What is the difference between a submersible pump and a centrifugal pump? What are they suitable for? If the two are used together, how should they be used? To pump the water in the foundation pit, put the submersible pump in the water and the centrifugal pump on the ground?
Submersible pumps and centrifugal pumps are called different classifications; submersible pumps: according to the use and installation category; centrifugal pumps: according to the structural principle category.
The difference between submersible pump and centrifugal pump is:
1. The working principle is different: the principle of the submersible pump is similar to that of an electric fan. The centrifugal pump uses centrifugal force to throw water out. Designed according to the centrifugal force principle, the high-speed rotating impeller blades drive the liquid to rotate and throw the liquid out to achieve the purpose of transportation. There are many media that can be transported, such as oil, water, chemical raw materials, etc. The water pump shaft and the motor shaft are the same shaft, the pump and the motor are integrated into the water, and the transport medium is water.
2. Different installation positions: one can be put in the water, and the other is on the ground.
3. Different uses: centrifugal pumps can be widely used in electric power, metallurgy, coal, building materials and other industries to transport slurry containing solid particles. Such as hydraulic ash removal in thermal power plants, slurry transportation in metallurgical beneficiation plants, coal slurry and heavy medium transportation in coal washing plants, etc. Submersible pumps are mainly used for farmland irrigation and water for humans and livestock in high mountain areas. They can also be used for central air conditioning cooling, heat pump units, cold pump units, cities, factories, railways, mines, and construction sites.
2. The submersible pumps are named according to their usage. As the name suggests, they can be used in the water. Its working principle is centrifugal, so it can be regarded as a kind of centrifugal pump. Centrifugal pumps are pump types named according to their working principles, with a very wide range, including ordinary centrifugal pumps, multi-stage pumps, sewage pumps, oil pumps and other categories.
3. The structure is different: the centrifugal pump is composed of impeller, pump body, pump cover, water retaining ring, pump shaft, bearing, sealing ring, stuffing box, axial force balance device, etc. The submersible pump is composed of a control cabinet, submersible cables, pumping pipes, submersible electric pumps and submersible motors.
Centrifugal pump is suitable for industrial and urban water supply and drainage, high-rise building pressurized water supply, garden sprinkler irrigation, fire pressurization, long-distance water delivery, HVAC refrigeration cycle, bathroom warm water cycle pressurization, and various water supply equipment and boilers. It is used to transport clear water and other liquids with similar physical and chemical properties to clear water.
The advantages of centrifugal pump:
1. The flow is continuous and uniform, working smoothly and Q is easy to adjust. The applicable Q range is very large, the commonly used range is 5-20000m3/h.
2. High speed, can be directly connected with electric motor or steam turbine, simple and compact structure, size and weight are much smaller than reciprocating pump of the same flow, and low cost
3, it is not sensitive to impurities, and it is easier to manage and maintain with less wearing parts. Whether on land or on ships, the number and scope of use of centrifugal pumps exceed other types of pumps.
4. There is no self-priming ability in itself, in order to expand the scope of use, special measures are taken in the structure to manufacture various self-priming centrifugal pumps. The centrifugal pump is equipped with a suction and water diversion device.
5. The Q of the pump changes with the working head. H increases. When the Q decreases to reach the closed head, the pump runs idling without draining. It is not suitable for lubricating oil pumps, fuel pumps and other occasions where Q does not change with H.
6. The head is determined by D2 and n, which is not suitable for small Q and high H. This requires the impeller flow path to be narrow and long, which makes it difficult to manufacture and the efficiency is too low. The maximum discharge pressure produced by the centrifugal pump is limited, so there is no need to install a safety valve. Centrifugal pumps are mostly used for marine water pumps and cargo oil pumps. Centrifugal pumps with self-priming capability are used for marine pumps, ballast pumps, bilge pumps, and tanker stripping pumps.
Disadvantages of centrifugal pump:
centrifugal pump is a vane machine, the biggest advantage is high efficiency and simple structure. On the surface, it is continuous and uniform water output. In fact, it is not continuous, because the number of blades is limited, and the pressure generated by it also fluctuates in a small range. When a stable range of pressure with a certain accuracy is required, centrifugal pumps alone cannot meet the requirements.
The working characteristic curve of the centrifugal pump is a parabola, so it cannot be satisfied in some situations.
When the specific speed of the centrifugal pump is very low, that is, when the flow rate is small and the head is high, its efficiency is very low, and it is not even comparable to other types of pumps. It is reported that there is already a centrifugal pump with a specific speed of 14. Foreign countries have also reported that: single-stage centrifugal pump head can reach 300 meters. Centrifugal pump is a simple mechanical product as a mechanical product. As a centrifugal pump theory, it is imperfect, and it has not been well solved even today. It is developed in computers. Today, the so-called numerical calculations can be carried out under certain assumptions.
Submersible pump is an important equipment for deep well water lifting. When in use, the whole unit is submerged into the water to work and extract groundwater to the surface. It is used for domestic water, mine rescue, industrial cooling, farmland irrigation, seawater lifting, ship load adjustment, and can also be used for fountain landscape.
Hot water submersible pumps are used for hot spring bathing, and can also be used to extract groundwater from deep wells, and can also be used for water lifting projects such as rivers, reservoirs, and canals. It is mainly used for farmland irrigation and water for humans and livestock in high mountainous areas. It can also be used for central air conditioning cooling, heat pump units, cold pump units, cities, factories, railways, mines, and construction sites. The general flow can reach 5~650m³/h, and the head can reach 10-550 meters.
The advantages of submersible pumps:
1. The electric motor and the water pump are integrated without a long drive shaft, and the weight is light
2. Both the motor and the water pump are submerged in the water, so there is no need to build a ground pump room.
3. Since motors are generally used for water lubrication and cooling, maintenance costs are small
Disadvantages of submersible pumps:
1. There are restrictions on the structure of submersible pumps. The lift range of submersible pumps is smaller than that of chemical pumps, so the selection range is greatly affected.
2. The working part of the submersible pump is immersed in the medium, and installation and maintenance are more difficult than that of the ground pump. At the same time, the service life of the whole machine is much shorter than that of the chemical pump because of the fragile parts.
3. Cables and seals are easy to age and cause leakage.