A desulfurization solvent network design method based on process connotation

Abstract

The application provides a desulfurization solvent network design method based on process connotation, which is based on the process connotation of desulfurization and proposes a new graph to illustrate the operation limit of a desulfurization device. The graph can show the relationship between lean amine liquid and rich amine liquid of a desulfurization unit, construct a feasible operation window of the desulfurization unit, analyze different situations of recycling rich amine liquid between desulfurization units, and guide the recycling of rich amine liquid between desulfurization units. Based on this, all feasible connections between desulfurization units are determined, the number of desulfurization units is divided, and the desulfurization solvent network is designed to reduce the circulation amount of desulfurization solvent. The method can reflect the process connotation of recycling rich amine liquid between desulfurization units and designing a desulfurization network, and can provide more accurate and simple solvent network design.

Description

Technical Field

[0001] This invention relates to desulfurization processes, and more particularly to a desulfurization solvent network design method based on process context. Background Technology

[0002] Hydrogen dioxide (H2S) gas is mainly produced in petroleum refining, coal gas production, natural gas purification, synthetic fiber manufacturing, sulfur dye production, wastewater treatment, papermaking, pharmaceutical manufacturing, and other production processes, as well as in the decomposition of organic matter. Due to its toxicity, corrosiveness, and distinctive rotten egg odor, it not only severely impacts the ecological environment but also poses a significant threat to human health. Low concentrations of H2S gas have a rotten egg odor and irritate the throat and eyes. High concentrations of H2S gas are fatal to humans; it enters the body through the lungs, causing respiratory arrest and ultimately death. Therefore, countries worldwide have established very strict emission standards.

[0003] As the sulfur content of global crude oil continues to increase, the processing of sulfur-containing oil products and hydrorefining generates significant amounts of H2S gas in hydrotreating tail gas and refinery gas, leading to catalyst deactivation, equipment corrosion, and excessively high sulfur content in gaseous products. However, environmental regulations are continuously reducing the sulfur content in fuel products. Therefore, the addition of desulfurization units is essential for refineries to obtain qualified crude oil products. The desulfurization process is energy-intensive; the addition of desulfurization units increases the circulation volume of desulfurization solvents, ultimately resulting in a surge in steam consumption during solvent regeneration, which has become a significant component of refinery energy costs. Therefore, reducing the circulation volume of desulfurization solvents is crucial for process economics.

[0004] Currently, methods to reduce the circulating volume of desulfurization solvents in desulfurization systems include optimizing process operating parameters, improving the absorption performance of desulfurization solvents, and constructing desulfurization solvent networks. Among these, constructing a desulfurization solvent network integrates the concept of process integration into the desulfurization system, achieving efficient utilization of solvent resources, reducing production costs, and promoting energy conservation, emission reduction, and resource protection. Existing optimization methods for constructing desulfurization solvent networks are often based on limiting data models and desulfurization mechanism models, but these methods have some shortcomings. Limiting data models do not consider mass transfer processes, and the results may deviate from actual data. Desulfurization mechanism models provide reliable results, but redundant connections exist in the superstructure, which increases the number of nonlinear terms in the model, increasing the difficulty and time required to solve the mathematical programming model. Furthermore, because mathematical programming models are black-box models, it is difficult to fine-tune the obtained design scheme. Summary of the Invention

[0005] To address the problems of the prior art, this invention provides a desulfurization solvent network design method based on process context, which can provide a more accurate and concise solvent network design.

[0006] This invention is achieved through the following technical solution:

[0007] A desulfurization solvent network design method based on process intension includes:

[0008] S1: Based on the equipment parameters, operating parameters, raw gas composition, and lean amine solution composition of the desulfurization unit, obtain the flow rate of lean amine solution, the flow rate of rich amine solution, and the H2S concentration of rich amine solution when achieving the desulfurization target for different H2S concentrations; calculate the H2S load of lean amine solution based on the flow rate and H2S concentration of lean amine solution; calculate the H2S load of rich amine solution based on the flow rate and H2S concentration of rich amine solution; the rich amine solution refers to the outlet amine solution of the desulfurization unit, and the lean amine solution refers to the inlet amine solution of the desulfurization unit.

[0009] S2: Based on the flow rate and H2S load of lean amine solution and the flow rate and H2S load of rich amine solution, create an H2S load-flow rate diagram for each desulfurization unit.

[0010] S3: Based on the H2S load-flow diagram of the desulfurization unit, determine the H2S concentration range of the amine-rich solution and the H2S concentration range of the available amine solution in the desulfurization unit.

[0011] S4: Based on the H2S concentration range obtained in S3, determine the matching relationship between each desulfurization unit;

[0012] S5: Based on the matching relationship between each desulfurization unit, the number of stages of the desulfurization unit is determined;

[0013] S6: Based on the number of stages of the desulfurization unit and the H2S load-flow diagram, determine the amount of fresh amine solution used after the desulfurization unit reuses the rich amine solution and the amount of rich amine solution reused.

[0014] S7: Based on the H2S concentration range of the rich amine solution in the desulfurization unit, the matching relationship of the desulfurization unit, the amount of rich amine solution reused, and the amount of fresh amine solution used, a desulfurization solvent network is constructed.

[0015] Preferably, S2 specifically includes:

[0016] S201: Plot the H2S load-flow rate curve of the lean amine solution with the flow rate of the lean amine solution as the x-axis and the H2S load of the lean amine solution as the y-axis. This curve is called the lean amine solution curve.

[0017] S202: Plot the H2S load-flow rate curve of the rich amine liquid with the flow rate of the rich amine liquid as the x-axis and the H2S load of the rich amine liquid as the y-axis. This curve is called the rich amine liquid curve.

[0018] S203: Starting from the origin O, with the H2S concentration of the fresh amine solution as the slope, draw a straight line L1, which is the H2S load-flow line of the fresh amine solution. The intersection of L1 and the lean amine solution curve is denoted as point C.

[0019] S204: The line connecting the origin O and the endpoint of the amine-deficient liquid curve is denoted as line L2, and the endpoint of L2 is denoted as point D;

[0020] S205: Draw the tangent line to the amine-deficient solution curve through point C, and denote it as L3';

[0021] S206: Starting from the origin O, draw a line parallel to L3', denoted as L3;

[0022] S207: Connect the origin O and the starting point E of the amine-rich liquid curve to obtain line segment L4;

[0023] S208: Connect the origin O and the endpoint H of the amine-rich liquid curve to obtain line segment L5.

[0024] Furthermore, S3 specifically includes:

[0025] S301: The range between L1 and L2 is the range of H2S concentration in the fully reused amine-rich liquid of the desulfurization unit;

[0026] S302: The range between L2 and L3 is the range of H2S concentration in the partially reused amine-rich liquid of the desulfurization unit;

[0027] S303: The range between L3 and L4 is the range of H2S concentrations in the desulfurization unit where the reuse of rich amine solution is prohibited.

[0028] S304: The range between L4 and L5 is the range of H2S concentration in the amine-rich liquid of the desulfurization unit.

[0029] Furthermore, assuming two desulfurization units, desulfurization unit A and desulfurization unit B, S4 specifically includes:

[0030] S401: When the L4 and L5 regions of desulfurization unit A are located between L1 and L2 of desulfurization unit B, the matching relationship between desulfurization unit A and desulfurization unit B is marked as complete reuse.

[0031] S402: When the L4 and L5 regions of desulfurization unit A are located between L2 and L3 of desulfurization unit B, the matching relationship between desulfurization unit A and desulfurization unit B is marked as partial reuse.

[0032] S403: When the region consisting of L4 and L5 of desulfurization unit A is located between L3 of desulfurization unit B and the vertical axis, the matching relationship between desulfurization unit A and desulfurization unit B is marked as prohibited from reuse.

[0033] Furthermore, S4 also includes:

[0034] S404: When the L4 and L5 regions of desulfurization unit A span multiple regions of desulfurization unit B, a combination of markings for complete reuse, partial reuse, and prohibited reuse is applied; the multiple regions include the region between L1 and L2, the region between L2 and L3, and the region between L3 and the vertical axis.

[0035] Furthermore, S5 specifically includes:

[0036] S501: Desulfurization units that cannot reuse amine-rich liquid from other desulfurization units are classified as first-stage desulfurization units; if multiple first-stage desulfurization units exist, they shall be discharged in parallel.

[0037] S502: Desulfurization units that can only reuse the rich amine solution from the first-stage desulfurization unit are classified as second-stage desulfurization units; desulfurization units that can only reuse the rich amine solution from the first-stage and second-stage desulfurization units are classified as third-stage desulfurization units, and so on.

[0038] Furthermore, S5 also includes:

[0039] When the second-stage desulfurization unit reuses the rich amine solution from the first-stage desulfurization unit, and there is still a surplus of rich amine solution from the first-stage desulfurization unit, the surplus rich amine solution from the first-stage desulfurization unit is diverted to the third-stage desulfurization unit for use, and so on.

[0040] Furthermore, S5 also includes:

[0041] If the matching relationship between desulfurization unit A and desulfurization unit B is complete reuse, then desulfurization unit B reuses all the amine-rich liquid from desulfurization unit A.

[0042] Furthermore, S6 specifically includes:

[0043] Starting from the origin O, with the H2S concentration of the amine-rich liquid in desulfurization unit A as the slope and the flow rate of the amine-rich liquid in desulfurization unit A as the abscissa, draw line segment L6 on the H2S load-flow diagram of desulfurization unit B.

[0044] If line segment L6 intersects or is tangent to the amine-poor liquid curve of desulfurization unit B, then the amount of fresh amine liquid used after desulfurization unit B reuses the amine-rich liquid from desulfurization unit A is 0. The intersection or tangency point indicates the amount of amine-rich liquid reused by desulfurization unit A.

[0045] Otherwise, move L6 along L1 until L6 intersects or is tangent to the lean amine liquid curve of desulfurization unit B, denoted as L6'. Connect the origin O with the intersection or tangent point of L6' and the lean amine liquid curve to obtain L7. The x-coordinate of the intersection point of L6' and L1 is the amount of fresh amine liquid used after desulfurization unit B reuses the rich amine liquid from desulfurization unit A. The x-coordinate corresponding to the end of L7 minus the amount of fresh amine liquid used is the amount of rich amine liquid reused by desulfurization unit A.

[0046] Preferably, in S1, the flow rate of the lean amine solution, the flow rate of the rich amine solution, and the H2S concentration of the rich amine solution are obtained by simulation calculation or experiment when the desulfurization target is achieved.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] This invention proposes a novel desulfurization solvent network design method based on process implications. Based on the desulfurization process implications, a new graphical representation is proposed to illustrate the operational constraints of the desulfurization unit. This graph can illustrate the relationship between lean and rich amine solutions in the desulfurization unit, construct feasible operating windows for the desulfurization unit, analyze different scenarios of rich amine solution reuse between desulfurization units, and guide the reuse of rich amine solution between desulfurization units. Based on this, all feasible connections between desulfurization units are determined, the number of stages of the desulfurization units is divided, and the desulfurization solvent network is designed to reduce the amount of circulating desulfurization solvent. This method can reflect the process implications of reusing rich amine solution between desulfurization units and designing the desulfurization network, and can provide a more accurate and concise solvent network design. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0050] Figure 1 This is a schematic diagram illustrating the implementation steps of the present invention;

[0051] Figure 2 This is a detailed flowchart of S2 of the present invention;

[0052] Figure 3 This is a schematic diagram of H2S load-flow rate for a desulfurization unit.

[0053] Figure 4 This is a detailed step diagram of S6 of the present invention;

[0054] Figure 5 This is a detailed schematic diagram of case 1 of S6 of the present invention;

[0055] Figure 6 This is a detailed schematic diagram of case 2 of S6 of the present invention;

[0056] Figure 7 This is a detailed schematic diagram of case 3 of S6 of the present invention;

[0057] Figure 8 This is a detailed schematic diagram of case 4 of S6 of the present invention. Detailed Implementation

[0058] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0059] It should be noted that the process equipment or apparatus not specifically mentioned in the following embodiments are all conventional equipment or apparatus in the art.

[0060] It should be noted that the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or desulfurization units is not necessarily limited to those steps or desulfurization units explicitly listed, but may include other steps or desulfurization units not explicitly listed or inherent to these processes, methods, products, or apparatuses. Furthermore, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not intended to limit the order of the method steps or define the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0061] Please see Figure 1 This invention provides a desulfurization solvent network design method based on process connotation, comprising the following steps:

[0062] S1: Based on the equipment parameters, operating parameters, raw gas composition, and lean amine solution composition of the desulfurization unit, the flow rates of lean amine solution, rich amine solution, and H2S concentration of rich amine solution are obtained through rigorous simulation calculations or experiments to achieve the desulfurization target. The H2S load of the lean amine solution is calculated based on its flow rate and H2S concentration; the H2S load of the rich amine solution is also calculated based on its flow rate and H2S concentration. The rich amine solution refers to the outlet amine solution of the desulfurization unit; the lean amine solution refers to the inlet amine solution of the desulfurization unit, which can be fresh amine solution, rich amine solution generated in the network, or a mixture thereof.

[0063] S2: Based on the results obtained from simulation calculations or experiments, and according to the flow rate and H2S load of lean amine solution and the flow rate and H2S load of rich amine solution, create an H2S load-flow diagram for each desulfurization unit.

[0064] S3: Based on the H2S load-flow diagram of the desulfurization unit, determine the H2S concentration range of the amine-rich liquid in the desulfurization unit and the H2S concentration range of the reusable amine-rich liquid.

[0065] S4: Based on the above H2S concentration range, determine the matching relationship between desulfurization units.

[0066] S5: Based on the matching relationship between desulfurization units, the number of stages of desulfurization units is divided.

[0067] S6: Based on the number of stages of the desulfurization unit and the H2S load-flow diagram, determine the amount of fresh amine solution used after the desulfurization unit reuses the rich amine solution and the amount of rich amine solution reused.

[0068] S7: Based on the above steps, construct the desulfurization solvent network.

[0069] Please see Figure 2 Based on simulation calculations or experimental results, the specific steps for creating an H2S load-flow diagram for each desulfurization unit, according to the flow rate and H2S load of the lean amine solution and the flow rate and H2S load of the rich amine solution, are as follows:

[0070] S201: Based on the flow rate and H2S load of the lean amine solution, plot the H2S load-flow rate curve of the lean amine solution in the desulfurization unit, and denote it as the lean amine solution curve.

[0071] S202: Based on the flow rate and H2S load of the rich amine solution, plot the H2S load-flow rate curve of the rich amine solution in the desulfurization unit, and denote it as the rich amine solution curve.

[0072] S203: Starting from the origin O, with the H2S concentration of the fresh amine solution as the slope, draw a straight line L1, which is the H2S load-flow line of the fresh amine solution. The intersection point with the curve of the lean amine solution is denoted as point C.

[0073] S204: Connect the origin O and the endpoint of the amine-deficient liquid curve, denoted as line L2, and the endpoint of L2 is denoted as point D.

[0074] S205: Draw the tangent line to the amine-deficient solution curve through point C, and denote it as L3'.

[0075] S206: Starting from the origin O, draw a line parallel to L3', denoted as L3.

[0076] S207: Connect the origin O and the starting point E of the amine-rich liquid curve to obtain line segment L4.

[0077] S208: Connect the origin O and the endpoint H of the amine-rich liquid curve to obtain line segment L5.

[0078] S209: The distance between the rich amine liquid curve and the poor amine liquid curve represents the desulfurization load ΔM of the desulfurization unit.

[0079] S210: The amine flow rate corresponding to intersection C is the minimum fresh amine flow rate F of the desulfurization unit. min .

[0080] S211: Line segment L4 represents the flow rate of fresh amine solution as F. min The slope of the corresponding amine-rich solution is the maximum H2S concentration at the outlet of the desulfurization unit.

[0081] S212: The slope of line segment L5 is the minimum H2S concentration at the outlet of the desulfurization unit.

[0082] Please see Figure 3 H in the desulfurization unit S A schematic diagram of the S-load-flow diagram.

[0083] S301: The range between L1 and L2 is the range of H2S concentration in the fully recycled amine-rich liquid of the desulfurization unit.

[0084] S302: The range between L2 and L3 is the range of H2S concentration in the partially reused amine-rich liquid of the desulfurization unit.

[0085] S303: The range between L3 and L4 is the range of H2S concentrations in the desulfurization unit where the reuse of rich amine solution is prohibited.

[0086] S304: The range between L4 and L5 is the range of H2S concentration in the amine-rich liquid of the desulfurization unit.

[0087] The specific steps for determining the matching relationship between desulfurization units based on the concentration range are as follows (there are two desulfurization units, A and B):

[0088] S401: When the L4 and L5 regions of desulfurization unit A are located between L1 and L2 of desulfurization unit B, if the flow rate is sufficient, desulfurization unit B can reuse only the amine-rich liquid from desulfurization unit A to meet its needs. The matching relationship is marked as complete reuse (CR).

[0089] S402: When the L4 and L5 regions of desulfurization unit A are located between L2 and L3 of desulfurization unit B, even if the flow rate is sufficient, desulfurization unit B can only reuse a portion of the amine-rich liquid from desulfurization unit A. The matching relationship is marked as partial reuse (PR).

[0090] S403: When the L4 and L5 regions of desulfurization unit A are located between L3 and the vertical axis of desulfurization unit B, desulfurization unit B cannot reuse the amine-rich liquid from desulfurization unit A, and the matching relationship is marked as prohibited from reuse (FR).

[0091] S404: When the L4 and L5 regions of desulfurization unit A span multiple regions of desulfurization unit B, a combined label is used, such as CR&PR, PR&FR, or CR&PR&FR.

[0092] Based on the matching relationship of the desulfurization units, the specific steps for dividing the desulfurization units into stages are as follows:

[0093] S501: Desulfurization units that cannot accept rich amine solutions from other desulfurization units and require fresh amine solutions to meet desulfurization targets are classified as Level 1. If multiple such desulfurization units exist, they shall be discharged in parallel.

[0094] S502: Desulfurization units that can only reuse the rich amine solution from the first-stage desulfurization unit are classified as the second-stage unit; desulfurization units that can only reuse the rich amine solution from the first-stage and second-stage desulfurization units are classified as the third-stage unit, and so on.

[0095] S503: When there is excess amine-rich liquid in the first stage, it should be bypassed to the third stage desulfurization unit for use, and so on.

[0096] S504: If a desulfurization unit can satisfy the requirement of using all or only the amine-rich liquid from another desulfurization unit, this should be given priority to reduce the number of matches in the network. For example, if the match relationship between desulfurization unit A and desulfurization unit B is complete reuse, then desulfurization unit B reuses all the amine-rich liquid from desulfurization unit A.

[0097] Please see Figure 4 After the desulfurization unit reuses the rich amine solution, the specific method for determining the amount of fresh amine solution to use is as follows:

[0098] S601: Starting from the origin O, with the H2S concentration of the amine-rich liquid in desulfurization unit A as the slope and the flow rate of the amine-rich liquid as the abscissa, draw line segment L6 on the H2S load-flow diagram of desulfurization unit B.

[0099] S602: Move L6 along L1 until it intersects or is tangent to the lean amine liquid curve of desulfurization unit B, and denoted as L6'.

[0100] S603: Connect the origin O of the coordinate system with the intersection or tangent point of the curve of the lean amine solution in S602 to obtain L7.

[0101] S604: L6 is the H2S load-flow rate line of the amine-rich liquid in desulfurization unit A, and the flow rate F corresponding to its endpoint is... rich The flow rate of the amine-rich solution in desulfurization unit A.

[0102] S605: Flow rate F corresponding to the intersection of L6' and L1 fresh The amount of fresh amine solution used after the desulfurization unit B reuses the rich amine solution.

[0103] S606: L7 indicates that the mixed amine solution of rich amine solution L6 and fresh amine solution in desulfurization unit A can meet the desulfurization requirements of desulfurization unit B.

[0104] S607: The slope of L7 represents the inlet H2S concentration of desulfurization unit B, and the corresponding flow rate F. in F is the flow rate of the amine solution at the inlet of desulfurization unit B. inSubtract F fresh This is the amount of amine-rich solution that can be reused.

[0105] S608: Please refer to Figure 5-8 The reuse of amine-rich liquid from desulfurization unit A by desulfurization unit B can be categorized into the following four cases:

[0106] S609: Figure 5 In scenario 1, the flow rate of the rich amine solution in desulfurization unit A is sufficiently large, and the H2S concentration of the rich amine solution meets the desulfurization requirements of desulfurization unit B (L6 is located between L1 and L2 in desulfurization unit B). Line segment L6 intersects or is tangent to the lean amine solution curve. Desulfurization unit B can achieve its desulfurization target using only the rich amine solution from desulfurization unit A. The intersection or tangency point represents the amount of rich amine solution recycled from desulfurization unit A. The H2S concentration of the inlet amine solution in desulfurization unit B is the slope of L6.

[0107] S610: Figure 6 In scenario 2, the flow rate of the rich amine solution in desulfurization unit A is low, and the H2S concentration of the rich amine solution is sufficient to meet the desulfurization requirements of desulfurization unit B (L6 is located between L1 and L2 in desulfurization unit B). However, the flow rate is insufficient, and line segment L6 neither intersects nor is tangent to the lean amine solution curve of desulfurization unit B. Even if desulfurization unit B uses all the rich amine solution from desulfurization unit A, it cannot meet the desulfurization requirements and needs to supplement a certain amount of fresh amine solution to meet the desulfurization target. Move L6 along L1 until L6 intersects or is tangent to the lean amine solution curve of desulfurization unit B, denoted as L6'. Connect the origin O with the intersection or tangency point of L6' and the lean amine solution curve to obtain L7. The x-coordinate of the intersection point of L6' and L1 represents the amount of fresh amine solution used after desulfurization unit B reuses the rich amine solution from desulfurization unit A. Subtracting the amount of fresh amine solution used from the x-coordinate corresponding to the end of L7 gives the amount of rich amine solution reused by desulfurization unit A.

[0108] S611: Figure 7 In scenario 3, the flow rate of the rich amine solution in desulfurization unit A is sufficiently large, but the H2S concentration of the rich amine solution is relatively high (L6 is located between L2 and L3 in desulfurization unit B). The line segment L6 neither intersects nor is tangent to the lean amine solution curve. Using rich amine solution alone cannot meet the needs of desulfurization unit B, and fresh amine solution needs to be added to reduce the H2S concentration of the mixed amine solution. Move L6 along L1 until L6 intersects or is tangent to the lean amine solution curve of desulfurization unit B, denoted as L6'. Connect the origin O with the intersection or tangent point of L6' and the lean amine solution curve to obtain L7. The x-coordinate of the intersection point of L6' and L1 is the amount of fresh amine solution used after desulfurization unit B reuses the rich amine solution from desulfurization unit A. The x-coordinate corresponding to the end of L7 minus the amount of fresh amine solution used is the amount of rich amine solution reused by desulfurization unit A.

[0109] S612: Figure 8In scenario 4, the flow rate of the rich amine solution in desulfurization unit A is low, but the H2S concentration in the rich amine solution is high (L6 is located between L2 and L3 in desulfurization unit B). The line segment L6 neither intersects nor is tangent to the lean amine solution curve. Desulfurization unit B needs to use all of the rich amine solution and some fresh amine solution to meet the desulfurization requirements. Move L6 along L1 until L6 intersects or is tangent to the lean amine solution curve of desulfurization unit B, denoted as L6'. Connect the origin O with the intersection or tangency point of L6' and the lean amine solution curve to obtain L7. The x-coordinate of the intersection point of L6' and L1 is the amount of fresh amine solution used by desulfurization unit B after reusing the rich amine solution from desulfurization unit A. The x-coordinate corresponding to the end of L7 minus the amount of fresh amine solution used is the amount of rich amine solution reused by desulfurization unit A.

[0110] S701: After determining the concentration range, matching relationship, reuse amount of rich amine solution, and fresh amine solution usage of the desulfurization unit, the desulfurization solvent network is finally constructed.

[0111] Example 1

[0112] Rigorous simulation calculations were performed on four desulfurization units (U101–U104) of a refinery to obtain the flow rate and H2S concentration of lean amine solution and rich amine solution for each unit, thereby calculating the H2S load of lean and rich amine solutions. Based on the simulation data, an H2S load-flow diagram was created for each desulfurization unit, revealing the feasible operating window for each unit, and the slopes of L1–L5 for each unit were compiled. Based on the slopes of the straight lines for each desulfurization unit, the matching relationship between any two units was determined, and the units were classified: U102 cannot reuse rich amine solution from any other desulfurization unit, so U102 is classified as Level 1. U101 can only reuse rich amine solution from U102, so U102 is classified as Level 2. U103 and U104 can reuse rich amine solution from both U101 and U102, but cannot reuse rich amine solution from each other, so U103 and U104 are classified as Level 3. Based on the results of the level division, four integrated design schemes for desulfurization solvent networks can be obtained.

[0113] In the current network, all four desulfurization units use only fresh amine solution, totaling 2363 kmol·h⁻¹. -1 The four integrated design schemes obtained using this method have a fresh amine solution consumption of 2172 kmol·h⁻¹, respectively. -1 2113 kmol·h -1 2117 kmol·h -1 and 2169 kmol·h -1 Compared to the existing network, it can save more than 8.08% of fresh amine solution.

[0114] The above describes the implementation method of the present invention. Any person skilled in the art may modify or alter the above method to create equivalent embodiments for application in other fields, such as using amine liquid for CO2 capture. However, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A desulfurization solvent network design method based on process connotation, characterized in that, include: S1: Based on the equipment parameters, operating parameters, raw gas composition, and lean amine solution composition of the desulfurization unit, obtain the flow rate of lean amine solution, the flow rate of rich amine solution, and the H2S concentration of rich amine solution when achieving the desulfurization target for different H2S concentrations; calculate the H2S load of lean amine solution based on the flow rate and H2S concentration of lean amine solution; calculate the H2S load of rich amine solution based on the flow rate and H2S concentration of rich amine solution; the rich amine solution refers to the outlet amine solution of the desulfurization unit, and the lean amine solution refers to the inlet amine solution of the desulfurization unit. S2: Based on the flow rate and H2S load of lean amine solution and the flow rate and H2S load of rich amine solution, create an H2S load-flow rate diagram for each desulfurization unit. S3: Based on the H2S load-flow diagram of the desulfurization unit, determine the H2S concentration range of the amine-rich solution and the H2S concentration range of the available amine solution in the desulfurization unit. S4: Based on the H2S concentration range obtained in S3, determine the matching relationship between each desulfurization unit; S5: Based on the matching relationship between each desulfurization unit, the number of stages of the desulfurization unit is determined; S6: Based on the number of stages of the desulfurization unit and the H2S load-flow diagram, determine the amount of fresh amine solution used after the desulfurization unit reuses the rich amine solution and the amount of rich amine solution reused. S7: Based on the H2S concentration range of the rich amine solution in the desulfurization unit, the matching relationship of the desulfurization unit, the amount of rich amine solution reused, and the amount of fresh amine solution used, a desulfurization solvent network is constructed.

2. The desulfurization solvent network design method based on process connotation according to claim 1, characterized in that, S2 specifically includes: S201: Plot the H2S load-flow rate curve of the lean amine solution with the flow rate of the lean amine solution as the x-axis and the H2S load of the lean amine solution as the y-axis. This curve is called the lean amine solution curve. S202: Plot the H2S load-flow rate curve of the rich amine liquid with the flow rate of the rich amine liquid as the x-axis and the H2S load of the rich amine liquid as the y-axis. This curve is called the rich amine liquid curve. S203: Starting from the origin O, with the H2S concentration of the fresh amine solution as the slope, draw a straight line L1, which is the H2S load-flow line of the fresh amine solution. The intersection of L1 and the lean amine solution curve is denoted as point C. S204: The line connecting the origin O and the endpoint of the amine-deficient liquid curve is denoted as line L2, and the endpoint of L2 is denoted as point D; S205: Draw the tangent line to the amine-deficient solution curve through point C, and denote it as L3'; S206: Starting from the origin O, draw a line parallel to L3', denoted as L3; S207: Connect the origin O and the starting point E of the amine-rich liquid curve to obtain line segment L4; S208: Connect the origin O and the endpoint H of the amine-rich liquid curve to obtain line segment L5.

3. The desulfurization solvent network design method based on process connotation according to claim 2, characterized in that, S3 specifically includes: S301: The range between L1 and L2 is the range of H2S concentration in the fully reused amine-rich liquid of the desulfurization unit; S302: The range between L2 and L3 is the range of H2S concentration in the partially reused amine-rich liquid of the desulfurization unit; S303: The range between L3 and L4 is the range of H2S concentrations in the desulfurization unit where the reuse of rich amine solution is prohibited. S304: The range between L4 and L5 is the range of H2S concentration in the amine-rich liquid of the desulfurization unit.

4. The desulfurization solvent network design method based on process connotation according to claim 3, characterized in that, Suppose there are two desulfurization units, desulfurization unit A and desulfurization unit B. S4 specifically includes: S401: When the L4 and L5 regions of desulfurization unit A are located between L1 and L2 of desulfurization unit B, the matching relationship between desulfurization unit A and desulfurization unit B is marked as complete reuse. S402: When the L4 and L5 regions of desulfurization unit A are located between L2 and L3 of desulfurization unit B, the matching relationship between desulfurization unit A and desulfurization unit B is marked as partial reuse. S403: When the region consisting of L4 and L5 of desulfurization unit A is located between L3 of desulfurization unit B and the vertical axis, the matching relationship between desulfurization unit A and desulfurization unit B is marked as prohibited from reuse.

5. The desulfurization solvent network design method based on process connotation according to claim 4, characterized in that, S4 also includes: S404: When the L4 and L5 regions of desulfurization unit A span multiple regions of desulfurization unit B, a combination of markings for complete reuse, partial reuse, and prohibited reuse is applied; the multiple regions include the region between L1 and L2, the region between L2 and L3, and the region between L3 and the vertical axis.

6. The desulfurization solvent network design method based on process connotation according to claim 4, characterized in that, S5 specifically includes: S501: Desulfurization units that cannot reuse amine-rich liquid from other desulfurization units are classified as first-stage desulfurization units; if multiple first-stage desulfurization units exist, they shall be discharged in parallel. S502: Desulfurization units that can only reuse the rich amine solution from the first-stage desulfurization unit are classified as second-stage desulfurization units; desulfurization units that can only reuse the rich amine solution from the first-stage and second-stage desulfurization units are classified as third-stage desulfurization units, and so on.

7. The desulfurization solvent network design method based on process connotation according to claim 6, characterized in that, S5 also includes: When the second-stage desulfurization unit reuses the rich amine solution from the first-stage desulfurization unit, and there is still a surplus of rich amine solution from the first-stage desulfurization unit, the surplus rich amine solution from the first-stage desulfurization unit is diverted to the third-stage desulfurization unit for use, and so on.

8. The desulfurization solvent network design method based on process connotation according to claim 6, characterized in that, S5 also includes: If the matching relationship between desulfurization unit A and desulfurization unit B is complete reuse, then desulfurization unit B reuses all the amine-rich liquid from desulfurization unit A.

9. The desulfurization solvent network design method based on process connotation according to claim 6, characterized in that, S6 specifically includes: Starting from the origin O, with the H2S concentration of the amine-rich liquid in desulfurization unit A as the slope and the flow rate of the amine-rich liquid in desulfurization unit A as the abscissa, draw line segment L6 on the H2S load-flow diagram of desulfurization unit B. If line segment L6 intersects or is tangent to the amine-poor liquid curve of desulfurization unit B, then the amount of fresh amine liquid used after desulfurization unit B reuses the amine-rich liquid from desulfurization unit A is 0. The intersection or tangency point indicates the amount of amine-rich liquid reused by desulfurization unit A. Otherwise, move L6 along L1 until L6 intersects or is tangent to the lean amine liquid curve of desulfurization unit B, denoted as L6'. Connect the origin O with the intersection or tangent point of L6' and the lean amine liquid curve to obtain L7. The x-coordinate of the intersection point of L6' and L1 is the amount of fresh amine liquid used after desulfurization unit B reuses the rich amine liquid from desulfurization unit A. The x-coordinate corresponding to the end of L7 minus the amount of fresh amine liquid used is the amount of rich amine liquid reused by desulfurization unit A.

10. The desulfurization solvent network design method based on process connotation according to claim 1, characterized in that, In S1, the flow rates of lean amine solution, rich amine solution, and H2S concentration of rich amine solution are obtained through simulation calculation or experiment to achieve the desulfurization target when lean amine solution with different H2S concentrations is used.

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