Method for optimizing thicknesses of front chamber, middle chamber and rear chamber of adsorption tower

Abstract

A method for optimizing the thicknesses of front, middle and rear chambers of an adsorption tower comprises the following steps: 1) establishing an activated carbon adsorption rate model; 2) dividing the adsorption tower into a front chamber, a middle chamber and a rear chamber, and performing desulfurization process simulation on activated carbon in each chamber; (3) setting the thickness of each chamber of the adsorption tower and the SO2 concentration at the flue gas inlet of the adsorption tower, and obtaining the activated carbon blanking speed of each chamber of the adsorption tower, so as to obtain the optimal circulation volume of the activated carbon and enable the SO2 concentration at the flue gas outlet of the adsorption tower to be within a set range; and (4) fixing the total thickness of the adsorption tower, and adjusting the thicknesses of the front, middle and rear chambers of the adsorption tower, so that the activated carbon circulation amount corresponding to the adjusted activated carbon discharging speed of each chamber of the adsorption tower is minimum, and the thicknesses of the front, middle and rear chambers of the adsorption tower are optimized. By establishing the activated carbon adsorption rate model, the optimal activated carbon circulation volume of the adsorption tower under the condition of different thicknesses of the front chamber, the middle chamber and the rear chamber is obtained, so that the minimum optimal activated carbon circulation volume is obtained, the thickness of each chamber of the adsorption tower is optimized, and the investment cost is reduced.

Description

Technical Field

[0001] The invention relates to controlling and adjusting the thickness of each chamber in an adsorption tower, and in particular to a method for optimizing the thickness of front, middle and rear chambers of an adsorption tower, and belongs to the technical field of activated carbon flue gas purification. Background Art

[0002] Activated carbon flue gas purification technology has the advantages of high efficiency in the coordinated purification of multiple pollutants, stable operation, and resource utilization of by-products. It has been widely used in the field of steel sintering flue gas purification. The activated carbon adsorption tower is divided into three channels: front, middle, and rear chambers. The activated carbon moves from top to bottom in each channel of the adsorption tower, and the flue gas passes vertically through the activated carbon bed. During production, the activated carbon feeding speed of each channel is controlled separately to achieve efficient coordinated removal of different pollutants. Generally speaking, the front layer has the smallest thickness, the middle layer is second, and the rear layer is the widest, or the existing technology also adopts a design in which the front layer has the smallest thickness and the middle and rear layers are of equal thickness. The coordinated treatment of multiple pollutants is achieved by adjusting the activated carbon feeding speed of the front, middle, and rear layers.

[0003] In the prior art, the structure of the adsorption tower is fixed, and the thickness of the front, middle and rear chambers is certain. In different projects, the efficient removal of pollutants is achieved only by adjusting the circulation volume of activated carbon, while the thickness of the front, middle and rear chambers of the adsorption tower has not been adaptively adjusted to the differences in sintering flue gas. For example, for components with high concentrations of SO2 and high flue gas volume, a wider tower body can be selected, and for components with low concentrations of SO2 and low flue gas volume, a narrow tower body can be selected to reduce investment costs. That is, for flue gas to be treated in different situations, an adsorption tower structure that is compatible with it can be selected, and the low-cost and efficient treatment of multiple pollutants can be further achieved by adjusting the thickness of the front, middle and rear chambers of the adsorption tower. Summary of the invention

[0004] In view of the deficiencies of the above-mentioned prior art, the present invention proposes a method for optimizing the thickness of the front, middle and rear chambers of the adsorption tower. Through experimental research, 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 adsorption tower and the activated carbon feeding speed of each chamber according to the characteristic law of activated carbon desulfurization, and based on the activated carbon desulfurization, denitrification and dust removal mechanism, on the premise of ensuring the desulfurization efficiency of the adsorption tower, obtains the optimal activated carbon feeding speed and the optimal activated carbon circulation amount of each chamber, and then obtains the optimal activated carbon circulation amount of the adsorption tower under different thickness conditions of the front, middle and rear chambers by adjusting the thickness of the front, middle and rear chambers of the adsorption tower, and thereby obtains the minimum optimal activated carbon circulation amount, thereby optimizing the thickness of the front, middle and rear chambers of the adsorption tower, and reducing the investment cost while guiding the operation of the project.

[0005] According to an embodiment of the present invention, a method for optimizing the thickness of the front, middle and rear chambers of an adsorption tower is provided.

[0006] A method for optimizing the thickness of the front, middle and rear chambers of an adsorption tower, the method comprising the following steps:

[0007] 1) Based on the variation pattern of the amount of SO2 adsorbed by activated carbon over time during the desulfurization process, an activated carbon adsorption rate model was established.

[0008] 2) The activated carbon bed of the adsorption tower is divided into front, middle and rear chambers according to the direction of the flue gas, and the desulfurization process of the activated carbon in each chamber is simulated.

[0009] 3) Input the model constants, set the thickness of the front, middle and rear chambers of the adsorption tower, and the SO2 concentration at the flue gas inlet of the adsorption tower, obtain the activated carbon feeding rate of the front, middle and rear chambers of the adsorption tower under the current conditions, and thus obtain the optimal circulation amount of activated carbon under the current conditions, so that the SO2 concentration at the flue gas outlet of the adsorption tower is within the set range.

[0010] 4) The total thickness of the activated carbon bed in the adsorption tower is fixed, and the thickness of the front, middle and rear chambers of the adsorption tower is adjusted so that the activated carbon circulation amount corresponding to the activated carbon feeding speed of the front, middle and rear chambers of the adsorption tower after adjustment is minimized, thereby optimizing the thickness of the front, middle and rear chambers of the adsorption tower.

[0011] In the present invention, the activated carbon adsorption rate model established in step 1) is specifically:

[0012] 101) Based on the variation of the amount of SO2 adsorbed by activated carbon over time during the desulfurization process, draw an activated carbon adsorption rate curve.

[0013] 102) Based on the variation pattern of SO2 concentration ratio between flue gas inlet and outlet of adsorption 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] 103) Based on the activated carbon adsorption rate curve and the characteristic that the adsorption rate of SO2 by activated carbon is constant in the first and third stages, an activated carbon adsorption rate equation is constructed.

[0015] In the present invention, in sub-step 103), the activated carbon adsorption rate equation is:

[0016]

[0017] In formula (1): Q is the adsorption capacity of activated carbon, mg / g. t is the residence time of activated carbon in the adsorption tower, h. α is the correction term. C is the SO2 concentration in the flue gas, mg / m 3l is the reaction order of the 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.

[0018] In the present invention, in step 2), the activated carbon bed of the adsorption tower is divided into a front chamber, a middle chamber, and a rear chamber, the thickness of the front chamber is L1, the thickness of the middle chamber is L2, and the thickness of the rear chamber is L3. Wherein, L1<L2≤L3.

[0019] In the present invention, 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, preferably V1:V2:V3=(5.7-6.3):(1.8-2.2):1.

[0020] In the present invention, in step 2), the desulfurization process is simulated for each chamber of activated carbon, specifically:

[0021] The adsorption tower is divided into grids, where the height of the adsorption tower is divided into m grids, and the width of the adsorption tower is divided into n grids. Based on the flue gas direction, the activated carbon adsorption rate equation is applied to each grid one by one. The adsorption amount and SO2 concentration of each grid are iteratively calculated according to the activated carbon adsorption rate equation. Among them, the activated carbon adsorption amount Q[0, j] of the top grid of the adsorption tower is 0, and the SO2 concentration C[i, 0] of the grid at the flue gas inlet of the adsorption 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] In the formula: Q[i, j] represents the adsorption amount of the grid corresponding to the position of the i-th grid in the height direction and the j-th grid in the width direction of the adsorption tower, and dQ[i, j] represents the newly added adsorption amount of activated carbon in the current grid. C[i, j] represents the SO2 concentration of the grid corresponding to the position of the i-th grid in the height direction and the j-th grid in the width direction of the adsorption tower, and dC[i, j] represents the reduced SO2 concentration under the adsorption of activated carbon in the current grid. Among them, i≤m, j≤n. dt represents the residence time of activated carbon in the current grid. h is the height of the adsorption tower. v is the activated carbon feeding speed at the corresponding position in the adsorption tower. C0 is the SO2 concentration at the flue gas inlet of the adsorption tower.

[0026] In the present invention, step 3) is specifically:

[0027] Input the model constants, set the initial thickness of the front, middle and rear chambers of the adsorption tower, detect the SO2 concentration at the flue gas inlet of the adsorption tower online, and calculate the activated carbon feeding speed of the front, middle and rear chambers of the adsorption tower through 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 adsorption tower. Adjust the activated carbon feeding speeds of the front, middle and rear chambers of the adsorption tower to obtain the optimal circulation amount of activated carbon under the corresponding conditions, while ensuring that the SO2 concentration at the flue gas outlet of the adsorption tower is within the set range.

[0028] In the present invention, the model constants include: the height, width and total thickness of the adsorption tower.

[0029] In the present invention, the activated carbon feeding speed of the front, middle and rear chambers of the adsorption tower is adjusted to obtain the optimal circulation amount of activated carbon under corresponding conditions, while satisfying that the SO2 concentration at the flue gas outlet of the adsorption 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 adsorption tower. 设 ≤35mg / Nm 3 .

[0030] In the present invention, the activated carbon feeding speed of the front, middle and rear chambers of the adsorption tower is adjusted to obtain the optimal circulation amount of activated carbon under corresponding conditions, while satisfying that the SO2 concentration at the flue gas outlet of the adsorption tower is less than C 设 Specifically:

[0031] 301) According to the SO2 concentration at the flue gas inlet of the adsorption tower, combined with the proportional relationship of the activated carbon feeding speed in the front, middle and rear chambers of the adsorption tower, and the SO2 concentration at the flue gas outlet of the adsorption 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 adsorption tower were preliminarily optimized by calculating the activated carbon adsorption rate equation.

[0032] 302) According to the calculated initial optimized activated carbon feeding speeds in the front, middle and rear chambers of the adsorption tower, calculate the initial SO2 concentration C at the flue gas outlet of the adsorption tower at the corresponding activated carbon feeding speed 初 . Compare the initial SO2 concentration C 初 and SO2 concentration upper limit C 设 .

[0033] 302a) If the initial SO2 concentration is 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 adsorption tower at this time, calculate the adjusted SO2 concentration at the flue gas outlet of the adsorption 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 adsorption tower is ≥ C 设 At this time, the last recorded activated carbon feeding rate in each chamber is the optimal feeding rate, so as to determine the optimal circulation amount of activated carbon and record it.

[0034] In the present invention, step 302) also includes:

[0035] 302b) If the initial SO2 concentration is C 初 ≥C 设 , slightly increase the activated carbon feeding speed of the front, middle and rear chambers of the adsorption tower at this time, and then record the current activated carbon feeding speed of each chamber. According to the activated carbon feeding speed of each chamber after adjustment, calculate the adjusted SO2 concentration at the flue gas outlet of the adsorption 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 adsorption tower is less than C 设 At this time, the last recorded activated carbon feeding rate in each chamber is the optimal feeding rate, so as to determine the optimal circulation amount of activated carbon and record it.

[0036] In the present invention, step 4) specifically includes:

[0037] 401) The total thickness of the adsorption tower is kept unchanged, and the thickness of the front chamber of the adsorption tower is slightly increased. At the same time, the thickness of the middle chamber and the thickness of the rear chamber are correspondingly reduced.

[0038] 402) Repeat step 3), calculate and record the activated carbon feeding rate and the corresponding optimal activated carbon circulation amount of the front, middle and rear chambers of the adjusted adsorption tower according to the thickness of each chamber of the adsorption tower after adjustment.

[0039] 403) Repeat sub-steps 401) and 402) until the thickness of the front chamber is greater than or equal to the thickness of the middle chamber, and then exit the loop.

[0040] 404) Find the recorded optimal activated carbon circulation amount, find out the minimum activated carbon circulation amount, and the thickness of the front, middle and rear chambers of the adsorption tower corresponding to the minimum activated carbon circulation amount is the optimized thickness of the front, middle and rear chambers.

[0041] In the prior art, the structure of the adsorption tower is fixed, and the thickness of the front, middle and rear chambers is often fixed. In different projects, the efficient removal of pollutants is achieved only by adjusting the circulation amount of activated carbon, while the thickness of the front, middle and rear chambers of the adsorption tower is not adaptively adjusted with the differences in sintering flue gas. Based on this, the present invention proposes a method for optimizing the thickness of the front, middle and rear chambers of the adsorption tower. In the scheme of the present invention, through the method of experimental research, according to the characteristic law of activated carbon desulfurization, the activated carbon adsorption rate equation of the relationship between the SO2 concentration at the flue gas outlet of the front, middle and rear chambers of the adsorption tower and the activated carbon feeding speed of each chamber is established, and based on the activated carbon desulfurization, denitrification and dust removal mechanism, under the premise of ensuring the desulfurization efficiency of the adsorption tower, the optimal activated carbon feeding speed of each chamber is obtained, and then by adjusting the thickness of the front, middle and rear chambers of the adsorption tower, the optimal circulation amount of activated carbon under the conditions of different thicknesses of the front, middle and rear chambers of the adsorption tower is obtained, and the minimum optimal circulation amount of activated carbon is obtained, so as to optimize the thickness of the front, middle and rear chambers of the adsorption tower, and reduce the investment cost while guiding the operation of the project.

[0042] By adopting the method of optimizing the thickness of the front, middle and rear chambers of the adsorption tower described in the present application, an adsorption tower structure suitable for the flue gas to be treated in different situations can be selected, and low-cost and efficient treatment of multiple pollutants can be further achieved by adjusting the thickness of the front, middle and rear chambers of the adsorption tower.

[0043] The method for optimizing the thickness of the front, middle and rear chambers of the adsorption tower according to the present invention mainly comprises the following steps:

[0044] 1) Based on the variation pattern of the amount of SO2 adsorbed by activated carbon over time during the desulfurization process, an activated carbon adsorption rate model was established.

[0045] 101) Based on the variation of the amount of SO2 adsorbed by activated carbon over time during the desulfurization process, draw an activated carbon adsorption rate curve.

[0046] 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 8As shown in the figure, in the initial stage, the SO2 concentration in the flue gas is high, the pore structure of the activated carbon is well developed, and the rate of SO2 adsorption by the activated carbon is maintained at a fast average value. At the end of the reaction, due to the adsorption of the activated carbon, the SO2 concentration in the flue gas decreases. After the activated carbon adsorbs part of the SO2, the pores are blocked, and the adsorption rate slows down, basically maintaining a relatively slow average value. From the activated carbon adsorption rate curve, it can be seen that as the adsorption time increases, the amount of SO2 adsorbed by the activated carbon gradually increases, and the adsorption amount increases slowly after a long time.

[0047] 102) Figure 6 As shown, based on the variation pattern of SO2 concentration ratio at flue gas inlet and outlet of the adsorption tower over time, activated carbon desulfurization, i.e. 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.

[0048] like Figure 7 As shown in the figure, according to the variation pattern of SO2 concentration at the flue gas outlet of the adsorption tower over time, it can be seen that with the extension of time, 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 slowly.

[0049] 103) Based on the activated carbon adsorption rate curve and the characteristics that the rate of activated carbon adsorption of SO2 is constant in the first and third stages, the activated carbon adsorption rate equation is constructed:

[0050]

[0051] In formula (1): Q is the adsorption capacity of activated carbon, mg / g. t is the residence time of activated carbon in the adsorption 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 the 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.

[0052] 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 .

[0053] 2) The activated carbon bed of the adsorption tower is divided into front, middle and rear chambers according to the direction of the flue gas, and the desulfurization process of the activated carbon in each chamber is simulated.

[0054] The present application divides the activated carbon bed in the adsorption tower into three layers, namely the front, middle and rear chambers. Among them, the thickness of the front chamber is L1, the thickness of the middle chamber is L2, and the thickness of the rear chamber is L3. 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. Taking into account various factors such as the uniformity of feeding and operation safety of the activated carbon in each chamber of the entire adsorption tower, the thickness relationship between the activated carbon in each chamber is L1<L2≤L3. According to laboratory research and engineering practice experience, under the structure of the thickness, height, width and other properties of the activated carbon bed in each chamber of the adsorption tower, the activated carbon feeding speeds in 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

[0055] The desulfurization process of each activated carbon chamber is simulated as follows:

[0056] The adsorption tower is divided into grids. The grid division described here can be understood as establishing a coordinate system on the activated carbon bed of the adsorption tower. The height and width of the activated carbon bed in the adsorption tower are divided into grids respectively. Then, according to the direction of the flue gas, the activated carbon adsorption rate equation is applied to each grid in turn, so that the adsorption amount of each grid, SO2 concentration, etc. can be iteratively calculated by software or computer program according to the equation.

[0057] Specifically, the height of the adsorption tower is divided into m grids, and the width of the adsorption tower is divided into n grids. Based on the direction of the flue gas, the activated carbon adsorption rate equation is applied to each grid one by one, and the adsorption amount and SO2 concentration of each grid are iteratively calculated according to the activated carbon adsorption rate equation. That is,

[0058] Q[i,j]=Q[i-1,j]+dQ[i,j]...(2).

[0059] dt=(h / m) / v…(3).

[0060] C[i,j]=C[i,j-1]-dC[i,j]...(4).

[0061] It is known that the activated carbon adsorption capacity Q[0, j] = 0 of the topmost grid of the adsorption tower, and the adsorption capacity of activated carbon in any grid and the newly added adsorption capacity in the current grid can be obtained by iteratively calculating each grid from top to bottom using formula (2). It is known that the SO2 concentration C[i, 0] = C0 of the grid at the flue gas inlet of the adsorption tower, and the outlet SO2 concentration of any grid can be obtained by iteratively calculating each grid from the flue gas inlet to the flue gas outlet of the adsorption tower using formula (4).

[0062] In formulas (2)-(4): Q[i, j] represents the adsorption amount of the grid corresponding to the position of the i-th grid in the direction of the adsorption tower and the j-th grid in the width direction, and dQ[i, j] represents the newly added adsorption amount of activated carbon in the current grid. C[i, j] represents the SO2 concentration of the grid corresponding to the position of the i-th grid in the height direction of the adsorption tower and the j-th grid in the width direction, and dC[i, j] represents the reduced SO2 concentration under the adsorption of activated carbon in the current grid. dC[i, j] can be converted by dQ[i, j]. Among them, i≤m, j≤n. dt represents the residence time of activated carbon in the current grid. h is the height of the adsorption tower. v is the activated carbon feeding speed at the corresponding position in the adsorption tower. C0 is the SO2 concentration at the flue gas inlet of the adsorption tower.

[0063] When the present invention performs fitting calculations through the above activated carbon adsorption rate equation (1), the activated carbon bed in the adsorption tower is divided into multiple grids, and each grid is iteratively calculated in turn through software or computer programs. At this time, dQ can be understood as the newly added adsorption amount of activated carbon in the current grid, and dt can be understood as the residence time of activated carbon in the current grid. The division of the grid has completed the spatial positioning of different positions in the adsorption tower, and formula (3) shows that the residence time of activated carbon in the corresponding grid is related to the feeding speed of activated carbon at the corresponding position. Therefore, through the residence time of activated carbon in the corresponding grid and the division of the grid, the iterative calculation between each grid, that is, the relationship between the parameters in the above equation (1) and the structural data of the adsorption tower (including the height, width, total thickness, thickness of each layer, etc. of the adsorption tower) and the feeding speed of each layer of activated carbon is reflected.

[0064] For any grid in the activated carbon bed, as long as the inlet parameters such as SO2 concentration at the flue gas inlet of the adsorption tower, flue gas temperature, and activated carbon feeding rate in the front chamber are given, the outlet parameters of the first grid can be calculated through the above activated carbon adsorption rate equation (1). At the same time, the outlet parameters of this grid become the inlet parameters of the next grid. Then, the outlet parameters of any grid can be obtained by iterative calculation through software or computer program. In the present invention, the activated carbon feeding rate of the front, middle and rear chambers is an unknown quantity and a parameter that needs to be obtained and optimized. At this time, based on the direction of the flue gas, when the upper limit of the SO2 concentration at the flue gas outlet of the adsorption tower is known (i.e., the outlet parameter of the last grid), and based on experience, the ratio of the activated carbon feeding rates of the front, middle and rear chambers is set, and the aforementioned calculation process for obtaining the outlet parameters of any grid is reversed, that is, the activated carbon feeding rate of each chamber can be calculated, and optimized to obtain the optimal circulation amount of activated carbon; then, by adjusting the thickness of the front, middle and rear chambers of the adsorption tower, the optimal circulation amount of activated carbon under the conditions of different thicknesses of the front, middle and rear chambers of the adsorption tower is obtained, and the minimum optimal circulation amount of activated carbon is obtained, thereby optimizing the thickness of the front, middle and rear chambers of the adsorption tower, and reducing the investment cost while guiding the operation of the project.

[0065] It should be noted that all formulas in the present invention are obtained by fitting by the inventor based on experiments and engineering applications, and all calculations are numerical values ​​converted according to prescribed units, and are obtained by substituting the numerical values ​​after conversion into the formulas (after conversion of 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).

[0066] 3) Input the model constants, set the thickness of the front, middle and rear chambers of the adsorption tower, and the SO2 concentration at the flue gas inlet of the adsorption tower, obtain the activated carbon feeding rate of the front, middle and rear chambers of the adsorption tower under the current conditions, and thus obtain the optimal circulation amount of activated carbon under the current conditions, so that the SO2 concentration at the flue gas outlet of the adsorption tower is within the set range.

[0067] The model constants described here include, for example, the height, width and total thickness of the adsorption tower, etc. The subsequent desulfurization simulation and related parameter calculations for each layer of activated carbon are all performed based on the input model constants.

[0068] Set the initial thickness of the front, middle and rear chambers of the adsorption tower, detect the SO2 concentration at the flue gas inlet of the adsorption tower online, combine the proportional relationship between the activated carbon feeding speeds in the front, middle and rear chambers of the adsorption tower, and iteratively calculate the activated carbon feeding speeds in the front, middle and rear chambers of the adsorption tower through software or computer programs according to the activated carbon adsorption rate equation. Adjust the activated carbon feeding speeds in the front, middle and rear chambers of the adsorption tower to obtain the optimal circulation amount of activated carbon under the corresponding conditions, while satisfying that the SO2 concentration at the flue gas outlet of the adsorption 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 adsorption tower. 设 ≤35mg / Nm 3 .

[0069] 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 adsorption 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 adsorption 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 adsorption tower, and make the SO2 concentration at the flue gas outlet of the adsorption 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.

[0070] Among them, the activated carbon feeding speed in the front, middle and rear chambers of the adsorption tower is adjusted to obtain the optimal circulation amount of activated carbon under the corresponding conditions, while satisfying that the SO2 concentration at the flue gas outlet of the adsorption tower is less than C 设 Specifically:

[0071] 301) According to the SO2 concentration at the flue gas inlet of the adsorption tower, combined with the proportional relationship of the activated carbon feeding speed in the front, middle and rear chambers of the adsorption tower, and the SO2 concentration at the flue gas outlet of the adsorption 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 adsorption tower were preliminarily optimized by calculating the activated carbon adsorption rate equation.

[0072] 302) According to the calculated initial optimized activated carbon feeding speeds in the front, middle and rear chambers of the adsorption tower, calculate the initial SO2 concentration C at the flue gas outlet of the adsorption tower at the corresponding activated carbon feeding speed 初 . Compare the initial SO2 concentration C 初 and SO2 concentration upper limit C 设 .

[0073] 302a) If the initial SO2 concentration is 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 adsorption tower at this time, calculate the adjusted SO2 concentration at the flue gas outlet of the adsorption 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 adsorption tower is ≥ C 设 At this time, the last recorded activated carbon feeding rate in each chamber is the optimal feeding rate, so as to determine the optimal circulation amount of activated carbon and record it.

[0074] 302b) If the initial SO2 concentration is C初 ≥C 设 , slightly increase the activated carbon feeding speed of the front, middle and rear chambers of the adsorption tower at this time, and then record the current activated carbon feeding speed of each chamber. According to the activated carbon feeding speed of each chamber after adjustment, calculate the adjusted SO2 concentration at the flue gas outlet of the adsorption 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 adsorption tower is less than C 设 At this time, the last recorded activated carbon feeding rate in each chamber is the optimal feeding rate, so as to determine the optimal circulation amount of activated carbon and record it.

[0075] The activated carbon feeding speed of each chamber calculated in the above step 301) is the preliminary optimization result of the premise of ensuring the desulfurization efficiency of the adsorption tower. Generally speaking, under the condition that the total concentration of pollutants at the flue gas inlet of the adsorption tower is kept constant, the smaller the SO2 concentration at the flue gas outlet of the adsorption tower, the greater the required activated carbon circulation amount. Therefore, the activated carbon feeding speed of each chamber calculated in the above steps 302a) and 302b) is the optimal activated carbon feeding speed obtained by reducing the activated carbon feeding speed of the front, middle and rear chambers as much as possible under the condition of ensuring the desulfurization efficiency of the adsorption tower, so as to obtain the best activated carbon circulation amount.

[0076] Among them, the activated carbon feeding speed of the front, middle and rear chambers of the adsorption tower that is initially optimized is slightly adjusted (reduced or increased). The slight adjustment mentioned here refers to fine-tuning the activated carbon feeding speed of each chamber currently calculated 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 this slight adjustment to the activated carbon feeding speed of each chamber that is initially 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.

[0077] It should be noted that the activated carbon feeding speed of the front, middle and rear chambers of the adsorption tower obtained in the preliminary optimization in step 301) is based on the SO2 concentration at the flue gas outlet of the adsorption tower being less than C 设 The target is calculated, but the present invention is based on the characteristic law of activated carbon desulfurization to simulate the desulfurization process of the adsorption tower. Therefore, although it is the result calculated under this premise, the preliminary SO2 concentration C in step 302b) may still appear. 初 ≥C 设The setting of step 302b) is, on the one hand, to obtain the optimal activated carbon feeding speed, that is, to obtain the optimal activated carbon circulation amount, and on the other hand, it also reflects the rigor of the experimental research of this application.

[0078] 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 adsorption 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 adsorption 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 a good fitting effect, and can truly optimize the activated carbon circulation amount, provide guidance for the operation of actual projects, and safeguard them.

[0079] 4) The total thickness of the activated carbon bed in the adsorption tower is fixed, and the thickness of the front, middle and rear chambers of the adsorption tower is adjusted so that the activated carbon circulation amount corresponding to the activated carbon feeding speed of the front, middle and rear chambers of the adsorption tower after adjustment is minimized, thereby optimizing the thickness of the front, middle and rear chambers of the adsorption tower.

[0080] According to the description in step 3), it can be obtained that under certain parameters such as the thickness of the front chamber, the thickness of the middle chamber, the thickness of the rear chamber, the width of the adsorption tower, the height of the adsorption tower, and the SO2 concentration at the flue gas inlet, the SO2 concentration at the flue gas outlet is less than C 设 The optimal feed rate and optimal activated carbon circulation volume of each chamber are obtained. Therefore, when the total thickness of the adsorption tower remains unchanged, the optimal activated carbon circulation volume under the corresponding thickness conditions can be obtained by changing the thickness of the front, middle and rear chambers of the activated carbon. The specific adjustments are as follows:

[0081] 401) The total thickness of the adsorption tower is kept unchanged, and the thickness of the front chamber of the adsorption tower is slightly increased. At the same time, the thickness of the middle chamber and the thickness of the rear chamber are correspondingly reduced.

[0082] 402) Repeat step 3), calculate and record the activated carbon feeding rate and the corresponding optimal activated carbon circulation amount of the front, middle and rear chambers of the adjusted adsorption tower according to the thickness of each chamber of the adsorption tower after adjustment.

[0083] 403) Repeat sub-steps 401) and 402) until the thickness of the front chamber is greater than or equal to the thickness of the middle chamber, and then exit the loop.

[0084] Taking into account factors such as uniformity of activated carbon feeding and operational safety in each chamber of the entire adsorption tower, the thickness relationship between activated carbon in each chamber generally satisfies L1<L2≤L3. Therefore, when the thickness of each chamber of the adsorption tower is adjusted slightly, when the current chamber thickness L1 is greater than or equal to L2, this cycle adjustment step is exited.

[0085] 404) Find the recorded optimal activated carbon circulation amount, find out the minimum activated carbon circulation amount, and the thickness of the front, middle and rear chambers of the adsorption tower corresponding to the minimum activated carbon circulation amount is the optimized thickness of the front, middle and rear chambers.

[0086] The small adjustment (increase or decrease) described in the above step 401) refers to fine-tuning the initial (or currently obtained) thickness of the front, middle and rear chambers of the adsorption tower with a certain smaller amplitude. The adjustment amplitude is not limited and can be selected in combination with actual engineering needs. For example, the thickness of the front chamber can be gradually increased by 0.05m, and correspondingly, the thickness of the middle chamber can be gradually reduced by 0.025m and the thickness of the rear chamber can be reduced by 0.025m. By gradually (or cyclically) adjusting the initial thickness of the front, middle and rear chambers of the adsorption tower, the optimal feeding rate and the optimal activated carbon circulation amount of each chamber that meet the desulfurization standard under different thickness conditions can be obtained in this process, and the minimum activated carbon circulation amount and the corresponding thickness design of the front, middle and rear chambers of the adsorption tower can be found from multiple optimal activated carbon circulation amounts, thereby optimizing the thickness of each chamber of the adsorption tower and minimizing the investment cost while ensuring the desulfurization efficiency of the adsorption tower.

[0087] Compared with the prior art, the present invention has the following beneficial technical effects:

[0088] 1. The present invention constructs an activated carbon adsorption rate equation combined with a simulation research method of actual engineering parameters to obtain the optimal circulation amount of activated carbon under different thickness conditions of the front, middle and rear chambers of the adsorption tower, and thereby obtains the minimum optimal circulation amount of activated carbon, thereby optimizing the thickness of the front, middle and rear chambers of the adsorption tower, and minimizing the investment cost while ensuring the desulfurization efficiency of the adsorption tower.

[0089] 2. According to the characteristic law of activated carbon desulfurization, the present invention establishes an activated carbon adsorption rate equation that represents the relationship between the SO2 concentration at the flue gas outlet of the front, middle and rear chambers of the adsorption tower and the activated carbon feeding rate of each chamber. Based on the mechanism of activated carbon desulfurization, denitrification and dust removal, while ensuring the desulfurization efficiency of the adsorption tower, the activated carbon feeding rates of the front, middle and rear chambers at different SO2 concentrations at the flue gas inlet of the adsorption tower are obtained, thereby optimizing the activated carbon circulation amount.

[0090] 3. The present invention also makes a small adjustment to the activated carbon feeding speed of each chamber that has been initially optimized. Under the premise of ensuring the desulfurization efficiency of the adsorption tower, the activated carbon feeding speed of the front, middle and rear chambers is reduced as much as possible to obtain the optimal activated carbon feeding speed, and then the best activated carbon circulation amount is obtained, thereby achieving further optimization of the activated carbon circulation amount, that is, reducing the investment cost while ensuring the desulfurization efficiency.

[0091] 4. The deviation between the predicted value calculated by the activated carbon adsorption rate equation and the actual value is small, 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 then optimize the thickness of each chamber of the adsorption tower, providing guidance for the operation of the actual project and safeguarding it. BRIEF DESCRIPTION OF THE DRAWINGS

[0092] Figure 1 A schematic diagram of a method for optimizing the thickness of the front, middle and rear chambers of an adsorption tower according to the present invention;

[0093] Figure 2 The process for determining the optimal circulation amount of activated carbon under corresponding parameter conditions in the present invention Figure 1 ;

[0094] Figure 3 The process for determining the optimal circulation amount of activated carbon under corresponding parameter conditions in the present invention Figure 2 ;

[0095] Figure 4 A flow chart of a method for optimizing the thickness of the front, middle and rear chambers of an adsorption tower according to the present invention;

[0096] Figure 5 It is the structural schematic diagram of the adsorption tower;

[0097] Figure 6 This is the variation of SO2 concentration ratio at the inlet and outlet of the adsorption tower over time;

[0098] Figure 7 This is the graph showing the change of SO2 concentration at the flue gas outlet of the adsorption tower over time;

[0099] Figure 8 This is a graph showing how the amount of SO2 adsorbed by activated carbon changes over time. DETAILED DESCRIPTION

[0100] The technical solution of the present invention is illustrated below by way of example, and the scope of protection requested by the present invention includes but is not limited to the following embodiments.

[0101] Example 1

[0102] A method for optimizing the thickness of the front, middle and rear chambers of an adsorption tower, the method comprising the following steps:

[0103] 1) Based on the variation pattern of the amount of SO2 adsorbed by activated carbon over time during the desulfurization process, an activated carbon adsorption rate model was established.

[0104] 2) The activated carbon bed of the adsorption tower is divided into front, middle and rear chambers according to the direction of the flue gas, and the desulfurization process of the activated carbon in each chamber is simulated.

[0105] 3) Input the model constants, set the thickness of the front, middle and rear chambers of the adsorption tower, and the SO2 concentration at the flue gas inlet of the adsorption tower, obtain the activated carbon feeding rate of the front, middle and rear chambers of the adsorption tower under the current conditions, and thus obtain the optimal circulation amount of activated carbon under the current conditions, so that the SO2 concentration at the flue gas outlet of the adsorption tower is within the set range.

[0106] 4) The total thickness of the activated carbon bed in the adsorption tower is fixed, and the thickness of the front, middle and rear chambers of the adsorption tower is adjusted so that the activated carbon circulation amount corresponding to the activated carbon feeding speed of the front, middle and rear chambers of the adsorption tower after adjustment is minimized, thereby optimizing the thickness of the front, middle and rear chambers of the adsorption tower.

[0107] Example 2

[0108] like Figure 1 As shown, a method for optimizing the thickness of the front, middle and rear chambers of an adsorption tower comprises the following steps:

[0109] 1) Based on the variation of the amount of SO2 adsorbed by activated carbon over time during the desulfurization process, an activated carbon adsorption rate model is established. Specifically:

[0110] 101) Figure 8 As shown, based on the variation pattern of the amount of SO2 adsorbed by activated carbon over time during the desulfurization process, an activated carbon adsorption rate curve is drawn.

[0111] 102) Figure 6 As shown, based on the variation pattern of SO2 concentration ratio at flue gas inlet and outlet of the adsorption 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.

[0112] 103) Based on the activated carbon adsorption rate curve and the characteristics that the rate of activated carbon adsorption of SO2 is constant in the first and third stages, the activated carbon adsorption rate equation is constructed:

[0113]

[0114] Where: Q is the adsorption capacity of activated carbon, mg / g. t is the residence time of activated carbon in the adsorption 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 the 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 -1Qs is the apparent saturated adsorption capacity of activated carbon for SO2, mg / g.

[0115] 2) The activated carbon bed of the adsorption tower is divided into front, middle and rear chambers according to the direction of the flue gas, wherein the thickness of the front chamber is L1, the thickness of the middle chamber is L2, and the thickness of the rear chamber is L3, L1<L2≤L3. 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, V1:V2:V3=(5.5-6.5):(1.5-2.5):1. The desulfurization process of the activated carbon in each chamber is simulated, specifically:

[0116] The adsorption tower is divided into grids, where the height of the adsorption tower is divided into m grids, and the width of the adsorption tower is divided into n grids. Based on the flue gas direction, the activated carbon adsorption rate equation is applied to each grid one by one. The adsorption amount and SO2 concentration of each grid are iteratively calculated according to the activated carbon adsorption rate equation. Among them, the activated carbon adsorption amount Q[0, j] of the top grid of the adsorption tower is 0, and the SO2 concentration C[i, 0] of the grid at the flue gas inlet of the adsorption tower is C0. That is:

[0117] Q[i,j]=Q[i-1,j]+dQ[i,j]...(2).

[0118] dt=(h / m) / v…(3).

[0119] C[i,j]=C[i,j-1]-dC[i,j]...(4).

[0120] In the formula: Q[i, j] represents the adsorption amount of the grid corresponding to the position of the i-th grid in the height direction and the j-th grid in the width direction of the adsorption tower, and dQ[i, j] represents the newly added adsorption amount of activated carbon in the current grid. C[i, j] represents the SO2 concentration of the grid corresponding to the position of the i-th grid in the height direction and the j-th grid in the width direction of the adsorption tower, and dC[i, j] represents the reduced SO2 concentration under the adsorption of activated carbon in the current grid. Among them, i≤m, j≤n. dt represents the residence time of activated carbon in the current grid. h is the height of the adsorption tower. v is the activated carbon feeding speed at the corresponding position in the adsorption tower. C0 is the SO2 concentration at the flue gas inlet of the adsorption tower.

[0121] 3) Input the model constants such as the height, width and total thickness of the adsorption tower, set the initial thickness of the front, middle and rear chambers of the adsorption tower, detect the SO2 concentration at the flue gas inlet of the adsorption tower online, and calculate the activated carbon feeding speed of the front, middle and rear chambers of the adsorption tower through 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 adsorption tower. Adjust the activated carbon feeding speeds of the front, middle and rear chambers of the adsorption tower to obtain the optimal circulation amount of activated carbon under the corresponding conditions, while satisfying that the SO2 concentration at the flue gas outlet of the adsorption tower is less than C 设 .

[0122] Where: C 设 It is the upper limit of SO2 concentration at the flue gas outlet of the adsorption tower. 设 =35mg / Nm 3 .

[0123] 4) The total thickness of the activated carbon bed in the adsorption tower is fixed, and the thickness of the front, middle and rear chambers of the adsorption tower is adjusted so that the activated carbon circulation amount corresponding to the activated carbon feeding speed of the front, middle and rear chambers of the adsorption tower after adjustment is minimized, thereby optimizing the thickness of the front, middle and rear chambers of the adsorption tower.

[0124] Example 3

[0125] Example 2 was repeated, except that the activated carbon feed rates in the front, middle and rear chambers of the adsorption tower were V1:V2:V3=(5.7-6.3):(1.8-2.2):1.

[0126] Example 4

[0127] 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 adsorption tower is adjusted to obtain the optimal circulation amount of activated carbon under the corresponding conditions, while satisfying that the SO2 concentration at the flue gas outlet of the adsorption tower is less than C 设 .

[0128] Specifically:

[0129] 301) According to the SO2 concentration at the flue gas inlet of the adsorption tower, combined with the proportional relationship of the activated carbon feeding speed in the front, middle and rear chambers of the adsorption tower, and the SO2 concentration at the flue gas outlet of the adsorption 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 adsorption tower were preliminarily optimized by calculating the activated carbon adsorption rate equation.

[0130] 302) According to the calculated initial optimized activated carbon feeding speeds in the front, middle and rear chambers of the adsorption tower, calculate the initial SO2 concentration C at the flue gas outlet of the adsorption tower at the corresponding activated carbon feeding speed 初 . Compare the initial SO2 concentration C 初 and SO2 concentration upper limit C 设 .

[0131] 302a) If the initial SO2 concentration is 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 adsorption tower at this time, calculate the adjusted SO2 concentration at the flue gas outlet of the adsorption 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 adsorption tower is ≥ C 设 At this time, the last recorded activated carbon feeding rate in each chamber is the optimal feeding rate, so as to determine the optimal circulation amount of activated carbon and record it.

[0132] Example 5

[0133] like Figure 3 As shown, Example 4 is repeated, except that step 302) further includes:

[0134] 302b) If the initial SO2 concentration is C 初 ≥C 设 , slightly increase the activated carbon feeding speed of the front, middle and rear chambers of the adsorption tower at this time, and then record the current activated carbon feeding speed of each chamber. According to the activated carbon feeding speed of each chamber after adjustment, calculate the adjusted SO2 concentration at the flue gas outlet of the adsorption 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 adsorption tower is less than C 设 At this time, the last recorded activated carbon feeding rate in each chamber is the optimal feeding rate, so as to determine the optimal circulation amount of activated carbon and record it.

[0135] Example 6

[0136] like Figure 4 As shown, Example 5 is repeated, except that step 4) specifically includes:

[0137] 401) The total thickness of the adsorption tower is kept unchanged, and the thickness of the front chamber of the adsorption tower is slightly increased. At the same time, the thickness of the middle chamber and the thickness of the rear chamber are correspondingly reduced.

[0138] 402) Repeat step 3), calculate and record the activated carbon feeding rate and the corresponding optimal activated carbon circulation amount of the front, middle and rear chambers of the adjusted adsorption tower according to the thickness of each chamber of the adsorption tower after adjustment.

[0139] 403) Repeat sub-steps 401) and 402) until the thickness of the front chamber is greater than or equal to the thickness of the middle chamber, and then exit the loop.

[0140] 404) Find the recorded optimal activated carbon circulation amount, find out the minimum activated carbon circulation amount, and the thickness of the front, middle and rear chambers of the adsorption tower corresponding to the minimum activated carbon circulation amount is the optimized thickness of the front, middle and rear chambers.

[0141] Application Example 1

[0142] The method for optimizing the thickness of the front, middle and rear chambers of the adsorption tower described in Example 6 was used to treat the sintering flue gas of a steel smelter. In this method, the activated carbon adsorption rate equation is:

[0143]

[0144] The SO2 concentration in the sintering flue gas to be treated is 380ppm, the moisture content is 12%, and the oxygen content is 15%. Under this condition, 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 .

[0145] Where: Q is the adsorption capacity of activated carbon, mg / g. t is the residence time of activated carbon in the adsorption 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.

[0146] In this embodiment, the total thickness of the adsorption tower is L=1.6 m, the height is H=24 m, and the width is W=1.6 m.

[0147] The initial thickness of the front, middle and rear chambers of the adsorption tower is set to L1 = 0.1m, L2 = 0.75m, and L3 = 0.75m. The SO2 concentration at the flue gas inlet of the adsorption tower is detected online. C0 = 380ppm. According to the ratio of the activated carbon feeding speed of the front, middle and rear chambers of the adsorption tower V1: V2: V3 = 6: 2: 1, and the SO2 concentration at the flue gas outlet of the adsorption tower is less than C 设 (C 设 =35mg / Nm 3 ) as the target, the activated carbon adsorption rate equation was used to calculate and adjust the activated carbon feeding speeds in the front, middle and rear chambers of the adsorption tower, V1 = 0.545m / h, V2 = 0.182m / h, V3 = 0.091m / h, so as to obtain the optimal activated carbon circulation amount S = 2.333m under the corresponding conditions. 3 / h and record.

[0148] Keep the total thickness of the adsorption tower unchanged, increase the thickness of the front chamber of the adsorption tower slightly, and at the same time, reduce the thickness of the middle chamber and the rear chamber accordingly, that is, increase the thickness of L1 by 0.05m on the original basis, and reduce the thickness of L2 and L3 by 0.025m on the original basis, and then calculate and record the activated carbon feeding speed and the corresponding optimal circulation amount of activated carbon in the front, middle and rear chambers of the adsorption tower according to the thickness of each chamber of the adsorption tower after adjustment. Considering the uniformity of activated carbon feeding in the adsorption tower and the safety of system operation, as well as not affecting the desulfurization, denitrification and dust removal functions of the adsorption tower, the thickness of each chamber in the adsorption tower must meet L1<L2≤L3. Therefore, repeat the aforementioned steps of adjusting the thickness of each chamber and calculating the corresponding optimal circulation amount of activated carbon until L1≥L2, and exit the cycle.

[0149] Application Example 2

[0150] Example 1 was repeated, except that in this example, the SO2 concentration C0 at the flue gas inlet of the adsorption tower was 680 ppm.

[0151] Similarly, according to the ratio of activated carbon feeding speed in the front, middle and rear chambers of the adsorption tower V1:V2:V3 = 6:2:1, and the SO2 concentration at the flue gas outlet of the adsorption tower is less than C 设 (C 设 =35mg / Nm 3 ) as the target, the activated carbon adsorption rate equation was used to calculate and adjust the activated carbon feeding speeds in the front, middle and rear chambers of the adsorption tower, V1 = 1.257m / h, V2 = 0.418m / h, V3 = 0.209m / h, so as to obtain the optimal activated carbon circulation amount S = 5.364m under the corresponding conditions. 3 / h and record.

[0152] Keep the total thickness of the adsorption tower unchanged, slightly increase the thickness of the front chamber of the adsorption tower, and at the same time, reduce the thickness of the middle chamber and the rear chamber accordingly, that is, increase the thickness of L1 by 0.05m on the original basis, and reduce the thickness of L2 and L3 by 0.025m on the original basis, and then calculate and record the activated carbon feeding speed of the front, middle and rear chambers of the adsorption tower and the corresponding optimal circulation amount of activated carbon according to the thickness of each chamber of the adsorption tower after adjustment. Repeat this step until L1 ≥ L2, and exit the cycle.

[0153] Calculate and record the relevant data in Application Example 1-2, the results are as follows Table 1:

[0154] Table 1 Feeding speed of each chamber of the adsorption tower and optimal circulation amount of activated carbon under different thickness conditions

[0155]

[0156] In application example 1, the optimal activated carbon circulation amount recorded in Table 1 is searched to find the minimum activated carbon circulation amount S min =2.059m 3 / h, the thickness of the front, middle and rear chambers of the adsorption tower corresponding to the minimum activated carbon circulation amount is L1=0.3m, L2=0.65m, L3=0.65m, which is the optimized design of the thickness of the front, middle and rear chambers.

[0157] In application example 2, the optimal activated carbon circulation amount recorded in Table 1 is searched to find the minimum activated carbon circulation amount S min =4.632m 3 / h, the thickness of the front, middle and rear chambers of the adsorption tower corresponding to the minimum activated carbon circulation amount is L1=0.25m, L2=0.675m, L3=0.675m, which is the optimized design of the thickness of the front, middle and rear chambers.

[0158] It can be seen from the data in Table 1 that the present invention, by constructing an activated carbon adsorption rate equation combined with a simulation research method of actual engineering parameters, can obtain the optimal circulation amount of activated carbon under different thickness conditions of the front, middle and rear chambers of the adsorption tower, and thereby obtain the minimum optimal circulation amount of activated carbon, thereby optimizing the thickness of the front, middle and rear chambers of the adsorption tower.

[0159] The optimal activated carbon circulation amount is the minimum activated carbon circulation amount obtained by minimizing the activated carbon feeding speed in the front, middle and rear chambers of the adsorption tower under the given thickness of each chamber of the adsorption tower and under the premise that the SO2 concentration at the flue gas outlet of the adsorption tower meets the control standard, that is, reducing the investment cost while ensuring the desulfurization efficiency. While keeping the total thickness of the adsorption tower unchanged, by changing the thickness of each chamber of the adsorption tower, multiple optimal activated carbon circulation amounts corresponding to different thicknesses are obtained, and the minimum optimal activated carbon circulation amount is obtained from them, so as to optimize the thickness of each chamber of the adsorption tower, further reduce the investment cost and improve the production efficiency.

Claims

1. A method for optimizing the thickness of the front, middle and rear chambers of an adsorption tower, the method comprising the following steps: 1) Based on the variation of the amount of SO2 adsorbed by activated carbon over time during the desulfurization process, an activated carbon adsorption rate model was established; 2) The activated carbon bed of the adsorption tower is divided into front, middle and rear chambers according to the direction of the flue gas, and the desulfurization process of the activated carbon in each chamber is simulated; 3) Input model constants, set the thickness of the front, middle and rear chambers of the adsorption tower, and the SO2 concentration at the flue gas inlet of the adsorption tower, obtain the activated carbon feeding rate of the front, middle and rear chambers of the adsorption tower under the current conditions, and thus obtain the optimal circulation amount of activated carbon under the current conditions, so that the SO2 concentration at the flue gas outlet of the adsorption tower is within the set range; 4) The total thickness of the activated carbon bed in the adsorption tower is fixed, and the thickness of the front, middle and rear chambers of the adsorption tower is adjusted so that the activated carbon circulation amount corresponding to the activated carbon feeding speed of the front, middle and rear chambers of the adsorption tower after adjustment is minimized, thereby optimizing the thickness of the front, middle and rear chambers of the adsorption tower.

2. The method for optimizing the thickness of the front, middle and rear chambers of the adsorption tower according to claim 1, characterized in that: The activated carbon adsorption rate model is established in step 1), specifically: 101) Based on the variation of the amount of SO2 adsorbed by activated carbon over time during the desulfurization process, draw an activated carbon adsorption rate curve; 102) Based on the variation of the SO2 concentration ratio at the flue gas inlet and outlet of the adsorption 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; 103) Based on the activated carbon adsorption rate curve and the characteristic that the adsorption rate of SO2 by activated carbon is constant in the first and third stages, an activated carbon adsorption rate equation is constructed.

3. The method for optimizing the thickness of the front, middle and rear chambers of the adsorption tower according to claim 2, characterized in that: In sub-step 103), 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 adsorption 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.

4. The method for optimizing the thickness of the front, middle and rear chambers of the adsorption tower according to any one of claims 1 to 3, characterized in that: In step 2), the activated carbon bed of the adsorption tower is divided into a front chamber, a middle chamber, and a rear chamber, the thickness of the front chamber is L1, the thickness of the middle chamber is L2, and the thickness of the rear chamber is L3; wherein L1<L2≤L3; and / or 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; wherein, 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.

5. The method for optimizing the thickness of the front, middle and rear chambers of the adsorption tower according to claim 3 or 4, characterized in that: In step 2), the desulfurization process is simulated for each chamber of activated carbon, specifically: The adsorption tower is divided into grids, the height of the adsorption tower is divided into m grids, and the width of the adsorption tower is divided into n grids; based on the flue gas direction, the activated carbon adsorption rate equation is applied to each grid one by one; 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 top grid of the adsorption tower is 0, and the SO2 concentration C[i, 0] of the grid at the flue gas inlet of the adsorption tower is 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 adsorption tower, dQ[i, j] represents the newly added 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 adsorption tower, dC[i, j] represents the reduced 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 adsorption tower; v is the activated carbon feeding speed at the corresponding position in the adsorption tower; C0 is the SO2 concentration at the flue gas inlet of the adsorption tower.

6. The method for optimizing the thickness of the front, middle and rear chambers of the adsorption tower according to claim 4 or 5, characterized in that: Step 3) is specifically: Input model constants, set the initial thickness of the front, middle and rear chambers of the adsorption tower, detect the SO2 concentration at the flue gas inlet of the adsorption tower online, and calculate the activated carbon feeding rates of the front, middle and rear chambers of the adsorption tower through the activated carbon adsorption rate equation according to the proportional relationship between the activated carbon feeding rates of the front, middle and rear chambers of the adsorption tower; adjust the activated carbon feeding rates of the front, middle and rear chambers of the adsorption tower to obtain the optimal circulation amount of activated carbon under corresponding conditions, while ensuring that the SO2 concentration at the flue gas outlet of the adsorption tower is within the set range.

7. The method for optimizing the thickness of the front, middle and rear chambers of the adsorption tower according to claim 6, characterized in that: The model constants include: the height, width and total thickness of the adsorption tower; and / or Adjust the activated carbon feeding speed of the front, middle and rear chambers of the adsorption tower to obtain the optimal activated carbon circulation under the corresponding conditions, while ensuring that the SO2 concentration at the flue gas outlet of the adsorption tower is less than C 设 ; Among them: C 设 is the upper limit of SO2 concentration at the flue gas outlet of the adsorption tower; C 设 ≤35mg / Nm 3 .

8. The method for optimizing the thickness of the front, middle and rear chambers of the adsorption tower according to claim 7, characterized in that: Adjust the activated carbon feeding speed in the front, middle and rear chambers of the adsorption tower to obtain the optimal activated carbon circulation under the corresponding conditions, while ensuring that the SO2 concentration at the flue gas outlet of the adsorption tower is less than C 设 ; Specifically: 301) According to the SO2 concentration at the flue gas inlet of the adsorption tower, combined with the proportional relationship of the activated carbon feeding speed in the front, middle and rear chambers of the adsorption tower, and the SO2 concentration at the flue gas outlet of the adsorption tower is less than C 设 As the goal, the activated carbon feeding rate in the front, middle and rear chambers of the adsorption tower was calculated by the activated carbon adsorption rate equation to obtain the preliminary optimized activated carbon feeding rate; 302) According to the calculated initial optimized activated carbon feeding speeds in the front, middle and rear chambers of the adsorption tower, calculate the initial SO2 concentration C at the flue gas outlet of the adsorption tower at the corresponding activated carbon feeding speed 初 ; Compare the preliminary SO2 concentration C 初 and SO2 concentration upper limit C 设 ; 302a) If the initial SO2 concentration is 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 adsorption tower at this time, calculate the adjusted SO2 concentration at the flue gas outlet of the adsorption 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 adsorption tower is ≥C 设 At this time, the last recorded activated carbon feeding rate in each chamber is the optimal feeding rate, so as to determine the optimal circulation amount of activated carbon and record it.

9. The method for optimizing the thickness of the front, middle and rear chambers of the adsorption tower according to claim 8, characterized in that: Step 302) also includes: 302b) If the initial SO2 concentration is C 初 ≥C 设 , slightly increase the activated carbon feeding speed of the front, middle and rear chambers of the adsorption tower at this time, and then record the current activated carbon feeding speed of each chamber. According to the activated carbon feeding speed of each chamber after adjustment, calculate the adjusted SO2 concentration at the flue gas outlet of the adsorption 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 adsorption tower is less than C 设 At this time, the last recorded activated carbon feeding rate in each chamber is the optimal feeding rate, so as to determine the optimal circulation amount of activated carbon and record it.

10. The method for optimizing the thickness of the front, middle and rear chambers of an adsorption tower according to any one of claims 1 to 9, characterized in that: Step 4) specifically includes: 401) keep the total thickness of the adsorption tower unchanged, slightly increase the thickness of the front chamber of the adsorption tower, and at the same time, reduce the thickness of the middle chamber and the thickness of the rear chamber accordingly; 402) Repeat step 3), calculate and record the activated carbon feeding speed of the front, middle and rear chambers of the adjusted adsorption tower and the corresponding optimal activated carbon circulation amount according to the thickness of each chamber of the adsorption tower after adjustment; 403) repeating sub-steps 401) and 402) until the thickness of the front chamber is greater than or equal to the thickness of the middle chamber, and then exiting the loop; 404) Find the recorded optimal activated carbon circulation amount, find out the minimum activated carbon circulation amount, and the thickness of the front, middle and rear chambers of the adsorption tower corresponding to the minimum activated carbon circulation amount is the optimized thickness of the front, middle and rear chambers.

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