Heating assembly and back flushing system thereof

Abstract

The utility model relates to a heating assembly and a back flushing system thereof. The heating assembly comprises an adsorption assembly and a back flushing assembly, wherein the adsorption assembly comprises a plurality of adsorption columns; the inlet end of each adsorption column is provided with a hot-blowing back-blowing outlet path; a cold air outlet path is arranged between the inlet end of the hydrogen tank and the outlet end of each adsorption column; meanwhile, a cold air inlet path is arranged between the outlet end of the hydrogen tank and the inlet end of each adsorption column; the inlet end of the heating assembly is connected to the outlet end of the hydrogen tank, and a hot gas back-blowing inlet path is arranged between the outlet end of the heating assembly and the outlet end of each adsorption column. By controlling the heating frequency and temperature of the heating assembly, thermal damage to the adsorbent, the heating unit and the like can be avoided, so that the long-term stability and the service life are improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of tail gas recovery of polysilicon, especially to the technical field of a backflushing system. BACKGROUND

[0002] In the production process of polysilicon, tail gas recovery is an important link, aiming to improve the utilization rate of raw materials and reduce environmental pollution. In the prior art, adsorption columns are used to recover and purify useful components in tail gas, such as hydrogen and chlorosilane. However, as the use time of the adsorbent increases, a certain amount of impurities will accumulate on its surface, which will reduce the adsorption efficiency, so it is necessary to regularly perform backflushing activation to restore its performance.

[0003] Although partial hot gas backflushing and cold gas forward flushing techniques are adopted in the existing backflushing technology for consideration of energy consumption and cost, the phenomenon of heating component damage caused by hot gas backflushing and cold gas forward flushing is not considered in the prior art. In addition, a considerable part of the backflushing technology does not fully consider the problem of thermal damage caused by hot flushing. SUMMARY

[0004] The technical problem to be solved by the utility model is how to quickly and efficiently achieve backflushing effect while avoiding thermal damage to the adsorbent and heating component, improving long-term stability and service life.

[0005] To solve the above technical problems, the utility model provides a heating component, comprising:

[0006] A plurality of heating units are connected in series.

[0007] A temperature sensor is arranged at the outlet of the heating component.

[0008] A control unit is electrically connected to the temperature sensor and all the heating units.

[0009] Further, the control unit is a PLC controller, and the PLC controller controls all the heating units through a pulse width modulation signal.

[0010] A backflushing system comprises the above-mentioned heating component and comprises:

[0011] An adsorption component comprises a plurality of adsorption columns, and each adsorption column is provided with a hot flushing backflushing outlet at the inlet end.

[0012] A hydrogen tank is provided with a cold gas outlet between the inlet end of the hydrogen tank and the outlet end of each adsorption column, and is provided with a cold gas inlet between the outlet end of the hydrogen tank and the inlet end of each adsorption column.

[0013] The inlet end of the heating assembly is connected to the outlet end of the hydrogen tank, and a hot gas back-blowing passage is arranged between the outlet end of the heating assembly and the outlet end of each adsorption column.

[0014] Further, the inlet end of each adsorption column is connected to a tail gas inlet, and the outlet end of the same adsorption column is connected to the hydrogen tank through a tail gas outlet.

[0015] Further, a first switch valve is arranged at each of the tail gas inlet and the tail gas outlet; and a pressure boosting valve is connected in parallel to the first switch valve.

[0016] Further, all the hot-blowing back-blowing outlets are connected to an exhaust passage, and the hot-blowing back-blowing outlets and the hot-blowing back-blowing passages are each provided with a second switch valve, and a pressure relief valve is connected in parallel to the second switch valve.

[0017] Further, a third switch valve is arranged at each of the cold gas outlet and the cold gas inlet.

[0018] Further, a pressure sensor is arranged in each of the adsorption columns.

[0019] Further, an auxiliary heating structure can be arranged at the heating assembly.

[0020] Further, the auxiliary heating structure is a petal-shaped structure, a grid structure or a rice-shaped structure.

[0021] Compared with the prior art, the technical scheme provided by the embodiment of the present application can achieve at least the following beneficial effects:

[0022] Firstly, the present application can more effectively remove the residual substances in the adsorption column by using the combination of hot gas back-blowing and cold gas forward-blowing, thereby improving the adsorption efficiency of the adsorption column.

[0023] Secondly, the present application can avoid thermal damage to the adsorbent and the heating unit by controlling the heating frequency and temperature of the heating assembly, thereby improving the long-term stability and service life thereof.

[0024] Thirdly, the present application can ensure that the system can stably operate in different operation stages by automatically controlling the switch valves of the heating assembly and the adsorption column.

[0025] Fourthly, the present application can avoid greater loss caused by the damaged heating unit by setting an upper preset value to protect the heating assembly, can timely repair, and prolong the service life of the equipment. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical scheme of the embodiments of the present application, the drawings of the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description only relate to some embodiments of the present application and are not intended to limit the present application.

[0027] Figure 1 A gas circuit structure diagram of the present application;

[0028] Figure 2 A schematic diagram of an auxiliary heating structure of the present application;

[0029] Figure 3 A schematic diagram of an auxiliary heating structure of the present application;

[0030] Figure 4 A schematic diagram of an auxiliary heating structure of the present application.

[0031] In the drawings:

[0032] Adsorption column A;

[0033] Adsorption column B;

[0034] Adsorption column C;

[0035] Tail gas inlet 111;

[0036] Tail gas outlet 112;

[0037] Pressure boosting valve 114;

[0038] Pressure relief valve 115;

[0039] Hydrogen tank 2;

[0040] Heating unit 3;

[0041] Heating unit 31;

[0042] Hot blow back inlet 41;

[0043] Hot blow back outlet 42;

[0044] First on-off valve 51;

[0045] Second on-off valve 52;

[0046] Third on-off valve 53;

[0047] Cold gas outlet 61;

[0048] Cold gas inlet 62;

[0049] First arc-shaped structure 71;

[0050] Second arc-shaped structure 72. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme of the embodiments of the utility model will be described clearly and completely below in combination with the drawings of the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, rather than all the embodiments. Based on the described embodiments of the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the utility model.

[0052] Unless otherwise defined, the technical terms or scientific terms used herein should be understood as the usual meanings understood by those skilled in the art to which the utility model belongs. The "first", "second" and similar words used in the utility model patent application description and claims do not represent any order, quantity or importance, but are only used to distinguish different components. Similarly, "one" or "a" and similar words do not represent a quantity limit, but represent the existence of at least one.

[0053] Reference Figure 1 The embodiment provides a heating assembly, which comprises:

[0054] A plurality of heating units 31 are connected in series.

[0055] A temperature sensor is arranged at the outlet of the heating assembly.

[0056] A control unit is electrically connected to the temperature sensor and all the heating units 31.

[0057] The utility model discloses a plurality of heating units 31 can make the heating of hydrogen realize step by step, avoid thermal shock damage pipeline and corresponding part. In addition, the utility model discloses a temperature sensor is arranged at the outlet of the heating assembly, that is, the last end of all the heating units 31, so that the control unit can detect the last temperature in real time. In this way, the utility model can detect the final temperature of the whole heating unit 31 after heating by arranging one temperature sensor.

[0058] Reference Figure 1 The embodiment provides a backflush system, which comprises the above heating assembly 3, and specifically comprises:

[0059] An adsorption assembly comprises a plurality of adsorption columns A, B and C. The inlet end of each adsorption column A or B or C is provided with a hot blow backflush outlet 42.

[0060] A hydrogen tank 2 is provided between the inlet end of the hydrogen tank 2 and the outlet end of each adsorption column A or B or C. Meanwhile, a cold gas inlet 62 is provided between the outlet end of the hydrogen tank 2 and the inlet end of each adsorption column A or B or C.

[0061] A heating assembly 3 is connected to the outlet end of the hydrogen tank 2, and a hot gas backflushing passage 41 is arranged between the outlet end of the heating assembly 3 and the outlet end of each adsorption column A or B or C.

[0062] The utility model discloses a plurality of adsorption column's design can carry out adsorption and backflushing operation simultaneously, improve the whole system's processing efficiency. In addition, the utility model discloses an adsorption assembly 1 realizes the adsorption of the tail gas of polysilicon production to make the hydrogen after recovery be high purity hydrogen, can store to hydrogen tank 2, simultaneously, the utility model discloses a hydrogen tank 2 in hydrogen heats and backflushes adsorption column A or B or C to can more effectively remove the residual in adsorption column A or B or C to improve adsorption column A or B or C's adsorption efficiency and service life. In addition, the utility model discloses the combination use of cold gas positive blowing and hot gas backflushing not only can effectively remove the dry residue in adsorption column A or B or C, can effectively reduce the consumption of backflushing gas, i. e. through hot blowing to improve the efficiency of backflushing cleaning, through cold blowing to realize the cooling of adsorption assembly 1.

[0063] In a preferred embodiment, the heating assembly 3 comprises a plurality of heating units 31, and the heating units are electric heaters, all of which are connected in series. The series connection of all the electric heaters can ensure that the gas is uniformly heated when passing through the adsorption column A or B or C, thereby improving the efficiency and effect of backflushing activation (heating to remove moisture and other impurities on the surface of the adsorbent to improve its adsorption capacity). The series connection of the electric heaters can reduce the thermal shock on the pipeline, thereby preventing the pipeline from being broken or the like.

[0064] In a preferred embodiment, the control unit is a PLC (Programmable Logic Controller) controller, which controls all the heating units 31 through a pulse width modulation signal. Specifically, the PWM (Pulse Width Modulation) signal is a commonly used power control method for controlling the power output of the heater, and is particularly suitable for resistive loads such as electric heaters. The principle of PWM control is to adjust the ratio of the power-on time to the total time of the heater within a certain time by rapidly switching the heater, so as to control the average power output of the heater.

[0065] In a preferred embodiment, the heating element in the electric heater is electrically connected to a solid-state relay, and the solid-state relay is communicatively connected to the PLC controller. The electrical connection between the heating element and the solid-state relay (SSR) and the communication connection between the solid-state relay and the PLC controller are for precise control of the heater. Specifically, the solid-state relay is a non-contact electronic switch that uses an optoelectronic coupler to achieve electrical isolation between the input and the output.

[0066] In a preferred embodiment, the inlet end of each adsorption column A or B or C is connected to the tail gas inlet 111, and the outlet end of the same adsorption column A or B or C is connected to the hydrogen tank 2 through the tail gas outlet 112.

[0067] In a preferred embodiment, a first switch valve 51 is provided between the adsorption column A or B or C and the tail gas inlet 111, and a first switch valve 51 is also provided between the adsorption column A or B or C and the tail gas outlet 112; a pressure boosting valve 114 is connected in parallel to each of the first switch valves 51. The pressure boosting valve 114 is connected in parallel to the first switch valve 51, which can increase the pressure of the system when needed to meet the requirements of a specific operation. Specifically, in order to ensure that the cold hydrogen can effectively penetrate the adsorbent layer and carry away impurities, it is usually necessary to maintain a certain pressure so that the cold hydrogen can pass through the adsorbent in the adsorption column at a sufficient speed and force.

[0068] In a preferred embodiment, all the hot blow-back outlet paths 42 are connected to the exhaust path 421, and the hot blow-back outlet path 42 and the hot blow-back inlet path 41 are each provided with a second switch valve 52; the second switch valve 52 is connected in parallel to a pressure relief valve 115. The pressure relief valve 115 is used to reduce the pressure in the adsorption column, because the gas will expand after being heated, so during the hot gas blow-back process, the pressure of the system will usually be reduced to prevent excessive pressure from causing damage to the adsorbent layer or the adsorption column.

[0069] Further, a pressure sensor is provided in each of the adsorption columns A and B and C; the pressure sensor can detect the progress of pressure reduction and pressure increase in real time, thereby avoiding the failure of the pressure relief valve 115 or the pressure boosting valve 114 to stop the process in time, thereby causing damage to the adsorption column; accordingly, the pressure sensor is connected to a sound alarm.

[0070] In a preferred embodiment, the cold gas outlet path 61 and the cold gas inlet path 62 are each provided with a third switch valve 53.

[0071] A control method of a blow-back system, including any of the above-described blow-back systems, comprising:

[0072] Step 1: the control unit opens all the first switch valves 51 connected to one of the adsorption columns A, closes the remaining switch valves of the adsorption column A; the adsorption column performs an adsorption process;

[0073] At the same time, the corresponding pressure boosting valve 114 of the adjacent adsorption column B is opened, and the third switch valve 53 of the adsorption column A is opened; the adsorption column B performs a pressure boosting and cooling process;

[0074] At the same time, the corresponding pressure relief valve 115 of the remaining adsorption column C is opened, and the second switch valve 52 of the adsorption column C is opened; the adsorption column C performs a hot gas blow-back process.

[0075] Step 2: The control unit first controls the adsorption column to move one position to the right (i.e. from adsorption column A to adsorption column B), and the rest repeats the operation of the previous step;

[0076] Specifically, the control unit first opens the first switch valve of adsorption column B, opens the first switch valve 51 of the adsorption column B, and closes the remaining switch valves of the adsorption column B; the adsorption column performs the adsorption process;

[0077] At the same time, the corresponding pressure increasing valve 114 of the adjacent adsorption column C is opened, the third switch valve 53 of the adsorption column C is opened; the adsorption column C performs the pressure increasing and cooling process;

[0078] At the same time, the corresponding pressure relief valve 115 of the remaining adsorption column A is opened, the second switch valve 52 of the adsorption column A is opened; the adsorption column A performs the hot gas back flushing process.

[0079] Step 3: Repeat step 2 until the operation is stopped.

[0080] Through the above operation, one adsorption column performs adsorption, another adsorption column performs hot back flushing, and the remaining adsorption column performs cold blowing at the same time. Thus, one adsorption column can always perform adsorption of tail gas, and the adsorption column is cleaned in real time. In addition, the hydrogen gas used for back flushing is filtered hydrogen gas after adsorption, which can reduce the use of back flushing gas and reduce the cost of back flushing.

[0081] For the convenience of understanding, taking the same adsorption column A as an example, the stages of the adsorption column A are described as follows:

[0082] Adsorption process:

[0083] The gas enters the adsorption column A in the adsorption state from the first switch valve 51 at the lower part of the adsorption column A, and under the selective adsorption of the activated carbon adsorbent, the HCL and chlorosilane components therein are adsorbed, and the unadsorbed hydrogen gas (the purity can reach 99.999%) is sent to the hydrogen tank 2 after the first switch valve 51 and the filter of the adsorption column, when the adsorbed impurities reach the bed outlet reserved section, the two first switch valves 51 of the adsorption column are closed, the adsorption is stopped, and the adsorption time is 240 min. The adsorption column A starts to enter the regeneration process.

[0084] Pressure reduction process:

[0085] After the adsorption process is completed, the pressure relief valve 115 is opened to release the pressure, and the pressure is released to 0.05 MPa, and the pressure relief time is 15 min. After the pressure relief is completed, the pressure relief valve 115 is closed;

[0086] Purging and heating process:

[0087] When the second switch valve 52 is opened, hydrogen is heated by the electric heating 31 and enters the adsorption tower A, so that HCl and chlorosilane adsorbed on the activated carbon are completely desorbed, and the activated carbon is regenerated. When the temperature at the bottom of the adsorption tower A is greater than 150 DEG C, and the timer reaches the preset time 208 min, it can be considered that the heating and purging is completed, and the adsorption column AS subsequently enters a cooling process. The two second switch valves 52 are closed.

[0088] Purging and cooling process:

[0089] When the heating and purging process is completed, the two third switch valves 53 are opened, and when the temperature at the top of the adsorption tower is less than 10 DEG C and the preset time 208 min of the timer is reached, the pressure charging and cooling process is completed, and the two third switch valves 53 are closed.

[0090] Pressure increasing process:

[0091] In order to enable the adsorption column A to be smoothly switched to the next adsorption, and to ensure that the pressure of the adsorption column A does not fluctuate in this process, it is necessary to increase the pressure of the adsorption column to the adsorption pressure. After the cooling of the adsorption tower is completed, the pressure increasing valve 114 is opened, and the adsorption tower A starts to be charged, and when the pressure is 1.25 Mpa, the pressure charging time is 15 min. The pressure increasing process is completed, and the pressure increasing valve 114 is closed.

[0092] After this process, the adsorption column completes a complete "adsorption-regeneration" cycle, and is ready for the next adsorption.

[0093] Since in the back flushing route of the utility model, the adsorption column A adsorption, the adsorption column B cold gas positive blowing and the adsorption column C hot gas back flushing this stage is taken as an example, at this time it can be seen that after the adsorption column B cold gas positive blowing, the cold gas (that is, the lower temperature cold hydrogen) will become heated hydrogen due to the heated adsorption column B, at this time, after passing through the heating assembly 3, it can cause damage to the already heated heating assembly 3; in order to avoid this situation, the control of the heating assembly 3 is adaptively changed.

[0094] A control method of a heating assembly, suitable for any one of the back flushing systems, comprising:

[0095] Step one, when the third switch valve 53 is opened, the control part reduces the heating frequency of all heating units 31 to a lower preset value, and the lower preset value is 10 ms.

[0096] Step two, when the temperature sensor senses that the temperature change gradient tends to be flat within the preset time period of the third switch valve 53, the heating frequency of all heating units 3 is increased to the normal heating frequency again;

[0097] The purpose of this step is to make the heated cold hydrogen less affect the heating assembly 3, start to increase the heating frequency of the heating assembly 3 to the normal heating frequency, and avoid heating beyond the bearing limit of the heating assembly 3 as much as possible.

[0098] Step three, the control part detects whether the heating frequency exceeds the upper preset value, if it exceeds, stop heating operation. The upper preset value is 20ms.

[0099] Because heating can cause uneven heating of hydrogen, further, the auxiliary heating structure 32 can be provided at the heating assembly 3; specifically, the auxiliary heating structure can be provided in the hot gas back blowing path 41.

[0100] As shown in Figures 2 to 4 , further, the auxiliary heating structure 32 is a petal type structure 321, a grid structure 322 and a rice type structure 323.

[0101] As shown in Figure 4 , further, the heating wire of the petal type structure 321 is a preferred structure, and the structure setting includes a plurality of heating groups, each group of heating group structure is a fan-shaped structure 321a, each group of fan-shaped structure includes two symmetrically arranged first arc-shaped structures 71, and each side of the arc-shaped structure is further provided with a second arc-shaped structure 72 for supporting; the first arc-shaped structure 71 and the second arc-shaped structure 72 can heat the hydrogen passing through such design can more effectively heat the hydrogen passing through, and ensure the uniformity of the heating process. In addition, this kind of structure consumes less material, and the heating of hydrogen can be realized quickly by continuously adding arc-shaped structures according to the demand.

[0102] 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 heating assembly, characterized by, The application relates to a hydrogen production system. The application relates to a hydrogen production system. The application relates to a hydrogen production system. The application relates to a hydrogen production system.

2. A heating assembly according to claim 1, wherein, The application relates to a hydrogen production system.

3. A backflush system comprising a heating assembly according to claim 1 or 2, characterized in that The application relates to a hydrogen production system. The application relates to a hydrogen production system. The application relates to a hydrogen production system. The application relates to a hydrogen production system.

4. A backflush system according to claim 3, wherein, The application relates to a hydrogen production system.

5. A backflush system according to claim 4, wherein, The application relates to a hydrogen production system.

6. A backflush system according to claim 5, wherein, The application relates to a hydrogen production system.

7. A backflush system according to claim 6, wherein, The application relates to a hydrogen production system.

8. A backflush system according to claim 6, wherein, The application relates to a hydrogen production system.

9. A backflush system according to claim 3, wherein, The application relates to a hydrogen production system.

10. A backflush system according to claim 9, wherein, The application relates to a hydrogen production system. The application relates to a hydrogen production system. The application relates to a hydrogen production system. The application relates to a hydrogen production system. The application relates to a hydrogen production system. The application relates to a hydrogen production system. The application relates to a hydrogen production system. The application relates to a hydrogen production system. The application relates to a hydrogen production system. The application relates to a hydrogen production system. The application relates to a hydrogen production system. The application relates to a hydrogen production system. The application relates to a hydrogen production system. The application relates to a hydrogen production system. The application relates to a hydrogen production system. The application relates to a hydrogen production system. 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