Concerned about the possibility of increased downtime and lost production, one plastics processor recently decided to install a new chiller.
“If the chillers go down, the whole plant goes down. And we didn't trust the chillers,” explains Walter Pipan, engineering manager.
UPM Inc., Baldwin Park, Calif., specializes in the production of custom injection-molded plastics. A key element to the company's production is the availability of chilled water to keep the intricate injection molding machines cool.
UPM's manufacturing facility, which is one of the largest plastics firms on the West Coast, produces plastic crates, containers, trays and complex specialty parts for many applications. The injection-molding machines rely on a flow of chilled water to remove process waste heat and remain in operation. “It's this simple: No chilled water, no production,” says Pipan.
Until recently, chilled water was supplied to the facility by an older 150-ton water-cooled chiller with six reciprocating compressors and a 106-ton water-cooled chiller with two screw compressors. An air-cooled reciprocating compressor chiller also was in reserve, though its condition was questionable. The chillers and related equipment were located at grade level in a mechanical yard adjacent to the manufacturing building. Pipan and the production staff were concerned because the reciprocating compressor chiller appeared to be getting increasingly unreliable, and frequent inspection and repair outages were required. Because the manufacturing plant operates around the clock, there was no good time to do service work. The specter of chiller failure was an increasing threat to production.
UPM approached Thermal Care Inc., a process cooling equipment manufacturer in Niles, Ill., that specializes in chilled water equipment. Working with Michael Clavelli, Thermal Care's West Coast regional manager, Pipan and other staff members explained their concerns about the reliability of the chillers, and their need to reduce the risk of losing their chilled water service.
Pipan and his team also indicated that they were interested in reducing the energy usage of the chilled water operation. Additionally, any replacement equipment would have to fit in the existing mechanical area.
After a detailed evaluation of the facility, Thermal Care recommended removing the water-cooled and standby air-cooled reciprocating compressor chillers in stages and replacing them with two chillers custom-designed for the installation. The new units would use a new type of centrifugal compressor manufactured by Danfoss Turbocor Compressors Inc., Dorval, Québec.
“We wanted to design a system with high reliability and efficiency. What we proposed was a system that we think is ideal for this type of process application,” Clavelli says.
After reviewing the proposal, UPM told Thermal Care to proceed with the new system installation. Thermal Care and Danfoss Turbocor had worked together for over a year in the development of this chiller product.
Because the new system would operate at a higher efficiency than the existing chillers, UPM was eligible for a rebate from the electric utility, Southern California Edison, which would further shorten the project payback. In early 2003, the water-cooled reciprocating chiller was removed and replaced with the first Thermal Care chiller. In June 2004, the air-cooled machine was removed and replaced with a second Thermal Care package. The existing screw chiller remains on the site and is generally held in standby status.
“The efficiency of the new chillers is such that we recommend they be used to carry the load, while the screw chiller is held as a backup,” Clavelli explains.
The Danfoss Turbocor compressors at the heart of the new chillers have a number of design characteristics that contribute to their high reliability and performance. For example, the machine is an oil-free design, and the shaft-and-twin-impeller assembly is the only moving part. The impeller shaft rotates on magnetic bearings, which eliminate friction and wear in the compressor. The bearings also require no oil, thereby avoiding many associated maintenance costs and problems.
The compressor design also incorporates a variable-speed motor and can operate at high efficiency over a range of loads. According to Clavelli, this makes the units well suited for mid-range size refrigeration applications such as the chillers installed at UPM.
Staying in the Sweet SpotThe chillers designed for the UPM installation each have two 70-ton Danfoss Turbocor compressors. The chillers have individual unit controls and diagnostics, and, along with the screw chiller, are linked to a central chilled water control system. In this installation, chilled water at approximately 50°F (10°C) goes to a 1,000-gal supply tank, from which it is pumped to injection-process machines as needed. The water typically returns from the manufacturing process to the chiller plant at approximately 60°F (16°C). The condensing water from the chillers is cooled by a custom fiberglass, forced-draft cooling tower, which also was supplied by Thermal Care.
An important aspect of the installation is the remote-monitoring capability. Thermal Care provided a central processing unit (CPU) and ran interconnecting cables from the CPU to the chiller, software and an Internet card. This design allows UPM or service specialists at Thermal Care to have remote access to 79 points of diagnostic information per compressor, including the status of the compressors, electronic expansion valves and condensing water regulating valves.
According to Tom Benson, Thermal Care's vice president of sales and marketing, “We can quickly assist with any chiller performance questions by having one of our service specialists communicate directly with the chiller through the Internet. Both Thermal Care and the end user can view temperatures, pressures, volts and amp draws, log and save data, adjust setpoints or control parameters, view alarm history and captured data at the time of the fault, view demand profile including KW usage, and make PLC program updates.”
Coordination During InstallationThe installation of the chillers at UPM was handled by West Coast Industrial Services Inc. (WCIS), Riverside, Calif. Bill Stanonis, president of WCIS, indicates that his team worked closely with Thermal Care's corporate staff and with Michael Clavelli to install and start the unit as efficiently as possible.
According to Pipan from UPM, the company immediately noticed a reduction in the plant's electric demand charge from Southern California Edison with the installation of the first chiller in 2003, and the installation of the second unit increased that savings. “The machines are using about 40 percent less energy than the reciprocating units that we were relying on earlier,” Pipan says.
Combined with the Southern California Edison rebate, the reduction in energy use is providing a significant payback on the new chillers.
Pipan also mentions that with a peak acoustic level of 71 dBA, the new chillers are much quieter than their predecessors. “I came out into the yard during the installation and asked when they were starting the compressors. When they told me they were already running, I was surprised. You can actually hold a conversation here now, where you couldn't when the recip units were running,” he notes. While this low acoustic signature was not critical in this installation, Pipan says it was a welcome change.
Increased UptimeWith the installation of the second unit in 2004, the screw chiller was relegated to standby status. Pipan is impressed at the reliability to date of the Thermal Care system and the Turbocor compressors. “They run great,” he says. “We've been really pleased with the reliability of the chillers.”
Stanonis from WCIS indicates that his firm handles the maintenance on the chilled water plant equipment at UPM, but there have been few service calls. “These compressors just don't require much attention,” he says.
Pipan also points out that the new 140-ton chillers actually have a smaller footprint than the chillers they replaced, thus freeing up space in the mechanical yard. But would he recommend installing this type of chiller with oil-free compressors to a colleague?
“Go ahead,” he says. “You will benefit from the energy savings, lower maintenance, no compressor oil, and only one moving part in the compressor. It's a good solution.”
For more information about industrial process chillers from Thermal Care, Niles, Ill., call (847) 966-2260; firstname.lastname@example.org visitwww.thermalcare.com.