Chemical Doser Design for Tamara, Honduras

The chemical doser (CD) designed for Tamara, Honduras has approximately the same design as the robust experimental CD from Fall 2008. The changes made to that design are explained below and a full guide to calibrating the system can be found here.

FC Outflow Tubing

In order to get a ballpark estimate of the length of tubing needed for the flow controller (FC) outflow for Tamara the theoretical performance of 1/8"ID tubing was plotted for multiple tubing lengths. It is apparent from that graph (below) that the 1/8"ID tubing would not give the performance needed at the Tamara plant (shown as the dotted pink line). Another line for 3/16"ID tubing, at 3.25 m long, shown on the same graph matches the Tamara theoretical head loss to dosing demand perfectly. Although 3.25 m is a long tubing length, it provides the necessary ratio of head loss to out flow.

CD Frame Height

The other CD parameter that was changed from the experimental robust design to the actual plant design was the overall height of the system. In the lab a tall (~4') CD was used for convenience. The height of the CD does not directly impact its function, but it must allow the FC and chemical dosing to occur below the height of the stock tank outflow. In Tamara this constrains the CD to a maximum height of approximately 13 cm. Calculations have shown that the system can function properly (i.e. without hitting the plant tank walls, etc) at such a low height.