Cooling the Quench
By ED SULLIVAN
Patriot Forge “presses on” with advanced HDPE cooling towers to maintain optimum bath temperatures for quenching metal forgings and cooling hydraulic systems.
August 17, 2020
By ED SULLIVAN
For Patriot Forge, a Canadian custom open-die forging company, feeling the heat is nothing new. Forging is the process of shaping metal by applying extremely high temperatures, and a variety of powerful compressive forces. The process results in products that feature optimum toughness, ductility, and both impact-, and fatigue-strength.
Due to those attributes, forged materials are often the only option for a number of highly critical machinery and equipment applications. The process of forging metal requires dealing with temperatures which can reach up to 1,150°C. Controlling the process hinges on dependable cooling tower technology.
Cooling towers work by taking the hot water coming from the cooling system and reducing the temperature by exhausting the heat into the atmosphere. The water is then returned to the cooling system through a closed loop. This process is similar to a number of industrial applications such as refineries, metal foundries, and manufacturing plants.
FORMING ALTERNATIVE SOLUTIONS
Patriot Forge produces products in a variety of materials ranging from carbon, alloy, stainless steel, nickel-based alloys, and aluminum, at its plants in Branford and Paris, Ontario.
Producing for demanding industries requires consistent quality, including the vital hardness characteristics of forgings ranging from two kilograms to 50 tonnes.
The company recently decided to replace its aging, multi-use stainless steel cooling tower at its Branford plant.
“The tower was simply rotting out,” said Derek Hynes, Senior Mechanical Engineer, Patriot Forge. “It is common with metal models which tend to rust and corrode, which requires us to try and plug the water flow, and that can interfere with cooling capacity.”
Located in Building One, the cooling tower expels heat from the quench system, a 160,000 litre water tank into which parts are submerged in water or polymer baths in order to achieve the desired hardness.
Having spent months, and a lot of worker hours, trying to repair and maintain the steel tower, Hynes and his team went looking for an alternative to metal and stainless steel. Part of that research lead him to investigate high-density polyethylene (HDPE) cooling tower design options that provide reliable, trouble-free operation for a longer period of time.
HDPE cooling towers are impervious to corrosive environments, and require lower amounts of water treatment chemicals and less downtime for repair or replacement. Hynes team went with a HDPE tower model with energysaving features such as direct drive fan motors that reduce electricity costs.
“We saw that this was a polymer-based tower that was UV-protected, and included a 20-year warranty, so we were convinced that it would offer long-term dependable service,” said Hynes.
HDPE EXCEEDS EXPECTATIONS
According to Hynes, the switch to HDPE was so successful, and exceeded expectations, so Patriot Forge chose to acquire another HDPE cooling tower, supporting multiple systems within the Building One.
The new tower had to cool the water that flowed through a heat exchanger used to draw heat off the hydraulic systems of three large pieces of production equipment. This included a rail-bound manipulator, a hydraulic ring roller, and a 5,000-tonne press, which plays a primary role in the forging processes of the plant.
“Essentially, all three machines are cycling the water that flows through their hot hydraulic heat exchangers and then through this cooling tower. This enables us to keep the hydraulic fluids at a stable 43.3° C,” said Hynes.
EXTENDING THE BENEFITS
Hynes mentioned that thus far the towers have required zero requests for repairs and much less maintenance or attention. Earlier this year, Patriot Forge needed another cooling tower to help cool the quench tanks in Building Two, so they chose another HDPE. This time, they selected a twincell HDPE cooling tower that would service the company’s heat treat system.
“Both of the quench tanks are about 400,000L, and we use the cooling towers to help maintain a heat level of approximately 38°C,” said Hynes.
Patriot Forge designated induced draft models for this building. A major benefit of these towers is the ability to configure them in combination of up to six units with cooling capacity from 250 to 2,500 cooling tonnes. The modular design gives the end user the opportunity to add cooling capacity as their processing needs grow. The new cooling towers installed at Building Two are installed in a two-cell configuration with combined cooling capacity of 836 cooling tonnes.
“We decided on this size and configuration because the quench tanks in Building Two are much larger,” said Hynes. “So, there is a lot more water you have to process through the towers.”
Hynes says the towers feature vibration sensors on all fans, which eliminates the need to climb the towers in order to check out the operating performance of the fans, a benefit that Hynes feels is particularly appealing because one of the towers tops out at 65 feet, “a long way up.”
Ed Sullivan is a Los Angeles-based freelance writer with over 30 years of expertise in the mechanical engineering, HVAC, and process cooling industries.