A catalyst precontacting unit for the polymerization of olefins

Abstract

This invention discloses a catalyst pre-contact unit for olefin polymerization production, comprising a feed cooler, a first online mixer, a second online mixer, a catalyst pre-contact tank, and a flushing oil pressure-stabilizing storage tank. The outlet of the feed cooler is connected to the inlet of the first online mixer via propylene feed line one and propylene feed line two, and the outlet of the feed cooler is connected to the inlet of the second online mixer via propylene feed line three and propylene feed line four. The catalyst pre-contact tank is connected to the first online mixer via discharge line one, and to the second online mixer via discharge line two. Discharge line ball valves are installed at both ends of discharge lines one and two. The catalyst pre-contact unit provided by this invention can effectively avoid problems such as blockage of the online mixer and flushing oil lines caused by raw material backflow, and can also shorten the maintenance time of the catalyst pre-contact tank and reduce the safety risks during maintenance.

Description

Technical Field

[0001] This invention belongs to the field of polypropylene preparation technology, specifically relating to a catalyst pre-contact unit for olefin polymerization production. Background Technology

[0002] The polypropylene production utilizes Sinopec's second-generation polypropylene process technology, which employs a dual-loop system and a gas-phase reactor. The catalyst pre-contact unit comprises a catalyst system, a propylene feedstock system, and a flushing oil system. The main catalyst, triethylaluminum, and electron donor are fed into the catalyst pre-contact tank via their respective metering pumps. After being thoroughly mixed by the tank's agitator, the mixture overflows through the top overflow port and enters the online catalyst mixer. The propylene feedstock, after being cryogenically cooled by a heat exchanger, enters the online mixer via the feed line. The catalyst mixes with the cryogenic propylene in the online mixer before entering the prepolymer reactor. A flushing oil system is installed on the inlet and outlet pipelines of the catalyst pre-contact tank. When the pipeline pressure in the online mixer fluctuates, the flushing oil can be used to flush the pipeline, removing blockages. If the online mixer or pipeline becomes clogged, the flushing oil can be used to clean and replace the blockage, ensuring a safe cleaning process.

[0003] The current structure has several drawbacks. If the propylene feed line becomes clogged, it cannot be cleaned online, rendering the clogged line in the online mixer unusable and severely hindering stable production. The existing flushing oil system suffers from excessively long pipelines, making it impossible to determine the actual pressure of the flushing oil before flushing. This easily leads to material backflow in the online mixer during flushing, causing blockages in the online mixer and its flushing oil pipelines. Furthermore, the blockage prevents the use of flushing oil to clean and replace the online mixer and its pipelines, creating significant safety hazards for subsequent maintenance and cleaning. Finally, the current structure uses a welded connection between the catalyst outlet pipeline and the overflow pipeline of the catalyst pre-contact tank. This makes rapid cleaning and maintenance impossible if the catalyst outlet and the overflow pipeline before the ball valve of the catalyst pre-contact tank become clogged with impurities or if the pre-contact tank agitator malfunctions. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a catalyst pre-contact unit for olefin polymerization production, which can effectively avoid the problems of online mixer blockage and flushing oil pipeline blockage caused by raw material backflow. At the same time, it can also shorten the maintenance time for catalyst pre-contact tank and online mixer pipeline blockage or pre-contact tank agitator failure, and reduce the safety risks during maintenance.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A catalyst pre-contact unit for olefin polymerization production includes a feed cooler, a first online mixer, a second online mixer, a catalyst pre-contact tank, and a flushing oil pressure stabilizing storage tank, wherein:

[0007] The outlet of the feed cooler is connected to the inlet of the first online mixer via propylene feed line 1 and propylene feed line 2; the outlet of the feed cooler is connected to the inlet of the second online mixer via propylene feed line 3 and propylene feed line 4; that is, both the first online mixer and the second online mixer are equipped with two propylene feed lines, so that when one propylene feed line is blocked in actual production, online switching can be performed quickly;

[0008] The catalyst pre-contact tank is connected to the first online mixer via discharge pipeline one; the catalyst pre-contact tank is connected to the second online mixer via discharge pipeline two; discharge line ball valves are installed at both ends of discharge pipeline one and discharge pipeline two; there are two discharge line ball valves, i.e., a double ball valve setup.

[0009] The flushing oil pressure-stabilizing storage tank is connected to the first online mixer via flushing oil pipeline one, and a side flushing oil line one is also connected between the flushing oil pressure-stabilizing storage tank and the first online mixer; the flushing oil pressure-stabilizing storage tank is connected to the second online mixer via flushing oil pipeline two, and a side flushing oil line two is also connected between the flushing oil pressure-stabilizing storage tank and the second online mixer. Furthermore, flushing oil pipeline one and flushing oil pipeline two are each equipped with a flushing oil line ball valve; there are two flushing oil line ball valves in total.

[0010] In a further embodiment, a pre-contact tank agitator is installed in the catalyst pre-contact tank. The catalyst delivered to the catalyst pre-contact tank is stirred and mixed evenly by the pre-contact tank agitator, and then flows out through the top overflow pipeline of the catalyst pre-contact tank and enters the first online mixer and the second online mixer.

[0011] A further proposed solution involves a catalyst pre-contact tank comprising a cover plate, on which a top overflow pipeline and a catalyst outlet pipeline are installed. These two pipelines are connected by snap-fit ​​connections. Compared to existing welding methods, this design allows for rapid disassembly of the top overflow pipeline and catalyst outlet pipeline when they are blocked by impurities or when the pre-contact tank agitator malfunctions, significantly reducing the time required to handle both the catalyst pre-contact tank and its agitator. It also eliminates the risk of bending, flattening, or even breaking of the catalyst outlet pipeline during disassembly.

[0012] A further solution is to install a pressure gauge in the flushing oil pressure stabilizing tank, which can monitor the flushing oil pressure in real time.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0014] (1) Both the first and second online mixers employ two propylene feed lines. If one of the propylene feed lines becomes blocked, online switching can be performed quickly, reducing the switching operations between online mixers and the risk of pipeline blockage during switching, thus greatly improving the operational stability of the online mixers. This also solves the problem of the inability to clean the propylene feed line online under existing technology. Even if the propylene feed line becomes blocked, the corresponding online mixer can remain operational, solving the bottleneck problem that restricts stable production of the equipment.

[0015] (2) In this invention, the discharge pipeline and flushing oil pipeline of the catalyst pre-contact tank are both equipped with double ball valves. Once the corresponding pipeline is blocked, the blocked pipeline can be directly isolated and removed. This solves the problem that the discharge pipeline of the catalyst pre-contact tank to the online mixer cannot be oil-washed under the prior art, greatly reducing the risk of cleaning the pipeline. At the same time, by directly replacing the blocked pipeline, the troubleshooting time is shortened.

[0016] (3) This invention, by setting up a pressure-stabilizing storage tank for flushing oil and installing a pressure gauge, allows for real-time monitoring of the flushing oil pressure. This ensures that during the top-oil operation of the online mixer, material backflow due to low oil pressure will not cause blockage of the flushing oil pipeline. This solves the problems of excessively long flushing oil pipelines, pressure drop issues, inability to determine the actual pressure of the flushing oil before flushing, and the high risk of material backflow during flushing, leading to blockage of the online mixer and flushing oil pipeline. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the catalyst pre-contact unit for olefin polymerization production provided by the present invention;

[0018] Figure 2 This is a schematic diagram of the catalyst pre-contact tank cover plate.

[0019] Reference numerals: 1-Feed cooler, 2-First online mixer, 3-Second online mixer, 4-Catalyst pre-contact tank, 401-Catalyst pre-contact tank cover, 402-Top overflow line, 403-Catalyst outlet line, 404-Snap fastener, 5-Flush oil pressure stabilizing tank, 6-Pre-contact tank agitator, 7-Pressure gauge, 8-Propylene feed line one, 9-Propylene feed line two, 10-Propylene feed line three, 11-Propylene feed line four, 12-Discharge line one, 13-Discharge line two, 14-Discharge line ball valve, 15-Flush oil line one, 16-Side flush oil line one, 17-Flush oil line two, 18-Side flush oil line two, 19-Flush oil line ball valve. Detailed Implementation

[0020] The present invention will be further described below with reference to the embodiments and accompanying drawings, so that those skilled in the art can better understand and implement the present invention, but the embodiments are not intended to limit the present invention.

[0021] In the description of this invention, it should be understood that the terms "upper," "lower," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for 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 of this invention. The terms "first" and "second" used in this invention do not represent a specific quantity or order, but are merely used for distinguishing names.

[0022] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0023] refer to Figure 1 A catalyst pre-contact unit for olefin polymerization production includes a feed cooler 1, a first online mixer 2, a second online mixer 3, a catalyst pre-contact tank 4, and a flushing oil pressure stabilizing tank 5. The catalyst pre-contact tank 4 is equipped with a pre-contact tank agitator 6, and the flushing oil pressure stabilizing tank 5 is equipped with a pressure gauge 7.

[0024] The outlet of the feed cooler 1 is connected to the inlet of the first online mixer 2 through propylene feed line 1 8 and propylene feed line 2 9. The outlet of the feed cooler 1 is connected to the inlet of the second online mixer 3 through propylene feed line 3 10 and propylene feed line 4 11.

[0025] The catalyst pre-contact tank 4 is connected to the first online mixer 2 via discharge pipeline 12; the catalyst pre-contact tank 4 is connected to the second online mixer 3 via discharge pipeline 2 13; both ends of the discharge pipeline 12 and discharge pipeline 2 13 are equipped with discharge line ball valves 14; preferably, there are two discharge line ball valves 14. In a preferred embodiment, the catalyst pre-contact tank 4 includes a catalyst pre-contact tank cover plate 401, on which a top overflow pipeline 402 and a catalyst outlet pipeline 403 are installed. The top overflow pipeline 402 and the catalyst outlet pipeline 403 are connected by a snap-fit ​​404. A schematic diagram of the connection structure is shown below. Figure 2 The snap-fit ​​connection method solves the problem of disassembly that was impossible under the original welding method, greatly shortening the troubleshooting time.

[0026] The flushing oil pressure stabilizing tank 5 is connected to the first online mixer 2 via flushing oil pipeline 15. A side flushing oil line 16 also connects the flushing oil pressure stabilizing tank 5 and the first online mixer 2. The flushing oil pressure stabilizing tank 5 is connected to the second online mixer 3 via flushing oil pipeline 17. A side flushing oil line 18 also connects the flushing oil pressure stabilizing tank 5 and the second online mixer 3. Furthermore, flushing oil pipelines 15 and 17 are each equipped with a flushing oil line ball valve 19; there are two flushing oil line ball valves 19 in total.

[0027] The catalyst pre-contact unit for olefin polymerization production provided by this invention is carried out through the following process:

[0028] The main catalyst, co-catalyst triethylaluminum, and electron donor are fed into the catalyst pre-contact tank 4 by their respective metering pumps. The catalyst is cooled by chilled water in the jacket of the catalyst pre-contact tank 4 to maintain its temperature at around 10°C. The catalyst is stirred and mixed evenly by the agitator 6 in the pre-contact tank. After flowing out through the overflow port at the top of the catalyst pre-contact tank 4, it enters the first online mixer 2 of the catalyst through the discharge line 12 and the corresponding discharge line ball valve 14, or it enters the second online mixer 3 of the catalyst through the discharge line 13 and the corresponding discharge line ball valve 14.

[0029] After the raw material propylene is cooled to about 10°C by the feed cooler, it enters the first online mixer 2 through propylene feed line 18 or propylene feed line 29, or enters the second online mixer 3 through propylene feed line 310 or propylene feed line 411. The catalyst is mixed with the low-temperature propylene in the first online mixer 2 or the second online mixer 3 and then enters the prepolymerization reactor.

[0030] The high-pressure flushing oil, after being boosted by the hydraulic oil pump, enters the flushing oil pressure stabilizing storage tank 5. The pressure-stabilized flushing oil is used to control the oil washing of the feed line of the first online mixer 2 through flushing oil line 15 and side flushing oil line 16. It can also be used to control the oil washing of the feed line of the second online mixer 3 through flushing oil line 17 and side flushing oil line 18.

[0031] The catalyst pre-contact unit for olefin polymerization production provided by this invention can effectively avoid the problems of online mixer blockage and flushing oil pipeline blockage caused by raw material backflow. At the same time, it can also shorten the maintenance time of catalyst pre-contact tank 4 and online mixer pipeline blockage or pre-contact tank agitator 6 failure, and reduce the safety risks during maintenance.

[0032] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A catalyst pre-contact unit for olefin polymerization production, characterized in that: Includes a feed cooler, a first online mixer, a second online mixer, a catalyst pre-contact tank, and a flushing oil pressure stabilizing storage tank, wherein: The outlet of the feed cooler is connected to the inlet of the first online mixer via propylene feed line one and propylene feed line two, and the outlet of the feed cooler is connected to the inlet of the second online mixer via propylene feed line three and propylene feed line four. The catalyst pre-contact tank is connected to the first online mixer via discharge pipeline one; the catalyst pre-contact tank is connected to the second online mixer via discharge pipeline two; discharge line ball valves are installed at both ends of discharge pipeline one and discharge pipeline two. The flushing oil pressure stabilizing tank is connected to the first online mixer via flushing oil pipeline one; the flushing oil pressure stabilizing tank is connected to the second online mixer via flushing oil pipeline two.

2. The catalyst pre-contact unit for olefin polymerization production according to claim 1, characterized in that: A side flushing oil line is also connected between the flushing oil pressure stabilizing tank and the first online mixer; a second side flushing oil line is also connected between the flushing oil pressure stabilizing tank and the second online mixer.

3. The catalyst pre-contact unit for olefin polymerization production according to claim 2, characterized in that: Both flushing oil pipeline one and flushing oil pipeline two are equipped with flushing oil line ball valves; there are two flushing oil line ball valves in total.

4. The catalyst pre-contact unit for olefin polymerization production according to any one of claims 1 to 3, characterized in that: The catalyst pre-contact tank is equipped with a pre-contact tank agitator.

5. The catalyst pre-contact unit for olefin polymerization production according to any one of claims 1 to 3, characterized in that: The flushing oil pressure stabilizing storage tank is equipped with a pressure gauge.

6. The catalyst pre-contact unit for olefin polymerization production according to any one of claims 1 to 3, characterized in that: The number of ball valves on the discharge line is two.

7. The catalyst pre-contact unit for olefin polymerization production according to any one of claims 1 to 3, characterized in that: The catalyst pre-contact tank includes a catalyst pre-contact tank cover plate, on which a top overflow pipeline and a catalyst outlet pipeline are installed. The top overflow pipeline and the catalyst outlet pipeline are connected by a snap-fit.

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