A method for continuous reforming of naphtha

Abstract

The present invention relates to the field of petrochemical technology, and more particularly to a method for continuous reforming of naphtha. The method comprises: (1) separating naphtha to obtain a light fraction and a heavy fraction; (2) introducing the light fraction into a first reaction zone under hydrogen conditions for a first contact reaction to obtain a reaction product I, and introducing the reaction product I and the heavy fraction into a second reaction zone for a second contact reaction; (3) introducing the regenerated catalyst flowing out of the contact reaction unit into a regenerator for regeneration treatment to obtain a regenerated catalyst, and recycling the regenerated catalyst back to the contact reaction unit. The method provided by the present invention can promote the conversion of the light fraction in naphtha, thereby improving the yield of aromatics.

Description

Technical Field

[0001] The present invention relates to the technical field of petrochemical industry, in particular to a method for continuous reforming of naphtha. Background Art

[0002] Catalytic reforming is a key process that uses naphtha as a feedstock to produce high-octane gasoline or aromatics, with hydrogen as a by-product. Depending on the process characteristics, catalytic reforming is categorized into fixed-bed semi-regenerative catalytic reforming, moving-bed continuous catalytic reforming, and fixed-bed cyclic regenerative catalytic reforming. Moving-bed continuous catalytic reforming units typically utilize three to four reactors, through which reactants flow sequentially in series.

[0003] Continuous reforming is categorized as co-current and counter-current, depending on the direction of catalyst and material flow. Both co-current and counter-current reforming processes present the problem of easily converting heavier fractions (e.g., C8+) while resisting conversion of lighter fractions. Furthermore, prolonged contact of heavier fractions with the catalyst produces a significant amount of coke precursors, accelerating catalyst carbon deposition.

[0004] US4325806 discloses a hydrocarbon conversion process having at least three reaction zones, wherein all reactants enter a first reaction zone, the product of the first reaction zone is divided into two parts, one part of the product passes through a second reaction zone, and the other part is combined with all the products of the second reaction zone and then passes through a third reaction zone.

[0005] US4325807A discloses a hydrocarbon conversion process having at least four reaction zones, wherein the first reaction zone and the second reaction zone are arranged in a parallel flow manner, and the two reaction zones share a heating furnace. The raw materials enter the first reaction zone and the second reaction zone in two ways respectively, and the products of the first reaction zone and the second reaction zone are combined and divided into two ways, one part passes through the third reaction zone, and the other part is combined with all the products of the third reaction zone and then passes through the fourth reaction zone.

[0006] USP5879537A discloses a hydrocarbon conversion method for staggered bypass of reaction zones, which uses four reaction zones. The reactant hydrocarbons are divided into two streams, one entering the first reaction zone and the other entering the second reaction zone; the product of the first reaction zone is further divided into two streams, one of which is combined with the hydrocarbons that bypass the first reaction zone and then enters the second reaction zone, and the other enters the third reaction zone; the product of the second reaction zone is also divided into two streams, one of which is combined with the product from the first reaction zone and enters the third reaction zone, and the other is combined with the product of the third reaction zone and then enters the fourth reaction zone.

[0007] CN100569918C discloses a semi-regenerative catalytic reforming method with multi-stage feeding, which includes passing a first stream of raw materials into the first-stage reactor of the reforming device, and then mixing a second stream of raw materials with the product of the front-stage reactor and passing them into the rear-stage reactor. The second stream of raw materials accounts for 1-30% by volume of the total amount of raw materials for the reforming reaction, and the cycloalkane content in the second stream of raw materials is greater than the cycloalkane content in the first stream of raw materials.

[0008] CN105462608A discloses a method for continuous catalytic reforming of naphtha, comprising mixing refined naphtha entering a continuous reforming reaction unit with hydrogen-rich gas and then dividing the mixture into two parts, one part entering a first reactor, and the other part mixing with the effluent of the first reactor and then entering a second reactor, the effluent of the second reactor being followed by a subsequent reactor. The continuous reforming reaction unit comprises at least three reactors connected in series, and the volume of the first reactor is smaller than that of the other reactors. Summary of the Invention

[0009] The purpose of the present invention is to overcome the problems in the prior art of naphtha continuous reforming process, in which light fractions are difficult to convert and catalyst carbon deposition occurs due to the long contact time between heavy fractions and catalyst.

[0010] To achieve the above object, the present invention provides a method for continuous reforming of naphtha, which is carried out in a continuous reforming device, wherein the continuous reforming device includes a contact reaction unit and a regenerator connected in sequence, wherein the contact reaction unit is provided with a first reaction zone and a second reaction zone that are kept in communication, and the method comprises:

[0011] (1) separating naphtha to obtain a light fraction and a heavy fraction;

[0012] (2) introducing the light fraction into the first reaction zone under hydrogen conditions to carry out a first contact reaction to obtain a reaction product I, and introducing the reaction product I and the heavy fraction into the second reaction zone to carry out a second contact reaction;

[0013] (3) introducing the regenerated catalyst flowing out of the contact reaction unit into a regenerator for regeneration treatment to obtain a regenerated catalyst, and recycling the regenerated catalyst back to the contact reaction unit;

[0014] Wherein, the cutting point between the light fraction and the heavy fraction is 100-130°C;

[0015] The first reaction zone and the second reaction zone each independently include at least one reactor; and according to the flow direction of the liquid phase logistics, the inlet temperature of each reactor in the first reaction zone is higher than the inlet temperature of the most upstream reactor in the second reaction zone.

[0016] The method provided by the present invention can not only promote the conversion of light fractions in naphtha, but also improve the yield of aromatics, while reducing the contact time between heavy fractions in naphtha and the catalyst and reducing carbon deposition on the catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic flow diagram of a preferred embodiment of the naphtha continuous reforming method provided by the present invention;

[0018] Figure 2 This is a schematic flow diagram of another preferred embodiment of the naphtha continuous reforming method provided by the present invention;

[0019] Figure 3 This is a schematic flow diagram of another preferred embodiment of the naphtha continuous reforming method provided by the present invention;

[0020] Figure 4 It is a flow diagram of another preferred embodiment of the naphtha continuous reforming method provided by the present invention.

[0021] Description of Reference Numerals

[0022] 101. First pipeline 102. First heating furnace

[0023] 103, second pipeline 104, third pipeline

[0024] 105. Fourth pipeline 106. Second heating furnace

[0025] 110, Fifth Pipeline 111, Sixth Pipeline

[0026] 112. Third heating furnace 113. Seventh pipeline

[0027] 114. Pipeline 8 I. First Reactor

[0028] II, second reactor III, third reactor

[0029] IV. The fourth reactor DETAILED DESCRIPTION

[0030] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0031] As described above, the present invention provides a method for continuous reforming of naphtha, which is carried out in a continuous reforming device, wherein the continuous reforming device includes a contact reaction unit and a regenerator connected in sequence, wherein the contact reaction unit is provided with a first reaction zone and a second reaction zone that are kept in communication, and the method comprises:

[0032] (1) separating naphtha to obtain a light fraction and a heavy fraction;

[0033] (2) introducing the light fraction into the first reaction zone under hydrogen conditions to carry out a first contact reaction to obtain a reaction product I, and introducing the reaction product I and the heavy fraction into the second reaction zone to carry out a second contact reaction;

[0034] (3) introducing the regenerated catalyst flowing out of the contact reaction unit into a regenerator for regeneration treatment to obtain a regenerated catalyst, and recycling the regenerated catalyst back to the contact reaction unit;

[0035] Wherein, the cutting point between the light fraction and the heavy fraction is 100-130°C;

[0036] The first reaction zone and the second reaction zone each independently include at least one reactor; and according to the flow direction of the liquid phase logistics, the inlet temperature of each reactor in the first reaction zone is higher than the inlet temperature of the most upstream reactor in the second reaction zone.

[0037] During the research process, the inventors discovered that according to the reaction characteristics of different naphtha fractions in the catalytic reforming reaction process, naphtha is cut into light fractions and heavy fractions. The light fraction that is more difficult to react first enters the reactor for reaction, and the heavy fraction that is more reactive is introduced into the subsequent reactor. Different reaction conditions are adopted in the reactors for introducing the light fraction and the heavy fraction. The method provided by the present invention can, on the one hand, increase the severity of the light fraction and promote the conversion of the light fraction. On the other hand, the catalyst is first passivated during the contact between the light fraction and the catalyst, which can reduce the contact time between the heavy fraction and the catalyst, thereby reducing carbon deposition on the catalyst.

[0038] Preferably, the cutting point between the light fraction and the heavy fraction is 110-130° C. so that the C7 content in the heavy fraction is less than 1% by mass.

[0039] Preferably, the cutting point between the light fraction and the heavy fraction is 100-115° C. so that the C6 content in the heavy fraction is less than 1% by mass.

[0040] In the present invention, the naphtha includes C6-C 12The naphtha is cut into a light fraction and a heavy fraction. When the C7 content of the heavy fraction is less than 1% by mass, the light fraction is mainly composed of C6-C7 hydrocarbons; when the C6 content in the heavy fraction is less than 1% by mass, the light fraction is mainly composed of C6 hydrocarbons.

[0041] Preferably, the contact reaction unit comprises at least three reactors connected in series.

[0042] Preferably, the reactors connected in series are arranged in parallel or stacked.

[0043] According to a particularly preferred embodiment of the present invention, the first reaction zone comprises a reactor.

[0044] It should be noted that, in this case, the light fraction is introduced into the reactor of the first reaction zone for a first contact reaction to obtain a reaction product I, and then the heavy fraction is mixed with the reaction product I and enters the upstream reactor in the second reaction zone, and then passes through the downstream reactors in the second reaction zone in sequence.

[0045] Preferably, the inlet temperature of the reactor in the first reaction zone is 10-50° C. higher than the inlet temperature of the most upstream reactor in the second reaction zone, more preferably 20-40° C. The inventors have found that adopting this preferred embodiment can obtain aromatics with a higher yield.

[0046] According to another particularly preferred embodiment of the present invention, the first reaction zone comprises two reactors.

[0047] It should be noted that, in this case, the light fraction enters the upstream reactor and the downstream reactor of the first reaction zone in sequence for catalytic reforming reaction to obtain reaction product I, and then the heavy fraction is mixed with the reaction product I and enters the upstream reactor in the second reaction zone, and then passes through the downstream reactors in the second reaction zone in sequence.

[0048] Preferably, the inlet temperature of each reactor in the first reaction zone is 10-40° C. higher than the inlet temperature of the most upstream reactor in the second reaction zone, more preferably 10-25° C. The inventors have found that adopting the specific embodiment of this preferred case can obtain aromatics with a higher yield.

[0049] Preferably, in step (2), the method further comprises: before carrying out the first contact reaction, subjecting the light fraction to a first heating treatment.

[0050] Preferably, in step (2), the method further comprises: before carrying out the second contact reaction, subjecting the reaction product I and the heavy fraction to a second heating treatment.

[0051] Preferably, in step (2), the conditions of the first reaction zone include at least: an inlet temperature of 480-580°C, a volume space velocity of 0.3-3h -1 , the hydrogen-to-oil molar ratio is 0.5-3:1.

[0052] Preferably, in step (2), the conditions of the second reaction zone include at least: an inlet temperature of 460-550°C, a volume space velocity of 0.3-3h -1 , the hydrogen-to-oil molar ratio is 0.5-3:1.

[0053] Preferably, the first contact reaction is carried out in a manner such that the light fraction contacts the catalyst in a countercurrent or forward manner in the first reaction zone.

[0054] It should be noted that when the flow direction of the liquid phase logistics is opposite to the flow direction of the catalyst, the light fraction and the catalyst are in counter-contact in the first reaction zone. At this time, the flow method of the catalyst is to flow from the most downstream reactor to the adjacent upstream reactor in sequence; when the flow direction of the liquid phase logistics is the same as the flow direction of the catalyst, the light fraction and the catalyst are in forward contact in the first reaction zone. At this time, the flow method of the catalyst is to flow from the most upstream reactor to the adjacent downstream reactor in sequence.

[0055] Preferably, the average reaction pressure of the contact reaction unit is 0.1-1 MPa, preferably 0.2-0.8 MPa.

[0056] The present invention has no particular requirements on the type of the catalyst, and any catalyst known in the art for continuous reforming methods can be used, for example, the catalyst for catalytic reforming reaction disclosed in CN105462608A.

[0057] The present invention has no special requirements on the type of the regenerator, and any regenerator known in the art can be used to regenerate the catalyst to be regenerated.

[0058] The following combination Figure 1 、 Figure 2 、 Figure 3 and Figure 4 The technical solution of the present invention is further described, but the present invention is not limited thereto and those skilled in the art should not understand it as limiting the present invention.

[0059] Figure 1 The present invention provides a schematic flow chart of a preferred embodiment of the continuous naphtha reforming method.

[0060] exist Figure 1In the specific embodiment shown, the first reaction zone includes a reactor, the light fraction is introduced into the reactor of the first reaction zone to carry out a first contact reaction to obtain a reaction product I, and then the heavy fraction is mixed with the reaction product I and enters the upstreammost reactor in the second reaction zone, and the first contact reaction is carried out in a manner such that the light fraction and the catalyst are in forward contact in the first reaction zone.

[0061] The specific method includes the following steps:

[0062] (1) separating naphtha to obtain a light fraction and a heavy fraction;

[0063] (2) The light fraction is mixed with hydrogen for heat exchange and then enters the first heating furnace 102 through the first pipeline 101 and is heated to 480-580°C. Then, it enters the first reactor I through the second pipeline 103 for the first contact reaction. The light fraction feed volume space velocity is 0.3-3h -1 The hydrogen-to-oil molar ratio is 0.5-3. The reaction product of the first reactor I is discharged from the third pipeline 104. The heavy fraction is introduced from the fourth pipeline 105 and mixed with the product of the first reactor I before entering the second heating furnace 106 and being heated to 460-550°C. The volumetric space velocity of the heavy fraction feed is 0.3-3h -1 The hydrogen-to-oil molar ratio is 0.5 to 3. The mixture of light fraction and heavy fraction enters the third reactor III through the fifth pipeline 110, and then passes through the sixth pipeline 111, the fourth heating furnace 112, the seventh pipeline 113, and the fourth reactor IV in sequence. The product of the fourth reactor IV is discharged through the eighth pipeline 114 and enters the product separation part.

[0064] The catalyst flows in the direction of the first reactor I, the second reactor II, the third reactor III, the fourth reactor IV, and the regenerator. The regenerated catalyst returns to the first reactor I from the regenerator to complete the catalyst cycle.

[0065] Figure 2 The present invention provides a schematic flow chart of another preferred embodiment of the continuous naphtha reforming method.

[0066] Figure 2 and Figure 1 The reaction process is similar to that of Figure 2 In the embodiment, the first reaction zone includes two reactors, the light fraction sequentially enters the upstream reactor and the downstream reactor of the first reaction zone to undergo catalytic reforming reaction to obtain a reaction product I, and then the heavy fraction is mixed with the reaction product I and enters the upstreammost reactor of the second reaction zone, and then sequentially passes through the downstream reactors of the second reaction zone; Figure 2 In the embodiment shown, the catalyst cycle process is Figure 1 The catalyst cycle process is the same.

[0067] Figure 3 The present invention provides a schematic flow chart of another preferred embodiment of the continuous naphtha reforming method.

[0068] Figure 3 and Figure 1 The reaction process is similar to that of FIG. 1 , except that the first contact reaction is carried out in such a manner that the light fraction contacts the catalyst in the first reaction zone in a reverse direction, that is, Figure 3 In the specific embodiment shown, the catalyst circulation direction is that the catalyst passes through the fourth reactor IV, the third reactor III, the second reactor II, and the first reactor I in sequence, the regenerated catalyst flows out from the bottom of the first reactor into the regenerator, and the regenerated catalyst flows out from the bottom of the regenerator into the fourth reactor IV, completing the catalyst circulation.

[0069] Figure 4 The present invention provides a schematic flow chart of another preferred embodiment of the continuous naphtha reforming method.

[0070] Figure 4 and Figure 1 The reaction process is similar to that of the reactor, except that the four reactors are arranged in an overlapping manner, the catalyst flow between the reactors relies on gravity, and the catalyst is circulated from the contact reaction unit to the regenerator, and from the regenerator to the contact reaction unit through lifting.

[0071] The present invention will be described in detail below through examples. In the following examples, unless otherwise specified, all raw materials used are commercially available.

[0072] Catalyst: brand RC011, purchased from Hunan Jianchang Petrochemical Co., Ltd.

[0073] Unless otherwise stated, the properties of the naphtha used in the following examples are shown in Table 1.

[0074] Table 1

[0075]

[0076] Example 1

[0077] The naphtha shown in Table 1 is cut into heavy fraction and light fraction at 120℃, where the heavy fraction mainly consists of C8~C 11 The light fraction is mainly composed of C6-C7 hydrocarbons.

[0078] according to Figure 1The process flow arrangement shown in the figure has catalyst loadings of 20 ml, 23 ml, 27 ml, and 30 ml in the first, second, third, and fourth reactors, respectively, in the first reactor I, second reactor II, third reactor III, and fourth reactor IV. Hydrogen circulation is established in the contact reaction unit, and the reaction pressure in the contact reaction unit is controlled at 0.35 MPa. At a reactor inlet temperature of 400°C, a light fraction is introduced into the first reactor I for a first contact reaction at a feed rate of 100 ml / hr, yielding reaction product I. The heavy fraction is then mixed with reaction product I and introduced into the second reactor II at a feed rate of 100 ml / hr. When the water content in the circulating hydrogen is less than 100 ppm, the temperature is increased to control the octane number of the C5+ liquid product to 102. The inlet temperatures of the first, second, third, and fourth reactors IV are 535°C, 500°C, 500°C, and 500°C, respectively.

[0079] Example 2

[0080] The naphtha shown in Table 1 is cut into heavy fraction and light fraction at 106℃, where the heavy fraction mainly consists of C7~C 11 The hydrocarbons of the oil are C7, with a C7 content of less than 1% by mass; the light fraction is mainly C6 hydrocarbons.

[0081] according to Figure 2 The process flow arrangement shown in the figure has catalyst loadings of 20 ml, 23 ml, 27 ml, and 30 ml in the first, second, third, and fourth reactors, respectively. Hydrogen circulation is established within the contact reaction units, and the reaction pressure in the contact reaction units is controlled at 0.35 MPa. At a reactor inlet temperature of 400°C, a light fraction is introduced into the first and second reactors, at a feed rate of 1000 ml / hr, for a first contact reaction to produce reaction product I. The heavy fraction is then mixed with reaction product I and introduced into the third reactor, at a feed rate of 100 ml / hr. When the water content in the circulating hydrogen is less than 100 ppm, the temperature is increased to control the octane number of the C5+ liquid product to 102. The inlet temperatures of the first, second, third, and fourth reactors, respectively, are 525°C, 510°C, 500°C, and 500°C.

[0082] Example 3

[0083] The naphtha shown in Table 1 is cut into heavy fraction and light fraction at 120℃, where the heavy fraction mainly consists of C8~C 11 The light fraction is mainly composed of C6-C7 hydrocarbons.

[0084] according to Figure 3The process flow arrangement shown in the figure has catalyst loadings of 20 ml, 23 ml, 27 ml, and 30 ml in the first, second, third, and fourth reactors, respectively. Hydrogen circulation is established within the contact reaction units, and the reaction pressure is controlled at 0.35 MPa. At a reactor inlet temperature of 400°C, a light fraction is introduced into the first reactor (I) for a first contact reaction at a feed rate of 100 ml / hr, yielding reaction product I. The heavy fraction is then mixed with reaction product I and introduced into the second reactor (II) at a feed rate of 100 ml / hr. When the water content in the circulating hydrogen is less than 100 ppm, the temperature is increased to control the octane number of the C5+ liquid product to 102. The inlet temperatures of the first, second, third, and fourth reactors (IV) are 535°C, 500°C, 500°C, and 500°C, respectively.

[0085] Example 4

[0086] The naphtha shown in Table 1 is cut into heavy fraction and light fraction at 120℃, where the heavy fraction mainly consists of C8~C 11 The light fraction is mainly composed of C6-C7 hydrocarbons.

[0087] according to Figure 4 The process flow arrangement shown in the figure has catalyst loadings of 20 ml, 23 ml, 27 ml, and 30 ml in the first, second, third, and fourth reactors, respectively, in the first reactor I, second reactor II, third reactor III, and fourth reactor IV. Hydrogen circulation is established in the contact reaction unit, and the reaction pressure in the contact reaction unit is controlled at 0.35 MPa. At a reactor inlet temperature of 400°C, a light fraction is introduced into the first reactor I for a first contact reaction at a feed rate of 100 ml / hr, yielding reaction product I. The heavy fraction is then mixed with reaction product I and introduced into the second reactor II at a feed rate of 100 ml / hr. When the water content in the circulating hydrogen is less than 100 ppm, the temperature is increased to control the octane number of the C5+ liquid product to 102. The inlet temperatures of the first, second, third, and fourth reactors IV are 535°C, 500°C, 500°C, and 500°C, respectively.

[0088] Example 5

[0089] Continuous naphtha reforming was carried out according to the method of Example 1, except that the inlet temperatures of the first reactor I, the second reactor II, the third reactor III and the fourth reactor IV were 550°C, 500°C, 500°C and 500°C, respectively.

[0090] Example 6

[0091] Continuous naphtha reforming was carried out according to the method of Example 2, except that the inlet temperatures of the first reactor I, the second reactor II, the third reactor III and the fourth reactor IV were 540°C, 510°C, 500°C and 500°C, respectively.

[0092] Comparative Example 1

[0093] Using naphtha as shown in Table 1 as raw material, Figure 1 The process flow arrangement shown in the figure has catalyst loadings of 20 ml, 23 ml, 27 ml, and 30 ml in the first, second, third, and fourth reactors, respectively, in the first, second, third, and fourth reactors, respectively. Hydrogen circulation is established within the contact reaction unit, and the reaction pressure in the contact reaction unit is controlled at 0.35 MPa. At a reactor inlet temperature of 400°C, naphtha is introduced into the first reactor, I, for the first contact reaction at a feed rate of 200 ml / hr, yielding reaction product I. When the water content in the circulating hydrogen is less than 100 ppm, the temperature is increased to control the octane number of the C5+ liquid product to 102. The inlet temperatures of the first, second, third, and fourth reactors, I, II, III, and IV, are all 515°C.

[0094] Comparative Example 2

[0095] The naphtha shown in Table 1 was used as raw material and was evenly divided into two streams.

[0096] according to Figure 1 The process flow arrangement shown in the figure has catalyst loadings of 20 ml, 23 ml, 27 ml, and 30 ml in the first, second, third, and fourth reactors, respectively, in the first reactor I, second reactor II, third reactor III, and fourth reactor IV. Hydrogen circulation is established within the contact reaction unit, and the reaction pressure in the contact reaction unit is controlled at 0.35 MPa. At a reactor inlet temperature of 400°C, a first stream of naphtha is introduced into the first reactor I for a first contact reaction at a feed rate of 100 ml / hr, yielding reaction product I. The second stream of feedstock is then mixed with reaction product I and introduced into the second reactor II at a feed rate of 100 ml / hr. When the water content of the circulating hydrogen is less than 100 ppm, the temperature is increased to control the octane number of the C5+ liquid product to 102. The inlet temperatures of the first, second, third, and fourth reactors IV are all 516°C.

[0097] Table 2

[0098] Example 1 Example 2 Example 3 Example 4 C5+ product octane number 102 102 102 102 C5+ liquid recovery rate, mass% 88.8 88.45 89.0 88.5 Aromatic hydrocarbon yield, mass% 72.9 72.9 73.0 72.7 Hydrogen yield, mass% 3.7 3.7 3.7 3.7 Carbon content of spent catalyst 3.8 3.8 3.9 3.7

[0099] Table 2 (Continued)

[0100] Example 5 Example 6 Comparative Example 1 Comparative Example 2 C5+ product octane number 102 102 102 102 C5+ liquid recovery rate, mass% 88.4 88.35 87.9 88.0 Aromatic hydrocarbon yield, mass% 72.7 72.65 72.1 72.0 Hydrogen yield, mass% 3.65 3.65 3.6 3.6 Carbon content of spent catalyst 3.9 3.9 4.2 4.2

[0101] From the results in Table 2, it can be seen that the method provided by the present invention can not only promote the conversion of light fractions in naphtha, but also increase the yield of aromatics. At the same time, it can reduce the contact time between the heavy fractions in naphtha and the catalyst, thereby reducing carbon deposition on the catalyst.

[0102] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for continuous reforming of naphtha, characterized in that: The method is carried out in a continuous reforming device, which includes a contact reaction unit and a regenerator connected in sequence, wherein the contact reaction unit is provided with a first reaction zone and a second reaction zone that are kept in communication, and the method comprises: (1) separating naphtha to obtain a light fraction and a heavy fraction; (2) Under hydrogen conditions, the light fraction is introduced into the first reaction zone for a first contact reaction to obtain a reaction product I, and the reaction product I and the heavy fraction are introduced into the second reaction zone for a second contact reaction; the conditions of the first reaction zone include at least: an inlet temperature of 480-580°C, a volume space velocity of 0.3-3h -1 , the hydrogen-to-oil molar ratio is 0.5-3:1; the conditions of the second reaction zone include at least: an inlet temperature of 460-550°C, a volume space velocity of 0.3-3h -1 , the hydrogen-to-oil molar ratio is 0.5-3:1; (3) introducing the regenerated catalyst flowing out of the contact reaction unit into a regenerator for regeneration treatment to obtain a regenerated catalyst, and recycling the regenerated catalyst back to the contact reaction unit; Wherein, the cutting point between the light fraction and the heavy fraction is 100-130°C; The first reaction zone and the second reaction zone each independently include at least one reactor; and according to the flow direction of the liquid phase logistics, the inlet temperature of each reactor in the first reaction zone is higher than the inlet temperature of the most upstream reactor in the second reaction zone.

2. The method according to claim 1, wherein The cutting point between the light fraction and the heavy fraction is 110-130° C. so that the C7 content in the heavy fraction is less than 1% by mass.

3. The method according to claim 1, wherein The cutting point between the light fraction and the heavy fraction is 100-115° C. so that the C6 content in the heavy fraction is less than 1% by mass.

4. The method according to any one of claims 1 to 3, wherein: The contact reaction unit includes at least three reactors connected in series.

5. The method according to claim 4, wherein The reactors connected in series are arranged in parallel or stacked.

6. The method according to claim 4, wherein: The first reaction zone includes a reactor.

7. The method according to claim 6, wherein: The inlet temperature of the reactor in the first reaction zone is 10-50° C. higher than the inlet temperature of the most upstream reactor in the second reaction zone.

8. The method according to claim 7, wherein: The inlet temperature of the reactor in the first reaction zone is 20-40° C. higher than the inlet temperature of the most upstream reactor in the second reaction zone.

9. The method according to claim 4, wherein: The first reaction zone includes two reactors.

10. The method according to claim 9, wherein: The inlet temperature of each reactor in the first reaction zone is 10-40° C. higher than the inlet temperature of the most upstream reactor in the second reaction zone.

11. The method according to claim 10, wherein: The inlet temperature of each reactor in the first reaction zone is 10-25° C. higher than the inlet temperature of the most upstream reactor in the second reaction zone.

12. The method according to any one of claims 1 to 3, wherein: In step (2), the method further comprises: before carrying out the first contact reaction, subjecting the light fraction to a first heating treatment.

13. The method according to claim 12, wherein: In step (2), the method further comprises: before carrying out the second contact reaction, subjecting the reaction product I and the heavy fraction to a second heating treatment.

14. The method according to any one of claims 1 to 3, wherein: The first contact reaction is carried out in a manner such that the light fraction contacts the catalyst in a countercurrent manner or a forward manner in the first reaction zone.

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