A method for optimizing activated carbon circulation amount

Abstract

A method for optimizing activated carbon circulation volume, comprising the following steps: 1) establishing an activated carbon adsorption rate model based on the activated carbon adsorption rate curve of a desulfurization tower; 2) dividing the activated carbon bed in the desulfurization tower into a front chamber, a middle chamber, and a rear chamber according to the direction of the flue gas, inputting model constants, setting the SO2 concentration at the flue gas inlet of the desulfurization tower, and simulating the desulfurization process for the activated carbon in each chamber; 3) obtaining the activated carbon feed rates of the front, middle, and rear chambers of the desulfurization tower so that the SO2 concentration at the flue gas outlet of the desulfurization tower is within a set range, thereby optimizing the activated carbon circulation volume. The present invention constructs an activated carbon adsorption rate equation and, based on the activated carbon desulfurization, denitrification, and dust removal mechanism, obtains the activated carbon feed rates of each chamber at different SO2 concentrations at the flue gas inlet of the desulfurization tower while ensuring the desulfurization efficiency of the desulfurization tower, thereby optimizing the activated carbon circulation volume and providing guidance for the operation of actual projects.

Description

Technical Field

[0001] The invention relates to controlling and adjusting the activated carbon circulation amount of an adsorption tower, and in particular to a method for optimizing the activated carbon circulation amount, belonging to the technical field of activated carbon flue gas purification. Background Art

[0002] The activated carbon flue gas purification process has many advantages. At present, the two-stage flue gas purification process has been widely used in the field of sintering flue gas treatment, but there are also many problems. For example, the desulfurization of activated carbon mainly relies on micropores and surface functional groups, and the denitrification mainly relies on oxygen-containing functional groups on the surface of activated carbon. The dust is mainly composed of sintering original dust and carbon powder. Among them, the desulfurization, denitrification and dust removal capabilities are closely related to the activated carbon circulation volume. The larger the activated carbon circulation volume, the stronger the desulfurization and denitrification capabilities, but the dust removal capacity is weakened. For the currently common two-stage activated carbon process or activated carbon + SCR process, the activated carbon circulation volume is mainly determined by the desulfurization capacity. When the SO2 concentration at the outlet of the desulfurization tower is less than 35mg / Nm 3 When the denitrification efficiency is not affected, it can reach about 80%.

[0003] The current activated carbon circulation control logic is relatively crude. As described above, the circulation rate is adjusted by controlling the SO2 concentration at the flue gas outlet of the first tower. Firstly, because the system contains thousands of tons of activated carbon, its adsorption capacity for SO2 is very strong compared to other pollutants, resulting in significant hysteresis. For example, when the outlet SO2 exceeds the standard, it indicates that the activated carbon circulation rate has been reduced for a long time, and it takes a long time for the system to return to optimal operation. Secondly, the activated carbon system is divided into three layers: front, middle, and back. The adsorption rate of SO2 in the flue gas varies significantly at different locations. For example, the front layer faces a high SO2 concentration in the flue gas, resulting in a short residence time and a fast adsorption rate. The middle layer has a slower rate, and the back layer has the slowest rate. Thirdly, due to the large amount of activated carbon loaded in the adsorption tower and the lack of independent space between the front, middle, and back chambers, flue gas monitoring is not possible. Therefore, it is difficult to adjust the activated carbon residence time based on the flue gas concentration in the front, middle, and back chambers.

[0004] The following rules apply to the process of activated carbon running from top to bottom. Taking the front chamber as an example, the activated carbon at the top has a well-developed pore structure and rich surface functional groups, and has excellent desulfurization performance. The activated carbon in the middle has already adsorbed some SO2, the pores are blocked, and the rate of adsorption of SO2 slows down. The activated carbon at the bottom has already adsorbed a large amount of SO2, and its ability to adsorb SO2 in the gas again is the slowest. Therefore, the SO2 concentration at the front chamber outlet increases from top to bottom. Similarly, the same rules apply to the middle and rear chamber outlets. When the inlet flue gas volume and SO2 concentration are kept consistent, the pollutant concentration at the front chamber outlet is related to the feed rate of the front chamber activated carbon, the pollutant concentration at the middle chamber outlet is related to the feed rate of the front chamber and the feed rate of the middle chamber, and the pollutant concentration at the rear chamber outlet is related to the feed rate of the front chamber, the feed rate of the middle chamber, and the feed rate of the rear chamber. In theory, any change in the feed rate of each chamber will affect the change in the outlet SO2 concentration.

[0005] The denitrification efficiency of activated carbon is closely related to the SO2 concentration. When the SO2 concentration is high, part of the added NH3 will react with SO2 to generate corresponding sulfate, which will affect the denitrification efficiency. When the SO2 concentration at the secondary tower entrance is lower than 35mg / Nm 3 The denitrification efficiency is not affected. Laboratory studies have also shown that denitrification efficiency is not significantly correlated with activated carbon circulation volume, so the activated carbon circulation volume sufficient to meet desulfurization requirements is sufficient. Therefore, this application aims to address the issue of optimizing the activated carbon circulation volume while still meeting the desulfurization requirements of the primary tower. Summary of the Invention

[0006] To address the shortcomings of the aforementioned prior art, the present invention proposes a method for optimizing activated carbon circulation. Based on the characteristic patterns of activated carbon desulfurization, this method establishes an activated carbon adsorption rate equation that relates the SO₂ concentration at the flue gas outlet of the front, middle, and rear chambers of the desulfurization tower to the activated carbon feed rate in each chamber. Furthermore, based on the desulfurization, denitrification, and dust removal mechanisms of activated carbon, the activated carbon feed rates for the front, middle, and rear chambers are calculated under different SO₂ concentrations at the flue gas inlet of the desulfurization tower, while ensuring the desulfurization efficiency of the desulfurization tower. This method optimizes the activated carbon circulation rate and guides project operation.

[0007] According to an embodiment of the present invention, a method for optimizing the amount of activated carbon circulation is provided.

[0008] A method for optimizing activated carbon circulation, the method comprising the following steps:

[0009] 1) According to the activated carbon adsorption rate curve of the desulfurization tower, an activated carbon adsorption rate model is established.

[0010] 2) According to the direction of the flue gas, the activated carbon bed in the desulfurization tower is divided into the front chamber, the middle chamber, and the rear chamber. The model constants are input, the SO2 concentration at the flue gas inlet of the desulfurization tower is set, and the desulfurization process of the activated carbon in each chamber is simulated.

[0011] 3) Obtain the activated carbon feeding rate in the front, middle and rear chambers of the desulfurization tower so that the SO2 concentration at the flue gas outlet of the desulfurization tower is within the set range, thereby optimizing the activated carbon circulation amount.

[0012] In the present invention, in step 1), establishing the activated carbon adsorption rate model specifically includes the following sub-steps:

[0013] 101) According to the variation law of SO2 concentration ratio at the inlet and outlet of the desulfurization tower over time, the rate of SO2 adsorption by activated carbon is divided into three stages: the first stage is a fast constant rate stage, the second stage is an exponential stage, and the third stage is a slow constant rate stage.

[0014] 102) Based on the change pattern of the amount of SO2 adsorbed by activated carbon over time during the desulfurization process, draw the activated carbon adsorption rate curve.

[0015] 103) Based on the characteristic that the rate of SO2 adsorption by activated carbon in sub-step 101) is constant in the first and third stages, combined with the activated carbon adsorption rate curve in sub-step 102), an activated carbon adsorption rate equation is constructed.

[0016] 104) The activated carbon bed in the desulfurization tower is divided into grids, and the activated carbon adsorption rate equation in sub-step 103) is applied to each grid in turn according to the direction of the flue gas.

[0017] In the present invention, in step 2), the activated carbon bed in the desulfurization tower is divided into a front chamber, a middle chamber, and a rear chamber. The activated carbon feed rate in the front chamber is V1, the activated carbon feed rate in the middle chamber is V2, and the activated carbon feed rate in the rear chamber is V3. Among them, V1:V2:V3 = (5.5-6.5):(1.5-2.5):1, preferably V1:V2:V3 = (5.7-6.3):(1.8-2.2):1.

[0018] In the present invention, in sub-step 103), the activated carbon adsorption rate equation is:

[0019]

[0020] Where: Q is the adsorption capacity of activated carbon, mg / g. t is the residence time of activated carbon in the desulfurization tower, h. α is the correction term. C is the SO2 concentration in the flue gas, mg / m 3 l is the reaction order of SO2 elementary reaction to produce sulfuric acid. Ea is the activation energy of activated carbon, kJ / mol. R is the gas constant, J / (mol·K). T is the flue gas temperature, K. K1 is the adsorption rate of SO2 in the first stage of sulfuric acid accumulation process in the activated carbon adsorption rate curve, h -1K2 is the adsorption rate of SO2 in the third stage of sulfuric acid accumulation process in the activated carbon adsorption rate curve, h -1 Qs is the apparent saturated adsorption capacity of activated carbon for SO2, mg / g.

[0021] In the present invention, sub-step 104) specifically involves dividing the activated carbon bed within the desulfurization tower into grids, with the height of the activated carbon bed divided into m grids and the width of the activated carbon bed divided into n grids. The activated carbon adsorption rate equation is applied to each grid in turn, and the adsorption capacity and SO2 concentration of each grid are iteratively calculated based on the activated carbon adsorption rate equation. The activated carbon adsorption capacity Q[0, j] of the topmost grid of the desulfurization tower is 0, and the SO2 concentration C[i, 0] of the grid at the flue gas inlet of the desulfurization tower is C0. That is,

[0022] Q[i,j]=Q[i-1,j]+dQ[i,j]...(2).

[0023] dt=(h / m) / v…(3).

[0024] C[i,j]=C[i,j-1]-dC[i,j]...(4).

[0025] Where: Q[i, j] represents the adsorption capacity of the activated carbon at the grid corresponding to the i-th grid in the height direction and the j-th grid in the width direction of the activated carbon bed, dQ[i, j] represents the newly adsorbed capacity of the activated carbon in the current grid. C[i, j] represents the SO2 concentration of the grid corresponding to the i-th grid in the height direction and the j-th grid in the width direction of the activated carbon bed, and dC[i, j] represents the reduction in SO2 concentration due to adsorption by the activated carbon in the current grid. Where i ≤ m, j ≤ n. dt represents the residence time of the activated carbon in the current grid. h represents the height of the activated carbon bed in the desulfurization tower. v represents the activated carbon feed rate at the corresponding position in the desulfurization tower. C0 represents the SO2 concentration at the flue gas inlet of the desulfurization tower.

[0026] In the present invention, in step 3), the SO2 concentration at the flue gas inlet of the desulfurization tower is detected online, and the activated carbon feeding speeds of the front, middle and rear chambers of the desulfurization tower are calculated by the activated carbon adsorption rate equation according to the proportional relationship between the activated carbon feeding speeds of the front, middle and rear chambers of the desulfurization tower. The activated carbon feeding speeds of the front, middle and rear chambers of the desulfurization tower are adjusted so that the SO2 concentration at the flue gas outlet of the desulfurization tower is less than C 设 .

[0027] Where: C 设 It is the upper limit of SO2 concentration at the flue gas outlet of the desulfurization tower. 设 ≤35mg / Nm 3 .

[0028] In the present invention, the activated carbon feeding speed of the front, middle and rear chambers of the desulfurization tower is adjusted so that the SO2 concentration at the flue gas outlet of the desulfurization tower is less than C 设 Specifically:

[0029] 301) According to the SO2 concentration at the flue gas inlet of the desulfurization tower, combined with the proportional relationship between the activated carbon feeding speeds of the front, middle and rear chambers of the desulfurization tower, and the SO2 concentration at the flue gas outlet of the desulfurization tower is less than C 设 With this as the goal, the activated carbon feeding rates in the front, middle and rear chambers of the desulfurization tower were preliminarily optimized by calculating the activated carbon adsorption rate equation.

[0030] 302) Based on the calculated preliminary optimized activated carbon feeding speeds in the front, middle and rear chambers of the desulfurization tower, calculate the preliminary SO2 concentration C at the flue gas outlet of the desulfurization tower at the corresponding activated carbon feeding speeds. 初 Compare the initial SO2 concentration C 初 and SO2 concentration upper limit C 设 .

[0031] 302a) If the initial SO2 concentration C 初 <C 设 , record the current activated carbon feeding speed of each chamber, then slightly reduce the activated carbon feeding speed of the front, middle and rear chambers of the desulfurization tower that is initially optimized, calculate the adjusted SO2 concentration at the flue gas outlet of the desulfurization tower according to the activated carbon feeding speed of each chamber after adjustment, and compare the adjusted SO2 concentration with the upper limit of SO2 concentration C 设 Repeat this step until the calculated SO2 concentration at the flue gas outlet of the desulfurization tower is ≥C 设 At this time, the last recorded activated carbon feeding rate in each chamber is the optimal feeding rate, thereby determining the optimal circulation amount of activated carbon.

[0032] In the present invention, step 302) further includes:

[0033] 302b) If the initial SO2 concentration C 初 ≥C 设 , slightly increase the activated carbon feeding speed of the front, middle and rear chambers of the preliminary optimized desulfurization tower, then record the current activated carbon feeding speed of each chamber, calculate the adjusted SO2 concentration at the flue gas outlet of the desulfurization tower according to the activated carbon feeding speed of each chamber after adjustment, and compare the adjusted SO2 concentration with the upper limit of SO2 concentration C 设 Repeat this step until the calculated SO2 concentration at the flue gas outlet of the desulfurization tower is less than C 设 At this time, the last recorded activated carbon feeding rate in each chamber is the optimal feeding rate, thereby determining the optimal circulation amount of activated carbon.

[0034] In the present invention, in step 2), the model constants include: the thickness of the front chamber, the thickness of the middle chamber, the thickness of the rear chamber of the desulfurization tower, and the height and width of the activated carbon bed in the desulfurization tower.

[0035] In the current common two-stage activated carbon process, the activated carbon circulation volume is mainly determined by the desulfurization capacity. When the SO2 concentration at the flue gas outlet of the first-stage adsorption tower is less than 35mg / Nm 3 , the denitrification efficiency of the secondary adsorption tower can remain unaffected and reach about 80%. However, the current activated carbon circulation control logic is relatively extensive. Due to the large amount of activated carbon loaded in the adsorption tower, there is no independent space between the front, middle and rear chambers, and there are no flue gas detection conditions. Therefore, the activated carbon circulation volume is often adjusted by detecting and controlling the SO2 concentration at the flue gas outlet of the first-level tower (i.e., the desulfurization tower), and the hysteresis is obvious. According to laboratory research, the denitrification efficiency has little to do with the activated carbon circulation volume, so the activated carbon circulation volume can meet the desulfurization requirements. Based on this, the present invention proposes a method for optimizing the activated carbon circulation volume, which aims to solve the problem of how to optimize the activated carbon circulation volume while meeting the desulfurization requirements of the first-level tower. In the scheme of the present invention, according to the characteristic law of activated carbon desulfurization, an activated carbon adsorption rate equation is established to show the relationship between the SO2 concentration at the flue gas outlet of the front, middle and rear chambers of the desulfurization tower and the activated carbon feeding rate of each chamber. Based on the activated carbon desulfurization, denitrification and dust removal mechanism, while ensuring the desulfurization efficiency of the desulfurization tower, the activated carbon feeding rates of the front, middle and rear chambers at different SO2 concentrations at the flue gas inlet of the desulfurization tower are obtained, thereby realizing the optimization of the activated carbon circulation amount and guiding the operation of the project.

[0036] The method for optimizing the activated carbon circulation amount of the present invention mainly comprises the following steps:

[0037] 1) According to the activated carbon adsorption rate curve of the desulfurization tower, an activated carbon adsorption rate model is established.

[0038] 101) Figure 4 As shown in the figure, according to the change pattern of the SO2 concentration ratio at the inlet and outlet of the flue gas of the desulfurization tower over time, the rate of activated carbon desulfurization, that is, the rate of activated carbon adsorption of SO2, can be divided into three stages. The first stage is a fast constant rate stage, the second stage is an exponential stage, and the third stage is a slow constant rate stage.

[0039] like Figure 5 As shown in the figure, according to the change pattern of SO2 concentration at the flue gas outlet of the desulfurization tower over time, it can be seen that as time goes by, the adsorption capacity of activated carbon for SO2 gradually tends to saturation, the SO2 concentration at the flue gas outlet gradually increases, and after a long time, the SO2 concentration at the flue gas outlet increases more slowly.

[0040] 102) Figure 6 As shown in the figure, according to the change law of the amount of SO2 adsorbed by activated carbon over time during the desulfurization process, the activated carbon adsorption rate curve is drawn.

[0041] Through experimental research, the amount of SO2 adsorbed by activated carbon changes with time in the form of a curve, that is, the rate curve of SO2 adsorption by activated carbon is obtained. Figure 6 As shown in the figure, in the initial stage, the SO2 concentration in the flue gas is high, the activated carbon has a well-developed pore structure, and the rate of SO2 adsorption by the activated carbon remains at a fast average value. At the end of the reaction, due to the adsorption effect of the activated carbon, the SO2 concentration in the flue gas decreases. After partially adsorbing SO2, the activated carbon's pores become clogged, and the adsorption rate slows down, basically maintaining a relatively slow average value. The activated carbon adsorption rate curve shows that the amount of SO2 adsorbed by the activated carbon gradually increases with the extension of adsorption time, and the adsorption amount increases more slowly after a long period of time.

[0042] 103) Based on the characteristic that the rate of SO2 adsorption by activated carbon in sub-step 101) is constant in the first and third stages, combined with the activated carbon adsorption rate curve in sub-step 102), an activated carbon adsorption rate equation is constructed:

[0043]

[0044] In formula (1), Q is the adsorption capacity of activated carbon, mg / g. t is the residence time of activated carbon in the desulfurization tower, h. α is the correction term. C is the SO2 concentration in the flue gas, mg / m 3 l is the reaction order of SO2 elementary reaction to produce sulfuric acid. Ea is the activation energy of activated carbon, kJ / mol. R is the gas constant, J / (mol·K). T is the flue gas temperature, K. K1 is the adsorption rate of SO2 in the first stage of sulfuric acid accumulation process in the activated carbon adsorption rate curve, h -1 K2 is the adsorption rate of SO2 in the third stage of sulfuric acid accumulation process in the activated carbon adsorption rate curve, h -1 Qs is the apparent saturated adsorption capacity of activated carbon for SO2, mg / g.

[0045] When the SO2 concentration in the sintering flue gas is 200-1000ppm, the moisture content is 10-12%, and the oxygen content is 15-17%, the reaction order of SO2 is calculated to be l=0.8, the correction term α=0.22, and K1=7.2h -1 , K2=0.008h -1 .

[0046] 104) The activated carbon bed in the desulfurization tower is divided into grids, and the activated carbon adsorption rate equation in sub-step 103) is applied to each grid in turn according to the direction of the flue gas.

[0047] The grid division described here can be understood as establishing a coordinate system on the activated carbon bed of the desulfurization tower, dividing the height and width of the activated carbon bed in the desulfurization tower into grids respectively, and then applying the activated carbon adsorption rate equation to each grid in turn according to the direction of the flue gas, so that the adsorption amount of each grid, SO2 concentration, etc. can be obtained by iterative calculation through software or computer program based on the equation.

[0048] Specifically, the activated carbon bed in the desulfurization tower is divided into grids, with the height of the activated carbon bed divided into m grids and the width of the activated carbon bed divided into n grids. The activated carbon adsorption rate equation is applied to each grid in turn, and the adsorption amount and SO2 concentration of each grid are iteratively calculated based on the activated carbon adsorption rate equation. That is,

[0049] Q[i,j]=Q[i-1,j]+dQ[i,j]...(2).

[0050] dt=(h / m) / v…(3).

[0051] C[i,j]=C[i,j-1]-dC[i,j]...(4).

[0052] Given the activated carbon adsorption capacity Q[0, j] = 0 at the topmost grid of the desulfurization tower, we can iterate the activated carbon adsorption capacity at any grid and the newly adsorbed capacity at the current grid using formula (2) from top to bottom. Given the SO2 concentration C[i, 0] = C0 at the flue gas inlet of the desulfurization tower, we can iterate the SO2 concentration at the outlet of any grid from the flue gas inlet to the flue gas outlet of the desulfurization tower using formula (4).

[0053] In formulas (2)-(4), Q[i, j] represents the adsorption capacity of the grid corresponding to the i-th grid in the height direction and the j-th grid in the width direction of the activated carbon bed, and dQ[i, j] represents the newly adsorbed capacity of the activated carbon in the current grid. C[i, j] represents the SO2 concentration of the grid corresponding to the i-th grid in the height direction and the j-th grid in the width direction of the activated carbon bed, and dC[i, j] represents the reduced SO2 concentration due to the adsorption of the activated carbon in the current grid. dC[i, j] can be converted from dQ[i, j]. Where i≤m, j≤n. dt represents the residence time of the activated carbon in the current grid. h is the height of the activated carbon bed in the desulfurization tower. v is the activated carbon feed rate at the corresponding position in the desulfurization tower. C0 is the SO2 concentration at the flue gas inlet of the desulfurization tower.

[0054] When fitting the activated carbon adsorption rate equation (1) described above, the present invention divides the activated carbon bed in the desulfurization tower into multiple grids and iteratively calculates each grid in turn through software or a computer program. At this time, dQ can be understood as the newly added adsorption amount of the activated carbon in the current grid, and dt can be understood as the residence time of the activated carbon in the current grid. The grid division has completed the spatial positioning of different positions in the desulfurization tower, and formula (3) shows that the residence time of the activated carbon in the corresponding grid is related to the discharge rate of the activated carbon at the corresponding position. Therefore, through the residence time of the activated carbon in the corresponding grid, the grid division, and the iterative calculation between each grid, the relationship between the various parameters in the above equation (1) and the structural data of the desulfurization tower (including the height, width, total thickness, thickness of each layer, etc. of the desulfurization tower) and the discharge rate of each layer of activated carbon is reflected.

[0055] For any grid in the activated carbon bed, as long as the SO2 concentration at the flue gas inlet of the desulfurization tower, the flue gas temperature, the activated carbon feeding rate of the front chamber and other inlet parameters are given, the outlet parameters of the first grid can be calculated by the above activated carbon adsorption rate equation (1). At the same time, the outlet parameters of the grid become the inlet parameters of the next grid. Then, by iterative calculations in succession through software or computer programs, the outlet parameters of any grid can be obtained. In the present invention, the activated carbon feeding rates of the front, middle and rear chambers are unknown quantities and are parameters that need to be obtained and optimized. At this time, based on the flue gas direction, when the upper limit of the SO2 concentration at the flue gas outlet of the desulfurization tower (i.e., the outlet parameter of the last grid) is known, and the ratio of the activated carbon feeding rates of the front, middle and rear chambers is set according to experience, the calculation process for obtaining the outlet parameters of any grid is reversed, and the activated carbon feeding rate of each chamber can be calculated, thereby optimizing the activated carbon circulation amount and guiding the operation of the actual project.

[0056] It should be noted that all formulas in the present invention are obtained by fitting by the inventors based on experiments and engineering applications, and all calculations are numerical values ​​converted according to prescribed units, and are obtained by substituting the converted numerical values ​​into the formulas (after converting the units, only the numerical values ​​are substituted into the formulas for calculation, without substituting the units, and the units are only used to adjust the size of the numerical values).

[0057] 2) According to the direction of the flue gas, the activated carbon bed in the desulfurization tower is divided into the front chamber, the middle chamber, and the rear chamber. The model constants are input, the SO2 concentration at the flue gas inlet of the desulfurization tower is set, and the desulfurization process of the activated carbon in each chamber is simulated.

[0058] The present application divides the activated carbon bed in the desulfurization tower into three layers, namely the front, middle and rear chambers. Among them, the activated carbon feeding rate of the front chamber is V1, the activated carbon feeding rate of the middle chamber is V2, and the activated carbon feeding rate of the rear chamber is V3. According to laboratory research and engineering practice experience, under the thickness, height, width and other structures of each layer of activated carbon bed in the existing desulfurization tower, considering multiple factors such as the feeding uniformity and operation safety of each layer of activated carbon in the entire desulfurization tower, the activated carbon feeding rates of the front, middle and rear chambers meet a certain proportional relationship, for example, V1:V2:V3=(5.5-6.5):(1.5-2.5):1, preferably V1:V2:V3=(5.7-6.3):(1.8-2.2):1, specifically, V1:V2:V3=6:2:1.

[0059] The model constants described here include, for example, the thickness of the front, middle, and rear chambers of the desulfurization tower, as well as the height and width of the activated carbon bed within the desulfurization tower. Subsequent desulfurization simulations and related parameter calculations for each layer of activated carbon are based on these input model constants.

[0060] 3) Obtain the activated carbon feeding rate in the front, middle and rear chambers of the desulfurization tower so that the SO2 concentration at the flue gas outlet of the desulfurization tower is within the set range, thereby optimizing the activated carbon circulation amount.

[0061] The SO2 concentration at the flue gas inlet of the desulfurization tower is detected online. The activated carbon feeding speeds of the front, middle and rear chambers of the desulfurization tower are calculated iteratively by software or computer program according to the activated carbon adsorption rate equation based on the proportional relationship between the activated carbon feeding speeds of the front, middle and rear chambers of the desulfurization tower. The activated carbon feeding speeds of the front, middle and rear chambers of the desulfurization tower are adjusted so that the SO2 concentration at the flue gas outlet of the desulfurization tower is less than C 设 Among them: C 设 It is the upper limit of SO2 concentration at the flue gas outlet of the desulfurization tower. 设 ≤35mg / Nm 3 .

[0062] In the above-mentioned calculation process of simulated desulfurization, the relevant parameters detected online (such as the SO2 concentration at the flue gas inlet of the desulfurization tower, etc.) are the actual engineering parameters. This application is based on the existing actual engineering parameters to simulate and experimentally study the desulfurization process of the desulfurization tower, so as to obtain the activated carbon feeding rate of each chamber under different SO2 concentration conditions at the flue gas inlet of the desulfurization tower, and make the SO2 concentration at the flue gas outlet of the desulfurization tower meet the control standard without affecting the denitrification efficiency of the subsequent denitrification tower, thereby realizing the control and optimization of the activated carbon circulation amount in the activated carbon flue gas purification process, and providing guidance for the operation of the actual project.

[0063] After achieving a certain degree of optimization in the activated carbon feed rate of each chamber with the goal of ensuring that the SO2 concentration at the flue gas outlet of the desulfurization tower meets the control standard, this application can further optimize the activated carbon circulation volume by (slightly) adjusting the activated carbon feed rate of the front, middle, and rear chambers of the desulfurization tower. The specific adjustment steps are as follows:

[0064] 301) According to the SO2 concentration at the flue gas inlet of the desulfurization tower, combined with the proportional relationship between the activated carbon feeding speeds of the front, middle and rear chambers of the desulfurization tower, and the SO2 concentration at the flue gas outlet of the desulfurization tower is less than C 设 With this as the goal, the activated carbon feeding rates in the front, middle and rear chambers of the desulfurization tower were preliminarily optimized by calculating the activated carbon adsorption rate equation.

[0065] 302) Based on the calculated preliminary optimized activated carbon feeding speeds in the front, middle and rear chambers of the desulfurization tower, calculate the preliminary SO2 concentration C at the flue gas outlet of the desulfurization tower at the corresponding activated carbon feeding speeds. 初 Compare the initial SO2 concentration C 初 and SO2 concentration upper limit C 设 .

[0066] 302a) If the initial SO2 concentration C 初 <C 设 , record the current activated carbon feeding speed of each chamber, then slightly reduce the activated carbon feeding speed of the front, middle and rear chambers of the desulfurization tower that is initially optimized, calculate the adjusted SO2 concentration at the flue gas outlet of the desulfurization tower according to the activated carbon feeding speed of each chamber after adjustment, and compare the adjusted SO2 concentration with the upper limit of SO2 concentration C 设 Repeat this step until the calculated SO2 concentration at the flue gas outlet of the desulfurization tower is ≥C 设 At this time, the last recorded activated carbon feeding rate in each chamber is the optimal feeding rate, thereby determining the optimal circulation amount of activated carbon.

[0067] 302b) If the initial SO2 concentration C 初 ≥C 设 , slightly increase the activated carbon feeding speed of the front, middle and rear chambers of the preliminary optimized desulfurization tower, then record the current activated carbon feeding speed of each chamber, calculate the adjusted SO2 concentration at the flue gas outlet of the desulfurization tower according to the activated carbon feeding speed of each chamber after adjustment, and compare the adjusted SO2 concentration with the upper limit of SO2 concentration C 设 Repeat this step until the calculated SO2 concentration at the flue gas outlet of the desulfurization tower is less than C 设 At this time, the last recorded activated carbon feeding rate in each chamber is the optimal feeding rate, thereby determining the optimal circulation amount of activated carbon.

[0068] The activated carbon feed rate calculated in step 301) above represents the preliminary optimization result for ensuring desulfurization efficiency in the desulfurization tower. Generally speaking, while maintaining a constant total pollutant concentration at the desulfurization tower flue gas inlet, the lower the SO2 concentration at the desulfurization tower flue gas outlet, the greater the required activated carbon circulation rate. Therefore, the activated carbon feed rate calculated in steps 302a) and 302b) above represents the optimal activated carbon feed rate achieved while minimizing the feed rates in the front, middle, and rear chambers while maintaining desulfurization efficiency, thereby achieving the optimal activated carbon circulation rate.

[0069] Among them, the activated carbon feeding speed of the front, middle and rear chambers of the desulfurization tower that has been preliminarily optimized is slightly adjusted (lowered or increased). The said slight adjustment refers to fine-tuning the currently calculated activated carbon feeding speed of each chamber by a certain smaller amplitude. The adjustment amplitude is not limited and can be selected in combination with actual engineering needs. For example, under the condition that the activated carbon feeding speed of the front, middle and rear chambers meets V1:V2:V3=6:2:1, the activated carbon feeding speed of the front, middle and rear chambers is adjusted by 0.018m / h, 0.006m / h and 0.003m / h respectively. By making such a slight adjustment to the activated carbon feeding speed of each chamber that has been preliminarily optimized, the minimum activated carbon circulation amount that meets the desulfurization control standard can be obtained in this process, that is, the investment cost can be reduced while ensuring the desulfurization efficiency.

[0070] It should be noted that the activated carbon feeding speed of the front, middle and rear chambers of the desulfurization tower obtained in the preliminary optimization in step 301) is based on the SO2 concentration at the flue gas outlet of the desulfurization tower being less than C 设 The target is calculated, but the present invention is based on the characteristic law of activated carbon desulfurization and simulates the desulfurization process of the desulfurization tower. Therefore, although the result is calculated under this premise, the preliminary SO2 concentration C in step 302b) may still appear. 初 ≥C 设 situation.

[0071] In addition, during the laboratory research process, for the activated carbon adsorption rate equation constructed by the present invention, given the actual engineering parameters, including the SO2 concentration at the flue gas inlet of the desulfurization tower, and the activated carbon feeding speeds in the front, middle and rear chambers, the simulated value of the SO2 concentration at the flue gas outlet of the desulfurization tower calculated by the activated carbon adsorption rate equation has a small deviation from the actual value of the SO2 concentration at the flue gas outlet detected by the SO2 concentration detection device. Therefore, it also shows that the activated carbon adsorption rate model constructed by the present invention has a high degree of fitting and good fitting effect, and can truly realize the optimization of the activated carbon circulation amount, provide guidance for the operation of actual projects, and escort.

[0072] Compared with the prior art, the present invention has the following beneficial technical effects:

[0073] 1. The present invention establishes an activated carbon adsorption rate equation for the relationship between the SO2 concentration at the flue gas outlet of the front, middle and rear chambers of the desulfurization tower and the activated carbon feeding rate of each chamber according to the characteristic law of activated carbon desulfurization through experimental research methods. Based on the desulfurization, denitrification and dust removal mechanism of activated carbon, and on the premise of ensuring the desulfurization efficiency of the desulfurization tower, the activated carbon feeding rate of the front, middle and rear chambers at different SO2 concentrations at the flue gas inlet of the desulfurization tower is obtained, thereby optimizing the activated carbon circulation amount and guiding the operation of the project.

[0074] 2. The present invention constructs an activated carbon adsorption rate equation, and obtains a preliminary optimized activated carbon feeding rate in each chamber with the goal of ensuring that the SO2 concentration at the flue gas outlet of the desulfurization tower meets the control standard, thereby achieving preliminary optimization of the activated carbon circulation amount; the present invention also makes small adjustments to the preliminary optimized activated carbon feeding rate in each chamber, while ensuring the desulfurization efficiency of the desulfurization tower, and at the same time reduces the activated carbon feeding rates in the front, middle and rear chambers as much as possible to obtain the optimal activated carbon feeding rate, and then obtains the best activated carbon circulation amount, thereby achieving further optimization of the activated carbon circulation amount, that is, reducing investment costs while ensuring desulfurization efficiency.

[0075] 3. The predicted value calculated by the activated carbon adsorption rate equation in the present invention has a small deviation from the actual value, that is, the activated carbon adsorption rate model constructed by the present invention has a high degree of fitting and a good fitting effect, which can truly optimize the activated carbon circulation amount and provide guidance and protection for the operation of actual projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] Figure 1 A schematic diagram of a method for optimizing activated carbon circulation volume according to the present invention;

[0077] Figure 2 The process for determining the optimal circulation amount of activated carbon in the present invention Figure 1 ;

[0078] Figure 3 The process for determining the optimal circulation amount of activated carbon in the present invention Figure 2 ;

[0079] Figure 4 This is the graph showing the change of SO2 concentration ratio at the inlet and outlet of the desulfurization tower over time;

[0080] Figure 5 This is the graph showing the change of SO2 concentration at the flue gas outlet of the desulfurization tower over time;

[0081] Figure 6 This is a graph showing the change in the amount of SO2 adsorbed by activated carbon over time. DETAILED DESCRIPTION

[0082] The technical solutions of the present invention are illustrated below with examples, and the scope of protection requested by the present invention includes but is not limited to the following embodiments.

[0083] Example 1

[0084] A method for optimizing activated carbon circulation, the method comprising the following steps:

[0085] 1) According to the activated carbon adsorption rate curve of the desulfurization tower, an activated carbon adsorption rate model is established.

[0086] 2) According to the direction of the flue gas, the activated carbon bed in the desulfurization tower is divided into the front chamber, the middle chamber, and the rear chamber. The model constants are input, the SO2 concentration at the flue gas inlet of the desulfurization tower is set, and the desulfurization process of the activated carbon in each chamber is simulated.

[0087] 3) Obtain the activated carbon feeding rate in the front, middle and rear chambers of the desulfurization tower so that the SO2 concentration at the flue gas outlet of the desulfurization tower is within the set range, thereby optimizing the activated carbon circulation amount.

[0088] Example 2

[0089] like Figure 1 As shown, a method for optimizing the activated carbon circulation amount comprises the following steps:

[0090] 1) Based on the activated carbon adsorption rate curve of the desulfurization tower, establish an activated carbon adsorption rate model. Specifically, it includes the following sub-steps:

[0091] 101) Figure 4 As shown in the figure, according to the change pattern of SO2 concentration ratio at the inlet and outlet of the desulfurization tower over time, the rate of SO2 adsorption by activated carbon is divided into three stages: the first stage is a fast constant rate stage, the second stage is an exponential stage, and the third stage is a slow constant rate stage.

[0092] 102) Figure 6 As shown in the figure, according to the change law of the amount of SO2 adsorbed by activated carbon over time during the desulfurization process, the activated carbon adsorption rate curve is drawn.

[0093] 103) Based on the characteristic that the rate of SO2 adsorption by activated carbon in sub-step 101) is constant in the first and third stages, combined with the activated carbon adsorption rate curve in sub-step 102), an activated carbon adsorption rate equation is constructed:

[0094]

[0095] Where: Q is the adsorption capacity of activated carbon, mg / g. t is the residence time of activated carbon in the desulfurization tower, h. α is the correction term. C is the SO2 concentration in the flue gas, mg / m 3l is the reaction order of SO2 elementary reaction to produce sulfuric acid. Ea is the activation energy of activated carbon, kJ / mol. R is the gas constant, J / (mol·K). T is the flue gas temperature, K. K1 is the adsorption rate of SO2 in the first stage of sulfuric acid accumulation process in the activated carbon adsorption rate curve, h -1 K2 is the adsorption rate of SO2 in the third stage of sulfuric acid accumulation process in the activated carbon adsorption rate curve, h -1 Qs is the apparent saturated adsorption capacity of activated carbon for SO2, mg / g.

[0096] 104) Divide the activated carbon bed in the desulfurization tower into a grid. According to the direction of the flue gas, apply the activated carbon adsorption rate equation in sub-step 103) to each grid in turn. Specifically:

[0097] The activated carbon bed in the desulfurization tower is divided into a grid, with the height of the activated carbon bed divided into m grids and the width of the activated carbon bed divided into n grids. The activated carbon adsorption rate equation is applied to each grid in turn, and the adsorption capacity and SO2 concentration of each grid are iteratively calculated based on the activated carbon adsorption rate equation. The activated carbon adsorption capacity Q[0, j] of the top grid of the desulfurization tower is Q[0, j] = 0, and the SO2 concentration C[i, 0] of the grid at the flue gas inlet of the desulfurization tower is C0. That is,

[0098] Q[i,j]=Q[i-1,j]+dQ[i,j]...(2).

[0099] dt=(h / m) / v…(3).

[0100] C[i,j]=C[i,j-1]-dC[i,j]...(4).

[0101] Where: Q[i, j] represents the adsorption capacity of the activated carbon at the grid corresponding to the i-th grid in the height direction and the j-th grid in the width direction of the activated carbon bed, dQ[i, j] represents the newly adsorbed capacity of the activated carbon in the current grid. C[i, j] represents the SO2 concentration of the grid corresponding to the i-th grid in the height direction and the j-th grid in the width direction of the activated carbon bed, and dC[i, j] represents the reduction in SO2 concentration due to adsorption by the activated carbon in the current grid. Where i ≤ m, j ≤ n. dt represents the residence time of the activated carbon in the current grid. h represents the height of the activated carbon bed in the desulfurization tower. v represents the activated carbon feed rate at the corresponding position in the desulfurization tower. C0 represents the SO2 concentration at the flue gas inlet of the desulfurization tower.

[0102] 2) According to the direction of the flue gas, the activated carbon bed in the desulfurization tower is divided into the front chamber, middle chamber, and rear chamber. The model constants such as the thickness of the front chamber, middle chamber, and rear chamber of the desulfurization tower, the height and width of the activated carbon bed in the desulfurization tower are input. The SO2 concentration at the flue gas inlet of the desulfurization tower is set, and the desulfurization process of the activated carbon in each chamber is simulated.

[0103] The activated carbon feeding rate of the front chamber is V1, the activated carbon feeding rate of the middle chamber is V2, and the activated carbon feeding rate of the rear chamber is V3. Among them, V1:V2:V3=(5.5-6.5):(1.5-2.5):1.

[0104] 3) Obtain the activated carbon feeding rate in the front, middle and rear chambers of the desulfurization tower so that the SO2 concentration at the flue gas outlet of the desulfurization tower is within the set range, thereby optimizing the activated carbon circulation amount. Specifically:

[0105] The SO2 concentration at the flue gas inlet of the desulfurization tower is detected online. According to the proportional relationship between the activated carbon feeding speeds in the front, middle and rear chambers of the desulfurization tower, the activated carbon feeding speeds in the front, middle and rear chambers of the desulfurization tower are calculated by the activated carbon adsorption rate equation. The activated carbon feeding speeds in the front, middle and rear chambers of the desulfurization tower are adjusted so that the SO2 concentration at the flue gas outlet of the desulfurization tower is less than C 设 .

[0106] Where: C 设 It is the upper limit of SO2 concentration at the flue gas outlet of the desulfurization tower. 设 =35mg / Nm 3 .

[0107] Example 3

[0108] Repeat Example 2, except that the activated carbon feeding rates in the front, middle and rear chambers of the desulfurization tower are V1:V2:V3=(5.7-6.3):(1.8-2.2):1.

[0109] Example 4

[0110] like Figure 2 As shown, Example 2 is repeated, except that in step 3), the activated carbon feeding speed of the front, middle and rear chambers of the desulfurization tower is adjusted so that the SO2 concentration at the flue gas outlet of the desulfurization tower is less than C 设 Specifically:

[0111] 301) According to the SO2 concentration at the flue gas inlet of the desulfurization tower, combined with the proportional relationship between the activated carbon feeding speeds of the front, middle and rear chambers of the desulfurization tower, and the SO2 concentration at the flue gas outlet of the desulfurization tower is less than C 设 With this as the goal, the activated carbon feeding rates in the front, middle and rear chambers of the desulfurization tower were preliminarily optimized by calculating the activated carbon adsorption rate equation.

[0112] 302) Based on the calculated preliminary optimized activated carbon feeding speeds in the front, middle and rear chambers of the desulfurization tower, calculate the preliminary SO2 concentration C at the flue gas outlet of the desulfurization tower at the corresponding activated carbon feeding speeds. 初 Compare the initial SO2 concentration C 初 and SO2 concentration upper limit C 设 .

[0113] 302a) If the initial SO2 concentration C 初 <C 设 , record the current activated carbon feeding speed of each chamber, then slightly reduce the activated carbon feeding speed of the front, middle and rear chambers of the desulfurization tower that is initially optimized, calculate the adjusted SO2 concentration at the flue gas outlet of the desulfurization tower according to the activated carbon feeding speed of each chamber after adjustment, and compare the adjusted SO2 concentration with the upper limit of SO2 concentration C 设 Repeat this step until the calculated SO2 concentration at the flue gas outlet of the desulfurization tower is ≥C 设 At this time, the last recorded activated carbon feeding rate in each chamber is the optimal feeding rate, thereby determining the optimal circulation amount of activated carbon.

[0114] Example 5

[0115] like Figure 3 As shown, Example 4 is repeated, except that step 302) further includes:

[0116] 302b) If the initial SO2 concentration C 初 ≥C 设 , slightly increase the activated carbon feeding speed of the front, middle and rear chambers of the preliminary optimized desulfurization tower, then record the current activated carbon feeding speed of each chamber, calculate the adjusted SO2 concentration at the flue gas outlet of the desulfurization tower according to the activated carbon feeding speed of each chamber after adjustment, and compare the adjusted SO2 concentration with the upper limit of SO2 concentration C 设 Repeat this step until the calculated SO2 concentration at the flue gas outlet of the desulfurization tower is less than C 设 At this time, the last recorded activated carbon feeding rate in each chamber is the optimal feeding rate, thereby determining the optimal circulation amount of activated carbon.

[0117] Application Example 1

[0118] The method for optimizing the activated carbon circulation amount described in Example 5 was used to treat sintering flue gas from a steel smelter. In this method, the activated carbon adsorption rate equation is:

[0119]

[0120] The SO2 concentration in the sintering flue gas to be treated is 380ppm, the moisture content is 10%, and the oxygen content is 17%. Under these conditions, the reaction order of SO2 is calculated to be l=0.8, the correction term α=0.22, and K1=7.2h. -1 , K2=0.008h -1 .

[0121] Where: Q is the adsorption capacity of activated carbon, mg / g. t is the residence time of activated carbon in the desulfurization tower, h. α is the correction term, α = 0.22. C is the SO2 concentration in the flue gas, C = 380ppm ≈ 1085.7mg / m 3 . l is the reaction order of the SO2 elementary reaction to produce sulfuric acid, l = 0.8. Ea is the activation energy of activated carbon, Ea = 0.89 kJ / mol. R is the gas constant, R = 8.314 J / (mol·K). T is the flue gas temperature, T = 413 K. K1 is the adsorption rate of SO2 in the first stage of sulfuric acid accumulation process in the activated carbon adsorption rate curve, K1 = 7.2 h -1 K2 is the adsorption rate of SO2 in the third stage of sulfuric acid accumulation process in the activated carbon adsorption rate curve, K2 = 0.008h -1 Qs is the apparent saturated adsorption capacity of activated carbon for SO2, Qs = 71 mg / g.

[0122] In this embodiment, the thickness of the front chamber of the desulfurization tower is L1 = 0.16m, the thickness of the middle chamber is L2 = 0.72m, and the thickness of the rear chamber is L3 = 0.72mm. The height of the activated carbon bed in the desulfurization tower is H = 24m, and the width is W = 9m.

[0123] Under the above desulfurization tower structure, the SO2 concentration at the flue gas inlet of the desulfurization tower is divided into 10 intervals of 0-100ppm, 100-200ppm, ... 900-1000ppm, combined with the ratio of the activated carbon feeding speed of the front, middle and rear chambers of the desulfurization tower V1:V2:V3=6:2:1, and the SO2 concentration at the flue gas outlet of the desulfurization tower is less than C 设 (C 设 =35mg / Nm 3 ) as the goal, the activated carbon adsorption rate equation is used to calculate the initial optimized activated carbon feeding rate of each chamber within the corresponding inlet SO2 concentration range, and the optimized strategy table of activated carbon feeding rate is drawn. The strategy table is as follows:

[0124]

[0125] In this embodiment, the SO2 concentration C0=380ppm at the flue gas inlet of the desulfurization tower is detected online. According to the above-mentioned optimization strategy table of activated carbon feeding rate, the preliminary optimized activated carbon feeding rates of each chamber of the desulfurization tower are: V1=0.33m / h, V2=0.11m / h, V3=0.055m / h.

[0126] According to the calculated preliminary optimized activated carbon feeding rate of the front, middle and rear chambers of the desulfurization tower, the preliminary SO2 concentration C at the flue gas outlet of the desulfurization tower under the corresponding activated carbon feeding rate is calculated. 初 =26.85mg / m 3 Compare the initial SO2 concentration C初 and SO2 concentration upper limit C 设 , C 设 =35mg / Nm 3 .

[0127] Obviously, the initial SO2 concentration C 初 <C 设 , record the current activated carbon feeding speed V1, V2, V3 of each chamber, and then slightly reduce the activated carbon feeding speed of the front, middle and rear chambers of the desulfurization tower according to the proportional relationship of the feeding speed of each chamber, that is, V1, V2, V3 are reduced by 0.018m / h, 0.006m / h, and 0.003m / h respectively on the original basis; according to the activated carbon feeding speed of each chamber after adjustment, calculate the adjusted SO2 concentration at the flue gas outlet of the desulfurization tower, and compare the adjusted SO2 concentration with the upper limit of SO2 concentration C 设 Repeat this step until the calculated SO2 concentration at the flue gas outlet of the desulfurization tower is ≥C 设 At this time, the last recorded activated carbon feeding speed in each chamber V1′=0.474m / h, V2′=0.158m / h, V3′=0.079m / h is the optimal feeding speed, thereby determining the optimal circulation amount of activated carbon.

[0128] The optimal activated carbon circulation rate is to minimize the activated carbon feeding rate in the front, middle and rear chambers of the desulfurization tower under the premise that the SO2 concentration at the flue gas outlet of the desulfurization tower meets the control standard, so as to obtain the minimum activated carbon circulation rate, that is, to reduce the investment cost while ensuring the desulfurization efficiency.

Claims

1. A method for optimizing activated carbon circulation, the method comprising the following steps: 1) According to the activated carbon adsorption rate curve of the desulfurization tower, an activated carbon adsorption rate model is established; the activated carbon adsorption rate model is an activated carbon adsorption rate equation, and the activated carbon adsorption rate equation is: Where: Q is the adsorption capacity of activated carbon, mg / g; t is the residence time of activated carbon in the desulfurization tower, h; α is the correction term; C is the SO2 concentration in the flue gas, mg / m 3 ; l is the reaction order of SO2 elementary reaction to produce sulfuric acid; Ea is the activation energy of activated carbon, kJ / mol; R is the gas constant, J / (mol·K); T is the flue gas temperature, K; K1 is the adsorption rate of SO2 in the first stage of sulfuric acid accumulation process in the activated carbon adsorption rate curve, h -1 ; K2 is the adsorption rate of SO2 in the third stage of sulfuric acid accumulation process in the activated carbon adsorption rate curve, h -1 ; Qs is the apparent saturated adsorption capacity of activated carbon for SO2, mg / g; 2) According to the direction of flue gas, the activated carbon bed in the desulfurization tower is divided into front chamber, middle chamber and rear chamber. The activated carbon feeding rate of the front chamber is V1, the activated carbon feeding rate of the middle chamber is V2, and the activated carbon feeding rate of the rear chamber is V3; Among them, V1:V2:V3=(5.7-6.3):(1.8-2.2):1; input model constants, set the SO2 concentration at the flue gas inlet of the desulfurization tower, and simulate the desulfurization process of each activated carbon chamber; 3) Obtain the activated carbon feeding rate in the front, middle and rear chambers of the desulfurization tower so that the SO2 concentration at the flue gas outlet of the desulfurization tower is within the set range, thereby optimizing the activated carbon circulation amount.

2. The method according to claim 1, wherein: In step 1), establishing the activated carbon adsorption rate model specifically includes the following sub-steps: 101) According to the variation of SO2 concentration ratio at the inlet and outlet of the desulfurization tower over time, the rate of SO2 adsorption by activated carbon is divided into three stages: the first stage is a fast constant rate stage, the second stage is an exponential stage, and the third stage is a slow constant rate stage; 102) Draw an activated carbon adsorption rate curve based on the change of the amount of SO2 adsorbed by activated carbon over time during the desulfurization process; 103) Based on the characteristic that the rate of SO2 adsorption by activated carbon in sub-step 101) is constant in the first and third stages, combined with the activated carbon adsorption rate curve in sub-step 102), an activated carbon adsorption rate equation is constructed; 104) The activated carbon bed in the desulfurization tower is divided into grids, and the activated carbon adsorption rate equation in sub-step 103) is applied to each grid in turn according to the direction of the flue gas.

3. The method according to claim 2, wherein: Sub-step 104) is specifically as follows: the activated carbon bed in the desulfurization tower is divided into grids, with the height of the activated carbon bed divided into m grids and the width of the activated carbon bed divided into n grids, and the activated carbon adsorption rate equation is applied to each grid in turn, and the adsorption amount and SO2 concentration of each grid are iteratively calculated according to the activated carbon adsorption rate equation; wherein, the activated carbon adsorption amount Q[0, j] of the topmost grid of the desulfurization tower is Q[0, j]=0, and the SO2 concentration of the grid at the flue gas inlet of the desulfurization tower is C[i, 0]=C0; that is, Q[i,j]=Q[i-1,j]+dQ[i,j]...(2); dt=(h / m) / v…(3); C[i,j]=C[i,j-1]-dC[i,j]...(4); In the formula: Q[i, j] represents the adsorption amount of the grid corresponding to the i-th grid in the height direction and the j-th grid in the width direction of the activated carbon bed, dQ[i, j] represents the new adsorption amount of activated carbon in the current grid; C[i, j] represents the SO2 concentration of the grid corresponding to the i-th grid in the height direction and the j-th grid in the width direction of the activated carbon bed, dC[i, j] represents the reduction of SO2 concentration under the adsorption of activated carbon in the current grid; where i≤m, j≤n; dt represents the residence time of activated carbon in the current grid; h is the height of the activated carbon bed in the desulfurization tower; v is the activated carbon feeding rate at the corresponding position in the desulfurization tower; C0 is the SO2 concentration at the flue gas inlet of the desulfurization tower.

4. The method according to claim 3, wherein: In step 3), the SO2 concentration at the flue gas inlet of the desulfurization tower is detected online, and the activated carbon feeding speeds of the front, middle and rear chambers of the desulfurization tower are calculated by the activated carbon adsorption rate equation according to the proportional relationship between the activated carbon feeding speeds of the front, middle and rear chambers of the desulfurization tower; the activated carbon feeding speeds of the front, middle and rear chambers of the desulfurization tower are adjusted so that the SO2 concentration at the flue gas outlet of the desulfurization tower is less than C 设 ; Where: C 设 The upper limit of SO2 concentration at the flue gas outlet of the desulfurization tower; C 设 ≤35mg / Nm 3 .

5. The method according to claim 4, characterized in that: Adjust the activated carbon feeding speed in the front, middle and rear chambers of the desulfurization tower so that the SO2 concentration at the flue gas outlet of the desulfurization tower is less than C 设 ; Specifically: 301) According to the SO2 concentration at the flue gas inlet of the desulfurization tower, combined with the proportional relationship between the activated carbon feeding speeds of the front, middle and rear chambers of the desulfurization tower, and the SO2 concentration at the flue gas outlet of the desulfurization tower is less than C 设 As the goal, the activated carbon feeding rate in the front, middle and rear chambers of the desulfurization tower was preliminarily optimized by calculating the activated carbon adsorption rate equation; 302) Based on the calculated preliminary optimized activated carbon feeding speeds in the front, middle and rear chambers of the desulfurization tower, calculate the preliminary SO2 concentration C at the flue gas outlet of the desulfurization tower at the corresponding activated carbon feeding speeds. 初 ; Compare the preliminary SO2 concentration C 初 and SO2 concentration upper limit C 设 ; 302a) If the initial SO2 concentration C 初 <C 设 , record the current activated carbon feeding speed of each chamber, then slightly reduce the activated carbon feeding speed of the front, middle and rear chambers of the desulfurization tower that is initially optimized, calculate the adjusted SO2 concentration at the flue gas outlet of the desulfurization tower according to the activated carbon feeding speed of each chamber after adjustment, and compare the adjusted SO2 concentration with the upper limit of SO2 concentration C 设 Repeat this step until the calculated SO2 concentration at the flue gas outlet of the desulfurization tower is ≥C 设 At this time, the last recorded activated carbon feeding rate in each chamber is the optimal feeding rate, thereby determining the optimal circulation amount of activated carbon.

6. The method according to claim 5, characterized in that: Step 302) also includes: 302b) If the initial SO2 concentration C 初 ≥C 设 , slightly increase the activated carbon feeding speed of the front, middle and rear chambers of the preliminary optimized desulfurization tower, then record the current activated carbon feeding speed of each chamber, calculate the adjusted SO2 concentration at the flue gas outlet of the desulfurization tower according to the activated carbon feeding speed of each chamber after adjustment, and compare the adjusted SO2 concentration with the upper limit of SO2 concentration C 设 Repeat this step until the calculated SO2 concentration at the flue gas outlet of the desulfurization tower is less than C 设 At this time, the last recorded activated carbon feeding rate in each chamber is the optimal feeding rate, thereby determining the optimal circulation amount of activated carbon.

7. The method according to any one of claims 1 to 6, characterized in that: In step 2), the model constants include: the thickness of the front chamber, the thickness of the middle chamber, the thickness of the rear chamber of the desulfurization tower, and the height and width of the activated carbon bed in the desulfurization tower.

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