Method for continuously converting hollow materials of the chromium type into polyethylene film stock of the chromium type

Abstract

The application discloses a method for continuously converting chromium-based middle hollow material into chromium-based film material polyethylene, and relates to the technical field of polymer composites.The method comprises the following steps: controlling the feeding amount of the chromium-based middle hollow material catalyst in a first catalyst operation tank to a first reactor according to the ethylene concentration; switching the catalyst operation tank corresponding to the first reactor from the first catalyst operation tank to a second catalyst operation tank according to the current ethylene concentration; respectively performing slight adjustment on the operation temperature of the first reactor and the second reactor according to the product melt index, and respectively performing slight adjustment on the feeding amount of 1-hexene in the first reactor and the second reactor according to the product density, so as to obtain target chromium-based middle hollow polyethylene products and target chromium-based film material polyethylene products.Through the arrangement, the method can effectively solve the problems of reactor wall skinning and device shutdown risk in the process of continuously converting the chromium-based middle hollow material into the chromium-based film material polyethylene.

Description

Technical Field

[0001] This application relates to the field of polymer composite materials technology, and in particular to a method for the continuous production of chromium-based hollow materials into chromium-based polyethylene film. Background Technology

[0002] Currently, in the continuous conversion of chromium-based hollow fiber materials to chromium-based membrane polyethylene, chromium-based hollow fiber materials require chromium-based hollow fiber catalysts, while chromium-based membrane catalysts require chromium-based membrane catalysts. However, chromium-based hollow fiber catalysts and chromium-based membrane catalysts are of different specifications, with different activation temperatures and activities. This leads to problems such as reactor wall scaling and plant shutdown risks during the continuous conversion of chromium-based hollow fiber materials to chromium-based membrane polyethylene. Summary of the Invention

[0003] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a method for the continuous conversion of chromium-based hollow materials to chromium-based film-forming polyethylene, which can effectively solve the problems of reactor wall scaling and plant shutdown risks during the continuous conversion of chromium-based hollow materials to chromium-based film-forming polyethylene.

[0004] This application provides a method for continuous conversion of chromium-based hollow materials to chromium-based film-grade polyethylene, comprising: controlling the ethylene concentration in a first reactor and a second reactor to maintain at 3.5 wt%, and controlling the feed rate of the chromium-based hollow material catalyst in a first catalyst operating tank to the first reactor according to the ethylene concentration; the first reactor stores chromium-based hollow materials, and the second reactor stores the target chromium-based hollow polyethylene product transported from the first reactor;

[0005] The loads of the first reactor and the second reactor are reduced from the initial preset load value to 19.0 t / h at a rate of 1.5 t / h.

[0006] The ethylene concentration in the first reactor is adjusted to 3.1 wt%. Based on the current ethylene concentration, the catalyst operating tank corresponding to the first reactor is switched from the first catalyst operating tank to the second catalyst operating tank storing chromium-based film catalyst.

[0007] When the chromium-based film catalyst in the first reactor is switched to the first preset catalyst operating time, the operating temperature of the first reactor and the second reactor is reduced to 97°C, and the feed rate of 1-hexene in the first reactor and the second reactor is adjusted to 16.0 kg / t PE.

[0008] The operating temperature of the first reactor and the second reactor is controlled to be reduced to 96°C, and the feed rate of 1-hexene in the first reactor and the second reactor is adjusted to 18.5 kg / t PE;

[0009] According to the preset analysis frequency, the samples in the first reactor and the second reactor are subjected to mass analysis to obtain the melt index and density of the product.

[0010] Based on the product melt index, the operating temperatures of the first reactor and the second reactor are slightly adjusted until the product melt index meets the first preset stop condition. Based on the product density, the feed amount of 1-hexene in the first reactor and the second reactor is slightly adjusted until the product density meets the second preset stop condition, thereby obtaining the target chromium-based hollow polyethylene product and the target chromium-based film polyethylene product.

[0011] According to some embodiments of this application, before performing mass analysis on the samples in the first reactor and the second reactor according to a preset analysis frequency to obtain the product melt index and product density, the method further includes:

[0012] The steam pressure in the flash line jacket is adjusted to maintain the temperature of the flash evaporator between 78°C and 82°C.

[0013] It was confirmed that the feed amount of antistatic agent delivered to the first reactor and the second reactor was in accordance with the preset feed amount value of antistatic agent;

[0014] Melt index analysis was performed on the chromium-based hollow material in the first reactor to confirm the melt index of the chromium-based hollow material.

[0015] If the melt index of the hollow material in the chromium system exceeds the preset product melt index range, a polyethylene additive is added to the first reactor.

[0016] According to some embodiments of this application, the step of performing mass analysis on samples in the first reactor and the second reactor according to a preset analysis frequency to obtain the product melt index and product density includes:

[0017] According to the preset analysis frequency, the quality analysis of the chromium-based hollow polyethylene product initially synthesized in the first reactor is carried out to obtain the melt index and density of the first product.

[0018] According to the preset analysis frequency, the target chromium-based hollow polyethylene product in the second reactor is subjected to quality analysis to obtain the second product melt index and the second product density. The product melt index includes the first product melt index and the second product melt index, and the product density includes the first product density and the second product density.

[0019] According to some embodiments of this application, the step of slightly adjusting the operating temperatures of the first reactor and the second reactor based on the product melt index until the product melt index meets a first preset stop condition, and slightly adjusting the feed amount of 1-hexene in the first reactor and the second reactor based on the product density until the product density meets a second preset stop condition, to obtain the target chromium-based hollow polyethylene product and the target chromium-based film polyethylene product, includes:

[0020] Based on the melt index of the first product, the operating temperature of the first reactor is slightly adjusted until the melt index of the first product meets the first preset stop condition. Based on the density of the first product, the feed amount of 1-hexene in the first reactor is slightly adjusted until the density of the first product meets the second preset stop condition, thereby obtaining the target chromium-based hollow polyethylene product.

[0021] According to some embodiments of this application, the step of slightly adjusting the operating temperatures of the first reactor and the second reactor based on the product melt index until the product melt index meets a first preset stop condition, and slightly adjusting the feed amount of 1-hexene in the first reactor and the second reactor based on the product density until the product density meets a second preset stop condition, thereby obtaining the target chromium-based hollow polyethylene product and the target chromium-based film polyethylene product, further includes:

[0022] Based on the melt index of the second product, the operating temperature of the second reactor is slightly adjusted until the melt index of the second product meets the first preset stop condition. Based on the density of the second product, the feed amount of 1-hexene in the second reactor is slightly adjusted until the density of the second product meets the second preset stop condition, thereby obtaining the target chromium-based film material polyethylene product.

[0023] According to some embodiments of this application, after the steps of slightly adjusting the operating temperatures of the first reactor and the second reactor according to the product melt index until the product melt index meets a first preset stop condition, and slightly adjusting the feed amount of 1-hexene in the first reactor and the second reactor according to the product density until the product density meets a second preset stop condition, and obtaining the target chromium-based hollow polyethylene product and the target chromium-based film polyethylene product, the process includes:

[0024] Adjust the loads of the first reactor and the second reactor to the initial preset load values.

[0025] According to some embodiments of this application, the initial preset load value is 40.0 t / h.

[0026] According to some embodiments of this application, the step of slightly adjusting the operating temperature of the first reactor based on the melt index of the first product until the melt index of the first product meets a first preset stop condition includes:

[0027] Based on the melt index of the first product, the operating temperature of the first reactor is slightly adjusted by the first reaction temperature controller, and the adjustment range of the operating temperature is less than or equal to 0.2℃ each time, until the melt index of the first product meets the first preset stop condition.

[0028] According to some embodiments of this application, the step of finely adjusting the operating temperature of the second reactor based on the melt index of the second product until the melt index of the second product meets the first preset stop condition includes:

[0029] Based on the melt index of the second product, the operating temperature of the second reactor is slightly adjusted by the second reaction temperature controller, with each adjustment being less than or equal to 0.2°C, until the melt index of the second product meets the first preset stop condition.

[0030] The beneficial effects of this application are reflected in the following: by controlling the ethylene concentration in the first and second reactors to maintain at 3.5 wt%, and controlling the feed rate of the chromium-based hollow catalyst from the first catalyst operating tank to the first reactor according to the ethylene concentration; the first reactor stores chromium-based hollow material, and the second reactor stores the target chromium-based hollow polyethylene product transported from the first reactor; the load of the first and second reactors is reduced from the initial preset load value to 19.0 t / h at a rate of 1.5 t / h; the ethylene concentration in the first reactor is adjusted to 3.1 wt%, and based on the current ethylene concentration, the catalyst operating tank corresponding to the first reactor is switched from the first catalyst operating tank to the second catalyst operating tank storing the chromium-based membrane catalyst; when the chromium-based membrane catalyst in the first reactor is switched to the first preset catalyst operating time, the operating temperature of the first and second reactors is reduced to 97°C, and the feed rate of 1-hexene in the first and second reactors is adjusted to 16.0 kg / t. The process involves controlling the operating temperature of the first and second reactors to decrease to 96°C, and adjusting the feed rate of 1-hexene in the first and second reactors to increase to 18.5 kg / t PE. Based on a preset analysis frequency, samples from the first and second reactors are subjected to mass analysis to obtain the melt index and density of the product. Based on the melt index, the operating temperature of the first and second reactors is slightly adjusted until the melt index meets the first preset stop condition. Based on the density, the feed rate of 1-hexene in the first and second reactors is slightly adjusted until the density meets the second preset stop condition, resulting in the target chromium-based hollow polyethylene product and the target chromium-based film polyethylene product. This application, through this setup, effectively solves the problems of reactor wall scaling and plant shutdown risks during the continuous conversion of chromium-based hollow materials to chromium-based film polyethylene.

[0031] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0032] Additional aspects and advantages of this application will become apparent and readily understood in conjunction with the following description of the embodiments, in which:

[0033] Figure 1 This is a schematic flowchart of a method for continuous production of chromium-based hollow materials into chromium-based film polyethylene, provided in an embodiment of this application.

[0034] Figure 2 This is a partial schematic of the process prior to sample quality analysis provided in the embodiments of this application;

[0035] Figure 3This is a schematic diagram illustrating the specific process for obtaining the melt index and density of a product according to an embodiment of this application;

[0036] Figure 4 This is a schematic diagram of the process for obtaining the target chromium-based hollow polyethylene product provided in the embodiments of this application;

[0037] Figure 5 This is a schematic diagram of the process for obtaining the target chromium-based film material polyethylene product provided in the embodiments of this application;

[0038] Figure 6 This is a schematic diagram of the process of adjusting the first reactor and the second reactor provided in an embodiment of this application;

[0039] Figure 7 This is a schematic diagram illustrating the specific process of adjusting the operating temperature based on the melt index of the first product, provided in an embodiment of this application.

[0040] Figure 8 This is a schematic diagram of the process for adjusting the operating temperature based on the melt index of the first product, provided in an embodiment of this application. Detailed Implementation

[0041] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0042] In the description of this application, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0043] In the description of this application, the use of "first" and "second" is for the purpose of distinguishing technical features only, and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or the order of the technical features indicated.

[0044] In the description of this application, unless otherwise expressly defined, terms such as "setup," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.

[0045] Currently, in the continuous conversion of chromium-based hollow fiber materials to chromium-based membrane polyethylene, chromium-based hollow fiber materials require chromium-based hollow fiber catalysts, while chromium-based membrane catalysts require chromium-based membrane catalysts. However, chromium-based hollow fiber catalysts and chromium-based membrane catalysts are of different specifications, with different activation temperatures and activities. This leads to problems such as reactor wall scaling and plant shutdown risks during the continuous conversion of chromium-based hollow fiber materials to chromium-based membrane polyethylene.

[0046] Based on this, the embodiments of this application provide a method for continuous conversion of chromium-based hollow materials to chromium-based film polyethylene, which can effectively solve the problems of reactor wall scaling and plant shutdown risk in the process of continuous conversion of chromium-based hollow materials to chromium-based film polyethylene.

[0047] The embodiments of this application will be further described below with reference to the accompanying drawings.

[0048] This application provides a specific method for the continuous production of chromium-based film polyethylene from chromium-based hollow materials, such as... Figure 1 As shown. The method for continuous production of chromium-based hollow polyethylene film material from chromium-based hollow materials includes, but is not limited to, the following steps:

[0049] In step S100, the ethylene concentration in the first reactor and the second reactor is controlled to be maintained at 3.5 wt%, and the feed rate of the chromium-based hollow catalyst in the first catalyst operating tank to the first reactor is controlled according to the ethylene concentration.

[0050] It should be noted that the first reactor contains chromium-based hollow materials, and the second reactor contains the target chromium-based hollow polyethylene product transported from the first reactor.

[0051] It should be noted that before step S100, the chromium-based hollow material is continuously converted to chromium-based film polyethylene product, and the load of the first reactor and the second reactor is reduced to 38t / h. The granulation operator pulls the chromium-based hollow material from the powder buffer silo into the first reactor according to the display of the powder buffer silo scale.

[0052] It should be noted that the first reactor is equipped with a first ethylene feed regulating valve, and the second reactor is equipped with a second ethylene feed regulating valve. By controlling the opening degree of the first ethylene feed regulating valve, the feed rate of ethylene in the first reactor can be regulated, thereby controlling the ethylene concentration in the first reactor; by controlling the opening degree of the second ethylene feed regulating valve, the feed rate of ethylene in the second reactor can be regulated, thereby controlling the ethylene concentration in the second reactor.

[0053] It should be noted that chromium-based hollow materials refer to medium-sized hollow products mainly used to make 5-160 liter buckets, stamped pallets, and sheets. The term "hollow" refers to the material application.

[0054] In step S200, the loads of the first reactor and the second reactor are reduced from the initial preset load value to 19.0 t / h at a rate of 1.5 t / h.

[0055] Specifically, the polymerization operator slowly reduces the feed rate of the chromium-based hollow catalyst in the first reactor according to the ethylene concentration to maintain the ethylene concentration at 3.5 wt%. At the same time, the loads of the first and second reactors are reduced from the initial preset load value to 38 t / h at a rate of 1.5 t / h. Finally, the load of the first reactor is reduced to 19.0 t / h, and the load of the second reactor is reduced to 19.0 t / h.

[0056] In step S300, the ethylene concentration in the first reactor is adjusted to 3.1 wt%. Based on the current ethylene concentration, the catalyst operating tank corresponding to the first reactor is switched from the first catalyst operating tank to the second catalyst operating tank storing chromium-based film catalyst.

[0057] It should be noted that the feed rate of the chromium-based hollow catalyst in the first reactor is adjusted by controlling the stroke controller of the first catalyst pump and the stroke controller of the second catalyst pump. The ethylene concentration in the first reactor is adjusted to 3.1 wt% by the first ethylene concentration controller. After the ethylene concentration reaches the target value of 3.1 wt%, the main operator starts to adjust the production control parameters.

[0058] In step S400, when the chromium-based film catalyst in the first reactor is switched to the first preset catalyst operating time, the operating temperature of the first reactor and the second reactor is reduced to 97°C, and the feed rate of 1-hexene in the first reactor and the second reactor is adjusted to 16.0 kg / t PE.

[0059] In some embodiments, the first preset catalyst running time is 45 minutes.

[0060] In step S500, the operating temperature of the first reactor and the second reactor is controlled to be reduced to 96°C, and the feed rate of 1-hexene in the first reactor and the second reactor is adjusted to 18.5 kg / t PE.

[0061] It should be noted that the first reactor is equipped with a first hexene feed control valve, and the second reactor is equipped with a second hexene feed control valve. Controlling the opening of the first hexene feed control valve does not control the amount of 1-hexene fed into the first reactor; similarly, controlling the opening of the second hexene feed control valve does not control the amount of 1-hexene fed into the second reactor.

[0062] Step S600: According to the preset analysis frequency, perform quality analysis on the samples in the first reactor and the second reactor respectively to obtain the melt index and density of the product.

[0063] Specifically, powder samples were taken from the first reactor and the second reactor for quality analysis. The analysis frequency was as follows: melt index once every 2 hours and density once every 4 hours for the first reactor; melt index once every 2 hours and density once every 4 hours for the second reactor; and melt index once every 2 hours and density once every 4 hours for the granular samples online. Here, "sample" refers to the current online granular sample from the first reactor and the second reactor.

[0064] In step S700, the operating temperatures of the first reactor and the second reactor are slightly adjusted according to the melt index of the product until the melt index of the product meets the first preset stop condition. According to the product density, the feed amount of 1-hexene in the first reactor and the second reactor is slightly adjusted until the product density meets the second preset stop condition, thereby obtaining the target chromium-based hollow polyethylene product and the target chromium-based film polyethylene product.

[0065] It should be noted that the first preset stopping condition is that the melt index of the granules in the first reactor and the granules in the second reactor corresponding to the online samples meet the qualification requirements; the second preset stopping condition is that the density of the granules in the first reactor and the granules in the second reactor corresponding to the online samples meet the qualification requirements.

[0066] It should be noted that the first reactor contains chromium-based hollow materials, and the second reactor contains the target chromium-based hollow polyethylene product transported from the first reactor.

[0067] It should be noted that before implementing the method of continuously converting chromium-based hollow materials to chromium-based membrane polyethylene, it is necessary to first confirm that a batch of chromium-based membrane catalyst has been prepared in the catalyst mixing tank at a concentration of 8 wt%, and that the chromium-based membrane catalyst injection system is operating normally. Then, it is confirmed that the liquid level of the prepared chromium-based membrane catalyst in the second catalyst operating tank is 70%, and finally, it is confirmed that the reactor unloading tank is in a usable state.

[0068] It should be noted that, in the first reactor, the chromium-based hollow material is processed by adjusting the proportions of each raw material and controlling the parameters to obtain the target chromium-based hollow polyethylene product. After the target chromium-based hollow polyethylene product is transported from the first reactor to the second reactor, it undergoes a series of adjustments to the proportions of each raw material and controlling the parameters in the second reactor to obtain the target chromium-based film polyethylene product. The final target chromium-based film polyethylene product is then transported to the reactor unloading tank for collection. After the target chromium-based hollow polyethylene product from the first reactor is transported to the second reactor, the first reactor continues to carry out a new cycle of chromium-based hollow material reaction, repeating the above process to achieve continuous conversion of chromium-based hollow material to chromium-based film polyethylene product.

[0069] It should be noted that during the execution of steps S100 to S700 of this application, the process is in the continuous conversion of chromium-based hollow materials to chromium-based film polyethylene products. That is, at this time, chromium-based hollow materials are added to the first reactor, and the chromium-based film polyethylene products that have been initially synthesized in the first reactor are transported from the first reactor to the second reactor. The control device adjusts the proportion of each raw material and control parameters of the first reactor and the second reactor in real time by controlling them simultaneously.

[0070] Reference Figure 2 It is understood that prior to step S600, the following steps are included, but are not limited to:

[0071] Step S610: Adjust the steam pressure of the flash line jacket to maintain the temperature of the flash evaporator between 78°C and 82°C.

[0072] Step S611: Confirm that the amount of antistatic agent fed into the first reactor and the second reactor meets the preset feed amount value of antistatic agent.

[0073] Step S612: Perform melt index analysis on the chromium-based hollow material in the first reactor to confirm the melt index of the corresponding chromium-based hollow material.

[0074] In step S613, if the melt index of the hollow material in the chromium system exceeds the preset melt index range, polyethylene additive is added to the first reactor.

[0075] It should be noted that before performing step S611, it is necessary to first confirm that the liquid level of the antistatic agent system is above 60% and that the concentration of the prepared antistatic agent solution is 5wt%.

[0076] It should be noted that the polyethylene additives in this application also refer to compound additives. After the melt index of the chromium-based hollow material in the first reactor exceeds the preset product melt index range, compound additives are added at a ratio of 2.5 kg / t PE. The compound additives may include antioxidants, preservatives, etc.

[0077] In this embodiment, the preset feed amount of the antistatic agent is 3 ppm.

[0078] It should be noted that before step S610, the catalyst feed rate in the first reactor needs to be adjusted according to the change in ethylene concentration to maintain the ethylene concentration in the first reactor at 3.1 wt%.

[0079] Reference Figure 3 It is understood that step S600 includes, but is not limited to, the following steps:

[0080] Step S620: According to the preset analysis frequency, perform quality analysis on the chromium-based hollow polyethylene product initially synthesized in the first reactor to obtain the melt index and density of the first product.

[0081] Step S621: Based on the preset analysis frequency, perform quality analysis on the target chromium-based hollow polyethylene product in the second reactor to obtain the melt index and density of the second product.

[0082] It should be noted that the product melt index includes the first product melt index and the second product melt index, and the product density includes the first product density and the second product density. The current pellet sample in the first reactor is the initially synthesized chromium-based hollow polyethylene product, and the current pellet sample in the second reactor is the initial target chromium-based hollow polyethylene product.

[0083] It should be noted that melt flow index, also known as melt flow rate, is a measure of the weight of thermoplastic resin melt passing through a standard mold every 10 minutes under certain load and temperature on a melt flow meter, expressed in g / 10min.

[0084] Reference Figure 4 It is understood that step S700 includes, but is not limited to, the following steps:

[0085] Step S710: Based on the melt index of the first product, the operating temperature of the first reactor is slightly adjusted until the melt index of the first product meets the first preset stop condition. Based on the density of the first product, the feed amount of 1-hexene in the first reactor is slightly adjusted until the density of the first product meets the second preset stop condition, thereby obtaining the target chromium-based hollow polyethylene product.

[0086] Reference Figure 5It is understood that step S700 also includes, but is not limited to, the following steps:

[0087] In step S720, the operating temperature of the second reactor is slightly adjusted according to the melt index of the second product until the melt index of the second product meets the first preset stop condition. The feed amount of 1-hexene in the second reactor is slightly adjusted according to the density of the second product until the density of the second product meets the second preset stop condition, thereby obtaining the target chromium-based film material polyethylene product.

[0088] Reference Figure 6 It is understood that after step S700, the following steps may occur, including but not limited to:

[0089] Step S800: Adjust the loads of the first reactor and the second reactor to the initial preset load values.

[0090] In one possible implementation, the initial preset load value is 40.0 t / h.

[0091] It should be noted that the load on the first reactor is adjusted by controlling the opening of the first ethylene feed regulating valve; and the load on the second reactor is adjusted by controlling the opening of the second ethylene feed regulating valve.

[0092] Reference Figure 7 It is understandable that step S710 involves making minor adjustments to the operating temperature of the first reactor based on the melt index of the first product until the melt index of the first product meets the first preset stop condition, including but not limited to the following steps:

[0093] Step S711: Based on the melt index of the first product, the operating temperature of the first reactor is slightly adjusted by the first reaction temperature controller, and the adjustment range of the operating temperature is less than or equal to 0.2℃ each time, until the melt index of the first product meets the first preset stop condition.

[0094] Reference Figure 8 It is understandable that step S720 involves making minor adjustments to the operating temperature of the second reactor based on the melt index of the second product until the melt index of the second product meets the first preset stop condition, including but not limited to the following steps:

[0095] Step S721: Based on the melt index of the second product, the operating temperature of the second reactor is slightly adjusted by the second reaction temperature controller, and the adjustment range of the operating temperature is less than or equal to 0.2℃ each time, until the melt index of the second product meets the first preset stop condition.

[0096] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0097] The above description is the preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications are also considered to be within the scope of protection of this application.

[0098] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for continuous production of chromium-based hollow polyethylene film material from chromium-based hollow materials, characterized in that, include: The ethylene concentration in the first reactor and the second reactor is maintained at 3.5 wt%, and the feed rate of the chromium-based hollow material catalyst in the first catalyst operating tank to the first reactor is controlled according to the ethylene concentration; the first reactor stores chromium-based hollow material, and the second reactor stores the target chromium-based hollow polyethylene product transported from the first reactor; The loads of the first reactor and the second reactor are reduced from the initial preset load value to 19.0 t / h at a rate of 1.5 t / h. The ethylene concentration in the first reactor is adjusted to 3.1 wt%. Based on the current ethylene concentration, the catalyst operating tank corresponding to the first reactor is switched from the first catalyst operating tank to the second catalyst operating tank storing chromium-based film catalyst. When the chromium-based film catalyst in the first reactor is switched to the first preset catalyst operating time, the operating temperature of the first reactor and the second reactor is reduced to 97°C, and the feed rate of 1-hexene in the first reactor and the second reactor is adjusted to 16.0 kg / t PE. The operating temperature of the first reactor and the second reactor is controlled to be reduced to 96°C, and the feed rate of 1-hexene in the first reactor and the second reactor is adjusted to 18.5 kg / t PE; The steam pressure in the flash line jacket is adjusted to maintain the temperature of the flash evaporator between 78°C and 82°C. It was confirmed that the feed amount of antistatic agent delivered to the first reactor and the second reactor was in accordance with the preset feed amount value of antistatic agent; Melt index analysis was performed on the chromium-based hollow material in the first reactor to confirm the melt index of the chromium-based hollow material. If the melt index of the hollow material in the chromium system exceeds the preset product melt index range, polyethylene additive is added to the first reactor. According to the preset analysis frequency, the samples in the first reactor and the second reactor are subjected to mass analysis to obtain the melt index and density of the product. Based on the product melt index, the operating temperatures of the first reactor and the second reactor are slightly adjusted until the product melt index meets the first preset stop condition. Based on the product density, the feed amount of 1-hexene in the first reactor and the second reactor is slightly adjusted until the product density meets the second preset stop condition, thereby obtaining the target chromium-based hollow polyethylene product and the target chromium-based film polyethylene product.

2. The method for continuous production of chromium-based hollow polyethylene film material from chromium-based hollow materials according to claim 1, characterized in that, The step of performing mass analysis on samples in the first reactor and the second reactor according to a preset analysis frequency to obtain the melt index and density of the product includes: According to the preset analysis frequency, the quality analysis of the chromium-based hollow polyethylene product initially synthesized in the first reactor is carried out to obtain the melt index and density of the first product. According to the preset analysis frequency, the target chromium-based hollow polyethylene product in the second reactor is subjected to quality analysis to obtain the second product melt index and the second product density. The product melt index includes the first product melt index and the second product melt index, and the product density includes the first product density and the second product density.

3. The method for continuous production of chromium-based hollow polyethylene film material from chromium-based hollow materials according to claim 2, characterized in that, The process involves finely adjusting the operating temperatures of the first and second reactors based on the product melt index until the product melt index meets a first preset stop condition; and finely adjusting the feed rate of 1-hexene in the first and second reactors based on the product density until the product density meets a second preset stop condition, thereby obtaining the target chromium-based hollow polyethylene product and the target chromium-based film polyethylene product, comprising: Based on the melt index of the first product, the operating temperature of the first reactor is slightly adjusted until the melt index of the first product meets the first preset stop condition. Based on the density of the first product, the feed amount of 1-hexene in the first reactor is slightly adjusted until the density of the first product meets the second preset stop condition, thereby obtaining the target chromium-based hollow polyethylene product.

4. The method for continuous production of chromium-based hollow polyethylene film material from chromium-based hollow materials according to claim 2, characterized in that, The step of finely adjusting the operating temperatures of the first reactor and the second reactor according to the product melt index until the product melt index meets a first preset stop condition, and finely adjusting the feed amount of 1-hexene in the first reactor and the second reactor according to the product density until the product density meets a second preset stop condition, thereby obtaining the target chromium-based hollow polyethylene product and the target chromium-based film polyethylene product, further includes: Based on the melt index of the second product, the operating temperature of the second reactor is slightly adjusted until the melt index of the second product meets the first preset stop condition. Based on the density of the second product, the feed amount of 1-hexene in the second reactor is slightly adjusted until the density of the second product meets the second preset stop condition, thereby obtaining the target chromium-based film material polyethylene product.

5. The method for continuous production of chromium-based hollow polyethylene film material from chromium-based hollow materials according to claim 4, characterized in that, After the steps of finely adjusting the operating temperatures of the first reactor and the second reactor according to the product melt index until the product melt index meets a first preset stop condition, and finely adjusting the feed amount of 1-hexene in the first reactor and the second reactor according to the product density until the product density meets a second preset stop condition, thus obtaining the target chromium-based hollow polyethylene product and the target chromium-based film polyethylene product, the process includes: Adjust the loads of the first reactor and the second reactor to the initial preset load values.

6. The method for continuous production of chromium-based hollow polyethylene film material from chromium-based hollow materials according to claim 5, characterized in that, The initial preset load value is 40.0 t / h.

7. The method for continuous production of chromium-based hollow polyethylene film material from chromium-based hollow materials according to claim 3, characterized in that, The step of finely adjusting the operating temperature of the first reactor based on the melt index of the first product until the melt index of the first product meets the first preset stop condition includes: Based on the melt index of the first product, the operating temperature of the first reactor is slightly adjusted by the first reaction temperature controller, and the adjustment range of the operating temperature is less than or equal to 0.2℃ each time, until the melt index of the first product meets the first preset stop condition.

8. The method for continuous production of chromium-based hollow polyethylene film material from chromium-based hollow materials according to claim 4, characterized in that, The step of finely adjusting the operating temperature of the second reactor according to the melt index of the second product until the melt index of the second product meets the first preset stop condition includes: Based on the melt index of the second product, the operating temperature of the second reactor is slightly adjusted by the second reaction temperature controller, with each adjustment being less than or equal to 0.2°C, until the melt index of the second product meets the first preset stop condition.

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