Alum Stock Tank Design Program
The purpose of the alum stock tank design program is to calculate the dimensions of the stock tank. The stock tank is placed on a platform close to the entrance tank so that the alum coagulant can be added to the raw water during rapid mix. The calculations for the alum stock tank can be found in the "ChemStorageTanks" MathCAD file, which is in the "Final Designs" folder on the AguaClara sourceforge. The design drawing can be found in the "AlumStock" AutoCAD file.
Alum Stock Tank Drawing
Alum Stock Tank Design Algorithm
The maximum flow rate through the alum stock tank is calculated based on the plant flow rate, and concentration of alum. These values are found in the User Inputs program.
Unknown macro: {latex}
\large
$$
Q_
Unknown macro: {AlumStockMax}
= {{Q_
Unknown macro: {Plant}
\cdot C_
Unknown macro: {FcmDoseMax}
} \over {C_
Unknown macro: {FcmAlum}
}}
$$
The volume of the Alum stock tank can then be calculated based on the User Inputs.
Unknown macro: {latex}
\large
$$
V_
Unknown macro: {AlumTank}
= Q_
Unknown macro: {AlumStockMax}
\cdot Ti_
Unknown macro: {StockMin}
$$
The height necessary to overcome head loss from the Alum stock tank is calculated using the orifice flow equation.
Unknown macro: {latex}
\large
$$
H_
Unknown macro: {MinAlumTank}
= ({{Q_
Unknown macro: {AlumStockMax}
} \over {Kvc \cdot (0.5 \cdot D_
Unknown macro: {FcmValveOrifice}
)^2 \cdot \pi }})^2 {1 \over {2 \cdot g}} + .1m
$$
Using a height to diameter ratio of 1.5 we calculate the stock tank radius.
Unknown macro: {latex}
\large
$$
R_
Unknown macro: {AlumTank}
= ({{V_
} \over {2\pi \cdot Ratio_
Unknown macro: {HeightToDiameterStockTank}
}})^
Unknown macro: {1/3}
$$
With the calculated radius we know the height of the stock tank.
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\large
$$
H_
Unknown macro: {AlumTank}
= Ratio_
Unknown macro: {HeightToDiameterStockTank}
\cdot 2\pi \cdot R_
$$
If H.AlumTank is greater than or equal to H.MinAlumTank then we have achieved the goal and we stop here. However, if the H.AlumTank is less than H.MinTank we set the height of the tank equal to H.MinAlumTank. Then we recalculate the radius based off the height diameter ratio.