Split type wet desulphurization device and method for low-sulfur-content flue gas

Abstract

The invention discloses a split type wet desulphurization device and method for low-sulfur-content flue gas, absorption towers and a slurry pool are in non-integrated connection design, a plurality of absorption towers are connected in parallel, are uniformly distributed around the slurry pool and share one slurry pool, and a chimney is fixedly connected to the upper part of a circulating slurry pool. According to the invention, the problem that the absorption zone and the oxidation zone are not matched when the existing wet desulphurization technology is applied to the working condition of low sulfur content and large flue gas amount is avoided, and the defect that the existing wet desulphurization technology cannot realize online maintenance is overcome; the system has the advantages of being small in occupied area, low in operation energy consumption, high in system economy, safe and stable in overall operation and high in system utilization rate.

Description

Technical Field

[0001] The invention belongs to the technical field of desulfurization devices, and in particular relates to a low-sulfur flue gas split-type wet desulfurization device and method. Background Art

[0002] Sulfur dioxide (SO 2 ) is one of the main air pollutants, and its emission mainly comes from the combustion of fossil fuels and the smelting process of non-ferrous metals. 2 After being emitted into the atmosphere, it will react with water vapor and oxygen to form sulfuric acid and sulfate aerosols, which will in turn cause environmental problems such as acid rain and haze, causing serious impacts on the ecological environment and human health. Governments around the world have stepped up efforts to control SO 2 In order to strengthen the supervision of air pollutant emissions, a series of strict environmental protection laws and emission standards have been formulated. These laws and standards require industrial enterprises to take effective measures to reduce SO 2 emission.

[0003] SO generated during aluminum electrolysis 2 Flue gas is one of the key points of environmental protection. By adopting advanced desulfurization technology, SO 2 Wet desulfurization technology is the most widely used desulfurization method. This technology uses limestone slurry to react with SO in flue gas. 2 The conventional wet desulfurization technology absorber is a countercurrent spray tower, which is an integrated structure integrating absorption, oxidation, demisting and emission functions. From bottom to top, it is composed of a circulating slurry pool (oxidation zone), a spray device (absorption zone), a demister (demisting zone) and a chimney (emission), containing SO 2 The flue gas enters the absorption tower from the circulating slurry pool and the spray device, and contacts with the atomized circulating slurry sprayed from the spray device in countercurrent. The SO 2 It reacts with limestone in the circulating slurry to form calcium sulfite. The saturated flue gas after desulfurization is discharged into the chimney after the mist droplets are removed by the demister on the top of the spray device to meet the emission standards and absorb SO 2 The circulating slurry after the slurry falls into the circulating slurry pool, and the oxidizing air blower blows air into the circulating slurry pool to oxidize the calcium sulfite in the circulating slurry into calcium sulfate, and the supersaturated calcium sulfate solution crystallizes to form gypsum (CaS0 4 ·2H 2 O), most of the slurry in the circulating slurry pool is pumped into the spraying device by the slurry circulating pump to circulate and spray to absorb SO in the flue gas 2A small part is discharged as a desulfurization by-product by the gypsum slurry discharge pump. At the same time, fresh absorbent slurry is supplied to the circulating slurry pool to replenish the consumed limestone. The advantages of this technology are that it can treat high-sulfur flue gas, has high desulfurization efficiency, mature technology, and by-products can be recycled; the disadvantages are large equipment investment and high operating energy consumption.

[0004] Aluminum electrolysis flue gas has large flue gas volume and SO 2 The concentration is low, so when wet desulfurization is used, it is necessary to expand the absorption area and reduce the oxidation area to achieve SO 2 Optimal coupling of absorption and oxidation to reduce construction costs and operating energy consumption. Since the absorption tower of conventional wet flue gas desulfurization technology is an integral structure, for the sake of structural safety and the operating requirements of the slurry circulation pump, the diameter of the circulating slurry pool is not less than the diameter of the spray absorption zone, and the liquid level in the circulating slurry pool must also be higher than the minimum liquid level for safe operation of the slurry circulation pump. As a result, the amount of slurry stored in the circulating slurry pool is much larger than the reasonable amount of slurry required for calcium sulfite oxidation, resulting in a waste of energy consumption of the slurry pool agitator, oxidation fan, etc., and at the same time, raising the overall cost of the desulfurization system. Conventional wet flue gas desulfurization technology can only shut down the entire tower for maintenance when the spray device, demister, etc. in the tower have operating failures and need maintenance, so the operating stability is poor and the system availability is low. Summary of the invention

[0005] In view of the defects of the above-mentioned prior art in the application of low-sulfur flue gas in aluminum electrolysis, the purpose of the present invention is to provide a low-sulfur flue gas split wet desulfurization device and method, which can effectively couple the oxidation volume requirements of calcium sulfite in the circulating slurry under low-sulfur and large flue gas volume, the safe operation liquid level requirements of the slurry circulation pump and SO 2 The absorption space requirements can effectively reduce the system's footprint, reduce the system's operating energy consumption, reduce project costs, increase overall economy, and improve the system's operating stability and availability.

[0006] The present invention is achieved in that: On the one hand, it is a split wet desulfurization device for low-sulfur flue gas, in which the absorption tower and the slurry pool are not connected in an integrated manner. Multiple absorption towers are connected in parallel and are evenly distributed around the slurry pool and share one slurry pool. The chimney is fixedly connected to the upper part of the circulating slurry pool. The flue gas inlet of the absorption tower is connected to the main flue through a pipeline, the outlet is connected to the chimney, and the bottom is connected to the circulating slurry pool. The inlet of the slurry circulation pump is connected to the circulating slurry pool, and the outlet is connected to the spray device in the absorption tower.

[0007] Furthermore, two absorption towers are provided, which are symmetrically arranged on both sides of the circulating slurry pool.

[0008] Furthermore, the absorption tower is arranged at a high position, and the bottom is not lower than the height of the liquid level in the slurry pool.

[0009] Furthermore, a spray device and a demister device are sequentially arranged in the absorption tower from bottom to top.

[0010] Furthermore, a plurality of circulating slurry pool agitators are arranged around the circulating slurry pool.

[0011] Furthermore, the circulating slurry pool is connected to the outlet of the desulfurizer adding pump, the outlet of the oxidation blower and the inlet of the desulfurization by-product discharging pump.

[0012] Another aspect of the present invention is a split-type wet desulfurization method for low-sulfur flue gas, which uses the above-mentioned desulfurization device, and the method steps are as follows: S1, start the slurry circulation pump, the slurry containing the desulfurizer in the circulating slurry pool is pumped into the spraying device through the slurry circulation pump, and sprayed from the upper part of the absorption tower; S2, open the flue gas inlet shut-off valve and the flue gas outlet shut-off valve, the flue gas is dispersed into each parallel absorption tower, and when flowing upward along the tower, it contacts with the circulating slurry sprayed by the spray device in the tower in countercurrent, and the SO in the flue gas is 2 It is absorbed by the circulating slurry to generate calcium sulfite. The desulfurized flue gas passes through the demister device and enters the chimney before being discharged into the atmosphere. S3, sprayed slurry and passed through flue gas to absorb SO 2 Then it falls to the bottom of the tower and flows into the circulating slurry pool by gravity.

[0013] Furthermore, the method also includes the following steps: air is blown into the circulating slurry pool by an oxidation blower to oxidize the calcium fumate in the circulating slurry into calcium sulfate.

[0014] Furthermore, the method also includes: supplying fresh desulfurizer slurry to the circulating slurry pool through a desulfurizer adding pump to replenish the consumed desulfurizer.

[0015] Further, part of the circulating slurry containing calcium sulfate is discharged as a desulfurization by-product through a desulfurization by-product discharge pump.

[0016] The beneficial effects of the present invention are: (1) The absorption tower (absorption zone) and slurry pool (oxidation zone) are creatively designed separately, and multiple absorption towers are connected in parallel. For flue gas with low sulfur content, the total flue gas flow volume in the absorption zone is increased. The number of absorption towers can be adjusted flexibly according to specific working conditions, effectively improving the utilization rate of the slurry pool (oxidation zone). The existing integrated design of the absorption tower and slurry pool solves the problems of mismatched demand between the absorption zone and the oxidation zone, high energy consumption, and low production efficiency. The high-position design of the absorption tower utilizes the high head difference, and the liquid in the tower can automatically flow into the slurry pool, saving energy and reducing consumption.

[0017] (2) By adopting a configuration method of connecting multiple absorption towers in parallel, a single absorption tower can be taken offline by closing the shut-off valves at the inlet and outlet of the split-type absorption flue gas, which facilitates the maintenance and overhaul of the absorption tower, improves the system operation stability, and extends the service life of the equipment.

[0018] (3) The pool-smoke integrated structure in which a circulating slurry pool is arranged at the bottom of the chimney can reduce the area occupied by the chimney. The absorption tower is arranged at a high position, freeing up space at the bottom of the absorption tower to place pumps and other equipment, making the overall layout of the device of the present invention more compact and improving the economy of the system.

[0019] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the connection of the device of the present invention; In the figure: 1 absorption tower, 2 slurry circulation pump, 3 spray device, 4 demister, 5 chimney, 6 circulating slurry pool, 7 circulating slurry pool agitator, 8 desulfurization agent addition pump, 9 desulfurization by-product discharge pump, 10 oxidation fan, 11 flue gas inlet shut-off valve, 12 flue gas outlet shut-off valve, 13 spray device shut-off valve, 14 main flue. DETAILED DESCRIPTION

[0021] Embodiment 1: This embodiment is a low sulfur flue gas split wet desulfurization method and device, such as Figure 1 As shown, it includes: an absorption tower 1, a slurry circulation pump 2, a spray device 3, a demister 4, a chimney 5, a circulating slurry pool 6, a circulating slurry pool agitator 7, a desulfurizer addition pump 8, a desulfurization by-product discharge pump 9, an oxidation fan 10, a flue gas inlet shut-off valve 11, a flue gas outlet shut-off valve 12, and a spray device shut-off valve 13.

[0022] The absorption tower 1 and the slurry pool 6 are not designed to be connected in an integrated manner. Multiple absorption towers 1 are connected in parallel, evenly distributed around the slurry pool 6, and share one slurry pool 6. The chimney 5 is fixedly connected to the upper part of the circulating slurry pool 6 and is an integrated structure with the chimney 5, which can make full use of the space and reduce the floor space. The flue gas inlet of the absorption tower 1 is connected to the main flue 14 through a flue gas inlet shut-off valve 11, the outlet is connected to the chimney 5 through a flue gas outlet shut-off valve 12, and the bottom is connected to the circulating slurry pool 6 through a pipeline. The inlet of the slurry circulation pump 2 is connected to the circulating slurry pool 6, and the outlet is connected to the spray device 3 in the absorption tower 1. The absorption tower 1 is provided with a spray device 3 and a demister device 4 from bottom to top. The spray device 3 is preferably a spray pipe.

[0023] The absorption tower 1 is arranged at a high position, and the bottom height is not lower than the liquid level in the slurry pool 6. A plurality of circulating slurry pool agitators 7 are arranged around the circulating slurry pool 6, and the circulating slurry pool 6 is also connected to the outlet of the desulfurizing agent adding pump 8, the outlet of the oxidation blower 10 and the inlet of the desulfurization by-product discharge pump 9.

[0024] Embodiment 2: This embodiment is an improvement of the embodiment 1, and is a refinement of the absorption tower 1. Two absorption towers are arranged in parallel and symmetrically on both sides of the circulating slurry pool 6. The flue gas inlets of the two absorption towers 1 are connected to the main flue 14 through the flue gas inlet shut-off valve 11, and the outlets are connected to the chimney 5 through the flue gas outlet shut-off valve 12, and the bottom is connected to the circulating slurry pool 6; the absorption tower 1 is sequentially arranged with a spray device 3 and a demister 4 from bottom to top; the inlet of the slurry circulation pump 2 is connected to the circulating slurry pool 6, and the outlet is connected to the spray device of the spray device 3 inside the absorption tower 1; the top of the circulating slurry pool 6 is connected to the chimney 5, and the circulating slurry pool 6 and the chimney 5 are an integrated structure; a number of circulating slurry pool agitators 7 are arranged around the wall of the circulating slurry pool 6; the circulating slurry pool 6 is connected to the outlet of the desulfurizer adding pump 8, the outlet of the oxidation fan 10 and the inlet of the desulfurization by-product discharge pump 9.

[0025] Embodiment 3: This embodiment is a split-type wet desulfurization method for low-sulfur flue gas, using the above-mentioned desulfurization device, and the method steps are as follows: Contains SO 2 During flue gas desulfurization, the slurry circulation pump 2 is turned on, and the slurry containing the desulfurizer in the circulating slurry pool 6 is pumped into the spraying device 3 through the slurry circulation pump 2. After being sprayed from the top of the absorption tower 1 to the bottom of the tower, it flows into the circulating slurry pool 6 by gravity, thereby forming a circulating spray of the slurry containing the desulfurizer.

[0026] S1, start the slurry circulation pump 2, and the slurry containing the desulfurizer in the circulating slurry pool 6 is pumped into the spraying device 3 through the slurry circulation pump 2 and sprayed from the upper part of the absorption tower 1.

[0027] S2, open the flue gas inlet shut-off valve 11 and the flue gas outlet shut-off valve 12, and the flue gas is dispersed into each parallel absorption tower 1. When flowing upward along the tower, it contacts the circulating slurry sprayed by the spray device 3 in countercurrent, and the SO in the flue gas is reduced. 2 The flue gas after desulfurization is absorbed by the circulating slurry to generate calcium sulfite. The flue gas passes through the demister device 4 and enters the chimney 5 to be combined and then discharged into the atmosphere.

[0028] S3, sprayed slurry and passed through flue gas to absorb SO 2 Finally, it falls to the bottom of the absorption tower 1 and then flows into the circulating slurry pool 6 through the pipeline.

[0029] The method also includes: air is blown into the circulating slurry pool 6 by the oxidation fan 10 to oxidize the calcium fumate in the circulating slurry into calcium sulfate; fresh desulfurizer slurry is supplied to the circulating slurry pool 6 by the desulfurizer addition pump 8 to replenish the consumed desulfurizer, and part of the circulating slurry containing calcium sulfate is discharged as a desulfurization by-product by the desulfurization by-product discharge pump 9.

[0030] In order to better illustrate the present invention, the following Figure 1 Describe its working process and principle in detail.

[0031] Contains SO 2 During flue gas desulfurization, the slurry circulation pump 2 is turned on, and the slurry containing the desulfurizer in the circulating slurry pool 6 is pumped into the spray device 3 through the slurry circulation pump 2, and then sprayed from the top of the absorption tower 1 to the bottom of the tower, and then flows into the circulating slurry pool 6 by gravity, so that the slurry containing the desulfurizer is sprayed in a circulating manner. The flue gas inlet shut-off valve 11 and the flue gas outlet shut-off valve 12 are turned on, and the flue gas is dispersed into each parallel absorption tower 1. When flowing upward along the tower, it contacts the circulating slurry sprayed and falling in the tower in a countercurrent manner, and the SO in the flue gas is 2 The sulfite is absorbed by the circulating slurry and the flue gas after desulfurization is discharged into the atmosphere after being combined in the chimney 5. Air is blown into the circulating slurry pool 6 by the oxidation blower 10 to oxidize the fumosulfate in the circulating slurry into calcium sulfate. Part of the circulating slurry containing calcium sulfate is discharged as a desulfurization by-product by the desulfurization by-product discharge pump 9. Fresh desulfurizer slurry is supplied to the circulating slurry pool 6 by the desulfurizer adding pump 8 to replenish the consumed desulfurizer.

[0032] When a parallel absorption tower 1 needs to be shut down for maintenance, the flue gas inlet shut-off valve 11 and the flue gas outlet shut-off valve 12 of the tower are closed, and the absorption tower 1 can be inspected and maintained online while other absorption towers continue to operate.

[0033] When the traffic is large but SO 2 When flue gas with low concentration enters the system and needs to be desulfurized, a large absorption tower is required to circulate the flue gas. 2 The content is low, and a relatively small slurry pool is required to meet the SO 2 The slurry pool and the absorption tower are usually integrated designs. The fixed absorption zone capacity and the limitation of flue gas flow rate cause the mismatch between the absorption tower (absorption zone) and the slurry pool (oxidation zone), or the defects of passive enlargement of the oxidation zone, the circulating slurry pool agitator 7 and the oxidation fan 10, which reduce the production efficiency and increase the production cost.

[0034] The present invention creatively separates the absorption tower (absorption zone) and the slurry pool (oxidation zone) into separate parts. The structure of multiple absorption towers 1 (absorption zone) connected in parallel increases the total flue gas flow area in the absorption zone. The number of absorption towers can be conveniently and flexibly adjusted according to specific working conditions, effectively improving the utilization rate of the slurry pool (oxidation zone), and improving production efficiency and the stability of system operation. At the same time, offline inspection and maintenance of a single absorption tower 1 is also realized.

[0035] The absorption tower 1 is arranged at a high position to realize the self-flow of the circulating slurry back to the circulating slurry pool 6, so the space at the bottom of the absorption tower 1 can be effectively utilized. At the same time, the circulating slurry pool 6 and the chimney 5 are an integrated structure, so the entire system occupies only the projected area of ​​the circulating slurry pool 6, effectively reducing the system's footprint and improving the system's economy.

[0036] In summary, the present invention effectively avoids the problem of mismatch between the absorption zone and the oxidation zone when the existing wet desulfurization technology is applied to low sulfur content and large flue gas volume conditions, and solves the defect that the existing wet desulfurization technology cannot realize online maintenance. It has the advantages of small system footprint, low operating energy consumption, high system economy, safe and stable overall operation, and high system availability.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low-sulfur flue gas split wet desulfurization device, characterized in that: The absorption tower (1) and the slurry pool (6) are not designed to be connected in an integrated manner. A plurality of the absorption towers (1) are connected in parallel and are evenly distributed around the slurry pool (6) and share one slurry pool (6). A chimney (5) is fixedly connected to the upper part of the circulating slurry pool (6). The smoke inlet of the absorption tower (1) is connected to the main flue (14) through a pipeline, and the outlet is connected to the chimney (5). The bottom is connected to the circulating slurry pool (6). The inlet of the slurry circulation pump (2) is connected to the circulating slurry pool (6), and the outlet is connected to the spray device (3) of the absorption tower (1).

2. The low sulfur flue gas split wet desulfurization device according to claim 1 is characterized in that: Two absorption towers (1) are provided, and are symmetrically arranged on both sides of the circulating slurry pool (6).

3. The low-sulfur flue gas split-type wet desulfurization device according to claim 1 is characterized in that: The absorption tower (1) is arranged at a high position, and the bottom thereof is not lower than the height of the liquid level in the slurry pool.

4. The low-sulfur flue gas split-type wet desulfurization device according to claim 1 is characterized in that: A spray device (3) and a demister device (4) are arranged in sequence from bottom to top in the absorption tower (1).

5. The low sulfur flue gas split wet desulfurization device according to claim 1 is characterized in that: A plurality of circulating slurry pool agitators (7) are arranged around the circulating slurry pool (6).

6. The low-sulfur flue gas split-type wet desulfurization device according to claim 1 is characterized in that: The circulating slurry pool (6) is connected to the outlet of the desulfurizing agent adding pump (8), the outlet of the oxidation blower (10) and the inlet of the desulfurizing by-product discharging pump (9).

7. A split wet desulfurization method for low-sulfur flue gas based on the desulfurization device according to any one of claims 1 to 6, characterized in that: The method steps are as follows: When desulfurizing flue gas containing SO2, the slurry circulation pump (2) is turned on, and the slurry containing the desulfurizer in the circulating slurry pool (6) is pumped into the spraying device (3) through the slurry circulation pump (2), sprayed from the upper part of the absorption tower (1) to the bottom of the tower, and then flows into the circulating slurry pool (6) by gravity, thereby forming a circulating spray of the slurry containing the desulfurizer; S1, start the slurry circulation pump (2), pump the slurry containing the desulfurizer in the circulating slurry pool (6) into the spraying device (3) through the slurry circulation pump (2), and spray from the upper part of the absorption tower (1); S2, open the flue gas inlet shut-off valve (11) and the flue gas outlet shut-off valve (12), and the flue gas is dispersed and enters each parallel absorption tower (1). When flowing upward along the tower, the flue gas countercurrently contacts with the circulating slurry sprayed by the spray device (3). SO2 in the flue gas is absorbed by the circulating slurry to generate calcium sulfite. The desulfurized flue gas passes through the demister device (4) and enters the chimney (5) to be combined and then discharged into the atmosphere; S3, the sprayed slurry passes through the flue gas to absorb SO2 and then falls to the bottom of the absorption tower (1), and then flows into the circulating slurry pool (6) through the pipeline.

8. The low-sulfur flue gas split-type wet desulfurization method according to claim 7, characterized in that: The method further comprises the steps of: air is blown into the circulating slurry pool (6) by an oxidation blower (10) to oxidize the calcium fumosulfate in the circulating slurry into calcium sulfate.

9. The low-sulfur flue gas split-type wet desulfurization method according to claim 8, characterized in that: The method further comprises the steps of: supplying fresh desulfurizing agent slurry into the circulating slurry pool (6) through a desulfurizing agent adding pump (8) to replenish the consumed desulfurizing agent.

10. The low-sulfur flue gas split-type wet desulfurization method according to claim 9, characterized in that: Part of the circulating slurry containing calcium sulfate is discharged as a desulfurization by-product from the desulfurization by-product discharge pump (9).

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