An efficient single-screw compressor technology is helping Valley Queen Cheese get more value out of its cheese byproducts while minimizing maintenance and energy costs.



The Valley Queen Cheese Factory in Milbank, S.D., was founded in 1929 by two Swiss immigrants with a knack for cheese-making. The plant has expanded several times over the past 75 years; the most recent 7,000 ft2 expansion, completed in 2004, houses a new delactosed whey drying process. The process involves removing line whey from the cheese-making process and then taking the sugar out of the whey to produce delactosed whey. After the sugar is removed, the liquefied, delactosed whey is dried into a powder. This dried powder is used as a milk replacer for calves and as an ingredient in other animal feed products.

Valley Queen uses reciprocating compressors from Vilter Manufacturing Corp., Cudahy, Wis., in its original plant. There, two compressors in two different systems (four compressors total) are used for process cooling. One system is devoted to cooling glycol, which is then used to cool lactose in the process of crystallization. The other system is used for cooling cheese storage areas and other process loads.

Valley Queen previously outsourced its delactosed whey drying process, but the company decided to bring this process in-house when the plant expanded in early 2004. To do this successfully, the company needed an efficient compressor. After carefully considering the operating requirements and the specifications of the new plant, Valley Queen chose a single-screw compressor technology from Vilter that was recommended by its design-build contractor Carlson & Stewart Refrigeration of Marshall, Minn. Carlson & Stewart specializes in industrial and commercial refrigeration systems.

“The Cool Compression system has the capacity to load and unload very efficiently, running at low or high capacity, so it was a good choice for this application,” said Dave Grong, project manager for Carlson & Stewart.

The single-screw compressor installed by Valley Queen has saved the plant a substantial amount of money in both energy and maintenance costs over the past three years.

The compressor also fit the bill in other ways for Valley Queen. According to Jason Humpton, Valley Queen’s maintenance manager, the small footprint of the compressor was important because little space was available in the mechanical room. Humpton also has appreciated the reduced maintenance requirements of the compressor. The system has fewer components compared to twin-screw and other single-screw compressors, which reduces the overall maintenance over the life of the unit.

One other benefit of the compressor is its reduced energy consumption. The system uses the efficiency of direct-contact heat transfer to cool the compressor oil in the oil separator. This technology reduces oil carryover and eliminates oil foaming as the liquid ammonia layer in the separator covers the heavier oil. The inherent pressure of the oil separator transfers the cooled oil back into the compressor.

Keeping the oil and liquid refrigerant at the saturation temperature leads to a cleaner and simpler design with reduced energy requirements. Grong estimates that the technology has saved Valley Queen a substantial amount of money in both energy and maintenance costs over the past three years, compared to what it might have spent with a twin-screw system.

Getting more value out of its cheese byproducts and employing other new technologies is a commitment this family-owned company has made in order to grow and prosper. The single-screw compressor is helping Valley Queen produce approximately 176,000 lb of delactosed whey daily while reaping maintenance and energy savings.

For more information from Vilter Manufacturing Corp., call (414) 744-0111 or visit www.vilter.com. For more information, from Carlson & Stewart Refrigeration, call (800) 215-2576 or www.carlsonstewart.com. For more information about Valley Queen Cheese, call (605) 432-4563 or visit www.vqcheese.com.

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