The polyurethane hydrocyclone is a simple and easy to maintain mechanical separation device. It’s crucial part of desander, desilter and mud cleaner. The split type is obtained by converting the feed energy of the power input into the centrifugal force inside the cone.
Centrifugal forces act on the drilling fluid to quickly separate the cuttings from other solid phases, which follow Stokes’ law. In some formations, because the drill cuttings produced are too insubstantial, the drilling fluid shaker cannot screen out this part of the cuttings and must rely on a hydrocyclone to remove most of these particles.
At this point, the drilling fluid shaker prevents excessively large particles from entering the polyurethane hydrocyclone causing blockage, thereby protecting the polyurethane hydrocyclone.
The optimum separation of the polyurethane hydrocyclone is to obtain maximum solids discharge of the cuttings with minimal liquid loss. Larger particles are discharged through the underflow port, and small, light particles are discharged through the overflow port. The greatest influence on the performance of the polyurethane hydrocyclone is the diameter of the cone, the taper angle, the diameter of the bottom orifice, the feed pressure, and the plastic viscosity of the feed.
Compared with drilling fluid vibrating screens and centrifuges, polyurethane hydrocyclone emissions are wet emissions, and the underflow density alone does not show the working condition of the polyurethane hydrocyclone because the fine particles contain more liquid and the final drilling The liquid density is lower than that of the coarse particles.
As the solid phase composition gradually increases, the polyurethane hydrocyclone separation efficiency gradually decreases, but the separable particle size increases.
Advantages of the polyurethane hydrocyclone
The polyurethane hydrocyclone has the following advantages compared to other solid-controlled devices:
- Compact device, simple structure, low price and no moving parts.
- The amount of processing is large. The scope of separation is also large.
- Adjustment and operation are simple and easy to maintain.
- Strong separation ability, in some cases, can get a finer overflow and higher separation efficiency. It’s separation efficiency is generally 60%, and in some cases it can be as high as 80% to 90%.
Disadvantage of the polyurethane hydrocyclone
The polyurethane hydrocyclone has the following disadvantages reported to other solid-state devices.
- Power consumption is large. In some construction projects, the desilter is equipped with a power of 55-75Kw.
- When the viscosity of the slurry, the solid phase concentration and the particle size change, the separation particle size and separation effect of the polyurethane hydrocyclone change accordingly.
- The working condition of the sand pump has a great impact on the polyurethane hydrocyclone.
- Cannot carry out ultra-fine separation, can not handle the flocculation material.
- The wear is fast, especially when the particle size is large, the hardness of the cuttings and the concentration of the slurry are large, the barrel of the cylinder, the lower part of the cone and the sanding mouth are easy to damage.
Generally, the service life of the polyurethane hydrocyclone is lower than 2000 hours. In recent years, many units have been developing more wear-resistant materials to move forward.
In general, when the solid phase particles are greater than 10 μm and the shape is spherical, the hydrocyclone is more efficient. If granules of solid phase are flat, and the movement is often random, the hydrocyclone is less efficient.
If the D50 separation point is increased to 75μm, 25% of 100μm grade particles are left in the overflow and only 25% of the 55μm grade particles are discharged.