A flue gas desulfurization system for power plants with stable sulfur emissions

Abstract

This utility model belongs to the field of flue gas desulfurization technology, specifically relating to a power plant flue gas desulfurization system with stable sulfur emissions. It includes a primary absorption tower, a secondary absorption tower, and a first slurry tank. The flue gas outlet of the primary absorption tower is connected to the flue gas inlet of the secondary absorption tower, and the bottom outlet of the secondary absorption tower is connected to the spray layer of the primary absorption tower. The bottom outlet of the primary absorption tower is connected to the first slurry tank, and a first circulation pump and a first slurry replenishment pump are arranged in parallel at the outlet of the first slurry tank, with their outlets respectively connected to the spray layer of the primary absorption tower. The first circulation pump and the first slurry replenishment pump can be used independently or simultaneously. This allows for flexible adjustment of the amount of desulfurizing agent injected into the absorption tower when the SO2 content in the flue gas varies, thus stabilizing the sulfur content in the tail gas. This avoids the waste of power and high energy consumption caused by continuously using a large flow rate device to spray desulfurizing agent into the absorption tower.

Description

Technical Field

[0001] This utility model belongs to the field of flue gas desulfurization technology, specifically relating to a power plant flue gas desulfurization system with stable sulfur emissions. Background Technology

[0002] Flue gas desulfurization (FGD) refers to the removal of sulfur oxides from flue gas or other industrial waste gases. The most common FGD methods are wet FGD and dry FGD. Wet FGD removes sulfur dioxide by spraying a desulfurizing agent into the flue gas, causing a chemical reaction between the sulfur dioxide and the desulfurizing agent (limestone or carbide slag) to form calcium sulfate. The limestone-gypsum FGD process is roughly as follows: Flue gas containing SO2 enters the absorption tower under the action of an induced draft fan. The absorption tower uses a counter-current spray structure to evenly spray limestone slurry into the tower. SO2 reacts with the limestone slurry to convert into calcium sulfite (Ca(HSO3)2). The calcium sulfite and limestone slurry form a solution that accumulates at the bottom of the absorption tower. Air is introduced into the solution, and the calcium sulfite reacts with the air to produce calcium sulfate (CaSO4). When the calcium sulfate reaches a certain saturation, it crystallizes to form gypsum dihydrate. The gypsum dihydrate slurry is finally discharged from the absorption tower for recycling and dehydration treatment. The calcium carbide slag-gypsum desulfurization method utilizes calcium carbide slag slurry, whose main component is Ca(OH)2, to spray into the absorption tower and mix with the flue gas. The SO2 in the flue gas reacts chemically with the Ca(OH)2 in the slurry and the injected oxidizing air to remove SO2. The final reaction product is gypsum, thereby achieving the purpose of purifying the flue gas.

[0003] However, in actual production, the SO2 content in the flue gas fed into the absorption tower will fluctuate. When the SO2 content in the flue gas is too high, the SO2 in the flue gas cannot be completely absorbed, resulting in excessive sulfur in the tail gas. When the SO2 content in the flue gas is too low, spraying desulfurizing agent into the absorption tower with a large flow rate will result in a waste of some power and high energy consumption. Summary of the Invention

[0004] Based on this, this application provides a power plant flue gas desulfurization system with stable sulfur emissions to solve the technical problems in the prior art where the SO2 content in the flue gas entering the absorption tower flues, resulting in excessive sulfur in the tail gas, or where desulfurizing agents are still sprayed into the absorption tower with a large flow rate, which causes some power waste and high energy consumption.

[0005] The technical solution to the above-mentioned technical problems in this application is as follows:

[0006] A flue gas desulfurization system for power plants with stable sulfur emissions includes: a primary absorption tower, a secondary absorption tower, and a first slurry tank. The flue gas outlet of the primary absorption tower is connected to the flue gas inlet of the secondary absorption tower, and the bottom outlet of the secondary absorption tower is connected to the spray layer of the primary absorption tower. The bottom outlet of the primary absorption tower is connected to the first slurry tank, and a first circulation pump and a first slurry replenishment pump are arranged side by side at the outlet of the first slurry tank. The outlets of the first circulation pump and the first slurry replenishment pump are respectively connected to the spray layer of the primary absorption tower.

[0007] Preferably, in the above-mentioned power plant flue gas desulfurization system with stable sulfur emissions, a first sensor is installed at the flue gas inlet of the primary absorption tower. The first sensor is used to detect the sulfur dioxide content and is electrically connected to the first circulating pump and the first slurry replenishment pump.

[0008] Preferably, in the above-mentioned power plant flue gas desulfurization system with stable sulfur emissions, the bottom outlet of the secondary absorption tower is connected to a second slurry tank, the outlet of the second slurry tank is equipped with a second circulation pump, and the outlet of the second circulation pump is connected to the spray layer of the secondary absorption tower.

[0009] Preferably, in the above-mentioned power plant flue gas desulfurization system with stable sulfur emissions, the outlet of the second slurry tank is also connected to a second slurry replenishment pump, and the outlet of the second slurry replenishment pump is connected to the spray layer of the secondary absorption tower.

[0010] Preferably, in the above-mentioned flue gas desulfurization system for power plants with stable sulfur emissions, the outlet of the second circulating pump is also provided with a slurry conveying pipe, the other end of which is connected to the spray layer of the primary absorption tower, and a check valve is provided on the slurry conveying pipe.

[0011] Preferably, in the above-mentioned power plant flue gas desulfurization system with stable sulfur emissions, a second sensor is installed at the flue gas inlet of the secondary absorption tower. The second sensor is used to detect the sulfur dioxide content and is electrically connected to the second circulating pump and the second slurry replenishment pump.

[0012] Preferably, the above-mentioned power plant flue gas desulfurization system with stable sulfur emissions further includes a first oxidation blower and a first air inlet pipe, one end of which is connected to the outlet of the first oxidation blower and the other end is connected to the bottom of the primary absorption tower.

[0013] Preferably, the above-mentioned power plant flue gas desulfurization system with stable sulfur emissions further includes a second oxidation blower and a second air inlet pipe, one end of which is connected to the outlet of the second oxidation blower and the other end of which is connected to the bottom of the secondary absorption tower.

[0014] Preferably, in the above-mentioned flue gas desulfurization system for power plants with stable sulfur emissions, the outlet of the first circulating pump is also connected to a slurry collection pipe, and the other end of the slurry collection pipe is connected to a post-processing device.

[0015] Compared with the prior art, this application has at least the following advantages:

[0016] The sulfur emission stabilization power plant flue gas desulfurization system provided in this application includes: a primary absorption tower, a secondary absorption tower, and a first slurry tank. The flue gas outlet of the primary absorption tower is connected to the flue gas inlet of the secondary absorption tower, and the bottom outlet of the secondary absorption tower is connected to the spray layer of the primary absorption tower. The bottom outlet of the primary absorption tower is connected to the first slurry tank, and a first circulation pump and a first slurry replenishment pump are arranged in parallel at the outlet of the first slurry tank. The outlets of the first circulation pump and the first slurry replenishment pump are respectively connected to the spray layer of the primary absorption tower. The first circulation pump and the first slurry replenishment pump can be used independently or simultaneously. This allows for flexible adjustment of the amount of slurry (desulfurizing agent) injected into the absorption tower when the SO2 content in the flue gas varies, thereby stabilizing the sulfur content in the tail gas. Furthermore, the rational use of different flow rates of the first circulation pump or the first slurry replenishment pump avoids the waste of power and high energy consumption caused by continuously using a large flow rate device to spray desulfurizing agent into the absorption tower. Attached Figure Description

[0017] Figure 1 This is a system diagram of the flue gas desulfurization system for power plants with stable sulfur emissions, as per this application.

[0018] In the diagram: primary absorption tower 100, secondary absorption tower 200, first slurry tank 110, first circulation pump 120, first slurry replenishment pump 130, first sensor 140, first oxidation blower 150, first air inlet pipe 160, concentrated slurry outlet pipe 170, second slurry tank 210, second circulation pump 220, second slurry replenishment pump 230, second sensor 240, second oxidation blower 250, second air inlet pipe 260, slurry conveying pipe 300, check valve 310, and post-treatment device 400. Detailed Implementation

[0019] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0020] It should be noted that when an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," "top," "bottom," "end," "top," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this specification is for descriptive purposes only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] Please refer to Figure 1 In one specific embodiment of this application, a power plant flue gas desulfurization system with stable sulfur emissions includes: a primary absorption tower 100, a secondary absorption tower 200, and a first slurry tank 110. The flue gas outlet of the primary absorption tower 100 is connected to the flue gas inlet of the secondary absorption tower 200, and the bottom outlet of the secondary absorption tower 200 is connected to the spray layer of the primary absorption tower 100. The bottom outlet of the primary absorption tower 100 is connected to the first slurry tank 110, and a first circulation pump 120 and a first slurry replenishment pump 130 are arranged side by side at the outlet of the first slurry tank 110. The outlets of the first circulation pump 120 and the first slurry replenishment pump 130 are respectively connected to the spray layer of the primary absorption tower 100.

[0023] The absorption tower adopts a counter-current spray tower. The spray layer of the absorption tower is located between the flue gas inlet and the flue gas outlet of the absorption tower. The flue gas outlet of the primary absorption tower 100 is connected to the flue gas inlet of the secondary absorption tower 200. The raw flue gas enters the primary absorption tower 100 through the side inlet. Inside the primary absorption tower 100, the flue gas comes into counter-current contact with the mist-like desulfurizing agent slurry. Here, the flue gas is cooled and saturated, and the SO2 in the flue gas is absorbed for the first time. The treated flue gas is discharged from the flue gas outlet at the top of the primary absorption tower 100, and then re-enters the secondary absorption tower 200. The SO2 in the flue gas is absorbed again. After the liquid droplets in the flue gas are removed by the dust removal and demister device, it is discharged to the chimney. After being lifted to a certain height by the chimney, it is discharged into the atmosphere.

[0024] The first slurry tank 110 in this application is used to hold desulfurizing agent slurry, which can be calcium carbide slag slurry, limestone slurry, or a mixture of the two. The desulfurizing agent in the first slurry tank 110 is transported to the spray layer of the primary absorption tower 100, where it is sprayed out and reacts with SO2 in the flue gas. If the absorbent is calcium carbide slag slurry, it absorbs SO2 in the flue gas upon contact with it, and simultaneously reacts with CO2 in the flue gas to generate CaCO3. CaCO3, as a supplement to the absorbent, continues to react with the flue gas, absorbing SO2 to generate gypsum CaSO4, which precipitates at the bottom of the absorption tower and is eventually discharged. If the absorbent is limestone slurry, it can also react with SO2 to generate gypsum, which precipitates at the bottom of the absorption tower and is eventually discharged. During this process, any desulfurizing agent that has not fully reacted can be continuously transported to the spray layer of the primary absorption tower 100 via the first circulating pump 120 to continue absorbing SO2 in the flue gas. The first slurry replenishment pump 130 is also located at the outlet of the first slurry tank 110, and its outlet is connected to the spray layer of the primary absorption tower 100. That is, the first circulation pump 120 and the first slurry replenishment pump 130 are connected in parallel. In the operating conditions of this application, the first circulation pump 120 is typically set to have a larger flow rate and power, while the first slurry replenishment pump 130 has a smaller flow rate and power. When the SO2 content in the flue gas changes, either the first circulation pump 120 or the first slurry replenishment pump 130 can be activated individually, or both can be used simultaneously if necessary. This allows for flexible adjustment of the amount of desulfurizing agent injected into the absorption tower when the SO2 content in the flue gas varies, thus stabilizing the sulfur content in the tail gas. Moreover, when the SO2 content is low, only the first slurry replenishment pump 130 can be activated; if the SO2 content increases, the first circulation pump 120 can be activated; and when the SO2 content is even higher, both the first circulation pump 120 and the first slurry replenishment pump 130 can be activated simultaneously. By using the first circulation pump 120 and / or the first slurry replenishment pump 130 with different flow rates (different power) according to different SO2 contents, the problem of wasted power and high energy consumption caused by continuously using equipment with a large flow rate to spray desulfurizing agent into the absorption tower can be avoided.

[0025] To obtain real-time SO2 content data in the flue gas and adjust the start / stop of the first circulation pump 120 and the first slurry replenishment pump 130 accordingly, a first sensor 140 is further installed at the flue gas inlet of the primary absorption tower 100. The first sensor 140 is used to detect sulfur dioxide content and is electrically connected to the first circulation pump 120 and the first slurry replenishment pump 130. Based on the SO2 content detected by the first sensor 140, either the first circulation pump 120 or the first slurry replenishment pump 130 can be activated individually, or both can be activated simultaneously if necessary.

[0026] In another specific embodiment of this application, the bottom outlet of the secondary absorption tower 200 is connected to a second slurry tank 210, and the outlet of the second slurry tank 210 is provided with a second circulation pump 220, the outlet of the second circulation pump 220 being connected to the spray layer of the secondary absorption tower 200.

[0027] The SO2 in the flue gas absorbed by the primary absorption tower 100 enters the secondary absorption tower 200 for further absorption. The working principle of the secondary absorption tower 200 in absorbing SO2 is the same as that of the primary absorption tower 100. The second slurry tank 210 is used not only to hold the desulfurizing agent, but also to inject new desulfurizing agent into it. The new agent is then transported to the secondary absorption tower 200 for reaction via the second circulation pump 220, while simultaneously replenishing the desulfurizing agent that has been reacted.

[0028] The flue gas absorbed by the secondary absorption tower 200 is lifted to a certain height by the chimney and then discharged into the atmosphere. In order to ensure that the sulfur content in the exhaust gas discharged into the atmosphere meets the standard and is stable, as a preferred option, the outlet of the second slurry tank 210 is also connected to a second slurry replenishment pump 230, and the outlet of the second slurry replenishment pump 230 is connected to the spray layer of the secondary absorption tower 200.

[0029] The second slurry replenishment pump 230 is also located at the outlet of the second slurry tank 210, and its outlet is connected to the spray layer of the secondary absorption tower 200. This means the second circulation pump 220 and the second slurry replenishment pump 230 are connected in parallel. In actual operation, the second circulation pump 220 is typically configured with a larger flow rate and power, while the second slurry replenishment pump 230 has a smaller flow rate and power. When the SO2 content in the flue gas entering the secondary absorption tower 200 changes, either the second circulation pump 220 or the second slurry replenishment pump 230 can be activated individually, depending on the SO2 content. If necessary, both can be used simultaneously. This allows for flexible adjustment of the amount of desulfurizing agent injected into the absorption tower when the SO2 content in the flue gas varies, thus stabilizing the sulfur content in the tail gas.

[0030] Similarly, in order to obtain real-time data on the SO2 content in the flue gas input to the secondary absorption tower 200, and thus adjust the start / stop of the second circulation pump 220 and the second slurry replenishment pump 230 as needed, a second sensor 240 is installed at the flue gas inlet of the secondary absorption tower 200. The second sensor 240 is used to detect the sulfur dioxide content and is electrically connected to the second circulation pump 220 and the second slurry replenishment pump 230. Based on the SO2 content detected by the second sensor 240, either the second circulation pump 220 or the second slurry replenishment pump 230 can be activated individually, or both can be activated simultaneously if necessary.

[0031] Since the flue gas entering the secondary absorption tower 200 has already been absorbed once by the primary absorption tower 100, the SO2 content in it is much lower than that in the original flue gas entering the primary absorption tower 100. Therefore, the amount of desulfurizing agent required for the secondary absorption tower 200 is lower than that for the primary absorption tower 100. At the same time, there is a lot of unreacted desulfurizing agent in the second slurry tank 210. In order to further recycle this part of the desulfurizing agent, and since fresh desulfurizing agent is added to the second slurry tank 210, it is preferable that the outlet of the second circulation pump 220 is also provided with a slurry conveying pipe 300. The other end of the slurry conveying pipe 300 is connected to the spray layer of the primary absorption tower 100, and a check valve 310 is provided on the slurry conveying pipe 300. The second circulating pump 220 transports the unreacted desulfurizing agent and fresh desulfurizing agent in the second slurry tank 210 to the first-stage absorption tower 100, where they participate in the flue gas absorption of the first-stage absorption tower 100, so that the desulfurizing agent is fully utilized and waste is avoided. The check valve can prevent the desulfurizing agent from flowing back in the slurry conveying pipe 300.

[0032] In another specific embodiment of this application, the power plant flue gas desulfurization system further includes a first oxidation blower 150 and a first air inlet pipe 160. One end of the first air inlet pipe 160 is connected to the outlet of the first oxidation blower 150, and the other end is connected to the bottom of the primary absorption tower 100.

[0033] Because the desulfurization of flue gas in the absorption tower requires a large amount of oxidizing air to fully and rapidly oxidize the calcium sulfite in the slurry pool of the absorption tower, a first oxidation blower 150 is connected to the bottom of the primary absorption tower 100 through a first air inlet pipe 160. The first oxidation blower 150 blows oxidizing air into the slurry pool of the primary absorption tower 100 to react with the slurry. The oxidizing air is injected into the pressure side of the agitator blades of the primary absorption tower 100, where it is dispersed into fine bubbles by the pressure and shear force generated by the agitator and evenly distributed in the slurry. A portion of the sulfite ions are oxidized by oxygen in the flue gas in the spray zone of the absorption tower, while the remaining sulfite ions are completely oxidized by the oxidizing air in the reaction pool.

[0034] Similarly, the flue gas desulfurization system of this power plant also includes a second oxidation blower 250 and a second inlet pipe 260. One end of the second inlet pipe 260 is connected to the outlet of the second oxidation blower 250, and the other end is connected to the bottom of the secondary absorption tower 200. The working principle and function of the second oxidation blower 250 are the same as those of the first oxidation blower 150, and will not be described again here.

[0035] In a preferred embodiment, the sulfur emission-stabilized flue gas desulfurization system of the power plant described above includes a slurry collection pipe 170 connected to the outlet of the first circulating pump 120. The other end of the slurry collection pipe 170 is connected to a post-treatment device 400, which processes the slurry collected from the slurry collection pipe 170. The slurry is typically filtered and dehydrated in the post-treatment device 400, after which the gypsum is discharged, and the filtrate is transported to the first slurry tank 110 and / or the second slurry tank 210 for pulping.

[0036] The specific work process is as follows:

[0037] Both the primary absorption tower 100 and the secondary absorption tower 200 employ counter-current spray towers, with their spray layers located between the flue gas inlet and outlet of the absorption towers. The flue gas outlet of the primary absorption tower 100 is connected to the flue gas inlet of the secondary absorption tower 200. Raw flue gas enters the primary absorption tower 100 through a side inlet. Inside the primary absorption tower 100, the flue gas comes into counter-current contact with the atomized desulfurizing agent slurry. Here, the flue gas is cooled and saturated, and the SO2 in the flue gas is absorbed for the first time. The desulfurizing agent in the first slurry tank 110 is transported to the spray layer of the primary absorption tower 100 by the first circulation pump 120 and / or the first slurry replenishment pump 130, where it is sprayed out and reacts with the SO2 in the flue gas. When the SO2 content in the flue gas changes, the first sensor 140 feeds back the detected SO2 content data to the control system. The control system can then activate either the first circulation pump 120 or the first slurry replenishment pump 130 individually, or both simultaneously if necessary. This allows for flexible adjustment of the amount of desulfurizing agent injected into the absorption tower when the SO2 content in the flue gas varies, thus stabilizing the sulfur content in the tail gas. Furthermore, the rational use of different flow rates of the first circulation pump 120 or the first slurry replenishment pump 130 avoids the waste of power and high energy consumption caused by continuously using equipment with a large flow rate to spray desulfurizing agent into the absorption tower. To fully and rapidly oxidize the calcium sulfite in the reaction tank, an oxidation air assembly is installed. Oxidation air is injected into the reaction tank of the primary absorption tower 100 by the first oxidation blower 150, and a portion of the HSO3... － In the spray zone of the absorption tower, the HSO3 is oxidized by oxygen in the flue gas, and the remaining HSO3... － The gypsum is completely oxidized by oxidizing air in the reaction tank. The concentrated slurry after reaction in the primary absorption tower 100 is transported to the post-treatment device 400 through the concentrated slurry collection pipe 170 at the outlet of the first circulation pump 120. After filtration and dehydration, the gypsum is discharged, and the filtrate is transported to the first slurry tank 110 and / or the second slurry tank 210 for pulping.

[0038] The treated flue gas is discharged from the flue gas outlet at the top of the primary absorption tower 100, and then re-enters the secondary absorption tower 200, where SO2 is absorbed again. After passing through a dust and mist removal device to remove liquid droplets, the flue gas is discharged through a chimney and, after being lifted to a certain height, is released into the atmosphere. The desulfurizing agent in the second slurry tank 210 is transported to the secondary absorption tower 200 for reaction via the second circulation pump 220 and / or the second slurry replenishment pump 230. When the SO2 content in the flue gas changes, the second sensor 240 feeds back the detected SO2 content data to the control system. The control system can activate either the second circulation pump 220 or the second slurry replenishment pump 230 individually, or both simultaneously if necessary. This allows for flexible adjustment of the amount of desulfurizing agent injected into the absorption tower when the SO2 content in the flue gas varies, thus stabilizing the sulfur content in the tail gas. To fully and rapidly oxidize the calcium sulfite in the reaction tank, an oxidation air assembly is installed. Oxidation air is injected into the reaction tank of the secondary absorption tower 200 by a second oxidation blower 250, and a portion of the HSO3... － In the spray zone of the absorption tower, the HSO3 is oxidized by oxygen in the flue gas, and the remaining HSO3... － The desulfurizer is completely oxidized by oxidizing air in the reaction tank. At the same time, the second circulation pump 220 transports the unreacted desulfurizer and fresh desulfurizer together in the second slurry tank 210 to the primary absorption tower 100 to participate in the flue gas absorption of the primary absorption tower 100, so that the desulfurizer is fully utilized and waste is avoided.

[0039] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A power plant flue gas desulfurization system with stable sulfur emission, characterized by, include: The system comprises a primary absorption tower, a secondary absorption tower, and a first slurry tank. The flue gas outlet of the primary absorption tower is connected to the flue gas inlet of the secondary absorption tower, and the bottom outlet of the secondary absorption tower is connected to the spray layer of the primary absorption tower. The bottom outlet of the primary absorption tower is connected to the first slurry tank, and the outlet of the first slurry tank is provided with a first circulation pump and a first slurry replenishment pump arranged in parallel. The outlets of the first circulation pump and the first slurry replenishment pump are respectively connected to the spray layer of the primary absorption tower.

2. The power plant flue gas desulfurization system with stable sulfur emissions as described in claim 1, characterized in that, The flue gas inlet of the primary absorption tower is equipped with a first sensor, which is used to detect the sulfur dioxide content. The first sensor is electrically connected to the first circulating pump and the first slurry replenishment pump.

3. The sulfur emissions stable power plant flue gas desulfurization system of claim 1, wherein, The bottom outlet of the secondary absorption tower is connected to a second slurry tank, and the outlet of the second slurry tank is equipped with a second circulation pump. The outlet of the second circulation pump is connected to the spray layer of the secondary absorption tower.

4. The sulfur emissions stable power plant flue gas desulfurization system of claim 3, wherein, The outlet of the second slurry tank is also connected to a second slurry replenishment pump, and the outlet of the second slurry replenishment pump is connected to the spray layer of the secondary absorption tower.

5. The sulfur emission stable power plant flue gas desulfurization system as claimed in claim 3, wherein, The outlet of the second circulating pump is also provided with a slurry conveying pipe, the other end of which is connected to the spray layer of the primary absorption tower, and a check valve is provided on the slurry conveying pipe.

6. The power plant flue gas desulfurization system with stable sulfur emissions as described in claim 3, characterized in that, The flue gas inlet of the secondary absorption tower is equipped with a second sensor, which is used to detect the sulfur dioxide content. The second sensor is electrically connected to the second circulation pump and the second slurry replenishment pump.

7. A sulfur emission stable power plant flue gas desulfurization system as set forth in claim 1, characterized by, It also includes a first oxidation blower and a first air inlet pipe, one end of which is connected to the outlet of the first oxidation blower and the other end is connected to the bottom of the first-stage absorption tower.

8. A sulfur emission stable power plant flue gas desulfurization system as set forth in claim 1, characterized by, It also includes a second oxidation blower and a second air inlet pipe. One end of the second air inlet pipe is connected to the outlet of the second oxidation blower, and the other end is connected to the bottom of the secondary absorption tower.

9. A sulfur emission stable power plant flue gas desulfurization system as set forth in claim 1, characterized by, The outlet of the first circulating pump is also connected to a slurry extraction pipe, and the other end of the slurry extraction pipe is connected to a post-processing device.

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