Wet limestone / lime-gypsum method two-stage circulating desulfurization device
By setting up a two-stage circulating desulfurization zone and controlling the pH value in a wet limestone/lime-gypsum desulfurization unit, the problem of existing units being unable to simultaneously oxidize and absorb SO2 was solved, thus improving desulfurization efficiency and gypsum crystallization effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- YINGKOU ENVIRONMENT ENG DEV
- Filing Date
- 2025-05-07
- Publication Date
- 2026-05-01
AI Technical Summary
Existing wet limestone/lime-gypsum desulfurization devices are difficult to form a relatively independent dual-zone circulating desulfurization system, and cannot simultaneously and effectively oxidize and absorb SO2 in flue gas.
A wet limestone/lime-gypsum method two-stage circulating desulfurization device is designed. By setting a liquid collection tray in the desulfurization tower, it is divided into a lower circulation desulfurization zone and an upper circulation desulfurization zone. The pH value of each zone is controlled to be 4.0-5.0 and 5.5-6.0 respectively. Combined with the flue gas dispersion section, slurry spray layer and connecting pipe, the flue gas can be treated in zones.
It achieves effective oxidation and absorption of flue gas under different pH conditions, improves the oxidation reaction rate and solubility of SO2, enhances the desulfurization effect, reduces the generation of by-products, and promotes gypsum crystallization.
Smart Images
Figure CN224180632U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of industrial environmental protection technology, and in particular to a wet limestone / lime-gypsum method dual-stage circulating desulfurization device. Background Technology
[0002] With the continuous development of my country's industry, energy consumption is also increasing, leading to a rapid rise in sulfur dioxide emissions. Without effective control measures, the nature of air pollution in my country will fundamentally change, resulting in a series of urban and regional environmental problems that threaten human health and the ecological environment. my country is a major coal-producing country, and currently, centralized heating sources are still mainly coal-fired boiler rooms and coal-fired power plants. The combustion products contain high levels of sulfur dioxide, necessitating effective desulfurization measures. The wet limestone / lime-gypsum process, with its mature technology and high desulfurization efficiency, has become the mainstream desulfurization process in thermal power plants, metallurgy, and chemical industries.
[0003] However, existing desulfurization devices using the wet limestone / lime-gypsum method typically form a desulfurization zone within a single desulfurization tower, making it difficult to form a relatively independent dual-zone circulating desulfurization system. Furthermore, since the pH values of the slurry required for absorbing and oxidizing acidic gases such as SO2 in flue gas are different, it is difficult to achieve absorption and oxidation treatment in a conventional single desulfurization zone. Utility Model Content
[0004] In view of this, the purpose of this utility model is to propose a wet limestone / lime-gypsum method dual-stage circulating desulfurization device to solve the problem that existing desulfurization devices cannot be divided into dual-zone desulfurization systems, that is, it is difficult to oxidize and absorb SO2 in flue gas at the same time.
[0005] To achieve the above objectives, this utility model provides a wet limestone / lime-gypsum dual-stage circulating desulfurization device, including a desulfurization tower, with a flue gas inlet at the bottom of the desulfurization tower and a flue gas outlet at the top of the desulfurization tower, and further comprising:
[0006] A liquid collection tray is installed inside the desulfurization tower to divide the desulfurization tower into a lower circulation desulfurization zone and an upper circulation desulfurization zone. The pH value in the lower circulation desulfurization zone is 4.0 to 5.0, and the pH value in the upper circulation desulfurization zone is 5.5 to 6.0. A lower slurry spray layer is provided in the lower circulation desulfurization zone, and an upper slurry spray layer is provided in the upper circulation desulfurization zone.
[0007] The flue gas dispersion section is located in the lower circulation desulfurization zone and above the flue gas inlet, so that the flue gas dispersion section can disperse and slow down the flow of the flue gas entering the lower circulation desulfurization zone.
[0008] A connecting pipe is installed on the desulfurization tower to connect the lower circulation desulfurization zone and the upper circulation desulfurization zone, so that the flue gas after desulfurization in the lower circulation desulfurization zone can enter the upper circulation desulfurization zone for further desulfurization through the connecting pipe.
[0009] Preferably, it also includes a slurry pool for providing slurry to the lower slurry spray layer and a slurry tank for providing slurry to the upper slurry spray layer, wherein the slurry pool is located at the bottom of the desulfurization tower and is in communication with the desulfurization tower.
[0010] The slurry tank is located on the side of the desulfurization tower, and a connecting pipe is connected to the top of the slurry tank, extending into the upper circulation desulfurization zone.
[0011] Preferably, both the lower slurry spray layer and the upper slurry spray layer are composed of spray pipes and spray heads, and the slurry pool and slurry tank can supply slurry to the spray pipes through an external water pump.
[0012] Preferably, the flue gas dispersion section is an inverted conical filter screen, and the inverted conical filter screen is fixed in the lower circulation desulfurization zone. A slurry equalization mechanism is provided between the inverted conical filter screen and the lower slurry spray layer. The slurry equalization mechanism is used to evenly distribute the slurry sprayed by the lower slurry spray layer to increase the contact range between the flue gas and the slurry.
[0013] Preferably, the slurry distribution mechanism includes a drain plate, on which an annular sleeve is fixedly fitted. The annular sleeve is fixedly connected to the lower circulation desulfurization zone, and the interior of the annular sleeve is inclined.
[0014] Preferably, a wire mesh demister is provided in the upper circulation desulfurization zone, and the wire mesh demister is located between the flue gas outlet and the slurry spray layer.
[0015] The beneficial effects of this utility model are as follows:
[0016] 1. By controlling the pH value of the lower circulation desulfurization zone between 4.0 and 5.0, the lower circulation desulfurization zone is in the oxidation zone at a low pH value. In the oxidation zone, the oxidation of sulfite is accelerated. The low pH (acidic environment) also promotes oxygen dissolution, increases the oxidation reaction rate, inhibits the redissolution of CaSO3, reduces the generation of by-products, and promotes the crystallization of gypsum (CaSO4·2H2O).
[0017] Second, by controlling the pH value of the upper circulation desulfurization zone between 5.5 and 6.0, the upper circulation desulfurization zone becomes an absorption zone at a higher pH value (weakly acidic). The absorption zone (pH≈5.5) promotes the dissolution and neutralization of sulfur dioxide, increases the sulfur dioxide dissolution rate. Sulfur dioxide dissolves in water to form sulfurous acid, which dissociates into hydrogen ions and sulfite ions. The higher pH (weakly acidic) reduces the concentration of hydrogen ions, driving the reaction to proceed in the reverse direction to form sulfite ions, thereby enhancing the absorption capacity of sulfur dioxide.
[0018] Third, by setting up a flue gas dispersion section above the flue gas inlet, and the flue gas dispersion section is an inverted conical filter screen, the cross-sectional area of the channel gradually increases when the flue gas passes through the inverted conical filter screen. According to the continuity equation (Q=A·v), the flow velocity decreases, the dynamic pressure is converted into static pressure, the flow velocity slows down, the turbulence decreases, and the conical structure forms a gradually expanding structure to form a gentle pressure gradient, which is conducive to the stable deposition of particulate matter, increases the contact range between the slurry and the flue gas, and facilitates full contact between the sprayed slurry and the flue gas, thereby improving the oxidation effect in the lower circulation desulfurization zone. Attached Figure Description
[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0020] Figure 1 This is a schematic diagram of the structure of an embodiment of the present utility model;
[0021] Figure 2 This is an embodiment of the present utility model. Figure 1 A partial sectional view of the structure;
[0022] Figure 3 This is an embodiment of the present utility model. Figure 2 A schematic diagram of the structure of the flue gas dispersion section and the slurry distribution mechanism.
[0023] In the diagram: 1. Desulfurization tower; 2. Liquid collection tray; 3. Lower circulation desulfurization zone; 4. Upper circulation desulfurization zone; 5. Connecting pipe; 6. Slurry pool; 7. Slurry tank; 8. Slurry distribution mechanism; 8-1. Leakage tray; 8-2. Annular sleeve; 9. Flue gas dispersion section; 10. Wire mesh demister. Detailed Implementation
[0024] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings.
[0025] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this utility model should have the ordinary meaning understood by one of ordinary skill in the art to which this utility model pertains. The terms "first," "second," and similar terms used in this utility model do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are only used to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.
[0026] like Figure 1 , Figure 2 , Figure 3 As shown, a wet limestone / lime-gypsum dual-stage circulating desulfurization device includes a desulfurization tower 1, with a flue gas inlet at the bottom of the desulfurization tower 1 and a flue gas outlet at the top of the desulfurization tower 1, and further includes:
[0027] Liquid collection tray 2 is installed inside the desulfurization tower 1 to divide the desulfurization tower 1 into a lower circulation desulfurization zone 3 and an upper circulation desulfurization zone 4. The pH value in the lower circulation desulfurization zone 3 is 4.0 to 5.0, and the pH value in the upper circulation desulfurization zone 4 is 5.5 to 6.0. A lower slurry spray layer is provided in the lower circulation desulfurization zone 3, and an upper slurry spray layer is provided in the upper circulation desulfurization zone 4.
[0028] The flue gas dispersion section 9 is located in the lower circulation desulfurization zone 3 and above the flue gas inlet, so that the flue gas dispersion section 9 can disperse and slow down the flow of the flue gas entering the lower circulation desulfurization zone 3.
[0029] Connecting pipe 5 is installed on desulfurization tower 1 to connect the lower circulation desulfurization zone 3 and the upper circulation desulfurization zone 4, so that the flue gas after desulfurization in the lower circulation desulfurization zone 3 can enter the upper circulation desulfurization zone 4 for desulfurization again through connecting pipe 5.
[0030] By controlling the pH value of the lower circulation desulfurization zone 3 at 4.0-5.0, the lower circulation desulfurization zone 3 becomes an oxidation zone, where oxidation and crystallization occur preferentially.
[0031] The process flow in the oxidation zone is as follows:
[0032] I. Accelerating the oxidation of sulfites
[0033] In the oxidation zone, It needs to be oxidized to
[0034]
[0035] In a low pH (acidic environment):
[0036] Promotes O2 dissolution and increases the oxidation reaction rate;
[0037] It inhibits the redissolution of CaSO3 and reduces the formation of byproducts.
[0038] II. Promotes gypsum (CaSO4·2H2O) crystallization
[0039] With Ca 2+ Combined with gypsum production;
[0040] This allows oxygen to dissolve even in low pH (acidic environment), increasing the oxidation reaction rate, inhibiting the redissolution of CaSO3, reducing the formation of byproducts, and promoting the crystallization of gypsum (CaSO4·2H2O).
[0041] By controlling the pH value of the upper circulation desulfurization zone 4 at 5.5-6.0, the upper circulation desulfurization zone 4 becomes an absorption zone. The absorption zone (pH≈5.5) promotes the efficient absorption and neutralization of SO2.
[0042] The process flow in the absorption region is as follows:
[0043] I. Enhance SO2 solubility
[0044] SO2 dissolves in water to form sulfurous acid (H2SO3), and its dissociation reaction is as follows:
[0045]
[0046] A higher pH (weakly acidic) can reduce H+. + Concentration drives the reaction toward production. This direction significantly improves SO2 dissolution efficiency.
[0047] II. Optimizing Limestone Dissolution
[0048] Limestone (CaCO3) and H in the slurry of the absorption zone + The reaction releases Ca 2+
[0049] CaCO3 + 2H+ + →Ca 2+ +CO2↑+H2O
[0050] When pH≈5.5, H + The concentration is kept constant, which can maintain the continuous dissolution of CaCO3 while avoiding excessive dissolution that could lead to increased slurry viscosity or equipment corrosion.
[0051] In a preferred embodiment of the present invention, it further includes a slurry pool 6 for providing slurry to the lower slurry spray layer and a slurry tank 7 for providing slurry to the upper slurry spray layer. The slurry pool 6 is provided with a pipe for introducing air into the slurry. The slurry pool 6 is located at the bottom of the desulfurization tower 1 and is interconnected with the desulfurization tower 1.
[0052] The slurry tank 7 is located on the side of the desulfurization tower 1, and the top of the slurry tank 7 is connected to a connecting pipe, which extends into the upper circulation desulfurization zone 4.
[0053] Both the lower and upper slurry spraying layers are composed of spray pipes and spray heads. The slurry pool 6 and slurry tank 7 can supply slurry to the spray pipes through an external water pump (not shown in the figure).
[0054] The water pump draws slurry from the slurry pool 6 or slurry tank 7, and sprays the slurry through the lower slurry spray layer or the upper slurry spray layer into the lower slurry circulation zone 3 or the upper slurry circulation zone 4, respectively, so as to facilitate contact and reaction with the flue gas in each zone.
[0055] In another preferred embodiment of this utility model, the flue gas dispersion section 9 is an inverted conical filter screen, and the inverted conical filter screen is fixed in the lower circulating desulfurization zone 3. A slurry distribution mechanism 8 is provided between the inverted conical filter screen and the lower slurry spraying layer. The slurry distribution mechanism 8 is used to evenly distribute the slurry sprayed by the lower slurry spraying layer to increase the contact range between the flue gas and the slurry.
[0056] As the flue gas passes through the inverted conical filter, the cross-sectional area of the channel gradually increases. According to the continuity equation (Q=A·v), the flow velocity decreases, the dynamic pressure is converted into static pressure, the flow velocity slows down, and the turbulence is reduced. Furthermore, the conical structure forms a gradually expanding structure, creating a gentle pressure gradient, which is conducive to the stable deposition of particulate matter. This increases the contact range between the slurry and the flue gas, facilitating full contact between the sprayed slurry and the flue gas, and improving the oxidation effect in the lower circulation desulfurization zone.
[0057] In another preferred embodiment of the present invention, the slurry distribution mechanism 8 includes a slurry plate 8-1, on which an annular sleeve 8-2 is fixedly sleeved. The annular sleeve 8-2 is fixedly connected to the lower circulating desulfurization zone 3, and the interior of the annular sleeve 8-2 is inclined. Through the inclined arrangement of the inner wall of the annular sleeve 8-2, the slurry adhering to the inner wall of the desulfurization tower 1 can flow into the annular sleeve 8-2, and then fall back down through the slurry plate 8-1 to contact the flue gas. The slurry plate 8-1 also plays the role of dispersing the slurry sprayed from the lower slurry spraying layer.
[0058] It should be noted that a wire mesh demister 10 is installed in the upper circulation desulfurization zone 4. The wire mesh demister 10 is located between the flue gas outlet and the slurry spray layer. The wire mesh demister 10 can filter out water mist in the flue gas, making it easier to discharge dry flue gas.
[0059] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the present invention is limited to these examples; within the framework of the present invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in the details for the sake of brevity.
[0060] The embodiments of this utility model are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.
Claims
1. A wet limestone / lime-gypsum dual-stage circulating desulfurization device, comprising a desulfurization tower (1), wherein a flue gas inlet is provided at the bottom of the desulfurization tower (1) and a flue gas outlet is provided at the top of the desulfurization tower (1), characterized in that, Also includes: Liquid collection tray (2) is installed inside the desulfurization tower (1) to divide the desulfurization tower (1) into a lower circulation desulfurization zone (3) and an upper circulation desulfurization zone (4). The pH value in the lower circulation desulfurization zone (3) is 4.0 to 5.0, and the pH value in the upper circulation desulfurization zone (4) is 5.5 to 6.
0. A lower slurry spray layer is provided in the lower circulation desulfurization zone (3), and an upper slurry spray layer is provided in the upper circulation desulfurization zone (4). The flue gas dispersion section (9) is located in the lower circulation desulfurization zone (3) and above the flue gas inlet, so that the flue gas dispersion section (9) can disperse and slow down the flue gas entering the lower circulation desulfurization zone (3). A connecting pipe (5) is installed on the desulfurization tower (1) to connect the lower circulation desulfurization zone (3) and the upper circulation desulfurization zone (4) to each other, so that the flue gas after desulfurization in the lower circulation desulfurization zone (3) can enter the upper circulation desulfurization zone (4) for desulfurization again through the connecting pipe (5).
2. The wet limestone / lime-gypsum dual-stage circulating desulfurization device according to claim 1, characterized in that, It also includes a slurry pool (6) for providing slurry to the lower slurry spray layer and a slurry tank (7) for providing slurry to the upper slurry spray layer. The slurry pool (6) is located at the bottom of the desulfurization tower (1) and is in communication with the desulfurization tower (1). The slurry tank (7) is located on the side of the desulfurization tower (1), and the top of the slurry tank (7) is connected to a connecting pipe, which extends into the upper circulation desulfurization zone (4).
3. The wet limestone / lime-gypsum dual-stage circulating desulfurization device according to claim 2, characterized in that, The lower slurry spray layer and the upper slurry spray layer are both composed of spray pipes and spray heads. The slurry pool (6) and the slurry tank (7) supply slurry to the spray pipes through an external water pump.
4. The wet limestone / lime-gypsum dual-stage circulating desulfurization device according to claim 1, characterized in that, The flue gas dispersion section (9) is an inverted conical filter screen, and the inverted conical filter screen is fixed in the lower circulation desulfurization zone (3). A slurry distribution mechanism (8) is provided between the inverted conical filter screen and the lower slurry spraying layer. The slurry distribution mechanism (8) is used to distribute the slurry sprayed by the lower slurry spraying layer evenly to increase the contact range between the flue gas and the slurry.
5. A wet limestone / lime-gypsum dual-stage circulating desulfurization device according to claim 4, characterized in that, The slurry distribution mechanism (8) includes a drain plate (8-1), on which an annular sleeve (8-2) is fixedly fitted. The annular sleeve (8-2) is fixedly connected in the lower circulation desulfurization zone (3), and the interior of the annular sleeve (8-2) is inclined.
6. The wet limestone / lime-gypsum dual-stage circulating desulfurization device according to claim 1, characterized in that, A wire mesh demister (10) is installed in the upper circulation desulfurization zone (4), and the wire mesh demister (10) is located between the flue gas outlet and the slurry spray layer.