Semi-dry circulating fluidized bed desulfurizing tower

Abstract

The utility model discloses a semi-dry method circulating fluidized bed desulfurizing tower. The desulfurization tower at least comprises a desulfurization tower inlet section, a Venturi tube group, a divergent section, a straight tube section and an outlet section which are sequentially and continuously arranged from bottom to top, a new desulfurizing agent feeding hole and / or a circulating ash feeding hole are / is formed in the downstream end of the inlet section of the desulfurizing tower; a rotational flow flue gas bypass pipe is arranged between the upstream end of the inlet section of the desulfurizing tower and the diverging section, and bypass flue gas horizontally enters the diverging section of the desulfurizing tower along the tangential direction from the flue gas bypass pipe. According to the utility model, the flue gas bypass pipe enters along the tangential direction to form a rotational flow effect, so that gas flow and a desulfurizing agent in the tower spirally rise, and the retention time is prolonged compared with pure straight flow. Meanwhile, under the action of centrifugal force of rotational flow, the desulfurizing agent is thrown to the periphery of the desulfurizing tower and decelerated in the rising process, and then falls back to the divergent section, so that the proportion of the internal circulation desulfurizing agent is increased.

Description

Technical Field

[0001] The utility model relates to a semi-dry circulating fluidized bed desulfurization tower. Background Art

[0002] According to the morphological characteristics of the desulfurizer and the desulfurization product, industrial flue gas desulfurization technology can be divided into three categories: wet method, dry method and semi-dry method. Among them, the semi-dry method has some characteristics of both the dry method and the wet method. The characteristic of this technology is the joint reaction in the three phases of gas, liquid and solid. The water in the wet desulfurizer is evaporated by the waste heat of the flue gas, and the final product is dry. Circulating fluidized bed desulfurization is a typical semi-dry flue gas desulfurization technology. It is based on the principle of circulating fluidized bed and uses slaked lime powder Ca(OH)2 as the absorbent. This technology sprays atomized water into the desulfurization tower, and through the internal circulation of the absorbent in the tower and multiple external circulations, the absorbent and the flue gas pollutants are fully contacted and reacted, thereby achieving a higher desulfurization efficiency.

[0003] Circulating fluidized bed flue gas desulfurization is currently widely used in power plant boilers, steel sintering and pelletizing flue gas purification and other fields. Compared with wet and dry desulfurization, it has the advantages of small footprint, no secondary pollution of wastewater, no need for equipment anti-corrosion, and low operating costs. When the Ca / S ratio of this technology is 1.3-1.5, the desulfurization efficiency can reach more than 95%, but compared with wet desulfurization, the desulfurization efficiency is slightly lower, and when the SO2 concentration in the flue gas is high, the Ca / S ratio needs to be increased to ensure that the outlet SO2 concentration meets the emission standards, resulting in increased operating costs.

[0004] In a traditional circulating fluidized bed desulfurization tower, the flue gas is accelerated through the Venturi section and then enters the gradually expanding section of the tower body. Under the action of the airflow, the solid desulfurizer at the center of the tower body gradually decreases in speed as it moves upward. When it rises to a certain height, a small part of the material falls back along the periphery of the tower, thus forming a fluidized bed layer with internal circulation. Since the overall movement direction of the absorbent in the desulfurization tower is vertically upward, the single residence time is limited by the tower height, and most of the desulfurizer leaves the tower with the airflow before reacting. In order to improve the utilization rate of the desulfurizer, a dust removal device is usually set downstream of the desulfurization tower, and most of the desulfurization ash captured by the dust removal device is returned to the interior of the desulfurization tower through the material circulation system, thereby increasing the total residence time. However, this will cause a large operating load on the subsequent dust removal equipment, thereby increasing the floor space and investment cost of the dust removal equipment.

[0005] In addition, due to the low flue gas flow rate around the tower, when the proportion of process water sprayed into the desulfurization tower is inappropriate, the wet desulfurizer will easily form on the wall inside the tower, affecting the stability of the desulfurization tower operation. Utility Model Content

[0006] In order to overcome the above defects, the purpose of the utility model is to provide a semi-dry circulating fluidized bed desulfurization tower to solve the problems of short residence time of desulfurizer and easy wall formation of desulfurizer in traditional circulating fluidized bed desulfurization tower.

[0007] To achieve the above-mentioned purpose, the semi-dry circulating fluidized bed desulfurization tower of the utility model at least comprises a desulfurization tower inlet section, a venturi tube group, a gradually expanding section, a straight section, and an outlet section which are arranged successively from bottom to top;

[0008] A desulfurizing agent fresh material feed port and / or a circulating ash feed port are provided at the downstream end of the desulfurizing tower inlet section;

[0009] A swirl flue gas bypass pipe is arranged between the upstream end of the desulfurization tower inlet section and the gradually expanding section, and the bypass flue gas enters the gradually expanding section of the desulfurization tower from the flue gas bypass pipe along a tangential horizontal direction.

[0010] Furthermore, the inlet section of the desulfurization tower includes a square flue, a transition flue and a circular flue connected in sequence; the square flue includes a 90° elbow, and the flue gas inlet is located on the horizontal square flue in front of the 90° elbow.

[0011] Furthermore, the venturi tube group comprises 1 to 7 symmetrically distributed venturi tubes, the lower inlet of the venturi tube is connected to the circular flue of the inlet section of the desulfurization tower, and the upper outlet is connected to the gradually expanding section of the desulfurization tower.

[0012] Furthermore, the gradually expanding section of the desulfurization tower is a conical barrel structure that is thicker at the top and thinner at the bottom.

[0013] Furthermore, the inlet of the cyclone flue gas bypass pipe is arranged on the side wall of the horizontal square flue of the desulfurization tower inlet section, and the outlet is located at the desulfurization tower expansion section, and the flue gas enters the desulfurization tower expansion section horizontally along the tangential direction from the bypass.

[0014] Furthermore, the desulfurizing agent fresh material feed port and the circulating ash feed port are arranged at the circular flue of the inlet section of the desulfurizing tower.

[0015] Furthermore, a bypass regulating valve is provided on the cyclonic flue gas bypass pipe for regulating the flow of the flue gas bypass pipe.

[0016] Furthermore, a flow guide device is provided in the 90° elbow of the square flue at the inlet section of the desulfurization tower.

[0017] Furthermore, the inlet of the cyclone flue gas bypass pipe is arranged upstream of the desulfurization tower inlet section guide device, and the horizontal distance between the bypass inlet center and the first guide device center is greater than the larger side length of the square flue cross section of the desulfurization tower inlet section.

[0018] Furthermore, the angle between the swirl flue gas bypass pipe and the side wall of the flue at the inlet section of the desulfurization tower is 15° to 45°.

[0019] Furthermore, the desulfurization tower is provided with 2 to 3 cyclone flue gas bypass pipes, and the inlets of the flue gas bypass pipes are symmetrically distributed along the vertical center line on the cross section of the horizontal flue of the desulfurization tower inlet section;

[0020] Furthermore, 1 to 2 branch pipes are arranged at the outlet of each flue gas bypass pipe, all the branch pipes are tangent to the gradually expanding section of the desulfurization tower, and are centrally symmetrically distributed on the horizontal cross section.

[0021] To achieve the above object, the utility model provides a semi-dry circulating fluidized bed desulfurization tower desulfurization method, comprising the following steps:

[0022] A portion of the flue gas at the inlet section of the desulfurization tower enters the gradually expanding section of the desulfurization tower along the tangential horizontal direction through the flue gas bypass pipe, so that the flue gas and desulfurizer in the desulfurization tower have an additional tangential swirl on the basis of the original straight flow; under the action of the swirl, the air flow and desulfurizer in the tower rise in a spiral, which increases the residence time compared with pure straight flow; and under the action of the centrifugal force of the swirl, more desulfurizer is thrown to the periphery of the desulfurization tower and decelerated during the rising process, and then falls back to the gradually expanding section, thereby increasing the proportion of internal circulation desulfurizer.

[0023] The utility model has the following beneficial effects:

[0024] 1) A flue gas bypass pipe is set between the inlet section and the gradually expanding section of the desulfurization tower. The flue gas in the bypass can achieve natural flow under the pressure difference without the need for an additional power device. Part of the flue gas at the inlet section of the desulfurization tower enters the gradually expanding section of the desulfurization tower through the bypass along the tangential horizontal direction, so that the flue gas and desulfurizer in the desulfurization tower have an additional tangential swirl on the basis of the original straight flow. Under the action of the swirl, the airflow and desulfurizer in the tower spiral upward, which increases the residence time compared to the pure straight flow. On the other hand, under the centrifugal force of the swirl, more desulfurizer is thrown to the periphery of the desulfurization tower and decelerated during the ascent, and then falls back to the gradually expanding section, thereby increasing the proportion of the internal circulation desulfurizer. While keeping the Ca / S ratio and the utilization rate of the desulfurizer unchanged, the proportion of the external circulation desulfurizer, that is, the circulating ash, can be appropriately reduced, thereby reducing the load of the subsequent dust removal device and reducing the land occupation and investment cost of the dust removal device. If the external circulation ratio remains unchanged, the introduction of swirl into the desulfurization tower through the bypass prolongs the total residence time of the desulfurizer, allowing the desulfurizer to react more fully with the pollutants in the flue gas and improving the utilization rate of the desulfurizer, thereby reducing the Ca / S ratio or improving the desulfurization efficiency while maintaining the Ca / S ratio.

[0025] 2) Introducing tangential swirling flue gas in the gradual expansion section of the desulfurization tower can enhance the scouring effect of the flue gas on the inner wall of the desulfurization tower, and make the desulfurizer easier to break under the action of tangential force, reduce the risk of desulfurizer wall formation due to improper use of process water, and improve the operating stability of the desulfurization tower. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1It is a structural schematic axonometric diagram of an embodiment of a desulfurization tower of the utility model.

[0027] Figure 2 It is a schematic front view of the structure of an embodiment of a desulfurization tower of the utility model.

[0028] In the figure: 1. Desulfurization tower inlet section; 2. Venturi tube group; 3. Gradual expansion section; 4. Straight section; 5. Exit section; 6. Desulfurization agent new material feeding port; 7. Circulating ash feeding port; 8. Process water spray gun; 9. Cyclone flue gas bypass pipe; 10. Bypass regulating valve. DETAILED DESCRIPTION

[0029] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0030] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, unless otherwise specified, "plurality" means two or more.

[0031] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] The semi-dry circulating fluidized bed desulfurization tower of the utility model comprises at least a desulfurization tower inlet section, a venturi tube group, a gradually expanding section, a straight section and an outlet section which are arranged successively from bottom to top in sequence; a desulfurization agent new material feed port and / or a circulating ash feed port are arranged at the downstream end of the desulfurization tower inlet section; a swirl flue gas bypass pipe is arranged between the upstream end of the desulfurization tower inlet section and the gradually expanding section, and the bypass flue gas enters the desulfurization tower gradually expanding section from the flue gas bypass pipe along the tangential direction horizontally.

[0033] A flue gas bypass pipe is set between the inlet section and the gradually expanding section of the desulfurization tower. The flue gas in the bypass can achieve natural flow under the pressure difference without the need for an additional power device. A part of the flue gas in the inlet section of the desulfurization tower enters the gradually expanding section of the desulfurization tower through the bypass along the tangential horizontal direction, so that the flue gas and desulfurizer in the desulfurization tower have an additional tangential swirl on the basis of the original straight flow. Under the action of the swirl, the airflow and desulfurizer in the tower spiral upward, which increases the residence time compared to pure straight flow. On the other hand, under the centrifugal force of the swirl, more desulfurizer is thrown to the periphery of the desulfurization tower and decelerated during the ascent, and then falls back to the gradually expanding section, thereby increasing the proportion of internal circulation desulfurizer. While keeping the Ca / S ratio and the utilization rate of the desulfurizer unchanged, the proportion of the external circulation desulfurizer, that is, the circulating ash, can be appropriately reduced, thereby reducing the load of the subsequent dust removal device and reducing the land occupation and investment cost of the dust removal device. If the external circulation ratio remains unchanged, the introduction of swirl into the desulfurization tower through the bypass prolongs the total residence time of the desulfurizer, allowing the desulfurizer to react more fully with the pollutants in the flue gas and improving the utilization rate of the desulfurizer, thereby reducing the Ca / S ratio or improving the desulfurization efficiency while maintaining the Ca / S ratio.

[0034] 2) Introducing tangential swirling flue gas in the gradual expansion section of the desulfurization tower can enhance the scouring effect of the flue gas on the inner wall of the desulfurization tower, and make the desulfurizer easier to break under the action of tangential force, reduce the risk of desulfurizer wall formation due to improper use of process water, and improve the operating stability of the desulfurization tower.

[0035] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0036] Example 1

[0037] A semi-dry circulating fluidized bed desulfurization tower comprises a desulfurization tower inlet section 1, a venturi tube group 2, a gradually expanding section 3, a straight section 4, an outlet section 5, a desulfurization agent new material feed port 6, a circulating ash feed port 7, a process water spray gun 8, a cyclone flue gas bypass pipe 9, and a bypass regulating valve 10. The desulfurization tower inlet section 1 comprises a square flue, a transition flue and a circular flue connected in sequence; the square flue comprises a 90° elbow, and the flue gas inlet is located on the horizontal square flue before the 90° elbow. A venturi tube 2 is arranged at the end of the circular flue of the desulfurization tower inlet section 1, and the outlet of the venturi tube 2 is connected to the gradually expanding section 3. After most of the flue gas enters the desulfurization tower inlet section 1, it flows through the venturi tube 2, the gradually expanding section 3 and the straight section 4 in sequence, and finally discharges the desulfurization tower through the outlet section 5.

[0038] The desulfurizer fresh material feeding port 6 and the circulating ash feeding port 7 are arranged at the circular flue of the desulfurization tower inlet section 1. The desulfurizer entering the desulfurization tower inlet section 1 is accelerated together with the flue gas through the venturi tube 2 and enters the gradually expanding section 3, and forms a fluidized bed in the gradually expanding section 3 and the straight section 4. The gradually expanding section 3 is provided with a process water spray gun 8 for spraying water into the flue gas to promote the desulfurization reaction.

[0039] The desulfurization tower is provided with two cyclone flue gas bypass pipes 9, the inlet of the bypass is located on the horizontal square flue side wall of the desulfurization tower inlet section 1, and the outlet pipe of each flue gas bypass pipe 9 is horizontally tangent to the desulfurization tower expansion section 3. A small part of the flue gas entering the desulfurization tower enters the expansion section 3 tangentially through the cyclone flue gas bypass pipe 9, so that a cyclone is formed in the expansion section 3 and the straight section 4. The outlets of the flue gas bypass pipe 9 on the expansion section 3 are symmetrically distributed on the horizontal cross section to prevent the flue gas from generating biased flow.

[0040] Example 2

[0041] A semi-dry circulating fluidized bed desulfurization tower comprises a desulfurization tower inlet section 1, a venturi tube group 2, a gradually expanding section 3, a straight section 4, an outlet section 5, a desulfurization agent new material feed port 6, a circulating ash feed port 7, a process water spray gun 8, a cyclone flue gas bypass pipe 9, and a bypass regulating valve 10. The desulfurization tower inlet section 1 comprises a square flue, a transition flue and a circular flue connected in sequence; the square flue comprises a 90° elbow, and the flue gas inlet is located on the horizontal square flue before the 90° elbow. A venturi tube group 2 is arranged at the end of the circular flue of the desulfurization tower inlet section 1, and the venturi tube group 2 comprises 7 symmetrically distributed venturi tubes. The outlet of the venturi tube group 2 is connected to the gradually expanding section 3. After most of the flue gas enters the desulfurization tower inlet section 1, it flows through the venturi tube group 2, the gradually expanding section 3 and the straight section 4 in sequence, and finally discharges the desulfurization tower through the outlet section 5.

[0042] The desulfurizer fresh material feeding port 6 and the circulating ash feeding port 7 are arranged at the circular flue of the desulfurization tower inlet section 1. The desulfurizer entering the desulfurization tower inlet section 1 is accelerated together with the flue gas through the venturi tube 2 and enters the gradually expanding section 3, and forms a fluidized bed in the gradually expanding section 3 and the straight section 4. The gradually expanding section 3 is provided with a process water spray gun 8 for spraying water into the flue gas to promote the desulfurization reaction.

[0043] The desulfurization tower is provided with two cyclone flue gas bypass pipes 9, the inlet of the bypass is located on the horizontal square flue side wall of the inlet section 1 of the desulfurization tower, and the outlet section of each flue gas bypass pipe 9 is provided with two branch pipes, which are horizontally tangent to the desulfurization tower expansion section 3. A small part of the flue gas entering the desulfurization tower enters the expansion section 3 tangentially through the cyclone flue gas bypass pipe 9, so that a cyclone is formed in the expansion section 3 and the straight section 4. The four outlets of the flue gas bypass pipe 9 on the expansion section 3 are centrally symmetrically distributed on the horizontal cross section to prevent the flue gas from biasing.

[0044] The utility model is described in detail above in conjunction with the accompanying drawings, but the utility model is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the field without departing from the purpose of the utility model. Many other changes and modifications that do not depart from the concept and scope of the utility model should be considered as the protection scope of the utility model.

[0045] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the utility model, which should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.

Claims

1. A semi-dry circulating fluidized bed desulfurization tower, characterized in that: At least including a desulfurization tower inlet section, a venturi tube group, a gradually expanding section, a straight section, and an outlet section which are arranged successively from bottom to top; A desulfurizing agent fresh material feed port and / or a circulating ash feed port are provided at the downstream end of the desulfurizing tower inlet section; A swirl flue gas bypass pipe is arranged between the upstream end of the desulfurization tower inlet section and the gradually expanding section, and the bypass flue gas enters the gradually expanding section of the desulfurization tower from the flue gas bypass pipe along a tangential horizontal direction.

2. The semi-dry circulating fluidized bed desulfurization tower according to claim 1, characterized in that: The desulfurization tower inlet section includes a square flue, a transition flue and a circular flue connected in sequence; the square flue includes a 90° elbow, and the flue gas inlet is located on the horizontal square flue in front of the 90° elbow.

3. The semi-dry circulating fluidized bed desulfurization tower according to claim 2, characterized in that: The venturi tube group comprises 1 to 7 symmetrically distributed venturi tubes, the lower inlet of the venturi tube is connected to the circular flue of the inlet section of the desulfurization tower, and the upper outlet is connected to the gradually expanding section of the desulfurization tower.

4. The semi-dry circulating fluidized bed desulfurization tower according to claim 2, characterized in that: The inlet of the cyclone flue gas bypass pipe is arranged on the side wall of the horizontal flue of the inlet section of the desulfurization tower.

5. The semi-dry circulating fluidized bed desulfurization tower according to claim 2, characterized in that: The desulfurizing agent new material feed port and the circulating ash feed port are arranged at the circular flue of the inlet section of the desulfurizing tower.

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