Catalyst feeding system for polyolefin device reactor

Abstract

The utility model relates to a catalyst feeding system for a polyolefin device reactor. The catalyst feeding system comprises a reactor; a triethyl aluminum conveying pipeline; the feeding connecting pipe is connected to the catalyst injection port, the ethylene back flushing pipeline is connected with the feeding connecting pipe, and the connecting position of the ethylene back flushing pipeline and the feeding connecting pipe is located on the upstream of the connecting position of the triethyl aluminum conveying pipeline and the feeding connecting pipe. Ethylene gas conveyed by the ethylene back-blowing pipeline brings triethyl aluminum conveyed into the feeding connecting pipe from the triethyl aluminum conveying pipeline into the reactor, the section, used for being connected with the feeding connecting pipe, of the ethylene back-blowing pipeline is marked as a first pipeline section, and the section, used for being connected with the ethylene back-blowing pipeline, of the feeding connecting pipe is marked as a second pipeline section. The included angle between the material conveying direction in the first pipeline section and the material conveying direction in the second pipeline section is an acute angle. The device has the advantages that dead zones in the pipeline can be effectively eliminated, the pressure feed effect of the triethyl aluminum is enhanced, and then the potential safety hazard problem caused by pipeline blockage is solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to polyolefin device technical field especially relates to a polyolefin device reactor catalyst feeding system. BACKGROUND

[0002] Linear low density polyethylene device is with titanium as active center M type catalyst and with chromium as active center S, F type catalyst, and with ethylene as main raw material, 1-butene (1-hexene) as copolymer monomer, hydrogen as molecular weight regulator, through gas phase fluidized bed reactor reaction, with polyethylene resin as final product's chemical production device. Among them, the polymerization reactor is as the core area of whole device, catalyst system (including slurry mother liquor, monochlorodicaluminum diethyl, tri-n-hexylaluminum, triethylaluminum), especially critical, especially triethylaluminum needs to control its addition accurately, because the activity and the use amount of catalyst directly influence reaction rate and product quality.

[0003] Triethylaluminum needs to be carried into the reactor by ethylene gas before being injected into the reactor, and ethylene and triethylaluminum are in contact for a long time in the pipeline dead zone, which can easily react to form polymers, block the pipeline, and even cause the reactor to stop, especially, because triethylaluminum is self-igniting in air and explosive in water, the process is extremely dangerous and has great safety risks.

[0004] Therefore, the existing polyolefin device reactor catalyst feeding system needs to be further improved. UTILITY MODEL CONTENT

[0005] The utility model solves the technical problem of the prior art, and provides a polyolefin device reactor catalyst feeding system that can effectively eliminate the dead zone in the pipeline, enhance the pressure sending effect of triethylaluminum, and improve the safety hazard problem caused by pipeline blockage.

[0006] The utility model solves the above technical problems by adopting the following technical scheme: a polyolefin device reactor catalyst feeding system, comprising:

[0007] A reactor has a catalyst injection port.

[0008] A triethylaluminum delivery pipeline is used to deliver triethylaluminum to the reactor.

[0009] The application also discloses a feed connecting pipe connected to the catalyst injection inlet and an ethylene backflushing pipe connected to the feed connecting pipe, the triethylaluminum feeding pipe is connected to the feed connecting pipe and the connection position is adjacent to the catalyst injection inlet, the connection position of the ethylene backflushing pipe to the feed connecting pipe is upstream of the connection position of the triethylaluminum feeding pipe to the feed connecting pipe, ethylene gas transported through the ethylene backflushing pipe carries triethylaluminum transported from the triethylaluminum feeding pipe to the feed connecting pipe into the reactor, a section of the ethylene backflushing pipe connected to the feed connecting pipe is defined as a first pipe section, a section of the feed connecting pipe connected to the ethylene backflushing pipe is defined as a second pipe section, and the included angle between the material transport directions of the first pipe section and the second pipe section is an acute angle.

[0010] As an improvement, the included angle between the material transport directions of the first pipe section and the second pipe section is defined as A, and the value range is 0°

[0011] In order to further eliminate the flow dead angle at the connection position of the pipes, the first pipe section and the second pipe section are connected through a socket welding mode.

[0012] In order to realize smooth transportation of triethylaluminum material, a section of the triethylaluminum feeding pipe connected to the feed connecting pipe vertically extends.

[0013] Generally, the ethylene backflushing pipe is connected to the feed connecting pipe through a gradually curved transition mode, the ethylene backflushing pipe comprises a vertical main pipe and a transition pipe connected to the main pipe and inclined to one side of the main pipe, the lower end of the transition pipe is connected to the feed connecting pipe, and the transition pipe is the first pipe section.

[0014] As an improvement, the included angle between the main pipe and the main pipe is an obtuse angle.

[0015] In order to realize automatic adjustment of the adjusting valve of the ethylene backflushing pipe according to actual working conditions and effectively solve the blockage problem of the catalyst injection inlet of the reactor in time, a diaphragm pump for pumping triethylaluminum material and a first monitoring device for detecting the outlet pressure of the diaphragm pump are arranged on the triethylaluminum feeding pipe, an adjusting valve for adjusting the ethylene flow is arranged on the ethylene backflushing pipe, the first monitoring device and the adjusting valve are in linkage control, so that the opening degree of the adjusting valve is increased when the outlet pressure of the diaphragm pump is increased. Under the condition that the reactor pressure and the triethylaluminum flow are constant, when the pump outlet pressure of the diaphragm pump is increased, the backflushing ethylene pressure or the backflushing ethylene flow can be increased to prevent the blockage of the injection inlet.

[0016] As an improvement, the first monitoring device is a pressure transmitter.

[0017] Compared with the prior art, the utility model discloses the following advantages: the first pipeline section of ethylene back flushing pipeline and the second pipeline section of feed connection pipe adopt the structure design of acute angle, can make the flow velocity of ethylene gas increase in the pipeline, eliminate the dead zone in the pipeline, prevent triethylaluminum and ethylene polymerization reaction, and then effectively enhance the pressure sending effect of triethylaluminum, eliminate the security hidden danger problem of pipeline blockage. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the polyolefin device reactor catalyst feed system of the utility model embodiment. DETAILED DESCRIPTION

[0019] The utility model will be described further in detail below in combination with the embodiment of the accompanying drawings.

[0020] In the specification and claims of the utility model, the terms expressing direction, such as "front", "back", "upper", "lower", "left", "right", "side", "top", "bottom" and the like, are used to describe various example structural parts and elements of the utility model, but these terms are only used for the purpose of convenient description, and are determined based on the example orientation shown in the drawings. Since the disclosed embodiments of the utility model can be arranged in different directions, these terms expressing direction are only as description and should not be regarded as limitation, for example, "upper", "lower" are not necessarily limited to the direction opposite or consistent with the direction of gravity.

[0021] Figure 1 A preferred embodiment of the polyolefin device reactor catalyst feed system of the utility model is shown. A polyolefin device reactor catalyst feed system includes a reactor 1, a feed connection pipe 11, a triethylaluminum delivery pipeline 2 and an ethylene back flushing pipe.

[0022] The side of the reactor 1 is provided with a catalyst injection port 10, and the catalyst injection port 10 has an outwardly extending feed connection pipe 11, which is generally horizontally extended and is provided with a corresponding control valve.

[0023] The triethylaluminum feed line 2 originates from the triethylaluminum storage device and connects to the feed inlet 11 on the reactor 1. The connection point between the triethylaluminum feed line 2 and the feed inlet 11 is located near the catalyst injection port 10. Specifically, the triethylaluminum feed line 2 is equipped with a diaphragm pump 21 for transporting triethylaluminum, and a first monitoring device 22 for detecting the outlet pressure of the diaphragm pump 21 is also provided. The triethylaluminum feed line 2 is generally vertically extended, with its lower end connected to the feed inlet 11. The triethylaluminum feed line 2 and the feed inlet 11 are connected by socket welding to eliminate flow dead zones at the pipeline connection point.

[0024] The ethylene backflush line 3 is connected to the feed pipe 11. The connection between the ethylene backflush line 3 and the feed pipe 11 is located upstream of the connection between the triethylaluminum feed line 2 and the feed pipe 11. The ethylene gas transported through the ethylene backflush line 3 can carry the triethylaluminum transported from the triethylaluminum feed line 2 to the feed pipe 11 into the reactor 1.

[0025] The ethylene backflush pipeline 3 should preferably be connected to the feed inlet pipe 11 in a gradually curved transition manner. In this embodiment, the ethylene backflush pipeline 3 includes a vertically extending main pipeline 30 and a transition pipeline connected to the main pipeline 30 and inclined to one side relative to the main pipeline 30. The lower end of the transition pipeline is connected to the feed inlet pipe 11. Similarly, the transition pipeline and the second pipeline segment 111 are also connected by socket welding. More specifically, the section of pipeline on the ethylene backflush pipeline 3 used to connect to the feed inlet pipe 11 is referred to as the first pipeline segment 31 (i.e., the aforementioned transition pipeline), and the section of pipeline on the feed inlet pipe 11 used to connect to the ethylene backflush pipeline 3 is referred to as the second pipeline segment 111.

[0026] The angle between the main line 30 and the main line 30 is an obtuse angle (i.e., Figure 1 The angle between the material conveying direction in the first pipeline segment 31 and the material conveying direction in the second pipeline segment 111 is an acute angle, specifically denoted as A, with a value range of 0° < A ≤ 45°. In this embodiment, the first pipeline segment 31 of the ethylene backflushing pipeline 3 and the second pipeline segment 111 of the feed inlet 11 are designed with an acute angle. This increases the flow velocity of ethylene gas within the pipeline, eliminates dead zones, prevents the polymerization reaction between triethylaluminum and ethylene, effectively enhances the pressure conveying effect of triethylaluminum, and eliminates the safety hazards caused by pipeline blockage.

[0027] Through the analysis of the production operation data, it is found that the triethyl aluminum injection state of reactor 1 is related to the parameters such as the pressure of reactor 1, the ethylene backflushing pressure, the ethylene backflushing flow, the triethyl aluminum pump outlet pressure, the triethyl aluminum pump outlet flow, etc., and the specific conditions are as follows: 1. When the pressure of reactor 1 is controlled stably, the ethylene backflushing pressure is inversely proportional to the triethyl aluminum pump outlet pressure, that is, when the ethylene backflushing pressure is increased, the triethyl aluminum pump outlet pressure is correspondingly reduced. 2. Since the diaphragm pump 21 is a positive displacement pump, its theoretical flow is fixed when the stroke is unchanged. However, in actual operation, when the triethyl aluminum pump outlet pressure is increased, the resistance of the fluid flowing in the pipeline is increased, which leads to the intensification of the liquid backflow and other situations, so that the actual flow of the triethyl aluminum pump outlet is reduced; on the contrary, when the triethyl aluminum pump outlet pressure is reduced, the flow resistance is reduced, and the actual triethyl aluminum pump outlet flow is increased, and the two are inversely proportional. 3. Under the condition that the working condition is unchanged, the triethyl aluminum pump outlet flow is proportional to the slurry activity of the catalyst, therefore, under the condition that the pressure of reactor 1 and the triethyl aluminum flow are constant, when the pump outlet pressure of the diaphragm pump 21 is increased, in order to prevent the blockage of the injection port 10, the backflushing ethylene pressure or the backflushing ethylene flow can be increased. Specifically, the ethylene backflushing pipeline 3 is provided with an adjusting valve 300 for adjusting the ethylene flow, in order to realize the automatic adjustment of the adjusting valve 300 of the ethylene backflushing pipeline 3 according to the actual working condition, and effectively solve the blockage problem of the catalyst injection port 10 of reactor 1 in time, the first monitoring device 22 and the adjusting valve 300 are linked for control, so that when the outlet pressure of the diaphragm pump 21 is increased, the opening degree of the adjusting valve 300 is increased. More specifically, the maximum flow of the adjusting valve 300 of the embodiment is changed from the original design of 600 kg / h to 1000 kg / h, because the valve opening degree of the adjusting valve 300 exceeds 80% when the original device is in normal production, and the upward adjustment margin is insufficient, the utility model is reformed, and the valve opening degree of the adjusting valve 300 is kept at 40% after the reform, which has a large adjustment margin, so that the triethyl aluminum can be smoothly injected into the reactor 1, and the safe and stable operation of the device is ensured.

Claims

1. A polyolefin plant reactor catalyst feed system, comprising: a reactor (1) having a catalyst injection port (10); a triethylaluminum feed line (2) for feeding triethylaluminum into the reactor (1); characterized in that it further comprises a feed nozzle (11) connected to the catalyst injection port (10) and an ethylene backflush line (3) connected to the feed nozzle (11), the triethylaluminum feed line (2) is connected to the feed nozzle (11) at a location adjacent to the catalyst injection port (10), the ethylene backflush line (3) is connected to the feed nozzle (11) at a location upstream of the location where the triethylaluminum feed line (2) is connected to the feed nozzle (11), ethylene gas fed through the ethylene backflush line (3) brings triethylaluminum fed through the triethylaluminum feed line (2) into the feed nozzle (11) and into the reactor (1), a section of the ethylene backflush line (3) connected to the feed nozzle (11) is designated as a first line section (31), a section of the feed nozzle (11) connected to the ethylene backflush line (3) is designated as a second line section (111), and the included angle between the direction of material flow in the first line section (31) and the direction of material flow in the second line section (111) is an acute angle.

2. The polyolefin plant reactor catalyst feed system of claim 1, characterized by: The included angle between the direction of material flow in the first line section (31) and the direction of material flow in the second line section (111) is designated as A, and the value range is: 0° < A ≤ 45°.

3. The polyolefin plant reactor catalyst feed system of claim 1, wherein: The first line section (31) and the second line section (111) and the triethylaluminum feed line (2) and the feed nozzle (11) are connected by a socket welding method.

4. The polyolefin plant reactor catalyst feed system of claim 1, wherein: The section of the triethylaluminum feed line (2) connected to the feed nozzle (11) extends vertically.

5. The polyolefin plant reactor catalyst feed system of claim 1, wherein: The ethylene backflush line (3) comprises a main line (30) extending vertically and a transition line connected to the main line (30) and inclined to one side of the main line (30), the lower end of the transition line is connected to the feed nozzle (11), and the transition line is the first line section (31).

6. The polyolefin plant reactor catalyst feed system of claim 5, wherein: The included angle between the main line (30) and the main line (30) is an obtuse angle.

7. The polyolefin plant reactor catalyst feed system according to any one of claims 1 to 6, characterized by: The triethylaluminum feed line (2) is further provided with a diaphragm pump (21) for pumping triethylaluminum material and a first monitoring device (22) for detecting the outlet pressure of the diaphragm pump (21), the ethylene backflush line (3) is provided with an adjusting valve (300) for adjusting the flow rate of ethylene, and the first monitoring device (22) and the adjusting valve (300) are linked for linkage control, so that when the outlet pressure of the diaphragm pump (21) increases, the opening of the adjusting valve (300) is increased.

8. The polyolefin plant reactor catalyst feed system of claim 7, wherein: The first monitoring device (22) is a pressure transmitter.

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