Multi-stage dense-phase collaborative absorption system applicable to flue gas with high-concentration pollutants and high fluctuations

Abstract

A multi-stage and multi-cycle absorption tower, comprising: more than two absorption towers, a bag filter, a humidifying device and a new ash bin; each absorption tower is provided with an air inlet and an air outlet, the air outlet of the previous absorption tower is communicated with the air inlet of the next absorption tower, and the absorption towers are sequentially communicated in series; the new ash bin is communicated with the first absorption tower, and a humidifying device is arranged between the new ash bin and the first absorption tower; the last absorption tower is communicated with the inlet of the bag filter, the bag filter is arranged above the absorption tower, and the ash hopper of the bag filter is communicated with the absorption tower through the humidifying device. This absorption tower is applicable to high-temperature, high-concentration, high-fluctuation and high-humidity flue gas containing acid and dust, especially industrial furnace waste gas and hazardous waste disposal, etc.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas treatment, and particularly to a multi-stage absorption system, and more specifically, to a multi-stage multi-cycle absorption system with multi-point humidification and multi-point ash discharge. Background Art

[0002] In recent years, the treatment of air pollution has been a research hotspot. The flue gas generated during industrial kiln furnaces and hazardous waste incineration contains acidic gases, dioxins, heavy metals and other harmful gases. If these harmful gases are not treated, they will cause serious pollution to the environment. Therefore, flue gas deacidification is very necessary. The traditional deacidification device generally includes a tower body arranged vertically, with a flue gas inlet and a flue gas outlet at the bottom and top of the tower body respectively, and an alkali liquid spray nozzle on the side wall of the tower body above the flue gas inlet. When this deacidification device operates, the flue gas entering the tower body from the flue gas inlet passes through the inner cavity of the tower body from bottom to top under the action of a fan, and at the same time, the alkali liquid is sprayed into the tower body from the alkali liquid spray nozzle by using high-pressure air. The freshly entered alkali liquid in the tower body is used to contact the flue gas to achieve the purpose of removing acidic gases. Due to the limited height of the tower body, the alkali liquid entering the tower body quickly discharges from the flue gas outlet outside the tower body after a short contact with the flue gas. The contact time between the alkali liquid and the flue gas is short, and the deacidification effect is poor, making it difficult to significantly reduce the pollution to the atmosphere.

[0003] The existing dry deacidification reaction tower also has problems such as uneven flue gas flow field in the tower, which is not conducive to the mixing of the deacidifying agent and the flue gas, short residence time of the deacidifying agent, sedimentation in the tower, and low utilization rate of the deacidifying agent. Therefore, it is urgent to design a deacidification device with high deacidification efficiency, good deacidification effect and economic applicability. Summary of the Invention

[0004] One object of the present application is to improve the deacidification efficiency of flue gas.

[0005] Another object of the present application is to be able to remove acidic gases from high-concentration acidic and high-temperature flue gas.

[0006] To achieve the above objects, the multi-stage absorption system of the present application includes: two (including) or more absorption towers, a bag filter, a humidifying device, and a new ash bin;

[0007] Each absorption tower is provided with an air inlet and an air outlet. The air outlet of the previous absorption tower is communicated with the air inlet of the next absorption tower, and the absorption towers are sequentially connected in series;

[0008] The new ash bin is communicated with the first absorption tower, and a humidifying device is arranged between the new ash bin and the first absorption tower;

[0009] The last absorption tower is connected to the inlet of the bag filter. The bag filter is arranged above the absorption tower. The ash hopper of the bag filter is connected to the absorption tower. A humidifying device is provided between the outlet of the bag filter and the absorption tower.

[0010] Placing the absorption tower under the dust collector allows the materials in the dust collector to directly return to the absorption tower for further acid removal, improving the acid removal efficiency.

[0011] An outlet is provided at the lower part of each absorption tower. The outlet is connected to the absorption tower through an external pipeline. The sinking materials at the bottom of the absorption tower can be circulated and transported back into the absorption tower.

[0012] The multi-stage absorption system further includes a waste ash bin. The outlet of each absorption tower is connected to the waste ash bin through a pipeline.

[0013] A switching valve is provided at the outlet to control whether the materials discharged from the outlet are sent to the waste ash bin or circulated into the absorption tower.

[0014] The multi-stage absorption system of the present application effectively removes acidic substances, heavy metals, dioxins, etc. in the flue gas through multi-point humidification, multi-stage, and multi-cycle, and increases the flue gas treatment capacity and the device's ability to handle highly fluctuating flue gas. Description of the Drawings

[0015] Figure 1 It is a schematic structural diagram of a multi-stage absorption system of the present invention.

[0016] Figure 2 It is a schematic structural diagram of a stirring assembly of the present invention

[0017] Figure 3 It is a schematic structural diagram of another stirring assembly of the present invention

[0018] Wherein: 1 - fresh ash bin; 2 - humidifying device; 3 - turbulence component; 4 - absorption tower body; 5 - ash discharge valve; 6 - Roots blower; 7 - bag filter; 9 - activated carbon bin; 31 - main shaft; 32 - stirring chain. Detailed Description of the Invention

[0019] The following further details a multi-stage absorption system of the present application. It does not limit the protection scope of the present application, and its protection scope is defined by the claims. Certain disclosed specific details provide a comprehensive understanding of each disclosed embodiment. However, those skilled in the relevant art know that embodiments can also be implemented without one or more of these specific details and by using other materials, etc.

[0020] Unless otherwise required by the context, in the description and claims, the terms "comprising", "including" shall be understood in an open, inclusive sense, that is, "including, but not limited to".

[0021] In this specification, the numerical range expressed as "numerical value A to numerical value B" means a range including the endpoint numerical values A and B.

[0022] In this specification, the numerical range expressed as "above" or "below" means a numerical range including this number.

[0023] The "embodiment", "one embodiment", "another embodiment", or "certain embodiments" mentioned in the specification mean that the specifically described features, structures, or characteristics related to the embodiment are included in at least one embodiment. Therefore, it is not necessary for the "embodiment", "one embodiment", "another embodiment", or "certain embodiments" to all refer to the same embodiment. Moreover, the specific features, structures, or characteristics can be combined in any manner in one or more embodiments. Each feature disclosed in the specification can be replaced by an alternative feature that provides the same, equivalent, or similar purpose. Therefore, unless otherwise specified, the disclosed features are only general examples of equivalent or similar features.

[0024] For the experimental methods without specific conditions indicated in the following examples, they are generally carried out under conventional conditions or according to the conditions recommended by the manufacturer. Unless otherwise stated, all percentages, ratios, proportions, or parts are by weight.

[0025] In the present application, the inventors found that in the prior art flue gas deacidification processes, whether dry processes, wet processes, or semi-dry processes, there are different defects. As mentioned in the background art, problems such as low acid removal efficiency and low utilization rate of the deacidifying agent exist. After years of research, the inventors proposed a multi-stage absorption system, which improves the acid removal efficiency and the utilization rate of the deacidifying agent, and has a wide range of applications.

[0026] The multi-stage absorption system of the present application includes: two (including) or more absorption towers, a bag filter, a humidifying device, and a new ash bin; each absorption tower is provided with an air inlet and an air outlet, the air outlet of the previous absorption tower is communicated with the air inlet of the next absorption tower, and the absorption towers are sequentially communicated in series; the new ash bin is communicated with the first absorption tower, and a humidifying device is arranged between the new ash bin and the first absorption tower; the last absorption tower is connected to the inlet of the bag filter, the bag filter is arranged above the absorption tower, the outlet of the bag filter is communicated with the absorption tower, and a humidifying device is arranged between the outlet of the bag filter and the absorption tower.

[0027] In the system of the present application, the deacidifying agent and the amount of humidification water in the absorption tower are quantitatively added according to the flue gas conditions (for example, the moisture content in the flue gas, etc.). The humidified deacidifying agent, on the one hand, absorbs the moisture in the flue gas, plays a role in regulating the humidity, and avoids bag sticking. On the other hand, it dilutes and wraps the dust entrained in the flue gas, and avoids the caking of sticky dust in the tower. Controlling the humidity of the deacidifying agent in this way can absorb acidic gases on the one hand and avoid corrosion in the tower. Generally, the water content in the flue gas is 5-50 wt%. Preferably, the water content in the flue gas is 15-40 wt%.

[0028] The humidifying device is used to mix the mixed solid deacidifying agent and the liquid to form a solid deacidifying agent containing 1-9 wt% of water. The higher the pollutant concentration in the flue gas, the higher the water ratio.

[0029] In some embodiments, the water content of the humidified solid deacidifying agent is 3-5 wt%.

[0030] In the present application, the flue gas discharged from industrial furnaces or other incineration equipment has a certain temperature (usually 90-280 °C, and more often higher than 100 °C), and can be directly introduced into the absorption tower of the present application for deacidification treatment. By mixing the deacidifying agent with a certain humidity (1-9 wt%) and the hot flue gas, the water film on the particle surface is gradually dried, and it is easy to contact and react in a suspended state. It will not be like the particles with high humidity or agglomeration that will fall to the bottom of the tower.

[0031] In some embodiments, the deacidifying agent includes a mixture of one or more substances selected from calcium carbonate, calcium oxide, calcium hydroxide, sodium carbonate, and zinc oxide.

[0032] In a preferred manner, in the solid deacidifying agent, more than 85% of the particle size distribution is in the range of 200-325 mesh.

[0033] A flow disturbing component, also called a stirring component, is installed in each absorption tower.

[0034] In some embodiments, the flow disturbing component of the present application includes a main shaft and a stirring chain, and the stirring chain is connected to the main shaft.

[0035] The cross-section of the main shaft can be circular, quadrilateral, hexagonal, or other shapes.

[0036] The stirring chain refers to a flexible, rope-like component with a certain length. A chain-like stirring chain made of stainless steel, manganese steel, iron steel, carbon steel, etc. can be used, or other temperature-resistant and corrosion-resistant materials can also be used.

[0037] The stirring chain is connected to the side wall in the axial direction of the main shaft. Preferably, the lengths of the stirring chains are different.

[0038] Alternatively, the stirring chain is connected to one end of the main shaft. The main shaft is driven to rotate, driving the stirring chain to rotate and playing a stirring role.

[0039] In some embodiments, the main shaft of the spoiler assembly is provided at the top of the absorption tower. The spoiler assembly can also be fixed inside the humidifying device, and the main shaft passes through the top of the absorption tower and extends into the interior of the absorption tower.

[0040] Taking the main shaft of the spoiler assembly at the top of the absorption tower as the vertex, the angle between the main shaft of the spoiler assembly and the longitudinal direction of the absorption tower is between -65° and +65°. Taking the top end as the axis, counterclockwise is the negative angle and clockwise is the positive angle.

[0041] Preferably, taking the main shaft of the spoiler assembly at the top of the absorption tower as the vertex, the angle between the main shaft of the spoiler assembly and the longitudinal direction of the absorption tower is between -65° and -30°, or between +30° and +65°.

[0042] The spoiler main shaft forms a certain angle with the longitudinal direction, and can stir the flue gas and the deacidifying agent in multiple directions. Improve the gas mixing degree.

[0043] Preferably, the movement range of the stirring chain of the spoiler assembly is controlled within 2 / 3 to 5 / 6 of the cross-sectional area of the absorption tower.

[0044] In some embodiments, the movement range of the stirring chain of the spoiler assembly is 1 to 24 m².

[0045] Specifically determine its range according to the size of the flue gas volume and the concentration ratio of the acidic gas contained.

[0046] In another embodiment, in addition to rotating on its own axis, the main shaft of the above-mentioned spoiler assembly can also perform circular motion within a certain range.

[0047] Through the combination of the rigid main shaft and the flexible stirring chain of the spoiler assembly, the flue gas and the deacidifying agent in the absorption tower are stirred in more dimensions, and there is no need to set up stirring devices in other directions. Increase the suspension time of the flue gas and the deacidifying agent in the tower and increase their mixing degree. In addition, the amount of sinking materials in the absorption tower can be alleviated, and the possibility of blocking the tower body can be reduced.

[0048] In some embodiments, the length of the main shaft of the spoiler assembly is 2 / 5 to 4 / 5 of the height of the tower body of the absorption tower.

[0049] The length of the stirring chain of the spoiler assembly is less than the radius of the cross-sectional area of the tower body of the absorption tower and greater than 1 / 2 of the radius of the cross-sectional area of the tower body.

[0050] The air passing area of the spoiler assembly is 1 to 24 m².

[0051] By arranging a flow disturbing component with the above structural characteristics at the top of the absorption tower, when the solid deacidifying agent with a certain humidity and the flue gas enter the absorption tower, most of the solid deacidifying agent is suspended in the absorption tower, and the flue gas and the solid deacidifying agent can effectively contact and react. In addition, due to the arrangement of the flow disturbing component, the suspended flue gas and the solid absorption tower can smoothly enter the next absorption tower for further reaction. In this way, problems such as uneven flue gas flow and unfavorable mixing of the deacidifying agent and the flue gas can be overcome.

[0052] Each stage of the multi-stage multi-cycle absorption tower is provided with a gravity flow zone where the flue gas flow direction and the material gravity are the same and a counter-gravity flow zone where the flue gas flow direction and the material gravity act in the opposite direction. The gravity flow area is provided with a vertical stirring device, the stirring rate of the device is 0 - 910 r / min, and the stirring radius is 0 - 4.5 m. According to the flue gas fluctuation, the rotation speed is dynamically adjusted by frequency conversion to match the change of the flue gas; in the counter-gravity flow area, a stirring device can be selectively added according to the pollutant concentration in the flue gas. The form of the device is the same as that of the vertical stirring device, and it can be arranged vertically or horizontally. The stirring rate of the device is 0 - 570 r / min, and the stirring radius is 0 - 3 m. The rotation speed is dynamically adjusted by frequency conversion to match the change of the material circulation.

[0053] A pipe with a downward opening is arranged between the last stage absorption tower and the bag filter. The substances in the absorption tower can enter the bag filter through this pipe.

[0054] In some embodiments, the first end of the pipe is connected to the absorption tower, the second end of the pipe is connected to the bag filter, and the diameter of the first end of the pipe is smaller than that of the second end of the pipe. Preferably, the diameter gradually increases from the first end to the second end of the pipe. Through this setting method, the gas-solid substances in the absorption tower are easily separated, the amount of solid substances mixed in the gas entering the bag filter is reduced, the dust concentration in the bag filter part is reduced, and the load of the bag filter is reduced. In addition, the solid substances return to the absorption tower for further reaction. It is equivalent to adding a gravity pre-dust collector or a baffle pre-dust collector.

[0055] In some embodiments, the diameter of the second end of the pipe is 1 - 3 times that of the first end of the pipe.

[0056] Multi-point humidification :

[0057] The outlet of the bag filter is respectively communicated with each stage of the absorption tower, and a humidifying device is arranged between the outlet of the bag filter and the absorption tower.

[0058] The gas entering the bag filter is mixed with unreacted solid deacidifying agent or reacted solid products. After being treated in the bag filter, the solid substances are appropriately humidified in the humidifying device and then enter each stage of the absorption tower again for further reaction. In this way, the use efficiency of the deacidifying agent can be improved.

[0059] Multi-stage circulation :

[0060] A double-layer jacket structure with a thickness of 6 - 40 mm is provided at the top of each absorption tower, and a discharge port is provided at the bottom. The discharge port is connected to the absorption tower through an external pipeline. The sinking materials at the bottom of the absorption tower can be circulated and transported back into the absorption tower.

[0061] The internal circulation of the above absorption tower is completed by the transportation of a Roots blower. During this process, due to frictional impact, agglomerated particles will be broken up, or the new surface of the particles leaking out due to friction will continue to deacidify, or the new surface area of the particles leaking out due to friction will continue to deacidify. In this way, the settled particles cannot be returned to the tower for re-reaction, and due to various frictions during the transportation process, more reactive contact surfaces are provided. Thus, the utilization rate of the deacidifying agent and the deacidification efficiency are ensured.

[0062] On the other hand, the materials discharged from the discharge port of each absorption tower can also be transported through pipelines into other absorption towers for further reaction, realizing the circulation between absorption towers.

[0063] In this application, through the internal circulation of the sinking materials in the absorption tower and the material circulation between absorption towers, the reaction materials in each absorption tower can be flexibly leveled, ensuring a longer and more sufficient reaction between the deacidifying agent and the flue gas, and improving the deacidification efficiency.

[0064] The multi-stage absorption system further includes a waste ash bin, and the discharge port of each absorption tower is connected to the waste ash bin through a pipeline.

[0065] In some embodiments, the multi-stage absorption system further includes an activated carbon bin for storing activated carbon, and other adsorbents can also be stored to remove certain substances in the flue gas. Activated carbon can also be added to the deacidifying agent to achieve the purpose of removing dioxins.

[0066] An activated carbon inlet is provided on the absorption tower. The activated carbon bin is connected to the activated carbon inlet on the absorption tower through a pipeline. Preferably, an activated carbon inlet is provided on each absorption tower.

[0067] In a preferred embodiment, the height of the activated carbon inlet from the bottom of the tower is 3 / 8 - 1 / 2 of the tower height.

[0068] In some embodiments, at least two discharge ports are provided on the side wall of the lower part of the absorption tower, and a valve is provided on the discharge port.

[0069] The discharge port is mainly used to emergently discharge excessive deacidifying agent and dust to avoid clogging the tower body, and is also used to emergently empty the lower hopper of the absorption tower body during maintenance.

[0070] Preferably, the discharge ports are evenly distributed along the circumference of the absorption tower.

[0071] The absorption system of the present application is applicable to absorbing acidic substances in flue gas, ensuring both high deacidification efficiency and good adaptability to flue gas volume and concentration. It is applicable to high-temperature, high-concentration, high-humidity flue gas containing acid and dust, especially industrial furnace waste gas and hazardous waste disposal, etc.

[0072] The multi-stage absorption system of the present application will be further described in detail below with reference to the accompanying drawings.

[0073] Example 1

[0074] As Figure 1 shown, in this embodiment, the multi-stage absorption tower system includes four absorption towers 4, specifically the first-stage absorption tower 41, the second-stage absorption tower 42, the third-stage absorption tower 43, and the fourth-stage absorption tower 44. Each stage of the absorption tower includes an air inlet and an air outlet, and they are connected in series in sequence from the first-stage absorption tower to the fourth-stage absorption tower, that is, the air outlet of the first-stage absorption tower is connected to the air inlet of the second-stage absorption tower, and the air outlet of the second-stage absorption tower is connected to the air inlet of the third-stage absorption tower.

[0075] The multi-stage absorption tower system includes a new ash bin 1 for storing deacidifying agents. The deacidifying agents include one or a mixture of two or more substances such as calcium carbonate, calcium oxide, calcium hydroxide, sodium carbonate, and zinc oxide. The new ash bin 1 is placed above the first-stage absorption tower body and is connected to the first-stage absorption tower 41, and a humidifying device 2 is provided between the first-stage absorption tower and the new ash bin. The humidifying device is used to add moisture to the deacidifying agent so that the water content of the deacidifying agent reaches a certain level when entering the first-stage absorption tower.

[0076] The fourth-stage absorption tower 44 is connected to the inlet of the bag filter 7 through a pipeline 10. The first end of the pipeline 10 is connected to the fourth-stage absorption tower 44, and the second end of the pipeline 10 is connected to the bag filter 7. From the first end to the second end, the diameter of the pipeline gradually increases. Or a gravity dust collector or a baffle pre-dust collector is added between the fourth-stage absorption tower 44 and the bag filter 7. It has a gravity sedimentation effect on particulate matter, reducing the dust concentration entering the bag filter 7 and reducing the load of the bag filter. The bag filter 7 is located above the absorption tower 4, and the outlet of the bag filter is respectively connected to at least one stage of the absorption tower. In this embodiment, the outlet of the bag filter is respectively connected to all the absorption towers. The solid materials are returned to the absorption tower here for further deacidification reaction. A humidifying device 2 is provided between the outlet of the bag filter and the absorption tower. The dust-removed flue gas is discharged from the left or right outlet of the bag filter 7.

[0077] A turbulence component 3 is provided in the deacidification reactor, as Figure 2 shown in or 3, the turbulence component includes a main shaft 31 and a stirring chain 32. In this embodiment, the cross-section of the main shaft is quadrilateral, that is, the main shaft is a strip-shaped plate. One end of the main shaft is connected to the driving device at the top of the absorption tower or the driving device in the humidifying device, and the stirring chain is connected to the other end of the main shaft, asFigure 2 As shown. The main shaft is driven to rotate, driving the stirring chain to rotate, playing a stirring role. The angle between the main shaft of the spoiler assembly and the longitudinal direction of the absorption tower is between -65° and -30°, or +30° and +65°. The main shaft length of the spoiler assembly is 1 / 4 of the tower body height of the absorption tower, and the length of the stirring chain 32 is less than the radius of the cross-sectional area of ​​the tower body of the absorption tower, and greater than the radius of 1 / 2 of the cross-sectional area of ​​the tower body. The setting method of the spoiler assembly in each absorption tower can be the same or different.

[0078] The humidifying device may adopt any structure of the prior art, for example, at least a certain spray plate is provided in a tank body to humidify the deacidifying agent until a certain moisture content is reached.

[0079] At least one discharge port is provided at the bottom of each absorption tower, and multiple discharge ports may also be provided. A Roots blower is provided at the discharge port. The discharge port is connected to the absorption tower of the same level through an external pipeline, and may also be connected to the absorption tower of other levels, or to the waste ash bin. According to actual needs, internal circulation or inter-tower circulation is performed to improve the efficiency of deacidification.

[0080] A Roots blower 6 is provided at the bottom of each stage of the absorption tower for pneumatic conveying, and a switching valve is provided at the discharge port. The blower is mainly used to provide power to allow the discharged material to circulate externally, and can be switched to be discharged into the waste ash bin, or circulated between towers within the tower to achieve a deacidification effect.

[0081] The above design ensures high deacidification efficiency and good adaptability to flue gas volume and concentration. At the same time, it can also remove dust in the flue gas. If there are toxic and harmful heavy metal components in the dust, they will also be effectively captured.

[0082] The multi-stage absorption system also includes an activated carbon silo 9, and an activated carbon inlet is provided on each absorption tower. The activated carbon silo is connected to the activated carbon inlet on the absorption tower through a pipeline. According to actual conditions, an activated carbon inlet can also be provided on one or several absorption towers. The height of the activated carbon inlet from the bottom of the tower is 3 / 8 to 1 / 2 of the tower body height. The absorption tower has the function of synchronously removing dioxins.

[0083] The ash discharge valve 5 of this embodiment is arranged on the rising side of the flue gas, which is convenient for emergency discharge when the deacidifying agent settles and there is too much dust entrained in the flue gas to avoid clogging the tower body. It is also used for emergency emptying of the tower bottom bucket during maintenance.

[0084] Example 2

[0085] Differing from Example 1 is the arrangement of the stirring device. Each stage of the tower body is provided with a gravity flow zone and a counter-gravity flow zone. The gravity flow zone is provided with a vertical stirring device, the stirring rate of the device is 0 - 910 r / min, the stirring radius is 0 - 4.5 m, and according to the flue gas fluctuations, the rotational speed is dynamically adjusted by frequency conversion to match the changes in the flue gas; the counter-gravity flow zone is provided with a horizontal stirring device, the stirring rate of the device is 0 - 570 r / min, the stirring radius is 0 - 3 m, and the rotational speed is dynamically adjusted by frequency conversion to match the changes in the material circulation.

[0086] The system of Example 1 (with a change in the number of absorption towers) is used below, and specific examples are given for illustration.

[0087] Experimental Example 1: A 4-stage absorption tower is used. The concentrations of acidic gases HF, HCl, and SO 2 in the original flue gas are as shown in the table. The water content of the flue gas is 40%. 200-mesh calcium hydroxide is used as the deacidifying agent (moisture content 8%). The tower body height is 12 m, the length of the flow disturbance component is 5.6 m, the inclination angle is +65°, and the purification efficiency is above 95%.

[0088] Experimental Example 2: A 3-stage absorption tower is used. The concentrations of acidic gases HF, HCl, and SO 2 in the original flue gas are as shown in the table. The water content of the flue gas is 35%. 325-mesh calcium oxide is used as the deacidifying agent (moisture content 6%). The tower body height is 24 m, the length of the flow disturbance component is 12 m, the inclination angle is -60°, and the purification efficiency is above 97%.

[0089] Experimental Example 3: A 2-stage absorption tower is used. The concentrations of acidic gases HF, HCl, and SO 2 in the original flue gas are as shown in the table. (The water content of the flue gas is 15%. 325-mesh sodium carbonate is used as the deacidifying agent (moisture content 5%). The tower body height is 36 m, the length of the flow disturbance component is 27 m, the inclination angle is +35°, and the purification efficiency is above 96%.

[0090]

[0091] This application has been described in detail with the aim of enabling those skilled in the art to understand the content of this application and implement it. However, this should not limit the protection scope of this application. Any equivalent changes or modifications made according to the spirit and essence of this application should be covered within the protection scope of this application.

Claims

1. Application of a multi-stage absorption system in absorbing acidic substances in flue gas, the multi-stage absorption system comprises: more than two absorption towers, a bag filter, a humidifying device and a new ash bin; An air inlet and an air outlet are provided at the upper part of each absorption tower. The air outlet of the previous absorption tower is communicated with the air inlet of the next absorption tower, and the absorption towers are sequentially communicated in series; the new ash bin is communicated with the first absorption tower, and a humidifying device is arranged between the new ash bin and the first absorption tower; the last absorption tower is connected to the inlet of the bag filter, the bag filter is arranged above the absorption tower, and the ash hopper of the bag filter is communicated with the absorption tower through the humidifying device; wherein, The humidifying device is used to mix the mixed solid deacidifying agent and liquid to form a solid deacidifying agent containing 1-9% moisture. In the solid deacidifying agent, more than 85% of the particle size is distributed between 200 and 325 meshes; A flow disturbing component is installed in each absorption tower; the flow disturbing component includes a main shaft and a stirring chain. The main shaft is a strip-shaped plate. One end of the main shaft is connected to the top of the absorption tower, and the stirring chain is connected to the other end of the main shaft. The length of the main shaft of the flow disturbing component is 2 / 5 to 4 / 5 of the height of the tower body of the absorption tower, and the length of the stirring chain of the flow disturbing component is less than the radius of the cross-sectional area of the tower body of the absorption tower and greater than 1 / 2 of the radius of the cross-sectional area of the tower body; Taking the main shaft of the flow disturbing component at the top of the absorption tower as the vertex, the included angle between the main shaft of the flow disturbing component and the longitudinal direction of the absorption tower is between -65° and -30°, or between +30° and +65°; The water content in the flue gas is 15-40 wt%.

2. The application according to claim 1, characterized in that, The main shaft of the flow disturbing component rotates and simultaneously makes a circular motion.

3. The application according to claim 2, characterized in that, The main shaft of the flow disturbing component makes a circular motion within the range of an angle of 30° to 65°.

4. The application according to any one of claims 1-3, characterized in that, A pipe with a downward opening is arranged between the last-stage absorption tower and the bag filter; The first end of the pipe is connected to the absorption tower, the second end of the pipe is connected to the bag filter, and the diameter of the first end of the pipe is smaller than the diameter of the second end of the pipe.

5. The application according to claim 4, characterized in that, From the first end to the second end of the pipe, the diameter gradually increases.

6. The application according to claim 5, characterized in that, The diameter of the second end of the pipe is more than 1 time and less than or equal to 3 times the diameter of the first end of the pipe.

7. The application according to any one of claims 1-3, characterized in that, The ash hopper of the bag filter is communicated with each stage of absorption tower respectively, and a humidifying device is arranged between the outlet of the ash hopper of the bag filter and the absorption tower.

8. The application according to any one of claims 1-3, characterized in that, There is a double-layer jacket structure at the top of each absorption tower, and a discharge port is provided at the bottom. The discharge port is communicated with the absorption tower through an external pipe; Or, the material discharged from the discharge port of each absorption tower is transported to other absorption towers through a pipe for further reaction.

9. The application according to any one of claims 1-3, characterized in that, The multi-stage absorption system further includes an activated carbon bin for storing activated carbon; An activated carbon inlet is provided on the absorption tower. The activated carbon silo is connected to the activated carbon inlet on the absorption tower through a pipeline. The height of the activated carbon inlet from the bottom of the tower is 3 / 8 to 1 / 2 of the tower height.

10. The application according to any one of claims 1-3, characterized in that, at least two discharge ports are provided on the side wall of the lower part of the absorption tower, and a valve is provided on the discharge port.

11. The application according to claim 10, characterized in that, the discharge ports are evenly distributed along the circumference of the absorption tower.

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