Pump is a kind of universal mechanical equipment widely used in petroleum, chemical industry, power metallurgy, mining, shipbuilding, light industry, agriculture, civil and national defense and other departments, occupies an important position in the national economy. According to 79 statistics, China's pump production reached 1.256 million units. The electricity consumption of the pump accounts for more than 21% of the national electricity consumption. Therefore, to greatly reduce the pump energy consumption, the use of energy conservation is of great significance.
At present, in all fields of the national economy, due to unreasonable selection, many pumps are in an unreasonable operating condition, and their operation efficiency is low, thus wasting a lot of energy. Some pumps because the selection is not reasonable, can not be used, or the use of maintenance costs increase, low economic benefits. Thus it can be seen that the rational selection of pumps is equally important for energy conservation.
The so-called rational selection of pumps, is to comprehensively consider the pump unit and pumping station investment and operating costs and other comprehensive technical and economic indicators, to make it in line with economic, security and applicable principles. Specifically, there are the following aspects:
1. Flow and lift requirements must be met, ie the point at which the pump is operating (the point of intersection of the device characteristic curve with the pump performance curve) is often maintained in a high-efficiency range, saving both motivation and damage to the machine.
2. The selected pump should not only small size, light weight, low cost, but also have good characteristics and high efficiency.
3. Has a good anti-cavitation performance, so that both to reduce the pump platform construction strength, without pump cavitation, smooth operation, long life.
4. According to the selected pumping pump station, less investment, low operating costs.
Selection step a, list the basic data:
1, the characteristics of the media: media name, specific gravity, viscosity, corrosive, toxic and so on.
2, the medium contained in the solid particle diameter, content how much.
3, medium temperature: (℃)
4, the required flow General industrial pumps in the process can be ignored in the pipeline leakage, but must consider the impact of process changes on the flow. Agricultural pumps if the use of open channel water, but also must consider the leakage and evaporation.
5, pressure: suction tank pressure, drainage tank pressure, pressure drop in the piping system (head loss).
6, the piping system data (diameter, length, type and number of pipe fittings, water tank to the pressure tank geometric elevation, etc.).
The device characteristics should also be made if necessary.
In the design and layout of the pipeline, we should note the following:
A, a reasonable choice of pipe diameter, pipe diameter, the same flow, the flow velocity is small, the resistance loss is small, but the high price, the pipe diameter is small, will lead to a sharp increase in resistance loss, so that the selected pump lift, with With increased power, cost and operating costs have increased. Therefore, it should be considered technically and economically.
B, discharge pipe and its fittings should consider the maximum pressure that can bear.
C, pipe layout should be arranged as straight pipe, pipe fittings to minimize and minimize the length of the pipeline, you must turn when bending the elbow bend radius should be 3 to 5 times the pipe diameter, the angle is greater than 90 ℃.
D, the discharge side of the pump must be installed valves (ball valve or globe valve, etc.) and check valve. The valve is used to adjust the operating conditions of the pump. The check valve prevents the pump from reversing when the fluid is flowing backwards and prevents the pump from hitting the water hammer. (When the liquid back flow, will produce a huge reverse pressure to pump damage)
Determine the flow head
Flow Determination a, if the production process has been given the smallest, normal, maximum flow, should be considered the maximum flow.
b, if the production process is only given normal flow, should consider leaving a certain margin.
For ns> 100 high-flow low-lift pump, the flow margin taken 5%, for ns <50 low-flow high-lift pump, the flow margin of 10%, 50≤ns ≤ 100 pump, flow margin also take 5 %, For poor quality and poor operating conditions of the pump, flow margin should be taken 10%.
c, if the basic data only to the weight flow, should be converted into volume flow.
Although most pumps are always based on different environments, but the customer life expectancy and efficiency of the product is growing, engineers at each manufacturer are improving the existing technology to improve, for the customer's project and project to provide the most Good solution
This article Keywords: pump