Sulfuric acid dry absorption equipment for adapting to humidity change

Abstract

The invention discloses sulfuric acid dry suction equipment for adapting to humidity change, which comprises a low-temperature heat recovery system, a drying system and a secondary suction system, when the environment humidity is increased, a central control system is used for increasing the opening degree of a first flow control device, a second flow control device and a fourth flow control device; the acid mixing amount from the low-temperature heat recovery system to the drying system and the acid mixing amount from the drying system to the low-temperature heat recovery system are increased; when the environment humidity is reduced, the central control system is used for reducing the opening degree of the three flow control devices so as to reduce the acid mixing amount from the low-temperature heat recovery system to the drying system and the acid mixing amount from the drying system to the low-temperature heat recovery system. The equipment can stabilize the acid concentration and reduce the acid mixing amount when the environment humidity is greatly changed, so that the adverse effects of reduced steam yield and increased circulating water consumption caused by the humidity change are reduced, the energy efficiency of the equipment in the area with the large humidity change is improved, and stable production of sulfuric acid is realized.

Description

Technical Field

[0001] This invention relates to the field of sulfuric acid production equipment technology, and more specifically, to a sulfuric acid dry absorption device for adapting to humidity changes. Background Technology

[0002] Sulfuric acid, hailed as the mother of the chemical industry, is a crucial upstream and downstream product in industries such as phosphate fertilizers, titanium dioxide, and laterite nickel hydrometallurgy. Nickel ore smelting requires a significant amount of sulfuric acid. The two-conversion, two-absorption process is currently the main production process for sulfuric acid production. The main energy proportions generated in each part of the equipment are as follows: sulfur combustion heat 52%, sulfur dioxide conversion heat 17%, sulfur trioxide absorption heat 28%, and main blower compression heat 3%. During heat recovery, the amount of medium- and high-pressure superheated steam produced as a byproduct is relatively stable, while the humidity of the low-pressure steam produced as a byproduct is a significant environmental factor affecting its yield.

[0003] In existing dry absorption equipment, the delivered sulfuric acid, the acid from the mixing and diluting unit of the low-temperature heat recovery system, and the secondary spray acid all originate from the drying tower system. However, in this situation, as the ambient humidity increases, the water absorption of the drying system increases, which leads to a decrease in the acid concentration of the drying system. To maintain a constant acid concentration in the drying system, it is necessary to increase the amount of acid from the low-temperature heat recovery system. This will remove heat from the low-temperature heat recovery system, resulting in a decrease in low-pressure steam production and an increase in circulating water consumption.

[0004] Therefore, there is an urgent need to develop a sulfuric acid dry absorption device that can stabilize acid concentration and reduce cross-contamination when the ambient humidity varies greatly. This would mitigate the adverse effects of humidity changes on reduced steam production and increased circulating water consumption, and improve the energy efficiency of sulfuric acid preparation equipment in areas with large humidity variations. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a sulfuric acid dry absorption device that adapts to humidity changes. This device can stabilize acid concentration and reduce cross-contamination when ambient humidity varies significantly, thereby mitigating the adverse effects of humidity-induced reductions in steam production and increased circulating water consumption. Furthermore, it improves the energy efficiency of sulfuric acid preparation equipment in areas with significant humidity variations, achieving stable sulfuric acid production.

[0006] The present invention provides a sulfuric acid dry absorption device for adapting to humidity changes, comprising a low-temperature heat recovery system, a drying system, and a secondary absorption system;

[0007] The low-temperature heat recovery system is equipped with a mixing and diluting device, the drying system is equipped with a drying tower acid tank, and the secondary absorption system is equipped with a secondary absorption tower acid tank. The drying tower acid tank is equipped with a first liquid level indicator controller. The other end of the first liquid level indicator controller is communicatively connected to a first flow control device on the main pipeline from the drying tower acid tank to the mixing and diluting device and the secondary absorption tower acid tank. The first flow control device is used to control the opening degree of the first flow control device according to the liquid level in the drying tower acid tank, thereby controlling the total flow rate of sulfuric acid flowing from the drying system into the low-temperature heat recovery system and the secondary absorption system.

[0008] A second flow control device is installed on the first branch of the main pipeline leading to the mixing and diluting unit. The drying system is equipped with a drying tower. A first acid concentration detection device is installed on the lower acid pipeline of the drying tower. The first acid concentration detection device is also communicatively connected to the second flow control device. It is used to control the opening of the second flow control device according to the acid concentration of the lower acid pipeline of the drying tower, so as to control the flow rate of sulfuric acid from the acid tank of the drying tower to the mixing and diluting unit.

[0009] A third flow control device is installed on the second branch of the main pipeline of the drying tower leading to the acid tank of the second absorption tower. The second absorption system also includes a second absorption acid cooler. A second acid concentration detection device is installed between the second absorption acid cooler and the acid tank of the second absorption tower. The second acid concentration detection device is communicatively connected to the third flow control device and is used to control the opening of the third flow control device according to the acid concentration of the second absorption system, so as to control the flow rate of sulfuric acid from the acid tank of the drying tower to the acid tank of the second absorption tower.

[0010] The drying system also includes a drying acid cooler. A third acid concentration detection device is provided between the drying tower acid tank and the drying acid cooler. The third acid concentration detection device is communicatively connected to a fourth flow control device located on the pipeline from the low-temperature heat recovery system to the drying tower acid tank. The third flow control device is used to control the opening of the fourth flow control device according to the acid concentration of the drying system, thereby controlling the flow rate of sulfuric acid from the low-temperature heat recovery system to the drying tower acid tank.

[0011] It also includes a central control system, which is communicatively connected to the first liquid level indicator controller, the first flow control device, the first acid concentration detection device, the second flow control device, the third flow control device, the second acid concentration detection device, the third acid concentration detection device, and the fourth flow control device.

[0012] When the ambient humidity increases, the central control system is used to increase the opening of the first flow control device, the second flow control device and the fourth flow control device, so as to increase the amount of acid carried from the low temperature heat recovery system to the drying system and the amount of acid carried from the drying system to the low temperature heat recovery system.

[0013] When the ambient humidity decreases, the central control system reduces the opening of the first flow control device, the second flow control device, and the fourth flow control device to reduce the amount of acid carried from the low-temperature heat recovery system to the drying system and the amount of acid carried from the drying system to the low-temperature heat recovery system.

[0014] Preferably, in the above-mentioned sulfuric acid dry absorption equipment for adapting to humidity changes, the acid tank of the second absorption tower is further provided with a demineralized water inlet pipeline, and a fifth flow control device is provided on the demineralized water inlet pipeline. The second acid concentration detection device is also communicatively connected to the fifth flow control device, and the central control system is also communicatively connected to the fifth flow control device. The fifth flow control device is used to input demineralized water into the acid tank of the second absorption tower to maintain the acid concentration of the second absorption system stable after the amount of acid flowing from the acid tank of the drying tower decreases.

[0015] Preferably, in the above-mentioned sulfuric acid dry absorption equipment for adapting to humidity changes, a second liquid level indicator controller is provided in the acid tank of the second absorption tower. The other end of the second liquid level indicator controller is communicatively connected to a sixth flow control device on the pipeline from the finished acid cooler to the finished acid underground tank. The sixth flow control device is used to control the opening degree of the sixth flow control device according to the liquid level in the acid tank of the second absorption tower, so as to control the flow rate of sulfuric acid flowing into the finished acid underground tank from the second absorption system.

[0016] Preferably, in the above-mentioned sulfuric acid dry absorption equipment for adapting to humidity changes, the circulation pipeline of the drying system further includes a drying tower acid pump and a drying acid cooler, and the acid concentration in the upper tower acid pipeline of the drying system and the acid concentration leading to the mixing diluent are 95%.

[0017] Preferably, in the above-mentioned sulfuric acid dry absorption equipment for adapting to humidity changes, a first flow indicator controller is provided on the pipeline from the dry acid cooler to the drying tower. The first flow indicator controller is also communicatively connected to the central control system for controlling the flow rate of sulfuric acid entering the drying tower from the dry acid cooler.

[0018] Preferably, in the above-mentioned sulfuric acid dry absorption equipment for adapting to humidity changes, the secondary absorption system further includes a secondary absorption tower acid pump and a secondary absorption tower. The pipeline from the secondary absorption acid cooler to the secondary absorption tower also has a first bypass leading to the finished product acid cooler. The finished product acid underground tank is also connected to the finished product acid tank area by a finished product acid transfer pump to output externally delivered product acid.

[0019] Preferably, in the above-mentioned sulfuric acid dry absorption equipment for adapting to humidity changes, the pipeline from the secondary absorption acid cooler to the secondary absorption tower also has a second bypass leading to the low-temperature heat recovery system for conveying secondary spray acid.

[0020] Preferably, in the above-mentioned sulfuric acid dry absorption equipment for adapting to humidity changes, the pipeline from the secondary absorption acid cooler to the secondary absorption tower is further equipped with a second flow indicator controller. The second flow indicator controller is also communicatively connected to the central control system for controlling the flow rate of sulfuric acid entering the secondary absorption tower from the secondary absorption acid cooler.

[0021] Preferably, in the above-mentioned sulfuric acid dry absorption equipment for adapting to humidity changes, the circulation pipeline of the low-temperature heat recovery system includes the mixing diluent, the low-temperature heat recovery tower, the low-temperature heat recovery boiler, the heater and the preheater connected in sequence, and the other end of the preheater is connected to the drying system and the secondary absorption system.

[0022] Preferably, in the above-mentioned sulfuric acid dry absorption equipment for adapting to humidity changes, a third flow indicator controller is provided on the second bypass. The third flow indicator controller is also communicatively connected to the central control system for controlling the flow rate of the secondary spray acid entering the low-temperature heat recovery system from the secondary absorption acid cooler.

[0023] As can be seen from the above technical solution, the sulfuric acid dry absorption device for adapting to humidity changes provided by the present invention includes a low-temperature heat recovery system, a drying system, and a secondary absorption system. When the ambient humidity increases, the central control system increases the opening of the first flow control device, the second flow control device, and the fourth flow control device to increase the amount of acid flowing from the low-temperature heat recovery system to the drying system and from the drying system to the low-temperature heat recovery system. When the ambient humidity decreases, the central control system decreases the opening of the first flow control device, the second flow control device, and the fourth flow control device to reduce the amount of acid flowing from the low-temperature heat recovery system to the drying system and from the drying system to the low-temperature heat recovery system. The system's acid cross-contamination rate demonstrates that this scheme, by optimizing the acid concentration in the drying system, reduces the concentration of the externally added acid entering the mixing and diluting unit when ambient humidity increases. Therefore, to achieve the same dilution effect, less acid cross-contamination is required for lower concentration acids, resulting in a lower acid cross-contamination rate. Furthermore, because the concentration difference between the two mixed acids is greater, the heat of dilution released during mixing is greater, leading to higher low-pressure steam production. Moreover, by reducing the acid cross-contamination rate with the low-temperature heat recovery system, the heat that the drying system needs to remove via circulating water is reduced. Thus, this equipment can stabilize acid concentration and reduce acid cross-contamination even when ambient humidity fluctuates significantly. This mitigates the adverse effects of humidity changes on steam production and increased circulating water consumption, improves the energy efficiency of sulfuric acid preparation equipment in areas with large humidity variations, and achieves stable sulfuric acid production. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of an embodiment of a sulfuric acid dry absorption device for adapting to humidity changes provided by the present invention.

[0026] The annotations in the attached figures are explained as follows:

[0027] Low-temperature heat recovery system A1, drying system A2, secondary suction system A3, mixing and diluting unit 1, drying tower acid tank 2, secondary suction tower acid tank 3, first liquid level indicator controller 4, first flow control device 5, second flow control device 6, drying tower 7, first acid concentration detection device 8, third flow control device 9, secondary suction acid cooler 10, second acid concentration detection device 11, drying acid cooler 12, third acid concentration detection device 13, fourth flow control device 14, central control system A4, demineralized water inlet pipeline 15. Fifth flow control device; 16. Second liquid level indicator controller; 17. Finished acid cooler; 18. Finished acid underground tank; 19. Sixth flow control device; 20. Drying tower acid pump; 21. First flow indicator controller; 22. Second suction tower acid pump; 23. Second suction tower; 24. Finished acid transfer pump; 25. Finished acid tank area; 26. Second bypass; 27. Second flow indicator controller; 28. Low temperature heat recovery tower; 29. ​​Low temperature heat recovery boiler; 30. Heater; 31. Preheater; 32. Third flow indicator controller; 33. Detailed Implementation

[0028] The core of this invention is to provide a sulfuric acid dry absorption device that adapts to humidity changes. It can stabilize acid concentration and reduce cross-contamination when the ambient humidity changes significantly, thereby reducing the adverse effects of humidity changes on reduced steam production and increased circulating water consumption. Furthermore, it improves the energy efficiency of sulfuric acid preparation equipment in areas with large humidity variations, and achieves stable sulfuric acid production.

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] An embodiment of the sulfuric acid dry adsorption device for adapting to humidity changes provided by the present invention is as follows: Figure 1 As shown, Figure 1This is a schematic diagram of an embodiment of a sulfuric acid dry absorption device for adapting to humidity changes provided by the present invention. The device may include a low-temperature heat recovery system A1, a drying system A2, and a secondary absorption system A3. It should be noted that the low-temperature heat recovery system A1 absorbs SO3 from the first three stages of conversion gas, accounting for approximately 95% of the total SO2 conversion rate. After absorption, the acid concentration of the low-temperature heat recovery system increases by approximately 0.5%. In this scheme, the main sulfuric acid produced, the heat of reaction generated, and the dilution heat generated from the acid series reaction in the drying system A2 all originate from the low-temperature heat recovery system A1. The drying system A2 provides dry air for sulfuric acid combustion by absorbing moisture from the air. The secondary absorption system A3 absorbs SO3 from the last stage of conversion gas through spray acid to produce sulfuric acid. Since the last stage of conversion accounts for approximately 5% of the total SO2 conversion rate, the increase in acid concentration of the secondary absorption system after absorption is less than 0.1%. In this scheme, the externally supplied product acid and the secondary spray acid from the low-temperature heat recovery system A1 originate from the secondary absorption system A3, and the acid concentration of the secondary absorption system A3 is 98.5%.

[0031] The low-temperature heat recovery system A1 is equipped with a mixing and diluting device 1. This device mixes low-concentration sulfuric acid (95% concentration) and high-concentration sulfuric acid (e.g., 99.5% concentration) from the drying system to form sulfuric acid of the required concentration for the primary spraying of the low-temperature heat recovery system A1, which is then transferred to the low-temperature heat recovery system A1. The drying system A2 is equipped with a drying tower acid tank 2, which receives sulfuric acid from the low-temperature heat recovery system A1 and forms a sulfuric acid circulation within the drying system. The secondary absorption system A3 is equipped with a secondary absorption tower acid tank 3, which receives sulfuric acid from both the low-temperature heat recovery system A1 and the drying system A2 and forms a circulation within the secondary absorption system. The drying tower acid tank 2 is equipped with a first liquid level indicator controller 4, which can... The first liquid level indicator controller 4 is capable of detecting the liquid level in the acid tank 2 of the drying tower. The other end of the first liquid level indicator controller 4 is communicatively connected to the first flow control device 5 on the main pipeline of the drying tower from the acid tank 2 of the drying tower to the mixing diluent 1 and the acid tank 3 of the secondary absorption tower. It is used to control the opening of the first flow control device 5 according to the liquid level in the acid tank 2 of the drying tower, so as to control the total flow of sulfuric acid flowing from the drying system A2 into the low temperature heat recovery system A1 and the secondary absorption system A3. It should be noted that when the liquid level in the acid tank 2 of the drying tower is too high, the opening of the first flow control device 5 can be increased to allow more sulfuric acid to flow into the low temperature heat recovery system A1 and the secondary absorption system A3, thereby reducing the liquid level in the acid tank 2 of the drying tower. Conversely, the liquid level in the acid tank 2 of the drying tower is kept within a relatively safe range.

[0032] The first branch of the main pipeline leading to the mixing and diluting unit 1 of the aforementioned drying tower is equipped with a second flow control device 6. The drying system A2 is equipped with a drying tower 7. The lower acid pipeline of the drying tower 7 is equipped with a first acid concentration detection device 8. The first acid concentration detection device 8 is also communicatively connected to the second flow control device 6. It is used to control the opening of the second flow control device 6 according to the acid concentration of the lower acid pipeline of the drying tower 7, so as to control the flow rate of sulfuric acid from the acid tank 2 of the drying tower to the mixing and diluting unit 1. It can be seen that the flow rate of sulfuric acid from the acid tank of the drying tower to the mixing and diluting unit can be controlled according to the acid concentration of the lower acid pipeline of the drying tower. This is because different external humidity will cause the acid concentration of the lower tower of the drying tower to change. This method can be used to adjust the flow rate according to the external humidity.

[0033] A third flow control device 9 is installed on the second branch of the main pipeline from the drying tower to the acid tank 3 of the secondary suction tower. The secondary suction system A2 also includes a secondary suction acid cooler 10. A second acid concentration detection device 11 is installed between the secondary suction acid cooler 10 and the acid tank 3 of the secondary suction tower. The second acid concentration detection device 11 is communicatively connected to the third flow control device 9 and is used to control the opening of the third flow control device 9 according to the acid concentration of the secondary suction system A3, thereby controlling the flow rate of sulfuric acid from the acid tank 2 of the drying tower to the acid tank 3 of the secondary suction tower. It should be noted that the purpose of this third flow control device 9 is to ensure a constant flow rate to guarantee the spray flow rate to the low-temperature heat recovery system A1 and avoid [further issues]. Low flow rate can lead to two consequences: first, the absorption effect of the low-temperature heat recovery tower is affected; second, the high temperature of the flue gas after absorption can damage the internal components of the tower. Controlling the flow rate here to prevent fluctuations can avoid affecting the operation of other control points and devices. The third flow control device 9 is always on regardless of the humidity level in the environment. Above the equilibrium humidity, the third flow control device 9 will adjust according to the acid concentration of the second absorption tower. When the acid concentration increases, the opening of the third flow control device 9 increases; when the acid concentration decreases, the opening of the third flow control device 9 decreases. The third flow control device 9 has a minimum opening point, which corresponds to the operating condition with the highest humidity.

[0034] The drying system A2 also includes a drying acid cooler 12. A third acid concentration detection device 13 is installed between the drying tower acid tank 2 and the drying acid cooler 12. The third acid concentration detection device 13 is communicatively connected to a fourth flow control device 14 located on the pipeline from the low-temperature heat recovery system A1 to the drying tower acid tank 2. It is used to control the opening of the fourth flow control device 14 according to the acid concentration of the drying system A2, so as to control the flow rate of sulfuric acid from the low-temperature heat recovery system A1 to the drying tower acid tank 2. It should be noted that when the external humidity is high, resulting in a low acid concentration detected by the third acid concentration detection device 13, the opening of the fourth flow control device 14 needs to be increased to allow more high-concentration sulfuric acid to flow from the low-temperature heat recovery system A1 into the drying system, and vice versa. It can be seen that this can better adapt to changes in the humidity of the external environment.

[0035] It also includes a central control system A4, which is communicatively connected to a first liquid level indicator controller 4, a first flow control device 5, a first acid concentration detection device 8, a second flow control device 6, a third flow control device 9, a second acid concentration detection device 11, a third acid concentration detection device 13, and a fourth flow control device 14. It should be noted that, to avoid cluttered wiring, in... Figure 1 These connections are not shown in the document. This central control system A4 can be, but is not limited to, a DCS system.

[0036] When the ambient humidity increases, the central control system A4 increases the opening of the first flow control device 5, the second flow control device 6, and the fourth flow control device 14 to increase the amount of acid flowing from the low-temperature heat recovery system A1 to the drying system A2 and from the drying system A2 to the low-temperature heat recovery system A1. It should be noted that in this case, when the ambient air humidity increases, the moisture absorbed by the drying system A2 also increases. In order to maintain the acid concentration balance in the drying system A2, more high-concentration sulfuric acid from the low-temperature heat recovery system A1 needs to be added. Since the excess 95% concentration of sulfuric acid for balancing the acid concentration returns to the mixing and diluting device 1 of the low-temperature heat recovery system A1, it is necessary to increase the opening of the first flow control device 5, the second flow control device 6, and the fourth flow control device 14 to increase the amount of acid flowing. It can be seen that this can effectively cope with the situation of increased ambient humidity.

[0037] When the ambient humidity decreases, the central control system A4 reduces the opening of the first flow control device 5, the second flow control device 6, and the fourth flow control device 14 to reduce the amount of acid carried from the low-temperature heat recovery system A1 to the drying system A2 and from the drying system A2 to the low-temperature heat recovery system A1. It should be noted that a decrease in ambient air humidity means a decrease in the moisture in the air. The dryer A2 absorbs less moisture, which leads to a decrease in the amount of concentrated acid required for balancing. Therefore, it is necessary to reduce the amount of acid carried. In actual control, the opening of the first flow control device 5, the second flow control device 6, and the fourth flow control device 14 is reduced until the humidity is balanced, and the amount of acid carried from the drying system A2 to the mixing diluent 1 of the low-temperature heat recovery system A1 is reduced to 0.

[0038] It should also be noted that when the ambient humidity increases or decreases, the opening of the third flow control device 9 remains constant. When the ambient humidity continues to decrease and falls below the equilibrium humidity, not only is the flow rate of the drying system A2 to the mixing diluter 1 zero, but the amount of acid sent to the secondary absorption system A3 also continues to decrease. This means that the acid production of the drying system A2 decreases as the ambient humidity decreases, resulting in a decrease in the amount of acid sent to the secondary absorption system A3 even if the opening of the third flow control device 9 remains constant.

[0039] As can be seen from the above technical solutions, in the embodiments of the sulfuric acid dry absorption device for adapting to humidity changes provided by the present invention, since it includes a low-temperature heat recovery system, a drying system, and a secondary absorption system, when the ambient humidity increases, the central control system increases the opening of the first flow control device, the second flow control device, and the fourth flow control device to increase the amount of acid flowing from the low-temperature heat recovery system to the drying system and from the drying system to the low-temperature heat recovery system; when the ambient humidity decreases, the central control system decreases the opening of the first flow control device, the second flow control device, and the fourth flow control device to reduce the amount of acid flowing from the low-temperature heat recovery system to the drying system. The amount of acid carried over from the drying system and the amount of acid carried over from the drying system to the low-temperature heat recovery system demonstrates that this scheme, by optimizing the acid concentration in the drying system and adjusting the source of the finished acid and the secondary spray acid in the low-temperature heat recovery system, can achieve low acid carryover and high low-pressure steam output when humidity increases. Moreover, by reducing the amount of acid carried over from the low-temperature heat recovery system, the amount of heat that the drying system needs to carry away with circulating water is reduced. Thus, this equipment can stabilize the acid concentration and reduce the amount of acid carried over when the ambient humidity varies greatly, thereby mitigating the adverse effects of humidity changes on reduced steam production and increased circulating water consumption. Furthermore, it improves the energy efficiency of sulfuric acid preparation equipment in areas with large humidity variations, achieving stable sulfuric acid production.

[0040] In a specific embodiment of the sulfuric acid dry absorption equipment described above for adapting to humidity changes, the acid tank 3 of the secondary absorption tower can also be provided with a demineralized water inlet pipe 15. A fifth flow control device 16 is provided on the demineralized water inlet pipe 15. The aforementioned second acid concentration detection device 11 is also communicatively connected to the fifth flow control device 16. The central control system A4 is also communicatively connected to the fifth flow control device 16. The fifth flow control device 16 is used to input demineralized water into the acid tank 3 of the secondary absorption tower after the amount of acid from the drying tower acid tank decreases, so as to maintain the acid concentration of the secondary absorption system A2 stable. It should be noted that when the ambient humidity drops below the equilibrium humidity, if the humidity continues to decrease, the amount of sulfuric acid produced by the drying system A2 to balance the acid concentration will continue to decrease, resulting in a reduction in the amount of supplementary acid going to the secondary absorption system A3. Since the acid concentration of the drying system A2 is lower than that of the secondary absorption system A3, the reduced amount of acid carried over between them is equivalent to a decrease in the dilution effect on the secondary absorption system A3. In this case, to balance the acid concentration of the secondary absorption system A3, the fifth flow control device 16 can be opened to input demineralized water into the acid tank 3 of the secondary absorption tower, ensuring the stability of the acid concentration in the secondary absorption system. As the humidity in the external environment increases, the opening of the fifth flow control device 16 is reduced using the central control system. When the critical point is reached, the fifth flow control device 16 is completely closed. Through the above-mentioned acid concentration and liquid level regulation, the entire equipment can still operate stably and fully automatically under conditions of extreme humidity changes, achieving automation and intelligence, and reducing manual operation costs.

[0041] In another specific embodiment of the sulfuric acid dry absorption equipment described above for adapting to humidity changes, a second liquid level indicator controller 17 is installed in the acid tank 3 of the second absorption tower. The other end of the second liquid level indicator controller 17 is communicatively connected to a sixth flow control device 20 on the pipeline from the finished acid cooler 18 to the finished acid underground tank 19. This sixth flow control device 20 is used to control the opening degree of the sixth flow control device 20 based on the liquid level in the acid tank 3 of the second absorption tower, thereby controlling the flow rate of sulfuric acid flowing from the second absorption system A3 into the finished acid underground tank 19. It should be noted that, to ensure the stability of the liquid level in the acid tank 3 of the second absorption system, this second liquid level indicator controller 17 and the sixth flow control device 20 are configured to control the amount of finished acid delivered, thus ensuring the stability of the operation of the second absorption system A3.

[0042] In another specific embodiment of the sulfuric acid dry absorption device for adapting to humidity changes, the circulation pipeline of the drying system A2 further includes a drying tower acid pump 21 and the aforementioned drying acid cooler 12. The acid concentration in the upper tower acid pipeline of the drying system A2, as well as the acid concentration leading to the mixing diluent 1, is 95%. It should be noted that the acid concentration entering the drying tower is not less than 95%, and the acid temperature is approximately 60°C, to ensure sufficient air drying effect. Since the acid concentration leading to the mixing diluent 1 in the low-temperature heat recovery system A1 is 95%, less acid is needed to achieve the same dilution effect, while excess acid from the drying system A2 is transferred to the secondary absorption system A3.

[0043] In a preferred embodiment of the sulfuric acid dry absorption device described above for adapting to humidity changes, a first flow indicator controller 22 may be installed on the pipeline leading from the dryer / cooler 12 to the drying tower 7. The first flow indicator controller 22 is also communicatively connected to the central control system A4 for controlling the flow rate of sulfuric acid entering the drying tower 7 from the dryer / cooler 12. In this case, the stability of the sulfuric acid flow rate entering the drying tower can be guaranteed.

[0044] In another preferred embodiment of the sulfuric acid dry absorption equipment described above for adapting to humidity changes, the secondary absorption system A3 further includes a secondary absorption tower acid pump 23 and a secondary absorption tower 24. The pipeline from the secondary absorption acid cooler 10 to the secondary absorption tower 24 also has a first bypass leading to the finished product acid cooler 18. The finished product acid underground tank 19 is also connected to the finished product acid tank area 26 via the finished product acid transfer pump 25 to output externally delivered product acid. In yet another preferred embodiment of the sulfuric acid dry absorption equipment described above for adapting to humidity changes, the pipeline from the secondary absorption acid cooler 10 to the secondary absorption tower 24 also has a second bypass 27 leading to the low-temperature heat recovery system A1 to transport secondary spray acid. It should be noted that the concentration of the secondary spray acid from the secondary absorption system A3 into the secondary absorption tower 24 and sent to the low-temperature heat recovery system A1 is preferably not less than 98.5% to ensure good absorption of SO3 in the conversion gas and to meet the concentration requirements of the finished acid to be sent out. After the secondary absorption acid is cooled to 60°C by the secondary absorption acid cooler 10, it is sent to the finished acid cooler to be cooled to 40°C and then sent to the finished acid underground tank 19 for buffering. Finally, it is pumped to the finished acid tank area 26. Moreover, the outlet acid concentration of the above-mentioned mixing and diluting device 1 is not less than 99%.

[0045] In a further embodiment, the pipeline from the secondary suction acid cooler 10 to the secondary suction tower 24 is also equipped with a second flow indicator controller 28. The second flow indicator controller 28 is also communicatively connected to the central control system A4 to control the flow rate of sulfuric acid entering the secondary suction tower 24 from the secondary suction acid cooler 10, so as to better ensure the stability of the flow rate of sulfuric acid entering the secondary suction tower 24.

[0046] Furthermore, the circulation pipeline of the low-temperature heat recovery system A1 includes the aforementioned mixing and diluting unit 1, low-temperature heat recovery tower 29, low-temperature heat recovery boiler 30, heater 31, and preheater 32 connected in sequence. The other end of the preheater 32 is connected to the drying system A2 and the secondary suction system A3. It should be noted that the low-temperature heat recovery tower 29 also includes a related pump.

[0047] Furthermore, a third flow indicator controller 33 can be installed on the second bypass 27. The third flow indicator controller 33 is also communicatively connected to the central control system A4 to control the flow rate of the secondary spray acid entering the low-temperature heat recovery system A1 from the secondary absorption acid cooler 10. This will enable more stable control of the flow rate of sulfuric acid entering the low-temperature heat recovery system from the secondary absorption system, ensuring the stable operation of the entire equipment.

[0048] The control method for the sulfuric acid dry absorption equipment described above, which adapts to changes in humidity, can be as follows:

[0049] Because drying system A2 absorbs moisture from the air, the acid concentration exiting drying tower 7 decreases. To maintain the acid concentration in drying system A2, high-concentration sulfuric acid from low-temperature heat recovery system A1 needs to be introduced. Therefore, a corresponding acid concentration detection device is configured, and the amount of acid introduced from low-temperature heat recovery system A1 is adjusted. The excess sulfuric acid from drying system A2 to balance the acid concentration is sent to the mixing and diluting unit 1 of low-temperature heat recovery system A1 as a concentration-adjusting acid, and also enters the secondary absorption system A3 as a supplementary acid. The absorption of SO3 from the flue gas by the secondary absorption system A3 increases the acid concentration exiting the secondary absorption tower 24. Furthermore, the introduction of approximately 99.5% sulfuric acid from the low-temperature heat recovery system A1 also increases the acid concentration exiting the secondary absorption system A3. To balance the acid concentration in the secondary absorption system A3, a corresponding acid concentration detection device is configured, and the amount of 95% low-concentration acid from the drying system A2 is adjusted. Additionally, a fifth flow control device 16 is installed on the demineralized water inlet pipeline 15 to control the amount of demineralized water added to the secondary absorption system A3, ensuring stable acid concentration in the secondary absorption system A3 under low humidity conditions. To ensure stable liquid level in the drying tower acid tank 2 of the drying system A2, a first liquid level indicator controller 4 is configured to adjust the amount of acid flowing through the main pipeline from the mixing and diluting unit 1 to the low-temperature heat recovery system A1 and the secondary absorption tower acid tank 3 of the secondary absorption system A3, thereby ensuring the operational stability of the drying system A2. To balance the acid concentration, excess sulfuric acid in the secondary absorption system A3 is sent to the secondary spray of the low-temperature heat recovery system A1 as absorption acid and as exported finished acid. To ensure the spray density of the secondary spray acid in the low-temperature heat recovery system A1, a third flow indicator controller 33 is configured to ensure a stable amount of secondary spray acid going to the low-temperature heat recovery system A1. To ensure a stable liquid level in the secondary absorption tower acid tank 3 in the secondary absorption system A3, a second liquid level indicator controller 17 is configured to ensure a stable amount of exported finished acid, thus ensuring the stable operation of the secondary absorption system A3.

[0050] When the humidity in the air decreases, the amount of high-concentration sulfuric acid introduced from the low-temperature heat recovery system A1 to maintain the acid concentration of the drying system A2 decreases, resulting in a decrease in the amount of excess sulfuric acid in the equilibrium acid concentration. When the air humidity decreases to a certain value, the amount of excess sulfuric acid in the equilibrium acid concentration becomes the same as the amount of supplementary acid going to the secondary absorption system A3. At this time, the amount of diluent going to the mixing diluent 1 in the low-temperature heat recovery system A1 is zero. This humidity is the equilibrium humidity. Under ambient humidity conditions below this value, the amount of diluent going to the mixing diluent 1 is always zero. Due to the function of the third acid concentration detection device 13 and the first flow indicator controller 22, the amount and concentration of acid entering the drying tower 7 remain constant. Therefore, the acid concentration at the bottom of the drying tower will increase due to the decrease in air humidity (assuming that under high humidity conditions, the acid concentration at the bottom of the drying tower is 94.5 wt%; when the humidity decreases to the equilibrium humidity, the acid concentration at the bottom of the drying tower is 94.7 wt%. Therefore, when the acid concentration at the bottom of the drying tower is ≥94.7 wt%, the amount of acid going to the mixing diluent as concentration-adjusting acid is always zero). At this time, a first acid concentration detection device 8 is installed on the lower acid pipeline of drying tower 7 to adjust the amount of diluted acid going to the mixing and diluting unit 1 of the low-temperature heat recovery system A1. When the acid concentration reaches or exceeds the acid concentration at the bottom of the drying tower corresponding to the equilibrium humidity, the opening of the regulating valve is 0; if it is lower than this acid concentration value, the opening is increased. To ensure the stability of the liquid level in the acid tank 2 of the drying tower in the drying system, a first liquid level indicator controller 4 is configured to adjust the amount of equilibrium acid sent out by the drying system A2 to ensure the stable operation of the drying system A2.

[0051] The absorption of SO3 from the flue gas by the secondary absorption system A3 will increase the acid concentration at the secondary absorption tower 24. The introduction of approximately 99.5% sulfuric acid from the low-temperature heat recovery system A1 will also increase the acid concentration at the outlet of the secondary absorption system A3. To balance the acid concentration in the secondary absorption system A3, a second acid concentration detection device 11 is configured to regulate the amount of 95% low-concentration acid from the drying system A1. An additional fifth flow control device 16 is installed to control the amount of demineralized water added to the secondary absorption system A3 in a segmented manner, ensuring stable acid concentration in the secondary absorption system A3 under low humidity conditions. The excess sulfuric acid from the secondary absorption system A3 used to balance the acid concentration is sent to the secondary spray of the low-temperature heat recovery system A1 as absorption acid and as exported finished acid. To ensure the spray density of the secondary spray acid in the low-temperature heat recovery system A1, a third flow indicator controller 33 is configured to ensure stable secondary spray acid flow to the low-temperature heat recovery system A1. For example, if the outlet flue gas temperature of the low-temperature heat recovery tower is too high or the acid mist content is too high, it means that the spray volume is too small. In this case, the spray volume needs to be increased, which requires modifying the corresponding flow value of the central control system and increasing the opening of the third flow indicator controller 33 to meet the corresponding requirements.

[0052] It is evident that by using the above-mentioned equipment, the amount of acid cross-contamination between the drying system and the low-temperature heat recovery system can be reduced, and the acid concentration of the delivered product and the acid concentration of the secondary spray in the low-temperature heat recovery system can be stabilized, thus achieving stable production of sulfuric acid under different environmental humidity conditions.

[0053] The equipment provided in this application optimizes the acid concentration in the drying system, adjusts the externally supplied finished acid, and utilizes the secondary spray acid source in the low-temperature heat recovery system. This results in low acid cross-contamination and high low-pressure steam production even when humidity is high. Specifically, taking Sulawesi Island in Indonesia, where humidity varies significantly, as an example, under traditional processes, acid cross-contamination increases by 102% and low-pressure steam production decreases by 47% under high humidity conditions in summer compared to the annual average humidity. However, using this equipment, the acid cross-contamination under the annual average humidity and high humidity conditions in summer are 16.7% and 19.2% of that under traditional processes, respectively; the low-pressure steam production is 143% and 235% of that under traditional conditions, respectively. Furthermore, the steam production of this equipment under high humidity conditions in summer is only 13.4% lower than under the annual average humidity, meaning that humidity changes have a smaller impact on the steam production of this equipment. By reducing the amount of acid exchanged with the low-temperature heat recovery system, the amount of heat that the drying system needs to remove with circulating water is reduced, resulting in lower circulating water consumption and a smaller circulating water station. For example, in Indonesia, this equipment reduces circulating water consumption by 20.5% and 37.2% under average annual humidity and high summer humidity conditions, respectively, compared to traditional processes. Furthermore, the circulating water consumption under high summer humidity is only 12% higher than under average annual humidity, while the traditional process is 41.8% higher. After exiting the acid cooler in the second absorption tower, the finished acid only needs to be cooled from 60℃ to 40℃. The temperature difference on the acid side of the finished acid cooler is 20℃. This small temperature difference reduces the impact of circulating water temperature fluctuations on the cooling effect of the finished acid cooler during high summer temperatures.

[0054] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A sulfuric acid dry absorption plant for adapting to humidity changes, characterized in that, The low-temperature heat recovery system, the drying system and the secondary absorption system; The low-temperature heat recovery system is provided with a mixing diluter, the drying system is provided with a drying tower acid tank, the secondary absorption system is provided with a secondary absorption tower acid tank, the drying tower acid tank is provided with a first liquid level indicating controller, one end of the first liquid level indicating controller is connected to a first flow control device on a drying tower outer sending main pipeline leading from the drying tower acid tank to the mixing diluter and the secondary absorption tower acid tank, and the other end of the first liquid level indicating controller is connected to the first flow control device, so as to control the opening of the first flow control device according to the liquid level in the drying tower acid tank, and to control the total flow of sulfuric acid flowing from the drying system to the low-temperature heat recovery system and the secondary absorption system; The first branch of the drying tower outer sending main pipeline leading to the mixing diluter is provided with a second flow control device, the drying system is provided with a drying tower, the lower tower acid pipeline of the drying tower is provided with a first acid concentration detection device, and the first acid concentration detection device is further connected to the second flow control device, so as to control the opening of the second flow control device according to the acid concentration of the lower tower acid pipeline of the drying tower, and to control the flow of sulfuric acid flowing from the drying tower acid tank to the mixing diluter; The second branch of the drying tower outer sending main pipeline leading to the secondary absorption tower acid tank is provided with a third flow control device, the secondary absorption system further comprises a secondary absorption acid cooler, a second acid concentration detection device is arranged between the secondary absorption acid cooler and the secondary absorption tower acid tank, and the second acid concentration detection device is connected to the third flow control device, so as to control the opening of the third flow control device according to the acid concentration of the secondary absorption system, and to control the flow of sulfuric acid flowing from the drying tower acid tank to the secondary absorption tower acid tank; The drying system further comprises a drying acid cooler, a third acid concentration detection device is arranged between the drying tower acid tank and the drying acid cooler, and the third acid concentration detection device is connected to a fourth flow control device on a pipeline leading from the low-temperature heat recovery system to the drying tower acid tank, so as to control the opening of the fourth flow control device according to the acid concentration of the drying system, and to control the flow of sulfuric acid flowing from the low-temperature heat recovery system to the drying tower acid tank; The central control system is connected to the first liquid level indicating controller, the first flow control device, the first acid concentration detection device, the second flow control device, the third flow control device, the second acid concentration detection device, the third acid concentration detection device and the fourth flow control device; When the environmental humidity increases, the central control system is used to increase the opening of the first flow control device, the second flow control device and the fourth flow control device, so as to increase the amount of serial acid flowing from the low-temperature heat recovery system to the drying system and the amount of serial acid flowing from the drying system to the low-temperature heat recovery system. When the ambient humidity decreases, the central control system is configured to reduce the opening degree of the first flow control device, the second flow control device and the fourth flow control device to reduce the amount of sour acid from the low-temperature heat recovery system to the drying system and the amount of sour acid from the drying system to the low-temperature heat recovery system.

2. The sulfuric acid dry absorption plant for adapting to humidity changes according to claim 1, characterized in that, The second absorption tower acid tank is further provided with a desalted water inlet pipeline, the fifth flow control device is arranged on the desalted water inlet pipeline, the second acid concentration detection device is further communicatively connected to the fifth flow control device, and the central control system is further communicatively connected to the fifth flow control device, so as to open the fifth flow control device to input desalted water into the second absorption tower acid tank to keep the acid concentration of the second absorption system stable when the amount of sour acid from the drying tower acid tank decreases.

3. The sulfuric acid dry absorption plant for adapting to humidity changes according to claim 2, characterized in that, The second absorption tower acid tank is further provided with a desalted water inlet pipeline, the fifth flow control device is arranged on the desalted water inlet pipeline, the second acid concentration detection device is further communicatively connected to the fifth flow control device, and the central control system is further communicatively connected to the fifth flow control device, so as to open the fifth flow control device to input desalted water into the second absorption tower acid tank to keep the acid concentration of the second absorption system stable when the amount of sour acid from the drying tower acid tank decreases.

4. The sulfuric acid dry absorption plant for adapting to humidity changes according to claim 3, characterized in that, The second absorption tower acid tank is further provided with a desalted water inlet pipeline, the fifth flow control device is arranged on the desalted water inlet pipeline, the second acid concentration detection device is further communicatively connected to the fifth flow control device, and the central control system is further communicatively connected to the fifth flow control device, so as to open the fifth flow control device to input desalted water into the second absorption tower acid tank to keep the acid concentration of the second absorption system stable when the amount of sour acid from the drying tower acid tank decreases.

5. The sulfuric acid dry absorption plant for adapting to humidity changes according to claim 4, characterized in that, The circulating pipeline of the drying system further comprises a drying tower acid pump and a drying acid cooler, and the acid concentration in the upper tower acid pipeline of the drying system and the acid concentration to the mixing diluter are 95%.

6. The sulfuric acid dry absorption plant for adapting to humidity changes according to claim 5, characterized in that, The first flow indication controller arranged on the pipeline from the drying acid cooler to the drying tower is further communicatively connected to the central control system, so as to control the flow of sulfuric acid from the drying acid cooler to the drying tower.

7. The sulfuric acid dry absorption plant for adapting to humidity changes according to claim 6, characterized in that, The second absorption system further comprises a second absorption tower acid pump and a second absorption tower, the pipeline from the second absorption acid cooler to the second absorption tower further has a first bypass to the product acid cooler, and the product acid underground tank is further connected to a product acid tank area by a product acid delivery pump to output the product acid.

8. The sulfuric acid dry absorption plant for adapting to humidity changes according to claim 7, characterized in that, The pipeline from the second absorption acid cooler to the second absorption tower further has a second bypass to the low-temperature heat recovery system to deliver the secondary spray acid.

9. The sulfuric acid dry absorption plant for adapting to humidity changes according to claim 8, characterized in that, The pipeline from the second absorption acid cooler to the second absorption tower is further provided with a second flow indication controller, and the second flow indication controller is further communicatively connected to the central control system, so as to control the flow of sulfuric acid from the second absorption acid cooler to the second absorption tower.

10. The sulfuric acid dry absorption plant for adapting to humidity changes according to claim 9, characterized in that, The circulating pipeline of the low-temperature heat recovery system comprises the mixing diluter, the low-temperature heat recovery tower, the low-temperature heat recovery boiler, the heater and the preheater connected in sequence, and the other end of the preheater is connected to the drying system and the second absorption system. The third flow indication controller arranged on the second bypass is further communicatively connected to the central control system, so as to control the flow of secondary spray acid from the second absorption acid cooler to the low-temperature heat recovery system.

Images