A method for loading a fixed bed reactor catalyst

Abstract

The application belongs to the field of catalysts in the field of chemistry, and particularly relates to a loading method for a catalyst of a fixed bed reactor with tubes. The loading method comprises: (1) feeding; (2) forming: (2-1) mixing water, a binder and the catalyst and freezing to obtain a low-temperature catalyst; (2-2) preparing a frozen core; (2-3) thawing and removing decomposition products. After automatic feeding, the loading method mixes water, a binder and the catalyst and freezes to obtain a low-temperature catalyst, and then prepares a frozen core, thaws and removes decomposition products, so that the loading precision and reliability are improved, the labor intensity of on-site workers is reduced, the contact between the on-site workers and the catalyst is reduced, health problems caused by the catalyst are reduced, the catalyst loading time can be controlled, and the loading quality of the catalyst is ensured.

Description

Technical Field

[0001] This invention belongs to the field of catalysts in the chemical field, and specifically relates to a method for loading catalysts for a tubular fixed-bed reactor. Background Technology

[0002] The quality and yield of a catalyst directly affect product quality and production safety. Catalyst loading is a routine operation in chemical production, especially during catalyst replacement. One reason for improper catalyst use is improper loading. Improper loading leads to varying pressure drops in different tubes, resulting in uneven gas flow distribution in the catalyst bed. This causes significant differences in the heat release and heat transfer rates in each reaction tube, leading to temperature variations and, in severe cases, localized overheating and catalyst deactivation.

[0003] Tubular reactors are widely used in ethylene epoxidation. In China, large ethylene epoxidation reactors now have over 30,000 tubes, with reactors having 10,000-20,000 tubes being more common. Loading the catalyst into these reactors presents a significant challenge. Currently, manual loading is the most common method, but this manual operation lacks precision control, impacting production efficiency. Specialized loading machines are expensive and require manual assistance. Furthermore, the reactor is a closed space with pervasive catalyst dust, creating a harsh working environment unsuitable for prolonged work and high-quality loading. Approximately 2%-5% of tubular reactor loadings fail to meet requirements, and about 1% require rework due to catalyst bridging. This negatively impacts worker health, production time, and company profits. Summary of the Invention

[0004] The purpose of this invention is to address the above-mentioned technical problems by providing a method for loading catalysts for tubular fixed-bed reactors that reduces the labor intensity of on-site workers, improves work efficiency, and enhances loading accuracy.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] This invention provides a method for loading a catalyst into a tubular fixed-bed reactor, the method comprising:

[0007] (1) Adding ingredients:

[0008] The catalyst is added to the molding device using a feeding device;

[0009] (2) Molding:

[0010] (2-1) Preparation of low-temperature catalysts:

[0011] Water, binder and catalyst are mixed and frozen to obtain a low-temperature catalyst;

[0012] (2-2) Preparation of cryogenic core:

[0013] The low-temperature catalyst is filled into the core-making box and optionally compacted to obtain the core to be hardened.

[0014] Low-temperature gas is blown in for freezing until a frozen core is obtained;

[0015] Insert the frozen-formed core into the tubes until the tubes are filled;

[0016] (2-3) Thaw and remove decomposition products:

[0017] The reactor is heated, gas is blown into the top of the tubes to thaw the liquid, and the mixture of discharged liquid water and adhesive is collected.

[0018] The reactor is heated further, and gas is blown in to remove the decomposition products of the adhesive and optionally remove residual liquid water and adhesive, thus completing the filling process.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] The filling method of this invention, after automatic feeding, mixes water, binder and catalyst and freezes to obtain a low-temperature catalyst, then prepares a frozen core, thaws and removes decomposition products, which improves filling accuracy and reliability, reduces the labor intensity of on-site workers, reduces on-site workers' contact with the catalyst, and reduces health problems caused by the catalyst; the catalyst filling time can be controlled and the filling quality of the catalyst is guaranteed.

[0021] Other features and advantages of the present invention will be described in detail in the following detailed description section. Detailed Implementation

[0022] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0023] This invention provides a method for loading a catalyst into a tubular fixed-bed reactor, the method comprising:

[0024] (1) Adding ingredients:

[0025] The catalyst is added to the molding device using a feeding device;

[0026] (2) Molding:

[0027] (2-1) Preparation of low-temperature catalysts:

[0028] Water, binder and catalyst are mixed and frozen to obtain a low-temperature catalyst;

[0029] (2-2) Preparation of cryogenic core:

[0030] The low-temperature catalyst is filled into the core-making box and optionally compacted to obtain the core to be hardened.

[0031] Low-temperature gas is blown in for freezing until a frozen core is obtained;

[0032] Insert the frozen-formed core into the tubes until the tubes are filled;

[0033] (2-3) Thaw and remove decomposition products:

[0034] The reactor is heated, gas is blown into the top of the tubes to thaw the liquid, and the mixture of discharged liquid water and adhesive is collected.

[0035] The reactor is heated further, and gas is blown in to remove the decomposition products of the adhesive and optionally remove residual liquid water and adhesive, thus completing the filling process.

[0036] In step (2-3), the reason for "optionally removing residual liquid water and adhesive" is that when the mixture of liquid water and adhesive has been completely collected, the blown gas will only remove the decomposition products of the adhesive and there is no longer a need to remove residual liquid water and adhesive.

[0037] As a preferred option, those skilled in the art can select the type of adhesive as needed, as long as it is harmless to the catalyst and can achieve adhesion. Preferably, the adhesive is a plant-based gum, such as at least one selected from dextrin, cyclodextrin, and starch solution.

[0038] As a preferred embodiment, in step (2-1), the amount of water added is 0.1 to 15 wt% relative to the total weight of water, binder, and catalyst. More preferably, the amount of water added is 1 to 5 wt%.

[0039] As a preferred embodiment, in step (2-1), the amount of adhesive added is 0.1–15 wt% relative to the total weight of water, adhesive, and catalyst. More preferably, the amount of adhesive added is 2–6 wt%.

[0040] As a preferred embodiment, in step (2-1) of the present invention, the mixing and freezing method is one of the following methods;

[0041] Method I:

[0042] A low-temperature catalyst is obtained by mixing water, binder and catalyst while freezing; more preferably, the mixing method includes spraying a mixed solution of water and binder onto the surface of the frozen catalyst.

[0043] Method II:

[0044] Water, binder and catalyst are mixed evenly and then frozen to obtain a low-temperature catalyst.

[0045] As a preferred option, the temperature of the obtained low-temperature catalyst is -0.1℃ to -150℃, and more preferably -1℃ to -10℃.

[0046] As a preferred option, in step (2-2), the temperature at which the cryogenic gas is blown in for freezing is -0.1℃ to -150℃, and more preferably -10℃ to -30℃.

[0047] As a preferred embodiment, in step (2-2), the cryogenic gas is selected from at least one of air, liquid nitrogen, and carbon dioxide, and the cryogenic gas optionally includes water; the water is in liquid and / or solid and / or gaseous state.

[0048] As a preferred embodiment, in steps (2-3), the thawing temperature is 0.1–100°C, and the space velocity of the gas blown in during thawing is 0.1–2000 h⁻¹. -1 .

[0049] As a preferred embodiment, in steps (2-3), the temperature after further heating is 100–240°C, and the space velocity of the injected gas is 0.1–2000 h⁻¹. -1 .

[0050] As a preferred option, in step (2-3), the gas blown in is at least one of compressed air, nitrogen, argon and carbon dioxide.

[0051] As a preferred option, the core is cylindrical with a length of 0.1 to 1 m and a diameter less than the inner diameter of the tube.

[0052] As a preferred option, the inner diameter of the tube is 20-60mm.

[0053] As a preferred option, the catalyst is cylindrical, and the catalyst here refers to the catalyst that has not undergone shaping treatment;

[0054] As a preferred embodiment, the feeding device includes a hopper and a switch, the switch being used to control the amount and rate of catalyst addition.

[0055] The present invention will be further described below with reference to the embodiments, but the scope of the present invention is not limited to these embodiments.

[0056] In this embodiment of the invention, the filling device used is a filling device commonly used by those skilled in the art.

[0057] In this embodiment of the invention, the catalyst to be loaded is a cylindrical ethylene epoxide silver catalyst with a central hole.

[0058] In Embodiment 1 and Comparative Example 1 of the present invention, the tubular reactors used each contain ten reaction tubes with a diameter of 38 mm and a height of 9 m.

[0059] In Embodiment 2 and Comparative Example 2 of the present invention, the tubular reactors used each contain three reaction tubes with a diameter of 42 mm and a height of 8 m.

[0060] In Embodiment 3 and Comparative Example 3 of the present invention, the tubular reactors used each contain three reaction tubes with a diameter of 50 mm and a height of 7 m.

[0061] Comparative Example 1:

[0062] This comparative example provides a conventional loading method.

[0063] Four skilled workers were employed, and the filling time was 12 hours. After filling, one reaction tube did not meet the required catalyst loading amount due to catalyst bridging. The two ends of the reaction tube were tapped and filling continued, but the loading amount still did not meet the requirements. The catalyst was unloaded and refilled, and the target was met.

[0064] Example 1:

[0065] This embodiment provides a novel method for loading catalysts into a tubular fixed-bed reactor.

[0066] (1) Adding ingredients:

[0067] The loading machine and molding machine are located on the top platform of the reactor. The catalyst is poured into the feeding device and added to the molding device at a rate of 1 kg per hour. After entering the molding device, the catalyst is formed into a catalyst cryogenic core in two steps.

[0068] (2) Molding:

[0069] (2-1) Preparation of low-temperature catalysts:

[0070] The catalyst is prepared by mixing 95% catalyst, 2% water, 2% dextrin, and 1% cyclodextrin, and then freezing it to -10°C.

[0071] (2-2) Preparation of cryogenic core:

[0072] The catalyst core was set to a length of 60 cm and a diameter of 35 mm. The low-temperature catalyst was filled into the core-making box and compacted to obtain the core to be hardened. Then, -10°C air was blown in, and after 15 minutes, the core box was opened to obtain the frozen core. The core was then inserted into the reaction tube from the top by a worker wearing heat-resistant gloves until the reaction tube was completely filled.

[0073] (2-3) Thaw and remove decomposition products:

[0074] The reactor is heated to 50°C, and compressed air is blown into the top of the tubes at a space velocity of 800 h⁻¹. -1 A collection tube is fixed at the bottom of the tube to collect the discharged liquid water and the mixture of additives (dextrin, cyclodextrin), and the temperature is further increased to 230℃ for 1000 hours. -1 Compressed air is blown in at airspeed to remove the decomposition products of the additives.

[0075] It took a total of 8 hours for all ten reaction tubes to meet the filling requirements.

[0076] Comparative Example 2:

[0077] This comparative example provides a conventional loading method.

[0078] Three skilled workers were employed, and the filling time was 11 hours. After filling, the pressure drop in two reaction tubes was lower than the average value, which did not meet the filling requirements. A small amount of catalyst was added during the filling process, and the requirements were met.

[0079] Example 2:

[0080] This embodiment provides a novel method for loading catalysts into a tubular fixed-bed reactor.

[0081] (1) Adding ingredients:

[0082] The loading machine and molding machine are located on the top platform of the reactor. The catalyst is poured into the feeding device and added to the molding device at a rate of 1 kg per hour. After entering the molding device, the catalyst is formed into a catalyst cryogenic core in two steps.

[0083] (2) Molding:

[0084] (2-1) Preparation of low-temperature catalysts:

[0085] The catalyst is prepared by mixing 93% catalyst, 3% water, 3% dextrin, and 1% cyclodextrin, and then freezing it to -5°C.

[0086] (2-2) Preparation of cryogenic core:

[0087] The catalyst core was set to a length of 80 cm and a diameter of 40 mm. The low-temperature catalyst was filled into the core-making box and compacted to obtain the core to be hardened. Then, -30°C carbon dioxide was blown in, and after 10 minutes, the core box was opened to obtain the frozen core. The core was then inserted into the reaction tube from the top by a worker wearing heat-resistant gloves until the reaction tube was filled.

[0088] (2-3) Thaw and remove decomposition products:

[0089] The reactor is heated to 40°C, and compressed air is blown into the top of the tubes at a space velocity of 1000 h⁻¹. -1A collection tube is fixed at the bottom of the tube to collect the discharged liquid water and the mixture of additives (dextrin, cyclodextrin), and the temperature is further increased to 240℃ for 1000 hours. -1 Compressed air is blown in at airspeed to remove the decomposition products of the additives.

[0090] It took a total of 9 hours for all ten reaction tubes to reach the filling requirements.

[0091] Comparative Example 3:

[0092] This comparative example provides a conventional loading method.

[0093] Three skilled workers were employed, and the filling time was 12 hours. After filling, the pressure drop of one reaction tube was higher than the average value. The filling volume was then unloaded and refilled, and the standard was met.

[0094] Example 3:

[0095] This embodiment provides a novel method for loading catalysts into a tubular fixed-bed reactor.

[0096] (1) Adding ingredients:

[0097] The loading machine and molding machine are located on the top platform of the reactor. The catalyst is poured into the feeding device and added to the molding device at a rate of 1 kg per hour. After entering the molding device, the catalyst is formed into a catalyst cryogenic core in two steps.

[0098] (2) Molding:

[0099] (2-1) Preparation of low-temperature catalysts:

[0100] The catalyst is prepared by mixing 94% catalyst, 3% water, 2% dextrin, and 1% cyclodextrin, and then freezing it to -5°C.

[0101] (2-2) Preparation of cryogenic core:

[0102] The catalyst core was set to a length of 100 cm and a diameter of 48 mm. The low-temperature catalyst was filled into the core-making box and compacted to obtain the core to be hardened. Nitrogen gas at -30°C was then blown in, and after 10 minutes, the core box was opened to obtain the frozen core. The core was then inserted into the reaction tube from the top by a worker wearing heat-resistant gloves until the tube was completely filled.

[0103] (2-3) Thaw and remove decomposition products:

[0104] The reactor is heated to 40°C, and compressed air is blown into the top of the tubes at a space velocity of 1000 h⁻¹. -1 A collection tube is fixed at the bottom of the tube to collect the discharged liquid water and the mixture of additives (dextrin, cyclodextrin), and the temperature is further increased to 240℃ for 1000 hours. -1Compressed air is blown in at airspeed to remove the decomposition products of the additives.

[0105] It took a total of 9 hours for all ten reaction tubes to reach the filling requirements.

[0106] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

[0107] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A method for loading catalyst into a tubular fixed-bed reactor, characterized in that, The loading method includes: (1) Adding ingredients: The catalyst is added to the molding device using a feeding device; (2) Molding: (2-1) Preparation of low-temperature catalysts: Water, binder and catalyst are mixed and frozen to obtain a low-temperature catalyst; (2-2) Preparation of cryogenic core: The low-temperature catalyst is filled into the core-making box; Low-temperature gas is blown in for freezing until a frozen core is obtained; Insert the frozen-formed core into the tubes until the tubes are filled; (2-3) Thaw and remove decomposition products: The reactor is heated, gas is blown into the top of the tubes to thaw the liquid, and the mixture of discharged liquid water and adhesive is collected. The reactor continues to heat up, and gas is blown in to remove the decomposition products of the binder, thus completing the filling process.

2. The method for loading catalyst into a tubular fixed-bed reactor according to claim 1, wherein, The gas is blown in to remove the decomposition products of the adhesive and to remove residual liquid water and adhesive.

3. The method for loading catalyst into a tubular fixed-bed reactor according to claim 1, wherein, The low-temperature catalyst is filled into the core-making box and compacted to obtain the core to be hardened.

4. The method for loading catalyst into a tubular fixed-bed reactor according to claim 1, wherein, The adhesive is harmless to the catalyst and can achieve bonding.

5. The method for loading catalyst into a tubular fixed-bed reactor according to claim 4, wherein, The adhesive is plant-based gum.

6. The method for loading catalyst into a tubular fixed-bed reactor according to claim 5, wherein, The plant gum is selected from dextrin and / or starch solution.

7. The method for loading catalyst into a tubular fixed-bed reactor according to claim 4, wherein, The adhesive is cyclodextrin and dextrin.

8. The method for loading catalyst into a tubular fixed-bed reactor according to claim 1, wherein, In step (2-1), relative to the total weight of water, binder, and catalyst, The amount of water added is 0.1–15 wt%; The amount of adhesive added is 0.1 to 15 wt%.

9. The method for loading catalyst into a tubular fixed-bed reactor according to claim 1, wherein, In step (2-1), the mixing and freezing are carried out in one of the following ways; Method I: A low-temperature catalyst is obtained by mixing water, binder and catalyst while freezing. Method II: Water, binder and catalyst are mixed evenly and then frozen to obtain a low-temperature catalyst.

10. The method for loading catalyst into a tubular fixed-bed reactor according to claim 9, wherein, Method I involves spraying a mixture of water and binder onto the surface of a frozen catalyst.

11. The method for loading catalyst for a tubular fixed-bed reactor according to claim 9, wherein, The temperature range of the obtained low-temperature catalyst is -0.1℃ to -150℃.

12. The method for loading catalyst into a tubular fixed-bed reactor according to claim 1, wherein, In step (2-2), the temperature at which the cryogenic gas is blown in for freezing is -0.1℃ to -150℃.

13. The method for loading catalyst into a tubular fixed-bed reactor according to claim 1, wherein, In step (2-2), The cryogenic gas is selected from at least one of air, liquid nitrogen, and carbon dioxide.

14. The method for loading catalyst for a tubular fixed-bed reactor according to claim 13, wherein, The cryogenic gas includes water, which may be in liquid and / or solid and / or gaseous states.

15. The method for loading catalyst into a tubular fixed-bed reactor according to claim 1, wherein, In steps (2-3), The thawing temperature is 0.1~100℃, and the space velocity of the gas blown in during thawing is 0.1~2000 h⁻¹. -1 ; The temperature after further heating is 100~240℃, and the space velocity of the injected gas is 0.1~2000 h⁻¹. -1 .

16. The method for loading catalyst for a tubular fixed-bed reactor according to claim 1, wherein, In steps (2-3), The gas blown in is at least one of compressed air, nitrogen, argon, and carbon dioxide.

17. The method for loading catalyst into a tubular fixed-bed reactor according to claim 1, wherein, The core is cylindrical, with a length of 0.1~1m and a diameter less than the inner diameter of the tube. The inner diameter of the tubes is 20-60mm; The catalyst is cylindrical; The feeding device includes a hopper and a switch, the switch being used to control the amount and rate of catalyst addition.