A method and apparatus for adding a yield-enhancing low-carbon olefin aid

Abstract

The application discloses a method and equipment for adding a low-carbon olefin yield increasing additive. The adding equipment for the low-carbon olefin yield increasing additive comprises an additive tank, and an evacuation line, a pressure charging line, an additive adding line, a loose air line and an additive charging line are arranged on the additive tank; the low-carbon olefin yield increasing additive in the additive tank is directly added to a catalyst regeneration line through the additive adding line, so that fresh additive is enriched in the regenerated catalyst, and then is sent to a reactor to be contacted with raw oil, so that the low-carbon olefin yield increasing additive can fully play a role and the use efficiency of the additive is improved.

Description

Technical Field

[0001] This invention belongs to the field of petrochemicals, and specifically relates to a method and equipment for adding an additive to increase the production of low-carbon olefins. Background Technology

[0002] Catalytic cracking units are crucial secondary processing units in the oil refining industry and a vital link in refineries' transformation and upgrading, enabling them to reduce oil consumption and increase chemical production. With the rise of the new energy vehicle industry, refineries are required to reduce gasoline and diesel yields and increase liquefied petroleum gas (LPG) yields in their catalytic cracking units, particularly increasing the yields of low-carbon olefins such as ethylene and propylene. Adding appropriate low-carbon olefin-enhancing additives to the catalyst is a method that requires minimal engineering work, yields quick results, and allows for flexible adjustments.

[0003] Fluidized bed light hydrocarbon cracking units are an important production process for chemical feedstocks such as propylene and ethylene. Depending on the feedstock, they can be further divided into C3-C4 cracking, naphtha cracking, reforming residue cracking, and mixed light hydrocarbon cracking. In actual production, to increase feedstock conversion rates or adjust ethylene and propylene yields, one or more low-carbon olefin enhancement additives are often added.

[0004] As mentioned above, both catalytic cracking units and light hydrocarbon cracking units employ fluidized bed processes. Besides the main catalyst, specific additives play a crucial supporting role. Commonly used additives include CO combustion improvers, sulfur transfer agents, denitrification aids, and low-carbon olefin production enhancers (such as ZSM-5). Based on their mechanisms of action, additives can be classified into different types, and even within the same type, different models exist. Most additives are solid fine powder particles with a particle size distribution similar to the main catalyst used in the unit. Among them, CO combustion improvers, sulfur transfer agents, and denitrification aids mainly act on the coking reaction in the regenerator and can be called regenerator additives. Low-carbon olefin production enhancers are shape-selective molecular sieves that provide micropores, offering the acidic centers required for the cracking and pyrolysis reactions of small-molecule chain hydrocarbons in the riser reactor.

[0005] Conventional methods for adding adjuvants, such as Figure 1 As shown, the additive is added to the additive feeding tank through the additive feeding hopper. The bottom of the feeding tank is equipped with an additive feeding line, which connects to the catalyst feeding line. The additive is then sent to the regenerator via the additive and catalyst feeding lines, where it mixes with a large amount of catalyst. Finally, it is sent to the riser reactor along with the regenerated catalyst through the regeneration inclined tube. This conventional addition method is suitable for regenerator additives, but not for additives that increase the production of low-carbon olefins. The main reason is that the process of adding low-carbon olefin-increasing additives to the regenerator and mixing them with the catalyst is also a process of additive dilution. The amount of fresh additive finally entering the riser reactor with the regenerated catalyst is small, resulting in poor timeliness and low utilization efficiency.

[0006] Conventional methods of adding adjuvants have the following main drawbacks:

[0007] 1. Additives are generally packaged in bags and need to be manually added to the additive hopper, then transported to the feeding tank by gravity. Under normal pressure conditions, dust pollution near the additive hopper is unavoidable, which is detrimental to HSE management.

[0008] 2. To maintain the activity of the balanced catalyst, the spent catalyst needs to be unloaded during normal operation of the regenerator. Conventional additive addition methods cannot avoid the fact that some fresh additives will be unloaded along with the spent catalyst, resulting in high consumption of additives for increasing the production of low-carbon olefins.

[0009] 3. When selecting and evaluating various types of additives for increasing the production of low-carbon olefins, if conventional additive addition methods are used, the additives take longer to act, making it impossible to accurately assess their effectiveness or the relationship between the amount of additive added and the increase in olefin production. The evaluation process requires more time and consumes more additives.

[0010] 4. When the equipment is replaced with a new type of low-carbon olefin additive, the yield of low-carbon olefins is a gradual process, which affects economic benefits.

[0011] To address the numerous problems associated with conventional additive addition methods, this invention proposes a method and equipment for adding additives to increase the production of low-carbon olefins. Summary of the Invention

[0012] The purpose of this invention is to provide a method and equipment for adding low-carbon olefin additives to address the shortcomings of conventional additive addition methods, thereby reducing dust generated during the loading process, improving additive utilization efficiency, enriching the additive concentration in the regenerator, and increasing the yield of low-carbon olefins.

[0013] This invention provides a method and equipment for adding an additive to increase the production of low-carbon olefins, the technical solution of which is as follows.

[0014] A method for adding an additive to increase the yield of low-carbon olefins, characterized by comprising the following steps:

[0015] 1) Open the vacuum line valve to reduce the pressure in the additive tank to 0~0.09 MPaA. At this time, the valves of the pressurization line, additive line, and loosening air line are all closed. Then open the filling line valve to draw the additive into the additive tank until the additive in the tank reaches 20~90% of the tank capacity.

[0016] 2) Close the evacuation line valve, and open the loosening air line valves one by one. The loosening medium enters the additive tank, and fluidization begins at the bottom of the additive tank under the action of the loosening point. Open the pressurization line valve and control the pressure of the additive tank to 0.1~1.0MPaG, preferably 0.2~0.6MPaG. Open the additive line valve and add the additive to the catalyst regeneration line. The addition point is located upstream of the regeneration slide valve of the catalyst regeneration line. The low-carbon olefin additive is mixed with the regenerated catalyst and then sent to the reactor.

[0017] The present invention discloses a method for adding an additive to increase the production of low-carbon olefins, further characterized in that: the loosening medium is nitrogen or compressed air, and the operating pressure is 0.2~1.1 MPaG, preferably 0.3~0.7 MPaG.

[0018] An additive device for increasing the production of low-carbon olefins, used in the aforementioned method for adding the additive, is characterized in that: the additive device includes an additive tank, on which are provided a vacuum line, a pressurization line, an additive addition line, a loosening air line, and a loading line; each of the vacuum line, pressurization line, additive addition line, loosening air line, and loading line is equipped with a valve; the vacuum line is connected to the top of the additive tank; the pressurization line is connected to the upper part of the additive tank; the loosening air line enters from the bottom of the additive tank, and the entry point is the loosening point of the additive tank, which is used to maintain the fluidization state at the bottom of the additive tank; the additive addition line is led out from the fluidization area at the bottom of the additive tank and connected to the catalyst regeneration line; and the loading line is connected to the upper part of the additive tank.

[0019] The present invention discloses an additive device for increasing the production of low-carbon olefins, which is further characterized in that: the bottom of the additive tank is a conical structure with an included angle of 30 to 120 degrees, preferably 60 to 90 degrees, and the loosening point of the additive tank is located at the bottom cone.

[0020] This invention discloses an additive device for increasing the production of low-carbon olefins, further characterized in that: the vacuum line is also equipped with a dust removal facility, preferably a dust particle filter, which can be a bag filter or a metal filter element. Preferably, the vacuum line also includes a vacuuming device. The vacuuming device is recommended to be a steam vacuum pump, which can utilize 0.4~3.5MPa steam as the vacuuming medium; preferably, a mechanical vacuuming device, such as a liquid ring vacuum pump, is used.

[0021] The present invention discloses an addition device for increasing the production of low-carbon olefins, which is further characterized in that: a flow-limiting orifice plate (RO) can be installed on the loosening air line for throttling; it is recommended to set 2 to 7 loosening air lines, preferably 3 to 4; there are multiple loosening points, which are evenly arranged at the same elevation at the bottom of the additive tank.

[0022] The present invention discloses an additive device for increasing the production of low-carbon olefins, which is further characterized in that: the diameter of the additive line is in the range of 25~300mm, preferably 50~80mm.

[0023] This invention discloses a device for adding a low-carbon olefin additive, further characterized in that a sight glass can be installed on the additive addition line. The sight glass is used to observe the flow state of the additive in the pipeline, and the valve is used to adjust the additive addition rate.

[0024] The present invention discloses an additive device for increasing the production of low-carbon olefins, which is further characterized in that: the additive line is also equipped with an automatic additive addition facility, which is usually a small automatic additive addition facility that uses the weighing principle to add the additive in a quantitative manner.

[0025] This invention discloses an additive device for increasing the production of low-carbon olefins, further characterized in that: an electric heating system is installed outside the additive line, or an electric heating system is installed at the bottom of the additive tank, or electric heating systems are installed both outside the additive line and at the bottom of the additive tank. The electric heating system heats the additive, avoiding affecting the temperature of the regenerated catalyst and thus preventing large fluctuations in the reaction temperature.

[0026] The present invention provides a method and apparatus for adding low-carbon olefin additives, which can be used to add multiple low-carbon olefin additives simultaneously, rapidly enrich the additive concentration in the regenerated catalyst, and can also be used to add fresh catalyst to rapidly improve the activity of the regenerated catalyst sent to the riser reactor.

[0027] The present invention provides a method and apparatus for adding an additive to increase the yield of low-carbon olefins, which has the following advantages compared with the prior art:

[0028] 1. When loading low-carbon olefin production additives into the additive tank, negative pressure operation is used, which can significantly reduce the dust generated during the loading process.

[0029] 2. Fresh low-carbon olefin production enhancers are directly fed to the riser reactor along with the regenerated catalyst, significantly improving the efficiency of enhancer utilization.

[0030] 3. When evaluating and selecting various types of low-carbon olefin production-enhancing additives, the method and equipment provided by this invention reduce additive consumption, shorten evaluation time, and significantly improve evaluation efficiency.

[0031] 4. The spent catalyst normally removed by the regenerator does not contain fresh additives, thus reducing additive loss.

[0032] 5. Adding low-carbon olefin production additives directly to the regenerated catalyst makes it easier to operate according to the optimal ratio of additives to regenerators.

[0033] 6. Replacing the equipment with new low-carbon olefin additives, especially for equipment with large regenerator reserves, can quickly enrich the concentration of additives in the regenerated catalyst, and the yield of low-carbon olefins can be improved in a timely manner.

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but this does not limit the scope of the invention. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of a conventional method for adding additives.

[0036] Figure 2 This is a schematic diagram of the equipment for adding the first low-carbon olefin production additive of the present invention.

[0037] Figure 3 This is a schematic diagram of the equipment for adding the second type of low-carbon olefin production additive of the present invention.

[0038] Figure 4 , Figure 5 This is an example of the application of the present invention in the retrofitting of existing devices: Figure 4 A diagram showing the addition of additives before modification. Figure 5 This is a schematic diagram showing the addition of the modified additives.

[0039] The reference numerals in the figure are:

[0040] 1. Lifting section; 1-1. Pre-lifting section; 1-2. Feed nozzle; 2. Regenerator; 2-1. Catalyst regeneration line; 2-2. Regeneration slide valve; 3. Additive tank; 4. Pressurization line; 4-1. Pressurization line valve; 5. Loosening air line; 5-1. Loosening air line valve; 6. Additive loading line; 6-1. Additive loading line valve; 7. Additive dosing line; 7-1. Sight glass; 7-2. Additive dosing line valve; 8. Electric heat tracing equipment; 9. Vacuum equipment; 10. Dust removal equipment; 11. Automatic additive dosing equipment; 12. Vacuum line; 12-1. Vacuum line valve.

[0041] 20. Cold catalyst tank; 21. Catalyst tank top vortex separator; 22. Catalyst tank evacuation system; 23. Catalyst dosing line; 24. Existing additive tank; 25. Existing additive dosing hopper; 26. Existing additive dosing line. Detailed Implementation

[0042] like Figure 1 As shown, Figure 1 This is a schematic diagram of a conventional additive addition method. The additive is added to the additive feeding tank through the additive feeding hopper. The bottom of the feeding tank is equipped with an additive addition line, which is connected to the catalyst addition line. The additive is sent to the regenerator through the additive addition line and the catalyst addition line, where it is mixed with a large amount of catalyst in the regenerator. Finally, it is sent to the riser reactor through the regeneration inclined tube along with the regenerated catalyst.

[0043] Figure 2This is a schematic diagram of the addition equipment for the first type of low-carbon olefin production enhancement agent of the present invention. The top of the agent tank 3 is equipped with a dust removal device 10 and a vacuum device 9. The vacuum device 9 is a steam vacuum pump. The dust removal device 10 is located at the top of the agent tank 3 and is connected to the steam vacuum pump via a vacuum line 12. The upper part of the agent tank 3 is equipped with a pressurization line 4 and a filling line 6. The loosening air line 5 is located at the bottom of the agent tank 3 and enters from the bottom of the agent tank. The entry point of the loosening air line 5 is at the bottom of the agent tank. The moving point and loosening point are used to maintain the fluidization state at the bottom of the additive tank; the additive line 7 is led out from the fluidization area at the bottom of the additive tank and connected to the catalyst regeneration line 2-1. The additive line 7 is equipped with an electric heating facility 8. The evacuation line 12 is equipped with an evacuation line valve 12-1. The pressurization line 4 is equipped with a pressurization line valve 4-1. The additive line 7 is equipped with an additive line valve 7-2. The loosening air line 5 is equipped with a loosening air line valve 5-1. The loading line 6 is equipped with a loading line valve 6-1.

[0044] The additive line 7 is also equipped with a sight glass 7-1 for observing the additive flow rate.

[0045] like Figure 3 As shown, Figure 3 This is a schematic diagram of the device for adding the second type of low-carbon olefin production additive of the present invention, which is related to... Figure 2 The difference is: the top of the additive tank 3 is equipped with a dust removal facility 10, which is connected to the evacuation system of the catalyst tank through the evacuation line 12, that is, the additive and the catalyst share the same evacuation system; the addition line 7 does not have a sight glass 7-1, and the addition line valve 7-2 is replaced by an automatic addition facility 11. The automatic addition facility usually adopts a small automatic addition facility, which uses the weighing principle to add the additive in a quantitative manner.

[0046] Figure 4 and Figure 5 This is an implementation example of the invention used for the retrofitting of an existing plant. A 1.2 million tons / year catalytic cracking unit uses the invention to retrofit its existing additive addition system. Figure 4 A schematic diagram of the additive addition system before modification. Figure 5 A schematic diagram of a propylene additive addition facility to be modified and added for the purpose of using this invention.

[0047] like Figure 4 As shown, before the modification, the propylene additive and CO additive in the unit shared a set of additive process: the additive was incorporated into the catalyst additive line 23 through the existing additive additive hopper 25, the existing additive tank 24, and the existing additive additive line 26, and then sent to the regenerator through the catalyst additive line 23.

[0048] This invention allows for the addition of a propylene additive facility. Figure 5 The diagram shows the modifications after the upgrade. The cloud-lined areas represent the added features, which allow propylene additives to be added directly to the catalyst regeneration line and then sent to the riser reactor along with the regenerated catalyst.

[0049] In this implementation case, an additional propylene additive addition facility is added, specifically: an additive tank 3 is added, and an evacuation line 12, a pressurization line 4, an additive addition line 7, a loosening air line 5, and a filling line 6 are installed on the additive tank 3. Valves are installed on the pressurization line 4, the loosening air line 5, the filling line 6, the additive addition line 7, and the evacuation line 12. The auxiliary agent tank 3 has a diameter of 2m and a height of 3.5m. The bottom of the auxiliary agent tank is a conical structure with an included angle of 60 degrees. Three loosening air lines 5 are connected to the bottom of the conical tank 3, with three evenly distributed loosening points to maintain the fluidized state of the conical structure. A pressurization line 4 connects factory air to the upper part of the auxiliary agent tank 3, using the factory air to pressurize the auxiliary agent tank 3. A loading line 6 is connected to the upper part of the auxiliary agent tank 3. A vacuum line 12 connects the top of the auxiliary agent tank 3 to the top of the cold catalyst tank 20. The top vortex separator 21 of the cold catalyst tank 20 is connected to the catalyst tank vacuum system 22. The vacuum system uses a steam vacuum pump. Opening the vacuum line valve 12-1, with the aid of the catalytic converter... The top vortex separator of the catalyst tank and the evacuation system of the catalyst tank achieve negative pressure in the additive tank 3. The bottom of the cone of the additive tank 3 is connected to the addition line 7. The addition line 7 is equipped with a sight glass 7-1 and an addition line valve 7-2. The addition of additives can be observed through the sight glass 7-1 and the addition speed can be adjusted through the valve 7-2. The other end of the addition line 7 is connected to the catalyst regeneration line 2-1. The catalyst regeneration line 2-1 is equipped with a regeneration slide valve 2-2, and the connection point is upstream of the regeneration slide valve 2-2. The catalyst regeneration line 2-1 connects the regenerator 2 and the riser 1. The lower part of the riser section 1 is the pre-riser section 1-1, and the riser section 1 is equipped with a feed nozzle 1-2.

[0050] Figure 5 The newly added propylene additive addition facility includes both loading and addition operations. A simplified operation process is as follows:

[0051] During loading, the evacuation system 22 at the top of the cold catalyst tank 20 of the catalytic converter is activated, and the fine powder carried by the evacuation gas is removed through the top vortex separator 21 of the catalyst tank. The evacuation line valve 12-1 is opened to reduce the pressure of the additive tank 3 to a semi-vacuum. At this time, the pressure line 4, the additive line 7, and the three valves at risk of loosening 5 are all closed. The valve of the loading line 6 is opened to draw propylene additives into the additive tank 3 until the propylene additives in the additive tank 3 reach 70% of the tank capacity.

[0052] After the loading is completed, the evacuation system at the top of the cold catalyst tank 20 is shut down, and the evacuation line valve 12-1 is closed. The three loosening air line valves 5-1 are opened one by one. Under the action of the three loosening points, the bottom cone section of the additive tank 3 begins to fluidize. The pressurization line valve 4 is opened, and the pressure of the additive tank 3 is controlled to 0.5 MPaG using the factory air. The additive line valve 7-2 is opened, and the additive flow rate is observed through the sight glass 7-1. The propylene additive is sent to the regeneration inclined tube 2-1 through the additive line 7, where it is mixed with the regenerated catalyst. It is then sent to the pre-lifting section 1-1 through the regeneration slide valve 2-2. Under the lifting action of the pre-lifting medium, the propylene additive and the regenerated catalyst are mixed evenly and then sprayed upwards to contact the feed oil injected into the feed nozzle 1-2, and the reaction begins.

Claims

1. A method for adding an additive to increase the yield of low-carbon olefins, characterized in that... Includes the following steps: 1) Open the vacuum line valve to reduce the pressure in the additive tank to 0~0.09 MPaA. At this time, the valves of the pressurization line, additive line, and loosening air line are all closed. Then open the filling line valve to draw the additive into the additive tank until the additive in the tank reaches 20~90% of the tank capacity. 2) Close the evacuation line valve and open the loosening air line valve. The loosening medium enters the auxiliary agent tank from the bottom. Under the action of the loosening medium, the bottom of the auxiliary agent tank begins to fluidize. Open the pressurization line valve and control the pressure of the auxiliary agent tank to 0.1~1.0 MPaG. Open the valve of the additive line and add the additive to the catalyst regeneration line. The addition point is located upstream of the regeneration slide valve on the catalyst regeneration line.

2. The method for adding an additive to increase the yield of low-carbon olefins according to claim 1, characterized in that: The loosening medium is nitrogen or compressed air, and the operating pressure of the loosening air line is 0.2~1.1 MPaG.

3. The method for adding an additive to increase the yield of low-carbon olefins according to claim 2, characterized in that: The operating pressure for loosening the air line is 0.3~0.7 MPaG.

4. The method for adding an additive to increase the yield of low-carbon olefins according to claim 1, characterized in that: In step 2), the pressure of the auxiliary agent tank is controlled at 0.2~0.6 MPaG.

5. An apparatus for adding an additive to increase the yield of low-carbon olefins, used in the method for adding the additive to increase the yield of low-carbon olefins as described in claim 1, characterized in that: The equipment for adding the low-carbon olefin production enhancer includes an enhancer tank. The enhancer tank is equipped with an evacuation line, a pressurization line, an additive addition line, a loosening air line, and a loading line. Valves are installed on the evacuation line, pressurization line, additive addition line, loosening air line, and loading line. The evacuation line is connected to the top of the enhancer tank, the pressurization line is connected to the upper part of the enhancer tank, the loosening air line is connected from the bottom of the enhancer tank, the connection point is the loosening point of the enhancer tank, the additive addition line is led out from the fluidization area at the bottom of the enhancer tank and connected to the catalyst regeneration line, and the loading line is connected to the upper part of the enhancer tank.

6. The device for adding an additive to increase the yield of low-carbon olefins according to claim 5, characterized in that: The bottom of the auxiliary agent container is a conical structure with an included angle of 30 to 120 degrees. The loosening point of the auxiliary agent container is located at the bottom cone.

7. The device for adding an additive to increase the yield of low-carbon olefins according to claim 6, characterized in that: The cone at the bottom of the auxiliary agent container has an included angle of 60 to 90 degrees.

8. The device for adding an additive to increase the yield of low-carbon olefins according to claim 5, characterized in that: The vacuum line is also equipped with dust removal facilities.

9. The device for adding an additive to increase the yield of low-carbon olefins according to claim 8, characterized in that: The dust removal equipment is a dust particle filter, which uses bag filters or metal filter cartridges.

10. The device for adding an additive to increase the yield of low-carbon olefins according to claim 8, characterized in that: The vacuum line is also equipped with vacuuming facilities.

11. The device for adding an additive to increase the yield of low-carbon olefins according to claim 10, characterized in that: The evacuation system uses a steam evacuator.

12. The device for adding an additive to increase the yield of low-carbon olefins according to claim 5, characterized in that: Set 2 to 7 loosening air lines, and the number of loosening points is the same as the number of loosening air lines. The loosening points are evenly distributed at the same elevation at the bottom of the auxiliary agent tank.

13. The device for adding an additive to increase the yield of low-carbon olefins according to claim 5, characterized in that: The diameter of the additive line ranges from 25 to 300 mm.

14. The device for adding an additive to increase the yield of low-carbon olefins according to claim 5, characterized in that: A sight glass is provided on the additive line.

15. The device for adding an additive to increase the yield of low-carbon olefins according to claim 5, characterized in that: Automatic dosing facilities are installed on the dosing line.

16. The device for adding an additive to increase the yield of low-carbon olefins according to claim 5, characterized in that: Electric heat tracing facilities are installed outside the dosing line, or at the bottom of the additive tank, or both outside the dosing line and at the bottom of the additive tank are equipped with electric heat tracing facilities.

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