Energy-efficient and reliable vacuum supply for Cheddar production

Maulburg, Germany Glanbia Nutritionals in Ireland operates one of the most modern production facilities for the manufacture of high-quality matured Cheddar cheese. After pasteurisation and the addition of rennet the curd is cheddared by passing through a sealed system, which separates the whey and adds salt to the remaining curd. The resulting 'prepared curd' is transported by vacuum conveying lines to the cheese towers, where it is shaped into blocks. Busch Mink claw vacuum pumps are used for both the conveying and forming parts of this process, providing significant advantages over the previously installed vacuum system.
Seven cheese towers are supplied with vacuum by energy-efficient Busch Mink claw vacuum pumps.

Glanbia Nutritionals is part of the Glanbia Group, which operates two production sites in Ireland. A third site is under construction, making it the largest manufacturer of milk products in Ireland. In addition to Cheddar, other cheese varieties and butter, milk proteins, milk powder and casein are also produced. Glanbia's customers include globally active producers of foodstuffs and baby food, and regional companies in Europe, the Middle East, Africa and Asia.

A fully automated cheddaring plant with seven cheese towers was installed at the Ballyragget production facility in 2011. The transport of curd and residual milk from the cheddaring plant to the cheese towers is carried out by vacuum conveying lines. An air current carries the curd to the top of a ten metre tall cheese tower, where it falls under gravity into the tower. The curd mass is compressed by its own weight, forming a column lower in the tower. A vacuum is maintained in the tower to remove residual milk and air which may have been included in the compression process. At the base of the tower is a block chamber where the cheese is cut into 20 kilogram blocks, then packed and weighed.

Previously, conventional rotary lobe vacuum pumps were used to transport the curd and compress it into blocks. This vacuum system had the disadvantage that it could only pump down to 500 mbar. The pumps were equipped with frequency controlled motors, but the vacuum level could not be improved by increasing the speed due to technical limitations. The previous installation used a total of nine of these pumps, each requiring 15 kilowatts.

Busch's recommendation to the works manager Vincent Cleere was to install Busch Mink claw vacuum pumps, which offer considerable advantages over the previous solution.

Reproducible product quality
Depending on size, Mink claw vacuum pumps reach a vacuum of between 100 and 200 mbar, which is significantly higher than the level achieved by rotary lobe vacuum pumps. The average working vacuum at the Glanbia site is between 300 and 350 mbar, giving Mink claw vacuum pumps ample reserve to cover demand spikes. The pump motors have individual frequency control, enabling the vacuum level to be adjusted to suit the process.
The vacuum in the cheese towers is controlled precisely, maintaining constant curd density and thus improving product quality. Consistent product quality has also helped precision at the packing station, as the variation in cheese block weights has reduced.

Energy savings
Mink claw vacuum pumps deliver better performance than conventional rotary lobe vacuum pumps, but consume less power: the new pumps require only nine kilowatts each running at 50 Hz. The Mink vacuum pumps are operating at 40 Hz, so that they absorb still 6 kW power. As Vincent Cleere confirms: "The installation of Mink claw vacuum pumps has reduced our energy requirements for vacuum generation by 54 kW/h". As power costs €0.09 per kWh and the plant operates for 18 hours per day, 7 days a week and 45 weeks a year, this represents an annual cost saving of €27,557.

Complete reliability
Mink claw vacuum pumps have been operating at Glanbia since January 2014. To date no service interruptions or technical problems have been observed. One of the reasons for this reliability is the dry and contact-free working principle of Mink claw vacuum pumps: they require no working fluids for compression, and the internal moving parts do not make contact with each other. In addition, the noise level is considerably lower than with the previously installed rotary lobe vacuum pumps.

Minimal maintenance
The maintenance requirements of Mink claw vacuum pumps are minimal: the filters should be cleaned every week. Busch recommends a gear oil change every 20,000 operating hours, which at the Glanbia site corresponds to a service interval of over 5 years.

Works manager Vincent Cleere is certain that the decision to install Mink claw vacuum pumps in his Cheddar production lines was correct. The investment will repay itself within a very short time by energy savings alone.

His main benefis are:
- Saving money due to less power consumption
- Less intervention and costs due to almost maintenance-free operation and high reliability
- High quality level of the products due to the possibility for fine tuning the vacuum level   
  and pumping speed of the vacuum pumps regarding the really needed capacities

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