Flue gas desulfurization system and method

Abstract

The invention discloses a flue gas desulfurization system and method. The system comprises an annularly-collected flue gas treatment unit, an acid-making tail gas treatment unit and an electric demisting device, the annularly-collected flue gas treatment unit comprises a limestone absorption tower and a security absorption tower, the lower end of the limestone absorption tower is provided with an annularly-collected flue gas inlet, and the upper end of the limestone absorption tower is provided with a desulfurized flue gas outlet; a desulfurized flue gas inlet is formed in the lower end of the security absorption tower, a purified flue gas outlet is formed in the upper end of the security absorption tower, the desulfurized flue gas inlet and the desulfurized flue gas outlet are connected through a first pipeline, and a first sulfur dioxide detection assembly is arranged on the first pipeline; the acid-making tail gas treatment unit comprises a hydrogen peroxide absorption tower, the lower end of the hydrogen peroxide absorption tower is provided with an acid-making tail gas inlet, and the upper end is provided with a purified tail gas outlet; and the purified flue gas outlet and the purified tail gas outlet are connected with the electric demisting device. The system can remove sulfur dioxide in the circulating collection flue gas and the acid-making tail gas as much as possible, the process is simple, the operation cost is low, no other impurity elements such as sodium ions are introduced, and the subsequent treatment process is facilitated.

Description

Technical Field

[0001] The invention belongs to the field of metal smelting flue gas treatment, and in particular relates to a flue gas desulfurization system and method. Background Art

[0002] Copper metal smelting mainly uses sulfide ore as the main raw material. Therefore, the flue gas emitted during the smelting process is mainly sulfur dioxide and smoke dust. The flue gas with high sulfur dioxide content is purified and then sulfuric acid is produced using the "two-turn and two-absorption" process. The exhaust gas after acid production needs to be desulfurized before it can meet emission standards; the circulating flue gas collected in front of the simultaneous copper smelting furnace also needs to be desulfurized before it can meet emission standards. Different smelting enterprises use different process flows to treat these two tail gases. Commonly used treatment processes include organic amine desulfurization, sodium alkali, limestone gypsum, activated coke, etc. However, all of the above processes have certain defects. For example, the organic amine desulfurization method has a high cost of desulfurizer and a large steam consumption, which leads to high operating costs. At the same time, organic amines (ionic liquids) enter the subsequent reuse water system with wastewater, affecting the COD index in the reuse water. Although the sodium alkali method has high desulfurization efficiency, short process flow and simple operation, the cost of desulfurizer is high, and a large amount of sodium salt is introduced, resulting in continuous enrichment of sodium salt in the reuse water system. The limestone gypsum method is mature in technology, but the desulfurization efficiency is relatively low because a certain amount of gypsum particles will inevitably be entrained in the flue gas. The activated coke treatment process has high operating costs, high energy consumption, and produces greenhouse gas CO at high temperatures. 2 , causing secondary pollution, not meeting low-carbon requirements, complex process, large one-time investment, small activated coke particle size, and easy to cause dust pollution. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, one object of the present invention is to provide a flue gas desulfurization system and method. The system can remove sulfur dioxide from the flue gas and the tail gas of the acid production plant as much as possible, has a simple process and low operating cost, does not introduce other impurity elements such as sodium ions, and is convenient for subsequent treatment processes. Specifically, the content of sulfur dioxide in the purified flue gas is less than 85mg / Nm 3 , the content of sulfur dioxide in the purified exhaust gas is not more than 30mg / Nm 3 .

[0004] In one aspect of the present invention, the present invention provides a flue gas desulfurization system. According to an embodiment of the present invention, the system comprises:

[0005] The ring-collected flue gas treatment unit comprises:

[0006] A limestone absorption tower, wherein the lower end of the limestone absorption tower is provided with a ring-collecting flue gas inlet, and the upper end is provided with a desulfurized flue gas outlet;

[0007] A security absorption tower, wherein a desulfurized flue gas inlet is provided at the lower end of the security absorption tower, and a purified flue gas outlet is provided at the upper end, wherein the desulfurized flue gas inlet and the desulfurized flue gas outlet are connected via a first pipeline, wherein a first sulfur dioxide detection component is provided on the first pipeline, and based on the display of the first sulfur dioxide detection component, the security absorption tower uses water or hydrogen peroxide as a spray liquid;

[0008] An acid-making tail gas treatment unit, the acid-making tail gas treatment unit comprising a hydrogen peroxide absorption tower, the lower end of the hydrogen peroxide absorption tower is provided with an acid-making tail gas inlet, and the upper end is provided with a purified tail gas outlet;

[0009] An electric demisting device, wherein the purified flue gas outlet and the purified tail gas outlet are connected to the electric demisting device.

[0010] The system according to the above embodiment of the present invention includes a flue gas treatment unit, an acid production tail gas treatment unit and an electric demisting device. The flue gas treatment unit includes a limestone absorption tower and a security absorption tower. The lower end of the limestone absorption tower is provided with a flue gas inlet for collecting the flue gas, and the upper end is provided with a desulfurized flue gas outlet. The flue gas collected enters the limestone absorption tower from the flue gas inlet for collecting the flue gas. The sulfur dioxide in the flue gas collected is absorbed in the limestone absorption tower. Then, the desulfurized flue gas after the sulfur dioxide is removed is discharged from the desulfurized flue gas outlet. The lower end of the security absorption tower is provided with a desulfurized flue gas inlet. A purified flue gas outlet is provided at the upper end, and the desulfurization flue gas inlet and the desulfurization flue gas outlet are connected by a first pipe. A first sulfur dioxide detection component is provided on the first pipe. Based on the display of the first sulfur dioxide detection component, the security absorption tower uses water or hydrogen peroxide as the spraying liquid. According to the different content of sulfur dioxide in the desulfurization flue gas, the security absorption tower sprays water or hydrogen peroxide, which can ensure that the sulfur dioxide content in the discharged flue gas meets the standard, remove particulate matter in the flue gas, and avoid a large amount of particulate matter in the flue gas from entering the electric demisting device, while reducing production costs.

[0011] The acid production tail gas treatment unit includes a hydrogen peroxide absorption tower. Because the sulfur dioxide content in the acid production tail gas is relatively low, a hydrogen peroxide absorption tower with high desulfurization efficiency is selected under the premise of controlling costs and reducing side reactions. The lower end of the hydrogen peroxide absorption tower is provided with an acid production tail gas inlet, and the upper end is provided with a purified tail gas outlet. The acid production tail gas enters the hydrogen peroxide absorption tower from the acid production tail gas inlet. After the sulfur dioxide in the acid production tail gas is absorbed, the purified tail gas is discharged from the purified tail gas outlet. The purified flue gas outlet and the purified tail gas outlet are connected to the electric demister. The purified flue gas treated by the ring collection flue gas treatment unit and the purified tail gas treated by the acid production tail gas treatment unit pass through the electric demister and meet the emission standards. Therefore, the system can remove sulfur dioxide in the ring collection flue gas and the acid production tail gas as much as possible. It is simple to operate and has low operating costs. There is no introduction of other impurity elements such as sodium ions, which is convenient for subsequent treatment processes. Specifically, the content of sulfur dioxide in the purified flue gas is less than 85 mg / Nm 3, the content of sulfur dioxide in the purified exhaust gas is not more than 30mg / Nm 3 .

[0012] In addition, the flue gas desulfurization system according to the above embodiment of the present invention may also have the following technical features:

[0013] In some embodiments of the present invention, based on the first sulfur dioxide detection component showing that the sulfur dioxide content in the desulfurized flue gas is not less than 85 mg / Nm 3 The security absorption tower uses hydrogen peroxide as the spray liquid; based on the first sulfur dioxide detection component showing that the sulfur dioxide content in the desulfurized flue gas is less than 85mg / Nm 3 The safety absorption tower uses water as the spraying liquid, thereby removing particulate matter in the flue gas and ensuring that the sulfur dioxide content in the discharged flue gas meets the standard.

[0014] In some embodiments of the present invention, the ring-collected flue gas treatment unit further includes a booster fan and a first ring-collected flue gas pipeline, wherein the first ring-collected flue gas pipeline is arranged upstream of the ring-collected flue gas inlet and connected to the first ring-collected flue gas inlet, and the booster fan is arranged on the first ring-collected flue gas pipeline. Thus, a certain pressure can be applied to the ring-collected flue gas to ensure smooth desulfurization of the ring-collected flue gas.

[0015] In some embodiments of the present invention, the first flue gas collection pipeline includes a main pipeline, a first branch pipeline and a second branch pipeline, one end of the first branch pipeline and one end of the second branch pipeline are connected to one end of the main pipeline, the other end of the first branch pipeline is connected to the first flue gas collection inlet, the booster fan is arranged on the main pipeline, the first branch pipeline is provided with a first valve, the other end of the second branch pipeline is connected to the first pipeline, the second branch pipeline is provided with a second valve, and the desulfurized flue gas outlet is provided with a third valve. Thus, when a failure occurs in the limestone absorption tower, the continuous desulfurization of the flue gas collection is ensured.

[0016] In some embodiments of the present invention, the limestone absorption tower is connected to a limestone slurry replenishing device, thereby ensuring the continuous operation of the limestone absorption tower.

[0017] In some embodiments of the present invention, the limestone absorption tower is connected to a gypsum processing device.

[0018] In some embodiments of the present invention, the lower end of the limestone absorption tower is connected to an oxygen supply device, thereby oxidizing sulfite into sulfate.

[0019] In some embodiments of the present invention, a tube-trough type acid separation device is provided in the hydrogen peroxide absorption tower, thereby improving the desulfurization efficiency of the hydrogen peroxide absorption tower.

[0020] In some embodiments of the present invention, a foam trap is provided at the top of the hydrogen peroxide absorption tower, thereby reducing foam in the gas.

[0021] In some embodiments of the present invention, a second sulfur dioxide monitoring assembly is provided on the pipeline connecting the purified tail gas outlet and the electric demisting device, and the hydrogen peroxide absorption tower is connected to a hydrogen peroxide replenishing device, thereby ensuring the continuous operation of the hydrogen peroxide absorption tower.

[0022] In another aspect of the present invention, the present invention proposes a method for purifying sulfur dioxide in flue gas using the above system. According to an embodiment of the present invention, the method comprises:

[0023] (1) desulfurizing the collected flue gas to obtain desulfurized flue gas;

[0024] (2) detecting sulfur dioxide in the desulfurized flue gas;

[0025] (3) purifying the desulfurized flue gas based on the sulfur dioxide content in the desulfurized flue gas to obtain purified flue gas;

[0026] (4) desulfurizing the acid production tail gas to obtain purified tail gas;

[0027] (5) The purified flue gas and the purified tail gas are subjected to electrostatic demisting to obtain emission gas that meets the standards.

[0028] Therefore, the method can remove particulate matter and sulfur dioxide in the flue gas and sulfur dioxide in the acid production tail gas as much as possible, and the operation is simple, and the discharged flue gas meets the standard requirements.

[0029] In addition, the method for purifying sulfur dioxide in flue gas using the system according to the present invention may also have the following technical features:

[0030] In some embodiments of the present invention, step (3) specifically includes: the sulfur dioxide content in the desulfurized flue gas is less than 85 mg / Nm 3 , the desulfurized flue gas is purified by spraying water; the sulfur dioxide content in the desulfurized flue gas is not less than 85mg / Nm 3 The desulfurized flue gas is purified by spraying a hydrogen peroxide solution, thereby removing sulfur dioxide and particulate matter in the flue gas and reducing production costs.

[0031] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0033] Figure 1 is a schematic diagram of a flue gas desulfurization system according to an embodiment of the present invention;

[0034] Figure 2 is a schematic diagram of a flue gas desulfurization system according to another embodiment of the present invention;

[0035] Figure 3 It is a schematic diagram of a flue gas desulfurization system according to another embodiment of the present invention. DETAILED DESCRIPTION

[0036] The embodiments of the present invention are described in detail below, which are intended to explain the present invention but should not be construed as limiting the present invention.

[0037] In one aspect of the present invention, the present invention provides a flue gas desulfurization system. According to an embodiment of the present invention, reference is made to Figure 1 The system includes: a ring collection flue gas treatment unit, an acid production tail gas treatment unit and an electric demister 100. It should be noted that the electric demister is a conventional device in the art, which is used for acid production from smelting flue gas, treatment of tail gas from titanium dioxide calcination, and various acid mist treatments in chemical plants. Those skilled in the art can select a specific electric demister according to actual conditions.

[0038] According to an embodiment of the present invention, the flue gas treatment unit includes: a limestone absorption tower 200 and a security absorption tower 300. The lower end of the limestone absorption tower 200 is provided with a flue gas inlet 210, and the upper end is provided with a desulfurization flue gas outlet 220; the lower end of the security absorption tower 300 is provided with a desulfurization flue gas inlet 310, and the upper end is provided with a purified flue gas outlet 320. The desulfurization flue gas inlet 310 and the desulfurization flue gas outlet 220 are connected by a first pipeline 10. The first pipeline 10 is provided with a first sulfur dioxide detection component 400. Based on the display of the first sulfur dioxide detection component 400, the security absorption tower 300 uses water or hydrogen peroxide as a spray liquid, and the purified flue gas outlet 320 is connected to the electric demisting device 100.

[0039] The flue gas enters the limestone absorption tower 200 from the flue gas inlet 210, and the sulfur dioxide in the flue gas is absorbed in the limestone absorption tower 200, and then the desulfurized flue gas after the sulfur dioxide is removed is discharged from the desulfurized flue gas outlet 220. When the desulfurized flue gas passes through the first pipeline 10, the first sulfur dioxide detection component 400 can detect the sulfur dioxide content in the desulfurized flue gas discharged from the desulfurized flue gas outlet 220, and purify the desulfurized flue gas according to the specific content of sulfur dioxide. According to the different content of sulfur dioxide in the desulfurized flue gas, the security absorption tower 300 sprays different solutions, which can not only ensure that the sulfur dioxide content in the discharged flue gas meets the standard, but also remove particulate matter in the flue gas, and avoid a large amount of particulate matter in the flue gas from entering the electric demisting device 100, but also reduce the production cost.

[0040] According to an embodiment of the present invention, based on the first sulfur dioxide detection component 400 showing that the sulfur dioxide content in the desulfurized flue gas is not less than 85 mg / Nm 3 The security absorption tower 300 uses hydrogen peroxide as the spray liquid; based on the first sulfur dioxide detection component 400 showing that the sulfur dioxide content in the desulfurized flue gas is less than 85mg / Nm 3 , the security absorption tower 400 uses water as the spray liquid. If the sulfur dioxide content in the desulfurized flue gas is less than 85mg / Nm 3 At this time, the first sulfur dioxide detection component 400 gives a signal. After the security absorption tower 300 receives the signal, water is sprayed on the upper end of the security absorption tower 300. The desulfurized flue gas enters the security absorption tower 300 from the desulfurized flue gas inlet 310. The particulate matter in the desulfurized flue gas will be washed away by water, so that the purified flue gas with the particulate matter removed is discharged from the purified flue gas outlet 320. If the sulfur dioxide content in the desulfurized flue gas is not less than 85 mg / Nm 3 At this time, after the security absorption tower 300 receives the signal from the first sulfur dioxide detection device 400, the upper end of the security absorption tower 300 sprays a hydrogen peroxide solution, and the sulfur dioxide in the desulfurized flue gas will be further removed, and the particulate matter in the desulfurized flue gas will also be removed. Because the desulfurization efficiency of hydrogen peroxide is high, it can ensure that the sulfur dioxide in the desulfurized flue gas is removed as much as possible.

[0041] According to an embodiment of the present invention, the ring-collected flue gas treatment unit further includes a booster fan 20 and a first ring-collected flue gas pipeline 30, the first ring-collected flue gas pipeline 30 is arranged upstream of the ring-collected flue gas inlet 210 and connected to the first ring-collected flue gas inlet 210, and the booster fan 20 is arranged on the first ring-collected flue gas pipeline 30. The booster fan 20 can give a certain pressure to the ring-collected flue gas, ensuring that the ring-collected flue gas passes smoothly through the limestone absorption tower 200 and the security absorption tower 300.

[0042] According to an embodiment of the present invention, referring to Figure 2The first-ring flue gas collection pipeline includes a main pipeline 31, a first branch pipeline 32 and a second branch pipeline 33. One end of the first branch pipeline 32 and one end of the second branch pipeline 33 are connected to one end of the main pipeline 31, and the other end of the first branch pipeline 32 is connected to the first-ring flue gas collection inlet 210. The booster fan 20 is arranged on the main pipeline 31, and the first branch pipeline 32 is provided with a first valve 40. The other end of the second branch pipeline 33 is connected to the first pipeline 10, and the second branch pipeline 33 is provided with a second valve 50. A third valve 60 is provided at the desulfurization flue gas outlet 220. In production, if the limestone absorption tower 200 fails, the first valve 40 and the third valve 60 can be closed, and the second valve 50 is opened at this time, and the flue gas collected enters the safety absorption tower 300 through the main pipeline 31, the second branch pipeline 33, the first pipeline 10 and the desulfurization flue gas inlet 310 in sequence, and the hydrogen peroxide solution is sprayed in the safety absorption tower 300 to remove the sulfur dioxide in the flue gas collected, so that the limestone absorption tower 200 can be short-circuited for maintenance to ensure the continuous production. Further, the limestone absorption tower 200 can be connected to a slurry collection and storage device (not shown). When the limestone absorption tower 200 needs to be repaired, the slurry in the limestone absorption tower 200 can be temporarily stored in the slurry collection and storage device for easy maintenance. After the limestone absorption tower 200 is repaired, the limestone slurry can be sent back to the limestone absorption tower 200.

[0043] According to an embodiment of the present invention, referring to Figure 3 The limestone absorption tower 200 is connected to the limestone slurry replenishing device 600. As the operation time of the limestone absorption tower 200 increases, the absorption efficiency of the limestone slurry in the limestone absorption tower 200 decreases. At this time, it is necessary to replenish new limestone slurry in the limestone absorption tower 200. The new limestone slurry is stored in the limestone slurry replenishing device 600 and is pumped into the limestone absorption tower 200. In this way, the continuous operation and efficient desulfurization of the limestone absorption tower 200 can be guaranteed.

[0044] According to an embodiment of the present invention, referring to Figure 3 , the limestone absorption tower 200 is connected to the gypsum treatment device 700. After the slurry in the limestone absorption tower 200 has finished absorbing sulfur, the slurry absorbing sulfur is discharged from the limestone absorption tower 200 to the gypsum treatment device 700, and the slurry absorbing sulfur is concentrated or dehydrated. Further, the lower end of the limestone absorption tower 200 is connected to the oxygen supply device 800. A lot of slurry after the limestone absorption tower 200 absorbs sulfur forms sulfites. In order to facilitate the subsequent utilization and treatment of gypsum slag, the lower end of the limestone absorption tower 200 is connected to the oxygen supply device 800, and oxygen or air is continuously introduced into the slurry below the limestone absorption tower 200 to oxidize the sulfites into sulfates and then discharge them.

[0045] According to an embodiment of the present invention, referring to Figure 3The acid production tail gas treatment unit includes a hydrogen peroxide absorption tower 500, the lower end of the hydrogen peroxide absorption tower 500 is provided with an acid production tail gas inlet 510, and the upper end is provided with a purified tail gas outlet 520, and the purified tail gas outlet 520 is connected to the electric demisting device 100. Because the sulfur dioxide content in the acid production tail gas is generally low, under the premise of satisfying the control cost and reducing the side reaction, a hydrogen peroxide absorption tower 500 with high desulfurization efficiency is selected, and the acid production tail gas enters the hydrogen peroxide absorption tower 500 from the acid production tail gas inlet 510. After the sulfur dioxide in the acid production tail gas is absorbed in the hydrogen peroxide absorption tower 500, the purified tail gas is discharged from the purified tail gas outlet 520. Furthermore, a pipe trough type acid separation device (not shown) is provided in the hydrogen peroxide absorption tower 500, so as to improve the desulfurization efficiency of hydrogen peroxide; a foam catcher (not shown) is provided at the top of the hydrogen peroxide absorption tower 500, so as to reduce the foam in the gas.

[0046] According to an embodiment of the present invention, referring to Figure 3 A second sulfur dioxide monitoring component 530 is provided on the pipeline connecting the purified tail gas outlet 520 and the electric demisting device 100, and the hydrogen peroxide absorption tower 500 is connected to the hydrogen peroxide replenishing device 540. The sulfur dioxide content of the purified tail gas after absorption by the hydrogen peroxide absorption tower 500 can be detected by the second sulfur dioxide monitoring component 530. As the absorption time increases, the hydrogen peroxide in the hydrogen peroxide absorption tower 500 is consumed. According to the sulfur dioxide content detected by the second sulfur dioxide monitoring component 530, the hydrogen peroxide solution in the hydrogen peroxide replenishing device 540 is replenished to the hydrogen peroxide absorption tower 500 in time to ensure the continuous operation of the hydrogen peroxide absorption tower 500. Furthermore, after a period of absorption by the hydrogen peroxide absorption tower 500, a dilute acid solution is formed, which is returned to the acid production system (not shown) because of its low impurity content and very clean.

[0047] In another aspect of the present invention, the present invention proposes a method for purifying sulfur dioxide in flue gas using the above system. According to an embodiment of the present invention, the method comprises:

[0048] S100: Desulfurization of flue gas collected from the ring

[0049] In this step, the flue gas is passed from the flue gas inlet to the limestone absorption tower for desulfurization treatment, and the sulfur dioxide in the flue gas is absorbed by the limestone slurry to obtain desulfurized flue gas, which is then discharged from the desulfurized flue gas outlet.

[0050] S200: Detection of sulfur dioxide in desulfurized flue gas

[0051] In this step, the desulfurized flue gas obtained in S100 contains particulate matter. When the desulfurized flue gas passes through the first pipeline, the first sulfur dioxide detection component detects the sulfur dioxide content in the desulfurized flue gas.

[0052] S300: Purify the desulfurized flue gas based on the sulfur dioxide content in the desulfurized flue gas

[0053] In this step, the desulfurized flue gas is purified based on the sulfur dioxide content in the S200 desulfurized flue gas. If the sulfur dioxide content is less than 85 mg / Nm 3 In the security absorption tower, spray water is used to purify the desulfurized flue gas, thereby removing particulate matter in the desulfurized flue gas. If the sulfur dioxide content in the desulfurized flue gas is not less than 85mg / Nm 3 The desulfurized flue gas is purified by spraying hydrogen peroxide solution in the security absorption tower, which can not only remove the particulate matter in the flue gas, but also further remove the sulfur dioxide in the desulfurized flue gas. According to the different content of sulfur dioxide in the desulfurized flue gas, different solutions are used to treat the desulfurized flue gas. Under the premise of ensuring the removal of particulate matter and sulfur dioxide in the desulfurized flue gas, it can also save costs to the greatest extent.

[0054] S400: Desulfurization of acid production tail gas

[0055] In this step, the acid production tail gas is desulfurized. Since the sulfur dioxide content in the acid production tail gas is generally low, under the premise of controlling costs and reducing side reactions, a hydrogen peroxide absorption tower with high desulfurization efficiency is selected to absorb the sulfur dioxide in the acid production tail gas, thereby obtaining purified tail gas that meets emission standards.

[0056] S500: Electrostatic demisting of purified flue gas and purified exhaust gas

[0057] In this step, the purified flue gas obtained in S300 and the purified tail gas obtained in S400 are introduced into an electric demisting device for electric demisting, thereby effectively separating the droplets in the purified flue gas and the purified tail gas.

[0058] The present invention is described below with reference to specific embodiments. It should be noted that these embodiments are merely illustrative and do not limit the present invention in any way.

[0059] Example 1

[0060] (1) The current flue gas volume of our company's flue gas collection system is 400,000 Nm 3 / h, the sulfur dioxide content in the flue gas is 798mg / Nm 3 ~7980mg / Nm 3 ; Flue gas volume of acid production tail gas system 250000Nm 3 / h, the sulfur dioxide content in the acid production tail gas is 171mg / Nm 3 ~399mg / Nm 3 .

[0061] The flue gas from the ring collection is passed into the flue gas treatment unit of the present application for absorption, and the tail gas from the acid production is passed into the tail gas treatment unit of the present application for absorption. After the flue gas from the ring collection is absorbed by the limestone absorption tower of the flue gas treatment unit, if the sulfur dioxide content in the desulfurized flue gas is less than 85 mg / Nm 3 The safety absorption tower uses water as the spray liquid to spray the desulfurized flue gas, and then the flue gas is discharged from the safety absorption tower to the atmosphere; if the sulfur dioxide content in the desulfurized flue gas is not less than 85mg / Nm 3 The security absorption tower uses hydrogen peroxide solution as the spray liquid to spray the desulfurized flue gas. The sulfur dioxide in the desulfurized flue gas is further absorbed by hydrogen peroxide. The sulfur dioxide content in the purified flue gas after absorption is 3mg / Nm 3 ~10mg / Nm 3 The sulfur dioxide content in the purified tail gas obtained after the acid production tail gas absorption is 15mg / Nm 3 ~30mg / Nm 3 (The current standard control value is 100mg / Nm 3 ). It shows that the system of the present application can effectively absorb sulfur dioxide in smelting flue gas, and the sulfur dioxide in the discharged flue gas is significantly lower than the national standard control value.

[0062] (2) In 2020, our company adopted the sodium-alkali desulfurization process, consuming 9,550 tons of 32% sodium hydroxide solution annually, equivalent to 1,756 tons of sodium salt, resulting in a monthly average sodium salt content in the neutralized and recycled water in the entire plant area of ​​more than 3,000 mg / L. After adopting the system of the present application, the concentration of sodium ions was greatly reduced, specifically reducing the concentration of sodium ions to below 1,200 mg / L, greatly expanding the breadth and depth of the long-term use area of ​​recycled water, and creating favorable conditions for further improving the water balance of the entire plant area.

[0063] (3) Daily output 25m 3 About 20% of the dilute acid solution is returned to the acid making system, effectively improving the sulfur recovery rate.

[0064] (4) Taking our company as an example, if we use the sodium alkali desulfurization process, the annual consumption of liquid alkali is 9,550 tons, the liquid alkali is 1,500 yuan per ton, and the annual cost is 14.325 million yuan; if we use the system of this application, we need limestone powder at 160 yuan per ton each year, the annual consumption is about 7,300 tons, and the annual cost is about 1.168 million yuan; gypsum is sold at 50 yuan per ton, the annual output is 7,200 tons, and the annual income is about 360,000 yuan; 27.5% hydrogen peroxide is 1,000 yuan per ton, the annual consumption is about 1,800 tons, and the annual cost is about 1.8 million yuan. Therefore, the system of this application can save more than 10 million yuan in production costs each year.

[0065] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0066] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A flue gas desulfurization system, characterized in that: include: The ring-collected flue gas treatment unit comprises: A limestone absorption tower, wherein the lower end of the limestone absorption tower is provided with a ring-collecting flue gas inlet, and the upper end is provided with a desulfurized flue gas outlet; A security absorption tower, wherein a desulfurized flue gas inlet is provided at the lower end of the security absorption tower, and a purified flue gas outlet is provided at the upper end, wherein the desulfurized flue gas inlet and the desulfurized flue gas outlet are connected via a first pipeline, wherein a first sulfur dioxide detection component is provided on the first pipeline, and based on the display of the first sulfur dioxide detection component, the security absorption tower uses water or hydrogen peroxide as a spray liquid; An acid-making tail gas treatment unit, the acid-making tail gas treatment unit comprising a hydrogen peroxide absorption tower, the lower end of the hydrogen peroxide absorption tower is provided with an acid-making tail gas inlet, and the upper end is provided with a purified tail gas outlet; An electric demisting device, wherein the purified flue gas outlet and the purified tail gas outlet are connected to the electric demisting device.

2. The system according to claim 1, characterized in that Based on the first sulfur dioxide detection component showing that the sulfur dioxide content in the desulfurized flue gas is not less than 85 mg / Nm 3 , the security absorption tower uses hydrogen peroxide as the spraying liquid; Based on the first sulfur dioxide detection component showing that the sulfur dioxide content in the desulfurized flue gas is less than 85 mg / Nm 3 The security absorption tower uses water as the spraying liquid.

3. The system according to claim 1, characterized in that The annular smoke collection processing unit further includes a booster fan and a first annular smoke collection pipeline, wherein the first annular smoke collection pipeline is arranged upstream of the annular smoke collection inlet and connected to the first annular smoke collection inlet, and the booster fan is arranged on the first annular smoke collection pipeline.

4. The system according to claim 3, characterized in that The first flue gas collection pipeline includes a main pipeline, a first branch pipeline and a second branch pipeline. One end of the first branch pipeline and one end of the second branch pipeline are connected to one end of the main pipeline, and the other end of the first branch pipeline is connected to the first flue gas collection inlet. The booster fan is arranged on the main pipeline, the first branch pipeline is provided with a first valve, the other end of the second branch pipeline is connected to the first pipeline, and the second branch pipeline is provided with a second valve. A third valve is provided at the desulfurized flue gas outlet.

5. The system according to claim 1 or 2, characterized in that: The limestone absorption tower is connected to a limestone slurry replenishing device; Optionally, the limestone absorption tower is connected to a gypsum processing device; Optionally, the lower end of the limestone absorption tower is connected to an oxygen supply device.

6. The system according to claim 1 or 2, characterized in that: The hydrogen peroxide absorption tower is provided with a tube-trough type acid separation device; Optionally, a foam trap is provided at the top of the hydrogen peroxide absorption tower.

7. The system according to claim 1 or 2, characterized in that: A second sulfur dioxide monitoring component is provided on the pipeline connecting the purified tail gas outlet and the electric demisting device, and the hydrogen peroxide absorption tower is connected to a hydrogen peroxide replenishing device.

8. A method for purifying sulfur dioxide in flue gas using the system according to any one of claims 1 to 7, characterized in that: include: (1) desulfurizing the collected flue gas to obtain desulfurized flue gas; (2) detecting sulfur dioxide in the desulfurized flue gas; (3) purifying the desulfurized flue gas based on the sulfur dioxide content in the desulfurized flue gas to obtain purified flue gas; (4) desulfurizing the acid production tail gas to obtain purified tail gas; (5) The purified flue gas and the purified tail gas are subjected to electrostatic demisting to obtain emission gas that meets the standards.

9. The method according to claim 8, characterized in that: Step (3) specifically includes: the sulfur dioxide content in the desulfurized flue gas is less than 85 mg / Nm 3 , the desulfurized flue gas is purified by spraying water; the sulfur dioxide content in the desulfurized flue gas is not less than 85mg / Nm 3 The desulfurized flue gas is purified by spraying a hydrogen peroxide solution.

10. The method according to claim 8, characterized in that: The content of sulfur dioxide in the purified flue gas is less than 85 mg / Nm 3 ; Optionally, the content of sulfur dioxide in the purified tail gas is not more than 30 mg / Nm 3 .

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