A flue gas circulating catalytic oxidation treatment system

Abstract

The utility model provides a kind of flue gas circulation catalytic oxidation treatment system, comprising: VOCs catalytic oxidation treatment unit, heat exchange device and discharge device;Waste gas pipeline and air pipeline are connected in parallel into the heat exchange device, the VOCs catalytic oxidation treatment unit is connected with heat exchange device and forms loop, the heat exchange device is connected discharge device by discharge pipeline, from the discharge pipeline, backflow pipeline is led out and connected into the air pipeline.The flue gas circulation catalytic oxidation treatment system provided by the utility model introduces a backflow pipeline in discharge pipeline and connects into air pipeline, part of flue gas to be discharged is backflowed into air pipeline circulation, waste flue gas to be discharged is backflowed for waste heat utilization, reduces flue gas heat loss, simultaneously, using waste flue gas to dilute organic waste gas, stabilizes organic matter concentration, reduces flue gas treatment pressure and reagent consumption, reduces air into system, reduces final flue gas quantity.

Description

Technical Field

[0001] This utility model belongs to the field of waste gas treatment technology, specifically relating to a flue gas recirculation catalytic oxidation treatment system. Background Technology

[0002] Volatile organic compounds (VOCs) are one of the main pollutants in industrial waste gas, widely present in industrial production processes such as petrochemicals, chemicals, coating, and printing. VOC emissions form ozone and fine particulate matter (PM2.5), and some components are toxic and carcinogenic, causing serious harm to the environment and human health. Therefore, the effective control and treatment of VOCs is of great environmental significance.

[0003] One of the main methods for treating VOCs (volatile organic compounds) is catalytic oxidation. This technology oxidizes VOCs into harmless carbon dioxide and water at a specific temperature with the aid of a catalyst. Compared to traditional combustion methods, catalytic oxidation has advantages such as lower reaction temperature, greater adaptability, and no secondary pollution. Furthermore, to simultaneously remove nitrogen oxides (NOx) from flue gas, denitrification technology is often integrated with catalytic oxidation technology. This utilizes a catalyst to selectively reduce NOx to N2, thereby achieving the synergistic removal of both VOCs and NOx.

[0004] For example, CN116036856A discloses a method for simultaneously removing CO and NOx from MTO regenerated flue gas. The MTO regenerated flue gas first enters a dust removal and filtration unit to remove particulate matter entrained in the flue gas. The regenerated flue gas after dust removal then enters a heat exchange unit to exchange heat with the clean flue gas after passing through a catalytic oxidation unit and a reduction denitrification unit. While recovering heat, the flue gas is initially heated. The regenerated flue gas is then heated by a heating unit to the temperature required for the reaction before entering the catalytic oxidation unit and the reduction denitrification unit. After purification, the tail gas is further heated by a waste heat recovery unit before being sent to a downstream chimney for emission.

[0005] However, traditional waste gas treatment systems often employ a unidirectional flow structure, with waste gas being directly discharged into the atmosphere after catalytic treatment. The emitted flue gas still maintains a high temperature, failing to achieve effective energy utilization and resulting in low overall system efficiency. Furthermore, the temperature and organic matter concentration of the organic waste gas entering the system fluctuate significantly, potentially leading to unsatisfactory reaction effects in the catalytic zone, reducing the catalytic treatment efficiency, and making it difficult to meet stable emission standards.

[0006] Therefore, given the problems existing in the current system, there is an urgent need to provide a device that optimizes catalytic oxidation treatment and emissions in order to improve the overall performance and efficiency of waste gas treatment. Utility Model Content

[0007] The purpose of this invention is to provide a flue gas recirculation catalytic oxidation treatment system that optimizes the structure of waste gas treatment and emission pipelines, improves the system's thermal efficiency and VOCs treatment effect, and reduces flue gas emissions.

[0008] To achieve the objective of this utility model, the following technical solution is adopted:

[0009] This utility model provides a flue gas recirculation catalytic oxidation treatment system, which includes: a VOCs catalytic oxidation treatment unit, a heat exchange device, and an emission device;

[0010] The exhaust gas pipeline and the air pipeline are connected in parallel to the heat exchange device. The VOCs catalytic oxidation treatment unit is connected to the heat exchange device to form a loop. The heat exchange device is connected to the emission device through the emission pipeline, and a return pipeline is led out from the emission pipeline and connected to the air pipeline.

[0011] The waste gas treatment system provided by this utility model performs catalytic oxidation treatment on VOCs waste gas. The waste gas and air are connected in parallel into the system. First, the mixed gas to be treated is preheated by a heat exchange device to increase the temperature of the mixed gas. Then, it enters the VOCs catalytic oxidation unit to remove VOCs components. The flue gas formed after treatment has a high temperature. It then enters the heat exchange device to exchange heat and cool down, utilizing its heat and reducing its temperature for easy emission. Simultaneously, a return pipeline is led out from the emission pipeline and connected to the air pipeline, allowing some of the flue gas to circulate back into the air pipeline. On the one hand, the flue gas still has residual heat, and its return for waste heat utilization can accelerate the bed heating of the catalytic oxidation unit, shorten start-up time, reduce power consumption for electric heating, reduce exhaust heat loss, improve thermal efficiency, and reduce costs. On the other hand, the returned flue gas plays a role in diluting the waste gas to be treated. When the concentration of organic matter in the waste gas to be treated increases, under the condition of ensuring sufficient oxygen concentration, the return flue gas is increased first for dilution, which can stabilize the concentration of organic matter, reduce the nitrogen oxides generated during oxidation, reduce denitrification pressure and reagent consumption, and reduce the amount of air blown into the system, thereby reducing the final emission volume of flue gas and reducing environmental pressure.

[0012] Preferably, the VOCs catalytic oxidation treatment unit includes an oxidation device and a denitrification device connected sequentially along the gas flow direction.

[0013] In the VOCs catalytic oxidation treatment unit, the oxidation device is used for the catalytic oxidation removal of VOCs from the waste gas. Its principle is to react VOCs with oxygen under the action of a catalyst to generate carbon dioxide and water for removal. The denitrification device is used to remove nitrogen oxides generated during oxidation. Its principle is to react nitrogen oxides with nitrogen gas and water under the action of a catalyst for removal. In this invention, the oxidation device and the denitrification device can be conventional devices in the art, and their structures are not specifically limited.

[0014] Preferably, the VOCs catalytic oxidation treatment unit further includes a heating device arranged in front of the oxidation device along the gas flow direction.

[0015] The heating device is an electric heater used to heat the waste gas entering the VOCs catalytic oxidation treatment unit to reach the treatment temperature for VOCs catalytic oxidation.

[0016] Preferably, the VOCs catalytic oxidation treatment unit further includes a waste heat recovery device installed between the oxidation device and the denitrification device.

[0017] The waste heat recovery device is used to recover the waste heat of the flue gas formed after oxidation by the oxidation device and then cool it down so that the flue gas meets the denitrification temperature window. Conventional waste heat recovery devices in the field can be used, and their structure is not specifically limited.

[0018] Preferably, the heat exchange device is provided with a cold medium channel and a hot medium channel inside.

[0019] Preferably, the exhaust gas pipeline and the air pipeline are connected in parallel to the inlet of the cold medium channel, the two ends of the VOCs catalytic oxidation treatment unit are respectively connected to the outlet of the cold medium channel and the inlet of the hot medium channel, and the emission pipeline is connected to the outlet of the hot medium channel.

[0020] Preferably, the flue gas recirculation catalytic oxidation treatment system further includes a fan, which is installed on the air duct.

[0021] Preferably, the flue gas recirculation catalytic oxidation treatment system further includes a gas-liquid separation device, which is installed at the inlet of the waste gas pipeline.

[0022] The gas-liquid separation device is used to separate liquid droplets in the waste gas to ensure the treatment effect.

[0023] Preferably, a smoke exhaust damper is provided on the discharge pipeline, and the smoke exhaust damper is located between the return pipeline and the discharge device.

[0024] Preferably, a return damper is provided on the return pipeline.

[0025] In this invention, the amount of flue gas recirculated is controlled by the combination of the exhaust damper and the return damper, thereby controlling the temperature rise and dilution of the waste gas to be treated.

[0026] This utility model provides a method for flue gas circulating catalytic oxidation treatment, using the flue gas circulating catalytic oxidation treatment system, the method comprising:

[0027] The waste gas to be treated is introduced into a gas-liquid separator to separate liquid droplets from the waste gas and introduce them into the waste gas pipeline. The air damper and fan are opened to introduce air into the air pipeline, where the waste gas and air mix and enter a heat exchanger for heat exchange and temperature increase. After temperature increase, it enters the VOCs catalytic oxidation treatment unit, sequentially passing through a heating device, an oxidation device, a waste heat recovery device, and a denitrification device. The heating device heats the waste gas to the oxidation temperature. In the oxidation device, VOCs catalytic oxidation removes organic matter, forming flue gas, which then enters the waste gas denitrification unit. The heat recovery device cools the flue gas to the temperature window for denitrification treatment and recovers and utilizes the waste heat of the flue gas. The cooled flue gas undergoes catalytic denitrification of the nitrogen oxides generated by oxidation in the denitrification device. The denitrified flue gas enters the heat exchange device to exchange heat with the waste gas to be treated for cooling, forming treated flue gas. The treated flue gas enters the emission pipeline, where the emission damper and return damper regulate the flow. Part of the flue gas is circulated into the air pipeline through the return pipeline to heat up and dilute the waste gas to be treated. The remaining flue gas is discharged into the atmosphere through the emission device.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The flue gas recirculation catalytic oxidation treatment system provided by this utility model has a return pipeline led out from the emission pipeline and connected to the air pipeline. Part of the flue gas to be emitted is returned to the air pipeline for circulation. The flue gas is returned to utilize waste heat, which accelerates the bed temperature rise of the VOCs catalytic oxidation treatment unit, shortens the start-up time, and reduces the heat loss of flue gas. At the same time, it dilutes the organic matter in the waste gas to be treated, stabilizes the organic matter concentration, reduces the nitrogen oxides generated during oxidation, reduces the flue gas treatment pressure and reagent consumption, reduces the amount of air blown into the system, and reduces the final amount of flue gas emitted. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the flue gas recirculation treatment system provided in Example 1;

[0031] Among them, 1 is a gas-liquid separation device; 2 is a fan; 3 is a heat exchange device; 4 is a heating device; 5 is an oxidation device; 6 is a waste heat recovery device; 7 is a denitrification device; 8 is an emission device; 91 is an air damper; 92 is a return damper; and 93 is an exhaust damper. Detailed Implementation

[0032] It should be understood that in the description of this utility model, the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0033] It should be noted that, in the description of this utility model, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0034] The technical solution of this utility model will be further described below with reference to the accompanying drawings and specific embodiments.

[0035] Example 1

[0036] This embodiment provides a method such as Figure 1 The flue gas recirculation catalytic oxidation treatment system shown.

[0037] The flue gas recirculation catalytic oxidation treatment system is equipped with a gas-liquid separation device 1, a fan 2, a heat exchange device 3, an emission device 8, and a VOCs catalytic oxidation treatment unit; the VOCs catalytic oxidation treatment unit includes a heating device 4, an oxidation device 5, a waste heat recovery device 6, and a denitrification device 7.

[0038] The gas-liquid treatment device 1 is installed at the exhaust gas inlet of the flue gas recirculation catalytic oxidation treatment system to separate liquid droplets in the exhaust gas to be treated.

[0039] The gas-liquid treatment device 1 is connected to the heat exchange device 3 via an exhaust gas pipeline. The heat exchange device 3 has internal cold medium and hot medium channels for heat exchange. The exhaust gas pipeline connects to the inlet of the cold medium channel, which is also connected to an air pipeline in parallel with the exhaust gas pipeline. Exhaust gas and air enter the heat exchange device through the exhaust gas pipeline and air pipeline respectively to complete heat exchange and temperature increase. An air damper 91 and a fan 2 are installed on the air pipeline to control the gas flow rate.

[0040] Along the gas flow direction, the outlet of the cold medium channel of heat exchanger 3 is connected to the inlet of the VOCs catalytic oxidation treatment unit, and the outlet of the VOCs catalytic oxidation treatment unit is connected to the inlet of the hot medium channel of heat exchanger 3, forming a loop between heat exchanger 3 and the VOCs catalytic oxidation treatment unit. The flue gas generated by the VOCs catalytic oxidation treatment unit enters the hot medium channel of heat exchanger 3 for heat exchange and cooling. The VOCs catalytic oxidation treatment unit includes a heating device 4, an oxidation device 5, a waste heat recovery device 6, and a denitrification device 7 connected in sequence. The heating device 4 uses an electric heater to heat the waste gas entering the VOCs catalytic oxidation treatment unit to reach the treatment temperature for VOCs catalytic oxidation. The oxidation device 5 is used to catalytically oxidize and remove VOCs components from the waste gas, forming flue gas. The waste heat recovery device 6 is used to recover waste heat from the flue gas formed by the oxidation device 5 and then cool it down to meet the denitrification temperature window. The denitrification device 7 is used to catalytically remove nitrogen oxides generated during oxidation in the flue gas. The oxidation unit 5, the waste heat recovery unit 6, and the denitrification unit 7 all use conventional devices in the field, and their structures are not specifically limited.

[0041] The outlet of the heat medium channel of heat exchanger 3 is connected to emission device 8 via an emission pipe, which is a chimney. A return pipe is led out from the emission pipe and connected to the air pipe, so that part of the flue gas formed after the catalytic oxidation of the waste gas is returned to the air pipe through the return pipe. The emission pipe and the return pipe are respectively equipped with an emission damper 93 and a return damper 92 to regulate the return flow of the flue gas. By recirculating the flue gas to participate in the waste gas treatment, the waste heat of the returned flue gas is used to accelerate the bed heating of the oxidation device of the VOCs catalytic oxidation treatment unit, shorten the start-up time, reduce the power consumption for heating the waste gas, reduce the heat loss of the exhaust gas, and dilute the waste gas to be treated. When the concentration of organic matter in the waste gas to be treated increases, the return flue gas is increased first to dilute it, stabilize the concentration of organic matter, reduce the nitrogen oxides generated during oxidation, reduce the denitrification pressure and reagent consumption, and reduce the amount of air blown into the system, thus reducing the final emission volume of flue gas. The remaining treated flue gas is discharged into the atmosphere through emission device 8.

[0042] Comparative Example 1

[0043] This comparative example provides a catalytic oxidation treatment system that, compared to Example 1, does not have a reflux pipeline, but is otherwise the same as Example 1.

[0044] Compared to Example 1, Comparative Example 1 does not have a return pipeline. All the flue gas formed after the exhaust gas is treated by VOCs catalytic oxidation is directly discharged into the atmosphere through the emission pipeline and emission device. The results show that without flue gas return circulation, the exhaust gas to be treated lacks the waste heat from the return flue gas to raise its temperature, the system energy consumption increases, the catalytic start-up time is prolonged, and the lack of dilution effect from the return flue gas makes the fluctuation of waste VOCs concentration easy to cause system instability, ultimately greatly increasing the amount of exhaust gas emitted.

[0045] In summary, the flue gas recirculation catalytic oxidation treatment system provided by this utility model has a return pipeline led out from the emission pipeline and connected to the air pipeline. A portion of the flue gas to be emitted is returned to the air pipeline for circulation, and the flue gas recirculation utilizes waste heat, which accelerates the bed heating of the VOCs catalytic oxidation treatment unit, shortens the start-up time, and reduces exhaust heat loss. At the same time, it dilutes the organic matter in the waste gas to be treated, stabilizes the organic matter concentration, reduces the nitrogen oxides generated during oxidation, reduces the flue gas treatment pressure and reagent consumption, reduces the amount of air blown into the system, and reduces the final amount of flue gas emitted.

[0046] The above description is only a specific embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present utility model fall within the protection and disclosure scope of the present utility model.

Claims

1. A flue gas recirculation catalytic oxidation treatment system, characterized in that, The flue gas recirculation catalytic oxidation treatment system includes: a VOCs catalytic oxidation treatment unit, a heat exchange device, and an emission device; The exhaust gas pipeline and the air pipeline are connected in parallel to the heat exchange device. The VOCs catalytic oxidation treatment unit is connected to the heat exchange device to form a loop. The heat exchange device is connected to the emission device through the emission pipeline, and a return pipeline is led out from the emission pipeline and connected to the air pipeline.

2. The flue gas recirculation catalytic oxidation treatment system according to claim 1, characterized in that, The VOCs catalytic oxidation treatment unit includes an oxidation device and a denitrification device connected sequentially along the gas flow direction.

3. The flue gas recirculation catalytic oxidation treatment system according to claim 2, characterized in that, The VOCs catalytic oxidation treatment unit further includes a heating device installed in front of the oxidation device along the gas flow direction.

4. The flue gas recirculation catalytic oxidation treatment system according to claim 2, characterized in that, The VOCs catalytic oxidation treatment unit further includes a waste heat recovery device installed between the oxidation device and the denitrification device.

5. The flue gas recirculation catalytic oxidation treatment system according to claim 1, characterized in that, The heat exchange device is internally equipped with a cold medium channel and a hot medium channel.

6. The flue gas recirculation catalytic oxidation treatment system according to claim 5, characterized in that, The exhaust gas pipeline and the air pipeline are connected in parallel to the inlet of the cold medium channel. The two ends of the VOCs catalytic oxidation treatment unit are respectively connected to the outlet of the cold medium channel and the inlet of the hot medium channel, and the emission pipeline is connected to the outlet of the hot medium channel.

7. The flue gas recirculation catalytic oxidation treatment system according to claim 1, characterized in that, The flue gas recirculation catalytic oxidation treatment system also includes a fan, which is installed on the air duct.

8. The flue gas recirculation catalytic oxidation treatment system according to claim 1, characterized in that, The flue gas recirculation catalytic oxidation treatment system further includes a gas-liquid separation device, which is installed at the inlet of the waste gas pipeline.

9. The flue gas recirculation catalytic oxidation treatment system according to claim 1, characterized in that, The discharge pipeline is equipped with a smoke exhaust damper, which is located between the return pipeline and the discharge device.

10. The flue gas recirculation catalytic oxidation treatment system according to claim 1, characterized in that, A return air damper is installed on the return pipeline.

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