Centrifugal filtering, dedusting and demisting device for wet flue gas

Abstract

The invention discloses a wet flue gas centrifugal filtration dedusting and demisting device, which relates to the technical field of deep purification of flue gas after wet washing, and comprises an absorption tower, a flue gas inlet, a flue gas outlet, a spraying layer, a dedusting and demisting layer and a washing layer, the dedusting and demisting layer is mounted in the absorption tower, is positioned above the spraying layer and below the flue gas outlet, and is formed by a plurality of groups of centrifugal filtering dedusting and demisting units which are compactly arranged side by side; the flushing layer is provided with a plurality of flushing nozzles, and each flushing nozzle is in one-to-one correspondence with the centrifugal filtration dedusting and demisting unit below the flushing nozzle; the centrifugal filtration dedusting and demisting unit comprises an outer cylinder, an inner cylinder, a centrifugal impeller and a filtration impeller, the outer cylinder is a tubular cylinder body, is perpendicular to the horizontal plane and comprises a cylinder body, an upper cover plate and a lower cover plate, and the centrifugal impeller and the filtration impeller are embedded in the center of the outer cylinder in a sleeved mode. The wet flue gas centrifugal filtration dedusting and demisting device has the advantages of centrifugal acceleration, collision interception, dynamic liquid film, filtration interception and channel reservation, and is safe in operation.

Description

Technical Field

[0001] The invention relates to the technical field of deep purification of flue gas after wet scrubbing, and in particular to a dust removal and mist removal device system based on the principle of centrifugal filtration liquid membrane interception. Background Art

[0002] Flue gas scrubbing technology is a commonly used pollutant treatment technology in industrial flue gas to reduce pollution to the environment. This technology removes particulate matter, acidic gases and other harmful components in flue gas through physical or chemical methods to meet environmental protection standards. Flue gas scrubbing technology has a wide range of applications, including metallurgy, electricity, chemical industry and other industries, among which dynamic wave scrubbing technology and liquid column injection flue gas desulfurization technology are two important flue gas scrubbing technologies. Especially in the process of large-scale fixed source flue gas treatment, wet flue gas desulfurization technology is often used as the tail process of flue gas treatment. The flue gas after scrubbing is directly discharged into the chimney and finally discharged into the surrounding atmosphere.

[0003] With the gradual improvement of the requirements for flue gas pollutant control, fine particles and slurry droplets carried in the flue gas after wet scrubbing and wet desulfurization are often carried in the flue gas and discharged together. Especially in special industries (steel sintering, petrochemical FCC, cement, etc.) and special working conditions (thermal power peak regulation, multiple furnaces and one tower, etc.), the particles and droplets in the flue gas are difficult to be intercepted by conventional demisters, wet electrostatic precipitators and other equipment, which ultimately causes the particle concentration in the flue gas emission index to exceed the standard.

[0004] Take the deep peak load regulation of thermal power as an example: The power system has undergone significant changes in the new scenario, and it has become more difficult to balance power supply and demand. The new scenario has typical characteristics such as rich new energy types, a high proportion of renewable energy access, and greater system uncertainty. The original load curve in the old scenario was relatively stable, and its flexibility adjustment capability could fully support the flexibility needs of the power system. In the new scenario, the power system has undergone the following four major changes: 1) Compared with the original load curve, the peak-to-valley difference and volatility of the net load curve in the new scenario have increased significantly; 2) With the increase in the proportion of renewable energy access, the flexibility needs of the power system have increased significantly; 3) Renewable energy has replaced traditional power sources, and the capacity of conventional flexibility resources has therefore been greatly reduced; 4) The traditional power supply and demand balancing method can no longer achieve the full-time envelope of the net load, and the power system has begun to experience a phenomenon of insufficient supply of flexibility resources during some periods.

[0005] In the context of deep peak regulation, thermal power units are faced with ultra-low load operating conditions, which bring operational problems not only in the main engine test and denitrification test, but also affect the deep purification process of flue gas particles and droplets after wet desulfurization. The existing deep dust removal and demisting devices at the back end of thermal power wet desulfurization are large in number, especially the tube bundle dust removal and demisting devices based on the principles of mechanical dust removal and water film dust removal, as well as plate type demisting devices and ridge type demisting devices. Especially when the unit is running at low load, the mechanical demisting device will greatly reduce the intensity of the collision between the particles and the liquid film due to the insufficient separation flow rate, and a large number of fine droplets and particles will escape from the wet desulfurization system under low flow rate conditions, thereby reducing the overall dust removal and demisting efficiency.

[0006] Faced with new industry characteristics, how to ensure that the normal emission concentration of particulate matter and droplets at ultra-low flow rates is lower than the conventional requirement of 5mg / Nm³ is a technical problem that practitioners must solve. Summary of the invention

[0007] In order to solve the problem that conventional mechanical dust and mist removal technologies are difficult to intercept fine particles and droplets under special working conditions, the present invention provides a flue gas centrifugal filtration dust and mist removal device and system installed in a wet flue gas scrubber, which utilizes fine droplets in the flue gas to form a dense filtration liquid film on the filter impeller, and after centrifugal acceleration of the flue gas, the flue gas containing dust and mist droplets collides with the liquid film at high speed, and the particles and fine droplets break through the surface tension of the liquid film and condense into droplets with larger diameters, thereby converging on the inner wall of the inner cylinder under the action of gravity and centrifugal force, and finally flowing back into the slurry pool of the wet scrubber under the action of their own weight and leaving the flue gas system.

[0008] To achieve the above object, the present invention provides the following technical solutions: A wet flue gas centrifugal filtration dust removal and demisting device, comprising an absorption tower, a flue gas inlet, a flue gas outlet, a spray layer, a dust removal and demisting layer, and a flushing layer; The dust removal and demisting layer is installed in the absorption tower, and is located above the spray layer and below the flue gas outlet. The dust removal and demisting layer is composed of multiple groups of centrifugal filtration dust removal and demisting units that are densely and side by side. The flushing layer is provided with a plurality of flushing nozzles, each of which corresponds one to one with the centrifugal filtration dust removal and demisting unit below it; The centrifugal filtering dust removal and demisting unit comprises an outer cylinder, an inner cylinder, a centrifugal impeller and a filtering impeller. The outer cylinder is a tubular cylinder, which is perpendicular to the horizontal plane. The inner cylinder is a tubular cylinder, which comprises a cylinder, an upper cover plate and a lower cover plate. The centrifugal impeller and the filtering impeller sleeve are embedded in the center of the outer cylinder, and the bottom surface is flush with the bottom surface of the inner cylinder. The centrifugal impeller is fixed on the lower side of the inner cylinder and is composed of n centrifugal blades arranged in a clockwise rotation in a centrosymmetric manner, where n≥3; The filtering impeller is fixed on the upper side of the inner cylinder and is composed of n centrosymmetrical filtering blades arranged counterclockwise, where n≥3, and the filtering blades are made of hollow m-mesh material, where m≥10; The centrifugal blades of the centrifugal impeller correspond to the filtering blades of the upper filtering impeller one by one and are connected to each other. The contact angle between each centrifugal blade and the corresponding filtering blade is 90°.

[0009] As a preferred embodiment, the centrifugal blades are made of airtight material.

[0010] The beneficial effects of the present invention are: 1. Centrifugal acceleration, collision interception. In the field of wet flue gas dust removal and mist removal technology, the core difficulty is the interception of fine particles and droplets. Taking wet flue gas desulfurization as an example, after the dust-containing particles enter the desulfurization absorption tower, they are intercepted by multiple layers of slurry spraying and the liquid holding layer in the tower. The particles that remain in the flue gas are because their particle size is small enough and is more strongly affected by the inertial force, and are easy to swing with the wind, causing them to escape multiple washings. In the present invention, a centrifugal impeller is used to force the flue gas to be centrifugally guided. When the flue gas passes through the centrifugal impeller, the flow rate of the channel parallel to the centrifugal blades reaches more than 3 times the vertical flow rate in the absorption tower. The higher centrifugal flow rate increases the probability of collision and condensation between droplets and particles, greatly increases the probability of particles and droplets in the flue gas being intercepted by the inner wall of the outer cylinder, and at the same time increases the probability of being intercepted by the rear liquid film, which comprehensively results in the removal of fine particles and droplets.

[0011] 2. Dynamic liquid film, filtering and interception. The filter impeller, which corresponds to the centrifugal impeller in a vertical angle, uses the droplets entrained in the wet flue gas to naturally form a dense liquid film on the hollow structure of the filter blade under the surface tension of the droplets. When the dust-containing and mist-containing flue gas accelerated by the centrifugal impeller below passes through the filter impeller, the fine particles and droplets collide, condense, and filter with the liquid film on the filter impeller at high speed. The liquid film on the filter impeller is in a dynamic state. After gathering to a certain extent, it will converge into a flow under the action of its own weight and flow back into the slurry pool of the washing tower below.

[0012] 3. Reserved channels for safe operation. In the process of filtering wet flue gas, the biggest hidden danger to operational safety is the increased resistance caused by adhesion and blockage of the filter material, tearing of the filter screen and other operational safety risks. The wet filtration designed by the present invention cleverly avoids this safety risk by utilizing a special wheel-shaped liquid film filtration form. The way to achieve this safety control is, on the one hand, a wheel-shaped design. Under special blockage conditions, the smoke will naturally bypass the filter impeller due to the increased resistance to passing through the filter impeller, and the blades of the filter impeller will intermittently pass through the impeller. On the other hand, the design of the filter blades at a certain angle can more easily help the accumulated liquid film to drain, especially when the blockage just begins to occur. In the flushing state, the blockage can more easily leave the filter impeller with the flushing water flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the overall structure of the device and system of the present invention; Figure 2 This is a schematic diagram of the structure of the centrifugal filtration dust removal and mist removal unit of the present invention; Figure 3 This is a schematic diagram of the inner cylinder structure of the present invention; Figure 4 This is a schematic diagram of the filter impeller structure of the present invention; Figure 5 It is a schematic diagram of the centrifugal impeller structure of the present invention.

[0014] Description of reference numerals: In the figure: 1-absorption tower; 2-smoke inlet; 3-smoke outlet; 4-spraying layer; 5-dust removal and demisting layer; 6-flushing layer; 7-flushing nozzle; 8-centrifugal filtration dust removal and demisting unit; 9-outer cylinder; 10-inner cylinder; 11-filter impeller; 12-centrifugal impeller; 13-cylinder body; 14-upper cover plate; 15-lower cover plate; 16-filter blades; 17-centrifugal blades. DETAILED DESCRIPTION

[0015] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features well known in the art are not described.

[0016] The connection method can be bonding, welding, bolt connection, etc., depending on actual needs.

[0017] See also Figures 1 to 5 , this embodiment includes an absorption tower 1, a smoke inlet 2, a smoke outlet 3, a spray layer 4, a dust removal and demisting layer 5, and a flushing layer 6; The dust removal and demisting layer 5 is installed in the absorption tower 1, and is located above the spray layer 4 and below the flue gas outlet 3. The dust removal and demisting layer 5 is composed of multiple groups of centrifugal filtration dust removal and demisting units 8 that are densely and side by side. The flushing layer 6 is provided with a plurality of flushing nozzles 7, each of which corresponds one to one to the centrifugal filtration dust removal and demisting unit 8 below it; The centrifugal filtering dust removal and mist removal unit 8 comprises an outer cylinder 9, an inner cylinder 10, a centrifugal impeller 12, and a filtering impeller 11. The outer cylinder 9 is a tubular cylinder, which is perpendicular to the horizontal plane. The inner cylinder 10 is also a tubular cylinder, and both comprise a cylinder body 13, an upper cover plate 14, and a lower cover plate 15. The centrifugal impeller 12 and the filtering impeller 11 are sleeved and embedded in the center of the outer cylinder 9, and the bottom surface is flush with the bottom surface of the inner cylinder 10. The centrifugal impeller 12 is fixed to the lower side of the inner cylinder 10 and is composed of n centrifugal blades 17 arranged in a clockwise rotation and symmetrically with respect to the center. The centrifugal blades 17 are made of an airtight material, wherein n≥3; The filter impeller 11 is fixed on the upper side of the inner cylinder 10 and is composed of n centrosymmetrical filter blades 16 arranged counterclockwise, where n≥3, and the filter blades 16 are made of hollow m-mesh material, where m≥10; The centrifugal blades 17 of the centrifugal impeller 12 correspond to the filtering blades 16 of the upper filtering impeller 11 one by one and are connected to each other. Each centrifugal blade 17 and the corresponding filtering blade 16 have a contact angle of 90°.

[0018] In a specific embodiment, dust-laden flue gas enters the absorption tower 1 from the flue gas inlet 2, and first passes through the wet scrubbing of the spray layer 4, where some particles are adhered and intercepted by the spray slurry of the spray layer 4, and another part of the particles that are not intercepted and the fine slurry particles sprayed by the spray layer 4 are entrained by the flue gas into the dust removal and demisting layer 5. When the flue gas passes through the dust removal and demisting layer 5, since the centrifugal filtration dust removal and demisting units 8 are densely and arranged side by side, and the gaps between them have been blocked, the flue gas can only go up through the centrifugal filtration dust removal and demisting units 8.

[0019] When the flue gas containing particles and mist drops passes through the centrifugal filtration dust removal and mist removal unit 8, the flue gas can only go up through the impeller gap between the outer cylinder 9 and the inner cylinder 10 because the inner cylinder 10 is provided with a lower cover plate 15. The flue gas first passes through the centrifugal impeller 12, and under the action of the inclined centrifugal blades 17 of the centrifugal impeller 12, the flue gas is accelerated and exhibits a clockwise centrifugal motion. During the acceleration and centrifugal process, the tiny droplets and particles collide with each other, break through the surface tension of the liquid film, condense with each other, and move toward the inner wall of the outer cylinder 9.

[0020] The dust-containing and mist-containing flue gas passing through the centrifugal impeller 12 further ascends and hits the filter blades 16 of the filter impeller 11 arranged counterclockwise with a clockwise centrifugal motion trend. Initially, the droplets are intercepted by the mesh on the filter blades 16, and adhere to the mesh of the filter blades 16 under the action of the surface tension of the liquid, and gradually form a dense liquid film on the filter blades 16. After the liquid film is formed, the subsequent dust-containing and mist-containing flue gas continues to vertically hit the liquid film on the filter blades 16 at high speed under the action of centrifugal inertia. Due to the high flow rate, the fine droplets and particulate matter in the flue gas break through the surface tension of the liquid film on the filter blades 16 and merge into the liquid film. The clean flue gas ascends through the space on the filter blades 16 that is not covered with the liquid film.

[0021] After the dust-containing droplet film gathered on the filter blades 16 is gradually accumulated, part of it, under the action of its own weight, flows back to the slurry pool of the absorption tower 1 below along the inclination angle of the filter blades 16. The other part is splashed upward by the high-speed flue gas along the inclination angle of the filter blades 16 in the form of large droplets. The upward large droplets move centrifugally toward the wall and are intercepted by the inner wall of the outer cylinder 9. Finally, they gather into a flow and also flow back to the slurry pool of the absorption tower 1.

[0022] This achieves the interception and purification of particulate matter and droplets in wet flue gas.

[0023] In addition, during the operation, the flushing layer 6 operates intermittently, generally once every 3 hours, and each time it runs for 2 minutes. The centrifugal filtration dust removal and demisting unit 8 is flushed with scale by a one-to-one flushing nozzle 7 to prevent the solid matter in the slurry from clogging the internal filter impeller 11, the centrifugal impeller 12, the inner wall of the outer cylinder 9, and the outer wall of the inner cylinder 10 of the centrifugal filtration dust removal and demisting unit 8.

[0024] It should be noted that, in this document, relational terms such as one and two are merely used to distinguish one entity or operation from another entity or operation, but do not necessarily require or imply any actual relationship or order between these entities or operations.

[0025] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A wet flue gas centrifugal filtration dust removal and demisting device, characterized in that: It comprises an absorption tower (1), a smoke inlet (2), a smoke outlet (3), a spray layer (4), a dust removal and mist removal layer (5), and a flushing layer (6); The dust removal and demisting layer (5) is installed in the absorption tower (1) and is located above the spray layer (4) and below the flue gas outlet (3). The dust removal and demisting layer (5) is composed of multiple groups of centrifugal filtration dust removal and demisting units (8) that are densely and side by side. The flushing layer (6) is provided with a plurality of flushing nozzles (7), and each flushing nozzle (7) corresponds one-to-one to a centrifugal filtering dust removal and demisting unit (8) below it; The centrifugal filtering dust removal and mist removal unit (8) comprises an outer cylinder (9), an inner cylinder (10), a centrifugal impeller (12), and a filtering impeller (11); the outer cylinder (9) is a tubular cylinder and is perpendicular to a horizontal plane; the inner cylinder (10) is also a tubular cylinder and both comprise a cylinder body (13), an upper cover plate (14), and a lower cover plate (15); the centrifugal impeller (12) and the filtering impeller (11) are sleeved and embedded in the center of the outer cylinder (9), and the bottom surface is flush with the bottom surface of the inner cylinder (10); The centrifugal impeller (12) is fixed to the lower side of the inner cylinder (10), and is composed of n centrifugal blades (17) arranged in a clockwise rotation manner and in a centrosymmetric manner, wherein n≥3; The filtering impeller (11) is fixed on the upper side of the inner cylinder (10), and is composed of n centrosymmetrical filtering blades (16) arranged counterclockwise, where n≥3, and the filtering blades (16) are made of a hollow m-mesh material, where m≥10; The centrifugal blades (17) of the centrifugal impeller (12) correspond one to one with the filtering blades (16) of the upper filtering impeller (11), and are connected to each other, and each centrifugal blade (17) has a contact angle of 90° with the corresponding filtering blade (16).

2. A wet flue gas centrifugal filtration dust removal and demisting device according to claim 1, characterized in that: The centrifugal blades (17) are made of an airtight material.

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