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

Abstract

The utility model discloses a split type wet desulphurization device for low-sulfur-content flue gas, which is characterized in that an absorption tower and a slurry pond are in non-integrated connection design, a plurality of split type absorption towers are connected in parallel, are uniformly distributed around the slurry pond and share one slurry pond, and a chimney is fixedly connected to the upper part of a circulating slurry pond. According to the utility model, the problem that the absorption area and the oxidation area 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 solved, 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] This utility model belongs to the technical field of desulfurization equipment, and specifically relates to a split-type wet desulfurization equipment for low sulfur flue gas. Background Technology

[0002] Sulfur dioxide (SO2), a major air pollutant, is primarily emitted from the combustion of fossil fuels and the smelting of non-ferrous metals. Once released into the atmosphere, SO2 reacts with water vapor and oxygen to form sulfuric acid and sulfate aerosols, leading to environmental problems such as acid rain and smog, severely impacting the ecological environment and human health. Governments worldwide have strengthened their oversight of SO2 and other air pollutant emissions, enacting a series of stringent environmental regulations and emission standards. These regulations and standards require industrial enterprises to take effective measures to reduce SO2 emissions during production processes.

[0003] SO2 emissions generated during aluminum electrolysis are a key focus of environmental protection. Advanced desulfurization technologies can effectively reduce SO2 emissions and improve resource utilization efficiency. Wet desulfurization is the most widely used method. This technology uses limestone slurry to react with SO2 in the flue gas, producing byproducts such as gypsum, thus achieving desulfurization. The conventional wet desulfurization absorption tower is a counter-current spray tower, an integrated structure combining absorption, oxidation, demisting, and emission functions. From bottom to top, it consists of a circulating slurry pool (oxidation zone), spray pipes (absorption zone), a demister (demisting zone), and a chimney (emission). SO2-containing flue gas enters the absorption tower between the circulating slurry pool and the spray pipes, coming into counter-current contact with the atomized circulating slurry sprayed from the spray pipes. The SO2 in the flue gas reacts with the limestone in the circulating slurry to form calcium sulfite. The desulfurized saturated flue gas then passes through… After the demister at the top of the spray pipe removes entrained mist droplets, the flue gas is discharged into the chimney to meet emission standards. The circulating slurry, having absorbed SO2, falls into the circulating slurry pool. An oxidation air blower blows air into the pool, oxidizing the calcium sulfite in the slurry into calcium sulfate. The supersaturated calcium sulfate solution crystallizes to form gypsum (CaSO4·2H2O). Most of the slurry in the pool is pumped back into the spray pipes by a slurry circulation pump to circulate and absorb SO2 from the flue gas. A small portion is discharged as a desulfurization byproduct by a gypsum slurry discharge pump. Simultaneously, fresh absorbent slurry is supplied to the circulating slurry pool to replenish the consumed limestone. The advantages of this technology are its ability to treat high-sulfur flue gas, high desulfurization efficiency, mature technology, and recyclable byproducts; the disadvantages are high equipment investment and high operating energy consumption.

[0004] Aluminum electrolysis flue gas is characterized by large volume and low SO2 concentration. Therefore, when using wet desulfurization, it is necessary to expand the absorption zone and reduce the oxidation zone to achieve optimal coupling of SO2 absorption and oxidation, thereby reducing costs and operating energy consumption. Because conventional wet desulfurization technology uses an integral absorption tower, for structural safety and the operational requirements of the slurry circulation pump, the diameter of the circulating slurry pool must be no 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 safe operating level of the slurry circulation pump. This results in a slurry volume in the circulating slurry pool that is far greater than the reasonable slurry volume required for calcium sulfite oxidation, leading to wasted energy from the slurry pool agitator and oxidation fan, and increasing the overall cost of the desulfurization system. Furthermore, when conventional wet desulfurization technology experiences operational malfunctions in the spray pipes or demisters within the tower requiring maintenance, the entire system must be shut down for repair, resulting in poor operational stability and low system availability. Summary of the Invention

[0005] In view of the above-mentioned defects in the application of low-sulfur flue gas in aluminum electrolysis, the purpose of this utility model is to provide a split-type wet desulfurization device for low-sulfur flue gas, which can effectively couple the oxidation volume requirements of calcium sulfite in the circulating slurry under low-sulfur large flue gas volume, the safe operation liquid level requirements of the slurry circulating pump, and the absorption space requirements of SO2, effectively reducing the system's footprint, reducing the system's operating energy consumption, reducing engineering costs, increasing overall economic efficiency, and improving the system's operational stability and availability.

[0006] This utility model is implemented as follows: a split-type wet desulfurization device for low-sulfur flue gas, wherein the absorption tower and slurry tank are not integrated. Multiple absorption towers are connected in parallel and evenly distributed around the slurry tank and share a slurry tank. The chimney is fixedly connected to the upper part of the circulating slurry tank. The flue gas inlet of the absorption tower is connected to the main flue, the outlet is connected to the chimney, and the bottom is connected to the circulating slurry tank through pipelines. The inlet of the slurry circulation pump is connected to the circulating slurry tank, and the outlet is connected to the spray device inside the absorption tower.

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

[0008] Furthermore, the split-type absorption tower is arranged at a high position, with its bottom not lower than the height of the liquid level in the slurry tank.

[0009] Furthermore, the split-type absorption tower is equipped with a spray device and a demister device arranged sequentially from bottom to top.

[0010] Furthermore, multiple circulating slurry tank agitators are arranged around the circulating slurry tank.

[0011] Furthermore, the circulating slurry tank is connected to the outlet of the desulfurizing agent addition pump, the outlet of the oxidation fan, and the inlet of the desulfurization by-product discharge pump.

[0012] The beneficial effects of this utility model are:

[0013] (1) The absorption zone and oxidation zone of wet desulfurization are separated into two completely independent devices, with the absorption device being a split-type absorption tower and the oxidation device being a circulating slurry tank. The two devices are connected by pipelines. This allows for the configuration of the absorption zone and oxidation zone according to the flue gas conditions, effectively avoiding mismatch and mutual constraints between the absorption zone and oxidation zone. This reduces the system's operating energy consumption and engineering cost.

[0014] (2) A configuration of multiple split-type absorption towers connected in parallel is adopted, and the offline operation of a single split-type absorption tower is achieved by closing the shut-off valves at the inlet and outlet of the split-type absorption flue gas. This improves the system's operational stability and availability.

[0015] (3) The combined structure of the pool and the flue gas with the circulating slurry pool set at the bottom of the chimney effectively reduces the system's footprint and improves the system's economy.

[0016] The technical solution of this utility model will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the device connection of this utility model;

[0018] In the diagram: 1. Split-type absorption tower, 2. Slurry circulation pump, 3. Spray pipe, 4. Demister, 5. Chimney, 6. Circulating slurry pool, 7. Circulating slurry pool agitator, 8. Desulfurizing 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 pipe shut-off valve, 14. Main flue. Detailed Implementation

[0019] Example 1:

[0020] This embodiment describes a split-type wet desulfurization method and apparatus for low-sulfur flue gas, such as... Figure 1 As shown, it includes: a split-type absorption tower 1, a slurry circulation pump 2, a spray pipe 3, a demister 4, a chimney 5, a circulating slurry pool 6, a circulating slurry pool agitator 7, a desulfurizing agent 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 pipe shut-off valve 13.

[0021] The split-type absorption tower 1 and the slurry tank 6 are not connected in an integrated manner. Multiple split-type absorption towers 1 are connected in parallel and evenly distributed around the slurry tank 6, sharing a single slurry tank 6. The chimney 5 is fixedly connected to the upper part of the circulating slurry tank 6 and is an integral structure with the chimney 5, which can make full use of space and reduce the floor area. The flue gas inlet of the split-type absorption tower 1 is connected to the main flue duct 14 via the flue gas inlet shut-off valve 11, and the outlet is connected to the chimney 5 via the flue gas outlet shut-off valve 12. The bottom is connected to the circulating slurry tank 6 through a pipeline. The inlet of the slurry circulation pump 2 is connected to the circulating slurry tank 6, and the outlet is connected to the spray device 3 inside the split-type absorption tower 1. The spray device 3 and the demister device 4 are arranged sequentially from bottom to top inside the split-type absorption tower 1.

[0022] Example 2:

[0023] Based on Example 1, the split-type absorption tower 1 described in this example is arranged at a high position, and the bottom height is not lower than the liquid level in the slurry pool 6.

[0024] Example 3:

[0025] This embodiment is a supplement to Embodiment 1, and it refines and limits the circulating slurry tank 6. In this embodiment, multiple circulating slurry tank agitators 7 are arranged around the circulating slurry tank 6. The circulating slurry tank 6 is also connected to the outlet of the desulfurizing agent addition pump 8, the outlet of the oxidation blower 10, and the inlet of the desulfurization by-product discharge pump 9.

[0026] Example 4:

[0027] This embodiment is a further limitation of Embodiment 1, and is a refinement of the split-type absorption tower 1. In this embodiment, two split-type absorption towers 1 are provided, and the two split-type absorption towers 1 are connected in parallel and symmetrically arranged on both sides of the circulating slurry tank 6.

[0028] The flue gas inlets of the two split-type absorption towers 1 are connected to the main flue via flue gas inlet shut-off valve 11, and the outlets are connected to the chimney 5 via flue gas outlet shut-off valve 12. The bottoms are connected to the circulating slurry pool 6. Spray pipes 3 and demisters 4 are arranged sequentially from bottom to top inside the split-type absorption towers 1. The inlet of the slurry circulation pump 2 is connected to the circulating slurry pool 6, and the outlet is connected to the spray pipe of the spray device 3 inside the split-type 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 integral 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 desulfurizing agent addition pump 8, the outlet of the oxidation fan 10, and the inlet of the desulfurization by-product discharge pump 9.

[0029] To better illustrate this utility model, the following is combined with... Figure 1 Explain its working process in detail.

[0030] During SO2 flue gas desulfurization, the slurry circulation pump 2 is started. The slurry containing desulfurizing agent in the circulating slurry tank 6 is pumped into the spray pipe 3 by the slurry circulation pump 2. After being sprayed from the top of the split-type absorption tower 1 to the bottom of the tower, it flows into the circulating slurry tank 6 by gravity, thus forming a circulating spray of slurry containing desulfurizing agent. The flue gas inlet shut-off valve 11 and the flue gas outlet shut-off valve 12 are opened, and the flue gas disperses into each of the parallel split-type absorption towers 1. As it flows upward along the tower, it comes into countercurrent contact with the circulating slurry sprayed and falling inside the tower. The SO2 in the flue gas is absorbed by the circulating slurry to form calcium sulfite. The desulfurized flue gas is then discharged into the atmosphere after converging in the chimney 5. Air is blown into the circulating slurry tank 6 by the oxidation blower 10 to oxidize the calcium sulfate in the circulating slurry into calcium sulfate. Part of the circulating slurry containing calcium sulfate is discharged as a desulfurization byproduct by the desulfurization byproduct discharge pump 9. Fresh desulfurizing agent slurry is supplied to the circulating slurry tank 6 by pump 8 to replenish the consumed desulfurizing agent.

[0031] When a parallel split-type absorption tower 1 needs to be shut down for maintenance, the flue gas inlet shut-off valve 11 and flue gas outlet shut-off valve 12 of that tower are closed, allowing for online maintenance of the split-type absorption tower 1 while the other absorption towers continue to operate.

[0032] When flue gas with a large flow rate but low SO2 concentration enters the system and needs desulfurization, the large flue gas volume results in a large cross-sectional area of ​​the split absorption tower 1 (absorption zone), while the low SO2 concentration results in a small cross-sectional area of ​​the circulating slurry tank 6 (oxidation zone). Therefore, the separate structure of the absorption zone and oxidation zone is adopted, which effectively avoids the defects of mismatch between the absorption zone and oxidation zone or passive enlargement of the oxidation zone, and passive enlargement of the circulating slurry tank agitator 7 and oxidation blower 10, thereby reducing operating energy consumption and improving system economy.

[0033] By employing a structure with multiple split-type absorption towers 1 (absorption zones) connected in parallel, the total flue gas flow area of ​​the absorption zone is increased, while offline maintenance of each individual split-type absorption tower 1 is achieved. This improves the system's operational stability and availability.

[0034] The split-type absorption tower 1 is arranged at a high position to enable the circulating slurry to flow back to the circulating slurry tank 6 by gravity. Therefore, the space at the bottom of the split-type absorption tower 1 can be effectively utilized. At the same time, the circulating slurry tank 6 and the chimney 5 are an integrated structure, so the entire system occupies only the projected area of ​​the circulating slurry tank 6, which effectively reduces the system's footprint and improves the system's economy.

[0035] In summary, this invention effectively avoids the mismatch between the absorption and oxidation zones in existing wet desulfurization technologies when applied to low-sulfur, high-volume flue gas conditions, and solves the deficiency of existing wet desulfurization technologies in that they cannot be maintained online. It boasts advantages such as small system footprint, low energy consumption, high system economy, overall safe and stable operation, and high system availability.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A split-type wet desulfurization device for low-sulfur flue gas, characterized in that, The split-type absorption tower (1) and the circulating slurry tank (6) are not integrated. Multiple split-type absorption towers (1) are connected in parallel, evenly distributed around the circulating slurry tank (6) and share one circulating slurry tank (6). The chimney (5) is fixedly connected to the upper part of the circulating slurry tank (6).

2. The low-sulfur flue gas split-type wet desulfurization device according to claim 1, characterized in that, The flue gas inlet of the split-type absorption tower (1) is connected to the main flue via a flue gas inlet shut-off valve (11), and the outlet is connected to the chimney (5) via a flue gas outlet shut-off valve (12). The bottom is connected to the circulating slurry tank (6) via a pipeline. The inlet of the slurry circulation pump (2) is connected to the circulating slurry tank (6), and the outlet is connected to the spray device (3) inside the split-type absorption tower (1).

3. The low-sulfur flue gas split-type wet desulfurization device according to claim 1, characterized in that, Two split-type absorption towers (1) are provided, symmetrically arranged on both sides of the circulating slurry tank (6).

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

5. The low-sulfur flue gas split-type wet desulfurization device according to claim 1, characterized in that, The split-type absorption tower (1) is equipped with a spray device (3) and a demister device (4) arranged sequentially from bottom to top.

6. The low-sulfur flue gas split-type wet desulfurization device according to claim 1, characterized in that, Multiple circulating slurry tank agitators (7) are arranged around the circulating slurry tank (6).

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

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