Slurry pump service life has the relationship with cost of production and production maintenance convenience. Selection unreasonable, may shorten the life of the slurry pump or adverse impact on production. So, bellow we will talk how to select suitable slurry pump to extend the service life and achieve maximum economic benefits.
From design side, we analysis the three main factors affecting the service life of slurry pump:
1 Slurry: the slower flow rate the slower pump wear. Cavitation and slurry with air will also reduce the service life of the pump.
2 Slurry properties: the concentration, solids particle size, shape, hardness, etc.. Which will directly lead to slurry pump wetted parts wear.
3 Quality of the slurry pump: wear-resistant properties of wetted parts and other parts quality.
Now we will do some analysis on how to extend the life of slurry pump, including slurry pump characteristics selection of working conditions, reasonable layout slurry pumps, selection of high quality slurry pump, etc.
Lower the slurry pump flow
The pump parts wear is caused by the impact and friction of slurry in the pump body. Obviously, the same medium and flow, lower flow rate, the wear speed will lower down, then longer pump life. Since the flow rate lower the slurry speed will lower too, we should select lower the flow for the pump to extend the slurry pump life. But can not lower too much, otherwise the pump efficiency will be lower too much.
If choose the high efficient district operating point flow, although the efficiency is higher, but analysis of the pump characteristic curves we can know that, the efficient district operating flow point will result in too high slurry flow rate, which will reduce the service life of the pump. The flow rate of the pump can only be selected as close as possible to the highest efficient point, just to try to get a higher efficiency. Due to the higher cost of slurry pump and power consumption cost is relatively low, after the technical and economic comparison, select the lower flow operating point will be the lowest cost and longest service life for the slurry pump.
When the pump efficiency at different flow relatively close, i.e. the pump characteristic curve is relatively gentle, the pump flow should be as small as it can and not lower than the critical settling velocity of the slurry. Also can use a larger pump and larger power motors to reduce the relative speed of medium with slurry pump parts, to make the lowest cost and longest life of slurry pump.
WARMAN slurry pump clean water characteristic curve table indicate: strong abrasive slurry pump outlet flow rate generally can not be greater than 8m / s, that is to limit the slurry flow rate, reduce wear and improve pump at the lowest cost and life.
Lower rotational speed of slurry pump
The relative speed of the slurry pump impeller and medium will be lower if the rotational speed of slurry pump lower. That is the relative speed of the ore particles is lower, so the wear of the impeller is also slower. And, when different slurry pumps to achieve the same flow rate, if the impeller diameter is large, the rotational speed will be lower. Larger impeller will wear slowly with large diameter and reducing unit area of particles, extend the pump life and maintance cost.
With lower speed, the slurry pump impeller will be large size, the pump cavity is also larger, and increase the flow rate of the pump, Therefore, in the case of the flow rate constant, the speed of the slurry within the pump should be greatly lower than the slurry pump with high rotational speed and small diameter of impeller, thereby extending the life of the pump. So, we should select lower speed slurry pump with large impeller diameter.
Normally, the higher speed pump is smaller and cheaper for the same flow and head working condition. There is the problem of technical and economic comparison, so the speed of the pump should be a proper value. The correct selection should be low speed pumps cost savings of extending the life greater than the high-speed pump wear out cost, and not as Slurry Pump Selection Handbook stated choice the maximum speed 3/4. The actually choice is, with same motor power, select the minimum speed, and not increase the power, otherwise the cost and power consumption will increase.
Selection the suitable slurry pump
For the different slurry characteristics, the centrifugal slurry pump should be designed into many different types. Light abrasive slurry should use a light abrasive slurry pump, in order to reduce costs, extend the life of the pump; heavy abrasive slurry should use heavy abrasive slurry pump. Due to the different characteristics, there are different optimal corresponding wear-resistant material, the design should be based on a different slurry characteristics in accordance with the information provided by the manufacturer to select a different wear-resistant material, to obtain a maximum service life at the lowest cost.
Reduce the speed of the pump and flow will help to improve the service life of the pump. So if high head slurry pump is used for conveying light abrasive slurry to transport heavy abrasive slurry, sometimes can longer service life and cost can be minimized. This is due to the high head slurry pump’ head is higher at low speed with more balanced efficiency, if flow is less, due to the very low speed, will make the life of the pump at the lowest cost and longer service life than heavy abrasive slurry pump.
In the selection of slurry pump, it should accurately calculate the pump head, or the pump head is too high will lead to excessive flow of the pump, resulting in vacuum phenomenon, air will be entrained into the pump and damage the pump, at the same time, the flow increased will also make the pump slurry flow rate too high, reducing the slurry pump life. In addition, the in slurry pump selection, select appropriate slurry pump manufacturers to ensure the high quality of the slurry pump is also very important.
NPSH of the slurry pump should be considered in the arrangement and minimizing the loss of suction conduit. For example bottom flow pipe under the ground in coal preparation plant enrichment workshops, but slurry pumps on the ground, that will require slurry pump higher cavitation margin. Therefore, the selection of high slurry pump cavitation margin, and to take reasonable piping, can also extend the slurry pump service life, resulting in huge economic efficiency