A moving bed low carbon alkane dehydrogenation system

Abstract

The present application provides a kind of mobile bed low carbon alkane dehydrogenation system, belong to low carbon alkane dehydrogenation technical field, solve the problem of complex structure in prior art mobile bed, olefin yield is low, reaction condition is complex, process is complex, investment cost is big.It includes first reactor, second reactor, third reactor, fourth reactor, reaction cyclone separator and quench tower, dehydrogenation system also includes first heating furnace and second heating furnace, first reactor, second reactor, third reactor and fourth reactor are connected with catalyst regeneration system.Low carbon alkane is heated and enters first reactor, second reactor, third reactor and fourth reactor in sequence to carry out reaction, to improve the yield of olefin, reaction product is sent to reaction cyclone separator, and reaction catalyst fine powder is separated out for recycling, gas is washed again in quench tower to obtain relatively clean reaction gas, the equipment used in the whole system is less and the process is simple, so the investment cost is smaller.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of low-carbon alkane dehydrogenation, and particularly relates to a mobile bed low-carbon alkane dehydrogenation system. BACKGROUND

[0002] Low-carbon alkane generally refers to alkane with carbon atom number less than or equal to 4, such as propane, isobutane and the like. Propane is an organic compound with chemical formula CH3CH2CH3, which is a colorless and odorless gas, slightly soluble in water, soluble in ethanol and diethyl ether, and stable in chemical properties and not easy to react chemically. The main use of propane is to make liquefied petroleum gas together with butane, and it is mainly used as fuel. Propane is also an important raw material for ethylene cracking. Propane gas-phase nitration is used to manufacture mixed nitro compounds, 1-nitropropane and 2-nitropropane, nitroethane and nitromethane. Nitropropane is a good solvent for vinyl and epoxy resin, and nitromethane is used as a racing fuel additive. Propane is widely used as a refrigerant in oil refining, chemical industry and natural gas processing operations. Propane is used as a lubricating oil fraction deasphalting solvent. When propane is used for extraction, asphalt is removed as extraction residue, and then propane is evaporated from the fraction from which the asphalt is removed to leave lubricating oil. Propane is catalytically dehydrogenated to produce propylene, which has been formed into an industry for many years and has developed rapidly. Isobutane, also known as 2-methylpropane, is an organic compound with chemical formula C4H10. It is a colorless and flammable gas at room temperature and normal pressure, slightly soluble in water, soluble in ethanol, diethyl ether and the like, and forms an explosive mixture with air. It mainly exists in natural gas, refinery gas and cracking gas, and is obtained by physical separation. It is mainly used for producing isooctane by alkylation with isobutene, as an octane number improver for gasoline, and also used as a refrigerant and for synthesizing isooctane, as an octane number improver for gasoline, and for producing isobutene, propylene, methacrylic acid and the like.

[0003] China is rich in propane reserves, and in recent years, the development of shale gas has further increased the production of propane. At present, the utilization of propane in China is mostly in the form of combustion for energy supply, which greatly reduces its utilization value. Converting propane into high-value-added products is one of the key technologies for improving the utilization efficiency of propane and realizing efficient utilization of carbon-based energy, and has broad practical prospects and huge economic benefits. Among the downstream products of propane, propylene is a very important chemical raw material, which can be used to produce high-value-added products such as polypropylene, acrylonitrile, propylene oxide, isopropyl alcohol, ethylene-propylene rubber, acetone, nylon 66 and ABS resin. Among them, polypropylene is widely used in people's daily life, making propylene the second largest chemical raw material after ethylene. From the development in recent years, the production of propylene in China has been rising, but it still cannot meet the demand of the downstream industry for propylene. It can be seen that the demand gap for propylene downstream in China in the future is very large, and the increasing demand for propylene and the large amount of propane produced as a byproduct of shale gas have brought opportunities for the development of propane dehydrogenation technology.

[0004] So far, a variety of processes have been developed for propane dehydrogenation, foreign PDH technologies include Oleflex process, Catofin process, STAR process, PDH process, etc., domestic PDH technologies include fixed bed SDH process, moving bed SPDH dehydrogenation process, ADHO process, etc., as shown in Table 1.

[0005] Table 1 Statistics of propane dehydrogenation process technology

[0006]

[0007] A variety of processes have also been developed for isobutane dehydrogenation, foreign technologies include STAR process, Catofin process, Oleflex process, FBD-4 process, Linde, etc., domestic isobutane technologies include ADHO process, etc., as shown in Table 2.

[0008] Table 2 Statistics of isobutane dehydrogenation process technology

[0009]

[0010] The above ten processes have been industrialized at this stage and are mainly used for propane and isobutane dehydrogenation, and the technology is relatively mature. Low-carbon alkane dehydrogenation technology refers to the preparation of target product olefin and by-product hydrogen by catalytic dehydrogenation of low-carbon alkane. The product composition is simple, easy to separate, and has good economic efficiency. The equipment investment is lower than that of hydrocarbon steam cracking, and the conversion rate is higher than that of hydrocarbon steam cracking. The total yield can reach 85% to 88%. The method of catalytic dehydrogenation can effectively utilize liquefied petroleum gas resources to convert them into useful olefins. The by-product hydrogen can be used in the field of new energy after purification, which is one of the important sources of hydrogen. The moving bed structure used in the existing low-carbon alkane dehydrogenation is complex, the olefin yield is low, the reaction conditions are complex, the process is complex, and the investment cost is high. SUMMARY

[0011] In view of the above problems, the purpose of the present application is to provide a moving bed low-carbon alkane dehydrogenation system. Low-carbon alkane is heated by a first heating furnace and enters a first reactor for reaction. The reaction products are heated and then enter a second reactor, a third reactor and a fourth reactor for further reaction to improve the yield of olefin. The reaction products in the fourth reactor are input into a reaction cyclone separator to separate and recover the reaction catalyst fines, thereby avoiding the blockage of the downstream pipeline by the reaction catalyst fines. The gas is cooled and washed in a quench tower to obtain relatively clean reaction gas. The reaction gas is finally transported to a rectification unit for separation and refining to obtain qualified olefin. The system uses less equipment and has a simple process, so the investment cost is relatively low. The used catalyst in the reactor is regenerated by a catalyst regeneration system for online cyclic use of the catalyst.

[0012] The technical scheme adopted by the present application is as follows:

[0013] A mobile bed low carbon alkane dehydrogenation system, comprising a first reactor, a second reactor, a third reactor, a fourth reactor, a reaction cyclone separator and a quench tower connected in sequence, the dehydrogenation system further comprising a first heating furnace for heating low carbon alkane and reaction products in the first reactor and a second heating furnace for heating reaction products in the second reactor and the third reactor, the first reactor, the second reactor, the third reactor and the fourth reactor being connected with a catalyst regeneration system.

[0014] Preferably, the first reactor, the second reactor, the third reactor and the fourth reactor are connected in sequence.

[0015] Preferably, a low carbon alkane heat exchanger is connected between the reaction cyclone separator and the quench tower.

[0016] Preferably, a low carbon alkane output port of the low carbon alkane heat exchanger is connected with the first heating furnace through a pipeline, and a low carbon alkane output port of the first heating furnace is connected with the first reactor through a pipeline.

[0017] Preferably, the first heating furnace is provided with upper heating pipes and lower heating pipes, the upper heating pipes are in communication with the low carbon alkane output port of the low carbon alkane heat exchanger, and the lower heating pipes are in communication with the reaction product pipeline of the first reactor, and the second heating furnace is provided with two groups of heating pipes at the same height, and the two groups of heating pipes are in communication with the reaction product pipelines of the second reactor and the third reactor, respectively.

[0018] Preferably, a hydrogen heat exchanger is connected between the low carbon alkane heat exchanger and the quench tower.

[0019] Preferably, a hydrogen output port of the hydrogen heat exchanger is connected with the first heating furnace and the second heating furnace through a pipeline, and the hydrogen output ports of the first heating furnace and the second heating furnace are in communication with the stripping sections of the first reactor, the second reactor, the third reactor and the fourth reactor through pipelines.

[0020] Preferably, the first reactor, the second reactor, the third reactor and the fourth reactor are provided with catalyst pipelines connected with the catalyst regeneration system at the bottom, and the catalyst pipelines are in communication with the hydrogen output ports of the first heating furnace and the second heating furnace.

[0021] Preferably, the catalyst regeneration system comprises a regenerator, the regenerator is connected in sequence with a regeneration cyclone separator, a steam generator, a flue gas dust collector and a chimney, the stripping section of the regenerator is in communication with the first reactor through a pipeline, and the regenerator is connected with a regenerator heat extractor.

[0022] Preferably, a reactor filter is arranged in each of the first reactor, the second reactor, the third reactor and the fourth reactor.

[0023] In summary, by adopting the technical scheme, the application has the following beneficial effects:

[0024] The low carbon alkane is heated by the first heating furnace and enters the first reactor for reaction, the reaction product is heated and then enters the second reactor, the third reactor and the fourth reactor for reaction again to improve the yield of the olefin, the reaction product in the fourth reactor is input into the reaction cyclone separator, the reaction catalyst fine powder is separated and recovered to avoid the reaction catalyst fine powder from blocking the downstream pipeline, the quench tower is used for cooling and washing the gas to obtain relatively clean reaction gas, and the reaction gas is finally transported to the rectification unit for separation and refining to obtain qualified olefin; the whole system uses less equipment and has simple process, so the investment cost is relatively low, the used catalyst in the reactor is regenerated by the catalyst regeneration system for regeneration treatment to realize the online circulation of the catalyst. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical scheme of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments, and it should be understood that the following drawings only show some embodiments of the application, and therefore should not be regarded as a limitation to the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of the drawings.

[0026] Figure 1 The dehydrogenation system process schematic diagram provided for the embodiments of the application;

[0027] Figure 2 Another catalyst feeding process schematic diagram provided for the embodiments of the application;

[0028] Figure 3 Another low carbon alkane feeding process schematic diagram provided for the embodiments of the application;

[0029] Figure 4 Another reactor parallel connection process schematic diagram provided for the embodiments of the application.

[0030] BRIEF DESCRIPTION OF DRAWINGS: 1-first reactor; 2-second reactor; 3-third reactor; 4-fourth reactor; 5-first heating furnace; 6-second heating furnace; 7-reaction cyclone separator; 8-low carbon alkane heat exchanger; 9-hydrogen heat exchanger; 10-quench tower; 11-regenerator; 12-regeneration cyclone separator; 13-steam generator; 14-flue gas dust collector; 15-chimney; 16-regenerator heat extractor; 17-main fan; 18-reactor filter. DETAILED DESCRIPTION

[0031] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative labor are within the scope of protection of the present application.

[0033] In the description of the present application, it should be noted that if the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship of the product of the application when it is usually placed, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0034] The following will be described in detail Figures 1-4 The present application will be described in detail.

[0035] Embodiments

[0036] A mobile bed low-carbon alkane dehydrogenation system, comprising a first reactor 1, a second reactor 2, a third reactor 3, a fourth reactor 4, a reaction cyclone 7 and a quench tower 10 connected in sequence, the dehydrogenation system further comprising a first heating furnace 5 for heating low-carbon alkane and reaction products in the first reactor 1 and a second heating furnace 6 for heating reaction products in the second reactor 2 and the third reactor 3, and the first reactor 1, the second reactor 2, the third reactor 3 and the fourth reactor 4 are connected with a catalyst regeneration system.

[0037] The first reactor 1, the second reactor 2, the third reactor 3 and the fourth reactor 4 can be connected in series or in parallel; for example, Figure 4The diagram shows a parallel reactor configuration. Low-carbon alkanes enter the first reactor (1), and the reaction products then flow into the second reactor (2), the third reactor (3), and the fourth reactor (4). The reaction products from the second reactor (2) then flow into the third reactor (3) and the fourth reactor (4), and vice versa. This connection method, combined with appropriate valves, allows for the individual shutdown of one reactor for maintenance, or the switching to a series connection. The system is highly flexible, easily adjustable, and its operating time fully meets any maintenance cycle. Reactors can be switched for maintenance, enabling long-term system operation. Maintenance of any reactor (≤3 units) or any heater will not affect system operation.

[0038] like Figure 1 As shown, reactors 1, 2, 3, and 4 are connected in series. Low-carbon alkanes are heated by the first heater 5 and then enter reactor 1 for reaction. The reaction products are then heated by the first heater 5 and enter reactor 2 for further reaction. The reaction products are then heated by the second heater 6 and enter reactor 3 for further reaction. The reaction products are then heated by the second heater 6 and enter reactor 4 for further reaction. The reaction products from reactor 4 are fed into a reaction cyclone separator 7 to separate and recover the fine catalyst powder. A quench tower 10 further cools and washes the gas to obtain a relatively clean reaction gas and lower its temperature. Finally, the reaction gas at a suitable temperature is sent to the downstream separation unit for further separation. With four reactors connected in series, the conversion rate of low-carbon alkanes is >99%, the olefin selectivity is 90-95%, the reaction operation is highly flexible, the processing load is large, the reaction conditions are easy to control, and the production is stable.

[0039] like Figure 3 As shown, low-carbon alkanes can also enter the four reactors separately to participate in the reaction, instead of entering the four reactors sequentially.

[0040] To reduce the generation of side reactions, the temperature and pressure of the reactors need to be controlled. Specifically, the temperature of the first reactor 1 is 550–600℃ and the reaction pressure is 0.2–0.3 MPa; the temperature of the second reactor 2 is 570–630℃ and the reaction pressure is 0.15–0.2 MPa; the temperature of the third reactor 3 is 590–640℃ and the reaction pressure is 0.1–0.15 MPa; and the temperature of the fourth reactor 4 is 590–630℃ and the reaction pressure is 0.03–0.1 MPa.

[0041] A low-carbon alkane heat exchanger 8 is connected between the reaction cyclone separator 7 and the quenching tower 10, a low-carbon alkane output port of the low-carbon alkane heat exchanger 8 is connected with the first heating furnace 5 through a pipeline, and a low-carbon alkane output port of the first heating furnace 5 is connected with the first reactor 1 through a pipeline. The heat exchange medium of the low-carbon alkane heat exchanger 8 is low-carbon alkane, the heat in the reaction gas is exchanged to the low-carbon alkane, the low-carbon alkane is preliminarily heated, the energy consumption of the subsequent heating furnace can be reduced, and the operation load of the quenching tower 10 can also be reduced.

[0042] The first heating furnace 5 is provided with upper heating pipes and lower heating pipes, the upper heating pipes are communicated with the low-carbon alkane output port of the low-carbon alkane heat exchanger 8, and the lower heating pipes are communicated with the reaction product pipeline of the first reactor 1. The second heating furnace 6 is provided with two groups of heating pipes at the same height, and the two groups of heating pipes are respectively communicated with the reaction product pipelines of the second reactor 2 and the third reactor 3. Since the temperature of the second reactor 2 is higher than that of the first reactor 1, the temperature of the upper heating pipes of the first heating furnace 5 is low for heating the low-carbon alkane, and the temperature of the lower heating pipes is high for heating the reaction product of the first reactor 1. Since the temperature of the third reactor 3 is close to that of the fourth reactor 4, the two heating pipes of the second heating furnace 6 are at the same height to ensure the same temperature, fully utilize the heat sources of the first heating furnace 5 and the second heating furnace 6, save energy and reduce consumption, and reduce production cost. The pipeline length from the heating furnace to the reactor is as short as possible, the purpose is to reduce the residence time of the reaction product in the catalyst-free area, reduce the occurrence of thermal cracking and other side reactions, and improve the reaction yield.

[0043] A hydrogen heat exchanger 9 is connected between the low-carbon alkane heat exchanger 8 and the quenching tower 10, a hydrogen output port of the hydrogen heat exchanger 9 is connected with the first heating furnace 5 and the second heating furnace 6 through a pipeline, and the hydrogen output ports of the first heating furnace 5 and the second heating furnace 6 are connected with the stripping sections of the first reactor 1, the second reactor 2, the third reactor 3 and the fourth reactor 4 through pipelines. The low-carbon alkane dehydrogenation reactor is an endothermic reaction, in order to ensure the temperature in the reactor, the hydrogen in the stripping section of the reactor needs to be heated, the heat exchange medium of the hydrogen heat exchanger 9 is hydrogen, the heat in the reaction gas is exchanged to the hydrogen, the hydrogen is preliminarily heated, the energy consumption of the subsequent heating furnace can be reduced, and the operation load of the quenching tower 10 can also be reduced. The pipelines for heating hydrogen in the first heating furnace 5 and the second heating furnace 6 are arranged at the top of the heating furnace, the hydrogen heating pipelines in the two heating furnaces are arranged in parallel, the layout is reasonable, the heat source is fully utilized, energy is saved and consumption is reduced, and production cost is reduced. The heated hydrogen is used for stripping the catalyst in the four reactors, the hydrogen is used for stripping the products and organic matters carried by the catalyst, the stripping effect is obvious, and the yield is improved.

[0044] The bottom of the first reactor 1, the second reactor 2, the third reactor 3 and the fourth reactor 4 is provided with a catalyst pipeline connected with the catalyst regeneration system, and the catalyst pipeline is communicated with the hydrogen output port of the first heating furnace 5 and the second heating furnace 6. Hydrogen is used to transport the catalyst to avoid the catalyst from blocking the pipeline. As shown in Figure 1 , the catalyst after stripping in the first reactor 1 is re-entered into the second reactor 2 for reuse, the catalyst in the second reactor 2 is re-entered into the third reactor 3 for reuse, the catalyst in the third reactor 3 is re-entered into the fourth reactor 4 for reuse, and finally the catalyst is transported into the regenerator 11. As shown in Figure 2 , the catalyst after use in each reactor is directly transported into the regenerator 11. Alternatively, as shown in Figure 4 , the catalyst is reacted into the first reactor 1 and discharged from the bottom, and the used catalyst is respectively introduced into the second reactor 2, the third reactor 3 and the fourth reactor 4, the used catalyst in the second reactor 2 is respectively introduced into the third reactor 3 and the fourth reactor 4, and the used catalyst in the third reactor 3 is introduced into the fourth reactor 4.

[0045] The catalyst regeneration system comprises a regenerator 11, and the regenerator 11 is sequentially connected with a regeneration cyclone 12, a steam generator 13, a flue gas dust remover 14 and a chimney 15. The stripping section of the regenerator 11 is communicated with the first reactor 1 through a pipeline, and the regenerator 11 is connected with a regenerator heat extractor 16. The regeneration cyclone 12 separates and recycles the regenerated catalyst fine powder carried in the flue gas, ensures that the downstream steam generator is not blocked, reduces the equipment maintenance frequency, and has obvious steam production effect and reduces energy consumption. The flue gas re-enters the low-pressure steam in the steam generator 13 to reduce the temperature of the flue gas. Then, the flue gas enters the flue gas dust remover 14 to remove the fine powder catalyst carried in the flue gas, and finally the gas is discharged from the chimney 15. The regenerator heat extractor 16 recovers the heat in the regenerator 11 to produce steam, and the flue gas system is provided with a steam generator to produce steam, so that the comprehensive energy consumption is reduced and the production cost is low. The regenerator 11 is also connected with a main air blower 17, and the main air blower 17 transports air into the regenerator 11 to provide air for catalyst coking.

[0046] The first reactor 1, the second reactor 2, the third reactor 3 and the fourth reactor 4 are all provided with a reactor filter 18. The reactor filter 18 filters the catalyst in the reaction product to reduce the content of the catalyst carried by the reaction product.

[0047] The dehydrogenation system has high flexibility and can be used for butane dehydrogenation reaction, has wide application range, large operation flexibility and controllable load of 80-150%, and completely has a large-scale production system.

[0048] The reaction produced in the reactor is as follows:

[0049] (1) Main reaction:

[0050] Propane dehydrogenation: CH3-CH2-CH3→ CH3-CH=CH2+ H2

[0051] Isobutane dehydrogenation: i-C4H 10 → i-C4H8+ H2

[0052] (2) Propane dehydrogenation side reactions:

[0053] ① CH3-CH2-CH3→ CH2=CH=CH2+ 2H2

[0054] ② CH3-CH2-CH3→ CH3-C≡CH + 2H2

[0055] ③ CH3-CH2-CH3+ H2→ CH3-CH3+ CH4

[0056] ④ CH3-CH2-CH3→ CH2-CH2+ CH4

[0057] (3) Isobutane dehydrogenation side reactions:

[0058] ① C4H8+ H2→ C3H6+ CH4

[0059] ② C3H6+ H2→ C3H8

[0060] ③ C3H6+ H2→ C2H4+ CH4

[0061] ④ C2H4+ H2→ C2H6

[0062] The main reaction of propane dehydrogenation is the production of propylene from propane, although the desired product is a mono-olefin, the high temperature and low pressure process conditions can lead to the production of some di-olefins, such as reactions ① and ② in (2); cracking reactions can also occur in the feedstock alkanes or olefins, such as reactions ③ and ④ in (2), although other side reactions such as isomerization are also possible, but the Rezel-MXB dehydrogenation catalyst used in the present application minimizes the possibility of these reactions, the selectivity of the single-pass propane dehydrogenation to produce propylene is > 90%, and the conversion rate is 30-40%.

[0063] The main reaction of isobutane dehydrogenation is the production of isobutene from isobutane, and there are other side reactions, such as the isobutene produced in reactions ①-④ in (3) is prone to hydrogenolysis in the presence of hydrogen to produce propylene and methane, and the propylene is further hydrogenolyzed to produce propane, ethylene, ethane and methane and other by-products, in addition to the above-mentioned side reactions, isobutane is prone to polymerization and the production of aromatic by-products during dehydrogenation, but the Rezel-MXB dehydrogenation catalyst used in the present application minimizes the possibility of these reactions, the selectivity of the single-pass isobutane dehydrogenation to produce isobutene is > 90%, and the conversion rate is 30-40%.

[0064] The Rezel-MXB catalyst has a large specific surface, high activity, good stability, low carbon deposition rate, and good chlorine holding and regeneration performance. The physical and chemical indexes of the Rezel-MXB catalyst are shown in Table 3.

[0065] Table 3 Physical and chemical indexes of Rezel-MXB catalyst

[0066] Item Indicator Appearance Spherical Size, mm 1.7～2.0 Crushing strength, N / grain ＞25 Low carbon alkane conversion, % ≥30 Olefin selectivity, % ≥90 Bulk density, g / cm 3 ]] ＞0.7

[0067] The effect of the number of reactors on the conversion rate and yield was tested as follows:

[0068] Experiment 1:

[0069] Four 70L reactors, each containing 50kg of Rezel-MXB catalyst, were used to feed 100kg / h of propane / isobutane. The first reactor had a temperature of 550-600°C and a reaction pressure of 0.2-0.3MPa; the second reactor had a temperature of 570-630°C and a reaction pressure of 0.15-0.2MPa; the third reactor had a temperature of 590-640°C and a reaction pressure of 0.1-0.15MPa; and the fourth reactor had a temperature of 590-630°C and a reaction pressure of 0.03-0.1MPa. The reaction results are shown in Table 4.

[0070] Table 4 Experimental data of Experiment 1 (Note: the reaction pressure is gauge pressure)

[0071]

[0072] Experiment 2:

[0073] The three remaining reactors were used to feed 100kg / h of propane / isobutane. The first reactor had a temperature of 550-600°C and a reaction pressure of 0.15-0.2MPa; the second reactor had a temperature of 570-630°C and a reaction pressure of 0.1-0.15MPa; and the third reactor had a temperature of 590-640°C and a reaction pressure of 0.03-0.1MPa. The reaction results are shown in Table 5.

[0074] Table 5 Experimental data of Experiment 2 (Note: the reaction pressure is gauge pressure)

[0075]

[0076] Experiment 3:

[0077] Four reactors are cut out for maintenance, and the remaining two reactors are used for reaction, each of which is loaded with 50 kg of Rezel-MXB catalyst, and the feed of propane / isobutane is 100 kg / h. The temperature of the No. 1 reactor is 550-600℃, and the reaction pressure is 0.1-0.15 MPa; the temperature of the No. 2 reactor is 570-630℃, and the reaction pressure is 0.03-0.1 MPa. The reaction results are shown in Table 6.

[0078] Table 6: Data table of the results of Experiment 3 (Note: the reaction pressure is gauge pressure)

[0079]

[0080] Experiment 4:

[0081] Three of the four reactors are cut out for maintenance, and the remaining one reactor is used for reaction, which is loaded with 50 kg of Rezel-MXB catalyst, and the feed of propane / isobutane is 100 kg / h. The temperature of the reactor is 550-600℃, and the reaction pressure is 0.03-0.1 MPa. The reaction results are shown in Table 7.

[0082] Table 7: Data table of the results of Experiment 4 (Note: the reaction pressure is gauge pressure)

[0083]

[0084] The comparison of the results of the above four experiments is shown in Table 8.

[0085] Table 8: Comparison table of the results of the experiments

[0086] Example Reactor / number Conversion / % Yield / % Experiment 1 4 ＞99 90～95 Experiment 2 3 80～95 90～95 Experiment 3 2 60～80 90～95 Experiment 4 1 30～40 ＞90％

[0087] It is found by comparison that the more the number of reactors in operation, the higher the conversion rate of propane / isobutane, and the yield is almost not affected.

[0088] The above only describes the preferred embodiments of the present application and is not used to limit the present application. The present application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A moving bed low carbon alkane dehydrogenation system, characterized in that, The dehydrogenation system comprises a first reactor (1), a second reactor (2), a third reactor (3), a fourth reactor (4), a reaction cyclone (7) and a quench tower (10) connected in sequence, and further comprises a first heating furnace (5) for heating low-carbon alkane and reaction products in the first reactor (1) and a second heating furnace (6) for heating reaction products in the second reactor (2) and the third reactor (3), the first reactor (1), the second reactor (2), the third reactor (3) and the fourth reactor (4) are connected with a catalyst regeneration system, a low-carbon alkane heat exchanger (8) is connected between the reaction cyclone (7) and the quench tower (10), the first heating furnace (5) is provided with upper heating pipes and lower heating pipes, the upper heating pipes are communicated with a low-carbon alkane outlet of the low-carbon alkane heat exchanger (8), and the lower heating pipes are communicated with a reaction product pipeline of the first reactor (1), the second heating furnace (6) is provided with two groups of heating pipes at the same height, and the two groups of heating pipes are respectively communicated with reaction product pipelines of the second reactor (2) and the third reactor (3).

2. A moving bed low carbon alkane dehydrogenation system according to claim 1, wherein, The first reactor (1), the second reactor (2), the third reactor (3) and the fourth reactor (4) are connected in sequence.

3. The moving bed low carbon alkane dehydrogenation system of claim 1, wherein, The low-carbon alkane outlet of the low-carbon alkane heat exchanger (8) is connected with the first heating furnace (5) through a pipeline, and the low-carbon alkane outlet of the first heating furnace (5) is connected with the first reactor (1) through a pipeline.

4. The moving bed low carbon alkane dehydrogenation system of claim 1, wherein, A hydrogen heat exchanger (9) is connected between the low-carbon alkane heat exchanger (8) and the quench tower (10).

5. A moving bed low carbon alkane dehydrogenation system according to claim 4, wherein, A hydrogen outlet of the hydrogen heat exchanger (9) is connected with the first heating furnace (5) and the second heating furnace (6) through a pipeline, and the hydrogen outlets of the first heating furnace (5) and the second heating furnace (6) are connected with stripping sections of the first reactor (1), the second reactor (2), the third reactor (3) and the fourth reactor (4) through pipelines.

6. A moving bed low carbon alkane dehydrogenation system according to claim 5, wherein, The bottom of each of the first reactor (1), the second reactor (2), the third reactor (3) and the fourth reactor (4) is provided with a catalyst pipeline connected with the catalyst regeneration system, and the catalyst pipeline is communicated with the hydrogen outlets of the first heating furnace (5) and the second heating furnace (6).

7. The moving bed low carbon alkane dehydrogenation system of claim 1, wherein, The catalyst regeneration system comprises a regenerator (11) connected with a regeneration cyclone (12), a steam generator (13), a flue gas dust collector (14) and a chimney (15) in sequence, a stripping section of the regenerator (11) is communicated with the first reactor (1) through a pipeline, and the regenerator (11) is connected with a regenerator heat extractor (16).

8. The moving bed low carbon alkane dehydrogenation system of claim 1, wherein, Each of the first reactor (1), the second reactor (2), the third reactor (3) and the fourth reactor (4) is provided with a reactor filter (18).

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