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The purpose of the Flow Control Module is to deliver a calibrated and easily varied dose of clay and alum into the plant.
Theoretical Design
The Flow Control ModuleController for the demonstration plant consists of bottles of alum solution and clay suspension attached to an upright pipe. A certain amount of tubing directs flow from each bottle into an inflow column before it flows into the first channel of the flocculator. There are multiple holes in the inflow column, and both the alum and clay tubes can be inserted into holes at varying heights to achieve different flow rates. In order to determine tube lengths and where they should be plugged into the mix inflow column for a certain flow rate, the FCM design tool was used. The theory behind the design tool is located on the Flow controller theory page, including formulas and application. The tool utilizes the Hagen-Poiseuille equation, explained on the theory page, for a relationship between head loss and tube length. We determined that with the water level in the bottles even with the top of the mix column and a head loss distance of about 5 cm between the water level and the outflow at the end of the pipe into the mix column, the design length for a tube with an 0.17" inner diameter is 73.5 cm to achieve a flow rate of 100 mL/min for the clay. For the bottle and outflow levels and a tube with an inner diameter of 0.063", the design length is about 95 cm to achieve a flow rate of 5 mL/min.
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