Efficient and safe Polysilicon production needs the right selection of process instrumentation

Correct monitoring of process conditions

Process Instrumentation

Answers for industry.

For a Polysilicon plant is it very important to produce highest output at minimum cost without compro-mising quality and safety. In order to guarantee most efficient production, the process needs to be continuously monitored and optimized. Therefore, information about particular process conditions needs to be continuously retrieved from different areas of the production facility. Data reports are generated from main process units such as a fluidized-bed furnace in the Trichlorosilane production and from supporting facilities such as a hydro-gen storage tank farm.

Selection of the correct instrumen-tation is very important for the efficiency of the entire plant. The optimized and extensive instru-mentation portfolio for the produc-tion of solar grade Polysilicon from

Information about temperatures, flows, levels, pressures and valve positions is of particular importance within this process.

Furthermore, there is an increasing demand for information about pro-cess condition and maintenance requirements. Reliable diagnostics and status reports are relevant prod-uct features that contribute to early recognition of actions to be taken and help therewith prevent damages, production downtimes and unneces-sary costs.

Siemens meets all measurement requirements throughout the produc-tion process – starting with the deliv-ery of the raw Silicon and finishing with the shipment of the high-purity Polysilicon.

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Process and Instrumentation Know-how

Polysilicon production for the Solar industry is a very demanding process.Aggressive media, extreme temperatures and pressure result in very high require-ments for the field devices to be in-stalled. The measurement technology used for individual applications depends on the respective situation. The most suitable measurement procedure can be often selected by taking a variety of pos-sibilities into account. For example, is ra-dar level measurement a more suitable technology than a differential pressure transmitter to measure the level of TCS? Which technology offers the best Cost of Ownership? What are the advantages and disadvantages of each technology?

Safety and Communication

Hazardous products can be found in every step of the Polysilicon production and safety is very important throughout the whole process. Siemens process instruments are available with all neces-sary approvals including ATEX (Ex) or SIL (up to SIL3). To communicate with the process control system, Siemens instru-

The complexity of applying the correct technology to the right application is of-ten underestimated. Siemens provides a comprehensive range of instruments and application experience to help customers select a suitable instrumentation concept for the following measuring devices

• Pressure Measurement• Temperature Measurement• Flow Measurement• Level Measurement• Weighing Technologies• Valve Positioners• Density Measurement

ments can have multiple options includ-ing the standard 4-20 mA with HART or intelligent bus communication such as PROFIBUS or Foundation Fieldbus.

The latest trend is to integrate instru-mentation direct into the control system. Siemens has developed SIMATIC modules,

To be able to provide the most suitable measurement for each application, Siemens has multiple technologies. For example, for flow meters, Electro-Mag-netic, Coriolis, Ultrasonic (in-line or clamp-on), orifice, or Vortex technology are available, depending on the applica-tion. For level measurement customers have a choice between Ultrasonic, Radar, Capacitance, Hydrostatic or Load cells. Many Siemens instruments were devel-oped to specifically suit the Polysilicon industry. For example, the SITRANS P DSIII pressure transmitter with a specially sin-tered gold diaphragm seal is most suit-able for Hydrogen applications.

that integrate the sensors of an in-strument directly into SIMATIC PCS 7. This is a unique and effective way to savecosts on hardware and to save time through more functionalities in the DCS during commissioning.