A brief discussion on trichlorosilane process
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Trichlorosilane production process flow. Trichlorosilane synthesis. Unload the silicon powder to the rotating disc, transport it to the silicon powder warehouse with gas through the pipeline, then add the silicon powder dryer, pass through the disc feeder and measure, and then add it to the trichlorosilane synthesis furnace. In the trichlorosilane synthesis furnace, the temperature is controlled at 80-310°C, and silicon powder and hydrogen chloride react to generate trichlorosilane and silicon tetrachloride. The generated trichlorosilane and silicon tetrachloride gases pass through a settler, cyclone separator and bag filter to remove dust and high chlorosilane. After being water-cooled, they are pressurized by a diaphragm compressor and then condensed into a liquid using -35°C refrigerant. The non-condensable gas enters the tail gas elution tower through the liquid seal tank, and is discharged after acid and alkali elution to meet the standards. Trichlorosilane separation. The mixture of trichlorosilane and silicon tetrachloride (trichlorosilane content is 80-85%) enters the pressurized tower and is continuously purified and separated by two towers. By controlling a certain reflux ratio, a product with a trichlorosilane content of more than 99% and a by-product with a silicon tetrachloride content of more than 95% is finally obtained. The dusty exhaust gas is mainly nitrogen that transports silicon powder. The silicon powder is first recovered through bag dust removal, and then washed with water. The washing wastewater is recycled after precipitation, and the tail gas is discharged into the atmosphere after being washed. The dust removal rate of the bag dust collector is 99%, the washing dust removal rate is calculated as 50%, the total dust removal efficiency reaches 99.5%, and the discharge reaches the standard after treatment. Non-condensable gas mainly contains protective gas, and the rest also contains a small amount of chlorosilane, hydrogen chloride, etc. After low-temperature condensation, the remaining non-condensable gas is sent to the exhaust gas treatment device. The chlorosilane series quickly decomposes into silicic acid and hydrogen chloride when exposed to water. The hydrogen chloride gas is first absorbed by the dilute hydrochloric acid cycle and recycled into concentrated hydrochloric acid. The trace part is absorbed and reacted by the alkali liquid. The main component of waste gas is nitrogen. After being washed and treated, the waste gas is discharged through the workshop exhaust pipe to meet the standards. Under the premise of meeting the requirements, try to choose equipment with low speed and low noise. ； At the same time, set up an independent soundproof room for the blower, separated from the floor where it is located, to reduce the noise caused by vibration. ； Install silencers on the air inlet pipes of air compressors, blowers, pumps, etc., and set up soundproof operating rooms to reduce indoor noise pollution and improve the working environment for workers. The chimney is set to a sufficient height to ensure that the flue gas emissions comply with * * The requirements of the secondary standards of the "Comprehensive Emission Standards for Air Pollutants". This post was last edited by LHY8771 on 2009-2-10 13:34 ]
The author believes that the synthesis of HCL in the trichlorosilane synthesis unit is not mentioned. At the same time, the recycled silicon powder is extremely active and can easily cause an explosion. At present, major domestic manufacturers producing trichlorosilane such as Tangshan * * factories, all use HCL recovery systems.
I would like to ask why the high activity of silica powder can easily cause explosions? Please let me know if there are any preventive measures or control indicators.
The explosion here needs to be determined according to the specific situation. . The activity of recycling silicon powder is very high. But if there is a small amount of open space, there will only be small sparks. The temperature is just higher. Because this type of silicon powder is discharged from the synthesis system, it contains trichlorosilane to some extent, and trichlorosilane easily hydrolyzes with moisture in the air to produce hydrogen, which generates heat. Hydrogen has a wide range of explosive limits. So it may cause an explosion. But basically there will be no explosion. Otherwise, among the many trichlorosilane manufacturers, I have never heard of any one causing an explosion due to the high activity of silicon powder. Are you right? Safety is important, but the key is prevention!
Of course, active silicon powder has high activity, but the activity of ferrosilicon block must be low.
The title should be: A brief discussion on the production process of trichlorosilane
Thank you for sharing, but these are just introductions. I wonder if there are some more specific introductions?
To be honest, there is still a difference from actual production. The actual production temperature and other processes and process flow control are different for each company, so the cost is also different, and the removal of impurities is not involved.
It seems like it was just mentioned in general, is there anything specific? For example, how can we increase the synthesis rate of trichlorosilane?