Volume loss of centrifugal pump including seal ring leakage loss, balancing mechanism leakage loss and interstage leakage loss. This article describes the seal ring leakage loss.
In the entrance of the impeller is a seal ring, when the pump works, because the sealing ring on both sides with pressure difference between the side of the approximately impeller outlet pressure side of the impeller inlet pressure, so there will always be a part of the liquid from the impeller to the outlet impeller inlet leak. This part of the liquid in the impeller in obtaining energy, but the liquid did not sent, thus reducing the water supply pump. All the energy used to overcome the leakage of fluid resistance of the seal ring.
Obviously, if the sealing ring diameter larger ,pressure on both sides is more special, the greater the amount of leakage. For stereotypes pump, in order to improve feed efficiency of the pump leakage amount should be permitted in the case of the sealing ring gap is narrowing. Usually approximated total clearance seal ring diameter of 0.002, as Dw = 200 mm, the total clearance of 0.40 mm, when assembled, the sealing ring can not be eccentric too large, otherwise the amount of leakage also increases. The main measures In addition, the sealing ring can be used to increase the resistance method of reducing the amount of leakage, increase the resistance of the seal ring is made of a maze, zigzag, etc., which also increases the length of the sealing ring seal, increasing the resistance along the way.
Ring seal leakage, and in some cases cause disturbance of the impeller inlet, so will the rational design of the sealing ring form.
First, compare various suppliers program when select centrifugal pump, taking into account the premise of cost-effective as far as possible under the high efficiency of the program
Second, the presence of a number of professionals in the plant producer, the impact of industrial pump efficiency of key components such as impeller, pump, pump cover, flow guide (vertical long shaft pump), such as manufacturing quality supervision, Impeller wing, the water angle, the blade indexing, flow channel shape, finish quality control, so that delivery of products in the current production conditions of high efficiency products
Third, in the production site of the installation and commissioning process, to ensure that the basis of a solid pump, with the drive on the good, flexible before and after the valve switch, pipeline layout design reasonable, safe and feasible on-site control, monitoring instrumentation complete running accurate to ensure The operation of the pump can be monitored in real time
The last step is in the long-term operation of the pump to pay attention to the point of inspection equipment, abnormal situation immediately reflect the report, in the normal minor repair, overhaul cycle, the vulnerability should be checked and replaced to ensure long-term efficient pump safety Of the operation.
The emergence of pumps for human life and production are very important. There are various water lifting devices in ancient times, such as the Egyptian chain pump (before the 17th century), China’s orange (before the 17th century), the pulley (before the 11th century), waterwheel (AD 1 century), and the 3rd century BC Ancient Greece Archimedes invented the spiral rod and so on. About 200 BC, the ancient Greek craftsmen Cesius Beius invented the most primitive piston pump – fire pump. As early as 1588 there will be on the 4 blade vane pump records, after the emergence of a variety of other rotary pump. In 1689, the French D. Papan invented the 4-blade impeller centrifugal pump volute. In 1818, the United States appeared with radial straight blade, semi-open double suction impeller and volute centrifugal pump. 1840 ~ 1850, the United States H.R. Worthington invented the pump cylinder and the steam cylinder directly against the steam piston pump action, marking the formation of modern piston pump. 1851 ~ 1875, with guide vanes of the multi-stage centrifugal pump have been invented, so that the development of high-lift centrifugal pump possible. Subsequently, a variety of pumps have come out. With the application of advanced technologies, the efficiency of the pump has been gradually improved, and the range and application of the pump has been expanded.
In recent years, China’s pump industry has entered the forefront of the world. Of which at least 70% of private enterprises, with a vast market and consumption potential for the development of China’s pump industry the main force. Lanshen group’s products are based on foreign demand for the pump industry, the export side of a number of adjustments to expand the external market, from the sales point of view, the results are gratifying.
As the talent, technology, equipment, management level that the concept of the introduction and application, Nanjing Lanshen Group‘s variety of products in the same industry leading position, not only that, the deep blue pump also has a comprehensive integrated service system : Including the early professional and technical personnel to quickly answer the technical advice to meet your needs, you choose the right products, provide reasonable and reliable recommendations on the quality of products, such as the commitment to supply cycle, to provide specific product programs and pricing. After-sales include: to provide product installation, use, maintenance, troubleshooting and other services.
In addition, lanshen pump has the highest level of domestic pump performance testing center, all products using CAD design software and CFD computational fluid dynamics software and other advanced design tools, all products through precision casting, hot forging, welding, heat treatment, finishing, assembly And the use of information technology, automation technology, modern control and management technology, so that the level of machinery products and service levels to a new level.
In recent years, the development of pump industry has been greatly improved, especially in the fields of industry and agriculture, such as centrifugal pumps and submersible pumps. The state-owned enterprises are the leading enterprises, Private enterprise as the mainstay of a number of regional industrial clusters, both to promote the local economic development, but also to promote the industry’s progress.
In many centrifugal pumps, it do not balance the axial thrust mechanism: such as balancing holes, balance pipe, balance disc and the like. Since both sides of the balance mechanism there is a pressure difference, which is also a part of the liquid leakage from a high pressure area to the low pressure area. About 5% of the balance holes reduce leakage will pump efficiency. In the balance disc mechanism, the amount of leakage usually accounts for 3% of the work flow, but some high-pressure pump is larger than this; in order to reduce the leakage loss can be reduced balance disc diameter D without affecting the counterweight situation ‘.
Hydraulic loss of centrifugal pump including shock loss, whirlpool loss and frictional loss.
First, the shock loss
Each pump has its own design flow, when consumed in the design flow conditions at work, the entrance is down stream into the impeller blades, and therefore does not react with the blade hit the same outlet flow nor the occurrence and the impact of the pump housing, then a high efficiency. However, when the flow rate deviates from the design condition, it is necessary to deviate from the direction of the flow direction of the blade occurs, have an impact.
Second, whirlpool loss
In the water pump, flow cross-section is very complex spatial cross-section, where the liquid through the flow rate and direction are too small to be constantly changing, so inevitably produce swirl losses. Also the presence of overcurrent sharp corners, burrs, also increases the loss of dead zones whirlpool surface.
Third, the frictional loss
Since the pump flow surface roughness and a viscous liquid, the liquid when swimming will produce friction losses. Loss size indicated by the following formula;
Hm = AQ2 formula A– coefficient.
Videos on the coordinates, that is a vertex at the origin of the parabola.
In various parts of the hydraulic losses, the loss of hydraulic impeller largest, accounting for about half of all black and white confuse losses; followed by the loss of hydraulic vane corner, accounting for about a quarter of all hydraulic losses, while the remaining 1 / 4 hydraulic losses, the loss to the impeller vanes, guide vane diffuser section, ABM leaves the impeller inlet and several other parts.
In order to reduce hydraulic loss of the pump, the flow of each section should be changed slowly, the speed of a reasonable size. And the appropriate choice of the impeller, guide vane type and placement of the entrance angle. It should also improve the flow through the surface finish of parts.
Centrifugal losses includes bearing, shaft seal and the impeller rub against the disk losses.
First, the bearings, shaft seal friction loss
Pump shaft is supported on bearings within the pump in order to prevent leakage of liquid out, set the seal. When the pump shaft rotates at high speed on friction with the bearing and shaft seal. In general, frictional losses are small, as: △ N = (0.01 ~ 0.03) N
Where △ N– friction loss; N– prime mover transmitted to the pump shaft power.
Second, the impeller and disc friction loss
Centrifugal impeller rotating liquid-filled pump housing, then cover the outer surface of the impeller and the liquid occurs causing friction between the friction loss.
Disc friction loss throughout the mechanical loss accounted for a larger proportion, particularly in some of the low number of revolutions of the pump even more so. Relationship between disc friction loss and the ratio of the number of revolutions. Low specific speed pumps, discs
Friction loss stingy faster, such as specific speed ns = 30, the disc friction loss increases to 30% effective power; and high specific speed pumps, a smaller proportion of the disc friction loss. Multi-stage pumps in various percentage of energy loss in a typical case:
Shock and swirl loss is 7%
Impellers and disc of balance disc friction loss is 5%
Clearance leakage loss is 2%
Balance mechanism leakage is2%
Hydraulic surface friction loss is 4%
The working principle of centrifugal pump is that when pump is filled with water, centrifugal force generated by the rotation of the impeller, the impeller channel water thrown to the periphery by centrifugal force flows into the pump housing, thus reducing the pressure on the center of the impeller, the pressure is lower than the inlet the pressure, the water at this pressure difference flows into the pool by the suction impeller. Such pumps can continue to supply the water continuously.
Addition of the impeller, spiral casing role is also very important. The energy obtained from the liquid in the impeller has a large function outflow impeller, helical liquid which is collected in the pump housing, and at the back of the diffusion tube into pressure energy to kinetic energy.
Compared with other types of pumps, centrifugal pump has a simple structure, easy to wear, smooth operation, low noise, easy to adjust the water evenly, high efficiency, and therefore the centrifugal pump has been widely used.
However, when centrifugal pump in the working process there will be different kinds of loss: mechanical loss, hydraulic loss and volume loss.