$42,000. Danfoss Turbocor Compressors Give INTERTECH PLASTICS A RESHORING ADVANTAGE. saved annually

Transcription

1 CASE STUDY TWO $42,000 saved annually Intertech s new variable speed cooling system is precise, reliable, and efficient slashing cooling costs by approximately $42,000 annually. Danfoss Turbocor Compressors Give INTERTECH PLASTICS A RESHORING ADVANTAGE BILLIONS OF CELL PHONE CASES, LAUNDRY BASKETS, PLASTIC TOTES, AND STORAGE BINS ARE PRODUCED BY A PROCESS KNOWN AS PLASTIC INJECTION MOLDING. That s why there s a lucrative, multi-billion-dollar plastics injection molding industry in the United States and why they re facing stiff competition from overseas producers. But one enterprising manufacturer based in Denver, Colo., Intertech Plastics, illustrates the new trend in reshoring by re-energizing domestic plastics manufacturing with the help of innovative, energy-efficient Danfoss Turbocor compressors. In a plastic injection molding machine, it is very important to cool the mold properly to get maximum productivity, says Mike Clavelli, west coast regional manager for Niles, Ill.-based Thermal Care, Intertech s process cooling system provider. As a manufacturer of process cooling equipment and systems for worldwide applications, Thermal Care recently installed for Intertech two centrifugal chillers using Danfoss Turbocor variable speed compressors. Clavelli explains: When Intertech added two new Husky 1,100-ton high-speed molding presses, we implemented the chiller installation using an array of variable speed technologies. This solution delivers variable cooling capacity that is precise, reliable, and efficient, which is giving Intertech a huge domestic and global competitive advantage.» VOLUME 13 / WINTER /

2 CASE STUDY TWO CONTINUED We ve been successful using Danfoss Turbocor centrifugal compressors in injection molding cooling for nearly a decade. Mike Clavelli, west coast regional manager for Thermal Care Handling the Heat of Plastic Injection Molding An injection molding machine employs two basic components: a clamp unit to hold the mold, and an injection unit where plastic is heated and mixed before being injected into the mold. Time, speed, pressure, and temperature all have to be controlled to ensure proper operation and maximum throughput. Depending on the resins, mold temperatures can range as high as 180 degrees Fahrenheit. At the beginning of each production cycle, the clamp unit closes the mold, and a screw in the injection unit pushes forward to shoot molten material into the mold. Continual pressure is applied to hold the plastic in place until it solidifies. While the material in the mold cools, the screw rotates and retracts to draw in new material for the next shot. When the part reaches the precise temperature set point, the clamp opens to eject the finished part and start the next cycle. Depending on the part size and type of plastic, the entire cycle can take anywhere from a few seconds to over a minute. Productivity depends on cooling that mold properly, says Clavelli. The difference in throughput can be huge. For example, with good temperature control you might be able to make 20 parts per hour instead of just three. Energy-efficient Cooling for Injection Molding Machines For efficient cooling, Thermal Care designed and manufactured a plant-wide central chiller cooling system to handle the unique requirements of Intertech Plastics two injection molding presses. The system comprises two centrifugal chillers, a cooling tower, and condenser and evaporator circuits using variable frequency drive pumps. The piping was designed to scale up to add another chiller if needed. To maximize the chillers efficiency, Clavelli applied Danfoss Turbocor centrifugal compressors with an oil-free, magnetic-bearing design instead of rotary screw compressors commonly used in the industry. We ve been successful using Danfoss Turbocor centrifugal compressors in injection molding cooling for nearly a decade, says Clavelli. In this case, a 140-ton chiller employs two Danfoss Turbocor TT300 compressors, and a 70-ton chiller uses one TT300 compressor. In this installation, the chillers supply a 1,000-gallon thermal storage tank with chilled water at 50 degrees Fahrenheit. From there, a liquid cooler pump control circulates water to the injection process to cool the molds as needed. The tool 12 ENVISIONEERING SOLUTIONS

3 and mold sections can range in temperature from 150 to 180 degrees. Depending on the temperature requirements for the part, a mold temperature control unit may be used to mix warmer water with the 50-degree supply water to provide the exact degree of cooling required. The temperature of the water that returns from the process is approximately 60 degrees. Because the amount of supplied chilled water varies, this application proved ideal for the Danfoss Turbocor compressor s variable speed capability. A rotary screw compressor may use stepless speed control or slide valve control to vary capacity, but those will be inefficient in certain conditions, says Clavelli. Danfoss Turbocor compressors simply vary compressor speed to deliver the needed cooling capacity. When full cooling capacity is not needed which is about 95 percent of the time the Danfoss Turbocor compressor reduces RPMs to produce just the amount of compressed refrigerant gas needed to match the cooling load. In a centrifugal compressor, electrical consumption is directly proportional to motor shaft speed. So slowing down reduces the amount of electricity consumed linearly: running at 50 percent speed reduces the compressor s electricity consumption by about 50 percent. At the same time, the Coefficient of Performance (COP) a measure of energy efficiency calculated by dividing the amount of cooling by the amount of power supplied to the compressor is much better as the cooling load is reduced. For example, at 40 percent capacity the COP of a Danfoss Turbocor compressor is more than double that of a rotary screw compressor. Coefficient of Performance (COP) : A measure of energy effiency calculated by dividing the amount of cooling by the amount of power supplied to the compressor. Easily Integrates with a Free Cooling Configuration Clavelli appreciates the inherent energy efficiency of the Danfoss Turbocor compressor, but he also values its ability to use colder cooling tower water. Denver is the Mile-High City, so outdoor ambient temperatures let Intertech use cooling tower water to drop the condenser water temperature, says Clavelli. Whenever you can do that, it means less work for the compressor. But conventional centrifugal chillers can t always run with cooling tower water below a 65-degree temperature limit. That s because below 65 degrees, the minimum entering condenser water temperature does not allow oil in the refrigerant to circulate properly to ensure compressor lubrication. We don t have oil circulation or oil management issues with Danfoss Turbocor compressors, notes Clavelli. That s because the Danfoss Turbocor design uses» Free Cooling Denver is the Mile-High City, so outdoor ambient temperatures let Intertech use cooling tower water to drop the condenser water temperature, says Clavelli. Whenever you can do that, it means less work for the compressor. VOLUME 13 / WINTER /

4 CASE STUDY TWO CONTINUED magnetic bearings that do not need oil. The impeller shaft spins in a friction-free magnetic field. And, because there is no oil to clog the system, a condenser water reset option can be used to enhance chiller efficiency to reduce energy consumption. That makes it is easy to use a free cool circuit with variable frequency drive pumps for both the cooling tower and chilled water loops. This configuration lets us take full advantage of off-design outdoor temperatures to avoid mechanical compression as much as possible, while variable speed capacity control lets us scale cooling capacity up and down as needed. The Thermal Care system with Danfoss Turbocor compressors has cut energy costs dramatically. Instead of paying $38 per hour for cooling, costs are now down to $3.40 per hour a remarkable order of magnitude in energy savings. The result: compared to the chillers it replaced at Intertech s facility, the Thermal Care system with Danfoss Turbocor compressors has cut energy costs dramatically. Instead of paying $38 per hour for cooling, costs are now down to $3.40 per hour a remarkable order of magnitude in energy savings. Danfoss Turbocor Compressor Wins on Size, Silence, Reliability, Controllability Clavelli also notes that the new chillers have a 50 percent smaller footprint than the chillers they replaced, freeing up space in the mechanical area. The magnetic bearing design eliminates the bearing race support structures and oil system, reducing actual operating weight to 265 pounds per compressor, while a conventional screw compressor can weigh over 1,000 pounds. Plus, with a peak acoustic level of 71 dba, the new chillers are much quieter than a typical screw compressor. Low sound was critical to this project, and it s nice to be able to stand beside the chiller while the compressors are running and hold a conversation without ear protection. Another critical benefit is controllability and reliability. We implemented an on-board programmable logic controller (PLC) on the chillers to provide a user interface. With inherent digital operation, each Danfoss Turbocor compressor provides nearly 80 points of diagnostic information: temperatures, pressures, volts, amp draws, log and save data, adjust set points or control parameters, alarm history, faults, and demand profile, including kilowatt usage. Access to that level of information assures us and the customer that things are running right and that we could take prompt corrective action if needed, with the option to access that information remotely over the Internet. 14 ENVISIONEERING SOLUTIONS

5 70% reshoring, 25% more jobs By enabling a chiller solution that enhances the manufacturing operation, Intertech has a significant competitive advantage. In fact, they were able to attract a large customer to reshore 70 percent of their business, which added 25 percent more jobs. Total Cost of Chiller Ownership Makes Intertech More Competitive We ve been using Danfoss Turbocor compressors for years, says Clavelli. Having a reliable, oil-free centrifugal compressor design that runs efficiently at part load and that integrates smoothly with a free-cooling configuration is a big plus. By cutting cooling costs by an order of magnitude from $38 to $3.40 the new chillers will save about $42,000 in annual energy costs at the current process load compared to rotary screw chillers. Just as important, the new cooling system has improved the manufacturing operation by improving cycle time efficiency by five percent, increasing plant yield by nine percent, and reducing scrap by $194,000. Moreover, the installation qualified for a sizeable five-figure rebate from the local utility, Xcel Energy. Looking further at energy efficiency, the customer recently commented to Clavelli: I stopped by the chiller system this morning. The total compressor demand was at three percent, which means we re taking advantage of 97 percent free cooling plant-wide. Those power reductions, plus our operating efficiency gains, are a constant source of conversation here at the plant. Everyone remembers how the old chiller ran full out, all of the time. Clavelli also adds that the oil-free Danfoss Turbocor compressors lower maintenance costs. The Danfoss Turbocor compressor s magnetic-bearing design dramatically cuts Intertech s total cost of ownership, he says. And by enabling a chiller solution that enhances the manufacturing operation, we re giving Intertech a significant competitive advantage. In fact, they were able to attract a large customer to reshore 70 percent of their business, which added 25 percent more jobs. When you can use innovative technology to save energy and reshore American jobs, it s something to be proud of. VOLUME 13 / WINTER /