Ceilcote Trichlorosilane Process vent scrubbing

Description

The production of trichlorosilane (TCS) is a critical step in the production of polysilica for the solar cell industry. TCS production creates a variety of waste gas streams, including TCS, dichlorosiliane (DCS), Silicon tetrachloride (STC), and HCl. These waste gases must be removed at high efficiency prior to venting process gases to the environment. Specialized pollution control solutions must be designed to accommodate the high levels of hydrogen, heat release, and product handling Issues that are associated with silicic acid by‐products of the waste gases.

Innovative Aspect

A major polysilica production facility in China sought a solution to economically and reliably remove
silane and acid wastes from their process vent gas system. The process gas stream contained large amounts of H2 in addition to contaminants and nitrogen. Ceilcote APC was able to provide three multi‐train scrubber systems containing a combination of spray towers, eductor venturis and packed towers. Redundant components provide automatic changeover during maintenance periods. This arrangement allowed for 100% system availability and very high removal efficiencies of silane and HCl gases. Wastewater streams were minimized to reduce water consumption and treatment costs.

The composition of exhaust gases from TCS production can include various chlorosilanes, silicon tetrachloride, and hydrogen gas. Understanding the hydrolysis and interaction of these chemicals along with associated heat generation, reaction byproducts, and proper pH control is critical to maintaining continuous operation of the pollution abatement equipment.

Benefits

Ceilcote’s broad range of scrubber designs, along with our extensive chemical engineering experience, enables us to select the right equipment combination to insure maximum system availability when dealing with complex silicon chemistry. Our eductor venturis (EVS Series) provide high liquid to gas ratios and can be designed in multiple stages to achieve high-efficiency removal and minimize potential fouling. If additional removal is required, our packed tower scrubbers can be used for final exhaust polishing.

Complete system design, including upstream knock-out drums to deal with process liquid surges and downstream seal pots to prevent atmospheric air backflow, can be provided.