CFB (circulating fluidized bed) desulfurizing tower

Abstract

The utility model relates to the technical field of flue gas desulfurization, in particular to a CFB (Circulating Fluidized Bed) desulfurization tower, which comprises a tower body and a smoke box connected to the bottom of the tower body, the smoke box is communicated with the tower body through a Venturi mechanism, a throat part of a Venturi throat pipe forms a curved surface type horn mouth shape, the smoke box and the tower body are further communicated with a plurality of bypasses capable of being opened and closed respectively, and the bypass is communicated with the tower body. And the upper end of the bypass is communicated with the side wall of the tower body at an outlet above the Venturi throat pipe, so that gas entering the tower body from the Venturi throat pipe and gas entering the tower body from the bypass are converged and form upward rotational flow. Due to the design of the upper and lower asymmetric, small-angle and hyperbolic-type throat outlets, the uniform distribution effect of airflow in the desulfurization tower is better, the flow field of a desulfurization reaction area is more stable, flue gas passing through the bypass pipeline tangentially enters the tower and forms a rotating flow field with vertically upward flue gas, so that the flow field in the desulfurization tower can be stabilized, the retention time of a desulfurizing agent is prolonged, and the desulfurization efficiency is improved. Higher desulfurization efficiency is achieved, and the dual effects of stabilizing the flow field of the desulfurization tower and reducing the resistance of the desulfurization tower are achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of flue gas desulfurization, in particular to a CFB desulfurization tower. Background Art

[0002] The circulating fluidized bed flue gas purification process is to fully contact and mix the Ca(OH)2 powder added to the desulfurization tower with SO2 and other components in the flue gas, such as SO3, HCl, HF and other acidic gases. The atomized water sprayed at the entrance of the desulfurization tower reduces the flue gas temperature to ensure the best reaction conditions, and forms a liquid phase on the surface of the Ca(OH)2 particles. The Ca(OH)2 powder, flue gas and sprayed water in the desulfurization tower are fully mixed in a suspended state, and the excess Ca(OH)2 powder is circulated in the desulfurization tower for many times. Under the appropriate Ca / S ratio, the acidic gases such as SO2 and SO3 in the flue gas can be more fully absorbed.

[0003] In a circulating fluidized bed flue gas desulfurization tower, in order to ensure sufficient fluidization and suspension of the desulfurizer and fly ash in the desulfurization tower, one or several Venturi throats are generally set at the bottom of the desulfurization tower to produce a certain spraying speed, thereby forming a better flow field, which is conducive to the full mixing of the desulfurizer and fly ash particles with the flue gas in the desulfurization tower.

[0004] The practical results show that the resistance loss of the desulfurization tower increases dramatically with the increase of the flue gas velocity in the throat, and it is closely related to the shape of the inlet and outlet of the throat of the desulfurization tower. The existing throat design of the desulfurization tower generally adopts a welding design of a smaller throat diameter, a larger throat expansion angle (>30°) and a linear bell mouth. The throat design of the existing desulfurization tower has the defects of large resistance loss, poor flow field stability, and inability to adapt to changes in boiler load. For this reason, the utility model proposes a CFB desulfurization tower to solve the above problems. Utility Model Content

[0005] The utility model aims at the above-mentioned technical problems, overcomes the shortcomings of the prior art, and provides a CFB desulfurization tower, which adopts a curved bell mouth, a smaller throat expansion angle and a flue gas bypass pipe design, and utilizes the spraying effect of the curved shrinkage and the flue gas bypass in combination to reduce the operating resistance of the desulfurization tower and improve the load regulation performance of the desulfurization tower.

[0006] The CFB desulfurization tower in this scheme includes a tower body and a smoke box connected to the bottom of the tower body, the smoke box and the tower body are connected through a venturi mechanism, the venturi mechanism includes upper and lower baffles and a plurality of venturi throats evenly connected to the upper and lower baffles, the throat of the venturi throat is in the shape of a curved bell mouth, wherein the smoke box and the tower body are also connected with a plurality of bypasses that can be opened and closed respectively, the plurality of bypasses are evenly distributed in a circular shape on the outside of the tower body and the smoke box, and the upper end of the bypass is connected to the side wall of the tower body at the outlet above the venturi throat, so that the gas entering the tower body from the venturi throat is in contact with the bypass The gases entering the tower body converge and form an upward swirl. Based on the dual effects of the curved surface design of the desulfurization tower throat inlet and outlet and the small angle design of the sparging chamber outlet, the resistance loss of the flue gas passing through the desulfurization tower sparging chamber is effectively reduced, thereby realizing the low resistance characteristics of the desulfurization tower. The design of the small angle throat outlet makes the airflow in the desulfurization tower more evenly distributed, and the flow field in the desulfurization reaction zone is more stable. The flue gas entering the tower tangentially through the bypass pipe can stabilize the flow field in the desulfurization tower, prolong the residence time of the desulfurizer, and achieve a higher desulfurization efficiency. It has the dual effects of stabilizing the flow field of the desulfurization tower and reducing the resistance of the desulfurization tower.

[0007] The technical solution further defined in the utility model is:

[0008] Furthermore, the bypass is composed of straight segments and curved segments connected to form a U-shaped curved pipe with an arc as a whole, so that the flue has fewer bends, the distance is further shortened and the resistance is reduced, the flue gas flow direction has no sudden change, the energy consumption is small, and the service life of the equipment is extended.

[0009] Furthermore, it also includes a spray gun unit arranged on the side wall of the tower body and located above the venturi mechanism. The spray gun unit includes an upper spray gun mechanism and a lower spray gun mechanism arranged in layers from top to bottom. The upper spray gun mechanism and the lower spray gun mechanism are both composed of a plurality of spray guns evenly arranged in a ring shape on the side wall of the tower body. The upper and lower layers are arranged to lengthen the reaction zone, reduce flue gas escape, and enable the material bed to be evenly humidified in sections, which is beneficial to improving the utilization efficiency of the desulfurizer. The annular arrangement increases the coverage of the liquid phase to the gas and solid phases.

[0010] Furthermore, the spray guns in the upper spray gun mechanism and the lower spray gun mechanism are arranged in a staggered manner, and the double-layer staggered arrangement of the air separation can effectively cover the smoke passing through the tower body to prevent the smoke from escaping.

[0011] Furthermore, the spray gun in the spray gun unit is arranged to be inclined upward toward the inside of the tower body. When the spray gun discharges liquid, the droplets will miss a part of the area above the near end of the spray zone due to the effect of gravity. Therefore, the spray gun outlet is tilted upward at a certain angle to reduce the escape of flue gas in the spray zone and ensure the desulfurization efficiency near the end of the spray zone (i.e., the center area of ​​the tower body).

[0012] Furthermore, the spray gun in the spray gun unit is arranged to be inclined upward at 15 degrees.

[0013] Furthermore, the spray gun includes an atomizing spray gun.

[0014] Furthermore, it also includes a bag dust removal system connected to the top of the tower body, and the bottom of the bag dust removal system is connected to a weighing and returning material system connected to the tower body to return materials to the tower body.

[0015] Furthermore, a feeding pipe is installed on the side wall of the tower body to replenish the material in the tower body.

[0016] Furthermore, the smoke box is connected to the circulating flue, and the gas in the circulating flue enters the tower body through the smoke box.

[0017] The beneficial effects of the utility model are:

[0018] (1) The utility model is based on the dual effects of the curved surface design of the inlet and outlet of the desulfurization tower throat and the small angle design of the outlet of the sparging chamber. The resistance loss of the flue gas passing through the sparging chamber of the desulfurization tower is effectively reduced, thereby realizing the low resistance characteristics of the desulfurization tower. The design of the throat outlet with a small angle makes the airflow in the desulfurization tower more evenly distributed, and the flow field in the desulfurization reaction zone is more stable. The flue gas passing through the bypass pipe enters the tower tangentially, which can stabilize the flow field in the desulfurization tower, prolong the residence time of the desulfurizer, and achieve a higher desulfurization efficiency, achieving the dual effects of stabilizing the flow field of the desulfurization tower and reducing the resistance of the desulfurization tower.

[0019] (2) The utility model lengthens the reaction zone by arranging the spray guns in two layers, which reduces the smoke escape and enables the material bed to be evenly humidified in sections, which is beneficial to improving the utilization efficiency of the desulfurizer. The annular arrangement increases the coverage of the liquid phase to the gas and solid phases, and the double-layer staggered arrangement of the air separation can effectively cover the smoke passing through the tower body to prevent the smoke from escaping. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the structure of a CFB desulfurization tower in an embodiment of the utility model;

[0021] Figure 2 It is a schematic diagram of the structure of the venturi throat in the embodiment of the utility model;

[0022] Figure 3 This is a schematic diagram of the structure of the upper and lower partitions in the embodiment of the utility model;

[0023] Figure 4 This is a schematic diagram of the bypass structure in the embodiment of the utility model;

[0024] In the figure: 10, tower body; 11, smoke box; 12, venturi throat; 13, bypass; 131, straight section; 132, curved section; 14, upper and lower partitions; 20, bag dust removal system; 30, circulating flue; 40, spray gun unit; 41, lower spray gun mechanism; 42, upper spray gun mechanism; 50, feeding pipe; 60, weighing and returning feeding system. DETAILED DESCRIPTION

[0025] like Figure 1 As shown, this embodiment provides a CFB desulfurization tower, including a tower body 10 and a smoke box 11 connected to the bottom of the tower body 10, the smoke box 11 is connected to the circulating flue 30, the gas in the circulating flue 30 enters the tower body 10 through the smoke box 11, and the smoke box 11 is connected to the tower body 10 through a Venturi mechanism. Figure 2-3 As shown, the Venturi mechanism specifically includes upper and lower baffles 14 and seven Venturi throats 12 evenly connected to the upper and lower baffles 14, and the throat of the Venturi throat 12 forms a curved bell-mouth shape. The smoke box 11 and the tower body 10 are also connected with four bypasses 13 that can be opened and closed respectively, and each bypass 13 is respectively provided with a valve for control. The four bypasses 13 are evenly distributed on the outside of the tower body 10 and the smoke box 11 in a circular shape, and the upper end of the bypass 13 is connected to the side wall of the tower body 10 at the upper outlet of the Venturi throat 12, so that the gas entering the tower body 10 from the Venturi throat 12 and the gas entering the tower body 10 from the bypass 13 can merge and form a swirl upward. The design of the upper and lower asymmetric, small-angle, hyperbolic throat outlet makes the airflow in the desulfurization tower more evenly distributed, and the flow field in the desulfurization reaction zone is more stable. A part of the flue gas is used as swirl fluidizing wind, which is led out through the bypass 13 and injected tangentially above the gradually expanding section of the Venturi tube, transforming the single Venturi tube direct flow fluidization into direct / swirl composite fluidization. After adding a part of the Venturi fluidizing wind as swirl fluidizing wind, the airflow can carry more particles, and the strong rotational momentum enhances the suspension ability of the particles, prolongs the residence time of the particles in the desulfurization tower, and reduces the entrainment loss. Therefore, it is easier to maintain a high particle concentration in the tower, and the internal circulation of the particles is enhanced, the desulfurization efficiency is improved accordingly, the mass transfer and heat transfer efficiency are enhanced, and the desulfurization products are prevented from moving to the wall, reducing or even avoiding the occurrence of wall sticking.

[0026] See also Figure 4 The bypass 13 is composed of a plurality of straight segments 131 and curved segments 132 connected to form a U-shaped curved tube shape as a whole.

[0027] The CFB desulfurization tower of this embodiment also includes a spray gun unit 40 arranged on the side wall of the tower body 10 and located above the venturi mechanism. The spray gun unit 40 specifically includes an upper spray gun mechanism 42 and a lower spray gun mechanism 41 arranged in layers from top to bottom. The upper spray gun mechanism 42 and the lower spray gun mechanism 41 are both composed of a plurality of spray guns uniformly arranged in a ring shape on the side wall of the tower body 10.

[0028] In this embodiment, the spray guns in the spray gun unit 40 are all inclined upward at 15 degrees toward the inside of the tower body 10 .

[0029] It should be noted that, in this embodiment, the number of spray guns in the lower spray gun mechanism 41 is three, the number of spray guns in the upper spray gun mechanism 42 is two, and the spray guns in the upper spray gun mechanism 42 and the lower spray gun mechanism 41 are staggered. The spray guns are specifically atomizing spray guns. Since the lower layer is close to the dense phase area, the water mist is more than the upper layer. During graded cooling, the lower layer is closer to the original flue gas and the high-efficiency reaction zone. Therefore, the number of spray guns in the upper layer is less than the number of spray guns in the lower layer.

[0030] The CFB desulfurization tower of this embodiment also includes a bag dust removal system 20 connected to the top of the tower body 10, and the bottom of the bag dust removal system 20 is connected to a weighing and returning system 60 connected to the tower body 10 to return materials to the tower body 10. A feeding pipe 50 is installed on the side wall of the tower body 10 to replenish the material in the tower body 10, and a feeding and returning area is formed at the bottom of the tower body 10.

[0031] In a specific embodiment, the tower body 10 includes a feed return zone, a sufficient mixing zone, an optimal reaction zone, a secondary reaction zone and a drying zone from bottom to top. The feed return zone is located above the venturi mechanism and the bypass 13, and is returned by the weighing and returning feeding system 60, and is supplemented by external feeding from the feeding pipe 50. The sufficient mixing zone is located above the feed return zone and below the spray gun, the optimal reaction zone is located in the two-layer spray gun area, and the drying zone is located above the tower body 10 and close to the outlet position.

[0032] It should be noted that, since the desulfurizer stays in the desulfurization tower for a short time, most of the newly added desulfurizer enters the post-dust collector from the top outlet of the desulfurization tower together with the flue gas. The desulfurization ash collected by the dust collector contains a large amount of unreacted desulfurizer, and it is necessary to return the desulfurization ash to the desulfurization tower for reuse through a return device (called the return feed system 60), so as to achieve a higher desulfurization efficiency at a lower calcium-sulfur ratio.

[0033] In a specific embodiment, the bag-type dust removal system 30 can specifically be one or more bag-type dust collectors, and the dust collector ash hopper can be designed as a weighing-type ash hopper, which avoids the phenomenon of unstable desulfurization tower bed pressure and unstable desulfurization efficiency caused by the low ash volume control accuracy of the traditional ship-type ash hopper. A level meter can also be set on the ash hopper. The combination of the weighing instrument and the level meter can improve the accuracy of ash volume control in the ash hopper, and cooperate with the adjustable return flow valve to form a weighing return system 60, which adjusts the return volume according to the load or sulfur dioxide content to improve the system stability.

[0034] It should be noted that the four bypasses 13 in this embodiment can be opened and closed respectively, and the load can be adjusted according to the flue gas flow entering the smoke box 11 from the circulating flue 30. If the bypass 13 is equipped with an automatic valve and interlocked with the boiler load, the load signal can be automatically tracked and automatically adjusted according to the boiler load to meet the optimal requirements of stable operation of the desulfurization tower and circulating fluidization in the tower when running at low load. In the FLUNENT simulation, the desulfurization tower has a good flow field and low pressure loss. The operating resistance can be adjusted according to different operating loads, which improves the adaptability to the load. The boiler load can reach as low as 35% and can still operate normally, and the operating resistance is low and the energy consumption is small.

[0035] In addition to the above embodiments, the present invention may also have other implementations. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. A CFB desulfurization tower, comprising a tower body (10) and a smoke box (11) connected to the bottom of the tower body (10), characterized in that: The smoke box (11) is connected to the tower body (10) through a Venturi mechanism, the Venturi mechanism comprising upper and lower baffles (14) and a plurality of Venturi throats (12) uniformly connected to the upper and lower baffles (14), the throat of the Venturi throat (12) forming a curved bell-mouth shape, wherein the smoke box (11) and the tower body (10) are further connected to a plurality of bypasses (13) which can be opened and closed respectively, the plurality of bypasses (13) being uniformly distributed in a circular shape on the outside of the tower body (10) and the smoke box (11), and the upper end of the bypass (13) being connected to the side wall of the tower body (10) at the upper outlet of the Venturi throat (12), so that the gas entering the tower body (10) from the Venturi throat (12) and the gas entering the tower body (10) from the bypass (13) merge and form a swirling flow upward.

2. The CFB desulfurization tower according to claim 1, characterized in that: The bypass (13) is composed of a straight section (131) and a curved section (132) connected together, so that the whole is formed into a U-shaped curved pipe with an arc.

3. The CFB desulfurization tower according to claim 1, characterized in that: It also includes a spray gun unit (40) arranged on the side wall of the tower body (10) and located above the venturi mechanism, the spray gun unit (40) comprising an upper spray gun mechanism (42) and a lower spray gun mechanism (41) arranged in layers from top to bottom, the upper spray gun mechanism (42) and the lower spray gun mechanism (41) both consisting of a plurality of spray guns evenly arranged in an annular shape on the side wall of the tower body (10).

4. The CFB desulfurization tower according to claim 3, characterized in that: The spray guns in the upper spray gun mechanism (42) and the lower spray gun mechanism (41) are arranged alternately.

5. The CFB desulfurization tower according to claim 3, characterized in that: The spray gun in the spray gun unit (40) is arranged to be inclined upward toward the inside of the tower body (10).

6. The CFB desulfurization tower according to claim 5, characterized in that: The spray gun in the spray gun unit (40) is arranged to be inclined upward at 15 degrees.

7. The CFB desulfurization tower according to claim 3, characterized in that: The spray gun comprises an atomizing spray gun.

8. The CFB desulfurization tower according to claim 1, characterized in that: It also includes a bag dust removal system (20) connected to the top of the tower body (10), and a weighing and returning material system (60) is connected to the bottom of the bag dust removal system (20) and is connected to the tower body (10) to return material to the tower body (10).

9. The CFB desulfurization tower according to claim 1, characterized in that: A feeding pipe (50) is installed on the side wall of the tower body (10) to replenish the material in the tower body (10).

10. The CFB desulfurization tower according to claim 1, characterized in that: The smoke box (11) is in communication with the circulating smoke duct (30), and the gas in the circulating smoke duct (30) enters the tower body (10) through the smoke box (11).

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