Some years ago, WACKER Burghausen decided to revamp a polymerization reactor and its measurement and control system, which had been in use for batch production of dispersions since 1972. An important factor was the plant's extremely confined surroundings. Several similar reactors are installed in minimum space, side by side and one above the other over four different floors. The new reactor and its new field instrumentation and control technology had to be seamlessly integrated ? spatially and functionally ? in this tightknit arrangement, and the new installation was not allowed to impair the operation of the other reactors. Fieldbus technology, and in particular PROFIBUS PA, can be very helpful to met these requirements.
The new plant contains approx. 80 multivendor field devices in PROFIBUS PA design, which are positioned in Ex Zone 1, distributed among 8 PA segments and connected by PA cable to assigned DP/PA link components. Additional devices such as inductive contacts are connected by conventional means using 'valve boxes' (these are PA bus nodes).
The links are nodes on PROFIBUS DP, together with the S7-400 controller which acts as the master. Other DP lines extend from the master to various DP devices (Simocode and converter) and to the ET 200M distributed I/O system.
The plant bus (Industrial Ethernet) with two redundant servers and a gateway connection to the old plant lies above PROFIBUS DP. At an even higher level lies the terminal bus with the operator stations, the engineering system and the batch server.
Conventional wiring was used only for a number of simple devices, for devices which are not yet available in PA design, and for safety circuits (e.g. maximum pressure).
The expectations placed on PROFIBUS PA with regard to its benefits, particularly for the revamping of plant sections in difficult spatial conditions, have been met in full.
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