CN-118421348-B - Method, device, equipment and storage medium for decoking inner wall of tubular reactor

CN118421348BCN 118421348 BCN118421348 BCN 118421348BCN-118421348-B

Abstract

The invention discloses a decoking method, a device, equipment and a storage medium for the inner wall of a tubular reactor, which comprises the steps of modeling according to a biomass pyrolysis device to generate a corresponding three-dimensional simulation model, calculating a volume fraction distribution predicted value and a temperature distribution predicted value of a solid phase main component of the tubular reactor after a time step through the three-dimensional simulation model, further calculating the current corresponding flow purging amount of a coking grid and the adhesion predicted amount of coke after the time step, judging whether the flow purging amount and the jet temperature of the coking grid at the moment of the next step are required to be regulated, and further increasing the flow purging amount or the jet temperature in a targeted area with superscale coking through quantitatively regulating the flow purging amount or the jet temperature of a specific jet nozzle, thereby realizing the prevention of superscale coking of the inner wall of the tubular reactor. The invention can effectively improve the response speed of the decoking control on the inner wall of the tubular reactor, thereby improving the control effect on tar removal.

Inventors

Wu Sikan
WANG XIN
ZHANG BIAO
XIAO BIN
SONG YONGYI

Assignees

中国石油化工股份有限公司
中石化（大连）石油化工研究院有限公司

Dates

Publication Date: 20260505
Application Date: 20230202

Claims (10)

1. A method for decoking the inner wall of a tubular reactor, comprising the steps of: S11, generating a corresponding three-dimensional simulation model according to a biomass pyrolysis device and meshing the model, wherein a decoking mechanism of the biomass pyrolysis device comprises a decoking gas generator and an air inlet guide pipe which is arranged in a tubular reactor in parallel and is close to the upper part of the inner wall; s12, determining input parameters of the three-dimensional simulation model, wherein the input parameters comprise a material feeding rate, a material temperature, an inert shielding gas inlet rate, a volume flux of decoking gas, a temperature of decoking gas, a multiphase flow volume fraction, a wall heat flux, a wall roughness height, a solid phase wall shearing force, an outlet pressure and a multiphase flow interphase drag force; s13, taking a preset time step as a calculation period, and obtaining a simulation result of the three-dimensional simulation model in a steady state according to the input parameters, wherein the simulation result comprises a volume fraction distribution predicted value and a temperature distribution predicted value of a solid phase main component of the tubular reactor after one time step; S14, determining grids with the volume fraction distribution predicted value of the solid phase main component larger than a preset fraction threshold as target grids, and respectively calculating the free coke adhesive force of the target grid area and the gravity and shearing stress of the solid phase main component of the target grid area; S15, judging whether an included angle between the resultant force direction of the components of the target grid in the radial direction of the reactor and the normal direction of the tangential surface of the wall surface and the radial direction of the reactor is larger than 90 degrees or not according to the adhesion force, the gravity and the shearing stress of the free coke, and if so, determining the target grid as a coking grid; s16, respectively calculating coke increment after a time step of each coking grid, and calculating coke adhesion pre-measurement after a time step according to the current coke stock of the coking grids; S17, respectively calculating the gas-solid phase traction force, the liquid-solid phase traction force and the convection dispersion amount of each coking grid after a time step, and recording the sum of the gas-solid phase traction force, the liquid-solid phase traction force and the convection dispersion amount as the flow purge amount after a time step; S18, calculating and obtaining the coke predicted stock of the coking grid by a time step through the difference value between the coke adhesion predicted quantity and the flow purging quantity; And S19, when the coke predicted stock of the coking grid is larger than a preset coking rate critical value, the flow purging amount or the jet temperature of the jet holes corresponding to the coking grid is increased according to a preset rule, and is used as updated flow purging amount or jet temperature to return to the step S13, if not, the current flow purging amount or jet temperature is used as target flow purging amount or target jet temperature, and a control instruction of the jet holes of the coking grid is generated.
2. The method for decoking an inner wall of a tubular reactor according to claim 1, wherein the increasing the flow purge amount of the gas injection holes corresponding to the coking grid according to a preset rule comprises: And improving the flow purging quantity of the air injection holes corresponding to the coking grids according to a preset pressurizing proportion.
3. The method for decoking an inner wall of a tubular reactor according to claim 1, wherein when the predicted coke stock of the coking grid is greater than a preset coking rate critical value, increasing the flow purge amount and/or the gas injection temperature of the gas injection holes corresponding to the coking grid according to a preset rule comprises: S21, acquiring volume flux and temperature of each air jet hole under a first time step according to the three-dimensional simulation model, and dividing a cavity of the tubular reactor into a plurality of decoking sections according to the spatial correlation degree weight, wherein each decoking section Jiao Oujian corresponds to a plurality of air jet holes; S22, acquiring a coking space position and a coking amount according to data in a data set Coked, and determining a corresponding relation between the coking space position and the decoking interval, wherein the data set Coked is a data set of a target grid with the total coke adhesion amount being larger than the flow purging amount; S23, setting a Boolean array Bool for adjusting the volume flux or the jet temperature of each jet hole, and setting an initial value; S24, traversing grids in the data set Coked, respectively judging whether the coke prediction stock of each grid in the next time step is an exceeding grid exceeding a preset coking rate critical value, if yes, determining the adjusting mode of the air jet corresponding to the decoking interval of the exceeding grid according to the current state of the Boolean array Bool, updating the volume flux or the air jet temperature according to the adjusting mode, changing the state of the Boolean array Bool after traversing, returning the updated volume flux or the updated air jet temperature of each exceeding grid to the step S13, and if no, taking the current volume flux and the current air jet temperature of each air jet as the volume flux and the air jet temperature of each air jet in the next time step and generating control instructions of the air jets according to the current volume flux and the air jet temperature of each air jet.
4. The method for decoking an inner wall of a tubular reactor according to claim 1, wherein the heating means of the pyrolysis device for substances comprises: One or more of electrical heating, microwave heating, plasma heating, laser heating, electron Shu Jia heating.
5. The method of claim 1, wherein generating and gridding a corresponding three-dimensional simulation model from the biomass pyrolysis device comprises: setting the cavity volume of the tubular reactor in the three-dimensional simulation model as V, wherein the number of air nozzles is n; Setting the feeding volume flux of the ith air nozzle as Qv i , the angle as Deg i and the temperature as T0 i ; The three-dimensional simulation model after gridding is provided with d grids and is stored in a set Data, wherein the temperature of the ith grid is T i , and the coking amount is Coke i .
6. The method for decoking an inner wall of a tubular reactor according to claim 1, wherein the calculation formula of the drag force between the gas and the solid phase comprises: an energy minimum multi-scale model is adopted, and an equation of the energy minimum multi-scale model comprises: Wherein F gs is the gas-solid phase drag force, re is the Reynolds coefficient, ε is the average void fraction, d p is the particle diameter, ρ is the average density, u g is the gas apparent velocity, and u p is the particle apparent velocity.
7. The method for decoking an inner wall of a tubular reactor according to claim 1, wherein the calculation formula of the drag force between the liquid and the solid phase comprises: a Schiller-Naumann uniform drag model is adopted, and the equation of the Schiller-Naumann uniform drag model comprises: wherein F ls is the liquid-solid phase drag force, C D,ls is the liquid-solid phase drag force coefficient, and u is the apparent fluid velocity.
8. A tubular reactor inner wall decoking apparatus, comprising: The decoking mechanism of the biomass pyrolysis device comprises a decoking gas generator and an air inlet conduit which is arranged in the tubular reactor in parallel and is close to the upper part of the inner wall, wherein the air inlet conduit sprays decoking gas to the inner wall of the tubular reactor through an air spraying hole arranged in the tubular reactor; The parameter determining unit is used for determining input parameters of the three-dimensional simulation model, and comprises a material feeding rate, a material temperature, an inert shielding gas inlet rate, a volume flux of decoking gas, a temperature of decoking gas, a multiphase flow volume fraction, a wall heat flux, a wall roughness height, a solid phase wall shearing force, an outlet pressure and a multiphase flow interphase drag force; The simulation calculation unit is used for obtaining a simulation result of the three-dimensional simulation model in a steady state according to the input parameters by taking a preset time step as a calculation period, wherein the simulation result comprises a volume fraction distribution predicted value and a temperature distribution predicted value of a solid phase main component of the tubular reactor after one time step; The target grid determining unit is used for determining grids with the volume fraction distribution predicted value of the solid phase main component larger than a preset fraction threshold value as target grids, and respectively calculating the free state coke adhesive force of the target grid area and the gravity and the shearing stress of the solid phase main component of the target grid area; The coking grid judging unit is used for judging whether the included angle between the resultant force direction of the components of the target grid in the radial direction of the reactor and the normal direction of the tangential surface of the wall surface and the radial direction of the reactor is larger than 90 degrees or not according to the free state coke adhesive force, gravity and shearing stress, and if so, determining the target grid as the coking grid; the coke adhesion prediction unit is used for respectively calculating the increment of the coke after one time step of each coking grid and calculating the predicted coke adhesion after one time step according to the current stock of the coke of the coking grids; the purging amount calculating unit is used for calculating the gas-solid phase traction force, the liquid-solid phase traction force and the convection dispersion amount of each coking grid after a time step, and recording the sum of the gas-solid phase traction force, the liquid-solid phase traction force and the convection dispersion amount as the flowing purging amount after a time step; The coke stock prediction unit is used for obtaining the coke prediction stock of the coking grid after a time step through the calculation of the difference value between the coke adhesion prediction amount and the flow sweeping amount; And the control instruction generation unit is used for increasing the flow purging quantity or the air injection temperature of the air injection holes corresponding to the coking grid according to a preset rule when the coke prediction stock of the coking grid is larger than a preset coking rate critical value, returning the flow purging quantity or the air injection temperature as updated flow purging quantity or air injection temperature to the simulation calculation unit, and generating a control instruction of the air injection holes of the coking grid by taking the current flow purging quantity or the air injection temperature as a target flow purging quantity or a target air injection temperature if the coke prediction stock of the coking grid is not larger than the preset coking rate critical value.
9. A tubular reactor inner wall decoking apparatus comprising: A memory for storing a computer program; a processor for invoking and executing said computer program to perform the steps of the tube reactor inner wall decoking method according to any of claims 1-7.
10. A storage medium comprising a software program adapted to be executed by a processor for performing the steps of the tube reactor inner wall decoking method according to any one of claims 1-7.

Description

Method, device, equipment and storage medium for decoking inner wall of tubular reactor Technical Field The invention relates to the field of chemical technology, in particular to a method, a device, equipment and a storage medium for decoking the inner wall of a tubular reactor. Background In reactions involved in the fields of petrochemical industry, coal chemical industry and the like, coking phenomenon often occurs on the wall surface of a reactor. This coking phenomenon is common and causes are complex. It is believed that substantial amounts of coke are formed to adhere to the walls of the reactor due to the ash of varying composition carried by the feedstock itself, or incomplete cracking of the heavy components of the feedstock due to reaction conditions. For chemical processes, coking of the reactor wall may cause a series of adverse effects that restrict the process, such as blockage of materials inside the reactor, incomplete reaction, and increased operating pressure. In the prior art, a plurality of reactors are generally used in parallel, and a fixed operation period is regulated to stop running each reactor for manual decoking in batches. The inventor finds that the decoking mode in the prior art has at least the following defects: Targeted decoking cannot be carried out according to actual coking conditions in the reactor, and the reactor is required to be shut down and maintained, so that normal production activities of equipment can be affected, and the maintenance cost is too high. The above information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person of ordinary skill in the art. Disclosure of Invention The invention aims to reduce the influence of decoking on the normal production of equipment and reduce the maintenance cost. The invention provides a decoking method for the inner wall of a tubular reactor, which comprises the following steps: S11, generating a corresponding three-dimensional simulation model according to a biomass pyrolysis device and meshing the model, wherein a decoking mechanism of the biomass pyrolysis device comprises a decoking gas generator and an air inlet guide pipe which is arranged in the tubular reactor in parallel and is close to the upper part of the inner wall; s12, determining input parameters of the three-dimensional simulation model, wherein the input parameters comprise a material feeding rate, a material temperature, an inert shielding gas inlet rate, a volume flux of decoking gas, a temperature of decoking gas, a multiphase flow volume fraction, a wall heat flux, a wall roughness height, a solid phase wall shearing force, an outlet pressure and a multiphase flow interphase drag force; s13, taking a preset time step as a calculation period, and obtaining a simulation result of the three-dimensional simulation model in a steady state according to the input parameters, wherein the simulation result comprises a volume fraction distribution predicted value and a temperature distribution predicted value of a solid phase main component of the tubular reactor after one time step; S14, determining grids with the volume fraction distribution predicted value of the solid phase main component larger than a preset fraction threshold as target grids, and respectively calculating the free coke adhesive force of the target grid area and the gravity and shearing stress of the solid phase main component of the target grid area; S15, judging whether an included angle between the resultant force direction of the components of the target grid in the radial direction of the reactor and the normal direction of the tangential surface of the wall surface and the radial direction of the reactor is larger than 90 degrees or not according to the adhesion force, the gravity and the shearing stress of the free coke, and if so, determining the target grid as a coking grid; s16, respectively calculating coke increment after a time step of each coking grid, and calculating coke adhesion pre-measurement after a time step according to the current coke stock of the coking grids; S17, respectively calculating the gas-solid phase traction force, the liquid-solid phase traction force and the convection dispersion amount of each coking grid after a time step, and recording the sum of the gas-solid phase traction force, the liquid-solid phase traction force and the convection dispersion amount as the flow purge amount after a time step; S18, calculating and obtaining the coke predicted stock of the coking grid by a time step through the difference value between the coke adhesion predicted quantity and the flow purging quantity; And S19, when the coke predicted stock of the coking grid is larger than a preset coking rate critical value, the flow purging amount or the jet temperature