A feeding device for a reduction furnace in polysilicon production

Abstract

The present invention discloses a feeding device for a reduction furnace in polysilicon production, which includes a bubbling vaporizer, a gas-liquid separator, and further includes a membrane layer unit and a control system. A trichlorosilane feeding pipeline and a hydrogen feeding pipeline are connected to the bubbling vaporizer, which are respectively used for introducing trichlorosilane liquid and hydrogen. The membrane layer unit is arranged in the bubbling vaporizer and is used for generating nano-micro bubbles of hydrogen in the trichlorosilane liquid in the bubbling vaporizer. The control system is used for tracking the liquid level change of the bubbling vaporizer and the feeding flow rate change of the trichlorosilane liquid to adjust the feeding flow rate of the trichlorosilane liquid, and for adjusting the feeding flow rate of hydrogen according to the preset ratio of the feeding flow rate of the trichlorosilane liquid to the feeding flow rate of hydrogen, so as to accurately control the feeding flow rates of trichlorosilane gas and hydrogen and their feeding ratio. The present invention can reduce energy consumption and accurately control the feeding amounts of trichlorosilane gas and hydrogen and their feeding ratio.

Description

Technical Field

[0001] The present invention belongs to the technical field of polysilicon, and particularly relates to a feeding device for a reduction furnace in polysilicon production. Background Art

[0002] Most of the international polysilicon production technologies adopt the improved Siemens method. A very important section is that high-purity trichlorosilane gas is reduced by hydrogen in a reduction furnace to produce polysilicon. The reduced polysilicon will continuously deposit on the high-temperature silicon core. As the reaction proceeds, more and more polysilicon deposits on the surface of the silicon core, the diameter of the formed silicon rod becomes larger and larger, and the consumption of trichlorosilane and hydrogen also increases accordingly. Therefore, as the reaction proceeds, the feeding amounts of trichlorosilane gas and hydrogen need to be continuously increased. In addition, during the polysilicon reduction production process, it is required that trichlorosilane gas and hydrogen enter the reduction furnace in a certain proportion. Generally speaking, the molar ratio of hydrogen to trichlorosilane is 3 - 4.5:1. If the proportion of hydrogen is insufficient, other side reactions will occur, affecting the quality of polysilicon; if the proportion of hydrogen is too high, the concentration of trichlorosilane gas will be low, reducing the collision frequency between trichlorosilane and the surface of the silicon rod, resulting in a decrease in polysilicon production, and a too high hydrogen concentration is not conducive to suppressing the precipitation of B and P impurities. Therefore, accurately controlling the feeding amounts of trichlorosilane gas and hydrogen and their feeding ratio is the key to improving the polysilicon reduction production efficiency and the quality of polysilicon.

[0003] Moreover, before feeding trichlorosilane, it needs to be vaporized first. The traditional vaporization method is to introduce hydrogen into a bubbling vaporizer containing trichlorosilane liquid, strengthen the evaporation of trichlorosilane through the bubbling of hydrogen to obtain a mixture of the two, then remove the small trichlorosilane droplets entrained in the gas through a gas-liquid separator, and finally introduce the mixture into the reduction furnace. In this vaporization process, the ratio of trichlorosilane to hydrogen is controlled by controlling the pressure or temperature in the bubbling vaporizer, and the hydrogen feeding flow is adjusted by controlling the outlet flow of the mixture gas. Since the liquid level of trichlorosilane will gradually decrease during the vaporization process, there will be a large error in controlling the feeding ratio of trichlorosilane to hydrogen. In view of the above problems existing in the traditional vaporization method, most of the existing processes adopt the method of directly vaporizing trichlorosilane liquid and then mixing it with high-purity hydrogen in a certain proportion and introducing it into the reduction furnace. However, compared with the traditional bubbling vaporization method, the required vaporization energy consumption is larger, and the traditional vaporization method can, to a certain extent, prevent B and Fe impurities in the liquid from escaping with the trichlorosilane vapor. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a feeding device for a reduction furnace in polysilicon production, which can reduce energy consumption and accurately control the feeding amounts of trichlorosilane gas and hydrogen and their feeding ratio, aiming at the above deficiencies existing in the prior art.

[0005] The technical solution of the present invention to solve the above technical problems is as follows:

[0006] A feeding device for a reduction furnace in polysilicon production, comprising a bubbling vaporizer, a gas-liquid separator, a membrane layer unit, and a control system. Among them:

[0007] A trichlorosilane feed pipeline and a hydrogen feed pipeline are connected to the bubbling vaporizer, which are respectively used to introduce trichlorosilane liquid and hydrogen. The membrane layer unit is arranged in the bubbling vaporizer and is used to generate nano / micro bubbles of hydrogen in the trichlorosilane liquid in the bubbling vaporizer.

[0008] The control system is used to track the liquid level change of the bubbling vaporizer and the feed flow change of the trichlorosilane liquid to adjust the feed flow of the trichlorosilane liquid, and, according to the preset ratio of the feed flow of the trichlorosilane liquid to the feed flow of hydrogen, adjust the feed flow of hydrogen, so as to accurately control the feed flow and the feed ratio of trichlorosilane gas and hydrogen.

[0009] Preferably, the device further comprises an ultrasonic unit, which is connected to the bubbling vaporizer and is used to feed ultrasonic waves around the membrane layer unit to make the nano / micro bubbles quickly escape and burst, and to generate cavitation.

[0010] Preferably, the membrane layer unit comprises a plate membrane and a support member. The plate membrane is installed inside the bubbling vaporizer through the support member, and the nano / micro bubbles are generated when hydrogen passes through the plate membrane.

[0011] Preferably, the device further comprises a gas distributor, which is arranged inside the bubbling vaporizer and is used to preliminarily disperse the hydrogen introduced into the vaporizing bubbler to make the hydrogen pass through the membrane layer unit evenly.

[0012] Preferably, the gas distributor adopts a spray head type structure, which includes a delivery pipe and a spray head. One end of the delivery pipe is connected to the hydrogen feed pipeline, and the other end is connected to the spray head. A plurality of air outlet holes are arranged on the spray head, and the air outlet holes are evenly distributed.

[0013] Preferably, a heating system is further arranged inside the bubbling vaporizer. The heating system includes a heat medium flow channel, which extends into the inside of the bubbling vaporizer and is used to introduce a heat medium to heat exchange and heat the trichlorosilane liquid.

[0014] Preferably, the control system includes a cascade control unit and a ratio control unit. Among them:

[0015] The cascade control unit includes a liquid level gauge, a first flowmeter, a first controller, and a computer system. The liquid level gauge is installed on the bubbling vaporizer. The first flowmeter and the first controller are both installed on the trichlorosilane feed pipeline. The computer system is electrically connected to the liquid level gauge and the first controller respectively to form a main regulation unit. A trichlorosilane liquid feed flow threshold is preset in the computer system. The liquid level gauge is used to detect the liquid level in the bubbling vaporizer and transmit the detected liquid level signal to the computer system. The computer system is used to convert the liquid level signal into a trichlorosilane liquid feed flow value and compare it with the trichlorosilane liquid feed flow threshold. And, according to the comparison result, send a first control instruction to the first controller. The first controller is used to adjust the feed flow of trichlorosilane liquid according to the first control instruction. The computer system is also electrically connected to the first flowmeter. The first flowmeter, the computer system, and the first controller form a secondary regulation unit. The first flowmeter is used to detect the feed flow of trichlorosilane liquid and transmit the detected first flow signal to the computer system. The computer system is used to receive the first flow signal to obtain the real-time trichlorosilane liquid feed flow value and compare it with the trichlorosilane liquid feed flow threshold. And, according to the comparison result, send a second control instruction to the first controller. The first controller is also used to adjust the feed flow of trichlorosilane liquid according to the second control instruction;

[0016] The ratio control unit includes a second flowmeter, a third flowmeter, a second controller, and a computer system. The second flowmeter is installed on the trichlorosilane feed pipeline. The third flowmeter and the second controller are both installed on the hydrogen feed pipeline. The computer system is also electrically connected to the second flowmeter, the third flowmeter, and the second controller respectively. A feed flow ratio threshold of trichlorosilane liquid to hydrogen is also preset in the computer system. The second flowmeter is used to detect the feed flow of trichlorosilane liquid and transmit the detected second flow signal to the computer system. The third flowmeter is used to detect the feed flow of hydrogen and transmit the detected third flow signal to the computer system. The computer system is also used to receive the second flow signal to obtain the real-time trichlorosilane liquid feed flow value and receive the third flow signal to obtain the real-time hydrogen feed flow value, and compare the ratio of the real-time trichlorosilane liquid feed flow value to the real-time hydrogen feed flow value with the feed flow ratio threshold of trichlorosilane liquid to hydrogen. And, according to the comparison result, send a third control instruction to the second controller. The second controller is used to adjust the feed flow of hydrogen according to the third control instruction.

[0017] Preferably, a hydrogen feed flow threshold is also preset in the computer system. The computer system is further configured to compare the real-time hydrogen feed flow with the hydrogen feed flow threshold, and send a fourth control instruction to the second controller according to the comparison result. The second controller is further configured to control and adjust the hydrogen feed flow according to the fourth control instruction.

[0018] Preferably, the control unit further includes a feedback control unit. The feedback control unit includes a fourth flowmeter, a third controller, and a computer system. The fourth flowmeter is arranged on the gas outlet pipeline of the gas-liquid separator. The third controller is arranged on the inlet pipeline of the heat medium flow channel. The computer system is electrically connected to the third controller and the fourth flowmeter respectively. A heat medium temperature threshold is also preset in the computer system. The fourth flowmeter is configured to detect the flow rate of the mixed gas output by the gas-liquid separator and transmit the detected fourth flow signal to the computer system. The computer system is further configured to receive the fourth flow signal, convert it into a heat medium temperature value, and compare the heat medium temperature value with the heat medium temperature threshold, and send a fourth control signal to the third controller according to the comparison result. The third controller is configured to adjust the heat medium temperature according to the fourth control signal.

[0019] Preferably, a vent valve and a residual liquid drain valve are provided on the bubbling vaporizer, where:

[0020] The vent valve is arranged on the upper part of the bubbling vaporizer and is used to relieve pressure on the bubbling vaporizer;

[0021] The residual liquid drain valve is arranged on the bottom of the bubbling vaporizer and is used to discharge the trichlorosilane residual liquid at the bottom of the bubbling vaporizer.

[0022] The feeding device for a polysilicon production reduction furnace of the present invention has the following beneficial effects compared with the prior art:

[0023] (1) By setting the membrane layer unit, the structure of the bubbling vaporizer is innovatively improved, so that the hydrogen gas introduced into the trichlorosilane liquid can be transformed into nano-micro bubbles with a smaller pressure drop, increasing the gas-liquid two-phase interface, and enabling the trichlorosilane to generate more "vaporization centers", thereby effectively reducing the vaporization energy consumption.

[0024] (2) By setting the control system, the feeding amounts of trichlorosilane gas and hydrogen and their feeding ratio can be accurately controlled. Moreover, the heat medium temperature can even be adjusted, thereby improving the polysilicon reduction production efficiency and the quality of polysilicon.

[0025] (3) By setting up the ultrasonic unit, not only can the nano-micro bubbles in the film layer unit escape and rupture as soon as possible, enabling the gas to escape from the bubbles as soon as possible, but also "cavitation" can be generated inside the trichlorosilane liquid, causing tens of thousands of tiny bubbles containing trichlorosilane gas to be rapidly generated inside the trichlorosilane liquid. By utilizing the huge instantaneous pressure and temperature generated when these tiny bubbles rupture, the vaporization efficiency of trichlorosilane can be further enhanced.

[0026] (4) By setting up the liquid level and temperature alarm system, alarms can be given for abnormal situations such as the liquid level of the bubbling vaporizer exceeding its preset value or the temperature inside the device exceeding its preset value, further ensuring the operation stability and safety of the device. Description of the Drawings

[0027] Figure 1 It is a schematic structural diagram of the feeding device for the reduction furnace in the production of polysilicon in the embodiment of the present invention;

[0028] Figure 2 It is a schematic structural diagram of the gas distributor in the embodiment of the present invention;

[0029] Figure 3 It is a top view of the gas distributor in the embodiment of the present invention.

[0030] In the figure: 1 - bubbling vaporizer; 2 - vent valve; 3 - film layer unit; 4 - ultrasonic unit; 5 - heating system; 6 - gas distributor; 7 - residual liquid drain valve; 8 - gas-liquid separator; 9 - hydrogen feed pipeline; 10 - trichlorosilane feed pipeline; 11 - gas outlet pipeline; 12 - liquid outlet pipeline; 13 - outlet pipeline; 14 - inlet pipeline; 15 - gas outlet hole; FT - flow transmitter; FV - flow regulator; FY - flow relay; FRC - flow recording control; FFIC - flow ratio indicating controller; LRC - liquid level recording controller; LRCA - liquid level alarm system; LT - liquid level transmitter; TIA - temperature alarm system; TRC - temperature recording controller; TV - temperature regulator. Detailed Embodiments

[0031] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the present invention will be clearly and completely described below in conjunction with the drawings in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts belong to the protection scope of the present invention.

[0032] In the description of the present invention, it should be noted that the terms "upper" and the like indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings. It is only for the convenience and simplification of description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0033] In the description of the present invention, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, "a plurality of" means two or more, unless otherwise specifically defined.

[0034] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "connected", "arranged", "installed", "fixed", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or the communication inside two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] Aiming at the problems in the prior art such as high energy consumption, difficult control of the feed rate and the feed ratio of trichlorosilane gas and hydrogen during the feed process of the reduction furnace for polysilicon production, the present invention provides a feed device for the reduction furnace for polysilicon production, including a bubbling vaporizer, a gas-liquid separator, and further including a membrane layer unit and a control system, wherein:

[0036] A trichlorosilane feed pipeline and a hydrogen feed pipeline are connected to the bubbling vaporizer, which are respectively used for introducing trichlorosilane liquid and hydrogen. The membrane layer unit is arranged inside the bubbling vaporizer, and is used to generate nano-micro bubbles of hydrogen in the trichlorosilane liquid in the bubbling vaporizer, so as to increase the gas-liquid two-phase interface, make the trichlorosilane liquid generate more "vaporization centers", and thus effectively reduce the vaporization energy consumption;

[0037] The control system is used to track the liquid level change of the bubbling vaporizer and the feed flow change of the trichlorosilane liquid to adjust the feed flow of the trichlorosilane liquid, and, according to the preset ratio of the feed flow of the trichlorosilane liquid to the feed flow of hydrogen, adjust the feed flow of hydrogen, so as to accurately control the feed flow and the feed ratio of trichlorosilane gas and hydrogen.

[0038] Embodiment 1

[0039] As Figure 1As shown in the figure, this embodiment discloses a feeding device for a polysilicon production reduction furnace, which includes a bubbling vaporizer 1 and a gas-liquid separator 8. Moreover, compared with the prior art, this device further includes a film layer unit 3 and a control system.

[0040] Specifically, a trichlorosilane feed pipeline 10 and a hydrogen feed pipeline 9 are connected to the bubbling vaporizer 1, which are respectively used to introduce trichlorosilane liquid and hydrogen, so as to vaporize the trichlorosilane liquid by bubbling the hydrogen through the trichlorosilane liquid. The gas-liquid separator 8 is connected to the bubbling vaporizer 1, and specifically, a spiral steam-water separator or a baffle steam-water separator can be used to receive the gas discharged from the bubbling vaporizer and perform gas-liquid separation on it, removing the trichlorosilane small liquid droplets entrained in the gas to obtain a mixed gas of trichlorosilane gas and hydrogen, and the mixed gas is introduced into the polysilicon production reduction furnace.

[0041] The film layer unit 3 is arranged inside the bubbling vaporizer 1 and is used to generate nano-micro bubbles of hydrogen in the trichlorosilane liquid in the bubbling vaporizer 1. Specifically, since the vaporization process of the trichlorosilane liquid involves a gas nucleation process, compared with homogeneous nucleation, heterogeneous nucleation is easier to occur than homogeneous nucleation. When the trichlorosilane liquid vaporizes, liquid-phase molecules will gather on the solid phase or other heterogeneous interfaces, and the continuous collision of molecules makes the energy accumulate, and then forms a "vaporization center". Through the film layer unit 3, a large number of hydrogen nano-micro bubbles can be generated. The nano-micro bubbles will generate more "vaporization centers" in the trichlorosilane liquid, significantly increasing the gas-liquid interface, bringing out more trichlorosilane vapor, and generating more "vaporization centers", thereby effectively reducing the vaporization energy consumption.

[0042] The control system is used to track the liquid level change of the bubbling vaporizer 1 and the feed flow rate change of the trichlorosilane liquid to adjust the feed flow rate of the trichlorosilane liquid, and, according to the preset ratio of the feed flow rate of the trichlorosilane liquid to the feed flow rate of hydrogen, adjust the feed flow rate of hydrogen, so as to accurately control the feed flow rates of the trichlorosilane gas and hydrogen and their feed ratio.

[0043] In some embodiments, the device of this embodiment further includes an ultrasonic unit 4. The ultrasonic unit 4 is connected to the bubbling vaporizer 1 and is used to feed ultrasonic waves around the film layer unit in the bubbling vaporizer 1. The ultrasonic waves can make the nano-micro bubbles quickly escape and rupture, so that the gas can escape from the bubbles as soon as possible. Moreover, the ultrasonic waves can also cause cavitation in the trichlorosilane liquid, quickly generating tens of thousands of tiny bubbles (the inside of the bubbles is trichlorosilane gas) in the trichlorosilane liquid and quickly rupturing. At the moment when the bubbles rupture, a huge instantaneous pressure and temperature will be generated, strengthening the vaporization efficiency of the trichlorosilane liquid, that is, improving the vaporization efficiency.

[0044] In this embodiment, as Figure 1As shown, the ultrasonic unit 4 preferably includes at least two ultrasonic feeding probes, and each feeding probe is arranged at a position outside the bubbling vaporizer corresponding to the position of the membrane layer unit 3. The specific distribution of each ultrasonic feeding probe should be as uniform as possible. The ultrasonic frequency is set to 40 - 68 kHz. The ultrasonic unit 4 can be used or not used during the operation of the device in this embodiment, and the specific selection is made according to actual needs.

[0045] In some embodiments, the membrane layer unit 3 includes a plate membrane and a support. The plate membrane is installed inside the bubbling vaporizer 1 through the support, and the nano-micro bubbles are generated when hydrogen passes through the plate membrane.

[0046] Specifically, the plate membrane is an oil-repellent and breathable membrane, and the oil-repellent and breathable membrane can reduce the pressure drop generated when hydrogen flows through the membrane layer unit. The pore size of the oil-repellent and breathable membrane is preferably 0.1 - 10 μm. For example, it can be 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, etc. The support is specifically a support plate for fixing and supporting the oil-repellent and breathable membrane.

[0047] In this embodiment, the material of the oil-repellent and breathable membrane is preferably polytetrafluoroethylene or any other material that can achieve the oil-repellent and breathable effect, which will not be elaborated here one by one.

[0048] In some embodiments, the device in this embodiment further includes a gas distributor 6. The gas distributor 6 is arranged inside the bubbling vaporizer 1 and is used for preliminarily dispersing the hydrogen introduced into the vaporization bubbler 1, so that the hydrogen passes through the membrane layer unit evenly, and to avoid the rupture of the plate membrane in the membrane layer unit 3 due to excessive local intake pressure.

[0049] Specifically, the gas distributor 6 is located below the plate membrane. The inlet end of the gas distributor 6 is connected to the hydrogen feed pipeline 9, and the outlet end of the gas distributor 6 is communicated with the inside of the bubbling vaporizer 1, that is, the hydrogen feed pipeline 9 is connected to the bubbling vaporizer 1 through the gas distributor 6, and the hydrogen enters the bubbling vaporizer 1 after being preliminarily dispersed by the gas distributor 6.

[0050] As Figure 2 、 Figure 3 shown, the specific structure of the gas distributor 6 preferably adopts a spray head type structure, which includes a delivery pipe 17 and a spray head 16. One end of the delivery pipe 17 is connected to the hydrogen feed pipeline 9, and the other end is connected to the spray head 16. The spray head 16 has a funnel-shaped outer shape, and a number of (such as 50, 100, etc.) air outlet holes 15 communicating with the delivery pipe are provided at one end facing the plate membrane. The air outlet holes 15 are evenly distributed to make the gas entering the bubbling vaporizer 1 as evenly dispersed as possible. The air outlet holes 15 are preferably circular air outlet holes. The pore size of the air outlet holes 15 is preferably 0.1 - 1 cm, and more preferably 0.5 cm.

[0051] In some embodiments, a heating system 5 is provided inside the bubbling vaporizer 1. The heating system heats up the trichlorosilane liquid introduced into the bubbling vaporizer 1 by means of heat medium heat exchange. The heating system 5 includes a heat medium flow channel which extends into the interior of the bubbling vaporizer 1, preferably in the middle and lower part of the bubbling vaporizer 1. For example, it is located between the membrane layer unit 3 and the gas distributor 6 and is used to introduce the heat medium to exchange heat and heat the trichlorosilane liquid.

[0052] Specifically, as Figure 1 shown, the heat medium flow channel is a double U-shaped pipeline to make the temperature rise of the trichlorosilane liquid more uniform. The inlet pipeline end 14 of the heat medium flow channel is at the lower part, and its outlet pipeline 13 is at the upper part, that is, the heat medium enters from the lower part and is discharged from the upper part. The heat medium preferably uses water or heat-conducting oil.

[0053] In some embodiments, the control system includes a cascade control unit and a ratio control unit. The cascade control unit is used to track the liquid level change of the bubbling vaporizer and the change of the feed flow rate of the trichlorosilane liquid and adjust the feed flow rate of the trichlorosilane liquid. The ratio control unit is used to adjust the feed flow rate of hydrogen according to the preset ratio of the feed flow rate of the trichlorosilane liquid to the feed flow rate of hydrogen, that is, taking the flow rate of hydrogen as the control flow according to the ratio, and controlling the flow rate of hydrogen through the set value of the feed flow rate of the trichlorosilane liquid.

[0054] Specifically, the cascade control unit includes a computer system and on-site installed instruments such as a liquid level gauge, a first flowmeter, and a first controller. The liquid level gauge is installed on the bubbling vaporizer 1, and the first flowmeter and the first controller are both installed on the trichlorosilane feed pipeline 10. The computer system is electrically connected to the liquid level gauge and the first controller respectively to form a main adjustment unit. A trichlorosilane liquid feed flow rate threshold is preset in the computer system. The liquid level gauge is used to detect the liquid level in the bubbling vaporizer to obtain a liquid level signal and transmit the detected liquid level signal to the computer system. The computer system is used to convert the liquid level signal into a trichlorosilane liquid feed flow rate value and compare it with the trichlorosilane liquid feed flow rate threshold. And, according to the comparison result, send a first control instruction to the first controller. The first controller is used to adjust the feed flow rate of the trichlorosilane liquid according to the first control instruction. The computer system is also electrically connected to the first flowmeter. The first flowmeter, the computer system, and the first controller form a secondary adjustment unit. The first flowmeter is used to detect the feed flow rate of the trichlorosilane liquid to obtain a first flow signal and transmit the detected first flow signal to the computer system. The computer system is used to receive the first flow signal to obtain the real-time trichlorosilane liquid feed flow rate value and compare it with the trichlorosilane liquid feed flow rate threshold. And, according to the comparison result, send a second control instruction to the first controller. The first controller is also used to adjust the feed flow rate of the trichlorosilane liquid according to the second control instruction.

[0055] The ratio control unit includes a computer system and in-situ installed instruments such as a second flowmeter, a third flowmeter, and a second controller. The second flowmeter is arranged on the trichlorosilane feed pipeline 10, and the third flowmeter and the second controller are both arranged on the hydrogen feed pipeline 9. The computer system is also electrically connected to the second flowmeter, the third flowmeter, and the second controller respectively. A feed flow ratio threshold of trichlorosilane liquid and hydrogen is preset in the computer system. The second flowmeter is used to detect the feed flow of trichlorosilane liquid to obtain a second flow signal, and transmit the detected second flow signal to the computer system. The third flowmeter is used to detect the feed flow of hydrogen to obtain a third flow signal, and transmit the detected third flow signal to the computer system. The computer system is also used to receive the second flow signal to obtain the real-time trichlorosilane liquid feed flow value and receive the third flow signal to obtain the real-time hydrogen feed flow value, and compare the ratio of the real-time trichlorosilane liquid feed flow value to the real-time hydrogen feed flow value with the feed flow ratio threshold of trichlorosilane liquid and hydrogen. Moreover, according to the comparison result, a third control instruction is sent to the second controller, and the second controller is used to adjust the feed flow of hydrogen according to the third control instruction, so as to accurately control the feed ratio of trichlorosilane gas and hydrogen.

[0056] In this embodiment, as Figure 1As shown in the figure, the computer system of the cascade control unit includes the computer system itself and the liquid level recording controller LRC-01 and the flow recording controller FRC-01 that are centrally connected to the computer system. The liquid level signal detected by the liquid level gauge is transmitted to the liquid level recording controller LRC-01 through the liquid level transmitter LT-01. After being converted into a flow signal by the computer system, it is transmitted to the flow recording controller FRC-01. In the flow recording controller FRC-01, the computer system converts the flow signal into the flow value of trichlorosilane liquid feed and compares it with the trichlorosilane liquid feed flow threshold. Then, according to the comparison result, a first control instruction is sent to the flow regulator FV-01 (i.e., the first controller) to automatically adjust the feed flow of trichlorosilane liquid, that is, to realize the adjustment of the feed flow of trichlorosilane liquid according to the liquid level change. And, before the adjustment of the feed flow of trichlorosilane liquid according to the liquid level change, it also includes transmitting the first flow signal detected by the first flowmeter to the flow recording controller FRC-01 through the flow transmitter FT-01 in the same way. In the flow recording controller FRC-01, the computer system converts the flow signal into the flow value of trichlorosilane liquid feed and compares it with the trichlorosilane liquid feed flow threshold. Then, according to the comparison result, a second control instruction is sent to the flow regulator FV-01 (i.e., the first controller) to automatically adjust and correct the feed flow of trichlorosilane liquid. Since before the adjustment according to the liquid level change, the flow regulator FV-01 has corrected the fluctuation of the trichlorosilane liquid feed flow caused by other factors in the system first, it can make the adjustment of the change of the trichlorosilane liquid feed flow according to the liquid level change more accurately controlled later, that is, it can improve the control accuracy.

[0057] In this embodiment, as Figure 1 shown, the computer system in the ratio control system includes the computer system itself and the flow ratio indicating control FFIC-01 and the flow relay FY-01 that are centrally connected to the computer system. The second flow signal detected by the second flowmeter is transmitted to the flow ratio indicating control FFIC-01 through the flow transmitter FT-02 and the flow relay FY-01 successively. The third flow signal detected by the third flowmeter is transmitted to the ratio indicating control FFIC-01 through the flow transmitter FT-03 in the same way. After being converted by the computer system, the second flow signal is converted into the real-time flow value of trichlorosilane liquid feed and the third flow signal is converted into the real-time flow value of hydrogen feed. Then, the ratio of the real-time flow value of trichlorosilane liquid feed to the real-time flow value of hydrogen feed is compared with the feed flow ratio threshold of trichlorosilane liquid to hydrogen. Then, according to the comparison result, a third control instruction is sent to the flow regulator FV-02 (i.e., the second controller) to automatically adjust the feed flow of hydrogen, and then adjust the feed ratio of trichlorosilane gas to hydrogen.

[0058] In some embodiments, a hydrogen feed flow rate threshold is also preset in the computer system. The computer system is further configured to compare the real-time hydrogen feed flow rate with the hydrogen feed flow rate threshold, and send a fourth control instruction to the second controller according to the comparison result. The second controller is further configured to control and adjust the hydrogen feed flow rate according to the fourth control instruction, so as to avoid system instability caused by too large a hydrogen feed flow rate.

[0059] In some embodiments, the control unit further includes a feedback control unit, which is configured to track the flow rate change of the material in front of the reduction furnace (i.e., the mixed gas of trichlorosilane gas and hydrogen obtained after gas-liquid separation) and adjust the temperature of the heat medium for heating the trichlorosilane liquid.

[0060] Specifically, the feedback control unit includes a computer system and on-site installed instruments such as a fourth flowmeter and a third controller. The fourth flowmeter is arranged on the gas outlet pipeline 11 of the gas-liquid separator 8, and the third controller is arranged on the inlet pipeline 14 of the heat medium flow channel. The computer system is also electrically connected to the third controller and the fourth flowmeter respectively. A heat medium temperature threshold is also preset in the computer system. The fourth flowmeter is configured to detect the flow rate of the mixed gas output by the gas-liquid separator 8 to obtain a fourth flow signal, and transmit the detected fourth flow signal to the computer system. The computer system is further configured to receive the fourth flow signal, convert it into a heat medium temperature value, and compare the heat medium temperature value with the heat medium temperature threshold, and send a fourth control signal to the third controller according to the comparison result. The third controller is configured to adjust the heat medium temperature according to the fourth control signal.

[0061] In this embodiment, as Figure 1 shown, the computer system in the feedback control unit includes the computer system itself and a flow recording controller FRC-02 and a temperature recording controller TRC-01 that are centrally connected to the computer system. The fourth flow signal detected by the fourth flowmeter is transmitted to the flow recording controller FRC-02 through a flow transmitter FT04, converted into a temperature signal by the computer system and transmitted to the temperature recording controller TRC-01. In the temperature recording controller TRC-01, the temperature signal is converted into a heat medium temperature value by the computer system and compared with the heat medium temperature threshold. Then, a fourth control signal is sent to the temperature regulator TV-01 (i.e., the third controller) according to the comparison result to automatically adjust the temperature of the heat medium.

[0062] In some embodiments, the device of this embodiment further includes a liquid level and temperature alarm system, which is configured to give an alarm when the liquid level of the bubbling vaporizer exceeds its preset value or the temperature in the device exceeds its preset value, so as to ensure the stable operation of the bubbling vaporizer.

[0063] Specifically, asFigure 1 As shown in the figure, the liquid level and temperature alarm system includes a liquid level alarm system LRCA-01 and a temperature alarm system TIA-01.

[0064] The liquid level alarm system LRCA-01 is electrically connected to a liquid level gauge and a liquid level recording controller LRC-01 respectively. The liquid level signal detected by the liquid level gauge is also transmitted to the liquid level alarm system LRCA-01 through a liquid level transmitter LT-01. The liquid level alarm system is centrally connected to a computer system, in which a liquid level threshold value is preset. The liquid level alarm system receives the liquid level signal, and after being converted by the computer system, a liquid level value is obtained and compared with the liquid level threshold value. When the liquid level value reaches or exceeds the liquid level threshold value, a liquid level alarm signal is sent.

[0065] As Figure 1 shown in the figure, the temperature alarm system TIA-01 includes a thermometer and an alarm. The number of thermometers is preferably multiple, which are respectively installed inside the bubbling vaporizer and on the outlet pipeline of the heat medium flow channel, and are respectively used to detect the temperature inside the bubbling vaporizer and the heat medium outlet temperature, and transmit them to the alarm. A temperature threshold value is preset in the alarm, which is used to receive the temperature value transmitted by the thermometer and compare it with the temperature threshold value. When the temperature value reaches or exceeds the temperature threshold value, a temperature alarm signal is sent.

[0066] In some embodiments, a vent valve 2 and a residual liquid drain valve 7 are provided on the bubbling vaporizer. The vent valve 1 is provided at the upper part of the bubbling vaporizer 1 for relieving pressure of the bubbling vaporizer to prevent excessive pressure inside the bubbling vaporizer. The residual liquid drain valve 7 is provided at the bottom of the bubbling vaporizer for discharging trichlorosilane residual liquid with too high impurity content at the bottom of the bubbling vaporizer.

[0067] The operation process of the device in this embodiment is described in detail below, specifically as follows:

[0068] As Figure 1 shown in the figure, trichlorosilane liquid is introduced into the upper part of the bubbling vaporizer 1 through a trichlorosilane feed pipeline 10, and water at 40 - 80°C is introduced through a heating system 5 to heat it to obtain trichlorosilane gas. Hydrogen is introduced into the lower part of the bubbling vaporizer 1 through a hydrogen feed pipeline 9, and furthermore, the hydrogen is preliminarily dispersed through 0.5 cm air holes 15 on a gas distributor 6. After the hydrogen enters the bubbling vaporizer 1, it passes through the oil-repellent and breathable membrane in the membrane layer unit 3 to form nano-micro bubbles and flow upward. Compared with large bubbles, nano-micro bubbles can increase the gas-liquid two-phase interface, not only can bring out more trichlorosilane gas, but also can form more "vaporization centers" in the trichlorosilane liquid, greatly reducing the energy consumption required for vaporization.

[0069] After that, the mixed gas containing trichlorosilane gas and hydrogen gas in the bubbling vaporizer 1 flows into the gas-liquid separator 8 together. After being separated by the gas-liquid separator 8, the trichlorosilane small liquid droplets that may be entrained are removed. The trichlorosilane small liquid droplets flow into the trichlorosilane liquid storage tank through the liquid outlet pipeline 12 on the gas-liquid separator 8. The mixed gas after gas-liquid separation is introduced into the polysilicon production reduction furnace through the gas outlet pipeline 11 on the gas-liquid separator 8 to achieve feeding.

[0070] In addition, ultrasonic waves (such as 50 - 60 kHz) are fed around the membrane layer unit 3 through the ultrasonic unit 4, so that the hydrogen nanobubbles remaining in the pores of the oil-repellent breathable membrane can escape as soon as possible, and the "cavitation" phenomenon is generated inside the trichlorosilane liquid, so that tens of thousands of tiny bubbles (the inside of the bubbles is trichlorosilane gas) are quickly generated in the trichlorosilane liquid and quickly burst. At the moment when the bubbles burst, a huge instantaneous pressure and temperature will be generated, thereby enhancing the vaporization efficiency of trichlorosilane.

[0071] Moreover, in the above process, the cascade control unit tracks the liquid level change of the bubbling vaporizer 1 and the feeding flow rate change of the trichlorosilane liquid, adjusts the feeding flow rate of the trichlorosilane liquid, so as to accurately control the feeding amount of the trichlorosilane gas. The specific control logic and process are not elaborated here one by one. And, through the ratio control unit, according to the preset ratio of the trichlorosilane liquid feeding flow rate to the hydrogen feeding flow rate, the feeding flow rate of hydrogen is further adjusted, so as to accurately control the feeding amount of hydrogen and the feeding ratio of trichlorosilane gas to hydrogen. The specific control logic and process are not elaborated here one by one. In addition, through the feedback control unit, tracking the flow rate change of the material in front of the reduction furnace (that is, the mixed gas of trichlorosilane gas and hydrogen obtained after gas-liquid separation), the temperature of the heat medium for heating the trichlorosilane liquid is adjusted. And, through the liquid level and temperature alarm unit, abnormal situations such as the liquid level of the bubbling vaporizer 1 exceeding its preset value or the temperature inside the device of this embodiment exceeding its preset value are alarmed to ensure the operation stability and safety of the device.

[0072] The feeding device for the polysilicon production reduction furnace of this embodiment has at least the following advantages compared with the prior art:

[0073] (1) By setting the membrane layer unit, the structure of the bubbling vaporizer is innovatively improved, so that the hydrogen gas introduced into the trichlorosilane liquid can be transformed into nanobubbles under a smaller pressure drop, increasing the gas-liquid two-phase phase interface and making trichlorosilane generate more "vaporization centers", thereby effectively reducing the vaporization energy consumption.

[0074] (2) By setting the control system, the feeding amounts and feeding ratios of trichlorosilane gas and hydrogen can be accurately controlled. Moreover, the temperature of the heat medium can also be adjusted, thereby improving the polysilicon reduction production efficiency and the quality of polysilicon.

[0075] (3) By setting up the ultrasonic unit, not only can the nano - micro bubbles in the film layer unit escape and rupture as soon as possible, enabling the gas to escape from the bubbles as soon as possible, but also the "cavitation" phenomenon can be generated inside the trichlorosilane liquid, causing tens of thousands of tiny bubbles containing trichlorosilane gas to be rapidly generated inside the trichlorosilane liquid. By utilizing the huge instantaneous pressure and temperature generated when these tiny bubbles rupture, the vaporization efficiency of trichlorosilane can be further enhanced.

[0076] (4) By setting up the liquid level and temperature alarm system, abnormal situations such as the liquid level of the bubbling vaporizer exceeding its preset value or the temperature inside the device exceeding its preset value can be alarmed, further ensuring the operation stability and safety of the device.

[0077] It can be understood that the above - mentioned embodiments are merely exemplary embodiments adopted to illustrate the principle of the present invention. However, the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also regarded as the protection scope of the present invention.

Claims

1. A feeding device for a reduction furnace in polysilicon production, comprising a bubbling vaporizer (1) and a gas-liquid separator (8), characterized in that, It further includes a film layer unit (3) and a control system. A trichlorosilane feed pipeline (10) and a hydrogen feed pipeline (9) are connected to the bubbling vaporizer, which are respectively used for introducing trichlorosilane liquid and hydrogen. The film layer unit is arranged inside the bubbling vaporizer and is used to generate nano / micro bubbles of hydrogen in the trichlorosilane liquid in the bubbling vaporizer. Among them, the film layer unit includes a plate-type film and a support. The plate-type film is an oil-repellent and breathable film and is installed inside the bubbling vaporizer through the support. The nano / micro bubbles are generated when hydrogen passes through the plate-type film. The control system is used to track the liquid level change of the bubbling vaporizer and the feed flow rate change of the trichlorosilane liquid to adjust the feed flow rate of the trichlorosilane liquid, and, according to the preset ratio of the feed flow rate of the trichlorosilane liquid to the feed flow rate of hydrogen, adjust the feed flow rate of hydrogen, so as to accurately control the feed flow rates of trichlorosilane gas and hydrogen and their feed ratio.

2. The feeding device for a reduction furnace used in polysilicon production according to claim 1, wherein It further includes an ultrasonic unit (4). The ultrasonic unit is connected to the bubbling vaporizer and is used to feed ultrasonic waves around the film layer unit to make the nano / micro bubbles quickly escape and burst, and, generate a cavitation phenomenon.

3. The feeding device for a polysilicon production reduction furnace according to claim 2, characterized in that, It further includes a gas distributor (6). The gas distributor is arranged inside the bubbling vaporizer and is used to preliminarily disperse the hydrogen introduced into the vaporization bubbling device, so that the hydrogen uniformly passes through the film layer unit.

4. The feeding device for a polysilicon production reduction furnace according to claim 3, characterized in that, The gas distributor adopts a spray head type structure, which includes a delivery pipe and a spray head. One end of the delivery pipe is connected to the hydrogen feed pipeline, and the other end is connected to the spray head. A number of air holes (15) are provided on the spray head, and the air holes are evenly distributed.

5. The feeding device for a reduction furnace used in polysilicon production according to any one of claims 1 to 3, characterized in that, A heating system (5) is further arranged inside the bubbling vaporizer. The heating system includes a heat medium flow channel, and the heat medium flow channel extends into the inside of the bubbling vaporizer and is used to introduce a heat medium to heat-exchange and heat the trichlorosilane liquid.

6. The feeding device for a reduction furnace used in polysilicon production according to claim 5, wherein, The control system includes a cascade control unit and a ratio control unit. The cascade control unit includes a liquid level gauge, a first flowmeter, a first controller, and a computer system. The liquid level gauge is arranged on the bubbling vaporizer, and the first flowmeter and the first controller are both arranged on the trichlorosilane feed pipeline. The computer system is electrically connected to the liquid level gauge and the first controller respectively to form a main adjustment unit. A trichlorosilane liquid feed flow rate threshold is preset in the computer system. The liquid level gauge is used to detect the liquid level inside the bubbling vaporizer and transmit the detected liquid level signal to the computer system. The computer system is used to convert the liquid level signal into a trichlorosilane liquid feed flow rate value and compare it with the trichlorosilane liquid feed flow rate threshold, and, according to the comparison result, send a first control instruction to the first controller. The first controller is used to adjust the feed flow rate of the trichlorosilane liquid according to the first control instruction. The computer system is also electrically connected to the first flowmeter. The first flowmeter, the computer system, and the first controller form a secondary adjustment unit. The first flowmeter is used to detect the feed flow rate of trichlorosilane liquid and transmit the detected first flow signal to the computer system. The computer system is used to receive the first flow signal to obtain the real-time feed flow rate value of trichlorosilane liquid and compare it with the feed flow rate threshold of trichlorosilane liquid. Moreover, according to the comparison result, a second control instruction is sent to the first controller, and the first controller is also used to adjust the feed flow rate of trichlorosilane liquid according to the second control instruction; The ratio control unit includes a second flowmeter, a third flowmeter, a second controller, and a computer system. The second flowmeter is arranged on the trichlorosilane feed pipeline, and the third flowmeter and the second controller are both arranged on the hydrogen feed pipeline. The computer system is also electrically connected to the second flowmeter, the third flowmeter, and the second controller respectively. A feed flow rate ratio threshold of trichlorosilane liquid and hydrogen is also preset in the computer system. The second flowmeter is used to detect the feed flow rate of trichlorosilane liquid and transmit the detected second flow signal to the computer system. The third flowmeter is used to detect the feed flow rate of hydrogen and transmit the detected third flow signal to the computer system. The computer system is also used to receive the second flow signal to obtain the real-time feed flow rate value of trichlorosilane liquid and receive the third flow signal to obtain the real-time feed flow rate value of hydrogen, and compare the ratio of the real-time feed flow rate value of trichlorosilane liquid to the real-time feed flow rate value of hydrogen with the feed flow rate ratio threshold of trichlorosilane liquid and hydrogen. Moreover, according to the comparison result, a third control instruction is sent to the second controller, and the second controller is used to adjust the feed flow rate of hydrogen according to the third control instruction.

7. The feeding device for a polysilicon production reduction furnace according to claim 6, characterized in that, A hydrogen feed flow rate threshold is also preset in the computer system. The computer system is also used to compare the real-time hydrogen feed flow rate with the hydrogen feed flow rate threshold and send a fourth control instruction to the second controller according to the comparison result. The second controller is also used to control and adjust the feed flow rate of hydrogen according to the fourth control instruction.

8. The feeding device for a polysilicon production reduction furnace according to claim 7, characterized in that, The control unit also includes a feedback control unit. The feedback control unit includes a fourth flowmeter, a third controller, and a computer system. The fourth flowmeter is arranged on the gas outlet pipeline of the gas-liquid separator, and the third controller is arranged on the inlet pipeline of the heat medium flow channel. The computer system is also electrically connected to the third controller and the fourth flowmeter respectively. A heat medium temperature threshold is also preset in the computer system. The fourth flowmeter is used to detect the flow rate of the mixed gas output by the gas-liquid separator and transmit the detected fourth flow signal to the computer system. The computer system is also used to receive the fourth flow signal and convert it into a heat medium temperature value, and compare the heat medium temperature value with the heat medium temperature threshold, and send a fourth control signal to the third controller according to the comparison result. The third controller is used to adjust the heat medium temperature according to the fourth control signal.

9. The feeding device for a polysilicon production reduction furnace according to claim 5, characterized in that, The bubbling vaporizer is provided with a vent valve (2) and a residual liquid drain valve (7). The vent valve is arranged at the upper part of the bubbling vaporizer and is used for relieving pressure of the bubbling vaporizer. The residual liquid drain valve is arranged at the bottom of the bubbling vaporizer and is used for discharging the trichlorosilane residual liquid at the bottom of the bubbling vaporizer.

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