An online catalyst unloading system for acrylonitrile plant reactor

Abstract

The utility model provides an online catalyst unloading system for an acrylonitrile device reactor, comprising a reactor and a catalyst storage tank, wherein one side of the reactor is connected to a feed pipeline on the catalyst storage tank through a second catalyst delivery pipeline, the other side of the reactor is connected to a feed pipeline through a first catalyst delivery pipeline, one end of the first catalyst delivery pipeline is connected to the reactor through a first connecting pipe and a second connecting pipe, the system is newly added with an online catalyst unloading pipeline, the catalyst unloading can be realized when the reactor is running, the device is prevented from being stopped, and long-cycle operation is realized, and the online catalyst unloading pipeline can accurately control the catalyst unloading speed, the catalyst unloading speed is 1-3t / h, and the effect on the operation of the reactor is very small, the online catalyst unloading process adopts nitrogen as the delivery air and the storage tank loosening air to prevent the catalyst mixed gas from exploding, the online catalyst unloading process is provided with a heat exchange device, and the desalted water accompanying cooling pipeline is utilized to reduce the catalyst and the reaction gas temperature, and ensure the operation safety.

Description

Technical Field

[0001] The utility model relates to the technical field of acrylonitrile reaction, and more specifically to an online catalyst unloading system for an acrylonitrile device reactor. Background Art

[0002] Acrylonitrile is an important organic chemical raw material. Most industrial acrylonitrile plants use propylene ammoxidation to produce acrylonitrile. Figure 1 In the existing catalyst loading and unloading process shown, when the catalyst cyclonic pressure difference of the reactor approaches the design upper limit, a part of the catalyst needs to be unloaded to prevent the catalyst from running away and causing the reactor to shut down. The existing unloading pipeline can only be used for catalyst loading and unloading during the shutdown period. A single reactor is started up and filled with 220 tons of bulk catalyst. During operation, catalyst is added at 0.4 kg / t.AN to maintain activity. The catalyst storage in the reactor increases at a rate of 4 tons / month. According to experience, the catalyst storage reaches 250 tons, and the catalyst cyclonic pressure difference is close to the design upper limit. If the existing unloading pipeline is used, the device will have to be shut down and unloaded once every 7 months of continuous operation, which cannot achieve long-term operation and ensure economic benefits.

[0003] In view of this, the utility model provides an online catalyst unloading system for an acrylonitrile device reactor. Utility Model Content

[0004] The purpose of the utility model is to provide an online catalyst unloading system for an acrylonitrile device reactor in view of the defects of the prior art, so as to solve the problems raised by the above-mentioned background technology.

[0005] To achieve the above-mentioned purpose, the utility model provides the following technical solutions: an online catalyst unloading system for an acrylonitrile device reactor, comprising a reactor and a catalyst storage tank, one side of the reactor is connected to a feed pipeline on the catalyst storage tank through a second catalyst delivery pipeline, the other side of the reactor is connected to a feed pipeline through a first catalyst delivery pipeline, one end of the first catalyst delivery pipeline is connected to the reactor through a first connecting pipe and a second connecting pipe, a first blind plate is installed on the first connecting pipe, a second blind plate is installed on the second connecting pipe, and a heat exchanger is also installed in the middle of the first catalyst delivery pipeline;

[0006] One side of the bottom of the catalyst storage tank is connected to an air supply pipeline, one end of the air supply pipeline is connected to a nitrogen delivery device, and the air supply pipeline is connected to the other side of the bottom of the catalyst storage tank through a connecting pipeline.

[0007] As a further improvement of the technical solution, a pressurized pipeline is connected to the top of the reactor, the middle of the pressurized pipeline is connected to the vacuum pump through a connecting pipe, and one end of the pressurized pipeline is connected to the pressurizing equipment.

[0008] As a further improvement of the technical solution, a first sampling head and a third blind plate are installed on the feed pipeline.

[0009] As a further improvement of the technical solution, the first catalyst delivery pipeline is also connected to a first nitrogen delivery pipeline.

[0010] As a further improvement of the technical solution, a second nitrogen delivery pipeline is installed on the second catalyst delivery pipeline.

[0011] As a further improvement of the technical solution, a catalyst storage tank control pipeline is connected to one side of the top of the catalyst storage tank, and a pressure gauge, a third nitrogen delivery pipeline and a second sampling head are installed on the catalyst storage tank control pipeline.

[0012] Compared with the prior art, the utility model has the following beneficial effects:

[0013] The online catalyst unloading system of the acrylonitrile unit reactor uses a vacuum system to draw negative pressure to the catalyst storage tank, causing a pressure difference between the reactor and the catalyst storage tank, and cooperates with the conveying air to unload the catalyst in the reactor into the catalyst storage tank. The catalyst unloading process uses nitrogen as the conveying air, and desalted water is used as the pipeline accompanying cooling medium to reduce the temperature of the catalyst mixed gas, ensuring the safety of the unloading operation, and realizing the unloading when the reactor is running to avoid the shutdown of the device, thereby realizing the long-term operation of the reactor. The catalyst unloading speed can be accurately controlled by controlling the diameter of the online unloading pipeline, which has little effect on the operation of the reactor. The online unloading system uses nitrogen as the conveying air and the tank loosening air to prevent the catalyst mixed gas from exploding in the tank. A heat exchanger is set on the online unloading pipeline, and the desalted water accompanying cooling pipeline is used to reduce the temperature of the catalyst and reaction gas to ensure safe operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention is described in more detail below by way of example with reference to the accompanying drawings, in which:

[0015] Figure 1 This is a schematic diagram of the existing catalyst loading and unloading process;

[0016] Figure 2 It is a schematic diagram of the system structure of the utility model.

[0017] The meaning of each number in the figure is:

[0018] 1. Reactor; 2. Catalyst storage tank; 3. First catalyst delivery pipeline; 301. First blind plate; 302. Second blind plate; 303. First nitrogen delivery pipeline; 304. Heat exchanger; 4. Second catalyst delivery pipeline; 401. Second nitrogen delivery pipeline; 402. First sampling head; 403. Third blind plate; 5. Air supply pipeline; 501. Nitrogen delivery device; 6. Connecting pipeline; 7. Catalyst storage tank control pipeline; 701. Pressure gauge; 702. Third nitrogen delivery pipeline; 703. Second sampling head; 8. Pressurization pipeline; 801. Vacuuming device; 802. Pressurization equipment. DETAILED DESCRIPTION

[0019] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0020] Example: Figure 2 As shown: an online catalyst unloading system for an acrylonitrile unit reactor comprises a reactor 1 and a catalyst storage tank 2, one side of the reactor 1 is connected to a feed pipeline 404 on the catalyst storage tank 2 via a second catalyst delivery pipeline 4, the other side of the reactor 1 is connected to a feed pipeline 404 via a first catalyst delivery pipeline 3, one end of the first catalyst delivery pipeline 3 is connected to the reactor 1 via a first connecting pipe and a second connecting pipe, a first blind plate 301 is installed on the first connecting pipe, a second blind plate 302 is installed on the second connecting pipe, and a heat exchanger 304 is also installed in the middle of the first catalyst delivery pipeline 3;

[0021] One side of the bottom of the catalyst storage tank 2 is connected to an air supply pipeline 5 , one end of which is connected to a nitrogen delivery device 501 . The air supply pipeline 5 is connected to the other side of the bottom of the catalyst storage tank 2 via a connecting pipeline 6 .

[0022] A pressurizing pipeline 8 is connected to the top of the reactor 1 , the middle of the pressurizing pipeline 8 is connected to a vacuum pumping device 801 via a connecting pipe, and one end of the pressurizing pipeline 8 is connected to a pressurizing device 802 .

[0023] The feed pipeline 404 is installed with a first sampling head 402 and a third blind plate 403 .

[0024] The first catalyst delivery pipeline 3 is also connected to a first nitrogen delivery pipeline 303 .

[0025] A second nitrogen delivery pipeline 401 is installed on the second catalyst delivery pipeline 4 .

[0026] A catalyst storage tank control pipeline 7 is connected to one side of the top of the catalyst storage tank 2 , and a pressure gauge 701 , a third nitrogen delivery pipeline 702 and a second sampling head 703 are installed on the catalyst storage tank control pipeline 7 .

[0027] Working principle: The online catalyst unloading system of the acrylonitrile unit reactor uses a vacuum system to pump negative pressure into the catalyst storage tank, causing a pressure difference between the reactor and the catalyst storage tank. With the help of conveying air, the catalyst in the reactor is unloaded into the catalyst storage tank. The catalyst unloading process uses nitrogen as the conveying air, and desalted water as the pipeline accompanying cooling medium to reduce the temperature of the catalyst mixed gas, ensuring the safety of the unloading operation.

[0028] When the reactor 1 is not working, the first blind plate 301, the second blind plate 302 and the third blind plate 403 can be opened, and the catalyst in the reactor 1 can be transported to the feed line 404 through the second catalyst delivery line 4 and the first catalyst delivery line 3 by using the second nitrogen delivery line 401 and the first nitrogen delivery line 303, and then enter the catalyst storage tank 2 through the feed line 404, thereby improving efficiency and saving time;

[0029] When the reactor 1 is working, by opening any one or both of the first blind plate 301 or the second blind plate 302, the catalyst is transported to the heat exchanger 304 by the first nitrogen delivery pipeline 303, and the temperature of the catalyst mixed gas is lowered by using desalted water as the pipeline accompanying cooling medium, and then the catalyst is transported to the catalyst storage tank 2 through the feed pipeline 404. At the same time, the nitrogen delivery device 501 at one end of the air supply pipeline 5 is used to transport nitrogen to the catalyst storage tank 2, and the nitrogen is used as loosening wind to prevent the catalyst mixed gas from exploding in the storage tank, thereby improving safety performance.

[0030] The specific steps are as follows:

[0031] Catalyst storage tank nitrogen replacement steps:

[0032] Step 1: Confirm that the nitrogen pressure in the catalyst storage tank 2 is maintained (0.1 MPa) and the third blind plate 403 is in a blind closed state.

[0033] Step 2: Open the catalyst storage tank catalyst suction pipeline exhaust drain and catalyst suction valve to release the system pressure until the pressure (PG-11012A) is 0MPa.

[0034] Step 3: After the system is depressurized, the reactor unloads the catalyst into the catalyst storage tank, and the third blind plate 403 on the feed pipeline 404 is adjusted to a blind passage.

[0035] Step 4: Check that the instrument air pressurizing valve of the catalyst storage tank is closed; the two valves of the pipeline from reactor 1 to the catalyst storage tank are closed; the cone valve of the catalyst storage tank is closed; and the catalyst storage tank drain valve and exhaust valve are closed.

[0036] Step 5: Connect a nitrogen hose to the third nitrogen delivery pipeline 702 of the catalyst storage tank, open the drain valve to pressurize the catalyst storage tank system to 0.1 MPa, and slowly open the catalyst suction port valve to release the pressure.

[0037] Step 6: After the catalyst storage tank is depressurized to 0 MPa, close the pressure relief valve, re-pressurize with nitrogen to 0.1 MPa, and then discharge. Repeat the operation 6 times. Contact the laboratory to sample and analyze the oxygen content at the first sampling head 402 and the second sampling head 703. If the oxygen content is not below 0.5%, repeat the nitrogen replacement operation until the analyzed oxygen content is less than 0.5%. Stop the nitrogen replacement work and keep the catalyst storage tank pressurized with nitrogen.

[0038] 2. Steps for removing the agent:

[0039] Step 1: Confirm that the third blind plate 403 on the feed pipeline 404 is in a blind state; the nitrogen replacement is qualified (oxygen content is less than 0.5%), and is in a nitrogen pressure maintenance state.

[0040] Step 2: The first blind plate 301 or the second blind plate 302 on the reactor unloading pipe is in a blind connection, the airtightness is qualified, and all valves and components of the system are intact;

[0041] Step 3: Confirm that the valve of the reactor unloading process on the other side is closed;

[0042] Step 4: The nitrogen delivery device 501 is changed from instrument air to nitrogen, a nitrogen metal hose is connected to the nitrogen delivery device 501, and nitrogen loosening air is used;

[0043] Step 5: Enable the vacuum system to maintain the pressure of the catalyst storage tank at 0.03MPaA;

[0044] Step 6: Open the reactor sampling port to the catalyst storage tank process, use nitrogen delivery air to purge the catalyst unloading process for 1 hour, and control the air volume to 300Nm 3 / h (reference boundary nitrogen flowmeter);

[0045] Step 7: Slightly open the sampling port valve to unload the catalyst into the catalyst storage tank (stop immediately when the pipeline after the valve becomes hot) and observe the change of catalyst storage. Use desalted water for cooling to ensure that the pipeline temperature does not exceed 150℃.

[0046] Step 8: Adjust the valve opening, control the unloading speed by 1-2 t / h according to the reactor storage meter, and frequently check the blockage of the unloading line; strengthen the monitoring of the reactor operation during the unloading process, and immediately close the unloading valve if there is any abnormality; take samples from the quench tower to observe the catalyst loss;

[0047] Step 9: When the reserve meter reaches 235 tons, close the sampling port valve and continue to purge the unloading pipeline with nitrogen;

[0048] Step 10: After purging the unloading pipeline for 1 hour, turn off the nitrogen delivery air, nitrogen loosening air, and close all valves on the unloading pipeline;

[0049] Step 11: Deactivate the injection pump, depressurize the catalyst storage tank 2 system, and adjust the third blind plate 403 to the blind close position.

[0050] Step 12: Pressurize the catalyst storage tank 2 to 0.1 MPa and maintain the pressure.

[0051] The improvement of this embodiment lies in that the online catalyst unloading system of the acrylonitrile unit reactor is equipped with an online unloading process, which can realize unloading while the reactor is running to avoid stopping the unit, realize long-term operation, and save the problem of alternating start and stop of the two reactors of the unit. The catalyst unloading speed can be accurately controlled by adjusting the pipe diameter of the unloading process online, which has little effect on the operation of the reactor. The online unloading process uses nitrogen as the conveying air and tank loosening air to prevent the explosion of the catalyst mixed gas. The online unloading process is equipped with a desalted water cooling pipeline to reduce the temperature of the catalyst and the reaction gas to ensure safe operation.

[0052] The above shows and describes the basic principle, main features and advantages of the utility model. Those skilled in the art should understand that the utility model is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the utility model and are not used to limit the utility model. Without departing from the spirit and scope of the utility model, the utility model may have various changes and improvements, which fall within the scope of the utility model to be protected. The scope of protection of the utility model is defined by the attached claims and their equivalents.

Claims

1. An online catalyst unloading system for an acrylonitrile plant reactor, comprising a reactor (1) and a catalyst storage tank (2), characterized in that: One side of the reactor (1) is connected to a feed pipeline (404) on a catalyst storage tank (2) via a second catalyst delivery pipeline (4), and the other side of the reactor (1) is connected to the feed pipeline (404) via a first catalyst delivery pipeline (3), one end of the first catalyst delivery pipeline (3) is connected to the reactor (1) via a first connecting pipe and a second connecting pipe, a first blind plate (301) is installed on the first connecting pipe, and a second blind plate (302) is installed on the second connecting pipe, and a heat exchanger (304) is also installed in the middle of the first catalyst delivery pipeline (3); One side of the bottom of the catalyst storage tank (2) is connected to an air supply pipeline (5), one end of the air supply pipeline (5) is connected to a nitrogen delivery device (501), and the air supply pipeline (5) is connected to the other side of the bottom of the catalyst storage tank (2) via a connecting pipeline (6).

2. The on-line catalyst unloading system for the reactor of an acrylonitrile device according to claim 1, characterized in that: The top of the reactor (1) is connected to a pressurizing pipeline (8), the middle of the pressurizing pipeline (8) is connected to a vacuum pump (801) via a connecting pipe, and one end of the pressurizing pipeline (8) is connected to a pressurizing device (802).

3. The on-line catalyst unloading system for the reactor of an acrylonitrile device according to claim 1, characterized in that: The feed pipeline (404) is installed with a first sampling head (402) and a third blind plate (403).

4. The on-line catalyst unloading system for an acrylonitrile device reactor according to claim 1, characterized in that: The first catalyst delivery pipeline (3) is also connected to a first nitrogen delivery pipeline (303).

5. The on-line catalyst unloading system for the reactor of an acrylonitrile device according to claim 1, characterized in that: A second nitrogen delivery pipeline (401) is installed on the second catalyst delivery pipeline (4).

6. The on-line catalyst unloading system for an acrylonitrile device reactor according to claim 1, characterized in that: A catalyst storage tank control pipeline (7) is connected to one side of the top of the catalyst storage tank (2), and a pressure gauge (701), a third nitrogen delivery pipeline (702) and a second sampling head (703) are installed on the catalyst storage tank control pipeline (7).

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