A method and device for establishing a flue gas circulation regeneration system model

Abstract

A flue gas circulation regeneration system model establishment method and device, comprising the following steps: S1, establishing a coke burning reaction kinetics model: based on carbon and hydrogen burning reactions, a coke burning reaction rate equation is established; S2, establishing a flue gas circulation regeneration system steady-state model, according to the flue gas circulation regeneration process, a regenerator steady-state model is established, and the CO, CO2, H2O and O2 flow rates in the regenerated flue gas and the coke content of the regenerated catalyst are calculated according to the regenerator steady-state model; S3, flue gas circulation regeneration optimization: target optimization is performed on the enrichment of carbon dioxide and the regeneration effect of the spent catalyst; in the S2, the CO, CO2, H2O and O2 flow rates in the regenerated flue gas are calculated by taking the CO, CO2, H2O and O2 flow rates in the flue gas at the outlet of the regenerator as the starting point and combining sufficient coke burning during the establishment process of the regenerator steady-state model. The present application breaks the cycle dependence, has high prediction accuracy and small calculation amount.

Description

Technical Field

[0001] This invention relates to the field of petrochemical technology, specifically to a method and apparatus for establishing a flue gas recirculation system model. Background Technology

[0002] The oil refining process is a significant source of carbon dioxide emissions in the petroleum and petrochemical industry. Among these, catalytic cracking units have the highest carbon dioxide emissions of all types of refining units. Therefore, it is crucial to reduce carbon dioxide emissions from catalytic cracking units and improve their carbon dioxide capture and recovery efficiency.

[0003] Flue gas recirculation (FGR) regeneration technology refers to using a mixture of oxygen and carbon dioxide instead of traditional air as the main airflow in the regenerator. This mixture contacts the spent catalyst for coke combustion and regeneration. By optimizing the oxygen and circulating flue gas flow rates, this process obtains high-purity carbon dioxide, improving carbon dioxide recovery and utilization efficiency. Establishing a FGR regeneration system model allows for optimization of oxygen and circulating flue gas flow rates under different regeneration conditions, resulting in high-purity carbon dioxide flue gas and achieving better regeneration effects.

[0004] In 2022, the applicant filed a patent application for a modeling method and apparatus for a catalytic cracking flue gas recirculation and regeneration system (patent number: CN114818359A). This method provides a kinetic model of the catalytic cracking regeneration process, predicts the optimal oxygen flow rate and recirculation ratio of the regenerated flue gas, predicts the composition of the regenerated flue gas, and determines the carbon content of the regenerated catalyst, thereby achieving efficient carbon dioxide capture. However, this modeling method relies on the calculation results of the flue gas recirculation and regeneration system model, which in turn depends on the initial values ​​of the model. This means the modeling method suffers from a cyclic dependency problem, resulting in low accuracy of the predictions and even causing calculation termination. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method and apparatus for establishing a flue gas recirculation system model, which breaks the cycle dependency, achieves high prediction accuracy, and requires minimal computation.

[0006] To achieve the above objectives, the specific solution adopted by the present invention is as follows: a method for establishing a flue gas recirculation and regeneration system model, comprising the following steps:

[0007] S1, Establish a kinetic model for the coking reaction: Establish the coking reaction rate based on the carbon burning and hydrogen burning reactions;

[0008] S2. Establish a steady-state model of the flue gas recirculation and regeneration system. Based on the flue gas recirculation and regeneration process, establish a steady-state model of the regenerator. Calculate the flow rates of CO, CO2, H2O, and O2 in the regenerated flue gas and the coke content of the catalyst after regeneration based on the steady-state model of the regenerator.

[0009] S3, Flue gas recirculation and regeneration optimization: Target optimization of carbon dioxide enrichment and the regeneration effect of the spent catalyst;

[0010] In S2, during the establishment of the regenerator steady-state model, the flow rates of CO, CO2, H2O, and O2 in the regenerated flue gas at the regenerator outlet are used as the starting point, combined with the setting of sufficient coking, to calculate the flow rates of CO, CO2, H2O, and O2 in the regenerated flue gas. When the O2 flow rate in the regenerated flue gas meets the coking requirement, the flow rates of CO, CO2, H2O, and O2 in the regenerated flue gas are:

[0011] Among them, F cat For regenerant flow rate, Carbon determination for the catalyst to be generated. The hydrogen content of coke, The molar flow rate of pure oxygen;

[0012] When the O2 flow rate in the regenerated flue gas does not meet the coking requirements, the CO, CO2, H2O, and O2 flow rates in the regenerated flue gas are:

[0013]

[0014] Among them, F cat For regenerant flow rate, Carbon determination for the catalyst to be generated. The hydrogen content of coke, The molar flow rate is for pure oxygen.

[0015] As an optimized scheme for establishing the above-mentioned flue gas recirculation system model: In S1, the process of establishing the coking reaction rate function based on the coke molar concentration and oxygen molar concentration is as follows: The reaction of carbon and hydrogen elements occurring in the dense phase bed is as follows:

[0016]

[0017] Where r1, r2, and r3 represent the reaction rates when carbon is oxidized to CO, CO2, and H is oxidized to H2O, respectively;

[0018] Within the dense phase bed, r1, r2, and r3 are respectively:

[0019]

[0020] Where k1 is the rate constant for the combustion of C, and k2 is the rate constant for the combustion of H to produce H2O, in m³ / s. 3 / (kmol·s), σ represents the molar ratio of CO2 to CO produced, in kmol / kmol, ρ c This indicates the density of catalyst particles in a dense-phase bed, expressed in kg·m³. -3, ε c，D Indicates the volume fraction of the dense-phase bed catalyst; w ck This indicates the coke content on the catalyst, expressed in kg coke / kg catalyst, in MW. C The molar molecular mass of carbon is expressed in kg / mol (MW). H The molar mass of hydrogen is expressed in kg / mol, and q is the hydrogen-to-carbon molar ratio in coke; c i，j Let i be the molar concentration of gaseous component i in region j, in kmol / m³. 3 Region j corresponds to region D of the dense phase bed or region F of the dilute phase. Gas component i includes CO, CO2, H2O, O2, and N2, in kmol / m³. 3 ;

[0021] In a dense-phase bed, the CO generated from carbon will continue to be oxidized to CO2, and the reaction rate is:

[0022]

[0023] Where k3 is the reaction rate constant for the oxidation of CO to CO2 in a dense-phase bed, and c i，D The molar concentration of the gas in the dense phase bed:

[0024] Where, n i，D v represents the molar flow rate of each gas component in the dense phase bed. g，D The volumetric flow rate of each gas component in the dense phase bed;

[0025] If only CO is oxidized in a dilute phase bed, then the CO oxidation rate in the dilute phase bed is:

[0026]

[0027] Where k4 is the reaction rate constant for the oxidation of CO to CO2 in the dilute phase, and c i，F The molar concentrations of each gas component in the dilute phase bed are as follows:

[0028]

[0029] Where, n i，F v represents the molar flow rate of each gas component in the dilute phase bed. g，F denoted as , where is the volumetric flow rate of each gas component in the dilute phase bed.

[0030] As an alternative optimization scheme for establishing the above-mentioned flue gas recirculation system model, the σ is obtained from an empirical formula:

[0031]

[0032] Where T is the temperature of the dense phase bed inside the regenerator, in K.

[0033] As an alternative optimization scheme for the above-mentioned method of establishing a flue gas recirculation system model: the ε c，D for:

[0034]

[0035] Among them, v g，D Ω represents the volumetric flow rate of each gas component in the dense phase bed. RG The cross-sectional area of ​​the dense phase bed in the regenerator;

[0036] The ε g，D for:

[0037] ε g，D =(1-ε c，D ).

[0038] As another optimization scheme for the above-mentioned method of establishing a flue gas regeneration system model: the reaction rate constant k i for:

[0039]

[0040] Where, k i0 and E i Here, T represents the pre-exponential factor and activation energy of the reaction, respectively; T is the regeneration temperature; R is the ideal gas constant; and T* is the reference regeneration temperature.

[0041] As an alternative optimization scheme for the above-mentioned method of establishing a flue gas recirculation and regeneration system model: In S2, the steady-state model of the flue gas recirculation and regeneration system is established as follows: material balance is performed on the gas in the dense phase bed of the regenerated flue gas, and the height of the dense phase bed is set to remain constant, so as to obtain the equation for the rate of change of the molar flow rate of each gas component in the dense phase bed along the axial direction:

[0042]

[0043]

[0044]

[0045] Where, r 1，D r represents the reaction rate of C combustion to CO in a dense-phase bed. 2，D r represents the reaction rate of C combustion to CO2 in a dense-phase bed. 3，D r represents the reaction rate of H combustion to H2O in a dense-phase bed. 4，D The reaction rate of CO combustion to CO2 in a dense-phase bed is given in meters. 3 / (kmol·s), σ represents the molar ratio of CO2 to CO produced, in kmol / kmol, ρ c This indicates the density of catalyst particles in a dense-phase bed, expressed in kg·m³. -3 , ε c，D Indicates the volume fraction of the dense-phase bed catalyst; w ck This indicates the coke content on the catalyst, expressed in kg coke / kg catalyst, in MW. C The molar molecular mass of carbon is expressed in kg / mol (MW). H The molar mass of hydrogen is expressed in kg / mol, and q is the hydrogen-to-carbon molar ratio in coke; c i，D The molar concentration of gaseous component i in a dense phase bed, in kmol / m³. 3 The gaseous components i include CO, CO2, H2O, O2, and N2, with units of kmol / m³. 3 n i，D v represents the molar flow rate of each gas component in the dense phase bed. g，D Let Z be the volumetric flow rate of each gas component in the dense phase bed, and Z be the dimensionless relative distance at section z in the dense phase bed.

[0046] The initial values ​​for the molar flow rates of each gas component are:

[0047]

[0048] in, c represents the fresh oxygen flow rate at the main air inlet of the regenerator, and c represents the recirculated flue gas in the regenerator.

[0049] The equation for the rate of change of the molar flow rate of each gas component in the dilute bed along the axial direction is:

[0050]

[0051]

[0052]

[0053]

[0054] Where k4 is the CO oxidation reaction rate in the dilute phase bed, and c i，F n represents the molar concentration of each gas component in the dilute phase bed. i，F v represents the molar flow rate of each gas component in the dilute phase bed. g，F V represents the volumetric flow rate of each gas component in the dilute phase bed. F Let Z be the volume of the dilute phase bed, and Z be the dimensionless relative distance at section z in the dilute phase bed.

[0055] The gas molar flow rate at the inlet of the dilute phase bed is equal to the gas molar flow rate at the outlet of the dense phase bed.

[0056]

[0057] in, The molar flow rates of each gas component at the inlet of the dilute phase bed are given. denoted as , where represents the molar flow rate of each gas component at the outlet of the dense phase bed.

[0058] As an alternative optimization scheme for establishing the above-mentioned flue gas recirculation system model, the coke content of the regenerated catalyst is:

[0059]

[0060] in, Carbon determination for the catalyst to be generated. The molar flow rate of the gas components at the regenerator outlet. The molar flow rate of the gas component at the regenerator inlet.

[0061] As an alternative optimization scheme for establishing the above-mentioned flue gas recirculation and regeneration system model: In S2, the flow rates of CO, CO2, H2O, and O2 in the regenerated flue gas are:

[0062]

[0063]

[0064]

[0065]

[0066] Where X is the ratio of circulating flue gas flow rate to oxygen flow rate. This refers to the CO flow rate at the outlet of the flue gas purification device. The CO2 flow rate at the outlet of the flue gas purification device. This refers to the flow rate of H2O at the outlet of the flue gas purification device. This refers to the flow rate of O2 at the outlet of the flue gas purification device. This refers to the flow rate of pure oxygen.

[0067]

[0068]

[0069]

[0070]

[0071] in, CO flow rate at regenerator outlet This refers to the CO2 flow rate at the regenerator outlet. The H2O flow rate at the regenerator outlet. This refers to the O2 flow rate at the regenerator outlet. The volumetric content of H2O at the outlet of the flue gas purification device;

[0072]

[0073] Where T is the regeneration temperature.

[0074] An apparatus for establishing a flue gas recirculation and regeneration system model includes: a module for establishing a coking reaction kinetic model, used to establish a coking reaction rate equation based on carbon and hydrogen burning reactions; a module for establishing a flue gas recirculation and regeneration system steady-state model, used to establish a regenerator stability model according to the flue gas recirculation and regeneration process; and a flue gas recirculation and regeneration optimization module, used to optimize the enrichment of carbon dioxide and the regeneration effect of the catalyst to be regenerated.

[0075] An electronic device includes a processor and a memory, the memory storing computer-readable instructions, which, when executed by the processor, perform the steps of the method for establishing a flue gas recirculation system model described above.

[0076] A readable storage medium having a computer program stored thereon, which, when executed by a processor, performs the steps of the above-described method for establishing a flue gas recirculation system model.

[0077] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method and apparatus for establishing a flue gas regeneration system model. Taking the flow rates of CO, CO2, H2O and O2 in the regenerated flue gas at the regenerator outlet as the starting point, and combining the fully burned setting to calculate the flow rates of CO, CO2, H2O and O2 in the regenerated flue gas, it serves as the entry point for the cyclic dependency problem, breaks the cyclic dependency chain, and improves the accuracy of the prediction results. Detailed Implementation

[0078] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. Parts not described or disclosed in detail in the following embodiments of the present invention should be understood as prior art known or should be known by those skilled in the art.

[0079] Example 1

[0080] A method for establishing a flue gas recirculation system model includes the following steps:

[0081] S1. Establishing a kinetic model for the coking reaction: During the combustion reaction, the coking reaction rate is established based on the carbon and hydrogen burning reactions. The coking reaction rate is a function of the molar concentration of coke and the molar concentration of oxygen. The coke adhering to the surface of the deactivated catalyst is a mixture, mainly containing carbon (C) and hydrogen (H). During the combustion reaction, carbon is oxidized to produce CO and CO2, and hydrogen is oxidized to produce H2O. In this embodiment, when establishing the kinetic model of the coking reaction, elements such as nitrogen (N) and sulfur (S) in the coke are ignored, and only the carbon and hydrogen burning reactions are considered. That is, the coking reaction equation of the deactivated catalyst in the dense phase bed of the regenerator is:

[0082]

[0083] Where r1, r2, and r3 represent the reaction rates of carbon oxidation to CO, CO2, and H oxidation to H2O, respectively.

[0084] Then, r1, r2, and r3 within the dense phase bed are respectively:

[0085]

[0086] Where k1 is the rate constant for the combustion of C, and k2 is the rate constant for the combustion of H to produce H2O, in m³ / s. 3 / (kmol·s), σ represents the molar ratio of CO2 to CO produced, in kmol / kmol, ρ c This indicates the density of catalyst particles in a dense-phase bed, expressed in kg·m³. -3 , ε c，D Indicates the volume fraction of the dense-phase bed catalyst; w ck This indicates the coke content on the catalyst, expressed in kg coke / kg catalyst, in MW. C The molar molecular mass of carbon is expressed in kg / mol (MW). H The molar mass of hydrogen is expressed in kg / mol, and q is the hydrogen-to-carbon molar ratio in coke; c i，j Let i be the molar concentration of gaseous component i in region j, in kmol / m³. 3 Region j corresponds to region D of the dense phase bed or region F of the dilute phase. Gas component i includes CO, CO2, H2O, O2, and N2, in kmol / m³. 3 .

[0087] In this embodiment, the value of σ is calculated using an empirical formula:

[0088]

[0089] Where T is the temperature of the dense phase bed inside the regenerator, in K.

[0090] ε c，D ε represents the volume fraction of the dense-phase bed catalyst. g，D To mix other volume fractions in a dense phase bed, specifically:

[0091]

[0092] Among them, v g，D Ω represents the volumetric flow rate of each gas component in the dense phase bed. RG The cross-sectional area of ​​the dense phase bed in the regenerator;

[0093] ε g，D =(1-ε c，D ).

[0094] Reaction rate constant k i Calculated according to the Arrhenius equation:

[0095]

[0096] Where, k i0 and E i Here, T represents the pre-exponential factor and activation energy of the reaction, respectively; T is the regeneration temperature; R is the ideal gas constant (8.314 kJ / (kmol·K)); and T* is the reference regeneration temperature.

[0097] The CO produced by the carbon element reaction will be further oxidized to CO2. This reaction can occur in both dense-phase and dilute-phase beds. The reaction equation for CO produced by the carbon element reaction in a dense-phase bed is as follows:

[0098]

[0099] The reaction rate of this reaction is:

[0100]

[0101] Where k3 is the reaction rate constant for the oxidation of CO to CO2 in a dense-phase bed, and c i，D The molar concentration of the gas in the dense phase bed:

[0102]

[0103] Where, n i，D v represents the molar flow rate of each gas component in the dense phase bed. g，D denoted as , where is the volumetric flow rate of each gas component in the dense phase bed.

[0104] In a dilute phase bed, no charring reaction occurs, only the oxidation of CO. Therefore, the rate of CO oxidation in the dilute phase bed is:

[0105]

[0106] Where k4 is the reaction rate constant for the oxidation of CO to CO2 in a dilute bed, and c i，F The molar concentrations of each gas component in the dilute phase bed are expressed in kmol / m³. 3 .

[0107]

[0108] Where, n i，F v represents the molar flow rate of each gas component in the dilute phase bed. g，F denoted as , where is the volumetric flow rate of each gas component in the dilute phase bed.

[0109] S2. Establish a steady-state model of the flue gas recirculation and regeneration system. Based on the flue gas recirculation and regeneration process, calculate the flow rates of CO, CO2, H2O, and O2 in the regenerated flue gas, as well as the coke content of the regenerated catalyst, according to the steady-state model of the regenerator. In the flue gas recirculation and regeneration process, the flue gas generated from coking exits the regenerator and passes through a flue gas purification device to remove pollutants such as S and N, as well as dust. Then, a portion of the flue gas is recirculated back to the main air inlet of the regenerator and mixed with high-purity oxygen. This mixture of flue gas and high-purity oxygen is then used as the main air to enter the regenerator for coking. Based on the coking reaction kinetic model and the flue gas recirculation and regeneration system, establish a steady-state model of the regenerator. The gases in the regenerator include O2, CO, CO2, and H2O. Perform material balance calculations on the gases in the dense phase bed, assuming a constant dense phase bed height, to obtain the equations for the rate of change of the molar flow rate of each gas component along the axial direction:

[0110]

[0111]

[0112]

[0113] Where, r 1，D r represents the reaction rate of C combustion to CO in a dense-phase bed. 2，D r represents the reaction rate of C combustion to CO2 in a dense-phase bed. 3，D r represents the reaction rate of H combustion to H2O in a dense-phase bed. 4，D V represents the reaction rate of CO combustion to CO2 in a dense-phase bed. D Where k is the volume of the dense bed, k1 is the rate constant for the combustion of C, and k2 is the rate constant for the combustion of H, in m³. 3 / (kmol·s), σ represents the molar ratio of CO2 to CO produced, in kmol / kmol, ρ c This indicates the density of catalyst particles in a dense-phase bed, expressed in kg·m³. -3 , ε c，D Indicates the volume fraction of the dense-phase bed catalyst; w ckThis indicates the coke content on the catalyst, expressed in kg coke / kg catalyst, in MW. C The molar molecular mass of carbon is expressed in kg / mol (MW). H The molar mass of hydrogen is expressed in kg / mol, and q is the hydrogen-to-carbon molar ratio in coke; c i，D The molar concentration of gaseous component i in a dense phase bed, in kmol / m³. 3 The gaseous components i include CO, CO2, H2O, O2, and N2, with units of kmol / m³. 3 n i，D v represents the molar flow rate of each gas component in the dense phase bed. g，D Z is the volumetric flow rate of each gas component in the dense phase bed, and Z is the dimensionless relative distance at section z in the dense phase bed, Z = z / Z D Z D The height of the dense phase bed is expressed in meters (m).

[0114] The initial values ​​for the molar flow rates of each gas component in the dense phase bed are:

[0115]

[0116] in, c represents the fresh oxygen flow rate at the main air inlet of the regenerator, and c represents the recirculated flue gas in the regenerator.

[0117] If all the gas in the dilute phase bed originates from the dense phase bed, including CO, CO2, and H2O generated by the coking reaction, then the equation for the rate of change of the molar flow rate of each gas component in the dilute phase bed along the axial direction is:

[0118]

[0119]

[0120]

[0121]

[0122] Where k4 is the reaction rate constant for the oxidation of CO to CO2 in a dilute bed, and c i，F n represents the molar concentration of each gas component in the dilute phase bed. i，F v represents the molar flow rate of each gas component in the dilute phase bed. g，F V represents the volumetric flow rate of each gas component in the dilute phase bed. F Let Z be the volume of the dilute phase bed, and Z be the dimensionless relative distance at section z in the dilute phase bed.

[0123] Based on the continuity of gas flow, the gas molar flow rate at the inlet of the dilute phase bed is equal to the gas molar flow rate at the outlet of the dense phase bed:

[0124]

[0125] in, The molar flow rate of each gas component at the inlet of the dilute phase bed is expressed in kmol·s. -1 , The molar flow rate of each gas component at the outlet of the dense phase bed is expressed in kmol·s. -1 .

[0126] The proportions of the various gaseous components in the flue gas are as follows:

[0127]

[0128] in, The molar flow rate of each gas component in the regenerated flue gas is expressed in kmol·s. -1 .

[0129] In this embodiment, the total flow rate of the circulating flue gas is set to... With oxygen flow The ratio is X, and the flow rates of CO, CO2, H2O, and O2 in the circulating flue gas are:

[0130]

[0131]

[0132]

[0133]

[0134] Where X is the ratio of circulating flue gas flow rate to oxygen flow rate. This refers to the CO flow rate at the outlet of the flue gas purification device. The CO2 flow rate at the outlet of the flue gas purification device. This refers to the flow rate of H2O at the outlet of the flue gas purification device. This refers to the flow rate of O2 at the outlet of the flue gas purification device. The molar flow rate of pure oxygen is expressed in kmol / s.

[0135] The calculation formula is:

[0136]

[0137]

[0138]

[0139]

[0140] in, CO flow rate at regenerator outlet This refers to the CO2 flow rate at the regenerator outlet. The H2O flow rate at the regenerator outlet. This refers to the O2 flow rate at the regenerator outlet. This refers to the volumetric content of H2O at the outlet of the flue gas purification device.

[0141] Volumetric content of H2O at the outlet of the flue gas purification device for:

[0142]

[0143] Where T is the regeneration temperature.

[0144] In the process of establishing the steady-state model of the regenerator, the flow rates of CO, CO2, H2O and O2 in the regenerated flue gas at the regenerator outlet are used as the starting point. Combined with the setting of full coking, the flow rates of CO, CO2, H2O and O2 in the regenerated flue gas are calculated to break the cycle dependence and improve the accuracy of the model.

[0145] For a single-stage regeneration system using flue gas recirculation, when the O2 flow rate in the regenerated flue gas meets the coke combustion requirement, the coke is completely combusted. The flow rates of CO, CO2, H2O, and O2 in the regenerated flue gas are:

[0146]

[0147] Among them, F cat For regenerant flow rate, Carbon determination for the catalyst to be generated. The hydrogen content of coke, The molar flow rate is for pure oxygen.

[0148] As a supplement to the fully combusted setting, when the O2 flow rate does not meet the combusting requirements, the CO, CO2, H2O, and O2 flow rates in the regenerated flue gas are:

[0149]

[0150] Among them, F cat For regenerant flow rate, Carbon determination for the catalyst to be generated. The hydrogen content of coke, The molar flow rate is for pure oxygen.

[0151] The above formula is used to calculate... The initial value, then, according to get Then the circulating flue gas flow rate is calculated. Then the initial value is obtained. The flow rates of each gas component in the regenerated flue gas were calculated based on the axial rate of change equations for the molar flow rates of each gas component in the dilute phase bed and the axial rate of change equations for the molar flow rates of each gas component in the dense phase bed.

[0152] The coke content of the regenerated catalyst is:

[0153]

[0154] in, Carbon determination for the catalyst to be generated. The molar flow rate of the gas components at the regenerator outlet. The molar flow rate of the gas component at the regenerator inlet is given.

[0155] S3, Flue Gas Recirculation and Regeneration Optimization: Target optimization is performed on the enrichment of carbon dioxide and the regeneration effect of the spent catalyst. By setting the CO2 content in the regenerated flue gas and the fixed carbon content of the regenerator, the oxygen flow rate and the recirculated flue gas flow rate can be optimized and calculated. Under the operating conditions of the calculated oxygen flow rate and recirculated flue gas flow rate, the CO2 content in the regenerated flue gas can be enriched to 95% wt%, and the fixed carbon content of the regenerator can be reduced to below 0.1% wt%.

[0156] Example 2

[0157] An apparatus for establishing a flue gas recirculation and regeneration system model includes a module for establishing a coking reaction kinetic model to establish the coking reaction rate based on carbon and hydrogen burning reactions; a module for establishing a steady-state model of the flue gas recirculation and regeneration system to establish a regenerator stability model according to the flue gas recirculation and regeneration process; and a flue gas recirculation and regeneration optimization module for optimizing the enrichment of carbon dioxide and the regeneration effect of the catalyst to be regenerated.

[0158] Example 3

[0159] An electronic device includes a processor and a memory, the memory storing computer-readable instructions, which, when executed by the processor, perform the steps of a method for establishing a flue gas recirculation system model as described in Embodiment 1.

[0160] Example 4

[0161] A readable storage medium having a computer program stored thereon, which, when executed by a processor, performs the steps of a method for establishing a flue gas recirculation system model as described in Example 1.

[0162] Application Example 1

[0163] This application was used to optimize oxygen flow rate and circulating flue gas flow rate. The catalytic cracking unit's processing capacity was set at 1 million tons / year, coke yield at 6.5 wt%, catalyst-to-oil ratio at 6.5, regenerator dense phase temperature at 690℃, and regenerator top pressure at 0.2 MPa. By optimizing the oxygen flow rate and circulating flue gas flow rate, the carbon dioxide content in the regenerated flue gas reached 95 wt%, and the fixed carbon content of the regenerated catalyst was reduced to 0.1 wt%. The oxygen flow rate, circulating flue gas flow rate and oxygen ratio, regenerated flue gas composition, and fixed carbon content of the regenerated catalyst were obtained, as shown in Table 1. In the flue gas recirculation regeneration process, the oxygen flow rate was set at 14842 Nm³. 3 / h, the ratio of circulating flue gas flow rate to oxygen flow rate is 3.64, and the carbon dioxide content in the regenerated flue gas after the reaction is 95.13v%, and the carbon content of the regenerated catalyst is 0.1w.

[0164] Application Example 2

[0165] This application was used to optimize oxygen flow rate and circulating flue gas flow rate. The catalytic cracking unit's processing capacity was set at 1 million tons / year, coke yield at 6.5 wt%, catalyst-to-oil ratio at 6.5, regenerator dense phase temperature at 690℃, and regenerator top pressure at 0.2 MPa. By optimizing the oxygen flow rate and circulating flue gas flow rate, the carbon dioxide content in the regenerated flue gas reached 96 wt%, and the fixed carbon content of the regenerated catalyst was reduced to 0.1 wt%. The oxygen flow rate, circulating flue gas flow rate and oxygen ratio, regenerated flue gas composition, and fixed carbon content of the regenerated catalyst were obtained, as shown in Table 1. In the flue gas recirculation regeneration process, the oxygen flow rate was set at 14974 Nm³. 3 / h, the ratio of circulating flue gas flow rate to oxygen flow rate is 3.91, and the carbon dioxide content in the regenerated flue gas after the reaction is 95.88v%, and the carbon content of the regenerated catalyst is 0.1w.

[0166] Application Example 3

[0167] This application was used to optimize oxygen flow rate and circulating flue gas flow rate. The catalytic cracking unit's processing capacity was set at 1 million tons / year, coke yield at 6.5 wt%, catalyst-to-oil ratio at 6.5, regenerator dense phase temperature at 690℃, and regenerator top pressure at 0.2 MPa. By optimizing the oxygen flow rate and circulating flue gas flow rate, the carbon dioxide content in the regenerated flue gas reached 97 wt%, and the fixed carbon content of the regenerated catalyst was reduced to 0.1 wt%. The oxygen flow rate, circulating flue gas flow rate and oxygen ratio, regenerated flue gas composition, and fixed carbon content of the regenerated catalyst were obtained, as shown in Table 1. In the flue gas recirculation regeneration process, the oxygen flow rate was set at 15179 Nm³. 3 / h, the ratio of circulating flue gas flow rate to oxygen flow rate is 4.45, and the carbon dioxide content in the regenerated flue gas after the reaction is 96.57v%, and the carbon content of the regenerated catalyst is 0.1w.

[0168] Application Example 4

[0169] This application was used to optimize oxygen flow rate and circulating flue gas flow rate. The catalytic cracking unit's processing capacity was set at 1 million tons / year, coke yield at 6.5 wt%, catalyst-to-oil ratio at 6.5, regenerator dense phase temperature at 690℃, and regenerator top pressure at 0.2 MPa. By optimizing the oxygen flow rate and circulating flue gas flow rate, the carbon dioxide content in the regenerated flue gas reached 97 wt%, and the fixed carbon content of the regenerated catalyst was reduced to 0.05 wt%. The oxygen flow rate, circulating flue gas flow rate and oxygen ratio, regenerated flue gas composition, and fixed carbon content of the regenerated catalyst were obtained, as shown in Table 1. In the flue gas recirculation regeneration process, the oxygen flow rate was set at 15809 Nm³. 3 / h, the ratio of circulating flue gas flow rate to oxygen flow rate is 4.2, and the carbon dioxide content in the regenerated flue gas after the reaction is 96.51v%, and the carbon content of the regenerated catalyst is 0.05w.

[0170] Comparative Example

[0171] A modeling method and apparatus for a catalytic cracking flue gas regeneration system (patent number: CN114818359A) were used to optimize oxygen flow rate and recirculating flue gas flow rate. The catalytic cracking unit's processing capacity was set at 1 million tons / year, coke yield at 6.5 wt%, catalyst-to-oil ratio at 6.5, regenerator dense phase temperature at 690℃, and regenerator top pressure at 0.2 MPa. By optimizing oxygen flow rate and recirculating flue gas flow rate, the carbon dioxide content in the regenerated flue gas reached 95 wt%, and the fixed carbon content of the regenerated catalyst was reduced to 0.1 wt%. The oxygen flow rate, recirculating flue gas flow rate and oxygen ratio, regenerated flue gas composition, and fixed carbon content of the regenerated catalyst were obtained, as shown in Table 1. The oxygen flow rate was set at 14730 Nm³. 3 / h, the ratio of circulating flue gas to oxygen flow rate is 3.86, and the carbon dioxide content in the regenerated flue gas after the reaction is 93.04v%, and the carbon content of the regenerated catalyst is 0.1w.

[0172] Table 1

[0173] As shown in Table 1, by setting the CO2 content in the regenerated flue gas and the carbon content of the regenerator, the oxygen flow rate and the circulating flue gas flow rate can be optimized and calculated. Under the operating conditions of the calculated oxygen flow rate and the circulating flue gas flow rate, the carbon dioxide content in the regenerated flue gas and the carbon content of the regenerator in Examples 1-4 are closer to the set CO2 content in the regenerated flue gas and the carbon content of the regenerator than those in the comparative examples. This achieves the enrichment of CO2 in the flue gas and achieves a better coking effect. In other words, the model established by this invention has a better optimization effect.

[0174] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for establishing a flue gas recirculation system model, comprising the following steps: S1, Establish a kinetic model for coking reaction: Establish a coking reaction rate equation based on carbon burning and hydrogen burning reactions; S2. Establish a steady-state model of the flue gas recirculation and regeneration system. Based on the flue gas recirculation and regeneration process, establish a steady-state model of the regenerator. Calculate the flow rates of CO, CO2, H2O, and O2 in the regenerated flue gas and the coke content of the regenerated catalyst based on the steady-state model of the regenerator. S3, Flue gas recirculation and regeneration optimization: Target optimization of carbon dioxide enrichment and the regeneration effect of the spent catalyst; The feature is that, in step S2, the steady-state model of the flue gas recirculation and regeneration system is established as follows: Material balance is performed on the gas in the dense phase bed of the regenerated flue gas, assuming the height of the dense phase bed remains constant, to obtain the equations for the rate of change of the molar flow rate of each gas component in the dense phase bed along the axial direction: in, The rate of C combustion to CO reaction in a dense-phase bed. The reaction rate of C combustion to CO2 in a dense-phase bed. The reaction rate for the combustion of H to produce H2O in a dense-phase bed. The reaction rate of CO combustion to CO2 in a dense-phase bed. The volume of the dense bed is given by k1, the rate constant for the combustion of C is given by k2, and the rate constant for the combustion of H is given by m. 3 / (kmol·s), σ represents the molar ratio of CO2 to CO produced, in kmol / kmol, ρ c This indicates the density of catalyst particles in a dense-phase bed, expressed in kg·m³. -3 , Indicates the volume fraction of the dense-phase bed catalyst; This indicates the coke content on the catalyst, expressed in kg coke / kg catalyst. The molar mass of carbon is expressed in kg / mol. The molar molecular mass of hydrogen is expressed in kg / mol, and q is the hydrogen-to-carbon molar ratio in coke. The molar concentration of each gas component i in the dense phase bed, in kmol / m³. 3 The gaseous components i include CO, CO2, H2O, O2, and N2, with units of kmol / m³. 3 , The molar flow rates of each gas component in the dense phase bed are given. Let Z be the volumetric flow rate of each gas component in the dense phase bed, and Z be the dimensionless relative distance at section z in the dense phase bed. The initial values ​​for the molar flow rates of each gas component are: in, c represents the fresh oxygen flow rate at the main air inlet of the regenerator, and c represents the recirculated flue gas in the regenerator. The equation for the rate of change of the molar flow rate of each gas component in the dilute bed along the axial direction is: Where k4 is the rate constant for the oxidation of dilute-phase CO to CO2. This represents the molar concentration of each gas component in the dilute phase bed. The molar flow rates of each gas component in the dilute phase bed are given. V represents the volumetric flow rate of each gas component in the dilute phase bed. F Let Z be the volume of the dilute phase bed, and Z be the dimensionless relative distance at section z in the dilute phase bed. The gas molar flow rate at the inlet of the dilute phase bed is equal to the gas molar flow rate at the outlet of the dense phase bed. in, The molar flow rates of each gas component at the inlet of the dilute phase bed are given. The molar flow rate of each gas component at the outlet of the dense phase bed; The flow rates of CO, CO2, H2O, and O2 in the circulating flue gas are: Where X is the ratio of circulating flue gas flow rate to oxygen flow rate. This refers to the CO flow rate at the outlet of the flue gas purification device. The CO2 flow rate at the outlet of the flue gas purification device. This refers to the flow rate of H2O at the outlet of the flue gas purification device. This refers to the flow rate of O2 at the outlet of the flue gas purification device. The molar flow rate of pure oxygen is expressed in kmol / s. The calculation formula is: in, CO flow rate at regenerator outlet This refers to the CO2 flow rate at the regenerator outlet. The H2O flow rate at the regenerator outlet. This refers to the O2 flow rate at the regenerator outlet. The volumetric content of H2O at the outlet of the flue gas purification device; Volumetric content of H2O at the outlet of the flue gas purification device for: Where T is the regeneration temperature; In establishing the steady-state model of the regenerator, the flow rates of CO, CO2, H2O, and O2 in the regenerator outlet flue gas are used as the starting point, combined with the setting of sufficient coking, to calculate the flow rates of CO, CO2, H2O, and O2 in the regenerated flue gas. When the O2 flow rate in the regenerated flue gas meets the coking requirement, the flow rates of CO, CO2, H2O, and O2 in the regenerated flue gas are: Among them, F cat For regenerant flow rate, Carbon determination for the catalyst to be generated. The hydrogen content of coke, This refers to the flow rate of pure oxygen. When the O2 flow rate in the regenerated flue gas does not meet the coking requirements, the CO, CO2, H2O, and O2 flow rates in the regenerated flue gas are: Among them, F cat For regenerant flow rate, Carbon determination for the catalyst to be generated. The hydrogen content of coke, This refers to the flow rate of pure oxygen. The above formula is used to calculate... The initial value, then, according to , , , get , Then the circulating flue gas flow rate is calculated. , Then the initial value is obtained. , The flow rates of each gas component in the regenerated flue gas are calculated based on the equations for the rate of change of molar flow rate of each gas component along the axial direction in the dilute phase bed and the equations for the rate of change of molar flow rate of each gas component along the axial direction in the dense phase bed. .

2. The method for establishing a flue gas recirculation system model as described in claim 1, characterized in that: In S1, the process of establishing the coking reaction rate function based on the molar concentration of coke and the molar concentration of oxygen is as follows: The reaction of carbon and hydrogen elements occurring in the dense phase bed is as follows: in, , , These represent the reaction rates of carbon oxidation to CO, CO2, and hydrogen oxidation to H2O, respectively; within the dense phase bed. , , They are respectively: Where k1 is the rate constant for the combustion of C, and k2 is the rate constant for the combustion of H to produce H2O, in m³ / s. 3 / (kmol·s), σ represents the molar ratio of CO2 to CO produced, in kmol / kmol, ρ c This indicates the density of catalyst particles in a dense-phase bed, expressed in kg·m³. -3 , Indicates the volume fraction of the dense-phase bed catalyst; This indicates the coke content on the catalyst, expressed in kg coke / kg catalyst. The molar molecular mass of carbon is expressed in kg / mol. The molar molecular mass of hydrogen is expressed in kg / mol, and q is the hydrogen-to-carbon molar ratio in coke. Let i be the molar concentration of gaseous component i in region j, in kmol / m³. 3 Region j corresponds to region D of the dense phase bed or region F of the dilute phase. Gas component i includes CO, CO2, H2O, O2, and N2, in kmol / m³. 3 ; In a dense-phase bed, the CO generated from carbon will continue to be oxidized to CO2, and the reaction rate is: Where k3 is the reaction rate constant for the oxidation of CO to CO2 in a dense-phase bed. The molar concentration of the gas in the dense phase bed: in, The molar flow rates of each gas component in the dense phase bed are given. The volumetric flow rate of each gas component in the dense phase bed; If only CO is oxidized in a dilute phase bed, then the CO oxidation rate in the dilute phase bed is: Wherein, k4 is the reaction rate constant for the oxidation of CO to CO2 in a dilute bed. The molar concentrations of each gas component in the dilute phase bed are as follows: in, The molar flow rates of each gas component in the dilute phase bed are given. denoted as , where is the volumetric flow rate of each gas component in the dilute phase bed.

3. The method for establishing a flue gas recirculation system model as described in claim 2, characterized in that: The σ is obtained from an empirical formula: Where T is the temperature of the dense phase bed inside the regenerator, in K.

4. The method for establishing a flue gas recirculation system model as described in claim 2, characterized in that: The for: in, The volumetric flow rate of each gas component in the dense phase bed is given. The cross-sectional area of ​​the dense phase bed in the regenerator; The for: 。 5. The method for establishing a flue gas recirculation system model as described in claim 2, characterized in that: The reaction rate constant k i for: Where, k i0 and E i Here, T represents the pre-exponential factor and activation energy of the reaction, respectively; T is the regeneration temperature; R is the ideal gas constant; and T* is the reference regeneration temperature.

6. The method for establishing a flue gas recirculation system model as described in claim 1, characterized in that: The coke content of the regenerated catalyst is: in, Carbon determination for the catalyst to be generated. The molar flow rate of the gas components at the regenerator outlet. The molar flow rate of the gas component at the regenerator inlet is given.

7. An apparatus for establishing a flue gas recirculation and regeneration system model, the apparatus being used to implement the method for establishing a flue gas recirculation and regeneration system model as described in any one of claims 1-6, characterized in that: This includes a module for establishing a kinetic model of coking reaction, used to establish the rate equation of coking reaction based on carbon burning and hydrogen burning reactions; a module for establishing a steady-state model of flue gas recirculation and regeneration system, used to establish a stable model of the regenerator based on the flue gas recirculation and regeneration process; and a flue gas recirculation and regeneration optimization module, used to optimize the enrichment of carbon dioxide and the regeneration effect of the catalyst to be regenerated.

8. An electronic device, characterized in that: It includes a processor and a memory, the memory storing computer-readable instructions, which, when executed by the processor, perform the steps of the method for establishing a flue gas recirculation system model according to any one of claims 1-6.

9. A readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it performs the steps of the method for establishing a flue gas recirculation system model as described in any one of claims 1-6.

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