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FSM: Liquid Desander – History of Hydrocyclones and Desanders (B-FSM045)

Banks of hydrocyclones used in closed-circuit grinding in copper ore processing

Continuing with our discussion of cyclone technology we will now derive the hydrocyclone and desander. The purpose is to clarify the terminology of all these devices.

Hydrocyclones

The hydrocyclone is a contraction of the term “hydraulic cyclone” and signifies that the carrying fluid phase is a liquid. While the use is predominantly in aqueous systems with water as the carrying fluid, hydrocyclones can be used on any liquid. I’ve ran them on glycol, diesel, fruit juice, and picante sauce to name a few. The hydrocyclone is a subset of the cyclone unit process – it has the same features and benefits as previously discussed.

Hydrocyclone History

  • The hydrocyclone is considered a mineral processing device – and that is where it still finds predominant use and where most research is published (same goes for flotation!)
  • First patented in 1891
  • Significant developments post-WWII to replace rake and screw classifiers
  • Primary uses are closed circuit grinding and solids density classification
  • Operates with open (atmospheric) underflow and overflow – this operation allows a central (vacuum) air core
  • 1000+ journal and conference papers on mineral processing hydrocyclones
  • Key authors: Bradley, Kelsall, Svarovsky, Trawinski, Plitt, Lynch-Rao, Rietema, Fahlstrom, Arterburn, Rajamani, Miller, etc.

Graphic below shows flow patterns within a hydrocyclone (courtesy of FLSmidth Krebs).

Desanders

The term “Desander” is short for the full name of Desanding Hydrocyclone. The desander is derived from the mineral processing hydrocyclone, thus is a subset of that technology. A technical term for the desander is a “flooded-core hydrocyclone”, since the encapsulation of the underflow prevents formation of the air-core – thus the body section is fully flooded.

Desander History

  • Initially designed in 1950’s for agriculture wells to protect irrigation spray nozzles
  • Original design is one cyclone per vessel (10”-50” vessels), horizontal orientation
  • Enclosed U/F with static accumulator
  • No air-core
  • Batch solids discharge
  • Low inlet solids concentration (agricultural use was 10 ppmw solids)
  • No journal papers on flooded-core static hydrocyclones (some papers on flooded-core operation, but still pulled fluid from accumulator chamber)
  • 1st produced water unit in 1964 with Saudi Aramco
  • Multi-liner design introduced in 1980’s (packing idea taken from liquid-liquid deoiler hydrocyclones)

The photo below shows 24” desanders treating produced water at onshore oil production site.

The next article will discuss the hardware terminology of hydrocyclones and desanders.

References

  1. Svarovsky, L. 1984. Hydrocyclones. Technomic Publishing Company, Lancaster, PA..

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