Activated carbon desulfurization and SCR denitrification coupling system and method for sintering pellet flue gas

Abstract

The present invention provides an activated carbon desulfurization and SCR denitration coupling system and method for sintering pellet flue gas, the system comprising a desulfurization and denitration reactor and an activated carbon regeneration tower; wherein, a super-low temperature SCR denitration reaction zone and an activated carbon desulfurization reaction zone connected from top to bottom are arranged in the desulfurization and denitration reactor, or the desulfurization and denitration reactor comprises an activated carbon desulfurization reactor and an super-low temperature SCR denitration reactor which are independent and connected, the activated carbon desulfurization reaction zone / reactor are respectively provided with a first activated carbon inlet, a flue gas inlet and a first activated carbon outlet, the super-low temperature SCR denitration reaction zone / reactor are respectively provided with an ammonia inlet and a clean flue gas outlet; an ammonia pre-activation device is arranged on an ammonia injection pipeline connected with the ammonia inlet; a plurality of SCR denitration catalyst layers are also arranged in the super-low temperature SCR denitration reaction zone / reactor; a heating zone, a degassing zone and a cooling zone connected in sequence are arranged in the activated carbon regeneration tower from top to bottom.

Description

Technical Field

[0001] The invention relates to an activated carbon desulfurization and SCR denitrification coupling system and method for sintering pellet flue gas, belonging to the technical field of flue gas treatment. Background Art

[0002] In recent years, my country has increasingly stringent requirements for air pollution emissions, and at the same time, the ultra-low emission transformation of the steel industry has been in full swing. Steel enterprises have many processes, and the flue gas emission components are complex. Different processes are suitable for different pollutant emission control methods; industry practitioners are also constantly developing and innovating the best flue gas treatment methods suitable for the characteristics of each process, and the technical route is frequently replaced to achieve the goal of both effective control and economic energy saving.

[0003] The flue gas emission characteristics of the sintering and pelletizing process are similar. The nitrogen oxides and sulfur dioxide produced by them account for more than 50% of the entire steel enterprise production process. Therefore, the pollution emission control of sintering and pelletizing flue gas is a top priority. The current more mature sintering and pelletizing flue gas treatment process involves desulfurization and denitrification of flue gas. The desulfurization methods mainly include activated carbon desulfurization and denitrification, wet desulfurization, semi-dry desulfurization (circulating fluidized bed, dense phase coherent tower method, SDS), and the denitrification method is mainly medium-temperature SCR denitrification. Among them, no wastewater and waste residue are generated during the activated carbon desulfurization and denitrification process, but the denitrification efficiency of activated carbon is not high. In order to achieve ultra-low NOx emissions, a large number of denitrification modules must be used. The investment of a large number of denitrification modules will increase the investment cost linearly. At the same time, excessive ammonia injection will also cause serious ammonia escape; wet desulfurization is easy to cause corrosion to downstream equipment, and gypsum rain and "white feathers" may be generated near the chimney; the by-products produced in semi-dry desulfurization are difficult to handle. In addition, since the denitrification method is limited by the temperature window of medium and low temperature SCR denitrification technology, the flue gas after desulfurization needs to be heated to above 200-280°C, which requires the addition of heating devices and large heat exchangers, which will also lead to an increase in overall investment and increased energy consumption of system operation.

[0004] 1. Prior art related to the present invention

[0005] 1.1. Technical solution of prior art 1

[0006] Chinese patent CN108993094A discloses an activated carbon flue gas purification tower, and specifically discloses that a channel extending in a vertical direction is arranged inside the desulfurization tower. The flue gas enters the desulfurization tower from the bottom of the desulfurization tower, and the activated carbon enters from the top of the desulfurization tower along the activated carbon channel. The two are in contact in the desulfurization tower, and then the purified flue gas is discharged from the top of the desulfurization tower, and the activated carbon after absorbing the waste is discharged from the bottom of the tower along the activated carbon channel.

[0007] 1.2. Disadvantages of the prior art 1

[0008] In this technology, multiple activated carbon channels are set inside the desulfurization tower to increase its contact area with the flue gas, which not only increases the construction cost, but also the activated carbon is prone to blockage in the channel, which may lead to spontaneous combustion due to excessive temperature in a certain area, endangering the safe operation of the entire system; in addition, the multi-channel arrangement will increase the pressure loss of the system, resulting in increased operating costs; finally, this technology has a low processing capacity for nitrogen oxides in flue gas and cannot meet the requirements of ultra-low emissions.

[0009] 2. Prior art related to the present invention

[0010] 2.1. Technical solution of the second prior art

[0011] Chinese patent CN 112337281A discloses a method for treating sintering flue gas, which first atomizes ammonia water and pre-treats the sintering flue gas to obtain a primary desulfurized flue gas, then introduces slaked lime to remove sulfur dioxide, and the desulfurized flue gas is sent to a dust collector, and after dust removal, it passes through a flue gas heating device and enters a denitrification device, and finally the desulfurized and denitrified flue gas is sent to a chimney under the action of a fan.

[0012] 2.2 Disadvantages of the Second Existing Technology

[0013] This technology uses a flue gas heating device to send the desulfurized flue gas into the denitrification device to complete the flue gas purification. This process is complex and requires two desulfurization steps. In addition, the use of a heating device requires an external heat source, which increases the system energy consumption and system investment.

[0014] Therefore, providing a sintering pellet flue gas treatment system and method with high efficiency, stability, low energy consumption and no desulfurization by-products has become a technical problem that urgently needs to be solved in this field. Summary of the invention

[0015] In order to solve the above-mentioned shortcomings and deficiencies, an object of the present invention is to provide an activated carbon desulfurization and SCR denitrification coupling system for sintering pellet flue gas.

[0016] Another object of the present invention is to provide a coupling method of activated carbon desulfurization and SCR denitrification of sintered pellet flue gas.

[0017] In order to achieve the above objectives, on the one hand, the present invention provides an activated carbon desulfurization and SCR denitrification coupling system for sintering pellet flue gas, wherein the system comprises a desulfurization and denitrification reactor and an activated carbon regeneration tower;

[0018] The desulfurization and denitration reactor is provided with an ultra-low temperature SCR denitration reaction zone and an activated carbon desulfurization reaction zone connected from top to bottom, or the desulfurization and denitration reactor includes an activated carbon desulfurization reactor and an ultra-low temperature SCR denitration reactor that are independent and connected to each other, the activated carbon desulfurization reaction zone or the activated carbon desulfurization reactor are respectively provided with a first activated carbon inlet, a flue gas inlet and a first activated carbon outlet, the ultra-low temperature SCR denitration reaction zone or the ultra-low temperature SCR denitration reactor are respectively provided with an ammonia inlet and a clean flue gas outlet; an ammonia pre-activation device is provided on the ammonia injection pipeline connected to the ammonia inlet; the ultra-low temperature SCR denitration reaction zone or the ultra-low temperature SCR denitration reactor is also provided with a plurality of SCR denitration catalyst layers;

[0019] The activated carbon regeneration tower is provided with a heating zone, a degassing zone and a cooling zone which are connected in sequence from top to bottom. The heating zone is provided with a second activated carbon inlet and a heat medium inlet, and the cooling zone is provided with a second activated carbon outlet; the first activated carbon inlet and the first activated carbon outlet are connected with the second activated carbon outlet and the second activated carbon inlet respectively through an activated carbon delivery pipeline and an activated carbon regeneration delivery pipeline.

[0020] As a specific implementation of the above system of the present invention, the smoke inlet is connected to a smoke duct, and a smoke valve is provided on the smoke duct.

[0021] As a specific implementation of the above system of the present invention, the heat medium inlet is connected to the hot air furnace through a heat medium pipeline.

[0022] As a specific embodiment of the system described above in the present invention, an ammonia nitrogen uniform distribution plate is further provided in the ultra-low temperature SCR denitration reaction zone or the ultra-low temperature SCR denitration reactor, and the ammonia nitrogen uniform distribution plate is located between the ammonia gas inlet and the SCR denitration catalyst layer. When the SCR denitration catalyst layer is multi-layered, the ammonia nitrogen uniform distribution plate is located between the ammonia gas inlet and the lowest SCR denitration catalyst layer.

[0023] As a specific embodiment of the above system of the present invention, the vertical distance between the ammonia nitrogen uniform distribution plate and the ammonia gas inlet is 1-2m.

[0024] In the present invention, the vertical distance between the ammonia nitrogen uniform distribution plate and the ammonia inlet is 1-2m, that is, ammonia is sprayed 1-2m below the ammonia nitrogen uniform distribution plate, which is beneficial to reduce the flue gas velocity deviation coefficient to below 10%, thereby facilitating high-efficiency denitrification.

[0025] As a specific embodiment of the above system of the present invention, the heating zone is also provided with a heat medium outlet, and the heat medium outlet is connected to the heat medium inlet of the ultra-low temperature SCR denitrification reaction zone or the ultra-low temperature SCR denitrification reactor through a catalyst regeneration pipeline and a heat medium valve.

[0026] As a specific embodiment of the system described above in the present invention, when an ammonia nitrogen uniform distribution plate is provided in the ultra-low temperature SCR denitrification reaction zone or the ultra-low temperature SCR denitrification reactor, the heat medium inlet of the ultra-low temperature SCR denitrification reaction zone or the ultra-low temperature SCR denitrification reactor is arranged below the ammonia nitrogen uniform distribution plate.

[0027] In the present invention, the heat medium inlet of the ultra-low temperature SCR denitration reaction zone or the ultra-low temperature SCR denitration reactor is arranged below the ammonia nitrogen uniform distribution plate. When the SCR denitration catalyst is thermally regenerated by using the cooled heat medium, the cooled heat medium passes through the ammonia nitrogen uniform distribution plate, which can thermally decompose a small amount of ammonium sulfate attached to the ammonia nitrogen uniform distribution plate, which is beneficial to improving and restoring the uniform mixing effect.

[0028] As a specific embodiment of the above-mentioned system of the present invention, the ammonia pre-activation device includes an ammonia pre-activator and a visible light filter, and the ammonia pre-activator is used to activate ammonia by reacting with oxygen under the irradiation of the visible light filter and the catalysis of an ammonia activation catalyst.

[0029] The ammonia pre-activator and visible light filter used in the present invention are conventional equipment and can be obtained commercially.

[0030] On the other hand, the present invention also provides a coupling method of activated carbon desulfurization and SCR denitrification of sintering pellet flue gas, wherein the method comprises:

[0031] (1) The sintering pellet flue gas is brought into reverse contact with the activated carbon to desulfurize the sintering pellet flue gas, and the desulfurized activated carbon is heated, regenerated, and then recycled for flue gas desulfurization;

[0032] (2) activating the ammonia gas to obtain a reducing agent;

[0033] (3) After the desulfurized flue gas is mixed with the reducing agent, the flue gas is denitrated under the action of an SCR denitration catalyst.

[0034] As a specific embodiment of the above method of the present invention, in step (1), the temperature of the sintering pellet flue gas is in the range of 120-150°C.

[0035] As a specific embodiment of the above method of the present invention, in step (1), the desulfurized activated carbon is heated and regenerated using a heat medium from a hot blast furnace, wherein the temperature range of the heat medium is 500-600°C.

[0036] As a specific embodiment of the above method of the present invention, the method further includes using a cooled heat medium to perform thermal regeneration on the SCR denitration catalyst, wherein the temperature range of the cooled heat medium is 280-420°C, and the regeneration time is no more than 24 hours.

[0037] In the present invention, the activated carbon after desulfurization is heated and regenerated by using the heat medium from the hot blast furnace. The heat medium is used to heat and analyze the activated carbon in the activated carbon regeneration tower. In this process, the activated carbon absorbs heat and the heat medium releases heat, but the temperature of the heat medium after cooling is still as high as 280-420°C; in order to fully utilize the energy and take into account the long-term stable operation of the hot blast furnace, in the prior art, a part of the cooled heat medium is usually sent to the hot blast furnace for continued heating for use in the activated carbon regeneration tower, and the other part is directly discharged. In this regard, the present invention sends the cooled heat medium to the ultra-low temperature SCR denitration reaction zone or ultra-low temperature SCR denitration reactor through the catalyst regeneration pipeline to perform thermal regeneration treatment on the SCR denitration catalyst.

[0038] As a specific embodiment of the above method of the present invention, in step (2), ammonia gas reacts with oxygen under irradiation of a visible light filter and catalysis of an ammonia activation catalyst to activate the ammonia gas, thereby obtaining the reducing agent.

[0039] As a specific embodiment of the above method of the present invention, in step (2), the volume ratio of ammonia to oxygen is 2:1-5:1.

[0040] In the present invention, the activated ammonia (ie, the reducing agent) has stronger reducing properties than NH3 and can efficiently remove nitrogen oxides from flue gas under ultra-low temperature conditions.

[0041] As a specific embodiment of the above method of the present invention, in step (3), the desulfurized flue gas is mixed with the reducing agent to reduce the velocity deviation coefficient of the flue gas to below 10%, preferably below 5%.

[0042] In the present invention, the desulfurized flue gas is mixed with the reducing agent, and then the obtained mixture is passed through an ammonia nitrogen uniform distribution plate, so that the desulfurized flue gas and the reducing agent are evenly mixed; in a specific embodiment of the present invention, the flue gas velocity deviation coefficient is reduced to less than 10% after the obtained mixture passes through the ammonia nitrogen uniform distribution plate.

[0043] In the present invention, during the desulfurization process of the sintering pellet flue gas and the activated carbon in reverse contact, the activated carbon adsorbs and releases heat, so after desulfurization, the temperature of the flue gas will generally rise slightly; after the flue gas after desulfurization enters the ultra-low temperature SCR denitrification reaction zone or the ultra-low temperature SCR denitrification reactor and is mixed with the reducing agent, the flue gas temperature drops slightly, but there is still no need to set up an additional heating device to heat the flue gas, and the denitrification treatment of the flue gas can be achieved only at the temperature of the flue gas itself after the desulfurization treatment.

[0044] As a specific embodiment of the above method of the present invention, in step (3), the temperature of the denitration treatment is ≤120°C.

[0045] As a specific embodiment of the method described above, the concentration of sulfur dioxide in the flue gas after desulfurization is 20 mg / Nm 3 Below, the nitrogen oxide concentration in the clean flue gas obtained after denitrification treatment is 35mg / Nm 3 Below, the concentration of other pollutants is <0.5ng TEQ / Nm 3 .

[0046] In the present invention, the SCR denitration catalyst is a conventional denitration catalyst used in the art. Those skilled in the art can select a suitable SCR denitration catalyst according to the actual on-site operation needs, as long as the purpose of the present invention can be achieved; in addition, the optimal regeneration temperature of the SCR denitration catalyst used in the present invention is 280-400°C, but at a temperature of 180°C, the catalytic performance of the regenerated SCR denitration catalyst can still reach 70% of the catalytic performance of the fresh catalyst.

[0047] In some embodiments of the present invention, the SCR denitration catalyst may be the medium-low temperature NH3-SCR catalyst and its improved catalyst disclosed in Chinese patent CN108435237A. The improved catalyst is obtained by adding about 0.05% of Mn to the improved catalyst based on the total weight of the medium-low temperature NH3-SCR catalyst as 100%.

[0048] The beneficial technical effects that can be achieved by the activated carbon desulfurization and SCR denitrification coupling system and method for sintering pellet flue gas provided by the present invention include:

[0049] The system and method provided by the present invention can simultaneously achieve ultra-clean removal of nitrogen oxides, sulfur dioxide, dioxins and other pollutants in the flue gas of sintering pellets. The concentration of sulfur dioxide in the flue gas after desulfurization is 20mg / Nm 3 Below, the nitrogen oxide concentration in the clean flue gas obtained after denitrification treatment is 35mg / Nm 3Below, the concentration of other pollutants such as dioxins is less than 0.5ng TEQ / Nm 3 It can be seen that compared with the existing technology of using activated carbon denitrification in the art, the activated carbon desulfurization and ultra-low temperature SCR denitrification coupling process used in the present invention has high denitrification efficiency and can achieve ultra-low (near zero) emissions;

[0050] In the present invention, the SCR denitration temperature is ≤120°C, which can achieve ultra-low temperature denitration. After the activated carbon desulfurization, the sintered pellet flue gas can be directly denitrated at its own temperature without the need for supplementary heat and temperature increase, thereby reducing the energy consumption of the flue gas denitration module.

[0051] Since the present invention uses pre-activated ammonia as the reducing agent for SCR denitration, the reaction rate of the reducing agent and nitrogen oxides is increased, and the generation of by-products such as ammonium sulfate during the denitration process is reduced; in addition, compared with NH3, the activated ammonia (i.e., the reducing agent) has stronger reducing properties, and can achieve efficient removal of nitrogen oxides in flue gas under ultra-low temperature conditions. At the same time, the ultra-low temperature conditions also avoid the re-synthesis of other pollutants such as dioxins in the flue gas;

[0052] In the system provided by the present invention, the ultra-low temperature SCR denitration reaction zone and the activated carbon desulfurization reaction zone are integrated into an integrated design, which saves space and production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0054] Figure 1 This is a schematic structural diagram of an activated carbon desulfurization and SCR denitrification coupling system for sintering pellet flue gas provided in an embodiment of the present invention.

[0055] Description of main figures:

[0056] 1. Ammonia spray pipeline; 2. Ammonia pre-activator; 3. Visible light filter; 4. Ultra-low temperature SCR denitrification reaction zone; 5. SCR denitrification catalyst layer; 6. Ammonia nitrogen uniform distribution plate; 7. Flue gas pipeline; 8. Flue gas valve; 9. Activated carbon desulfurization reaction zone; 10. Activated carbon regeneration and transportation pipeline; 11. Heat medium pipeline; 12. Activated carbon regeneration tower; 13. Catalyst regeneration pipeline; 14. Heat medium valve; 15. Heating zone; 16. Degassing zone; 17. Cooling zone; 18. Activated carbon transportation pipeline. DETAILED DESCRIPTION

[0057] It should be noted that the "numerical range" disclosed in the present invention is given in the form of a lower limit and an upper limit. It can be one or more lower limits, and one or more upper limits respectively. A given range is defined by selecting a lower limit and an upper limit. The selected lower limit and upper limit define the boundaries of a particular range. All ranges defined in this way are combinable, i.e. any lower limit can be combined with any upper limit to form a range. For example, a range of 60-120 and 80-110 is listed for a specific parameter, and it is understood that a range of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​listed are 1 and 2, and the maximum range values ​​listed are 3, 4 and 5, then the following ranges can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5.

[0058] In the present invention, unless otherwise specified, the numerical range "ab" represents an abbreviation of any real number combination between a and b, where a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed in the present invention, and "0-5" is just an abbreviation of these numerical combinations.

[0059] In the present invention, unless otherwise specified, all embodiments and preferred embodiments mentioned in the present invention can be combined with each other to form a new technical solution.

[0060] In the present invention, unless otherwise specified, all technical features and preferred features mentioned in the present invention can be combined with each other to form a new technical solution.

[0061] The term "comprises" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0062] In the present invention, the terms "upper", "lower", "top" and "bottom" indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings. These terms are mainly used to better describe the present invention and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0063] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those skilled in the art, the specific meanings of these terms in the present invention can be understood according to specific circumstances.

[0064] In addition, the terms "disposed", "provided with", and "connected" should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0065] In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical scheme of the present invention is now described in detail in conjunction with the following specific embodiments, but it should not be understood as limiting the applicable scope of the present invention.

[0066] Example 1

[0067] This embodiment provides an activated carbon desulfurization and SCR denitrification coupling system for sintering pellet flue gas, wherein the structural schematic diagram of the system is as follows: Figure 1 As shown, from Figure 1 It can be seen that it includes: a desulfurization and denitrification reactor and an activated carbon regeneration tower 12;

[0068] Among them, the desulfurization and denitration reactor is provided with a connected ultra-low temperature SCR denitration reaction zone 4 and an activated carbon desulfurization reaction zone 9 from top to bottom, the upper part, lower part and bottom of the activated carbon desulfurization reaction zone 9 are respectively provided with a first activated carbon inlet, a flue gas inlet and a first activated carbon outlet, and the lower part and top of the ultra-low temperature SCR denitration reaction zone 4 are respectively provided with an ammonia inlet and a clean flue gas outlet; an ammonia pre-activation device is provided on the ammonia injection pipeline 1 connected to the ammonia inlet; and three layers of SCR denitration catalyst layers 5 are also provided in the ultra-low temperature SCR denitration reaction zone 4;

[0069] The activated carbon regeneration tower 12 is provided with a heating zone 15, a degassing zone 16 and a cooling zone 17 which are connected in sequence from top to bottom. The top and the bottom of the heating zone 15 are respectively provided with a second activated carbon inlet and a heat medium inlet, and the bottom of the cooling zone 17 is provided with a second activated carbon outlet; the first activated carbon inlet and the first activated carbon outlet of the activated carbon desulfurization reaction zone 9 are connected with the second activated carbon outlet of the cooling zone 17 and the second activated carbon inlet of the heating zone 15 through an activated carbon delivery pipeline 18 and an activated carbon regeneration delivery pipeline 10 respectively.

[0070] In this embodiment, the smoke inlet is communicated with a smoke duct 7 , and a smoke valve 8 is provided on the smoke duct 7 .

[0071] In this embodiment, the heat medium inlet of the heating zone 15 is connected to a hot air furnace (not shown in the figure) through a heat medium pipeline 11 .

[0072] In this embodiment, an ammonia nitrogen uniform distribution plate 6 is further provided in the ultra-low temperature SCR denitration reaction zone 4 , and the ammonia nitrogen uniform distribution plate 6 is located between the ammonia gas inlet and the SCR denitration catalyst layer 5 .

[0073] In this embodiment, the vertical distance between the ammonia nitrogen uniform distribution plate 6 and the ammonia gas inlet is 1-2m.

[0074] In this embodiment, a heat medium outlet is further provided at the upper portion of the heating zone 15 , and the heat medium outlet is connected to the heat medium inlet of the ultra-low temperature SCR denitration reaction zone 4 via a heat medium valve 14 through a catalyst regeneration pipeline 13 .

[0075] In this embodiment, when an ammonia nitrogen uniform distribution plate 6 is provided in the ultra-low temperature SCR denitration reaction zone 4 , the heat medium inlet of the ultra-low temperature SCR denitration reaction zone 4 is arranged below the ammonia nitrogen uniform distribution plate 6 .

[0076] In this embodiment, the ammonia preactivation device includes an ammonia preactivator 2 and a visible light filter 3. The ammonia preactivator 2 contains an ammonia activation catalyst. The ammonia preactivator 2 is used to activate ammonia by reacting with oxygen under the catalytic action of the ammonia activation catalyst and irradiating the visible light filter 3.

[0077] Example 2

[0078] This embodiment provides a method for coupling activated carbon desulfurization and SCR denitrification of sintering pellet flue gas, which is implemented by using the coupled activated carbon desulfurization and SCR denitrification system for sintering pellet flue gas provided in Example 1, and includes the following specific steps:

[0079] (1) Untreated sintering pellet flue gas (temperature 120°C, calculated based on the total volume of the flue gas, with a SO2 concentration of 1500 mg / Nm 3 , NOx concentration is 400mg / Nm 3 ) is sent to the activated carbon desulfurization reaction zone 9 through the flue gas pipeline 1. The flue gas enters the activated carbon desulfurization reaction zone 9 from the bottom and flows upward. At the same time, the activated carbon delivery pipe 18 sends the activated carbon to the upper part of the activated carbon desulfurization reaction zone 9. The activated carbon contacts the flue gas from top to bottom in the activated carbon desulfurization reaction zone 9. After the activated carbon desulfurization, the sulfur dioxide in the flue gas is removed by more than about 98% by volume. The sulfur dioxide concentration in the flue gas after the desulfurization treatment entering the ultra-low temperature SCR denitration reaction zone 4 can be reduced to 20mg / Nm 3 (based on the total volume of flue gas after desulfurization treatment) below;

[0080] After passing through the activated carbon desulfurization reaction zone 9, the activated carbon enters the activated carbon regeneration conveying pipe 10, and then enters the activated carbon regeneration tower 12. In the heating zone 15 of the activated carbon regeneration tower 12, the activated carbon is heated and regenerated by the heat medium (hot air) from the hot air furnace. The heated activated carbon enters the degassing zone 16 and the cooling zone 17 in turn to obtain regenerated activated carbon. The regenerated activated carbon is conveyed to the activated carbon desulfurization reaction zone through the activated carbon conveying pipe 18 to complete the cycle.

[0081] The temperature of the heat medium (hot air) from the hot air furnace is 550°C, and the discharge temperature of the heat medium after heat exchange with the activated carbon in the activated carbon regeneration tower 12 is 300°C;

[0082] (2) introducing ammonia and oxygen from the ammonia-air mixer into the ammonia preactivator 2 by using the ammonia injection pipeline 1, wherein the molar ratio (volume ratio) of ammonia to oxygen is controlled at 1:0.5; in the ammonia preactivator 2, the ammonia reacts with oxygen under the catalytic action of an ammonia activation catalyst (the ammonia activation catalyst is a conventional catalyst, and the ammonia activation catalyst used in this embodiment is a catalyst whose main active component is a precious metal, such as the silver phosphate catalyst disclosed in Chinese patent CN108854518A) to activate the ammonia to obtain a reducing agent;

[0083] The visible light source used in this embodiment is obtained by filtering out the ultraviolet light in the xenon lamp, and the visible light filter is used to further filter out the light in the light source that has a negative impact on the ammonia activation catalyst;

[0084] (3) The reducing agent in step (2) enters the ultra-low temperature SCR denitration reaction zone 4 and is fully mixed with the flue gas after desulfurization in step (1). The resulting mixture is passed through the ammonia nitrogen uniform distribution plate 6 to reduce the average velocity deviation coefficient of the flue gas to less than 10%. Then, the flue gas with a relatively uniform flow rate passes through the SCR denitration catalyst (the SCR denitration catalyst can be the medium-low temperature NH3-SCR catalyst disclosed in Chinese patent CN108435237A and its improved catalyst. The improved catalyst is obtained by adding about 0.05% of Mn to the improved catalyst based on the total weight of the medium-low temperature NH3-SCR catalyst as 100%). At a temperature of about 120°C (in this embodiment, no other heating equipment is required, and this temperature is the temperature of the flue gas after desulfurization treatment), the nitrogen oxides in the flue gas are reduced to N2 and H2O by the activated ammonia in the reducing agent, and the nitrogen oxide concentration in the flue gas after denitration is less than 30 mg / Nm 3 (measured by the total volume of flue gas after denitration / clean flue gas); at the same time, under this denitration temperature condition, dioxins and other pollutants in the flue gas of sintering pellets are not easy to be resynthesized, which can ensure that the concentration of dioxins and other pollutants in the clean flue gas is <0.5ng TEQ / Nm 3(measured in terms of flue gas after denitration / total volume of clean flue gas);

[0085] In this embodiment, the flow rate of the catalyst discharged after heat exchange with activated carbon in step (1) is about 10000m 3 / h-20000m 3 / h of heat medium is sent to the ultra-low temperature SCR denitration reaction zone 4 to perform thermal regeneration treatment on the SCR denitration catalyst to achieve online regeneration of the catalyst, wherein the regeneration time of this embodiment is not more than 24h.

[0086] Example 3

[0087] This embodiment aims to improve the existing activated carbon desulfurization technology of sintering pellet flue gas, and provides an activated carbon desulfurization and SCR denitrification coupling system for sintering pellet flue gas, wherein the system includes: a desulfurization and denitrification reactor and an activated carbon regeneration tower;

[0088] The desulfurization and denitration reactor comprises an activated carbon desulfurization reactor and an ultra-low temperature SCR denitration reactor which are independent of each other and connected. The upper part, lower part, bottom part and top part of the activated carbon desulfurization reactor are respectively provided with a first activated carbon inlet, a flue gas inlet, a first activated carbon outlet and a flue gas outlet after desulfurization. The bottom part, lower part and top part of the ultra-low temperature SCR denitration reactor are respectively provided with a flue gas inlet after desulfurization, an ammonia inlet and a clean flue gas outlet. The flue gas outlet after desulfurization of the activated carbon desulfurization reactor is connected with the flue gas inlet after desulfurization of the ultra-low temperature SCR denitration reactor through a pipeline.

[0089] An ammonia pre-activation device is provided on the ammonia injection pipeline connected to the ammonia gas inlet; three layers of SCR denitration catalyst layers are also provided in the ultra-low temperature SCR denitration reactor;

[0090] The activated carbon regeneration tower is provided with a heating zone, a degassing zone and a cooling zone which are connected in sequence from top to bottom. The top and the bottom of the heating zone are respectively provided with a second activated carbon inlet and a heat medium inlet, and the bottom of the cooling zone is provided with a second activated carbon outlet; the first activated carbon inlet and the first activated carbon outlet are respectively connected with the second activated carbon outlet and the second activated carbon inlet through an activated carbon delivery pipeline and an activated carbon regeneration delivery pipeline.

[0091] In this embodiment, the smoke inlet is communicated with a smoke duct, and a smoke valve is provided on the smoke duct.

[0092] In this embodiment, the heat medium inlet is connected to the hot air furnace through a heat medium pipeline.

[0093] In this embodiment, an ammonia nitrogen uniform distribution plate is further provided in the ultra-low temperature SCR denitration reactor, and the ammonia nitrogen uniform distribution plate is located between the ammonia inlet and the SCR denitration catalyst layer.

[0094] In this embodiment, the vertical distance between the ammonia nitrogen uniform distribution plate and the ammonia gas inlet is 1-2m.

[0095] In this embodiment, a heat medium outlet is further provided at the upper portion of the heating zone, and the heat medium outlet is connected to the heat medium inlet of the ultra-low temperature SCR denitration reactor via a catalyst regeneration pipeline and a heat medium valve.

[0096] In this embodiment, when an ammonia nitrogen uniform distribution plate is provided in the ultra-low temperature SCR denitration reactor, the heat medium inlet of the ultra-low temperature SCR denitration reactor is arranged below the ammonia nitrogen uniform distribution plate.

[0097] In this embodiment, the ammonia preactivation device includes an ammonia preactivator and a visible light filter. The ammonia preactivator contains an ammonia activation catalyst. The ammonia preactivator is used to activate ammonia by reacting with oxygen under the irradiation of the visible light filter and the catalytic action of the ammonia activation catalyst.

[0098] Example 4

[0099] This embodiment provides a method for coupling activated carbon desulfurization and SCR denitrification of sintering pellet flue gas, which is implemented by using the coupled activated carbon desulfurization and SCR denitrification system for sintering pellet flue gas provided in Example 3, wherein the method includes the following specific steps:

[0100] A factory uses 400m 2 The sintering machine has a flue gas emission of 2400000m 3 / h, and added ultra-low temperature SCR denitrification process in the transformation of activated carbon desulfurization process. The flue gas temperature after activated carbon desulfurization is 120℃, and the SO2 concentration is <20mg / Nm 3 ; After passing through the activated carbon desulfurization reactor, the activated carbon enters the activated carbon regeneration delivery pipe, and then enters the activated carbon regeneration tower. In the heating zone of the activated carbon regeneration tower, the activated carbon is heated and regenerated by the heat medium (hot air) from the hot air furnace. The heated activated carbon enters the degassing zone and the cooling zone in turn to obtain regenerated activated carbon. The regenerated activated carbon is sent to the activated carbon desulfurization reactor through the activated carbon delivery pipe to complete the cycle;

[0101] The temperature of the heat medium (hot air) from the hot air furnace is 550°C, and the discharge temperature of the heat medium after heat exchange with the activated carbon in the activated carbon regeneration tower is 300°C;

[0102] Ammonia and oxygen are introduced into an ammonia pre-activator from an ammonia-air mixer by using an ammonia injection pipeline, wherein the molar ratio (volume ratio) of ammonia to oxygen is controlled at 1:0.5; in the ammonia pre-activator, ammonia reacts with oxygen under irradiation with a visible light filter and under the catalytic action of an ammonia activation catalyst (the ammonia activation catalyst is a conventional catalyst, and the ammonia activation catalyst used in this embodiment is a catalyst whose main active component is a precious metal, such as the silver phosphate catalyst disclosed in Chinese patent CN108854518A) to activate the ammonia to obtain a reducing agent;

[0103] The visible light source used in this embodiment is obtained by filtering out the ultraviolet light in the xenon lamp, and the visible light filter is used to further filter out the light in the light source that has a negative impact on the ammonia activation catalyst;

[0104] The flue gas after activated carbon desulfurization is introduced into the ultra-low temperature SCR denitration reactor through a pipeline and is fully mixed with the reducing agent in the ultra-low temperature SCR denitration reactor. The obtained mixture is passed through an ammonia nitrogen uniform distribution plate to reduce the average velocity deviation coefficient of the flue gas to less than 10%. Then, the flue gas with a relatively uniform flow rate passes through the SCR denitration catalyst (the SCR denitration catalyst can be the medium-low temperature NH3-SCR catalyst disclosed in Chinese patent CN108435237A and its improved catalyst. Among them, the improved catalyst is obtained by adding about 0.05% of Mn to the improved catalyst based on the total weight of the medium-low temperature NH3-SCR catalyst as 100%) layer. At a temperature of 120°C (in this embodiment, no other heating equipment is required, and this temperature is the temperature of the flue gas after desulfurization treatment), the nitrogen oxides in the flue gas are reduced to N2 and H2O by the activated ammonia in the reducing agent, and the nitrogen oxide concentration in the flue gas after denitration is less than 35mg / Nm 3 (measured in terms of flue gas after denitration / total volume of clean flue gas);

[0105] At the same time, under this denitrification temperature condition, dioxins and other pollutants in the flue gas of sintering pellets are not easy to be re-synthesized, which can ensure that the concentration of dioxins and other pollutants in the clean flue gas is <0.5ng TEQ / Nm 3 (measured in terms of flue gas after denitration / total volume of net flue gas); compared with the medium-high temperature SCR denitration at a temperature of 150-280°C, this embodiment does not require the installation of a heating furnace and a heat exchanger, which can save investment costs (a total of about 16.8 million yuan), equivalent to saving about 70,000 yuan in investment costs per cubic meter of flue gas; in addition, this embodiment directly completes denitration at a temperature of 120°C, which can save about 20,000Nm of blast furnace gas consumption. 3 / h(The calorific value of blast furnace gas is 750Kcal / Nm 3 ), reducing system energy consumption and improving the overall economic benefits of the system;

[0106] In this embodiment, the heat medium with a temperature of 300°C discharged after heat exchange with the activated carbon is sent to the ultra-low temperature SCR denitration reactor through the catalyst regeneration pipeline to perform thermal regeneration treatment on the SCR denitration catalyst (wherein the regeneration time is not more than 24 hours), thereby realizing online activation and regeneration of the catalyst. At the same time, the rational recovery and utilization of the waste heat from regeneration and analysis in the activated carbon regeneration tower is realized, thereby improving the energy utilization efficiency.

[0107] The above is only a specific embodiment of the present invention, and cannot be used to limit the scope of the invention. Therefore, the replacement of equivalent components, or equivalent changes and modifications made according to the protection scope of the patent of the present invention, should still fall within the scope of this patent. In addition, the technical features of the present invention can be freely combined with each other, with each other and with each other, and with each other.

Claims

1. An activated carbon desulfurization and SCR denitrification coupling system for sintering pellet flue gas, characterized in that: The system includes a desulfurization and denitrification reactor and an activated carbon regeneration tower; Wherein, the desulfurization and denitration reactor is provided with an ultra-low temperature SCR denitration reaction zone and an activated carbon desulfurization reaction zone connected from top to bottom, or the desulfurization and denitration reactor includes an activated carbon desulfurization reactor and an ultra-low temperature SCR denitration reactor that are independent and connected to each other, the activated carbon desulfurization reaction zone or the activated carbon desulfurization reactor is respectively provided with a first activated carbon inlet, a flue gas inlet and a first activated carbon outlet, the ultra-low temperature SCR denitration reaction zone or the ultra-low temperature SCR denitration reactor is respectively provided with an ammonia inlet and a clean flue gas outlet; an ammonia pre-activation device is provided on the ammonia injection pipeline connected to the ammonia inlet, the ammonia pre-activation device includes an ammonia pre-activator and a visible light filter, the ammonia pre-activator is used to activate ammonia by reacting with oxygen under the catalytic action of an ammonia activation catalyst under irradiation of the visible light filter; the visible light source is obtained by filtering out the ultraviolet light in the xenon lamp, and the visible light filter is used to further filter out the light in the light source that has a negative impact on the ammonia activation catalyst; a plurality of SCR denitration catalyst layers are also provided in the ultra-low temperature SCR denitration reaction zone or the ultra-low temperature SCR denitration reactor; The activated carbon regeneration tower is provided with a heating zone, a degassing zone and a cooling zone which are connected in sequence from top to bottom, the heating zone is provided with a second activated carbon inlet and a heat medium inlet, and the cooling zone is provided with a second activated carbon outlet; the first activated carbon inlet and the first activated carbon outlet are connected with the second activated carbon outlet and the second activated carbon inlet respectively through an activated carbon delivery pipeline and an activated carbon regeneration delivery pipeline; Among them, the heat medium inlet is connected to the hot air furnace through a heat medium pipeline; the ultra-low temperature SCR denitration reaction zone or the ultra-low temperature SCR denitration reactor is also provided with an ammonia nitrogen uniform distribution plate, and the ammonia nitrogen uniform distribution plate is located between the ammonia inlet and the SCR denitration catalyst layer.

2. The system according to claim 1, characterized in that The vertical distance between the ammonia nitrogen uniform distribution plate and the ammonia gas inlet is 1-2m.

3. The system according to claim 1 or 2, characterized in that: The heating zone is also provided with a heat medium outlet, and the heat medium outlet is connected to the heat medium inlet of the ultra-low temperature SCR denitration reaction zone or the ultra-low temperature SCR denitration reactor through a catalyst regeneration pipeline via a heat medium valve.

4. The system according to claim 3, characterized in that When an ammonia nitrogen uniform distribution plate is provided in the ultra-low temperature SCR denitration reaction zone or the ultra-low temperature SCR denitration reactor, the heat medium inlet is arranged below the ammonia nitrogen uniform distribution plate.

5. A coupling method of activated carbon desulfurization and SCR denitrification of sintering pellet flue gas, characterized in that: The method is achieved by using the activated carbon desulfurization and SCR denitrification coupling system for sintering pellet flue gas according to any one of claims 1 to 4, and comprises: (1) The sintering pellet flue gas is brought into reverse contact with the activated carbon to desulfurize the sintering pellet flue gas, and the desulfurized activated carbon is heated, regenerated, and then recycled for flue gas desulfurization; (2) irradiating a visible light filter and reacting ammonia with oxygen under the catalytic action of an ammonia activation catalyst to activate the ammonia and obtain a reducing agent; (3) After the desulfurized flue gas is mixed with the reducing agent, the flue gas is denitrated under the action of an SCR denitration catalyst.

6. The method according to claim 5, characterized in that In step (1), the temperature of the sintering pellet flue gas is in the range of 120-150°C.

7. The method according to claim 5, characterized in that In step (1), the desulfurized activated carbon is heated and regenerated using a heat medium from a hot blast furnace, wherein the temperature of the heat medium is in the range of 500-600°C.

8. The method according to claim 5, characterized in that In step (3), the desulfurized flue gas is mixed with the reducing agent so that the velocity deviation coefficient of the flue gas is reduced to less than 10%.

9. The method according to claim 5, characterized in that In step (3), the temperature of the denitration treatment is ≤120°C.

10. The method according to claim 5 or 7, characterized in that: The method further comprises utilizing the cooled heat medium to perform thermal regeneration treatment on the SCR denitration catalyst, wherein the temperature range of the cooled heat medium is 280-420°C.

11. The method according to claim 5, characterized in that The concentration of sulfur dioxide in the flue gas after desulfurization is 20mg / Nm 3 Below, the nitrogen oxide concentration in the clean flue gas obtained after denitrification treatment is 35mg / Nm 3 Below, the concentration of other pollutants is <0.5 ng TEQ / Nm 3 .

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