Profiting from fieldbus flexibility

Field automation technology has helped Avecia upgrade its new dual stream facility at Billingham, UK. Siemens Automation outlines how it came about.

At Billingham in the UK, Avecia Biologics is involved in the contract manufacture of active pharmaceutical ingredients produced by a process of fermentation, separation and purification. Since 1996, activity has focused exclusively on developing bioprocesses for human therapeutic proteins. The site has two principal manufacturing facilities: a dual-stream facility with 100 and 1000-litre fermentation capability (ABC1000); and a new dual-stream facility with 5000-litre fermentation capability (ABC5000).

control and monitoring

The ABC5000 facility deploys a process control system (PCS) - the SIMATIC PCS 7 - which is in the Siemens automation network Totally Integrated Automation. One PCS 7 controller pair carries out control and monitoring for the two separation and two purification suites, as well as the buffer preparation and refold suites in the facility. When batches are completed, there is control, sequencing and valve routing for six CIP skids that service these suites. This PCS 7 also controls the distribution of three water systems - two purified water and one water-for-injection (WFI) - and carries out the sanitisation sequences. Additionally, it oversees other utility services such as process drainage, biowaste, chilled water and air generation.

A second PCS 7 controller pair regulates and monitors the HVAC system within the building, which comprises 15 air-handling units, plus ancillary heating/cooling services and, following a recent project, now includes duty control and services control for the site's steam boilers.

Profibus DP is also used as the networking standard in the two fermentation suites, linking ten S7-300 controllers together and to the WinCC operator interface system.

The adoption of Profibus on the Avecia site at Billingham has brought the company several benefits.

'The ABC5000 facility was a new build and very different from anything that we had on site previously. We therefore didn't have any baseline expectations of improvements that Profibus might bring, but we wanted to make the best use of available technology,' explains Avecia process control systems engineer Gareth Maloney.

'From an engineering perspective, the use of a single network infrastructure for our PCS system - DP for main control hardware and PA for instrumentation - has reduced our overall cabling/networking requirements. Instrument cabinet sizes are much smaller and control circuits are simplified. We were also able to order certain skid-mounted operations that required only a single PA cable to be connected which made all the instrumentation live to the PCS.'

fault identification

Maloney adds: 'Although we aren't using an asset management tool at present, on-line instrument diagnostics has meant that more faults or maintenance requirements can be identified via operator graphics, which can be followed up using software tools at a central location without the need to enter cleanrooms or remove instruments from their locations. Engineers from instrument suppliers can also utilise the same network with their PC-based tools, so fault rectification and instrument replacement/optimisation is simpler and quicker because the saved configuration of previous devices can be downloaded from a computer rather than having to configure the instrument by hand. This ultimately means greater availability.'

Distributed automation solutions on the basis of open fieldbuses are now the standard in many production and process engineering industries. Only fieldbuses permit full use of the functional advantages of digital communication such as improved resolution of measured values, diagnostics facilities and remote parameterisation.

rapid response

Modern process applications cover not only continuous or batch control, but also discrete applications such as filling, bottling, labelling and packaging, where drives, fast digital IO and pneumatic valves are needed. Profibus is the first fieldbus system that covers both types of application with identical communications services.

The advantages of distributed field automation with Profibus PA include: totally integrated modular system from sensor up to management level; problem free interchanging of field devices from different vendors; connection of transmitters, valves and actuators to the network; ease of installation; and low commissioning and servicing costs. The benefits result in: lower hardware costs; shorter start-up times; problem free maintenance; low cost software engineering; and higher operational reliability.

One of the biggest advantages to Avecia relates to the improved flexibility offered by Profibus enabling the company to respond rapidly to changing market conditions. 'We are a contract manufacturing organisation and need to be able to modify our plant to customer requirements in relatively short timescales,' says Maloney. 'Profibus allows us to deploy new instruments rapidly with minimum cabling/infrastructure changes.'