An apparatus and method for synergistic removal of NOx, CO and dioxins

Abstract

This invention relates to flue gas treatment technology for sintering machines in the steel industry, and particularly to a device and method for the synergistic removal of NOx, CO, and dioxins. The device for the synergistic removal of NOx, CO, and dioxins includes a reaction tower. A flue gas inlet pipe is connected to the top of the reaction tower, and a flue gas outlet pipe is connected to the bottom of the reaction tower. Inside the reaction tower, multiple first honeycomb catalyst packings for NOx removal and at least one second honeycomb catalyst packing for CO and dioxin removal are arranged sequentially from top to bottom. Advantages: It can simultaneously remove CO and dioxins while removing NOx, achieving compliance with emission standards for multiple pollutants, while reducing ammonia slip. The entire device reduces the processing flow and floor space required; the process is simple and easy to operate; it reduces pollutant emissions, carbon emissions, and operating costs.

Description

Technical Field

[0001] This invention relates to flue gas treatment technology for sintering machines in the steel industry, and particularly to a device and method for the synergistic removal of NOx, CO and dioxins. Background Technology

[0002] Sintering machine flue gas is a major source of air pollution in the steel industry, accounting for over 60% of air pollutants. Major pollutants such as SO2, NOx, CO, and dioxins are characterized by high concentrations, large fluctuations, and uneven distribution, posing significant challenges to flue gas treatment. With increasingly stringent national policies and environmental protection requirements, sintering flue gas treatment technology is developing towards a comprehensive approach that synergistically purifies harmful substances such as dust, SO2, NOx, CO, and dioxins.

[0003] Therefore, it is necessary to develop a comprehensive flue gas treatment equipment and process. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an apparatus and method for synergistic removal of NOx, CO and dioxins, which effectively overcomes the defects of the prior art.

[0005] The technical solution of the present invention to solve the above technical problems is as follows:

[0006] An apparatus for the synergistic removal of NOx, CO and dioxins includes a reaction tower, with a flue gas inlet pipe connected to the top of the reaction tower and a flue gas outlet pipe connected to the bottom of the reaction tower. Inside the reaction tower, a plurality of first honeycomb catalyst packings for NOx removal and at least one second honeycomb catalyst packing for CO and dioxin removal are arranged sequentially from top to bottom.

[0007] Based on the above technical solution, the present invention can be further improved as follows.

[0008] Furthermore, a cavity region is formed above each of the aforementioned first honeycomb catalyst packings and second honeycomb catalyst packings, and a rake-type soot blower is provided in each of the aforementioned cavity regions. The aforementioned rake-type soot blowers are all connected to a high-pressure gas delivery device through a gas delivery pipeline.

[0009] Furthermore, the aforementioned high-pressure gas delivery device is an air compressor.

[0010] Furthermore, the reaction tower sidewall is equipped with a pressure detection device for detecting each of the cavity regions, and each of the gas delivery pipelines is equipped with an electrically controlled valve. The electrically controlled valve, the pressure detection device, and the high-pressure gas delivery device are respectively connected to a controller.

[0011] Furthermore, there are two of the first honeycomb catalyst packing materials and one of the second honeycomb catalyst packing materials.

[0012] Furthermore, the aforementioned flue gas exhaust pipe is connected to the chimney.

[0013] The beneficial effects are: it can remove NOx while simultaneously removing CO and dioxins, achieving compliance with emission standards for multiple pollutants, while reducing ammonia slip value. The entire equipment reduces the processing steps and floor space required; the process is simple and easy to operate; it reduces pollutant emissions, carbon emissions, and overall operating costs.

[0014] A method for synergistic removal of NOx, CO and dioxins is also provided, comprising the following steps:

[0015] Step 1: The desulfurized flue gas is sent into the reaction tower through the flue gas inlet pipe;

[0016] Step 2: The flue gas passes through each of the first honeycomb catalyst packings from top to bottom, and some NOx is removed after the reaction;

[0017] Step 3: The flue gas with some NOx removed passes through the second honeycomb catalyst packing, and CO and dioxins are removed after the reaction.

[0018] Step 4: The flue gas is discharged from the flue gas discharge pipe.

[0019] Beneficial effects: The process is simple, easy to operate, and produces excellent results. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the device for the synergistic removal of NOx, CO and dioxins according to the present invention.

[0021] In the accompanying drawings, the components represented by the reference numerals are as follows:

[0022] 1. Reaction tower; 2. First honeycomb catalyst packing; 3. Second honeycomb catalyst packing; 4. Rake soot blower; 5. High-pressure gas conveying device; 6. Pressure detection device; 7. Chimney; 11. Flue gas inlet pipe; 12. Flue gas outlet pipe. Detailed Implementation

[0023] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0024] Example: Figure 1As shown, the device for synergistic removal of NOx, CO and dioxins in this embodiment includes a reaction tower 1. The top of the reaction tower 1 is connected to a flue gas inlet pipe 11, and the bottom of the reaction tower 1 is connected to a flue gas outlet pipe 12. The interior of the reaction tower 1 is provided with a plurality of first honeycomb catalyst packings 2 for removing NOx and at least one second honeycomb catalyst packing 3 for removing CO and dioxins, arranged sequentially from top to bottom.

[0025] The process is as follows:

[0026] Step 1: The desulfurized flue gas is sent into the reaction tower 1 through flue gas inlet pipe 11;

[0027] Step 2: The flue gas passes through each of the first honeycomb catalyst packings 2 from top to bottom, and some NOx is removed after the reaction;

[0028] Step 3: The flue gas with some NOx removed passes through the second honeycomb catalyst packing 3, and CO and dioxins are removed after the reaction;

[0029] Step 4: The flue gas is discharged from the flue gas discharge pipe 12.

[0030] In this embodiment, the reaction tower 1 can use a conventional SCR tower body. The first honeycomb catalyst packing 2 is a conventional catalyst in SCR denitrification towers, specifically a vanadium-titanium honeycomb catalyst, which is mainly composed of vanadium oxide, titanium oxide and other additives, with vanadium pentoxide as the main active component. The second honeycomb catalyst packing 3 is also a catalyst of the prior art. It can be a honeycomb CO oxidation catalyst material (with alumina as the matrix and platinum metal supported), or it can be a composite support prepared by using titanium dioxide (TiO2) as the support, vanadium pentoxide (V2O5) and tungsten oxide (WO3) as active components, supplemented with various additives (Al2O3 and SiO2) (from Industrial Catalysis, Vol. 17, No. 11, Development of Honeycomb Catalysts for Dioxin Decomposition), with a metal target coating loaded on the surface (more specifically, the ratio of each component is: 80-85% TiO2, 3-6% WO3, 0.3-0.5% V2O5, with the balance being Al2O3 and SiO2).

[0031] In this embodiment, the first catalyst (first honeycomb catalyst packing 2) is installed at the front end of the gas inlet of the reaction tower 1, typically packed in 2-3 layers, and its main function is to remove NOx. The second catalyst (second honeycomb catalyst packing 3) is installed after the first catalyst, i.e., at the rear end of the gas inlet of the reaction tower 1, typically packed in a single layer, and its main function is to remove CO, and synergistically remove dioxins and ammonia. The desulfurized clean flue gas enters the reaction tower 1 through the flue gas discharge pipe 12, passes sequentially through the first catalyst layer and the second catalyst, and then exits through the flue gas discharge pipe 12 at the outlet of the reaction tower 1. More specifically, the function of the first catalyst is to remove NOx from the flue gas. XNOx enters the catalyst layer of reaction tower 1 and reacts with ammonia (each layer of the first honeycomb catalyst packing 2 is equipped with an ammonia injection device to inject ammonia into the catalyst). The active components in the catalyst reduce NOx in the flue gas to N2 and H2O. This catalyst has the characteristics of high activity and high selectivity. The second catalyst can oxidize CO in the flue gas, catalytically combusting CO to produce CO2, while simultaneously removing dioxins and ammonia that escapes after denitrification. This catalyst has the characteristics of high activity and low selectivity. To ensure high CO removal efficiency, the second catalyst is packed after the first catalyst, i.e., after the reaction of ammonia and NOx.

[0032] Of course, in actual use, the second catalyst can also be loaded into the front end of the denitrification ammonia injection system.

[0033] In a preferred embodiment, a cavity region is formed above each of the aforementioned first honeycomb catalyst packing 2 and second honeycomb catalyst packing 3. Each of these cavity regions is equipped with a rake-type sootblower 4, which is externally connected to a high-pressure gas delivery device 5 via a gas delivery pipeline. The rake-type sootblower 4 is a product of the prior art, and its specific structure will not be described in detail here.

[0034] In the above implementation scheme, a rake-type soot blower 4 is installed on the top of each catalyst layer to regularly purge the catalyst layer and prevent catalyst blockage. The catalyst purge needs to be carried out from top to bottom in sequence, and purge 2 to 3 times a day.

[0035] In this embodiment, the high-pressure gas delivery device 5 can be a conventional air compressor.

[0036] In a preferred embodiment, the reaction tower 1 is provided with a pressure detection device 6 for detecting each cavity region, and each gas delivery pipeline is provided with an electrically controlled valve. The electrically controlled valve, the pressure detection device 6 and the high-pressure gas delivery device 5 are respectively connected to a controller.

[0037] In the above implementation scheme, pressure detection devices 6 are installed in the cavity area above and below each catalyst layer to measure pressure in real time (monitoring the pressure drop of the catalyst layer, that is, the pressure difference between the two pressure detection devices 6). If an abnormal pressure drop occurs in a certain catalyst layer, it indicates that the catalyst layer is blocked, and the rake soot blower 4 of the corresponding layer needs to be activated in time to blow it. Specifically, the two pressure detection devices 6 feed back the pressure information to the controller, the controller calculates the pressure difference, and reasonably controls the high-pressure gas delivery device 5 to deliver high-pressure gas to the rake soot blower 4 of the corresponding layer according to the pressure difference change data, so as to blow away and clear the blocked catalyst layer.

[0038] In this embodiment, the pressure detection device 6 described above can be a conventional pressure transmitter.

[0039] In this embodiment, there are two first honeycomb catalyst packings 2 and one second honeycomb catalyst packing 3.

[0040] In this embodiment, the flue gas exhaust pipe 12 is connected to the chimney 7 and is discharged externally through the chimney 7.

[0041] It should be noted that: when reaction tower 1 was only filled with the first type of catalyst and not the second type, the NOx, CO, and dioxin levels were monitored at the monitoring ports before and after the ultra-low emission project of the sintering machine flue gas. The NOx monitoring result was 264.4 mg / m³. 3 and 28.5 mg / m 3 The CO monitoring results were 8044 mg / m³. 3 and 8052mg / m 3 The dioxin monitoring results were 0.355 ng TEQ / m³. 3 and 0.307ng TEQ / m 3 The ammonia slip value at the outlet of the monitoring reaction tower was 1.0 ppm. With both the first and second catalysts simultaneously loaded into reaction tower 1, NOx, CO, and dioxins were monitored at the monitoring ports before and after the ultra-low emission project for the sintering machine flue gas. The NOx monitoring result was 333.2 mg / m³. 3 and 38.5 mg / m 3 The CO monitoring results were 8449.1 mg / m³. 3 and 2915.2 mg / m 3 The dioxin monitoring results were 0.317 ng TEQ / m³. 3 0.0048ng TEQ / m 3 The ammonia slip value at the outlet of the reaction tower equipment is 0.05 ppm.

[0042] The above data leads to the following conclusions: When reaction tower 1 is filled with only the first type of catalyst, it can only remove NOx; when reaction tower 1 is filled with both the first and second catalysts, it can synergistically remove NOx, CO, and dioxins, achieving compliance with emission standards for multiple pollutants while reducing ammonia slip. The entire system reduces the processing flow and floor space required; the process is simple and easy to operate; it reduces pollutant emissions, carbon emissions, and overall operating costs.

[0043] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to 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 invention.

[0044] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0045] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0046] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0047] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0048] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention. The above descriptions are only preferred embodiments of the present invention and are 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 within the protection scope of the present invention.

Claims

1. A device for synergistic removal of NOx, CO and dioxins, characterized in that: The reaction tower (1) is connected to a flue gas inlet pipe (11) at the top and a flue gas outlet pipe (12) at the bottom. The reaction tower (1) is provided with multiple first honeycomb catalyst packings (2) for NOx removal and at least one second honeycomb catalyst packing (3) for CO and dioxin removal in sequence from top to bottom inside the reaction tower (1). A cavity region is formed above each of the first honeycomb catalyst packing (2) and the second honeycomb catalyst packing (3). A rake-type soot blower (4) is provided in each cavity region. The rake-type soot blower (4) is connected to a high-pressure gas delivery device (5) through a gas delivery pipeline. A pressure detection device (6) for detecting each cavity region is provided on the side wall of the reaction tower (1). An electric control valve is provided on each gas delivery pipeline. The electric control valve, the pressure detection device (6) and the high-pressure gas delivery device (5) are respectively connected to a controller. A pressure detection device (6) is provided in the cavity region above and below each layer of catalyst for real-time pressure measurement.

2. The device for synergistic removal of NOx, CO and dioxins according to claim 1, characterized in that: The high-pressure gas delivery device (5) is an air compressor.

3. The device for synergistic removal of NOx, CO and dioxins according to claim 1, characterized in that: The pressure detection device (6) is a pressure transmitter.

4. The device for synergistic removal of NOx, CO and dioxins according to claim 1, characterized in that: There are two of the first honeycomb catalyst packing (2) and one of the second honeycomb catalyst packing (3).

5. The device for synergistic removal of NOx, CO and dioxins according to claim 1, characterized in that: The flue gas exhaust pipe (12) is connected to the chimney (7).

6. A method for synergistic removal of NOx, CO, and dioxins, implemented using the equipment for synergistic removal of NOx, CO, and dioxins as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Step 1: The desulfurized flue gas is sent into the reaction tower (1) through the flue gas inlet pipe (11); Step 2: The flue gas passes through each of the first honeycomb catalyst packings (2) from top to bottom, and some NOx is removed after the reaction; Step 3: The flue gas with some NOx removed passes through the second honeycomb catalyst packing (3), and CO and dioxins are removed after the reaction; Step 4: The flue gas is discharged from the flue gas discharge pipe (12).

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