...
Lime dosage required in the Lime-feeder
...
For our experiment, the lime feeder water flow rate required was calculated in a MathCad file.
The variables required in the analysis, such as the dosage of lime, the operation time, water velocities, water pH etc. were taken from the values in the previous team's report. Hence the raw water was assumed to have a hardness of 0.02gm/L and an initial pH of 6.5.
...
The total lime required is the sum of these two parts, the equations are shown below.
...
Relationship between the ratio of flow rates and pH
Under actual plant conditions, we cannot keep the flow rate of water in the lime feeder constant. The water flow rate entering the lime feeder will keep changing in proportion to the actual plant flow rate because the doage of lime required in the plant will change as per the amount of water entering the plant. So the calculations must be based on the variable 'ratio' i.e. the fraction of plant flow rate entering the lime feeder.
The effect of this ratio on the ANC and pH are illustrated in the MathCad file.
...