Device and method for simultaneous removal of droplets and fine particulate matter from flue gas

Abstract

The application discloses a device and method for synergistically removing mist droplets and fine particulate matters from flue gas. The device is arranged in a desulfurization tower and comprises: a plurality of draft tubes which are cylindrical elements with upper and lower openings, the lower ends of the draft tubes being fixed on a tower tray and serving as flue gas inlets; atomizing nozzles fixed in the draft tubes for atomizing and spraying condensed water to form condensed water mist covering the cross section of the draft tubes; a plurality of gas collecting tubes which are cylindrical elements with open lower ends and closed upper ends, the number of the gas collecting tubes being matched with that of the draft tubes, the gas collecting tubes being used for receiving cooled flue gas from the draft tubes; a drainage gap being arranged between the lower end of each gas collecting tube and the outer wall surface of the corresponding draft tube; and a plurality of gas distribution holes being arranged on the sidewall of each gas collecting tube, so that the flue gas flowing out of adjacent gas collecting tubes collides with each other to remove mist droplets and fine particulate matters. The device and method of the application do not need to use additional mist removal equipment and increase the height of the tower body, and can effectively remove mist droplets and condensable particulate matters in the flue gas.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flue gas emission control, in particular to a device and method for flue gas and fine particulate matter removal. BACKGROUND

[0002] A large amount of flue gas is generated in the production process of energy, petrochemical, metallurgy, chemical industry and other fields, and the flue gas contains a large amount of SO2, NO X X and dust (particulate matter) and other harmful substances, which cause a series of environmental problems such as haze, acid rain, greenhouse effect, etc., and cause serious pollution to the ecological environment. At present, in the process of flue gas desulfurization and tail gas dust removal in the environmental protection field, wet process is generally used, such as wet desulfurization process, that is, by spraying alkali solution in the desulfurization absorption tower to wash away or absorb SO2 and dust (particulate matter) in the flue gas. The wet flue gas discharged after wet treatment still contains fine droplets and particulate matter composed of sulfuric acid, sulfate, liquid water, soluble salt, smoke dust and other substances, which not only causes serious corrosion and fouling to the process equipment, but also pollutes the atmosphere and seriously endangers the ecological environment. Wet desulfurization process generally sets a mist eliminator at the top of the absorption tower, and the existing mist eliminator can only remove liquid droplets larger than 20 μm (JB / T 10989-2010), and cannot remove smaller liquid droplets and dust (particulate matter) in the flue gas.

[0003] There is a technical scheme in the prior art that directly sprays a cooling medium into the flue gas to cool the flue gas: by cooling the flue gas, the CPM (condensable particulate matter) in the flue gas is condensed to form fine particulate matter (i.e. smaller particulate matter than PM 2.5 ), and after the flue gas is cooled, water vapor condenses and precipitates with the fine particulate matter formed by CPM and other fine particulate matter such as dust, SO3 aerosol (sulfuric acid mist) in the flue gas as condensation nuclei, the particle size of the fine particulate matter increases, and then is removed. However, this kind of scheme often needs to separately set a condensation tower and a matching condensation system, a mist eliminator, etc., which requires more floor area, or greatly increases the height of the desulfurization tower, and the investment is high, which is difficult to meet the compact desulfurization system modification.

[0004] For example, Chinese patent application CN108014578A discloses a method and device for removing fine particulate matter and condensable particulate matter in low-temperature sprayed coal-fired flue gas. The method sprays cold mist on the saturated wet flue gas after wet desulfurization, the temperature of the cold mist is not more than 20℃, and the droplet particle diameter of the cold mist is not more than 800 μm. This scheme can remove fine particulate matter and condensable particulate matter in coal-fired flue gas, but a separate condensation tower is needed, and the travel of the cooled flue gas is short, the particle size of the fine particulate matter cannot be effectively increased, and the removal efficiency needs to be improved.

[0005] Therefore, there is an urgent need for a desulfurization tower which can effectively remove the mist and condensable particulate matters in the flue gas without additional land occupation and significant increase in the height of the tower.

[0006] The information disclosed in this Background section is only for the purpose of increasing an understanding of the general context of the present application and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known in this field. SUMMARY

[0007] The present application aims to provide a device and method for simultaneously removing mist and fine particulate matters from flue gas, which is arranged in a desulfurization tower without using additional mist removal equipment and without increasing the height of the tower, and which can effectively remove the mist and fine particulate matters in the flue gas.

[0008] To achieve the above-mentioned purpose, according to a first aspect of the present application, a device for simultaneously removing mist and fine particulate matters from flue gas is provided, which is arranged in a desulfurization tower and comprises: a plurality of draft tubes which are cylindrical elements with upper and lower openings, the lower ends of the draft tubes being fixed to the tower tray and serving as the flue gas inlet; an atomizing nozzle which is fixed in the draft tube and used for atomizing and spraying the condensed water to form a condensed water mist covering the cross section of the draft tube; a plurality of gas collection tubes which are cylindrical elements with lower openings and upper ends closed, used for receiving the cooled flue gas from the draft tubes; a drainage gap being provided between the lower end of the gas collection tube and the outer wall surface of the draft tube; and a plurality of gas distribution holes being provided on the side wall of the gas collection tube, so that the flue gas flowing out of adjacent gas collection tubes forms a collision, and the mist and fine particulate matters are removed.

[0009] Further, in the above-mentioned technical solution, the draft tube can be a tapered tube with a gradually changing inner diameter, and the upper end diameter is smaller than the lower end diameter.

[0010] Further, in the above-mentioned technical solution, a guide vane can be provided outside the gas distribution hole, so that the flue gas flowing out forms an obliquely downward airflow.

[0011] Further, in the above-mentioned technical solution, the drainage gap can be an annular gap, and a V-shaped space for removing the mist can be provided below the annular gap.

[0012] Further, in the above-mentioned technical solution, the lower end inner diameter of the gas collection tube can be smaller than the upper end inner diameter, i.e. the tube wall is obliquely arranged towards the inside.

[0013] Further, in the above-mentioned technical solution, the device of the present application can further comprise a coalescence removal assembly which is arranged above the gas collection tube and receives the cooled flue gas flowing out of the gas distribution hole and colliding, and is used for coalescing the mist and fine particulate matters in the flue gas, and under the action of centrifugal force, the mist and fine particulate matters are thrown to the wall surface of the desulfurization tower after the particle size is increased.

[0014] Further, in the technical scheme, the coalescence removal assembly can include: coalescence elements, which are in the form of a brush and are in a plurality, one end of each coalescence element is fixed on the central shaft, and the plurality of coalescence elements are uniformly distributed along the axial direction and the radial direction of the central shaft.

[0015] Further, in the technical scheme, the coalescence removal assembly can further include an impeller and / or a driving motor; wherein the impeller can be arranged below the coalescence elements and fixed on the central shaft, under the action of the rising flue gas, the impeller drives the central shaft and the coalescence elements to rotate; the driving motor can be connected with the central shaft, for driving the central shaft and the coalescence elements to rotate.

[0016] According to the second aspect of the present application, the present application provides a method for removing mist droplets and fine particulate matters from flue gas, which uses the device of any one of the preceding aspects, and includes the following steps: A, in the process of flue gas entering the riser from the lower part of the tower tray upwards, a condensate mist covering the entire cross section of the riser is formed, and the condensable particulate matters in the flue gas are condensed and precipitated to form fine particulate matters; B, the fine particulate matters collide with each other to form coalescence, and are further captured by the condensate mist droplets, which can effectively increase the particle size of the fine particulate matters; C, the flue gas flowing out of the adjacent gas collectors collides with each other through the gas distribution holes arranged on the side wall of the gas collector, thereby removing the mist droplets and fine particulate matters.

[0017] Further, in the technical scheme, by using the conical riser, the rising speed of the flue gas in the riser can be gradually increased.

[0018] Further, in the technical scheme, since the inner diameter of the gas collector is larger than the inner diameter of the riser, the running speed of the flue gas in the gas collector slows down and the flue gas can flow obliquely downward under the action of the guide vanes at the gas distribution holes.

[0019] Further, in the technical scheme, the obliquely downward flowing flue gas collides with the flue gas flowing out of the corresponding position of the adjacent gas collector, and the mist droplets and fine particulate matters formed after coalescence are removed in the V-shaped space below the collision area.

[0020] Further, in the technical scheme, the method of the present application can further include the following step: D, the colliding flue gas continues to rise into the space where the coalescence removal assembly is located, the particle size of the mist droplets and fine particulate matters coalesced on the coalescence elements is increased, and the mist droplets and fine particulate matters are thrown to the desulfurization tower wall under the action of centrifugal force.

[0021] Further, in the technical scheme, the mist droplets and fine particulate matters thrown to the desulfurization tower wall under the action of centrifugal force can be specifically: under the action of the rising flue gas, the central shaft is driven and the coalescence elements are rotated by the impeller located below the coalescence elements, thereby forming the centrifugal force; and / or, the central shaft is driven and the coalescence elements are rotated by the driving motor, thereby forming the centrifugal force.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] 1) Compared with the existing mist eliminator of the wet desulfurization system, the present application can remove the condensable particulate matter effectively while removing the mist droplets, and has good environmental benefits;

[0024] 2) The present application can realize in-situ replacement of the existing mist eliminator, and after replacement, the height of the tower body, the floor area and the weight of the tower body change little, so the tower foundation does not need to be reinforced, and the transformation cost can be greatly reduced;

[0025] 3) The structural design of the conical gas riser of the present application increases the flow rate of the flue gas carrying the condensed water mist droplets flowing through the gas riser, strengthens the gas-liquid mixing, is more conducive to mass and heat transfer, and increases the probability of collision and coalescence of the liquid droplets and the fine particulate matter; after the flue gas enters the gas collector, the flow rate slows down and the residence time increases, which is conducive to mass and heat transfer between the gas and the liquid, and is conducive to the continuous condensation and precipitation of water vapor on the surface of the liquid droplets and the fine particulate matter, and the particle size of the liquid droplets and the fine particulate matter is further increased; after the flue gas leaves the gas collector, the flow direction of the gas flow becomes obliquely downward under the action of the guide vane, and the gas flow between adjacent two gas collectors collides with each other, greatly increasing the probability of collision and coalescence of the liquid droplets and the fine particulate matter, and creating more favorable conditions for gas-liquid separation;

[0026] 4) When the flue gas enters the coalescing removal assembly, the mist droplets and fine particulate matter that have not been removed will adhere to the surface of the coalescing element and continue to coalesce and increase, and the coalesced mist droplets and fine particulate matter will be thrown to the desulfurization tower wall by the centrifugal force, which can further remove the mist droplets and fine particulate matter in the flue gas;

[0027] 5) The arrangement of the drainage gap and the V-shaped space can make the liquid droplets with a larger particle size in the flue gas enter the V-shaped space under the action of their own gravity, realizing the first gas-liquid separation; the second gas-liquid separation can be realized by the collision of the flue gas outside the gas distribution hole of the gas collector, and the third gas-liquid separation can be realized by the coalescing and centrifugal throwing of the coalescing removal assembly, so that the liquid droplets in the flue gas can be removed in stages, and the removal efficiency of the liquid droplets can be effectively improved;

[0028] 6) Compared with the existing mist elimination equipment, the present application can not only realize the third gas-liquid separation, but also realize self-cleaning without the need to set up a flushing water, so that the equipment investment and system water consumption can be effectively reduced.

[0029] The above description is only a summary of the technical solutions of the present application, in order to more clearly understand the technical means of the present application and can be implemented according to the content of the specification, and at the same time, in order to make the above and other purposes, technical features and advantages of the present application more easily understood, one or more preferred embodiments are listed below, and are described in detail as follows with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is the structural schematic diagram of the device for removing mist droplets and fine particulate matters from flue gas according to the present application, embodiment 1.

[0031] Figure 2 is the structural schematic diagram of the device for removing mist droplets and fine particulate matters from flue gas according to the present application, embodiment 2.

[0032] Figure 3 is the structural schematic diagram of the device for removing mist droplets and fine particulate matters from flue gas according to the present application, embodiment 3.

[0033] Figure 4 is the structural schematic diagram of the device for removing mist droplets and fine particulate matters from flue gas according to the present application, embodiment 4.

[0034] MAIN REFERENCE NUMERALS:

[0035] 10 - desulfurization tower body, 100 - tower tray, 101 - overflow pipe;

[0036] 41 - gas lifting cylinder, 42 - atomizing nozzle, 420 - condensed water pipeline, 43 - gas collecting cylinder, 431 - gas distribution hole, 432 - guide vane, 44 - drainage gap;

[0037] 50 - coalescence removal assembly, 51 - central shaft, 52 - coalescence element, 53 - fixing member, 54 - driving motor, 55 - impeller. DETAILED DESCRIPTION

[0038] The specific embodiments of the present application will be described in detail below with reference to the accompanying drawings, but it should be understood that the scope of protection of the present application is not limited by the specific embodiments.

[0039] Unless otherwise explicitly stated, throughout the specification and claims, the term "comprise" or its variants such as "comprises" or "comprising" will be understood to encompass the stated element or components, but not to exclude other elements or components.

[0040] For the purposes of this document, spatially relative terms, such as "beneath", "below", "lower", "above", "upper", and the like, can be used to describe an element's or feature's relationship to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. For example, if an element in a figure is oriented horizontally, it is also intended to encompass various other orientations, including vertical and rotated orientations. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0041] In this document, the terms "first", "second", etc. are used to distinguish between two different elements or portions of an element, and are not used to designate a particular position or relative relationship. In other words, in some embodiments, the terms "first", "second", etc. can also be interchanged with each other.

[0042] Example 1

[0043] As Figure 1 shown, the present embodiment provides a device for simultaneous removal of droplets and fine particulate matter from flue gas, which is arranged in a desulfurization tower body 10, and can realize in-situ replacement of the existing mist eliminator. The device of the present embodiment includes a gas lifting cylinder 41, an atomizing nozzle 42, and a gas collecting cylinder 43. The gas lifting cylinder 41 is a plurality of upper and lower open cylindrical elements, the lower end of the gas lifting cylinder 41 is fixed on the tower tray 100 and serves as the flue gas inlet, the bottom of the tower tray 100 is provided with an overflow pipe 101 for transporting the liquid on the tower tray 100 to the lower part of the tower tray. The shape of the gas lifting cylinder 41 can be one or a combination of a cylindrical, conical, inverted conical, square, rectangular, or quadrangular prism. Preferably, but not limitedly, the present embodiment adopts a conical cylinder with gradually changing inner diameter, and the upper end diameter is smaller than the lower end diameter, which can effectively ensure that the flue gas velocity gradually increases during the ascending process in the gas lifting cylinder.

[0044] Further as Figure 1 shown, the atomizing nozzle 42 is fixed in the gas lifting cylinder 41, and is preferably arranged on the center line of the gas lifting cylinder 41. The atomizing nozzle 42 is in communication with the condensate water pipeline, and is used to atomize and spray the condensate water to form a condensate water mist covering the cross section of the gas lifting cylinder 41.

[0045] Further as Figure 1As shown, the gas collecting tubes 43 are arranged above the gas lifting tubes 41 in a number corresponding to the number of the gas lifting tubes 41. The gas collecting tubes 43 are open-ended at the lower end and closed at the upper end, and are used to receive the flue gas cooled by the atomizing nozzles 42 from the gas lifting tubes 41. A drainage gap 44 is provided between the lower end of the gas collecting tubes 43 and the outer wall surface of the gas lifting tubes 41, which is preferably but not limited to an annular gap. A V-shaped space (the end of the V-shaped space is the tray 100) is provided below the annular gap for removing mist droplets, and is used to directly discharge the larger size mist droplets in the flue gas after temperature reduction from the annular gap to the tray. Further, the side wall of the gas collecting tube 43 is provided with a plurality of gas distribution holes 431, so that the flue gas flowing out of adjacent gas collecting tubes 43 forms a collision to remove mist droplets and fine particulate matter. Preferably but not limited to, a guide vane 432 can be arranged outside the gas distribution hole 431, so that the flue gas flowing out forms an obliquely downward airflow. The flue gas flowing out of the gas collecting tube 43 changes from one stream to multiple streams, and the collision of the obliquely downward airflow effectively prolongs the airflow path and creates better conditions for collision and coalescence.

[0046] The working principle of the embodiment is as follows: during the working process, flue gas enters the riser 41 from the lower space of the tray 100 upwards, the atomizing nozzle 42 atomizes and sprays the condensed water to form mist droplets covering the entire cross section of the riser, the flue gas mixes with the condensed water mist droplets to perform heat and mass transfer, the temperature of the flue gas decreases, the condensable particulate matters in the flue gas are condensed and precipitated to form fine particulate matters, the water vapor in the flue gas is condensed and precipitated to form fine particulate matters with the fine particulate matters formed after the condensation of the condensable particulate matters, dust, SO3 aerosol (sulfuric acid mist) and other fine particulate matters in the flue gas as condensation nuclei, thereby forming a "water-in-nucleus" structure, so that the particle size of the fine particulate matters is increased, the fine particulate matters collide with each other to produce coalescence and further increase the particle size, and the fine particulate matters collide with the condensed water mist droplets to be captured by the condensed water mist droplets. The riser 41 of the embodiment adopts a conical cylinder structure, the flue gas flows through the riser, the gas velocity gradually increases, and the mass and heat transfer between the gas and the liquid are strengthened. The condensed water mist droplets carried by the gas, the fine particulate matters and the condensed water mist droplets, and the fine particulate matters collide with each other, small droplets are more likely to coalesce into large droplets, a part of the fine particulate matters are captured by the condensed water mist droplets, the flue gas carrying the mist droplets leaves the riser 41, the liquid droplets with a larger particle size in the flue gas enter the V-shaped space formed by the outer wall of the adjacent riser and the tray under the action of gravity through the drainage gap 44, and the first gas-liquid separation is realized; further, the flue gas carrying the condensed water mist droplets and the fine particulate matters enters the gas collecting cylinder 43, the cross-sectional area of the passage increases, the flow velocity of the flue gas slows down, the residence time increases, the mass and heat transfer between the gas and the liquid continue, the particle size of the fine particulate matters continues to increase, and more fine particulate matters are captured by the condensed water mist droplets; the flue gas carrying the condensed water mist droplets and the fine particulate matters leaves the gas collecting cylinder 43 through the gas distribution hole 431, and the gas flow changes into several gas flows, the flow direction of the gas flow changes to be obliquely downward under the action of the flow guide piece 432, the gas flow between the adjacent two gas collecting cylinders 43 collides, the condensed water mist droplets in the flue gas collide with each other, the condensed water mist droplets collide with the fine particulate matters, and the fine particulate matters collide with each other, coalesce and further increase the particle size after the violent collision under the action of the gas flow, and fall on the tray 100 or flow into the liquid layer on the tray 100 after colliding with the outer wall of the riser 41, so that the condensed water mist droplets and the fine particulate matters are removed, and the liquid flows into the space below the tray through the overflow pipe 101 on the tray 100 to realize the second gas-liquid separation in the flue gas.

[0047] Example 2

[0048] As shown in Figure 2 , the embodiment adopts the same riser 41, atomizing nozzle 42 and gas collecting cylinder 43 as those of the embodiment 1, and the same drainage gap 44 is also provided between the lower end of the gas collecting cylinder 43 and the outer wall of the riser 41. Different from the embodiment 1, the flue gas carrying the remaining fine particulate matters after the collision of multiple gas flows continues to rise into the coalescence removal assembly 50.

[0049] Further as Figure 2 shown, the coalescing removal assembly 50 is arranged above the gas collecting cylinder 43 and receives the cooling flue gas after colliding from the gas distribution holes 432, for coalescing the droplets and fine particulate matters in the flue gas, and after the particle size increases, the droplets and fine particulate matters are thrown to the desulfurization tower wall under the action of centrifugal force. Specifically, the coalescing removal assembly 50 of the embodiment includes a central shaft 51, coalescing elements 52, a fixing member 53, and a driving motor 54. The central shaft 51 is fixed on the center line of the desulfurization tower body 10 through the fixing member 53 and can be driven to rotate by the driving motor 54. The outer edge of the fixing member 53 is fixed on the inner wall of the desulfurization tower body 10, and the fixing member 53 is provided with gas holes (not shown in the figure) allowing the flue gas to pass through. The coalescing elements 52 are in the form of a brush and are multiple in number. Each coalescing element 52 is fixed at one end on the central shaft 51, and the multiple coalescing elements 52 are uniformly distributed along the axial and radial directions of the central shaft 51. The arrangement of the coalescing elements forms a brush array that basically covers the entire tower body space in the desulfurization tower body 100. The driving motor 54 is used to drive the central shaft 51 and rotate the coalescing elements 52.

[0050] The working principle of the embodiment is as follows: the flue gas is atomized and sprayed by the riser 41, forms a "water-in-nucleus" structure, and after the fine particulate matters collide with the condensed water droplets, the fine particulate matters are captured by the condensed water droplets. The large droplets enter the V-shaped space through the drainage gap to realize the first gas-liquid separation (the same as in embodiment 1). After the flue gas enters the gas collecting cylinder 43, it exits the gas collecting cylinder 43 through the gas distribution holes 431, and the gas flow changes from one gas flow to several gas flows. Under the action of the guide vanes 432, the flow direction of the gas flow becomes obliquely downward, and the gas flow between two adjacent gas collecting cylinders 43 collides to realize the second gas-liquid separation (the same as in embodiment 1). The flue gas further rises into the coalescing removal assembly 50. The droplets and fine particulate matters that are not removed in the flue gas will adhere to the surface of the coalescing elements 52. When the particle size of the droplets and fine particulate matters increases to a certain extent, the driving motor 54 is started, and the droplets and fine particulate matters will be thrown to the inner wall of the desulfurization tower under the action of the centrifugal force generated by the rotation of the central shaft 51 driving the coalescing elements 52, and then collected into a water flow, and then enter the tower tray below through the overflow pipe 101 to realize the third gas-liquid separation.

[0051] Example 3

[0052] As Figure 3 shown, the embodiment adopts the same riser 41, atomizing nozzle 42, and gas collecting cylinder 43 as in embodiment 2, and the same drainage gap 44 is also provided between the lower end of the gas collecting cylinder 43 and the outer wall of the riser 41. Different from embodiment 2, the driving element of the central shaft 51 in the embodiment is a impeller 55.

[0053] Further as Figure 3As shown, the coalescing removal component 50 is positioned above the gas collecting cylinder 43 and receives the cooled flue gas flowing out from the gas distribution hole 432 after collision. It is used to coalesce droplets and fine particulate matter in the flue gas, and after the particle size increases, the droplets and fine particulate matter are thrown towards the desulfurization tower wall under the action of centrifugal force. Specifically, the coalescing removal component 50 of this embodiment includes a central shaft 51, a coalescing element 52, a fixing member 53, and an impeller 55. The central shaft 51 is fixed to the center line of the desulfurization tower body 10 by the fixing member 53 and is rotatable. The outer edge of the fixing member 53 is fixed to the inner wall of the desulfurization tower body 10, and the fixing member 53 is provided with air holes (not shown in the figure) that allow flue gas to pass through. The coalescing elements 52 are brush-like structures and are numerous. Each coalescing element 52 is fixed at one end to the central shaft 51. The multiple coalescing elements 52 are evenly spaced along the axial and radial directions of the central shaft 51. The overall arrangement of the coalescing elements forms a brush array that basically covers the entire space of the desulfurization tower 100. The impeller 55 is fixed on the central shaft below the coalescing elements 52. The impeller 55 can rotate under the action of the rising flue gas. The rotation of the impeller 55 drives the central shaft 51 and drives the coalescing elements to rotate, generating centrifugal force. In this embodiment, no additional driving force is required. The continuous rotation of the coalescing elements 52 is achieved by utilizing the thrust of the rising flue gas, thereby removing the surface-agglomerated droplets and fine particulate matter. This embodiment can also achieve three-stage gas-liquid separation.

[0054] Example 4

[0055] like Figure 4 As shown, this embodiment combines Embodiment 2 and Embodiment 3, and adopts the same air lifting cylinder 41, atomizing nozzle 42 and air collecting cylinder 43 as Embodiment 2 and Embodiment 3. The lower end of the air collecting cylinder 43 and the outer wall surface of the air lifting cylinder 41 also have the same drainage gap 44. It should be noted that the coalescing removal component 50 in this embodiment employs both a drive motor 54 and an impeller 55. When the rotational drive element is the drive motor 54 and the impeller 55 is simultaneously mounted on the central shaft 51, the drive motor 54 can be periodically turned on and off. When the drive motor 54 stops and the flue gas flows through the impeller 55, the rising flue gas drives the impeller 55 to rotate and drives the central shaft 51 to rotate. At this time, the rotation speed is relatively slow, and droplets and fine particles continuously coalesce on the coalescing element, with the particle size continuously increasing. When the particle size increases to a certain extent, the drive motor 54 is turned on, and the rotation speed of the coalescing element 52 increases sharply, generating a large centrifugal force, which removes all droplets and fine particles attached to the coalescing element 52. This effectively achieves self-cleaning of the coalescing element 52 and avoids the consumption of rinsing water.

[0056] Further, the embodiment differs from embodiments 1 to 3 in the shape of the gas collecting cylinder 43, the inner diameter of the lower end of the gas collecting cylinder 43 of the embodiment is smaller than that of the upper end, i.e. the cylinder wall is arranged to be inclined towards the inside. With such a gas collecting cylinder, on the one hand, the speed of the flue gas gradually slows down in the gas collecting cylinder 43 as the flue gas rises, which can effectively increase the coalescence time of the fine particulate matters and the mist droplets, and the coalescence removal effect is better; on the other hand, the flue gas flowing out of the gas distribution holes 431 gradually increases in speed during the rising process, which can further optimize the collision effect and at the same time increase the speed of the flue gas rising into the coalescence removal assembly 50, so that the impeller 55 obtains greater driving force.

[0057] Example 5

[0058] The embodiment provides a method for coalescing and removing mist droplets and fine particulate matters from flue gas by using the aforementioned device, which comprises the following steps:

[0059] In step S101, the flue gas enters the riser 41 from the lower part of the tray 100 upwards, forming a condensate mist covering the entire cross section of the riser 41, and the condensable particulate matters in the flue gas are condensed and precipitated to form fine particulate matters. Further, the riser is arranged in a conical shape, so that the rising speed of the flue gas in the riser gradually increases, which can further strengthen the heat and mass transfer between the gas and the liquid.

[0060] In step S102, the fine particulate matters in the flue gas collide with each other to produce coalescence, and are further captured by the condensate mist droplets, which can effectively increase the particle size of the fine particulate matters, creating more favorable conditions for subsequent removal. In this stage, larger mist droplets can flow to the tray through the drainage gap 44, realizing the first gas-liquid separation.

[0061] In step S103, the flue gas flowing out of the adjacent gas collecting cylinders 43 forms a collision through the multiple gas distribution holes 431 arranged on the side wall of the gas collecting cylinder 43, and the mist droplets and fine particulate matters are removed. Specifically, preferably but not limitedly, the flue gas slows down in the gas collecting cylinder 43 and flows downward under the action of the guide piece 432 at the gas distribution hole 431. The flue gas flowing downward obliquely collides with the flue gas flowing out of the corresponding position of the adjacent gas collecting cylinder, and the mist droplets and fine particulate matters formed after coalescence can be removed in the V-shaped space below the collision area, realizing the second gas-liquid separation.

[0062] Step S104, the flue gas after collision continues to rise into the space where the coalescing removal assembly 50 is located, and the droplets and fine particulate matters after coalescing on the coalescing element 52 gradually increase in size, and under the action of centrifugal force, the droplets and fine particulate matters are thrown to the desulfurization tower wall. Specifically, under the action of the rising flue gas, the central shaft 51 can be driven by the impeller 55 located below the coalescing element 52 and the coalescing element is rotated, forming a centrifugal force; and / or, the central shaft 51 is driven by the driving motor 54 and the coalescing element 52 is rotated, forming a centrifugal force. When the driving motor 54 and the impeller 55 are used at the same time, the driving motor 54 can be started and stopped periodically, when the driving motor 54 stops, the flue gas flows through the impeller 55, the rising flue gas drives the impeller 55 to rotate and drives the central shaft 51 to rotate, at this time the rotating speed is relatively slow, the droplets and fine particulate matters are continuously coalesced on the coalescing element, and the particle size is continuously increased, when it is increased to a certain extent, the driving motor 54 is started again, the rotating speed of the coalescing element 52 is sharply increased, a larger centrifugal force is generated, and the droplets and fine particulate matters attached to the coalescing element 52 can be completely removed.

[0063] The foregoing description of specific exemplary embodiments of the application is intended to be illustrative only and is not intended to limit the application to the precise forms described. Many modifications and variations are possible in light of the above teachings without departing from the spirit or essential characteristics of the application. The exemplary embodiments were chosen and described in order to explain the principles of the application and its practical application and to allow others skilled in the art to understand the application for various exemplary embodiments and its various modifications as are suited to the particular use contemplated. Any simple modification, equivalent replacement, and modification of the above-described exemplary embodiments should fall within the scope of the present application.

Claims

1. A device for the synergistic removal of mist droplets and fine particulate matter from flue gas, characterized in that, Installed inside the desulfurization tower, including: The air lifter consists of multiple cylindrical elements that are open at the top and bottom. The lower end of the air lifter is fixed to the tray and serves as the flue gas inlet. The air lifter is a tapered cylinder with a gradually changing inner diameter, and the diameter at the upper end is smaller than the diameter at the lower end. Atomizing nozzle, fixed in the air-lifting cylinder, is used to atomize and spray condensed water to form a condensed water mist covering the cross-section of the air-lifting cylinder. Water vapor in the flue gas condenses and precipitates out as fine particles formed by the condensation of condensable particles, as well as dust and SO3 aerosols in the flue gas, forming a "water-encased nucleus" structure. This increases the particle size of the fine particles, and the collisions between the fine particles cause them to aggregate and further increase in size. The fine particles are then captured by the condensed water mist droplets after colliding with them. As the flue gas flows through the air-lifting cylinder, the gas velocity gradually increases, enhancing the mass and heat transfer between the gas and liquid. The condensed water droplets carried by the gas, the fine particles and the condensed water droplets, and the fine particles collide with each other, causing small droplets to aggregate into large droplets. The number of gas collecting cylinders is matched with the number of gas lifting cylinders, and they are cylindrical elements with open bottoms and closed tops, used to receive cooled flue gas from the gas lifting cylinders; a drainage gap is provided between the lower end of the gas collecting cylinder and the outer wall of the gas lifting cylinder; the side wall of the gas collecting cylinder is provided with multiple gas distribution holes, so that the flue gas flowing out of adjacent gas collecting cylinders collides, removing mist droplets and fine particulate matter.

2. The apparatus for synergistic removal of mist droplets and fine particulate matter from flue gas according to claim 1, characterized in that, The gas distribution hole is provided with a guide plate on the outside, so that the outflowing flue gas forms an inclined downward airflow.

3. The apparatus for synergistic removal of mist droplets and fine particulate matter from flue gas according to claim 1, characterized in that, The drainage gap is an annular gap, and a V-shaped space for removing mist droplets is provided below the annular gap.

4. The apparatus for synergistic removal of mist droplets and fine particulate matter from flue gas according to claim 1, characterized in that, The lower inner diameter of the gas collecting cylinder is smaller than the upper inner diameter, and the cylinder wall is inclined inward.

5. The apparatus for synergistic removal of mist droplets and fine particulate matter from flue gas according to claim 1, characterized in that, The device further includes: The coalescence removal component is located above the gas collecting cylinder and receives the cooled flue gas flowing out of the gas distribution hole and after collision. It is used to coalesce droplets and fine particulate matter in the flue gas and, after the particle size increases, throw the droplets and fine particulate matter towards the wall of the desulfurization tower under the action of centrifugal force.

6. The apparatus for synergistic removal of mist droplets and fine particulate matter from flue gas according to claim 5, characterized in that, The coalescing removal component includes: The coalescing elements are brush-like structures and there are multiple coalescing elements. One end of each coalescing element is fixed on a central shaft, and the multiple coalescing elements are evenly spaced along the axial and radial directions of the central shaft.

7. The apparatus for synergistic removal of mist droplets and fine particulate matter from flue gas according to claim 6, characterized in that, The coalescing removal assembly also includes an impeller and / or a drive motor; The impeller is positioned below the coalescing element and fixed on the central shaft. Under the action of the rising flue gas, the impeller drives the central shaft and causes the coalescing element to rotate. The drive motor is connected to the central shaft and is used to drive the central shaft and rotate the coalescing element.

8. A method for synergistic removal of mist droplets and fine particulate matter from flue gas, characterized in that, Using the apparatus as described in any one of claims 1 to 7, the method includes the following steps: A. As the flue gas enters the riser from the bottom of the tray, it forms a condensate mist that covers the entire cross-section of the riser. Condensable particulate matter in the flue gas condenses and precipitates out to form fine particulate matter. B. The fine particles collide with each other and then aggregate, and are further captured by condensed water droplets, increasing the particle size of the fine particles. C. Multiple gas distribution holes are provided on the side wall of the gas collecting cylinder, causing the flue gas flowing out of adjacent gas collecting cylinders to collide and remove mist droplets and fine particulate matter.

9. The method for synergistic removal of mist droplets and fine particulate matter from flue gas according to claim 8, characterized in that, The rising speed of the flue gas in the riser gradually increases.

10. The method for synergistic removal of mist droplets and fine particulate matter from flue gas according to claim 9, characterized in that, The flue gas slows down in the gas collecting cylinder and flows downward at an angle under the action of the guide plate at the gas distribution hole.

11. The method for synergistic removal of mist droplets and fine particulate matter from flue gas according to claim 10, characterized in that, The downward-flowing flue gas collides with the flue gas flowing out from the corresponding position of the adjacent gas collecting cylinder. The resulting droplets and fine particles are removed in the V-shaped space below the collision area.

12. The method for synergistic removal of mist droplets and fine particulate matter from flue gas according to claim 8, characterized in that, The method further includes the following steps: D. After the collision, the flue gas continues to rise and enters the space where the coalescing removal component is located. The droplets and fine particles that coalesce on the coalescing element have increased in size. Under the action of centrifugal force, the droplets and fine particles are thrown towards the wall of the desulfurization tower.

13. The method for synergistic removal of mist droplets and fine particulate matter from flue gas according to claim 12, characterized in that, Specifically, the process of the mist droplets and fine particulate matter being thrown towards the wall of the desulfurization tower under the action of centrifugal force is as follows: Under the action of rising flue gas, the impeller located below the coalescing element drives the central shaft and causes the coalescing element to rotate, generating the centrifugal force; and / or, The centrifugal force is generated by driving the central shaft with a drive motor and causing the coalescing element to rotate.

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