Optimization method for maleic anhydride cycloaddition process

Abstract

The invention provides an optimization method for a maleic anhydride cycloaddition process, and relates to the technical field of maleic anhydride cycloaddition processes. Comprising the following steps: inputting a mixture of olefin, recycled olefin and maleic anhydride into a first-stage reactor to convert maleic anhydride into a six-membered ring structure so as to obtain a first-stage reaction solution; the second-stage reactor receives the first-stage reaction liquid and supplemented maleic anhydride, and the conversion rate of the six-membered ring structure in the second-stage reaction liquid is predicted; the reaction curing kettle enables maleic anhydride which is not completely converted in the secondary reaction liquid and olefin to continue to be subjected to cycloaddition reaction, and the mass of a maleic anhydride ring crude product is calculated according to the conversion rate of a six-membered ring structure; rectifying and separating the maleic anhydride ring crude product in a rectifying tower, predicting the quality of a tower bottom maleic anhydride ring fine product according to the quality of the maleic anhydride ring crude product, and adjusting the process parameters of the rectifying tower according to the quality of the maleic anhydride ring fine product. The continuous operation of the device is realized and the cycloaddition efficiency is improved through a series connection process of the double-loop reactor and the curing reactor.

Description

Technical Field

[0001] This invention relates to the field of maleic anhydride cycloaddition process technology, and in particular to an optimized method for maleic anhydride cycloaddition process. Background Technology

[0002] The cycloaddition reaction of maleic anhydride with alkenes has significant application value, and its products can be used in the synthesis of various downstream products. However, traditional cycloaddition processes of maleic anhydride with alkenes often have many limitations and challenges.

[0003] Traditional processes may struggle to efficiently convert maleic anhydride, resulting in low raw material utilization. This not only wastes valuable resources but also increases production costs. Furthermore, unreacted maleic anhydride residue can lead to a series of problems, such as affecting product quality and interfering with the stable operation of subsequent processes. The conversion rate of maleic anhydride is limited, making it difficult to achieve high levels that meet the yield and quality requirements of large-scale industrial production. Many traditional processes lack continuous flow design, with insufficiently smooth transitions between reaction stages. This results in material transfer losses and excessive waiting times, impacting overall production efficiency and hindering automation and large-scale production. Moreover, intermittent operation can cause fluctuations in product quality between batches, making stable quality control difficult. Without effective control over reaction depth and subsequent purification methods, the final product often contains significant impurities, limiting its use in applications requiring high purity. Summary of the Invention

[0004] This invention provides an optimized method for the cycloaddition process of maleic anhydride, which solves the defects of low raw material utilization and low product purity in the prior art.

[0005] On the one hand, the present invention provides an optimized method for the cycloaddition process of maleic anhydride, wherein a mixture of olefins, recycled olefins and maleic anhydride is fed into a primary reactor through a Venturi injector and reacted to convert maleic anhydride into a six-membered ring structure to obtain a primary reaction solution.

[0006] The secondary reactor receives the primary reaction solution and the added maleic anhydride for reaction. The conversion rate of the six-membered ring structure in the secondary reaction solution is predicted based on the initial concentration of maleic anhydride in the primary reaction solution and the concentration of added maleic anhydride.

[0007] The reaction maturation vessel receives the secondary reaction liquid and raises the temperature of the reaction liquid, allowing the incompletely converted maleic anhydride in the secondary reaction liquid to continue to undergo cycloaddition reaction with the olefin. The mass of crude maleic anhydride ring is calculated based on the conversion rate of the six-membered ring structure.

[0008] The crude maleic anhydride ring is separated by distillation in a distillation column. The quality of the fine maleic anhydride ring at the bottom of the column is predicted based on the quality of the crude maleic anhydride ring, and the process parameters of the distillation column are adjusted according to the quality of the fine maleic anhydride ring.

[0009] According to an optimization method for maleic anhydride cycloaddition process provided by the present invention, the secondary reaction liquid output from the bottom of the secondary reactor is reintroduced into the top of the secondary reactor through a secondary circulation pump and a secondary heat exchanger. It is determined whether the secondary reaction liquid is below a preset secondary threshold. If so, the secondary switch is opened and the secondary reaction liquid is input into the reaction ripening vessel.

[0010] According to an optimization method for the maleic anhydride cycloaddition process provided by the present invention, crude maleic anhydride is output from the bottom of the reaction maturation vessel and enters the reaction unloading pump. If the crude maleic anhydride is lower than a preset three-level threshold, the reaction unloading pump is started to transport the crude maleic anhydride in the reaction maturation vessel to the distillation column.

[0011] According to the optimization method for the maleic anhydride cycloaddition process provided by the present invention, the specific steps for predicting the conversion rate of the six-membered ring structure in the secondary reaction solution are as follows: A machine learning-based model was constructed to predict the conversion rate of six-membered ring structures in a second-order reaction solution.

[0012] Collect historical environmental data and preprocess it.

[0013] Feature extraction was performed on the preprocessed historical environmental data to obtain raw material characteristics, reaction condition characteristics, and equipment operation characteristics.

[0014] Historical environmental data is divided into training and test sets according to a preset ratio. The conversion rate prediction model is trained using the training set and validated using the test set until the test accuracy meets the preset accuracy. The corresponding model parameters are then retained.

[0015] By inputting recent raw material characteristics into the conversion rate prediction model, the predicted conversion rate Y of the six-membered ring structure is obtained.

[0016] The predicted amount of maleic anhydride to be added and the cycle intensity were calculated based on the conversion rate of the six-membered ring structure.

[0017] According to the optimization method for the maleic anhydride cycloaddition process provided by the present invention, the predicted conversion value Y of the six-membered ring structure is expressed as:

[0018] In the formula, Y0 is the model's basic predicted value, α is the concentration influence coefficient, C1 is the initial concentration of maleic anhydride in the first-stage reaction solution, C2 is the concentration of supplemented maleic anhydride, t is the second-stage reaction time, and k is the time correction index.

[0019] According to the optimization method for the maleic anhydride cycloaddition process provided by the present invention, the calculation formula for calculating the crude quality of maleic anhydride rings based on the conversion rate of the six-membered ring structure is expressed as follows:

[0020] In the formula, This represents the original mass of maleic anhydride in the primary reaction solution. The mass of the added maleic anhydride.

[0021] According to the optimization method for the maleic anhydride cycloaddition process provided by the present invention, the specific steps for obtaining the quality of the fine maleic anhydride cycloaddition product from the bottom of the prediction tower based on the quality of the crude maleic anhydride cycloaddition product are as follows: The mass fraction ω of the target six-membered ring product in the crude maleic anhydride product was determined by high performance liquid chromatography. 目标 .

[0022] Collect the top temperature T of the distillation column 顶 Temperature at the bottom of the tower T 底 Tower top pressure P 顶 Pressure P at the bottom of the tower 底 Reflux ratio R.

[0023] Based on the mass fraction ω of the target six-membered ring product in the crude product 目标 Calculate the bottom recovery rate of the target product using the distillation column process parameters. .

[0024] Based on the crude product quality and the mass fraction of the target six-membered ring product in the crude product, ω 目标 Calculate the theoretical mass m of the target product that can be converted into the fine product from the crude product. 理论 .

[0025] The formula for calculating the quality of the fine rings of maleic anhydride obtained at the bottom of the tower is expressed as follows:

[0026] In the formula, γ is the residual coefficient of trace impurities at the bottom of the tower.

[0027] According to an optimized method for maleic anhydride cycloaddition process provided by the present invention, in the recycling structure, the top buffer tank of the tower performs preliminary gas-liquid separation of olefins and trace amounts of maleic anhydride. The separated gas phase is discharged from the top to the vacuum system, while the liquid phase remains at the bottom of the buffer tank and is used by the olefin pump for the next maleic anhydride cycloaddition process.

[0028] According to the optimization method for the maleic anhydride cycloaddition process provided by the present invention, the specific steps for adjusting the process parameters of the distillation column based on the quality of the maleic anhydride cycloaddition product are as follows: Calculate the theoretical mass m of the target product 理论 The quality difference value between the product and the maleic anhydride ring-fine product.

[0029] Analyze the reasons for the discrepancies.

[0030] Adjust the distillation column process parameters according to the cause.

[0031] This invention provides an optimized method for the cycloaddition process of maleic anhydride. By employing a dual-loop reactor plus a ripening reactor in series, the device can operate continuously. The strong mass transfer effect of the loop reactor improves the cycloaddition efficiency. No catalyst is needed, reducing the impact of catalyst separation and residue. Maleic anhydride is added in a gradient between the primary and secondary reactors. The concentration of maleic anhydride in the primary reactor is reduced, while the product concentration in the secondary reactor is increased, thereby increasing the solubility of maleic anhydride, reducing maleic anhydride self-polymerization, and reducing product by-products.

[0032] The Venturi injector enables highly turbulent mixing of materials, allowing for full contact between material molecules. Furthermore, the use of a primary circulating pump to promote the circulation of the reaction liquid and a primary heat exchanger to precisely control the temperature ensures uniform mixing of materials within the reaction system and maintains a suitable reaction temperature. This facilitates a more complete reaction, improves overall reaction efficiency, and results in more uniform products in terms of properties and quality.

[0033] The six-membered ring structure conversion rate prediction model built based on machine learning comprehensively considers multiple factors such as raw material characteristics, reaction condition characteristics, and equipment operation characteristics. It can adjust key parameters such as the amount of maleic anhydride added and the cycle intensity in advance according to the predicted conversion rate, thereby controlling the reaction process more accurately, improving the quality of the final product, maleic anhydride ring fine product, and making it meet the high purity requirements for subsequent sales or use.

[0034] A recycling structure was set up, and with the help of equipment such as the top buffer tank and olefin pump, the reusable liquid material can be compounded with fresh raw materials to participate in the cycloaddition reaction again, realizing the closed-loop utilization of raw materials, effectively reducing the consumption of purchased raw materials, saving production costs from the source, and improving the economic efficiency of the entire process.

[0035] In the distillation column stage, a bottom circulation pump is used to maintain material balance and improve heat and mass transfer efficiency. Furthermore, the distillation column process parameters are finely adjusted based on predicted crude product quality and relevant process parameters. This minimizes the loss of target products due to incomplete reactions or poor separation, improving raw material utilization and avoiding resource waste. By linking the vacuum system with the vapor outlet of the top buffer tank, a stable, slightly negative pressure environment is created in the distillation column. This not only removes non-condensable gases promptly, preventing their accumulation and impacting separation efficiency, but also lowers the boiling points of olefins and maleic anhydride, reducing the occurrence of side reactions such as high-temperature pyrolysis. This contributes to improved product quality and also reduces potential safety and quality risks associated with side reactions.

[0036] The bottom circulation pump draws a portion of the liquid from the bottom of the distillation column and circulates it back into the column, ensuring a stable material quantity and appropriate liquid level. This allows the distillation operation to proceed continuously and stably. Furthermore, by dynamically adjusting the process parameters of the distillation column, the effects of changes in factors such as temperature, pressure, and reflux ratio are addressed, maintaining the distillation column's good separation efficiency and stability, and ensuring the reliable operation of the entire process. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in this 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 this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0038] Figure 1 This is a schematic flowchart of an optimized method for the cycloaddition process of maleic anhydride provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the physical structure of an optimized method for the maleic anhydride cycloaddition process provided in an embodiment of the present invention. Figure 3 This is a schematic diagram of the process for predicting the conversion rate of a six-membered ring structure in a secondary reaction solution, provided in an embodiment of the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0040] Example 1 The following is combined Figures 1-3 This invention describes an optimized method for the cycloaddition process of maleic anhydride.

[0041] Figure 1 This is a schematic flowchart of an optimized method for the cycloaddition process of maleic anhydride provided in an embodiment of the present invention.

[0042] like Figure 1 As shown in the embodiment of the present invention, an optimization method for the maleic anhydride cycloaddition process is provided, the method comprising: A mixture of olefins, recycled olefins, and maleic anhydride is fed into a primary reactor via a Venturi ejector for reaction and conversion, transforming the maleic anhydride into a six-membered ring structure to obtain the primary reaction solution. The mass ratio of olefins to maleic anhydride is 2:1 to 6:1. The Venturi ejector has a contraction section, a throat section, and a diffusion section. When the material enters the contraction section, the fluid velocity increases rapidly, and the pressure decreases accordingly. The highest velocity and lowest pressure are reached at the throat section, and then the velocity gradually decreases and the pressure rises again in the diffusion section. The mixture of olefins, recycled olefins, and maleic anhydride achieves a high degree of turbulent mixing, ensuring sufficient contact between the material molecules. Temperature, pressure, and level sensors are installed inside the primary reactor to monitor the internal data.

[0043] A primary circulation pump circulates the primary reaction liquid within the primary reactor, drawing it from the bottom and transporting it through pipelines to equipment such as the primary heat exchanger, ensuring uniform mixing of materials within the reaction system. In this embodiment, a uniform primary reaction liquid helps improve reaction efficiency and product homogeneity, allowing the reaction to proceed more fully. The primary heat exchanger facilitates heat exchange between the reaction liquid and other media, precisely controlling the temperature of the reaction liquid within the primary reactor. The primary heat exchanger utilizes steam to heat the primary reaction liquid. As steam exchanges heat with the primary reaction liquid inside the heat exchanger, the heat carried by the steam is continuously transferred to the reaction liquid, gradually increasing its temperature until it reaches 180-200°C. The primary heat exchanger's use of steam to heat the primary reaction liquid brings it to a suitable reaction temperature, accelerating the reaction rate and promoting the reaction process.

[0044] The primary level sensor measures whether the primary reaction liquid level is below the preset threshold. If so, switch one is turned on, and the primary reaction liquid is input into the secondary reactor.

[0045] The secondary reactor receives the primary reaction solution and adds maleic anhydride for reaction, and then transfers the secondary reaction solution to the reaction maturation vessel. Based on the characteristics of the raw materials, reaction conditions, and equipment operation, the conversion rate of the six-membered ring structure in the secondary reaction solution is predicted, and the amount of maleic anhydride added and the circulation intensity are adjusted in advance.

[0046] The secondary circulation structure is connected to the secondary reactor at two ends and at the other end. The secondary circulation structure includes a secondary circulation pump, a secondary level sensor, a secondary heat exchanger, and a switch. The main function of the secondary circulation pump is to provide power to circulate the secondary reaction liquid within the secondary reactor, extracting the secondary reaction liquid from the bottom of the reactor and transporting it through pipelines to the secondary heat exchanger and other equipment, ensuring uniform mixing of materials within the reaction system. In this embodiment, adding maleic anhydride to the secondary reactor circulation allows the newly added reactant to quickly mix with other materials in the system, maintaining stable reaction progress. The secondary heat exchanger controls the temperature of the maleic anhydride at 190~210℃.

[0047] The secondary liquid level sensor measures whether the secondary reaction liquid is below the preset threshold. If so, switch 2 is opened, and the secondary reaction liquid is input into the reaction maturation vessel.

[0048] The specific steps for constructing a machine learning-based model to predict the conversion rate of six-membered ring structures in a second-order reaction solution are as follows: The specific steps for predicting the conversion rate of the six-membered ring structure in the second-stage reaction solution based on the initial and added maleic anhydride concentrations in the first-stage reaction solution are as follows: A machine learning-based conversion rate prediction model for a six-membered ring structure was established by collecting and preprocessing historical environmental data. Raw material characteristics, reaction condition characteristics, and equipment operation characteristics were extracted from the historical reaction data. These characteristics were used as inputs, and the conversion rate of the six-membered ring structure was used as the output to train the conversion rate prediction model. Model parameters that meet the test accuracy were retained.

[0049] Historical environmental data is divided into training and test sets according to a preset ratio. The conversion rate prediction model is trained using the training set and validated using the test set. Once the model achieves the required accuracy on the test set, its output prediction value is used as the base prediction value Y0.

[0050] The composition characteristics of the reaction solution include the initial concentration of maleic anhydride C1 in the primary reaction solution and the concentration of supplemented maleic anhydride C2.

[0051] The predicted conversion rate Y of the six-membered ring structure is expressed as:

[0052] In the formula, Y0 is the model's basic predicted value, α is the concentration influence coefficient, C1 is the initial concentration of maleic anhydride in the first-stage reaction solution, C2 is the concentration of supplemented maleic anhydride, t is the second-stage reaction time, and k is the time correction index.

[0053] The predicted amount of maleic anhydride to be added and the cycle intensity were calculated based on the conversion rate of the six-membered ring structure.

[0054] The predicted amount of maleic anhydride to be added, ΔM, and the circulation rate, v, were calculated based on the conversion rate of the six-membered ring structure.

[0055] The formula for calculating the amount of maleic anhydride to be added, ΔM, is as follows:

[0056] In the formula, M0 represents the amount of maleic anhydride added based on the base amount. To achieve the target conversion rate, This represents the reaction efficiency coefficient of maleic anhydride.

[0057] The formula for calculating the cycle rate v is expressed as:

[0058] In the formula, v0 is the original basic circulation flow, that is, the initial flow value without considering the conversion rate.

[0059] A plug flow reactor is used for maturation to reduce the residual maleic anhydride to 0.05%, avoiding the impact of residual maleic anhydride sublimation on the stability of the column operation, especially solving the problem of vapor phase blockage and achieving continuous operation of the column. The secondary reaction liquid is further reacted in the reaction maturation vessel to obtain crude maleic anhydride rings. The primary reactor, secondary reactor and reaction maturation vessel adopt gradient heating, and the temperature of the reaction maturation vessel is controlled at 200~220℃. The reaction temperature is inversely proportional to the concentration of maleic anhydride, which reduces the self-polymerization of maleic anhydride and reduces product by-products. The maturation time in the plug flow maturation vessel is 5~15 hours. After the reaction is completed, the crude maleic anhydride rings are conveyed to the distillation column through the discharge structure.

[0060] The unloading structure includes a liquid level sensor and a reaction unloading pump. The crude maleic anhydride product output from the bottom of the reaction maturation vessel enters the reaction unloading pump. The liquid level sensor measures whether the crude maleic anhydride product is below a preset threshold. If so, it sends a command to start the reaction unloading pump, which transports the crude maleic anhydride product in the reaction maturation vessel to the distillation column.

[0061] The amount of crude maleic anhydride ring in the reaction maturation vessel was calculated based on the predicted conversion rate Y of the six-membered ring structure. 粗 .

[0062]

[0063] In the formula, This represents the original mass of maleic anhydride in the primary reaction solution. λ represents the mass of maleic anhydride added, and λ represents the material loss rate.

[0064] The crude maleic anhydride ring is separated by distillation in a distillation column, and the fine maleic anhydride ring is obtained from the bottom of the column based on the quality prediction of the crude maleic anhydride ring.

[0065] The top buffer tank in the recycling structure utilizes the principle of natural gas-phase rise and liquid-phase gravity settling to achieve preliminary gas-liquid separation. Trace amounts of non-condensable gases with extremely low boiling points are discharged from the top gas phase outlet and extracted by a vacuum system. This vacuum system is linked to the gas phase outlet of the top buffer tank; continuous vacuuming removes non-condensable gases promptly, preventing their accumulation within the system and impacting separation efficiency. It also provides a stable, slightly negative pressure environment for the distillation column, lowering the boiling points of olefins and maleic anhydride, reducing high-temperature pyrolysis side reactions, ensuring smooth vaporization and separation of the light components at the top of the column, and improving the separation accuracy of the components. The top buffer tank maintains the slightly negative pressure environment of the system, promoting vapor-liquid balance within the distillation column. The liquid phase containing olefins and a small amount of maleic anhydride collects at the bottom of the buffer tank, forming a reusable liquid material. After the olefin pump monitors the buffer tank and the liquid phase material reaches the start-up level, it accurately extracts the bottom liquid phase and transports it through pipelines to the reactor inlet of the next maleic anhydride cycloaddition process. There, it is mixed with fresh olefins and maleic anhydride raw materials and continues to participate in the cycloaddition reaction, realizing closed-loop utilization of raw materials and reducing the consumption of purchased raw materials.

[0066] Distillation columns separate mixtures into components with different boiling points through multiple vaporization and condensation processes. A bottom circulation pump draws a portion of the liquid from the bottom of the distillation column, recycling a portion back into the column to ensure a stable feed volume and appropriate liquid level, allowing for continuous and stable distillation operations. Without the bottom circulation pump maintaining feed balance, the liquid level in the column might continuously drop, affecting the separation efficiency and stability of the distillation column, and even causing the distillation process to fail. When the liquid drawn by the bottom circulation pump returns to the distillation column, it comes into full contact with the rising vapor inside the column. During this process, more thorough heat and mass exchange occurs between the liquid and vapor. This helps improve the separation effect of the distillation column, resulting in higher purity products at the top and bottom of the column, thereby improving the overall product quality of the maleic anhydride cycloaddition process.

[0067] The bottom product obtained from the distillation column is a relatively high-purity maleic anhydride cyclic fine product. A bottom circulation pump circulates a portion of the liquid from the bottom of the column to maintain material balance and heat and mass transfer efficiency within the distillation column, while the remaining portion is output as product. After cooling and other treatments, the output maleic anhydride cyclic fine product is collected, stored, and packaged as the final product to meet subsequent sales or usage needs.

[0068] The specific steps for obtaining the quality of the fine maleic anhydride ring from the bottom of the prediction tower based on the quality of the crude maleic anhydride ring are as follows: The mass fraction ω of the target six-membered ring product in the crude maleic anhydride product was determined by high performance liquid chromatography. 目标 .

[0069] Collect process parameters of the distillation column, including the top temperature T. 顶 Temperature at the bottom of the tower T 底 Tower top pressure P顶 Pressure P at the bottom of the tower 底 Reflux ratio R.

[0070] Based on the mass fraction ω of the target six-membered ring product in the crude product 目标 Calculate the bottom recovery rate of the target product using the distillation column process parameters. .

[0071] Based on the crude product quality and the mass fraction of the target six-membered ring product in the crude product, ω 目标 Calculate the theoretical mass m of the target product that can be converted into the fine product from the crude product. 理论 .

[0072] The formula for calculating the quality of the fine rings of maleic anhydride obtained at the bottom of the tower is expressed as follows:

[0073] In the formula, γ is the residual coefficient of trace impurities at the bottom of the tower.

[0074] The specific steps for adjusting the process parameters of the distillation column based on the quality of maleic anhydride cyclic fines are as follows: Calculate the theoretical mass m of the target product 理论 The quality difference value between the product and the maleic anhydride ring-fine product.

[0075] The reasons for the discrepancies include: The reaction itself was not fully completed. Specifically, the reaction temperature and pressure conditions were not optimal, resulting in some maleic anhydride failing to convert successfully into the target six-membered ring structure product. This led to a lower actual product yield than theoretically expected. Increasing the bottom temperature of the distillation column provides more heat to the incoming materials, promoting further reaction and conversion of unreacted feedstock, thus increasing the yield of the target product. Insufficient reaction time also caused some feedstock to enter subsequent processes before participating in the reaction, affecting the final product yield. This can be addressed by adjusting the residence time of the materials in the column and reducing the feed rate to allow more time for reaction and separation, thereby improving the yield and quality of the final product.

[0076] Improper settings of temperature, pressure, and reflux ratio at the top and bottom of a distillation column can directly affect separation efficiency. Inadequate temperature control may prevent accurate separation of the target product from impurities and unreacted raw materials based on the differences in boiling points, leading to the loss of some target product with other substances and impurities contaminating the final collected maleic anhydride ring concentrate, resulting in a discrepancy between the actual and theoretical product quality. If excessively high top temperatures cause loss due to product volatilization, the top temperature should be appropriately lowered to allow for better enrichment of the target product at the bottom of the column.

[0077] An inappropriate reflux ratio can also affect the gas-liquid balance and mass transfer efficiency within the column, thus impacting product purity and yield, ultimately resulting in quality variations. If product purity is insufficient, the reflux ratio can be appropriately increased to enhance mass transfer and separation within the column, thereby improving product purity. Conversely, if an excessively high reflux ratio leads to reduced production efficiency, the reflux ratio should be appropriately decreased. The specific structural condition of the distillation column, including tray blockage and packing performance, also affects separation efficiency. Tray blockage impairs gas-liquid contact; cleaning the trays or replacing substandard packing can restore the distillation column's optimal separation performance.

[0078] Example 2 Specific examples of the reaction between maleic anhydride and 5-dodecene: Prepare appropriate amounts of maleic anhydride, fresh 5-dodecene, and recycled 5-dodecene, and mix them in a mass ratio of 2:1 to form a mixture to be reacted.

[0079] The above mixture is fed into the primary reactor via a Venturi injector. After the reaction is started, the reaction liquid is heated by steam through the primary heat exchanger, gradually increasing the temperature until it stabilizes within a suitable reaction temperature range of 180-200℃. At this temperature, maleic anhydride and 5-dodecene begin to react. After the reaction is complete, the primary circulation pump starts operating, extracting the primary reaction liquid from the bottom of the primary reactor and transporting it through pipelines to the primary heat exchanger and other equipment. The flow rate of the primary circulation pump is set to 5 m³ / s. 3 The reaction proceeds more fully, producing a primary reaction solution containing poly(5-dodecene-alt-maleic anhydride) and small amounts of unreacted raw materials and byproducts. A primary level sensor monitors the liquid level in real time. When the liquid level is below 1 / 3 of the total height of the reactor, the switch is turned on, and the primary reaction solution is fed into the secondary reactor.

[0080] The secondary reactor receives the primary reaction liquid from the primary reactor and adds maleic anhydride in a certain amount. The amount of maleic anhydride added this time is set at 10 kg, and the basic amount of maleic anhydride added is M0. After the addition, the reaction continues.

[0081] The secondary reactor receives the primary reaction liquid and adds maleic anhydride, with the basic amount of maleic anhydride added set at M0 = 20 kg.

[0082] The raw material characteristics were extracted. The initial concentration of maleic anhydride in the primary reaction solution, C1, was 30%, and the concentration of maleic anhydride added in this supplementary reaction, C2, was 40%, which were used as inputs. The conversion rate of the six-membered ring structure was used as the output for model training. The training set and the test set were divided into 80%:20%. After training, when the model reached the required accuracy on the test set, the basic predicted value Y0 was obtained as 0.7. Assuming the concentration influence coefficient α = 0.1, the secondary reaction time t = 2 hours, and the time correction index k = 0.6, according to the formula... The calculated predicted conversion rate Y of the six-membered ring structure in the secondary reaction solution is 0.85875.

[0083] The predicted adjustment amount of maleic anhydride to be added and the circulation rate v are calculated based on the predicted conversion rate. For example, the target conversion rate Y is set. t =0.9, maleic anhydride reaction efficiency coefficient K M =0.8, according to the formula Therefore, ΔM is 1.11 kg.

[0084] The original basic circulation flow rate was set to v0 = 8m. 3 / h, calculated using the corresponding cycle rate formula We can obtain v as 9.18m. 3 / h.

[0085] The secondary reaction solution enters the reaction maturation vessel for further reaction. Assuming the original maleic anhydride mass in the primary reaction solution is m1 = 100 kg, the added maleic anhydride mass is m2 = 20 + 1.11 = 21.11 kg, and the material loss rate is λ = 0.03, according to the formula... The yield of crude maleic anhydride ring is approximately 100.23 kg.

[0086] High-performance liquid chromatography (HPLC) was used to detect the crude maleic anhydride ring entering the distillation column, and the mass fraction of 5-dodecene-alt-maleic anhydride in the crude product was found to be ω = 0.75. Simultaneously, process parameters of the distillation column were collected, including the column top temperature T. 顶 =155℃, bottom temperature of the tower T 底 =225℃, tower top pressure P 顶 =12kPa, pressure at the bottom of the tower P 底 =15kPa, reflux ratio R=3.5.

[0087] The bottom recovery rate of the target product is obtained through a specific calculation formula. =0.88.

[0088] Based on the crude product mass mcrude = 100.23 kg and ω... 目标 =0.75 Calculate the theoretical mass of the target product that can be converted into the fine product from the crude product. The theoretical crude target is 75.1725 kg.

[0089] Assuming the residual coefficient of trace impurities at the bottom of the column is γ = 0.02, the formula is used to... The yield is mfine = 64.54 kg. The distillation column separates the mixture based on the differences in boiling points of its components through multiple vaporization and condensation processes. The top buffer tank utilizes the principle of natural gas-phase rise and liquid-phase gravity settling to achieve initial gas-liquid separation. A trace amount of non-condensable gas is extracted through a vacuum system to maintain a slightly negative pressure environment. The liquid phase, containing 1,3-butadiene and a small amount of maleic anhydride, collects at the bottom of the buffer tank and is then pumped by an olefin pump to the reactor inlet for the next reaction, achieving closed-loop utilization of the raw materials.

[0090] In summary, this embodiment provides an optimized method for the maleic anhydride cycloaddition process. By adopting a dual-loop reactor + ripening reactor series process, the device can be operated continuously. The strong mass transfer effect of the loop reactor improves the cycloaddition efficiency, eliminates the need for catalysts, and reduces the impact of catalyst separation and residue.

[0091] By using a gradient addition of maleic anhydride in the primary and secondary reactors, the concentration of maleic anhydride in the primary reactor is controlled at a relatively low and reasonable level. This effectively inhibits the occurrence of self-polymerization, ensures the purity of the reaction system and the normal progress of the reaction, reduces material discharge losses and lowers the amount of new raw materials added. While improving the economic efficiency of the process, it also helps to achieve more efficient continuous production of the maleic anhydride cycloaddition process by shortening the material turnover process and enhancing gas-liquid separation efficiency.

[0092] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of various embodiments or some parts of embodiments.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An optimization method for a maleic anhydride cycloaddition process, characterized in that, The method comprises the following steps: The olefin, the recycled olefin and the maleic anhydride mixture are input into a first reactor through a Venturi ejector and are reacted and converted, so that the maleic anhydride is converted into a six-membered ring structure to obtain a first reaction liquid; A second reactor receives the first reaction liquid and additional maleic anhydride for reaction, and the conversion rate of the six-membered ring structure in the second reaction liquid is predicted according to the initial concentration of the maleic anhydride in the first reaction liquid and the concentration of the additional maleic anhydride. A reaction maturation kettle receives the second reaction liquid and increases the temperature of the second reaction liquid, so that the maleic anhydride that is not completely converted in the second reaction liquid and the olefin continue to undergo a cycloaddition reaction, the quality of the maleic anhydride ring crude product is calculated according to the conversion rate of the six-membered ring structure. The maleic anhydride ring crude product is separated by a rectifying column, the quality of the maleic anhydride ring fine product at the bottom of the column is predicted according to the quality of the maleic anhydride ring crude product, and the process parameters of the distillation column are adjusted according to the quality of the maleic anhydride ring fine product.

2. An optimization method for a maleic anhydride cycloaddition process according to claim 1, characterized in that, The second reaction liquid output from the bottom of the second reactor is input into the top of the second reactor through a second circulating pump and a second heat exchanger, and it is determined whether the second reaction liquid is lower than a preset second threshold value; if yes, a second switch is opened, and the second reaction liquid is input into the reaction maturation kettle.

3. An optimization method for a maleic anhydride cycloaddition process according to claim 1, characterized in that, The maleic anhydride crude product output from the bottom of the reaction maturation kettle is input into a reaction discharge pump, and it is determined whether the maleic anhydride crude product is lower than a preset third threshold value; if yes, the reaction discharge pump is started, and the maleic anhydride crude product in the reaction maturation kettle is transported to the rectifying column.

4. An optimization method for a maleic anhydride cycloaddition process according to claim 1, characterized in that, The specific steps for predicting the conversion rate of the six-membered ring structure in the second reaction liquid are as follows: A conversion rate prediction model of the six-membered ring structure in the second reaction liquid based on machine learning is constructed; Historical environmental data are collected and preprocessed; The preprocessed historical environmental data are subjected to feature extraction to obtain raw material features, reaction condition features and equipment operation features; The historical environmental data are divided into a training set and a test set according to a preset ratio, the conversion rate prediction model is trained by using the training set, and the test set is used for verification until the test accuracy meets a preset accuracy, and the corresponding model parameters are reserved; The raw material features in the near future are input into the conversion rate prediction model to obtain a predicted conversion rate Y of the six-membered ring structure; The predicted adjustment amount of the additional maleic anhydride and the predicted circulation intensity are calculated according to the conversion rate of the six-membered ring structure.

5. An optimization method for a maleic anhydride cycloaddition process according to claim 4, characterized in that, The predicted conversion rate Y of the six-membered ring structure is expressed as follows: ； In the formula, Y0 is a basic prediction value of the model, α is a concentration influence coefficient, C1 is the initial concentration of the maleic anhydride in the first reaction liquid, C2 is the concentration of the additional maleic anhydride, t is the second reaction time, and k is a time correction index.

6. An optimization method for a maleic anhydride cycloaddition process according to claim 1, characterized in that, The calculation formula for calculating the quality of the maleic anhydride ring crude product according to the conversion rate of the six-membered ring structure is expressed as follows: ； In the formula, is the mass of maleic anhydride originally contained in the first reaction solution, is the mass of maleic anhydride added.

7. An optimization method for a maleic anhydride cycloaddition process according to claim 1, characterized in that, The specific steps for predicting the quality of the maleic anhydride ring fine product at the bottom of the column according to the quality of the maleic anhydride ring crude product are as follows: The mass fraction ω of the target six-membered ring product in the crude product is detected by high performance liquid chromatography on the maleic anhydride ring crude product 目标 ; Collecting the overhead temperature T of the rectification column 顶 , the bottom temperature T 底 , the overhead pressure P 顶 , the bottom pressure P 底 , the reflux ratio R; According to the mass fraction ω of the target six-membered ring product in the crude product 目标 and the rectification column process parameters to calculate the bottom recovery rate of the target product ; According to the mass of the crude product and the mass fraction ω of the target six-membered ring product in the crude product 目标 The theoretical mass m of the target product that can be converted from the crude product is calculated 理论 ; The calculation formula for obtaining the quality of the maleic anhydride ring fine product at the bottom of the column is expressed as follows: ； In the formula, γ is a trace impurity residue coefficient at the bottom of the column.

8. An optimization method for a maleic anhydride cycloaddition process according to claim 1, characterized in that, In the recycling structure, the olefin and trace maleic anhydride are preliminarily separated in a gas-liquid manner in a top buffer tank, the gas phase after the separation is discharged from the top to a vacuum system, and the liquid phase remains at the bottom of the buffer tank and is used for the next maleic anhydride cycloaddition process by an olefin pump.

9. An optimization method for a maleic anhydride cycloaddition process according to claim 1, characterized in that, The specific steps for adjusting the process parameters of the distillation column according to the quality of the maleic anhydride ring fine product are as follows: Theoretical mass m of the calculated target product 理论 And the mass difference value of the maleic anhydride ring product The causes of the difference value are analyzed; Adjusting distillation column process parameters in accordance with the cause.

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