Method and device for eliminating white smoke from wet desulfurization flue gas

Abstract

The application discloses a method and device for eliminating white smoke in wet desulfurization flue gas, which mixes hot air with reheated flue gas to eliminate white smoke in the flue gas, collects various temperature and humidity data, and finally calculates the critical heating temperature T of the hot air required for eliminating white smoke in the flue gas HCT , and then adjusts the amount of heat medium of the air heater in real time until the temperature T of the hot air is equal to the critical heating temperature T ah of the hot air HCT , and then the flue gas is discharged. The application can heat the flue gas after wet desulfurization by the intermediate wall heating, mix the flue gas with hot air, determine the critical heating temperature of the hot air for eliminating white smoke in the flue gas in real time, adjust the amount of heat medium in real time to control the temperature of the hot air, automatically control the amount of heat medium for mixed heating and eliminating white smoke, and thus eliminate white smoke and avoid unnecessary energy consumption of the device caused by the lack of theoretical basis for adjusting the temperature of the discharged flue gas by the operator.

Description

Technical Field

[0001] This invention relates to the field of flue gas emission control technology, and in particular to a method and apparatus for eliminating white smoke in wet desulfurization flue gas. Background Technology

[0002] Production processes in energy, petrochemical, metallurgical, and chemical industries generate large amounts of flue gas, which contains significant amounts of SO2 and NO. X Hazardous substances such as dust (particulate matter) cause a series of environmental problems, such as smog, acid rain, and the greenhouse effect, resulting in serious pollution of the ecological environment. Currently, the environmental protection field generally adopts wet desulfurization technology in the process of flue gas desulfurization. In this process, SO2 in the flue gas is washed away or absorbed by spraying alkaline solution in the desulfurization absorption tower. The saturated wet flue gas after wet desulfurization is discharged from the chimney and comes into contact with the cooler ambient air. During the cooling process of the flue gas, water vapor in the flue gas condenses and precipitates out. The condensed water droplets refract and scatter light, forming a white plume.

[0003] Currently, there are three main methods for eliminating white smoke from flue gas: direct heating of flue gas, direct condensation of flue gas, and condensation followed by heating of flue gas. There are two main methods for flue gas heating: one is indirect heating, where the flue gas and the heating medium are separated by a solid wall and do not mix. Heat exchange occurs through the wall, such as GGH (flue gas-to-flue gas reheater) and MGGH (heat medium-type flue gas-to-flue gas reheater). However, due to the presence of dust, aerosols, SO3 droplets, and other components in the flue gas, the resistance of indirect heating gradually increases during operation, and scaling, corrosion, and blockage can occur, causing the unit to shut down for maintenance and affecting its long-term operation. The other method is mixed heating, where hot clean gas is mixed with the purified flue gas after desulfurization and then discharged into the atmosphere. This can heat the flue gas to the required temperature. Hot clean gas includes hot air, hot secondary air, and hot flue gas. The mixing location between the hot clean gas and the flue gas is between the flue gas desulfurization unit and the chimney, thus avoiding the problems of indirect heating and leading to its widespread application.

[0004] For "hybrid heating to eliminate white smoke" devices, the critical heating temperature of the hot cleaning gas is closely related to environmental conditions. Lower ambient temperatures and higher humidity result in a higher critical heating temperature of the hot cleaning gas required to eliminate white smoke from wet desulfurization flue gas, and vice versa. In actual operation, the critical heating temperature of the hot cleaning gas is generally set according to the design temperature. Although the critical heating temperature can be appropriately lowered under favorable weather conditions (high ambient temperature, low humidity), operators often lack a theoretical basis for adjusting this temperature, leading to haphazard adjustments. This can result in white smoke appearing when the heating temperature is too low, or excessive energy consumption when the heating temperature is too high. Furthermore, using only "hybrid heating" requires a large volume of hot cleaning gas, necessitating a large footprint for the fans and heaters.

[0005] Therefore, there is an urgent need for a wet desulfurization flue gas white smoke elimination method and device. By combining "indirect heating" and "hybrid heating", the critical heating temperature of the hot air to eliminate white smoke can be determined in real time and the amount of heat medium can be adjusted in real time to control the hot air temperature. This enables automatic control of the heat medium usage for hybrid heating white smoke elimination, achieving the elimination of white smoke plumes with minimal energy consumption, thereby reducing the energy consumption of the device. It also avoids the scaling problem of using "indirect heating" alone and the large footprint of the fans and heaters of using "hybrid heating" alone.

[0006] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to provide a method and apparatus for eliminating white smoke from wet desulfurization flue gas. The method involves mixing the wet desulfurization flue gas after indirect heat exchange with hot air to eliminate white smoke. The critical heating temperature of the hot air for eliminating white smoke can be determined in real time, and the amount of heat transfer medium can be adjusted in real time to control the temperature of the hot air. This achieves automatic control of the amount of heat transfer medium used for mixed heating to eliminate white smoke, thereby eliminating white smoke while avoiding unnecessary energy consumption of the device due to the lack of theoretical basis for operators to adjust the exhaust flue gas temperature.

[0008] To achieve the above objectives, according to a first aspect of the present invention, the present invention provides a method for eliminating white smoke from wet desulfurization flue gas, which eliminates white smoke by mixing hot air with wet desulfurization flue gas heated by a partition wall, comprising the following steps: A. Collecting the atmospheric temperature T at the corresponding height of the exhaust outlet of the wet desulfurization chimney. e and atmospheric relative humidity Data; collecting air temperature T at the fan inlet. a and relative humidity of air Data; B, via atmospheric temperature T e and atmospheric relative humidity air temperature T a and relative humidity of air Atmospheric moisture content ω was calculated. e and air humidity ω a C. Collect the flue gas temperature T of the saturated wet flue gas after wet desulfurization. G And the moisture content ω of the flue gas was calculated. G D. Collect the dry air flow rate F at the fan outlet. a The dry flue gas flow rate F after wet desulfurization and reheating G Combined with air humidity ω a and the moisture content of flue gas ω G Calculate the moisture content ω of the flue gas and air mixture. mix E. The temperature T of the flue gas after reheating. GH ; Utilizing the moisture content ω of the mixed gas mix Calculate the temperature at the intersection T mix According to the temperature T at the intersection point mix Moisture content ω of mixed gas mix Temperature T of flue gas after reheating GH Moisture content in flue gas ω G and atmospheric moisture content ω e Calculate the critical heating temperature T of hot air required for flue gas to eliminate white smoke. HCT F. Adjust the amount of heat medium used in the air heater in real time until the hot air temperature T is reached. ah Critical heating temperature T of hot air HCT When the values ​​are equal, the flue gas is discharged.

[0009] Furthermore, in the above technical solution, the atmospheric moisture content ω in step B... e air humidity ω a and the moisture content ω of the flue gas in step C. G The calculation is performed in the following way:

[0010]

[0011] Among them, P s The partial pressure of water vapor in saturated air is the pressure of water vapor when the relative humidity of the gas is 100%, and the unit is Pa; the unit of moisture content is g / kg dry air.

[0012] The moisture content ω of the mixed gas in step D mix The calculation is performed in the following way:

[0013]

[0014] The intersection temperature T in step E mixThe calculation is performed in the following way:

[0015]

[0016] The critical heating temperature T of the hot air in step E HCT The calculation is performed in the following way:

[0017]

[0018] Furthermore, in the above technical solution, when the flue gas contains droplets in a supersaturated state, the critical heating temperature T of the hot air is controlled by the droplet content A. HCT The calculation formula (4) is modified as follows:

[0019]

[0020] Where A is the droplet content in the flue gas after wet desulfurization and before entering the flue gas reheater, in g / kg dry flue gas.

[0021] Furthermore, in the above technical solution, the droplet content A can be comprehensively defined by the demister structure factor, flue gas velocity factor, demister pressure drop factor, and demister flushing factor.

[0022] Furthermore, in the above technical solution, when the temperature measuring point of the hot air is at a certain distance from the mixing point of the reheated flue gas and the hot air, and / or when the mixing point of the reheated flue gas and the hot air is at a certain distance from the chimney outlet, the critical heating temperature T of the hot air is determined by the temperature deviation σ. HCT The calculation formula (5) is modified as follows:

[0023]

[0024] Where σ is the temperature deviation, specifically defined as -5℃ to 5℃.

[0025] Furthermore, in the above technical solution, when there is a certain distance between the reheated flue gas and hot air mixing point and the chimney outlet, the temperature deviation σ can be comprehensively defined by the heat transfer area factor, chimney structure factor, flue gas and atmosphere temperature difference factor, flue gas flow rate factor, and environmental wind force level factor.

[0026] Furthermore, in the above technical solution, when the critical heating temperature T of the hot air... HCT ≤Air temperature at the fan inlet T a When this happens, the heat transfer medium consumption of the heater should be adjusted to 0 t / h.

[0027] Furthermore, in the above technical solution, the flue gas after wet desulfurization enters the flue gas reheater for heating before being mixed with hot air, and the temperature rise of the flue gas after passing through the flue gas reheater is 2 to 10°C.

[0028] Furthermore, in the above technical solution, the method for eliminating white smoke from flue gas involves pressurizing air with a fan, heating the pressurized air by connecting a heat transfer medium water heater and a steam heater in series, mixing the heated air with the flue gas after wet desulfurization and reheating, and then discharging the mixed heated flue gas into the atmosphere through a chimney.

[0029] To achieve the above objectives, according to a second aspect of the present invention, a wet desulfurization flue gas white smoke elimination device is provided. The wet desulfurization tower and the chimney are integrated or separate, and the white smoke elimination is achieved by mixing hot air with the reheated flue gas after wet desulfurization. The device includes an atmospheric and air data acquisition unit for acquiring the atmospheric temperature T at a corresponding height at the exhaust outlet of the wet desulfurization chimney. e and atmospheric relative humidity Data; collecting air temperature T at the fan inlet. a and relative humidity of air Data; atmospheric and air humidity calculation unit, which uses atmospheric temperature T e and atmospheric relative humidity air temperature T a and relative humidity of air Atmospheric moisture content ω was calculated. e and air humidity ω a The flue gas temperature acquisition and moisture content calculation unit is used to acquire the flue gas temperature T of the saturated wet flue gas after wet desulfurization. G And the moisture content ω of the flue gas was calculated. G ; Flow acquisition and mixed gas moisture content calculation unit, which is used to collect the dry air flow rate F at the fan outlet. a The dry flue gas flow rate F after wet desulfurization and reheating G Combined with air humidity ω a and the moisture content of flue gas ω G Calculate the moisture content ω of the flue gas and air mixture. mix The hot air critical heating temperature calculation unit collects the temperature T of the reheated flue gas. GH ; Utilizing the moisture content ω of the mixed gas mix Calculate the temperature at the intersection T mix According to the temperature T at the intersection point mix Moisture content ω of mixed gas mix Temperature T of flue gas after reheating GH Moisture content in flue gas ω G and atmospheric moisture content ω e Calculate the critical heating temperature T of hot air required for flue gas to eliminate white smoke. HCT The flue gas exhaust control unit is used to adjust the amount of heat medium used in the air heater in real time until the hot air temperature T is reached. ah Critical heating temperature T of hot air HCTWhen the values ​​are equal, the flue gas is discharged.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1) The flue gas white smoke elimination method and system of the present invention automatically calculates the critical heating temperature T of the hot air required for mixed heating white smoke elimination based on weather conditions such as ambient temperature and humidity, as well as the flue gas temperature before and after the flue gas reheater. HCT The temperature T of the hot air is adjusted by regulating the amount of heat transfer medium used in the device. ah Equal to the calculated critical heating temperature of hot air, it can effectively realize the automatic control of the heat medium usage of the device, avoid blind adjustment by operators, avoid situations where white smoke appears in the exhaust gas due to excessively low hot air heating temperature, or excessive energy consumption of the device due to excessively high hot air heating temperature, and can also effectively reduce the workload of operators.

[0032] 2) Wet desulfurization flue gas is saturated wet flue gas, which inevitably contains droplets. When hot cleaning gas is mixed with saturated wet flue gas for heating, insufficient mixing distance or too short mixing time (especially when the wet desulfurization tower and chimney are integrated) can easily cause droplets to not completely vaporize when the flue gas exits the chimney. Although the temperature of the flue gas exiting the chimney is high, a small amount of droplets are still present in some areas, resulting in a small amount of white smoke in the exhaust gas. This invention uses a flue gas reheater (i.e., indirect heating) to heat the flue gas after wet desulfurization, which can heat all the droplets contained in the wet desulfurization flue gas into gas. The flue gas after passing through the flue gas reheater does not contain liquid droplets, thus avoiding the appearance of a small amount of white smoke in the exhaust gas due to the presence of droplets in some areas.

[0033] 3) This invention uses a flue gas reheater to heat the flue gas after wet desulfurization. The droplets in the flue gas are completely heated and evaporated. The soluble salts such as sulfates and sulfites, dust, desulfurizing agent particles, and sulfuric acid mist contained in the droplets will adhere to the heat exchange tubes. Therefore, this method can further purify the flue gas after wet desulfurization. After passing through the flue gas reheater, the content of filterable particulate matter such as dust, soluble salts, and condensable particulate matter such as sulfuric acid mist in the flue gas will be reduced, thus achieving deep purification of the flue gas.

[0034] 4) This invention uses low-temperature hot water with a small temperature difference between the flue gas and the air temperature as a heat source to reduce the temperature difference between the inside and outside of the heat exchange tubes, thereby reducing the scaling rate of the heat exchange tubes. The temperature rise of the flue gas after passing through the flue gas reheater is only 2-10℃, so the required heat exchange area is smaller. Compared with the direct heating of the flue gas by tens of degrees through the flue gas reheater, the scaling rate of the flue gas reheater is significantly reduced. Combined with heat exchanger equipment (adding soot blowers or online cleaning, increasing the spacing between heat exchange tubes, etc.), it can effectively meet the requirements for stable operation during the equipment maintenance cycle. The wet desulfurization flue gas is heated slightly before being mixed with hot clean gas (air) for heating to eliminate white smoke, effectively avoiding the problems of increased heater resistance, scaling, and blockage that exist in the existing wet desulfurization flue gas indirect heating system for eliminating white smoke.

[0035] 5) The present invention uses a flue gas reheater to heat the flue gas from wet desulfurization. After the flue gas flows through the subsequent flue / chimney, it will not condense and form water, thus preventing corrosion of the subsequent flue / chimney. This can effectively increase the maintenance cycle of the flue / chimney and reduce the material requirements of the flue / chimney, thereby reducing investment costs.

[0036] 6) Since the flue gas may contain mist droplets, the flue gas is in a supersaturated state. The flue gas state point should be located above the saturated humid air line. Therefore, there will be some error when calculating the critical heating temperature for whitening. This invention uses the mist droplet content A to correct the calculation formula for the critical heating temperature of hot air, so that the calculation results are more accurate and the whitening method of this invention is more consistent with the actual situation, thus improving the accuracy and reliability of whitening.

[0037] 7) Due to the large measuring range of the measuring instruments themselves, and imperfections in their mechanical performance or electrical structure, there is often a certain measurement error. Improper instrument installation or significant interference in the operating environment can also cause errors, and may even lead to instrument malfunction or failure. Furthermore, because there is a certain distance between the temperature measuring point of the hot air and the mixing point of the flue gas and hot air, especially between the mixing point and the chimney outlet (and this distance cannot be adjusted), the temperature of the flue gas decreases after passing through this distance. Therefore, there is a certain deviation between the actual temperature of the hot air required for eliminating white smoke and the temperature at the measuring point. To address these issues, this invention uses a temperature deviation σ to correct the calculation formula for the critical heating temperature of the hot air. The value of the temperature deviation σ is determined after adjustments based on actual field conditions, making the calculation formula for the critical heating temperature of the hot air more accurate. This makes the white smoke elimination method of this invention more consistent with actual conditions, improving the accuracy and reliability of the invention.

[0038] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it according to the contents of the specification, and to make the above and other objects, technical features and advantages of the present invention easier to understand, one or more preferred embodiments are listed below and described in detail with reference to the accompanying drawings. Attached Figure Description

[0039] Figure 1 This is a schematic diagram illustrating the principle of the wet desulfurization flue gas white smoke elimination method of the present invention.

[0040] Figure 2 This is a schematic diagram illustrating the principle of the present invention's method for eliminating whitening by mixing flue gas after wet desulfurization and reheating with hot air through heating.

[0041] Figure 3 This is a schematic flowchart of the wet desulfurization flue gas white smoke elimination method of the present invention.

[0042] Figure 4 This is a schematic diagram of one embodiment of the wet desulfurization flue gas white smoke elimination device of the present invention.

[0043] Figure 5 This is a schematic diagram of another embodiment of the wet desulfurization flue gas white smoke elimination device of the present invention.

[0044] Explanation of key figure labels:

[0045] 100-Wet desulfurization tower; 101-Demister; 200-Chimney; 201-Second flue gas temperature and humidity detector; 300-Steam heater; 301-Hot air temperature detector; 302-Steam; 303-Steam flow regulating valve; 400-Fan; 401-Air monitoring unit; 402-Air flow detector; 500-Integrated desulfurization and chimney tower; 501-Dust removal and desulfurization section; 502-Demister section; 503-First flue gas temperature detector; 504-Second flue gas temperature detector. 505 - Flue gas flow meter; 506 - First atmospheric temperature and humidity meter; 507 - First flue gas reheater; 508 - Second flue gas temperature meter; 509 - First heat medium; 600 - Second flue gas reheater; 601 - Second heat medium; 602 - Third flue gas temperature meter; 603 - Second flue gas flow meter; 604 - Fourth flue gas temperature meter; 700 - Heat medium water heater; 701 - Heat medium water; 702 - Heat medium water flow regulating valve. Detailed Implementation

[0046] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0047] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0048] In this document, for ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” “above,” “upper,” etc., are used to describe the relationship of one element or feature to another element or feature in the accompanying drawings. It should be understood that spatial relative terms are intended to encompass different orientations of an object in use or operation, in addition to those depicted in the figures. For example, if an object in the figure is flipped, an element described as “below” or “under” another element or feature would be oriented “above” that element or feature. Thus, the exemplary term “below” can encompass both the downward and upward orientations. An object may also have other orientations (rotated 90 degrees or other orientations), and the spatial relative terms used herein should be interpreted accordingly.

[0049] In this document, the terms "first," "second," etc., are used to distinguish two different elements or parts, and are not used to define specific positions or relative relationships. In other words, in some embodiments, the terms "first," "second," etc., can also be used interchangeably.

[0050] refer to Figure 1 There are three main methods for eliminating white smoke in flue gas: direct heating of flue gas, direct condensation of flue gas, and condensation followed by heating of flue gas. Figure 1 The saturation curve diagram shows that after the flue gas passes through the wet desulfurization tower, it forms low-temperature saturated wet flue gas, and its state is as follows: Figure 1 Point A is shown above, and the ambient atmospheric conditions are shown at point C. The intersection of the straight line between points A and C with the saturation curve will produce white smoke. Further, as shown... Figure 1 As shown, the direct flue gas heating method (ABC) involves heating the desulfurized and purified flue gas, changing its state point from A to B, and reducing its relative humidity. The line segment BC is tangent to the saturation curve at point F. This means that the flue gas will not become saturated during the process of changing from state point B to ambient air state point C, thus preventing the formation of "white smoke." Further details are provided below. Figure 1As shown, the flue gas condensation followed by heating (ADEC) method involves: cooling the exhaust gas, changing it from state point A to state point D, during which condensate water is released, reducing the absolute humidity and water vapor content; then heating the condensed flue gas, changing it from state point D to state point E, further reducing the relative humidity and eliminating the white plume; the line segment EC is tangent to the saturation curve at point F, meaning that the flue gas will not reach saturation or form "white smoke" during the transition from state point E to ambient air state point C. Further details are provided... Figure 1 As shown, Direct Flue Gas Condensation (ADFC) cools the clean flue gas, changing it from state point A to state point F, with the temperature approaching the ambient temperature. This advances the condensation process of the wet flue gas outside the chimney to occur before the chimney, allowing the flue gas to directly merge with the environment after entering the atmosphere, thus preventing the formation of "white smoke".

[0051] This invention employs a hybrid heating method to eliminate white smoke. Specifically, the flue gas after wet desulfurization is first subjected to indirect wall heating to achieve a low temperature rise. Then, the reheated flue gas is mixed with hot air to eliminate white smoke. The principle of this hybrid heating method for eliminating white smoke is as follows: (Refer to...) Figure 2 As shown, the state point A of the flue gas after wet desulfurization is located on the water vapor saturation curve (saturated humid air line). After isohumid heating (using a partitioned heating method), the state point becomes D (when the flue gas contains droplets, the state point becomes A', which is located above the water vapor saturation curve; after isohumid heating, the state point becomes D'). The moisture content of the gas after mixing hot air and flue gas decreases to ω = ω mix Draw a tangent line from the environmental state point E to the water vapor saturation curve (the point of tangency is T). The extension of ET intersects ω = ω mix They intersect at point B, and the temperature at point B is T. mix This refers to the critical mixing temperature at which the mixed gas can eliminate white smoke; EC is the isohyet heating line for air, where the air's moisture content remains constant and its temperature increases after passing through the heater. The extensions of EC and DB intersect at point C, then the temperature T at point C is... HCT This is the critical heating temperature of hot air, which is the temperature of the air after passing through the heater that is greater than or equal to T. HCT This can eliminate white smoke from wet desulfurization (when the flue gas contains droplets, the extensions of EC and D'B intersect at point C', then the temperature at point C' is the critical heating temperature T of the hot air). HCT .

[0052] The method for eliminating white smoke in wet desulfurization flue gas of the present invention involves mixing hot air with wet desulfurization flue gas heated by a partition wall to eliminate white smoke, and includes the following steps:

[0053] Step S101: Collect the atmospheric temperature T at the corresponding height of the exhaust outlet of the wet desulfurization chimney. e and atmospheric relative humidity Data; collecting air temperature T at the fan inlet. a and relative humidity of air data.

[0054] Specifically, the present invention can be achieved through... Figure 4 The first large temperature and humidity detector 506 shown is... Figure 5 The second large air temperature and humidity detector 201 shown collects the atmospheric temperature T at the corresponding height of the chimney exhaust outlet. e and atmospheric relative humidity Data. The height of the chimneys used for wet desulfurization flue gas discharge varies across different industries, generally exceeding 50m, with some cement chimneys even surpassing 200m in height. Temperature and humidity at high altitudes differ from those at ground level. For every 100m increase in altitude, the air temperature decreases by 0.5–1.5℃, and humidity also varies. This invention installs temperature and humidity detectors near the chimney discharge outlet or on structures at the same height to measure the atmospheric temperature T at the location where the flue gas is emitted. e and atmospheric relative humidity Therefore, compared with ground-based testing, the critical heating temperature of hot air obtained by this invention is more accurate and has less error.

[0055] Furthermore, the present invention can be achieved through... Figure 4 or Figure 5 The air monitoring unit 401 shown collects the air temperature T at the fan inlet. a and relative humidity of air data.

[0056] Step S102, using the atmospheric temperature T collected in step S101 e and atmospheric relative humidity air temperature T a and relative humidity of air Atmospheric moisture content ω was calculated. e and air humidity ω a .

[0057] Specifically, atmospheric moisture content ω e and air humidity ω a (Unit: g / kg dry air) can be calculated as follows:

[0058]

[0059] Among them, P s P represents the partial pressure of saturated water vapor, which is the partial pressure of water vapor when the relative humidity of the gas is 100%, and is expressed in Pa. sThe calculation can be performed using the Goff-Gratch formula (see the formula below); T is the temperature, in K.

[0060]

[0061] In this formula,

[0062] C1=-7.90298, C2=5.028081, C3=1.3816×10 -7 C4 = 8.1328 × 10 -3 ;

[0063] C5=lg1013.246, a=373.16.

[0064] Step S103: Collect the flue gas temperature T of the saturated wet flue gas after wet desulfurization. G (i.e., the flue gas temperature before entering the flue gas reheater) and calculate the flue gas moisture content ω. G .

[0065] Specifically, through Figure 4 The second flue gas temperature detector 508 shown collects the flue gas temperature T after wet desulfurization in the "integrated tower". G Or through Figure 5 The fourth flue gas temperature detector 604 shown collects the flue gas temperature T after wet desulfurization in the "split tower". G Further analysis was conducted using the collected flue gas temperature T. G and (The flue gas after wet desulfurization is saturated wet flue gas) Substitute into the aforementioned formula (1) and still calculate the flue gas moisture content ω using the aforementioned Goff-Grech formula. G .

[0066] Step S104: Collect the dry air flow rate F at the outlet of the fan. a The dry flue gas flow rate F after wet desulfurization and reheating G Combined with the aforementioned air humidity ω a and the moisture content ω of the flue gas G Calculate the moisture content ω of the flue gas and air mixture. mix .

[0067] Specifically, the present invention through Figure 4 or Figure 5 The air flow meter 402 shown collects the dry air flow F at the outlet of the fan 400. a ;pass Figure 4 The first flue gas flow meter 504 shown collects the dry flue gas flow rate F after wet desulfurization in the "integrated tower". G ,pass Figure 5The second flue gas flow meter 603 shown collects the dry flue gas flow rate F after wet desulfurization in the "split tower". G .

[0068] Combined with the air humidity ω calculated in step S102 above a and the moisture content ω of the flue gas calculated in step S103 G The moisture content ω of the flue gas-air mixture is calculated using the following method. mix :

[0069]

[0070] Step S105, passing the atmospheric environment state point (T) e ω e Draw a tangent to the water vapor saturation curve (reference) Figure 2 ), the tangent point is (T) tan ω tan ),

[0071]

[0072]

[0073] in,

[0074] Step S106: Collect the temperature T of the reheated flue gas. GH The moisture content ω of the mixed gas obtained in step S104 is used. mix Calculate the temperature at the intersection T mix According to the temperature T at the intersection point mix Moisture content ω of mixed gas mix and the aforementioned flue gas temperature T G The aforementioned moisture content ω in flue gas G Atmospheric moisture content ω e Calculate the critical heating temperature T of hot air required for flue gas to eliminate white smoke. HCT .

[0075] Specifically, the temperature T of the reheated flue gas GH It is possible Figure 4 The first flue gas temperature detector 503 or Figure 5 The third flue gas temperature detector 602 collects the data.

[0076] Furthermore, the intersection temperature T mix The calculation is performed in the following way:

[0077]

[0078] Hot air critical heating temperature T HCTThe calculation is performed in the following way:

[0079]

[0080] Further research by the inventors revealed that existing wet desulfurization demisters are highly efficient at removing larger droplets (≥30μm), but less efficient at removing smaller droplets. Therefore, droplets are inevitably present in the flue gas after wet desulfurization. When calculating the critical heating temperature of hot air, if the influence of droplets is not considered, and the flue gas after wet desulfurization is treated as saturated wet flue gas, its state point (reference) is assumed to be... Figure 2 Point A in the diagram is located on the saturated humid air line, and the critical heating temperature T of the hot air is... HCT The calculation results may have some deviation. Because the flue gas contains droplets, it is in a supersaturated state, and the flue gas state point should be located above the saturated moist air line (reference). Figure 2 Point A' in the equation (4) is used to calculate the critical heating temperature T of the hot air using only the aforementioned formula (4). HCT There will be some error in the calculation. Therefore, this invention further uses the droplet content A to determine the critical heating temperature T of the hot air. HCT The calculation formula was modified to make the calculation results more accurate.

[0081] The droplet content A is related to many factors. The inventors have found that a more scientific and effective approach is to comprehensively define the droplet content A using factors such as demister structure, flue gas velocity, demister pressure drop, and demister flushing. Specifically: 1) Regarding the demister's structural type, different types such as flat-plate demisters, ridge demisters, cyclone demisters, electrostatic demisters, and tubular demisters result in different demisting efficiencies and droplet contents in the flue gas. 2) Regarding the flue gas velocity, excessively high velocities cause previously removed droplets to be carried away again, leading to secondary carryover, reduced demisting efficiency, and increased droplet content in the flue gas. Conversely, insufficient centrifugal force results in inadequate droplet removal, also increasing droplet content. 3) Regarding the demister pressure drop (i.e., the degree of fouling), severe fouling reduces the flue gas flow area, increases the pressure drop, lowers demisting efficiency, and increases droplet content in the flue gas. 4) Regarding the pressure, frequency, volume, and coverage of the demister flushing water, reducing these factors will lead to a decrease in demister efficiency and an increase in the mist droplet content in the flue gas.

[0082] Considering the four influencing factors highly correlated with droplet content A, the specific value of droplet content A can be defined based on the actual situation on site. That is, in step S106, preferably but not limitingly, when the flue gas contains droplets in a supersaturated state, the droplet content A is used to determine the critical heating temperature T of the hot air. HCTThe calculation formula (4) is modified as follows:

[0083]

[0084] Where A is the droplet content in the flue gas after wet desulfurization and before entering the flue gas reheater, in g / kg dry flue gas.

[0085] Further research by the inventors revealed that the measuring instruments themselves often exhibit errors due to their large range, imperfect mechanical performance, or flawed electrical structure. Improper instrument installation or significant interference in the operating environment can also cause errors, even leading to instrument malfunction or failure. More importantly, there is a certain distance between the temperature measuring point of the hot air and the mixing point of the flue gas and hot air, and also a certain distance between the mixed flue gas and hot air and the chimney outlet. This distance between the mixing point and the chimney outlet cannot be eliminated by adjusting the equipment structure. The flue gas temperature decreases after passing through this distance, resulting in a deviation between the actual temperature of the flue gas emitted into the atmosphere and the temperature at the measuring point. To address these issues, this invention uses the temperature deviation σ to determine the critical heating temperature T of the hot air required for eliminating white smoke. HCT The calculation formula was further revised, and the value of the temperature deviation σ was determined after adjustments based on the actual site conditions, thereby determining the critical heating temperature T of the hot air. HCT The calculations are more accurate.

[0086] To address the calculation errors caused by the distance between the flue gas and hot air mixing point and the chimney outlet, this invention addresses the temperature deviation σ, which is related to many factors. The inventors have found that a comprehensive definition of the temperature deviation σ using factors such as the heat transfer area factor, chimney structure factor, flue gas-atmosphere temperature difference factor, flue gas velocity factor, and environmental wind force factor is more scientific and effective. Specifically, 1) Regarding the heat transfer area factor, the heat transfer area between the measuring point at the flue gas and hot air mixing point and the chimney outlet, and / or between the chimney and the atmosphere, is related to factors such as the shape and size of the flue and / or chimney, as well as the distance between the measuring point and the chimney outlet. The larger the heat transfer area, the greater the temperature deviation. 2) Regarding chimney construction factors, the material, wall thickness, and material and thickness of the duct and / or chimney between the measuring point at the flue gas and hot air mixing point and the chimney outlet are crucial. A higher thermal conductivity of the duct and / or chimney material, and the material of the lining and / or insulation layer, results in a larger required temperature deviation; a larger wall thickness and a thicker lining and / or insulation layer result in a smaller required temperature deviation. 3) Regarding the temperature difference factor between flue gas and the atmosphere, a larger temperature difference (in winter) results in a larger required temperature deviation; a smaller temperature difference (in summer) results in a smaller required temperature deviation. 4) Regarding the wind force factor in the ambient air, stronger winds facilitate heat dissipation from the flue gas, resulting in a larger required temperature deviation. 5) Regarding the flue gas velocity factor, higher flue gas velocity facilitates heat dissipation from the flue gas, resulting in a larger required temperature deviation.

[0087] Considering the five influencing factors highly correlated with temperature deviation σ, the specific value of temperature deviation σ can be defined based on the actual site conditions. That is, when there is a certain distance between the mixing point of reheated flue gas (i.e., flue gas after indirect heating) and hot air and the chimney exhaust outlet, the temperature deviation σ is used to determine the critical heating temperature T of the hot air. HCT The calculation formula (5) is modified as follows:

[0088]

[0089] Where σ is the temperature deviation, specifically defined as -5℃ to 5℃.

[0090] Step S107: Adjust the heat transfer medium usage of the air heater in real time until the heated air reaches temperature T. ah The critical heating temperature T of the hot air calculated in step S106 HCT When the values ​​are equal, the flue gas is discharged.

[0091] Specifically, such as Figure 4 , 5As shown, this invention introduces pressurized air through a fan 400. The air first enters the heat medium water heater 700 for heating, and then enters the steam heater 300 for further heating. The amount of heat medium used is adjusted by the heat medium water flow regulating valve 702 and the steam flow regulating valve 303 respectively to heat the air. When the hot air temperature detector 301 detects the hot air temperature T... ah The critical heating temperature T of the hot air calculated in step S106 HCT When they are equal, hot air is mixed with wet desulfurization and then reheated (refer to...). Figure 4 , Figure 5 The flue gas is mixed with the exhaust gas to avoid white smoke in the exhaust. Furthermore, if the critical heating temperature T of the hot air... HCT ≤Air temperature T a If so, the heat transfer medium consumption of the heater is adjusted to 0t / h (i.e., no air heating is required).

[0092] This invention eliminates white smoke from flue gas by mixing hot air with reheated flue gas. The flue gas can be reheated flue gas from wet desulfurization in an integrated tower, for example... Figure 4 The integrated desulfurization and desulfurization tower 500 shown comprises, from bottom to top, a dust removal and desulfurization section 501, a demisting section 502, and a chimney section 505. The desulfurized and demisted flue gas enters the first flue gas reheater 507 and undergoes indirect heating via the first heat medium 509. The reheated flue gas mixes with heated hot air at the root of the chimney section 505, and the mixed flue gas is then discharged to eliminate white smoke. The flue gas can also be the reheated flue gas from wet desulfurization in a "split tower," for example... Figure 5 The "split tower" shown includes a wet desulfurization tower 100 and a chimney 200. The wet desulfurization tower 100 is equipped with a demister 101. Before entering the chimney 200, the flue gas after wet desulfurization is first heated by the second heat medium 601 in the second flue gas reheater 600. The reheated flue gas is then mixed with hot air at the root of the chimney 200. The mixed flue gas is then discharged to eliminate white smoke.

[0093] It should be noted that before mixing the flue gas with hot air, the flue gas after wet desulfurization is first subjected to indirect heating. Preferably, but not limitingly, low-temperature hot water with a small temperature difference from the flue gas temperature can be used as a heat source to reduce the temperature difference inside and outside the heat exchange tubes, thereby reducing the scaling rate of the heat exchange tubes. The temperature rise of the flue gas after passing through the flue gas reheater is only 2-10°C, so the required heat exchange area is small. Compared with the direct heating of the flue gas by tens of degrees through the flue gas reheater, the scaling rate of the flue gas reheater is significantly reduced. Combined with heat exchanger equipment (adding soot blowers or online cleaning, increasing the spacing between heat exchange tubes, etc.), it can effectively meet the requirements for stable operation during the equipment maintenance cycle. The wet desulfurization flue gas is heated slightly before being mixed with hot clean gas (air) for white smoke elimination, which can effectively avoid the problems of increased heater resistance, scaling and blockage that exist in the existing wet desulfurization flue gas indirect heater white smoke elimination.

[0094] Example 1

[0095] like Figure 4 As shown, the white smoke elimination device in this embodiment consists of a wet desulfurization tower, an air heater (composed of a hot water heater 700 and a steam heater 300 connected in series), and a fan 400. The wet desulfurization tower is an integrated desulfurization and chimney tower 500, which includes, from bottom to top, a desulfurization section 501, a demister section 502, a first flue gas reheater 507, and a chimney section 505. A second flue gas temperature detector 508 is installed above the demister section 502, and a first flue gas temperature detector 503 and a first flue gas flow detector 504 are installed above the first flue gas reheater 507. A first ambient temperature and humidity detector 506 is installed near the exhaust port of the chimney section 505 of the integrated desulfurization and chimney tower 500. A hot air temperature detector 301 is installed on the hot air outlet pipeline of the steam heater 300; an air monitoring unit 401 is installed at the inlet of the fan 400, and an air flow detector 402 is installed at the outlet of the fan 400.

[0096] The hot air mixing heating system of this invention is used to eliminate white smoke in a certain wet desulfurization process. The relevant design parameters are as follows: the volume of the desulfurized flue gas is 180,000 Nm³. 3 / h (wet basis), the temperature of the flue gas after desulfurization is 48℃. Low-temperature hot water at 85℃ is used to heat the flue gas to 55℃. The design requires the elimination of white smoke under ambient temperature of 10℃ and relative humidity of 50%. The fan air volume is 80000Nm³ / h. 3 / h (wet basis), the air is heated by a series connection of a water heater 700 and a steam heater 300. The heat medium is a low-temperature water heater 701 at 85℃ and a steam heater 302 at 1.0MPa and 250℃. The designed temperature of the heated air is 95.6℃. To meet the design requirements, 60t / h of low-temperature hot water and 1.7t / h of steam are required.

[0097] The automatic control process for the dosage of heat transfer fluid 701 and steam 302 in the wet desulfurization flue gas white smoke elimination method and apparatus of the present invention is as follows:

[0098] First, the atmospheric temperature T is obtained in real time by the first atmospheric temperature and humidity detector 506 installed below the exhaust outlet of chimney section 505. e 19℃, atmospheric relative humidity The air temperature T is 55%, and the air temperature T is obtained in real time through the air monitoring unit 401 installed at the inlet of the fan 400. a 20℃, relative humidity The dry air flow rate F is 58%, and the dry air flow rate F is obtained in real time through the air flow detector 402 installed at the outlet of the fan 400. a 78938 Nm 3 / h, the desulfurization flue gas temperature T is obtained in real time by the second flue gas temperature detector 508 installed above the demister section 502. G The temperature is 50℃ (2℃ difference from the design value). The flue gas reheat temperature T is obtained in real time by the first flue gas temperature detector 503 and the first flue gas flow detector 504 installed above the first flue gas reheater 507. GH For 55℃ and dry flue gas flow rate F G 158215 Nm 3 / h;

[0099] Secondly, by obtaining the atmospheric temperature T e and atmospheric relative humidity air temperature T a and relative humidity The atmospheric moisture content ω was calculated. e =7.501 g / kg dry air and air moisture content ω a = 8.431 g / kg dry air, obtained by measuring the flue gas temperature T G and The calculated moisture content ω of the flue gas G = 81.216 g / kg dry flue gas;

[0100] Then, by obtaining the dry air flow rate F a and dry flue gas flow rate F G The calculated air humidity ω a and the moisture content of flue gas ω G The moisture content ω of the mixed gas was calculated. mix = 60.325 g / kg dry flue gas;

[0101] Then, passing the atmospheric environmental state point (T) e ω e Draw a tangent line to the water vapor saturation curve, with the point of tangency at (T). tanω tan T is obtained through calculation. tan =26.4℃, further calculation yields the saturated moisture content ω at the tangent point. tan =21.81 g / kg dry flue gas;

[0102] Next, obtain the aforementioned tangent and line ω=ω mix The intersection temperature T mix =57.9℃;

[0103] Next, calculate the critical heating temperature T of the hot air required to eliminate white smoke from the flue gas. HCT =63.8℃;

[0104] Finally, the steam consumption of the steam heater 300 and the hot medium water consumption of the hot medium water heater 700 are adjusted in real time by the steam flow regulating valve 303 and the hot medium water flow regulating valve 702, so that the hot air temperature T is adjusted accordingly. ah The calculated critical heating temperature T of hot air HCT equal.

[0105] At this time, the consumption of low-temperature hot water is 52.8 t / h, which is 7.2 t / h lower than the design value; the consumption of steam is 0 t / h, which is 1.7 t / h lower than the design value. The steam consumption is significantly reduced, and the energy consumption is reduced accordingly.

[0106] Example 2

[0107] like Figure 4 As shown, the wet desulfurization flue gas whitening method and apparatus in this embodiment are the same as those in Embodiment 1. After running for a period of time, a small amount of white smoke was found in the flue gas discharged from the top outlet of chimney 505. After diagnosing the device, it was found that the demisting efficiency of the demister 501 installed in the integrated desulfurization chimney tower 500 had decreased, and the desulfurized flue gas contained a large number of mist droplets. Taking into account the influence factor of mist droplet content A, and after sampling and conversion, the mist droplet content was as high as 1.2 g / kg dry flue gas. The mist droplet content A was compared with T HCT The calculation formula was modified, and after the modification, the white smoke emitted from the chimney 505 disappeared, making the white smoke elimination method of the present invention more consistent with the actual situation and improving the accuracy and reliability of the present invention.

[0108] Example 3

[0109] like Figure 5As shown, the white smoke elimination device in this embodiment consists of a wet desulfurization tower 100, a chimney 200, an air reheater (composed of a steam heater 300 and a hot water heater 700 connected in series), a fan 400, and a second flue gas reheater 600. A demister 101 is installed inside the wet desulfurization tower 100; a second atmospheric temperature and humidity detector 201 is installed below the exhaust outlet of the chimney 200 to monitor atmospheric temperature and relative humidity in real time; a hot air temperature detector 301 is installed on the flue gas outlet pipeline of the steam heater 300; an air monitoring unit 401 is installed at the inlet of the fan 400, and an air flow detector 402 is installed at the outlet of the fan 400; a third flue gas temperature detector 602 and a second flue gas flow detector 603 are installed on the flue after the second flue gas reheater 600.

[0110] A certain wet desulfurization flue gas uses hot air mixing heating to eliminate white smoke. The relevant design parameters are as follows: the flue gas volume after demister 101 for saturated wet desulfurization is 250,000 Nm³. 3 The flue gas temperature is 45℃ (wet basis) and then a second flue gas reheater (600) is used to heat the saturated wet flue gas from the wet desulfurization process to 55℃. The design requires the elimination of white smoke under the conditions of an ambient temperature of 5℃ and an atmospheric relative humidity of 60%. The fan air volume is 150,000 Nm³. 3 / h (wet basis), the heat medium 302 of the steam heater 300 uses steam at 1.0MPa and 250℃, and the heat medium 701 of the heat medium water heater 700 uses low-temperature hot water at 85℃. The design value of the hot air temperature after heating is 83.4℃. To meet the design requirements, 200t / h of low-temperature hot water and 3t / h of steam are required.

[0111] The automatic control of the dosage of heat transfer fluid 701 and steam 302 in the wet desulfurization flue gas white smoke elimination method and system of the present invention is illustrated in the following example:

[0112] First, the atmospheric temperature T is obtained in real time through the second large temperature and humidity detector 201 installed below the exhaust outlet of chimney 200. e 25℃, atmospheric relative humidity The air temperature T is 65% and is obtained in real time through the air monitoring unit 401 installed at the inlet of the fan 400. a 27℃, relative humidity The dry air flow rate F is 67%, and the dry air flow rate F is obtained in real time through the air flow detector 402 installed at the outlet of the fan 400. a 149226 Nm 3 / h, the temperature T of the flue gas after wet desulfurization is monitored in real time by the fourth flue gas temperature detector 604 installed before the second flue gas reheater 600. GThe temperature is 45℃. The temperature T of the reheated flue gas is obtained by the third flue gas temperature detector 602 and the second flue gas flow detector 603 installed after the second flue gas reheater 600. GH For 55℃ and dry flue gas flow rate (F) G The value is 226518 Nm. 3 / h;

[0113] Secondly, by obtaining the atmospheric temperature T e and atmospheric relative humidity air temperature T a and relative humidity The atmospheric moisture content ω was calculated. e =12.893 g / kg dry air and air moisture content ω a =15.009 g / kg dry air, obtained by measuring the flue gas temperature T G and The calculated moisture content ω of the flue gas G = 64.963 g / kg dry flue gas;

[0114] Then, by obtaining the dry air flow rate F a and dry flue gas flow rate F G The calculated air humidity ω a and the moisture content of flue gas ω G The moisture content ω of the mixed gas was calculated. mix = 49.914 g / kg dry flue gas;

[0115] Then, passing the atmospheric environmental state point (T) e ω e Draw a tangent line to the water vapor saturation curve, with the point of tangency at (T). tan ω tan T is obtained through calculation. tan =31.0℃, further calculation yields the saturated moisture content ω at the tangent point. tan =28.77 g / kg dry flue gas;

[0116] Next, obtain the aforementioned tangent and line ω=ω mix The intersection temperature T mix =46.3℃;

[0117] Next, calculate the critical heating temperature T of the hot air required to eliminate white smoke from the flue gas. HCT =24.8℃.

[0118] Finally, at this point, the critical heating temperature of the hot air (T) HCT =24.8℃) < air temperature (T) aIf the temperature is 27℃, then close the steam flow regulating valve 303 of the steam heater 300 and the hot water flow regulating valve 702 of the hot water heater 700.

[0119] At this point, the consumption of both heat transfer medium water and steam is 0 t / h, and the energy consumption is significantly reduced compared to the design value.

[0120] Example 4

[0121] like Figure 5 As shown, the method and apparatus for eliminating white smoke in this embodiment are the same as in Embodiment 3. After one year of operation, a small amount of white smoke was found in the flue gas discharged from the top exhaust port of chimney 200. Sampling and analysis were performed on the flue gas after the demister 101 in the wet desulfurization tower 100. Taking into account the influence factor of droplet content A, and after sampling and conversion, the droplet content A = 0.15 g / kg dry flue gas. The droplet content and temperature deviation σ were used to adjust the temperature... HCT The calculation formula was modified, and the influence factors of temperature deviation were comprehensively considered. The temperature deviation σ was defined as 2.5℃, at which point the exhaust gas no longer produced white smoke.

[0122] The foregoing description of specific exemplary embodiments of the present invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. Any simple modifications, equivalent changes, and alterations made to the foregoing exemplary embodiments should fall within the scope of protection of the present invention.

Claims

1. A method for eliminating white smoke in wet desulfurization flue gas, characterized in that, The process of eliminating white smoke in flue gas by mixing hot air with wet desulfurization flue gas heated by a partition wall includes the following steps: A. Collect the atmospheric temperature at the corresponding height of the exhaust outlet of the wet desulfurization chimney. T e and atmospheric relative humidity Data; collecting air temperature at the fan inlet. T a and relative humidity of air data; B. Based on the atmospheric temperature T e and atmospheric relative humidity The air temperature T a and relative humidity of air Calculate atmospheric moisture content and air humidity ; C. Collect the flue gas temperature of the saturated wet flue gas after wet desulfurization. T G And calculate the moisture content of the flue gas. ; D. Collect the dry air flow rate at the fan outlet. F a Dry flue gas flow rate after wet desulfurization and reheat F G Combined with the aforementioned air humidity content and the moisture content of the flue gas Calculate the moisture content of the mixture of flue gas and air. ; E. Temperature of the flue gas after reheating T GH ; Using the moisture content of the mixed gas Calculate the temperature at the intersection T mix According to the temperature at the intersection point T mix The moisture content of the mixed gas The temperature of the flue gas after reheating T GH The moisture content of the flue gas and the atmospheric moisture content Calculate the critical heating temperature of hot air required for flue gas to eliminate white smoke. T HCT ; F. Adjust the amount of heat medium used in the air heater in real time until the hot air temperature reaches the target level. T ah Critical heating temperature of the hot air T HCT When the values ​​are equal, the flue gas is discharged. The atmospheric humidity in step B air humidity and the moisture content of the flue gas in step C The calculation is performed in the following way: ； in, P s The partial pressure of water vapor in saturated air is the pressure of water vapor when the relative humidity of the gas is 100%, and the unit is Pa; the unit of moisture content is g / kg dry air. The moisture content of the mixed gas in step D The calculation is performed in the following way: ； The intersection temperature in step E T mix The calculation is performed in the following way: ； Ttan This refers to the atmospheric environmental state point ( T e , The temperature at which the tangent line to the water vapor saturation curve is drawn; The critical heating temperature of hot air in step E T HCT The calculation is performed in the following way: ； When the flue gas contains droplets and is in a supersaturated state, the critical heating temperature of the hot air is determined by the droplet content A. T HCT The calculation formula (4) is modified as follows: ； Wherein, A is the droplet content in the flue gas after wet desulfurization and before entering the flue gas reheater, in g / kg dry flue gas; the droplet content A is comprehensively defined by the demister structure factor, flue gas flow rate factor, demister pressure drop factor, and demister flushing factor.

2. The method for eliminating white smoke in wet desulfurization flue gas according to claim 1, characterized in that, When the temperature measuring point of the hot air is at a certain distance from the mixing point of the reheated flue gas and the hot air, and / or when the mixing point of the reheated flue gas and the hot air is at a certain distance from the chimney outlet, the temperature deviation is used to measure the temperature. The critical heating temperature of the hot air T HCT The calculation formula (5) is modified as follows: ； in, This refers to the temperature deviation, specifically defined as -5℃ to 5℃.

3. The method for eliminating white smoke in wet desulfurization flue gas according to claim 2, characterized in that, When there is a certain distance between the reheated flue gas and hot air mixing area and the chimney outlet, the temperature deviation... The factors are comprehensively defined by heat transfer area factor, chimney structure factor, temperature difference factor between flue gas and atmosphere, flue gas velocity factor, and environmental wind force level factor.

4. The method for eliminating white smoke in wet desulfurization flue gas according to claim 1, characterized in that, When the hot air reaches its critical heating temperature T HCT ≤Air temperature at the inlet of the fan T a When this happens, the heat transfer medium consumption of the heater is adjusted to 0 t / h.

5. The method for eliminating white smoke in wet desulfurization flue gas according to claim 1, characterized in that, Before being mixed with hot air, the flue gas after wet desulfurization enters a flue gas reheater for heating, and the temperature rise of the flue gas after passing through the flue gas reheater is 2~10℃.

6. The method for eliminating white smoke in wet desulfurization flue gas according to claim 5, characterized in that, The method for eliminating white smoke from flue gas involves pressurizing the air using the fan, heating the pressurized air by connecting a heat transfer medium water heater and a steam heater in series, mixing the heated air with the flue gas after wet desulfurization and reheating, and then discharging the mixed heated flue gas into the atmosphere through a chimney.

7. A wet desulfurization flue gas white smoke elimination device, characterized in that, The method described in any one of claims 1 to 6, wherein the wet desulfurization tower and the chimney are integrated or separate, and white smoke elimination in the flue gas is achieved by mixing hot air with the reheated flue gas after wet desulfurization, includes: The atmospheric and air data acquisition unit is used to collect the atmospheric temperature at the corresponding height of the exhaust outlet of the wet desulfurization chimney. T e and atmospheric relative humidity Data; collecting air temperature at the fan inlet. T a and relative humidity of air data; The atmospheric and air humidity calculation unit calculates the atmospheric temperature. T e and atmospheric relative humidity The air temperature T a and relative humidity of air Calculate atmospheric moisture content and air humidity ; The flue gas temperature acquisition and moisture content calculation unit is used to collect the flue gas temperature of the saturated wet flue gas after wet desulfurization. T G And calculate the moisture content of the flue gas. ; The flow rate acquisition and mixed gas moisture content calculation unit is used to acquire the dry air flow rate at the fan outlet. F a Dry flue gas flow rate after wet desulfurization and reheat F G Combined with the aforementioned air humidity content and the moisture content of the flue gas Calculate the moisture content of the mixture of flue gas and air. ; The hot air critical heating temperature calculation unit collects the temperature of the reheated flue gas. T GH ; utilizing the moisture content of the mixed gas Calculate the temperature at the intersection T mix According to the temperature at the intersection point T mix The moisture content of the mixed gas The temperature of the flue gas after reheating T GH The moisture content of the flue gas and the atmospheric moisture content Calculate the critical heating temperature of hot air required for flue gas to eliminate white smoke. T HCT ; The flue gas exhaust control unit is used to adjust the amount of heat medium used in the air heater in real time until the hot air temperature reaches the specified level. T ah Critical heating temperature of the hot air T HCT When the values ​​are equal, the flue gas is discharged.

Images