Structure optimization design method for high-efficiency diesel hydrogen production reformer

Abstract

The invention discloses a high-efficiency diesel hydrogen production reformer structure optimization design method, and belongs to the technical field of reformer optimization design. The method comprises the following steps: establishing a reformer multi-physical field model in finite element software; determining main structure parameters influencing the reforming efficiency of the diesel hydrogen production reformer; the reforming conversion rate, the H2 output rate, the heat efficiency and the CO output rate of the diesel hydrogen production reformer under different structure parameters are obtained through a multi-physical field model to serve as performance evaluation indexes of the diesel hydrogen production reformer, and the structure parameters capable of improving the reforming conversion rate and the H2 output rate of the diesel hydrogen production reformer and / or reducing the CO output rate of the diesel hydrogen production reformer are selected. On the basis of improving a heating structure of an existing reformer, main structural parameters influencing the reforming efficiency of the diesel hydrogen production reformer are analyzed, and the structural parameters of the improved reformer are optimized by utilizing a finite element to establish a multi-physical field model, so that the diesel hydrogen production reformer with high reforming conversion rate is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of reformer structural optimization design, and in particular to a high-efficiency diesel hydrogen production reformer structural optimization design method. Background Art

[0002] Hydrogen energy is one of the representatives of clean energy. It has advantages that traditional energy sources do not have, such as low greenhouse gas emissions and high energy density. Fuel cells are one of the most efficient ways to utilize hydrogen energy. Solid oxide fuel cells (SOFCs), as a relatively mature type of fuel cell technology, have the advantages of high efficiency, cleanliness, high power generation efficiency, and good fuel flexibility. They are considered to be an important development direction in the future energy field. However, an important problem restricting their application is the source, storage, and transportation of hydrogen. Diesel has a high energy density and is easy to obtain and store. Using diesel carried by the catalytic reaction of the diesel reformer to produce hydrogen on site is one of the most effective ways to obtain hydrogen for fuel cells.

[0003] The operating temperature of diesel hydrogen production is 600~800℃, which is higher than the temperature required by other fossil fuels. Therefore, a more reasonable arrangement of reformer heating tubes is needed to provide heat for the reforming reaction. Existing hydrogen production reformers mostly produce hydrogen by reforming fuels such as methane and propane. But diesel is an ideal hydrogen production raw material that is easier to obtain. At present, most reformers use fuel combustion to provide heat for the reforming reaction, which will make the overall fuel utilization rate low, and the heater structure is mostly an external heating method, which has a high heat loss and is difficult to meet the diesel reforming temperature requirements, resulting in a decrease in diesel reforming efficiency. The unsatisfactory heating structure of the reformer is the main reason for the reduction in diesel reforming efficiency. In order to improve the reforming efficiency of the diesel hydrogen production reformer, it is necessary to optimize the structure of the reformer, especially the heating structure of the reformer. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for optimizing the structure of a high-efficiency diesel hydrogen production reformer.

[0005] The technical solution adopted by the present invention is: The present invention provides a method for optimizing the structure of a high-efficiency diesel hydrogen production reformer, comprising the following steps: S1. Establish a three-dimensional structural model of a diesel hydrogen reformer, and import the three-dimensional structural model into a finite element analysis software. Set the physical parameters and assumptions required for finite element simulation according to the actual working conditions, set the control equations for gas flow and heat transfer and reforming reaction, and establish a multi-physics field model based on the coupling of material transfer, porous medium heat transfer, and fluid heat transfer. S2. Determine the main structural parameters that affect the reforming efficiency of the diesel hydrogen reformer; S3, according to the structural parameters determined in step S2, using the multi-physics field model established in step S1 to obtain the reforming conversion rate, H 2 The output rate, thermal efficiency and CO output rate are used as the performance evaluation indicators of diesel hydrogen reformer; and the reforming conversion rate, H 2 The output rate and CO output rate indicators are selected to increase the reforming conversion rate and H 2 Structural parameters that increase the yield and / or decrease the CO yield; S4, reforming conversion rate based on diesel hydrogen reformer, H 2 The three performance evaluation indicators of output rate, thermal efficiency and comprehensive performance evaluation factor are established to verify the comprehensive performance of the diesel hydrogen reformer under the structural parameters determined in step S3.

[0006] Furthermore, the three-dimensional structural model of the diesel hydrogen reformer in step S1 includes a reformer shell, a porous medium carrier for loading a catalyst disposed in the reformer shell, a plurality of heating gas pipelines penetrating the porous medium carrier, and a heat preservation layer sleeved on the outside of the reformer shell, and the inlet end of the porous medium carrier is used to input a mixed gas of diesel and superheated steam, and the outlet end of the porous medium carrier is used to output H 2 and CO.

[0007] Furthermore, the assumptions set in the multi-physics field model in step S1 include: (a) The mixed reactants of diesel and superheated steam are uniformly mixed before entering the reformer, and the temperature of the superheated steam has been preheated to the same temperature as the diesel. The mixed reactants of diesel and superheated steam enter the reformer in a gaseous state; (b) The mixed reactant of diesel and superheated steam is an ideal gas, incompressible, and the flow state is steady laminar flow; (c) Ignore the effect of gravity; (d) Ignore the effect of catalyst coating on the reforming reaction; (e) Ignore thermal radiation during the reaction.

[0008] Furthermore, the main structural parameters affecting the reforming efficiency of the diesel hydrogen reformer in step S2 include: The number of heating gas pipelines n is used to adjust the heat exchange area of ​​the mixed gas of heating gas, diesel and superheated steam; The distribution distance d of the heating gas pipeline from the center of the reformer is used to adjust the heat transfer efficiency of the reformer; The heating gas pipeline length L is used to adjust the convection heat exchange time of the mixed gas of the heating gas, diesel and superheated steam; Whether baffles are provided in the porous medium carrier to adjust the reforming efficiency of the reformer.

[0009] Furthermore, the step S3 specifically includes: S31, setting different numbers of heating gas pipelines n, and setting the total heat transfer area of ​​the heating gas pipelines to be the same in the diesel hydrogen production multi-physics field model established in step S1, and simulating and calculating the reforming conversion rate, H under different numbers of heating gas pipelines. 2 output rate, CO output rate, and select the reforming conversion rate and H 2 The number n of heating gas pipes with increased production rate and / or reduced CO production rate; S32, setting different distribution distances d between the heating gas pipeline and the center of the reformer, and using the diesel hydrogen production multi-physics field model established in step S1 to simulate and calculate the reforming conversion rate, H 2 output rate, CO output rate, and select the reforming conversion rate and H 2 The distribution distance d of the heating gas pipeline for increasing the yield and / or reducing the CO yield from the center of the reformer; S33, setting different heating gas pipeline lengths L, using the diesel hydrogen production multi-physics field model established in step S1 to simulate and calculate the reforming conversion rate, H under different lengths L 2 output rate, CO output rate, and select the reforming conversion rate and H 2 Length L of heating gas pipeline for increasing the output rate and / or reducing the CO output rate; S34, using the diesel hydrogen production multi-physics field model established in step S1 to simulate and calculate the diesel hydrogen production reformer with and without baffles, and obtain the reforming conversion rate, H 2 The output rate and CO output rate are compared and analyzed. If baffles are set, the reforming conversion rate and H 2 If the output rate is increased and / or the CO output rate is reduced, it means that setting the baffle can improve the reforming efficiency of the diesel hydrogen reformer, otherwise there is no need to set the baffle.

[0010] Furthermore, the calculation formula of the comprehensive performance evaluation factor in step S4 is: ; in: ; ; ; In the formula, is the comprehensive performance evaluation factor, FUR is the reforming conversion rate, HPR is the H 2 Output rate, TE is thermal efficiency, , , are the reforming conversion rate, H 2 The weight of output rate and thermal efficiency in the comprehensive performance evaluation of diesel hydrogen reformer, and ; is the diesel inlet molar concentration, mol / m³; is the diesel outlet molar concentration, mol / m³; is the hydrogen outlet molar concentration, mol / m³; is the outlet molar concentration of carbon monoxide, mol / m³; is the lower heating value of hydrogen, kJ / mol; is the lower heating value of carbon monoxide, kJ / mol; Total heat input for heating gas.

[0011] The beneficial effects of the present invention are: The present invention proposes a method for optimizing the structure of a high-efficiency diesel hydrogen production reformer. On the basis of improving the heating structure of an existing reformer, the main structural parameters affecting the reforming efficiency of the diesel hydrogen production reformer are analyzed, and a multi-physical field model is established using finite elements to optimize the structural parameters of the improved reformer, so as to obtain a diesel hydrogen production reformer with a high reforming conversion rate. In addition, the present invention also proposes a comprehensive performance evaluation factor for evaluating the comprehensive performance of the reformer, which is used to evaluate the comprehensive performance of the diesel hydrogen production reformer structure obtained by finite element simulation, that is, whether it can simultaneously maintain a high reforming conversion rate and a high thermal efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0013] Figure 1 is a flow chart of the present invention; Figure 2 It is a structural schematic diagram of the reformer of the present invention; Figure 3 for Figure 2 A cross-sectional view of Figure 4 A schematic diagram of setting different numbers of heating gas pipelines for the present invention; Figure 5A schematic diagram of the distribution distances of different heating gas pipelines from the center of the reformer according to the present invention; Figure 6 The reforming conversion rate and H under different numbers of heating gas pipelines in the present invention are 2 Output rate change curve; Figure 7 The reforming conversion rate and H at different distribution distances of the heating gas pipeline from the center of the reformer in the present invention are 2 Output rate change curve; Figure 8 The reforming conversion rate and H under different heating gas pipeline lengths of the present invention are 2 Output rate change curve; Fig. 9 This is a schematic diagram of the structure of the baffle plate provided in the reformer according to the present invention; Fig.10 The figure is a curve showing the change of CO production rate when baffles are added or not in the present invention.

[0014] Note in the figure: 1. Reformer shell; 2. Porous medium carrier; 3. Heating gas pipeline; 4. Baffle. DETAILED DESCRIPTION

[0015] The present invention provides a method for optimizing the structure of a high-efficiency diesel hydrogen production reformer. To make the purpose, technical solution and effect of the present invention clearer and more specific, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0016] The present invention is described in detail below with reference to the accompanying drawings.

[0017] This embodiment provides a method for optimizing the structure design of a high-efficiency diesel-to-hydrogen reformer, and based on this method, a diesel-to-hydrogen reformer structure with good comprehensive performance is determined.

[0018] Reference Figure 1 , the steps of the above optimization design method are as follows: S1. Establish a three-dimensional structural model of the diesel hydrogen reformer and import the three-dimensional structural model into the finite element analysis software. Set the physical parameters and assumptions required for the finite element simulation according to the actual working conditions, set the control equations for material transfer, heat transfer and reforming reaction, and establish a multi-physics field model based on the coupling of material transfer, porous medium heat transfer and fluid heat transfer.

[0019] Reference Figure 2 and Figure 3The three-dimensional structural model of the diesel hydrogen reformer in step S1 includes a reformer shell 1, a porous medium carrier 2 for loading a catalyst disposed in the reformer shell 1, a plurality of heating gas pipelines 3 penetrating the porous medium carrier, and a heat preservation layer sleeved on the outside of the reformer shell 1. The inlet end of the porous medium carrier is used to input a reactant mixed gas formed by mixing diesel and superheated steam, and the outlet end of the porous medium carrier is used to output H 2 and CO; the heating gas pipeline is used to introduce heating gas to increase the heat for the reforming reaction, and the heating gas pipeline and baffles are made of 316L stainless steel.

[0020] In addition, the physical parameters set in the established multi-physics field model in step S1 mainly include: The heating gas inlet temperature and inlet flow rate of the heating gas pipeline; The inlet temperature and pressure difference of the reactant mixture gas in the porous medium carrier; The substance type of the reactant gas mixture; Porosity, heat capacity, and density of porous media carriers; Materials of reformer shell and heating gas pipeline.

[0021] The assumptions set in the multi-physics model in step S1 include: (a) The mixed reactants of diesel and superheated steam are uniformly mixed before entering the reformer, and the temperature of the superheated steam has been preheated to the same temperature as the diesel steam. The mixed reactants of diesel and superheated steam enter the reformer in a gaseous state; (b) The mixed reactant of diesel and superheated steam is an ideal gas, incompressible, and the flow state is steady laminar flow; (c) Ignore the effect of gravity; (d) Ignore the effect of catalyst coating on the reforming reaction; (e) Ignore thermal radiation during the reaction.

[0022] The reforming reactions involved in the multi-physics field model established in step S1 mainly include the following three types, and the specific reaction equations are as follows: Reforming reaction (SR): ; Water Gas Shift (WGS): ; Methane Steam Reaction (MSR): ; The control equations of material transfer and heat transfer involved in the multi-physics field model established in step S1 mainly include: The flow of gaseous substances through the porous medium carrier in the reformer follows Darcy's law, that is: ; in, represents the gas density, Indicates viscosity, represents the permeability of porous media, represents the pressure in the reformer; and the inlet to outlet is set to a 50Pa pressure drop; all other boundaries are impermeable; For the heated gas flow within the heated gas duct, the Navier-Stokes governing equations and the continuity equation are used: ; ; in, represents the gas velocity vector, represents the gas pressure, represents the fluid dynamic viscosity, represents the diffusion coefficient, Indicates gas density; During the reforming reaction, diesel steam reforming follows the energy conservation equation: ; in, represents the constant pressure specific heat of the mixed gas, represents the thermal conductivity of the mixed gas, Represents the heat source generated by the chemical reaction, is temperature; ; in, For the The reaction enthalpy of the reaction, For the The reaction rate of a reaction; For reactants and products in porous media carriers, the governing equations for concentrated species transport are used: ; in, For material The quality score of For material and substances The binary diffusion coefficient, For the The mass fraction of a substance, For the The mole fraction of a substance, is the generalized thermal diffusion coefficient, which is taken as 0, For material reaction rate.

[0023] S2. Determine the main structural parameters that affect the reforming efficiency of the diesel hydrogen reformer.

[0024] The main structural parameters affecting the reforming efficiency of the diesel hydrogen reformer in step S2 include: The number of heating gas pipelines n is used to adjust the heat exchange area of ​​the mixed gas of heating gas, diesel and superheated steam; The distribution distance d of the heating gas pipeline from the center of the reformer is used to adjust the heat transfer efficiency of the reformer; The heating gas pipeline length L is used to adjust the convection heat exchange time of the mixed gas of the heating gas, diesel and superheated steam; Whether baffles are provided in the porous medium carrier to adjust the reforming efficiency of the reformer.

[0025] S3, according to the structural parameters determined in step S2, using the multi-physics field model established in step S1 to obtain the reforming conversion rate, H 2 The output rate, thermal efficiency and CO output rate are used as the performance evaluation indicators of diesel hydrogen reformer; and the reforming conversion rate, H 2 The output rate and CO output rate indicators are selected to increase the reforming conversion rate and H 2 Structural parameters that increase the yield and / or decrease the CO yield.

[0026] The step S3 specifically includes: S31, setting different numbers of heating gas pipelines n, and setting the total heat transfer area of ​​the heating gas pipelines to be the same in the diesel hydrogen production multi-physics field model established in step S1, and simulating and calculating the reforming conversion rate, H under different numbers of heating gas pipelines. 2 output rate, CO output rate, and select the reforming conversion rate and H 2 The number n of heating gas pipes with increased production rate and / or reduced CO production rate; S32, setting different distribution distances d between the heating gas pipeline and the center of the reformer, and using the diesel hydrogen production multi-physics field model established in step S1 to simulate and calculate the reforming conversion rate, H 2 output rate, CO output rate, and select the reforming conversion rate and H 2 The distribution distance d of the heating gas pipeline for increasing the yield and / or reducing the CO yield from the center of the reformer; S33, setting different heating gas pipeline lengths L, using the diesel hydrogen production multi-physics field model established in step S1 to simulate and calculate the reforming conversion rate, H under different lengths L2 output rate, CO output rate, and select the reforming conversion rate and H 2 Length L of heating gas pipeline for increasing the output rate and / or reducing the CO output rate; S34, using the diesel hydrogen production multi-physics field model established in step S1 to simulate and calculate the diesel hydrogen production reformer with and without baffles, and obtain the reforming conversion rate, H 2 The output rate and CO output rate are compared and analyzed. If baffles are set, the reforming conversion rate and H 2 If the output rate is increased and / or the CO output rate is reduced, it means that setting the baffle can improve the reforming efficiency of the diesel hydrogen reformer, otherwise there is no need to set the baffle.

[0027] S4, reforming conversion rate based on diesel hydrogen reformer, H 2 The three performance evaluation indicators of output rate, thermal efficiency and comprehensive performance evaluation factor are established to verify the comprehensive performance of the diesel hydrogen reformer under the structural parameters determined in step S3.

[0028] The step S4 specifically comprises: respectively calculating the comprehensive performance evaluation factors under different structural parameters set in step S3, and judging whether the comprehensive performance evaluation factors under the optimal structural parameters determined in step S3 are the maximum value or close to the maximum value in the group; if so, it means that the structural parameters selected in step S3 have passed the verification, and the comprehensive performance of the reformer under the structural parameters is good; otherwise, it means that the structural parameters selected in step S3 have not passed the verification, and if they have not passed the verification, return to step S3 to continue optimizing the parameters.

[0029] The calculation formula of the comprehensive performance evaluation factor in step S4 is: ; in: ; ; ; In the formula, is the comprehensive performance evaluation factor, FUR is the reforming conversion rate, HPR is the H 2 Output rate, TE is thermal efficiency, , , are the reforming conversion rate, H 2 The weight of output rate and thermal efficiency in the comprehensive performance evaluation of diesel hydrogen reformer, and , weights are assigned by entropy method; is the diesel inlet molar concentration, mol / m³; is the diesel outlet molar concentration, mol / m³; is the hydrogen outlet molar concentration, mol / m³; is the outlet molar concentration of carbon monoxide, mol / m³; is the lower heating value of hydrogen, kJ / mol; is the lower heating value of carbon monoxide, kJ / mol; Total heat input for heating gas.

[0030] Specifically in this embodiment, in order to speed up the model calculation time, improve the solution efficiency and simplify the calculation model during the finite element simulation process, 1 / 2 is selected for calculation, and then the reforming condition of the entire reformer can be simulated through symmetric boundary conditions.

[0031] Specifically in this embodiment, the diesel component is close to n-hexadecane, and n-hexadecane is used as the reactant. The reaction gas is a mixture of n-hexadecane and superheated steam, of which n-hexadecane accounts for 20% and water vapor accounts for 80%. The two are mixed evenly and enter the porous medium carrier after preheating. The inlet temperature is 700K and the pressure difference is 50pa; the inlet temperature of the heating gas in the heating gas pipeline is 900K and the inlet flow rate is 1m / s; the reaction gas and the heating gas flow in reverse; the porosity of the porous medium carrier is 0.25, the heat capacity is 2800J / (kg·K), and the density is 2000kg / m 3 The heating gas pipeline and the reformer shell are both made of 316L stainless steel, the diameter of the porous medium carrier is 30mm, and the length of the porous medium carrier is 100mm.

[0032] Reference Figure 4 In this embodiment, when determining the number n of heating gas pipelines, n is set to 1, 4, 5, 6, and 8. When n is 1, the heating gas pipeline is located at the center of the reformer; when n is 4, 5, 6, and 8, the heating gas pipelines are evenly distributed around the center of the reformer. The diameter of the reformer is set to 0.3m, and the total heat transfer area of ​​the heating gas pipelines is set to be the same. When n is a different number, the diameter of the corresponding heating gas pipeline changes. During the simulation process, the heating temperature is kept at 900K, the inlet velocity is 1m / s, and the heating gas and the reaction gas enter from the same side. The structures with five different numbers of pipelines are studied respectively, and the distribution curves of the n-hexadecane reforming efficiency and hydrogen production rate under different n values ​​are simulated and calculated to obtain, such as Figure 6 As shown. Figure 6, the channel structure with high diesel reforming rate and hydrogen production rate is selected as the optimal channel range of diesel high-efficiency reformer is 5~8. When the optimal number of channels is 5~8, the conversion rate of n-hexadecane is maintained at a high level and has stabilized. Under different value ranges of n, the comprehensive performance evaluation factor is used for verification. Through calculation, the values ​​of the comprehensive performance evaluation factor are 0.648, 0.705, 0.694, 0.715, and 0.715 respectively. When the value of the comprehensive performance evaluation factor is larger, the comprehensive performance is better. When n is 5~8, the values ​​of the comprehensive performance evaluation factor are all in a larger range, indicating that the reformer has better comprehensive performance when the number of channels is 5~8.

[0033] like Figure 5 As shown in the figure, in this embodiment, when determining the distribution distance d between the heating gas pipeline and the center of the reformer, the number of channels and the heat exchange area are set to remain unchanged, and the value of d is set to 15mm, 17.5mm, 20mm, 22.5mm, and 25mm. The reforming conversion rate and H under different distribution distances d are 2 The output rate is Figure 7 As shown. Figure 7 It can be seen that with the increase of d value, the reforming conversion rate and H 2 The output rate showed a trend of increasing first and then decreasing. When d reached 17.5~22.5mm, the reforming conversion rate and H 2 The output rates are all within a large range, among which the n-hexadecane reforming conversion rate is more than 90%, and the hydrogen molar concentration is also the highest. d is selected as 17.5~22.5mm as the optimal range. The comprehensive performance evaluation factor is used for verification. Through calculation, the values ​​of the comprehensive performance evaluation factor are 0.698, 0.709, 0.722, 0.711, and 0.704, respectively, among which d is 17.5~22.5mm. The values ​​of the comprehensive performance evaluation factor are all within a large range, indicating that the reformer performance under this structure is good.

[0034] In this embodiment, based on the determination of the optimal number of heating gas pipelines n and the optimal distribution distance d, the heating gas pipeline length L is further determined. The values ​​of pipeline L are set to be 0.1m, 0.125m, 0.15m, 0.175m, and 0.2m respectively. The reforming conversion rate and H under different length values ​​L are 2 The output rate is Figure 8 As shown. Figure 8 It can be seen that with the increase of L value, the reforming conversion rate and H 2The output rate shows a trend of gradual increase. When the length reaches 0.15m, the reforming rate of n-hexadecane reaches more than 98%. However, as the channel distance continues to increase, the reforming conversion rate does not change significantly. The optimal value range of the pipeline length L is 0.15~0.2m. The comprehensive performance evaluation factor is used for verification. Through calculation, the values ​​of the comprehensive performance evaluation factor are 0.610, 0.683, 0.722, 0.723, and 0.723, respectively. When the pipeline length is 0.15~0.2m, the values ​​of the comprehensive performance evaluation factor are all within a large range, indicating that the reformer performance under this structure is good.

[0035] like Fig. 9 As shown, in this embodiment, a baffle structure is set in the reformer. Specifically, two semicircular baffles 4 parallel to the end surface of the reformer are set on the porous medium carrier, and the two baffles are arranged symmetrically about the center of the reformer. In order to verify the influence of adding baffles on the reforming performance of the diesel hydrogen reformer, this embodiment also selects a group of heating gas pipelines n, distribution distance d and length L within the optimal range determined above, and then only adds baffles to simulate and calculate the reforming conversion rate and H 2 Output rate, after simulation, whether to set the baffle plate has an effect on the reforming conversion rate and H 2 The output rate has little impact, so the CO output rate curve is obtained by simulation calculation and compared, such as Fig.10 As shown. Fig.10 It can be seen that after adding baffles, the CO concentration dropped from 2.7497mol / m³ to 1.772mol / m³, a decrease of 36%, indicating that adding baffles can effectively reduce carbon deposition in the reformer, improve the reforming performance of the reformer, and extend the service life of the reformer. The comprehensive performance evaluation factor was used for verification. Through calculation, the values ​​of the comprehensive performance evaluation factors without and with baffles were 0.722 and 0.731 respectively. The comprehensive performance evaluation factor with baffles was higher, indicating that the reformer performance under this structure was good.

[0036] The molar concentration of CO above represents the degree of carbon deposition in the reformer. CO is the precursor for the formation of C. 2 The mutual conversion between CO and carbon leads to the formation of carbon (carbon deposits), while carbon dioxide does not directly form carbon, so a high CO content is more likely to cause carbon deposits. If there is too much carbon deposit, it will affect the heat and mass transfer effects of the reactor, reduce the reaction efficiency, and even cause equipment damage. Therefore, in the diesel reforming process, the CO content needs to be controlled to reduce the occurrence of carbon deposits.

[0037] Based on the above simulation analysis, the structural parameters of the diesel hydrogen reformer, mainly the geometric parameters of the heating gas pipeline, are determined as follows: The number n of heating gas pipes ranges from 5 to 8; The distribution distance d between the heating gas pipeline and the center of the reformer is 17.5~22.5mm; The length L of the heating gas pipeline is 0.15~0.2m; Baffles are provided in the reformer.

[0038] According to the above simulation analysis, the range of structural parameters for achieving better comprehensive performance of the reformer has been screened out. In order to further determine the most specific values ​​of the structure and seek the optimal solution of geometric parameters for optimal reformer performance, on the basis of the above simulation analysis, the multi-objective optimization method is used to continue the simulation analysis to obtain the optimal structural parameters.

[0039] Specifically, this embodiment uses a multi-objective optimization genetic algorithm to establish a multi-objective optimization model, mainly optimizing the structural parameter range n=5~8, d=17.5~22.5mm, L=0.15~0.2m, and taking the reforming conversion rate FUR, H 2 Output rate HPR, thermal efficiency TE as evaluation indicators. In this embodiment, each independent variable takes three levels within the set value range, and the overall variance of the combination design of multiple independent variables is set to 0.995. It can be considered that the result of the combination design is reliable; then calculate the reforming conversion rate FUR, HPR, and TE of each group. 2 The output rate HPR, thermal efficiency TE, and the comprehensive performance evaluation factor η of the reformer are calculated to comprehensively evaluate the heat exchange performance of the reformer.

[0040] Through optimization, it is found that when η is the largest, the corresponding values ​​are n=6, d=20mm, and L=0.2m.

[0041] The multi-physics field model established by the finite element software established in this embodiment is used to simulate the above results to verify the accuracy of the optimal structural parameters predicted by the multi-objective optimization model. The calculation results are compared and the reforming conversion rate error between the two is 2.35%, H 2 The output rate error is 0.931% and the thermal efficiency error is 0.771%, so the prediction model is considered accurate. Finally, the number of heating gas pipelines n of the diesel high-efficiency reformer is determined to be 6, the distance d from the center of the pipeline is 20.0 mm, and the length L of the heating gas pipeline is 0.15 m.

[0042] In addition, the above optimized internal heating pipeline reformer is compared with the traditional external heating reformer, and η is increased by 37.21%. By optimizing the reformer channel structure, not only the diesel reforming conversion rate and hydrogen output rate of the diesel reformer are improved, but also the thermal efficiency is significantly improved, which solves the problems of low hydrogen production efficiency and low energy utilization efficiency of the traditional reformer, and greatly improves the comprehensive performance of the reformer.

[0043] It should be noted that some parts not described in the present invention can be implemented by adopting or drawing on existing technologies.

[0044] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for optimizing the structure of a high-efficiency diesel hydrogen reformer, characterized in that: Includes steps: S1. Establish a three-dimensional structural model of a diesel hydrogen reformer, and import the three-dimensional structural model into a finite element analysis software. Set the physical parameters and assumptions required for finite element simulation according to the actual working conditions, set the control equations for gas flow and heat transfer and reforming reaction, and establish a multi-physics field model based on the coupling of material transfer, porous medium heat transfer, and fluid heat transfer. S2. Determine the main structural parameters that affect the reforming efficiency of the diesel hydrogen reformer; S3. According to the structural parameters determined in step S2, the multi-physical field model established in step S1 is used to obtain the reforming conversion rate, H2 output rate, thermal efficiency, and CO output rate of the diesel hydrogen reformer under different structural parameters as performance evaluation indicators of the diesel hydrogen reformer; and the reforming conversion rate, H2 output rate, and CO output rate indicators under different structural parameters are analyzed to select structural parameters that can increase the reforming conversion rate and H2 output rate of the diesel hydrogen reformer and / or reduce the CO output rate; S4. Based on the three performance evaluation indicators of the diesel hydrogen reformer, namely, reforming conversion rate, H2 output rate, and thermal efficiency, a comprehensive performance evaluation factor is established to verify the comprehensive performance of the diesel hydrogen reformer under the structural parameters determined in step S3.

2. The method for optimizing the structure of a high-efficiency diesel hydrogen production reformer according to claim 1, characterized in that: The three-dimensional structural model of the diesel hydrogen reformer in step S1 includes a reformer shell, a porous medium carrier for loading a catalyst arranged in the reformer shell, a plurality of heating gas pipes penetrating the porous medium carrier, and an insulation layer sleeved on the outside of the reformer shell, and the inlet end of the porous medium carrier is used to input a mixed gas of diesel and superheated steam, and the outlet end of the porous medium carrier is used to output H2 and CO.

3. The method for optimizing the structure of a high-efficiency diesel hydrogen production reformer according to claim 2, characterized in that: The assumptions set in the multi-physics model in step S1 include: (a) The mixed reactants of diesel and superheated steam are uniformly mixed before entering the reformer, and the temperature of the superheated steam has been preheated to the same temperature as the diesel. The mixed reactants of diesel and superheated steam enter the reformer in a gaseous state; (b) The mixed reactant of diesel and superheated steam is an ideal gas, incompressible, and the flow state is steady laminar flow; (c) Ignore the effect of gravity; (d) Ignore the effect of catalyst coating on the reforming reaction; (e) Ignore thermal radiation during the reaction.

4. The method for optimizing the structure of a high-efficiency diesel hydrogen production reformer according to claim 1, characterized in that: The main structural parameters affecting the reforming efficiency of the diesel hydrogen reformer in step S2 include: The number of heating gas pipelines n is used to adjust the heat exchange area of ​​the mixed gas of heating gas, diesel and superheated steam; The distribution distance d of the heating gas pipeline from the center of the reformer is used to adjust the heat transfer efficiency of the reformer; The heating gas pipeline length L is used to adjust the convection heat exchange time of the mixed gas of the heating gas, diesel and superheated steam; Whether baffles are provided in the porous medium carrier to adjust the reforming efficiency of the reformer.

5. The method for optimizing the structure of a high-efficiency diesel hydrogen production reformer according to claim 4, characterized in that: The step S3 specifically includes: S31, setting different numbers of heating gas pipelines n, and in the diesel hydrogen production multi-physics field model established in step S1, setting the total heat transfer area of ​​the heating gas pipelines to be the same, simulating and calculating the reforming conversion rate, H2 output rate, and CO output rate under different numbers of heating gas pipelines, and selecting the number of heating gas pipelines n that can increase the reforming conversion rate and H2 output rate of the diesel hydrogen production reformer and / or reduce the CO output rate; S32, setting different distribution distances d between the heating gas pipeline and the center of the reformer, using the diesel hydrogen production multi-physics field model established in step S1 to simulate and calculate the reforming conversion rate, H2 output rate, and CO output rate at different distribution distances, and selecting the distribution distance d between the heating gas pipeline and the center of the reformer that can increase the reforming conversion rate and H2 output rate of the diesel hydrogen production reformer and / or reduce the CO output rate; S33, setting different heating gas pipeline lengths L, using the diesel hydrogen production multi-physical field model established in step S1 to simulate and calculate the reforming conversion rate, H2 output rate, and CO output rate under different lengths L, and selecting a heating gas pipeline length L that can increase the reforming conversion rate and H2 output rate of the diesel hydrogen production reformer and / or reduce the CO output rate; S34. Use the diesel hydrogen production multi-physics field model established in step S1 to simulate and calculate the diesel hydrogen production reformer with and without baffles, obtain the reforming conversion rate, H2 output rate, and CO output rate when the baffles are set and when the baffles are not set, and conduct a comparative analysis. If the reforming conversion rate and H2 output rate are improved and / or the CO output rate is reduced when the baffles are set, it means that the baffles can improve the reforming efficiency of the diesel hydrogen production reformer. Otherwise, there is no need to set the baffles.

6. The method for optimizing the structure of a high-efficiency diesel hydrogen production reformer according to claim 4, characterized in that: The calculation formula of the comprehensive performance evaluation factor in step S4 is: ； in: ； ； ； In the formula, is a comprehensive performance evaluation factor, FUR is the reforming conversion rate, HPR is the H2 output rate, TE is the thermal efficiency, , , are the weights of reforming conversion rate, H2 output rate and thermal efficiency in the comprehensive performance evaluation of diesel hydrogen reformer, and ; is the diesel inlet molar concentration; is the diesel outlet molar concentration; is the hydrogen outlet molar concentration; is the outlet molar concentration of carbon monoxide; It is the low calorific value of hydrogen; It is the lower heating value of carbon monoxide; Total heat input for heating gas.

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