Expanded Bed Headloss Experiment

Purpose

The purpose of this experiment is test the validity of the Okun and Schulz's headloss equation for fluidized bed and to discover whether or not, once fluidized, the headloss through an expanded granular bed is constant.

Concept of Experiment

For this experiment, we again simulate a granular bed with a test tube filled with sand. The sand filter has a depth of 5 cm and a diameter of 3 cm. We attached a pressure transmitter to the bottom and top of the test tube in order to measure the headloss that occurs in the test tube. The test tube has a strainer on the bottom and top to keep the sand from escaping which we believe would introduce a significant headloss. We first measured the headloss that occurs within the test tube without the sand. We then introuced a range of varying flow through the test tube ranging from 0 mL/min to 380 mL/min and measured the headloss that occurs as a result. We then subtract the empty test tube headloss from the headloss of the sand-filled test tube to determine the headloss that occurs through the expanded bed.

Figure 1: Fluidization Velocity Experiment-Single Media Diagram

Results and Discussion

Figure 2: Calculated Fluidization Velocity vs Actual Fluidization Velocity

The above chart shows us that the headloss through an expanded bed is constant once fluidization is achieved and, for a 5 cm filter bed, it ranges around 0.7 cm. According to Okun and Schulz's equation, a 5 cm filter bed with porosity of 0.4 and specific gravity of 1.92 should have a headloss of 2.76cm.