Catalyst filling method of axial-radial reactor
By adjusting the filling position of the catalyst in the radial reactor of the methanol synthesis shaft, the problem of excessive temperature at the bottom of the catalyst bed is solved, ensuring the safe operation of the reactor and improving methanol production.
Patent Information
- Application Number
- CN202411969544.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-30
- Publication Date
- 2025-04-29
AI Technical Summary
In the methanol synthesis axis radial reactor, the bottom of the catalyst bed is close to the inner wall of the reactor shell, and the methanol synthesis reaction is violent, resulting in excessive temperature and affecting the safe operation of the reactor.
By adjusting the bottom loading position of the catalyst, it is increased in the direction close to the reactor air outlet, shortening the circulation height of the synthesis gas at the bottom of the catalyst bed, thereby reducing the temperature at the bottom position. At the same time, according to the settling rate of the catalyst particles, determine the top loading position of the catalyst to ensure that it is always higher than the top tube plate, and avoid the problems of catalyst accumulation and excessive temperature.
The temperature at the bottom of the catalyst bed is effectively reduced, the difference between the maximum temperature and the average temperature is reduced, the risk of reactor damage is avoided, the safe operation of the reactor is ensured, and methanol production is improved.
Smart Images
Figure CN119897027A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of coal chemical industry and petroleum and natural gas chemical industry, and in particular to a catalyst loading method of an axial radial reactor. Background Art
[0002] The methanol synthesis axial radial reactor is a reactor that combines the axial and radial flow characteristics. It is suitable for methanol synthesis production and has the advantages of high efficiency and energy saving.
[0003] The basic structure of the methanol synthesis axial radial reactor includes a reactor shell, a central gas collecting pipe, a jacket inner cylinder and a catalyst bed. The upper and lower ends of the reactor shell are respectively provided with air inlets, and the left and right sides of the reactor shell are respectively provided with air outlets; the central gas collecting pipe is located at the center of the reactor shell; the jacket inner cylinder surrounds the periphery of the central gas collecting pipe, and forms an annular area with the central gas collecting pipe; the catalyst bed, i.e. the annular area formed between the jacket inner cylinder and the central gas collecting pipe, is the core place for methanol synthesis, and the catalyst is loaded in the catalyst bed; the upper and lower ends of the catalyst bed are respectively provided with a top tube sheet and a bottom tube sheet for supporting the catalyst, and the air outlet is located above the bottom tube sheet.
[0004] In the prior art, the catalyst is loaded from the bottom tube sheet to the top tube sheet. In the methanol synthesis reaction process, after the synthesis gas enters the reactor shell through the air inlet, it first enters the central gas collecting pipe, and then is guided to the catalyst bed through the central gas collecting pipe; in the catalyst bed, the synthesis gas contacts the catalyst, and the methanol synthesis reaction occurs. The methanol gas generated by the reaction and the incompletely reacted synthesis gas continue to pass through the catalyst bed until they are discharged through the gas outlet.
[0005] However, during normal production, the airflow in the top and bottom areas of the catalyst bed near the inner wall of the reactor shell is too concentrated, causing the methanol synthesis reaction at these locations to be intense, resulting in the temperature at these locations being about 40°C higher than the average temperature of the catalyst bed, making the catalyst bed at risk of being locally subjected to high temperature for a long time, restricting the production load; in addition, the granular catalyst will experience slight displacement and sedimentation after long-term contact with the high-pressure synthesis gas, causing the top of the catalyst to be slightly lower than the top tube sheet, resulting in catalyst accumulation at the bottom. The catalyst accumulation will intensify the methanol synthesis reaction at the bottom, causing the temperature at the bottom to be too high, affecting the safe operation of the reactor. Summary of the invention
[0006] In order to solve the technical problem in the background technology that the methanol synthesis reaction is violent in the area at the bottom of the catalyst bed near the inner wall of the reactor shell, resulting in excessively high temperature at the bottom position, the present invention provides a catalyst loading method for an axial radial reactor.
[0007] The catalyst loading method of the axial radial reactor of the present invention increases the bottom loading position of the catalyst toward the gas outlet of the reactor, shortens the flow height of the synthesis gas at the bottom of the catalyst bed, shortens the methanol synthesis reaction time at the bottom position, and then reduces the temperature at the bottom position, so that the difference between the maximum temperature and the average temperature of the catalyst bed is reduced, avoiding the risk of reactor damage due to excessive local temperature, and ensuring the safe operation of the reactor; at the same time, based on the estimation of the sedimentation velocity of the catalyst particles, the top loading position of the catalyst is determined to ensure that after the catalyst is settled, its top position is always higher than the top tube plate, avoiding the situation that the synthesis gas cannot be fully catalyzed after passing through the catalyst bed from the top, thereby increasing the methanol yield.
[0008] In order to solve the above technical problems, the present invention provides the following technical solutions:
[0009] A catalyst loading method for an axial radial reactor, comprising:
[0010] S1. Determine the bottom loading position of the catalyst: determine whether the bottom loading position of the catalyst needs to be raised toward the gas outlet of the reactor;
[0011] If not, the bottom loading position of the catalyst is not changed;
[0012] If so, determine the height of the catalyst bottom loading position closer to the reactor outlet to shorten the flow height of the synthesis gas at the bottom of the catalyst bed;
[0013] S2. Determine the top loading position of the catalyst: estimate the settling velocity of the catalyst particles, calculate the top loading position of the catalyst particles according to the settling velocity of the catalyst particles, and ensure that after the catalyst particles settle, the top position of the catalyst is always higher than the top tube sheet, so as to ensure that the methanol synthesis reaction is fully carried out;
[0014] S3, loading: loading the catalyst from the bottom loading position determined in step S1 to the top loading position determined in step S2, thereby completing the loading of the catalyst.
[0015] In a specific possible implementation scheme, the method for determining whether the bottom loading position of the catalyst needs to be raised toward the reactor outlet in step S1 is:
[0016] The maximum temperature of the catalyst bed is T1, and the average temperature of the catalyst bed is T2.
[0017] If T1-T2≤25℃, the bottom loading position of the catalyst will not be changed;
[0018] If 25℃<T1-T2<35℃, based on the original bottom loading position of the catalyst, the bottom loading height of the catalyst is increased by 3% of the original bottom loading height toward the reactor outlet;
[0019] If T1-T2≥35°C, based on the original bottom loading position of the catalyst, the bottom loading height of the catalyst is increased by 5% of the original bottom loading height toward the reactor outlet.
[0020] In a specific embodiment, the method for calculating the top loading position of the catalyst in step S2 is: according to the formula H = h + ∫ (SV t dt) Calculate the top loading position of the catalyst;
[0021] Wherein, H is the top filling height of the catalyst, unit: mm; S is the compensation coefficient; h is the catalyst filling height designed for the reactor, unit: mm; V t is the settling velocity of the catalyst, unit: m / s, and the settling velocity is estimated according to the Ergun equation.
[0022] In a specific embodiment, the influencing factors of the compensation coefficient S include the service life of the catalyst, the pressure of the synthesis gas and the degree of wear of the catalyst particles.
[0023] In a specific embodiment, the Ergun equation is
[0024]
[0025] Among them, V t represents the sedimentation velocity, unit: m / s; ε represents the porosity of the catalyst bed; ε s Indicates the maximum porosity of the catalyst bed; d g Indicates the diameter of the catalyst particles, unit: m; ρ g Indicates the density of the fluid, unit: kg / m 3 ρ p Indicates the density of catalyst particles, unit: kg / m 3 ; g represents the acceleration due to gravity, unit: m / s2; μ represents the dynamic viscosity of the fluid, unit: Pa·s.
[0026] In a specific embodiment, the bottom filling starting point of the catalyst is set within a range of 30 mm to 100 mm above the bottom tube sheet.
[0027] In a specific embodiment, the top filling end point of the catalyst is set within a range of 50 mm to 150 mm above the top tube sheet.
[0028] In one specific possible embodiment, the top position of the catalyst is always at least 30 mm above the top tube sheet.
[0029] In a specific possible implementation, during the filling process of step S3, the catalyst is filled in a layer-by-layer manner to ensure the uniformity and stability of the catalyst bed.
[0030] In a specific possible implementation mode, the catalyst loading method for the axial radial reactor further comprises: S4, after the catalyst loading is completed, compacting the catalyst bed to ensure the stability and catalytic efficiency of the catalyst bed.
[0031] In summary, the present invention includes the following beneficial technical effects:
[0032] 1. The catalyst loading method of the axial radial reactor of the present invention increases the bottom loading position of the catalyst toward the gas outlet of the reactor, shortens the flow height of the synthesis gas at the bottom of the catalyst bed, shortens the methanol synthesis reaction time at the bottom position, and then reduces the temperature at the bottom position, so that the difference between the maximum temperature and the average temperature of the catalyst bed is reduced, thereby avoiding the risk of reactor damage caused by excessive local temperature and ensuring the safe operation of the reactor; at the same time, based on the estimation of the sedimentation velocity of the catalyst particles, the top loading position of the catalyst is determined to ensure that after the catalyst settles, its top position is always higher than the top tube sheet, thereby avoiding the situation where the synthesis gas cannot be fully catalyzed after passing through the catalyst bed from the top, thereby increasing the methanol yield.
[0033] 2. The catalyst loading method of the axial radial reactor of the present invention accurately calculates the bottom loading position and the top loading position of the catalyst, so that the synthesis gas can contact and react with the catalyst more fully, thereby improving the reaction efficiency of the methanol synthesis reaction. At the same time, it reduces the emission of unreacted synthesis gas and improves the overall production efficiency and resource utilization of the methanol synthesis process. BRIEF DESCRIPTION OF THE DRAWINGS
[0034] Figure 1 It is a schematic diagram of the overall structure of the axial radial reactor of the present invention.
[0035] Explanation of the reference numerals: 1. bottom tube sheet; 2. top tube sheet; 3. reactor shell; 4. central gas collecting pipe; 5. inner cylinder of jacket; 6. gas outlet. DETAILED DESCRIPTION
[0036] The technical solution of the present invention is further explained below in conjunction with the accompanying drawings and embodiments, but the present invention is not limited to the implementation modes described below.
[0037] In the present invention, the axial radial reactor includes a reactor shell 3, a central gas collecting pipe 4, a jacket inner cylinder 5 and a catalyst bed. The upper and lower ends of the reactor shell 3 are respectively provided with air inlets, and the left and right sides of the reactor shell 3 are respectively provided with air outlets 6, and the diameter of the air outlet 6 is 10840mm; the central gas collecting pipe 4 is located at the center of the reactor shell 3; the jacket inner cylinder 5 surrounds the periphery of the central gas collecting pipe 4, and forms an annular area with the central gas collecting pipe 4; the catalyst bed is the annular area formed between the jacket inner cylinder 5 and the central gas collecting pipe 4; the upper and lower ends of the catalyst bed are respectively provided with a top tube sheet and a bottom tube sheet 1, and the distance between the top tube sheet and the bottom tube sheet is 12460mm. In the normal production process, the synthesis gas enters from the top and bottom of the reactor shell 3 at the same time, and under the catalytic action of the catalyst, a methanol synthesis reaction occurs and a large amount of heat is released, and the methanol gas generated by the reaction is discharged from the outlet 6.
[0038] Embodiment 1:
[0039] Reference Figure 1 , a catalyst loading method for an axial radial reactor, comprising:
[0040] S1. Determine the bottom loading position of the catalyst: determine whether the bottom loading position of the catalyst needs to be raised toward the reactor gas outlet 6;
[0041] If not, the bottom loading position of the catalyst is not changed;
[0042] If so, determine the height of the catalyst bottom loading position to be raised towards the reactor gas outlet 6 to shorten the flow height of the synthesis gas at the bottom of the catalyst bed;
[0043] Specifically, the method for determining whether the bottom loading position of the catalyst needs to be raised toward the reactor gas outlet 6 is as follows:
[0044] The maximum value of the catalyst bed temperature is T1, and the average value of the catalyst bed temperature is T2. The catalyst loaded at the bottom contains a thermocouple in the synthesis tower, which is used to accurately measure the temperature of the catalyst bed to avoid the situation where the thermocouple in the synthesis tower protrudes out of the catalyst bed and the temperature of the catalyst bed cannot be accurately measured.
[0045] If T1-T2≤25℃, the bottom loading position of the catalyst will not be changed;
[0046] If 25℃<T1-T2<35℃, then based on the original bottom loading position of the catalyst, the bottom loading height of the catalyst is increased by 3% of the original bottom loading height toward the reactor gas outlet 6;
[0047] If T1-T2≥35°C, based on the original catalyst bottom loading position, the catalyst bottom loading height is increased by 5% of the original bottom loading height in the direction close to the reactor gas outlet (6).
[0048] Specifically, in the present invention, the original bottom filling height of the catalyst is 900 mm; the bottom filling height of the catalyst is increased by 3% of the original bottom filling height toward the reactor outlet 6, and the bottom filling height of the catalyst is 927 mm; the bottom filling height of the catalyst is increased by 5% of the original bottom filling height toward the reactor outlet 6, and the bottom filling height of the catalyst is 945 mm.
[0049] More specifically, factors influencing the bottom loading position of the catalyst also include: the size of the reactor, the flow rate of the synthesis gas, and the performance of the catalyst.
[0050] As the reactor height increases, the flow path of the synthesis gas in the catalyst bed increases accordingly. The airflow will be more concentrated at the top and bottom of the catalyst bed close to the inner wall of the reactor shell 3. Correspondingly, the methanol synthesis reaction will be more intense, causing the temperature at these locations to further increase. At this time, the bottom loading position of the catalyst can be appropriately increased to shorten the circulation height of the synthesis gas at the bottom of the catalyst bed.
[0051] When the synthesis gas flow rate is large, more catalysts are needed to ensure the full progress of the methanol synthesis reaction. At this time, the bottom loading position of the catalyst can be appropriately lowered to increase the height and volume of the catalyst bed, thereby improving the reaction efficiency. Conversely, when the synthesis gas flow rate is small, the bottom loading position of the catalyst can be appropriately raised to reduce unnecessary catalyst use and reduce costs.
[0052] High-performance catalysts have higher reactivity and selectivity and can achieve higher conversion rates in shorter reaction times. Therefore, for high-performance catalysts, the bottom loading position can be appropriately raised to reduce the amount of catalyst used and reduce costs; for catalysts with poor performance, the bottom loading position can be appropriately lowered to increase the flow height of the synthesis gas at the bottom of the catalyst bed.
[0053] S2. Determine the top loading position of the catalyst: estimate the settling velocity of the catalyst, calculate the top loading position of the catalyst according to the settling velocity of the catalyst, and ensure that after the catalyst settles, the top position of the catalyst is always higher than the top tube sheet to ensure that the methanol synthesis reaction is fully carried out;
[0054] Specifically, the method for calculating the top loading position of the catalyst is: according to the formula H = h + ∫ (SV t dt) Calculate the top loading position of the catalyst;
[0055] Wherein, H is the top filling height of the catalyst, unit: mm; S is the compensation coefficient; h is the catalyst filling height designed for the reactor, unit: mm; V t is the settling velocity of the catalyst, unit: m / s, and the settling velocity is estimated according to the Ergun equation.
[0056] The Ergun equation is
[0057] Among them, V t represents the sedimentation velocity, unit: m / s; ε represents the porosity of the catalyst bed; ε s Indicates the maximum porosity of the catalyst bed; d g Indicates the diameter of the catalyst particles, unit: m; ρ g Indicates the density of the fluid, unit: kg / m 3 ρ p Indicates the density of catalyst particles, unit: kg / m 3 ; g represents the acceleration due to gravity, unit: m / s2; μ represents the dynamic viscosity of the fluid, unit: Pa·s.
[0058] More specifically, factors affecting the compensation coefficient S include the service life of the catalyst, the pressure of the synthesis gas, and the degree of wear of the catalyst particles.
[0059] As the catalyst ages, the activity of the catalyst gradually decreases, resulting in a decrease in the efficiency of the methanol synthesis reaction. As the catalyst ages, the compensation coefficient S gradually increases to compensate for the impact of the decrease in catalyst activity.
[0060] At higher syngas pressures, the friction between catalyst particles increases, causing the catalyst to settle faster. As syngas pressure increases, the compensation factor S gradually increases to compensate for the effects of increased pressure.
[0061] During use, catalyst particles will wear out, resulting in a decrease in catalyst particle size and a change in shape, which in turn affects the catalyst settling rate and the stability of the catalyst bed. As the degree of catalyst particle wear increases, the compensation coefficient S gradually increases to compensate for the impact of catalyst particle wear.
[0062] S3, loading: loading the catalyst from the bottom loading position determined in step S1 to the top loading position determined in step S2, thereby completing the loading of the catalyst.
[0063] Specifically, during the loading process, the catalyst is loaded layer by layer to ensure the uniformity and stability of the catalyst bed.
[0064] More specifically, during the process of loading the catalyst layer by layer, each loaded layer is compacted by vibration compaction or mechanical compaction. Preferably, the loaded catalyst layer is compacted by vibration compaction.
[0065] Reference Figure 1 The filling starting point of the catalyst bottom is set within the range of 30mm-100mm above the upper surface of the bottom tube plate.
[0066] In the present invention, the filling end point of the catalyst bottom can be 30 mm higher than the upper surface of the bottom tube sheet, 50 mm higher than the upper surface of the bottom tube sheet, or 100 mm higher than the upper surface of the bottom tube sheet. By raising the filling position of the catalyst bottom to a position close to the reactor gas outlet 6, the flow height of the synthesis gas at the bottom of the catalyst bed is shortened, thereby reducing the methanol synthesis reaction time at the bottom of the catalyst bed, thereby reducing the temperature at the bottom of the catalyst bed, and avoiding the risk of damage to the reactor caused by local high temperature at the bottom of the catalyst bed. Such settings are all acceptable. Preferably, the filling starting point of the catalyst bottom is set at 50 mm higher than the upper surface of the bottom tube sheet.
[0067] Reference Figure 1 The filling end point of the catalyst top is set within the range of 50mm-150mm above the upper surface of the top tube plate.
[0068] In the present invention, the loading end point of the catalyst top can be 50 mm higher than the upper surface of the top tube sheet, 100 mm higher than the upper surface of the top tube sheet, or 150 mm higher than the upper surface of the top tube sheet. By setting the loading end point of the catalyst top within a suitable range higher than the top tube sheet, the synthesis gas can still maintain sufficient contact with the catalyst after the catalyst settles, thereby increasing the methanol yield. Such settings are all acceptable. Preferably, the loading end point of the catalyst top is set at 100 mm higher than the upper surface of the top tube sheet, and at this time, the loading height of the catalyst is 12510 mm.
[0069] Reference Figure 1 In step S2, the top position of the catalyst is always at least 30 mm higher than the top tube sheet 2.
[0070] Specifically, there is no specific numerical limit on the distance that the top position of the catalyst is always higher than the top tube sheet. The top position of the catalyst can always be higher than the top tube sheet 2 by at least 30 mm, 40 mm, or 50 mm, to ensure that after the catalyst settles, the top position of the catalyst is always higher than the top tube sheet, to avoid the situation where the synthesis gas cannot be fully catalyzed after passing through the catalyst bed from the top. Such settings are all acceptable.
[0071] Embodiment 2:
[0072] Reference Figure 1 The catalyst loading method of the axial radial reactor of this embodiment, based on Example 1, further includes:
[0073] S4. After the catalyst is loaded, the catalyst bed is compacted to ensure the stability and catalytic efficiency of the catalyst bed.
[0074] In this embodiment, after the compaction process, the gaps between the catalyst particles are reduced, thereby reducing the possibility of displacement or sedimentation of the catalyst due to airflow scouring or gravity during use.
[0075] Embodiment 3:
[0076] Reference Figure 1 The catalyst loading method of the axial radial reactor in this embodiment is based on Example 1 and combined with H=h+∫(SV t dt);
[0077] In this embodiment, ε is 0.4, ε s is 0.45, d g is 5mm, ρ g 1.225kg / m 3 , ρ p 2700kg / m 3 , g is 9.81m / s 2 , μ is 1.81×10^-5Pa·s, the compensation coefficient S is set to 1.1, and the final H is 12510mm.
[0078] The above are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.
Claims
1. A catalyst loading method for an axial radial reactor, characterized in that: include: S1. Determine the bottom loading position of the catalyst: determine whether the bottom loading position of the catalyst needs to be raised toward the reactor gas outlet (6); If not, the bottom loading position of the catalyst is not changed; If so, the catalyst bottom loading position is determined to be raised in a direction close to the reactor gas outlet (6) to shorten the flow height of the synthesis gas at the bottom of the catalyst bed; S2. Determine the top loading position of the catalyst: estimate the settling velocity of the catalyst, calculate the top loading position of the catalyst according to the settling velocity of the catalyst, and ensure that after the catalyst settles, the top position of the catalyst is always higher than the top tube sheet (2), so as to ensure that the methanol synthesis reaction is fully carried out; S3, loading: loading the catalyst from the bottom loading position determined in step S1 to the top loading position determined in step S2, thereby completing the loading of the catalyst.
2. The catalyst loading method for an axial radial reactor according to claim 1, characterized in that: The method for determining whether the bottom loading position of the catalyst needs to be raised toward the reactor gas outlet (6) in step S1 is: The maximum temperature of the catalyst bed is T1, and the average temperature of the catalyst bed is T2. If T1-T2≤25℃, the bottom loading position of the catalyst will not be changed; If 25°C < T1-T2 < 35°C, based on the original catalyst bottom loading position, the catalyst bottom loading height is increased by 3% of the original bottom loading height toward the reactor gas outlet (6); If T1-T2≥35°C, based on the original catalyst bottom loading position, the catalyst bottom loading height is increased by 5% of the original bottom loading height in the direction close to the reactor gas outlet (6).
3. The catalyst loading method for an axial radial reactor according to claim 1, characterized in that: The method for calculating the top loading position of the catalyst in step S2 is: according to the formula H = h + ∫ (SV t dt) Calculate the top loading position of the catalyst; Wherein, H is the top filling height of the catalyst, unit: mm; S is the compensation coefficient; h is the catalyst filling height designed for the reactor, unit: mm; V t is the settling velocity of the catalyst, unit: m / s, and the settling velocity is estimated according to the Ergun equation.
4. The catalyst loading method for an axial radial reactor according to claim 3, characterized in that: The influencing factors of the compensation coefficient S include the service life of the catalyst, the pressure of the synthesis gas and the degree of wear of the catalyst particles.
5. The catalyst loading method for an axial radial reactor according to claim 3, characterized in that: The Ergun equation is Among them, V t represents the sedimentation velocity, unit: m / s; ε represents the porosity of the catalyst bed; ε s Indicates the maximum porosity of the catalyst bed; d g Indicates the diameter of the catalyst particles, unit: m; ρ g Indicates the density of the fluid, unit: kg / m 3 ρ p Indicates the density of catalyst particles, unit: kg / m 3 ; g represents the acceleration due to gravity, unit: m / s 2 ; μ represents the dynamic viscosity of the fluid, unit: Pa·s.
6. The catalyst loading method for an axial radial reactor according to claim 3, characterized in that: The catalyst bottom filling starting point is set within the range of 25 mm to 100 mm above the bottom tube sheet (1).
7. The catalyst loading method for an axial radial reactor according to claim 6, characterized in that: The top filling end point of the catalyst is set within the range of 50 mm to 150 mm above the top tube sheet (2).
8. The catalyst loading method for an axial radial reactor according to claim 1, characterized in that: The top position of the catalyst is always at least 30 mm above the top tube sheet (2).
9. The catalyst loading method for an axial radial reactor according to claim 1, characterized in that: During the filling process of step S3, the catalyst is filled layer by layer to ensure the uniformity and stability of the catalyst bed.
10. The catalyst loading method for an axial radial reactor according to claim 9, characterized in that: The catalyst loading method of the axial radial reactor also includes: S4. After the catalyst is loaded, the catalyst bed is compacted to ensure the stability and catalytic efficiency of the catalyst bed.