Submersible sewage pump is a pump and motor Siamese, and at the same time into the work under the liquid pump products, compared with general horizontal or vertical sewage pump, submersible sewage pump has obvious advantages of the following aspects:
1. Compact structure, cover an area of an area small. Diving sewage pump due to dive under the working fluid, and therefore can be directly installed in the sewage pool, to build a special pump used to install pumps and machines, can save a lot of land and infrastructure costs.
2. Easy installation and maintenance. Small diving sewage pump free installation, large diving sewage pump is generally equipped with automatic coupling device can be installed automatically, installation and maintenance is very convenient.
3. Continuous operation time is long. Diving sewage pump due to the pump and motor coaxial, shaft short, rotating parts weight is light, so carry the load on the bearing (radial) is relatively small, life is much longer than the average pump.
4. There is no cavitation damage and irrigation water diversion and other issues. Especially after a little to the operating personnel has brought great convenience.
5. Vibration noise is small, the motor temperature rise is low, no pollution to the environment.
It is because of the above advantages, diving sewage pump has more and more get people's attention, the scope of use is becoming more and more widely, from simply used to transport water to the present can transport all kinds of sewage and industrial waste water, construction drainage, liquid feed and so on.
In the municipal engineering, industrial, hotel, hospital, building, water conservancy construction and plays an important role in all walks of life.
But any every coin has two sides, the most critical problem for diving sewage pump is a * sexual problems, because the use of submersible sewage pump occasions is under liquid; Transmission medium are some of the mixed liquid containing solid material; Pump and motor * close; Pump for vertical layout, with the impeller rotating components weight under water stress direction. These problems can make diving sewage pump in a sealed, motor bearing capacity, bearing arrangement and selection requirements is higher than general sewage pump.
In order to improve the life of diving sewage pump, and now most of the foreign and domestic manufacturers have to find a way to in the protection system of the pump, namely in the pump leakage, overload and overtemperature of failure can automatically alarm, and automatically stop for repair. We believe, however, set in the diving sewage pump protection system is very necessary, it can effectively protect the safe operation of electric pump.
But this is not the crux of the problem, the protection system is just after the pump failure of a remedy, is a relatively passive approach. The crux of the problem should be from the root, a thorough solution to pump in a sealed, overload and other problems, it is a more active way. We deputy hydrodynamic impeller seal technology and design technique is applied to the overloading of the pump submersible sewage pump to improve the pump seal can * sex and carrying capacity, prolong the service life of the pump.
A, vice impeller fluid power applications of sealing technology
Deputy hydrodynamic impeller seal refers to the near the back of the pump impeller HouGaiBan coaxial install a open impeller in the opposite direction. When the pump work, vice impeller with pump shaft rotation, the deputy impeller together with the liquid will be rotate, rotating liquid will produce an outward centrifugal force, the centrifugal force on the one hand, standing up to the liquid flow to the mechanical seal, reduces the pressure of the mechanical seal. Solid particles on the other hand to stop the medium into mechanical seal friction pair, reduce the wear of mechanical seal grinding block, prolong its service life.
Vice impeller besides sealing effect, still can rise to reduce the effect of axial force, the submersible sewage pump axial argued that if the role of the liquid in the differential pressure force on the impeller and the rotating part of the force of gravity, the role of the two forces direction is the same, the resultant force is composed of two forces combined. As you can see, in the case of performance parameters of the same, the submersible sewage pump axial force is bigger than the general horizontal pump, and balance the difficulty is harder than the vertical pump. So in the submersible sewage pump, bearing is easy to damage the reason also has a lot to do with large axial force.
And if installed vice impeller, liquid on the role of the vice impeller of differential pressure force direction is in contrast to the composition of the two forces, so that we can offset part of the axial force, also have the effect of the extend bearing life. But using vice impeller sealing system also has a drawback, that is on the vice impeller part consumes energy, usually at around 3%, but as long as reasonable design, this part can reduce the loss to the minimum.
The application of the two, the overloading of the pump design technology
In general centrifugal pump, the power is always along with the increase with the increase of the flow, that is to say, the power curve is a rising curve with the increase of flow rate, the use of the pump will lead to a problem: when the pump design point operation, in general, the power is less than the motor rated power of the pump, the use of the pump is safe; But when the pump will reduce the flow rate will increase (can be seen from the pump performance curve), the power also will increase.
When the flow more than design point flow and get to a certain value, the input power of pump may exceed the motor rated power caused by the motor overload and burned. Motor overload runtime or protection system action make the pump stop running; Either make the motor burned protection system failure.
Pump lift used lower than design point head, also often encountered in practice, a situation is when the pump selection, pump lift selected too high, and the actual pump is reduced when using head use; Another case is that, in the use of pump point is not so good, in other words, the pump flow need to be adjusted frequently; There is a kind of circumstance is pump need often change the site to use. This three of the following message may make pump overload and affect the use of the pump can be *. You can say that, for there is no total head characteristics of the pump (including diving sewage pump), the scope of its use is limited by a largely.
So-called total head features (also known as no overload characteristics) refers to the power curve rise with the increase of flow speed is very slow, is more ideal when the flow increased to a certain value, the power not only won't rise, it will declined, that is to say, the curve of the power curve is a hump, if so, we just choose the motor rated power point slightly over the hump of power value, so at zero flow to the largest flow of the whole range, no matter you run on that one point, the power will be no more than a motor power of the pump and make the pump overload, to have the performance of the pump, the selection and use, will be very convenient. Other motor power do not have to be too large, can save considerable cost of equipment.
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