Working principle of the hydrocyclones

As two indispensable equipments in the solid control system of oil & gas drilling, desander & desilter is responsible for separating the small solids in the drilling fluids which has been treated by the shale shaker & vacuum degasser. The desander takes care of the solid with diameter 45~74μm, and 15~44μm for desilter.

Normally desander is mounted on the top of the first mud tank together with shale shakers & vacuum degassers, while desilters are mounted together with centrifuges. Sometimes to save the top area of the mud tank, desander & desilter are combined together to work as high efficient mud cleaner.

Desander & desilter is consist of hydrocyclones, high pressure flow pipes & a small shale shaer at the bottom. For desander & desilter, only one vibration motor is used to drive the screen basket. while for high efficient it would need two motors. There would equiped two 10″ or 12″ diameter iron hydrocyclones for desander just as the solids need to be separated is relatively big, and include some sands in the mud. While for desilter, it would equiped 6 to 12 pcs 4″ diameter hydrocyclones which are made of wear resist plastic.

Working principle of the hydrocyclones

For the work principle of hydrocyclones, it works like this. First the drilling fluids are sucked up to 0.25Mpa ~ 0.4Mpa by sand pump, and enter into the cones through the side inlet which is normally only 2-1/2″ diameter. The fluids then flow spirally inside of the cone. Effected by the centrifugal force, the heavy solids in the fluids would be throwed towards the inner wall of the cones, go down to the bottem, and discharge through the sand discharge port, while the light fluids would go up and discharge through the upper oulet. The diameter of the bottom discharge port is adjustable, and with a cover of hydrocyclone.

As an quick-wear part of desander & desilter, the lifetime of hydrocyclones is not so long as other parts. So it is neccessary to check their working condition, and replace them with new ones. As a whole set of the hydrocyclone, clamps & flang are also replaced together with the hydrocyclones.