A WALK AT THE NEW PLANT
Reception and storage of raw milk
The new plant is located in North Attica near the Acharnes area. The raw milk is transported in special isothermal-stainless steel tanks and is offloaded in the raw milk reception and storage department. The automatic reception line is designed to ensure that milk losses are minimized and CIP chemicals are reduced when the time comes to clean the lines. After being examined by the Quality Control department, the milk is cooled and stored in the storage silos. It is possible to receive milk in one silo while sending milk from another silo to pasteurization, and washing a third silo at the same time, all with absolute safety. The above processes can be performed with any sequence and combination.
The milk is then transferred to the pasteurization sector. For this procedure, an automatic prefabricated GalaxiAS™ pasteurization unit was installed to pasteurize either the milk or the yogurt mixture. The pasteurization section also includes a bactofuge, separator, fully automatic milk standardizer, homogenizer, deaerator, and holder. All the processes are fully customizable and automated, depending on the final product for which the pasteurized milk is intended.
The pasteurization process is fully automated using Siemens S7-1500 and ET-200SP controllers and SINAMICS G120C drives, all connected via a PROFINET network. The proprietary software from AS HELLAS, monitors the correct operation and activates all the necessary routines to ensure the quality of the final product. Records of all pasteurization variables (temperatures, diversion valve activation, differential pressures on the heat exchanger sections) are collected in the central control system Siemens WinCC V7.5 of the plant.
From the pasteurizer, a valve cluster with automatic Mixproof valves is distributing the pasteurized milk (that is intended for fresh milk production) to storage tanks and to the milk filling line. The storage tanks are insulated to maintain a constant product temperature. The central automation ensures that the milk is delivered safely to the filling machine and that the filling line is properly and securely cleaned through the CIP at the end of the production day.
Mixing and mixture preparation
This section includes tanks for storing and mixing pasteurized milk. A key parameter in modern dairies, is the ability to produce many smaller batches to meet the individual needs and preferences of consumers. In this section, automatic valve clusters give great flexibility and control in storage, processing, and cleaning.
Here too there is the flexibility of performing various tasks simultaneously. The plant can store milk from pasteurization in a tank and at the same time, it can:
- Send a mixture from a tank to the pasteurization of yogurt mixture, AND
- Send a mixture to the dessert section, AND
- Send a mixture to a traditional yogurt tank, AND
- Clean a fourth tank.
As in the Reception sector, here too, the above cases can be safely realized with any possible combination.
This sector of the new plant includes both the Production Department of Strained and European (Set) Yogurt, as well as the Production Department of Traditional Yogurt and Sour Milk. The pasteurized milk intended for the fermentation products is led to the incubators for the fermentation process. With the help of special “good” micro-organisms, lactose is converted to lactic acid, and the result is this particular sour taste characteristic of all fermentation products.
Pipe networks and automatic pneumatic valves make sure yogurt is sent to different packaging destinations as planned. At the automatic valve cluster for the circulation of the incoming milk and the final product, care has been taken to accommodate future expansion with valves and tanks.
Cleaning in Place (CIP)
Particular care and attention have been given to the process of cleaning the production lines. Cleaning and sanitation of the processing plant are among the most critical aspects of food processing, as it ensures consumer health and safety. Proper cleaning is essential to produce high-quality products with longer shelf life. Cleaning in Place is not only a key process in the production cycle but also a significant part of the operating cost.
A typical CIP cleaning process requires large amounts of water, chemicals, and energy. A dairy unit is likely to use 13% of its total energy in the CIP process. Therefore AS HELLAS’s approach to the CIP process has a dual purpose. To ensure the most efficient cleaning of production lines, taking into account all the parameters of dairy production, as well as the best and most efficient use of resources. A fully automated CentrASIP™ unit with Siemens S7-1500 controllers and Comfort panels was installed for the cleaning and sanitation of all the circuits of the factory. The CIP unit can be expanded in the future. The extensive know-how of AS Hellas and its long experience in the construction of automatic CIP systems, ensure efficient use, low water consumption, and the best use of energy and detergent resources.
The Plant’s Automation:
For the process control system, STAMOU S.A. wanted an automation solution that is advanced and energy efficient. The system monitors and controls the entire production process using Siemens S7-1500 and ET-200SP controllers.
The entire factory is controlled and monitored centrally by the production control room. The central SCADA system (Supervisory Control and Data Acquisition) Siemens WinCC V7.5, guarantees the quality of the final product as it controls all production processes and all cleaning operations. It also records and stores production information, with full traceability in the past. The central SCADA system integrates (through visual display of the entire installation) the following:
- All procedures related to raw milk.
- All the functions and processes of the factory.
- The CIP operation and the central dosing of chemicals.
At the same time it has the ability to create customized production reports with the production data, as well as a complete history of operation and production processes.
THE AUTOMATION CONFIGURATION
1. The purpose of the automated production process is to control the following subsystems:
- Reception and storage of raw milk.
- Pasteurization and standardization of the final product.
- Fresh Milk filling.
- Production of sour milk, strained, set and traditional yogurt.
- The CIP (Cleaning in Place) of the above units.
2. Features of the automation system
- Remote access via VPN for faster service.
- Generation of alarms in case of failure or malfunction.
- Sending alarms via SMS (optional).
- Recording and graphical display of all variables (temperature, pressure, etc.).
- Recording of operations of all operators individually (optional).
- Operator access level.
- Interlocks to avoid operator mistakes.
- Ability to communicate with external systems for the exchange of information.
- Ability to exchange data with ERP.
- Interface with the recipe program (optional).
- Report generation.
3. Technical characteristics
- Latest generation PLC of the SIEMENS S7 1500 series.
- Software for human-machine interface (HMI) SIEMENS WinCC.
- More than 1.500 control points.
- Control of VFDs (Variable Frequency Drives) with Profinet.
- Stainless steel MCCs (motors control center) & CPs (control panels) around the plant.