A smoke whitening device, chimney and smoke whitening method

Abstract

The present invention discloses a smoke whitening device, a chimney and a smoke whitening method. The disclosed smoke whitening device includes a cylinder, a smoke channel is formed in the cylinder, and the cylinder forms at least one air introduction channel connecting the smoke channel and the external space of the cylinder to introduce air into the smoke channel. With the smoke whitening device, air is introduced into the smoke channel through the air introduction channel and mixed with the smoke to be treated. Since the air has a low water content and is relatively dry, the humidity of the smoke to be treated can be reduced, thereby maintaining an unsaturated state, avoiding or reducing water condensation, and achieving the purpose of eliminating or reducing the smoke whitening phenomenon. The smoke whitening device provided by the present invention can achieve smoke whitening by introducing air in advance based only on the air introduction channel on the cylinder, and has a simple and reliable structure and maintains a low cost.

Description

Technical Field

[0001] This invention relates to industrial flue gas treatment technology, and particularly to a flue gas whitening device, as well as a chimney including the flue gas whitening device and a flue gas whitening method using the above-mentioned flue gas whitening device. Background Technology

[0002] Flue gas emitted from power plant boilers, petrochemical heating furnaces, and other sources contains pollutants such as sulfur and nitrates. To prevent pollution incidents such as acid rain caused by direct emissions of flue gas, appropriate methods are currently used to purify the flue gas, reducing or removing pollutants.

[0003] Currently, the most common method for purifying flue gas by desulfurization or denitrification is the wet process. This involves contacting the flue gas with a slurry containing an absorbent to absorb and separate pollutants from the flue gas for harmless treatment, and then releasing the purified flue gas back into the atmosphere.

[0004] When flue gas is purified using a wet process, its moisture content is relatively high. As it is discharged into the atmosphere, the temperature drops (usually to 50-60℃), and the relative humidity of the flue gas increases, reaching a state of wet saturation, i.e., 100% relative humidity. At this point, as the flue gas, under low temperature and high humidity conditions, is discharged into the atmosphere through the chimney, the water in the flue gas condenses, forming water droplets. These small droplets are refracted and scattered by the atmosphere, forming a visible white plume, which is the phenomenon known as white smoke in flue gas.

[0005] To eliminate or mitigate the white smoke phenomenon during flue gas discharge, several methods are currently available. These include: heating, which involves heating the flue gas before discharge (either by using a heater to directly raise the temperature or by adding high-temperature gas), reducing the relative humidity and keeping the flue gas unsaturated, thus eliminating white smoke; dehumidification, which uses condensation to dehumidify the flue gas, reducing its water content and absolute moisture content, keeping it unsaturated and eliminating white smoke; dehumidification followed by heating, which involves first condensing to reduce absolute humidity and then heating the flue gas to reduce relative humidity; and solution dehumidification, which uses a liquid absorbent to absorb moisture from the flue gas, utilizing the water vapor partial pressure difference between the absorbent and the flue gas to allow moisture to migrate between them, releasing and absorbing latent heat of vapor and recovering moisture from the flue gas.

[0006] While existing methods can eliminate white smoke during flue gas emissions to some extent, they all suffer from drawbacks such as high cost and complex structure.

[0007] How to better eliminate or mitigate the white smoke from exhaust gases, reduce costs, and simplify the structure are currently technical challenges for those skilled in the art. Summary of the Invention

[0008] The purpose of this invention is to provide a smoke whitening device that can better eliminate or mitigate white smoke in exhaust gas while maintaining low cost and simple structure.

[0009] The present invention also provides a chimney including a flue gas whitening device and a flue gas whitening method using the flue gas whitening device.

[0010] The flue gas whitening device provided by this invention includes a cylindrical body, within which a flue gas channel is formed. The cylindrical body also forms at least one air inlet channel connecting the flue gas channel and the external space of the cylindrical body to introduce air into the flue gas channel. Using this flue gas whitening device, air is introduced into the flue gas channel through the air inlet channel and mixed with the flue gas to be treated. Because the air has low moisture content and is relatively dry, the humidity of the flue gas to be treated can be reduced, thus maintaining an unsaturated state, avoiding or reducing moisture condensation, and achieving the purpose of eliminating or reducing the phenomenon of white smoke in the flue gas.

[0011] This flue gas whitening device allows for pre-mixing of flue gas with air before it is discharged. Compared to existing technologies, this device divides the mixing or contact between flue gas and air into two stages. By altering the changes in flue gas parameters (temperature and humidity) during the mixing process, the device keeps the flue gas variation curve outside the humidity saturation curve and maintains it in an unsaturated state, thereby reducing or eliminating white smoke during flue gas discharge.

[0012] The flue gas whitening device provided by the present invention can achieve flue gas whitening simply by introducing air in advance through the air introduction channel on the cylinder. It has a simple and reliable structure and maintains a low cost.

[0013] In a further technical solution, the air inlet channel is vertically inclined in the direction from the outside to the inside, with the inclination direction being the same as the flue gas flow direction in the flue gas channel. This allows the introduced air to have a component perpendicular to the flue gas flow direction, promoting the mixing of the introduced air and the flue gas to be treated, improving the controllability of flue gas parameters, and enhancing the whitening effect. Similarly, in the direction from the outside to the inside, the air inlet channel is circumferentially inclined, which can create a rotating flow of introduced air, further promoting the mixing of the introduced air and the flue gas to be treated, improving the uniformity of mixing or contact, enhancing the controllability of flue gas parameters, and improving the whitening effect.

[0014] In a further technical solution, the cross-sectional area of ​​the air inlet channel gradually increases from the outside to the inside. This allows the airflow velocity to gradually decrease, making the contact between the introduced air and the flue gas gentler, promoting the uniformity of mixing between the introduced air and the flue gas to be treated, improving the controllability of the flue gas parameters, and enhancing the whitening effect.

[0015] In an optional technical solution, the flue gas passage forms a throat section, and the inner openings of the multiple air inlet channels are located in the throat section. Compared with the upper or lower flue gas passage, the throat section has a smaller flow cross-section. Based on the principle of fluid flow, the flow velocity in the throat section is faster, which can promote the mixing of the introduced air and the flue gas to be treated. After passing through the throat section, the flow cross-section of the flue gas passage increases and the flow velocity decreases, which can promote the uniformity of mixing between the introduced air and the flue gas to be treated. This improves the controllability of flue gas parameters and enhances the whitening effect.

[0016] In an optional technical solution, a rotating impeller is provided in the air introduction channel. The rotating impeller buffers the unevenness of the introduced air caused by changes in the external environment, thereby improving the controllability of flue gas parameters and enhancing the whitening effect. For example, the air introduction channel can also be equipped with a drive device for driving the rotating impeller to rotate. This drive device can control the rotational speed of the impeller, thereby controlling the amount of introduced air, improving the controllability of flue gas parameters, and enhancing the whitening effect.

[0017] In an optional technical solution, the flue gas whitening device further includes a uniform dispersion inner cylinder, which is located inside the cylinder and opposite to the inner opening of the air inlet channel, thereby allowing air to enter the flue gas channel more evenly. The uniform dispersion inner cylinder may be provided with uniform dispersion holes, which can make the introduced air mix with the flue gas more gently, improve the controllability of flue gas parameters, and improve the whitening effect.

[0018] In an optional technical solution, a narrow-diameter mixing section is formed at the upper end of the uniformly distributed inner cylinder in the flue gas channel. The flow cross-section of the narrow-diameter mixing section is smaller than the inner diameter of the uniformly distributed inner cylinder to promote the contact and mixing of the introduced air and the flue gas. Furthermore, an extended guiding section is formed at the upper end of the uniformly distributed inner cylinder, extending into the narrow-diameter mixing section to guide the mixing of air and flue gas, thereby improving the uniformity of mixing or contact.

[0019] The chimney provided by this invention includes a flue gas inlet and a flue gas outlet, and also includes any of the aforementioned flue gas whitening devices. The flue gas to be treated passes through the flue gas inlet, the flue gas passage of the flue gas whitening device, and the flue gas outlet before being discharged into the atmosphere. Due to the inclusion of the aforementioned flue gas whitening device, this chimney also possesses corresponding technical advantages.

[0020] The flue gas whitening method provided by this invention utilizes any of the aforementioned flue gas whitening devices. Before the flue gas to be treated is discharged, air is introduced through the air inlet channel to allow the flue gas to be treated to mix with the air for the first time, thereby reducing the relative humidity of the flue gas. Then, the flue gas with reduced relative humidity is discharged. For the same reason, the white smoke phenomenon during flue gas emission can also be reduced or eliminated. Attached Figure Description

[0021] Figure 1 This is a cross-sectional structural diagram of a flue gas whitening device provided in an embodiment of the present invention.

[0022] Figure 2 for Figure 1 Schematic diagram of the AA section structure.

[0023] Figure 3 This is a schematic diagram of the trajectory of flue gas moisture content and temperature changes, including the theoretical trajectory line of flue gas exhaust, the trajectory line of flue gas under normal exhaust, and the trajectory line of flue gas after mixing with air according to the present invention.

[0024] Figure 4 This is a vertical half-section diagram of a flue gas whitening device provided in another embodiment of the present invention.

[0025] Figure 5 This is a schematic diagram of the transverse cross-sectional structure of a flue gas whitening device provided in an embodiment of the present invention.

[0026] Figure 6 This is a vertical cross-sectional view of a flue gas whitening device provided in one embodiment of the present invention.

[0027] Figure 7 This is a vertical cross-sectional view of a flue gas whitening device provided in another embodiment of the present invention.

[0028] Figure 8 This is a vertical cross-sectional view of the flue gas whitening device in another embodiment of the present invention. Detailed Implementation

[0029] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0030] It should be noted that:

[0031] 1. In this document, directional terms such as "upper", "lower", "inner" and "outer" are used with reference to the specific application scenario of the flue gas whitening device or chimney.

[0032] 2. According to those skilled in the art, “white smoke elimination” includes not only eliminating white smoke but also reducing white smoke.

[0033] Please refer to Figure 1 and Figure 2 , Figure 1 This is a cross-sectional view of a flue gas whitening device according to an embodiment of the present invention, wherein the flue gas channel 110 extends in the vertical direction so that the flue gas flows from bottom to top. Figure 2 for Figure 1 Schematic diagram of the AA section structure.

[0034] The smoke whitening device provided in this embodiment includes a cylinder 100, a smoke channel 110 is formed inside the cylinder 100, and at least one air inlet channel 120 is formed in the cylinder 100 to connect the smoke channel 110 and the external space of the cylinder 100, so as to introduce air into the smoke channel 110.

[0035] Using this flue gas whitening device, air is introduced into the flue gas channel 110 through the air introduction channel 120 and mixed with the flue gas to be treated.

[0036] Please refer to Figure 3 , Figure 3 This diagram illustrates the trajectory of flue gas moisture content versus temperature change, where moisture content refers to the amount of water present in gaseous form. The diagram shows the theoretical trajectory of flue gas exhaust, the trajectory during normal exhaust, and the trajectory of flue gas after mixing with air according to this patent. According to the theoretical trajectory (moisture saturation line) of flue gas exhaust, as the temperature decreases, the moisture content of the flue gas also decreases, meaning the absolute water content in the flue gas decreases with temperature; excess moisture will condense into water droplets. During normal exhaust, the trajectory of the flue gas intersects the theoretical trajectory, with intersection points A and B. When the flue gas parameters are between A and B, the moisture in the flue gas will exist in a supersaturated state, and some of the moisture will condense into water droplets, resulting in white smoke. Using the flue gas whitening device provided by this invention, the flue gas comes into premature contact with air within the device, and by appropriately controlling the air-to-flue gas ratio, the flue gas parameters can be varied along the YH line. After passing through the flue gas whitening device, the flue gas is then vented. During the venting process, the flue gas changes along the HC line, thereby keeping the flue gas state above the theoretical trajectory line (wet saturation line). This prevents moisture in the flue gas from condensing, thus avoiding or reducing the occurrence of white smoke.

[0037] The flue gas whitening device provided by the present invention can achieve flue gas whitening simply by introducing air in advance through the air introduction channel 120 on the cylinder 100. It has a simple and reliable structure and maintains a low cost.

[0038] Multiple air inlet channels 120 can be provided, and these channels can be evenly distributed. Depending on the location, local climate, and wind direction, they can also be unevenly distributed to ensure mixing and contact between the introduced air and the flue gas. Alternatively, the air inlet channels 120 can be sequentially arranged in the flue gas flow direction to allow the flue gas to make two, three, or more contacts before exhaust, thereby altering the flue gas parameter trajectory and ensuring the flue gas state remains above the theoretical trajectory line (wet saturation line), maintaining an unsaturated state and preventing or reducing white smoke.

[0039] The air inlet channel 120 can be a through hole perpendicular to the center of the flue gas channel 110, or it can have a corresponding tilt angle. For example... Figure 4As shown, this figure is a vertical half-sectional structural schematic diagram of a flue gas whitening device provided in another embodiment of the present invention. In the direction from the outside to the inside, the air inlet channel 120 can be vertically inclined, with the inclination direction being the same as the flue gas flow direction in the flue gas channel 110. This allows the introduced air to have a component perpendicular to the flue gas flow direction, promoting the mixing of the introduced air and the flue gas to be treated, improving the controllability of flue gas parameters, and enhancing the whitening effect. In this embodiment, in the direction from the outside to the inside, the flow cross-section of the air inlet channel 120 can be gradually increased, which allows the introduced air flow velocity to gradually decrease, making the contact between the introduced air and the flue gas gentler, promoting the uniformity of mixing between the introduced air and the flue gas to be treated, improving the controllability of flue gas parameters, and enhancing the whitening effect. Of course, according to actual needs, the flow cross-section of the air inlet channel 120 can have a suitable flow cross-section or a flow cross-section of an appropriate shape to meet actual requirements.

[0040] In addition, such as Figure 5 The diagram shows a cross-sectional view of a flue gas whitening device according to an embodiment of the present invention. In the direction from the outside to the inside, the air inlet channel 120 can be inclined circumferentially, thereby forming a rotating flow of introduced air through multiple air inlet channels 120. This also promotes the mixing of the introduced air with the flue gas to be treated, improves the uniformity of mixing or contact, enhances the controllability of flue gas parameters, and improves the whitening effect.

[0041] like Figure 6 As shown in the figure, this is a vertical cross-sectional view of a flue gas whitening device according to an embodiment of the present invention. In this flue gas whitening device, the flue gas channel 110 forms a throat section 111, which is a portion with a relatively small flow cross-section. The flow cross-section of the upper part and the flow cross-section of the lower part are both larger than the flow cross-section of this portion. The minimum flow cross-sectional area of ​​the throat section 1111 is 40%-85% of the upper flow cross-section, and the lower flow cross-section can be equal to the upper flow cross-section. The inner openings of the plurality of air inlet channels 120 are located in the throat section 111. In a preferred embodiment, the inner openings of the plurality of air inlet channels 120 are all located at the minimum flow cross-sectional area of ​​the throat section 111. Based on the principle of fluid flow, the throat section 111 has a small flow cross-section, resulting in a faster flue gas flow velocity and lower pressure, which promotes the mixing of the introduced air and the flue gas to be treated. After passing through the throat section 111, the flow cross-section of the flue gas channel 110 increases and the flow velocity decreases, which promotes the uniformity of the mixing of the introduced air and the flue gas to be treated. This improves the controllability of the flue gas parameters and enhances the whitening effect.

[0042] In a preferred embodiment, a rotating impeller is provided in the air inlet channel 120. When the external atmospheric pressure suddenly increases, the rotating impeller can rotate against the external airflow, thus providing a buffering effect; when the external atmospheric pressure suddenly decreases, the inertia of the rotating impeller can generate a suction effect, thereby improving the uniformity of the introduced air, thus improving the controllability of flue gas parameters and enhancing the whitening effect. For example, the air inlet channel 120 can also be provided with a drive device for driving the rotating impeller to rotate. This drive device can control the rotational speed of the impeller, thereby controlling the amount of introduced air, improving the controllability of flue gas parameters, and enhancing the whitening effect.

[0043] like Figure 7 As shown in the figure, this is a vertical cross-sectional view of a flue gas whitening device according to another embodiment of the present invention. In this flue gas whitening device, the device further includes a uniform distribution inner cylinder 200, which is located inside the cylinder body 100 and opposite to the inner opening of the air inlet channel 120. This allows air introduced through the air inlet channel 120 to enter the flue gas channel through the gap between the outer wall of the uniform distribution inner cylinder 200 and the inner wall of the cylinder body 100, and mix with the flue gas within a 360-degree range at the upper end of the uniform distribution inner cylinder 200, thus entering the flue gas channel 110 more evenly. The uniform distribution inner cylinder 200 may be provided with uniform distribution holes, which allows the introduced air to mix more gently with the flue gas, improving the controllability of flue gas parameters and enhancing the whitening effect.

[0044] like Figure 8 The diagram shows a vertical cross-sectional view of another flue gas whitening device. In the flue gas passage 110 of this device, a narrow-diameter mixing section 112 is formed at the upper end of the uniform distribution inner cylinder 200. The flow cross-section of the narrow-diameter mixing section 112 is smaller than the inner diameter of the uniform distribution inner cylinder 200 to promote the contact and mixing of the introduced air and the flue gas. An extension guide section 300 may be formed at the upper end of the uniform distribution inner cylinder 200. The extension guide section 300 extends into the narrow-diameter mixing section to guide the mixing of air and flue gas, thereby improving the uniformity of mixing or contact.

[0045] The chimney provided by this invention includes a flue gas inlet and a flue gas outlet, and also includes any of the aforementioned flue gas whitening devices. The flue gas to be treated passes through the flue gas inlet, the flue gas passage 110 of the flue gas whitening device, and the flue gas outlet before being discharged into the atmosphere. Due to the presence of the aforementioned flue gas whitening device, the chimney also possesses corresponding technical advantages. The cylinder 100 of the flue gas whitening device can be integrally formed with the chimney, or it can be assembled with the chimney through installation.

[0046] The flue gas whitening method provided by this invention can utilize any of the above-mentioned flue gas whitening devices. Before the flue gas to be treated is discharged, air is introduced through the air introduction channel 120 to mix the flue gas to be treated with the air for the first time, thereby reducing the relative humidity of the flue gas to be treated. Then, the flue gas to be treated with reduced relative humidity is discharged. This process involves mixing and contacting the flue gas with the air two or more times, keeping the parameters of the flue gas above the temperature saturation trajectory line, i.e., maintaining an unsaturated state, thereby reducing or eliminating the white smoke phenomenon during flue gas emission. The specific principle will not be elaborated further.

[0047] The specific embodiments provided by the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention, and the descriptions of the embodiments above are only for the purpose of helping to understand the core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A flue gas whitening device, comprising a cylindrical body (100), wherein a flue gas passage (110) is formed within the cylindrical body (100), characterized in that, The cylinder (100) forms at least one air inlet channel (120) that connects the flue gas passage (110) and the external space of the cylinder (100) to introduce air into the flue gas passage (110).

2. The flue gas whitening device according to claim 1, characterized in that, The air inlet channel (120) is vertically inclined in the direction from the outside to the inside, and the inclination direction is the same as the flue gas flow direction in the flue gas channel (110); or / and, The air inlet channel (120) is circumferentially inclined in the direction from the outside to the inside.

3. The flue gas whitening device according to claim 1, characterized in that, The cross-sectional area of ​​the air inlet channel (120) gradually increases from the outside to the inside.

4. The flue gas whitening device according to claim 1, characterized in that, The flue gas passage (110) forms a throat section (111), and the inner openings of the plurality of air inlet passages (120) are located in the throat section (111).

5. The flue gas whitening device according to claim 1, characterized in that, A rotating blade wheel is provided in the air inlet channel (120).

6. The flue gas whitening device according to any one of claims 1 to 5, characterized in that, It also includes a uniform distribution inner cylinder (200), which is located inside the cylinder body (100) and is opposite to the inner opening of the air inlet channel (120).

7. The flue gas whitening device according to claim 6, characterized in that, The uniform distribution inner cylinder (200) is provided with uniform distribution holes.

8. The flue gas whitening device according to claim 7, characterized in that, In the flue gas passage (110), a narrow-diameter mixing section (112) is formed at the upper end of the uniformly distributed inner cylinder (200), and the flow cross section of the narrow-diameter mixing section (112) is smaller than the inner diameter of the uniformly distributed inner cylinder (200).

9. A chimney, comprising a flue gas inlet and a flue gas outlet, characterized in that, The flue gas whitening device according to any one of claims 1 to 8 is provided, wherein the flue gas to be treated is discharged into the atmosphere after passing through the flue gas inlet, the flue gas passage (110) of the flue gas whitening device and the flue gas exhaust port.

10. A method for eliminating white smoke, characterized in that, Includes the following steps: Using the flue gas whitening device according to any one of claims 1 to 9, before the flue gas to be treated is discharged, air is introduced through the air introduction channel (120) to mix the flue gas to be treated with the air for the first time, thereby reducing the relative humidity of the flue gas to be treated; then, the flue gas to be treated with the reduced relative humidity is discharged.

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