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incorporate a variety of vital subsystems. Tese include: • Filters and other devices to keep the water clean and flowing.


• Heat exchangers, inline heaters and cold water diversion valves to main- tain the optimal water temperature.


• Automatic city water makeup to keep the cooling system full.


• Flow sensors, pressure gauges, thermometers, water meters, and other monitoring and control devices needed to be sure it’s all working properly.


• An emergency backup system to maintain furnace cooling in the event of pump failure or power outage. Because cooling systems are so


essential, when the system at Chassix was no longer able to meet its needs, the management team moved quickly to repair or replace it. According to Darold “Jack” Roop, senior project engineer, Chassix, the


problems with the old cooling system had increased considerably when new furnaces were installed to support growth in the company’s casting business. “We added three 12.5 metric tons per


hour, medium frequency induction fur- naces for batch melting, along with their power supplies, compressors and hydrau- lics,” Roop explained. “But our cooling system lacked the capacity to handle this new load. Due to inadequate cooling, the furnaces frequently overheated and tripped out. Several coils were burned up. We did not have sufficient cooling to allow us to run all of our furnaces at the same time. Tis reduced our metal pro- duction and limited our ability to fully benefit from the new melting capacity we had just added.” Chassix determined repairs to the existing cooling system would not pro- vide the cooling capacity needed, so it set up and funded a project to replace much of the system. Chassix project


manager Frank Burton oversaw the creation of the new cooling system. “Our cooling tower was old, the


wood was rotting and falling apart and its three pumps had to run all the time to provide needed cooling,” he said. “Tere was no redundancy. If one pump failed, production had to be shut down until the pump could be replaced. Shutting down was a slow process. Te only emergency backup was city water, and that outflow pre- sented environmental concerns.”


Designing an Induction Melt Cooling System


Very small induction furnaces used


in labs or for melting small quantities of precious metals may be cooled by direct connection to an incoming city water line and use a city drain for the outflow. Most other size furnaces require a pump or pumps to push cooling water through the furnace and a cooling tower of some kind to remove the heat from the water, which is then recircu- lated back through the furnace. Tis is the basis of most cooling systems. To design a cooling system for an


induction melt shop, first you must deter- mine the heat load on the system, taking into account the size of each furnace, the power applied, the metal melted, type of melting (batch or heel), holding and pouring times and the heat loads added by non-furnace ancillary equipment. Tese calculations can be complex.


Te new cooling system for Chassix was based on heat load calculations for the facility’s wide variety of furnace sizes, melting processes and ancil- lary equipment used to support them. Tese included: • Three 12.5-metric-ton, medium frequency induction batch melting furnaces.


• Five 10-ton line frequency induc- tion heel melting furnaces.


• Two 17-ton line frequency induc- tion heel melting furnaces.


• Ancillary systems including air compressors, hydraulic pumps and air conditioners. Te calculations also had to take into


Chassix project manager Frank Burton at the new cooling tower and its pumps.


account the need for backup capacity to maintain cooling during equipment maintenance or repair and to support future growth.


February 2014 MODERN CASTING | 33


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