Tucked away in the West Virginia Mountains next to the slow flowing Ohio River is the CertainTeed drywall facility.
The Moundsville, WV plant is designed to flow drywall sheet materials up to 500 feet per minute. The process pours, shapes, flattens, and dries the product to its final form. Any part of the production process that produces waste is recycled. Even the materials that make up the product are derived from local waste and recycled material streams.
A major element in the manufacturing process is water, which must be controlled within a tight temperature range. Process water that is too hot or too cold results in product inconsistencies and poor quality.
The water driven off during the drying process is condensed and the temperature is adjusted by high capacity cooling towers. Unfortunately, during the hot summer, the temperature of the reclaimed water exceeds the maximum allowable range, resulting in unscheduled and unwanted plant shutdowns. To prevent this, supplemental cooling capacity was required to lower the process water temperature.
Application: ACT was contacted to evaluate and size a large, direct drive, fan cooled radiator system that could be placed in series with the building products process water loop. ACT provided performance predictions as a function of flow rate, incoming process water temperature, outdoor temperature, and fan speed. The water is continuously pumped through the radiator at a fixed flow rate between 17 and 21 gpm. The temperature of the water leaving the fan cooled radiator is controlled by varying the speed of the fan. A variable frequency drive was used to modulate the fan motor speed. The process control parameters are monitored and controlled by local PLCs and coordinated through the plant SCADA system. The fan cooled radiator system was required to cool the process water to approximately 60°F, which translates into a cooling capacity of over 600,000 BTU/hr. of cooling.
Design Scope: The fan controlled radiator was engineered to address the process parameters. All metal surfaces were formed from 304 stainless steel. The radiator coils were E-coated to prevent corrosion. A direct drive 54 inch diameter, 10.9° pitch, high speed fan was driven by a ten horsepower AC motor. An Ethernet based temperature sensor is used to provide input to a PLC. The PLC communicates via Allen Bradley Device Net to vary the frequency of the 460VAC motor drive coupled to the fan cooled radiator’s 10 HP motor.
Conception to Installation and Start-Up: ACT provided support throughout the entire project ranging from the initial design to predictive performance modeling to field installation and startup support. ACT also designed and built the custom three foot high, galvanized steel mounting base and the AC drive motor control cabinet. The final deliverable included full system documentation including startup and maintenance recommendations.
Project Results: The plant engineering and facilities teams are pleased with the initial performance of the radiator system. Early in the conceptual stage, a $400,000 chiller system was proposed. The chiller system was expensive from both initial cost and operating cost points of view. The fan cooled radiator solution from ACT was chosen over the chiller system as the solution with the highest value, value being defined as function / cost. A cost avoidance of nearly $400K was realized. Thomas Oei, Sr. Project Manager for CertainTeed commented on the project:
An effective, innovative and complete solution for our cooling need was provided by ACT.
Their continual support from project conception to commissioning resulted in exceeding our expectations as well as the original equipment specifications.”
The project was completed one week ahead of schedule and 15% under budget. It was in full compliance with CertainTeed’s World Class Manufacturing (WCM) practices, in large part because of the complete documentation and vendor information provided. CertainTeed also achieved “vertical startup”, which is one of the aims of WCM. Vertical startup means the switch is turned on and it works, and continues to work. Thomas Oei continued “In the opinion of CertainTeed, ACT was able to work well with our local contractors and plant staff to ensure the successful equipment integration into the plant automation systems.”
The additional process control achieved through the implementation of the supplemental fan cooled radiator will result in less downtime, improved quality, and will allow CertainTeed to do innovative new product development that may require cooler process water temperatures.
