Centrifugal pump is the equipment to transfer drilling fluids in the well drilling mud system.
Summary of centrifugal pumps
Such pumps installation way is usually horizontal type. There is coupling between pump and motor. We need to fix or assemble the pump and motor on a common base. The base, sometimes it’s just a frame, while sometimes it’s a skid for convenient handling or transportation.
Pumps used in drilling mud solids control including sand pump, slurry pump or screw pump, mixing pump, shear pump and so on. Here we are talking about centrifugal pump-sand pumps, mixing pump, and shearing pump. We use sand pumps as feeding pump for hydrocyclones both desander cone and desilter cone. About mixing pump, we configure centrifugal pump, Venturi hopper, necessary pipelines, fittings, valves, etc. The Shearing pump working principle is the same as the common sand pump, the difference is the impeller. There is a special design on the impeller to help shear polymer mud material. By the way, sometimes we combine the shearing pump and Venturi hopper instead of the separated mixing pump and shearing pump. This will provide a better effect on the material completely mixed.
Centrifugal pump
Different design on pumps for operation in different condition
As we talked about earlier. There are so many different uses so we may adjust configuration or proposal on pumps. For example, the APSB6X5 pump with motor 75HP in 380V/50Hz electrical system holding a different impeller with same pump same motor in 460V/69Hz. Because the impeller size and speed will impact the loading effect then lead motor current variation. If it’s overloading motor will stop at once to protect the motor and pump.
Referred to experience until now, almost centrifugal pumps in oil drilling fluids solids control system are horizontal installation type. While, for some mud recycling system or slurry separation and desanding plant, the pumps may install as overhead to save space in the horizontal direction. And for more special requirement we may fit diesel engine to drive pumps.
Factors affect pump performance
- Pump itself design and casting quality
- Pump seal is capable or not. Is it durable and in good condition?
- Impeller size is proper or not
- Motor power is sufficient or not
- Drilling mud property. Including density/gravity/viscosity and so on
- Pipelines are properly set
- Legal operation and maintenance on pumps
How to select pumps?
We need to confirm the flow rate firstly. Such as 528GPM, 1000GPM, or 1200GPM, etc. How to confirm the flow rate? Please inquire suppliers or consult professional engineers. They will suggest suitable pumps according to certain working conditions. Including mud property, use, lift need, etc.
If we wish make sure pump performance is sufficient for operation. Please check the pump working curve. There is information on flow rate, lift or head, and the power we need. If under a certain working condition with a ration, impeller size, lift, flow rate and power are related to each other. That means, with one ratio any factor changes may lead to other performance differences. For example, APSB8X6 pump when the power is the same 75kW and loading lower than the limit, a larger impeller will transfer more fluids than a smaller impeller. Another situation: APSB8X6 pump with same impeller and the same power, when lift 30m flow rate is different with flow rate when pump lift is 45m.
Furthermore, pump sizing or selection should consider the efficiency and actual working condition thoroughly. As different energy consumption provides different efficiency.
The maintenance of centrifugal pumps
We need to pay attention to parts including but not limited to couplings, seals, bearings, shaft, impeller, and so on. Also, we need to consider the proper and legal operation. Such as correct pipelines configuration, timely cleaning in the pump housing and check the drainage port on the pump housing.
When we maintain pumps, we need to uninstall the pump:
1.Uninstall pump shaft end coupler
2.Screw out the packing stress nut and move the packing sleeve away
3.Screw out the pump case nut get the pump case
4.Brake the shaft at shaft end uninstall the impeller
5.Screw out the mechanical seal case tension bolt
6.Get mechanical seal case away from bearing base
7.Get out the packing from the mechanical seal case
8.Uninstall the anti-abrasive shaft sleeve. If don’t replace mechanical seal pay more attention to moving-ring to avoid any damage
9.Get the retaining ring away
10.Screw out the internal bearing cap bolts
11.Screw out the axial adjusting sleeve tension bolts
12.Get the pump shaft assembly out of the bearing base
13.Get out the external bearing cap
14.Move away from the tension bolts and brake gasket
15.Uninstall bearing and shaft adjusting sleeve from the shaft
16.Get the internal bearing off the shaft
Maintain or repair on centrifugal pumps
Then we check all components to confirm if they are all in good conditions or requesting replacement or repair:
1.All parts before installed must be cleaned well, especially the position ring, O ring notch, screw, gasket surface, bearing and bearing lubrication area
2.When the impeller is serious rusty (especially the back side of impeller) or serious abrasion we must replace the impeller
3.After inspecting the radial jump to confirm if the pump shaft is curved. If the radial jump height is over 0.05mm we have to change the pump shaft. There should be no nick and notch on the bearing or oil seal. All screws on the pump shaft should be in good condition, otherwise, we need to replace the pump shaft
4.If there is an obvious nick or serious abrasion on the anti-abrasive shaft sleeve we need to change the anti-abrasive shaft sleeve
5.If there is serious abrasion on the bearing we need to replace the new bearing. The new bearing size and model must be completely the same as the original one and don't open the package before the operation
6.Mechanical seal moving ring and static ring if seriously abraded we need to change the seal assembly
7.All O rings and seals have to be changed if uninstalled. The gasket can be used as before if no damage
We know you may have questions on other issues of the centrifugal pump. Kindly leave messages below or contact us freely via emails or calls. You will find Aipu Solids Control is the ideal partner to give you solutions.
