Development of model-based safety modules for a safety-related control system for the chemical industry
In the chemical industry, the majority of processes are carried out in pressure vessels. In case of improper plant operation, the hazard potential of a vessel to burst is very high. Hence, these processes need to be protected against an impermissible overpressure or negative pressure. For this purpose, PLC interlock systems and mechanical protective devices are used. These are intended to prevent incidents or to limit the possible damage in case of inevitable accidents.
Synergy of Economic and Green Safety – The forward-looking safety design!
If mechanical protective devices are used, the required mass flow rate to achieve a pressure reduction is either discharged via a pressure relief line to the ambient or fed into downstream collecting or retention systems. Currently, the ever more stringent emission limits and the shortage of resources leads to a situation where the release of hazardous substances and resources is no longer tolerable and economical. A reconsideration towards Zero Emission is necessary. Technical plants should be run at a safe state before a release threatens. In addition, round-robin calculations have shown that, according to the current state of the art, an oversizing of the mechanical protective devices from 300% to 500% is possible and this yields a further cost factor.
For these reasons, the industry is increasingly using PLC interlock systems to protect reactors. PLC interlock systems operate before a improper plant operation occurs by estimating the hazard potential via current process data and, if necessary, initiate countermeasures. For instance, an accumulation can be detected at an early stage by an indirect concentration measurement and the feed stream can then be switched off, so that the risk of a spontaneous pressure increase is no longer possible.
The complexity of designing PLC interlock systems is still very high, because for any individual process the reaction model as well as the implementation in the SSPS must be executed from the beginning. Fact is, that many chemical reactors are similar, so that a transfer of certain modules, such as the interconnection of inhibitors, can be unified.
This principle and its realization is the aim of the project SmartHIP. A modular kit is to be developed, which allows to parametrize a process safely and is applicable for different reactor types and processes at the same time.
PhD-Project in the scope of the CSE Research Areas: Economic Safety | Green Safety
Begin January 2017 / Project Duration 4 years