Ceramic Valve Solutions for Organosilicon Cyclone Separation

Unreacted materials from monomer synthesis are recovered for reuse after undergoing a three-stage separation process

Main Industry: Polysilicon Manufacturing

Operating Conditions

Primary and secondary cyclone separators are installed internally or externally on the fluidized-bed reactor to recover fine catalyst particles. Most of the recovered material is returned to the fluidized bed, while a small portion is discharged into a fines collection tank or waste-fines tank. The medium temperature is below 250°C and consists of a methyl chloride gas mixture, silicon powder, catalyst-grade copper powder, and other components. This high-temperature gas-solid two-phase service is one of the most severely abrasive conditions in organosilicon production

Medium Details: Silicon powder, methylchlorosilane mixture, methyl chloride, high-boiling chlorosilanes, and a small amount of hydrogen chloride

Special Operating Conditions

Abrasion and Corrosion

• High-velocity dust-laden gas continuously erodes the sealing surfaces. Silicon powder has a Mohs hardness of 7 and is therefore highly abrasive
• The medium contains organochlorosilanes and trace amounts of HCl. Small quantities of moisture entering the system cause further hydrolysis, generating additional HCl and intensifying corrosion
• Powder readily settles and accumulates on internal supports, valve cavities, and other retention areas
• Frequent intermittent process operation, combined with alternating high-temperature cycles, can cause fatigue damage

Keywords: High Hardness | Powder Media

Process Pain Points and Key Opportunities

Keywords: High Cost | Short Service Life | Frequent Maintenance | Production Accidents | Product Quality Stability

Why Choose Ceramic Valves?

Conclusion: Specialized ceramic materials successfully overcome the severe high-velocity erosion and abrasion encountered in these valve applications. These valves have already been successfully applied at critical points in synthesis and cold-hydrogenation systems operated by many of the world’s top ten polysilicon manufacturers

Case Study

End Users

• Zhejiang Xinan Momentive Performance Materials Co., Ltd., China, since 2012
• Inner Mongolia Hengyecheng Silicone Co., Ltd., China, since 2017
• Shandong Dongyue Silicone Material Co., Ltd., China, since 2012
• Jiangxi Bluestar Xinghuo Silicones Co., Ltd., China, since 2014
• Tangshan Sanyou Silicon Industry Co., Ltd., China, since 2018

In polysilicon trichlorosilane synthesis, the principal feedstock is silicon powder, which is highly abrasive. Many metal hard-seat materials have a hardness similar to that of silicon powder, making it extremely difficult to improve valve wear resistance through metallic materials alone. Due to these material limitations, the service life of conventional metal hard-seated valves has remained difficult to extend

To reduce costs, domestic producers attempted to replace imported hard-seated valves with locally manufactured alternatives. However, when assessed over a two-year operating cycle, this localization approach did not generate meaningful savings. Ceramic valves provide a considerably longer service life than metal hard-seated valves. Based on total life-cycle costs, each ceramic valve reduces expenditure by more than 25% compared with a domestic metal hard-seated valve over the same operating period. Further savings from reduced shutdown maintenance, production interruptions, and labor have not yet been included

Conclusion

Actual Service Life: Control valves: 3 years; on/off valves: ≥5 years

Commonly Used Products