Flue gas treatment system

Abstract

This invention relates to the field of environmental protection technology and discloses a flue gas treatment system that solves the technical problem that after denitrification, dust removal, and desulfurization, coal-fired flue gas still retains a certain amount of nitrogen oxides, sulfur oxides, and particulate matter, resulting in unsatisfactory carbon dioxide capture efficiency. The system includes a desulfurization device, a water washing tower, a carbon dioxide capture device, a first conveying pipeline, and a second conveying pipeline. The desulfurization device has an outlet, the water washing tower has a first inlet and a first outlet, and the carbon dioxide capture device has an inlet. The outlet of the desulfurization device is connected to the first inlet of the water washing tower via the first conveying pipeline; the first outlet of the water washing tower is connected to the inlet of the carbon dioxide capture device via the second conveying pipeline. The water washing tower is used to wash the flue gas entering from the first inlet of the water washing tower using an alkaline washing solution, and the washed flue gas is output through the first outlet of the water washing tower.

Description

Technical Field

[0001] This invention relates to the field of environmental protection technology, and more specifically to a flue gas treatment system. Background Technology

[0002] Currently, the flue gas emitted from boilers is usually purified by sequentially using processes such as denitrification, dust removal, desulfurization, and carbon dioxide capture.

[0003] However, in practical applications, even after denitrification, dust removal, and desulfurization, a certain amount of nitrogen oxides (NOx) still remain in the flue gas from coal combustion. x ), sulfur oxides (SO x Nitrogen oxides, sulfur oxides, and soot remaining in the flue gas after coal combustion enter the carbon dioxide capture device will affect the absorption effect of the carbon dioxide absorbent on the carbon dioxide in the flue gas, resulting in an unsatisfactory carbon dioxide capture effect. Summary of the Invention

[0004] This application provides a flue gas treatment system that can solve the technical problem that after denitrification, dust removal and desulfurization of coal-fired flue gas, a certain amount of nitrogen oxides, sulfur oxides and soot still remain, resulting in unsatisfactory carbon dioxide capture effect.

[0005] This application provides a flue gas treatment system, which includes: a desulfurization device, a water scrubbing tower, a carbon dioxide capture device, a first conveying pipeline, and a second conveying pipeline.

[0006] The desulfurization device has an outlet, the water washing tower has a first inlet and a first outlet, and the carbon dioxide capture device has an inlet;

[0007] The outlet of the desulfurization unit is connected to the first inlet of the water washing tower through the first conveying pipeline; the first outlet of the water washing tower is connected to the inlet of the carbon dioxide capture unit through the second conveying pipeline.

[0008] The water washing tower is used to wash the flue gas entering from the first inlet of the water washing tower with alkaline water washing liquid, and the washed flue gas is output through the first outlet of the water washing tower.

[0009] Optionally, in one embodiment, the water washing tower further includes a second inlet and a liquid distributor, the liquid distributor being disposed inside the water washing tower and having an inlet that communicates with the second inlet of the water washing tower;

[0010] The alkaline washing liquid enters the liquid distributor through the second inlet of the washing tower and is sprayed down through the liquid distributor;

[0011] In the water washing tower, the flue gas entering from the first inlet of the water washing tower comes into countercurrent contact with the alkaline water washing liquid sprayed down.

[0012] Optionally, in one embodiment, the processing system further includes an alkali tank, a third delivery pipeline and a fourth delivery pipeline, the water washing tower also has a second outlet, and the alkali tank has an outlet;

[0013] The second outlet of the water washing tower is connected to the second inlet of the water washing tower through the third conveying pipeline, and the second outlet of the water washing tower is located at the bottom of the water washing tower;

[0014] The outlet of the alkali tank is connected to the first position of the third conveying pipeline through the fourth conveying pipeline.

[0015] Optionally, in one embodiment, the processing system further includes a first pumping device and a second pumping device; the first pumping device is disposed at a second position in the third conveying pipeline, the second position being downstream of the first position; the second pumping device is disposed at a third position in the fourth conveying pipeline.

[0016] Optionally, in one embodiment, the processing system further includes a cooling device disposed at a fourth position in the third delivery pipeline, the fourth position being downstream of the second position.

[0017] Optionally, in one embodiment, the water washing tower further includes a gas-liquid separation device disposed at the top of the water washing tower;

[0018] In the water washing tower, the washed flue gas passes through the gas-liquid separation device and is then output from the first outlet of the water washing tower.

[0019] Optionally, in one embodiment, the water washing tower further has a third outlet, and the treatment system further includes a carbon dioxide absorbent preparation device and a fifth delivery pipeline, the carbon dioxide absorbent preparation device having an inlet and an outlet, and the third outlet of the water washing tower being located at the bottom of the water washing tower;

[0020] The third outlet of the water washing tower is connected to the inlet of the carbon dioxide absorbent preparation device through the fifth conveying pipeline.

[0021] Optionally, in one embodiment, the processing system further includes an alkaline washing liquid storage tank and a fifth delivery pipeline, the alkaline washing liquid storage tank having an inlet;

[0022] The inlet of the alkaline washing liquid storage tank is connected to the fifth position of the fourth conveying pipeline through the fifth conveying pipeline.

[0023] Optionally, in one embodiment, the processing system further includes a flow detection device, a sulfur oxide concentration detection device, a nitrogen oxide concentration detection device, a dust concentration detection device, and a humidity detection device;

[0024] Among them, at least one of the flow detection devices, at least one of the sulfur oxide concentration detection devices, at least one of the nitrogen oxide concentration detection devices, at least one of the dust concentration detection devices, and at least one of the humidity detection devices are disposed in the first conveying pipeline;

[0025] At least one of the flow detection devices, at least one of the sulfur oxide concentration detection devices, at least one of the nitrogen oxide concentration detection devices, at least one of the dust concentration detection devices, and at least one of the humidity detection devices are disposed in the second conveying pipeline.

[0026] Optionally, in one embodiment, the processing system further includes a denitrification device, a first dust removal device, and a second dust removal device, wherein the first conveying pipeline includes a first sub-pipeline and a second sub-pipeline, and the second dust removal device has an inlet and an outlet;

[0027] The denitrification device, the first dust removal device, the desulfurization device, and the second dust removal device are connected in sequence;

[0028] The outlet of the desulfurization device is connected to the inlet of the second dust removal device through the first sub-pipeline, and the outlet of the second dust removal device is connected to the first inlet of the water washing tower through the second sub-pipeline.

[0029] The beneficial effects of the embodiments in this application are as follows:

[0030] The flue gas treatment system provided in this application includes: a desulfurization device, a water scrubbing tower, a carbon dioxide capture device, a first conveying pipeline, and a second conveying pipeline. The desulfurization device has an outlet, the water scrubbing tower has a first inlet and a first outlet, and the carbon dioxide capture device has an inlet. The outlet of the desulfurization device is connected to the first inlet of the water scrubbing tower via the first conveying pipeline. The first outlet of the water scrubbing tower is connected to the inlet of the carbon dioxide capture device via the second conveying pipeline. The water scrubbing tower is used to scrub the flue gas entering from the first inlet of the water scrubbing tower using an alkaline scrubbing solution. The scrubbed flue gas is then fed into the second conveying pipeline via the first outlet of the water scrubbing tower. Thus, before the flue gas enters the carbon dioxide capture device, the alkaline scrubbing solution in the water scrubbing tower can further absorb nitrogen oxides and sulfur oxides in the flue gas, and further scrub the particulate matter in the flue gas. This reduces the content of nitrogen oxides, sulfur oxides, and particulate matter in the flue gas entering the carbon dioxide capture device, thereby improving the absorption effect of the carbon dioxide absorbent on the carbon dioxide in the flue gas and optimizing the carbon dioxide capture effect.

[0031] Other features and advantages of the embodiments of this application will be described in detail in the following detailed description section. Attached Figure Description

[0032] The accompanying drawings are provided to further illustrate the embodiments of this application and form part of the specification. They are used together with the following detailed description to explain the embodiments of this application, but do not constitute a limitation on the embodiments of this application. In the drawings:

[0033] Figure 1 The schematic diagram illustrates a structural schematic of a flue gas treatment system according to an embodiment of this application;

[0034] Figure 2 The schematic diagram illustrates the structure of another flue gas treatment system according to an embodiment of this application.

[0035] Explanation of reference numerals in the attached figures

[0036] 100—Flue gas treatment system; 101—Desulfurization device; 102—Water washing tower; 1021—Liquid distributor; 1022—Gas-liquid separation device; 103—Carbon dioxide capture device; 104—First conveying pipeline; 105—Second conveying pipeline; 106—Booster fan; 107—Alkali solution tank; 108—Third conveying pipeline; 109—Fourth conveying pipeline; 110—First pumping device; 111—Second pumping device; 112—Cooling device; 113—Carbon dioxide absorbent preparation device; 114—Fifth conveying pipeline; 115—Alkaline water washing liquid storage tank; 116—Sixth conveying pipeline. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for illustration and explanation of the embodiments of this application and are not intended to limit the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0038] It should be noted that if the embodiments of this application involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0039] Furthermore, if the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0040] As described in the background section of this application, after denitrification, dust removal, and desulfurization, the flue gas discharged from the boiler still retains a certain amount of nitrogen oxides, sulfur oxides, and particulate matter. Although the content of the remaining nitrogen oxides, sulfur oxides, and particulate matter is low and basically meets the emission standards, the inventors have discovered that after the flue gas enters the carbon dioxide capture device, the remaining nitrogen oxides and sulfur oxides in the flue gas react with the carbon dioxide absorbent (such as an organic amine solution), leading to the consumption of the carbon dioxide absorbent. For example, nitrogen oxides and sulfur oxides react with the organic amine solution to form thermally stable salts. In the carbon dioxide capture process, the carbon dioxide absorbent is recycled. Specifically, after the carbon dioxide absorbent absorbs nitrogen oxides, sulfur oxides, and carbon dioxide, it undergoes desorption outside the carbon dioxide capture device. After the carbon dioxide is desorbed, it returns to the carbon dioxide capture device for reuse. During this desorption process, nitrogen oxides and sulfur oxides are not desorbed. Furthermore, as the carbon dioxide absorbent circulates, more and more of it is consumed by nitrogen oxides and sulfur oxides, leaving less and less absorbent available for carbon dioxide absorption. This affects the absorbent's effectiveness in absorbing carbon dioxide from the flue gas. Simultaneously, the accumulation of particulate matter within the absorbent also hinders its absorption. Therefore, even after denitrification, dust removal, and desulfurization, residual nitrogen oxides, sulfur oxides, and particulate matter in the coal-fired flue gas can lead to suboptimal carbon dioxide capture.

[0041] To address this, this application provides a flue gas treatment system 100, which can be used to treat coal-fired flue gas discharged from a boiler. For example... Figure 1 As shown, the flue gas treatment system 100 may include a desulfurization device 101, a water scrubbing tower 102, a carbon dioxide capture device 103, a first conveying pipeline 104, and a second conveying pipeline 105. The desulfurization device 101 has an outlet, the water scrubbing tower 102 has a first inlet and a first outlet, and the carbon dioxide capture device 103 has an inlet. The outlet of the desulfurization device 101 is connected to the first inlet of the water scrubbing tower 102 through the first conveying pipeline 104. The first outlet of the water scrubbing tower 102 is connected to the inlet of the carbon dioxide capture device 103 through the second conveying pipeline 105. The water scrubbing tower 102 is used to scrub the flue gas entering from the first inlet of the water scrubbing tower 102 with alkaline scrubbing liquid, and the scrubbed flue gas is output through the first outlet of the water scrubbing tower 103.

[0042] In the embodiments of this application, the flue gas may be coal-fired flue gas, which may contain nitrogen oxides, sulfur oxides, soot, carbon dioxide, and water vapor, etc.

[0043] The desulfurization device 101 can be used to remove sulfur oxides from the flue gas. The desulfurization device 101 can be a device corresponding to wet flue gas desulfurization technology, dry flue gas desulfurization technology, or semi-dry flue gas desulfurization technology.

[0044] In practical applications, the flue gas treatment system 100 may further include a denitrification device and a first dust removal device (not shown in the figure). The desulfurization device 101 is located after the first dust removal device, and the flue gas flows sequentially through the denitrification device, the first dust removal device, and the desulfurization device 101. The denitrification device can be used to remove nitrogen oxides from the flue gas. The denitrification device may include, but is not limited to, a selective catalytic reduction (SCR) reactor, a selective non-catalytic reduction (SNCR) reactor, etc. The first dust removal device can be used to remove particulate matter from the flue gas. The first dust removal device may include, but is not limited to, a cyclone separator, a bag filter, etc. Therefore, the content of nitrogen oxides, sulfur oxides, and particulate matter in the flue gas output from the outlet of the desulfurization device 101 is greatly reduced, basically meeting the respective emission standards for nitrogen oxides, sulfur oxides, and particulate matter.

[0045] The carbon dioxide capture device 103 can be used to remove carbon dioxide from flue gas. Specifically, the carbon dioxide capture device 103 can be an absorption tower that uses a carbon dioxide absorbent to absorb carbon dioxide from the flue gas. The carbon dioxide absorbent can be, for example, an organic amine solution.

[0046] Flue gas exiting from desulfurization unit 101 enters water washing tower 102, where it is washed with an alkaline washing solution. Since nitrogen oxides and sulfur oxides are acidic substances, the alkaline washing solution can further absorb residual nitrogen oxides and sulfur oxides in the flue gas. Simultaneously, washing the flue gas can further remove residual soot. The alkaline washing solution may include, but is not limited to, sodium hydroxide solution, amine solution, etc.

[0047] The first inlet of the water washing tower 102 can be located near the bottom of the water washing tower 102, and the first outlet of the water washing tower 102 can be located at the top of the water washing tower 102. After the flue gas enters the water washing tower 102 through the first inlet, it flows upward inside the water washing tower 102 and is transported to the second conveying pipeline 105 through the second outlet.

[0048] In this embodiment of the application, a water washing tower 102 is added between the desulfurization device 101 and the carbon dioxide capture device 103, so that the residual nitrogen oxides, sulfur oxides and soot in the flue gas can be further removed before the flue gas enters the carbon dioxide capture device 103. As a result, after the flue gas enters the carbon dioxide capture device 103, the consumption of carbon dioxide absorbent can be reduced, and more carbon dioxide absorbent can be used to absorb carbon dioxide in the flue gas.

[0049] In practical applications, in order to ensure that the flue gas can smoothly enter the water scrubbing tower 102, in one embodiment, such as... Figure 2 As shown, the flue gas treatment system 100 also includes a booster fan 106, the inlet of which is connected to the outlet of the desulfurization device 101, and the outlet of which is connected to the inlet of the first conveying pipeline 104.

[0050] It is understood that the flue gas treatment system 100 provided in this application includes a desulfurization device 101, a water scrubbing tower 102, a carbon dioxide capture device 103, a first conveying pipeline 104, and a second conveying pipeline 105. The desulfurization device 101 has an outlet, the water scrubbing tower 102 has a first inlet and a first outlet, and the carbon dioxide capture device 103 has an inlet. The outlet of the desulfurization device 101 is connected to the first inlet of the water scrubbing tower 102 through the first conveying pipeline 104, and the first outlet of the water scrubbing tower 102 is connected to the inlet of the carbon dioxide capture device 103 through the second conveying pipeline 105. The water washing tower 102 is used to wash the flue gas entering from the first inlet of the water washing tower 102 with alkaline water washing liquid. The washed flue gas is then output through the first outlet of the water washing tower 103. Thus, before the flue gas enters the carbon dioxide capture device 103, the alkaline water washing liquid in the water washing tower 102 can be used to further absorb nitrogen oxides and sulfur oxides in the flue gas, and further wash the dust in the flue gas. This can reduce the content of nitrogen oxides, sulfur oxides, and dust in the flue gas entering the carbon dioxide capture device 103, thereby improving the absorption effect of carbon dioxide absorbent on carbon dioxide in the flue gas and optimizing the carbon dioxide capture effect.

[0051] On the other hand, in the prior art, as the carbon dioxide absorbent is recycled, more and more of it is occupied due to the absorption of nitrogen oxides and sulfur oxides, resulting in fewer and fewer absorbents available for carbon dioxide absorption. Consequently, the carbon dioxide absorption capacity of the recycled absorbent is greatly reduced, leading to the need for frequent replacement and higher carbon dioxide capture costs. However, the solution provided in the above embodiments of this application washes the flue gas with alkaline washing liquid in the water washing tower 102 before it enters the carbon dioxide capture device 103, reducing the content of nitrogen oxides, sulfur oxides, and particulate matter in the flue gas entering the carbon dioxide capture device 103. This reduces the consumption of carbon dioxide absorbent, extends its recycling time, and thus lowers the carbon dioxide capture cost.

[0052] To further reduce the content of nitrogen oxides, sulfur oxides, and particulate matter in the flue gas entering the carbon dioxide capture device 103, in one embodiment, such as Figure 2 As shown, the water washing tower 102 also has a second inlet and a liquid distributor 1021. The liquid distributor 1021 is disposed inside the water washing tower 102 and has an inlet that communicates with the second inlet of the water washing tower 102. The alkaline washing liquid enters the liquid distributor 1021 through the second inlet of the water washing tower 102 and is sprayed down through the liquid distributor 1021. In the water washing tower 102, the flue gas entering from the first inlet of the water washing tower 102 comes into countercurrent contact with the sprayed alkaline washing liquid.

[0053] The liquid distributor 1021 is used to evenly distribute the alkaline washing liquid, ensuring a uniform distribution of the alkaline washing liquid sprayed down from the washing tower 102. Specifically, the liquid distributor 1021 can be a spray-type distributor. The liquid distributor 1021 can be located above the first inlet and below the first outlet of the washing tower 102. After the flue gas comes into countercurrent contact with the alkaline washing liquid sprayed down from the liquid distributor 1021, it is then discharged from the first outlet of the washing tower 102.

[0054] As the alkaline washing liquid is sprayed down, it forms a pooled liquid at the bottom of the washing tower 102, also known as the bottom liquid. In this embodiment, the first inlet of the washing tower 102 can be located below the surface of the bottom liquid. Therefore, the flue gas entering the washing tower 102 can first contact the bottom liquid, then escape from it, and then countercurrently contact the sprayed alkaline washing liquid. This increases the contact time between the flue gas and the alkaline washing liquid, resulting in better removal of nitrogen oxides, sulfur oxides, and particulate matter from the flue gas.

[0055] Considering the power limitation of the booster fan 106, the first inlet of the water washing tower 102 can be located above the liquid surface in the bottom of the tower. Then, the flue gas entering the water washing tower 102 can flow directly upwards, contacting the alkaline washing liquid sprayed downwards in a counter-current manner. This reduces the resistance of the flue gas entering the water washing tower 102, thereby reducing the power of the booster fan 106 and lowering electricity costs.

[0056] In practical applications, the first inlet of the water washing tower 102 can be set below or above the liquid level in the bottom of the tower, depending on the actual production needs.

[0057] It is understandable that by adopting the above scheme, by setting a liquid distributor 1021 in the water washing tower 102, the alkaline water washing liquid is evenly distributed and sprayed downwards. The flue gas and the alkaline water washing liquid come into countercurrent contact, so that the flue gas and the alkaline water washing liquid can be fully contacted. As a result, the desulfurization effect of nitrogen oxides, sulfur oxides and dust in the flue gas is better, and the content of nitrogen oxides, sulfur oxides and dust in the flue gas entering the carbon dioxide capture device 103 can be further reduced.

[0058] To further prolong the contact time between the flue gas and the alkaline washing liquid, ensuring sufficient contact between the two, the washing tower 102 may also include a tray (not shown in the figure), which can be positioned below the liquid distributor 1021. The tray has holes at its bottom and receives a certain amount of alkaline washing liquid sprayed from the liquid distributor 1021, maintaining a shallow layer of alkaline washing liquid in the tray. This arrangement allows the flue gas to continue counter-current contact with the alkaline washing liquid sprayed from the liquid distributor 1021 after initial contact with the alkaline washing liquid in the tray, thereby prolonging the contact time between the flue gas and the alkaline washing liquid.

[0059] In the above embodiments of this application, the second inlet of the water washing tower 102 can be supplied with fresh alkaline washing liquid that has not absorbed nitrogen oxides, sulfur oxides, and soot. However, considering the operating cost of the water washing tower 102, in one embodiment, such as Figure 2 As shown, the flue gas treatment system 100 also includes an alkali tank 107, a third conveying pipeline 108, and a fourth conveying pipeline 109. The water scrubbing tower 102 also has a second outlet, and the alkali tank 107 has an outlet. The second outlet of the water scrubbing tower 102 is connected to the second inlet of the water scrubbing tower 102 through the third conveying pipeline 108, and the second outlet of the water scrubbing tower 102 is located at the bottom of the water scrubbing tower 102. The outlet of the alkali tank 107 is connected to the first position A of the third conveying pipeline 108 through the fourth conveying pipeline 109.

[0060] The alkali solution tank 107 can be used to prepare and store the target alkali solution. Specifically, the alkali solution tank 107 can draw demineralized water from the power plant's demineralized water pipeline and a higher concentration initial alkali solution from the power plant's alkali solution pipeline. In the alkali solution tank 107, the demineralized water and the higher concentration initial alkali solution are mixed to obtain the target alkali solution.

[0061] Regulating valves and flow meters can be installed on both the demineralized water inlet pipe and the initial alkali solution inlet pipe. By adjusting the regulating valves, the amount of demineralized water and the amount of initial alkali solution entering the alkali solution tank 107 can be adjusted to obtain the target alkali solution with the required concentration.

[0062] In practical applications, the alkali tank 107 can be further equipped with a stirrer to agitate the liquid inside the tank, thereby obtaining a target alkali solution with uniform concentration. The alkali tank 107 can also be equipped with a level gauge to control the flow rate of the demineralized water and the initial alkali solution.

[0063] In this embodiment, a second outlet is provided at the bottom of the water washing tower 102 for drawing out the bottom liquid. The drawn-out bottom liquid is mixed with the target alkali solution drawn from the alkali tank 107 at the first position A of the third conveying pipeline 108 to obtain an alkaline water washing solution. The mixed alkaline water washing solution then enters the water washing tower 102 through the second inlet and continues to be used for washing the flue gas.

[0064] It is understandable that by adopting the above scheme, by setting a second outlet at the bottom of the water washing tower 102, the bottom liquid of the tower is drawn out and mixed with the target alkaline solution, and then fed into the water washing tower 102 as alkaline water washing liquid, a closed-loop circulation system for obtaining alkaline water washing liquid can be constructed, thereby realizing the reuse of alkaline water washing liquid and reducing the operating cost of the water washing tower 102.

[0065] To facilitate the circulation of the alkaline washing solution, in one embodiment, such as Figure 2 As shown, the flue gas treatment system 100 also includes a first pumping device 110 and a second pumping device 111; the first pumping device 110 is located at the second position B of the third conveying pipeline 108, and the second position B is located downstream of the first position A; the second pumping device 111 is located at the third position C of the fourth conveying pipeline 109.

[0066] The second pumping device 111 provides power for transporting the target alkali solution, enabling it to mix smoothly with the extracted bottom liquid. Specifically, the second pumping device 111 can be a variable frequency pump.

[0067] The first pumping device 110 can be used to provide power for the circulation of alkaline washing solution. Specifically, the first pumping device 110 can be a variable frequency pump.

[0068] The second position B is located downstream of the first position A. This can be understood as, according to the flow direction of the fluid in the third conveying pipeline 108, the second position B is downstream of the first position A. The flow direction of the fluid in the third conveying pipeline 108 can be further specified. Figure 2 As shown by the arrow in the image.

[0069] It is understandable that by adopting the above scheme and adding a first pumping device 110 and a second pumping device 111, power can be provided for the transportation of alkaline washing liquid, thereby realizing the recycling of alkaline washing liquid.

[0070] Furthermore, in one implementation, such as Figure 2 As shown, the flue gas treatment system 100 also includes a cooling device 112, which is located at the fourth position D of the third conveying pipeline 108, and the fourth position D is located downstream of the second position B.

[0071] The cooling device 112 can be used to cool the alkaline washing liquid that is about to be fed into the washing tower 102.

[0072] In practical implementation, the cooling device 112 can utilize the power plant's circulating water to cool the alkaline washing solution. The lower-temperature circulating water exchanges heat with the higher-temperature alkaline washing solution; after the heat exchange, the temperature of the alkaline washing solution decreases, while the temperature of the circulating water increases. The cooled alkaline washing solution is fed into the washing tower 102, while the heated circulating water can be sent to a heat dissipation device for cooling. After cooling, the circulating water returns to the cooling device 112 as a coolant to exchange heat with the alkaline washing solution. The heat dissipation device may include, but is not limited to, a mechanically ventilated cooling tower or a natural draft cooling tower.

[0073] The fourth position D is located downstream of the second position B. This can be understood as the fourth position D being located downstream of the second position B, according to the flow direction of the fluid in the third delivery pipeline 108.

[0074] In practical applications, the temperature of the flue gas entering the water washing tower 102 is generally 55℃~60℃. However, the inventors discovered that the target temperature of the flue gas corresponding to a good absorption effect of carbon dioxide in the carbon dioxide capture device 103 is around 40℃. The solution adopted in this application uses a cooling device 112 installed on the third conveying pipeline 108 to cool the alkaline washing liquid about to enter the water washing tower 102. This lowers the temperature of the alkaline washing liquid entering the water washing tower 102, thereby reducing the temperature of the flue gas and controlling the flue gas entering the carbon dioxide capture device 103 to achieve the target temperature. This improves the absorption effect of the carbon dioxide absorbent on carbon dioxide. Simultaneously, because the alkaline washing liquid has a lower temperature, impurities in the alkaline washing liquid are less likely to volatilize and be carried into the carbon dioxide capture device 103 when in contact with the flue gas.

[0075] In practice, when the target temperature is around 40°C, the temperature of the circulating water used as coolant can be controlled between 32°C and 40°C.

[0076] On the other hand, the flue gas entering the water scrubbing tower 102 contains not only nitrogen oxides, sulfur oxides, and particulate matter, but also water vapor. Through the solution provided in the above embodiments of this application, the flue gas is washed with a low-temperature alkaline washing solution, which also allows the water vapor in the flue gas to condense and remain in the water scrubbing tower; that is, the water vapor in the flue gas can be removed. Therefore, the water content in the flue gas entering the carbon dioxide capture device 103 can be reduced, and the degree of dilution of the carbon dioxide absorbent in the carbon dioxide capture device 103 can be reduced, thereby improving the absorption effect of the carbon dioxide absorbent on carbon dioxide.

[0077] To further reduce the moisture content in the flue gas entering the carbon dioxide capture device 103, in one embodiment, such as Figure 2 As shown, the water washing tower 102 also includes a gas-liquid separation device 1022, which is located at the top of the water washing tower 102. In the water washing tower 102, the washed flue gas passes through the gas-liquid separation device 1022 and is then output from the first outlet of the water washing tower 102.

[0078] The gas-liquid separation device 1022 can be used to further separate the condensate carried in the flue gas. The gas-liquid separation device 1022 can be installed above the second inlet of the water washing tower 102 and below the first outlet of the water washing tower 102.

[0079] In practical applications, after the flue gas is cooled by the alkaline washing solution, some of the condensate flows downwards to the bottom of the washing tower 102, while some condensate remains in the flue gas and flows upwards with it. By adding a gas-liquid separation device 1022, the residual condensate in the flue gas can be further removed. This further reduces the water content in the flue gas entering the carbon dioxide capture device 103, improving the absorption efficiency of the carbon dioxide absorbent.

[0080] As the flue gas is cooled, more and more condensate will accumulate at the bottom of the water washing tower 102. Therefore, in the later stages of system operation, the condensate can be mainly used to mix with the target alkali solution, and the amount of demineralized water supplied to the alkali solution tank 107 for preparing the target alkali solution can be reduced, thereby reducing the operating cost of the system.

[0081] Furthermore, as more and more condensate accumulates at the bottom of the water scrubbing tower 102, the amount of liquid in the bottom of the tower increases, and the liquid level rises. To avoid the bottom liquid affecting the countercurrent contact process between the flue gas and the sprayed alkaline water scrubbing liquid, in one embodiment, the water scrubbing tower 102 also has a third outlet. The flue gas treatment system 100 further includes a carbon dioxide absorbent preparation device 113 and a fifth conveying pipeline 114. The carbon dioxide absorbent preparation device 113 has an inlet and an outlet. The third outlet of the water scrubbing tower 102 is located at the bottom of the water scrubbing tower 102. The third outlet of the water scrubbing tower 102 is connected to the inlet of the carbon dioxide absorbent preparation device 113 through the fifth conveying pipeline 114.

[0082] The third outlet of the water washing tower 102 can draw out excess bottom liquid for use in the preparation of carbon dioxide absorbent. In practice, a target liquid level can be set in the water washing tower 102 beforehand. When the bottom liquid level in the water washing tower 102 exceeds the target liquid level, it indicates that there is too much bottom liquid, and the excess bottom liquid can be drawn out.

[0083] In this embodiment, the excess bottom liquid drawn from the column can be used as a solvent to prepare the carbon dioxide absorbent. When preparing the carbon dioxide absorbent, the demineralized water and condensate from the drawn bottom liquid are mainly utilized. Since the content of nitrogen oxides, sulfur oxides, and particulate matter in the flue gas entering the water washing tower 102 is low, the concentration of nitrogen oxides, sulfur oxides, and particulate matter in the drawn bottom liquid is also low, and therefore their impact on the preparation of the carbon dioxide absorbent can be ignored.

[0084] In practical applications, the carbon dioxide absorbent preparation device 113 can be an underground tank. When preparing carbon dioxide absorbent using the carbon dioxide absorbent preparation device 113, not only can the bottom liquid of the water washing tower 102 be drawn out, but the initial amine raw material can also be fed into the carbon dioxide absorbent preparation device 113. In the carbon dioxide absorbent preparation device 113, the bottom liquid and the initial amine raw material are mixed to prepare the carbon dioxide absorbent.

[0085] After the carbon dioxide absorbent is prepared, it can be fed into the carbon dioxide capture device 103 to absorb carbon dioxide. In a specific implementation, the flue gas treatment system 100 may also include a third pumping device M, which delivers the carbon dioxide absorbent to the carbon dioxide capture device 103.

[0086] It is understandable that by adopting the above scheme, and drawing out the excess bottom liquid to prepare carbon dioxide absorbent, sufficient contact space can be provided for the countercurrent contact process between the flue gas and the alkaline washing liquid, thereby avoiding the influence of the bottom liquid on the countercurrent contact process. Furthermore, the demineralized water and condensate can be recycled, further reducing the system's operating costs.

[0087] Considering that the carbon dioxide capture device 103 may not require the addition of new carbon dioxide absorbent, i.e., the amount of liquid drawn from the bottom of the column is greater than the amount required by the carbon dioxide capture device 103, in one embodiment, such as Figure 2 As shown, the flue gas treatment system 100 also includes an alkaline water washing liquid storage tank 115 and a sixth conveying pipeline 116. The alkaline water washing liquid storage tank 115 has an inlet. The inlet of the alkaline water washing liquid storage tank 115 is connected to the fifth position E of the fifth conveying pipeline 114 through the sixth conveying pipeline 116.

[0088] If the amount of bottom liquid drawn from the tower exceeds the required amount for the carbon dioxide capture device 103, the bottom liquid can be transferred to the alkaline washing liquid storage tank 115 for storage. The bottom liquid stored in the alkaline washing liquid storage tank 115 can be further utilized, for example, it can be returned to the unit's desulfurization unit.

[0089] It is understandable that by adopting the above scheme and adding an alkaline water washing liquid storage tank 115 to store the drawn-out tower bottom liquid, the liquid level of the tower bottom liquid can be further maintained at a reasonable level, thereby ensuring that the flue gas and the sprayed alkaline water washing liquid have sufficient contact space.

[0090] To ensure that the water scrubbing tower 102 effectively removes nitrogen oxides, sulfur oxides, particulate matter, and water vapor from the flue gas, in one embodiment, the flue gas treatment system 100 further includes a flow detection device (such as...). Figure 2 The “FT” in the text), sulfur oxide concentration detection device (such as Figure 2 The "SO2" and nitrogen oxide concentration detection device (in the context of the text) Figure 2 (not shown in the image) Smoke and dust concentration detection device (such as...) Figure 2 The “DUST” in the text) and humidity detection devices (such as Figure 2(TT); at least one of the flow detection devices, at least one of the sulfur oxide concentration detection devices, at least one of the nitrogen oxide concentration detection devices, at least one of the dust concentration detection devices, and at least one of the humidity detection devices are disposed in the first conveying pipeline 104; at least one of the flow detection devices, at least one of the sulfur oxide concentration detection devices, at least one of the nitrogen oxide concentration detection devices, at least one of the dust concentration detection devices, and at least one of the humidity detection devices are disposed in the second conveying pipeline 105.

[0091] The first conveying pipeline 104 is equipped with a flow detection device, a sulfur oxide concentration detection device, a nitrogen oxide concentration detection device, a dust concentration detection device, and a humidity detection device, and the second conveying pipeline 105 is equipped with a flow detection device, a sulfur oxide concentration detection device, a nitrogen oxide concentration detection device, a dust concentration detection device, and a humidity detection device. These devices can be used to precisely control the amount of target alkali solution added, thereby enabling the water washing tower 102 to have a better removal effect on nitrogen oxides, sulfur oxides, dust, and water vapor in the flue gas.

[0092] For example, if the sulfur oxide concentration detection device on the first conveying pipeline 104 detects a sulfur oxide concentration of X in the flue gas, and the desired sulfur oxide concentration in the flue gas after purification by the water scrubbing tower 102 is Y, then the theoretical amount of target alkali solution to be added can be calculated based on X and Y, and the amount of target alkali solution to be added can be adjusted to the theoretical amount. Then, after the system has been running for a certain period of time, the actual concentration Z in the flue gas detected by the sulfur oxide concentration detection device on the second conveying pipeline 105 is used to calculate the deviation between Z and Y, and the amount of target alkali solution to be added is finely adjusted based on this deviation.

[0093] It is understandable that by adopting the above scheme and adding corresponding detection devices to the first conveying pipeline 104 and the second conveying pipeline 105, the precise control of the target alkali solution addition can be achieved, thereby enabling the water washing tower 102 to have a better removal effect on nitrogen oxides, sulfur oxides, dust and water vapor in the flue gas.

[0094] Furthermore, the flue gas treatment system 100 also includes a pH detection device (such as...). Figure 2 The pH detection device can be installed on the third delivery pipeline 108 near the second inlet of the washing tower 102. After the system is running stably, the concentration of the alkaline washing solution tends to remain within a stable range. By installing a pH detection device to detect the alkaline washing solution, the operating status of the system can be monitored.

[0095] In the prior art, to further reduce the dust in the flue gas entering the carbon dioxide capture device 103, a second dust removal device may be provided between the desulfurization device 101 and the carbon dioxide capture device 103. Therefore, in one embodiment, the flue gas treatment system 100 may further include a denitrification device, a first dust removal device, and a second dust removal device. The first conveying pipeline includes a first sub-pipeline and a second sub-pipeline. The second dust removal device has an inlet and an outlet (not shown in the figure). The denitrification device, the first dust removal device, the desulfurization device, and the second dust removal device are connected sequentially. The outlet of the desulfurization device is connected to the inlet of the second dust removal device through the first sub-pipeline, and the outlet of the second dust removal device is connected to the first inlet of the water washing tower through the second sub-pipeline.

[0096] The second dust removal device can be a wet electrostatic precipitator.

[0097] It is understandable that, with the above-mentioned scheme, if a second dust removal device is installed between the desulfurization device 101 and the carbon dioxide capture device 103, the water washing tower 102 can be installed after the second dust removal device; that is, between the second dust removal device and the carbon dioxide capture device 103. This improves the flexibility of equipment modification and enriches the application scenarios of the flue gas treatment system 100.

[0098] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0099] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A flue gas treatment system, characterized in that, The processing system includes a desulfurization unit, a water washing tower, a carbon dioxide capture unit, a first conveying pipeline, and a second conveying pipeline; The desulfurization device has an outlet, the water washing tower has a first inlet and a first outlet, and the carbon dioxide capture device has an inlet; The outlet of the desulfurization unit is connected to the first inlet of the water washing tower through the first conveying pipeline; the first outlet of the water washing tower is connected to the inlet of the carbon dioxide capture unit through the second conveying pipeline. The water washing tower is used to wash the flue gas entering from the first inlet of the water washing tower with alkaline water washing liquid, and the washed flue gas is output through the first outlet of the water washing tower. The water washing tower also has a third outlet, which is located at the bottom of the water washing tower. The treatment system also includes a carbon dioxide absorbent preparation device and a fifth conveying pipeline. The carbon dioxide absorbent preparation device has an inlet and an outlet. The third outlet of the water washing tower is connected to the inlet of the carbon dioxide absorbent preparation device through the fifth conveying pipeline. When the liquid level of the bottom liquid in the water washing tower exceeds the target liquid level, the excess bottom liquid is drawn out. In the carbon dioxide absorbent preparation device, the bottom liquid is mixed with the initial amine liquid raw material to prepare the carbon dioxide absorbent. After the carbon dioxide absorbent is prepared, it is input into the carbon dioxide capture device to absorb carbon dioxide. The processing system also includes an alkaline washing liquid storage tank and a sixth conveying pipeline. The alkaline washing liquid storage tank has an inlet, and the inlet of the alkaline washing liquid storage tank is connected to the fifth position of the fifth conveying pipeline through the sixth conveying pipeline. When the amount of bottom liquid drawn out is more than the amount required by the carbon dioxide capture device, the bottom liquid drawn out is input into the alkaline washing liquid storage tank for storage.

2. The flue gas treatment system according to claim 1, characterized in that, The water washing tower also has a second inlet and a liquid distributor. The liquid distributor is located inside the water washing tower and has an inlet that communicates with the second inlet of the water washing tower. The alkaline washing liquid enters the liquid distributor through the second inlet of the washing tower and is sprayed down through the liquid distributor; In the water washing tower, the flue gas entering from the first inlet of the water washing tower comes into countercurrent contact with the alkaline water washing liquid sprayed down.

3. The flue gas treatment system according to claim 1, characterized in that, The processing system also includes an alkali tank, a third conveying pipeline and a fourth conveying pipeline, the water washing tower also has a second outlet, and the alkali tank has an outlet; The second outlet of the water washing tower is connected to the second inlet of the water washing tower through the third conveying pipeline, and the second outlet of the water washing tower is located at the bottom of the water washing tower; The outlet of the alkali tank is connected to the first position of the third conveying pipeline through the fourth conveying pipeline.

4. The flue gas treatment system according to claim 3, characterized in that, The processing system further includes a first pumping device and a second pumping device; the first pumping device is located at a second position on the third conveying pipeline, the second position being downstream of the first position; the second pumping device is located at a third position on the fourth conveying pipeline.

5. The flue gas treatment system according to claim 4, characterized in that, The processing system further includes a cooling device located at a fourth position in the third conveying pipeline, which is downstream of the second position.

6. The flue gas treatment system according to claim 5, characterized in that, The water washing tower also includes a gas-liquid separation device, which is located at the top of the water washing tower; In the water washing tower, the washed flue gas passes through the gas-liquid separation device and is then output from the first outlet of the water washing tower.

7. The flue gas treatment system according to claim 1, characterized in that, The processing system also includes a flow detection device, a sulfur oxide concentration detection device, a nitrogen oxide concentration detection device, a dust concentration detection device, and a humidity detection device. Among them, at least one of the flow detection devices, at least one of the sulfur oxide concentration detection devices, at least one of the nitrogen oxide concentration detection devices, at least one of the dust concentration detection devices, and at least one of the humidity detection devices are disposed in the first conveying pipeline; At least one of the flow detection devices, at least one of the sulfur oxide concentration detection devices, at least one of the nitrogen oxide concentration detection devices, at least one of the dust concentration detection devices, and at least one of the humidity detection devices are disposed in the second conveying pipeline.

8. The flue gas treatment system according to claim 1, characterized in that, The processing system also includes a denitrification device, a first dust removal device, and a second dust removal device. The first conveying pipeline includes a first sub-pipeline and a second sub-pipeline. The second dust removal device has an inlet and an outlet. The denitrification device, the first dust removal device, the desulfurization device, and the second dust removal device are connected in sequence; The outlet of the desulfurization device is connected to the inlet of the second dust removal device through the first sub-pipeline, and the outlet of the second dust removal device is connected to the first inlet of the water washing tower through the second sub-pipeline.

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