Food & Beverage / Dairy
The corporate group Emmi AG, a dairy processor in Landquart (Switzerland), has for the first time employed an NT100X plate heat exchanger as milk pasteurizer from Kelvion PHE GmbH. The result was an efficiency increase of 10%. Landquart is a city in the Swiss canton of Graubünden. The company Emmi AG, the largest Swiss producer of cheese, has since 1993 primarily produced Raclette cheese in Landquart. The company recently set two objectives: to reduce energy costs, and at the same time to further increase cheese production – which had already reached its energetic limit. To achieve these goals, the company focused its attention on savings available from the milk pasteurizing process. According to Emmi calculations, it would be necessary to increase heat recovery in the pasteurization process from 91 to 94% to achieve the desired effect.
The problem: with the use of conventional milk pasteurization systems, achieving the desired constellation of high heat recovery efficiency, an effective temperature program, and a high flow rate was virtually impossible owing to the fact that the systems involved had reached the limits dictated by physics. The solution: Emmi broke new ground and installed an NT100X multi-stage pasteurizer from Kelvion PHE GmbH for milk heating. The NT series had proved its new features and had, for example, already provided top performance in the brewery and beverage industry. Thus it was a perfect match to win over Emmi for launching the NT100X for the dairy industry. Since its implementation of NT100X, Emmi has recorded consistent evidence of achieving approx. 10% energy cost savings in pasteurization at its plant near Chur (Switzerland) – combined with an increase in throughput from 12,000 to 15,000 liters per hour. Not only that: Emmi Group later again raised its production capacity significantly – an output of 25,000 liters per hour has by now been reached by upgrading the highly efficient NT100X with an additional plate package.
This represented the simplest, most flexible, and most cost-effective option for the company. The Plant Manager Werner Sutter in Landquart: “For as long as we can remember, Emmi has been a GEA customer. And Kelvion PHE GmbH can look back on more than 80 years of experience in the manufacture of milk pasteurizers. As a result, we had complete confidence in the NT series.” Emmi was confident even though there had been virtually no empirical evidence from the dairy industry in support of this system. The decisive factor, however, was the technical specifications. Once the specialists at Emmi had looked beyond their own requirements to NT success in the brewing industry, they were convinced – even before the Kelvion plate heat exchanger was installed. The gasketed plate heat exchangers from the NT series excel with their patented OptiWave plate design. Despite smaller heat-transfer surfaces, this design increases performance and accordingly reduces investment and maintenance costs for the customer. The compact units in the NT series are simple to install from the handling aspect, and offer innovative EcoLoc gasket technology. The multi-stage NT100X pasteurizer features novel EcoLoc gaskets without adhesives. These gaskets can be exchanged quickly and easily. In case of maintenance, this reduces production downtime to a minimum. Additionally, this plate heat exchanger features a self-centering plate package that provides optimal seating of the plates and, in turn, security that the user can really count on in milk pasteurization.
The asymmetrical plate design of the NT series has convinced its users by its ideal flow profile – which assures uniform flow as well as its consistent self-cleaning effect. This considerably reduces the accumulation of residue coating, which enables longer uptime. The Landquart Plant Manager Sutter: “Typically, we allow production to run for ten hours before we rinse the machine and then clean it.” But production at Landquart has also run for longer uptime periods without difficulties at any point. “We are in fact completely satisfied with the pasteurizer, and we trust it to output considerably more for us,” Sutter emphasizes. This is also why the NT plate heat exchanger has been opened only once a year for inspection – because it has always been free of residue coating. “We had to service the previously installed model much more frequently,” says Sutter, “because we found accumulation of residue in some cases.”Milk is a sensitive product – one that must be gently heated. This requires long thermal processing of the product. At the same time, it is also necessary to heat the milk in a multistage pasteurizer for at least 15 seconds to 72°C. This is the necessary step to inactivate any possible pathogenic microorganisms, followed by quickly cooling the milk in the further pasteurization process to preserve proteins and vitamins. All this takes place in one NT machine, one step per section. With the NT100X, heat recovery is at the specified 94% – a high level in the dairy industry. It would be technically possible to achieve as much as 96% here, but this would result in investment costs at an unprofitably high level.
Although there is no legal requirement for equipment manufacturers to have new systems for milk pasteurization officially approved in Germany, Kelvion PHE GmbH decided to follow the old tradition by certifying its new system as a milk pasteurizer. The Department of Safety and Quality for Dairy and Fish Products at the Max Rubner Institute in Germany has granted the NT series official approval as milk heater. As part of this approval, an expert from the German Federal Research Institute visited Emmi in Switzerland and conducted type testing in the actual running production process at the plant in Landquart. This approval testing covered the following factors: the efficiency of heat recovery in heat exchange, characteristic data for heat and flow, condition of the milk flow gaps after uptime testing for residue coating, flow control, gasketing of the milk flow gaps, as well as service quality. As Sutter summarized: “The obtained findings correlated with our experience gained in actual service. Anything else would have been a big surprise to me.” Sutters NT100X now carries the approval mark KI-E 670/10 as certification for use in milk processing. The following model sizes of the NT series are accordingly now certified as high-temperature, short-time (HTST) pasteurizers for milk: NT50, NT100, and NT150. These pasteurizers can be fitted with plates of various lengths, according to the customer’s requirements. The company Emmi AG was founded in 1993 as successor to the Central Swiss Dairy Association of Lucerne, established in 1907 and later known as Swiss Dairy Food. In Switzerland alone, Emmi operates nine production plants and employs 3,700 staff. The headquarters of this internationally oriented corporate group is in Lucerne, Switzerland. In 2010, the group achieved net sales of nearly 2.7 billion Swiss francs by processing almost one billion liters of milk and cream. Emmi concentrates on the production of cheese and fresh cheese, as well as dairy products such as milk, butter, quark (curd cheese), yoghurt, milk drinks, desserts, and ice cream. Emmi produces 54 types of cheese alone, ranging from mozzarella, cheese spread, and fondue cheese, to hard and semi-hard cheese types.