CN218422701U - Reaction system for producing silicon nitride - Google Patents

Abstract

The utility model provides a reaction system of production silicon nitride, include: a reaction tower and a heat transfer assembly; the heat transfer assembly is arranged on the reaction tower; a micro-interface unit is arranged in the reaction tower, the micro-interface unit comprises a micro-interface generator and an expansion pipe positioned above the micro-interface generator, and the bottom of the expansion pipe is communicated with the micro-interface generator; the top of the expansion pipe is connected with a silicon tetrachloride conveying pipeline, and the micro-interface generator is connected with a liquid ammonia conveying pipeline. The utility model discloses a reaction system of production silicon nitride can realize solvent-free production, low in production cost, and the silicon nitride powder particle diameter of production is even, and the fineness is high.

Description

Reaction system for producing silicon nitride

Technical Field

The utility model relates to a silicon nitride preparation technical field particularly, relates to a reaction system of production silicon nitride.

Background

Silicon nitride is an inorganic substance with the chemical formula of Si ₃ N ₄ It is an important structural ceramic material, has high hardness, lubricity, is an atomic crystal, is wear-resistant and is oxidation-resistant at high temperature. It can resist cold and hot impact, and can be heated to above 1000 deg.C in air, and can be rapidly cooled and then rapidly heated, and can not be broken. Because of such excellent properties, silicon nitride ceramics are often used to manufacture mechanical components such as bearings, turbine blades, mechanical seal rings, permanent molds, and the like.

In the prior art, silicon nitride powder is prepared by a low-temperature liquid phase method, namely, liquid ammonia is adopted to react with an organic solution of silicon tetrachloride at the low temperature of-40 ℃ to obtain intermediate product silicon imine and a byproduct ammonium chloride, and the silicon nitride powder is obtained by filtering, washing and heat treatment. The reaction process requires controlled heat release to maintain the system temperature at-40 deg.c and the reactor pressure at micro positive pressure.

However, the prior art processes are facing the following problems:

firstly, the method comprises the following steps: the reaction has violent heat release, and the instantaneous temperature rise can reach 10-20 ℃, so that the reaction temperature in the tower is difficult to be stably controlled;

secondly, the method comprises the following steps: although the added organic solvent can dilute the silicon tetrachloride and control the reaction speed, the organic solvent is added, so that the required purer product is difficult to separate in subsequent operation, and the cost is increased;

thirdly, the steps of: the reaction conversion rate is extremely high, the reaction speed is also very high, but the particle size control is difficult to achieve in the prior art, one is that the particle size distribution is not uniform enough, the other is that the particle size is not fine enough, the micron scale level is difficult to achieve, and the continuous production of the whole flow cannot be realized.

In view of this, the utility model discloses it is special.

SUMMERY OF THE UTILITY MODEL

A first object of the utility model is to provide a reaction system of production silicon nitride, this reaction system have realized the production silicon nitride of no solvent, have overcome the exothermic violent and particle diameter uncontrollable problem of reaction among the prior art simultaneously.

The second objective of the present invention is to provide a method using the above reaction system, which is simple in operation and can produce silicon nitride with uniform and fine particle size.

In order to realize the above purpose of the utility model, the following technical scheme is adopted:

the utility model provides a reaction system of production silicon nitride, include: a reaction tower and a heat transfer assembly; the heat transfer assembly is arranged on the reaction tower; a micro-interface unit is arranged in the reaction tower, the micro-interface unit comprises a micro-interface generator and an expansion pipe positioned above the micro-interface generator, and the bottom of the expansion pipe is communicated with the micro-interface generator; the top of the expansion pipe is connected with a silicon tetrachloride conveying pipeline, and the micro-interface generator is connected with a liquid ammonia conveying pipeline.

In the prior art, the heat release in the production of silicon nitride is severe, and the instant temperature rise can reach 10-20 ℃, so that the reaction temperature in the tower is difficult to be stably controlled, and meanwhile, in order to control the reaction speed, an organic solvent is required to be used, but the organic solvent is difficult to separate in the subsequent process, and the cost is increased in the separation process; in addition, the silicon nitride produced by the prior art has uneven particle size distribution and is not fine enough, which affects the quality of the product.

In order to solve the technical problem, the utility model provides a reaction system for producing silicon nitride, which can disperse and crush raw materials into micro-droplets of micron level by arranging a micro interface unit, thereby improving the mass transfer area between two phases of oil and water, and further playing a role in strengthening the reaction; the heat released by the reaction can be removed in time by arranging the heat transfer component, so that the control of the reaction temperature in the tower is realized, and conditions are provided for the solvent-free production of silicon nitride.

Preferably, a circulating pipeline is arranged outside the reaction tower, an inlet of the circulating pipeline is connected with the side wall of the reaction tower, and an outlet of the circulating pipeline is communicated with the top of the expansion pipe; and a heat exchanger is arranged on the circulating pipeline.

Preferably, the heat transfer assembly comprises a coil and an outer jacket, the coil is coiled on the inner wall of the reaction tower, and the outer jacket is sleeved on the outer wall of the reaction tower.

Preferably, a discharging device is arranged at the bottom of the reaction tower; the discharger is funnel-shaped, and a reaction product in the reaction tower flows out through the discharger. The reaction product is solid-state silicon imine crystal, and the funnel-shaped discharging device can prevent the outlet from being blocked.

Preferably, the diameter of the expansion pipe is gradually increased from top to bottom, and the bottom of the expansion pipe is in contact with the top wall of the micro-interface generator. This allows for thorough mixing of the fluids at the point where the fluid reynolds number is higher, the turbulence is more vigorous, and the mixing is better.

The utility model discloses a reaction system need not to use the solvent at the in-process of production silicon nitride to avoid the separation difficult problem in the follow-up processing, the existing purity that does benefit to the guarantee result can practice thrift the cost again. In addition, the heat transfer assembly consisting of the coil pipe and the outer jacket is arranged on the reaction tower, so that reaction heat can be transferred out in time, the stability of the reaction temperature in the tower is guaranteed, the system breakdown caused by the reaction heat release is effectively prevented, and the reaction speed is not changed into the toggle for manufacturing the silicon nitride any more due to the real-time heat transfer, so that the condition is created for realizing solvent-free production, the product purity is greatly improved, the ammonium chloride byproduct can be more simply purified in the follow-up process, and the collection and reutilization of the byproduct are realized. The utility model discloses a specific heat transfer subassembly sets up the mode, has realized the preparation scheme of no solvent, greatly reduced manufacturing cost, improved production efficiency simultaneously.

The utility model discloses still combine the production technology of silicon nitride with the micro-interface technique in, particularly, when reacting, raw materials liquid ammonia and silicon tetrachloride just can get into from the micro-interface unit, directly send to the inside of reaction tower after emulsifying through the micro-interface. Therefore, the production efficiency is greatly improved by enhancing the reaction by increasing the mass transfer area between two phases, the silicon imine intermediate with the micron-sized size can be effectively generated in a micron-sized reaction system, and the particle size distribution of the powder generated by the reaction can be more uniform by adopting a micro-interface technology.

The utility model discloses a little interface unit comprises little interface generator and expansion pipe, the liquid ammonia directly gets into little interface generator, silicon tetrachloride then gets into in the little interface generator through the expansion pipe, thus, two strands of liquid streams can form the clash in little interface generator, the pressure energy that will carry silicon tetrachloride and liquid ammonia that get into in the tower simultaneously under the effect of little interface generator can change into liquid drop surface energy and transmit for silicon tetrachloride and liquid ammonia, make the two breakage form the double-phase reaction system of micron yardstick profit in the tower and react, two interphase mass transfer areas have been improved, make and strengthen the reaction in the condition within range of predetermineeing, and make the reaction generate the silicon imine powder of micron order.

The utility model discloses a reaction tower outside still is provided with the circulating line, on the one hand, the circulating line can be through the mode of extrinsic cycle constantly circulating reaction liquid to send this reaction liquid into the expansion pipe and mix with silicon tetrachloride and get into among the micro-interface generator, be favorable to the degree of depth of reaction to go on; on the other hand, the heat exchanger arranged on the circulating pipeline can remove the reaction heat in time, and the heat exchanger is matched with the heat removal assembly to achieve a better temperature control effect and be beneficial to the constancy of the temperature in the tower.

It will be appreciated by those skilled in the art that the micro-interface generator used in the present invention has been embodied in the prior patents of the present invention, such as the patents of application numbers CN201610641119.6, CN201610641251.7, CN201710766435.0, CN106187660, CN105903425A, CN109437390A, CN205833127U and CN 207581700U. Detailed description of the specific product structure and working principle of the micro bubble generator (i.e. micro interface generator) is provided in the prior patent CN201610641119.6, which describes that "the micro bubble generator comprises a body and a secondary crushing member, wherein the body is provided with a cavity therein, the body is provided with an inlet communicated with the cavity, the opposite first end and second end of the cavity are both open, and the cross-sectional area of the cavity decreases from the middle part of the cavity to the first end and second end of the cavity; the secondary crushing member is disposed at least one of the first end and the second end of the cavity, a portion of the secondary crushing member is disposed within the cavity, and an annular passage is formed between the secondary crushing member and the through holes open at both ends of the cavity. The micron bubble generator also comprises an air inlet pipe and a liquid inlet pipe. "the specific working principle of the specific structure disclosed in the application document is as follows: liquid tangentially enters the micro-bubble generator through the liquid inlet pipe, and gas is cut by ultra-high speed rotation to break gas bubbles into micro-bubbles at the micron level, so that the mass transfer area between a liquid phase and a gas phase is increased.

In addition, in the patent 201610641251.7, it is described that the primary bubble breaker has a circulation liquid inlet, a circulation gas inlet and a gas-liquid mixture outlet, and the secondary bubble breaker communicates the feed inlet with the gas-liquid mixture outlet, which means that the bubble breakers all need to be mixed with gas and liquid, and it can be known from the following figure that the primary bubble breaker mainly uses circulation liquid as power, so the primary bubble breaker belongs to a hydraulic micro-interface generator, and the secondary bubble breaker simultaneously introduces the gas-liquid mixture into an elliptical rotating ball for rotation, thereby realizing bubble breaking in the rotation process, so the secondary bubble breaker actually belongs to a gas-liquid linkage micro-interface generator. In fact, no matter be the hydraulic formula micro-interface generator, still gas-liquid linkage micro-interface generator all belongs to a specific form of micro-interface generator, however the utility model discloses the micro-interface generator who adopts is not limited to above-mentioned several kinds of forms, and the specific structure of the bubble breaker who records in the patent in advance is only one of them form that the micro-interface generator can adopt.

In addition, the patent 201710766435.0 states that the principle of the bubble breaker is high-speed jet flow to achieve mutual collision of gases, and also states that the bubble breaker can be used for a micro-interface strengthening reactor to verify the relevance between the bubble breaker and a micro-interface generator; moreover, in the prior patent CN106187660, there is a related description on the specific structure of the bubble breaker, see paragraphs [0031] - [0041] in the specification, and the accompanying drawings, which illustrate the specific working principle of the bubble breaker S-2 in detail, the top of the bubble breaker is a liquid phase inlet, and the side of the bubble breaker is a gas phase inlet, and the liquid phase coming from the top provides entrainment power, so as to achieve the effect of breaking into ultrafine bubbles.

Because in the initial stage of earlier patent application, the micro-interface generator just developed, so the early name is micron bubble generator (CN 201610641119.6), bubble breaker (201710766435.0) etc. along with continuous technological improvement, the later stage is more named as the micro-interface generator, now the utility model provides a micro-interface generator and micro-interface generator are equivalent to micron bubble generator, bubble breaker etc. before, just the name is different. To sum up, the utility model discloses a little interface generator belongs to prior art.

Preferably, the inlet of the circulation line comprises a first inlet and a second inlet, the first inlet being located above the second inlet. During production, different inlets can be selected according to the height of the liquid level in the tower to realize circulation of the reaction liquid.

Preferably, a first baffle is arranged in the reaction tower, the top of the first baffle is higher than the first inlet along the vertical direction, and the bottom of the first baffle is located between the first inlet and the second inlet along the vertical direction.

Preferably, a second baffle is arranged in the reaction tower, the top of the second baffle is located between the first inlet and the second inlet along the vertical direction, and the bottom of the second baffle is located below the second inlet along the vertical direction.

The utility model discloses a set up first baffle and second baffle respectively, can prevent that the silicon imine crystallization that produces in the outer loop in-process tower from blockking up or damaging the device on the pipeline in getting into the circulating line to improve whole life.

Preferably, the washing device further comprises a washing filter, the discharger is connected with the washing filter, a filter residue outlet of the washing filter is connected with a silicon nitride output pipeline, and a filtrate outlet of the washing filter is connected with a recovery pipeline.

Preferably, a screw conveyor is arranged in the washing filter, and filter residues are output by the screw conveyor; and a liquid ammonia washing liquid conveying pipeline is arranged above the washing filter.

Preferably, the silicon nitride output pipeline comprises a temperature programming furnace and a silicon nitride conveying pipeline, and filter residues are output from the silicon nitride conveying pipeline after being processed by the temperature programming furnace.

Preferably, the recovery pipeline comprises a crude ammonium chloride storage tank, an ammonia evaporator and an ammonia condenser, the filtrate filtered out by the washing filter is processed by the ammonia evaporator, the obtained ammonia gas enters the ammonia condenser, and the obtained crude ammonium chloride enters the crude ammonium chloride storage tank.

The utility model also provides a method of production silicon nitride, the production silicon nitride of using above-mentioned production system.

The method is simple to operate, and can produce silicon nitride powder with uniform and fine granularity.

Compared with the prior art, the beneficial effects of the utility model reside in that:

(1) No solvent: the utility model adopts the preparation idea of solvent-free silicon nitride production, avoids the separation problem in the subsequent treatment, and adopts the heavy heat transfer mode, so that the system is not required to be broken down due to obvious heat release, the reaction speed is not changed into the toggle for manufacturing the silicon nitride, the product purity is greatly improved, and the ammonium chloride byproduct can be more simply purified in the subsequent process;

(2) Continuous production: the reaction system of the utility model can realize continuous production, and the liquid ammonia in the reaction process can be continuously recycled;

(3) The product has uniform granularity and high fineness: the utility model discloses after changing traditional silicon nitride preparation technology into the micro-interface and strengthening the technology, raw materials liquid ammonia and silicon tetrachloride just can get into from the micro-interface unit, directly send to the inside of reaction tower after the rethread micro-interface emulsification. Therefore, the production efficiency is greatly improved by increasing the mass transfer area between two phases to enhance the reaction, and meanwhile, the silicon imine intermediate with micron-sized dimension can be effectively generated in a micron-sized reaction system, and the particle size distribution of the powder generated by the reaction can be more uniform by adopting the micro-interface technology.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:

fig. 1 is a schematic structural diagram of a reaction system provided by an embodiment of the present invention.

1-a heat exchanger; 2-a silicon tetrachloride delivery line;

3-flushing the pipeline; 4-expanding the tube;

5-a first baffle; 6-a second baffle;

7-a micro-interface generator; 8-a coil pipe;

9-liquid ammonia delivery line; 10-outer jacket;

11-a discharger; 12-washing the filter;

13-liquid ammonia washing liquid conveying pipeline; 14-screw conveyor;

15-temperature programmed furnace; 16-silicon nitride conveying pipelines;

17-a return line; an 18-ammonia condenser;

19-an ammonia evaporator; 20-a storage tank for crude ammonium chloride;

21-ammonium chloride crude product conveying pipeline; 22-a circulation pump;

23-nitrogen pressurization means; 24-a reaction column;

25-a circulation line; 26-a first inlet;

27-second inlet.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings and detailed description, but those skilled in the art will understand that the following described embodiments are some, not all, of the embodiments of the present invention, and are only used for illustrating the present invention, and should not be construed as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.

In order to clarify the technical solution of the present invention, the following description is made in the form of specific embodiments.

Example 1

Referring to fig. 1, the present embodiment provides a reaction system for producing silicon nitride, including: the reaction tower 24 and the heat transfer component, the heat transfer component is arranged on the reaction tower 24; a micro-interface unit is arranged in the reaction tower 24 and comprises a micro-interface generator 7 and an expansion pipe 4 positioned above the micro-interface generator 7, and the bottom of the expansion pipe 4 is communicated with the micro-interface generator 7; the top of the expansion pipe 4 is connected with a silicon tetrachloride conveying pipeline 2, and the micro-interface generator 7 is connected with a liquid ammonia conveying pipeline 9. The diameter of the expanding tube 4 of this embodiment is gradually increased from top to bottom, and the bottom of the expanding tube 4 is in contact with the top wall of the micro-interface generator 7.

The heat transfer assembly comprises a coil pipe 8 and an outer jacket 10, the coil pipe 8 is coiled on the inner wall of the reaction tower 24, and the outer jacket 10 is sleeved on the outer wall of the reaction tower 24; when the device is actually used, low-temperature heat conducting oil is introduced into the coil 8, and ethylene glycol aqueous solution or low-temperature heat conducting oil with the temperature of minus 55 ℃ and minus 65 ℃ is introduced into the outer jacket 10 for cold insulation.

In this embodiment, a circulation pipeline 25 is arranged outside the reaction tower 24, an inlet of the circulation pipeline 25 is connected with the side wall of the reaction tower 24, and an outlet of the circulation pipeline 25 is communicated with the top of the expansion pipe 4; the heat exchanger 1 and the circulation pump 22 are provided in the circulation line 25.

Specifically, the inlet of the circulation line 25 includes a first inlet 26 and a second inlet 27, and the first inlet 26 is located above the second inlet 27. When the outlet of the circulating pipeline 25 is used for production, different inlets can be selected according to the liquid level height in the tower to realize the circulation of the reaction liquid.

The top of the reaction tower 24 is also connected with a flushing pipeline 3, the flushing pipeline 3 is used for preventing the occurrence of conditions such as blockage inside the reaction tower 24, and after the blockage occurs inside the reaction tower 24, organic solvent can be input through the flushing pipeline 3 for dredging.

In order to prevent the silicon imide crystals generated during the circulation from entering the circulation line 25, a first baffle 5 and a second baffle 6 are provided in the reaction tower 24, wherein the first baffle 5 has a top portion vertically higher than the first inlet 26 and a bottom portion vertically between the first inlet 26 and the second inlet 27. The second baffle 6 has a top portion located between the first inlet 26 and the second inlet 27 in the vertical direction and a bottom portion located below the second inlet 27 in the vertical direction.

Because the product of the reaction in the reaction tower 24 is crystallized to form a solid state, a discharging device 11 is arranged at the bottom of the reaction tower 24 for easy extraction; the discharging device 11 is funnel-shaped, and the reaction product in the reaction tower 24 flows out through the discharging device 11.

The reaction system of the embodiment further comprises a washing filter 12, the discharging device 11 is connected with the washing filter 12, a filter residue outlet of the washing filter 12 is connected with a silicon nitride output pipeline, and a filtrate outlet of the washing filter 12 is connected with a recovery pipeline.

Wherein, a screw conveyor 14 is arranged in the washing filter 12, and filter residue is output by the screw conveyor 14 and enters a silicon nitride output pipeline; a liquid ammonia washing liquid conveying pipeline 13 is arranged above the washing filter 12. In addition, a nitrogen pressurization device 23 may be provided to increase the filtration pressure in order to improve the filtration efficiency in the washing filter 12.

The silicon nitride output pipeline comprises a temperature programming furnace 15 and a silicon nitride conveying pipeline 16, the filter residue is processed by the temperature programming furnace 15 to generate a final product silicon nitride, and the generated silicon nitride is output from the silicon nitride conveying pipeline 16.

The recycling pipeline comprises an ammonium chloride crude product storage tank 20, an ammonia evaporator 19 and an ammonia condenser 18, filtrate filtered by the washing filter 12 is treated by the ammonia evaporator 19, obtained ammonia gas enters the ammonia condenser 18, and obtained crude ammonium chloride enters the ammonium chloride crude product storage tank 20. After the ammonia gas is cooled to liquid ammonia in the ammonia condenser 18, the liquid ammonia is sent to the liquid ammonia delivery pipe 9 through the return pipe 17 thereon. The crude ammonium chloride storage tank 20 is connected to a crude ammonium chloride conveying pipeline 21 for outputting crude ammonium chloride.

The method for producing silicon nitride by using the reaction system of the embodiment is as follows:

before reaction, nitrogen replacement is carried out on the whole system, and silicon tetrachloride and liquid ammonia are input into a micro-interface unit after being cooled to-35 to-45 ℃; silicon tetrachloride and liquid ammonia are dispersed and crushed into micro-droplets in a micro interface unit and then sent into a reaction tower 24 to react, the generated product is sent into a washing filter 12, the liquid ammonia is sprayed and washed for 4-5 times until ammonium chloride is completely dissolved in liquid ammonia filtrate, the obtained filter residue is sent into a temperature programming furnace 15 to obtain a product silicon nitride, and the silicon nitride is output through a silicon nitride output pipeline; and (3) sending the filtrate obtained by washing into an ammonia evaporator 19, cooling the ammonia gas obtained by evaporation into liquid ammonia in an ammonia condenser 18, sending the liquid ammonia into a liquid ammonia conveying pipeline 9 for recycling, sending the crude ammonium chloride obtained by evaporation into an ammonium chloride crude product storage tank 20, and outputting the crude ammonium chloride to the purification process through an ammonium chloride crude product conveying pipeline 21.

Through detection, the produced silicon nitride powder has uniform granularity which is between 1 and 3 mu m.

Example 2

The difference between this example and example 1 is only that in this example the bottom of the dilation tube 4 penetrates inside the micro-interface generator 7.

Through detection, the produced silicon nitride powder has uniform granularity which is between 2 and 6 mu m.

Comparative example 1

This example differs from example 1 only in that no micro-interface unit is used.

Through detection, the produced silicon nitride powder has uniform granularity which is between 5 and 20 mu m.

Comparing the silicon nitride powders produced in example 1 and example 2, it can be seen that although the minimum particle sizes of the silicon nitride powders of example 1 and example 2 are substantially the same, the silicon nitride powder of example 1 has a narrower particle size distribution and a finer overall particle size, which is probably because the extension tube extending directly into the interior of the micro-interfacial generator affects the residence time of the silicon tetrachloride and the circulating liquid themselves in the micro-interfacial generator and the impact effect between the silicon tetrachloride and the circulating liquid and the liquid ammonia, indicating that the best quality silicon nitride can be obtained only when the bottom of the extension tube is brought into direct contact with the top wall of the micro-interfacial generator.

Comparing with the silicon nitride powder produced in example 1, it can be seen that the silicon nitride powder of example 1 has finer particle size, narrower particle size distribution and better uniformity, which indicates that the uniformity of silicon nitride can be improved by using the micro-interface technique and the silicon nitride powder produced can be made finer.

In a word, compare with prior art, the utility model discloses a reaction system of production silicon nitride can realize solvent-free production, low in production cost, and the silicon nitride powder particle diameter of production is even, and the fineness is high.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications or substitutions do not depart from the scope of the invention in its corresponding aspects.

Claims (10)

1. A reaction system for producing silicon nitride, comprising: the heat transfer assembly is arranged on the reaction tower; a micro-interface unit is arranged in the reaction tower, the micro-interface unit comprises a micro-interface generator and an expansion pipe positioned above the micro-interface generator, and the bottom of the expansion pipe is communicated with the micro-interface generator; the top of the expansion pipe is connected with a silicon tetrachloride conveying pipeline, and the micro-interface generator is connected with a liquid ammonia conveying pipeline.

2. The reaction system of claim 1, wherein a circulation pipeline is arranged outside the reaction tower, an inlet of the circulation pipeline is connected with the side wall of the reaction tower, and an outlet of the circulation pipeline is communicated with the top of the expansion pipe; and a heat exchanger is arranged on the circulating pipeline.

3. The reaction system of claim 1, wherein the heat removal assembly comprises a coil pipe and an outer jacket, the coil pipe is coiled on the inner wall of the reaction tower, and the outer jacket is sleeved on the outer wall of the reaction tower.

4. The reaction system of claim 1, wherein an ejector is provided at the bottom of the reaction column; the discharger is funnel-shaped, and reaction products in the reaction tower flow out through the discharger.

5. The reaction system of claim 1 wherein the diameter of the expanded pipe increases from top to bottom, and the bottom of the expanded pipe contacts the top wall of the micro-interface generator.

6. The reaction system of claim 2, wherein the inlet of the circulation line comprises a first inlet and a second inlet, the first inlet being positioned above the second inlet.

7. The reaction system of claim 6, wherein a first baffle is disposed within the reaction column, wherein a top of the first baffle is vertically higher than the first inlet, and a bottom of the first baffle is vertically between the first inlet and the second inlet.

8. The reaction system of claim 6 wherein a second baffle is disposed within the reaction column, the second baffle having a top vertically between the first inlet and the second inlet and a bottom vertically below the second inlet.

9. The reaction system of claim 4, further comprising a washing filter, wherein the discharger is connected with the washing filter, a filter residue outlet of the washing filter is connected with a silicon nitride output pipeline, and a filtrate outlet of the washing filter is connected with a recovery pipeline.

10. The reaction system of claim 9, wherein a screw conveyor is arranged in the washing filter, and filter residues are output by the screw conveyor; and a liquid ammonia washing liquid conveying pipeline is arranged above the washing filter.

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