Description of a Decanter Centrifuge:

A decanter centrifuge, also known as a horizontal bowl centrifuge, solid bowl centrifuge or scroll centrifuge, is a machine used to separate a solid material from a liquid(s) using a high-speed and continual rotational process. While wastewater treatment of biosolids is a primary application, the separation of one solid material from one liquid (2-phase dewatering) in a slurry is also important for a number of industries including chemical, food, oil, and mining to name a few.

How it Works

The separation of a solid and liquid(s) in a decanter centrifuge system work on the principle of gravitational forces. Whereas it takes considerable time for the gravitational separation of a muddy mixture (to fall to the bottom) and water (to rise to the top) in separation technologies based on 1xG separation such as,a static container, clarifier or lamal separator, the rapid rotation of a centrifuge greatly speeds up this gravitational principle.

In fact, the G-force generated by a decanter centrifuge can be well in excess of three-thousand times greater than gravity reducing the separation process from hours to mere seconds. Today's centrifuges are a counter-current type technology. The separation process in a 2-phase decanter centrifuge results in the denser solid particles to be compacted and settled out in the inner drum and then transported and removed via solids discharge end of the decanter. The centrate is routed to the opposite end of the centrifuge and removed via the centrate outlet. In a 3-phase centrifuge, the baffle system is built inside the centrifuge. The baffle system blocks the oil from being discharged with the water. The oil (the lighter phase fluid) is collected between the two baffles and skimmed off the top.

Decanter Centrifuge Operational Diagram

The basic operation includes the following centrifuge parts and how they function:

1. The feed material enters the centrifuge via the feed pipe inlet on one end of the centrifuge
   
   
2. Due to centrifugal force, the heavier particles are pushed through the liquid and collected on the inner wall of the bowl; the high speed rotation of the bowl separates the solids and liquid materials
   
   
3. The continuous rotation of the bowl can be accomplished by a VFD (Variable Frequency Drive)
   
   
4. The scroll conveyor (scroll) inside the bowl rotates at a slightly different speed than the bowl (differential speed)
   
   
5. The scroll conveyor continuously scrapes the solids off the inner bowl wall and moves the solids in the direction of the centrifuge conical's solids discharge area
   
   
6. The liquid (centrate) moves in the opposite direction from the solids due to Pascal's Law (or a system of combined piping) and because the solids discharge end is sealed by the solids
   
   
7. The differential speed of the centrifuge controls the solids retention time; the longer the solids are under g-force the drier the solids become in the dewatering process

Usage:

For open recirculation cooling water systems, closed recirculation cooling water systems and one-through cooling water systems.

• All organic high pH treatment chemicals

• Scale and Corrosion Inhibitors

• Oxidizing Biocides

• Non-oxidizing broad Spectrum Biocides

• De-alkalizers

• Silica Dispersants

• General Dispersants

• Bio-dispersants

• De-emulsifiers

• New cooling water System Pre-cleaning Chemicals.

• Passivating Chemicals

• Acid Inhibitors

• Close circuit scale and Corrosion Inhibitors.

• Idle cooling water system preservatives.

• All-in-One packaged chemicals/tablets

• Stabilized phosphate treatment chemicals