Basic knowledge of slurry pump selection
Slurry pump suppliers will share this article with you.
Slurry pump is a kind of general-purpose mechanical equipment, which is widely used in petroleum, chemical industry, power metallurgy, mining, ship selection, light industry, agriculture, civil and national defense departments, and occupies an important position in the national economy. According to the statistics in 1979, the output of pumps in China reached 1.256 million units. The power consumption of pumps accounts for more than 21% of the national power consumption. Therefore, reducing the energy consumption of slurry pump is of great significance to energy saving.
In recent years, our slurry pump industry has designed and developed many high-efficiency energy-saving products, which play a positive role in reducing the energy consumption of slurry pump. But at present, in various fields of national economy, due to the unreasonable selection, many slurry pumps are in unreasonable operation, low operation efficiency and waste a lot of energy. Some slurry pumps can not be used at all due to unreasonable selection, or the use and maintenance costs increase, resulting in low economic benefits. Therefore, reasonable selection of slurry pump is also of great significance to energy saving.
The so-called reasonable selection of slurry pump is to comprehensively consider the investment and operating costs of pump units and pumping stations and other comprehensive technical and economic indicators, so as to make it conform to the principles of economy, safety and applicability. Specifically, there are the following aspects:
1. It must meet the requirements of flow rate and head, that is, the operation time point of slurry pump (the intersection of device characteristic curve and pump performance curve) should always be kept in the high efficiency range, so as to save power and not easily damage the parts.
2. The slurry pump selected should not only be small in volume, light in weight, cheap in cost, but also have good characteristics and high efficiency.
3. It has good anti cavitation performance, which can not only reduce the excavation depth of slurry pump room, but also prevent the pump from cavitation, stable operation and long service life.
4. The construction of pumping station according to the selected pump has the advantages of less project investment and low operation cost.
1、 List the basic data:
1. Characteristics of medium: medium name, specific gravity, viscosity, corrosiveness, toxicity, etc.
2. The diameter and content of the particles in the medium.
3. Medium temperature: (℃)
4. Required flow
The leakage in the pipeline system can be ignored in the process of general industrial slurry pump, but the influence of process change on the flow must be considered. If the agricultural slurry pump uses open channel water delivery, the leakage and evaporation must also be considered.
5. Pressure: suction tank pressure, drainage tank pressure, pressure drop in piping system (head loss).
6. Pipe system data (pipe diameter, length, type and number of pipe accessories, geometric elevation from suction tank to pressure tank). If necessary, the device characteristic curve should also be drawn.
In the design and layout of pipelines, the following matters should be paid attention to:
A. Reasonable selection of pipe diameter, large pipe diameter, under the same flow rate, low liquid flow velocity, small resistance loss, but high price, small pipe diameter, will lead to a sharp increase in resistance loss, increase the head of the selected pump, increase the power with, increase the cost and operating costs. Therefore, it should be considered comprehensively from the perspective of technology and economy.
B. The maximum pressure that the discharge pipe and its pipe joint can bear should be considered.
C. The pipeline should be arranged as straight as possible to minimize the accessories in the pipeline and the length of the pipeline. When it is necessary to turn, the bending radius of the elbow should be 3 ~ 5 times of the diameter of the pipeline, and the angle should be greater than 90 ℃.
D. The discharge side of slurry pump must be equipped with valve (ball valve or stop valve, etc.) and check valve. The valve is used to adjust the working point of the pump. The check valve can prevent the pump from reversing when the liquid flows back, and prevent the pump from being hit by water hammer. (when the liquid flows backward, a huge reverse pressure will be generated and the pump will be damaged)
2、 Determination of flow head
1. Determination of flow rate
a. If the minimum, normal and maximum flow rates have been given in the production process, the maximum flow rate should be considered.
b. If only normal flow is given in the production process, a certain margin should be considered.
For large flow and low head slurry pump with NS > 100, the flow margin should be 5%; for small flow and high lift pump with NS < 50, the flow margin should be 10%; for 50 ≤ ns ≤ 100, the flow margin should also be 5%; for slurry pump with poor quality and poor operation conditions, the flow margin should be 10%.
c. If the basic data only gives weight flow, it should be converted into volume flow.
Slurry pump is the power source of the whole process system. It is very important for industrial and mining units to choose a slurry pump which is suitable for their own working conditions, high efficiency and energy saving.
3 Calculation formula of shaft power of slurry pump
Q flow calculation unit: m3 / h
H head calculation unit: M
A slag slurry density: kg / m3
G acceleration of gravity: 9.8m/s
N-axis power: kw
The motor power should also consider the transmission efficiency and safety factor. Generally, the direct connection is 1, the belt is 0.96, and the safety factor is 1.2.
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