Method and system for aromatizing paraffin

Abstract

The invention relates to the technical field of aromatization reaction, in particular to a paraffin aromatization method and system, and the method comprises the following steps: (1) in the presence of an aromatization catalyst, carrying out aromatization reaction on a reaction material after heat exchange to obtain an aromatization reaction product; (2) carrying out heat exchange on the aromatization reaction product and a reaction material to obtain an intermediate material flow converted from the aromatization reaction product and a heat-exchanged reaction material converted from the reaction material; the reaction material comprises a raw material rich in C6 / C7 alkane and the recycle hydrogen; and (3) directly carrying out gas-liquid separation on the intermediate material flow to obtain an aromatic hydrocarbon material flow, recycle hydrogen and hydrogen. According to the method, the hydrogen concentration in the recycle hydrogen and the average pressure of the aromatization reaction are regulated and controlled, so that the activity and selectivity of the aromatization reaction are improved, and meanwhile, the service life of the catalyst is greatly prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of aromatization reaction, and in particular to a method for aromatization of paraffin and a system for aromatization of paraffin. Background Art

[0002] C6 / C7 paraffins are important components in naphtha fractions. Realizing high-value utilization of C6 / C7 paraffins, especially normal paraffins, has always been a technical hotspot and difficulty in the petrochemical industry. Usually, naphtha fractions are converted into high-octane gasoline and aromatics by catalytic reforming. However, the bifunctional reforming catalysts currently used in catalytic reforming, whether platinum-rhenium or platinum-tin series, have poor reactivity and selectivity for dehydrogenation, cyclization and aromatization of C6 / C7 paraffins in naphtha. C6 / C7 paraffins can also be directly used as gasoline blending components, but the proportion of normal paraffins is high and the octane number is low, which limits the blending ratio of C6 / C7 paraffins in gasoline. C6 / C7 normal paraffins can be converted into isoparaffins by the light hydrocarbon isomerization method, but due to the limitation of the thermodynamic equilibrium of the isomerization reaction, the conversion rate of normal paraffins is certain, and the light hydrocarbon isomerization effect is still not ideal. In addition, the relatively mature alkane isomerization technology at home and abroad is only for C5 / C6 alkane isomerization. The C7 alkane isomerization reaction has the problem of low isomerization selectivity, especially when the conversion rate is high, there are more cracking products.

[0003] In summary, there is an urgent need for a new method for aromatization of paraffins, which has high reactivity and selectivity. Summary of the invention

[0004] The purpose of the present invention is to overcome the above technical problems and provide a new method for aromatization of paraffins and a system for aromatization of paraffins. The method improves the activity and selectivity of the aromatization reaction by regulating the hydrogen concentration in the circulating hydrogen and the average pressure of the aromatization reaction, and greatly improves the catalyst life.

[0005] In order to achieve the above object, the present invention provides a method for aromatization of paraffins in a first aspect, the method comprising the following steps:

[0006] (1) in the presence of an aromatization catalyst, subjecting the reaction material after heat exchange to an aromatization reaction to obtain an aromatization reaction product;

[0007] (2) exchanging heat between the aromatization reaction product and a reaction material to obtain an intermediate stream converted from the aromatization reaction product and a heat-exchanged reaction material converted from the reaction material; the reaction material comprises a C6 / C7 alkane-rich feedstock and the circulating hydrogen;

[0008] (3) directly subjecting the intermediate stream to gas-liquid separation to obtain an aromatics stream, circulating hydrogen and hydrogen.

[0009] Preferably, in step (1), the aromatization reaction comprises at least one primary aromatization reaction, preferably comprises N primary aromatization reactions, where N is selected from a natural number of 2-6.

[0010] Preferably, the average pressure of the aromatization reaction is ≤1 MPa, preferably 0.2-0.5 MPa, wherein the average pressure = [inlet pressure of the first aromatization reaction + inlet pressure of the second aromatization reaction + ... + inlet pressure of the Nth aromatization reaction] / N.

[0011] Preferably, in step (2), the temperature of the reaction material is lower than the temperature of the intermediate flow.

[0012] Preferably, the temperature difference between the reaction mass and the intermediate flow is 5-50°C, preferably 10-25°C.

[0013] Preferably, in step (2), the temperature of the circulating hydrogen is lower than the temperature of the reaction materials.

[0014] Preferably, in step (3), the gas-liquid separation includes: a first gas-liquid separation and a second gas-liquid separation, wherein at least a portion of the first gas obtained by the first gas-liquid separation is compressed and deeply cooled in sequence, and then the second gas-liquid separation is performed.

[0015] A second aspect of the present invention provides a system for aromatization of paraffins, the system comprising a heat exchange unit, an aromatization unit, and a gas-liquid separation unit connected to each other;

[0016] The heat exchange unit is connected to the aromatization reaction product outlet of the aromatization unit and the circulating hydrogen outlet of the gas-liquid separation unit, and is used to use the C6 / C7 paraffin-rich feedstock and circulating hydrogen as reaction materials to perform heat exchange with the aromatization reaction product to obtain an intermediate stream converted from the aromatization reaction product and a heat-exchanged reaction material converted from the reaction material;

[0017] The aromatization unit is used to carry out an aromatization reaction on the reaction material after heat exchange in the presence of an aromatization catalyst to obtain the aromatization reaction product;

[0018] The gas-liquid separation unit is connected to the intermediate logistics outlet of the heat exchange unit, and is used to directly perform gas-liquid separation on the intermediate logistics to obtain the aromatics logistics, the circulating hydrogen and hydrogen.

[0019] Preferably, the gas-liquid separation unit comprises: a first gas-liquid separator and a second gas-liquid separator connected to each other, as well as a gas compressor, a liquid booster pump and a deep cooler.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] (1) The method provided by the present invention reduces the temperature of circulating hydrogen and increases the hydrogen concentration of circulating hydrogen by regulating the technical means of gas-liquid separation, greatly improves the catalyst life by delaying the carbon deposition process of the aromatization catalyst, and improves the activity and selectivity of the aromatization reaction. In particular, the temperature of the circulating hydrogen is regulated to be as low as 5°C, and the hydrogen concentration is increased by 5-30% by volume, which is more conducive to increasing the benzene content in the aromatic hydrocarbon stream. At the same time, the method limits the intermediate stream to not need to undergo air cooling, water cooling and other operations, and can directly perform gas-liquid separation, thereby simplifying the process flow;

[0022] (2) The method provided by the present invention also optimizes the average pressure of the aromatization reaction, that is, the average pressure of the aromatization reaction is reduced by 5-30%, thereby effectively improving the conversion rate of the aromatization reaction;

[0023] (3) The method provided by the present invention further ensures that the intermediate stream is directly subjected to gas-liquid separation by limiting the temperature of the reaction material to be lower than the temperature of the intermediate stream and the temperature difference between the reaction material and the intermediate stream.

[0024] (4) The system provided by the present invention optimizes the aromatization reaction process, reduces the number of equipment from the gas-liquid separation tank to the upstream reactor, and facilitates industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the first system for aromatization of paraffin provided by the present invention;

[0026] Figure 2 is a schematic diagram of a second system for aromatization of paraffin provided by the present invention;

[0027] Figure 3 is a schematic diagram of a third system for aromatization of paraffin provided by the present invention;

[0028] Figure 4 is a schematic diagram of a fourth system for aromatization of paraffin provided by the present invention;

[0029] Figure 5 This is a schematic diagram of a system for aromatization of paraffin provided in Comparative Example 1.

[0030] Description of Reference Numerals

[0031] I. Heat exchange unit II. Aromatization unit III. Gas-liquid separation unit

[0032] IV-1, first aromatization reactor IV-2, second aromatization reactor IV-3, third aromatization reactor V-1, first heater V-2, second heater V-3, third heater VI-1, first gas-liquid separator VI-2, second gas-liquid separator VII, gas compressor VIII, liquid booster pump IX, deep cooler X, air cooler XI, water cooler

[0033] 1. Raw materials 2. Circulating hydrogen 3. Reaction materials 4. Reaction materials after heat exchange 5. Primary aromatization reaction product 6. Secondary aromatization reaction product 7. Aromatization reaction product 8. Intermediate logistics 9. First gas 10. First liquid 11. Second gas 12. Second liquid 13. Hydrogen 14. Aromatic hydrocarbon logistics DETAILED DESCRIPTION

[0034] The endpoints and any values ​​of the ranges disclosed in this article 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 endpoint values ​​of each range, the endpoint values ​​of each range and the 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 as specifically disclosed in this article.

[0035] In the present invention, unless otherwise specified, "first", "second" and "Nth" do not indicate a sequence, nor do they limit the materials or steps, but are only used to distinguish that they are not the same material. For example, "first", "second" and "Nth" in "first aromatization catalyst", "second aromatization catalyst" and "Nth aromatization catalyst" are only used to indicate that they are not the same aromatization catalyst; similarly, "first" and "second" in "first gas-liquid separation" and "second gas-liquid separation" are only used to indicate that they are not the same gas-liquid separation.

[0036] The first aspect of the present invention provides a method for aromatizing paraffin, the method comprising the following steps:

[0037] (1) in the presence of an aromatization catalyst, subjecting the reaction material after heat exchange to an aromatization reaction to obtain an aromatization reaction product;

[0038] (2) exchanging heat between the aromatization reaction product and a reaction material to obtain an intermediate stream converted from the aromatization reaction product and a heat-exchanged reaction material converted from the reaction material; the reaction material comprises a C6 / C7 alkane-rich feedstock and the circulating hydrogen;

[0039] (3) directly subjecting the intermediate stream to gas-liquid separation to obtain an aromatics stream, circulating hydrogen and hydrogen.

[0040] The inventors of the present invention have found that, since the aromatization reaction of paraffin is a strong endothermic reaction, a plurality of reactors are usually arranged in the aromatization reaction system of paraffin, and a heating furnace is arranged between the reactors to heat the reaction materials and maintain a high reaction temperature. In the prior art, the high-temperature logistics at the outlet of the last aromatization reactor is first heat exchanged with the raw material and the circulating hydrogen, and then cooled to 40°C by air cooling equipment and water cooling equipment, and then separated by gas and liquid through a gas-liquid separation tank to obtain aromatized oil and by-product hydrogen, and a certain flow of hydrogen is circulated, and the gas-liquid separation tank is the lowest pressure point of the reaction system. That is, in the conventional aromatization reaction method, the number of heat exchange or cooling equipment between the gas-liquid separation tank and the upstream reactor is large, and the pressure drop of the reaction system is large, resulting in a high average reaction pressure; and the aromatization reaction is a volume-enhancing equilibrium reaction, and the higher the average reaction pressure, the lower the reaction conversion rate.

[0041] In the C6 / C7 paraffin aromatization method provided by the present invention, at least a portion of the first gas obtained by the first gas-liquid separation is deeply cooled so that at least a portion of the first gas reaches a new gas-liquid equilibrium state, so that during the first gas-liquid separation process, part or all of the C3 / C4 components present in the first gas are condensed into a liquid phase, and the liquid phase mainly composed of C3 / C4 is stripped off through the second gas-liquid separation to obtain hydrogen with a higher hydrogen concentration, so that the hydrogen concentration in the circulating hydrogen can be increased by 5%-30%, thereby improving the selectivity of the aromatization reaction and the catalyst life.

[0042] In addition, the present invention also reduces the temperature of circulating hydrogen and mixes circulating hydrogen and raw materials into reaction materials. After heat exchange with the reaction materials, the temperature of the outlet logistics of the last aromatization reactor can be reduced to 40°C or lower, and the first gas-liquid separation can be directly performed without cooling by other cooling equipment, and the accuracy requirement of the first gas-liquid separation can be met, that is, most of the carbon four is cooled into the liquid phase, the reaction system process is simplified, and the average pressure of the aromatization reaction is reduced by 5%-30%, thereby improving the conversion rate of the aromatization reaction.

[0043] In the present invention, unless otherwise specified, the aromatization reaction of paraffin refers to the cyclodehydrogenation reaction of C6 / C7 paraffin to generate benzene and toluene, and produce hydrogen as a by-product. The aromatization reaction needs to be carried out under the condition of a certain flow rate of circulating hydrogen. The higher the hydrogen concentration in the circulating hydrogen, the more it helps to improve the catalyst life and reaction selectivity, conversion and other reaction effects. In addition, the aromatization reaction is a volume increase reaction. The lower the average reaction pressure, the higher the reaction conversion rate.

[0044] In some embodiments of the present invention, preferably, in step (1), the aromatization reaction comprises at least one primary aromatization reaction, preferably comprises N-stage aromatization reaction, N being a natural number selected from 2-6; further preferably, the aromatization reaction comprises 3-6-stage aromatization reaction; more preferably, the aromatization reaction comprises 3-stage aromatization reaction.

[0045] In some embodiments of the present invention, preferably, the aromatization reaction process comprises:

[0046] i. After the heat exchange reaction material is first heated, a primary aromatization reaction is performed in the presence of a first aromatization catalyst to obtain a primary aromatization reaction product;

[0047] ii. subjecting the primary aromatization reaction product to a second heating, and then subjecting it to a secondary aromatization reaction in the presence of a second aromatization catalyst to obtain a secondary aromatization reaction product;

[0048] iii. After the (N-1)-stage aromatization reaction product is heated for the Nth time, an N-stage aromatization reaction is carried out in the presence of an N-th aromatization catalyst, and the obtained N-stage aromatization reaction product is used as the aromatization reaction product.

[0049] In the present invention, unless otherwise specified, the temperature ranges of the first heating, the second heating and the Nth heating depend on the temperature ranges of the primary aromatization reaction, the secondary aromatization reaction and the Nth aromatization reaction, respectively.

[0050] In a specific embodiment of the present invention, the aromatization reaction includes a tertiary aromatization reaction, which specifically includes: i. after the reaction material after heat exchange is subjected to a first heating, a primary aromatization reaction is carried out in the presence of a first aromatization catalyst to obtain a primary aromatization reaction product; ii. after the primary aromatization reaction product is subjected to a second heating, a secondary aromatization reaction is carried out in the presence of a second aromatization catalyst to obtain a secondary aromatization reaction product; iii. after the secondary aromatization reaction product is subjected to a third heating, a tertiary aromatization reaction is carried out in the presence of a third aromatization catalyst, and the obtained tertiary aromatization reaction product is used as the aromatization reaction product.

[0051] In some embodiments of the present invention, preferably, the average pressure of the aromatization reaction is ≤1MPa, for example, 0.1MPa, 0.2MPa, 0.3MPa, 0.5MPa, 1MPa, and any value in the range of any two values, preferably 0.2-0.5MPa, wherein the average pressure = [the inlet pressure of the first aromatization reaction + the inlet pressure of the second aromatization reaction + ... + the inlet pressure of the Nth aromatization reaction] / N. The average pressure range that meets the above range is more conducive to improving the conversion rate of the aromatization reaction. In the present invention, the pressure parameters all refer to the gauge pressure.

[0052] In some embodiments of the present invention, preferably, the conditions of the primary aromatization reaction, the secondary aromatization reaction, ..., and the N-stage aromatization reaction each independently include: a temperature of 350-650°C, preferably 450-550°C; a pressure of 0.1-1MPa, preferably 0.2-0.5MPa, and a space velocity of 0.5-15h -1 , preferably 5-10h -1 .

[0053] In the present invention, the type of the aromatization catalyst has a wide range of choices, as long as C6 / C7 paraffins are subjected to cyclodehydrogenation to generate benzene and toluene. In the present invention, the source of the aromatization catalyst has a wide range of choices, and can be obtained by commercial purchase or preparation.

[0054] In the present invention, the first aromatization catalyst, the second aromatization catalyst, ..., the Nth aromatization catalyst may be of the same type or different types, and are preferably the same type.

[0055] In some embodiments of the present invention, preferably, based on the total weight of the aromatization catalyst, the carrier content is 98-99.9wt%, and the active component content is 0.1-2wt%; wherein the carrier includes but is not limited to L molecular sieve, ZSM-5, β molecular sieve, mercerized molecular sieve, and the active component includes but is not limited to platinum, palladium, and gold.

[0056] In some embodiments of the present invention, preferably, in step (2), the temperature of the reaction material is lower than the temperature of the intermediate flow; further preferably, the temperature difference between the reaction material and the intermediate flow is 5-50° C., for example, 5° C., 10° C., 20° C., 25° C., 50° C., and any value in the range of any two values, preferably 10-25° C. This arrangement allows the intermediate flow to be directly separated from gas and liquid without air cooling, water cooling, etc., thereby simplifying the process flow.

[0057] In some embodiments of the present invention, preferably, in step (2), the temperature of the reaction material is ≤50°C, for example, 0°C, 10°C, 20°C, 30°C, 50°C, and any value in the range consisting of any two numerical values, preferably 0-30°C; the temperature of the intermediate logistics is ≤60°C, for example, 0°C, 20°C, 30°C, 40°C, 50°C, 60°C, and any value in the range consisting of any two numerical values, preferably 30-50°C.

[0058] In some embodiments of the present invention, preferably, in step (2), the temperature of the circulating hydrogen is lower than the temperature of the reaction material. In the present invention, unless otherwise specified, the temperature of the circulating hydrogen is lower than the temperature of the raw material.

[0059] In some embodiments of the present invention, preferably, in the reaction material, the volume flow ratio of the raw material to the circulating hydrogen is 1:300-1000, such as 1:300, 1:500, 1:800, 1:1000, and any value in the range of any two values. By adjusting the above volume flow ratio, the temperature of the intermediate material obtained after heat exchange of the reaction material meeting the above limited range meets the temperature range of gas-liquid separation.

[0060] In some embodiments of the present invention, preferably, the temperature of the circulating hydrogen is ≤20°C, preferably 0-20°C; and the temperature of the raw material is 30-50°C.

[0061] In some embodiments of the present invention, preferably, the content of C6 / C7 paraffin in the raw material is 80-99wt%.

[0062] In the present invention, the source of the raw material has a wide selection range. Preferably, the raw material is selected from at least one of reforming raffinate oil, light naphtha and C6 solvent oil.

[0063] In some embodiments of the present invention, preferably, in step (3), the gas-liquid separation includes: a first gas-liquid separation and a second gas-liquid separation; wherein at least part of the first gas obtained by the first gas-liquid separation is compressed and deeply cooled in sequence, and then the second gas-liquid separation is performed. This arrangement allows at least part of the first gas to reach a new gas-liquid equilibrium state, and the C3 / C4 components in the first gas are partially or completely condensed into a liquid phase, and the liquid phase with C3 / C4 as the main component is stripped off by the second gas-liquid separation to obtain hydrogen with a higher hydrogen concentration.

[0064] In some embodiments of the present invention, preferably, the hydrogen concentration in the circulating hydrogen is ≥70 volume %, preferably 80-95 volume %; the C1-C4 alkane content is ≤30 volume %, preferably 5-20 volume %.

[0065] In some embodiments of the present invention, preferably, the benzene content in the aromatic hydrocarbon stream is ≥ 20% by volume, preferably 30-50% by volume.

[0066] In the first embodiment of the present invention, preferably, Figure 1 As shown, the gas-liquid separation process includes: subjecting the intermediate logistics 8 to the first gas-liquid separation, and mixing the obtained first gas 9 and first liquid 10 after respectively being compressed and pressurized, and subjecting the obtained mixture to the second gas-liquid separation after being deeply cooled, and the obtained second gas 11 is divided into the hydrogen 13 and the circulating hydrogen 2, and the obtained second liquid 12 is used as the aromatic hydrocarbon logistics 14.

[0067] In the second embodiment of the present invention, preferably, Figure 2 As shown, the gas-liquid separation process includes: performing the first gas-liquid separation on the intermediate logistics 8 to obtain the first gas 9 and the first liquid 10, dividing the first gas 9 into two parts, one part of which is used as the hydrogen 13, and the remaining part is compressed and deeply cooled in turn, and then subjected to the second gas-liquid separation, the obtained second gas 11 is used as the circulating hydrogen 2, and the obtained second liquid 12 is mixed with the pressurized first liquid 10 as the aromatic hydrocarbon logistics 14.

[0068] In a third embodiment of the present invention, preferably, Figure 3 As shown, the gas-liquid separation process includes: performing the first gas-liquid separation on the intermediate logistics 8 to obtain the first gas 9 and the first liquid 10, compressing and deeply cooling the first gas 9 in turn, and then performing the second gas-liquid separation to obtain the second gas 11, which is divided into the circulating hydrogen 2 and the hydrogen 13, and the second liquid 12 is mixed with the pressurized first liquid 10 as the aromatic hydrocarbon logistics 14.

[0069] In a fourth embodiment of the present invention, preferably, Figure 4 As shown, the gas-liquid separation process includes: performing the first gas-liquid separation on the intermediate logistics 8 to obtain the first gas 9 and the first liquid 10, dividing the first gas 9 into two parts, one part of which is used as the hydrogen 13, and the remaining part is compressed and mixed with the pressurized first liquid 10, and the obtained mixture is deep cooled and then subjected to the second gas-liquid separation, and the obtained second gas 11 is used as the circulating hydrogen 2, and the obtained second liquid 12 is used as the aromatic hydrocarbon logistics 14.

[0070] In the present invention, compared with the above four implementation modes, it can be seen that: by adopting the above first implementation mode, the hydrogen concentrations of the obtained circulating hydrogen / hydrogen gas are the same and relatively high, and the hydrogen also meets the hydrogen concentration requirements of other hydrogen-using devices, but the loads of the gas compressor and the deep cooler are the highest; by adopting the above second implementation mode, the hydrogen concentration of the obtained hydrogen gas is the lowest, and the loads of the gas compressor and the deep cooler are the lowest; by adopting the third implementation mode, the hydrogen concentration of the obtained circulating hydrogen / hydrogen gas is similar to the hydrogen concentration of the circulating hydrogen obtained by the second implementation mode, but the loads of the gas compressor and the deep cooler are higher than those of the second implementation mode; by adopting the above fourth implementation mode, the hydrogen concentration of the obtained circulating hydrogen is the highest, and the hydrogen concentration of the hydrogen gas is relatively low.

[0071] In some embodiments of the present invention, preferably, the temperature of the intermediate logistics is ≤ the temperature of the first gas-liquid separation.

[0072] In some embodiments of the present invention, preferably, the conditions for the first gas-liquid separation include: a temperature of 20-80°C, preferably 30-50°C; and a pressure of 0.1-1 MPa, preferably 0.2-0.5 MPa.

[0073] In some embodiments of the present invention, preferably, the conditions for the second gas-liquid separation include: a temperature of -20 to 20°C, preferably 0-10°C; and a pressure of 0.3-2MPa, preferably 0.5-1MPa.

[0074] A second aspect of the present invention provides a system for aromatization of paraffins, such as Figure 1 As shown, the system includes a connected heat exchange unit I, an aromatization unit II, and a gas-liquid separation unit III;

[0075] The heat exchange unit I is connected to the aromatization reaction product outlet of the aromatization unit II and the circulating hydrogen outlet of the gas-liquid separation unit III, and is used to use the C6 / C7 paraffin-rich raw material 1 and the circulating hydrogen 2 as the reaction material 3 to perform heat exchange with the aromatization reaction product 7 to obtain the intermediate stream 8 converted from the aromatization reaction product 7, and the heat-exchanged reaction material 4 converted from the reaction material 3;

[0076] The aromatization unit II is used to carry out an aromatization reaction on the heat-exchanged reaction material 4 in the presence of an aromatization catalyst to obtain the aromatization reaction product 7;

[0077] The gas-liquid separation unit III is connected to the intermediate logistics outlet of the heat exchange unit I, and is used to directly perform gas-liquid separation on the intermediate logistics 8 to obtain the aromatics logistics 14, the circulating hydrogen 2 and the hydrogen 13.

[0078] In the present invention, there is a wide range of choices for the types of the heat exchange unit, including but not limited to heat exchangers and the like.

[0079] In the present invention, preferably, Figure 1 As shown, the aromatization unit II comprises at least one aromatization reactor connected in series, preferably comprises N aromatization reactors, N is selected from a natural number of 2-6; further preferably, the aromatization unit II comprises 3-6 aromatization reactors connected in series; more preferably, the aromatization unit II comprises 3 aromatization reactors connected in series.

[0080] In the present invention, preferably, Figure 1 As shown, the aromatization unit II further comprises at least one heater, preferably comprises M heaters, M is selected from a natural number of 2-6, and according to the flow direction of the logistics, the (M-1)th heater is arranged before the (N-1)th aromatization reactor.

[0081] In the present invention, unless otherwise specified, the number of heaters is the same as the number of aromatization reactors, and according to the material flow direction, the heaters are arranged before the aromatization reactors.

[0082] In the present invention, Figure 1 As shown, the gas-liquid separation unit III includes: a first gas-liquid separator VI-1 and a second gas-liquid separator IV-2 connected to each other, as well as a gas compressor VII, a liquid booster pump VIII and a deep cooler IX.

[0083] In the first embodiment of the present invention, preferably, Figure 1 As shown, the inlet of the first gas-liquid separator VI-1 is connected to the intermediate logistics outlet of the heat exchange unit I, and is used to perform a first gas-liquid separation on the intermediate logistics 8. The obtained first gas 9 and first liquid 10 enter the gas compressor VII and the liquid booster pump VIII for compression and boosting respectively, and the obtained mixed material enters the deep cooler IX for deep cooling, and then enters the second gas-liquid separator VI-2 for a second gas-liquid separation to obtain a second gas 11 and a second liquid 12, wherein the second gas 11 is divided into two parts, one part is discharged as the hydrogen 13, and the remaining part is returned as the circulating hydrogen 2 and mixed with the reaction material 3; the second liquid 12 is used as the aromatic hydrocarbon logistics 14.

[0084] In the second embodiment of the present invention, preferably, Figure 2 As shown, the inlet of the first gas-liquid separator VI-1 is connected to the intermediate logistics outlet of the heat exchange unit I, and is used to perform a first gas-liquid separation on the intermediate logistics 8 to obtain a first gas 9 and a first liquid 10. The first gas 9 is divided into two parts, one part is discharged as the hydrogen 13, and the remaining part enters the gas compressor VII and the deep cooler IX in turn for compression and deep cooling. The obtained logistics enters the second gas-liquid separator VI-2 for a second gas-liquid separation to obtain a second gas 11 and a second liquid 12; wherein the second gas 11 is used as the circulating hydrogen 2, and the first liquid 10 enters the liquid compression pump VIII for pressurization, and then is mixed with the second liquid 12 as the aromatic hydrocarbon logistics 14.

[0085] In a third embodiment of the present invention, preferably, Figure 3As shown, the inlet of the first gas-liquid separator VI-1 is connected to the intermediate logistics outlet of the heat exchange unit I, and is used to perform a first gas-liquid separation on the intermediate logistics 8 to obtain a first gas 9 and a first liquid 10. The first gas 9 enters the gas compressor VII and the deep cooler IX in turn for compression and deep cooling, and the obtained logistics enters the second gas-liquid separator VI-2 for a second gas-liquid separation to obtain a second gas 11 and a second liquid 12, wherein the second gas 11 is divided into two parts, one part is discharged as hydrogen 13, and the remaining part is returned as the circulating hydrogen 2 and mixed with the reaction material 3, and the first liquid 10 enters the liquid compression pump VIII for pressurization, and then is mixed with the second liquid 12 to serve as the aromatic hydrocarbon logistics 14.

[0086] In a fourth embodiment of the present invention, preferably, Figure 4 As shown, the inlet of the first gas-liquid separator VI-1 is connected to the intermediate logistics outlet of the heat exchange unit I, and is used to perform a first gas-liquid separation on the intermediate logistics 8 to obtain a first gas 9 and a first liquid 10. The first gas 9 is divided into two parts, one part is discharged as the hydrogen 13, and the remaining part enters the gas compressor VII in turn for compression. The obtained logistics is mixed with the first liquid 10 pressurized by the liquid booster pump VIII, and then enters the deep cooler IX and the second gas-liquid separator IV-2 in turn for deep cooling and second gas-liquid separation. The obtained second gas 11 is returned as the circulating hydrogen 2 and mixed into the reaction material 3, and the obtained second liquid 12 is used as the aromatic hydrocarbon logistics 14.

[0087] According to a particularly preferred embodiment of the present invention, a method for aromatizing paraffins comprises the following steps:

[0088] (1) in the presence of an aromatization catalyst, subjecting the reaction material after heat exchange to an aromatization reaction to obtain an aromatization reaction product;

[0089] (2) exchanging heat between the aromatization reaction product and a reaction material to obtain an intermediate stream converted from the aromatization reaction product and a heat-exchanged reaction material converted from the reaction material; the reaction material comprises a C6 / C7 alkane-rich feedstock and the circulating hydrogen;

[0090] (3) directly subjecting the intermediate stream to gas-liquid separation to obtain an aromatics stream, circulating hydrogen and hydrogen;

[0091] The aromatization reaction includes N-stage aromatization reactions, where N is a natural number selected from 2 to 6; the average pressure of the aromatization reaction is 0.2-0.5 MPa, and the average pressure = [the inlet pressure of the first-stage aromatization reaction + the inlet pressure of the second-stage aromatization reaction + ... + the inlet pressure of the N-stage aromatization reaction] / N;

[0092] Wherein, the temperature of the reaction material is lower than the temperature of the intermediate flow, and the temperature difference between the reaction material and the intermediate flow is 10-25°C; the temperature of the circulating hydrogen is lower than the temperature of the reaction material;

[0093] The gas-liquid separation includes: a first gas-liquid separation and a second gas-liquid separation, wherein at least a portion of the first gas obtained by the first gas-liquid separation is compressed and deeply cooled in sequence, and then the second gas-liquid separation is performed.

[0094] The present invention will be described in detail below through examples.

[0095] The raw material is C6 raffinate oil, and the mass composition is shown in Table 1.

[0096] The first aromatization catalyst, the second aromatization catalyst and the third aromatization catalyst are all Pt / KL molecular sieve catalysts, the content of active component (Pt) is 0.5wt%, and the carrier is L-type molecular sieve.

[0097] The process parameters of Examples 1-4 and Comparative Example 1 are all listed in Table 2; the compositions of the circulating hydrogen produced by Examples 1-4 and Comparative Example 1 are all listed in Table 3.

[0098] Example 1

[0099] Systems for aromatization of paraffins such as Figure 1 As shown, the system comprises: a heat exchange unit I, a first heater V-1, a first aromatization reactor IV-1, a second heater V-2, a second aromatization reactor IV-2, a third heater V-3, a third aromatization reactor IV-3, a first gas-liquid separator VI-1, a gas compressor VII and a liquid booster pump VIII respectively arranged at the top and bottom of the first gas-liquid separator VI-1, and a deep cooler IX and a second gas-liquid separator VI-2 connected in sequence;

[0100] Among them, the heat exchange unit I is connected to the second gas-liquid separator IV-2, the third aromatization reactor IV-3 and the first gas-liquid separator IV-1; the deep cooler IX is connected to the gas compressor VII and the liquid booster pump VIII.

[0101] The process for aromatization of paraffins is carried out in the above-mentioned device, comprising:

[0102] (1) After the heat exchange reaction material is first heated, a primary aromatization reaction is carried out in the presence of a first aromatization catalyst (temperature is 500° C., pressure is 0.38 MPa, and space velocity is 7 h -1 ), to obtain a primary aromatization reaction product;

[0103] The primary aromatization product is subjected to a second heating and then to a secondary aromatization reaction in the presence of a second aromatization catalyst (temperature 500°C, pressure 0.33 MPa, space velocity 7 h -1 ), to obtain a secondary aromatization reaction product;

[0104] The secondary aromatization product is subjected to a third heating and then to a tertiary aromatization reaction in the presence of a third aromatization catalyst (temperature 500°C, pressure 0.28 MPa, space velocity 7 h -1 ), the obtained tertiary aromatization reaction product is used as the aromatization reaction product;

[0105] (2) exchanging heat between the aromatization reaction product and the reaction material to obtain an intermediate stream and the reaction material after heat exchange; the reaction material includes C6-rich raffinate oil and circulating hydrogen;

[0106] (3) The intermediate logistics is subjected to a first gas-liquid separation, and the obtained first gas and first liquid are respectively compressed and pressurized and then mixed. The obtained mixture is subjected to deep cooling and then to a second gas-liquid separation. The obtained second gas is divided into hydrogen and circulating hydrogen S1, and the obtained second liquid is used as the aromatic hydrocarbon logistics P1.

[0107] The benzene content in the aromatic hydrocarbon stream P1 is 39.4% by volume.

[0108] Example 2

[0109] Systems for aromatization of paraffins such as Figure 2 As shown, the system includes: a heat exchange unit I, a first heater V-1, a first aromatization reactor IV-1, a second heater V-2, a second aromatization reactor IV-2, a third heater V-3, a third aromatization reactor IV-3, a first gas-liquid separator VI-1 connected in sequence, a gas compressor VII, a deep cooler IX and a second gas-liquid separator VI-2 connected in sequence, and a liquid booster pump VIII connected to the bottom of the first gas-liquid separator VI-1;

[0110] Among them, the heat exchange unit I is connected to the second gas-liquid separator IV-2, the third aromatization reactor IV-3 and the first gas-liquid separator IV-1; the gas compressor VII is connected to the top of the first gas-liquid separator VI-1.

[0111] The process for aromatization of paraffins is carried out in the above-mentioned device, comprising:

[0112] (1) After the heat exchange reaction material is first heated, a primary aromatization reaction is carried out in the presence of a first aromatization catalyst (temperature is 500° C., pressure is 0.38 MPa, and space velocity is 7 h -1 ), to obtain a primary aromatization reaction product;

[0113] The primary aromatization product is subjected to a second heating and then to a secondary aromatization reaction in the presence of a second aromatization catalyst (temperature 500°C, pressure 0.33 MPa, space velocity 7 h -1 ), to obtain a secondary aromatization reaction product;

[0114] The secondary aromatization product is subjected to a third heating and then to a tertiary aromatization reaction in the presence of a third aromatization catalyst (temperature 500°C, pressure 0.28 MPa, space velocity 7 h -1 ), the obtained tertiary aromatization reaction product is used as the aromatization reaction product;

[0115] (2) exchanging heat between the aromatization reaction product and the reaction material to obtain an intermediate stream and the reaction material after heat exchange; the reaction material includes C6-rich raffinate oil and circulating hydrogen;

[0116] (3) The intermediate logistics is subjected to a first gas-liquid separation to obtain a first gas and a first liquid. The first gas is divided into two parts, one part is used as hydrogen, and the remaining part is compressed and deeply cooled in sequence, and then subjected to a second gas-liquid separation. The obtained second gas is used as circulating hydrogen S2, and the obtained second liquid is mixed with the pressurized first liquid to serve as the aromatic hydrocarbon logistics P2.

[0117] The benzene content in the aromatic hydrocarbon stream P2 is 39.0% by volume.

[0118] Example 3

[0119] Systems for aromatization of paraffins such as Figure 3 As shown, the system includes: a heat exchange unit I, a first heater V-1, a first aromatization reactor IV-1, a second heater V-2, a second aromatization reactor IV-2, a third heater V-3, a third aromatization reactor IV-3, a first gas-liquid separator VI-1 connected in sequence, a gas compressor VII, a deep cooler IX and a second gas-liquid separator VI-2 connected in sequence, and a liquid booster pump VIII connected to the bottom of the first gas-liquid separator VI-1;

[0120] Among them, the heat exchange unit I is connected to the second gas-liquid separator IV-2, the third aromatization reactor IV-3 and the first gas-liquid separator IV-1; the gas compressor VII is connected to the top of the first gas-liquid separator VI-1.

[0121] The process for aromatization of paraffins is carried out in the above-mentioned device, comprising:

[0122] (1) After the heat exchange reaction material is first heated, a primary aromatization reaction is carried out in the presence of a first aromatization catalyst (temperature is 500° C., pressure is 0.38 MPa, and space velocity is 7 h -1), to obtain a primary aromatization reaction product;

[0123] The primary aromatization product is subjected to a second heating and then to a secondary aromatization reaction in the presence of a second aromatization catalyst (temperature 500°C, pressure 0.33 MPa, space velocity 7 h -1 ), to obtain a secondary aromatization reaction product;

[0124] The secondary aromatization product is subjected to a third heating and then to a tertiary aromatization reaction in the presence of a third aromatization catalyst (temperature 500°C, pressure 0.28 MPa, space velocity 7 h -1 ), the obtained tertiary aromatization reaction product is used as the aromatization reaction product;

[0125] (2) exchanging heat between the aromatization reaction product and the reaction material to obtain an intermediate stream and the reaction material after heat exchange; the reaction material includes C6-rich raffinate oil and circulating hydrogen;

[0126] (3) The intermediate logistics is subjected to a first gas-liquid separation to obtain a first gas and a first liquid. The first gas is compressed and deeply cooled in sequence, and then subjected to a second gas-liquid separation. The obtained second gas is divided into circulating hydrogen S3 and hydrogen. The obtained second liquid is mixed with the pressurized first liquid to serve as the aromatics logistics P3.

[0127] Among them, the benzene content in the above aromatic hydrocarbon logistics P3 is 39.0 volume %.

[0128] Example 4

[0129] Systems for aromatization of paraffins such as Figure 4 As shown, the system comprises: a heat exchange unit I, a first heater V-1, a first aromatization reactor IV-1, a second heater V-2, a second aromatization reactor IV-2, a third heater V-3, a third aromatization reactor IV-3, a first gas-liquid separator VI-1, a gas compressor VII and a liquid booster pump VIII respectively arranged at the top and bottom of the first gas-liquid separator VI-1, and a deep cooler IX and a second gas-liquid separator VI-2 connected in sequence;

[0130] Among them, the heat exchange unit I is connected to the second gas-liquid separator IV-2, the third aromatization reactor IV-3 and the first gas-liquid separator IV-1; the deep cooler IX is connected to the gas compressor VII and the liquid booster pump VIII.

[0131] The process for aromatization of paraffins is carried out in the above-mentioned device, comprising:

[0132] (1) After the heat exchange reaction material is first heated, a primary aromatization reaction is carried out in the presence of a first aromatization catalyst (temperature is 500° C., pressure is 0.38 MPa, and space velocity is 7 h -1 ), to obtain a primary aromatization reaction product;

[0133] The primary aromatization product is subjected to a second heating and then to a secondary aromatization reaction in the presence of a second aromatization catalyst (temperature 500°C, pressure 0.33 MPa, space velocity 7 h -1 ), to obtain a secondary aromatization reaction product;

[0134] The secondary aromatization product is subjected to a third heating and then to a tertiary aromatization reaction in the presence of a third aromatization catalyst (temperature 500°C, pressure 0.28 MPa, space velocity 7 h -1 ), the obtained tertiary aromatization reaction product is used as the aromatization reaction product;

[0135] (2) exchanging heat between the aromatization reaction product and the reaction material to obtain an intermediate stream and the reaction material after heat exchange; the reaction material includes C6-rich raffinate oil and circulating hydrogen;

[0136] (3) The intermediate logistics is subjected to a first gas-liquid separation to obtain a first gas and a first liquid. The first gas is divided into two parts, one part of which is used as the hydrogen gas, and the remaining part is compressed and mixed with the pressurized first liquid. The obtained mixture is deeply cooled and subjected to a second gas-liquid separation. The obtained second gas is used as circulating hydrogen S4, and the obtained second liquid is used as the aromatic hydrocarbon logistics P4.

[0137] The benzene content in the aromatic hydrocarbon stream P4 is 39.6% by volume.

[0138] Comparative Example 1

[0139] Systems for aromatization of paraffins such as Figure 5 As shown, the system comprises: a heat exchange unit I, a first heater V-1, a first aromatization reactor IV-1, a second heater V-2, a second aromatization reactor IV-2, a third heater V-3, a third aromatization reactor IV-3, a first gas-liquid separator VI-1, and a gas compressor VII and a liquid booster pump VIII respectively arranged at the top and bottom of the first gas-liquid separator VI-1;

[0140] Among them, the heat exchange unit I connects the first gas-liquid separator IV-1, the third aromatization reactor IV-3 and the first gas-liquid separator IV-1; an air cooler X and a water cooler XI are also arranged on the pipeline connecting the heat exchange unit I and the first gas-liquid separation unit VI-1.

[0141] The method for aromatizing paraffin is carried out in the above system, and the method comprises:

[0142] (1) After the heat exchange reaction material is first heated, a primary aromatization reaction is carried out in the presence of a first aromatization catalyst (temperature is 500° C., pressure is 0.44 MPa, and space velocity is 7 h -1 ), to obtain a primary aromatization reaction product;

[0143] The primary aromatization product is subjected to a second heating and then to a secondary aromatization reaction in the presence of a second aromatization catalyst (temperature 500°C, pressure 0.39 MPa, space velocity 7 h -1 ), to obtain a secondary aromatization reaction product;

[0144] The secondary aromatization product is subjected to a third heating and then to a tertiary aromatization reaction in the presence of a third aromatization catalyst (temperature 500°C, pressure 0.34 MPa, space velocity 7 h -1 ), the obtained tertiary aromatization reaction product is used as the aromatization reaction product;

[0145] (2) exchanging heat between the aromatization reaction product and the reaction material to obtain an intermediate stream and the reaction material after heat exchange; the reaction material includes C6-rich raffinate oil and circulating hydrogen;

[0146] (3) The intermediate logistics is sequentially air-cooled and water-cooled, and then subjected to a first gas-liquid separation. The first gas obtained is compressed, part of which is discharged as hydrogen, and the remaining part is returned to the reaction material as circulating hydrogen DS1; the first liquid obtained is pressurized as the aromatic hydrocarbon logistics DP1.

[0147] The benzene content in the aromatic hydrocarbon stream DP1 is 36.6% by volume.

[0148] Table 1

[0149] <![CDATA[Composition of C6 raffinate]]> Composition, wt% 2,2-Dimethylbutane 0.63 2,3-Dimethylbutane 2.79 2-Methylpentane 17.12 3-Methylpentane 23.22 n-Hexane 48.37 2,2-Dimethylpentane 1.74 Methylcyclopentane 4.41 2,4-Dimethylpentane 0.91 other 0.81 total 100.00

[0150] Table 2

[0151]

[0152]

[0153] Note: Hydrogen to oil ratio* - the volume flow ratio of circulating hydrogen and raw materials in the reaction mass.

[0154] Table 2

[0155]

[0156] Note: Hydrogen to oil ratio* - the volume flow ratio of circulating hydrogen and raw materials in the reaction mass.

[0157] Table 3

[0158]

[0159] It can be seen from the data in Table 2 that the temperature of the intermediate logistics of Examples 1-4 is 40°C, and gas-liquid separation can be directly performed, while the temperature of the intermediate logistics of Comparative Example 1 is 91°C, which is relatively high and gas-liquid separation cannot be performed directly.

[0160] Compared with Examples 1-4, the process adopted in Comparative Example 1 requires an additional air cooler and a water cooler to be directly provided between the heat exchange unit and the first gas-liquid separator. The pressure drop of the two devices is 0.3 MPa respectively, thereby increasing the average pressure of the aromatization reaction.

[0161] The average pressure of the aromatization reaction of Examples 1-4 is 0.33 MPa, the average pressure of the aromatization reaction of Comparative Example 1 is 0.39 MPa, and the average pressure of the aromatization reaction of Examples 1-4 is 15.4% lower than that of Comparative Example 1. Therefore, by adopting the process scheme of Examples 1-4, the number of equipment in the reaction system is less, the average pressure of the aromatization reaction is lower, and the conversion rate of the aromatization reaction can be improved.

[0162] It can be seen from the data in Table 3 that the hydrogen concentrations in the circulating hydrogen of Examples 1-4 are 88.1 volume %, 87.8 volume %, 87.8 volume % and 88.3 volume %, respectively, while the hydrogen concentration in the circulating hydrogen of Comparative Example 1 is 76.3 volume %. Compared with Comparative Example 1, the hydrogen concentrations in the circulating hydrogen of Examples 1-4 are increased by 15.5%, 15.1%, 15.1% and 15.7%, respectively. Therefore, by adopting the process scheme of Examples 1-4, the concentration of hydrogen in the circulating hydrogen is higher, which can improve the selectivity and catalyst life of the aromatization reaction.

[0163] In Example 1, the hydrogen concentrations of the circulating hydrogen / hydrogen gas are the same and relatively high, and the hydrogen meets the hydrogen purity requirements of other hydrogen-using devices, but the loads of the gas compressor and the deep cooler are the highest; in Example 2, the hydrogen concentration of the hydrogen is the lowest, and the loads of the gas compressor and the deep cooler are the lowest; in Example 3, the hydrogen concentration of the circulating hydrogen / hydrogen gas is similar to that of the circulating hydrogen in Example 2, but the loads of the gas compressor and the deep cooler are higher than those in Example 2; in Example 4, the hydrogen concentration of the circulating hydrogen is the highest, and the hydrogen concentration of the hydrogen gas is relatively low.

[0164] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for aromatizing paraffins, characterized in that: The method comprises the following steps: (1) in the presence of an aromatization catalyst, subjecting the heat-exchanged reaction material (4) to an aromatization reaction to obtain an aromatization reaction product (7); (2) exchanging heat between the aromatization reaction product (7) and the reaction material (3) to obtain an intermediate stream (8) converted from the aromatization reaction product (7) and the heat-exchanged reaction material (4) converted from the reaction material (3); the reaction material (3) comprises a C6 / C7 paraffin-rich feedstock (1) and the circulating hydrogen (2); (3) The intermediate stream (8) is directly subjected to gas-liquid separation to obtain an aromatic stream (14), circulating hydrogen (2) and hydrogen (13).

2. The method according to claim 1, wherein: In step (1), the aromatization reaction comprises at least one primary aromatization reaction, preferably comprises N-stage aromatization reactions, where N is a natural number selected from 2 to 6; And / or, the aromatization reaction process comprises: i. After the heat exchange reaction material (4) is subjected to a first heating, a primary aromatization reaction is carried out in the presence of a first aromatization catalyst to obtain a primary aromatization reaction product; ii. subjecting the primary aromatization reaction product to a second heating, and then subjecting it to a secondary aromatization reaction in the presence of a second aromatization catalyst to obtain a secondary aromatization reaction product; iii. After the (N-1)-stage aromatization reaction product is heated for the Nth time, an N-stage aromatization reaction is carried out in the presence of an N-th aromatization catalyst, and the obtained N-stage aromatization reaction product is used as the aromatization reaction product.

3. The method according to claim 2, wherein: The average pressure of the aromatization reaction is ≤1 MPa, preferably 0.2-0.5 MPa, wherein the average pressure = [the inlet pressure of the first aromatization reaction + the inlet pressure of the second aromatization reaction + ... + the inlet pressure of the Nth aromatization reaction] / N; And / or, the conditions of the primary aromatization reaction, the secondary aromatization reaction, ..., and the N-stage aromatization reaction independently include: a temperature of 350-650° C., preferably 450-550° C.; a pressure of 0.1-1 MPa, preferably 0.2-0.5 MPa; a space velocity of 0.5-15 h -1 , preferably 5-10h -1 .

4. The method according to any one of claims 1 to 3, wherein: In step (2), the temperature of the reaction material (3) is lower than the temperature of the intermediate stream (8); and / or, the temperature difference between the reaction mass (3) and the intermediate stream (8) is 5-50°C, preferably 10-25°C; And / or, the temperature of the reaction mass (3) is ≤50°C, preferably 0-30°C; the temperature of the intermediate flow (8) is ≤60°C, preferably 30-50°C.

5. The method according to any one of claims 1 to 4, wherein: In step (2), the temperature of the circulating hydrogen (2) is lower than the temperature of the reaction material (3); and / or, in the reaction material (3), the volume flow ratio of the raw material (1) to the circulating hydrogen (2) is 1:300-1000; and / or, the temperature of the circulating hydrogen (2) is ≤20°C, preferably 0-10°C; the temperature of the raw material (1) is 30-50°C; and / or, in the raw material (1), the content of C6 / C7 paraffins is 80-99 wt%; And / or, the raw material is selected from at least one of reforming raffinate oil, light naphtha and C6 solvent oil.

6. The method according to any one of claims 1 to 5, wherein: In step (3), the gas-liquid separation includes: a first gas-liquid separation and a second gas-liquid separation, wherein at least a portion of the first gas obtained by the first gas-liquid separation is compressed and deeply cooled in sequence, and then the second gas-liquid separation is performed; and / or, the hydrogen concentration in the circulating hydrogen (2) is ≥70% by volume, preferably 80-95% by volume; the C1-C4 alkane content is ≤30% by volume, preferably 5-20% by volume; And / or, the benzene content in the aromatic hydrocarbon stream (14) is ≥ 20% by volume, preferably 30-50% by volume.

7. The method according to claim 6, wherein: The gas-liquid separation process comprises: a) subjecting the intermediate stream (8) to the first gas-liquid separation, and mixing the obtained first gas (9) and first liquid (10) after respectively being compressed and pressurized, and subjecting the obtained mixed material to the second gas-liquid separation after being deeply cooled, and the obtained second gas (11) is separated into the hydrogen (13) and the circulating hydrogen (2), and the obtained second liquid (12) is used as the aromatic hydrocarbon stream (14); or, b) subjecting the intermediate stream (8) to the first gas-liquid separation to obtain the first gas (9) and the first liquid (10), dividing the first gas (9) into two parts, one part of which is used as the hydrogen (13), and the remaining part is subjected to the second gas-liquid separation after being compressed and deeply cooled in sequence, and the obtained second gas (11) is used as the circulating hydrogen (2), and the obtained second liquid (12) is mixed with the pressurized first liquid (10) to serve as the aromatics stream (14); or, c) subjecting the intermediate stream (8) to the first gas-liquid separation to obtain the first gas (9) and the first liquid (10); subjecting the first gas (9) to the first compression and deep cooling in sequence, and then subjecting the first gas (9) to the second gas-liquid separation to obtain the second gas (11), which is separated into the circulating hydrogen (2) and the hydrogen (13); and the obtained second liquid (12) is mixed with the pressurized first liquid (10) to form the aromatics stream (14); or d) subjecting the intermediate stream (8) to the first gas-liquid separation to obtain the first gas (9) and the first liquid (10); dividing the first gas (9) into two parts, one part of which is used as the hydrogen (13); and the remaining part is compressed and mixed with the pressurized first liquid (10); the obtained mixture is subjected to the deep cooling and then subjected to the second gas-liquid separation to obtain the second gas (11) as the circulating hydrogen (2); and the obtained second liquid (12) is used as the aromatic hydrocarbon stream (14); and / or, the temperature of the intermediate stream (8) is ≤ the temperature of the first gas-liquid separation; And / or, the first gas-liquid separation conditions include: temperature of 20-80°C, preferably 30-50°C; pressure of 0.1-1MPa, preferably 0.2-0.5MPa; And / or, the conditions for the second gas-liquid separation include: a temperature of -20 to 20°C, preferably 0-10°C; and a pressure of 0.3-2MPa, preferably 0.5-1MPa.

8. A system for aromatization of paraffins, characterized in that: The system comprises a connected heat exchange unit (I), an aromatization unit (II), and a gas-liquid separation unit (III); The heat exchange unit (I) is connected to the aromatization reaction product outlet of the aromatization unit (II) and the circulating hydrogen outlet of the gas-liquid separation unit (III), and is used to use the C6 / C7 paraffin-rich raw material (1) and the circulating hydrogen (2) as the reaction material (3) to perform heat exchange with the aromatization reaction product (7), so as to obtain the intermediate stream (8) converted from the aromatization reaction product (7), and the heat-exchanged reaction material (4) converted from the reaction material (3); The aromatization unit (II) is used to carry out an aromatization reaction on the reaction material (4) after heat exchange in the presence of an aromatization catalyst to obtain the aromatization reaction product (7); The gas-liquid separation unit (III) is connected to the intermediate logistics outlet of the heat exchange unit (I) and is used to directly perform gas-liquid separation on the intermediate logistics (8) to obtain the aromatics logistics (14), the circulating hydrogen (2) and hydrogen (13).

9. The system according to claim 8, wherein: The aromatization unit (II) comprises at least one aromatization reactor connected in series, preferably comprises N aromatization reactors, wherein N is selected from a natural number of 2-6; The aromatization unit (II) further comprises at least one heater, preferably comprises M heaters, M is selected from a natural number of 2-6, and according to the flow direction of the logistics, the (M-1)th heater is arranged before the (N-1)th aromatization reactor.

10. The system according to claim 8 or 9, wherein: The gas-liquid separation unit (III) comprises: a first gas-liquid separator (VI-1) and a second gas-liquid separator (IV-2) connected to each other, as well as a gas compressor (VII), a liquid booster pump (VIII) and a deep cooler (IX); Preferably, the inlet of the first gas-liquid separator (VI-1) is connected to the intermediate logistics outlet of the heat exchange unit (I), and is used to perform a first gas-liquid separation on the intermediate logistics (8); the obtained first gas (9) and first liquid (10) enter the gas compressor (VII) and the liquid booster pump (VIII) for compression and boosting respectively, and the obtained mixed material enters the deep cooler (IX) for deep cooling, and then enters the second gas-liquid separator (VI-2) for a second gas-liquid separation to obtain a second gas (11) and a second liquid (12), wherein the second gas (11) is divided into two parts, one part is discharged as the hydrogen (13), and the remaining part is returned as the circulating hydrogen (2) and mixed with the reaction material (3); the second liquid (12) is used as the aromatic hydrocarbon logistics (14); or, The inlet of the first gas-liquid separator (VI-1) is connected to the intermediate logistics outlet of the heat exchange unit (I), and is used to perform a first gas-liquid separation on the intermediate logistics (8) to obtain a first gas (9) and a first liquid (10). The first gas (9) is divided into two parts, one part is discharged as the hydrogen (13), and the remaining part enters the gas compressor (VII) and the deep cooler (IX) in sequence for compression and deep cooling. The obtained logistics enters the second gas-liquid separator (VI-2) for a second gas-liquid separation to obtain a second gas (11) and a second liquid (12); wherein the second gas (11) is used as the circulating hydrogen (2), and the first liquid (10) is pressurized by entering the liquid compression pump (VIII) and then mixed with the second liquid (12) to serve as the aromatic hydrocarbon logistics (14); or, The inlet of the first gas-liquid separator (VI-1) is connected to the intermediate logistics outlet of the heat exchange unit (I), and is used to perform a first gas-liquid separation on the intermediate logistics (8) to obtain a first gas (9) and a first liquid (10); the first gas (9) enters the gas compressor (VII) and the deep cooler (IX) in sequence for compression and deep cooling; the obtained logistics enters the second gas-liquid separator (VI-2) for a second gas-liquid separation to obtain a second gas (11) and a second liquid (12); wherein the second gas (11) is divided into two parts, one part is discharged as hydrogen (13), and the remaining part is returned as the circulating hydrogen (2) and mixed with the reaction material (3); the first liquid (10) enters the liquid compression pump (VIII) for pressurization, and then is mixed with the second liquid (12) to serve as the aromatic hydrocarbon logistics (14); or, The inlet of the first gas-liquid separator (VI-1) is connected to the intermediate logistics outlet of the heat exchange unit (I), and is used to perform a first gas-liquid separation on the intermediate logistics (8) to obtain a first gas (9) and a first liquid (10). The first gas (9) is divided into two parts, one part is discharged as the hydrogen (13), and the remaining part enters the gas compressor (VII) for compression. The obtained logistics is mixed with the first liquid (10) pressurized by the liquid booster pump (VIII), and then enters the deep cooler (IX) and the second gas-liquid separator (IV-2) in sequence for deep cooling and second gas-liquid separation. The obtained second gas (11) is returned as the circulating hydrogen (2) and mixed into the reaction material (3), and the obtained second liquid (12) is used as the aromatic hydrocarbon logistics (14).

Images