The treatment of diabetes mellitus was revolutionised by insulin. For more than a quarter of a century, this life-saving medication has been produced industrially with the help of genetically manipulated bacteria and yeasts. The requirements placed on the applied process technology are strict. The plants not only have to meet stringent standards and legal rules with regard to hygiene and cleaning; they must also operate with a high level of precision and reliability. The Zeta Group, based near Graz in Austria, is considered a specialist for tailor-made process solutions for these sterile and aseptic applications. This technology supplier to the biotech and pharmaceutical industries designs, manufactures and installs customised solutions for renowned companies worldwide. One example of this is a turnkey automation solution for a fermentation plant for insulin production, which was put into operation in Russia at the end of 2018. The scope of this project was considerable: 18 tanks, 30 control cabinets and the entire measurement, control and regulating technology had to be designed, installed, tested and certified. A total of 20 valve islands from Bürkert (Type 8647 Airline SP), which control about 600 valve functions as part of the fermentation process, are responsible for electropneumatic automation in combination with the ET 200SP distributed I/O system.
There were several reasons for this choice, as Andreas Rauscheder, project engineer at Zeta, explains: “Even at the planning stage, we were able to recognise the advantages of the new valve island generation compared to standard pneumatic solutions. Hardware and software integration into our world of automation from Siemens facilitated installation, start-up and parameterisation. Thanks to the option of fully parameterising the valve islands using an HSP file in the Siemens TIA portal, we managed to save a considerable amount of time and money.”
Another of the system’s decisive advantages is the external valve shutdown (EVS). A potential-free contact in the supply power circuit is used here to cut off the load voltage of the valves. “It enables us to safely shut down individual valve modules according to the Machinery Directive and EN 13849 or the corresponding SIL requirements.” By using the EVS function, individual safe emergency stop circuits can be implemented on the valve island with little effort. In the event of an external shutdown, internal communication on the valve island remains unaffected and indicates the EVS function both on the integrated LC display and via Profinet to the higher control level. “We were also able to reduce the time and effort needed; if an emergency stop pushbutton is actuated by a member of staff, the valve island at the corresponding plant section goes into a safe state immediately and the control centre is also informed of this”, says a delighted Rauscheder.
High reliability and availability
In addition to displaying and forwarding the EVS function, the standard integrated diagnostics offer further options that help to increase operational reliability. An integrated pressure measurement module monitors the supply pressure and forwards warning and error messages to the control level in the event of deviations from the specified values. Switching cycle counters can also be used independently of each other for the pilot valves and the downstream actuators. Moreover, the switching position of the process valve can be shown directly on the display of the valve island by means of an integrated software function. “Pilot and process valves can therefore also be identified visually on site for greater clarity”, Rauscheder adds. Broken wires, short circuits and open valve outputs are likewise detected, displayed directly on the valve island in plain text and as symbols and forwarded via the communication interface of the ET 200SP.
To increase pneumatic availability, Zeta also opted for the integrated P channel shut-off. This allows the valve to be changed during operation without having to depressurise the rest of the valve island. The non-return valves, too, are integrated in the valve island’s exhaust air ducts and additionally ensure that the process actuators are switched safely without any adverse effects. “Because the valve islands have a modular design, we were able to relocate certain functions to another control cabinet at a later date. We only had to replace the corresponding modules and change the threaded connection”, Rauscheder comments.
Since the fermentation plant is intended for the Russian market, the Eurasian conformity mark of the Eurasian Customs Union was also required for the valve islands. Zeta was pleasantly surprised at the speed with which the fluid experts reacted and presented the relevant documents. Yet cooperation proved to be just as rewarding in other respects. “Delivery deadlines were strictly adhered to, all advice was spot on and minor software adjustments that had to be made were performed quickly”, the project manager reports. Hence, nothing stands in the way of continued cooperation for future projects.
As intelligent electropneumatic automation systems, valve islands are not only used widely in the pharmaceutical industry. Very similar tasks and requirements exist, for example, in the cosmetics industry, food and beverages or the water treatment sector.