Energy-cost cooler

Reading, Pennsylvania — RPA Engineering is employing Allen-Bradley technology within, what it claims is, a unique temperature-control system for cooling towers used in chilled-water processes.
The dual PLC-driven system offers a variable control option that allows two or more cooling towers to be individually controlled for cost and energy savings.

Traditionally, a single-temperature controller operates two or more cooling towers’ fans in tandem. However, cooling towers are very sensitive to changes in process temperatures, as well as fluctuations in humidity and ambient conditions.

In systems with multiple cooling towers, this sensitivity can result in wasted energy as the secondary cooling towers are sometimes forced to run unnecessarily in response to subtle atmospheric and process changes.

RPA’s “dual cooling tower spillover temperature control” system allows the controller to establish different set points for each cooling tower. It is already operating at a number of manufacturing and foundry locations.

The first tower, therefore, operates its fan only as needed to regulate the temperature, while the additional tower fans are engaged only as needed to regulate the broad range of temperatures required by the process plant equipment.

The system uses an Allen-Bradley RS Logix 5000 PLC with a unique proprietary ladder-logic and structured text program in conjunction with variable frequency drives to control the fans speed.

Target applications include facilities that use a chilled or cool water process at oil refineries, chemical plants, power stations, iron and steel foundries and other process manufacturing plants. It is suitable for both new and retrofit applications and be adapted to any manufacturer’s fan-controlled cooling tower.

“The design helps to eliminate waste heat from induction furnaces, arc furnaces, induction coils, power supplies and quench tanks, while managing the fans, pumps, valves and temperature control loops,” said Jack Guitas, manager of electrical and controls engineering for RPA.