A cleaning method and cleaning device for solid products in an ethylene oligomerization reactor

Abstract

The present application relates to the technical field of ethylene oligomerization reaction, in particular to a cleaning method and cleaning device for solid products in an ethylene oligomerization reactor, which comprises: injecting a cleaning agent into the reactor, raising the temperature in the reactor and stirring and dissolving the solid products in the reactor to obtain liquid material containing polyethylene; discharging the liquid material containing polyethylene into a mixed liquid collecting tank; then injecting an oligomerization solvent into the ethylene oligomerization reactor, and after stirring and flushing, discharging the same into the mixed liquid collecting tank; after the temperature of the liquid in the mixed liquid collecting tank is reduced to room temperature, the solid products are precipitated and then sent into a separation device for separation, and the filtrate and the residue are collected respectively. The cleaning method for the solid products in the ethylene oligomerization products in the present application avoids the disassembly of the reactor by the operator and the direct contact with the residual material in the reactor, ensures the safety of the personnel, removes the solid products attached to the reactor in a non-opening mode, improves the cleaning efficiency, and promotes the continuous production of the reactor.

Description

Technical Field

[0001] This invention relates to the field of ethylene oligomerization reaction technology, specifically to a method and apparatus for cleaning solid products in an ethylene oligomerization reactor. Background Technology

[0002] Linear α-olefins refer to straight-chain monoolefins with double bonds located at the ends of the molecular chain. They are widely used in high-density polyethylene, low-density polyethylene, surfactants, lubricants, detergents, oilfield chemicals, and other fields. 1-Hexene and 1-octene are mainly used as comonomers for high-end polyethylene. 1-Octene can also be used as a raw material for polyα-olefins, and its demand is constantly increasing. Compared with traditional methods such as coal extraction, extraction separation, alkane catalytic cracking, and alkane dehydrogenation, the preparation of 1-hexene and 1-octene by ethylene oligomerization, especially selective oligomerization, has the advantages of being cleaner and more efficient.

[0003] During the selective oligomerization of ethylene, target products such as 1-hexene and 1-octene are generated under the action of a catalyst, while a small amount of C is also generated. 10 and C 10 The above describes liquid olefins and polyethylene byproducts. Currently, most research focuses on improving the activity of ethylene oligomerization catalysts, enhancing the selectivity of 1-hexene and 1-octene, especially 1-octene, and reducing the formation of high molecular weight polyethylene byproducts during oligomerization. However, polyethylene byproducts have not been completely eliminated in current research. These byproducts are generated during the reaction and mostly adhere to the agitator and the inner wall of the reactor. As the reaction continues, polyethylene formation accelerates, affecting catalyst performance. Simultaneously, the heat transfer capacity of the reactor inner wall is affected by the polyethylene buildup, and the continuous accumulation of polyethylene at pipe inlets eventually leads to blockages, necessitating reactor shutdown for cleaning, significantly hindering continuous operation. Currently, reactor cleaning is mainly done manually by opening and closing the reactor, typically using high-pressure water jets. This manual cleaning process requires opening and closing the reactor, and there are issues with severe polyethylene buildup that is difficult to remove, along with a strong odor inside the reactor, increasing safety hazards for operators. Therefore, completing the reactor cleaning without opening the reactor, reducing the direct contact between operators and the materials inside the reactor, shortening the reactor cleaning time, and simplifying the process also plays an important role in promoting the industrialization of selective oligomerization of ethylene. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method and apparatus for cleaning solid products in an ethylene oligomerization reactor. This method avoids operators from disassembling the reactor body and directly contacting residual materials inside the reactor, ensuring personnel safety. It also improves cleaning efficiency and promotes continuous production in the reactor.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for cleaning solid products in an ethylene oligomerization reactor, comprising the following steps:

[0006] S1. Empty the material in the ethylene oligomerization reactor, inject cleaning agent into the reactor, raise the temperature inside the reactor, and stir to dissolve the solid product in the reactor to obtain a liquid material containing polyethylene.

[0007] S2. Discharge the liquid material containing polyethylene into the mixed liquid collection tank;

[0008] S3. Subsequently, the oligomerization reaction solvent is injected into the ethylene oligomerization reactor, and after stirring and rinsing, it is also discharged into the mixed liquid collection tank.

[0009] S4. After the liquid temperature in the mixed liquid collection tank drops to room temperature, the solid product precipitates out and is then sent to the separation device for separation, and the filtrate and filter residue are collected separately.

[0010] Preferably, in step S1, the cleaning agent is 1,1,2,2-tetrachloroethane, with a volume fraction of 60-100%.

[0011] Preferably, in step S1, the level of the cleaning agent injected into the ethylene oligomerization reactor is higher than the level of a conventional oligomerization reaction.

[0012] Preferably, in step S1, the temperature inside the ethylene oligomerization reactor is 80-150℃.

[0013] Preferably, in step S3, the oligomerization solvent is one or more of toluene, xylene, mesitylene, pentane, cyclopentane, methylcyclopentane, hexane, cyclohexane, methylcyclohexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, 1-hexene, 1-octene, 1-decene, dichloromethane, dichloroethane, chlorobenzene, o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene, bromobenzene, o-dibromobenzene, m-dibromobenzene, p-dibromobenzene, and iodobenzene.

[0014] Preferably, in steps S1-S3, the temperature of the pipeline between the ethylene oligomerization reactor and the mixed liquid collection tank is controlled to be 80-150°C.

[0015] The present invention also provides a cleaning device for solid products in an ethylene oligomerization reactor, comprising a cleaning agent storage tank; an ethylene oligomerization reactor connected to the cleaning agent storage tank; a solvent storage tank and a mixture collection tank connected to the ethylene oligomerization reactor; a separation device connected to the mixture collection tank; a filtrate recovery tank and a filter residue collection tank connected to the separation device; the filtrate recovery tank is connected to the ethylene oligomerization reactor.

[0016] This invention provides a method and apparatus for cleaning solid products in an ethylene oligomerization reactor, which has the following advantages compared with the prior art:

[0017] This invention utilizes the characteristic that the solid product can dissolve in 1,1,2,2-tetrachloroethane under high-temperature conditions to complete the vessel cleaning process without opening the vessel. The resulting liquid material is easily transferred out of the vessel, shortening the vessel shutdown time. Simultaneously, the solubility of the solid product, mainly polyethylene, in 1,1,2,2-tetrachloroethane is highly sensitive to temperature; during the cooling process of the liquid material, it precipitates and floats on the surface of the cleaning agent. In subsequent separation processes, the solid product can be collected and the cleaning agent recovered using conventional separation methods. Furthermore, the morphology of the precipitated polyethylene changes from large lumps or a thin film adhering to the vessel wall and agitator to more fluid granules, facilitating subsequent transfer and collection.

[0018] After the liquid material containing polyethylene is discharged from the reactor, the inner wall of the reactor is rinsed with an ethylene selective oligomerization reaction solvent and transported to a mixed liquid collection tank to remove the residual liquid material containing polyethylene in the reactor, ensuring the normal use of the reactor in the future. During the rinsing process, the reactor is kept under heat to prevent solid products from re-precipitating and remaining in the reactor.

[0019] This invention employs a heat tracing pipeline to maintain a high temperature in pipelines transporting liquid materials containing polyethylene, preventing blockage caused by the precipitation of solid products due to cooling, and ensuring the smooth flow of the transport pipeline.

[0020] The cleaning method for solid products in ethylene oligomerization products of this invention avoids operators from disassembling the reactor and directly contacting residual materials inside the reactor, ensuring personnel safety. At the same time, it removes solid products attached to the reactor without opening the reactor, improving cleaning efficiency and promoting continuous production in the reactor. Attached Figure Description

[0021] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0022] Figure 1 This is a schematic diagram of the cleaning device in this invention;

[0023] In the diagram: 1- Cleaning agent storage tank, 2- Ethylene oligomerization reactor, 3- Solvent storage tank, 4- Mixed liquid collection tank, 5- Separation device, 6- Filtrate recovery tank, 7- Filter residue collection tank. Detailed Implementation

[0024] The following embodiments are provided to illustrate the implementation of this application in detail, so that the process of how this application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0025] Example 1

[0026] A cleaning device for solid products in an ethylene oligomerization reactor includes a cleaning agent storage tank; an ethylene oligomerization reactor connected to the cleaning agent storage tank; a solvent storage tank and a mixture collection tank connected to the ethylene oligomerization reactor; a separation device connected to the mixture collection tank; a filtrate recovery tank and a filter residue collection tank connected to the separation device; the filtrate recovery tank is connected to the ethylene oligomerization reactor.

[0027] The pipeline between the ethylene oligomerization reactor and the mixed liquid collection tank is equipped with a heat tracing line to maintain the temperature, thereby preventing the liquid material containing polyethylene from precipitating solid products and clogging the pipeline due to temperature drop during transportation.

[0028] After the liquid in the mixed liquid collection tank is cooled to room temperature, most of the solid products will precipitate and float on the surface of the liquid. After entering the separation device, the liquid can be drawn from the bottom to complete most of the recovery. Then, the liquid and solid products are further separated by filtration, pressure filtration or centrifugation.

[0029] The cleaning device described in this embodiment solves the problem of cleaning solid products remaining in the ethylene oligomerization reactor, avoids the cumbersome work of opening and closing the reactor in conventional reactor cleaning, and avoids direct contact between operators and materials inside the reactor, shortening the cleaning time of the reactor and promoting the continuous process of ethylene oligomerization reaction.

[0030] Example 2

[0031] A method for cleaning solid products in an ethylene oligomerization reactor, comprising the following steps:

[0032] S1. Empty the material in the ethylene oligomerization reactor, and inject 1,1,2,2-tetrachloroethane with a volume fraction of 80% as a cleaning agent into the reactor. The 1,1,2,2-tetrachloroethane is injected to the 75% liquid level (60% liquid level for conventional oligomerization reactions). The reactor is heated to 125°C through its own jacket, and the solid products in the reactor are stirred and dissolved to obtain a liquid material containing polyethylene.

[0033] S2. The liquid material containing polyethylene is discharged into the mixed liquid collection tank through a pipeline with a heat tracing line; the pipeline temperature is controlled at 125℃ during the process.

[0034] S3. Then, toluene, the oligomerization solvent, is injected into the ethylene oligomerization reactor. After stirring and rinsing, the mixture is also discharged into the mixed liquid collection tank.

[0035] S4. After the liquid temperature in the mixed liquid collection tank drops to room temperature, the solid product precipitates out and is then sent to the separation device for separation, and the filtrate and filter residue are collected separately.

[0036] S5. The filtrate can be temporarily stored and returned to the ethylene oligomerization reactor as cleaning liquid for the next cleaning.

[0037] In this embodiment, the cleaning device from Example 1 is used. The cleaning agent recovery rate reaches 87.4%. Simultaneously, after the reactor is cleaned, an ethylene oligomerization reaction is carried out, and the reactor operation returns to normal. The cleaning agent recovery time is not included in this timeframe; the reactor cleaning time is 5 hours.

[0038] Example 3

[0039] A method for cleaning solid products in an ethylene oligomerization reactor, comprising the following steps:

[0040] S1. Empty the material in the ethylene oligomerization reactor, inject the previously generated filtrate into the reactor as a cleaning agent, and add 1,1,2,2-tetrachloroethane to make the mixture reach 75% liquid level in the reactor. Heat the mixture to 125°C through the reactor's jacket and stir to dissolve the solid product in the reactor to obtain a liquid material containing polyethylene.

[0041] S2. The liquid material containing polyethylene is discharged into the mixed liquid collection tank through a pipeline with a heat tracing line; the pipeline temperature is controlled at 125℃ during the process.

[0042] S3. Then, toluene, the oligomerization solvent, is injected into the ethylene oligomerization reactor. After stirring and rinsing, the mixture is also discharged into the mixed liquid collection tank.

[0043] S4. After the liquid temperature in the mixed liquid collection tank drops to room temperature, the solid product precipitates out and is then sent to the separation device for separation, and the filtrate and filter residue are collected separately.

[0044] S5. The filtrate can be temporarily stored and returned to the ethylene oligomerization reactor as cleaning liquid for the next cleaning.

[0045] In this embodiment, the cleaning device from Example 1 is used. The cleaning agent recovery rate reaches 85.3%. Simultaneously, after the reactor is cleaned, an ethylene oligomerization reaction is carried out, and the reactor operation returns to normal. The cleaning agent recovery time is not included in this timeframe; the reactor cleaning time is 5 hours.

[0046] Example 4

[0047] It is basically the same as Example 2, except that the oligomerization solvent is p-xylene.

[0048] Example 5

[0049] It is basically the same as Example 2, except that the oligomerization solvent is dichloromethane.

[0050] Comparative Example 1

[0051] The commonly used manual method for cleaning the reactor was employed. After the reactor was shut down and the materials were emptied, operators with appropriate protective measures opened the reactor. Upon opening, the operators first removed the larger solid products, then used a high-pressure water gun to thoroughly rinse the inside of the reactor and the agitator to ensure no significant solid product residue remained. The reactor and agitator were then dried and finally reassembled. After reassembly, the ethylene oligomerization reaction was carried out, and the reactor operation returned to normal. Under favorable environmental conditions, the reactor cleaning was completed over two days, with a total cleaning time of 16 hours.

[0052] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for cleaning solid products in an ethylene oligomerization reactor, characterized in that, Includes the following steps: S1. Empty the material in the ethylene oligomerization reactor, inject cleaning agent into the reactor, raise the temperature inside the reactor, and stir to dissolve the solid product in the reactor to obtain a liquid material containing polyethylene. The cleaning agent is 1,1,2,2-tetrachloroethane, with a volume fraction of 60-100%. S2. Discharge the liquid material containing polyethylene into the mixed liquid collection tank; S3. Subsequently, the oligomerization reaction solvent is injected into the ethylene oligomerization reactor, and after stirring and rinsing, it is also discharged into the mixed liquid collection tank. S4. After the liquid temperature in the mixed liquid collection tank drops to room temperature, the solid product precipitates out and is then sent to the separation device for separation, and the filtrate and filter residue are collected separately.

2. The method for cleaning solid products in an ethylene oligomerization reactor according to claim 1, characterized in that, In step S1, the level of the cleaning agent injected into the ethylene oligomerization reactor is higher than the level of the conventional oligomerization reaction.

3. The method for cleaning solid products in an ethylene oligomerization reactor according to claim 1, characterized in that, In step S1, the temperature inside the ethylene oligomerization reactor is 80-150℃.

4. The method for cleaning solid products in an ethylene oligomerization reactor according to claim 1, characterized in that, In step S3, the oligomerization solvent is one or more of toluene, xylene, mesitylene, pentane, cyclopentane, methylcyclopentane, hexane, cyclohexane, methylcyclohexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, 1-hexene, 1-octene, 1-decene, dichloromethane, dichloroethane, chlorobenzene, o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene, bromobenzene, o-dibromobenzene, m-dibromobenzene, p-dibromobenzene, and iodobenzene.

5. The method for cleaning solid products in an ethylene oligomerization reactor according to claim 1, characterized in that, In steps S1-S3, the temperature of the pipeline between the ethylene oligomerization reactor and the mixed liquid collection tank is controlled to be 80-150℃.

6. A cleaning apparatus used in the cleaning method as described in any one of claims 1-5, characterized in that, It includes a cleaning agent storage tank; an ethylene oligomerization reactor connected to the cleaning agent storage tank; a solvent storage tank and a mixture collection tank connected to the ethylene oligomerization reactor; a separation device connected to the mixture collection tank; a filtrate recovery tank and a filter residue collection tank connected to the separation device; and the filtrate recovery tank is connected to the ethylene oligomerization reactor.

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