The world of industrial process cooling equipment is one of extremes, with diverse and unique equipment required to complete processes that can have a wide variety of operational characteristics in terms of operating temperatures, viscosities and particulate levels. This need for versatility requires the plant’s process engineer to become adept in managing many different types of equipment, supplies and materials during the course of the process cooling operation.
One of the key pieces of equipment in process cooling is the industrial pump. Many different styles of pump can be used, but pumps that incorporate air-operated, double-diaphragm (AODD) technology have long been a first choice for process cooling engineers. AODD pumps meet the needs of diverse process cooling applications because they have been designed to operate efficiently and reliably in a range of utilitarian, severe-duty pumping conditions.
One example of a process cooling operation within a severe-duty application is found in steel mills, where AODD pumps serve the coolant quench line. In order to roll steel into plates or coils, the steel slabs must be heated to 2,282°F (1,250°C). When the slab reaches that temperature, it is rolled back and forth in a roughing stand, where it will eventually be reduced to a thickness of 0.08 inches (2 mm) and grow to a length of 4,265 feet (1,300 m)—the equivalent of nearly one mile—before it is rolled into a coil for shipping or storage.
Facilitating this process are the rollers that flatten the extremely hot steel slab to the required thickness. As the hot steel is rolled through the roughing stand, it is sprayed with a light, oily coolant that is needed to cool and lubricate the rollers during the quenching process. While this coolant is integral to the proper operation of the rollers, it must also be removed from the steel at some point.
To remove the coolant from the steel, high-pressure spray pumps are used. The coolant drains to a collection pit located beneath the rolling line. Also located in this coolant-collection pit are AODD pumps, which transfer the coolant from the collection pit through a filter and back to the coolant’s storage tank, where it is reused to spray the rollers.
AODD pumps are needed in the coolant recirculation process because the high-pressure spray pumps that remove the coolant tend to also dislodge debris such as dirt, grit, steel fines and other impurities that are on the steel. These impurities find their way into the coolant-collection pit and must be removed from the coolant before it is recirculated. The AODD pump is well suited for the operation because it can handle liquids that contain solids or particulate matter.
The AODD pump is able to perform these difficult tasks where other pump types fall short because of its design. AODD pumps operate by displacing fluid from one of its two liquid chambers upon each stroke completion. To operate, the AODD pumps require a given amount of pressure—measured in pounds per square inch—and air volume—measured in cubic feet per minute—to deliver the proper amount of fluid. This simple design allows AODD pumps to provide efficient, reliable operation in many pumping situations. Other operational characteristics of AODD pump that make them a common choice in process cooling applications are portability, dry-run capability, sealless design, deadhead capability, shear-sensitivity, self-priming operation and submersibility. For more on the operation of AODD pumps, please check out this video on “How Air-Operated Double-Diaphragm Pumps Work” from Wilden® Pump & Engineering Co.
Grand Terrace, CA, USA-based Wilden has long recognized the need for robust, reliable pumps in severe-duty fluid-transfer applications and has designed its full lines of AODD Pumps to meet the needs of process coolers everywhere.
We are always interested in hearing about any equipment-related successes you have had in any of your operations. If there are any recent instances where an AODD pump has helped optimize your capabilities in any industrial fluid-handling applications, please send me an email at tom.zuckett@psgdover.com.
