ANC CONTROL

EXPERIMENT 1. GLASS COLUMN AS FLUIDIZED LIME FEEDER

INTRODUCTION

The first experimental task was to check the feasibility of a fluidized lime bed suspended in a tall column. This is the simplest model that can be used as a lime feeder. The aim was to find the optimum upflow velocity that would mix the lime uniformly and keep it suspended without causing a great amount of lime to go out with the effluent. Upflow velocity can be calculated by dividing the flow rate by the cross sectional area of the column. Since the area is constant, upflow velocity is directly proportional to the flow rate. The equation of up flow velocity is shown below.

Vup flow: Velocity of the inlet flow.
As top: Superficial area at the top of the tube.
Qlime feeder: Flow rate employed on the experiment.

DESCRIPTION

This experiment consisted of measuring the upflow velocity with at different flow rates and different quantities of lime, while always maintaining a suspended column of lime. This was an initial experiment and hence most of the quantities were taken through approximation. (Why are you measuring the upflow velocity? I thought we were trying to ascertain good upflow velocities to set for the column with lime.)

The experimental set up can be seen in Figure 1. It consists in a vertical column that is fed by the bottom with water; the water flow rate is controlled by an automatic pump. Lime is added at the top of the column before running it. Once it is running, the effluent comes by the top; it is water hyper super saturated with lime.

Figure 1: Schematic Diagram of Experimental Set up

The Figure 2 shows the actual apparatus used for the first trial. A glass column connected with a water source regulated by a peristaltic pump.
 
Figure 2: Experimental Apparatus

RESULTS

The optimum flow rate which could keep the lime suspended without excessive lime coming out (as observed visually) was found to be about 85ml/min. Which corresponds to an up flow velocity of 22.7 cm/min. (Put in mm/s)

The results are summarized in Table 1.

The details of the exact quantities of lime and flow rates as well as the results obtained can be found on ANC-Initial Experiment Spreadsheet.