Blowback system for polycrystalline silicon tail gas adsorption device and control method of blowback system

Abstract

The invention relates to a back flushing system of a polycrystalline silicon tail gas adsorption device. The back flushing system comprises a hydrogen pipeline; the output ends of the nitrogen pipeline and the hydrogen pipeline are connected; the inlet end of the heating assembly is connected with the output ends of the nitrogen pipeline and the hydrogen pipeline; the outlet end of the adsorption assembly is connected to the outlet end of the heating assembly; the inlet end of the tail gas recovery system is connected with the outlet end of the adsorption assembly. According to the invention, by adding the heating assembly in the system, the temperature of the blowback gas can be increased, so that the adsorption and desorption capacities of the gas are enhanced, and impurities are more easily desorbed from the adsorption assembly.

Description

Technical Field

[0001] The invention relates to the technical field of polysilicon tail gas recovery, and in particular to the technical field of a backflush system of a polysilicon tail gas adsorption device. Background Art

[0002] In the production process of polysilicon, tail gas containing trichlorosilane (TCS), dichlorosilane (DCS), silicon tetrachloride (STS), hydrogen, hydrogen chloride and other gases will be generated. If these tail gases are directly discharged without treatment, they will cause serious pollution to the environment. Therefore, the development of effective tail gas recovery and treatment technology is crucial to the sustainable development of the polysilicon industry.

[0003] In the existing back-flushing adsorption technology, the adsorbed impurities such as chlorosilane and hydrogen chloride in the adsorption column are generally back-flushed directly through hydrogen and nitrogen pipelines; however, the back-flushing efficiency is relatively low and the impurities in the adsorption column cannot be effectively treated. Summary of the invention

[0004] The technical problem to be solved by the present invention is how to more quickly realize the backflushing of impurities in the adsorption column so that the impurities can be more efficiently resolved from the adsorption component.

[0005] In order to solve the above technical problems, a backflush system for a polysilicon tail gas adsorption device is provided according to the present invention, comprising:

[0006] Hydrogen pipelines;

[0007] A nitrogen pipeline, wherein the nitrogen pipeline is connected to an output end of the hydrogen pipeline;

[0008] A heating component, wherein the inlet end of the heating component is connected to the output ends of the nitrogen pipeline and the hydrogen pipeline;

[0009] An adsorption component, wherein the outlet end of the adsorption component is connected to the outlet end of the heating component;

[0010] A tail gas recovery system, wherein the inlet end of the tail gas recovery system is connected to the outlet end of the adsorption component.

[0011] Furthermore, the heating assembly includes a plurality of heating units, and all the heating units are connected in series.

[0012] Furthermore, a jumper pipe is provided on one side of the heating component, one end of the jumper pipe is connected to the inlet end of the heating component, and the other end of the jumper pipe is connected to a plurality of branch pipes; each branch pipe is connected in turn between every two heating units.

[0013] Furthermore, the jumper pipe is provided with a first switch valve, each branch pipe is provided with the second switch valve, and all the first and second switch valves are electrically connected to the control unit.

[0014] Furthermore, the hydrogen pipeline and the nitrogen pipeline are both provided with a third switch valve, and all the third switch valves are electrically connected to the control unit.

[0015] Furthermore, the adsorption assembly includes a plurality of adsorption units connected in parallel; the inlet end of the adsorption unit is connected to the material gas inlet, and the outlet of the adsorption unit is connected to the material gas outlet.

[0016] Furthermore, a temperature detector is provided at the outlet end of the heating component, and the temperature detector is electrically connected to the control unit.

[0017] Furthermore, the exhaust gas recovery system includes a regeneration condensation system and a waste gas pipeline network; the inlet ends of the regeneration condensation system and the waste gas pipeline network are connected to the inlet end of the adsorption component; a fourth switch valve is respectively provided between the regeneration condensation system and the waste gas pipeline network to the adsorption component, and all the fourth switch valves are electrically connected to the control unit.

[0018] A method for a backflush system for a polysilicon tail gas adsorption device, comprising the above-mentioned backflush system for a polysilicon tail gas adsorption device, comprises the following steps:

[0019] Step 1: The control unit opens the third switch valve of the hydrogen pipeline, and the hydrogen passes through the plurality of heating units in sequence for 48 hours; at the same time, the control unit opens the fourth switch valve of the regeneration condensing system;

[0020] Step 2: The control unit closes the third switch valve of the hydrogen pipeline; the control unit opens the third switch valve of the nitrogen pipeline, and the nitrogen passes through the plurality of heating units in sequence for 48 hours; at the same time, the control unit closes the fourth switch valve of the regeneration condensing system, and the control unit opens the fourth switch valve of the exhaust gas network;

[0021] Step three, the control unit closes the third switch valve of the nitrogen pipeline, and opens the third switch valve of the hydrogen pipeline; the hydrogen passes through one of the heating units for 24 hours; at the same time, the control unit closes the fourth switch valve of the exhaust gas network, and opens the fourth switch valve of the regeneration condensing system.

[0022] Furthermore, in step 1 and step 2, the temperature of the temperature sensor is 180°C; in step 3, the temperature of the temperature sensor is 60°C; the pressure of the hydrogen pipeline is 1.0MPa, and the flow rate is 1500Nm 3 / h; the pressure of the nitrogen pipeline is 0.7MPa, and the flow rate is 1500Nm 3 / h.

[0023] Compared with the prior art, the technical solution provided by the embodiments of the present invention can at least achieve the following beneficial effects:

[0024] First, the present invention can increase the temperature of the back-blowing gas by adding a heating component to the system, thereby enhancing the adsorption and desorption capabilities of the gas, making it easier to resolve impurities from the adsorption component.

[0025] Second, the present invention further increases the temperature of the gas by providing a heating assembly composed of a plurality of heating units connected in series, and can alleviate the damage to the pipeline caused by thermal shock, which helps to more thoroughly remove impurities in the adsorption assembly.

[0026] Third, the present invention can realize the control of a single heating unit through the design of jumper pipes and branch pipes, thereby realizing more stepped heating control and reducing the damage caused by heating; at the same time, due to the different heating temperatures used in different stages during the backblowing process, unnecessary energy waste is reduced.

[0027] Fourthly, the present invention can reduce the supply of hydrogen through the dual supply of nitrogen and hydrogen, thereby reducing the cost of gas supply and the corresponding energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments will be briefly introduced below. Obviously, the drawings in the following description only relate to some embodiments of the present invention, but are not intended to limit the present invention.

[0029] Figure 1 It is a cross-sectional schematic diagram of the main view of the present invention.

[0030] In the figure:

[0031] Hydrogen pipeline 1

[0032] Nitrogen pipeline 2

[0033] Heating element 3

[0034] Heating unit 31

[0035] Jumper pipe 32

[0036] Branch line 321

[0037] Temperature detector 33

[0038] Adsorption component 4

[0039] Adsorption unit 41

[0040] Material gas inlet 42

[0041] Material gas outlet 43

[0042] Exhaust gas recovery system 5

[0043] Regeneration condensation system 51

[0044] Exhaust pipe network 52

[0045] First on-off valve 61

[0046] The third switch valve 63

[0047] Fourth switch valve 64

[0048] Control unit 7 DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] Unless otherwise defined, the technical or scientific terms used herein shall have the common meanings understood by persons with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "a" do not indicate a quantity limitation, but indicate the existence of at least one.

[0051] refer to Figure 1 , this embodiment provides a recovery system for recovering chlorosilane, comprising:

[0052] Hydrogen pipeline 1;

[0053] A nitrogen pipeline 2, wherein the nitrogen pipeline 2 is connected to an output end of the hydrogen pipeline 1;

[0054] A heating component 3, the inlet end of the heating component 3 is connected to the output end of the nitrogen pipeline 2 and the hydrogen pipeline 1;

[0055] An adsorption component 4, wherein the outlet end of the adsorption component 4 is connected to the outlet end of the heating component 3;

[0056] The tail gas recovery system 5 has an inlet end connected to the outlet end of the adsorption component 4 .

[0057] The present invention realizes the supply of hydrogen through the hydrogen pipeline 1 and the supply of nitrogen through the nitrogen pipeline 2. By supplying hydrogen and nitrogen in stages, the adsorbed waste gas in the adsorption component 4 can be blown away by the backblowing gas (hydrogen and nitrogen) as much as possible and then be circulated and discharged in the exhaust gas recovery system 5; in addition, the present invention can activate the adsorption component 4 through the heating component 3, thereby maximizing the efficiency of backblowing the adsorbed waste gas.

[0058] In addition, since the present invention uses two gases, hydrogen and nitrogen, for backflushing, nitrogen can replace a portion of the hydrogen supply. Since hydrogen is more expensive and consumes more energy during its generation, the nitrogen supply of the present invention can save supply costs and corresponding energy consumption.

[0059] In a preferred embodiment, Figure 1 As shown, the heating assembly 3 includes a plurality of heating units 31, and all the heating units 31 are connected in series. The heating units 31 connected in series can create a pipeline with an increased temperature gradient, so that the passing gas (such as hydrogen and nitrogen) gradually increases in temperature when passing through each heating unit 31, which helps to heat more evenly and reduce hot spots.

[0060] In addition, since it is split into multiple heating units 31, effective heat recovery can be achieved; specifically, in Figure 1 In the case of two heating units 31, the front heating unit 31 can be a heat exchanger, and the rear heating unit 31 can be an electric heater; in this case, the heat exchanger can preheat the passing gas through the waste heat of other production processes, reducing the energy loss of the electric heater.

[0061] In a preferred embodiment, Figure 1 As shown, a jumper pipe 32 is also provided on one side of the heating assembly 3, one end of the jumper pipe 32 is connected to the inlet end of the heating assembly 3, and the other end of the jumper pipe 32 is connected to a plurality of branch pipes 321; each branch pipe 321 is sequentially connected between every two heating units 31. The present invention allows each heating unit 31 in the system of the heating assembly 3 to be controlled more independently by providing the jumper pipe 32, and a specific heating unit 31 can be enabled or disabled as needed to meet different heating requirements; specifically, Figure 1 For example, when the gas only needs to be heated to 60° C., the gas can be allowed to pass through the first heating unit 31 only, and when the gas needs to be heated to 180° C., only the second heating unit 31 is needed.

[0062] Furthermore, each heating unit 31 may be electrically connected to the control unit 7 ; the control unit 7 may flexibly turn on or off a specific heating unit 31 to meet different heating requirements.

[0063] by Figure 1 For example, there are actually two routes for making the gas reach 180°C; the first is to make the gas pass through two heating units 31 continuously to reach 180°C, that is, first heated to 60°C and then heated to 180°C; the second is to pass through the latter heating unit 31 through the jumper line 32 to reach 180°C; therefore, the present application can effectively provide two ways to achieve the required high temperature conditions, namely the energy-saving mode of the first line and the mode of quickly reaching the required temperature of the second line, so that the operator can choose according to actual needs.

[0064] In a preferred embodiment, Figure 1 As shown, the jumper pipe 32 is provided with a first switch valve 61, each branch pipe 321 is provided with a second switch valve (not shown in the figure), and all the first switch valves 61 and all the second switch valves are electrically connected to the control unit 7. By providing the second switch valve in the jumper pipe 32 and each branch pipe 321, the operator can independently control the activation and deactivation of the gas to each heating unit 31, that is, in the event of a control failure of the heating unit 31, the control of the gas flow can be guaranteed, thereby further improving the safety factor.

[0065] In a preferred embodiment, the hydrogen pipeline 1 and the nitrogen pipeline 2 are both provided with a third switch valve 63, and all the third switch valves 63 are electrically connected to the control unit 7. The present invention can centrally manage the supply of hydrogen and nitrogen by connecting the control unit 7, realize automatic control, and improve operating efficiency. That is, the operator can remotely control the opening and closing of the valve in the control room without having to operate on site in person, thereby improving safety and convenience. In addition, since hydrogen has the dangerous characteristics of being flammable and explosive, if a leak or system failure is detected, the control unit 7 can quickly cut off the gas supply to prevent the accident from expanding.

[0066] In a preferred embodiment, the adsorption assembly 4 includes a plurality of adsorption units 41 connected in parallel; the inlet end of the adsorption unit 41 is connected to the material gas inlet 42, and the outlet of the adsorption unit 41 is connected to the material gas outlet 43. The arrangement of the plurality of adsorption units 41 can work simultaneously, thereby improving the adsorption efficiency of impurities such as chlorosilane, and ensuring that impurities in the tail gas are effectively removed; in addition, if a certain adsorption unit 41 needs maintenance or replacement, the other units can still continue to work, which improves the reliability of the system and the flexibility of operation. Specifically, the waste gas discharged from other processes, such as impurities such as chlorosilane, will enter from the material gas inlet 42, and then be discharged from the material gas outlet 43; this work will be completed before the backblowing work begins.

[0067] In a preferred embodiment, a temperature detector 33 is provided at the outlet end of the heating component 3, and the temperature detector 33 is electrically connected to the control unit 7. The temperature detector 33 is connected to the control unit 7 through electronic communication, so that the monitoring data can be transmitted to the control system in a timely manner. By accurately controlling the temperature, energy waste can be avoided and heating efficiency can be improved.

[0068] In addition, the control unit 7 can use a programmable logic controller (PLC) to achieve precise control of the entire system; the PLC can be electrically connected to the temperature detector 33, and the PLC can collect temperature data in real time to ensure that the temperature of the gas in the heating component 3 meets the process requirements; the PLC can automatically control the start and stop of the heating unit 31, and automatically adjust the heating power according to the feedback of the temperature sensor 33; and through the control of each development valve, the flow direction of the gas flow is controlled. In addition, the PLC is usually equipped with an operation panel and a display, so that the operator can easily view the system status, adjust the settings and manually override the automatic control. The present invention mainly describes the control steps of each pipeline and heating unit, so the electrical connection between the PLC and each component is not repeated here, and the existing PLC and each electrical component connection structure are referred to.

[0069] In a preferred embodiment, the tail gas recovery system 5 includes a regeneration condensation system 51 and an exhaust gas network 52; the inlet ends of the regeneration condensation system 51 and the exhaust gas network 52 are connected to the inlet end of the adsorption assembly 4; a fourth switch valve 64 is respectively provided between the regeneration condensation system 51 and the exhaust gas network 52 and the adsorption assembly 4, and all the fourth switch valves 64 are electrically connected to the control unit 7. The operator can adjust the treatment process of the tail gas according to the process requirements by controlling the fourth switch valve 64, for example, the tail gas can be directly discharged to the exhaust gas network 52, or processed and recovered through the regeneration condensation system 51.

[0070] In a preferred embodiment, a heat exchanger is provided at the regeneration condensation system 51, and the heat exchanger can use the waste heat in the system to preheat the gas in the regeneration condensation system to reduce energy consumption. In addition, through effective heat exchange, the dependence on external energy can be reduced and the operating cost of the system can be reduced. An air cooler is provided at the exhaust gas pipe network 52. The air cooler can effectively cool the exhaust gas and improve the condensation efficiency.

[0071] A method for a backflush system for a polysilicon tail gas adsorption device, comprising the above-mentioned backflush system for a polysilicon tail gas adsorption device, comprises the following steps:

[0072] Step 1: Hydrogen backflush and condensation regeneration;

[0073] Start-up phase: the control unit 7 operates the third switch valve 63 to open the hydrogen pipeline 1 , allowing hydrogen to flow into the multiple heating units 31 of the heating assembly 3 .

[0074] Heating stage: Hydrogen passes through each heating unit 31 in sequence, and each unit is provided with a temperature detector 33 to ensure that the temperature of the gas reaches 180°C when passing through.

[0075] Duration: The process of hydrogen passing through the heating unit lasts for 48 hours to ensure that impurities such as chlorosilane and hydrogen chloride in the adsorption component 4 are effectively backflushed.

[0076] Condensation regeneration: At the same time, the control unit 7 operates the fourth switch valve 64 to open the regeneration condensation system 51 to prepare for receiving the heated hydrogen.

[0077] Step 2: Nitrogen backflush and exhaust gas discharge;

[0078] Switching stage: the control unit 7 closes the third switch valve 63 of the hydrogen pipeline to stop the supply of hydrogen.

[0079] Starting nitrogen: the control unit 7 opens the third switch valve 63 of the nitrogen pipeline to allow nitrogen to flow into the multiple heating units 31 of the heating assembly 3 .

[0080] Heating stage: Nitrogen also passes through each heating unit 31, and the temperature detector 33 monitors and maintains the gas temperature at 180°C.

[0081] Duration: The process of passing nitrogen through the heating unit also lasts for 48 hours to ensure that the silane in the adsorption assembly 4 is purged.

[0082] Exhaust gas emission: the control unit 7 closes the fourth switch valve 64 of the regeneration condensation system, and simultaneously opens the fourth switch valve 64 of the exhaust gas pipe network 52 to emit the treated nitrogen to the exhaust gas pipe network.

[0083] Step 3: Hydrogen backflush and system preparation

[0084] Switching stage: the control unit 7 closes the third switch valve 63 of the nitrogen pipeline to stop the supply of nitrogen.

[0085] Restarting hydrogen: the control unit 7 reopens the third switch valve 63 of the hydrogen pipeline to allow hydrogen to flow into a heating unit 31 of the heating assembly 3 .

[0086] Heating stage: Hydrogen passes through the heating unit, and the temperature detector 33 monitors and maintains the gas temperature at 60°C.

[0087] Duration: The process of hydrogen passing through the heating unit lasts for 24 hours to ensure that the nitrogen in the adsorption assembly 4 is completely removed.

[0088] System preparation: The control unit 7 closes the fourth switch valve 64 of the exhaust gas pipe network and reopens the fourth switch valve 64 of the regeneration condensation system to prepare for receiving the heated hydrogen.

[0089] In the above process, the pressure of hydrogen pipeline 1 is maintained at 1.0MPa and the flow rate is controlled at 1500Nm 3 / h; the pressure of nitrogen pipeline 2 is maintained at 0.7MPa, and the flow rate is also controlled at 1500Nm 3 / h. This precisely controlled backflushing method can effectively remove impurities from the adsorption components, improve the efficiency of the tail gas recovery system, and ensure the environmental sustainability of polysilicon production.

[0090] In order to achieve the above-mentioned purpose of real-time monitoring of the pressure and flow in the pipeline and ensure the stability and uniformity of the gas supply, the nitrogen pipeline 1 and the hydrogen pipeline 2 are both provided with a pressure sensor and a flow sensor.

[0091] The above description is merely an exemplary embodiment of the present invention and is not intended to limit the protection scope of the present invention. The protection scope of the present invention is determined by the appended claims.

Claims

1. A backflush system for a polysilicon tail gas adsorption device, characterized in that: Hydrogen pipelines; A nitrogen pipeline, wherein the nitrogen pipeline is connected to an output end of the hydrogen pipeline; A heating component, wherein the inlet end of the heating component is connected to the output ends of the nitrogen pipeline and the hydrogen pipeline; An adsorption component, wherein the outlet end of the adsorption component is connected to the outlet end of the heating component; A tail gas recovery system, wherein the inlet end of the tail gas recovery system is connected to the outlet end of the adsorption component.

2. A backflush system for a polysilicon tail gas adsorption device according to claim 1, characterized in that: The heating assembly includes a plurality of heating units, and all the heating units are connected in series.

3. A backflush system for a polysilicon tail gas adsorption device according to claim 2, characterized in that: A jumper pipe is also provided on one side of the heating component, one end of the jumper pipe is connected to the inlet end of the heating component, and the other end of the jumper pipe is connected to a plurality of branch pipes; each branch pipe is sequentially connected between every two heating units.

4. The backflush system for a polysilicon tail gas adsorption device according to claim 1, characterized in that: The jumper pipe is provided with a first switch valve, each branch pipe is provided with the second switch valve, and all the first and second switch valves are electrically connected to the control unit.

5. A backflush system for a polysilicon tail gas adsorption device according to claim 4, characterized in that: The hydrogen pipeline and the nitrogen pipeline are both provided with a third switch valve, and all the third switch valves are electrically connected to the control unit.

6. A backflush system for a polysilicon tail gas adsorption device according to claim 4, characterized in that: The adsorption assembly comprises a plurality of adsorption units connected in parallel; the inlet end of the adsorption unit is connected to the material gas inlet, and the outlet of the adsorption unit is connected to the material gas outlet.

7. A backflush system for a polysilicon tail gas adsorption device according to claim 6, characterized in that: A temperature detector is provided at the outlet end of the heating component, and the temperature detector is electrically connected to the control unit.

8. The backflush system for a polysilicon tail gas adsorption device according to claim 7, characterized in that: The exhaust gas recovery system includes a regeneration condensation system and a waste gas pipeline network; the inlet ends of the regeneration condensation system and the waste gas pipeline network are connected to the inlet end of the adsorption component; a fourth switch valve is respectively provided between the regeneration condensation system and the waste gas pipeline network to the adsorption component, and all the fourth switch valves are electrically connected to the control unit.

9. A control method for a backflush system of a polysilicon tail gas adsorption device, characterized in that: A backflush system for a polysilicon tail gas adsorption device according to claim 1 to claim 7, comprising the following steps: Step 1: The control unit opens the third switch valve of the hydrogen pipeline, and the hydrogen passes through the plurality of heating units in sequence for 48 hours; at the same time, the control unit opens the fourth switch valve of the regeneration condensing system; Step 2: The control unit closes the third switch valve of the hydrogen pipeline; the control unit opens the third switch valve of the nitrogen pipeline, and the nitrogen passes through the plurality of heating units in sequence for 48 hours; at the same time, the control unit closes the fourth switch valve of the regeneration condensing system, and the control unit opens the fourth switch valve of the exhaust gas network; Step three, the control unit closes the third switch valve of the nitrogen pipeline, and opens the third switch valve of the hydrogen pipeline; the hydrogen passes through one of the heating units for 24 hours; at the same time, the control unit closes the fourth switch valve of the exhaust gas network, and opens the fourth switch valve of the regeneration condensing system.

10. The method for a backflush system for a polysilicon tail gas adsorption device according to claim 9, characterized in that: In step one and step two, the temperature of the temperature sensor is 180°C; in step three, the temperature of the temperature sensor is 60°C; the pressure of the hydrogen pipeline is 1.0MPa, and the flow rate is 1500Nm / h; the pressure of the nitrogen pipeline is 0.7MPa, and the flow rate is 1500Nm / h.

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