A desilter uses smaller hydrocyclones usually 5” or smaller. The smaller cones enable desilters to make the finest particle size separation of any full flow solids control equipment. Removing particles of 15 microns and larger. Multiple cones are normally used in this application to obtain the required GPM you need for your solids control system.
When installing a desilter, follow these general recommendations:
1. Size the desilter to process 100-125% of the total mud circulation rate.
2. Take the desilter suction from the compartment receiving fluid processed by the desander.
3. Keep all lines as short & straight as possible.
4. Do not use the same centrifugal pump to feed both the desander & desilter. If both pieces of equipment are to be operated at the same time, they should be installed in series and each should have its own pump.
5. Direct the overflow line downward into the next downstream compartment at an angle of approximately 45%.
6. Keep the end of the discharge line above the surface of the mud to avoid creating a vacuum in the line.
7. Install a low equalizer line to permit backflow in to the desander section.
8. Install a guard screen over the suction with ½” slots to prevent large trash from entering the unit and plugging the cones.
Operating a desander ahead of the desilter takes a big load off the desilter and improves its efficiency.
Operating desilters at peak efficiency is much the same as operating a desander. Here are a few fundamental principles to keep in mind.
1. Operate the desilter at the recommend pressure 32 to 40 PSI.
2. As solids increase, the cones bottom can be opened slightly to help increase solids removal.
3. Check cones regularly for bottom plugging or flooding, since a plugged cone allows solids to return to the active mud system.
4. If a cone bottom becomes plugged, unplug it with a welding rod or nail. If a cone is flooding it may need to be adjusted or the feed may be partially blocked off. It should also be inspected to make sure the cone is not worn out.
5. Run the desander continuously let fluid overflow back and process over & over.
Maintenance. A desilters smaller cyclones are more likely than a desander cones to become plugged with oversized solids, so it is important to inspect them often for wear & plugging. This may generally be done between bores, unless a failure occurs. The feed manifold needs to be flushed & checked for debris between bores.