The hydraulic design and structural design considerations are as follows:
a. Wear and hydraulic performance problems: In order to reduce wear, the flow rate of the rotating parts and fluid should be kept low enough, and the thickness of the pump body carbide lining or elastic lubricating material should be increased to meet the actual operation needs. The radial section of the impeller is generally close to a rectangle, and the front end seal is used to reduce the axial rotation area on the vertical plane. The pump casing is generally designed to be semi-helical or annular, so that a small wear is maintained in a wide range near the highest efficiency point. the amount. When it is necessary to transport large particles of solids, the width of the built-in closed impeller is usually large, and the number of blades is also reduced to 2-3 pieces. Under the premise of improving the wear of the pump, the hydraulic performance of the pump will be reduced to different extents.
In order to make the pump have the minimum amount of wear in the different operating conditions of the highest efficiency flow, the volute structure of the slurry pump is from the spiral volute to the semi-helical volute, to the annular volute and the OB type structure. The types of impellers are RV type with a rectangular cross section, ME type with twisted blades and a rounded rectangular cross section, and the most common HE type.
Different combinations of impeller and volute have different hydraulic and wear characteristics. Generally there are:
1.HE/T combination, with good hydraulic performance, but poor wear performance;
2.ME/C combination with good hydraulic performance and wear performance;
3. A or OB type volute and impeller different combinations, can be used in more severe wear.
b. Material problem: the impeller and volute material of the slurry pump, such as rubber, neoprene, polyurethane resin and other elastic materials, generally used in the case where the impeller exit speed is lower than 23m/s, which can improve the effective steam of the pump. Erosion allowance.
c. Mechanical design (shaft, bearing, seal, pump body, etc.)
Shafts and bearings must have higher strength and stiffness as well as reliability. The trapezoidal screw-connected impeller is generally capable of withstanding heavy loads, using sliding thrust bearings under heavy loads, while ball bearings are typically used for light load conditions.
The slurry pump has no radial seal, so the deflection of the shaft is allowed to be larger than that of a conventional pump, which limits the life of the stuffing box and the mechanical seal. Therefore, a shorter shaft is generally used, and the allowable skewness is also small, which can improve the life of the stuffing box. Generally, high-pressure water should be injected into the sealed cavity to dilute the material and prolong the service life of the pump. If the material cannot be diluted, the push-type seal can be used, which is generally used in a single-stage slurry pump, but the efficiency will be 3%. reduce.
Mechanical seals generally use a partially balanced structure, in which case the fluid can be used for cooling; in some cases the pump may idling, in which case a double mechanical seal must be used. Under light load conditions, general mechanical seals are used; under heavy load conditions, special mechanical seals must be used.
Generally, the strength of the pump casing made of elastic material may be too small to withstand large pressure loads, so a pump casing should be added, which is called double-wall structure. The material is generally made of hard metal, rubber or polyurethane resin. For large pumps, bolt-tight constructions can be used due to volume and cost constraints.
d. Effect of solid particles on centrifugal pump
The flow-stage curve of the slurry pump changes more gently, and the flow resistance loss of the conveying pipe will increase slowly with the increase of the flow rate. The angle between the characteristic curve of the pipeline and the performance curve is small, so that a small change of the head will cause Significant changes in traffic.
The wear of the slurry pump is generally very serious, and the life of the part is sometimes only one month. So using the right materials is a key factor in pump design. The main causes of wear are sliding erosion and particle impact.
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Label: Several problems to pay attention to when designing slurry pump
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The present invention provides a multifunctional pull faucet, comprising: a faucet body, a drawing part is provided at the water outlet port thereof, and the drawing part is connected to a main channel, wherein at least three are provided in the faucet body A branch channel, and the three branch channels are all connected to the main channel. A multifunctional pull faucet provided by the present invention, wherein the hot water channel, the cold water channel and the water purification channel (pure water channel) are all connected to the main channel , And the main channel is connected with the drawing part on the main body of the faucet, so that the drawing part can obtain the water quality (hot water, cold water, purified water or pure water) required by different users, thereby improving the user experience, and , By integrating the hot water channel, cold water channel and pure water channel (pure water channel) into the main channel, the internal structure of the faucet is simplified, and the production cost of the faucet is reduced..
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