A flue gas whitening device with multi-stage condensation phase change and a flue gas whitening method

Abstract

The present invention relates to the field of waste gas treatment technology, and discloses a flue gas decolorization device with multi-stage condensation phase change and a flue gas decolorization method. The device comprises: a main body; a multi-stage condensation phase change system comprising a pretreatment module and a condensation heat exchange module; external cold air entering the pretreatment module performs a first-stage cooling on the hot gas, and the cold air entering the pretreatment module does not come into contact with the hot gas; the secondary cold air and external cold air entering the condensation heat exchange module perform a second-stage cooling on the hot gas, and neither comes into contact with the hot gas; the secondary cold air and the discharged cold air discharged from the condensation heat exchange module are mixed with the discharged hot gas above the condensation heat exchange module, performing a third-stage cooling on the hot gas, and a water cutting system intercepts the moisture contained in the mixed gas; and the exhaust module extracts the mixed gas to a gas output port for discharge. The advantages of the present invention are that it uses a three-stage gas phase heat exchange to treat the flue gas, gradually reduce the flue gas temperature, and remove water vapor, resulting in a good decolorization effect, economy, and environmental protection.

Description

Technical Field

[0001] The present invention relates to the technical field of waste gas treatment, and in particular to a flue gas whitening device with multi-stage condensation phase change and a flue gas whitening method. Background Art

[0002] The co-processing of solid waste in ceramsite kilns produces white flue gas. Unlike flue gas from traditional coal-fired boilers, this flue gas contains a more complex chemical composition and particulate matter. This flue gas originates from various chemical reactions during the waste treatment process and changes in material properties during the ceramsite sintering process. It is characterized by high salinity, high corrosiveness, high levels of VOCs, non-methane hydrocarbons, and high levels of aerosols. This type of industrial white flue gas generally requires flue gas whitening before it can be discharged.

[0003] Traditional flue gas whitening methods primarily include heating, condensation, condensation-reheating, solution absorption, and electrostatic demisting. Condensation has garnered widespread attention due to its cost-effectiveness in eliminating white smoke. Condensation can be further categorized as indirect or direct condensation. Direct condensation typically uses a specialized fine mist spray gun to cool the flue gas, rapidly condensing water vapor. Indirect condensation, on the other hand, utilizes demineralized water flowing through heat exchange tubes to cool and condense the flue gas. While both methods are effective in eliminating white smoke, they both require low water supply temperatures and high circulating water volumes, which undoubtedly increases water consumption and disposal costs. Summary of the Invention

[0004] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is to propose a flue gas dewhitening device and a flue gas dewhitening method with multi-stage condensation phase change, which utilize three-stage gas phase heat exchange for treatment, gradually reduce the flue gas temperature, and remove water vapor, with good dewhitening effect, economy and environmental protection.

[0005] The technical solution adopted by the present invention to solve the technical problem is to propose a flue gas decolorization device with multi-stage condensation phase change, which can decolorize the hot gas discharged from the chimney, including:

[0006] A main body, a water collecting structure is provided at the bottom of the main body, and the chimney can be connected to the main body from the bottom of the main body to pass the hot air in the chimney into the main body; a gas output port is provided at the top of the main body, and an exhaust module is provided near the gas output port;

[0007] A multi-stage condensation phase change system and a water cutting system are arranged in sequence from bottom to top, wherein the multi-stage condensation phase change system includes a pretreatment module and a condensation heat exchange module;

[0008] The pre-processing module is provided with a first hot air inlet, a first hot air outlet, a first cold air inlet, and a first cold air outlet. The hot air discharged from the chimney into the main body can enter the pre-processing module from the first hot air inlet and be discharged from the first hot air outlet; the outside cold air can enter the pre-processing module from the first cold air inlet and be discharged from the first cold air outlet. The outside cold air entering the pre-processing module performs a first-stage cooling on the hot air, and the cold air entering the pre-processing module does not come into contact with the hot air.

[0009] The condensing heat exchange module is arranged above the pretreatment module, and the condensing heat exchange module is provided with a second hot air inlet, a second hot air outlet, a second cold air inlet, a second cold air outlet, a third cold air inlet and a third cold air outlet. The hot air discharged from the first hot air outlet after passing through the pretreatment module can enter the condensing heat exchange module from the second hot air inlet and be discharged from the second hot air outlet; the sub-cold air discharged from the first cold air outlet can enter the condensing heat exchange module from the second cold air inlet and be discharged from the second cold air outlet; the outside cold air can enter the condensing heat exchange module from the third cold air inlet and be discharged from the third cold outlet; the sub-cold air entering the condensing heat exchange module and the outside cold air perform secondary cooling on the hot air, and neither of them contacts the hot air in the condensing heat exchange module;

[0010] The sub-cold air discharged from the second cold air inlet of the condensing heat exchange module and the cold air discharged from the third cold air outlet of the condensing heat exchange module are mixed with the hot air discharged from the second hot air outlet of the condensing heat exchange module above the condensing heat exchange module, and the hot air is cooled in three stages. The water cutting system can intercept the moisture contained in the mixed gas, and the intercepted moisture flows downward into the water collecting structure; the exhaust module can draw the mixed gas upward to the gas output port for discharge.

[0011] Furthermore, the temperature of the hot air discharged from the second hot air outlet is greater than the temperature of the sub-cold air discharged from the second cold air outlet;

[0012] Furthermore, the temperature of the sub-cold air discharged from the second cold air outlet is greater than the temperature of the cold air discharged from the third cold air outlet.

[0013] Furthermore, the pre-processing module is provided with a first air flow channel and a second air flow channel spaced apart from each other, one of the first air flow channel and the second air flow channel is used for circulation of external cold air, and the other of the first air flow channel is used for circulation of hot air discharged from the chimney;

[0014] The condensing heat exchange module is provided with a third air flow channel, a fourth air flow channel and a fifth air flow channel which are spaced apart from each other. One of the third air flow channel, the fourth air flow channel and the fifth air flow channel is used for circulation of external cold air, one is used for circulation of sub-cold air and one is used for circulation of hot air.

[0015] Furthermore, the pre-processing module is provided with an air cooler, which is located at the first cold air inlet and can draw external cold air into the pre-processing module.

[0016] Furthermore, the direction of the second cold air outlet is perpendicular to the direction of the second hot air outlet, and the direction of the third cold air outlet is perpendicular to the direction of the second hot air outlet.

[0017] Furthermore, the condensing heat exchange module includes multiple groups of condensing heat exchangers, and each group of condensing heat exchangers is evenly distributed on the main body after being rotated 45 degrees counterclockwise.

[0018] Furthermore, the water cutting system includes a water cutting device, and the water cutting device is provided with multiple layers of corrugated blades inside; the water cutting device gradually protrudes downward from the end to the center;

[0019] The exhaust module is a fan, and when the fan rotates, negative pressure is formed below the fan, and the mixed gas is drawn to the gas output port for discharge.

[0020] Furthermore, the water collection structure is arranged in a conical shape, and its cross-sectional area decreases from top to bottom; a drainage pipe is provided on the outer wall of the water collection structure, and the water collected by the water collection structure can be discharged through the drainage pipe.

[0021] Furthermore, the chimney is provided with a hot air outlet near its top, and a water retaining cover is provided on the top of the chimney, the water retaining cover shielding the top of the hot air outlet, and the water retaining cover is conical in shape, and its cross-sectional area increases from top to bottom;

[0022] The water falling onto the water retaining cover can be guided by the water retaining cover to the water collecting structure.

[0023] The technical solution adopted by the present invention to solve the technical problem is to provide a flue gas decolorization method, which is applied to the above-mentioned flue gas decolorization device with multi-stage condensation phase change. The method comprises the following steps:

[0024] S1, chimney to introduce hot air from the lower part of the main body;

[0025] S2. Hot air enters the pre-processing module from the first hot air inlet from bottom to top and is discharged from the first hot air outlet; external cold air enters the pre-processing module from the first cold air inlet and is discharged from the first cold air outlet; in the pre-processing module, the incoming air cools the hot air in a first stage without coming into contact with the hot air;

[0026] S3, the hot air discharged from the first hot air outlet enters the condensing heat exchange module through the second hot air inlet and is discharged from the second hot air outlet; the sub-cold air discharged from the first cold air outlet enters the condensing heat exchange module through the second cold air inlet and is discharged from the second cold air outlet; the outside cold air enters the condensing heat exchange module through the third cold air inlet and is discharged from the third cold air outlet; the sub-cold air and the outside cold air perform secondary cooling on the hot air in the condensing heat exchange module, and neither of them comes into contact with the hot air in the condensing heat exchange module;

[0027] S4, the hot air output from the second hot air outlet, the sub-cooled air discharged from the second cold air outlet, and the cold air discharged from the third cold air outlet are mixed to cool the hot air; the water cutting system intercepts moisture in the mixed air;

[0028] S5. The exhaust module draws the mixed gas to the gas outlet at the top of the main body for discharge.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects:

[0030] In the present invention, a multi-stage condensation phase change system is provided in the main body, which includes a pretreatment module and a condensation heat exchange module arranged from bottom to top. The pretreatment module and the condensation heat exchange module both include multiple air flow channels for gas to pass through. When the hot air in the chimney is discharged from the bottom of the main body, it first passes through the pretreatment module from bottom to top. The pretreatment module inhales external cold air, and the external cold air performs a first-stage cooling on the hot air at the pretreatment module; the hot air discharged from the pretreatment module and the secondary cold air enter the condensation heat exchange module, and the condensation heat exchange module inhales external cold air, and the secondary cold air and the external cold air perform a second-stage cooling on the hot air at the condensation heat exchange module. During the first-stage cooling and the second-stage cooling process, the cold air does not directly contact the hot air; finally, the external cold air, the secondary cold air and the hot air treated by the condensation heat exchange module are fully mixed above it, and the hot air is cooled for a third time; the water cutting system captures and intercepts the moisture and tiny particles in the mixed gas, and dissolves harmful substances at the same time; the qualified mixed gas is discharged from the gas output port at the top of the main body. This device uses a three-stage gas-phase heat exchange process to treat flue gas, applying a multi-grade cooling gradient to the flue gas. This ensures complete removal of moisture from the flue gas, prevents sudden temperature drops from affecting the device, and extends its service life. It also facilitates accurate control of the flue gas temperature. During the pre-cooling process, the cold air is controlled to prevent direct contact with the hot air. Only at the final stage, above the condensing heat exchange module, do the three streams of gas at different temperatures mix, ensuring uniform mixing and preventing evenly distributed overcooling or overheating. The overall flue gas whitening effect is excellent, and it is economical and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of the flue gas whitening device of the present invention;

[0032] Figure 2 Schematic diagram of gas flow in the flue gas whitening device;

[0033] Figure 3 It is a structural diagram of the preprocessing module;

[0034] Figure 4 This is a flow chart of the flue gas dewhitening method.

[0035] In the picture:

[0036] 1. Main body; 10. Water collection structure; 101. Drain pipe; 100. Gas outlet; 11. Exhaust module;

[0037] 2. Multi-stage condensation phase change system; 21. Pretreatment module; 210. Air cooler; 211. First hot air inlet; 212. First hot air outlet; 213. First cold air inlet; 214. First cold air outlet; 22. Condensation heat exchange module; 221. Second hot air inlet; 222. Second hot air outlet; 223. Second cold air inlet; 224. Second cold air outlet; 225. Third cold air inlet; 226. Third cold air outlet;

[0038] 3. Water cutting system;

[0039] 4. Chimney; 40. Water retaining cover. DETAILED DESCRIPTION

[0040] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.

[0041] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0042] In addition, in the present invention, descriptions such as "first," "second," and "one" are for descriptive purposes only and should not be understood to indicate or imply their relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0043] In the present invention, unless otherwise specified or limited, the terms "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can mean fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will be able to understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0044] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0045] Example 1:

[0046] like Figure 1-Figure 3 As shown, a flue gas bleaching device with a multi-stage condensation phase change system can bleach hot gases exhausted from a chimney 4. It is widely applicable to various industrial flue gas treatment scenarios, especially when the amount of hot and humid flue gas is large, and can demonstrate the environmental and economic benefits of this flue gas bleaching device. The flue gas bleaching device mainly includes: a main body 1, a multi-stage condensation phase change system 2, and a water cut-off system 3. The exhaust module 11 at the top of the main body 1 can form a negative pressure system near the top of the main body 1.

[0047] In the main body 1, a water collection structure 10 is provided at the bottom of the main body 1. The water collection structure 10 is arranged in a conical shape, and its cross-sectional area decreases from top to bottom. A drain pipe 101 is provided on the outer wall of the water collection structure 10, and the water collected by the water collection structure 10 can be discharged through the drain pipe 101. During the process of flue gas decolorization, the moisture in the flue gas is condensed and intercepted by the water cutting system 3, and the generated droplets converge. When their gravity exceeds the combined force of the buoyancy of the rising gas and the surface tension of the liquid, they will be peeled off from the water cutting system 3 under the action of gravity and fall into the water collection structure 10. The water is converged through the water collection structure 10 and discharged to other subsequent processes or links through the drain pipe 101 for water recycling and reuse. The water collection structure 10 is a water collection bucket.

[0048] The chimney 4 can be passed into the main body 1 from the bottom of the main body 1 to pass the hot air in the chimney 4 into the main body 1. The hot air is generally high-temperature and high-humidity flue gas, and its temperature can reach about 80 degrees. A gas outlet 100 is provided at the top of the main body 1, and an exhaust module 11 is provided near the gas outlet 100. The exhaust module 11 is a large fan, which is equivalent to the air outlet of the large fan leading to the outside world. The rotation speed of the large fan can control the amount of external cold air entering the multi-stage condensation phase change system 2, as well as the mixing time and mixing degree of the hot air and multiple streams of cold air at the top of the main body 1, thereby controlling the effect of flue gas de-whitening. When the fan rotates, a negative pressure system is formed below the fan, which facilitates the mixing of multiple streams of gas and facilitates the discharge of the mixed gas. Among them, the chimney 4 is provided with a hot gas outlet near its top. The hot gas outlet is a ring outlet and is arranged on the side wall of the chimney 4 near the top. A water retaining cover 40 is provided on the top of the chimney 4. The water retaining cover 40 blocks the top of the hot gas output port, and the water retaining cover 40 is set in a cone shape, and its cross-sectional area increases from top to bottom. The water falling onto the water retaining cover 40 can be guided by the water retaining cover 40 to the water collection structure 10. The setting of the water retaining cover 40 can prevent the moisture generated by condensation from mixing into the chimney 4, thereby affecting the whitening of the flue gas.

[0049] The multi-stage condensation phase change system 2 and the water removal system 3, arranged sequentially from bottom to top, comprise a pretreatment module 21 and a condensation heat exchange module 22. The pretreatment module 21 is equipped with a first hot gas inlet 211, a first hot gas outlet 212, a first cold gas inlet 213, and a first cold gas outlet 214. Hot gas discharged from the chimney 4 into the main body 1 can enter the pretreatment module 21 through the first hot gas inlet 211 and be discharged through the first hot gas outlet 212. External cold air can enter the pretreatment module 21 through the first cold air inlet 213 and be discharged through the first cold air outlet 214. The external cold air entering the pretreatment module 21 cools the hot gas in a primary stage. Since the cold air entering the pretreatment module 21 does not come into contact with the hot gas, some water vapor begins to condense into water droplets and is collected. In this embodiment, the flue gas (i.e., hot gas) discharged from the chimney 4 is divided into two paths and enters two groups of pretreatment modules 21, using the external cold air as a cooling source to cool the hot gas.

[0050] Specifically, a first air flow channel and a second air flow channel are provided in the pre-processing module 21, which are spaced apart from each other. One of the first air flow channel and the second air flow channel is used for circulation of cold air from the outside, and the other of the two is used for circulation of hot air discharged from the chimney 4. The separation ensures that the cold air from the outside does not come into direct contact with the hot air in the pre-processing module 21, thereby avoiding a sudden drop in the temperature of the hot air. For example, the temperature of the hot air can be reduced to below 60 degrees after the first level of cooling is performed in the pre-processing module 21. Preferably, an air cooler 210 is provided on the pre-processing module 21. The air cooler 210 is located at the first cold air inlet 213 and can draw cold air from the outside into the pre-processing module 21. By controlling the rotation speed of the air cooler 210, the amount and flow rate of cold air from the outside entering the pre-processing module 21 can be controlled.

[0051] The condensing heat exchange module 22 is positioned above the pretreatment module 21 and is equipped with a second hot air inlet 221, a second hot air outlet 222, a second cold air inlet 223, a second cold air outlet 224, a third cold air inlet 225, and a third cold air outlet 226. After passing through the pretreatment module 21 and exiting the first hot air outlet, the hot air can enter the condensing heat exchange module 22 through the second hot air inlet 221 and exit through the second hot air outlet 222. The sub-cooled air exiting the first cold air outlet 214 can enter the condensing heat exchange module 22 through the second cold air inlet 223 and exit through the second cold air outlet 224. Ambient cold air can enter the condensing heat exchange module 22 through the third cold air inlet 225 and exit through the third cold air outlet 226. The sub-cooled air and ambient cold air entering the condensing heat exchange module 22 provide a secondary cooling effect on the hot air, and neither air comes into contact with the hot air in the condensing heat exchange module 22, further removing moisture. For example, after the secondary cooling, the temperature of the hot gas can be reduced to below 40 degrees. The temperature entering the condensing heat exchange module 22 is controlled below 60 degrees, which can effectively ensure the corrosion resistance and deformation resistance of the condensing heat exchange module 22. The condensing heat exchange module 22 of this embodiment is a condensing heat exchanger.

[0052] During use, the sub-cold air discharged from the second cold air inlet 223 of the condensing heat exchange module 22 and the cold air discharged from the third cold air outlet 226 of the condensing heat exchange module 22 are mixed with the hot air discharged from the second hot air outlet 222 of the condensing heat exchange module 22 above the condensing heat exchange module 22, and the hot air is cooled in three stages, that is, only at the end are the three gases of different temperatures fully mixed.

[0053] Specifically, the temperature of the hot air discharged from the second hot air outlet 222 is greater than the temperature of the sub-cold air discharged from the second cold air outlet 224. Furthermore, the temperature of the sub-cold air discharged from the second cold air outlet 224 is greater than the temperature of the cold air discharged from the third cold air outlet 226. That is, at the condensing heat exchange module 22, the temperature of the hot air discharged from the second hot air outlet 222 is the highest, the temperature of the sub-cold air discharged from the second cold air outlet 224 is the second lowest, and the temperature of the cold air discharged from the third cold air outlet 226 is the lowest. During the pre-cooling process, the cold air is controlled not to come into direct contact with the hot air. Only at the end, above the condensing heat exchange module 22, are the three gases of different temperatures mixed to ensure uniform mixing of the gases and prevent uniform overcooling or overheating. This results in a good overall flue gas whitening effect and is economical and environmentally friendly.

[0054] More specifically, the condensing heat exchange module 22 is provided with a third airflow channel, a fourth airflow channel, and a fifth airflow channel spaced apart from each other. One of the third airflow channel, the fourth airflow channel, and the fifth airflow channel is used to circulate external cold air, one to circulate sub-cold air, and one to circulate hot air. The second cold air outlet 224 is oriented perpendicular to the second hot air outlet 222, and the third cold air outlet 226 is oriented perpendicular to the second hot air outlet 222. This angle control ensures more uniform contact and mixing between hot and cold air, and maximizes the contact area for heat exchange. The condensing heat exchange module 22 of this embodiment includes multiple groups of condensing heat exchangers, each of which is rotated 45 degrees counterclockwise and evenly distributed on the main body 1. They are arranged in a diamond pattern, so that the outlet directions of cold and hot air form a 90° angle. This rotational arrangement ensures uniform contact between hot and cold air, and maximizes the contact area for heat exchange within a limited space. Preferably, reinforcing ribs are provided at the four corners and the middle of the condensing heat exchanger to fix the condensing heat exchanger and prevent deformation of the heat exchange plates in the heat exchanger.

[0055] It needs to be explained that the first air flow channel, the second air flow channel, the third air flow channel, the fourth air flow channel, and the fifth air flow channel can all be set as serpentine channels or wavy channels, and the channels for secondary cold air circulation can be set parallel to the channels for external cold air circulation.

[0056] The water-cutting system 3 can intercept the water contained in the mixed gas, and the intercepted water flows downward into the water collection structure 10. The water-cutting system 3 of this embodiment includes a water-cutting device, and the water-cutting device is internally provided with multiple layers of corrugated blades; the water-cutting device gradually protrudes downward from the end toward the center, i.e., a downward arched structure. Its advantages are good force resistance, simple structure, durability and maintenance, and easy manufacturing and processing. When the hot gas from the condensing heat exchanger mixes and cools the cold air during the rising process, the residual water therein can be effectively intercepted by the water-cutting device. At the same time, the VOCS, PM2.5, and some soluble pollutants contained in the hot gas can be dissolved in the droplets intercepted on the water-cutting device. After the droplets converge and become larger, they flow into the water collection structure 10 through gravity. The water-cutting device can effectively capture and remove remaining water droplets and tiny particles, thereby improving the cleanliness of the flue gas.

[0057] In actual use, this embodiment sets a multi-stage condensation phase change system 2 in the main body 1, which includes a pretreatment module 21 and a condensation heat exchange module 22 arranged from bottom to top. The pretreatment module 21 and the condensation heat exchange module 22 both include multiple air flow channels for gas to pass through. When the hot air in the chimney 4 is discharged from the bottom of the main body 1, it first passes through the pretreatment module 21 from bottom to top. The pretreatment module 21 inhales external cold air, and the external cold air performs a first-level cooling on the hot air at the pretreatment module 21; the hot air discharged from the pretreatment module 21 and the sub-cold air enter the condensation heat exchange module Module 22, and the condensation heat exchange module 22 inhales external cold air, and the secondary cold air and external cold air at the condensation heat exchange module 22 perform secondary cooling on the hot air. During the primary cooling and secondary cooling processes, the cold air does not come into direct contact with the hot air. Finally, the external cold air, secondary cold air, and hot air processed by the condensation heat exchange module 22 are fully mixed above it, and the hot air is cooled in the third stage. The water cutting system 3 captures and intercepts the moisture and tiny particles in the mixed gas, and dissolves harmful substances at the same time. The qualified mixed gas is discharged from the gas output port 100 at the top of the main body 1. This device uses gas-phase three-stage heat exchange to treat flue gas and performs multi-gradient cooling on the flue gas, which can ensure that the moisture in the flue gas is completely removed, avoid the impact of sudden temperature drops on the device, and extend the service life of the device. At the same time, it is convenient to accurately control the temperature of the flue gas.

[0058] Example 2:

[0059] Combine Figure 1 and Figure 4 As shown, a flue gas decolorization method is applied to the flue gas decolorization device with multi-stage condensation phase change in Example 1. The method includes the following steps:

[0060] S1, chimney 4 allows hot air to enter from the lower part of the main body 1.

[0061] S2. Hot air enters the pretreatment module 21 from the first hot air inlet 211 from bottom to top and is discharged from the first hot air outlet 212; external cold air enters the pretreatment module 21 from the first cold air inlet 213 and is discharged from the first cold air outlet 214; in the pretreatment module 21, the air entering from the outside performs a first-level cooling on the hot air and does not come into contact with the hot air.

[0062] S3. The hot air discharged from the first hot air outlet 212 enters the condensing heat exchange module 22 from the second hot air inlet 221 and is discharged from the second hot air outlet 222; the sub-cold air discharged from the first cold air outlet 214 enters the condensing heat exchange module 22 from the second cold air inlet 223 and is discharged from the second cold air outlet 224; the external cold air enters the condensing heat exchange module 22 from the third cold air inlet 225 and is discharged from the third cold air outlet 226; the sub-cold air and the external cold air perform secondary cooling on the hot air in the condensing heat exchange module 22, and neither of them comes into contact with the hot air in the condensing heat exchange module 22.

[0063] S4. The hot air output from the second hot air outlet 222, the sub-cold air discharged from the second cold air outlet 224, and the cold air discharged from the third cold air outlet 226 are mixed to cool the hot air; the water cutting system 3 intercepts the moisture in the mixed air.

[0064] S5. The exhaust module 11 draws the mixed gas to the gas outlet 100 at the top of the main body 1 for discharge.

[0065] During the flue gas decolorization process, the hot gas temperature is reduced in multiple gradients through multi-stage condensation phase transitions. Each stage cools the hot gas to near its dew point, but without completely condensing all the moisture. This helps reduce heat loss when heat recovery is needed. A single sudden cooling step can also cause the flue gas temperature to drop rapidly below the acid dew point, potentially corroding equipment. The hot gas does not come into direct contact with the cold gas during the primary and secondary heat exchange processes. Instead, after passing through the condensation heat exchange module 22, the three gases at different temperatures come into direct contact and mix, ensuring uniform mixing and preventing localized overcooling or overheating.

Claims

1. A flue gas decolorization device with multi-stage condensation phase change, which can decolorize the hot gas discharged from the chimney, characterized in that: include: A main body, a water collecting structure is provided at the bottom of the main body, and the chimney can be connected to the main body from the bottom of the main body to pass the hot air in the chimney into the main body; a gas output port is provided at the top of the main body, and an exhaust module is provided near the gas output port; A multi-stage condensation phase change system and a water cutting system are arranged in sequence from bottom to top, wherein the multi-stage condensation phase change system includes a pretreatment module and a condensation heat exchange module; The pre-processing module is provided with a first hot gas inlet, a first hot gas outlet, a first cold gas inlet and a first cold gas outlet. The hot gas discharged from the chimney into the main body can enter the pre-processing module from the first hot gas inlet and be discharged from the first hot gas outlet. External cold air can enter the pre-processing module from the first cold air inlet and be discharged from the first cold air outlet; The outside cold air entering the pre-processing module performs a first-stage cooling on the hot air, and the cold air entering the pre-processing module does not come into contact with the hot air; The condensing heat exchange module is arranged above the pretreatment module, and is provided with a second hot air inlet, a second hot air outlet, a second cold air inlet, a second cold air outlet, a third cold air inlet and a third cold air outlet. The hot air discharged from the first hot air outlet after passing through the pretreatment module can enter the condensing heat exchange module from the second hot air inlet and be discharged from the second hot air outlet; the sub-cold air discharged from the first cold air outlet can enter the condensing heat exchange module from the second cold air inlet and be discharged from the second cold air outlet. External cold air can enter the condensing heat exchange module from the third cold air inlet and be discharged from the third cold air outlet; The secondary cold air and the external cold air entering the condensing heat exchange module perform secondary cooling on the hot air, and neither of them comes into contact with the hot air in the condensing heat exchange module; The sub-cold air discharged from the second cold air inlet of the condensing heat exchange module and the cold air discharged from the third cold air outlet of the condensing heat exchange module are mixed with the hot air discharged from the second hot air outlet of the condensing heat exchange module above the condensing heat exchange module, and the hot air is cooled in three stages. The water cutting system can intercept the moisture contained in the mixed gas, and the intercepted moisture is downwardly collected into the water collecting structure; the exhaust module can draw the mixed gas upward to the gas output port for discharge; wherein the temperature of the hot air discharged from the second hot air outlet is greater than the temperature of the sub-cold air discharged from the second cold air outlet; and the temperature of the sub-cold air discharged from the second cold air outlet is greater than the temperature of the cold air discharged from the third cold air outlet; The pre-processing module is provided with a first air flow channel and a second air flow channel spaced apart from each other, one of the first air flow channel and the second air flow channel is for circulation of external cold air, and the other of the first air flow channel is for circulation of hot air exhausted from the chimney; The condensing heat exchange module is provided with a third air flow channel, a fourth air flow channel and a fifth air flow channel which are spaced apart from each other, wherein one of the third air flow channel, the fourth air flow channel and the fifth air flow channel is for circulating outside cold air, one is for circulating sub-cold air and one is for circulating hot air; The direction of the second cold air outlet is perpendicular to the direction of the second hot air outlet, and the direction of the third cold air outlet is perpendicular to the direction of the second hot air outlet; The condensing heat exchange module includes multiple groups of condensing heat exchangers, and each group of condensing heat exchangers is evenly distributed on the main body after being rotated 45 degrees counterclockwise.

2. The flue gas whitening device with multi-stage condensation phase change according to claim 1 is characterized in that: The pre-processing module is provided with a cooling fan, which is located at the first cold air inlet and can draw external cold air into the pre-processing module.

3. The flue gas whitening device with multi-stage condensation phase change according to claim 1 is characterized in that: The water cutting system includes a water cutting device, and the water cutting device is provided with multiple layers of corrugated blades inside; the water cutting device gradually protrudes downward from the end to the center; The exhaust module is a fan, and when the fan rotates, negative pressure is formed below the fan, and the mixed gas is drawn to the gas output port for discharge.

4. The flue gas whitening device with multi-stage condensation phase change according to claim 1 is characterized in that: The water collecting structure is arranged in a conical shape, and its cross-sectional area decreases from top to bottom; a drainage pipe is provided on the outer wall of the water collecting structure, and the water collected by the water collecting structure can be discharged through the drainage pipe.

5. The flue gas whitening device with multi-stage condensation phase change according to claim 1 is characterized in that: The chimney is provided with a hot air outlet near its top, and a water retaining cover is provided on the top of the chimney to shield the hot air outlet. The water retaining cover is tapered, and its cross-sectional area increases from top to bottom. The water falling onto the water retaining cover can be guided by the water retaining cover to the water collecting structure.

6. A flue gas decolorization method, applied to the flue gas decolorization device with multi-stage condensation phase change according to any one of claims 1 to 5, characterized in that: The method comprises the steps of: S1, chimney to introduce hot air from the lower part of the main body; S2. Hot air enters the pretreatment module from the bottom to the top through the first hot air inlet and is discharged from the first hot air outlet; External cold air enters the pre-processing module from the first cold air inlet and is discharged from the first cold air outlet; In the pre-processing module, the air entering from the outside performs a first-stage cooling on the hot gas without coming into contact with the hot gas; S3, the hot air discharged from the first hot air outlet enters the condensing heat exchange module through the second hot air inlet and is discharged from the second hot air outlet; the sub-cooled air discharged from the first cold air outlet enters the condensing heat exchange module through the second cold air inlet and is discharged from the second cold air outlet; The outside cold air enters the condensing heat exchange module from the third cold air inlet and is discharged from the third cold air outlet; the secondary cold air and the outside cold air perform secondary cooling on the hot air in the condensing heat exchange module, and neither of them comes into contact with the hot air in the condensing heat exchange module; S4, the hot air output from the second hot air outlet, the sub-cooled air discharged from the second cold air outlet, and the cold air discharged from the third cold air outlet are mixed to cool the hot air; the water cutting system intercepts moisture in the mixed air; S5. The exhaust module draws the mixed gas to the gas outlet at the top of the main body for discharge.

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