Methods for reacting compounds
View Patent ↗Shell and tube heat exchangers that include a baffle arrangement that improves the temperature profile and flow pattern throughout the exchanger and/or that are integral with a reaction vessel are disclosed. Methods for using the exchangers including methods that involve use of the exchanger and a reaction vessel to produce a reaction product gas containing trichlorosilane are also disclosed.
1. A method for reacting one or more compounds in a reactor feed gas and exchanging heat between the reactor feed gas and a reactor product gas, the reaction and heat exchange occurring in a reactor apparatus comprising a reaction vessel having a wall and a reaction chamber in which the reaction occurs, the apparatus further comprising a shell and tube heat exchanger for transferring heat between the reactor feed gas and reactor product gas, the shell and tube heat exchanger comprising a shell that is in fluid communication with the reaction chamber and a tube bundle within the shell with a chamber being formed between the tube bundle and the shell, the tube bundle extending through the wall into the reaction vessel, the bundle comprising a plurality of central tubes and a plurality of peripheral tubes between the central tubes and the shell, the tubes being in fluid communication with the reaction chamber, the method comprising:
introducing the reactor feed gas into the peripheral tubes and central tubes of the shell and tube heat exchanger;
discharging the reactor feed gas into the reaction vessel to cause one or more compounds of the reactor feed gas to react and to form the reactor product gas;
introducing the reactor product gas into the chamber formed between the tube bundle and the shell; and
discharging the reactor product gas from the shell;
wherein the reactor feed gas comprises silicon tetrachloride and hydrogen, the silicon tetrachloride reacting with hydrogen to produce the reactor product gas comprising trichlorosilane and hydrogen chloride in the reaction vessel.
2. The method as set forth in claim 1 further comprising:
introducing the trichlorosilane discharged from the shell and tube heat exchanger into a second reaction vessel to produce polycrystalline silicon and silicon tetrachloride by-product; and
introducing the silicon tetrachloride by-product into the peripheral and central tubes of the shell and tube heat exchanger.
3. The method as set forth in claim 2 wherein the trichlorosilane is purified prior to introduction into the second reaction vessel.
4. The method as set forth in claim 1 wherein the reactor feed gas is heated to at least about 600° C. before being discharged from the shell and tube heat exchanger.
5. The method as set forth in claim 1 wherein the reactor product gas is cooled to less than about 550° C. before discharged from the shell and tube heat exchanger.
6. A method for reacting one or more compounds in a reactor feed gas and exchanging heat between the reactor feed gas and a reactor product gas, the reaction and heat exchange occurring in a reactor apparatus comprising a reaction vessel having a wall and a reaction chamber in which the reaction occurs, the apparatus further comprising a shell and tube heat exchanger for transferring heat between the reactor feed gas and reactor product gas, the shell and tube heat exchanger comprising a shell that is in fluid communication with the reaction chamber and a tube bundle within the shell with a chamber being formed between the tube bundle and the shell, the tube bundle extending through the wall into the reaction vessel, the bundle comprising a plurality of central tubes and a plurality of peripheral tubes between the central tubes and the shell, the tubes being in fluid communication with the reaction chamber, a (1) terminal flange or (2) baffle within the reaction chamber for securing the portion of tubes that extends into the reaction chamber, and a reactor gas outlet and a product gas inlet, the reactor gas outlet being above the product gas inlet, the method comprising:
introducing the reactor feed gas into the peripheral tubes and central tubes of the shell and tube heat exchanger;
discharging the reactor feed gas into the reaction vessel to cause one or more compounds of the reactor feed gas to react and to form the reactor product gas;
introducing the reactor product gas into the chamber formed between the tube bundle and the shell; and
discharging the reactor product gas from the shell;
wherein the reactor feed gas comprises silicon tetrachloride and hydrogen, the silicon tetrachloride reacting with hydrogen to produce the reactor product gas comprising trichlorosilane and hydrogen chloride in the reaction vessel.
7. The method as set forth in claim 6 further comprising:
introducing the trichlorosilane discharged from the shell and tube heat exchanger into a second reaction vessel to produce polycrystalline silicon and silicon tetrachloride by-product; and
introducing the silicon tetrachloride by-product into the peripheral and central tubes of the shell and tube heat exchanger.
8. The method as set forth in claim 7 wherein the trichlorosilane is purified prior to introduction into the second reaction vessel.
9. The method as set forth in claim 6 wherein the reactor feed gas is heated to at least about 600° C. before being discharged from the shell and tube heat exchanger.
10. The method as set forth in claim 6 wherein the reactor product gas is cooled to less than about 550° C. before discharged from the shell and tube heat exchanger.