Process Automation How Modernized Process Automation Boosts Efficiency and Safety for Food Production
Dairy and cheese production is by no means a business of hillbilly herdsmen: To ensure sustained maximum quality and productivity, big dairies regularly invest large sums in the modernization of their production plants — using the latest automation technology and process control systems.
A very popular cheese in Finland is called Oltermanni and has been produced in the Haapavesi factory of the dairy corporation Valio since 1993. The factory which is located 500 km to the north of the capital, Helsinki, was commissioned in 1965. Today, Haapavesi employs 175 people and processes more than 200 million liters of milk per year. Haapavesi claims to produce “The cream of the crop” — a challenging claim. Supplies are, nevertheless, adequate: The factory is located in the center of the productive milk region of Pohjanmaa (Ostrobothnia). Fresh raw milk is available from over one thousand farms in the immediate vicinity. Haapavesi is one of seven cheese dairies of Valio and produces all the Oltermanni cheese — around 20,000 tons per year. Further products are demineralized whey powders for use in the food industry and as feed for calves. The capacity for the complete portfolio has been expanded several times over the past years, with regular investment planned for the future. This is the only way to ensure a constantly high product quality and maximum productivity of the multi-layered dairy processes.
Automated for Efficiency
Processing of around one million liters of milk daily requires efficient interacting processes throughout the factory. From acceptance of the raw milk, through its inspection and preparation and the various dairy processes to packaging, storage and dispatch. Valio has achieved this for many years with a high degree of automation and a good deal of technology and process control systems from Siemens.
An important stage in cheese production is souring: A high-quality souring agent is the basis of unvarying excellent taste and homogeneity of the cheese. Currently 10,000 liters of souring agent are required per day. Valio therefore recently invested five million euros in a new souring agent center which was commissioned in April 2009. The aim of this investment was to ensure quality and to create optimum conditions for expected further expansions.
Modernized for the Future
The production plants for Oltermanni cheese were originally equipped with Simatic S5 series controllers. Even though they were still reliably performing their tasks, they had gradually approached the end of their lifetime. Therefore, the controllers had to be replaced to enable future productivity and quality. In a modernization project over several years, almost every part of the factory was equipped with modern and sustainable programmable controllers of the Simatic S7-400 series.
The original process control system was also from Siemens and, according to Petri Moisio, technical expert at Haapavesi, well-proven over many years. The company was therefore looking for a sustainable Siemens solution for the supervisory level too and finally decided on the Simatic PCS 7 process control system (version 7.0).
The comprehensive retrofit started in the powder department with the drying tower and the twin steamer in 2003 and 2004. Goods incoming and joint processing were renewed over the following years. The new souring agent center followed in 2008 and 2009. The second drying tower for powder and stork is currently being modernized.
The overall system will, once completed, feature several field-related process stations or their subordinate automation systems. The stations for stork and souring agent are implemented with redundant Simatic S7-400H automation systems to ensure permanent availability. At the control level, there are three redundant server pairs that supply twelve operator stations (OS clients) with process data. Three engineering stations (ES) are used for continuous system maintenance and engineering. The systems of the process control level are linked with Industrial Ethernet, whereas Profibus DP is standard field- bus throughout the factory. This minimizes the wiring outlay and makes expansions and changes easier to implement in the future. All sub-processes are controlled, monitored, documented and archived around the clock.