VSD-equipped chiller an instant hit at compact-disc facility: production relies on constant supply of chilled water. (Case Studies).(variable-speed drive)

Sony Disc Manufacturing operates a 365,000-square-foot ([ft.sup.2]) compact-disc manufacturing facility in Springfield, OR. The five-year-old plant employs approximately 400 workers and has the capacity to produce as many as 12 million discs per month in a process that requires cooling 24-hours-a-day, 7-days-a-week. The year-round demand for chilled water is created by the need for humidity control, an extensive exhaust system, and production equipment that requires cooling.

When the facility was built, Sony installed two constant-speed centrifugal chillers, one a 400-ton unit and the other a 700-ton unit. During winter months the smaller unit met the average 300 to 350 ton load. During warmer summer months, the cooling load reached 900 to 1000 tons, which required the operation of both chillers. Sony understood that the heating, ventilating and air-conditioning (HVAC) system did not provide the redundancy critical to a 24/7 operation.

Sony required a system that was robust enough to remain on-line without compromising production, even in the face of system failures. "Our production equipment relies on chilled water, so we needed to ensure a constant supply, regardless of weather conditions or other events affecting conditions within the facility," said Steve Kreuzer, facilities engineer at Sony.

To provide redundancy year round, the company made the decision to purchase a third chiller. At first, they were looking for an inexpensive chiller that would be called into service only during an emergency. "Our initial thought," recalled Dan Riney, Sony's facilities engineering manager, "was to provide redundancy year round. That was our goal and one we thought we could achieve by purchasing one of the cheaper chillers on the market, figuring we would rarely, if ever, require its services."

Chiller with VSD Offers Energy Benefits

However, Dan Mitchell, technical sales representative with Applied Systems Oregon (ASO), convinced SONY that a 700-ton centrifugal chiller equipped with variable-speed drive (VSD) offered significant energy benefits.

Chillers typically spend less than 1% of the time operating at design conditions. The remaining operating time is spent in off-design-conditions where any or all of these basic conditions exist: