“To sterilize the 148 storage, sterilization and butter ageing tanks, steam is injected over a longer period of time,” says Florian Lexhaller, head engineer at the dairy. Large quantities of steam are also used for the process control technology. On average the dairy utilizes 7 to 8 tons of steam per hour, with up to 10 tons during peak periods. Because the production of steam consumes large amounts of energy, and given that the steam boilers were getting on in years, management saw significant savings potential in the area of energy consumption and CO2 emissions.
Gas turbine for energy and steam production
Instead of drawing energy from the public grid for the plant technology and the production of steam, the idea was for the dairy to generate its own electricity and produce steam from residual heat. The advantage of this solution is that energy production can be designed more efficiently. Since the plant uses both electricity and steam, this solution leads to a more reliable energy supply system while significantly reducing the risk of downtime. Berchtesgadener Land worked together with a plant engineering partner to carry-out the retrofit while the plant was still in operation. The 1.6 MW gas turbine from Kawasaki, which was connected to the dairy’s network in 2016, produces around half of the plant’s electricity needs. The residual heat from the turbine is then diverted to a recovery boiler that generates 5 tons of steam per hour. The steam production is supplemented by two peak-load boilers from Bosch, each of which can generate 10 tons of steam per hour at a pressure of 10 bar.
Low-temperature heating for further efficiency improvements
As if that were not enough, the residual heat is then used for a warm water system containing a 200,000-liter buffer tank. This so-called low-temperature heating system will eventually be used for all of the buildings so that building heating systems can be deinstalled. The CIP systems and the milk heating system for curd cheese will also be fed by the low-temperature heating system. A heating network for the entire company has already been installed. Using this cascade of heat exchangers, the 530 °C turbine exhaust will be cooled down to 50 °C before it leaves the exhaust pipe.
More reliable supply of energy and steam
With a peak capacity of 25 tons of steam per hour, the dairy is positioned to produce twice the amount of steam than it currently needs. The aim was to be prepared for increased capacity in the future while ensuring there is a constant supply. If a steam boiler or even the gas turbine goes down, the plant continues to be supplied with steam. Electricity can then be drawn from the public grid on short notice to keep the plant operational. Because the dairy runs completely on steam heat, a continuous supply is essential. Without steam, production comes to a halt. Even if bottlenecks in the public grid occur, the gas turbine still generates enough electricity to keep important systems for cooling the milk and the products up and running, thus providing another way to significantly reduce the risk of production downtime.
The location in Piding offered highly favorable conditions for the realization of the energy center with a gas turbine. A high-pressure gas line that transports natural gas at a pressure of 70 bar is located just a short distance from Berchtesgadener Land Dairy. A reduction station then reduces the pressure to 16 bar for the gas turbine. The natural gas is supplied in gas form by Erdgas Südbayern. The location offered the ideal conditions for the construction of the energy center from a space standpoint as well. Since the company was able to sufficiently dimension the production halls, there is still enough space to expand the gas power plant. The installation of a second turbine is also conceivable, which would help the company take a further step toward energy self-sufficiency, although there are currently no concrete plans for an expansion.
Measurement technology provides additional downtime protection
Florian Lexhaller understands the importance of selecting the right measurement technology when it comes to ensuring that the process control system for the milk production, the cleaning systems, the energy center and the dairy’s energy distribution network all operate smoothly. To do this he delved deep into the matter, becoming intimately familiar with the measurement instruments used in the plant. New measurement instruments are regularly inspected with test applications. In addition, the equipment specifications list standard types, which means the spare instrument inventory can be kept lean. “When we install a new system, we provide our partners exact specifications that outline what the instrumentation should look like,” reports Lexhaller. “We are satisfied with the quality and reliability of the instruments from Endress+Hauser,” says the chief engineer who adds that “the instruments have proven their worth, especially when it comes to reliability.” When the energy center was built, instruments were installed that had never been used in the plant before, such as vortex-based flowmeters and steam computers. Here Lexhaller once again placed his complete trust in the advice and instrumentation layout provided by the Endress+Hauser field engineer who has been responsible for Berchtesgadener Land Dairy for more than 10 years. After four years of operating the energy center, he summed up his experience with a wink of the eye and said: “The stuff simply works.”
High degree of automation in the energy center
To optimize the resource efficiency of the energy center, the automation technology in the plant plays an important role. The system can react quickly to changes in the operating conditions and automatically adapts its performance. Through connection of the systems, measurement values and key energy indicators are continuously analyzed and applied by the energy management system. One of the key components here is the heat computer from Endress+Hauser, which features a Modbus TCP/IP interface. Lexhaller emphasizes that “Endress+Hauser is one of the few providers that offer this type of transmission link, which allows us to send the energy values direct to a central SPS and analyze them without extensive cabling work.
Summary: well-aligned system with a high degree of efficiency
The energy center is an important building block in Berchtesgadener Land’s sustainability strategy. To ensure that the system runs stably and smoothly, and to be able to achieve an efficiency of more than 90 percent, the individual components must be intertwined and well-aligned to one another. The instrumentation from Endress+Hauser plays an important role in ensuring the quality of the dairy products and the reliability of the systems. With the installation of the gas turbine, the dairy is also taking on the role of trailblazer when it comes to decentralized energy provisioning. Given that the system can be operated efficiently and the availability ensured through a redundant design, these arguments will certainly lead many other companies to one day follow the example of the Berchtesgadener Land Dairies.