CN202808380U - Silicon tetrachloride hydrogenating device - Google Patents

Abstract

The utility model discloses a silicon tetrachloride hydrogenation device, comprising: a hydrogenation furnace, the hydrogenation furnace includes: a furnace body and a heating element, the heating element is used to heat the gas in the furnace body; a reaction material liquid evaporator, The reaction feed liquid evaporator is used to gasify silicon tetrachloride and mix the gasified silicon tetrachloride and hydrogen uniformly according to the set ratio and then pass it into the hydrogenation furnace through the gas pipeline; the tail gas heat exchange tube, The tail gas heat exchange tube is used to cool down the tail gas after reaction in the hydrogenation furnace; wherein, the length of the tail gas heat exchange tube is not less than 4m. The silicon tetrachloride hydrogenation device can control the temperature of the tail gas by setting the length of the tail gas heat exchange tube, so that the temperature of the tail gas flowing through the tail gas heat exchange tube can be quickly reduced to the set temperature range, thereby increasing the four The conversion rate of silicon chloride is high; at the same time, it avoids the occurrence of exhaust gas leakage accidents caused by the thermal expansion of gas pipelines due to excessive exhaust gas temperature, and has good safety.

Description

A kind of silicon tetrachloride hydrogenation device

technical field

The utility model relates to the technical field of polysilicon production technology, in particular to a silicon tetrachloride hydrogenation device.

Background technique

Polysilicon is the basic raw material of the electronics industry and solar photovoltaic industry. With the rapid development of information technology and solar photovoltaic industry, the demand for high-purity polysilicon is increasing rapidly, and polysilicon production has become a hot spot for investors in the industry.

A large amount of harmful by-product silicon tetrachloride is produced in the polysilicon production process, and the treatment of silicon tetrachloride has become a bottleneck problem in the production process of polysilicon production enterprises. The current method for treating silicon tetrachloride is mainly to convert it into trichlorosilane by hydrogenation technology, and the products after hydrogenation of silicon tetrachloride are trichlorosilane and hydrogen chloride. Among them, trichlorosilane is the raw material for polysilicon production, and silicon tetrachloride is converted into trichlorosilane to realize the recycling of silicon tetrachloride, which improves the utilization rate of raw materials and reduces production costs; the by-product hydrogen chloride is Important chemical raw materials increase the extra income of the enterprise.

In the prior art, when silicon tetrachloride is hydrogenated, hot hydrogen technology is generally used, and its vaporization and hydrogen are mixed evenly according to the set ratio and then reacted in the hydrogenation device. The reaction is carried out at high temperature, and the exhaust gas Cool and separate. The reaction equation of the hydrogenation reaction in the hydrogenation unit is:

The above reaction is a reversible reaction, so the tail gas after the reaction is a mixed gas of the four substances in the above reaction equation. The existing hydrogenation device cannot effectively cool the tail gas in time. At high temperature, the tail gas will undergo the reverse reaction of the above reaction, making the conversion rate of silicon tetrachloride low; at the same time, the high temperature will lead to gas pipeline interface Thermal expansion, thereby creating gaps, resulting in gas leakage, causing safety hazards.

Utility model content

In order to solve the above technical problems, the utility model provides a silicon tetrachloride hydrogenation device, the conversion rate of silicon tetrachloride of the device is high, and the safety is good.

In order to achieve the above object, the utility model provides the following technical solutions:

A silicon tetrachloride hydrogenation device, the device comprising:

A hydrogenation furnace, the hydrogenation furnace includes: a furnace body and a heating element, the heating element is used to heat the gas in the furnace body;

Reaction feed liquid evaporator, the reaction feed liquid evaporator is used to gasify silicon tetrachloride and mix the gasified silicon tetrachloride and hydrogen evenly according to the set ratio, and then pass it into the hydrogenation furnace through the gas pipeline ;

tail gas heat exchange tubes, the tail gas heat exchange tubes are used to cool down the tail gas reacted in the hydrogenation furnace;

Wherein, the length of the exhaust gas heat exchange tube is not less than 4m.

Preferably, in the above device, the length of the tail gas heat exchange tube is 4m-8m.

Preferably, in the above device, the tail gas heat exchange tube is a spiral tube or a zigzag tube.

Preferably, in the above-mentioned device, the hydrogenation furnace also includes:

An external heat preservation cover arranged inside the furnace body;

A graphite liner arranged inside the outer heat preservation cover;

Wherein, the heating element is arranged inside the graphite liner.

Preferably, in the above device, the heating power of the heating element is 300kW-500kW.

Preferably, in the above device, the exhaust gas heat exchange tube is a corrosion-resistant 316L stainless steel tube.

Preferably, in the above device, the heating element is a graphite heating element.

Preferably, in the above device, the tail gas heat exchange tube includes: an inner tube and an outer tube arranged outside the inner tube;

Wherein, there is cooling water flowing between the outer wall of the inner tube and the inner wall of the outer tube, and the exhaust gas is cooled by the cooling water.

Preferably, in the above device, when the hydrogenation reaction is carried out, the molar ratio of hydrogen to silicon tetrachloride in the hydrogenation furnace is 2-3.

It can be seen from the above technical scheme that the silicon tetrachloride hydrogenation device provided by the utility model includes: a hydrogenation furnace, and the hydrogenation furnace includes: a furnace body and a heating element, and the heating element is used to heat the gas in the furnace body; Reaction feed liquid evaporator, the reaction feed liquid evaporator is used to gasify silicon tetrachloride and mix the gasified silicon tetrachloride and hydrogen evenly according to the set ratio, and then pass it into the hydrogenation furnace through the gas pipeline ; Tail gas heat exchange tube, the tail gas heat exchange tube is used to cool down the tail gas after reaction in the hydrogenation furnace; wherein, the length of the tail gas heat exchange tube is not less than 4m.

The silicon tetrachloride hydrogenation device cools the tail gas after the reaction through the tail gas heat exchange tube, the length of the tail gas heat exchange tube is not less than 4m, and the temperature of the tail gas can be controlled by setting the length of the tail gas heat exchange tube , the temperature of the tail gas flowing through the tail gas heat exchange tube is rapidly reduced to a set temperature range, avoiding the reverse reaction of the hydrogenation reaction of the tail gas due to the excessively high tail gas temperature, and ensuring the conversion rate of silicon tetrachloride; and due to the The tail gas heat exchange tube can effectively reduce the temperature of the tail gas, so the heating power of the heating element of the hydrogenation device can be improved, and the temperature in the hydrogenation furnace can be increased, thereby improving the conversion rate of silicon tetrachloride; at the same time, because it can effectively treat The temperature of the tail gas is cooled, which avoids the occurrence of the tail gas leakage accident caused by the thermal expansion of the gas transmission pipeline due to the excessively high tail gas temperature, and has good safety.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are only some embodiments of the utility model, and those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is the structural representation of a kind of silicon tetrachloride hydrogenation device provided by the utility model.

Detailed ways

As mentioned in the background technology section, the existing hydrogenation device cannot effectively cool the tail gas in time. At high temperature, the tail gas will undergo the reverse reaction of the above reaction, making the conversion rate of silicon tetrachloride low; at the same time, high temperature will This will lead to thermal expansion at the interface of the gas pipeline, resulting in gaps, resulting in gas leakage and potential safety hazards.

The temperature required for the reaction in the hydrogenation furnace is generally 1200°C, and the temperature of the reacted tail gas discharged from the bottom of the hydrogenation furnace is generally 700°C-900°C. The length of the tail gas heat exchange tube of the existing silicon tetrachloride hydrogenation device is about 3m, and its first port communicates with the exhaust port of the base of the hydrogenation furnace, and the first port is welded or integrated with the base Formed structure, no gaps will be generated due to thermal expansion; but its second port needs to be connected to other parts of the hydrogenation device through an interface flange. If the exhaust gas cannot be effectively cooled, the interface flange will be thermally expanded, thereby As a result, gaps appear in the connection between the second port and other components, resulting in exhaust gas leakage.

The tail gas heat exchanger generally lowers the temperature of the tail gas conveyed between the inner pipes and the outer pipes through high-temperature cooling water between the inner pipes and the outer pipes. Although the temperature of the exhaust gas can be quickly lowered by reducing the temperature of the cooling water, when the lower temperature cooling water cools the exhaust gas, the volume difference of the lower temperature cooling water changes greatly, and a large amount of water vapor will be generated, which may cause Probably the exhaust gas heat exchange tube burst. Therefore, the above method is generally not used. In the existing similar devices, the tail gas heat exchange tube length is generally short, less than 4m, and the temperature of the tail gas cooled by the tail gas heat exchanger after reaching the reaction feed liquid evaporator can still reach about 400 degrees Celsius, which cannot effectively reduce the hydrogenation device. The temperature of the tail gas after the reaction may easily cause thermal expansion or deformation at the flange connecting the reaction feed liquid evaporator and the tail gas heat exchange tube, resulting in tail gas leakage.

In order to solve the problem that the exhaust gas leaks easily at the joint between the tail gas heat exchange tube and the reaction feed liquid evaporator, and at the same time in order to improve the conversion rate of silicon tetrachloride, the inventors have found through long-term practice and research that increasing the length of the tail gas heat exchange tube increases the The heat exchange area between the high-temperature cooling water and the tail gas in the large jacket can reduce the temperature of the tail gas reaching the connection between the reaction feed liquid evaporator and the tail gas heat exchange tube, which can effectively solve the problem of the length of the connecting flange between the reaction feed liquid evaporator and the tail gas heat exchange tube. If the problem of exhaust gas leakage occurs, it can also realize the rapid cooling of the exhaust gas and reduce the occurrence of the reverse reaction of silicon tetrachloride hydrogenation. When the length of the tail gas heat exchange tube is not less than 4m, the temperature of the tail gas can be effectively reduced to below 250 degrees Celsius, avoiding the leakage of the tail gas caused by thermal expansion; moreover, avoiding the hydrogenation reaction of the tail gas due to the excessively high tail gas temperature The reverse reaction ensures the conversion rate of silicon tetrachloride; at the same time, because the tail gas heat exchange tube can effectively reduce the temperature of the tail gas, it can increase the heating power of the heating element of the hydrogenation device and increase the temperature in the hydrogenation furnace, thereby Improve the conversion rate of silicon tetrachloride.

On the basis of above-mentioned research, the utility model provides a kind of silicon tetrachloride hydrogenation device, and this device comprises:

A hydrogenation furnace, the hydrogenation furnace includes: a furnace body and a heating element, the heating element is used to heat the gas in the furnace body;

Reaction feed liquid evaporator, the reaction feed liquid evaporator is used to gasify silicon tetrachloride and mix the gasified silicon tetrachloride and hydrogen evenly according to the set ratio, and then pass it into the hydrogenation furnace through the gas pipeline ;

tail gas heat exchange tubes, the tail gas heat exchange tubes are used to cool down the tail gas reacted in the hydrogenation furnace;

Wherein, the length of the exhaust gas heat exchange tube is not less than 4m.

The silicon tetrachloride hydrogenation device provided by the embodiment of the utility model cools the tail gas after the reaction through the tail gas heat exchange tube. The length of the tail gas heat exchange tube is not less than 4m. By setting the tail gas heat exchange tube The length controls the temperature of the tail gas, so that the temperature of the tail gas flowing through the tail gas heat exchange tube is quickly reduced to the set temperature range, avoiding the reverse reaction of the hydrogenation reaction of the tail gas due to the excessively high tail gas temperature, and ensuring the conversion of silicon tetrachloride rate; and because the tail gas heat exchange tube can effectively reduce the temperature of the tail gas, so the heating power of the heating element of the hydrogenation device can be improved, and the temperature in the hydrogenation furnace can be increased, thereby improving the conversion rate of silicon tetrachloride; at the same time, Because the exhaust gas can be effectively cooled, the exhaust gas leakage accidents caused by the thermal expansion of the gas pipeline caused by the excessively high exhaust gas temperature are avoided, and the safety is good.

The above is the core idea of the present application. The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the present invention. Examples, not all examples. Based on the embodiments of the present utility model, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.

In the following description, a lot of specific details have been set forth in order to fully understand the utility model, but the utility model can also be implemented in other ways that are different from those described here, and those skilled in the art can do so without violating the connotation of the utility model. Under the circumstances, similar promotion is done, so the utility model is not limited by the specific embodiments disclosed below.

Secondly, the utility model is described in detail in conjunction with the schematic diagram. When describing the embodiment of the utility model in detail, for the convenience of explanation, the section view showing the structure of the device will not be partially enlarged according to the general scale, and the schematic diagram is only an example, which is here The protection scope of the utility model should not be limited. In addition, the three-dimensional space dimensions of length, width and height should be included in actual production.

Based on the above thought, the embodiment of the utility model provides a silicon tetrachloride hydrogenation device, with reference to Fig. 1, comprising:

A hydrogenation furnace, the hydrogenation furnace includes: a furnace body; a heating element 15 arranged inside the furnace body. Wherein, the furnace body is composed of a bell jar 12 and a base 17 , and the heating element 15 is arranged on the base 17 . During the hydrogenation reaction, the reaction gas (hydrogen and gaseous silicon tetrachloride) mixed uniformly according to the set ratio enters the bell jar 12 through the feed port 11 at the top of the bell jar 12, and is heated by the heating element 15 to carry out the hydrogenation reaction.

In order to prevent the bell jar 12 from being too high in temperature, an outer heat preservation cover 13 is arranged between the bell jar 12 and the heating element 15, and an air vent is provided between the outer heat preservation cover 13 and the base 17, and from the feed inlet 11 The reaction gas passed through the vent enters into the outer heat preservation cover 13, and after being heated by the heating element 15, a hydrogenation reaction occurs. The outer heat preservation cover 13 protects the temperature of the bell jar 12 from being too high and also plays a role of heat preservation, so that the internal temperature thereof is kept at the set reaction temperature.

Simultaneously, in order to make the thermal field in the outer heat preservation cover 12 uniform, between the heating element 15 and the outer heat preservation cover 12, the ink liner 14 is a cylindrical structure with an octagonal cross section. Through the scattering of heat, the temperature inside the outer heat preservation cover 13 is made uniform. The two are a pair, which are distributed in the graphite liner 14 in an I-shape, that is, the paired two heating elements 15 are parallel to each other. The hydrogenation device in this embodiment has 18 pairs of heating elements distributed in the graphite liner 14 .

Wherein, the heating element 15 is a graphite heating element, which has stable chemical properties and does not chemically react with the reaction gas in the hydrogenation furnace. The heating element 15 is connected to an external power source through an electrode 16. The electrode 16 is a copper electrode with good electrical conductivity, and the surface of the copper electrode is plated with metallic silver to protect the copper electrode. After an electric field is applied to the heating element 15 by an external power source, the heating element 15 generates heat to heat the reaction gas in the hydrogenation furnace. The heating power of the heating element 15 can be controlled by controlling the output intensity of the external power supply, thereby controlling the reaction temperature value in the hydrogenation furnace.

The hydrogenation device also includes: a tail gas heat exchange tube for cooling the reacted tail gas; and a reaction material liquid evaporator for providing reaction gas to the hydrogenation furnace.

The first port of the tail gas heat exchange tube communicates with the hydrogenation furnace through the air hole on the base 17 . The reacted tail gas enters the tail gas heat exchange tube through the air guide hole provided on the base 17, and is cooled in the tail gas heat exchange tube. The exhaust gas heat exchange tube is composed of an inner tube 22 and an outer tube 23 arranged outside the inner tube 22 . A high-temperature cooling water inlet 24 is provided on the side wall of the outer tube 23 close to the second port of the exhaust gas heat exchange tube, and the high-temperature cooling water enters the tube walls of the inner tube 22 and the outer tube 23 through the high-temperature cooling water inlet 24 Between the gaps, the high-temperature cooling water passes through the gaps in the pipe wall, then passes through the cooling water pipe (not shown in the figure) arranged inside the base 17, and then exits the hydrogenation device through the high-temperature cooling water outlet 21.

After the reaction material liquid evaporator heats and vaporizes silicon tetrachloride, gaseous silicon tetrachloride and hydrogen are uniformly mixed according to a set ratio and then passed into the hydrogenation furnace. Specifically, the configuration of the reaction feed liquid evaporator includes: a condensed water outlet 37 , a hydrogen inlet 36 , a silicon tetrachloride inlet 35 , a water vapor inlet 34 , and a reaction gas outlet 33 .

The side wall of the reaction feed liquid evaporator is a hollow structure, and when working, liquid silicon tetrachloride at normal temperature is injected into the first part of the reaction feed liquid evaporator through the silicon tetrachloride inlet 35. chamber, and through the hydrogen inlet 36 to the first chamber at a set gas flow rate; at the same time, through the water vapor inlet 34 into the side wall of the reaction feed liquid evaporator into high-temperature water vapor , heat the liquid silicon tetrachloride inside to vaporize it, mix it with hydrogen evenly, and then enter the hydrogenation furnace through a gas pipeline (not shown in the figure) connected to the reaction gas feed port 11. In the side wall of the reaction feed liquid evaporator, the condensed water formed by the cooling of the water vapor is discharged from the hydrogenation device through the condensed water outlet 37 .

In the uniformly mixed reaction gas, the molar ratio of hydrogen to silicon tetrachloride is 2-3, so that the volume content of hydrogen in the reaction gas is greater than the volume content of gaseous silicon tetrachloride, which promotes the reaction in the hydrogenation furnace to generate trichlorohydrogen The direction of silicon is carried out, increasing the conversion rate of silicon tetrachloride.

The reaction feed liquid evaporator also includes a second chamber, the second chamber is provided with a tail gas inlet 31 and a tail gas outlet 32, and the second port of the tail gas heat exchange tube is connected to the tail gas inlet 31 through a flange 311. connected, the tail gas in the tail gas heat exchange tube passes through the second chamber and then enters the tail gas collection and separation device through a gas pipeline (not shown in the figure) communicated with the tail gas outlet 32 . Wherein, the gas transmission pipeline and the exhaust gas collection and separation device are not shown in the figure. When the tail gas flows through the second chamber, the silicon tetrachloride in the first chamber can be auxiliary heated to accelerate the gasification of the silicon tetrachloride.

When cooling the exhaust gas, high-temperature cooling water is generally used instead of lower-temperature cooling water to avoid problems such as bursting of gas pipelines. Therefore, in order to effectively reduce the temperature of the exhaust gas, it can be realized by increasing the length of the exhaust gas heat exchange tube. Within a certain range, the temperature of the exhaust gas is inversely proportional to the length of the exhaust gas heat exchange tube, that is, the longer the exhaust gas heat exchange tube is, the lower the temperature of the exhaust gas after cooling.

The tail gas heat exchange tube of the hydrogenation device described in this embodiment is not less than 4m, and compared with the existing tail gas heat exchange tube of about 3m, it can reduce the temperature of the tail gas more significantly, effectively cool down the tail gas, and avoid excessive temperature The reverse reaction leading to the hydrogenation reaction of the tail gas ensures the conversion rate of silicon tetrachloride.

At the same time, the hydrogenation device can apply greater power to the heating element (the heating power of the heating element is 300kW-500kW), increasing the reaction temperature in the hydrogenation furnace to 1200°C-1300°C, increasing the The reaction speed of the reaction gas and the conversion rate of silicon tetrachloride, although the temperature of the tail gas discharged at this time is correspondingly increased, but because the tail gas heat exchange tube can effectively reduce the temperature of the tail gas, avoid the hydrogenation of the tail gas caused by the high temperature The reverse reaction of the reaction improves the conversion rate of silicon tetrachloride on the whole.

Moreover, when the length of the tail gas heat exchange tube is not less than 4m, the temperature of the tail gas can be effectively reduced to below 250 degrees Celsius, and the leakage of the tail gas caused by thermal expansion can be avoided. As in this embodiment, gaps between the exhaust gas heat exchange tubes and the exhaust gas inlet 31 due to thermal expansion of the flange 311 are avoided, thereby avoiding the occurrence of exhaust gas leakage and higher safety.

Preferably, the length of the tail gas heat exchange tube described in this embodiment is 4m-8m, and the length of the tail gas heat exchange tube can reduce the temperature of the tail gas to 150°C-250°C, on the one hand, it can avoid hydrogenation due to excessively high tail gas temperature The reverse reaction of the reaction, so as to ensure the conversion rate of silicon tetrachloride; on the other hand, make the trichlorosilane in the cooled tail gas be in a gas state, so as to avoid the condensation of trichlorosilane into liquid and adhere to the tail gas due to the low temperature The inner wall of the heat exchange tube.

In this embodiment, the cooling tail gas is used to assist the heating of liquid silicon tetrachloride in order to make full use of energy. The collection and separation device is connected, and only steam is used to heat silicon tetrachloride.

The exhaust gas heat exchange tubes and gas pipelines are made of high temperature resistant and corrosion resistant 316L stainless steel tubes. In order to reduce the space occupied by the hydrogenation unit, the tail gas heat exchange tube is designed as a zigzag pipe or a spiral pipe.

It should be noted that the conversion rate of silicon tetrachloride mentioned in the utility model refers to the conversion rate of tetrachloride tube into trichlorosilane.

It can be seen from the above description that the silicon tetrachloride hydrogenation device described in this embodiment can effectively cool down the tail gas after the reaction, improve the conversion rate of silicon tetrachloride, and at the same time ensure the safety of production.

The above description of the disclosed embodiments enables those skilled in the art to realize or use the utility model. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims (8)

1. a hydrogenation of silicon tetrachloride device is characterized in that, comprising:

Hydrogenation furnace, described hydrogenation furnace comprises: body of heater and heating element, described heating element are used for gas in the body of heater is heated;

Reaction feed liquid vaporizer, described reaction feed liquid vaporizer are used for the silicon tetrachloride gasification and the silicon tetrachloride after will gasify and hydrogen mix afterwards according to preset proportion and passes into described hydrogenation furnace by gas pipe line;

Tail gas heat transfer tube, described tail gas heat transfer tube are used for the reacted tail gas of described hydrogenation furnace is cooled;

Wherein, the length of described tail gas heat transfer tube is not less than 4m.

2. device according to claim 1 is characterized in that, the length of described tail gas heat transfer tube is 4m-8m.

3. device according to claim 1 is characterized in that, described tail gas heat transfer tube is spirality pipe or fold-line-shaped pipeline.

4. device according to claim 1 is characterized in that, described hydrogenation furnace also comprises:

Be arranged on the outer stay-warm case of described body of heater inside;

Be arranged on the graphite inner bag of outer stay-warm case inside;

Wherein, described heating element is arranged on the inside of described graphite inner bag.

5. device according to claim 1 is characterized in that, the heating power of described heating element is 300kW-500kW.

6. device according to claim 1 is characterized in that, described tail gas heat transfer tube is corrosion resistant 316L stainless steel tube.

7. device according to claim 1 is characterized in that, described heating element is graphite heater.

8. device according to claim 1 is characterized in that, described tail gas heat transfer tube comprises: inner tube and be arranged on the outer outer tube of described inner tube;

Wherein, have mobile water coolant between the outer wall of described inner tube and the inwall of described outer tube, by described water coolant described tail gas is cooled.