the upper valve is pressed down, the lower valve is lifted, and the liquid is inhaled; The piston moves to the left, the pressure in the cavity increases, the upper valve is lifted, the lower valve is pressed down, and the liquid is discharged.
Reciprocating pump advantages:
High discharge pressure can be obtained, and the flow is independent of pressure, the suction can be good, the efficiency is high, and the steam reciprocating pump can reach 80% to 95%;
In principle, it can transport any medium, almost not limited by the physical or chemical properties of the medium;
The performance of the pump does not change with the pressure and the viscosity of the conveying medium.
Disadvantages of reciprocating pump: the flow rate is not very stable. Larger than centrifugal pump under the same flow rate; The mechanism is complex; Large amount of funds; Not easy to repair, etc.
6, double acting reciprocating pump
Working principle: When the double-acting reciprocating pump works, the piston moves to the right, the left lower suction, the right upper drainage. Piston moves left, right down suction, left up drainage. The piston reciprocates once, and there are two suction and drainage, and the flow rate is more uniform.
7. Piston pump
Working principle: piston pump is also called electric reciprocating pump, which is divided into single cylinder and multi-cylinder from the structure. When the piston pump works, the reciprocating action of the piston in the cylinder makes the cylinder content change repeatedly to inhale and discharge the fluid.
Piston pump performance characteristics:
The piston pump is suitable for high pressure and small flow, especially when the flow is less than 100m3/h and the discharge pressure is greater than 9.8 mpa, which shows its high efficiency and good operating performance.
Good suction, can suck a variety of different media, different viscosity of the liquid, can be used for oil field, coal seam water injection, oil injection, oil recovery. If the flow parts are stainless steel, corrosive liquids can be transported. In addition, according to the different structural materials, it can also transport high temperature tar, slime, high concentration mortar, high viscosity liquid.
Piston pump is widely used in petrochemical industry, machinery manufacturing industry, paper making, food processing, pharmaceutical production and so on.
8, hydraulic plunger pump
Working principle: Hydraulic plunger pump or solid pump, the hydraulic power pack drives the hydraulic cylinder, the hydraulic cylinder promotes the conveying cylinder, and the material in the conveying cylinder is output to the pipeline.
Generally divided into single and double plungers, the basic principle of the plunger pump is very simple, this pump uses the momentum of a relatively large moving body of water to pump a relatively small volume of water to a high place.
Hydraulic piston pump is widely used in sewage treatment, solid waste treatment, mining metallurgy, dredging, petrochemical, power plant, cement industry and other fields.
9. Mud pump
Working principle: The commonly used mud pump is piston or plunger type, driven by the power engine pump crankshaft rotation, crankshaft through the cross head and then drive the piston or plunger in the pump cylinder to do reciprocating movement. Under the alternating action of suction and discharge valves, the purpose of pressing and circulating flushing liquid is realized.
Mud pump refers to the drilling process to the drilling hole to transport mud or water and other washing fluid machinery, is an important part of drilling equipment.
In the commonly used positive circulation drilling, the surface flushing medium – water, mud or polymer flushing liquid is directly sent to the bottom of the drill bit through the high-pressure hose, faucet and the center hole of the drill pipe string under a certain pressure, in order to cool the drill bit, remove the cuttings cut down and transport to the surface.
10, pneumatic diaphragm pump
Working principle: When the pneumatic diaphragm pump works, in order to make the living column not in direct contact with the corrosive material liquid, the cylinder chamber is separated from the liquid material by the diaphragm, which is also the principle of the reciprocating pump. Pneumatic diaphragm pump has four materials: engineering plastic, aluminum alloy, cast iron, stainless steel.
Performance characteristics of pneumatic diaphragm pump
Using compressed air as power source, it can be used for various corrosive liquids. Different materials can be used according to different liquid media to meet the needs of different users.
The pump will not overheat: compressed air for power, in the exhaust is an expansion heat absorption process, the temperature is reduced when the pneumatic pump is working, no harmful gas discharge.
No electrical sparks: The pneumatic diaphragm pump does not use electricity for power, and prevents electrostatic sparks after grounding
Liquid containing particles can be passed: because of the positive displacement type and the inlet is a ball valve, it is not easy to be blocked.
The shear force on the material is very low: how to suck in and spit out when working, so the agitation of the material is minimal, which is suitable for the transport of unstable substances
The flow can be adjusted, and a throttle valve can be installed at the outlet of the material to adjust the flow.
It has self-priming function.
It can run empty without danger.
Can dive work.
A wide range of fluids can be transported, from low viscosity to high viscosity, from corrosive to viscous.
No complex control systems, no cables, fuses, etc.
Small size, light weight, easy to move.
No lubrication is required, so the maintenance is simple and will not pollute the working environment due to drip.
The pump is always efficient and does not degrade due to wear.
100% energy utilization, when the outlet is closed, the pump automatically stops, the equipment moves, wears, overloads, and heats up
No dynamic seal, easy maintenance to avoid leakage. There are no dead ends at work.
11, axial flow pipeline pump
Working principle: The impeller of the axial flow pipeline pump is designed to be axial flow, the speed is very high, if the motor power, impeller diameter, pipe diameter is large enough, the flow can be large.
Axial flow pipeline pump performance characteristics:
The pipeline pump has compact structure, integration of machine and pump, small size, and its vertical structure has a small installation area, smooth operation, and no installation adjustment.
The inlet and outlet of the pump are designed to have the same specifications flange, and are located in the same center online, which can be directly installed on the pipeline like a valve, and the center is low, which is convenient for pipeline layout and easy installation.
The pump is coaxial with the motor, and the axial size is short, which makes the pump run more smoothly and has low noise.
The traditional shaft sealing method is cancelled to avoid the leakage of the conveying medium, so it has the remarkable characteristics of completely no leakage.
12, self-priming pump
Working principle: Before starting the pump, fill the pump shell with water (or the pump shell itself contains water). After starting, the impeller rotates at high speed to make the water flow in the impeller groove to the vortex shell, then the inlet forms a vacuum, so that the water inlet check door is opened, the air in the suction tube enters the pump, and reaches the outer edge through the impeller groove.
Self-priming pump performance characteristics:
Self-priming pump is a self-priming centrifugal pump, which has the advantages of compact structure, easy operation, smooth operation, easy maintenance, high efficiency, long life, and strong self-priming ability.
The pipeline does not need to install the bottom valve, and only need to ensure that there is a quantitative primer stored in the pump body before work. Different liquids can be self-priming pumps of different materials.
13, whirlpool pump
Working principle: The liquid in the groove of the blade of the vortex pump is thrown to the flow channel by centrifugal force and pressurized once; The liquid in the flow channel is thrown out of the liquid in the tank to form a low pressure, and then enters the groove again and is pressurized again. The vortex motion of multiple grooves leads to a higher pressure head.
Advantages of vortex pump:
W type single-stage direct-connected vortex pump is used for suction and delivery of water or liquid similar to water in physical and chemical properties, the use of liquid temperature does not exceed 60℃, often used in boiler water supply, shipbuilding, textile, chemical industry, metallurgy, machinery manufacturing, aquaculture, fixed fire pressure regulation, heat exchange units, agricultural remote sprinkler irrigation and other departments have a wide range of applications.
Vortex pump has great advantages in Marine installations because of its small size and light weight. Self-priming ability or with the help of a simple device to achieve self-priming.
It has a steep drop head characteristic curve and is therefore insensitive to pressure fluctuations in the system. Some vortex pumps can realize steam and liquid mixed transport. This is of great significance for pumping volatile liquids containing gases and high temperature liquids with high vaporization pressure.
Vortex pump structure is simple, casting and processing technology are easy to achieve, some vortex pump parts can also use non-metallic materials, such as plastic, nylon molded impeller.
Disadvantages of vortex pump:
The efficiency is low, the maximum is not more than 55%, and the efficiency of most vortex pumps is 20-40%, thus hindering its development to the direction of high power.
The cavitation performance of vortex pump is poor.
Vortex pumps cannot be used to pump viscous media. As the viscosity of the liquid increases, the lift and efficiency of the pump will be sharply reduced, and the viscosity of the medium is limited to 114 CST.
The requirement of radial clearance and axial clearance between impeller and pump body is strict, which brings some difficulties to machining and assembly process.
The pumping medium is limited to pure liquids. When the liquid contains solid particles, the axial and radial clearance will increase due to wear, which will reduce the performance of the pump or cause the vortex pump to not work.
14, water ring vacuum pump
Working principle: The impeller of the water ring vacuum pump blade is mounted eccentrically in the cylindrical pump housing. A certain amount of water is injected into the pump. When the impeller rotates, water is thrown to the pump housing to form a water ring, and the inner surface of the ring is tangent to the impeller hub. Due to the different heart of the pump shell and the impeller, the intake space 4 between the right half wheel hub and the water ring gradually expands, thus forming a vacuum, so that the gas enters the intake space in the pump through the intake pipe. Then the gas enters the left half, as the volume between the hub ring is gradually compressed and the pressure is increased, so the gas is discharged to the pump through the exhaust space and exhaust pipe.
Advantages of water ring vacuum pump:
Simple structure, manufacturing precision requirements are not high, easy to process.
Compact structure, pump speed is high, generally can be directly connected with the motor, no deceleration device. Therefore, with a small structure size, you can obtain a large displacement and occupy a small area.
The compressed gas is basically isothermal, that is, the temperature of the compressed gas process changes very little.
Because there is no metal friction surface in the pump chamber, there is no need to lubricate the pump, and the wear is very small. The sealing between the rotating part and the fixed part can be done directly by the water seal.
The suction is uniform, the work is stable and reliable, the operation is simple, the maintenance is convenient.
Disadvantages of water ring vacuum pump:
The efficiency is low, generally about 30%, and the best can reach 50%.
Low vacuum, this is not only because of structural limitations, more importantly, by the working fluid saturation.