Tail gas treatment system

Abstract

The utility model provides a tail gas treatment system, which relates to the technical field of tail gas treatment and is used for solving the technical problem of low tail gas treatment efficiency of Scrubber. The tail gas treatment system comprises a heating type or combustion type Scrubbing device, the Scrubbing device comprises a gas inlet and a gas outlet, and tail gas is oxidized and decomposed after being introduced into the Scrubbing device through the gas inlet; the SCR denitration device comprises a tail gas connector and an exhaust port, the tail gas connector of the SCR denitration device is communicated with the gas outlet of the Scrubbing device, and the tail gas treated by the Scrubbing device is introduced into the SCR denitration device to be reduced and then is exhausted through the exhaust port of the SCR denitration device. According to the SCR denitration device, a washing device is not additionally arranged, the structure of the SCR denitration device is simplified, the application range is wider, the structure is simpler, and a large amount of polluted water needing to be treated does not exist at the tail end.

Description

Technical Field

[0001] The utility model relates to the technical field of tail gas treatment, in particular to a tail gas treatment system. Background Art

[0002] Scrubber (originally meaning washer, in semiconductor industry process production it is called waste gas treatment equipment) is a kind of exhaust gas treatment device that uses various methods to harmlessly treat harmful exhaust gas generated during the chemical vapor deposition (CVD) process, so that the exhaust gas meets the emission standards allowed by national or local standards. There are various types of existing CVDScrubbers, which are divided into "heating", "combustion", "electrolysis" or "adsorption" according to their structural characteristics, usage methods, and application scenarios, each with its own advantages and disadvantages.

[0003] The heating and combustion types are currently the most widely used in the market. They use electric heating or organic energy oxidation to maintain the equipment temperature, and high-temperature oxidation decomposes the tail gas. Most of them are then equipped with a water washing device to treat the high-temperature oxidation byproduct nitrogen oxides. This method has low one-time investment costs and low energy consumption. However, it cannot treat nitrogen oxides, and a large amount of wastewater is generated that requires additional treatment. The electrolysis type is less used in the market. It uses ultra-high temperature electrolysis to plasma-treat harmful tail gas. This method has high treatment efficiency and can reduce nitrogen oxides to nitrogen in the plasma process. However, the one-time investment cost is high and the energy consumption is high. The adsorption type is mostly used for backup and one-time bypass use.

[0004] The Selective Catalytic Reduction (SCR) denitration device uses a metal catalyst to reduce nitrogen oxides to N2 through NH3 at 350-400°C. At present, the market generally uses ammonia water and urea as reducing agents, which need to be further decomposed into NH3 before denitration can be carried out. The process is cumbersome; and in order to maintain the temperature of the device, some SCR equipment will also be designed with preheating at the front end and heat storage ceramics installed inside; and if it is necessary to treat nitrogen oxides in CVD exhaust gas, saddle-shaped ceramics need to be arranged above the heat storage ceramics to reduce the impact of dust in the exhaust gas on the pressure drop and the activity of the metal catalyst, and the dust needs to be cleaned regularly.

[0005] It can be seen from the above that the overall structure of the tail gas treatment system in the prior art is complex, which is not conducive to the plane layout in the clean workshop. Utility Model Content

[0006] In view of the technical problem of the complex structure of the tail gas treatment system in the prior art, the utility model proposes a tail gas treatment system, which is based on the traditional heating or combustion scrubber, but does not install a water scrubber, but uses the selective catalytic reduction technology SCR to denitrate nitrogen oxides, and simplifies the structure of the SCR denitration device. The scope of application is wider than that of the single heating type and the single SCR, the structure is simpler, and there is no large amount of polluted water to be treated at the tail end.

[0007] In order to achieve the above object, the technical solution of the utility model is implemented as follows:

[0008] An exhaust gas treatment system includes a heating or combustion scrubber, wherein the scrubber includes an air inlet and an air outlet, and the exhaust gas is oxidized and decomposed after passing into the scrubber through the air inlet;

[0009] The SCR denitrification device comprises a tail gas interface and an exhaust port. The tail gas interface of the SCR denitrification device is connected with the exhaust port of the scrubber. The tail gas treated by the scrubber is introduced into the SCR denitrification device and discharged through the exhaust port of the SCR denitrification device after being reduced.

[0010] Optionally, the SCR denitration device further includes an ammonia interface and a catalyst. The tail gas treated by the scrubber is mixed with ammonia introduced through the tail gas interface of the SCR denitration device and then reduced by the catalyst, and finally discharged through the exhaust port.

[0011] Optionally, the SCR denitrification device also includes a shell, which includes at least a gas mixing chamber and a catalyst filling chamber; the ammonia interface and the exhaust gas interface are arranged on a side of the gas mixing chamber away from the catalyst filling chamber, and the catalyst is arranged in the catalyst filling chamber.

[0012] Optionally, the tail gas interface and the exhaust port are located on opposite sides of the shell, and the exhaust port is arranged on a side of the catalyst filling chamber away from the gas mixing chamber.

[0013] Optionally, the catalyst is any one or more of a noble metal catalyst, a metal oxide catalyst, a molecular sieve support catalyst or a carbon-based support catalyst.

[0014] Optionally, the catalyst is filled in the catalyst filling chamber in a corrugated plate type, a honeycomb type or a plate type.

[0015] Optionally, the SCR denitration device is connected to the scrubber via an exhaust gas pipeline; a cooling device is provided on the exhaust gas pipeline, and the cooling device can reduce the temperature of the exhaust gas in the exhaust gas pipeline.

[0016] Optionally, the cooling device includes a blower and a fresh air pipeline, the blower is connected to the exhaust gas pipeline through the fresh air pipeline, and the gas introduced through the fresh air pipeline is mixed with the exhaust gas in the exhaust gas pipeline to be cooled.

[0017] Optionally, the SCR denitration device further includes a heater, which is disposed in the gas mixing chamber and can heat the gas in the gas mixing chamber.

[0018] Optionally, the air inlet of the scrubber is connected to a CVD system, and the exhaust gas is the exhaust gas generated by the CVD system; the CVD system also includes an ammonia pipeline, and the ammonia interface is connected to the ammonia pipeline.

[0019] Beneficial effects of the utility model:

[0020] (1) The utility model is applied to exhaust gas treatment by adding an SCR denitration device to a heating or combustion scrubber. The scrubber is first used to treat the exhaust gas so that harmful gases in the exhaust gas are oxidized and decomposed into nitrogen oxides, and then the nitrogen oxides are reduced to nitrogen through the SCR denitration device.

[0021] (2) On the one hand, the utility model utilizes the SCR denitration device to treat nitrogen oxides, thereby avoiding the joint use of the scrubber and the water washing device. On the other hand, the exhaust gas treated by the scrubber has a high temperature and does not contain impurities such as dust. The subsequent SCR denitration device does not need to be preheated or cleaned of dust, and the effect of dust on the catalyst and pressure drop in the SCR denitration device can be reduced, thereby improving the utilization efficiency of the SCR. Therefore, the exhaust gas treatment system described in the present application can meet the standards for treating nitrogen oxides without increasing high energy consumption and polluting a large amount of water.

[0022] (3) When the SCR denitration device in the utility model is used for CVD tail gas treatment, it can directly use the NH3 gas source in the CVD process, without using ammonia water and urea as reducing agents to decompose and produce ammonia, and has the characteristics of high efficiency and simplicity. In addition, the utility model has a simple process and is easy to implement. From the technical and economic perspectives, it has good application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1It is a structural schematic diagram of the utility model.

[0025] In the figure, 1. Scrubber; 2. SCR denitrification device; 21. Shell; 22. Exhaust gas interface; 23. Ammonia interface; 24. Exhaust port; 25. Catalyst; 3. Ammonia pipeline; 4. Exhaust gas pipeline; 5. Cooling device; 51. Blower; 52. Fresh air pipeline; 6. Heater. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0027] Example 1

[0028] An exhaust gas treatment system, such as Figure 1 As shown, it includes a heating or combustion type Scrubber 1, the Scrubber 1 includes an air inlet and an air outlet, and the exhaust gas is oxidized and decomposed after passing into the Scrubber 1 through the air inlet;

[0029] The principle of the heating Scrubber 1 is: inject exhaust gas and air, heat to 700-800℃ through an electric heater, and oxidize and decompose the exhaust gas; the principle of the combustion Scrubber 1 is: inject exhaust gas and air, ignite and fully burn in the combustion chamber, and oxidize and decompose the exhaust gas. The heating or combustion Scrubber 1 is a common equipment in the semiconductor industry process production, such as GST (Global Standard Technology Co., Ltd) Gallant A. Usually, the bottom of the Scrubber 1 has a dust removal function, and its specific structure will not be introduced in detail.

[0030] The SCR denitrification device 2 is connected to the SCR denitrification device 2 and is located in the post-process of the Scrubber 1, including a tail gas interface 22 and an exhaust port 24. The tail gas interface 22 of the SCR denitrification device 2 is connected to the gas outlet of the Scrubber 1. The tail gas treated by the Scrubber 1 is passed into the SCR denitrification device 2 and is discharged through the exhaust port 24 of the SCR denitrification device 2 after reduction.

[0031] Specifically, after the exhaust gas is passed into the exhaust gas treatment system in this embodiment, the exhaust gas is first subjected to high-temperature oxidation decomposition in the heating or combustion type Scrubber1, and then the high-temperature oxidized and decomposed exhaust gas is discharged through the outlet of Scrubber1. Then, after passing into the SCR denitrification device for denitrification reduction reaction, the high temperature carried by the exhaust gas itself can be used to complete the denitrification treatment. There is no need to add preheating devices such as heat storage ceramics at the front end of the SCR denitrification device, which simplifies the structure of the SCR denitrification device and saves energy. At the same time, since the exhaust gas is subjected to high-temperature oxidation decomposition in Scrubber1, the dust content in the exhaust gas is reduced to avoid the dust in the exhaust gas affecting the pressure drop and the activity of the metal catalyst, thereby reducing the frequency of dust cleaning in the exhaust gas treatment system.

[0032] The principle of SCR denitration device 2 is: under the action of catalyst and in the presence of oxygen, NH3 preferentially reacts with NO x A reduction and removal reaction occurs to generate nitrogen and water. The main reaction formula is:

[0033] 4NO+4NH3+O2→4N2+6H2O

[0034] 2NO2+4NH3+O2→3N2+6H2O;

[0035] The SCR denitration device 2 described in this embodiment is a conventional device in exhaust gas treatment, and any device designed according to the above principle can be applied to this solution; for example, the SCR denitration device 2 disclosed in patent publication numbers CN203002214U, CN212492407U, CN218608819U, etc.

[0036] Example 2

[0037] An exhaust gas treatment system, such as Figure 1 As shown, it includes a heating or combustion type Scrubber1, and the Scrubber1 includes an air inlet and an air outlet. The exhaust gas is introduced into the Scrubber1 through the air inlet and then oxidized and decomposed; the SCR denitrification device 2 is connected with the air outlet of the Scrubber1, and specifically includes an exhaust gas interface 22 and an exhaust port 24. The exhaust gas interface 22 of the SCR denitrification device 2 is connected with the air outlet of the Scrubber1, and the exhaust gas treated by the Scrubber1 is introduced into the SCR denitrification device 2 for reduction and then discharged through the exhaust port 24 of the SCR denitrification device 2.

[0038] Specifically, in this embodiment, the structure of the conventional SCR denitration device 2 is simplified, and the SCR denitration device 2 includes a shell 21, which is a hollow sealed structure, and its shape and size are selected according to the flow rate of the exhaust gas treatment. The shell 21 is provided with an exhaust gas interface 22, an ammonia interface 23 and an exhaust port 24, and the shell 21 is filled with a catalyst 25. The exhaust gas treated by the Scrubber 1 is introduced into the shell 21 through the exhaust gas interface 22 and mixed with the ammonia introduced through the ammonia interface 23, and then reduced by the catalyst 25, and finally discharged through the exhaust port 24.

[0039] On the other hand, the interior of the shell 21 is divided into two chambers, including a gas mixing chamber and a catalyst filling chamber; in order to allow the exhaust gas and ammonia gas to be fully mixed before contacting the catalyst 25, the ammonia interface 23 and the exhaust gas interface 22 are arranged on the side of the gas mixing chamber away from the catalyst filling chamber. The positions of the ammonia interface 23 and the exhaust gas interface 22 are arranged in this way to ensure that the ammonia and exhaust gas introduced into the shell 21 enter the catalyst filling chamber after being fully mixed and the mixed temperature reaches the temperature requirement of the denitrification reaction, thereby preventing the lower temperature ammonia or the higher temperature exhaust gas from entering the catalyst filling chamber alone, thereby affecting the denitrification reaction efficiency.

[0040] On the other hand, the tail gas interface 22 and the exhaust port 24 are located on opposite sides of the shell 21, and the exhaust port 24 is arranged on the side of the catalyst filling chamber away from the gas mixing chamber, so that the reduction reaction is more complete and prevents the oxidized exhaust gas from being directly discharged from the SCR denitrification device without reduction.

[0041] The tail gas interface 22 and the exhaust port 24 are located on opposite sides of the shell 21 to prevent the tail gas entering the shell through the tail gas interface 22 from being directly discharged through the exhaust port, thereby improving the denitration effect of the SCR denitration device.

[0042] The catalyst 25 is laid in the catalyst filling chamber, and the catalyst 25 can be laid directly on the bottom of the shell 21; or a multi-layer bracket can be set in the catalyst filling chamber, and multiple layers of catalyst 25 can be laid to increase the contact area between the tail gas and the catalyst 25 and improve the catalytic efficiency. The commonly used catalysts at present include: precious metal catalysts, metal oxide catalysts, molecular sieve carrier catalysts and carbon-based carrier catalysts, etc., and can also be arranged in a corrugated plate type, honeycomb type, plate type and other structures.

[0043] Example 3

[0044] An exhaust gas treatment system, such as Figure 1As shown, it includes a heating or combustion type Scrubber1, and the Scrubber1 includes an air inlet and an air outlet. The exhaust gas is introduced into the Scrubber1 through the air inlet and then oxidized and decomposed; the SCR denitrification device 2 is connected with the air outlet of the Scrubber1, and specifically includes an exhaust gas interface 22 and an exhaust port 24. The exhaust gas interface 22 of the SCR denitrification device 2 is connected with the air outlet of the Scrubber1, and the exhaust gas treated by the Scrubber1 is introduced into the SCR denitrification device 2 for reduction and then discharged through the exhaust port 24 of the SCR denitrification device 2.

[0045] The SCR denitration device 2 includes a shell 21, which is provided with an exhaust gas interface 22, an ammonia interface 23 and an exhaust port 24. The shell 21 is filled with a catalyst 25. The exhaust gas treated by the Scrubber 1 is introduced into the shell 21 through the exhaust gas interface 22 and mixed with the ammonia introduced by the ammonia interface 23, and then reduced by the catalyst 25, and finally discharged through the exhaust port 24. The shell 21 is divided into two chambers, including a gas mixing chamber and a catalyst filling chamber; the ammonia interface 23 and the exhaust gas interface 22 are arranged on the side wall of the shell 21 of the gas mixing chamber; the ammonia interface 23 is connected to the ammonia pipeline 3.

[0046] Furthermore, the SCR denitration device 2 is connected to the Scrubber 1 through an exhaust gas pipeline 4. The exhaust gas pipeline 4 is provided with a cooling device 5, which can reduce the temperature of the exhaust gas in the exhaust gas pipeline 4, so that the temperature of the exhaust gas entering the SCR denitration device is the temperature required for the denitration reaction, and prevent the denitration effect of the SCR denitration device from being affected by excessive temperature. The cooling device 5 can adopt heat dissipation structures or waste heat recovery systems designed with different specifications according to the content of heat energy in the exhaust gas, such as using heat sinks or wrapping a refrigerant medium on the pipe of the exhaust gas pipeline 4.

[0047] Since the amount of tail gas generated by the chemical vapor deposition device is small, the heat energy contained in the tail gas after passing through the heated scrubber 1 is small, and this embodiment adopts a relatively simple cooling structure. Specifically, the cooling device 5 includes a blower 51 and a fresh air pipeline 52. The blower 51 is connected to the exhaust gas pipeline 4 through the fresh air pipeline 52. The gas introduced by the fresh air pipeline 52 is mixed with the tail gas in the exhaust gas pipeline 4 for cooling. In addition to cooling the tail gas, the air introduced by the blower 51 can also participate in the reaction of oxygen in the air in the SCR denitration device 2.

[0048] Furthermore, in order to ensure the stable catalytic reduction reaction of nitrogen oxides in the SCR denitrification device 2, the SCR denitrification device 2 also includes a heater 6, which can heat the SCR denitrification device 2 to avoid instability in the reaction temperature caused by unstable input of fresh air into the cooling device 5 and unstable input of ammonia into the ammonia pipeline 3, thereby ensuring stable and efficient reaction.

[0049] Specifically, the heater 6 is an electric heater, which is mainly made of winding resistance wire. The electric heater is arranged in the gas mixing chamber to maintain the temperature required for the denitration reaction and improve the denitration effect.

[0050] Furthermore, the tail gas treatment system in this embodiment is mainly used for treating harmful tail gas generated by the CVD system, and directly connects the Scrubber 1 to the CVD system. Specifically, the CVD system includes an ammonia pipeline 3, and the ammonia interface 23 is connected to the ammonia pipeline 3. The ammonia pipeline 3 can be directly connected to the ammonia cylinder pipeline in the CVD process, without indirectly using urea or ammonia water to generate ammonia, thereby reducing device redundancy.

[0051] The method of using the tail gas treatment system of this embodiment is as follows: the tail gas generated by CVD is introduced into the heating scrubber 1, the temperature inside the heating scrubber 1 is 700°C, and the tail gas is oxidized to generate nitrogen oxides. Since the heating scrubber 1 device is equipped with a dust removal device, only the high-temperature nitrogen oxide tail gas is discharged from the heating scrubber 1. After the tail gas enters the exhaust pipe 4, the blower 51 in the cooling device 5 is turned on to introduce fresh air into the exhaust pipe 4 to reduce the tail gas temperature to 350-400°C required for the SCR denitration reaction. Ammonia is introduced into the SCR denitration device 2 to mix with the tail gas again, and the heater 6 is turned on as needed to maintain the catalytic denitration reaction temperature. Under the action of the catalyst 25, the tail gas reacts with the ammonia to remove the residual nitrogen oxides in the tail gas, and the removal efficiency can reach 95%, and then it can be discharged from the exhaust port 24.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A tail gas treatment system, characterized in that: The invention comprises a heating or combustion type scrubber (1), wherein the scrubber (1) comprises an air inlet and an air outlet, and the exhaust gas is passed into the scrubber (1) through the air inlet and then oxidized and decomposed; The SCR denitrification device (2) comprises an exhaust gas interface (22) and an exhaust port (24); the exhaust gas interface (22) of the SCR denitrification device (2) is connected to the exhaust port of the scrubber (1); the exhaust gas treated by the scrubber (1) is introduced into the SCR denitrification device (2) and is discharged through the exhaust port (24) of the SCR denitrification device (2) after being reduced.

2. The exhaust gas treatment system according to claim 1, characterized in that: The SCR denitration device (2) further comprises an ammonia interface (23) and a catalyst (25). The tail gas treated by the scrubber (1) is mixed with ammonia introduced through the tail gas interface (22) of the SCR denitration device (2) and then reduced through the catalyst (25) and finally discharged through the exhaust port (24).

3. The exhaust gas treatment system according to claim 2, characterized in that: The SCR denitration device (2) further comprises a shell, wherein the shell (21) comprises at least a gas mixing chamber and a catalyst filling chamber; the ammonia interface (23) and the exhaust gas interface (22) are arranged on a side of the gas mixing chamber away from the catalyst filling chamber, and the catalyst (25) is arranged in the catalyst filling chamber.

4. The exhaust gas treatment system according to claim 3, characterized in that: The tail gas interface (22) and the exhaust port (24) are located on opposite sides of the shell (21), and the exhaust port (24) is arranged on a side of the catalyst filling chamber away from the gas mixing chamber.

5. The exhaust gas treatment system according to claim 3, characterized in that: The catalyst is filled in the catalyst filling chamber in a corrugated plate type, a honeycomb type or a plate type.

6. The exhaust gas treatment system according to claim 2, characterized in that: The SCR denitration device (2) and the scrubber (1) are connected via an exhaust gas pipeline (4); a cooling device (5) is provided on the exhaust gas pipeline (4), and the cooling device (5) can reduce the temperature of the exhaust gas in the exhaust gas pipeline (4).

7. The exhaust gas treatment system according to claim 6, characterized in that: The cooling device (5) comprises a blower (51) and a fresh air pipeline (52); the blower (51) is connected to the exhaust gas pipeline (4) via the fresh air pipeline (52); the gas introduced through the fresh air pipeline (52) and the exhaust gas are mixed and cooled in the exhaust gas pipeline (4).

8. The exhaust gas treatment system according to claim 3, characterized in that: The SCR denitration device (2) further comprises a heater (6), wherein the heater (6) is arranged in the gas mixing chamber, and the heater (6) is capable of heating the gas in the gas mixing chamber.

9. The exhaust gas treatment system according to any one of claims 2 to 8, characterized in that: The air inlet of the scrubber (1) is connected to the CVD system, and the tail gas is the tail gas generated by the CVD system; the CVD system also includes an ammonia pipeline (3), and the ammonia interface (23) is connected to the ammonia pipeline (3).

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