Flue gas desulfurization equipment with liquid breaking function and desulfurization method

Abstract

The invention belongs to the technical field of flue gas desulfurization, and discloses flue gas desulfurization equipment with a liquid breaking function and a desulfurization method. A grating plate and a plurality of spraying layers are sequentially mounted in the absorption tower along a flowing path of flue gas in the absorption tower; a plurality of liquid breaking devices are installed on grating holes, facing the spraying layer, of the grating plate, a plurality of through holes are formed in the surfaces of the liquid breaking devices at fixed intervals, and the size of the through holes is smaller than that of the grating holes of the grating plate. By arranging the liquid breaking device on the grating plate, when absorption liquid passes through the liquid breaking device and the grating plate, the liquid is cut into finer fog drops, so that the surface area of the liquid drops is increased, the absorption efficiency is improved, the type selection allowance of a corresponding circulating pump does not need to be increased at the same time, and the power consumption of a desulfurization process is further reduced; due to the design of the liquid breaking device and the grating plate, the diameter of the liquid drops can be reduced, the splashing height of the liquid drops is reduced, the liquid drops are effectively prevented from rebounding, and the stability of the absorption process is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of flue gas desulfurization, and in particular relates to a flue gas desulfurization device with a liquid breaking function and a desulfurization method. Background Art

[0002] The existing electrolytic aluminum industry is gradually adding deep purification devices, and most of the purification process projects use limestone-gypsum wet desulfurization process (hereinafter referred to as "wet desulfurization process"). Due to the common characteristics of large flue gas volume and low SO2 concentration in flue gas in electrolytic aluminum projects, there is distortion in the professional selection calculation software for wet desulfurization process. In order to ensure that pollutants can be discharged in compliance with standards, the desulfurization design unit can only increase the selection margin of the slurry circulation pump, an important equipment in the wet desulfurization process, resulting in an increase in the power consumption of the wet desulfurization process. Summary of the invention

[0003] In order to solve the problems in the background technology, the present invention provides a flue gas desulfurization device and a desulfurization method with a liquid breaking function.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A flue gas desulfurization device with a liquid breaking function, comprising an absorption tower;

[0006] Along the flow path of the flue gas in the absorption tower, grid plates and a plurality of spray layers are sequentially installed in the absorption tower;

[0007] A plurality of liquid-breaking devices are installed on the grid holes of the grid plate facing the spray layer, and a plurality of through holes are provided on the surface of the liquid-breaking devices at fixed intervals, and the size of the through holes is smaller than the grid holes of the grid plate.

[0008] Preferably, a smoke inlet and a smoke outlet are provided on the surface of the absorption tower;

[0009] The smoke inlet is located 200 to 1000 mm below the grid plate, and the smoke outlet is located above the spray layer;

[0010] The spray layer is located 1500-2300 mm above the grid plate.

[0011] Preferably, the liquid breaking device is in the shape of a cone or a trapezoid, the bottom of which is connected to the grid plate, the cone angle is 75-80°, the height is 45-60 mm, and the cone has triangular through holes with a diameter of 25-30 mm uniformly distributed at intervals of 30-40 mm.

[0012] Preferably, the height of the grid plate is 20-30 mm, the grid holes on the surface are square holes with a side length of 30-50 mm, and the square holes are welded to the liquid breaking device.

[0013] Preferably, the grating plate is made of stainless steel alloy, or carbon steel coated with an anti-corrosion layer, and the thickness of the anti-corrosion layer is 3 to 4 mm.

[0014] Preferably, the coating of the anti-corrosion layer is one of epoxy resin coating, polyurethane coating, fluorocarbon coating, glass flake coating and rubber coating.

[0015] Preferably, it also includes a plurality of support beams and a plurality of tower wall supports;

[0016] The support beam is located at the bottom of the grid plate, and both ends are fixedly connected to the inner wall of the absorption tower to support the grid plate;

[0017] The tower wall brackets are fixedly connected to the inner wall of the absorption tower, and a plurality of the tower wall brackets are evenly arranged along the circumference of the grid plate for being fixedly connected to the grid plate.

[0018] Preferably, spray liquid is stored at the bottom of the absorption tower, and a circulation pump is installed outside the absorption tower, one end of the circulation pump is connected to the bottom of the absorption tower through a pipeline, and the other end of the circulation pump is connected to the spray layer through a pipeline.

[0019] A desulfurization method, used for the above-mentioned flue gas desulfurization equipment with liquid breaking function, comprises the following steps:

[0020] The flue gas to be desulfurized is transported to the absorption tower

[0021] Along the flow path of the flue gas in the absorption tower, the flue gas is divided into several smoke columns by means of grid plates and liquid breaking devices;

[0022] The smoke column is sprayed through a spray layer to perform liquid breaking treatment;

[0023] The flue gas after the liquid breaking treatment is discharged from the absorption tower.

[0024] Preferably, the smoke column is sprayed by a spray layer to perform liquid breaking treatment, comprising the following steps:

[0025] The spray liquid at the bottom of the absorption tower is transported to the spray layer through a circulating pump outside the absorption tower;

[0026] The spray liquid is evenly sprayed into the smoke column through the nozzles of the spray layer, where it contacts and mixes with the smoke;

[0027] During the contact and mixing process, the sulfides in the flue gas undergo physical absorption and chemical reactions with the components in the spray liquid to generate corresponding salts and water.

[0028] Beneficial effects of the present invention:

[0029] 1. The present invention arranges a liquid breaking device on the grid plate. When the absorption liquid passes through the liquid breaking device and the grid plate, the liquid is cut into finer droplets, thereby increasing the surface area of ​​the droplets and improving the absorption efficiency. The selection margin of the corresponding circulation pump does not need to be increased blindly, thereby reducing the power consumption of the desulfurization process. In addition, the design of the liquid breaking device and the grid plate can also reduce the diameter of the droplets, reduce the splashing height of the droplets, effectively prevent the droplets from rebounding, and ensure the stability of the absorption process.

[0030] 2. After the present invention installs the liquid breaking device at a position 1m away from the top elevation of the absorption tower inlet, the relative standard deviation of the velocity distribution at the cross section is optimized to 25.3%. Since the relative standard deviation change rate of the velocity distribution at the same cross section reaches about 65%, the contact area between the flue gas and the slurry is greatly improved. After the liquid breaking device is installed, the selection margin of a single slurry circulation pump in the wet desulfurization process of the electrolytic aluminum industry can be reduced from 40% to 25%, thereby reducing the power consumption of the wet desulfurization process, and the power consumption per ton of aluminum is reduced by about 1.7kwh / (ht).

[0031] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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.

[0033] Figure 1 A schematic structural diagram of a flue gas desulfurization device with a liquid breaking function according to the present invention is shown;

[0034] Figure 2 A flow chart of a desulfurization method of the present invention is shown;

[0035] Figure 3 The relative standard deviation cloud diagram of velocity distribution at the cross section of the grid plate (without liquid breaking device) at a height of 1m from the top of the absorption tower inlet is shown;

[0036] Figure 4 The relative standard deviation cloud diagram of velocity distribution at the cross section of the grid plate (with liquid breaking device installed) at a height of 1m from the top of the absorption tower inlet is shown.

[0037] In the figure: 1. grid plate; 2. support beam; 3. tower wall bracket; 4. liquid breaking device; 5. spray layer; 6. absorption tower; 601. flue gas inlet; 602. flue gas outlet; 7. circulation pump. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] A flue gas desulfurization device with liquid breaking function, such as Figure 1 As shown, the flue gas desulfurization equipment is mainly composed of an absorption tower 6, a grid plate 1, a spray layer 5 and a liquid breaking device 4. Among them, along the flow path of the flue gas in the absorption tower 6, the grid plate 1 and a plurality of spray layers 5 are sequentially installed in the absorption tower 6. When working, the flue gas enters the absorption tower 6 and first encounters the grid plate 1 during the flow process. The plate can effectively disperse the flue gas and increase its contact area with the spray layer 5. Then, the spray layer 5 sprays the absorption liquid, which fully contacts with the flue gas and absorbs pollutants such as SO2 therein.

[0040] A plurality of liquid breaking devices 4 are installed on the grid holes of the grid plate 1 facing the spray layer 5, and a plurality of through holes are provided on the surface of the liquid breaking devices 4 at fixed intervals. When the absorption liquid passes through the liquid breaking devices 4, the liquid flows down along the conical wall surface into the slurry pool at the bottom, and cannot form a liquid holding layer on the desulfurization device, thereby reducing the resistance of the flue gas desulfurization equipment.

[0041] Furthermore, if Figure 1 As shown, the surface of the absorption tower 6 is provided with a smoke inlet 601 and a smoke outlet 602. The smoke inlet 601 is located 200-1000 mm below the grid plate 1, and the smoke outlet 602 is located above the spray layer 5; the spray layer 5 is located 1500-2300 mm above the grid plate 1.

[0042] It should be noted that Figure 1In the figure, the flue gas inlet 601 is located 1000mm below the grid plate 1. This design allows the flue gas to enter the absorption tower 6 smoothly, avoiding the problem of poor flue gas flow caused by the inlet position being too high. At the same time, this layout also helps to increase the contact area between the flue gas and the spray water, thereby improving the purification effect. The flue gas outlet 602 is located 1500mm above the spray layer 5. This design ensures that the flue gas can be fully purified after passing through the spray layer 5. The spray layer 5 can efficiently absorb and decompose harmful substances in the flue gas, and the setting of the outlet position ensures that the purified flue gas can be discharged smoothly, avoiding secondary pollution.

[0043] Furthermore, the liquid breaking device 4 is in the shape of a cone or a trapezoid, with a cone angle of 75-80°, a height of 45-60 mm, and through holes with a diameter of 25-30 mm uniformly distributed in triangles at intervals of 30-40 mm on the cone (if there is not enough space, only one through hole can be provided). In addition, the height of the grid plate 1 is 20-30 mm, and the grid holes on the surface are square holes with a side length of 30-50 mm, and the square holes are connected to the through holes.

[0044] It should be noted that the advantages of conical and trapezoidal tables in liquid breaking are as follows:

[0045] (1) Increase contact area: The shape design of the conical table and the trapezoidal table allows the liquid to be fully distributed, increasing the contact area between the liquid and the flue gas and improving the pollutant absorption efficiency.

[0046] (2) Optimizing droplet breakup: The structures of the conical platform and the trapezoidal platform help break the liquid sprayed by the spray layer 5 into smaller droplets, increase the contact frequency between the droplets and the flue gas, and thus improve the absorption effect of pollutants such as SO2.

[0047] (3) Preventing the formation of liquid film: The design of the conical table and the trapezoidal table can effectively prevent the formation of liquid film, maintain full contact between flue gas and liquid, and improve desulfurization efficiency.

[0048] (4) Easy to clean and replace: The shapes of the conical table and the trapezoidal table are easy to clean and replace during equipment operation, reducing maintenance costs.

[0049] (5) Structural stability: The structural design of the conical platform and the trapezoidal platform has strong stability, which is beneficial to improving the operating life of the flue gas desulfurization equipment.

[0050] Furthermore, the grating plate 1 is made of stainless steel alloy or carbon steel with an anti-corrosion layer, and the thickness of the anti-corrosion layer is 3-4 mm. Specifically, the coating of the anti-corrosion layer is one of epoxy resin coating, polyurethane coating, fluorocarbon coating, glass flake coating and rubber coating.

[0051] It should be noted that the grating plate 1 made of stainless steel alloy or carbon steel with a 3-4 mm thick anti-corrosion layer has many significant advantages. First, it has extremely strong corrosion resistance and can effectively prevent the metal material from being corroded by corrosive substances in the environment, such as acids, alkalis, salts, etc., thereby greatly extending the service life of the grating plate 1. Secondly, the anti-corrosion layer has excellent weather resistance and can adapt to various climatic conditions, whether it is high temperature, low temperature, humid or dry environment, it can maintain its stable performance. In addition, the 3-4 mm thickness of the anti-corrosion layer provides strong physical protection, which can resist physical damage such as wear and scratches, further extending the service life of the grating plate 1. Most importantly, the application of the anti-corrosion layer greatly reduces the maintenance frequency and cost of the metal and reduces operating costs.

[0052] Further, Figure 1 The structure also includes a plurality of support beams 2 and tower wall brackets 3, wherein the support beam 2 is located at the bottom of the grid plate 1, and its two ends are welded to the inner wall of the absorption tower 6 for supporting the grid plate 1; the tower wall brackets 3 are fixedly connected to the inner wall of the absorption tower 6, and a plurality of them are evenly arranged along the circumference and welded to the edge of the grid plate 1.

[0053] Furthermore, spray liquid is stored at the bottom of the absorption tower 6, and a circulation pump 7 is installed outside the absorption tower 6, one end of the circulation pump 7 is connected to the bottom of the absorption tower 6 through a pipeline, and the other end is connected to the spray layer 5 through a pipeline.

[0054] It should be noted that in some optional solutions, a spray liquid storage tank with an effective capacity of 10 cubic meters is set at the bottom of the absorption tower 6, and the storage tank is connected to the circulation pump 7 through a dedicated pipeline. The circulation pump 7 uses a centrifugal pump of model CP-300, which has a flow capacity of 30 cubic meters per hour and can meet the spraying demand of the spray layer 5. One end of the circulation pump 7 is connected to the bottom of the absorption tower 6 through a pipeline, and the other end is connected to the spray layer 5 through another pipeline to ensure that the spray liquid can be continuously and evenly distributed to the entire spray layer.

[0055] like Figure 2 As shown, a desulfurization method is used for Figure 1 The flue gas desulfurization equipment with liquid breaking function comprises the following steps:

[0056] S1: The flue gas to be desulfurized is transported to the absorption tower 6.

[0057] S2: Along the flow path of the flue gas in the absorption tower 6, the flue gas is divided into several smoke columns through the grid plate 1 and the liquid breaking device 4.

[0058] S3: Spraying the smoke column through the spray layer 5 to perform liquid breaking treatment, including:

[0059] S301: The spray liquid at the bottom of the absorption tower 6 is transported to the spray layer 5 through the circulation pump 7 outside the absorption tower 6.

[0060] S302: The spray liquid is evenly sprayed into the smoke column through the nozzles of the spray layer 5, and is fully contacted and mixed with the smoke.

[0061] S303: During the contact and mixing process, the sulfides in the flue gas undergo physical absorption and chemical reactions with the components in the spray liquid to generate corresponding salts and water.

[0062] S4: The flue gas after the liquid breaking treatment is discharged from the absorption tower 6.

[0063] The specific process is given below in combination with S1-S5:

[0064] No liquid breaking device is used4

[0065] S1: The flue gas to be desulfurized (with a SO2 content of 800 mg / Nm3, an O2 content of 6%, and the rest being N2 and CO2) is transported to the absorption tower 6, and the operation time is 24 consecutive hours.

[0066] S2: Along the flow path of the flue gas in the absorption tower 6, the flue gas is divided into several smoke columns by the grid plate 1, and the diameter of each smoke column is 50 mm.

[0067] S3: Spraying the smoke column through the spray layer 5 to perform liquid breaking treatment, including:

[0068] S301: The spray liquid (composed of NaOH solution with a concentration of 2.5%) at the bottom of the absorption tower 6 is transported to the spray layer 5 through the circulation pump 7 outside the absorption tower 6 at a flow rate of 50m3 / h.

[0069] S302: The spray liquid is evenly sprayed into the smoke column through the nozzles of the spray layer 5, and is fully contacted and mixed with the smoke.

[0070] S303: During the contact and mixing process, the sulfide in the flue gas undergoes physical absorption and chemical reaction with the NaOH in the spray liquid to generate Na2SO3 and H2O. The reaction time is 2 seconds.

[0071] S4: The flue gas after the liquid breaking treatment is discharged from the absorption tower 6, and the SO2 content in the flue gas is reduced to below 50mg / Nm3.

[0072] Using liquid breaking device 4

[0073] S1: The flue gas to be desulfurized (with a SO2 content of 800 mg / Nm 3 , O2 content is 6%, the rest is N2 and CO2) is transported to the absorption tower 6, and the operation time is continuous 24 hours.

[0074] S2: Along the flow path of the flue gas in the absorption tower 6, the flue gas is divided into several smoke columns through the grid plate 1 and the liquid breaking device 4, and the diameter of each smoke column is 35 mm.

[0075] S3: Spraying the smoke column through the spray layer 5 to perform liquid breaking treatment, including:

[0076] S301: The circulation pump 7 outside the absorption tower 6 is used to pump the absorber at a flow rate of 60m 3 / h transports the spray liquid (consisting of NaOH solution with a concentration of 2.5%) at the bottom of the absorption tower 6 to the spray layer 5.

[0077] S302: The spray liquid is evenly sprayed into the smoke column through the nozzles of the spray layer 5, and is fully contacted and mixed with the smoke.

[0078] S303: During the contact and mixing process, the sulfide in the flue gas undergoes physical absorption and chemical reaction with the NaOH in the spray liquid to generate Na2SO3 and H2O, and the reaction time is 1.8 seconds.

[0079] S4: The flue gas after liquid breaking treatment is discharged from the absorption tower 6. At this time, the SO2 content in the flue gas is reduced to 30mg / Nm 3 the following.

[0080] The implementation results of the liquid breaking device 4 are as follows:

[0081] (1) The contact area between flue gas and spray liquid is increased, and the desulfurization efficiency is improved, which may increase the desulfurization efficiency to more than 97%.

[0082] (2) Liquid breaking device 4 helps to more effectively convert sulfide in flue gas into Na2SO3 and H2O, reducing the SO2 content in flue gas to 30 mg / Nm 3 the following.

[0083] The implementation results without using the liquid breaking device 4 are as follows:

[0084] (1) The contact area between the flue gas and the spray liquid is small, and the desulfurization efficiency may be low, which may only reach 85%-90%.

[0085] (2) The conversion of sulfides in flue gas to Na2SO3 and H2O may be slow, requiring longer reaction time and more spray liquid.

[0086] like Figure 3 and Figure 4 As shown in the figure, through flow field simulation analysis, before the flow equalization device (grid plate 1 + liquid breaking device 4) is installed, the relative standard deviation of the velocity distribution at the cross section 1m above the top elevation of the absorption tower 6 inlet is 74.4%. For details, see the attached Figure 3After the flow equalizer is installed at a height of 1m from the top of the absorption tower 6 inlet, the relative standard deviation of the velocity distribution at the cross section after the flow equalizer is optimized to 25.3%, see the attached Figure 4 . Since the relative standard deviation change rate of velocity distribution at the same cross section reaches about 65%, the contact area between flue gas and slurry is greatly increased. According to experimental data, after installing the equalizing device, the selection margin of a single slurry circulation pump in the wet desulfurization process of the electrolytic aluminum industry can be reduced from 40% to 25%, thereby reducing the power consumption of the wet desulfurization process, and the power consumption per ton of aluminum is reduced by about 1.7kwh / (ht).

[0087] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flue gas desulfurization equipment with liquid breaking function, characterized in that: comprising an absorption tower (6); Along the flow path of the flue gas in the absorption tower (6), a grid plate (1) and a plurality of spray layers (5) are sequentially installed in the absorption tower (6); A plurality of liquid-breaking devices (4) are installed on the grid holes of the grid plate (1) facing the spray layer (5), and a plurality of through holes are provided on the surface of the liquid-breaking devices (4) at fixed intervals, wherein the size of the through holes is smaller than the grid holes of the grid plate (1).

2. The flue gas desulfurization equipment with liquid breaking function according to claim 1, characterized in that: The absorption tower (6) is provided with a smoke inlet (601) and a smoke outlet (602) on its surface; The smoke inlet (601) is located 200 to 1000 mm below the grid plate (1), and the smoke outlet (602) is located above the spray layer (5); The spray layer (5) is located 1500 to 2300 mm above the grid plate (1).

3. The flue gas desulfurization equipment with liquid breaking function according to claim 1, characterized in that: The liquid breaking device (4) is in the shape of a cone or a trapezoid, the bottom of which is connected to the grid plate (1), the cone angle is 75-80°, the height is 45-60 mm, and the cone has triangular through holes with a diameter of 25-30 mm evenly distributed at intervals of 30-40 mm.

4. The flue gas desulfurization equipment with liquid breaking function according to claim 1, characterized in that: The height of the grid plate (1) is 20 to 30 mm, and the grid holes on the surface are square holes with a side length of 30 to 50 mm, and the square holes are welded to the liquid breaking device (4).

5. The flue gas desulfurization equipment with liquid breaking function according to claim 1, characterized in that: The material of the grid plate (1) is a stainless steel alloy, or carbon steel coated with an anti-corrosion layer, and the thickness of the anti-corrosion layer is 3 to 4 mm.

6. The flue gas desulfurization equipment with liquid breaking function according to claim 5, characterized in that: The coating of the anti-corrosion layer is one of epoxy resin coating, polyurethane coating, fluorocarbon coating, glass flake coating and rubber coating.

7. A flue gas desulfurization equipment with liquid breaking function according to any one of claims 1 to 6, characterized in that: It also includes a plurality of support beams (2) and a plurality of tower wall brackets (3); The support beam (2) is located at the bottom of the grid plate (1), and its two ends are fixedly connected to the inner wall of the absorption tower (6), so as to support the grid plate (1); The tower wall bracket (3) is fixedly connected to the inner wall of the absorption tower (6), and a plurality of the brackets are evenly arranged along the circumference of the grid plate (1) for being fixedly connected to the grid plate (1).

8. The flue gas desulfurization equipment with liquid breaking function according to claim 7, characterized in that: The bottom of the absorption tower (6) stores spray liquid, and a circulation pump (7) is installed outside the absorption tower (6). One end of the circulation pump (7) is connected to the bottom of the absorption tower (6) through a pipeline, and the other end is connected to the spray layer (5) through a pipeline.

9. A desulfurization method, characterized in that: The flue gas desulfurization equipment with liquid breaking function used in any one of claims 1 to 8 comprises the following steps: transporting the flue gas to be desulfurized to the absorption tower (6); Along the flow path of the flue gas in the absorption tower (6), the flue gas is divided into a plurality of smoke columns by means of a grid plate (1) and a liquid breaking device (4); The smoke column is sprayed through a spray layer (5) to perform liquid breaking treatment; The flue gas after the liquid breaking treatment is discharged from the absorption tower (6).

10. A desulfurization method according to claim 9, characterized in that: The smoke column is sprayed through the spray layer (5) to perform liquid breaking treatment, comprising the following steps: The spray liquid at the bottom of the absorption tower (6) is transported to the spray layer (5) through a circulation pump (7) outside the absorption tower (6); The spray liquid is evenly sprayed into the smoke column through the nozzles of the spray layer (5) to contact and mix with the smoke; During the contact and mixing process, the sulfides in the flue gas undergo physical absorption and chemical reactions with the components in the spray liquid to generate corresponding salts and water.

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