Polysilicon Reduction gas separation
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Polysilicon – Reduction gas separation. The volume fractions of the main components in the polysilicon exhaust gases are as follows: HCl 30%； H2 64.2% ； SIHCl3 5.4% ； 0.2% for the rest. All polysilicon exhaust gases are recyclable products or reusable raw materials. Effective treatment of exhaust gases can not only improve the utilization rate of raw materials but also reduce the emission of waste substances. To manage exhaust gases effectively, it is necessary to select appropriate process flows and technical conditions based on the characteristics, composition, pressure, and other properties of the exhaust gases. By taking advantage of the differences in boiling points, solubility, and adsorption capacity on the adsorbent among these components, they can be completely separated from one another. Our company has developed the following two process technologies for treating polysilicon off-gases: Separation methods: 1. Condensation adsorption method – The polysilicon off-gases are fed into a condensation separation system, where the pressurized syngas is cooled; chlorosilanes and hydrogen chloride are separated from it. Subsequently, hydrogen chloride and hydrogen are separated through distillation, with the hydrogen being sent to an adsorption purification system to produce highly pure purified hydrogen. The condensation separation system consists of a refrigeration compressor unit, a distillation tower, and pumps, while the adsorption purification system is made up of an adsorption tower, a heater, and a cooler. 2. Pressure swing adsorption method: A pressure swing adsorption system consists of an adsorption tower, a heat exchanger, and a buffer tank. At any given moment, one adsorption tower is in the adsorption state, while the others are in the regeneration state. Hydrogen, trichlorosilane, and hydrogen chloride are separated based on the differences in their adsorption capabilities on the surface of the adsorbent. The adsorbent is regenerated by heating and depressurizing. Regeneration is complete, and the adsorption tower once again has the capability to treat trichlorosilane exhaust gas and produce hydrogen. After this series of processes, the adsorption tower completes a full \"adsorption-regeneration\" cycle, preparing itself for the next adsorption cycle. By alternating between adsorption and regeneration in each adsorption tower, continuous separation and purification of gases can be achieved.
The volume fraction of HCl is a bit high; I’m not aware of the specific control conditions in the reduction furnace
How does pressure swing adsorption separate the three substances? Please explain in detail, OP. Thank you
The reduced exhaust gas undergoes filtration, dust removal, and condensation to separate its components
Sir, isn’t the content of silicon tetrachloride in those exhaust gases you mentioned too low? Additionally, if the hydrogen content is only in the high 60s, the reactions inside the furnace don’t proceed well, and the viewing glass tends to become foggy very easily. I hope you can give me some advice. Thank you
The components of LZ should be the synthesis off-gases of trichlorosilane
The HCL content is extremely high! It’s mainly H2 and SIHCL3!
LZ isn’t involved in polysilicon production, right? The HCL content shouldn’t exceed 10%, and the exhaust gases should contain a few percent of STC
That is due to a low-temperature reaction that results in the formation of silicone oil. In addition, large amounts of amorphous silicon and silicon-chlorine compounds form on the furnace walls. 5# Sad Elf
It would be better for exhaust gas recovery to use the materials within the system as absorbents.
I’m a newcomer and there are many things I don’t understand. For example, how large must the adsorption capacity of the adsorbent be? And what happens to the gas trapped on the adsorbent after adsorption?
It should be the components of TCS synthesized exhaust gas
7# anndy1971 activated carbon
What can the exhaust gas outlet temperature be controlled at?