Streamlining process operations with an online batching system

A leading Australian food manufacturer is utilising an automation and control system from Citect to improve efficiency and productivity.

Two of the main requirements in designing the system were to interface the plant floor with the MRP system, and remove the paper trail and data entry errors – common requirements of many food and beverage manufacturers in Australia and around the world.

The factory itself consists of five manufacturing lines, operating 24 hours a day. Each line consists of a mixer, a forming line, ovens, secondary processing and packaging. There are also numerous associated processes: yeast, ferment, volume and invert manufacture, cookers, creaming machines, ingredient preparation and storage, truck receivals, packaging facilities, and an automated warehouse.

Citect worked with the manufacturer to design an automation and control system that integrated the Business Planning and Control System (BPCS), SQLServer database, the Manufacturing Resource Planning (MRP) software and almost 100 individual Allen-Bradley Programmable Logic Controller – PLC-5s and SLC-500s. The system facilitates the flow of information from the BPCS to the factory floor and back, without the need to re-enter data at any point.

It provides for the fast and accurate flow of production planning information, the execution of production activities and the recording of materials used during manufacture. The BPCS system contains shop order requests, inventory control, and accounting details. Shop order requests are transferred to the recipe database for production, while batch statistics are transferred from the recipe database to the BPCS for inventory control and accounting purposes.

The SQLServer is used to store the recipes, which include not only the batch parameters, but also the sequential control for the PLC program. The entire recipe is stored in tables that, once downloaded to the PLC, interface with the sequence engine to provide full sequential control of the process.

Recipes may be created online via the mixing procedure design utility that allows non-technical personnel to design and error check mixing recipes. This provides flexibilityand advanced error checking prior to download. New recipes can be created or existing recipes altered without affecting production, and any existing process or ingredient can be incorporated into the new or altered recipe.

Existing recipes can also be easily modified to account for fluctuations in environment or ingredients, or to test new products. As the recipes are created in the database and downloaded as required to the PLC, a potentially limitless number of recipes can exist for any mixer. Multiple batches are possible in the sequence engine, permitting multiple runs of the same recipe sequence until the shop order is complete. This requires the number of batches for a given recipe to be calculated in the recipe database from the shop order request and downloaded.

Batch statistics, including detailed and accurate data such as temperature fluctuations, are totalled through the sequence and reported to the automation and control system at the completion of a given batch for reporting to the BPCS. These statistics are compared to test results and product quality in order to improve product consistency and increase output.

Should a system such as the recipe database or BPCS fail, the other systems can continue operating until a change of recipes is required because all sequence control is in the PLC.

The redundancy in the CitectSCADA automation and control system allows operator intervention at any station, thus removing dependence on a single PC for system integrity.

Stephen Flannigan is the global director of CitectSCADA.

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