Method and device for starting hydrogen system in olefin separation production
By adding the methanation start-up replacement line, the new cold box 3 torch line and the hydrogen start-up line, the cold box cooling process is optimized, the methanation reactor is driven in advance, and hydrogen is distributed simultaneously in the downstream process, the problem of the long-term temperature and cooling time of the methanation reactor in hydrogen preparation is solved, and the efficient and energy-saving hydrogen preparation start-up process is achieved.
Patent Information
- Application Number
- CN202311647306.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-04
- Publication Date
- 2025-06-06
AI Technical Summary
In the existing hydrogen production, there are economic losses caused by the flying temperature of the methanation reactor when driving, the cooling time of the device when driving, and the excessive carbon-2 material discharge torch.
By adding the methanation replacement line, the new cold box 3 torch line and the hydrogen start line, the cold box cooling process is optimized, the methanation reactor is driven in advance, and the hydrogen distribution is synchronized in the downstream process to reduce the loss of carbon-2 material torch discharge.
It improves the efficiency of hydrogen preparation, reduces material consumption and control risks, ensures stable production of downstream processes, reduces energy consumption and material losses, and achieves the goals of energy saving, consumption reduction and operational safety.
Smart Images
Figure CN120094522A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of hydrogen preparation, and relates to a method and a device for starting a hydrogen system in olefin separation production. Background Art
[0002] After the expansion and renovation, the company's existing 220,000 tons / year ethylene unit can produce 219.996 tons of polymerization-grade ethylene and 105.658 tons of polymerization-grade propylene within 7,560 hours of operation per year. The renovation adopts the LUMMUS process package. Among them, according to the sequential separation process, the crude hydrogen from the new and old cold boxes is heated to 30°C respectively, one stream is sent to the hydrogen production unit through a regulating valve, and the remaining hydrogen flow is methanated under the action of a catalyst to produce 95% (mol) hydrogen products. Another wet hydrogen flow is sent to the hydrogen production unit, and the remaining hydrogen products are dried in a molecular sieve drying system. The dried hydrogen product is used for acetylene reactors, MAPD converters, and polyolefin units, and the excess is sent to the hydrogen pipeline network.
[0003] Due to the lack of cooling capacity and slow cooling speed when the new cold box was started up, it took at least 8 hours after the old cold box was cooled down to the required level before the crude hydrogen could meet the feeding requirements of the methanation reactor; the cold box outlet and the methanation reactor formed a pipeline blind end of about 150 meters. When the methanation reactor was started up, the crude hydrogen material in the pipeline had a high ethylene content and the bed was prone to temperature rise; the cold box cooled down slowly, which prolonged the start-up time of the methanation reactor, and there was no qualified hydrogen to supply hydrogen to the acetylene hydrogenation reactor, which increased the carbon dioxide flare emission time at the reactor outlet. These problems became apparent during the start-up process, seriously affecting the product qualification time and the start-up energy consumption of the ethylene unit. Summary of the invention
[0004] The present invention provides a method and device for starting a hydrogen system in olefin separation production, which overcomes the shortcomings of the above-mentioned prior art and can effectively solve the problems of temperature rise during the start-up of a methanation reactor, too long cycle cooling time during the start-up of the device, and economic losses caused by excessive carbon dioxide discharge from the flare in the existing hydrogen preparation production.
[0005] One of the technical solutions of the present invention is achieved by the following measures: A method and device for starting a hydrogen system in olefin separation production, comprising the following steps: In the first step, a first crude hydrogen and a second crude hydrogen are produced by a first hydrogen production device and a second hydrogen production device respectively; The second step is to deliver the first crude hydrogen, the second crude hydrogen or the third crude hydrogen from the hydrogen pipeline network to a methanation reactor according to whether the first crude hydrogen and the second crude hydrogen meet the standards, remove impurities therein and obtain qualified hydrogen; The third step is to cool, dehydrate and dry the qualified hydrogen before sending it to the downstream hydrogen preparation process.
[0006] The following is a further optimization and / or improvement of one of the above-mentioned technical solutions: In the second step, the compliance conditions of the first crude hydrogen and the second crude hydrogen include: the first crude hydrogen meets the standard but the second crude hydrogen does not meet the standard, the first crude hydrogen and the second crude hydrogen both meet the standard, and the first crude hydrogen and the second crude hydrogen both do not meet the standard.
[0007] When the first crude hydrogen meets the standard but the second crude hydrogen does not, the first crude hydrogen is sent to the methanation reactor to remove impurities in the first crude hydrogen to obtain qualified hydrogen; when both the first crude hydrogen and the second crude hydrogen meet the standard, the first crude hydrogen and the second crude hydrogen are sent to the methanation reactor to remove impurities in the first crude hydrogen and the second crude hydrogen to obtain qualified hydrogen; when both the first crude hydrogen and the second crude hydrogen do not meet the standard, the third crude hydrogen from the hydrogen pipeline network is sent to the methanation reactor to obtain qualified hydrogen.
[0008] The second technical solution of the present invention is achieved by the following measures: a device for implementing a method for starting a hydrogen system in olefin separation production, comprising a methanation reactor, a new cold box, an old cold box, a propylene heat exchanger, a gas-liquid separation tank and a hydrogen dryer, a first crude hydrogen input pipeline is fixedly connected between the outlet of the old cold box and the inlet of the methanation reactor, a second crude hydrogen input pipeline is fixedly connected between the first crude hydrogen input pipeline and the outlet of the new cold box, a first qualified hydrogen pipeline is fixedly connected between the outlet of the methanation reactor and the inlet of the propylene heat exchanger, and a first qualified hydrogen pipeline is fixedly connected between the outlet of the propylene heat exchanger and the inlet of the gas-liquid separation tank. The second qualified hydrogen pipeline is fixedly connected between the outlet of the gas-liquid separation tank and the inlet of the hydrogen dryer. The outlet of the gas-liquid separation tank is fixedly connected with a drainage pipeline, the outlet of the hydrogen dryer is fixedly connected with a dry hydrogen output pipeline, the second crude hydrogen input pipeline and the first crude hydrogen input pipeline between the methanation reactor are fixedly connected with a start-up replacement pipeline, the first crude hydrogen input pipeline between the start-up replacement pipeline and the methanation reactor is fixedly connected with an external hydrogen production input pipeline, and a feed steam heater is fixedly installed on the first crude hydrogen input pipeline between the external hydrogen production input pipeline and the methanation reactor.
[0009] The following is a further optimization and / or improvement of the second technical solution of the above invention: The above-mentioned second crude hydrogen input pipeline is fixedly connected with a newly added flare removal pipeline, and a first regulating valve is fixedly installed on the newly added flare removal pipeline. The newly added flare removal pipelines before and after the first regulating valve are fixedly connected with a first parallel pipeline, and a hand valve is fixedly installed on the second crude hydrogen input pipeline between the first parallel pipeline, the newly added flare removal pipeline and the first crude hydrogen input pipeline.
[0010] An inlet and outlet heat exchanger is fixedly installed between the first crude hydrogen input pipeline between the above-mentioned external hydrogen production input pipeline and the feed steam heater and the first qualified hydrogen pipeline. The cold material inlet and outlet of the inlet and outlet heat exchanger are fixedly connected to the first crude hydrogen input pipeline, and the hot material inlet and outlet of the inlet and outlet heat exchanger are fixedly connected to the first qualified hydrogen pipeline.
[0011] A first automatic control valve is fixedly installed on the first crude hydrogen input pipeline between the start-up replacement pipeline and the external hydrogen production input pipeline, a second parallel pipeline is fixedly connected between the first crude hydrogen input pipeline between the first automatic control valve and the external hydrogen production input pipeline and the first crude hydrogen input pipeline between the feed steam heater and the methanation reactor, and a second regulating valve is fixedly installed on the second parallel pipeline.
[0012] An exhaust-to-flare pipeline is fixedly connected between the first qualified hydrogen pipeline between the above-mentioned inlet and outlet heat exchanger and the methanation reactor and the start-up replacement pipeline, a third regulating valve is fixedly installed on the exhaust-to-flare pipeline, a first hydrogen online detector is arranged on the start-up replacement pipeline between the exhaust-to-flare pipeline and the first crude hydrogen input pipeline, a second hydrogen online detector is arranged on the newly added flare-removing pipeline between the first parallel pipeline and the newly added flare-removing pipeline outlet, and hand valves are fixedly installed on the start-up replacement pipelines before and after the first hydrogen online detector.
[0013] A discharge circulating water heat exchanger is fixedly installed on the first qualified hydrogen pipeline between the above-mentioned inlet and outlet heat exchangers and the propylene heat exchanger, a second automatic control valve is fixedly installed on the first qualified hydrogen pipeline between the discharge circulating water heat exchanger and the propylene heat exchanger, a wet hydrogen output pipeline is fixedly connected to the third qualified hydrogen pipeline, a fourth regulating valve is fixedly installed on the wet hydrogen output pipeline, and a fifth regulating valve is fixedly installed on the discharge pipeline.
[0014] The above-mentioned external hydrogen production input pipeline is provided with an 8-shaped blind plate, and the external hydrogen production input pipeline between the 8-shaped blind plate and the inlet of the external hydrogen production input pipeline and the start-up replacement pipeline between the first hydrogen online detector and the first crude hydrogen input pipeline are fixedly connected with a pipeline network hydrogen replacement pipeline, and hand valves are fixedly installed on the external hydrogen production input pipeline and the pipeline network hydrogen replacement pipeline before and after the 8-shaped blind plate.
[0015] The present invention improves the start-up efficiency of hydrogen preparation, reduces material consumption and control risks during the start-up of hydrogen preparation, ensures stable production of downstream processes during the start-up of hydrogen preparation, reduces material losses, and achieves the goals of energy saving, consumption reduction and operational safety. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Attached Figure 1 This is a schematic diagram of the process flow of Example 4 of the present invention.
[0017] The codes in the attached figure are: 1 is a methanation reactor, 2 is an old cold box, 3 is a new cold box, 4 is a propylene heat exchanger, 5 is a gas-liquid separation tank, 6 is a hydrogen dryer, 7 is a first crude hydrogen input pipeline, 8 is a second crude hydrogen input pipeline, 9 is a first qualified hydrogen pipeline, 10 is a second qualified hydrogen pipeline, 11 is a third qualified hydrogen pipeline, 12 is a drainage pipeline, 13 is a dry hydrogen output pipeline, 14 is a start-up replacement pipeline, 15 is an external hydrogen production input pipeline, 16 is a feed steam heater, and 17 is a newly added flare pipe Line, 18 is the first regulating valve, 19 is the first parallel pipeline, 20 is the inlet and outlet heat exchanger, 21 is the first automatic control valve, 22 is the second parallel pipeline, 23 is the second regulating valve, 24 is the exhaust to flare pipeline, 25 is the third regulating valve, 26 is the first hydrogen online detector, 27 is the outlet circulating water heat exchanger, 28 is the second automatic control valve, 29 is the wet hydrogen output pipeline, 30 is the fourth regulating valve, 31 is the fifth regulating valve, 32 is the 8-shaped blind plate, 33 is the second hydrogen online detector, and 34 is the pipeline network hydrogen replacement pipeline. DETAILED DESCRIPTION
[0018] The present invention is not limited by the following embodiments, and specific implementation methods can be determined based on the technical solution of the present invention and actual conditions.
[0019] The present invention will be further described below in conjunction with embodiments: Embodiment 1: As attached Figure 1 As shown, the method for starting up the hydrogen system in olefin separation production comprises the following steps: In the first step, the first crude hydrogen and the second crude hydrogen are produced by the first hydrogen production device (old cold box 2) and the second hydrogen production device (new cold box 3), respectively; The second step is to deliver the first crude hydrogen, the second crude hydrogen or the third crude hydrogen from the hydrogen pipeline network to the methanation reactor 1 according to whether the first crude hydrogen and the second crude hydrogen meet the standards, remove impurities therein and obtain qualified hydrogen; The third step is to cool, dehydrate and dry the qualified hydrogen before sending it to the downstream hydrogen preparation process.
[0020] The present invention adds a methanation start-up replacement line, a new cold box 3 flare line and a hydrogen start-up line, and puts the methanation start-up replacement line and the new cold box 3 flare line into use in sequence during the start-up of the ethylene device, thereby accelerating the cooling speed of the cold box, avoiding the risk of temperature runaway when the methanation reactor 1 is started, and the methanation reactor 1 is started in advance, providing conditions for timely hydrogen preparation after the acetylene hydrogenation reactor is fed, avoiding the loss of carbon dioxide material flaring caused by lack of qualified hydrogen, and achieving the goal of low-energy consumption start-up of the device.
[0021] Example 2: As an optimization of the above example, in the second step, the compliance conditions of the first crude hydrogen and the second crude hydrogen include: the first crude hydrogen meets the standard but the second crude hydrogen does not meet the standard, the first crude hydrogen and the second crude hydrogen both meet the standard, and the first crude hydrogen and the second crude hydrogen do not meet the standard.
[0022] Example 3: As an optimization of the above example, when the first crude hydrogen meets the standard but the second crude hydrogen does not meet the standard, the first crude hydrogen is sent to the methanation reactor 1, impurities in the first crude hydrogen are removed, and qualified hydrogen is obtained; when both the first crude hydrogen and the second crude hydrogen meet the standard, the first crude hydrogen and the second crude hydrogen are sent to the methanation reactor 1, impurities in the first crude hydrogen and the second crude hydrogen are removed, and qualified hydrogen is obtained; when both the first crude hydrogen and the second crude hydrogen do not meet the standard, the third crude hydrogen from the hydrogen pipeline network is sent to the methanation reactor 1 to obtain qualified hydrogen.
[0023] Embodiment 4: As attached Figure 1 As shown, the device of the hydrogen system start-up method in olefin separation production comprises a methanation reactor 1, a new cold box 3, an old cold box 2, a propylene heat exchanger 4, a gas-liquid separation tank 5 and a hydrogen dryer 6, a first crude hydrogen input pipeline 7 is fixedly connected between the outlet of the old cold box 2 and the inlet of the methanation reactor 1, a second crude hydrogen input pipeline 8 is fixedly connected between the first crude hydrogen input pipeline 7 and the outlet of the new cold box 3, a first qualified hydrogen pipeline 9 is fixedly connected between the outlet of the methanation reactor 1 and the inlet of the propylene heat exchanger 4, a second qualified hydrogen pipeline 10 is fixedly connected between the outlet of the propylene heat exchanger 4 and the inlet of the gas-liquid separation tank 5, and the outlet of the gas-liquid separation tank 5 is fixedly connected to the inlet of the propylene heat exchanger 4. A third qualified hydrogen pipeline 11 is fixedly connected between the inlet and the inlet of the hydrogen dryer 6, a discharge pipeline 12 is fixedly connected to the outlet of the gas-liquid separation tank 5, a dry hydrogen output pipeline 13 is fixedly connected to the outlet of the hydrogen dryer 6, a start-up replacement pipeline 14 is fixedly connected to the first crude hydrogen input pipeline 7 between the second crude hydrogen input pipeline 8 and the methanation reactor 1, an external hydrogen production input pipeline 15 is fixedly connected to the first crude hydrogen input pipeline 7 between the start-up replacement pipeline 14 and the methanation reactor 1, and a feed steam heater 16 is fixedly installed on the external hydrogen production input pipeline 15 and the first crude hydrogen input pipeline 7 between the methanation reactor 1.
[0024] Embodiment 5: As an optimization of the above embodiment, as shown in the attached Figure 1 As shown, the second crude hydrogen input pipeline 8 is fixedly connected to a newly added flare removal pipeline 17, and a first regulating valve 18 is fixedly installed on the newly added flare removal pipeline 17. The newly added flare removal pipeline 17 before and after the first regulating valve 18 is fixedly connected to a first parallel pipeline 19, and a hand valve is fixedly installed on the second crude hydrogen input pipeline 8 between the first parallel pipeline 19, the newly added flare removal pipeline 17 and the first crude hydrogen input pipeline 7.
[0025] Embodiment 6: As an optimization of the above embodiment, as shown in the attached Figure 1As shown, an inlet and outlet heat exchanger 20 is fixedly installed between the first crude hydrogen input pipeline 7 between the external hydrogen production input pipeline 15 and the feed steam heater 16 and the first qualified hydrogen pipeline 9, and the cold material inlet and outlet of the inlet and outlet heat exchanger 20 is fixedly connected to the first crude hydrogen input pipeline 7, and the hot material inlet and outlet of the inlet and outlet heat exchanger 20 is fixedly connected to the first qualified hydrogen pipeline 9.
[0026] Embodiment 7: As an optimization of the above embodiment, as shown in the attached Figure 1 As shown, a first automatic control valve 21 is fixedly installed on the first crude hydrogen input pipeline 7 between the start-up replacement pipeline 14 and the external hydrogen production input pipeline 15, and a second parallel pipeline 22 is fixedly connected between the first crude hydrogen input pipeline 7 between the first automatic control valve 21 and the external hydrogen production input pipeline 15 and the first crude hydrogen input pipeline 7 between the feed steam heater 16 and the methanation reactor 1, and a second regulating valve 23 is fixedly installed on the second parallel pipeline 22.
[0027] Embodiment 8: As an optimization of the above embodiment, as shown in the attached Figure 1 As shown, an exhaust to flare pipeline 24 is fixedly connected between the first qualified hydrogen pipeline 9 between the inlet and outlet heat exchanger 20 and the methanation reactor 1 and the start-up replacement pipeline 14, a third regulating valve 25 is fixedly installed on the exhaust to flare pipeline 24, a first hydrogen online detector 26 is arranged on the start-up replacement pipeline 14 between the exhaust to flare pipeline 24 and the first crude hydrogen input pipeline 7, a second hydrogen online detector 33 is arranged on the newly added flare-removing pipeline 17 between the first parallel pipeline 19 and the outlet of the newly added flare-removing pipeline 17, and manual valves are fixedly installed on the start-up replacement pipeline 14 before and after the first hydrogen online detector 26.
[0028] Embodiment 9: As an optimization of the above embodiment, as shown in the attached Figure 1 As shown, a discharge circulating water heat exchanger 27 is fixedly installed on the first qualified hydrogen pipeline 9 between the inlet and outlet heat exchanger 20 and the propylene heat exchanger 4, a second automatic control valve 28 is fixedly installed on the first qualified hydrogen pipeline 9 between the discharge circulating water heat exchanger 27 and the propylene heat exchanger 4, a wet hydrogen output pipeline 29 is fixedly connected to the third qualified hydrogen pipeline 11, a fourth regulating valve 30 is fixedly installed on the wet hydrogen output pipeline 29, and a fifth regulating valve 31 is fixedly installed on the discharge pipeline 12.
[0029] As required, the water-containing wet hydrogen separated by the gas-liquid separation tank 5 can be delivered to the hydrogen production device via the wet hydrogen output pipeline 29 .
[0030] Embodiment 10: As an optimization of the above embodiment, as shown in the attached Figure 1As shown, an 8-shaped blind plate 32 is provided on the external hydrogen production input pipeline 15, and a pipeline network hydrogen replacement pipeline 34 is fixedly connected between the external hydrogen production input pipeline 15 between the 8-shaped blind plate 32 and the inlet of the external hydrogen production input pipeline 15 and the start-up replacement pipeline 14 between the first hydrogen online detector 26 and the first crude hydrogen input pipeline 7, and hand valves are fixedly installed on the external hydrogen production input pipeline 15 and the pipeline network hydrogen replacement pipeline 34 before and after the 8-shaped blind plate 32.
[0031] As needed, when both the first crude hydrogen and the second crude hydrogen meet the standards, the first crude hydrogen and the second crude hydrogen are delivered to the methanation reactor 1 to ensure normal and stable operation, and then the external hydrogen production input pipeline 15 can be temporarily blinded through the 8-shaped blind plate 32.
[0032] In the present invention, unless otherwise specified, the equipment and devices used are all the equipment and devices known and used in the art.
[0033] As required, conventional valves, thermometers and pressure gauges known and used in the art can be installed on the pipelines and equipment of the device of the method for starting the hydrogen system in olefin separation production according to production needs. The above-mentioned automatic control valves, regulating valves, hydrogen online detectors, etc. can be interlocked with related equipment according to production needs, and automatic operation can be achieved through automatic control programs.
[0034] Embodiment 11: The method for starting up the hydrogen system in the olefin separation production comprises the following steps: Two hours before the start of the hydrogen system in olefin separation production, the first automatic control valve 21 is closed to divide the hydrogen system in olefin separation production into two operation lines for simultaneous operation, that is, the methanation reactor 1 start-up replacement line and the external hydrogen preparation start-up line are operated simultaneously.
[0035] When the external hydrogen supply start-up line is in operation, the hydrogen in the hydrogen pipeline network is sent to the first crude hydrogen input pipeline 7 through the external hydrogen production input pipeline 15, and then enters the methanation reactor 1 after heat exchange and temperature increase through the inlet and outlet heat exchangers 20 and the feed steam heater 16, and the bed temperature is maintained between 230°C and 270°C to produce qualified hydrogen for standby use.
[0036] When the replacement line of methanation reactor 1 is started up, the manual valve on the second crude hydrogen input pipeline 8 between the newly added flare removal pipeline 17 and the first crude hydrogen input pipeline 7 is closed, and the second crude hydrogen containing high concentration of ethylene from the second hydrogen production unit (new cold box 3) is flared via the newly added flare removal pipeline 17, and the first crude hydrogen containing high concentration of ethylene from the first hydrogen production unit (old cold box 2) is flared via the first crude hydrogen input pipeline 7 via the start-up replacement pipeline 14.
[0037] When the first hydrogen online detector 26 and the second hydrogen online detector 33 detect that the first crude hydrogen meets the standard but the second crude hydrogen does not meet the standard, the manual valve on the start-up replacement pipeline 14 is closed, the manual valve on the external hydrogen production input pipeline 15 is closed, and the first automatic control valve 21 is opened. The first crude hydrogen enters the methanation reactor 1 through the first crude hydrogen input pipeline 7, and is heated by the inlet and outlet heat exchanger 20 and the feed steam heater 16 in sequence. Impurities in the first crude hydrogen are removed, and the obtained qualified hydrogen is cooled by the inlet and outlet heat exchanger 20, the outlet circulating water heat exchanger 27 and the propylene heat exchanger 4 in sequence, and then separated into gas phase and liquid phase by the gas-liquid separation tank 5. The gas phase is dried by the hydrogen dryer 6 and sent to the downstream hydrogen preparation process; When both the first crude hydrogen and the second crude hydrogen meet the standards, the manual valve on the start-up replacement pipeline 14 is closed, the manual valve on the external hydrogen production input pipeline 15 is closed, the first regulating valve 18 for the second crude hydrogen to be flared from the newly added flare removal pipeline 17 is closed, the manual valve on the second crude hydrogen input pipeline 8 between the newly added flare removal pipeline 17 and the first crude hydrogen input pipeline 7 is opened, and the first automatic control valve 21 is opened. The first crude hydrogen and the second crude hydrogen are mixed and heated from the first crude hydrogen input pipeline 7 in turn through the feed and discharge heat exchanger 20 and the feed steam heater 16 to enter the methanation reactor 1, and impurities in the first crude hydrogen are removed. The qualified hydrogen obtained is cooled in turn through the feed and discharge heat exchanger 20, the discharge circulating water heat exchanger 27 and the propylene heat exchanger 4, and then separated into gas phase and liquid phase by the gas-liquid separation tank 5. The gas phase is dried by the hydrogen dryer 6 and sent to the downstream hydrogen preparation process; When both the first crude hydrogen and the second crude hydrogen fail to meet the standards, the first automatic control valve 21 is closed and the external hydrogen supply line is started.
[0038] In the original process, each time the device was started up, due to the high temperature of the new cold box 3, the cycle cooling took about 8 hours. During this period, a large amount of hydrogen from ethylene materials gathered in the pipeline in front of the solenoid valve of the methanation feed line. This line is DN100 and about 150 meters long. The start-up requirement is that the ethylene content in this line is less than 1000 ml / m³. At this time, the ethylene content in the pipeline is about 50% (volume fraction), which is much higher than the ethylene content requirement in the hydrogen of the methanation reactor 1. The crude hydrogen has a high ethylene content. When the feed of the methanation reactor 1 is started up, at a bed temperature above 200°C, a strong exothermic reaction of ethylene decomposition occurs under the action of the catalyst. The bed temperature is difficult to control and even temperature spikes occur, damaging the catalyst and reactor equipment.
[0039] The present invention adds a methanation start-up replacement line to introduce unqualified crude hydrogen containing high-concentration ethylene into a flare system until the ethylene content in the crude hydrogen reaches the start-up requirement of less than 1000 mL / m³, thereby avoiding the risk of high temperature of the methanation reactor 1 on the catalyst and equipment.
[0040] According to needs, in actual operation, the present invention can also add a pipeline to the upstream process before the flare in the methanation start-up replacement line. During the start-up of the device, the unqualified crude hydrogen containing high concentration of ethylene in the methanation start-up replacement line is introduced into the upstream process to avoid all the unqualified crude hydrogen being directly introduced into the flare system to cause material loss and environmental pollution.
[0041] Due to the existing process, the cooling speed at start-up is slow, while the cooling speed of the old cold box 2 is fast. When the temperature of the old cold box 2 drops to below -150°C, the methanation reactor 1 can be put into use to produce qualified hydrogen. The present invention places a flare line in the new cold box 3 to separate the hydrogen lines of the new cold box 3 and the old cold box 2 for separate cooling. When the temperature of the old cold box 2 drops to below -150°C, the methanation reactor 1 can be started in advance, and when the temperature of the new cold box 3 drops to below -155°C, the crude hydrogen from the new cold box 3 is incorporated into the methanation reactor 1. In this way, on the one hand, the loss of hydrogen flaring from the old cold box 2 during the cooling of the new cold box 3 (about 3 tons each time) is avoided, and at the same time, the methanation reactor 1 is started in advance to produce qualified hydrogen, thereby reducing the flare loss of carbon dioxide at the outlet of the acetylene hydrogenation reactor.
[0042] The present invention adds a hydrogen start-up line, introduces crude hydrogen from a hydrogen pipeline network into the inlet of a methanation reactor 1, and the hydrogen gas volume fraction is 99%. During the start-up of the device, before the feeding of an acetylene hydrogenation reactor in a downstream process begins, it is ensured that the start-up hydrogen is introduced into the methanation reactor 1, and the bed temperature is maintained between 230° C. and 250° C. After the acetylene hydrogenation reactor in the downstream process is fed, hydrogen can be prepared immediately, and the methanation reactor 1 does not need to be started after the crude hydrogen of a new cold box 3 and an old cold box 2 is qualified, thereby greatly shortening the flare loss of carbon dioxide materials caused by the start-up of the acetylene hydrogenation reactor in the downstream process and waiting for qualified hydrogen, and at the same time, convenient conditions are provided for cooling the new cold box 3 and the old cold box 2 and introducing qualified crude hydrogen into the methanation reactor 1.
[0043] Therefore, the present invention optimizes the start-up process of the methanation reactor 1, avoids the risk of the bed temperature flying when starting the methanation reactor 1, shortens the hydrogen qualified time, and can be synchronously prepared with hydrogen after the start-up and feeding of the acetylene hydrogenation reactor in the downstream process, thereby avoiding the loss of carbon dioxide materials due to the flare caused by the lack of qualified hydrogen. At the same time, the cooling speed of the new cold box 3 and the old cold box 2 is greatly improved, the time of hydrogen flare is shortened, and the loss of olefins in the cold box is reduced. When the temperature of the new cold box 3 and the old cold box 2 drops to -150°C, it is shortened from about 8 hours to about 6 hours now, which buys more time for the methanation reactor 1 to be fed in advance.
[0044] In summary, the present invention improves the start-up efficiency of hydrogen preparation, reduces material consumption and control risks during the start-up of hydrogen preparation, ensures stable production of downstream processes during the start-up of hydrogen preparation, reduces material losses, and achieves the goals of energy saving, consumption reduction and operational safety.
[0045] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.
Claims
1. A method for starting a hydrogen system in olefin separation production, Features The steps include: In the first step, a first crude hydrogen and a second crude hydrogen are produced by a first hydrogen production device and a second hydrogen production device respectively; The second step is to deliver the first crude hydrogen, the second crude hydrogen or the third crude hydrogen from the hydrogen pipeline network to a methanation reactor according to whether the first crude hydrogen and the second crude hydrogen meet the standards, remove impurities therein and obtain qualified hydrogen; The third step is to cool, dehydrate and dry the qualified hydrogen before sending it to the downstream hydrogen preparation process.
2. The method for starting a hydrogen system in olefin separation production according to claim 1, Features In the second step, the compliance conditions of the first crude hydrogen and the second crude hydrogen include: the first crude hydrogen meets the standard but the second crude hydrogen does not meet the standard, the first crude hydrogen and the second crude hydrogen both meet the standard, and the first crude hydrogen and the second crude hydrogen both do not meet the standard.
3. The method for starting a hydrogen system in olefin separation production according to claim 2, Features When the first crude hydrogen meets the standard but the second crude hydrogen does not, the first crude hydrogen is sent to the methanation reactor to remove impurities in the first crude hydrogen to obtain qualified hydrogen; when both the first crude hydrogen and the second crude hydrogen meet the standard, the first crude hydrogen and the second crude hydrogen are sent to the methanation reactor to remove impurities in the first crude hydrogen and the second crude hydrogen to obtain qualified hydrogen; when both the first crude hydrogen and the second crude hydrogen do not meet the standard, the third crude hydrogen from the hydrogen pipeline network is sent to the methanation reactor to obtain qualified hydrogen.
4. A device for implementing the method for starting up a hydrogen system in olefin separation production according to any one of claims 1 to 3, Features The invention comprises a methanation reactor, a new cold box, an old cold box, a propylene heat exchanger, a gas-liquid separation tank and a hydrogen dryer. A first crude hydrogen input pipeline is fixedly connected between the outlet of the old cold box and the inlet of the methanation reactor. A second crude hydrogen input pipeline is fixedly connected between the first crude hydrogen input pipeline and the outlet of the new cold box. A first qualified hydrogen pipeline is fixedly connected between the outlet of the methanation reactor and the inlet of the propylene heat exchanger. A second qualified hydrogen pipeline is fixedly connected between the outlet of the propylene heat exchanger and the inlet of the gas-liquid separation tank. A gas-liquid separation tank outlet is fixedly connected to the inlet of the hydrogen dryer. A third qualified hydrogen pipeline is fixedly connected between the ports, a drain pipeline is fixedly connected to the outlet of the gas-liquid separation tank, a dry hydrogen output pipeline is fixedly connected to the outlet of the hydrogen dryer, a start-up replacement pipeline is fixedly connected to the first crude hydrogen input pipeline between the second crude hydrogen input pipeline and the methanation reactor, an external hydrogen production input pipeline is fixedly connected to the first crude hydrogen input pipeline between the start-up replacement pipeline and the methanation reactor, and a feed steam heater is fixedly installed on the first crude hydrogen input pipeline between the external hydrogen production input pipeline and the methanation reactor.
5. The device according to claim 4, Features The second crude hydrogen input pipeline is fixedly connected with a newly added flare removal pipeline, on which a first regulating valve is fixedly installed, the newly added flare removal pipelines before and after the first regulating valve are fixedly connected with a first parallel pipeline, and a hand valve is fixedly installed on the second crude hydrogen input pipeline between the first parallel pipeline, the newly added flare removal pipeline and the first crude hydrogen input pipeline.
6. The device according to claim 4 or 5, Features An inlet and outlet heat exchanger is fixedly installed between the first crude hydrogen input pipeline between the external hydrogen production input pipeline and the feed steam heater and the first qualified hydrogen pipeline. The cold material inlet and outlet of the inlet and outlet heat exchanger are fixedly connected to the first crude hydrogen input pipeline, and the hot material inlet and outlet of the inlet and outlet heat exchanger are fixedly connected to the first qualified hydrogen pipeline.
7. The device according to claim 6, Features A first automatic control valve is fixedly installed on the first crude hydrogen input pipeline between the start-up replacement pipeline and the external hydrogen production input pipeline, a second parallel pipeline is fixedly connected between the first crude hydrogen input pipeline between the first automatic control valve and the external hydrogen production input pipeline and the first crude hydrogen input pipeline between the feed steam heater and the methanation reactor, and a second regulating valve is fixedly installed on the second parallel pipeline.
8. The device according to claim 6 or 7, Features An exhaust-to-flare pipeline is fixedly connected between the first qualified hydrogen pipeline between the inlet and outlet heat exchanger and the methanation reactor and the start-up replacement pipeline, a third regulating valve is fixedly installed on the exhaust-to-flare pipeline, a first hydrogen online detector is arranged on the start-up replacement pipeline between the exhaust-to-flare pipeline and the first crude hydrogen input pipeline, a second hydrogen online detector is arranged on the newly added flare-removing pipeline between the first parallel pipeline and the newly added flare-removing pipeline outlet, and hand valves are fixedly installed on the start-up replacement pipelines before and after the first hydrogen online detector.
9. The device according to claim 8, Features A discharge circulating water heat exchanger is fixedly installed on the first qualified hydrogen pipeline between the inlet and outlet heat exchangers and the propylene heat exchanger, a second automatic control valve is fixedly installed on the first qualified hydrogen pipeline between the discharge circulating water heat exchanger and the propylene heat exchanger, a third qualified hydrogen pipeline is fixedly connected to a wet hydrogen output pipeline, a fourth regulating valve is fixedly installed on the wet hydrogen output pipeline, and a fifth regulating valve is fixedly installed on the discharge pipeline.
10. The device according to any one of claims 4 or 5 or 7 or 9, Features An 8-shaped blind plate is arranged on the external hydrogen production input pipeline. The external hydrogen production input pipeline between the 8-shaped blind plate and the inlet of the external hydrogen production input pipeline and the start-up replacement pipeline between the first hydrogen online detector and the first rough hydrogen input pipeline are fixedly connected with a pipeline network hydrogen replacement pipeline. Hand valves are fixedly installed on the external hydrogen production input pipeline and the pipeline network hydrogen replacement pipeline before and after the 8-shaped blind plate.