FSM: Liquid Desander – Sizing and Selection: Application Steps (B-FSM054)

We now start the discussion on sizing and selection of a desander for separation duty. This takes all the theory we have previously detailed and adds calculation steps to properly size a desander for your application.

There are quite a few good sizing routines available. I recommend starting with Plitt (see references). Please keep in mind that he is sizing a hydrocyclone, not a desander, so the appropriate modifications must be made to account for no flow split. Svarovsky also publishes quite a few sizing equations, which are valid for various applications and geometries.

The routine I have outlined below was published in 2001 (see Rawlins and Wang reference). It is the commercial routine I’ve used since my grad school days. In this post I am just detailing the main application steps. Subsequent posts will provide the calculation details – but I need to give an outline first.

Application Steps for Desander Selection

1. Select the size of desander (insert or liner) geometry for separation duty
• Gives appropriate separation size (D98)
• Gives required total solids recovery (%)
• Meets allowable pressure drop (ΔP)
1. Select appropriate number of operating units for flow and turndown
• Insert style: number of vessels in parallel operation
• Liner style: number of liners (design, high, and low flow) in the vessel
1. Select appropriate mechanical design rating and materials of construction
• Vessel diameter determines insert diameter or quantity of liners
• Appropriate vessel mechanical design rating (i.e. ASME) suitable for design pressure and temperature
• Vessel materials of construction for corrosion control
• Insert/liner materials of construction for erosion control

The next article discusses desander geometry for separation duty.

References

1. Plitt, L.R., “A mathematical model of the hydrocyclone classifier”, CIM Bulletin, December, 1976, pp. 115-123.
2. Rawlins, C.H., and Wang, I. I., “Design and Installation of a Sand Separation and Handling System for a Gulf of Mexico Oil Production Facility,” SPE Production and Facilities, paper 72999, Vol. 16, No. 3, 2001, pp. 134-140.
3. Svarovsky, L., “Hydrocyclones”, Technomics Publishing Co. Inc., Lancaster, PA, 1984.