Apparatus and method for treating flue gas

Abstract

The application discloses a device and method for treating flue gas, which comprises a urea supply device, a flue gas pipeline, a cooling device, a dust removal device, a denitration device and an absorption device, wherein the urea supply device is provided with a urea outlet, the flue gas pipeline is provided with a high-temperature flue gas inlet, a urea inlet and a mixed flue gas outlet, the urea inlet is connected with the urea outlet, the cooling device is provided with a mixed flue gas inlet, a cooled flue gas outlet and a cooling medium inlet, the mixed flue gas inlet is connected with the mixed flue gas outlet, the dust removal device is provided with a cooled flue gas inlet and a dust-removed flue gas outlet, the cooled flue gas inlet is connected with the cooled flue gas outlet, the denitration device is provided with a dust-removed flue gas inlet and a denitration flue gas outlet, the dust-removed flue gas inlet is connected with the dust-removed flue gas outlet, and the absorption device is provided with a denitration flue gas inlet and a purified flue gas outlet. The device can be used for treating flue gas containing nitrogen oxides, bromine and / or hydrogen bromide, and the water consumption and treatment cost can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flue gas treatment, in particular to a device and method for treating flue gas. BACKGROUND

[0002] Hexabromocyclododecanes (HBCD) is mainly used as a flame retardant additive for the production of expanded polystyrene (EPS) and extruded polystyrene (XPS), and a small amount is used in textiles, electrical and electronic equipment. HBCD is not easy to degrade, can persist in the environment, and has biological accumulation and biological amplification potential. Related studies have shown that as the trophic level in the food web increases, the concentration of HBCD in the organism is higher, in addition, the surface-air exchange is active under seasonal and diurnal temperature fluctuations, which may enable HBCD to have long-distance migration potential through a series of jump deposition / volatilization.

[0003] As a hazardous waste, there is no related treatment process in China. Due to the high bromine content in HBCD, the emission of bromine content needs to be considered during the treatment process. At present, there is no requirement for the emission of bromine and bromide in the domestic “Integrated Emission Standard of Air Pollutants GB16297-1996” and “Integrated Emission Standard of Sewage GB 8978-1996”, but with the improvement of environmental emission requirements, the content of bromine and bromide in gas / water will be included in the environmental protection standard, and the emission standard of hydrogen bromide must be less than 5mg / m 3 It can be seen from the relevant provisions that the environmental protection standard is becoming increasingly stringent.

[0004] In the related art, the treatment method of the bromine-containing waste is to pass the bromine-containing organic waste through multiple stages of pyrolysis, into a reduction tank, and react with the reducing agent sulfur added into the reduction tank to generate hydrogen bromide waste gas. The generated hydrogen bromide waste gas enters a water absorption tower, and after multiple stages of absorption, when the concentration of hydrogen bromide in the water solution in the absorption tower reaches a certain amount, it is recovered. Since the bromine element is recovered and utilized, the purity of the recovered liquid is required to be high. The flue gas contains both bromine and hydrogen bromide, and the solubility of bromine in water is small, so a large amount of water is needed for absorption, and the treatment cost is high. SUMMARY

[0005] The present application aims to at least solve one of the technical problems in the related art. To this end, one object of the present application is to provide a device and method for treating flue gas containing nitrogen oxides (NO X ), bromine and / or hydrogen bromide, which can reduce the amount of water used and reduce the treatment cost.

[0006] In a first aspect, the present application provides a device for treating flue gas. According to an embodiment of the present application, the flue gas contains nitrogen oxides, hydrogen bromide and / or bromine, and the device for treating flue gas comprises:

[0007] a urea supply device having a urea outlet;

[0008] a flue gas pipeline having a high-temperature flue gas inlet, a urea inlet connected to the urea outlet, and a mixed flue gas outlet;

[0009] a cooling device having a mixed flue gas inlet connected to the mixed flue gas outlet, a cooled flue gas outlet, and a cooling medium inlet;

[0010] a dust removal device having a cooled flue gas inlet connected to the cooled flue gas outlet, and a dust-removed flue gas outlet;

[0011] a denitration device having a dust-removed flue gas inlet connected to the dust-removed flue gas outlet, and a denitration flue gas outlet;

[0012] an absorption device having a denitration flue gas inlet connected to the denitration flue gas outlet, and a purified flue gas outlet.

[0013] According to the device for treating flue gas of the above-mentioned embodiment of the present application, before entering the cooling device, urea solution is supplied to the flue gas pipeline by the urea supply device, mixed with the flue gas containing nitrogen oxides, bromine and / or hydrogen bromide to obtain mixed flue gas, and then the mixed flue gas is supplied to the denitration device after passing through the cooling device and the dust removal device. On the one hand, the flue gas containing nitrogen oxides, bromine and / or hydrogen bromide that has not passed through the cooling device has a higher temperature, and mixing it with the urea solution can make the urea in the urea solution decompose more completely and produce ammonia. On the other hand, the mixed flue gas is supplied to the denitration device after passing through the cooling device and the dust removal device, which can make the ammonia produced by the decomposition of urea in the mixed flue gas mix more uniformly with the flue gas containing nitrogen oxides, bromine and / or hydrogen bromide, thereby facilitating the improvement of denitration efficiency. The mixed flue gas is subjected to denitration treatment in the denitration device to obtain denitration mixed flue gas, and then the denitration mixed flue gas is supplied to the absorption device. The unreacted ammonia in the denitration mixed flue gas can dissolve in the water sprayed by the absorption device to form ammonia water, which can react with bromine and hydrogen bromide. Thus, the water consumption of the absorption device for absorbing bromine and hydrogen bromide in the denitration mixed flue gas can be reduced, and the processing cost can be reduced. In addition, urea has higher safety than ammonia water or ammonia. Therefore, using the device for treating flue gas to treat flue gas containing nitrogen oxides, bromine and / or hydrogen bromide can reduce water consumption, reduce processing cost, and improve denitration efficiency.

[0014] In addition, the device for treating flue gas according to the above-mentioned embodiments of the present application can further have the following additional technical features:

[0015] In some embodiments of the present application, the absorption device has a first spray zone, a second spray zone and a liquid storage zone defined from top to bottom, a first partition is arranged between the first spray zone and the second spray zone, the first partition has a first gap, the first spray zone is in communication with the second spray zone through the first gap, the denitration flue gas inlet is arranged in the first spray zone, the purified flue gas outlet is arranged in the second spray zone, the first spray zone is provided with a first nozzle, and the second spray zone is provided with a second nozzle. In this way, the absorption efficiency can be improved, and the floor area can be reduced.

[0016] In some embodiments of the present application, the absorption device further comprises a first circulating pump having a first liquid inlet and a first liquid outlet, the first liquid inlet is connected to the liquid storage zone, and the first liquid outlet is connected to at least one of the first nozzle and the second nozzle. In this way, the water consumption can be reduced.

[0017] In some embodiments of the present application, the absorption device further comprises a second circulating pump having a second liquid inlet and a second liquid outlet, the second liquid inlet is connected to the liquid storage zone, and the second liquid outlet is connected to the cooling medium inlet.

[0018] In some embodiments of the present application, the liquid storage zone has a liquid supplementing port. In this way, water can be supplemented to the liquid storage zone.

[0019] In some embodiments of the present application, the denitration flue gas inlet is arranged at the side of the first spray zone, the first gap is arranged at the side of the first partition away from the denitration flue gas inlet, and the purified flue gas outlet is arranged at the side of the second spray zone away from the first gap. In this way, the absorption efficiency of the absorption device can be improved.

[0020] In some embodiments of the present application, the first partition comprises a first flow guide surface inclined along the first gap. In this way, the discharge of the absorption liquid in the first spray zone can be facilitated.

[0021] In some embodiments of the present application, the first flow guide surface has an angle of 5°-10° with the horizontal direction.

[0022] In some embodiments of the present application, a second partition is arranged between the liquid storage zone and the second spray zone, the second partition has a second gap, and the liquid storage zone is in communication with the second spray zone through the second gap. In this way, the absorption efficiency of the absorption device can be improved.

[0023] In some embodiments of the present application, the second baffle plate comprises a second flow guide surface inclined to the second gap. In this way, the discharge of the absorbent liquid in the second spray zone can be facilitated.

[0024] In some embodiments of the present application, the second flow guide surface forms an angle of 5-10° with the horizontal direction.

[0025] In some embodiments of the present application, the absorption device comprises a demister connected to the purified flue gas outlet, a gas-water separator connected to the second gap, and a filter device connected to the gas-water separator. In this way, the liquid droplets carried in the purified flue gas can be removed, the flue gas in the second spray zone can be prevented from entering the liquid storage area to cause pressure change and affect the safety performance, and the first circulating pump and the second circulating pump can be prevented from being blocked.

[0026] In a second aspect, the present application provides a method for treating flue gas by using the above-mentioned device for treating flue gas. According to embodiments of the present application, the method for treating flue gas comprises: (1) supplying urea solution into the flue gas pipeline to mix with flue gas containing nitrogen oxides, elemental bromine and / or hydrogen bromide to obtain mixed flue gas; (2) supplying the mixed flue gas to the cooling device for cooling to obtain cooled mixed flue gas; (3) supplying the cooled mixed flue gas to the dust removal device for dust removal to obtain dust-removed mixed flue gas; (4) supplying the dust-removed mixed flue gas to the denitration device for denitration treatment to obtain denitration-treated mixed flue gas; and (5) supplying the denitration-treated mixed flue gas to the absorption device to absorb the elemental bromine and / or hydrogen bromide to obtain purified flue gas.

[0027] According to the method for treating flue gas in the above-mentioned embodiments of the present application, the urea solution is mixed with the flue gas containing nitrogen oxides, bromine and / or hydrogen bromide before the flue gas is cooled, to obtain mixed flue gas, and the mixed flue gas is subjected to denitration after being cooled and dedusted. On the one hand, the flue gas containing nitrogen oxides, bromine and / or hydrogen bromide has a high temperature before being cooled, and mixing the flue gas with the urea solution can make the urea in the urea solution decompose more completely and produce ammonia. On the other hand, the ammonia produced by the decomposition of urea in the mixed flue gas can be mixed more uniformly with the flue gas containing nitrogen oxides, bromine and / or hydrogen bromide in the process of cooling and dedusting, thereby facilitating the improvement of the efficiency of subsequent denitration. The mixed flue gas after denitration is supplied to the absorption device, and the unreacted ammonia in the mixed flue gas after denitration can dissolve in the water sprayed by the absorption device to form ammonia water, which can react with bromine and hydrogen bromide. Therefore, the amount of water required for absorbing bromine and hydrogen bromide in the mixed flue gas after denitration can be reduced, and the processing cost can be reduced. In addition, urea has higher safety than ammonia water or ammonia. Therefore, the method for treating flue gas containing nitrogen oxides, bromine and / or hydrogen bromide can reduce the amount of water, reduce the processing cost and improve the denitration efficiency.

[0028] In addition, the method for treating flue gas according to the above-mentioned embodiments of the present application can have the following additional technical features:

[0029] In some embodiments of the present application, the method for treating flue gas further comprises: (6) supplying the absorption liquid in the absorption device to the cooling device to cool the mixed flue gas, or discharging the absorption liquid in the absorption device for evaporation crystallization to extract ammonium bromide therein.

[0030] In some embodiments of the present application, in step (1), the temperature of the flue gas containing nitrogen oxides, bromine and / or hydrogen bromide is not lower than 400℃.

[0031] In some embodiments of the present application, the concentration of the urea solution is 25wt%-33wt%.

[0032] In some embodiments of the present application, the mixed flue gas after denitration contains ammonia.

[0033] In some embodiments of the present application, in step (1), the mass ratio of urea in the urea solution to the nitrogen oxides is 1:(0.9-1.2).

[0034] Additional aspects and advantages of the present application will be partially given in the following description, partially will become obvious from the following description, or will be understood by the practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0035] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, including the references to the figures, in which:

[0036] Figure 1 is a schematic diagram of an apparatus for treating flue gas according to an embodiment of the present application;

[0037] Figure 2 is a schematic diagram of an absorption device according to an embodiment of the present application;

[0038] Figure 3 is a schematic diagram of a method for treating flue gas according to an embodiment of the present application.

[0039] Reference Signs:

[0040] 100 - urea supply device; 11 - urea outlet; 200 - flue gas duct; 21 - high-temperature flue gas inlet; 22 - mixed flue gas outlet; 23 - urea inlet; 300 - cooling device; 31 - mixed flue gas inlet; 32 - cooled flue gas outlet; 33 - cooling medium inlet; 400 - dust removal device; 41 - cooled flue gas inlet; 42 - dust-removed flue gas outlet; 500 - denitration device; 51 - dust-removed flue gas inlet; 52 - denitration flue gas outlet; 600 - absorption device; 61 - denitration flue gas inlet; 62 - purified flue gas outlet; 621 - mist eliminator; 63 - first spray zone; 64 - first partition; 641 - first gap; 642 - first flow guide surface; 65 - second spray zone; 66 - second partition; 661 - second gap; 662 - second flow guide surface; 663 - gas-water separator; 664 - filtration device; 67 - liquid storage zone; 671 - first absorption liquid outlet; 672 - second absorption liquid outlet; 673 - liquid supplement inlet; 681 - first spray head; 682 - second spray head; 691 - first circulating pump; 6911 - first liquid inlet; 6912 - first liquid outlet; 6913 - absorption liquid delivery main pipe; 6914 - absorption liquid delivery branch pipe; 692 - second circulating pump; 6921 - second liquid inlet; 6922 - second liquid outlet; 700 - fan; 800 - chimney. DETAILED DESCRIPTION

[0041] Embodiments of the present application are described in detail below with reference to the attached drawing figures, wherein the same or like reference numerals and letters throughout the figures denote the same or like elements or elements with the same or similar functionality. The embodiments described below are exemplary and are intended to be illustrative of the present application and are not to be construed as limiting thereof.

[0042] In the description of the present application, it needs to be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0043] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.

[0044] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0045] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through an intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be directly above or obliquely above the first feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature can be directly below or obliquely below the first feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.

[0046] In a first aspect of the present application, an apparatus for treating flue gas is provided. According to an embodiment of the present application, with reference to Figure 1The flue gas can be high-temperature flue gas containing nitrogen oxides, hydrogen bromide and / or bromine monomer generated after the HBCD-containing hazardous waste is burned in a rotary kiln. The device for treating the flue gas comprises a urea supply device 100, a flue gas pipeline 200, a cooling device 300, a dust removal device 400, a denitration device 500 and an absorption device 600.

[0047] According to an embodiment of the present application, referring to Figure 1 The urea supply device 100 can have a urea outlet 11 adapted to supply urea solution into the flue gas pipeline 200. It should be noted that the specific structure of the urea supply device 100 is not particularly limited, and those skilled in the art can select it according to actual needs. For example, the urea supply device 100 can include a spray gun adapted to spray urea solution.

[0048] According to an embodiment of the present application, referring to Figure 1 The flue gas pipeline 200 can have a high-temperature flue gas inlet 21, a urea inlet 23 connected to the urea outlet 11 and a mixed flue gas outlet 22. The flue gas containing nitrogen oxides, hydrogen bromide and / or bromine monomer generated after the HBCD-containing hazardous waste is burned in a rotary kiln can enter the flue gas pipeline 200 through the secondary combustion chamber and the waste heat boiler for heat recycling, and mix with the urea solution supplied by the urea supply device 100 into the flue gas pipeline 200 to obtain mixed flue gas. The flue gas containing nitrogen oxides, bromine monomer and / or hydrogen bromide that has not been cooled by the cooling device 300 has a relatively high temperature (which can be not lower than 400 DEG C), and mixing it with the urea solution can make the urea in the urea solution decompose more completely and produce ammonia gas. The ammonia gas not only can be used as a denitration agent for subsequent denitration treatment, but also can be dissolved in water sprayed by the absorption device 600 to form ammonia water, which can react with bromine monomer and hydrogen bromide. Therefore, the amount of water required for the absorption device 600 to absorb bromine monomer and hydrogen bromide in the mixed flue gas after denitration can be reduced, thereby reducing the processing cost. In addition, using urea has higher safety than directly using ammonia water or ammonia gas.

[0049] According to an embodiment of the present application, referring to Figure 1The cooling device 300 can have a mixed flue gas inlet 31, a cooled flue gas outlet 32, and a cooling medium inlet 33. The mixed flue gas inlet 31 can be connected to the mixed flue gas outlet 22. The mixed flue gas containing nitrogen oxides, elemental bromine, and / or hydrogen bromide obtained by mixing the flue gas containing nitrogen oxides, elemental bromine, and / or hydrogen bromide with the urea solution enters the cooling device 300 through the mixed flue gas inlet 31, and the cooling medium enters the cooling device 300 through the cooling medium inlet 33. The mixed flue gas containing nitrogen oxides, elemental bromine, and / or hydrogen bromide obtained by mixing the flue gas containing nitrogen oxides, elemental bromine, and / or hydrogen bromide with the urea solution is cooled under the action of the cooling medium (the temperature of the cooled mixed flue gas can be 180-200°C), and the ammonia generated by the decomposition of urea in the mixed flue gas and the flue gas containing nitrogen oxides, elemental bromine, and / or hydrogen bromide can be more uniformly mixed during the cooling process, thereby facilitating the improvement of the efficiency of the subsequent denitration treatment. It should be noted that the specific type of the cooling device 300 is not particularly limited, and a person skilled in the art can select it according to actual needs as long as the purpose of cooling the flue gas can be achieved. For example, the cooling device 300 can include a quench tower.

[0050] According to an embodiment of the present application, with reference to Figure 1 The dust removal device 400 can have a cooled flue gas inlet 41 and a dedusted flue gas outlet 42. The cooled flue gas inlet 41 can be connected to the cooled flue gas outlet 32. The mixed flue gas obtained after being cooled by the cooling device 300 enters the dust removal device 400 through the cooled flue gas outlet 32 and the cooled flue gas inlet 41 to remove dust therein, and the ammonia generated by the decomposition of urea in the mixed flue gas and the flue gas containing nitrogen oxides, elemental bromine, and / or hydrogen bromide can be more uniformly mixed during the dust removal process. It should be noted that the specific type of the dust removal device 400 is not particularly limited, and a person skilled in the art can select it according to actual needs as long as the purpose of dust removal of the cooled mixed flue gas can be achieved. As a specific example, the dust removal device 400 can include a bag filter.

[0051] According to an embodiment of the present application, with reference to Figure 1The denitration device 500 can have a dedusted flue gas inlet 51 and a denitration flue gas outlet 52, and the dedusted flue gas inlet 51 can be connected with the dedusted flue gas outlet 42. The mixed flue gas obtained after dedusting by the dedusting device 400 enters the denitration device 500 through the dedusted flue gas inlet 51 from the dedusted flue gas outlet 42, and the denitration device 500 is suitable for denitration treatment of the mixed flue gas after dedusting. In the denitration device 500, the ammonia gas generated by the decomposition of urea can react with the nitrogen oxides in the flue gas containing nitrogen oxides, elemental bromine and / or hydrogen bromide, so as to remove the nitrogen oxides in the mixed flue gas. The mixed flue gas is supplied to the denitration device 500 through the cooling device 300 and the dedusting device 400, and the ammonia gas generated by the decomposition of urea in the mixed flue gas can also be mixed with the flue gas containing nitrogen oxides, elemental bromine and / or hydrogen bromide more uniformly, thereby facilitating the improvement of the denitration efficiency. It should be noted that the specific type of the denitration device 500 is not particularly limited, and those skilled in the art can select according to actual needs, as long as the purpose of denitration can be achieved. As a specific example, the denitration device 500 can be a selective catalytic reduction (SCR) reactor.

[0052] According to an embodiment of the present application, referring to Figure 1 The absorption device 600 can have a denitration flue gas inlet 61 and a purified flue gas outlet 62, and the denitration flue gas inlet 61 can be connected with the denitration flue gas outlet 52. The denitration mixed flue gas enters the absorption device 600 through the denitration flue gas inlet 61 from the denitration flue gas outlet 52, and the unreacted ammonia gas in the denitration mixed flue gas can be dissolved in the water sprayed by the absorption device 600 to form ammonia water, and the ammonia water can react with elemental bromine and hydrogen bromide, thereby reducing the amount of water required for the absorption device 600 to absorb elemental bromine and hydrogen bromide in the denitration mixed flue gas, thereby reducing the processing cost.

[0053] According to an embodiment of the present application, referring to Figure 2The absorption device 600 is provided with a first spray zone 63, a second spray zone 65 and a liquid storage zone 67 defined from top to bottom, a first partition 64 is arranged between the first spray zone 63 and the second spray zone 65, the first partition 64 is provided with a first gap 641, the first spray zone 63 is communicated with the second spray zone 65 through the first gap 641, a denitration flue gas inlet 61 is arranged in the first spray zone 63, a purified flue gas outlet 62 is arranged in the second spray zone 65, a first nozzle 681 is arranged in the first spray zone 63, and a second nozzle 682 is arranged in the second spray zone 65. The denitration mixed flue gas can enter the first spray zone 63 through the denitration flue gas inlet 61, the first nozzle 681 in the first spray zone 63 sprays water thereon, the unreacted ammonia in the denitration mixed flue gas can be dissolved in the water sprayed by the first nozzle 681 to form ammonia water, and reacts with the elemental bromine and hydrogen bromide in the denitration mixed flue gas, thereby the absorption efficiency can be improved and the water consumption can be reduced. The mixed flue gas after being sprayed in the first spray zone 63 can enter the second spray zone 65 through the first gap 641, and the elemental bromine and hydrogen bromide are subjected to absorption treatment again, thereby the absorption effect is improved. The absorption liquid flowing out of the first spray zone 63 and the second spray zone 65 can be stored in the liquid storage zone 67, and the first spray zone 63, the second spray zone 65 and the liquid storage zone 67 are arranged from top to bottom, thereby the floor area can be reduced, and a circulating pump for conveying the absorption liquid to the liquid storage zone 67 is not needed.

[0054] It should be noted that the specific positions of the denitration flue gas inlet 61, the purified flue gas outlet 62 and the first gap 641 are not particularly limited, and a person skilled in the art can select them according to actual needs. As a preferred scheme, referring to Figure 2 , the denitration flue gas inlet 61 can be arranged at the side of the first spray zone 63, the first gap 641 can be arranged at the side of the first partition 64 away from the denitration flue gas inlet 61, and the purified flue gas outlet 62 can be arranged at the side of the second spray zone 65 away from the first gap 641, thereby the residence time of the denitration mixed flue gas in the first spray zone 63 and the second spray zone 65 can be increased, and the absorption efficiency can be improved.

[0055] In order to further improve the absorption efficiency, the absorption device 600 can also be provided with a partition to define three or more spray zones and the liquid storage zone 67 from top to bottom, and the nozzles are arranged in each spray zone, the denitration flue gas inlet 61 is arranged in the uppermost spray zone, and the purified flue gas outlet 62 is arranged in the lowermost spray zone.

[0056] According to the embodiments of the present application, referring to Figure 2The first guide surface 642 on the first partition plate 64 is inclined along the first gap 641. The included angle a1 between the first guide surface 642 and the horizontal direction is preferably 5-10°, for example, 5°, 6°, 7°, 8°, 9°, 10°, etc. The inventor finds that if the included angle a1 between the first guide surface 642 and the horizontal direction is too large, the speed of the mixed flue gas flowing downward is too fast, the contact time with the absorption liquid is too short, which is not conducive to the absorption of bromine and hydrogen bromide; if the included angle a1 between the first guide surface 642 and the horizontal direction is too small, it is not conducive to the discharge of the absorption liquid in the first spray area 63, and the absorption liquid remaining on the first partition plate 64 is easy to cause corrosion. Therefore, by controlling the included angle a1 between the first guide surface 642 and the horizontal direction within the above range, the present application not only facilitates the discharge of the absorption liquid in the first spray area 63, avoids the corrosion caused by the absorption liquid remaining on the first partition plate 64, but also facilitates the absorption of bromine and hydrogen bromide.

[0057] According to an embodiment of the present application, referring to Figure 2 The absorption device 600 can further include a first circulating pump 691 having a first liquid inlet 6911 and a first liquid outlet 6912. The storage area 67 has a first absorption liquid outlet 671, the first liquid inlet 6911 is connected to the first absorption liquid outlet 671, and the first liquid outlet 6912 is connected to at least one of the first spray head 681 and the second spray head 682. Thus, the absorption liquid stored in the storage area 67 can be delivered to at least one of the first spray head 681 and the second spray head 682 for recycling by the first circulating pump 691, thereby reducing water consumption. It can be understood that the connection mode of the first liquid outlet 6912 to the first spray head 681 and the second spray head 682 is not particularly limited, and those skilled in the art can select according to actual needs as long as the purpose of recycling the absorption liquid can be achieved. As a specific example, the first liquid outlet 6912 can be connected to two absorption liquid delivery branch pipes 6914 through an absorption liquid delivery main pipe 6913, and the two absorption liquid delivery branch pipes 6914 are respectively connected to the first spray head 681 of the first spray area 63 and the second spray head 682 of the second spray area 65.

[0058] According to an embodiment of the present application, referring to Figure 2The absorption device 600 can further comprise a second circulating pump 692 having a second liquid inlet 6921 and a second liquid outlet 6922, and the liquid storage area 67 has a second absorption liquid outlet 672, the second liquid inlet 6921 is connected with the second absorption liquid outlet 672, and the second liquid outlet 6922 is connected with the cooling medium inlet 33. In this way, the absorption liquid stored in the liquid storage area 67 can be delivered to the cooling device 300 through the second circulating pump 692, on the one hand, part of the absorption liquid can be used as the cooling medium to cool the mixed flue gas with a higher temperature, on the other hand, part of the absorption liquid can be vaporized, and the salt substances in the absorption liquid can enter the dust removal device with the flue gas to be removed, so as to avoid that the concentration of the salt substances in the absorption liquid stored in the liquid storage area 67 is too high, thereby being conducive to the absorption of bromine and hydrogen bromide; on the other hand, the emission of the bromine-containing wastewater can be avoided. Further, the liquid storage area 67 can further have a liquid supplementing port 673, when the liquid level of the liquid storage area 67 is too low, water can be supplemented into the liquid storage area 67 through the liquid supplementing port 673. Specifically, the position of the liquid supplementing port 673 can be higher than the first absorption liquid outlet 671 and the second absorption liquid outlet 672.

[0059] According to the embodiment of the present application, the liquid storage area 67 can be provided with an electric conductivity testing device (not shown), which can measure the electric conductivity of the absorption liquid in the liquid storage area 67, so as to determine the concentration of the salt substances in the absorption liquid according to the measurement result of the electric conductivity.

[0060] According to the embodiment of the present application, referring to Figure 2 , the liquid storage area 67 and the second spraying area 65 can be provided with a second partition plate 66, the second partition plate 66 has a second gap 661, and the liquid storage area 67 is communicated with the second spraying area 65 through the second gap 661. In this way, the residence time of the mixed flue gas in the second spraying area 65 can be increased, thereby improving the absorption efficiency. Further, the second partition plate 66 comprises a second flow guide surface 662 inclined along the second gap 661, and the included angle a2 between the second flow guide surface 662 and the horizontal direction is preferably 5°-10°, for example, can be 5°, 6°, 7°, 8°, 9°, 10°, etc., thereby not only being conducive to the discharge of the absorption liquid in the second spraying area 65, avoiding the corrosion caused by the retention of the absorption liquid on the second partition plate 66, but also being conducive to the absorption of bromine and hydrogen bromide.

[0061] According to the embodiment of the present application, referring to Figure 2 , the absorption device 600 can further comprise a demister 621 connected with the purified flue gas outlet 62. The demister 621 can remove the liquid droplets carried in the purified flue gas, thereby being conducive to improving the purification effect of the flue gas containing nitrogen oxides, bromine and / or hydrogen bromide.

[0062] According to the embodiment of the present application, referring to Figure 2The absorption device 600 can further comprise an air-water separator 663 connected to the second gap 661 and a filtering device 664 connected to the air-water separator 663. The air-water separator 663 can prevent the flue gas in the second spraying area 65 from entering the liquid storage area 67 to cause pressure change and affect the safety performance. The filtering device 664 can filter the insoluble substances in the absorption liquid to prevent the first circulating pump 691 and the second circulating pump 692 from being blocked.

[0063] According to an embodiment of the present application, referring to Figure 1 The device for treating flue gas can further comprise a fan 700 and a chimney 800. The fan 700 has an air inlet 71 connected to the purified flue gas outlet 62 and an air outlet 72 connected to the chimney 800. The purified flue gas obtained in the absorption device 600 can be extracted by the fan 700 and then discharged by the chimney 800, thereby improving the efficiency of treating flue gas.

[0064] Therefore, the device for treating flue gas can reduce the amount of water used, reduce the treatment cost, and improve the denitration efficiency when treating flue gas containing nitrogen oxides, elemental bromine, and / or hydrogen bromide.

[0065] In a second aspect of the present application, a method for treating flue gas by using the device for treating flue gas is provided. According to an embodiment of the present application, referring to Figure 3 The method for treating flue gas comprises:

[0066] S100: supplying a urea solution into a flue gas duct to mix with flue gas containing nitrogen oxides, elemental bromine, and / or hydrogen bromide

[0067] In this step, the urea solution is supplied into the flue gas duct to mix with the flue gas containing nitrogen oxides, elemental bromine, and / or hydrogen bromide to obtain mixed flue gas. Since the flue gas containing nitrogen oxides, elemental bromine, and / or hydrogen bromide has a high temperature before being cooled, mixing it with the urea solution can make the urea in the urea solution decompose more completely and produce ammonia gas. The ammonia gas not only serves as a denitration agent for subsequent denitration treatment, but also dissolves in the water sprayed by the absorption device to form ammonia water, which can react with elemental bromine and hydrogen bromide. Therefore, the amount of water required for the absorption device to absorb elemental bromine and hydrogen bromide in the mixed flue gas after denitration can be reduced, thereby reducing the treatment cost. In addition, using urea has higher safety than directly using ammonia water or ammonia gas.

[0068] Specifically, the temperature of the flue gas containing nitrogen oxides, elemental bromine, and / or hydrogen bromide can be not lower than 400°C, for example, 400°C, 420°C, 440°C, 460°C, 480°C, 500°C, 520°C, 540°C, 560°C, etc.

[0069] It should be noted that the concentration of the urea solution is not particularly limited, and those skilled in the art can select it according to actual needs. As a preferred solution, the concentration of the urea solution can be 25wt%-33wt%, for example, it can be 25wt%, 26wt%, 27wt%, 28wt%, 29wt%, 30wt%, 31wt%, 32wt%, 33wt% and the like. The inventors have found that if the concentration of the urea solution is too large, crystalline bodies are easily generated, which is not conducive to the supply of the urea solution; if the concentration of the urea solution is too small, the amount of water required is too large, and the cost is relatively high. Therefore, by controlling the concentration of the urea solution in the above range, the present application not only facilitates the supply of the urea solution, but also reduces the cost.

[0070] According to the embodiment of the present application, when the urea solution is supplied into the flue gas pipeline and mixed with the flue gas containing nitrogen oxides, elemental bromine and / or hydrogen bromide, the mass ratio of urea in the urea solution to nitrogen oxides in the flue gas containing nitrogen oxides, elemental bromine and / or hydrogen bromide can be 1:(0.9-1.2). The inventors have found that if the ratio of urea in the urea solution to NO X is too low, the generated ammonia is too little to effectively remove NO X in the subsequent process, and it is even more difficult to dissolve in the water sprayed by the absorption device to form ammonia water to improve the absorption efficiency; if the ratio of urea in the urea solution to NO X is too high, ammonia escape is easily caused. Therefore, by controlling the ratio of urea in the urea solution to NO X in the above range, the present application can effectively remove NO X in the subsequent process, and the mixed flue gas after denitrification contains unreacted ammonia, which can form ammonia water with water in the absorption device to improve the absorption efficiency.

[0071] S200: supplying the mixed flue gas to a cooling device for cooling

[0072] In this step, the mixed flue gas is supplied to the cooling device for cooling to obtain the cooled mixed flue gas, and the temperature of the cooled mixed flue gas can be 180℃-200℃, and the ammonia generated by the decomposition of urea in the mixed flue gas and the flue gas containing nitrogen oxides, elemental bromine and / or hydrogen bromide can be mixed more uniformly in the cooling process, thereby facilitating the improvement of the efficiency of the subsequent denitrification process.

[0073] S300: supplying the cooled mixed flue gas to a dust removal device for dust removal

[0074] In this step, the cooled mixed flue gas is supplied to the dust removal device for dust removal, and the ammonia gas generated by the decomposition of urea and the flue gas containing nitrogen oxides, elemental bromine and / or hydrogen bromide can be mixed more uniformly in the dust removal process, thereby facilitating the improvement of the efficiency of the subsequent denitration treatment.

[0075] S400: supplying the dust-removed mixed flue gas to the denitration device for denitration treatment

[0076] In this step, the dust-removed mixed flue gas containing ammonia gas generated by the decomposition of urea is supplied to the denitration device for denitration treatment, and the ammonia gas can act as a denitration agent to react with NOx in the dust-removed mixed flue gas X to remove NOx X , to obtain denitrated mixed flue gas.

[0077] S500: supplying the denitrated mixed flue gas to the absorption device for absorption of elemental bromine and / or hydrogen bromide

[0078] In this step, the denitrated mixed flue gas is supplied to the absorption device for absorption of elemental bromine and / or hydrogen bromide, to obtain purified flue gas. Since the unreacted ammonia gas in the denitrated mixed flue gas can dissolve in the water sprayed by the absorption device to form ammonia water, the ammonia water can react with elemental bromine and hydrogen bromide to form ammonium bromide, thereby reducing the amount of water required for the absorption device to absorb elemental bromine and hydrogen bromide in the denitrated mixed flue gas, and reducing the processing cost.

[0079] According to an embodiment of the present application, the method for treating flue gas can further comprise:

[0080] S600: supplying the absorption liquid in the absorption device to the cooling device or discharging for evaporation crystallization

[0081] In this step, when the conductivity of the absorption liquid in the storage area of the absorption device reaches a certain value, the absorption liquid can be supplied to the cooling device for cooling the mixed flue gas, or discharged for evaporation crystallization to extract ammonium bromide therein. By supplying the absorption liquid in the absorption device to the cooling device, on the one hand, part of the absorption liquid can be used as a cooling medium to cool the mixed flue gas with a relatively high temperature, and on the other hand, part of the absorption liquid can be vaporized, and the salt substances therein can enter the dust removal device with the flue gas for removal, thereby avoiding the concentration of salt substances in the absorption liquid stored in the storage area from being too high, and thereby facilitating the absorption of elemental bromine and hydrogen bromide; on the other hand, the discharge of bromine-containing wastewater can be avoided. In addition, if the amount of absorption liquid in the absorption device is insufficient, the absorption device can be watered, thereby facilitating the dissolution of ammonia gas generated by the decomposition of urea solution in water to form ammonia water, and thereby facilitating the absorption of elemental bromine and / or hydrogen bromide in the mixed flue gas.

[0082] Thus, the flue gas containing nitrogen oxides, bromine and / or hydrogen bromide is treated by the method for treating flue gas, so that the water consumption is reduced, the treatment cost is lowered, the denitration efficiency is improved, and the salt substances in the absorption liquid are relatively simple, facilitating subsequent recycling.

[0083] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. Furthermore, different embodiments or examples described in the present specification and the features of different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0084] Although the embodiments of the present application have been shown and described above, it should be understood that the above-described embodiments are exemplary and should not be construed as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. An apparatus for treating flue gas, characterized by, The flue gas contains nitrogen oxides, bromine and hydrogen bromide, and the equipment for treating the flue gas comprises: a urea supply device having a urea outlet; a flue gas pipeline having a high-temperature flue gas inlet, a urea inlet connected with the urea outlet, and a mixed flue gas outlet; a cooling device having a mixed flue gas inlet connected with the mixed flue gas outlet, a cooling flue gas outlet, and a cooling medium inlet; a dust removal device having a cooling flue gas inlet connected with the cooling flue gas outlet, and a dust removal flue gas outlet; a denitration device having a dust removal flue gas inlet connected with the dust removal flue gas outlet, and a denitration flue gas outlet; an absorption device having a denitration flue gas inlet connected with the denitration flue gas outlet, and a purified flue gas outlet; the absorption liquid in the absorption device is supplied to the cooling device to cool the mixed flue gas.

2. The apparatus for treating flue gas according to claim 1, characterized by, The absorption device is internally defined from top to bottom with a first spray zone, a second spray zone, and a liquid storage zone, a first partition is arranged between the first spray zone and the second spray zone, the first partition has a first gap, the first spray zone is in communication with the second spray zone through the first gap, the denitration flue gas inlet is arranged in the first spray zone, and the purified flue gas outlet is arranged in the second spray zone; the first spray zone is provided with a first spray head, and the second spray zone is provided with a second spray head.

3. The apparatus for treating flue gas according to claim 2, characterized in that, The absorption device further comprises: a first circulating pump having a first liquid inlet connected with the liquid storage zone, and a first liquid outlet connected with at least one of the first spray head and the second spray head.

4. The apparatus for treating flue gas according to claim 2, characterized by, The absorption device further comprises: a second circulating pump having a second liquid inlet connected with the liquid storage zone, and a second liquid outlet connected with the cooling medium inlet; the liquid storage zone is provided with a liquid supplementing opening.

5. The apparatus for treating flue gas according to claim 2, wherein The denitration flue gas inlet is arranged at a side of the first spray zone, the first gap is arranged at a side of the first partition away from the denitration flue gas inlet, and the purified flue gas outlet is arranged at a side of the second spray zone away from the first gap; the first partition comprises a first flow guide surface inclined along the first gap; an angle between the first flow guide surface and a horizontal direction is 5°-10°.

6. The apparatus for treating flue gas according to claim 2, wherein The liquid storage zone and the second spray zone are provided with a second partition, the second partition has a second gap, and the liquid storage zone is in communication with the second spray zone through the second gap; the second partition comprises a second flow guide surface inclined along the second gap; an angle between the second flow guide surface and a horizontal direction is 5°-10°.

7. The apparatus for treating flue gas according to claim 6, characterized in that, The absorption device comprises: a mist eliminator connected with the purified flue gas outlet; a gas-water separator connected with the second gap; a filtering device connected with the gas-water separator.

8. A method of treating flue gases using the apparatus of any one of claims 1 to 7, characterized in that, The method for treating the flue gas comprises: (1) supplying a urea solution into the flue gas pipeline to mix with flue gas containing nitrogen oxides, elemental bromine and hydrogen bromide to obtain mixed flue gas; (2) supplying the mixed flue gas to the cooling device to cool to obtain cooled mixed flue gas; (3) supplying the cooled mixed flue gas to the dust removal device to remove dust to obtain dust-removed mixed flue gas; (4) supplying the dust-removed mixed flue gas to the denitration device to perform denitration treatment to obtain denitration-treated mixed flue gas; (5) supplying the denitration-treated mixed flue gas to the absorption device to absorb the elemental bromine and / or hydrogen bromide to obtain purified flue gas; supplying the absorption liquid in the absorption device to the cooling device to cool the mixed flue gas.

9. The method of claim 8, wherein, Further comprising: (6) discharging the absorption liquid in the absorption device to perform evaporation crystallization to extract ammonium bromide therein.

10. The method according to claim 8 or 9, characterized in that, In step (1), the temperature of the flue gas containing nitrogen oxides, elemental bromine and / or hydrogen bromide is not lower than 400℃; the concentration of the urea solution is 25wt%-33wt%; the denitration-treated mixed flue gas contains ammonia gas; in step (1), the mass ratio of urea in the urea solution to the nitrogen oxides is 1:(0.9-1.2).

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