ANC CONTROL

Spring 2010 Research

INTRODUCTION

The Spring 2010 ANC team is continuing research with lime feeders where the Fall 2009 team left off. The original idea was to create lamellar sedimentation by placing a slanted tube on top of a vertical one and running water upwards through the reactor. With appropriate fluid velocities, one can maintain a fluidized bed of lime particles in the lower segment but prevent the vast majority of solid lime particles from leaving with the effluent (see 2009 design). This semester the team modified the reactor design in order to improve its performance and provide an easy way to feed lime while the reactor is running (see new lime feeder design).

Following the  set-up described in each experiment found below with both the new apparatus and the old one, the team is conducting a series of experiments in order to determine which mechanisms are important in producing effluent saturated with lime for long periods of time. The tests are based on hypotheses which the team has developed over the course of the semester. Following the recommendation of previous ANC teams, the Spring 2010 team has tried to isolate variables and test them separately. In all of the experiments, the team has tried to vary only one parameter at a time so that comparisons between tests are more meaningful.

Nine comparison experiments have been carried out. The results and analysis are shown on each of their respective pages. 

Experiment 1: Minimum amount of lime input in two reactors

Experiment 2: Testing Carbonates Hypothesis

Experiment 3: Repeated lime input to overload large reactor

Experiment 4: Overloading the reactors with lower flow rate

Experiment 5: Overloading the reactors with different up-flow velocities in each one

Experiment 6: Blending the lime slurry 

Experiment 7: Pulsing in a stock solution of lime

Experiment 8: Formalizing blender methods + continued pulsing

Experiment 9: Increased lime concentration + continued pulsing 

From the experimental observation and results analysis, the Spring 2010 team proposed several suggestions on how to improve the design in the future, discussed the feasibility of implementing the design in Aguaclara plant and provided the next team with future challenges.