Fan Case Studies

Blower Use for an Industrial Application

Background

The operation of a centrifugal fan by damper control is energy inefficient because part of the energy supplied to the fan is lost across the damper. The damper control has to be minimized by suitably optimizing the capacity of the fan to suit the requirement. One of the best methods to optimize the capacity of the fan is by reducing the revolutions per minute (RPM) of the fan and operating the blower with more damper opening.

Previous Status

In this particular example, an air blower was operated with a 30% damper opening. The blower was belt driven. The pressure required for the process was 0.0853 psi. The pressure rise of the blower was 0.1423 psi and the pressure drop across the damper was 0.0569 psi. This indicates an excess capacity/static head available in the blower.

Energy Saving Project

The RPM of the blower was reduced by 20% by suitably changing the pulley. After the reduction in RPM, the damper was operated with 60% to 70% opening. The replacement of the pulley was accomplished during a non-working day. No difficulties were encountered on implementation of the project.

Financial Analysis

This reduction in RPM of the blower and minimization of the damper control resulted in reduction of power consumption by 1.2 kW. This resulted in an annual savings of approximately $720. The investment made was approximately $210, which was paid back in under 4 months.