Back blowing system of polycrystalline silicon tail gas adsorption device

Abstract

The utility model relates to a blowback system of a polycrystalline silicon tail gas adsorption device. The blowback 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 utility model, the heating component is additionally arranged in the system, so that the temperature of the blowback gas can be increased, the adsorption and desorption capabilities of the gas are enhanced, and impurities are more easily desorbed from the adsorption component.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of polycrystal silicon tail gas recovery, especially to the technical field of the back flushing system of polycrystal silicon tail gas adsorption device. BACKGROUND

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

[0003] In the existing back flushing adsorption technology, hydrogen and nitrogen pipelines are generally used to directly back flush the adsorbed chlorosilane, hydrogen chloride and other impurities in the adsorption column. However, the back flushing efficiency is relatively low, and the treatment of impurities in the adsorption column cannot be effectively realized. UTILITY MODEL CONTENT

[0004] The technical problem to be solved by the utility model is how to more quickly realize back flushing of impurities in the adsorption column, so that the impurities can be more efficiently desorbed from the adsorption assembly.

[0005] To solve the above technical problems, according to the utility model, a back flushing system of polycrystal silicon tail gas adsorption device is provided, which comprises:

[0006] A hydrogen pipeline;

[0007] A nitrogen pipeline, the output end of the nitrogen pipeline is connected with the output end of the hydrogen pipeline;

[0008] A heating assembly, the inlet end of the heating assembly is connected with the output end of the nitrogen pipeline and the output end of the hydrogen pipeline;

[0009] An adsorption assembly, the outlet end of the adsorption assembly is connected with the outlet end of the heating assembly;

[0010] A tail gas recovery system, the inlet end of the tail gas recovery system is connected with the outlet end of the adsorption assembly.

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

[0012] Further, the heating assembly is further provided with a cross connection pipeline on one side, one end of the cross connection pipeline is connected with the inlet end of the heating assembly, and the other end of the cross connection pipeline is connected with a plurality of branch pipelines; each branch pipeline is connected between every two heating units in turn.

[0013] Further, the cross connection pipeline is provided with a first switch valve, each branch pipeline is provided with a second switch valve, and all the first and second switch valves are electrically connected to a control unit.

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

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

[0016] Further, the outlet end of the heating assembly is provided with a temperature detector, and the temperature detector is electrically connected to the control unit.

[0017] Further, the tail gas recovery system comprises a regenerative condensing system and a waste gas pipeline network, the inlet end of the regenerative condensing system and the waste gas pipeline network is connected to the inlet end of the adsorption assembly, a fourth switch valve is arranged between the regenerative condensing system and the waste gas pipeline network and the adsorption assembly, and all the fourth switch valves are electrically connected to the control unit.

[0018] Further, the nitrogen pipeline and the hydrogen pipeline are each provided with a pressure sensor and a flow sensor.

[0019] Further, the regenerative condensing system is provided with a heat exchanger, and the waste gas pipeline network is provided with an air cooler.

[0020] Compared with the prior art, the technical scheme provided by the embodiment of the utility model has at least the following beneficial effects:

[0021] Firstly, the utility model adds a heating assembly in the system, which can improve the temperature of the back-blowing gas, thereby enhancing the adsorption and desorption capacity of the gas, and making the impurities more easily desorbed from the adsorption assembly.

[0022] Secondly, the heating assembly is connected by a plurality of heating units in series, which further improves the temperature of the gas, relieves the damage of thermal shock to the pipeline, and helps to more completely remove the impurities in the adsorption assembly.

[0023] Thirdly, the design of the cross connection pipeline and the branch pipeline can control a single heating unit, 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 back-blowing process, unnecessary energy waste is reduced.

[0024] Fourthly, the double supply of nitrogen and hydrogen can reduce the supply of hydrogen, thereby reducing the cost of gas supply and the corresponding energy consumption. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of this utility model, the accompanying drawings of the embodiments will be briefly introduced below. Obviously, the drawings described below only involve some embodiments of this utility model, and are not intended to limit this utility model.

[0026] Figure 1 This is a schematic diagram of the backflushing system of a polycrystalline silicon tail gas adsorption device according to this utility model. In the figure:

[0027] Hydrogen pipeline 1

[0028] Nitrogen pipeline 2

[0029] Heating component 3

[0030] Heating unit 31

[0031] Overpass Pipeline 32

[0032] Branch pipe 321

[0033] Temperature detector 33

[0034] Adsorption component 4

[0035] Adsorption unit 41

[0036] Material gas inlet 42

[0037] Material gas outlet 43

[0038] Exhaust gas recovery system 5

[0039] Regenerative Condensation System 51

[0040] Exhaust gas pipeline network 52

[0041] First switching valve 61

[0042] Third switching valve 63

[0043] Fourth switching valve 64

[0044] Control Unit 7 Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the described embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0046] Unless otherwise defined, technical terms or scientific terms used herein shall have the same meaning as commonly understood by one of ordinary skill in the art to which this patent belongs. The terms "first", "second", and similar terms do not imply any order, quantity, or importance, but are used to distinguish one element from another, and are used only to assist with description of the exemplary embodiments. Similarly, the terms "one" or "a" or "an" do not limit the quantity of defined or described elements to one.

[0047] Reference Figure 1 The embodiment provides a back flushing system of a polysilicon tail gas adsorption device, which comprises:

[0048] a hydrogen pipeline 1;

[0049] a nitrogen pipeline 2, the output end of the nitrogen pipeline 2 being connected with the output end of the hydrogen pipeline 1;

[0050] a heating assembly 3, the input end of the heating assembly 3 being connected with the output end of the nitrogen pipeline 2 and the output end of the hydrogen pipeline 1;

[0051] an adsorption assembly 4, the output end of the adsorption assembly 4 being connected with the output end of the heating assembly 3;

[0052] a tail gas recovery system 5, the input end of the tail gas recovery system 5 being connected with the output end of the adsorption assembly 4.

[0053] The hydrogen pipeline 1 is used to supply hydrogen, and the nitrogen pipeline 2 is used to supply nitrogen. The hydrogen and nitrogen are supplied in stages, so that the adsorbed waste gas in the adsorption assembly 4 can be blown away by the back flushing gas (hydrogen and nitrogen) as much as possible and then recycled in the tail gas recovery system 5. In addition, the heating assembly 3 can activate the adsorption assembly 4, so as to improve the efficiency of back flushing the adsorbed waste gas as much as possible.

[0054] In addition, the two kinds of hydrogen and nitrogen are used for back flushing in the utility model, so that the nitrogen can replace a part of the supply of hydrogen. Since the price of hydrogen is higher and more energy is consumed in the generation of hydrogen, the supply of nitrogen in the utility model can save the supply cost and the corresponding energy consumption.

[0055] In a preferred embodiment, as shown in Figure 1 The heating assembly 3 comprises a plurality of heating units 31, and all the heating units 31 are connected in series. The series-connected heating units 31 can create a pipeline with a temperature gradient rising, so that the gas (such as hydrogen and nitrogen) passing through the pipeline is gradually heated when passing through each heating unit 31, which helps to more uniformly heat and reduce hot spots.

[0056] In addition, since the heating units 31 are split into multiple, efficient heat recovery can be achieved; specifically, in the case of two heating units 31, the first heating unit 31 can be a heat exchanger, and the second 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. Figure 1

[0057] In a preferred embodiment, as shown in Figure 1 one side of the heating assembly 3 is also provided with a bypass line 32, one end of the bypass line 32 is connected to the inlet end of the heating assembly 3, and the other end of the bypass line 32 is connected to multiple branch lines 321; each branch line 321 is connected between every two heating units 31. The present application allows each heating unit 31 in the system of the heating assembly 3 to be more independently controlled by setting the bypass line 32, and specific heating units 31 can be enabled or closed as needed to adapt to different heating needs; specifically, taking Figure 1 60℃ as an example, the gas can only pass through the first heating unit 31, and when heating to 180℃ is required, only the second heating unit 31 is needed.

[0058] Further, each heating unit 31 can be electrically connected to the control unit 7; the control unit 7 can flexibly turn on or off specific heating units 31 to adapt to different heating needs.

[0059] Taking Figure 1 as an example, there are actually two lines for the gas to reach 180℃; the first is to make the gas pass through two heating units 31 in succession, so as to reach 180℃, that is, first heated to 60℃, and then heated to 180℃; the second is to pass through the second heating unit 31 through the bypass line 32, so as to reach 180℃; therefore, the present application can effectively provide two ways to achieve the required high temperature condition, that is, 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.

[0060] In a preferred embodiment, as shown in Figure 1 the bypass line 32 is provided with a first switch valve 61, and each branch line 321 is provided with a second switch valve (not shown in the figure), and all first switch valves 61 and all second switch valves are electrically connected to the control unit 7. By providing a second switch valve in the bypass line 32 and each branch line 321, the operator can independently control the enablement and closure of the gas to each heating unit 31, that is, in the case of control failure of the heating unit 31, the control of the gas flow can be ensured, further improving the safety factor.

[0061] ​In a preferred embodiment, the hydrogen pipeline 1 and the nitrogen pipeline 2 are each provided with a third switch valve 63, and all the third switch valves 63 are electrically connected to the control unit 7. Through the connection of the control unit 7, the supply of hydrogen and nitrogen can be centrally managed, realizing automatic control and improving operational efficiency. That is, the operator can remotely control the opening and closing of the valve in the control room, without the need to operate on site, improving safety and convenience. In addition, due to the flammable and explosive nature of hydrogen, if a leak or system failure is detected, the control unit 7 can quickly cut off the gas supply to prevent the accident from spreading.

[0062] 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 multiple adsorption units 41 can work simultaneously, improving the adsorption efficiency of chlorosilane and other impurities and ensuring that impurities in the tail gas are effectively removed; in addition, if a certain adsorption unit 41 needs to be maintained or replaced, other units can still continue to work, which improves the reliability of the system and the flexibility of operation. Specifically, waste gas excluded by other processes, such as chlorosilane and other impurities, 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 backflushing work begins.

[0063] In a preferred embodiment, the outlet end of the heating assembly 3 is provided with a temperature detector 33, 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 precisely controlling the temperature, energy waste can be avoided and heating efficiency can be improved.

[0064] In addition, the control unit 7 can use a programmable logic controller (PLC) to realize precise control of the entire system; the PLC can be electrically connected to the temperature detector 33, the PLC can collect temperature data in real time, and ensure that the temperature of the gas in the heating assembly 3 meets the process requirements; the PLC can automatically control the start and stop of the heating unit 31, automatically adjust the heating power according to the feedback of the temperature sensor 33; and by controlling the various development valves, the flow direction of the gas flow can be controlled. In addition, the PLC is usually equipped with an operation panel and a display, so that the operator can easily check the system status, adjust the settings and manually override the automatic control. The utility model mainly describes the control steps of the various pipelines and heating units, so the electrical connection of the PLC and the components will not be described again, and the connection structure of the existing PLC and electrical components can be referred to.

[0065] In a preferred embodiment, the tail gas recovery system 5 comprises a regenerative condensing system 51 and a waste gas pipe network 52; the inlet end of the regenerative condensing system 51 and the waste gas pipe network 52 are connected to the inlet end of the adsorption assembly 4; a fourth switch valve 64 is respectively arranged between the regenerative condensing system 51 and the waste gas pipe network 52 and the adsorption assembly 4, and all the fourth switch valves 64 are electrically connected to the control unit 7. By controlling the fourth switch valve 64, the operator can adjust the processing flow of the tail gas according to the process requirements, for example, the tail gas can be directly discharged to the waste gas pipe network 52 or processed and recovered through the regenerative condensing system 51.

[0066] In a preferred embodiment, a heat exchanger is arranged at the regenerative condensing system 51, which can utilize the waste heat in the system to preheat the gas in the regenerative condensing system, thereby reducing energy consumption. In addition, through effective heat exchange, the dependence on external energy can be reduced, and the operation cost of the system can be reduced. An air cooler is arranged at the waste gas pipe network 52. The air cooler can effectively cool the waste gas and improve the condensing efficiency.

[0067] A method of a back flushing system of a polysilicon tail gas adsorption device, comprising the back flushing system of the polysilicon tail gas adsorption device, comprising the following steps:

[0068] Step one: hydrogen back flushing and condensing regeneration;

[0069] Start-up phase: the control unit 7 operates the third switch valve 63 to open the hydrogen pipe 1, allowing hydrogen to flow into the plurality of heating units 31 of the heating assembly 3.

[0070] Heating phase: the hydrogen passes through each heating unit 31 in turn, and each unit is provided with a temperature detector 33 to ensure that the temperature of the gas reaches 180°C when passing through.

[0071] Duration: the process of hydrogen passing through the heating unit lasts for 48 hours to ensure that the impurities such as chlorosilane and hydrogen chloride in the adsorption assembly 4 are effectively back flushed.

[0072] Condensing regeneration: at the same time, the control unit 7 operates the fourth switch valve 64 to open the regenerative condensing system 51 to prepare to receive the heated hydrogen.

[0073] Step two: nitrogen back flushing and waste gas discharge;

[0074] Switching phase: the control unit 7 closes the third switch valve 63 of the hydrogen pipe to stop the supply of hydrogen.

[0075] Start nitrogen: the control unit 7 opens the third switch valve 63 of the nitrogen pipe to allow nitrogen to flow into the plurality of heating units 31 of the heating assembly 3.

[0076] Heating phase: nitrogen gas also passes through each heating unit 31, and the temperature detector 33 monitors and maintains the gas temperature at 180℃.

[0077] Duration: the process of nitrogen gas passing through the heating unit also lasts for 48 hours to ensure that the silane in the adsorption assembly 4 is completely removed.

[0078] Waste gas discharge: the control unit 7 closes the fourth on-off valve 64 of the regeneration condensing system and opens the fourth on-off valve 64 of the waste gas pipeline network 52 to discharge the treated nitrogen gas to the waste gas pipeline network.

[0079] Step three: hydrogen back flushing and system preparation

[0080] Switching phase: the control unit 7 closes the third on-off valve 63 of the nitrogen pipeline to stop the supply of nitrogen gas.

[0081] Hydrogen re-start: the control unit 7 re-opens the third on-off valve 63 of the hydrogen pipeline to allow the hydrogen gas to flow into one heating unit 31 of the heating assembly 3.

[0082] Heating phase: hydrogen gas passes through the heating unit, and the temperature detector 33 monitors and maintains the gas temperature at 60℃.

[0083] Duration: the process of hydrogen gas passing through the heating unit lasts for 24 hours to ensure that the nitrogen gas in the adsorption assembly 4 is completely removed.

[0084] System preparation: the control unit 7 closes the fourth on-off valve 64 of the waste gas pipeline network and re-opens the fourth on-off valve 64 of the regeneration condensing system to prepare to receive the heated hydrogen gas.

[0085] In the above process, the pressure of the hydrogen pipeline 1 is maintained at 1.0 MPa, and the flow is controlled at 1500 Nm 3 / h; the pressure of the nitrogen pipeline 2 is maintained at 0.7 MPa, and the flow is also controlled at 1500 Nm 3 / h. Through this precisely controlled back flushing method, the impurities in the adsorption assembly can be effectively removed, the efficiency of the tail gas recovery system can be improved, and the environmental sustainability of the polysilicon production can be ensured.

[0086] In order to achieve the above purpose of monitoring the pressure and flow in the pipeline in real time, 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.

[0087] The above only describes exemplary embodiments of the present application, and is not used to limit the protection scope of the present application, and the protection scope of the present application is determined by the appended claims.

Claims

1. A back flushing system of a polysilicon tail gas adsorption device, characterized in that, a hydrogen pipeline; a nitrogen pipeline, the output end of the nitrogen pipeline being connected with the output end of the hydrogen pipeline; a heating assembly, the inlet end of the heating assembly being connected with the output end of the nitrogen pipeline and the output end of the hydrogen pipeline; an adsorption assembly, the outlet end of the adsorption assembly being connected with the outlet end of the heating assembly; a tail gas recovery system, the inlet end of the tail gas recovery system being connected with the outlet end of the adsorption assembly.

2. The backflush system of a polysilicon exhaust adsorption device according to claim 1, wherein, The heating assembly comprises a plurality of heating units, all of which are connected in series.

3. The backflush system of a polysilicon exhaust adsorption device according to claim 2, wherein, The heating assembly is further provided with a cross-pipeline, one end of the cross-pipeline being connected with the inlet end of the heating assembly, and the other end of the cross-pipeline being connected with a plurality of branch pipelines; each of the branch pipelines is connected between every two of the heating units in sequence.

4. The backflush system of a polysilicon exhaust adsorption device according to claim 3, wherein, The cross-pipeline is provided with a first switch valve, and each of the branch pipelines is provided with a second switch valve, all of the first and second switch valves being electrically connected with a control part.

5. The backflush system of a polysilicon exhaust adsorption device according to claim 4, wherein, The hydrogen pipeline and the nitrogen pipeline are both provided with a third switch valve, all of the third switch valves being electrically connected with the control part.

6. The backflush system of a polysilicon exhaust adsorption device according to claim 4, wherein, The adsorption assembly comprises a plurality of adsorption units connected in parallel; the inlet end of the adsorption unit is connected with a material gas inlet, and the outlet of the adsorption unit is connected with a material gas outlet.

7. The backflush system of a polysilicon exhaust adsorption device according to claim 6, wherein, The outlet end of the heating assembly is provided with a temperature detector, the temperature detector being electrically connected with the control part.

8. The backflush system of a polysilicon exhaust adsorption device according to claim 7, wherein, The tail gas recovery system comprises a regeneration condensing system and a waste gas pipeline network; the inlet end of the regeneration condensing system and the waste gas pipeline network is connected with the inlet end of the adsorption assembly; a fourth switch valve is arranged between the regeneration condensing system and the waste gas pipeline network and the adsorption assembly, respectively, and all of the fourth switch valves are electrically connected with the control part.

9. The backflush system of a polysilicon exhaust adsorption device according to claim 7, wherein, The nitrogen pipeline and the hydrogen pipeline are both provided with a pressure sensor and a flow sensor.

10. The backflush system of a polysilicon exhaust adsorption device according to claim 8, wherein, The regeneration condensing system is provided with a heat exchanger, and the waste gas pipeline network is provided with an air cooler.

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