A coupling system for preparing crude benzene hydrogenation and maleic anhydride with tail gas recycling

Abstract

The utility model discloses a kind of coupling systems of crude benzene hydrogenation and maleic anhydride preparation with tail gas reuse, belong to chemical technology field, the coupling system includes crude benzene hydrogenation unit and maleic anhydride preparation unit, the crude benzene hydrogenation unit includes hydrogen gas refining unit, the maleic anhydride preparation unit includes absorption tower, TO furnace, the TO furnace includes gas inlet one, gas inlet two and combustion chamber, tail gas in the hydrogen gas refining unit is transported into the combustion chamber by the gas inlet one, tail gas in the absorption tower is transported into the combustion chamber by the gas inlet two.The coupling system of the utility model replaces TO furnace part external fuel by tail gas of crude benzene hydrogenation, avoid the energy waste caused by crude benzene hydrogenation tail gas direct discharge.

Description

Technical Field

[0001] This utility model relates to the field of chemical technology, and more specifically, to a coupled system for the preparation of crude benzene hydrogenation and maleic anhydride with tail gas recycling. Background Technology

[0002] Currently, the crude benzene hydrogenation process generates tail gas containing hydrocarbons, hydrogen, and small amounts of impurities in the pre-separation unit. Direct emission of this tail gas would result in significant energy waste, as the hydrocarbons and hydrogen have high calorific values. Furthermore, the pollutants in the tail gas would pollute the environment and increase environmental treatment costs. In the maleic anhydride preparation process, the associated TO furnace requires fuel to treat the tail gas emitted from the absorber, oxidizing organic matter and carbon monoxide into harmless carbon dioxide and water. Traditional TO furnaces typically rely on external fuel for combustion energy, which not only increases the operating costs of the maleic anhydride preparation process but also fails to effectively integrate and utilize the tail gas resources from other processes.

[0003] The above problems urgently need to be solved. Therefore, this utility model provides a coupling system for the preparation of crude benzene hydrogenation and maleic anhydride with tail gas recycling. Utility Model Content

[0004] The technical problem to be solved by this utility model is to provide a coupling system for the preparation of crude benzene hydrogenation and maleic anhydride with tail gas recycling, which fully recovers the calorific value of the tail gas from the crude benzene hydrogenation process and avoids the energy waste caused by the direct emission of crude benzene hydrogenation tail gas.

[0005] The technical solution adopted by this utility model to solve its technical problem is: to provide a coupled system for crude benzene hydrogenation and maleic anhydride preparation with tail gas recycling, including a crude benzene hydrogenation unit and a maleic anhydride preparation unit. The crude benzene hydrogenation unit includes a hydrogen refining unit, and the maleic anhydride preparation unit includes an absorption tower and a TO furnace. The TO furnace includes an inlet one, an inlet two, and a combustion chamber. The tail gas in the hydrogen refining unit is transported to the combustion chamber through the inlet one, and the tail gas in the absorption tower is transported to the combustion chamber through the inlet two.

[0006] In this embodiment, specifically, the crude benzene hydrogenation unit further includes a vacuum distillation tower, a hydrogenation reactor, a pre-separation unit, an extraction unit, and a distillation tower, which are connected sequentially via pipelines.

[0007] In this embodiment, specifically, the second air inlet is also connected to a gas pipe, the gas pipe is equipped with a flow meter and a control valve, and the pre-separation unit is connected to the pipeline inside the TO furnace by a flow meter.

[0008] In this embodiment, specifically, the TO furnace includes a furnace body, an insulation layer disposed on the inner wall of the furnace body, and an air outlet opened on the furnace body. A preheating channel is disposed inside the insulation layer, and a combustion chamber is disposed inside the preheating channel.

[0009] In this embodiment, specifically, the preheating channel is a loop channel, and the preheating channel connects the air inlet and the combustion chamber.

[0010] In this embodiment, specifically, an air inlet pipe is provided on the furnace body, and the second air inlet is located at the end of the furnace body away from the air outlet.

[0011] In this embodiment, specifically, a partition is provided between the preheating channels, the partition is located on the end of the furnace body away from the gas outlet, and a gas distribution plate is provided between the partitions, the gas distribution plate having through holes.

[0012] In this embodiment, specifically, an ignition device is provided at the two outlet ends of the air inlet, and the ignition device is located on the side of the air distribution plate near the air outlet.

[0013] In this embodiment, specifically, the maleic anhydride preparation unit further includes a butane vaporizer, a butane superheater, an air heater, a butane mixer, a reactor, an air cooling unit, and an absorption tower. The butane mixer, the reactor, the air cooling unit, and the absorption tower are connected in sequence via pipelines. The butane vaporizer is connected to the butane superheater, and the butane superheater and the air heater are connected to the butane mixer.

[0014] In this embodiment, specifically, the maleic anhydride preparation unit further includes a post-flash evaporation tower, a stripping tower, a water washing unit, a solvent tank, and a product tower. The absorption tower is connected to the post-flash evaporation tower, and the post-flash evaporation tower is connected to the water washing unit and the solvent tank. The solvent tank is connected to the absorption tower.

[0015] The beneficial effects of this utility model are as follows: A coupled system for crude benzene hydrogenation and maleic anhydride preparation with tail gas recycling includes a crude benzene hydrogenation unit and a maleic anhydride preparation unit. The crude benzene hydrogenation unit includes a hydrogen refining unit, and the maleic anhydride preparation unit includes an absorption tower and a TO furnace. The TO furnace includes an inlet one, an inlet two, and a combustion chamber. The tail gas from the hydrogen refining unit is transported to the combustion chamber through the inlet one, and the tail gas from the absorption tower is transported to the combustion chamber through the inlet two. This replaces part of the external fuel in the TO furnace with the tail gas from the crude benzene hydrogenation. Simultaneously, the tail gas from the maleic anhydride preparation absorption tower is also effectively treated in the TO furnace, avoiding energy waste caused by direct emission of crude benzene hydrogenation tail gas and improving the overall environmental performance of the process. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0017] In the picture: Figure 1 This is a schematic diagram of the structure of a coupling system for the preparation of crude benzene hydrogenation and maleic anhydride with tail gas recycling according to this utility model; Figure 2 for Figure 1 Schematic diagram of the structure of the TO furnace; 100. Coupling system; 1. Crude benzene hydrogenation unit; 11. Vacuum reducing tower; 12. Hydrogenation reactor; 13. Hydrogen refining unit; 14. Pre-separation unit; 141. Flow meter 1; 15. Extraction unit; 16. Distillation column; 2. Maleic anhydride preparation unit; 21. Butane vaporizer; 22. Butane superheater; 23. Air heater; 24. Butane mixer; 25. Reactor; 26. Gas cooling unit; 27. Absorption tower; 28. TO furnace; 281. Furnace body; 282. Air inlet 1; 283. Air inlet 2; 284. Air inlet pipe; 2841. Air distribution plate; 285. Insulation layer; 286. Preheating channel; 2861. Baffle plate; 287. Combustion chamber; 288. Air outlet; 289. Ignition device; 29. ​​Gas pipe; 291. Flow meter; 292. Control valve; 31. Post-flash distillation tower; 32. Desorption tower; 33. Water washing unit; 34. Solvent tank; 35. Product tower. Detailed Implementation

[0018] To make the technical problems, technical solutions, and beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.

[0019] It should be noted that when a component is referred to as "connected to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0020] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" 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 mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0021] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0022] Throughout this specification, reference to "an embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of this application. Therefore, the phrases "in one embodiment," "in some embodiments," or "in some of these embodiments" appear in various places throughout the specification, and not all refer to the same embodiment. Furthermore, in one or more embodiments, a particular feature, structure, or characteristic may be combined in any suitable manner.

[0023] like Figure 1-2 As shown, this utility model provides a coupled system 100 for crude benzene hydrogenation and maleic anhydride preparation with tail gas recycling, including a crude benzene hydrogenation unit 1 and a maleic anhydride preparation unit 2.

[0024] In this embodiment, specifically, the crude benzene hydrogenation unit 1 includes a vacuum distillation tower 11, a hydrogenation reactor 12, a hydrogen refining unit 13, a pre-separation unit 14, an extraction unit 15, and a distillation tower 16. The vacuum distillation tower 11, hydrogenation reactor 12, pre-separation unit 14, extraction unit 15, and distillation tower 16 are connected sequentially via pipelines. After crude benzene enters the vacuum distillation tower 11, separation is achieved under reduced pressure by utilizing the differences in boiling points of the components. The heavier aromatics with higher boiling points are discharged from the bottom of the tower; the lighter benzene with lower boiling points is distilled from the top of the vacuum distillation tower 11 and enters the hydrogenation reactor 12. Fresh hydrogen and recycled hydrogen are mixed in the hydrogen refining unit 13 and then enter the hydrogenation reactor 12. The hydrogen provides a hydrogen source for subsequent hydrogenation reactions, causing unsaturated hydrocarbons and impurities containing sulfur, nitrogen, and oxygen in the lighter benzene to undergo hydrogenation saturation reactions. Light benzene undergoes hydrodesulfurization, hydrodenitrogenation, hydrodeoxygenation, and olefin hydrogenation saturation reactions under the action of a catalyst. After the reaction, impurities in the material are significantly removed, and the hydrocarbon components are purified. The material then enters the pre-separation unit 14. The pre-separation unit 14 separates the mixed xylenes through distillation as one of the products, while the remaining material enters the extraction unit 15. In the extraction unit 15, the difference in solubility of aromatic and non-aromatic hydrocarbons in the solvent is utilized to separate the non-aromatic hydrocarbons from the system, which are discharged as byproducts. The solvent phase containing dissolved benzene and toluene enters the distillation column 16. Because the boiling point of toluene is between that of benzene and pure benzene, the temperature and pressure of the distillation column are controlled to allow toluene to distill from a specific fraction of the column, while pure benzene is separated from the bottom of the column or in subsequent distillation sections.

[0025] In this embodiment, light benzene reacts with hydrogen to produce an acidic tail gas containing hydrogen sulfide. Therefore, hydrogen sulfide tail gas is generated in the hydrogenation reactor 13. In other embodiments, an absorption vessel (not shown) can be set at the end of the hydrogenation reactor 12. The absorption vessel contains a sodium hydroxide solution. The hydrogen sulfide tail gas is treated by the absorption vessel to remove hydrogen sulfide and generate sodium hydrosulfide, which is then stored or sold as a product, thus turning waste into treasure.

[0026] In this embodiment, specifically, the tail gas mainly produced by the crude benzene hydrogenation unit 1 consists of substances with high calorific value such as hydrogen, methane, and carbon monoxide, which can be used as fuel for energy supply.

[0027] In this embodiment, specifically, the maleic anhydride preparation unit 2 includes a butane vaporizer 21, a butane superheater 22, an air heater 23, a butane mixer 24, a reactor 25, an air cooling unit 26, an absorption tower 27, a TO furnace 28, a post-flash evaporation tower 31, a stripping tower 32, a water washing unit 33, a solvent tank 34, and a product tower 35. The butane mixer 24, reactor 25, air cooling unit 26, and absorption tower 27 are sequentially connected by pipelines. The butane vaporizer 21 is connected to the butane superheater 22, and the butane superheater 22 and air heater 23 are connected to the butane mixer 24. The absorption tower 27 is connected to the post-flash evaporation tower 31, which is further connected to the water washing unit 33 and the solvent tank 34. The solvent tank 34 is connected to the absorption tower 27. Butane first enters the butane vaporizer 21, where it vaporizes from a liquid state to a gaseous state. The gaseous butane then enters the butane superheater 22, where it is heated to the temperature required for the reaction, giving it sufficient reactivity. Meanwhile, air is heated in air heater 23, and humidifying steam at 0.4 MPa is introduced to provide adequate moisture and regulate the reaction environment. The heated and humidified air is then thoroughly mixed with superheated butane in butane mixer 24, along with a co-catalyst. The mixed butane, air, and co-catalyst enter reactor 25, where an oxidation reaction occurs under the action of the co-catalyst, releasing a large amount of heat. The high-temperature gas after the reaction enters air cooling unit 26 and is cooled to a temperature suitable for subsequent absorption operations. The cooled gas enters absorption tower 27, where a lean solvent is sprayed. Maleic anhydride is readily soluble in the lean solvent and is thus absorbed, resulting in a rich solvent. The unabsorbed tail gas is sent to TO furnace 28 for combustion treatment to prevent pollutant emissions and recover heat. The rich solvent first enters post-flash evaporation tower 31, where pressure is reduced or appropriate heating causes some low-boiling-point impurities dissolved in the rich solvent to flash out. The rich solvent, after being processed in flash distillation tower 31, enters stripping tower 32. In stripping tower 32, maleic anhydride is stripped from the solvent by heating, yielding crude anhydride. A portion of the stripped lean solvent is recycled back to the absorption tower, while the other portion enters the water washing unit 33 to remove trace impurities dissolved in the solvent. The treated lean solvent returns to solvent tank 34, completing the solvent cycle. The crude anhydride enters product tower 35, where high-purity maleic anhydride is separated through distillation.

[0028] In this embodiment, butane, after passing through butane vaporizer 21 and butane superheater 22, is mixed with air heated by air heater 23 in butane mixer 24. The mixed material enters reactor 25 for reaction, and the material cooled by air cooling unit 26 after reaction enters absorption tower 27. In absorption tower 27, maleic anhydride is absorbed by solvent, and tail gas containing organic matter and carbon monoxide is generated at the top of absorption tower 27. This tail gas is transported to combustion chamber 287 of TO furnace 28 through inlet 283. At the same time, fuel can be added to gas pipeline 29 as needed, and its flow rate is controlled by flow meter 291 and control valve 292.

[0029] In this embodiment, specifically, the exhaust gas composition of maleic anhydride preparation unit 2 is complex. When the feed is n-butane, the exhaust gas contains unreacted n-butane, maleic anhydride, organic acids, aldehydes and ketones, nitrogen, carbon dioxide, etc., which need to be treated before being discharged.

[0030] In this embodiment, specifically, the TO furnace 28 includes a furnace body 281, an air inlet 1 282, an air inlet 283, an air inlet pipe 284, an insulation layer 285, a preheating channel 286, a combustion chamber 287, an air outlet 288, an ignition device 289, and is also connected to a gas pipe 29, on which a flow meter 291 and a control valve 292 are installed. The insulation layer 285 is set on the inner wall of the furnace body 281. The preheating channel 286 is set inside the insulation layer 285 and is a loop channel. The combustion chamber 287 is set inside the preheating channel 286. The preheating channel 286 connects the first air inlet 282 and the combustion chamber 287. An air inlet pipe 284 is opened on the furnace body 281. The second air inlet 283 is set at the end of the furnace body 281 away from the air outlet 288. A partition 2861 is set between the preheating channels 286. The partition 2861 is set on the end of the furnace body 281 away from the air outlet 288. A gas distribution plate 2841 is set between the partitions 2861. The gas distribution plate 2841 is provided with through holes. An ignition device 289 is set at the outlet end of the second air inlet 283. The ignition device 289 is set on the side of the gas distribution plate 2841 near the air outlet 288.

[0031] In this embodiment, the crude benzene hydrogenation tail gas entering from inlet 282 is first preheated through preheating channel 286, and then combined with the maleic anhydride absorber tower 27 tail gas entering from inlet 283 and any supplementary fuel in combustion chamber 287. After ignition by ignition device 289, high-temperature combustion occurs. The high-temperature flue gas generated during combustion is discharged through outlet 288. The heat generated during combustion can be used to preheat the intake gas through preheating channel 286, achieving heat recycling. By setting flow meter 141, flow meter 291, and control valve 292, the flow rates of the crude benzene hydrogenation tail gas, the maleic anhydride absorber tower 27 tail gas, and the gas pipeline 29 can be precisely controlled, ensuring the stable and controllable combustion process within the TO furnace 28 and guaranteeing the safe and efficient operation of the entire system.

[0032] In some other embodiments, a thermometer for real-time monitoring is installed in the TO furnace 28, and the opening and closing of the control valve 292 is controlled by temperature sensing.

[0033] The working principle of the coupling system for the preparation of crude benzene hydrogenation and maleic anhydride with tail gas recycling in this utility model is as follows: The calorific value-bearing tail gas from the crude benzene hydrogenation process is fed into the TO furnace 28 for maleic anhydride preparation, where it undergoes a high-temperature combustion reaction with the tail gas from the maleic anhydride absorption tower 27 within the combustion chamber 287 of the TO furnace 28. The combustible components such as hydrocarbons and hydrogen in the crude benzene hydrogenation tail gas are used as energy sources, providing some of the energy required for combustion in the TO furnace 28, thus achieving energy utilization of the tail gas. Simultaneously, under the high-temperature combustion environment, pollutants such as organic matter and carbon monoxide in the maleic anhydride tail gas are oxidized into carbon dioxide and water, achieving environmental protection. Furthermore, the preheating channel 286 within the TO furnace 28 preheats the tail gas entering the combustion chamber 287, further improving combustion efficiency. The beneficial effects of this utility model on the coupling system for the preparation of crude benzene hydrogenation and maleic anhydride with tail gas recycling are as follows: 1. The tail gas rich in hydrocarbons and hydrogen generated by the hydrogen refining unit 14 is introduced into the TO furnace 28 for maleic anhydride preparation for combustion, which fully recovers the calorific value of the tail gas from the crude benzene hydrogenation process, replaces part of the external fuel consumption of the TO furnace 28, reduces the energy cost of the maleic anhydride preparation process, and avoids the energy waste caused by the direct emission of crude benzene hydrogenation tail gas.

[0034] 2. The tail gas from the crude benzene hydrogenation process is fully combusted in the TO furnace 28, where pollutants are oxidized and decomposed, reducing the environmental protection pressure on the tail gas of the crude benzene hydrogenation process. At the same time, the tail gas from the maleic anhydride preparation absorption tower 27 is also effectively treated in the TO furnace 28, ensuring that the tail gas of the entire combined system meets the emission standards and improving the overall environmental performance of the process.

[0035] 3. The preheating channel 286 inside the TO furnace can preheat the exhaust gas entering the combustion chamber 287, further improving combustion efficiency.

[0036] 4. By setting flow meter 141, flow meter 291 and control valve 292, the flow rates of crude benzene hydrogenation tail gas, maleic anhydride absorption tower 27 tail gas and gas pipeline 29 can be precisely controlled, ensuring the stable and controllable combustion process in TO furnace 28 and guaranteeing the safe and efficient operation of the entire system.

[0037] Based on the above-described preferred embodiments of this utility model, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the scope of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A coupled system for the preparation of crude benzene hydrogenation and maleic anhydride with tail gas recycling, characterized in that, The system includes a crude benzene hydrogenation unit (1) and a maleic anhydride preparation unit (2). The crude benzene hydrogenation unit (1) includes a hydrogen refining unit (13). The maleic anhydride preparation unit (2) includes an absorption tower (27) and a TO furnace (28). The TO furnace (28) includes an inlet 1 (282), an inlet 2 (283), and a combustion chamber (287). The tail gas in the hydrogen refining unit (13) is transported to the combustion chamber (287) through the inlet 1 (282). The tail gas in the absorption tower (27) is transported to the combustion chamber (287) through the inlet 2 (283).

2. The coupled system for the preparation of crude benzene hydrogenation and maleic anhydride with tail gas recycling as described in claim 1, characterized in that, The crude benzene hydrogenation unit (1) also includes a vacuum tower (11), a hydrogenation reactor (12), a pre-separation unit (14), an extraction unit (15), and a distillation column (16), which are connected in sequence by pipelines.

3. The coupled system for the preparation of crude benzene hydrogenation and maleic anhydride with tail gas recycling as described in claim 2, characterized in that, The second air inlet (283) is also connected to a gas pipe (29), on which a flow meter (291) and a control valve (292) are installed. The pre-separation unit (14) is connected to the pipeline inside the TO furnace (28) and a flow meter (141) is installed.

4. The coupled system for the preparation of crude benzene hydrogenation and maleic anhydride with tail gas recycling as described in claim 1, characterized in that, The TO furnace (28) includes a furnace body (281), an insulation layer (285) disposed on the inner wall of the furnace body (281), and an air outlet (288) opened on the furnace body (281). A preheating channel (286) is disposed inside the insulation layer (285), and a combustion chamber (287) is disposed inside the preheating channel (286).

5. The coupled system for the preparation of crude benzene hydrogenation and maleic anhydride with tail gas recycling according to claim 1, characterized in that, The preheating channel (286) is a loop channel, and the preheating channel (286) connects the air inlet (282) and the combustion chamber (287).

6. The coupled system for the preparation of crude benzene hydrogenation and maleic anhydride with tail gas recycling according to claim 4, characterized in that, An air inlet pipe (284) is provided on the furnace body (281), and an air inlet (283) is located at one end of the furnace body (281) away from the air outlet (288).

7. The coupled system for the preparation of crude benzene hydrogenation and maleic anhydride with tail gas recycling according to claim 4, characterized in that, A partition (2861) is provided between the preheating channels (286). The partition (2861) is located on the end of the furnace body (281) away from the gas outlet (288). A gas distribution plate (2841) is provided between the partitions (2861). The gas distribution plate (2841) has through holes.

8. The coupled system for the preparation of crude benzene hydrogenation and maleic anhydride with tail gas recycling according to claim 3, characterized in that, An ignition device (289) is provided at the outlet end of the second air inlet (283), and the ignition device (289) is located on the side of the air distribution plate (2841) near the air outlet (288).

9. The coupling system for the preparation of crude benzene hydrogenation and maleic anhydride with tail gas recycling according to claim 1, characterized in that, The maleic anhydride preparation unit (2) also includes a butane vaporizer (21), a butane superheater (22), an air heater (23), a butane mixer (24), a reactor (25), an air cooling unit (26), and an absorption tower (27). The butane mixer (24), the reactor (25), the air cooling unit (26), and the absorption tower (27) are connected in sequence by pipelines. The butane vaporizer (21) is connected to the butane superheater (22), and the butane superheater (22) and the air heater (23) are connected to the butane mixer (24).

10. The coupling system for the preparation of crude benzene hydrogenation and maleic anhydride with tail gas recycling according to claim 9, characterized in that, The maleic anhydride preparation unit (2) further includes a post-flash evaporation tower (31), a stripping tower (32), a water washing unit (33), a solvent tank (34), and a product tower (35). The absorption tower (27) is connected to the post-flash evaporation tower (31), and the post-flash evaporation tower (31) is connected to the water washing unit (33) and the solvent tank (34). The solvent tank (34) is connected to the absorption tower (27).

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