Upward flow of fluid through a bed of particles is a naturally occurring phenomenon, for example in the movement of ground water. Industrial applications include ion exchange, extraction of soluble components from raw materials and other chemical processes.

The Armfield CEL-MKII apparatus facilitates the study of flow through fixed and fluidised particle beds. The simultaneous study of air and water systems and the phenomenon of ‘bubbling’ can be observed.

The apparatus comprises three clear acrylic columns mounted above a moulded ABS base. The base contains a water reservoir with a variable speed submersible pump that pumps water through an electronic flow meter into the base of the left-hand column. This column features an overflow pipe that returns the water back into the sump.

The two air columns are fed by variable pressure regulators, which can be used to adjust the air flow rate through the column. The air flow rate is measured using pressure sensors at discharge orifices at the top of the columns. The integral microcontroller calculates the flow rates from the pressure readings and displays these on the front panel.

Pressure drops on all three columns are measured by differential pressure sensors connected to tapping points at the top and bottom of the columns.

All process measurements are displayed simultaneously on the front panel display and are available on the USB output for data logging. The software also provides powerful graph-plotting facilities.

Experimental Content

• Determining the voidage of granular material
• Flow through fixed and fluidised beds using water as the fluidising medium
• Flow through fixed and fluidised beds using air as the fluidising medium
• To determine the pressure drop (head loss) across the beds with different particle sizes
• Verification of Carman-Kozeny’s equation
• To compare the predicted onset of fluidisation with the measured pressure drop
• To compare the onset of fluidisation between two particle sizes
• To observe the onset of fluidisation and differentiate between the characteristics of a fixed bed and fluidised bed
• To observe the onset of fluidisation and differentiate between the characteristics of a fixed bed and a fluidised bed for different particle sizes.
• To investigate the difference between different sized granular material on fluidisation characteristics, using air as the fluidising medium.
• Demonstration of liquefaction and liquefied soil phenomena (e.g. quicksand)
• To investigate the characteristics associated with water flowing vertically upwards through beds of different granular material