Safety aspects of Schmid Polysilicon Production SPP

Each single process step in our plant Schmid Polysilicon Production SPP operates with very low pressure. Pressure in the hydrochlorination ranges at about 11bar, monosilane production works with 4bar, and the deposition process works with less than two bar.

Basic safety of the plant is guaranteed by the Process Control System (PCS) via interlocks, alarm systems and an automatic switch off processes. The next level of safety is provided by the Safety Integrity Control, which, in case of failure of the PLS, leads the plant into a secure condition. Last safety level are bursting discs and safety valves which ease in so-called Blow-Down Vessels. The Safety Integrity Control system including control mechanisms and actuators adheres to the SIL standard (Safety integrity level standard).

Safety Integrity Functions are certified and tested on a regular basis by TÜV.

Measures for answering safety risks are calculated via the HAZOP method. The results lead to above mentioned measures, as well as further design requirements and operation instructions for the plant.