[Company Logo Image]  

Performance Curves

 

Home Oil Droplet Data Performance Curves

 

What is a Performance Curve?

A performance curve is one effective way to measure the 'power' of an oil separator. This separator performance curve plots oil droplet size on the horizontal axis and percentage removal on the vertical axis. The curve plots the actual percentage of oil of a certain size removed. A more powerful separator will be able to remove a higher percentage of smaller oil droplets. The most accurate curves are produced using the actual oily water feed conditions. See also FAQ for more information.

 

Why are Performance Curves important?

perfor5.gif (50000 bytes)

The Spinifex Separator is extremely efficient.  The performance curves show that it has the capability to efficiently remove oil droplets from 10 mm and greater.
  •  More powerful separators separate a higher percentage of smaller oil droplets. This will result in cleaner water.
  •  Performance curves enable companies who purchase oil water separators test vendor performance claims objectively. 
  •  Many oily water equipment vendors claim to be able to achieve, say 10 mg/l oil and grease in the treated water. Without specifying the conditions and performance curves such claims can lack credibility. 

Types of Separator

Plate Pack also known as: 

  • Coalescing plate separator (CPS)

  • Coalescing plate interceptor (CPI)

  • Tilted plate separator

  • Vertical gravity separator (VGS)

Settling Tanks also known as:
  • API separators
  • Triple Interceptors
  • Above ground tanks
  • Collection pits
ex6-6.gif (16323 bytes)
Belt and rope skimmers are often used as part of an oily water treatment system however they are not included as they are not water treatment devices. These devices typically remove only some of the oil that may already be separated at the surface of water via some other means such as from a gravity vessel.  

What data is needed for a Performance Curve?

To ensure that the curves can be compared and are meaningful the minimum set of data that must be specified and produced with performance curves includes:

1. Fluid Properties:
  •  Water density
  •  Water viscosity
  •  Oil density
  •  Oil viscosity

2. Method of Operation:
  •  Feed water flow rate
  •  Inlet oil concentration
  • Data depends on type of separator

3. Separator Design Factors:
  •  Nominal plate spacing
  •  Total horizontal projected wetted plate area
  •  Operating oil depth
  •  Design retention time
  • Depends on type of separator, data shown for plate pack

Certain factors are well known to affect the ease of oil droplet separation, so generally the curve is plotted under actual clients conditions or a typical set of conditions.

In the absence of client specific data the following data and conditions are typically used to compare separators.

 

Water Temperature                             

  25°C

Oil density                                         

  850 kg/m3

Water density                                    

  1000 kg/m3

Oil/Water interfacial tension              

 < 30 dyne/cm2

Water Viscosity                                  

 1 cP

Rated Flow                                        

  1500 l/hr

Separator Condition                           

 Just prior to routine service (ie used, dirty condition)

Blue divider