Hydrocyclone Demonstration Test

A small-scale hydrocyclone was set up in a test rig and a trial was performed to determine its potential for removing fine solids from vegetable washwater. The term ‘hydrocyclone’ refers to a cone-like structure where waste is separated out of wastewater. They can be run singularly or in a parallel system; the piece of equipment tested employed several small hydrocyclones running in parallel within a larger unit.

The unit was installed on top of a barrel with an inlet, outlet, and waste outlet so that the water could cycle through the system (Figure 1). A solution of muck and water was prepared; 1 L of muck was sieved through a 200 micron screen to remove roots and coarse solids and added to 150 L of water.

Figure 1: Small scale hydrocyclone test rig

Figure 2: The path of wastewater, treated water, and waste (A) through the unit and (B) through a single hydrocyclone [Source: A: HMGA Water Project; B: TangShan Dachuan Machinery Co., Ltd., 2013]

In this system the water is cleaned using 16 hydrocyclones running in parallel (Figure 2). The coarse solids are collected in the lower hopper and are removed through the outlet. Within the hydrocyclone, the wastewater is pumped in through a tangential opening at the top (Figure 3) which causes the water to rotate (CSI, 2009; TangShan Dachuan Machinery Co., Ltd., 2013). The swirling water creates a centrifugal force which where the heavy objects move to the outside and the lighter objects move to the centre (Figure 2B) (CSI, 2009). The solids pushed to the outside will continue to spiral downwards and exit to a waste collection tank (Figure 4). The lighter solids and liquid spin upwards and exits through a short pipe; this pipe extends below the inlet to ensure the entering wastewater doesn’t exit immediately (TangShan Dachuan Machinery Co., Ltd., 2013).

Figure 3: Openings to the top of 16 hydrocyclones

Figure 4: Collected waste

The pressure at which the wastewater is pumped through the system is important (TangShan Dachuan Machinery Co., Ltd., 2013). If the pressure is too high, there isn’t enough time to for the waste to separate from the liquid and fall out. If the pressure is too low, the speed of the swirling water is insufficient to separate the waste.

The results of this test will be shared in upcoming article.

References

• CSI. (2009). FAQ. In Hydrocyclone. Retrieved March 26, 2015, from http://www.hydrocyclone.com/faq.htm
  
• TangShan Dachuan Machinery Co., Ltd. (2013). Working Principle of Hydrocyclones. Retrieved March 6, 2015, from http://shaleshakerdc.com/working-principle-of-hydrocyclones/