Water and type
The ascension of water is important for human life and production. Ancient times has had a variety of water appliances, such as Egypt's chain pump (17th century BC), China's shadoof (17th century BC), jigger (11th century BC) and the water wheel (the 1st century AD). Also famous is the spiral rod invented by Archimedes in the third century BC, which can lift water to several meters continuously and smoothly. Its principle is still used by modern screw pumps.
Around 200 BC, the ancient Greek craftsmen invented by Kurt west than uz fire pump is one of the most primitive piston pump, has typical piston pump's main components, but the piston pump only after the steam engine got rapid development.
In 1840-1850, worthington invented a piston pump with steam acting directly on pump cylinder and steam cylinder, marking the formation of modern piston pump. The invention of multistage centrifugal pumps with guide vanes in 1851-1875 made it possible to develop high-lift centrifugal pumps. The 19th century was the height of the development of piston pumps, which were used in hydraulic machines and other machinery. However, with the rapid increase of water demand, from the 1920s, low-speed piston pumps with limited flow were gradually replaced by high-speed centrifugal pumps and rotary pumps. But in the high pressure small flow field reciprocating pump still occupies the main position, especially the diaphragm pump, plunger pump has the unique advantages, the application is increasing day by day.
Back to the transformation of
The appearance of rotary pump is related to the increasing diversification of industrial requirements for liquid transportation. As early as in 1588 had about four blade vane pump, later emerged in succession various rotary pump, but it was not until the 19th century rotary pump there are still large leakage, wear and low efficiency of disadvantage. At the beginning of the 20th century, people can solve the problem of rotor lubrication and sealing, and use high speed motor drive, suitable for high pressure, small flow and all kinds of viscous liquid rotary pump got rapid development. The type of rotary pump and the type of liquid suitable for transportation are more than other types of pumps.
The centrifugal type
The idea of using centrifugal force to transport water was first developed in leonardo Da Vinci's sketches. In 1689, the French physicist papin invented a volute centrifugal pump with a four-blade impeller. But closer to the modern centrifugal pump is the so-called Massachusetts pump with radial straight blades, semi-open double-suction impeller and volute casing that appeared in the United States in 1818. From 1851 to 1875, multistage centrifugal pumps with guide vanes were successively invented, making it possible to develop high-lift centrifugal pumps.
Although as early as in 1754, the Swiss mathematician euler proposed basic equations for impeller type hydraulic machinery, laid the theoretical basis of design of centrifugal pump, but it was not until the end of the 19th century, the invention of the high-speed motor centrifugal pump to obtain the ideal power source, to give full play to its superiority. Renault in the UK and Germany's puff dreier and many other scholars, on the basis of theory research and practice of centrifugal pump efficiency is greatly increased, the scope of its performance and use is also growing, has become a modern applied most widely, the largest output pump.
1. The choice of centrifugal pump and installation of centrifugal pump should be based on the liquid transported, and check the performance required, analyze the suction and discharge conditions, intermittent operation or continuous operation, etc. Centrifugal pumps shall normally operate under or near the pressure and flow conditions specified in the manufacturer's design. The following review shall be conducted when installing the pump:
The size, position and elevation of the concrete foundation shall meet the design requirements, and the anchor bolts shall be properly and correctly fixed in the concrete foundation.
According to the characteristics of the medium conveyed by the circulating pump, the materials of main parts, shaft seals and gaskets should be checked if necessary.
(3) the leveling of the pump, is to get a job should comply with the provisions of the equipment technical documents, without rules, should be consistent with the current national standard "mechanical equipment installation engineering code for construction and acceptance of the general regulations;
All piping connected to the pump body, installation of piping fittings and cleaning requirements of lubricating oil piping shall comply with relevant national standards.
2. The test run of centrifugal pump should meet the following requirements:
The steering of the drive should be the same as that of the pump.
Investigation of the steering of the tube pump and the spindle pump;
Never loosen any fixed connection parts, and the specification and quantity of lubricants added to each lubrication part shall conform to the provisions of technical documents of the equipment.
The parts with prelubrication requirements shall be prelubricated in accordance with the provisions;
Each indicator and safety protection device should be sensitive, accurate and reliable.
Should be flexible without abnormal phenomenon.
7) should be done before the heat pump in the test run the pump body preheating, temperature rise should be uniform, should not be greater than the temperature of 50 ℃ per hour; Pump body surface and has a working medium import process piping temperature difference should not be greater than 40 ℃;
Also set up a connection device to eliminate the influence of temperature rise, and set up a bypass connection device to provide cooling water.
When operating the centrifugal pump, the following points should be noted:
It is prohibited to operate without water, not to adjust the suction population to reduce the displacement, and not to operate under too low flow;
Parliamentary monitoring of the operation process to completely prevent the leakage of the stuffing box, new stuffing should be used when replacing the stuffing box;
Torque ensures that the mechanical seal has sufficient flushing water flow, and water-cooled bearings are prohibited from using excessive water flow;
Superior lubricants should not be used too much;
Transaction is conducted on a recommended cycle. Establish operating records, including running hours, packing adjustment and replacement, addition of lubricants and other maintenance measures and times. The suction and discharge pressure, flow rate, input power, temperature and vibration of the cleaning fluid and bearings of the centrifugal pump should be measured and recorded regularly.
The pump's main engine pumps water from low to high levels at atmospheric pressure, which only supports about 10.3m of the water column at most, so the pump's main engine is 12 metres above the surface of the water.
3. Maintenance of centrifugal pump
3. 1. Analysis of mechanical seal failure of centrifugal pump
The shutdown of centrifugal pump is mainly caused by the failure of mechanical seal. Most of the failures are leakage, and the reasons are as follows:
The leakage of the sealing surface of the static and static ring is mainly caused by: the surface plane of the end face, the roughness is not up to the requirement, or the surface is scratched; There is granule material between the end surfaces, so the two end surfaces cannot operate in the same way. The installation is not in place and the method is not correct.
The main reasons for the leakage of the compensating ring seal ring are: deformation of the pressing cover and uneven pre-tightening force; Incorrect installation; The seal ring quality does not meet the standards; The seal ring is not selected correctly.
The practical application results show that the most frequently failed parts of the sealing elements are the end face of the moving ring, the end face of the static ring, the sealing movement of the centrifugal pump machine, and the cracking of the end face of the static ring is a common failure phenomenon, mainly caused by:
When installing, the clearance of the sealing surface is too large, and the washing liquid is too late to take away the heat generated by the friction pair. The washing liquid leaked out from the clearance of the sealing surface, causing the end surface to overheat and damage.
The two end faces are separated by the vaporization and expansion force. When the two sealing surfaces are pressed together with each other, the lubrication film is damaged, causing the end surface to overheat.
Due to poor lubricity of the liquid medium and overload of operating pressure, the two sealing surface tracking rotation is out of sync. Such as high speed pump rotating speed of 20445 r/min, sealing surface center 7 cm diameter, pump running after the linear speed up to 75 m/s, when there is a lag cannot track rotating on sealing surface, instantaneous heat sealing surface damage.
The sealing washing liquid orifice plate or filter screen is blocked, resulting in insufficient water supply and machine seal failure.
In addition, the sealing element fails because of the sliding groove on the surface of the sealing surface and the gap in the end face bonding. The main reasons are:
The liquid medium is not clean, there are small hard particles, with a high speed to slide the sealing surface, the end surface of the surface will be damaged and ineffective.
The drive parts of circulating pump of circulatory machine have poor coaxial degree, and the end face of circulating pump is shaken and rubbed once every week after opening.
The frequent occurrence of hydraulic characteristics of the liquid medium causes the vibration of the pump set, resulting in the misalignment of the sealing surface and failure.
Liquid medium corrosion of seal element, stress concentration, hard and soft materials, erosion, auxiliary seal ring 0, v-shaped ring, concave ring and liquid medium are incompatible, the surface damage of the mechanical seal failure deformation, etc, so the damage form to comprehensive analysis, find out root cause, ensure mechanical seal for a long time operation.
3. 2. Requirements after the centrifugal pump stops operation
When the centrifugal pump stops operation, the inlet valve of the pump should be closed, and the valve of the auxiliary system should be closed successively after the pump cools.
(2) heat pump stop shall be governed by the provisions of the equipment technical documents, should be each partial 20 30 min after stop turning, half a circle until the pump body temperature down to 50 ℃.
When the low temperature pump stops, when no special requirements, the pump should always be filled with liquid; The suction valve and discharge valve shall remain normally open; The grouting pressure of the pump shall be maintained by the low temperature pump with mechanical seal on both end face, the liquid level controller and the sealing liquid in the pump sealing chamber.
The pumps which are easy to crystallize, solidify and precipitate should be stopped to prevent blockage and wash the pumps and pipelines with water or other media in time.
Flow out of trapped liquid in the pump to prevent corrosion and frostbite.
3. 3. Storage of centrifugal pump
(1) has not been installed pump in the unpainted surface should be coated with a layer of suitable corrosion inhibitor, oil lubricated bearings should be filled with the appropriate oil and grease lubricated bearings should only fill a grease, do not use a mixture of grease.
Circulating cooling water pumps clean liquid, flush, drain line, discharge line, pump shell and impeller, clean pump shell, sucker string and discharge line of washing liquid.
Remove grease from bearing box, add clean oil, thoroughly clean grease and refill new grease.
To seal up the absorber and discharge port, store the pump in a clean, dry place, protect the motor winding from dampness, and spray the inner part of the pump casing with anti-rust liquid and anti-corrosion liquid.
Flow pump shaft turns once a month to avoid freezing and lubricate bearings.
The volumetric pump relies on the working element to reciprocate or rotate in the pump cylinder, making the working volume increase and decrease alternately, so as to realize the suction and discharge of the liquid. The volumetric pump that the working element makes reciprocating motion is called reciprocating pump, and the one that makes rotary motion is called rotary pump. The suction and discharge processes of the former are carried out alternately in the same pump cylinder and controlled by the suction valve and the discharge valve. The latter is driven from the suction side to the discharge side by the rotation of working elements such as gears, screws, lobed rotors or slides.
Volume pump in a certain speed or reciprocating times under a certain flow rate is a certain, almost does not change with the pressure; The flow and pressure of the reciprocating pump fluctuate greatly, and corresponding measures should be taken to reduce the fluctuation. Rotary pumps generally have no pulse or only small pulse; With self-priming ability, the pump can remove the air inhalation liquid in the pipeline immediately after starting; When starting the pump, the discharge line valve must be fully opened. Reciprocating pump is suitable for high pressure and small flow. Rotary pump is suitable for medium and small flow and high pressure. Reciprocating pump suitable for conveying clean liquid or gas mixture. Generally speaking, the efficiency of volume pump is higher than that of power pump.
By rapidly spinning, the power of the impeller on the liquid to mechanical energy transmitted to the liquid, make its kinetic energy and pressure can increase, and then through the pump cylinder, will be carrying can and do most of the kinetic energy is converted to pressure. Power pump is also known as impeller pump or blade pump. Some power pumps have the main impeller and the secondary impeller used at the same time, centrifugal pump is the most common power pump.
The lift produced by the power pump at a certain speed has a limited value, and the lift is changed with the flow. Stable operation, continuous transmission, no pulsation of flow and pressure; Generally, there is no self-priming capacity, and the pump needs to be filled with liquid or vacuum the pipeline before starting to work. Wide range of applicable performance; Suitable for conveying clean liquid with low viscosity.
Type of sewage
Impeller, pressurized water chamber, are two core components of sewage pump. The structure of impeller can be divided into four categories: blade type (open type, closed type), rotary type, runner type, (including single channel and double channel) spiral centrifugal type. The pros and cons of its performance, also on behalf of the advantages and disadvantages of pump performance, the anti-clogging sewage pump performance, efficiency, and cavitation performance, anti-abrasion performance mainly by the impeller and the pressurized water chamber to ensure that the two parts.
The diaphragm pump, also known as the control pump, is the main type of actuator. By receiving the control signal from the modulation unit, the fluid flow is changed with the help of dynamic operation. Diaphragm pumps generally consist of actuators and valves. Using compressed air as the power source, all kinds of corrosive liquids, granular liquids, high viscosity, volatile, inflammable and highly toxic liquids can be drained away.
I. overview of diaphragm pump
Pneumatic diaphragm pump has four materials: plastic, aluminum, cast iron, stainless steel. Electric diaphragm pump has four materials: plastic, aluminum, cast iron, stainless steel. According to different liquid media, the diaphragm pump adopts nitrile rubber, chloroprene rubber, fluoro rubber, polyvinylidene fluoride, polytetrafluoroethylene respectively. To meet the needs. Set up in a variety of special occasions, used to pump a conventional pump can not pump the medium.
Ii. Type of diaphragm pump
Diaphragm pump by their ticket enforcement agencies use the power, can be divided into pneumatic, electrical, fluid movement three, namely to compressed air to power sources pneumatic diaphragm pump, based on electric power electric diaphragm pump, as a liquid medium (such as oil) pressure as the power of electric hydraulic diaphragm pump.
Diaphragm pump role in the process control is to accept the regulator control signal, or computer change modulated medium flow, make the modulated maintain within the scope of the required parameters, so as to achieve the automation of production process. If the automatic adjustment system is compared with the manual adjustment process, the detection unit is the human eye, and the control unit is the human brain, then the executive unit, the diaphragm pump, is the human hand and foot. The diaphragm pump is indispensable to realize the adjustment and control of some parameters of the process, such as temperature, pressure, flow rate and liquid level. Therefore, it is of great importance to choose diaphragm pump correctly in process automation.
Other types of
Other types of pumps are those that transfer energy in other ways. For example, the jet pump relies on the working fluid which is ejected out at high speed. The fluid that needs to be transported is sucked into the pump, and the energy is transferred through the momentum exchange between two fluids. The water hammer pump USES the energy generated when the water in the flow is suddenly stopped, so that part of the water pressure rises to a certain height. Electromagnetic pump is to make the electrified liquid metal under the action of electromagnetic force, the generation of flow and delivery; Air lift pump through the catheter to compressed air or compressed gas to the liquid at the bottom of the other, to form a liquid gas-liquid mixing of fluid, then borrow pipe outside the pressure of the liquid will come up mixed fluid pressure.
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