The pump is mainly used for transporting liquids, including water, oil, acid and alkali solution, emulsion, suspension emulsion and liquid metal. It also can transport liquids, gas mixtures and liquids containing suspended solids. The promotion of water is very important for human life and production. There are various ancient water appliances, such as Egypt's chain pump (seventeenth Century BC), Chinese shadoof (seventeenth Century BC), Burton (Eleventh Century BC) and water (first Century ad). The more famous one is the spiral rod invented by Archimedes in the third Century B.C., which can steadily lift water to several meters high, and its principle is still used by modern screw pumps.
Around 200 B.C., the fire pump, invented by ancient Greek craftsman Kurt Siby Lucius, is the most primitive piston pump. It already has the main components of typical piston pumps, but the piston pump developed rapidly only after the emergence of steam engine.
1840~1850 years, the United States Worthington invented the pump cylinder and the steam cylinder opposite, the steam direct action piston pump, marked the formation of the modern piston pump. The nineteenth Century was the climax of the development of the piston pump, which was used in a variety of machinery, such as hydraulic press. However, with the rapid increase of water demand, since 1920s, the low speed and high volume piston pumps are gradually replaced by high-speed centrifugal pumps and rotary pumps. But the reciprocating pump in the field of high pressure and small flow still occupies the main position, especially the advantages of diaphragm pump and plunger pump, and the application is increasing day by day.
The emergence of a rotary pump is related to the increasing diversification of the demand for liquid transport in industry. As early as 1588 there about the 4-vane pump records, after the emergence of other types of rotary pump, rotary pump until nineteenth Century but there are still a large leak, wear serious shortcomings and low efficiency. In the early twentieth Century, people solved the problems of rotor lubrication and seal, and developed a high speed motor driven rotary pump suitable for high pressure, small and medium flow rate and various viscous liquids. The types of rotary pumps and the types of liquids suitable for transportation are too much for other types of pumps.
The idea of using centrifugal force to lose water first appeared in the sketches made by Leonardo • Da Vinci. In 1689, French physicist Papin invented 4-impeller volute centrifugal pump. But more close to the modern centrifugal pump, it was a so-called Massachusetts pump with a radial straight blade, a semi open double suction impeller and a volute in the United States in 1818. In the past 1851~1875 years, multistage centrifugal pumps with guide vane have been invented successively, making it possible to develop high lift centrifugal pumps.
Although early in 1754, the Swiss mathematician Ola proposed the basic equation of impeller hydraulic machinery, lay a theoretical foundation for the design of centrifugal pump, but until the end of the nineteenth Century, the invention of high-speed motor makes the centrifugal pump obtain the ideal power source, its advantages can be brought into full play. Based on the theoretical research and practice of many scholars in Renault and Pugh Lederer, Germany, the efficiency of centrifugal pumps has been greatly improved, and its performance range and application area are also expanding. It has become the most widely used and the most productive pump in modern times.
Pumps are usually divided into volumetric pumps, power pumps and other types of pumps, such as jet pumps, water hammer pumps, electromagnetic pumps, and gas pumps. The pump is classified according to the principle of work and can be classified and named according to other methods. For example, according to the driving method, it can be divided into electric pump and water pump. According to the structure, it can be divided into single stage pump and multi-stage centrifugal pump. According to its usage, it can be divided into boiler feed water pump and metering pump. According to the nature of the conveying liquid, it can be divided into water pump, oil pump and mud pump.
Positive displacement pumps rely on working elements in reciprocating or rotary motion in the pump cylinder to increase and shrink the working volume alternately, so as to achieve liquid suction and discharge. Working components for reciprocating movement of the volume pump called reciprocating pump, rotary motion is called a rotary pump. The suction and discharge process of the former is alternated in the same pump cylinder, and is controlled by the suction valve and the discharge valve. The latter is driven by the rotation of working elements such as gears, screws, leaf rotor or sliding vane, forcing the liquid to move from the suction side to the discharge side.
Flow volume pump at a certain speed or reciprocating times which is certain, almost does not change with the stress; reciprocating pump flow and pressure have a larger fluctuation, need to take the pulse of the corresponding mitigation measures; rotary pump without pulsation or only a small ripple; self absorption capacity, after the pump start pumping the line of air inhaled liquids; start the pump discharge pipe when the valve must be fully open; reciprocating pump for high pressure and small flow; rotary pump is suitable for small flow and high pressure; reciprocating pump for conveying clean liquid or gas-liquid mixture. In general, the efficiency of the volume pump is higher than that of the power pump.
The power pump transfers the mechanical energy to the liquid by the action of the fast rotating impeller to the liquid, so that the kinetic energy and pressure can be increased. Then, the most kinetic energy can be transferred to the pressure energy through the pump cylinder to realize the transportation. The power pump is also known as the blade wheel pump or the vane type pump. Centrifugal pump is the most common type of power pump.
Pump power generated under a certain speed of the head has a limit value, the lift changes the flow; continuous conveying, stable work, flow and pressure pulsation; no self absorption capacity, the need to pump first filled with liquid or pipeline pumping into a vacuum in order to begin work; applicability to a wide range of suitable; the cleaning liquid conveying viscosity is very small, the special design of the pump can transport slurry, sewage or water solids. Power pumps are mainly used in water supply
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