Case History No. 15

Industry & Location:

A cement plant in the northeast

Problem:

Inadequate draft from the kiln I.D. fan. Excessive duct pressure losses.

Source of Detection:

A large elbow is situated in the duct system upstream of the main I.D. fan. The position of this elbow in conjunction with a duct transition at the precipitator inlet is causing a pressure drop of 6" w.g. Because this pressure drop is inordinate, a decision was made to install turning vanes to straighten the flow and to minimize the pressure drop.

Duct Arrangement

Solution:

Because the ductwork arrangement is at an inaccessibly high elevation and of considerable size, the cost associated with installing duct turning vanes was evaluated to be in excess of $50,000. To minimize the chance of error or the possible need to reposition the vanes, a model study was made of the ductwork. The model study identified the problem and the results were used to design the turning vanes and new duct transition. With the model study, the duct modifications were made and the pressure loss was reduced from 6" to 2".

Model Study

Benefit:

Increased flow rate from the I.D. fan without an increase in fan horsepower consumption.