A method and system for continuous reforming reaction of naphtha in a moving bed

Abstract

The present disclosure relates to a method and system for naphtha moving bed continuous reforming reaction, the method comprising: sequentially feeding naphtha into a naphthene dehydrogenation reaction zone and a paraffin dehydrogenation cyclization reaction zone in series to react with catalysts, wherein each reaction zone comprises a plurality of reactors in series; feeding the catalysts out of the last reactor in the naphthene dehydrogenation reaction zone into a regeneration zone for regeneration; feeding the regenerated catalysts from the regenerator into the first reactor of the paraffin dehydrogenation cyclization reaction zone, and then sequentially flowing through the remaining reactors of the paraffin dehydrogenation cyclization reaction zone; and feeding the catalysts out of the paraffin dehydrogenation cyclization reaction zone into the first reactor of the naphthene dehydrogenation reaction zone, and then sequentially flowing through the remaining reactors of the naphthene dehydrogenation reaction zone. Compared with conventional countercurrent or cocurrent moving bed continuous reforming reaction, the present disclosure can reduce the carbon deposition of catalysts in the reaction system, and improve the liquid yield and aromatic yield.

Description

Technical Field

[0001] This disclosure relates to the field of petrochemical technology, and more specifically, to a method and system for continuous reforming reaction of naphtha in a moving bed. Background Technology

[0002] Catalytic reforming is a crucial petroleum refining process. It provides high-octane, clean gasoline components for blending, hydrogen for hydrotreating processes to improve feedstock properties, and aromatics for chemical production, thus playing an increasingly important role in refineries. Continuous reforming, with its ability to continuously regenerate catalysts, maintain peak catalyst activity over extended periods, and offer high liquid and aromatic yields, is gradually replacing semi-regenerative reforming as the dominant process.

[0003] In traditional cocurrent continuous reforming processes, the catalyst flow direction between reactors is the same as the reactant flow direction. Reactions that are easier to occur come into contact with highly active catalysts, while reactions that are more difficult to occur come into contact with less active catalysts, resulting in a mismatch between catalyst activity and reaction difficulty. Countercurrent continuous reforming aims to solve this problem, allowing the catalyst in each reactor to fully exert its activity. However, in existing countercurrent continuous reforming processes, the freshly regenerated catalyst first enters the last reactor, contacting the product from the penultimate reactor. Due to its strong metallic and acidic properties, and the generation of a large amount of high-dry-point components and coking precursors in the penultimate reactor, the catalyst reacts rapidly with these components, leading to coking. This causes a sharp increase in catalyst coking in the last reactor, which in turn affects the catalyst activity in the penultimate reactor and so on until the first reactor. This not only reduces product yield and selectivity but also impacts the catalyst regeneration operation.

[0004] CN1247886A discloses a multi-reactor countercurrent moving bed catalytic conversion process. The reactants flow sequentially from the first reactor, then the second reactor, until the final reactor completes the entire reaction. The regenerated fresh catalyst first enters the final reactor, then flows in reverse order until it reaches the first reactor. The catalyst exiting the first reactor, due to excessive carbon buildup and low activity, is sent to a regenerator for regeneration. The regenerated catalyst then returns to the final reactor, forming a catalyst cycle.

[0005] CN102295954A discloses a countercurrent moving bed reforming process apparatus and its catalyst delivery method. The catalyst flows in the opposite direction to the reaction stream between reactors, and is continuously delivered from the low-pressure reactor to the high-pressure reactor under a reverse pressure differential. Each reactor has a buffer hopper and an upper hopper at its top; the buffer hopper is higher than the upper hopper, and a catalyst sealing leg with a length of 10-30 meters connects the buffer hopper and the upper hopper. The pressure in the buffer hopper is lower than that in the upper hopper, and the pressure in the upper hopper is slightly higher than that in the reactor stage. Hydrogen is injected into the upper hopper, flowing downwards into the reactor to prevent the reaction stream from flowing into the upper hopper, and also flowing upwards through the catalyst sealing leg into the buffer hopper to provide the reverse pressure differential from the buffer hopper to the upper hopper.

[0006] CN1286950C discloses a mixed-flow catalytic reforming process using multiple moving bed reactors. The feedstock oil flows sequentially from the first moving bed reactor to the last moving bed reactor, where it contacts the reforming catalyst in each reactor. The reformed oil is then separated in a subsequent separation device. The catalyst to be generated in the second moving bed reactor is regenerated and then flows sequentially to the first moving bed reactor, the last moving bed reactor, the penultimate moving bed reactor, ..., the second moving bed reactor.

[0007] CN114456830A discloses a countercurrent moving bed continuous reforming method for naphtha. Naphtha is introduced into the reaction zone of a moving bed continuous reforming reactor containing multiple reactors connected in series, where it contacts a reforming catalyst for reforming. The spent catalyst flowing from the first reactor is conveyed to the catalyst regeneration zone of the moving bed continuous reforming reactor. It first undergoes coking, oxychlorination, and roasting in the regenerator of the regeneration zone, and then is reduced with hydrogen in the reducer of the regeneration zone. The regenerated catalyst obtained after reduction flows sequentially from the last reactor into multiple reactors connected in series in the opposite direction to the flow of the reactants, until it enters the first reactor. A pre-passivating agent is injected into the reducer or the catalyst delivery pipe below the reducer in the catalyst regeneration zone to reduce the degree of hydrocracking reaction of the catalyst loaded in the last reactor of the countercurrent continuous reforming method, thereby improving the liquid yield and aromatics yield of the countercurrent continuous reforming under high-severity conditions. Summary of the Invention

[0008] The purpose of this disclosure is to provide a method and system for continuous reforming of naphtha in a moving bed. Compared with traditional countercurrent or cocurrent moving bed continuous reforming methods, the method of this disclosure can reduce catalyst coking in the reaction system and improve liquid yield and aromatics yield.

[0009] To achieve the above objectives, the first aspect of this disclosure provides a method for continuous reforming reaction of naphtha in a moving bed, the method comprising: sequentially feeding naphtha into a cycloalkane dehydrogenation reaction zone and an alkane dehydrogenation cyclization reaction zone connected in series to react with a catalyst, wherein each reaction zone comprises multiple reactors connected in series.

[0010] The catalyst flowing out of the last reactor in the cycloalkane dehydrogenation reaction zone is then regenerated in the regeneration zone.

[0011] The regenerated catalyst from the regenerator is fed into the first reactor of the alkane dehydrogenation cyclization reaction zone, and then flows sequentially through the remaining reactors of the alkane dehydrogenation cyclization reaction zone; the catalyst flowing out of the alkane dehydrogenation cyclization reaction zone is fed into the first reactor of the cycloalkane dehydrogenation reaction zone, and then flows sequentially through the remaining reactors of the cycloalkane dehydrogenation reaction zone.

[0012] Optionally, each reaction zone includes 2 to 3 reactors connected in series from top to bottom.

[0013] Optionally, each reaction zone includes two reactors connected in series from top to bottom;

[0014] The method includes: heating naphtha and then sequentially entering a first reactor and a second reactor connected in series to undergo a cycloalkane dehydrogenation reaction to obtain a second product; heating the second product and then sequentially entering a third reactor and a fourth reactor to undergo an alkane dehydrogenation cyclization reaction.

[0015] The regenerated catalyst is first introduced into the third reactor, where it contacts the second product to undergo the alkane dehydrogenation cyclization reaction, and then exits as a three-stage catalyst. Under gravity, the three-stage catalyst enters the fourth reactor to undergo the alkane dehydrogenation cyclization reaction, and then exits as a four-stage catalyst. The four-stage catalyst is then pressurized and introduced into the first reactor to undergo the cycloalkane dehydrogenation reaction, and exits as a one-stage catalyst. Under gravity, the one-stage catalyst enters the second reactor to undergo the cycloalkane dehydrogenation reaction, yielding the regenerated catalyst.

[0016] The catalyst to be generated is then introduced into the regeneration zone for catalyst regeneration.

[0017] Optionally, the temperature of each reactor is 450-550°C, preferably 480-540°C.

[0018] Optionally, the pressures of the first reactor, the second reactor, the third reactor, and the fourth reactor decrease sequentially.

[0019] Optionally, the inlet pressure of the first reactor is 0.35-0.80 MPa, preferably 0.40-0.55 MPa;

[0020] The inlet pressure of the second reactor is 0.30-0.75 MPa, preferably 0.35-0.50 MPa;

[0021] The inlet pressure of the third reactor is 0.25-0.70 MPa, preferably 0.30-0.45 MPa;

[0022] The inlet pressure of the fourth reactor is 0.20-0.65 MPa, preferably 0.25-0.40 MPa.

[0023] Optionally, the method further includes: providing a control zone between the fourth reactor and the first reactor; the control zone is provided with a pressure conversion and flow control hopper for pressurizing the catalyst from the fourth reactor to the pressure of the first reactor before it enters the first reactor.

[0024] Optionally, the control zone includes a low-pressure zone, a transformer zone, and a high-pressure zone. The pressure in the low-pressure zone is 0.20-0.65 MPa, preferably 0.25-0.40 MPa; the pressure in the high-pressure zone is 0.35-0.80 MPa, preferably 0.45-0.65 MPa.

[0025] Optionally, the regeneration zone includes a regenerator and a reduction tank; the pressure of the regenerator is between that of the second reactor and the third reactor; the reduction tank is located above the third reactor, and the catalyst used to regenerate the regenerator is reduced and then enters the third reactor by gravity.

[0026] Optionally, the pressure of the regenerator is 0.25-0.75 MPa, preferably 0.35-0.45 MPa.

[0027] Optionally, in the cycloalkane dehydrogenation reaction zone, the total conversion rate of cycloalkane components in naphtha is above 70%, and the total conversion rate of alkane components is below 25%; in the alkane dehydrogenation cyclization reaction zone, the total conversion rate of alkane components in naphtha is above 55%, and the total conversion rate of cycloalkane components is below 25%.

[0028] A second aspect of this disclosure provides a system for continuous reforming reaction of naphtha in a moving bed, the system comprising a reaction zone and a regeneration zone, the reaction zone comprising a cycloalkane dehydrogenation reaction zone and an alkane dehydrogenation cyclization reaction zone connected in sequence, the reactant outlet of the cycloalkane dehydrogenation reaction zone being connected to the reactant inlet of the alkane dehydrogenation cyclization reaction zone; each reaction zone comprising multiple reactors connected in series from top to bottom;

[0029] The regeneration zone includes a regenerator and a reduction tank; the reduction tank is located above the first reactor in the alkane dehydrogenation cyclization reaction zone; a first hydrogen booster line connects the catalyst outlet of the regenerator to the catalyst inlet of the reduction tank; the catalyst outlet of the reduction tank is connected to the catalyst inlet of the first reactor in the alkane dehydrogenation cyclization reaction zone; a second hydrogen booster line connects the catalyst outlet of the last reactor in the alkane dehydrogenation cyclization reaction zone to the catalyst inlet of the first reactor in the cycloalkane dehydrogenation reaction zone; and a nitrogen booster line connects the catalyst outlet of the last reactor in the cycloalkane dehydrogenation reaction zone to the catalyst inlet of the regenerator.

[0030] Optionally, the system further includes a control area, which is equipped with a pressure conversion and flow control hopper;

[0031] The control zone is located between the last reactor of the alkane dehydrogenation cyclization reaction zone and the first reactor of the cycloalkane dehydrogenation reaction zone, and is used to pressurize the catalyst from the last reactor of the alkane dehydrogenation cyclization reaction zone to the pressure of the first reactor of the cycloalkane dehydrogenation reaction zone before it enters the first reactor.

[0032] Optionally, in the cycloalkane dehydrogenation reaction zone, the total conversion rate of cycloalkane components in the naphtha is above 70%, and the total conversion rate of alkane components is below 25%; in the alkane dehydrogenation cyclization reaction zone, the total conversion rate of alkane components in the naphtha is above 55%, and the total conversion rate of cycloalkane components is below 25%.

[0033] Through the above technical solution, this disclosure improves the reaction process of the regenerated catalyst, utilizing the reaction characteristics that cycloalkane dehydrogenation produces less high-dry-point components and coking precursors, while alkane dehydrogenation cyclization produces more. The fresh regenerated catalyst first contacts the products from the cycloalkane dehydrogenation reaction to carry out the alkane dehydrogenation cyclization reaction. Compared to countercurrent or cocurrent moving bed continuous reforming reactions, the amount of coking on the catalyst in the entire system is reduced. Simultaneously, the catalyst is "passivated" in the first reactor of the alkane dehydrogenation cyclization reaction, allowing the catalyst to maintain high reactivity for the cycloalkane dehydrogenation reaction. This results in a better match between catalyst activity and reaction difficulty, further improving the reaction efficiency of alkane dehydrogenation cyclization and increasing liquid yield and aromatics yield. Compared to countercurrent or cocurrent moving bed continuous reforming reactions, the method of this disclosure reduces the amount of coking on the catalyst in the reaction system while simultaneously increasing liquid yield and aromatics yield.

[0034] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0035] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0036] Figure 1 This is a schematic diagram of the continuous reforming reaction in Embodiment 1 of this disclosure.

[0037] Figure 2 This is a schematic diagram of the continuous reforming reaction in Comparative Example 1 of this disclosure.

[0038] Explanation of reference numerals in the attached figures

[0039] Figure 1 In the diagram, 2-1: First reactor; 2-2: Second reactor; 2-3: Third reactor; 2-4: Fourth reactor; 2-5: Regenerator; 202: Heating furnace I; 204: Heating furnace II; 206: Heating furnace III; 208: Heating furnace IV; 210: Lower hopper of regenerator; 211: Lifting pipeline; 212: Reduction tank; 213: Buffer hopper; 214: Pressure conversion and flow control hopper; 215: Lower hopper; 216: Lifting pipeline; 217: Upper hopper; 218: Lower hopper; 219: Lifting pipeline III; 220: Separation hopper; 201, 203, 205, 207, 209, N2, and H2 are all pipelines.

[0040] Figure 2 In the middle, 102: Heating furnace I'; 105: Heating furnace II'; 108: Heating furnace III'; 111: Heating furnace IV'; 114: Lower hopper of regenerator; 115: Lifting pipeline I'; 116: Buffer hopper I'; 118: Reduction tank I'; 119: Lower hopper I'; 120: Lifting pipeline II'; 121: Buffer hopper II'; 122: Material leg I'; 123: Upper hopper I'; 124: Lower hopper II'; 125: Lifting pipeline III'; 126: Buffer hopper III'; 127: Material leg II'; 128: Upper hopper II'; 129: Lower... 130: Hopper III'; 131: Lifting Pipeline IV'; 132: Buffer Hopper IV'; 133: Upper Hopper III'; 134: Lower Hopper IV'; 135: Lifting Pipeline V'; 136: Separation Hopper I'; 137: Metering Tank I'; 1-1: First Reactor I'; 1-2: Second Reactor I'; 1-3: Third Reactor I'; 1-4: Fourth Reactor I'; 1-5: Regenerator I'; 101, 103, 104, 106, 107, 109, 110, 112, 113, 117, N1, and H1 are all pipelines. Detailed Implementation

[0041] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0042] The first aspect of this disclosure provides a method for continuous reforming of naphtha in a moving bed, the method comprising: sequentially feeding naphtha into a cycloalkane dehydrogenation reaction zone and an alkane dehydrogenation cyclization reaction zone connected in series to react with a catalyst, wherein each reaction zone includes multiple reactors connected in series.

[0043] The catalyst flowing out of the last reactor in the cycloalkane dehydrogenation reaction zone is then regenerated in the regeneration zone.

[0044] The regenerated catalyst from the regenerator is fed into the first reactor of the alkane dehydrogenation cyclization reaction zone, and then flows sequentially through the remaining reactors of the alkane dehydrogenation cyclization reaction zone; the catalyst flowing out of the alkane dehydrogenation cyclization reaction zone is fed into the first reactor of the cycloalkane dehydrogenation reaction zone, and then flows sequentially through the remaining reactors of the cycloalkane dehydrogenation reaction zone.

[0045] In this disclosure, the cycloalkane dehydrogenation reaction zone refers to the reactor in which naphtha comes into contact with the catalyst and the cycloalkane dehydrogenation reaction mainly occurs; the alkane dehydrogenation cyclization reaction zone refers to the reactor in which the catalyst comes into contact with the stream exiting the cycloalkane dehydrogenation reaction zone and the alkane dehydrogenation cyclization reaction mainly occurs.

[0046] This disclosure improves the reaction process of the regenerated catalyst by utilizing the reaction characteristics that cycloalkane dehydrogenation produces fewer high-dry-point components and coking precursors, while alkane dehydrogenation cyclization produces more. The fresh regenerated catalyst is first contacted with the products from the cycloalkane dehydrogenation reaction to carry out the alkane dehydrogenation cyclization reaction. Compared to countercurrent or cocurrent moving bed continuous reforming reactions, the amount of coking on the catalyst is reduced throughout the system. Simultaneously, the catalyst is "passivated" in the first reactor of the alkane dehydrogenation cyclization reaction, allowing it to maintain high reactivity for the cycloalkane dehydrogenation reaction. This results in a better match between catalyst activity and reaction difficulty, further improving the reaction efficiency of alkane dehydrogenation cyclization and increasing liquid yield and aromatics yield.

[0047] This disclosure does not specifically limit the composition of the catalyst, but rather describes conventional continuous reforming catalysts in the art.

[0048] According to one embodiment of this disclosure, in the cycloalkane dehydrogenation reaction zone, the total conversion rate of cycloalkane components in naphtha is above 70%, and the total conversion rate of alkane components is below 25%; in the alkane dehydrogenation cyclization reaction zone, the total conversion rate of alkane components in naphtha is above 55%, and the total conversion rate of cycloalkane components is below 25%. The weight content of cycloalkane components in the naphtha described in this disclosure can be 10-60%, and the weight content of alkane components can be 20-80%, for example, selected from straight-run naphtha, coking naphtha, or hydrocracking naphtha.

[0049] According to one embodiment of this disclosure, each reaction zone includes 2 to 3 reactors connected in series from top to bottom.

[0050] According to one embodiment of this disclosure, each reaction zone includes two reactors connected in series from top to bottom;

[0051] The method includes: heating naphtha and then sequentially entering a first reactor and a second reactor connected in series to undergo a cycloalkane dehydrogenation reaction to obtain a second product; heating the second product and then sequentially entering a third reactor and a fourth reactor to undergo an alkane dehydrogenation cyclization reaction.

[0052] The regenerated catalyst is first introduced into the third reactor to undergo the alkane dehydrogenation cyclization reaction with the second product, and the three-transformer catalyst flows out. Under gravity, the three-transformer catalyst enters the fourth reactor to undergo the alkane dehydrogenation cyclization reaction, and the four-transformer catalyst flows out. The four-transformer catalyst is then pressurized and introduced into the first reactor to undergo the cycloalkane dehydrogenation reaction, and the first-transformer catalyst flows out. Under gravity, the first-transformer catalyst enters the second reactor to undergo the cycloalkane dehydrogenation reaction, yielding a spent catalyst. This spent catalyst is then introduced into the regeneration zone for catalyst regeneration. The above embodiments utilize the reaction characteristics of cycloalkane dehydrogenation reactions producing fewer high-dry-point components and coking precursors, while alkane dehydrogenation cyclization reactions produce more. This allows the fresh, regenerated catalyst to first contact the cycloalkane dehydrogenation products for the alkane dehydrogenation cyclization reaction. Compared to countercurrent or cocurrent moving bed continuous reforming reactions, the amount of coking on the catalyst is reduced throughout the system. Simultaneously, the catalyst is "passivated" in the first reactor of the alkane dehydrogenation cyclization reaction, maintaining high reactivity for the cycloalkane dehydrogenation reaction. This results in a better match between catalyst activity and reaction difficulty, further improving the reaction efficiency of alkane dehydrogenation cyclization and increasing liquid yield and aromatics yield. In this disclosure, high-dry-point components refer to heavy components with 12 or more carbon atoms; coking precursors refer to polycyclic aromatic hydrocarbons and long-chain olefins, such as naphthalene, indene, and dienes.

[0053] According to one embodiment of this disclosure, the temperature of each reactor is 450-550°C, preferably 480-540°C. In this disclosure, the temperature of each reactor refers to the inlet temperature of each reactor. The above embodiment is beneficial for improving liquid yield and aromatics yield.

[0054] According to one embodiment of this disclosure, the pressures of the first reactor, the second reactor, the third reactor, and the fourth reactor decrease sequentially. In a further embodiment, the inlet pressure of the first reactor is 0.35-0.80 MPa, preferably 0.40-0.55 MPa; the inlet pressure of the second reactor is 0.30-0.75 MPa, preferably 0.35-0.50 MPa; the inlet pressure of the third reactor is 0.25-0.70 MPa, preferably 0.30-0.45 MPa; and the inlet pressure of the fourth reactor is 0.20-0.65 MPa, preferably 0.25-0.40 MPa. These embodiments are beneficial for reducing catalyst coking in the reaction system and improving liquid yield and aromatic hydrocarbon yield.

[0055] According to one embodiment of this disclosure, the method further includes: providing a control zone between the fourth reactor and the first reactor; the control zone is equipped with a pressure conversion and flow control hopper for pressurizing the regenerated catalyst from the fourth reactor to the pressure of the first reactor before it enters the first reactor. This embodiment reduces the need for an upper long feed leg as a material seal in the regeneration section's structural frame; compared to conventional countercurrent reactors, it reduces the number of reverse pressure differential transport operations, eliminates the need for an extra-long feed leg at the top of the reactor, and reduces the number of equipment such as upper feed hoppers between reactors and hydrogen pressurization pipelines, thus lowering the investment in plant construction and reducing operational difficulty.

[0056] According to one embodiment of this disclosure, the control zone includes a low-pressure zone, a variable-pressure zone, and a high-pressure zone. The pressure in the low-pressure zone is 0.20-0.65 MPa, preferably 0.25-0.40 MPa; the pressure in the high-pressure zone is 0.35-0.80 MPa, preferably 0.45-0.65 MPa. This embodiment facilitates the regeneration of the catalyst by overcoming the adverse pressure difference and transitioning it from a lower-pressure reactor to a higher-pressure reactor.

[0057] According to one embodiment of this disclosure, the regeneration zone includes a regenerator and a reduction tank; the pressure of the regenerator is between that of the second reactor and the third reactor; the reduction tank is disposed above the third reactor, and the catalyst used for regenerating the regenerator is reduced and then enters the third reactor by gravity. In a further embodiment, the pressure of the regenerator is 0.25-0.75 MPa, preferably 0.35-0.45 MPa.

[0058] The second aspect of this disclosure provides a system for continuous reforming reaction of naphtha in a moving bed. The system includes a reaction zone and a regeneration zone. The reaction zone includes a cycloalkane dehydrogenation reaction zone and an alkane dehydrogenation cyclization reaction zone connected in sequence. The reactant outlet of the cycloalkane dehydrogenation reaction zone is connected to the reactant inlet of the alkane dehydrogenation cyclization reaction zone. Each reaction zone includes multiple reactors connected in series from top to bottom.

[0059] The regeneration zone includes a regenerator and a reduction tank; the reduction tank is located above the first reactor in the alkane dehydrogenation cyclization reaction zone; a first hydrogen booster line connects the catalyst outlet of the regenerator to the catalyst inlet of the reduction tank; the catalyst outlet of the reduction tank is connected to the catalyst inlet of the first reactor in the alkane dehydrogenation cyclization reaction zone; a second hydrogen booster line connects the catalyst outlet of the last reactor in the alkane dehydrogenation cyclization reaction zone to the catalyst inlet of the first reactor in the cycloalkane dehydrogenation reaction zone; and a nitrogen booster line connects the catalyst outlet of the last reactor in the cycloalkane dehydrogenation reaction zone to the catalyst inlet of the regenerator.

[0060] According to one embodiment of this disclosure, the system further includes a control zone, which is provided with a pressure conversion and flow control hopper; the control zone is located between the last reactor of the alkane dehydrogenation cyclization reaction zone and the first reactor of the cycloalkane dehydrogenation reaction zone, and is used to pressurize the catalyst from the last reactor of the alkane dehydrogenation cyclization reaction zone to the pressure of the first reactor of the cycloalkane dehydrogenation reaction zone before it enters the first reactor.

[0061] According to one embodiment of this disclosure, a buffer hopper is provided between the final reactor and the control zone of the alkane dehydrogenation cyclization reaction zone to buffer the regenerated catalyst flowing out of the final reactor of the alkane dehydrogenation cyclization reaction zone; a lower hopper is provided below the pressure conversion and control hopper to allow the regenerated catalyst, pressurized after passing through the pressure conversion and control hopper, to enter and await being lifted to the cycloalkane dehydrogenation reaction zone; an upper hopper is provided above the first reactor of the cycloalkane dehydrogenation reaction zone, and a lower hopper is provided below the final reactor of the cycloalkane dehydrogenation reaction zone to collect the catalyst to be regenerated, thereby entering the regenerator for regeneration. In this disclosure, the setting of the regeneration zone and the regeneration process of the catalyst to be regenerated in the regeneration zone are conventional operations in the art and are not specifically limited herein. For example, the regeneration zone includes a separation hopper, a regenerator, and a lower hopper of the regenerator arranged from top to bottom. The above-described implementation reduces the need for an upper long feed leg as a material seal in the regeneration section's structural frame; compared to conventional countercurrent reactors, it reduces the number of reverse pressure differential conveying operations, eliminates the need for an extra-long feed leg at the top of the reactor, and reduces the number of equipment such as upper feed hoppers between reactors and hydrogen pressurization pipelines, thereby lowering the investment in plant construction and reducing operational difficulty.

[0062] According to one embodiment of this disclosure, in the cycloalkane dehydrogenation reaction zone, the total conversion rate of cycloalkane components in the naphtha is above 70%, and the total conversion rate of alkane components is below 25%; in the alkane dehydrogenation cyclization reaction zone, the total conversion rate of alkane components in the naphtha is above 55%, and the total conversion rate of cycloalkane components is below 25%.

[0063] The technical solution of this disclosure is further described below with reference to the accompanying drawings, but this disclosure is not limited thereto and should not be construed as a limitation of this disclosure by those skilled in the art.

[0064] Unless otherwise specified, all raw materials used in the following embodiments are commercially available products. The industrial grade of the catalyst used in this disclosure is RC011, purchased from Hunan Jianchang Petrochemical Co., Ltd. The properties of the naphtha used in this disclosure are shown in Table 1. The composition of the naphtha was determined by a gas chromatograph (GC 8890), and the carbon content of the spent catalyst was determined by a carbon-sulfur analyzer (EMIA-820V).

[0065] Table 1

[0066] <![CDATA[Density (20°C), g / cm 3 > 0.7447 Sulfur content, ppm ＜0.5 Nitrogen content, ppm ＜0.5 Bromine valence, gBr / 100g ＜0.1 Initial boiling point 83.4 10％ 104.1 30％ 114.9 50％ 127.3 90％ 154.8 Final boiling point 172.5 Composition of naphtha, by mass % Alkanes 54.47 Cycloalkanes 30.55 Aromatics 14.96

[0067] Example 1

[0068] This embodiment 1 is as follows: Figure 1 The process shown involves a continuous reforming reaction, such as... Figure 1As shown, the naphtha continuous reforming system includes a reaction zone, a regeneration zone, and a control zone. The reaction zone includes a cycloalkane dehydrogenation reaction zone and an alkane dehydrogenation cyclization reaction zone connected in sequence. The reactant outlet of the cycloalkane dehydrogenation reaction zone is connected to the inlet of the alkane dehydrogenation cyclization reaction zone. Each reaction zone includes two reactors connected in series from top to bottom: reactor 2-1, reactor 2-2, reactor 2-3, and reactor 2-4. The regeneration zone includes a regenerator 2-5 and a reduction tank 212. The reduction tank 212 is located above the third reactor 2-3 in the alkane dehydrogenation cyclization reaction zone. A separation hopper 220 is located above the inlet of the regenerator 2-5, and a lower hopper 210 is located below the catalyst outlet of the regenerator. A first hydrogen riser line 211 connects the lower hopper 210 to the catalyst inlet of the reduction tank 212, which is used to allow the regenerated catalyst from the regenerator to first enter the first reactor in the alkane dehydrogenation cyclization reaction zone after reduction. The control zone is located in the alkane dehydrogenation cyclization reaction zone. Between the final reactor (fourth reactor 2-4) in the cycloalkane dehydrogenation reaction zone and the first reactor (2-1) in the cycloalkane dehydrogenation reaction zone, a pressure conversion and flow control hopper 214 is installed in the control zone. A buffer hopper 213 is installed between the fourth reactor 2-4 and the control zone. A lower hopper 215 is installed below the outlet of the control zone. A second hydrogen riser line 216 is connected between the catalyst outlet of the lower hopper 215 and the catalyst inlet of the first reactor (2-1) in the cycloalkane dehydrogenation reaction zone, used to lift the catalyst from the final reactor in the cycloalkane dehydrogenation cyclization reaction zone to the first reactor in the cycloalkane dehydrogenation reaction zone. An upper hopper 217 is installed above the inlet of the first reactor 2-1, and a lower hopper 218 is installed below the outlet of the second reactor 2-2, so that the outflowing catalyst awaiting regeneration waits in the lower hopper 218 to be lifted to the regenerator 2-5 for regeneration. A nitrogen riser line is connected between the catalyst outlet of the lower hopper 219 and the catalyst inlet of the regenerator 2-5, used to lift the catalyst awaiting regeneration to the regenerator for regeneration.

[0069] The naphtha reaction process is as follows: The feedstock enters heater I 202 via pipeline 201 and is heated to the reaction temperature. It then enters the first reactor 2-1, where the main reaction is cycloalkane dehydrogenation. Since this is primarily an endothermic reaction, the reactor outlet temperature decreases. The product from the first reactor enters heater II 204 via pipeline 203 and is heated to the reaction temperature. It then enters the second reactor 2-2, where the main reactions are the same in both reactors, primarily cycloalkane dehydrogenation. The product from the second reactor enters heater III 206 via pipeline 205 and is heated to the reaction temperature before entering the third reactor 2-3. In the third reactor, a large amount of alkanes undergo dehydrogenation to generate aromatics, while also producing a significant amount of coking precursors. The product from the third reactor enters heater IV 208 via pipeline 207 and is heated to the reaction temperature before entering the fourth reactor 2-4. The catalyst in the fourth reactor reacts with the product from the third reactor. The product from the fourth reactor is then exited via pipeline 209 and enters the post-fractionation system.

[0070] The catalyst circulation process is as follows: The spent catalyst undergoes coking, oxychlorination, drying, and cooling in regenerator 2-5, then flows out from the bottom of the regenerator and into the lower hopper 210. It is then lifted via riser 211 to the reduction tank 212 above the third reactor 2-3. In the reduction tank, the metal is converted from its oxidized state to its metallic state. Subsequently, it enters the third reactor 2-3 to react with the products of the second reactor. Since the first and second reactors mainly involve cycloalkane dehydrogenation, they produce relatively few high-dry-point compounds and coking precursors, resulting in minimal coking of the catalyst in the third reactor. The catalyst exiting the third reactor enters the fourth reactor 2-4, where it reacts with the products of the third reactor, converting a large amount of alkanes into aromatics. The catalyst exiting the fourth reactor then enters the fourth reactor... The catalyst is buffered in the lower hopper 213 of the reactor. Then, under the action of the pressure conversion and flow control hopper 214, the pressure is increased from the pressure in the fourth reactor to the pressure in the first reactor, and the catalyst flow rate is metered. The pressurized catalyst enters the lower hopper 215 and enters the upper hopper 217 of the first reactor through the lift line 216. In the first reactor 2-1, naphtha reacts with the catalyst from the fourth reactor. The reacted catalyst enters the second reactor 2-2 under the action of gravity. In the second reactor, it reacts with the product of the first reactor. The reacted catalyst enters the lower hopper 218 of the second reactor and is lifted to the separation hopper 220 through the lift line 219. After removing catalyst dust and fragments, it is returned to the regenerator for catalyst regeneration.

[0071] The catalyst loading amounts in reactors 2-1, 2-2, 2-3, and 2-4 are 7g, 7g, 7g, and 7g, respectively. A hydrogen circulation is established in the reaction unit. The reaction pressure in the reaction zone is controlled as follows: 0.35MPa in reactor 4, 0.38MPa in reactor 3, 0.41MPa in reactor 2, 0.44MPa in reactor 1, 0.34MPa in low-pressure zone, and 0.5MPa in high-pressure zone. At an inlet temperature of 400℃ for each reactor, naphtha is introduced at a feed rate of 100 ml / hr. The naphtha passes sequentially through the first, second, third, and fourth reactors, each with an inlet temperature of 520℃. The reaction products are then extracted from the fourth reactor. The first reactor 2-1 and the second reactor 2-2 primarily undergo cycloalkane dehydrogenation reactions, with a total conversion rate of over 70% for cycloalkane components and under 25% for alkanes. The third reactor 2-3 and the fourth reactor 2-4 primarily undergo alkane dehydrogenation cyclization reactions, with a total conversion rate of over 55% for alkanes and under 25% for cycloalkane components. When the water content in the circulating hydrogen is less than 100 ppm, the temperature is increased, and the octane number of the C5+ liquid product is adjusted to 103.5. The catalyst flowing out from the bottom of the second reactor is the catalyst to be generated.

[0072] The overall conversion rate of cycloalkanes is the total conversion rate of cycloalkanes flowing into and out of a reaction zone.

[0073] For example, the total conversion rate of cycloalkane in the cycloalkane dehydrogenation reaction zone can be calculated as follows:

[0074] Total conversion of cycloalkanes = (Cycloalkanes content in the inlet reaction stream of the cycloalkanes dehydrogenation reaction zone - Cycloalkanes content in the outlet reaction stream of the cycloalkanes dehydrogenation reaction zone) / Cycloalkanes content in the feedstock * 100%;

[0075] The total conversion rate of alkanes is the total conversion rate of alkanes flowing into and out of a reaction zone.

[0076] For example, in the alkane dehydrogenation cyclization reaction zone, the total conversion rate of alkanes can be calculated as follows:

[0077] Total conversion rate of alkanes = (Alkanes content in the inlet reaction stream of the alkanes dehydrogenation cyclization reaction zone - Alkanes content in the outlet reaction stream of the alkanes dehydrogenation cyclization reaction zone) / Alkanes content in the feedstock * 100%.

[0078] Comparative Example 1

[0079] This comparative example is as follows: Figure 2 The process shown involves a continuous reforming reaction, such as... Figure 2 As shown, the material reaction process is as follows: the raw material enters the heating furnace I'102 via pipeline 101 and is heated to the reaction temperature, then enters the first reactor I'1-1 via pipeline 103. In the first reactor, the main reaction is dehydrogenation. Since the main reaction is endothermic, the reactor outlet temperature decreases. The product from the first reactor enters the heating furnace II'105 via pipeline 104 and is heated to the reaction temperature, then enters the second reactor I'1-2 via pipeline 106 to react. The main reactions in the first and second reactors are the same, both mainly involving the dehydrogenation of cycloalkanes. The product from the outlet of the second reactor enters the heating furnace III'108 via pipeline 107 and is heated to the reaction temperature, then enters the third reactor I'1-3 via pipeline 109. In the third reactor, a large amount of alkanes are dehydrogenated to produce aromatics, and a large amount of coking precursors are also produced. The product from the third reactor enters the heating furnace IV'111 via pipeline 110 and is heated to the reaction temperature. Then, it enters the fourth reactor I'1-4 via pipeline 112. The catalyst in the fourth reactor reacts with the product from the third reactor. The product from the fourth reactor is then drawn out via pipeline 113 and enters the post-fractionation system.

[0080] The catalyst circulation process is as follows: After being coked, oxychlorinated, dried, and cooled in regenerator I'1-5, the spent catalyst flows out from the bottom of the regenerator and enters the lower hopper 114 of the regenerator. It is then lifted through the lift line I'115 to the upper buffer hopper I'116 of the fourth reactor I'1-4, and then enters the reduction tank I'118 via the pressure difference through the pipeline 117. In the reduction tank, the metal is converted from the oxidized state to the metallic state. Subsequently, it enters the fourth reactor I'1-4 to react with the product of the third reactor. The catalyst after the reaction enters the lower hopper I'119 and is then lifted through the lift line... After being lifted, the catalyst enters the upper buffer hopper II'121 of the third reactor. Since the pressure in buffer hopper II'121 is lower than that in the upper hopper I'123 of the third reactor, it needs to be sealed via feed leg I'122. Under the influence of hydrogen, the pressure in the upper hopper I'123 of the third reactor increases, allowing the catalyst to smoothly enter the third reactor I'1-3. In the third reactor, the catalyst reacts with the products from the second reactor. The reacted catalyst enters the lower hopper II'124, and after being lifted via lift line III'125, it enters the upper buffer hopper of the second reactor. The feed hopper Ⅲ'126, due to its lower pressure compared to the upper feed hopper Ⅱ'128 of the second reactor, requires sealing via feed leg Ⅱ'127. Under the influence of hydrogen, the pressure in the upper feed hopper Ⅱ'128 increases, allowing the catalyst to smoothly enter the second reactor Ⅰ'1-2. In the second reactor, the catalyst reacts with the products from the first reactor. The reacted catalyst enters the lower feed hopper Ⅲ'129, is then lifted via lift line Ⅳ'130, and enters the upper buffer feed hopper Ⅳ'131 of the first reactor. Because the buffer feed hopper Ⅳ'1... The pressure at 31 is lower than that at the upper hopper Ⅲ'133 of the first reactor, so it needs to be sealed by the feed leg Ⅲ'132. Under the action of hydrogen, the pressure at the upper hopper Ⅲ'133 of the first reactor increases, allowing the catalyst to smoothly enter the first reactor I'1-1. In the first reactor, the catalyst comes into contact with the raw materials and reacts. The reacted catalyst enters the lower hopper Ⅳ'134, is lifted by the lift line Ⅴ'135, and enters the separation hopper I'136 to remove catalyst dust and particles. It then enters the metering tank I'137 to measure the catalyst flow rate and returns to the regenerator for catalyst regeneration.

[0081] The catalyst loading amounts of the first reactor I'1-1, the second reactor I'1-2, the third reactor I'1-3, and the fourth reactor I'1-4 are 7g, 7g, 7g, and 7g, respectively. A hydrogen circulation is established in the reaction unit, and the reaction pressure of the fourth reactor is controlled at 0.25MPa. When the inlet temperature of the first reactor is 400℃, the raw material is introduced at a feed rate of 100 ml / hr to obtain the reaction products. The first reactor I'1-1 and the second reactor I'1-2 mainly undergo cycloalkane dehydrogenation reactions. In the cycloalkane dehydrogenation reaction zone, the total conversion rate of cycloalkane components is above 70%, and the total conversion rate of alkanes is below 25%. The third reactor I'1-3 and the fourth reactor I'1-4 mainly undergo alkane dehydrogenation cyclization reactions. In the alkane dehydrogenation cyclization reaction zone, the total conversion rate of alkanes is above 55%, and the total conversion rate of cycloalkanes is below 25%. When the water content in the circulating hydrogen is less than 100 ppm, the temperature is increased, and the octane number of the C5+ liquid product is adjusted to 102. The catalyst flowing out from the bottom of the first reactor is the catalyst to be generated.

[0082] The conversion rate was calculated in the same way as in Example 1.

[0083] The products and catalysts obtained from the above examples and comparative examples were analyzed, and the results are shown in Table 2.

[0084] Table 2

[0085] C5+ product octane rating 103.5 103.5 C5+ liquid yield, % by mass 85.11 84.98 Aromatics yield, % by mass 73.94 73.19 Carbon content of the catalyst (mass%) 3.3 3.8

[0086] As can be seen from the results in Table 2, the method provided in this disclosure reduces the amount of coke deposited in the reaction system, and improves the liquid yield and aromatics yield.

[0087] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0088] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0089] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for continuous reforming reaction of naphtha in a moving bed, characterized in that, The method includes: Naphtha is sequentially introduced into a series of cycloalkane dehydrogenation reaction zones and a chain alkane dehydrogenation cyclization reaction zones to react with the catalyst, wherein each reaction zone includes multiple reactors in series. The catalyst flowing out of the last reactor in the cycloalkane dehydrogenation reaction zone is then regenerated in the regeneration zone. The regenerated catalyst from the regenerator is fed into the first reactor of the alkane dehydrogenation cyclization reaction zone, and then flows sequentially through the remaining reactors of the alkane dehydrogenation cyclization reaction zone; the catalyst flowing out of the alkane dehydrogenation cyclization reaction zone is fed into the first reactor of the cycloalkane dehydrogenation reaction zone, and then flows sequentially through the remaining reactors of the cycloalkane dehydrogenation reaction zone. Each reaction zone comprises two reactors connected in series from top to bottom; The method includes: heating naphtha and then sequentially entering a first reactor and a second reactor connected in series to undergo a cycloalkane dehydrogenation reaction to obtain a second product; heating the second product and then sequentially entering a third reactor and a fourth reactor to undergo an alkane dehydrogenation cyclization reaction. The regenerated catalyst is first introduced into the third reactor to contact the second product and carry out the alkane dehydrogenation cyclization reaction, from which the three-transformer catalyst flows out. Under gravity, the three-transformer catalyst enters the fourth reactor to carry out the alkane dehydrogenation cyclization reaction, from which the four-transformer catalyst flows out. The four-transformer catalyst is then pressurized and introduced into the first reactor to carry out the cycloalkane dehydrogenation reaction, from which the first-transformer catalyst flows out. Under gravity, the first-transformer catalyst enters the second reactor to carry out the cycloalkane dehydrogenation reaction, yielding the regenerated catalyst. The catalyst to be generated is then introduced into the regeneration zone for catalyst regeneration.

2. The method according to claim 1, wherein, The temperature of each reactor is 450-550℃.

3. The method according to claim 2, wherein, The temperature of each reactor is 480-540℃.

4. The method according to claim 1, wherein, The pressures of the first reactor, the second reactor, the third reactor, and the fourth reactor decrease sequentially.

5. The method according to claim 4, wherein, The inlet pressure of the first reactor is 0.35-0.80 MPa; The inlet pressure of the second reactor is 0.30-0.75 MPa; The inlet pressure of the third reactor is 0.25-0.70 MPa; The inlet pressure of the fourth reactor is 0.20-0.65 MPa.

6. The method according to claim 5, wherein, The inlet pressure of the first reactor is 0.40-0.55 MPa; The inlet pressure of the second reactor is 0.35-0.50 MPa; The inlet pressure of the third reactor is 0.30-0.45 MPa; The inlet pressure of the fourth reactor is 0.25-0.40 MPa.

7. The method according to claim 4, wherein, The method further includes: a control zone is provided between the fourth reactor and the first reactor; the control zone is provided with a pressure conversion and flow control hopper for pressurizing the catalyst from the fourth reactor to the pressure of the first reactor before it enters the first reactor.

8. The method according to claim 7, wherein, The control zone includes a low-pressure zone, a transformer zone, and a high-pressure zone. The pressure in the low-pressure zone is 0.20-0.65 MPa, and the pressure in the high-pressure zone is 0.35-0.80 MPa.

9. The method according to claim 8, wherein, The pressure in the low-pressure zone is 0.25-0.40 MPa; the pressure in the high-pressure zone is 0.45-0.65 MPa.

10. The method according to claim 1, wherein, The regeneration zone includes a regenerator and a reduction tank; the pressure of the regenerator is between that of the second reactor and the third reactor; the reduction tank is located above the third reactor, and the catalyst used to regenerate the regenerator is reduced and then enters the third reactor by gravity.

11. The method according to claim 10, wherein, The pressure of the regenerator is 0.25-0.75 MPa.

12. The method according to claim 11, wherein, The pressure of the regenerator is 0.35-0.45 MPa.

13. The method according to any one of claims 1 to 12, wherein, In the cycloalkane dehydrogenation reaction zone, the total conversion rate of cycloalkane components in naphtha is above 70%, and the total conversion rate of alkane components is below 25%; in the alkane dehydrogenation cyclization reaction zone, the total conversion rate of alkane components in naphtha is above 55%, and the total conversion rate of cycloalkane components is below 25%.

14. A system for continuous reforming reaction of naphtha in a moving bed, characterized in that, The system includes a reaction zone and a regeneration zone. The reaction zone includes a cycloalkane dehydrogenation reaction zone and an alkane dehydrogenation cyclization reaction zone connected in sequence. The reactant outlet of the cycloalkane dehydrogenation reaction zone is connected to the reactant inlet of the alkane dehydrogenation cyclization reaction zone. Each reaction zone includes multiple reactors connected in series from top to bottom. The regeneration zone includes a regenerator and a reduction tank; the reduction tank is located above the first reactor in the alkane dehydrogenation cyclization reaction zone; a first hydrogen booster line connects the catalyst outlet of the regenerator to the catalyst inlet of the reduction tank; the catalyst outlet of the reduction tank is connected to the catalyst inlet of the first reactor in the alkane dehydrogenation cyclization reaction zone; a second hydrogen booster line connects the catalyst outlet of the last reactor in the alkane dehydrogenation cyclization reaction zone to the catalyst inlet of the first reactor in the cycloalkane dehydrogenation reaction zone; and a nitrogen booster line connects the catalyst outlet of the last reactor in the cycloalkane dehydrogenation reaction zone to the catalyst inlet of the regenerator.

15. The system according to claim 14, wherein, The system also includes a control area, which is equipped with a pressure conversion and flow control hopper; The control zone is located between the last reactor of the alkane dehydrogenation cyclization reaction zone and the first reactor of the cycloalkane dehydrogenation reaction zone, and is used to pressurize the catalyst from the last reactor of the alkane dehydrogenation cyclization reaction zone to the pressure of the first reactor of the cycloalkane dehydrogenation reaction zone before it enters the first reactor.

16. The system according to claim 14, wherein, In the cycloalkane dehydrogenation reaction zone, the total conversion rate of cycloalkane components in naphtha is above 70%, and the total conversion rate of alkane components is below 25%; in the alkane dehydrogenation cyclization reaction zone, the total conversion rate of alkane components in naphtha is above 55%, and the total conversion rate of cycloalkane components is below 25%.

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