Application of an Early Warning Detection System to batch and semi-batch polymerization processes

The EWDS is an electronic device designed to recognize, on-line and well in advance, anomalous process conditions in chemical reactors that can lead to runaway reactions. The EWDS consists of hardware and software parts: In the hardware part we have: PT resistance thermometers to measure reactor and jacket temperatures; a data acquisition unit; a supply unit that complies with industrial safety standards and a PC equipped with a special data acquisition card. The software part is used to save and elaborate data, to show the results on line and to provide warning and alarm signals. For the bench scale reactor experiments the EWDS performance has been satisfactory. The algorithm, in fact, has detected the runaway events in advance without producing false alarms. For the industrial experiments two different algorithms have been used. Algorithm n.1 was able to distinguish between runaway and non-runaway situations, because it is mainly focused on the dynamics inside the reactor. Algorithm n.2, instead, produced false alarms during the manual opening of the jacket valve by the operator. The results that I have presented refer to the first versions of the algorithms. In the future a new version of the EWDS algorithm will be tested. This version uses only the reactor temperature and it does not use derivatives. So the calculation will be simpler compared to the first versions.