Method for oxygen-free loading, unloading and recycling of copper-based catalyst

Abstract

The invention discloses a method for oxygen-free loading, unloading and recycling of a copper-based catalyst, and relates to the technical field of reactor catalyst loading and unloading, and the method comprises the following steps: enabling the oxygen content in a conversion reactor of a hydrogen production device to be lower than 0.5%; a flange is provided with a blind plate to control the internal pressure of the device; the manhole of the hydrogen production device is connected with the ton box through a connecting pipe; dry ice is added into the ton box in batches, so that the copper-based catalyst slides into the ton box along the connecting pipe, and after all the copper-based catalyst is discharged, the temperature of the outer wall of the ton box is maintained; and after the hydrogen production device completes detection, the copper-based catalyst is reloaded. Oxygen in a conversion reactor of a hydrogen production device is controlled to be lower than 0.5%, and dry ice is put in the loading and unloading process, so that the interior of a ton box and the hydrogen production device can be effectively close to an anaerobic state, the contact time of a catalyst and oxygen in the loading and unloading process is reduced to the maximum extent, and active components of the catalyst are prevented from being in contact with oxygen in the loading and unloading process of the catalyst; the problems of spontaneous combustion and strength reduction are prevented, and the service life of the catalyst is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of reactor catalyst loading and unloading, and in particular to a method for oxygen-free loading and unloading and recycling of copper-based catalysts. Background Art

[0002] There are many kinds of catalysts in the oil refining process applications. According to the different active metal components, they are divided into precious metals and conventional metals. According to the operation cycle of the oil refining unit, the general unit needs to be overhauled once every four years. Since the active metals of some catalysts are very active, such as copper-based catalysts, they need to be soaked in water for passivation before being unloaded during the overhaul. After the catalyst is soaked in water, its strength and activity are affected and it cannot be reused.

[0003] There are a large number of catalysts using active metals as active components in the oil refining process. For example, copper-based catalysts are very active in the reduced state. Even if they come into contact with air at room temperature, the catalysts will spontaneously combust, or the copper grains will grow, the catalyst strength will decrease, and there will be serious breakage. According to the active life of the catalyst, it can meet the 8-year use requirement, but according to the national container inspection specifications, it is necessary to enter the reactor for inspection regularly. Therefore, during the maintenance period after 4 years of operation, the catalyst needs to be unloaded and the container needs to be inspected. In order to control the risks of the catalyst unloading process, the catalyst is usually arranged to be passivated by soaking in water. After passivation, the catalyst strength decreases significantly and cannot be reused, so it can only be replaced as a whole. The replacement of the catalyst will occupy the three-dose cost of the device, and at the same time generate a large amount of solid waste and wastewater, increasing the environmental pressure of the refinery.

[0004] CN 87103259A discloses a method for unloading and recycling a medium temperature shift catalyst. The medium temperature shift catalyst does not need to be passivated before unloading, but is cooled to between 70° and 20°C by cold nitrogen circulation before unloading. After screening, it is directly loaded into the reactor. It is aimed at the loading and unloading and recycling of catalysts whose main components are Fe-Cr oxides, and it is not carried out in an oxygen-free environment. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for oxygen-free loading and unloading of a copper-based catalyst for reuse, thereby ensuring the strength and activity of the catalyst during the unloading process.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for anaerobic loading and unloading and recycling of a copper-based catalyst comprises the following steps:

[0008] Use nitrogen to replace the oxygen in the hydrogen production device to convert the oxygen content in the reactor to less than 0.5%;

[0009] Blind plates are installed on the inlet and outlet flanges of the shift reactor, and the internal pressure of the shift reactor is maintained between 0.02 and 0.05 MPa by nitrogen supplementation;

[0010] Connect the manhole of the shift reactor to the tote box using a connecting pipe;

[0011] Put 400-600g of dry ice in the ton box, and let the copper-based catalyst slide into the ton box along the connecting pipe. When the ton box is 30-35% filled, put 400-600g of dry ice in the ton box. When the ton box is 65-70% filled, put 400-600g of dry ice in the ton box. When the ton box is 90-95% filled, put 400-600g of dry ice in the ton box.

[0012] After all copper-based catalysts are unloaded, the temperature of the outer wall of the ton box is tested and maintained by adding dry ice to the ton box;

[0013] After the hydrogen production unit conversion reactor is inspected, the copper-based catalyst is reinstalled.

[0014] As a preferred embodiment of the present invention, the connecting pipe includes a sleeve and a hose connected to each other, the sleeve is used to connect to the manhole, and the sleeve is consistent with the opening of the manhole, and the hose is used to connect to the tote box.

[0015] As a preferred embodiment of the present invention, the mass percentage of copper oxide in the copper-based catalyst is ≥20%.

[0016] As a preferred embodiment of the present invention, the volume of the tonnage box is 0.5 to 10 m 3 .

[0017] As a preferred embodiment of the present invention, 500 g of dry ice is placed in the ton box, and the copper-based catalyst is allowed to slide into the ton box along the connecting pipe. When the ton box is 33% filled, 500 g of dry ice is placed in the ton box. When the ton box is 66% filled, 500 g of dry ice is placed in the ton box. When the ton box is 92% filled, 500 g of dry ice is placed in the ton box.

[0018] As a preferred embodiment of the present invention, the method for reloading the copper-based catalyst is specifically:

[0019] After the inspection of the hydrogen production device is completed, the copper-based catalyst is slipped into the conversion reactor of the hydrogen production device along the connecting pipe. When the ton box has 90-95% remaining, 400-600g of dry ice is put into the ton box. When the ton box has 65-70% remaining, 400-600g of dry ice is put into the ton box. When the ton box has 30-35% remaining, 400-600g of dry ice is put into the ton box until the reloading is completed.

[0020] As a preferred embodiment of the present invention, the method for reloading the copper-based catalyst is specifically:

[0021] After the inspection of the hydrogen production device is completed, the copper-based catalyst is slipped into the hydrogen production device along the connecting pipe. When the ton box has 92% remaining, 500g of dry ice is put into the ton box. When the ton box has 66% remaining, 400-600g of dry ice is put into the ton box. When the ton box has 33% remaining, 500g of dry ice is put into the ton box until the reloading is completed.

[0022] As a preferred embodiment of the present invention, during the reloading of the copper-based catalyst, the oxygen content in the shift reactor of the hydrogen production device is maintained below 0.5%.

[0023] As a preferred embodiment of the present invention, during the reloading of the copper-based catalyst, the internal temperature of the shift reactor of the hydrogen production device is maintained within 65°C.

[0024] As a preferred embodiment of the present invention, after the copper-based catalyst is reloaded, the manhole is sealed and nitrogen is added to maintain the pressure in the reactor between 0.02 and 0.05 MPa and the oxygen content <0.5%, so that the device enters the start-up state.

[0025] The beneficial effects of the present invention are as follows: (1) The present invention controls the oxygen in the hydrogen production device conversion reactor to be less than 0.5%, and uses dry ice to be placed during the loading and unloading process, which can effectively make the ton box and the hydrogen production device conversion reactor close to an oxygen-free state, thereby maximally reducing the time that the catalyst is in contact with oxygen during the catalyst unloading process, maintaining the catalyst active components from contacting oxygen during the catalyst unloading process, preventing the problem of spontaneous combustion and strength reduction, and basically solving the problem that the active metal catalyst cannot be reused after being unloaded, thereby extending the service life of the catalyst. (2) The present invention puts dry ice in batches into the ton box according to the loading ratio of the copper-based catalyst (the ratio of the catalyst to the volume of the ton box). Dry ice is a solid and can be fully volatilized when heated. After volatilization, the dry ice is converted into carbon dioxide. The molecular weight of carbon dioxide is 44, which is larger than the molecular weight of air (28), so it can discharge the residual air in the ton box, so that the ton box reaches a nearly oxygen-free state. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of the structure of an exemplary hydrogen production device. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] In the present invention, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0029] In the present invention, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0030] The reagents or instruments used in the present invention without indicating the manufacturer are all conventional products that can be obtained through commercial purchase.

[0031] Existing hydrogen production equipment, such as shift reactors, need to be regularly inspected and maintained in accordance with national container inspection specifications (mandatory inspection), that is, the hydrogen production equipment needs to complete regular inspections every four years. During the inspection, the catalyst needs to be unloaded and the container must be inspected. However, general catalysts, such as copper-based catalysts, have an active lifespan that can meet the 8-year usage requirement. Therefore, how to ensure the strength and activity of the catalyst during the unloading process has become a technical problem that needs to be urgently solved by technicians in this field.

[0032] The existing method of unloading the catalyst generally involves soaking the catalyst in water to passivate it, causing its strength to drop significantly before unloading it. However, this method cannot reuse the catalyst and it can only be replaced, which greatly increases the processing cost. In addition, a large amount of solid waste and wastewater are generated, increasing the environmental pressure on the refinery.

[0033] The embodiment of the present invention provides a method for anaerobic loading and unloading and recycling of a copper-based catalyst, comprising the following steps:

[0034] Use nitrogen to replace the oxygen in the hydrogen production device to convert the oxygen content in the reactor to less than 0.5%;

[0035] The inlet and outlet flanges of the hydrogen production unit conversion reactor are equipped with blind plates (also known as flange covers) to maintain the internal pressure of the unit between 0.02 and 0.05 MPa by nitrogen supplementation;

[0036] Use a connecting pipe to connect the manhole of the hydrogen production unit shift reactor and the ton box;

[0037] Put 400-600g of dry ice in the ton box, and let the copper-based catalyst slide into the ton box along the connecting pipe. When the ton box is 30-35% filled, put 400-600g of dry ice in the ton box. When the ton box is 65-70% filled, put 400-600g of dry ice in the ton box. When the ton box is 90-95% filled, put 400-600g of dry ice in the ton box.

[0038] After all copper-based catalysts are unloaded, the temperature of the outer wall of the ton box is tested and maintained by adding dry ice to the ton box;

[0039] After the hydrogen production unit conversion reactor is inspected, the copper-based catalyst is reinstalled.

[0040] The CuO content in copper-based catalysts is relatively high (according to the catalyst activity, it can be used for 8 years). During the shutdown process, the catalyst is very active in the reduced state. Even if it comes into contact with air at room temperature, the catalyst will spontaneously combust, or the copper grains in the catalyst will grow, the catalyst strength will decrease, and there will be serious breakage. After the oxidized low-temperature shift catalyst is reduced, the catalyst activity is difficult to restore to its original state.

[0041] The inventors of the present invention creatively control the oxygen in the conversion reactor of the hydrogen production device to less than 0.5%, and use dry ice to drop in the loading and unloading process, which can effectively make the tonnage box and the conversion reactor of the hydrogen production device close to an oxygen-free state, thereby maximally reducing the time that the catalyst is in contact with oxygen during the unloading process, maintaining that the active components of the catalyst will not be in contact with oxygen during the unloading process of the catalyst, preventing the problem of spontaneous combustion and strength reduction, and basically solving the problem that the active metal catalyst cannot be reused after being unloaded, thereby extending the service life of the catalyst.

[0042] Dry ice is added in batches according to the loading ratio of the copper-based catalyst (the ratio of the catalyst to the volume of the ton box) in the ton box. Dry ice is solid and can be fully volatilized when heated. After volatilization, the dry ice is converted into carbon dioxide. The molecular weight of carbon dioxide is 44, which is larger than the molecular weight of air (28). Therefore, it can discharge the residual air in the ton box and make the ton box reach a nearly oxygen-free state.

[0043] It should be noted that the hydrogen production device is a conventional hydrogen production device of the company, such as a shift reactor, etc.

[0044] In one embodiment, the connecting pipe includes a sleeve and a hose connected to each other, the sleeve is used to connect to the manhole, and the sleeve is consistent with the opening of the manhole, and the hose is used to connect to the tote box.

[0045] It should be noted that the structural diagram of the connecting pipe is not shown in the present invention. Due to the difference in apertures, the sleeve and the hose in the connecting pipe can be treated with shrinkage holes at the connection point to make them seamlessly connected. In addition, the sleeve only needs to be consistent with the opening of the manhole.

[0046] As a preferred embodiment of the present invention, the mass percentage of copper oxide in the copper-based catalyst is ≥20%.

[0047] In one embodiment, the volume of the tonnage box is 0.5 to 10 m 3 .

[0048] In one embodiment, 500 g of dry ice is placed in the ton box, and the copper-based catalyst is allowed to slide into the ton box along the connecting pipe. When the ton box is 33% filled, 500 g of dry ice is placed in the ton box. When the ton box is 66% filled, 500 g of dry ice is placed in the ton box. When the ton box is 92% filled, 500 g of dry ice is placed in the ton box.

[0049] In one embodiment, the method for reloading the copper-based catalyst is specifically:

[0050] After the inspection of the conversion reactor of the hydrogen production unit is completed, the copper-based catalyst is slipped into the conversion reactor of the hydrogen production unit along the connecting pipe. When the ton box has 90-95% remaining, 400-600g of dry ice is put into the ton box. When the ton box has 65-70% remaining, 400-600g of dry ice is put into the ton box. When the ton box has 30-35% remaining, 400-600g of dry ice is put into the ton box until the reloading is completed.

[0051] The present invention adopts the unloading method in the process of reloading the catalyst, which can effectively make the ton box and the conversion reactor of the hydrogen production device close to the oxygen-free state, thereby maximally reducing the time of the catalyst contacting with oxygen during the unloading process, maintaining the active components of the catalyst from contacting with oxygen during the unloading process of the catalyst, preventing the problem of spontaneous combustion and strength reduction, and basically solving the problem that the active metal catalyst cannot be reused after being unloaded, thereby extending the service life of the catalyst.

[0052] In one embodiment, the method for reloading the copper-based catalyst is specifically:

[0053] After the inspection of the conversion reactor of the hydrogen production unit is completed, the copper-based catalyst is slipped into the conversion reactor of the hydrogen production unit along the connecting pipe. When the ton box has 92% remaining, 500g of dry ice is put into the ton box. When the ton box has 66% remaining, 400-600g of dry ice is put into the ton box. When the ton box has 33% remaining, 500g of dry ice is put into the ton box until the reloading is completed.

[0054] In one embodiment, during the reloading of the copper-based catalyst, the oxygen content in the shift reactor of the hydrogen production unit is maintained below 0.5%.

[0055] In one embodiment, during the reloading of the copper-based catalyst, the internal temperature of the hydrogen production device shift reactor is maintained within 65°C.

[0056] In one embodiment, after the copper-based catalyst is reloaded, the manhole is sealed, and nitrogen is added to maintain the pressure in the reactor between 0.02 and 0.05 MPa and the oxygen content is less than 0.5%, so that the device enters the start-up state.

[0057] Example 1

[0058] Figure 1 The hydrogen production low-temperature conversion reactor shown (a conventional device, since the present invention does not involve its internal structure, it only involves the unloading and use of the copper-based catalyst, so its structure will not be repeated, wherein M1, M2, M3, and M4 are manholes).

[0059] As shown in Table 1, the hydrogen production low-temperature shift reactor was overhauled in 2017 and replaced with a new copper-based catalyst. The CuO content of the copper-based catalyst is above 35%. The catalyst is very active in the reduced state during the shutdown process. Even if it comes into contact with air at room temperature, it will cause the catalyst to spontaneously combust, or the catalyst will experience copper grain growth, catalyst strength reduction, and serious breakage. After the oxidized low-temperature shift catalyst is reduced, the catalyst activity is difficult to restore to its original state. Therefore, the hydrogen production low-temperature shift catalyst generally has a service life of only 4 years, while it can be used for 8 years according to the catalyst activity.

[0060] From October 1, 2017 to December 1, 2017, its activity was monitored, and the monitoring results are shown in Table 1.

[0061] From June 1, 2021 to October 1, 2021, its activity was monitored, and the monitoring results are shown in Table 1.

[0062] From October to December 2021, after nearly 4 years of use, a strong inspection was required, and the copper-based catalyst was unloaded and reused using the following method so that it could be used normally.

[0063] A method for anaerobic loading and unloading and recycling of a copper-based catalyst comprises the following steps:

[0064] (1) During the shutdown process of the low-temperature shift reactor (hereinafter referred to as the hydrogen production unit), the temperature and pressure are lowered, and nitrogen is used to replace the oxygen in the hydrogen production unit to reduce the oxygen content to less than 0.5%;

[0065] (2) Blind plates are installed on the inlet and outlet flanges of the hydrogen production device to maintain the internal pressure of the device between 0.02 and 0.05 MPa by nitrogen supplementation;

[0066] (3) Use a connecting pipe to connect the manhole of the hydrogen production device to the 2m 3The tonnage box (hereinafter referred to as the tonnage box), the connecting pipe includes a sleeve and a DN200 hose (hereinafter referred to as the hose) connected to each other, the sleeve is used to connect the manhole, and the opening of the sleeve is consistent with that of the manhole, the hose is used to connect the tonnage box, and the connection end of the sleeve and the hose is subjected to shrinkage treatment;

[0067] (4) Put 500g of dry ice in the ton box, and let the copper-based catalyst slide into the ton box through the connecting pipe. When the ton box is 33% filled, put 500g of dry ice in the ton box. When the ton box is 66% filled, put 500g of dry ice in the ton box. When the ton box is 92% filled, put 500g of dry ice in the ton box. It should be noted that when the manhole cannot be unloaded naturally, arrange for the unloading professionals to wear positive pressure respirators to enter the reactor (take good protection according to anaerobic operation) and unload the remaining catalyst into the ton box through the hose;

[0068] (5) After all copper-based catalysts are unloaded, the temperature of the outer wall of the ton box is tested and maintained by adding dry ice to the ton box;

[0069] (6) After the hydrogen production device is tested, the copper-based catalyst is slipped into the hydrogen production device along the connecting pipe. When the ton box is 92% full, 500g of dry ice is placed in the ton box. When the ton box is 66% full, 500g of dry ice is placed in the ton box. When the ton box is 33% full, 500g of dry ice is placed in the ton box until the reloading is completed;

[0070] During the reloading of the copper-based catalyst, the oxygen content in the hydrogen production unit was maintained below 0.5% by nitrogen supplementation.

[0071] During the reloading of the copper-based catalyst, the internal temperature of the hydrogen production device is maintained within 65°C. If over-temperature occurs, the operation is stopped and nitrogen is added to replace the gas in the reactor. The reloading operation is arranged after the temperature is restored.

[0072] (7) After the copper-based catalyst is reloaded, the manhole is sealed and nitrogen is added to maintain the pressure in the reactor between 0.02 and 0.05 MPa and the oxygen content less than 0.5%, so that the device enters the start-up state.

[0073] After the overhaul was completed, its activity was monitored from December 1, 2021 to December 2, 2021. The monitoring results are shown in Table 1. Although the low-transformer CO removal rate after the overhaul in 2021 was lower than the removal rate before the overhaul and after the overhaul in 2017, it could meet the CO content requirement of the downstream methanation system of <0.41%; due to the low CO outlet of the high-transformer, the total reaction temperature rise of the low-transformer was low; from the low-transformer temperature distribution, the hot spot temperature was at the lower part of the upper bed layer, and the catalyst in the lower bed layer had not yet risen in temperature, which was similar to the hot spot temperature position after the overhaul in 2017 and before the overhaul in 2021. Therefore, it was judged that the activity of the low-transformer catalyst was maintained well after the overhaul. Judging from the start-up and operating conditions after the overhaul, it can fully meet the production needs.

[0074] Table 1

[0075]

[0076]

[0077]

[0078]

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for anaerobic loading and unloading of copper-based catalysts for reuse, characterized in that: The following steps are involved: Replace the oxygen in the hydrogen production unit with nitrogen to reduce the oxygen content to less than 0.5%; The flange of the hydrogen production device is installed with a blind plate, and the internal pressure of the device is maintained between 0.02 and 0.05 MPa by nitrogen supplementation; Use a connecting pipe to connect the manhole of the hydrogen production device and the ton box; Put 400-600g of dry ice in the ton box, and let the copper-based catalyst slide into the ton box along the connecting pipe. When the ton box is 30-35% filled, put 400-600g of dry ice in the ton box. When the ton box is 65-70% filled, put 400-600g of dry ice in the ton box. When the ton box is 90-95% filled, put 400-600g of dry ice in the ton box. After all copper-based catalysts are unloaded, the temperature of the outer wall of the ton box is tested and maintained by adding dry ice to the ton box; After the hydrogen production device is inspected, the copper-based catalyst is reinstalled.

2. The method for anaerobic loading and unloading and recycling of copper-based catalysts according to claim 1, characterized in that: The connecting pipe includes a sleeve and a hose that are connected to each other. The sleeve is used to connect to the manhole, and the opening of the sleeve is consistent with that of the manhole. The hose is used to connect to the tonnage box.

3. The method for anaerobic loading and unloading and recycling of copper-based catalysts according to claim 1, characterized in that: The mass percentage of copper oxide in the copper-based catalyst is ≥20%.

4. The method for anaerobic loading and unloading and recycling of copper-based catalysts according to claim 1, characterized in that: The volume of the ton box is 0.5 to 10 m 3 .

5. The method for anaerobic loading and unloading and recycling of copper-based catalysts according to claim 1, characterized in that: Put 500g of dry ice in the ton box and allow the copper-based catalyst to slide into the ton box along the connecting pipe. When the ton box is 33% filled, put 500g of dry ice in the ton box. When the ton box is 66% filled, put 500g of dry ice in the ton box. When the ton box is 92% filled, put 500g of dry ice in the ton box.

6. The method for anaerobic loading and unloading and recycling of copper-based catalysts according to claim 1, characterized in that: The method for reloading the copper-based catalyst is specifically as follows: After the hydrogen production device is inspected, the copper-based catalyst is slipped into the hydrogen production device along the connecting pipe. When the ton box has 90-95% remaining, 400-600g of dry ice is placed in the ton box. When the ton box has 65-70% remaining, the finished product is placed in the ton box.

7. The method for anaerobic loading and unloading and recycling of copper-based catalysts according to claim 6, characterized in that: The method for reloading the copper-based catalyst is specifically as follows: After the inspection of the hydrogen production device is completed, the copper-based catalyst is slipped into the hydrogen production device along the connecting pipe. When the ton box has 92% remaining, 500g of dry ice is put into the ton box. When the ton box has 66% remaining, 400-600g of dry ice is put into the ton box. When the ton box has 33% remaining, 500g of dry ice is put into the ton box until the reloading is completed.

8. The method for anaerobic loading and unloading and recycling of copper-based catalysts according to claim 6, characterized in that: During the reinstallation of the copper-based catalyst, the oxygen content of the hydrogen production device is maintained below 0.5%.

9. The method for anaerobic loading and unloading and recycling of copper-based catalysts according to claim 6, characterized in that: During the reloading of the copper-based catalyst, the internal temperature of the hydrogen production device is maintained within 65°C.

10. The method for anaerobic loading and unloading and recycling of copper-based catalysts according to claim 6, characterized in that: After the copper-based catalyst is reloaded, the manhole is sealed and nitrogen is added to maintain the pressure in the reactor between 0.02 and 0.05 MPa and the oxygen content <0.5%, so that the device enters the start-up state.

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