New process control system in pharmaceutical plant

An automated weighing and process control system, supplied by Procon Engineering, is playing a pivotal role at the Ernest Jackson Devon facility, which produces medicated pastilles and lozenges

An automated weighing and process control system, supplied by Procon Engineering, is playing a pivotal role at the Ernest Jackson Devon facility.

The new PLC based system has replaced a Defiant Weighing Batchmaker DOS based system, fitted by the company over 12 years ago.

With a heritage dating back to 1817, Ernest Jackson, now part of the Cadbury Trebor Bassett Group, has over 180 years experience and expertise in developing, manufacturing and marketing medicated pastilles and lozenges.

The company manufactures over 200 different products and its portfolio includes many leading brands including household names such as Victory V, Throaties, Hacks and Potters Traditional Pastilles.

To meet growing demand for a wider range of products and increased traceability legislation, the company had recognised they needed to automate the batching process .

The DOS system had become unsupportable and the manual manufacturing process was somewhat laborious, relying totally on the operator to ensure batches were collated and processed correctly.

However they were mindful of the fact that any changes would be disruptive to the plant and would preferably need to take place during a scheduled shut-down.

Other considerations included the need to operate an effective automatic CIP (Clean-in-Place) programme.

Following site visits and consultation, Procon were able to give an objective view on how best to upgrade the system within the required time frame.

This included reviewing the existing equipment to avoid changing equipment for change sake.

Procon advised that the existing load cells on the premix vessel and holding tanks, together with the EP11 local amplifiers, were in good condition and did not need replacing.

This would not only save money but also reduce installation time.

The new system is centred on a Siemens S7-300 PLC to oversee the plant control and TP270 HMI (Human Machine Interface), which acts as the primary operator interface.

An EP50 Proweigher batching instrument controls the batching process into the premix vessel via a Profibus interface with the PLC.

The EP50 is a highly versatile process controller which can handle a number of process variables including weight, temperature, pressure and flow.

The EP50 has direct control over the material feed valves to provide accurate batch control while the PLC manages all other plant I/O for the control of the evaporator and final mixing and holding vessels.

All the batches follow the same basic routine and the system automatically controls the manufacture of product to a preset recipe as selected by the operator.

Bulk ingredients are charged by weight into the premix vessel from bulk storage hoppers, mobile IBCs or via the lean-flow vacuum transfer system which is then agitated and heated as defined in the recipe.

When the premix is complete the product is transferred under vacuum to the evaporator vessel where again the mix is agitated and heated.

The product is finally transferred to one of two holding tanks where further manual additions are made to complete the recipe.

The system can track up to three recipes which may be running simultaneously in the premix vessel, evaporator, and one of the holding tanks.

Although the batching process is effectively fully automatic, the operator can be prompted to carry out manual acknowledgements where required by a particular recipe.

At critical points the operator can also be asked to enter a user-specific ID before the next process step can take place.

All events are logged and printed to a final batch report with relevant parameters including ingredient name, target weight, actual weight, time, date and confirmation of any manual ingredients that were added.

All manual acknowledgement events are also logged.

The HMI displays plant mimics and batch status information, live weights and temperatures, status and diagnostic information.

Password protected access through the operator interface is available at three levels for the Operator, Supervisor and Engineering.

Operator level allows only current recipes to be selected and run, with control of the usual start, stop and alarm handling functions.

Supervisor level allows access to additional functions such as recipe entry and editing of current recipes.

Engineering level allows further access to all the fundamental plant parameters such as alarm and limit settings.

Manual control of the plant can also be implemented through the operator interface, allowing individual material feed valves and mixers to be turned on or off.

In the event of any critical alarm condition controlled system shutdown can take place.

Close cooperation between Procon and Ernest Jackson ensured the main part of the project was carried out during the summer shutdown without any plant disruption.

Following the installation and commissioning, productivity has improved and Jacksons now have full batch traceability.

The system allows management to track yield throughout the process and this can be linked in with their stock reporting system.

A comprehensive range of system integrity checks give forward warning of any potential problems, allowing them to make ordered risk assessments.

Back to top