A flue gas treatment system and method

Abstract

The application provides a flue gas treatment system and method. The system comprises a water washing and dust removing module including a water washing and dust removing unit and a dust removing acid liquid pool; a wet desulfurization module including a wet desulfurization unit and a desulfurization slurry pool; and a filter tank arranged between the dust removing acid liquid pool and the desulfurization slurry pool, wherein a limestone particle filter layer is arranged in the filter tank, and the filter tank is configured to be opened when the acid liquid in the dust removing acid liquid pool reaches a preset condition, so that the acid liquid in the dust removing acid liquid pool is filtered and neutralized by the filter layer of the filter tank and then enters the desulfurization slurry pool. Since dust removing and desulfurization are carried out separately, and the dust deposits in the acid liquid are removed by filtration, the quality of gypsum is ensured. Moreover, while the acid liquid is filtered by the limestone particle filter layer, the acid liquid can also react with the limestone particles of the filter layer to remove part of sulfur, so that the amount of limestone powder used in the wet desulfurization link can be saved, and the treatment cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of gas treatment technology, and in particular to a flue gas treatment system and method. Background Technology

[0002] Wet desulfurization is a commonly used process in flue gas treatment, among which limestone-gypsum wet desulfurization is widely adopted due to its maturity and reliability. However, limestone-gypsum wet desulfurization requires the use of finely ground limestone powder as the desulfurization absorbent to prepare the desulfurization absorbent slurry, increasing the difficulty of limestone pretreatment and raising overall costs. Furthermore, in existing technologies that integrate flue gas washing and dust removal with wet desulfurization, the presence of dust reduces the quality of the resulting gypsum. Therefore, existing flue gas treatment processes require improvement. Summary of the Invention

[0003] In view of the above problems, the present invention provides a flue gas treatment system and method that overcomes or at least partially solves the above problems.

[0004] One object of the present invention is to provide a flue gas treatment system and method that can guarantee the quality of the gypsum produced and save on the amount of limestone powder used.

[0005] A further object of the present invention is to improve the filtration and neutralization effect of acid solutions through a limestone particle filter layer.

[0006] In particular, according to one aspect of the present invention, a flue gas treatment system is provided, comprising:

[0007] The water-washing dust removal module includes:

[0008] A water-washing dust removal unit is configured to contact the input flue gas with a dust removal liquid to remove dust from the flue gas and absorb at least a portion of the water-soluble acidic gases in the flue gas to obtain an acid solution; and

[0009] A dust removal acid tank is configured to receive the acid solution generated by the water washing dust removal unit.

[0010] Wet desulfurization module, which includes:

[0011] The wet desulfurization unit is configured to contact the flue gas, after water washing and dust removal, with a desulfurization liquid containing limestone or lime to obtain a desulfurized slurry; and

[0012] A desulfurization slurry tank is configured to receive the desulfurized slurry produced by the wet desulfurization unit; and

[0013] A filter tank is disposed between the dust removal acid solution tank and the desulfurization slurry tank. The filter tank is provided with a limestone particle filter layer and is configured to open when the acid solution in the dust removal acid solution tank reaches a preset condition, so that the acid solution in the dust removal acid solution tank is simultaneously filtered and neutralized through the filter layer of the filter tank before entering the desulfurization slurry tank.

[0014] Optionally, the thickness of the limestone particle filter layer is 0.5 m to 5 m; and / or

[0015] The porosity of the limestone particle filter layer is 30% to 70%; and / or

[0016] The initial particle size of the limestone particles in the limestone particle filter layer is 0.5 cm to 5 cm.

[0017] Optionally, the limestone particle filter layer is horizontally arranged, and

[0018] The filter tank is also configured to allow the acid entering the filter tank to flow horizontally, obliquely downward, or vertically downward relative to the limestone particle filter layer.

[0019] Optionally, the filter tank includes:

[0020] A bubbling unit is located at the bottom of the limestone particle filter layer and is configured to introduce air into the limestone particle filter layer.

[0021] Optionally, the acid in the dust removal acid tank is circulated and used as the dust removal liquid until the preset conditions are met; and

[0022] The desulfurized slurry in the desulfurization slurry tank is filtered to remove precipitates in order to prepare gypsum, and then recycled for use as the desulfurization solution.

[0023] Optionally, the preset conditions include:

[0024] The dust content of the acid solution exceeds a first threshold; and / or

[0025] The pH value of the acid solution is lower than the second threshold.

[0026] Optionally, the flue gas treatment system further includes:

[0027] A sludge removal device configured to remove deposits accumulated on the filter layer; and / or

[0028] The backwashing device is configured to backwash the filter layer using the desulfurized slurry in the desulfurization slurry tank.

[0029] Optionally, the flue gas treatment system further includes:

[0030] The combustion device is configured to incinerate and render harmless the sediment obtained from cleaning or backwashing.

[0031] According to another aspect of the present invention, a flue gas treatment method is also provided, comprising:

[0032] The flue gas is brought into contact with the dust removal liquid for water washing and dust removal, so as to remove the dust in the flue gas and absorb at least part of the water-soluble acidic gas in the flue gas to obtain an acid solution.

[0033] The flue gas, after being washed and dust-removed by water, is contacted with a desulfurization liquid containing limestone or lime to obtain a desulfurized slurry; wherein...

[0034] When the acid solution reaches the preset conditions, the acid solution is filtered and neutralized simultaneously through a limestone particle filter layer, and the filtered and neutralized acid solution is combined with the desulfurized slurry.

[0035] Optionally, the flow velocity of the acid solution across the cross-section of the limestone particle filter layer is 0.01 m / s to 0.1 m / s; and / or

[0036] The contact time between the acid solution and the limestone particle filter layer is 10s to 100s.

[0037] Optionally, the limestone particle filter layer is horizontally arranged, and

[0038] The acid solution flows horizontally, obliquely downward, or vertically downward relative to the limestone particle filter layer.

[0039] Optionally, the flue gas treatment method further includes:

[0040] During the process of the acid solution passing through the limestone particle filter layer, air is introduced into the limestone particle filter layer to create bubbles.

[0041] Optionally, the acid solution is circulated and used as the dust removal liquid until the preset conditions are met; and

[0042] The desulfurized slurry is filtered to remove the precipitates in order to prepare gypsum, and then recycled as the desulfurization liquid.

[0043] The preset conditions include:

[0044] The dust content of the acid solution exceeds a first threshold; and / or

[0045] The pH value of the acid solution is lower than the second threshold.

[0046] Optionally, the flue gas treatment method further includes:

[0047] When the filter layer reaches the cleaning trigger condition, the filter layer is mechanically cleaned or backwashed using the desulfurized slurry; and

[0048] The sediments removed or obtained from backwashing are incinerated to render them harmless.

[0049] In the flue gas treatment system and method of the present invention, the acid solution obtained after water washing and dust removal of flue gas is simultaneously filtered and neutralized by passing through a limestone particle filter layer, and then combined with the desulfurized slurry to prepare gypsum. Because dust removal and desulfurization are performed separately, and dust deposits in the acid solution are removed by filtration, the quality of the obtained gypsum is ensured. Furthermore, while the acid solution is being filtered through the limestone particle filter layer, the acid solution (mainly sulfuric acid) can also undergo an acid-base neutralization reaction with the limestone particles in the filter layer. That is, some sulfur is removed by consuming the limestone particles in the filter layer, thereby saving the amount of limestone powder used in the wet desulfurization process and reducing treatment costs.

[0050] Furthermore, the large number of limestone particles in the filter layer also act as a stabilizer for the pH value of the entire desulfurization system, making the pH value of the slurry in the desulfurization process more stable.

[0051] Furthermore, by optimizing the structure of the limestone particle filter layer, the parameters of the limestone particles, and the flow pattern of the acid relative to the filter layer, sufficient contact time between the acid and the limestone particles is ensured, allowing them to fully interact and react, thereby improving the filtration and neutralization effect of the acid through the limestone particle filter layer.

[0052] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below.

[0053] The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0054] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0055] Figure 1 A schematic structural block diagram of a flue gas treatment system according to an embodiment of the present invention is shown;

[0056] Figure 2 A schematic structural block diagram of a flue gas treatment system according to another embodiment of the present invention is shown;

[0057] Figure 3 A schematic flowchart of a flue gas treatment method according to an embodiment of the present invention is shown. Detailed Implementation

[0058] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0059] To address the aforementioned technical problems, the present invention provides a flue gas treatment system.

[0060] Figure 1 A schematic structural block diagram of a flue gas treatment system 100 according to an embodiment of the present invention is shown. See also Figure 1 As shown, the flue gas treatment system 100 may include at least a water washing dust removal module 110, a wet desulfurization module 120, and a filter tank 130.

[0061] The water washing dust removal module 110 includes: a water washing dust removal unit 111, configured to bring the input flue gas into contact with the dust removal liquid to remove dust from the flue gas and absorb at least part of the water-soluble acidic gases in the flue gas to obtain acid liquid; and a dust removal acid liquid tank 112, configured to receive the acid liquid generated by the water washing dust removal unit 111.

[0062] The flue gas can be input from any flue gas source that generates flue gas, such as a cement kiln or a coal-fired boiler. Before the flue gas enters the water washing dust removal unit 111, it can undergo other treatments such as waste heat recovery, which are well known to those skilled in the art and will not be described in detail herein. In the water washing dust removal unit 111, the flue gas can be brought into contact with the dust removal liquid in various ways. For example, the dust removal liquid can be sprayed to make the dust removal liquid and flue gas come into countercurrent contact, or the flue gas can be passed into the dust removal liquid pool to bring the two into contact, etc. This invention does not limit these methods. The water washing dust removal unit 111 and the dust removal acid pool 112 can be installed separately or integrated into one unit. Especially when the flue gas is passed into the dust removal liquid pool to bring the two into contact, the water washing dust removal unit 111 and the dust removal acid pool 112 are actually an integrated device. The main component of the dust removal liquid is water. Those skilled in the art will understand that water can be used as the dust removal liquid in the initial stage of dust removal. Afterward, the acid in the dust removal acid tank 112 can be recycled as the dust removal liquid until the acid reaches the preset conditions and is no longer recycled. At this time, fresh dust removal liquid (such as water) is used to continue the water washing dust removal operation.

[0063] The wet desulfurization module 120 includes: a wet desulfurization unit 121, configured to contact the flue gas after water washing and dust removal with a desulfurization liquid containing limestone or lime to obtain a desulfurized slurry; and a desulfurization slurry tank 122, configured to receive the desulfurized slurry produced by the wet desulfurization unit 121. The flue gas after water washing and dust removal enters the wet desulfurization unit 121. In the wet desulfurization unit 121, any known method can be used to contact the flue gas with the desulfurization liquid for wet desulfurization, which should be known to those skilled in the art and will not be described further. Preferably, an oxidizing gas (such as oxygen) can also be introduced into the wet desulfurization unit 121. Sulfur dioxide in the flue gas reacts with calcium carbonate or lime in the desulfurization liquid and the oxidizing gas to generate calcium sulfate, which is present in the desulfurized slurry.

[0064] Furthermore, the desulfurized slurry in the desulfurization slurry tank 122 can be recycled as desulfurization liquid after filtering out the precipitate (calcium sulfate dihydrate) to prepare gypsum.

[0065] A filter tank 130 is disposed between the dust removal acid solution tank 112 and the desulfurization slurry tank 122. The filter tank 130 is provided with a limestone particle filter layer 131 and is configured to open the filter tank 130 when the acid solution in the dust removal acid solution tank 112 reaches a preset condition, so that the acid solution in the dust removal acid solution tank 112 is filtered and neutralized simultaneously through the filter layer 131 of the filter tank 130 before entering the desulfurization slurry tank 122.

[0066] As mentioned earlier, in the water-washing dust removal unit 111, at least some water-soluble acidic gases, such as some sulfur dioxide and sulfur trioxide, are absorbed by the dust removal liquid to generate acid. Since flue gas usually contains a certain amount of oxidizing gases, sulfur dioxide is absorbed under the action of these oxidizing gases to generate sulfuric acid. When the acid solution passes through the limestone particle filter layer 131, the limestone particle filter layer 131 not only intercepts dust and other deposits in the acid solution, but the limestone particles in the filter layer 131 can also undergo an acid-base neutralization reaction with the sulfuric acid in the acid solution to generate calcium sulfate. After filtration and neutralization by the limestone particle filter layer 131, the acid solution enters the desulfurization slurry tank 122 and is combined with the desulfurized slurry for the preparation of gypsum and recycling as desulfurization liquid.

[0067] In this embodiment, since dust removal and desulfurization are carried out separately, and dust deposits in the acid solution are removed by filtration, the quality of the gypsum produced is guaranteed. Furthermore, while the acid solution is filtered through the limestone particle filter layer 131, the acid solution (mainly sulfuric acid) can also undergo an acid-base neutralization reaction with the limestone particles in the filter layer 131. That is, some sulfur is removed by consuming the limestone particles in the filter layer 131, thereby saving the amount of limestone powder used in the wet desulfurization process and reducing processing costs.

[0068] Furthermore, the large number of limestone particles in the filter layer 131 also serve as a stabilizer for the pH value of the entire desulfurization system, making the pH value of the slurry in the desulfurization process more stable.

[0069] The filter tank 130 opens when the acid in the dust removal acid tank 112 reaches a preset condition. Optionally, the preset condition may include: the dust content of the acid exceeds a first threshold; and / or the pH value of the acid is lower than a second threshold. When the dust content of the acid exceeds the first threshold and / or the pH value of the acid is lower than the second threshold, it indicates that the acid is no longer suitable for recycling. At this time, the filter tank 130 is opened to filter and neutralize the acid. The first and second thresholds can be set according to actual application requirements. Optionally, the first threshold can be set between 25% and 35% of the weight dust content of the acid, for example, 30%. The second threshold can be set between 3.0 and 4.0, for example, 3.5.

[0070] In some optional embodiments, the thickness of the limestone particle filter layer 131 can be from 0.5 m to 5 m, for example, 1 m, 1.5 m, 2 m, 2.5 m, 3 m, 3.5 m, 4 m, or 4.5 m. In practical applications, an appropriate acid flow rate can be used to ensure the contact time between the acid and the limestone particles. Optionally, the flow rate of the acid across the cross-section of the limestone particle filter layer 131 can be from 0.01 m / s to 0.1 m / s, for example, 0.02, 0.04, 0.05, 0.07, or 0.09 m / s; and / or, the contact time between the acid and the limestone particle filter layer 131 can be from 10 s to 100 s, for example, 20, 30, 40, 50, 60, 70, 80, or 90 s.

[0071] In some alternative embodiments, the porosity of the limestone particle filter layer 131 can be from 30% to 70%, for example, 40%, 45%, 50%, 55%, 60%, 65%. The appropriate porosity design ensures both the strength of the limestone particle filter layer 131 and reduces the resistance of acid solution passing through it, thereby improving filtration and neutralization efficiency.

[0072] In some optional embodiments, the initial particle size of the limestone particles (i.e., the original particle size of the limestone particles before they react with the acid) can be from 0.5 cm to 5 cm, for example, 1 cm, 2 cm, 2.5 cm, 3 cm, 4 cm, or 4.5 cm. An appropriate limestone particle size ensures sufficient contact surface area between the limestone particles and the acid, guaranteeing a full reaction between the limestone particles and the acid, thereby improving filtration and neutralization efficiency.

[0073] To achieve the desired acid throughput efficiency and filtration neutralization effect, the flow pattern of the acid relative to the limestone particle filter layer 131 can be optimized. Generally, the limestone particle filter layer 131 can be horizontally positioned to simplify its support and fixing structure.

[0074] In some embodiments, the filter tank 130 can also be configured to allow the acid entering the filter tank 130 to flow horizontally relative to the limestone particle filter layer 131. That is, the acid flows parallel to the horizontal surface of the limestone particle filter layer 131. During the flow, under the influence of gravity, the acid gradually penetrates downward through the limestone particle filter layer 131 to contact and react with the limestone particles, thereby achieving filtration and neutralization. This flow pattern can maximize the contact time between the acid and the limestone particle filter layer 131 while appropriately sacrificing the flow rate of the acid.

[0075] In other embodiments, the filter tank 130 may also be configured such that the acid entering the filter tank 130 flows obliquely downward relative to the limestone particle filter layer 131. This can provide a driving force for the acid to pass through the cross-section of the filter layer 131, thereby appropriately improving the efficiency of the acid passing through the limestone particle filter layer 131.

[0076] In other embodiments, the filter tank 130 may also be configured such that the acid entering the filter tank 130 flows vertically downwards relative to the limestone particle filter layer 131. This configuration maximizes the efficiency of the acid passing through the limestone particle filter layer 131.

[0077] By optimizing the structure of the limestone particle filter layer 131, the parameters of the limestone particles, and the flow pattern of the acid relative to the filter layer 131, sufficient contact time between the acid and the limestone particles is ensured, allowing them to fully interact and react, thereby improving the filtration and neutralization effect of the acid through the limestone particle filter layer 131.

[0078] In some embodiments, see Figure 2 As shown, the filter tank 130 may include a bubbling unit 132. The bubbling unit 132 is disposed at the bottom of the limestone particle filter layer 131 and configured to introduce air into the limestone particle filter layer 131. By introducing air through the bubbling unit 132 at the bottom of the filter layer 131, the filter layer 131 can be cleaned to prevent clogging, while simultaneously oxidizing sulfite ions in the flowing acid solution to sulfate ions. Furthermore, this method of aeration and bubbling, because the bubbles are dispersed by the filter layer 131 and have a long residence time, makes the oxidation process more efficient than traditional slurry tank bubbling, and also ensures a more complete neutralization reaction between sulfate ions and limestone.

[0079] In some embodiments, see continue to see Figure 2As shown, the flue gas treatment system 100 may further include a sludge removal device 140 and / or a backwashing device 150. The sludge removal device 140 is configured to clean the deposits accumulated on the filter layer 131, for example, by mechanical means. The backwashing device 150 is configured to backwash the filter layer 131 using the desulfurized slurry from the desulfurization slurry tank 122. In practical applications, it is possible to monitor whether the filter layer 131 meets the cleaning trigger condition. When the filter layer 131 meets the cleaning trigger condition, the sludge removal device 140 and / or the backwashing device 150 are activated to clean the filter layer 131. The cleaning trigger condition can be set according to actual application requirements. For example, it can be set as follows: the change in the flow rate of the acid solution before and after passing through the filter layer 131 reaches a preset change threshold; or, a cleaning activation command is received; or, the thickness of the deposits on the filter layer 131 reaches a preset thickness threshold, etc. By promptly cleaning the deposits on the filter layer 131, the normal function of the filter layer 131 is ensured, and clogging is prevented.

[0080] In some cases, the aforementioned sediments can be combustible. Therefore, in some further embodiments, see [reference needed]. Figure 2 As shown, the flue gas treatment system 100 may also include a combustion device 160 configured to incinerate and render harmless the sediment obtained from cleaning or backwashing.

[0081] Based on the same technical concept, the present invention also provides a flue gas treatment method. This flue gas treatment method can be applied to the aforementioned flue gas treatment system 100. Figure 3 A schematic flow chart of a flue gas treatment method according to an embodiment of the present invention is shown. See also Figure 3 As shown, the flue gas treatment method may include at least the following steps S302 to S306.

[0082] Step S302: The flue gas is brought into contact with the dust removal liquid for water washing and dust removal, so as to remove dust in the flue gas and absorb at least part of the water-soluble acidic gas in the flue gas to obtain acid liquid.

[0083] Step S304 involves contacting the flue gas after water washing and dust removal with a desulfurization liquid containing limestone or lime to obtain a desulfurized slurry.

[0084] In step S306, when the acid solution reaches the preset conditions, the acid solution is filtered and neutralized simultaneously through the limestone particle filter layer 131, and the filtered and neutralized acid solution is combined with the desulfurized slurry.

[0085] In step S302, the acid solution can be recycled as a dust removal liquid until the preset conditions are met.

[0086] In step S304, the desulfurized slurry can be recycled as desulfurization liquid after filtering out the precipitates to prepare gypsum.

[0087] In step S306, the preset conditions may include: the dust content of the acid solution exceeds a first threshold; and / or the pH value of the acid solution is lower than a second threshold.

[0088] In some embodiments, the flow rate of the acid solution across the cross-section of the limestone particle filter layer 131 can be from 0.01 m / s to 0.1 m / s; and / or, the contact time between the acid solution and the limestone particle filter layer 131 can be from 10 s to 100 s, so as to ensure sufficient reaction between the limestone particles and the acid solution, thereby improving the filtration and neutralization effect.

[0089] In some embodiments, the limestone particle filter layer 131 may be horizontally arranged. To obtain the desired acid throughput efficiency and filtration neutralization effect, the flow mode of the acid relative to the limestone particle filter layer 131 may be selected from any of the following.

[0090] The first method involves the acid flowing horizontally relative to the limestone particle filter layer 131. That is, the acid flows parallel to the horizontal surface of the limestone particle filter layer 131. During this flow, under the influence of gravity, the acid gradually penetrates downwards through the limestone particle filter layer 131 to react with the limestone particles, thereby achieving filtration and neutralization. This flow method maximizes the contact time between the acid and the limestone particle filter layer 131 while appropriately sacrificing the flow rate of the acid.

[0091] The second method involves the acid flowing obliquely downwards relative to the limestone particle filter layer 131. This method provides a driving force for the acid to pass through the cross-section of the filter layer 131, thereby appropriately improving the efficiency of the acid passing through the limestone particle filter layer 131.

[0092] The third method involves the acid flowing vertically downwards relative to the limestone particle filter layer 131. This method maximizes the efficiency of the acid passing through the limestone particle filter layer 131.

[0093] In some embodiments, the flue gas treatment method may further include the following steps:

[0094] Air is introduced into the limestone particle filter layer 131 to bubble the acid solution as it passes through the filter layer 131.

[0095] By introducing air into the filter layer 131 to create bubbles, the filter layer 131 can be cleaned to prevent clogging, while the sulfite ions in the flowing acid solution are oxidized to sulfate ions. Furthermore, this method of aeration and bubbling, because the bubbles are dispersed by the filter layer 131 and have a longer residence time, makes the oxidation process more efficient than traditional slurry tank bubbling, and also ensures a more complete neutralization reaction between sulfate ions and limestone.

[0096] In some embodiments, the flue gas treatment method may further include the following steps:

[0097] When the filter layer 131 reaches the cleaning trigger condition, the filter layer 131 is mechanically cleaned or backwashed using the desulfurized slurry.

[0098] The cleanup trigger conditions are as described above and will not be repeated.

[0099] In some further embodiments, the flue gas treatment method may further include the following steps:

[0100] The sediments removed or obtained from backwashing are incinerated to render them harmless.

[0101] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0102] Example 1

[0103] In this embodiment, the following is adopted: Figure 2 The flue gas treatment system 100 shown performs flue gas dust removal and desulfurization. The specific process conditions are as follows:

[0104] The limestone particle filter layer 131 is horizontally arranged with a thickness of 0.8 μm and a porosity of 50%. The initial particle size of the limestone particles is 1 cm. The initial sulfur content of the flue gas entering the water washing dust removal module 110 is 500 mg / m³. 3 Dust content is 200mg / m³ 3 The conditions for opening filter tank 130 are set as follows: the first threshold is a dust content of 30%, and the second threshold is a pH value of 3.5. During the treatment process, the acid solution flows downwards through a 0.8m thick layer of filter layer 131. The flow velocity of the acid solution through filter layer 131 is 0.05 m / s, and the contact time between the acid solution and filter layer 131 is 16 seconds. The limestone powder dosage in wet desulfurization unit 121 (i.e., desulfurization section) is 500 mg / m³. 3 The sulfur content of the treated flue gas is 35 mg / m³. 3 Dust content 50mg / m³ 3 .

[0105] Comparative Example

[0106] Except for the absence of a filter tank 130 and the different amount of limestone powder used in the desulfurization section, the other conditions are the same as in Example 1.

[0107] In the comparative example, the limestone powder dosage in the desulfurization section was 780 mg / m³. 3 .

[0108] Based on the limestone powder usage in Example 1 and the comparative example, the limestone powder saving rate was (780-500) / 780 = 36%.

[0109] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0110] Therefore, those skilled in the art should recognize that although numerous exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications conforming to the principles of the present invention can be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Thus, the scope of the present invention should be understood and construed as covering all such other variations or modifications.

Claims

1. A flue gas treatment system, characterized in that, include: The water-washing dust removal module includes: A water-washing dust removal unit is configured to contact the input flue gas with a dust removal liquid to remove dust from the flue gas and absorb at least a portion of the water-soluble acidic gases in the flue gas to obtain an acid solution; and The dust removal acid tank is configured to receive the acid generated by the water washing dust removal unit. The dust removal acid tank and the water washing dust removal unit are integrated into a dust removal liquid tank. The acid is circulated and used as the dust removal liquid until a preset condition is met. Wet desulfurization module, which includes: The wet desulfurization unit is configured to contact the flue gas, after water washing and dust removal, with a desulfurization liquid containing limestone or lime to obtain a desulfurized slurry; and A desulfurization slurry tank is configured to receive the desulfurized slurry produced by the wet desulfurization unit; and A filter tank is disposed between the dust removal acid tank and the desulfurization slurry tank. The filter tank is provided with a limestone particle filter layer and is configured to open the filter tank when the acid reaches the preset conditions, so that the acid is filtered and neutralized simultaneously through the filter layer of the filter tank before entering the desulfurization slurry tank. The limestone particle filter layer is horizontally arranged, and the filter tank includes a bubbling unit disposed at the bottom of the limestone particle filter layer and configured to introduce air into the limestone particle filter layer for bubbling.

2. The flue gas treatment system according to claim 1, characterized in that, The thickness of the limestone particle filter layer is 0.5 m to 5 m; and / or The porosity of the limestone particle filter layer is 30% to 70%; and / or The initial particle size of the limestone particles in the limestone particle filter layer is 0.5 cm to 5 cm.

3. The flue gas treatment system according to claim 1, characterized in that, The filter tank is also configured to allow the acid entering the filter tank to flow horizontally, obliquely downward, or vertically downward relative to the limestone particle filter layer.

4. The flue gas treatment system according to claim 1, characterized in that, The desulfurized slurry in the desulfurization slurry tank is filtered to remove precipitates in order to prepare gypsum, and then recycled for use as the desulfurization solution.

5. The flue gas treatment system according to claim 1, characterized in that, The preset conditions include: The dust content of the acid solution exceeds a first threshold; and / or The pH value of the acid solution is lower than the second threshold.

6. The flue gas treatment system according to claim 1, characterized in that, Also includes: A dredging device is configured to clean the sediment accumulated on the filter layer; and / or The backwashing device is configured to backwash the filter layer using the desulfurized slurry in the desulfurization slurry tank.

7. The flue gas treatment system according to claim 6, characterized in that, Also includes: The combustion device is configured to incinerate and render harmless the sediment obtained from cleaning or backwashing.

8. A method for treating flue gas, comprising: The flue gas is brought into contact with the dust removal liquid for water washing and dust removal, so as to remove the dust in the flue gas and absorb at least part of the water-soluble acidic gas in the flue gas to obtain an acid solution. The dust removal liquid and the acid solution are the same liquid in the integrated dust removal liquid pool. The acid solution is recycled as the dust removal liquid until the preset conditions are met. The flue gas, after being washed and dust-removed by water, is contacted with a desulfurization liquid containing limestone or lime to obtain a desulfurized slurry; characterized in that, When the acid solution reaches the preset conditions, the acid solution is simultaneously filtered and neutralized through a limestone particle filter layer, and the filtered and neutralized acid solution is combined with the desulfurized slurry. The limestone particle filter layer is horizontally arranged, and air is introduced into the limestone particle filter layer to bubble it as the acid solution passes through it.

9. The flue gas treatment method according to claim 8, characterized in that, The flow velocity of the acid solution through the cross-section of the limestone particle filter layer is 0.01 m / s to 0.1 m / s; and / or The contact time between the acid solution and the limestone particle filter layer is 10 s to 100 s.

10. The flue gas treatment method according to claim 8, characterized in that, The acid solution flows horizontally, obliquely downward, or vertically downward relative to the limestone particle filter layer.

11. The flue gas treatment method according to claim 8, characterized in that, The desulfurized slurry is filtered to remove precipitates in order to prepare gypsum, and then recycled as the desulfurization liquid. The preset conditions include: The dust content of the acid solution exceeds a first threshold; and / or The pH value of the acid solution is lower than the second threshold.

12. The flue gas treatment method according to claim 8, characterized in that, Also includes: When the filter layer reaches the cleaning trigger condition, the filter layer is mechanically cleaned or backwashed using the desulfurized slurry. as well as The sediments removed or obtained from backwashing are incinerated to render them harmless.

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