Desander use centrifugal force and gravity separate and eliminate solid phase particles. After fluid enter into desander barrel and impacting to the baffle ring, fluid is refracted to each direction, depending on the centrifugal force and gravity, solid phase particles sediment to the bottom of filter screen. The fluid is filtered through the hohlraum between filter screen and desander barrel is discharged. Desander use the reinforce filter screen of different stages filtrate solid phase particles. The filter screen is made of different levels filter screen barrel and reinforce outer sphere to composit formation. The filter screen is put in the pressureproof working barrel can provide more reliable structure support.
Ability of desander processing drilling fluid is decided to the size of desander barrel and the processing fluid’s viscosity. If the bottom mouth of desander is processed appropriate, all fluid will flow from overflow when transport liquid for hydrocyclone, but when the liquid contain the solid phase input the particles will be discharged from the bottom flow, the size of bottom mouth is called the balanced point of the hydrocyclone.
If the diameter of the desander bottom flow is too smaller than balanced diameter, the area between of balanced point and bottom flow mouth will form a stem region, the steam region is the wall of balanced point and bottom mouth border is dry. When fine particles lose their water film and want to through the stem region is easy to be adhered on and blocking is called dry bottom. If the diameter of bottom mouth is bigger than the balanced point diameter have a part of mud will flow from bottom flow, this kind of unreasonable adjustment is called wet bottom.
Advantages of desander are the structure is simple, the cost is lower, throughput is big. The shortcomings are the solid can’t be efficiency separate into obvious two kinds of size ranges by desander.