ANC CONTROL
Experiment 1: Minimum amount of lime input in two reactors
INTRODUCTION
In the first experiment of Spring 2010 team, the goal is to evaluate the lime feeder's performance in respect to its effluent pH if the lime input was based on theoretical value, which was the mass of lime would be consumed in 12 hours as a function of calcium hydroxide solubility constant (equation 1.1), and different flow rate. As can be seen in (equation 1.2), the theoretical lime requirement was simply based on mass balance, and didn't take into account the insufficient use of lime that would occur by the influential of other factors.
PROCEDURE
The team used basically the same procedure as described on materials and methods, but it is important to address the change of the design in which the lime was fed through the vertical tube.
As a comparison with the last experiment carried out by Fall 2009 team(Experiment 3, Trial 4), the Spring 2010 team used the same flow rate, which was 40mL/min in both reactors, and a lime mass of 8gm based on (figure 1.1). However, one thing has to be noticed is that the team feed powdered lime directly into the vertical tube without dissolving the lime in distilled water.
Unknown macro: {latex}
\large
$$
[〖Ca〗^(2+) ]× [〖OH〗^- ]=K_sp
$$
Unknown macro: {latex}
\large
$$
Lime(Q)=(K_sp/〖[〖OH〗^-]〗^2 )×MW×Q×12hrs
$$
RESULT and CONCLUSION
From the experiment data shown in figure 1.2: the A1 reactor could barely go above 12 and the A2 reactor maintained a pH over 12 for just over 2 hours. Compared to Trial 4, which the previous team used fine hydrated lime instead of powdered form in this run, the comparison parameter--lime input, could be a very important factor and further discussion is shown in (kinetic hypothesis). The experiment also showed that the A2 reactor could create a much better suspension than A1, which means its new geometry reaches our expectation, but the 40mL/min flow rate is far from the ideal velocity to get the best suspension. By kept changing the up-flow and observing the suspension in A2 reactor, the team assumed the optimum flow rate was 120mL/min, which around this level best suspension could be acquired in A2 reactor.
