Systems and methods of producing trichlorosilane
View Patent ↗The present invention is directed to systems and methods of synthesizing trichlorosilane. The disclosed systems and methods can involve increasing the concentration of the solids in the slurry to recover or separate the volatilized metal salts and reduce the obstructions created by the solidification of the metal salts in downstream operations of the during trichlorosilane synthesis. Rather than heating to raise the temperature to vaporize chlorosilane compounds, and subsequently condensing the volatilized chlorosilane compounds, the present invention can involve increasing the solids concentration in the slurry stream by utilizing a non-condensable gas, such as hydrogen, to volatilize the chlorosilane components, which can consequently promote evaporative conditions that can reduce the slurry temperature. The lower slurry temperature results in a lower volatility of the metal salts, which reduces the likelihood of carryover to downstream unit operations.
1. A system for synthesizing trichlorosilane comprising:
a source of silicon tetrachloride;
a source of hydrogen;
a reactor fluidly connected to the source of silicon tetrachloride and to the source of hydrogen, the reactor having a reactor outlet;
a quench column having a crude vapor inlet, a second vapor inlet, a crude vapor product outlet, and a residue outlet, the crude vapor inlet fluidly connected downstream from the reactor outlet; and
a stripper column having an overhead liquid inlet, a contact gas inlet, and an overhead vapor outlet, the overhead liquid inlet fluidly connected downstream from the residue outlet of the quench column, and the overhead vapor outlet fluidly connected to the second vapor inlet of the quench column.
2. The system of claim 1 , further comprising a condenser having a condenser inlet, a condensate outlet, and a condenser outlet, the condenser inlet fluidly connected downstream from the crude vapor product outlet, the condenser outlet fluidly connected upstream of a trichlorosilane, dichlorosilane, silicon tetrachloride separation train, and the condensate outlet fluidly connected upstream of an overhead condensate inlet of the quench column.
3. The system of claim 2 , further comprising a residue pump having a pump inlet and a pump outlet, the pump inlet fluidly connected downstream from the residue outlet of the quench column, and the pump outlet fluidly connected upstream of the overhead liquid inlet of the stripper column, and upstream of a residue recycle inlet of the quench column.
4. The system of claim 3 , further comprising a hydrogen recovery system having a recovered hydrogen outlet, the hydrogen recovery system fluidly connected downstream from the condenser outlet.
5. The system of claim 4 , wherein the contact gas inlet of the stripper column is fluidly connected downstream from the recovered hydrogen outlet.
6. The system of claim 1 , further comprising a source of a contact gas stream fluidly connected upstream of the contact gas inlet of the stripper column, the contact gas stream comprising hydrogen.
7. The system of claim 1 , further comprising a heat exchanger having a first fluid side and a second fluid side in thermal communication with the first fluid side, the first fluid side fluidly connecting at least one of the source of hydrogen and the source of silicon tetrachloride to the reactor, and the second fluid side fluidly connecting the reactor outlet to the crude vapor inlet of the quench column.