Method and system for preparing low-carbon olefin by combining microwave cracking with catalytic cracking

Abstract

The invention relates to the technical field of crude oil cracking, and discloses a method and a system for preparing low-carbon olefin by combining microwave cracking with catalytic cracking, and the method comprises the following steps: hydrotreating a petroleum raw material to obtain a hydrogenated petroleum raw material; carrying out vaporization treatment on the hydrogenated petroleum raw material to obtain a vapor phase and a liquid phase; carrying out microwave cracking on the steam phase in the presence of an electromagnetic wave absorber under a microwave cracking condition to obtain microwave cracking gas; under the catalytic cracking condition, the liquid phase is subjected to catalytic cracking in the presence of a catalyst, and catalytic cracking gas is obtained. According to the method, microwave cracking and catalytic cracking are combined, so that the utilization rate of the petroleum raw material is increased, the problem of easy coking in the preparation process of the low-carbon olefin is effectively solved, the yield of the low-carbon olefin is increased, and the stable operation period is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of crude oil cracking, and in particular to a method and system for preparing light olefins by combining microwave cracking with catalytic cracking. Background Art

[0002] Low-carbon olefins are a general term for unsaturated hydrocarbons with a carbon content of four or less. In industry, low-carbon olefins are organic chemical raw materials with high economic value.

[0003] Currently, one of the main methods for producing low-carbon olefins is the tubular cracking furnace steam cracking method. However, the main raw material for producing low-carbon olefins using the steam cracking method is refined oil such as naphtha, resulting in high raw material costs.

[0004] In order to reduce the cost of raw materials for preparing light olefins by cracking, the development of a process route that directly uses crude oil as cracking raw material has become a research hotspot in this field in recent years. However, researchers have found that when crude oil is directly used as raw material using the existing process, some non-volatile components in the crude oil that are difficult to be gasified are entrained to the radiation section with the mixed gas flow, which can easily cause coking deposition in the radiation section and even block the radiation section. On the one hand, it causes the problem of short stable operation time, and on the other hand, it also has an adverse effect on the yield of cracking products. Moreover, frequent shutdowns to clean the cracking furnace also cause problems such as increased production costs. Although some studies have found that the separation of light components in crude oil for cracking can slow down reactor coking to a certain extent through certain pretreatment methods, such a treatment method is prone to low raw material utilization and cannot fully utilize resources.

[0005] Therefore, it is very important for the development of the light olefin industry and the improvement of corporate benefits to develop a crude oil cracking process that can achieve a high yield of light olefins at a low raw material cost, while slowing down the coking of the cracking furnace and improving production efficiency and resource utilization. Summary of the invention

[0006] The purpose of the present invention is to overcome the problems of easy coking, low carbon olefin yield and resource utilization in the cracking process of preparing low carbon olefins by cracking petroleum raw materials in the prior art, and provide a method and system for preparing low carbon olefins by combining microwave cracking with catalytic cracking. The method provided by the present invention can obtain low carbon olefins with a higher yield, and the reactor coking speed is slow, the stable operation time is long, and it also has the advantages of low carbon emissions.

[0007] In order to achieve the above-mentioned object, the first aspect of the present invention provides a method for preparing light olefins by combining microwave cracking with catalytic cracking, characterized in that the method comprises: hydrogenating a petroleum feedstock to obtain a hydrogenated petroleum feedstock; vaporizing the hydrogenated petroleum feedstock to obtain a vapor phase and a liquid phase; under microwave cracking conditions, the vapor phase is subjected to microwave cracking in the presence of an electromagnetic wave absorber to obtain microwave cracking gas; under catalytic cracking conditions, the liquid phase is subjected to catalytic cracking in the presence of a catalyst to obtain catalytic cracking gas.

[0008] The second aspect of the present invention provides a system for preparing light olefins by combining microwave cracking with catalytic cracking, characterized in that the system comprises: a hydrogenation unit, a vaporization unit, a microwave cracking unit and a catalytic cracking unit; wherein:

[0009] The hydrogenation unit is used to hydrogenate the petroleum feedstock to obtain the hydrogenated petroleum feedstock;

[0010] The vaporization unit is used to vaporize the hydrogenated petroleum feedstock to obtain a vapor phase and a liquid phase;

[0011] The microwave cracking unit is used to perform microwave cracking on the vapor phase in the presence of an electromagnetic wave absorber under microwave cracking conditions to obtain microwave cracking gas;

[0012] The catalytic cracking unit is used to catalytically crack the liquid phase in the presence of a catalyst under catalytic cracking conditions to obtain catalytic cracking gas.

[0013] The third aspect of the present invention provides the use of the method described in the first aspect and / or the system described in the second aspect in improving the target product yield, selectivity and / or extending the operation cycle of preparing light olefins by direct cracking of crude oil.

[0014] Through the time-line number technical solution, the present invention can at least achieve the following beneficial effects:

[0015] (1) The present invention adopts a combination of microwave cracking and catalytic cracking to prepare light olefins, making full use of petroleum raw materials, especially non-asphaltene components in crude oil, and improving the utilization rate of raw materials. At the same time, the method can also improve the yield of light olefins and extend the stable operation cycle.

[0016] (2) The heat source of the present invention can be electrically heated, and the microwave reactor uses electrical energy, which can effectively save energy and reduce carbon emissions.

[0017] (3) Compared with conventional thermal cracking, the microwave cracking of the present invention can improve the selectivity of light olefins and reduce the cracking temperature; at the same time, it can also reduce carbon emissions and energy consumption. In a preferred case, the preferred microwave absorbing material (such as silicon carbide) of the present invention can further reduce the cracking temperature, while promoting the rapid cracking of light components, so that more light components are converted into light olefins.

[0018] (4) The present invention adopts a specific pretreatment method and a combination of microwave cracking and catalytic cracking to further improve the yield of the target product and extend the stable operation period when light olefins are prepared using crude oil as a raw material. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the system for preparing light olefins in Example 1 of the present invention.

[0020] Description of Reference Numerals

[0021] 1-hydrogenation unit, 2-vaporization unit, 3-microwave cracking unit, 3-fluidized reactor, 4-catalytic cracking reactor, 5-catalytic cracking regenerator, 6-deep catalytic cracking unit, 7-catalytic cracking unit, 8-separation unit. DETAILED DESCRIPTION

[0022] 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.

[0023] In the present invention, unless otherwise specified, the external heating heat source in each step adopts electric energy. The use of green electricity can achieve zero carbon emissions of the production device.

[0024] In the present invention, unless otherwise specified, "petroleum raw materials" refers to crude oil and crude oil derivatives, such as refinery oil products obtained through refining. "Crude oil" refers to unrefined petroleum. API values ​​(also called API degrees) can usually be used to characterize the relative density of petroleum raw materials (such as crude oil and petroleum products). As the API value increases, the relative density of the petroleum raw materials decreases.

[0025] In the present invention, unless otherwise specified, when the temperature of water vapor is higher than 100° C., the water vapor is high-pressure water vapor, that is, the temperature of the water vapor is the saturation temperature of water vapor under high pressure.

[0026] The first aspect of the present invention provides a method for preparing light olefins by combining microwave cracking with catalytic cracking, characterized in that the method comprises: hydrogenating a petroleum feedstock to obtain a hydrogenated petroleum feedstock; vaporizing the hydrogenated petroleum feedstock to obtain a vapor phase and a liquid phase; under microwave cracking conditions, the vapor phase is subjected to microwave cracking in the presence of an electromagnetic wave absorber to obtain microwave cracking gas; under catalytic cracking conditions, the liquid phase is subjected to catalytic cracking in the presence of a catalyst to obtain catalytic cracking gas.

[0027] According to the present invention, preferably, the API of the petroleum raw material is not less than 18 (for example, 18, 20, 23, 25, 28, 30, 35, 40, 50, 60, 70, 80, 90, 100, 150, 200, 300, 400, and the range formed by any two of the above points), preferably 20-60, and more preferably 25-58 (for example, 25, 28, 30, 32, 35, 38, 40, 42, 45, 48, 50, 52, 55, 58, and the range formed by any two of the above points).

[0028] According to the present invention, preferably, the petroleum feedstock includes at least one of crude oil, light naphtha, naphtha, diesel and hydrogenated tail oil.

[0029] More preferably, the crude oil includes at least one of light crude oil, crude oil with a final distillation point higher than 600° C. and lower than 700° C., and dehydrated and desalted crude oil.

[0030] According to the present invention, the hydroprocessing method includes: preheating the petroleum raw material and mixing it with hydrogen, and then performing a hydrogenation reaction under hydrogenation conditions. In the present invention, the purpose of the hydroprocessing is to lighten the petroleum raw material, thereby increasing the content of raw materials that can be used to obtain light olefins through microwave cracking, thereby improving the utilization rate of the raw materials and the yield of light olefins.

[0031] According to the present invention, preferably, the petroleum feedstock is preheated to 100-400°C and then mixed with hydrogen. More preferably, it is preheated to 150-350°C.

[0032] According to the present invention, preferably, the weight ratio of the preheated petroleum feedstock to hydrogen is 100-500:1, preferably 200-400:1.

[0033] According to the present invention, preferably, the hydrogenation conditions include: hydrogenation temperature 200-500° C., hydrogenation pressure 1-5 MPa.

[0034] More preferably, the hydrogenation conditions include: hydrogenation temperature of 200-350° C. and hydrogenation pressure of 2-4 MPa.

[0035] In the present invention, the vaporization treatment step can adopt any vaporization method applicable to the process of preparing light olefins from petroleum raw materials in the art, for example, it can be at least one of stripping, flash evaporation, and cyclone separation. The inventor accidentally discovered in the study that the use of cyclone separation can incorporate more hydrocarbon raw materials that can be used to obtain light olefins by microwave cracking into the vapor phase. Therefore, in the method provided by the present invention, it is preferred to use cyclone separation for vaporization treatment.

[0036] According to the present invention, preferably, the vaporization treatment comprises: mixing the first water vapor with the hydrogenated petroleum feedstock and then introducing the mixture into a cyclone separator for cyclone separation.

[0037] According to the present invention, preferably, the weight ratio of the first water vapor to the hydrogenated petroleum feedstock is 0.5-1.5:1, preferably 0.5-1:1.

[0038] Preferably, the temperature of the first water vapor is 180-400°C, preferably 200-350°C.

[0039] Preferably, the separation efficiency of the cyclone separator does not exceed 90%, preferably 50-90%, and more preferably 65-85%. The separation efficiency refers to the percentage of the weight of the vapor phase separated from the hydrogenated petroleum raw material for subsequent treatment to the weight of the hydrogenated petroleum raw material fed. For example, a separation efficiency of 20% means that 100g of hydrogenated petroleum raw material is fed and 20g of vapor phase is finally separated.

[0040] Preferably, the temperature of the cyclone separation is 250-550°C, preferably 300-500°C.

[0041] More preferably, the API value of the vapor phase is increased by 3-33 (e.g., 3, 5, 8, 10, 15, 20, 25, 30, 33, and a range consisting of any two of the above) compared to the petroleum feedstock.

[0042] According to the present invention, preferably, the microwave cracking method includes: introducing the steam phase and the optional second water vapor into a microwave cracking unit, and performing a microwave cracking reaction in the presence of an electromagnetic wave absorber. "Optional" means that during the microwave cracking process, the second water vapor can be selectively introduced into the microwave cracking unit according to actual conditions and needs, and it is not an essential raw material for microwave cracking.

[0043] According to the present invention, the electromagnetic wave absorber is preferably selected from at least one of silicon carbide, composite ferrite, ultrafine metal particles, and organic high molecular polymer nanomaterials. The particle size of the electromagnetic wave absorber is preferably 5-50 mm, preferably 10-50 mm.

[0044] According to the present invention, preferably, the dielectric constant of the electromagnetic wave absorber is 1-20 Farads / meter, more preferably 5-15 Farads / meter. More preferably, the electromagnetic wave absorber is selected from at least one of silicon carbide, composite ferrite and organic polymer (functional polymer) nanomaterials.

[0045] In the present invention, unless otherwise specified, the dielectric constant refers to the relative dielectric constant. The relative dielectric constant of silicon carbide used in the present invention is usually 9-11 Farad / m.

[0046] According to the present invention, preferably, the temperature of the optional second water vapor is 100-650°C, preferably 200-450°C.

[0047] According to the present invention, preferably, the weight ratio of the optional second water vapor to the steam phase is 0.1-2:1, preferably 0.1-1.5:1.

[0048] According to the present invention, preferably, the conditions for microwave cracking include: microwave cracking temperature of 400-800°C (for example, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, and the range formed by any two of the above), residence time of 0.05-1s, and preferably the microwave power in the reactor is 2-12000kW (for example, 2kW, 10kW, 100kW, 1000kW, 2000kW, 3000kW, 4000kW, 5000kW, 6000kW, 7000kW, 8000kW, 9000kW, 10000kW, 11000kW, 12000kW, and the range formed by any two of the above). The microwave frequency is preferably 500-5000 MHz (e.g., 500 MHz, 1000 MHz, 1500 MHz, 2000 MHz, 2500 MHz, 3000 MHz, 3500 MHz, 4000 MHz, 4500 MHz, 5000 MHz, and a range between any two of the above). Unless otherwise specified, the temperature of microwave pyrolysis refers to the temperature at the reactor outlet; the microwave power in the reactor refers to the total microwave power provided by the microwave pyrolysis device to the reactor.

[0049] More preferably, the microwave cracking conditions include: microwave cracking temperature of 500-800°C, residence time of 0.1-0.8s, preferably the microwave power in the reactor is 2000-10000kW, and preferably the microwave frequency is 1000-4000MHz.

[0050] In the present invention, in order to achieve the above power, different magnetrons can be combined. The greater the microwave power, the more magnetrons need to be combined.

[0051] In the present invention, unless otherwise specified, the microwave cracking temperature refers to the temperature at the reactor outlet.

[0052] The present invention can further process the heavy components in the petroleum raw materials through catalytic cracking, so as to make full use of the heavy components and improve the utilization rate of the raw materials and the yield of the light olefins.

[0053] According to the present invention, preferably, the catalytic cracking method comprises: introducing a liquid phase into a fluidized reactor comprising a riser and a bed reactor in the presence of a catalyst for catalytic cracking.

[0054] According to the present invention, preferably, the catalyst is a solid acid selective molecular sieve catalyst. More preferably, the catalyst includes at least one of MMC-1 catalyst, MMC-2 catalyst, CHP-1 catalyst, CHP-2 catalyst, CRP-1 catalyst, CHP-S catalyst, CIP-1 catalyst, CIP-2 catalyst, CIP-3 catalyst, CIP-4 catalyst, CIP-5 catalyst and CIP-S catalyst. The above-mentioned catalysts of different types are all industrialized catalysts and can be obtained commercially.

[0055] According to the present invention, preferably, the catalytic cracking conditions include: catalytic cracking temperature 450-700°C, catalyst-oil ratio 1-25:1, bed space velocity 1-15h -1 .

[0056] According to the present invention, more preferably, the fluidized reactor comprises a first riser, a second riser, a bed reactor and a stripping section. The fluidized reactor in the present invention can refer to the reactor disclosed in CN201684585U.

[0057] In the present invention, preferably, the bed reactor, the first riser and the second riser are all filled with catalyst.

[0058] According to the present invention, preferably, the volume ratio of the liquid phase entering the first riser to that entering the second riser is 2-10:1, preferably 3-8:1.

[0059] According to the present invention, preferably, the outlet temperature of the first riser is 520-580°C, preferably 550-580°C.

[0060] According to the present invention, preferably, the outlet temperature of the second riser is 600-650°C, preferably 600-630°C.

[0061] According to the present invention, preferably, the product of the first riser, the product of the second riser and the steam generated in the stripping section enter the bed reactor together. More preferably, the volume ratio of the product of the first riser, the product of the second riser and the steam generated in the stripping section is 2-10:1:0.5-1.5, preferably 3-8:1:0.8-1.2.

[0062] According to the present invention, preferably, the method further comprises the step of separating the microwave cracking gas and / or the catalytic cracking gas to obtain light olefins.

[0063] According to the present invention, the microwave cracking product and the catalytic cracking product can be mixed for separation, or can be separated separately. Preferably, the process of separating the microwave cracking product and / or the catalytic cracking product includes: sequentially entering the microwave cracking product and / or the catalytic cracking product into a quencher and a cracking gas separation system to obtain products such as hydrogen, methane, ethylene, propylene, butadiene, gasoline, fuel oil and diesel. Among them, the cracking separation system can be a separation process commonly used in the art, such as a sequential separation process of LUMMUS.

[0064] According to the present invention, in order to further improve the yield of light olefins, preferably, the microwave cracking product and / or catalytic cracking is first subjected to heat exchange, and then enters the quencher (heat exchanger) and the cracking gas separation system in sequence. The microwave cracking product and / or catalytic cracking is first subjected to heat exchange, which can also reduce the coking phenomenon of the cracking gas during cooling and separation.

[0065] According to a particularly preferred embodiment of the present invention, the method comprises:

[0066] (1) The dehydrated and desalted crude oil (API 30-40) is electrically heated to 200-300° C., mixed with hydrogen at a weight ratio of 250-350:1, and introduced into a hydrogenation reactor for hydrogenation reaction to obtain hydrogenated crude oil; the conditions of the hydrogenation reaction include: hydrogenation temperature of 250-300° C., hydrogenation pressure of 2.5-3.5 MPa;

[0067] (2) mixing the hydrogenated crude oil at 200-300° C. and the first steam at 180-270° C. in a weight ratio of 0.6-0.8:1, and introducing the mixture into a cyclone separator for cyclone separation to obtain a vapor phase and a liquid phase; the separation efficiency of the cyclone separator is 75-85%, the temperature of the cyclone separation is 200-550° C., and the API value of the vapor phase is preferably increased by 5-20, more preferably by 10-20 (e.g., 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, 18.5, 19, 19.5, 20, and a range formed by any two of the above) compared with that of the petroleum feedstock;

[0068] (3) introducing the steam phase and the optional second water vapor into a microwave cracking unit, and performing a microwave cracking reaction in the presence of an electromagnetic wave absorber to obtain a microwave cracking gas; wherein the electromagnetic wave absorber is silicon carbide with a particle size of 10-35 mm, and the conditions of the microwave cracking reaction include: a microwave cracking temperature of 740-770°C, a residence time of 0.5-0.8s, a microwave power of 5000-8000kW, and a microwave frequency of 1500-2500MHz; the temperature of the optional second water vapor is 200-350°C, and the weight ratio of the optional second water vapor to the gas phase fraction is 0.5-1:1.

[0069] (4) introducing the liquid phase into a fluidized reactor and performing a catalytic cracking reaction in the presence of a solid acid molecular sieve catalyst CHP-1 to obtain a catalytic cracking gas; the catalytic cracking unit comprises a first riser, a second riser, a stripping section and a bed reactor; the liquid phase (preferably in a volume ratio of 4-7:1) is divided into two parts and enters the first riser and the second riser respectively, the stripper generates water vapor, and the products of the first riser and the second riser enter the bed reactor together with the water vapor (the volume ratio is preferably 4-6:1:0.8-1.2); the conditions of the catalytic cracking reaction include: the outlet temperature of the first riser is 565-575°C, the outlet temperature of the second riser is 605-615°C, and the space velocity of the bed reactor is 6-6.5h -1 , the agent-oil ratio is 11-14:1.

[0070] (5) After the microwave cracking gas is mixed with the catalytic cracking gas, it passes through a quencher and a cracking gas separation system to separate hydrogen, light olefins, cracking gasoline, cracking diesel and cracking fuel oil.

[0071] The second aspect of the present invention provides a system for preparing light olefins by combining microwave cracking with catalytic cracking, characterized in that the system comprises: a hydrogenation unit, a vaporization unit, a microwave cracking unit and a catalytic cracking unit; wherein:

[0072] The hydrogenation unit is used to hydrogenate the petroleum feedstock to obtain the hydrogenated petroleum feedstock;

[0073] The vaporization unit is used to vaporize the hydrogenated petroleum feedstock to obtain a vapor phase and a liquid phase;

[0074] The microwave cracking unit is used to perform microwave cracking on the vapor phase in the presence of an electromagnetic wave absorber under microwave cracking conditions to obtain microwave cracking gas;

[0075] The catalytic cracking unit is used to catalytically crack the liquid phase in the presence of a catalyst under catalytic cracking conditions to obtain catalytic cracking gas.

[0076] According to the present invention, preferably, the vaporization unit includes a cyclone separator. Preferably, the cyclone separator is selected from at least one of a volute cyclone separator, an axial flow guide vane cyclone separator, a straight cyclone separator, a cone-tube combination cyclone separator, and a direct-flow cyclone separator. More preferably, the cyclone separator is provided with internal components, for example, the internal components may include a skimmer located at the top of the cyclone separator and / or an isolation plate and a vortex preventer located at the bottom of the cyclone separator.

[0077] According to the present invention, preferably, the microwave cracking unit comprises a tubular reactor and a microwave generator fixed outside the tubular reactor. The tubular reactor can be arranged along the fluid direction; the microwave generator can include a magnetron. In order to minimize the mutual interference and cancellation of electromagnetic waves emitted by each magnetron, the magnetrons should be evenly distributed outside the tubular reactor.

[0078] According to the present invention, preferably, the catalytic cracking unit comprises a fluidized reactor, wherein the fluidized reactor comprises a riser and a bed reactor, preferably comprises a first riser, a second riser, a bed reactor and a stripper.

[0079] According to some preferred embodiments of the present invention, the catalytic cracking unit further comprises a catalyst regenerator, and the catalyst regenerator is used to regenerate the catalyst.

[0080] According to some preferred embodiments of the present invention, the system may further include a preheating unit, and preferably the preheating unit includes an electric heating device.

[0081] According to some preferred embodiments of the present invention, the system further comprises a device for providing (high temperature) water vapor. Optionally, the device can be connected to the vaporization unit and can also be selectively connected to the microwave cracking unit to provide the water vapor required by the above units during the processing.

[0082] According to a preferred embodiment of the present invention, the system further comprises a separation unit connected to the microwave cracking unit and / or the catalytic cracking unit (for separating light olefins from the microwave cracking products and / or the catalytic cracking products).

[0083] When light olefins are prepared using the method and system (suitable for the method) provided by the present invention, crude oil can be directly used as the raw material, and the yield / selectivity of light olefins when crude oil is used as the raw material is higher than that using existing methods such as steam cracking, and the system can operate stably for a longer time, making it more suitable for industrial production applications.

[0084] Based on this, the third aspect of the present invention provides the method described in the first aspect, and / or the application of the system described in the second aspect in improving the target product yield, selectivity and / or extending the operation cycle of directly cracking crude oil to prepare light olefins.

[0085] The present invention will be described in detail below by way of examples. It should be understood that the following examples are only used to further explain and illustrate the content of the present invention by way of example, and are not intended to limit the present invention.

[0086] In the following examples, unless otherwise specified, the petroleum raw material used is dehydrated and desalted crude oil, whose API value is 33.5 and whose composition is shown in Table 1 (measured according to ASTM D5307 method). Unless otherwise specified, the reagents used are commercial products purchased from regular chemical suppliers and are analytically pure.

[0087] Table 1

[0088]

[0089]

[0090] In the following embodiments, unless otherwise specified, the microwave cracking unit uses a microwave cracking furnace including a tubular reactor and magnetrons evenly arranged and fixed outside the tubular reactor to perform microwave cracking on the material to be processed. The microwave power is adjusted by adjusting the number of magnetrons. During the adjustment process, the magnetrons should be evenly arranged outside the reactor to reduce the interference and cancellation of electromagnetic waves emitted by different magnetrons. The vaporization processing unit uses a guide vane cyclone separator with internal components, wherein the internal components are conventional internal components located at the bottom of the cyclone separator.

[0091] Example 1

[0092] use Figure 1 The system shown (preheating unit not shown in the figure) performs crude oil cracking to produce light olefins.

[0093] (1) The dehydrated and desalted crude oil is preheated to 280°C by electric heating, mixed with hydrogen at a weight ratio of 300:1, introduced into a hydrogenation reactor, and subjected to a hydrogenation reaction to obtain a hydrogenated crude oil (API value of about 42).

[0094] The conditions of the hydrogenation reaction include: hydrogenation temperature 260°C, hydrogenation pressure 3MPa.

[0095] (2) The first water vapor at 260° C. and the hydrogenated crude oil at 280° C. were mixed in a weight ratio of 0.75:1 and introduced into a cyclone separator for cyclone separation to obtain a vapor phase (API value of about 42) and a liquid phase.

[0096] The separation efficiency of the cyclone separator is 80%, and the temperature of the cyclone separation is 450°C.

[0097] (3) The steam phase is introduced into a microwave cracking unit, and a microwave cracking reaction is carried out in the presence of silicon carbide (particle size 25 mm) to obtain microwave cracking gas.

[0098] The conditions of the microwave cracking reaction include: microwave cracking temperature of 750° C., residence time of 0.6 s, microwave power of 5000 kW, and microwave frequency of 2000 MHz.

[0099] (4) The liquid phase is introduced into a deep catalytic cracking unit comprising a fluidized reactor, and a catalytic cracking reaction is carried out in the presence of a solid acid molecular sieve catalyst (CHP-1 catalyst) to obtain a catalytic cracking gas.

[0100] The fluidized reactor comprises a first riser, a second riser, a stripping section and a bed reactor; the liquid phase is divided into two parts according to a volume ratio of 5:1 and enters the first riser and the second riser respectively, water vapor is generated in the stripping section, and the products of the first riser and the second riser and the water vapor enter the bed reactor together according to a volume ratio of 5:1:1.

[0101] The conditions for the catalytic cracking reaction include: the outlet temperature of the first riser is 568°C, the outlet temperature of the second riser is 606°C, and the space velocity of the bed reactor is 6.2h -1 , the agent-oil ratio is 11.8.

[0102] (5) After the microwave cracking gas is mixed with the catalytic cracking gas, it passes through a quencher and a cracking gas separation system to separate hydrogen, light olefins, cracking gasoline, cracking diesel and cracking fuel oil.

[0103] The yield of ethylene was 27.37 wt%, the yield of propylene was 14.89 wt%, the yield of 1,3-butadiene was 4.82 wt%, and the total yield of the above trienes was 47.08 wt%. The operation period was 53 days.

[0104] Example 2

[0105] use Figure 1 The system shown is used to crack crude oil to produce light olefins.

[0106] (1) The dehydrated and desalted crude oil is preheated to 210° C. by electric heating, mixed with hydrogen at a weight ratio of 300:1, introduced into a hydrogenation reactor, and subjected to a hydrogenation reaction to obtain a hydrogenated crude oil (API value of about 38).

[0107] The conditions of the hydrogenation reaction include: hydrogenation temperature of 300°C and hydrogenation pressure of 3MPa.

[0108] (2) The first water vapor at 260° C. and the hydrogenated crude oil at 220° C. were mixed in a weight ratio of 1:1 and introduced into a cyclone separator for cyclone separation to obtain a vapor phase (API value of about 45) and a liquid phase.

[0109] The separation efficiency of the cyclone separator is 80%, and the temperature of the cyclone separation is 500°C.

[0110] (3) The second water vapor (300° C.) and the steam phase are introduced into a microwave cracking unit at a weight ratio of 0.8:1, and a microwave cracking reaction is carried out in the presence of silicon carbide (particle size 25 mm) to obtain microwave cracking gas.

[0111] The conditions of the microwave cracking reaction include: microwave cracking temperature of 750° C., residence time of 0.5 s, microwave power of 7000 kW, and microwave frequency of 2500 MHz.

[0112] (4) The liquid phase is introduced into a deep catalytic cracking unit comprising a fluidized reactor, and a catalytic cracking reaction is carried out in the presence of a solid acid molecular sieve catalyst (CHP-1 catalyst) to obtain a catalytic cracking gas.

[0113] The fluidized reactor comprises a first riser, a second riser, a stripping section and a bed reactor; the liquid phase is divided into two parts according to a volume ratio of 5:1 and enters the first riser and the second riser respectively, water vapor is generated in the stripping section, and the products of the first riser and the second riser and the water vapor enter the bed reactor together according to a volume ratio of 5:1:1.

[0114] The conditions for the catalytic cracking reaction include: the outlet temperature of the first riser is 568°C, the outlet temperature of the second riser is 606°C, and the space velocity of the bed reactor is 6.2h -1 , the agent-oil ratio is 11.8.

[0115] (5) After the microwave cracking gas is mixed with the catalytic cracking gas, it passes through a quencher and a cracking gas separation system to separate hydrogen, light olefins, cracking gasoline, cracking diesel and cracking fuel oil.

[0116] The yield of ethylene was 27.20 wt%, the yield of propylene was 14.90 wt%, the yield of 1,3-butadiene was 4.53 wt%, and the total yield of the above trienes was 46.63 wt%. The operation period was 56 days.

[0117] Example 3

[0118] The method of Example 1 was followed, except that in step (3), the temperature of the microwave pyrolysis reaction was 650° C. The other operations and conditions were the same as those of Example 1.

[0119] The yield of ethylene was 20.08 wt%, the yield of propylene was 12.05 wt%, the yield of 1,3-butadiene was 5.53 wt%, and the total yield of the above trienes was 37.66 wt%. The operation period was 64 days.

[0120] Example 4

[0121] The method of Example 1 was followed, except that in step (2), the temperature of the cyclone separation was controlled to be 550° C. and the separation efficiency was 95% (the API of the obtained vapor phase was about 44). Other operations and conditions were the same as those of Example 1.

[0122] The yield of olefins was 24.42 wt%, the yield of propylene was 13.43 wt%, the yield of 1,3-butadiene was 4.07 wt%, and the total yield of the above trienes was 41.92 wt%. The operation period was 40 days.

[0123] Comparative Example 1

[0124] In this comparative example 1, only a conventional cracking furnace is used for cracking, and the cracking furnace used is a CBL-III cracking furnace (purchased from China Petrochemical Corporation).

[0125] The dehydrated and desalted crude oil is directly sent to the cracking furnace, and after passing through the convection section, it directly enters the radiation section. The operating parameters of the radiation section are the furnace tube outlet temperature of 760℃, the residence time of 0.1s, and the water-oil ratio of 1:1; cracking is carried out. The cracking gas adopts the LUMMUS sequential separation process.

[0126] The steam cracking reaction products were analyzed to show that the yield of ethylene was 21.49 wt%, the yield of propylene was 13.29 wt%, the yield of 1,3-butadiene was 4.03 wt%, and the yield of triene was 38.81 wt%. The operation period was 5 days.

[0127] Comparative Example 2

[0128] The method of Example 1 was followed, except that the vapor phase obtained after cyclone separation in step (2) entered an industrial cracking furnace, which used fuel gas as a heating source instead of microwave heating; the operating temperature of the radiation section of the cracking furnace was 800° C. Other operations and conditions were the same as those of Example 1.

[0129] Among them, the yield of ethylene is 23.31wt%, the yield of propylene is 12.82wt%, the yield of 1,3-butadiene is 3.89wt%, and the total yield of the above trienes is 40.02wt%. The operation period is 50 days.

[0130] It can be seen from the results of Example 1 and Comparative Example 1 that, with the conventional cracking device, the crude oil can only be put into use for a 5-day operation cycle, while the present invention can ensure that the crude oil can be normally put into use in the cracking device, and can effectively reduce the occurrence of coking, with an operation cycle of 50 days; and improve the yield of light olefins.

[0131] It can be seen from the results of Example 1 and Comparative Example 2 that in the method provided by the present invention, the yield of light olefins can be further improved and the operation time can be extended by combining microwave cracking and catalytic cracking with a specific pretreatment combination of hydrogenation and vaporization.

[0132] 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 preparing light olefins by combining microwave cracking with catalytic cracking, characterized in that: The method comprises: subjecting a petroleum raw material to hydrogenation treatment to obtain a hydrogenated petroleum raw material; subjecting the hydrogenated petroleum raw material to vaporization treatment to obtain a vapor phase and a liquid phase; subjecting the vapor phase to microwave cracking in the presence of an electromagnetic wave absorber under microwave cracking conditions to obtain microwave cracking gas; and subjecting the liquid phase to catalytic cracking in the presence of a catalyst under catalytic cracking conditions to catalytic cracking to obtain catalytic cracking gas.

2. The method according to claim 1, wherein: The API of the petroleum raw material is not less than 18, preferably 20-60, more preferably 25-58; Preferably, the petroleum raw material includes at least one of crude oil, light naphtha, naphtha, diesel and hydrogenated tail oil, and preferably the crude oil includes at least one of light crude oil, crude oil with a final distillation point higher than 600°C and lower than 700°C, and dehydrated crude oil that has been desalted.

3. The method according to claim 1 or 2, wherein: The hydroprocessing method includes: preheating the petroleum raw material, mixing it with hydrogen, and then performing a hydrogenation reaction under hydrogenation conditions; Preferably, the petroleum feedstock is preheated to 100-400°C and then mixed with hydrogen, preferably preheated to 150-350°C; Preferably, the weight ratio of the preheated petroleum feedstock to hydrogen is 100-500:1, preferably 200-400:1; Preferably, the hydrogenation conditions include: hydrogenation temperature 200-500°C, hydrogenation pressure 1-5MPa.

4. The method according to claim 1, wherein: The vaporization treatment method includes: mixing the first water vapor with the hydrogenated petroleum feedstock and introducing the mixture into a cyclone separator for cyclone separation; Preferably, the weight ratio of the first water vapor to the hydrogenated petroleum feedstock is 0.5-1.5:1; Preferably, the temperature of the first water vapor is 180-400°C, preferably 200-350°C; Preferably, the hydrogenated petroleum feedstock is preheated to 200-350° C. and then mixed with the first steam; Preferably, the separation efficiency of the cyclone separator does not exceed 90%, preferably 50-90%; Preferably, the temperature of the cyclone separation is 250-550°C; More preferably, the API value of the vapor phase is increased by 3-33 compared to the petroleum feedstock.

5. The method according to claim 1, wherein: The microwave cracking method includes: introducing the steam phase and the optional second water vapor into a microwave cracking unit, and performing a microwave cracking reaction in the presence of an electromagnetic wave absorber; And / or, the electromagnetic wave absorber is selected from at least one of silicon carbide, composite ferrite and organic high molecular polymer nanomaterials, and preferably the particle size of the electromagnetic wave absorber is 5-50 mm; Preferably, the temperature of the optional second water vapor is 100-650°C, preferably 200-450°C; Preferably, the weight ratio of the optional second water vapor to the steam phase is 0.1-2:1, preferably 0.1-1.5:1; Preferably, the microwave cracking conditions include: microwave cracking temperature of 400-800°C, residence time of 0.05-1s, preferably the microwave power in the reactor is 2-12000kW, and preferably the microwave frequency is 500-5000MHz.

6. The method according to claim 1, wherein: The catalytic cracking method includes: in the presence of a catalyst, introducing a liquid phase into a fluidized reactor containing a riser and a bed reactor to carry out a catalytic cracking reaction; Preferably, the catalyst is a solid acid selective molecular sieve catalyst; And / or, the catalytic cracking conditions include: catalytic cracking temperature 450-700°C, catalyst-oil ratio 1-25:1, bed space velocity 1-15h -1 ; Preferably, the fluidized reactor comprises a first riser, a second riser, a bed reactor and a stripping section; More preferably, the volume ratio of the liquid phase entering the first riser to that entering the second riser is 2-10:1, preferably 3-8:1; More preferably, the outlet temperature of the first riser is 520-580°C, preferably 550-580°C; More preferably, the outlet temperature of the second riser is 600-650°C, preferably 600-630°C; More preferably, the product of the first riser, the product of the second riser and the steam generated in the stripping section enter the bed reactor together, and preferably the volume ratio of the product of the first riser, the product of the second riser and the steam generated in the stripping section is 2-10:1:0.5-1.5, preferably 3-8:1:0.8-1.

2.

7. The method according to any one of claims 1 to 6, wherein: The method further comprises the step of separating the microwave cracking gas and / or the catalytic cracking gas to obtain light olefins.

8. A system for preparing light olefins by combining microwave cracking with catalytic cracking, characterized in that: The system comprises: a hydrogenation unit (1), a vaporization unit (2), a microwave cracking unit (3) and a catalytic cracking unit (7); wherein: The hydrogenation unit (1) is used to hydrogenate the petroleum feedstock to obtain hydrogenated petroleum feedstock; The vaporization unit (2) is used to vaporize the hydrogenated petroleum feedstock to obtain a vapor phase and a liquid phase; The microwave cracking unit (3) is used to carry out microwave cracking of the vapor phase in the presence of an electromagnetic wave absorber under microwave cracking conditions to obtain microwave cracking gas; The catalytic cracking unit (7) is used to catalytically crack the liquid phase in the presence of a catalyst under catalytic cracking conditions to obtain catalytic cracking gas.

9. The system according to claim 8, wherein: The vaporization unit (2) comprises a cyclone separator, and the cyclone separator is preferably selected from at least one of a volute cyclone separator, an axial flow guide vane cyclone separator, a straight cylinder cyclone separator, a cone cylinder combination cyclone separator and a direct current cyclone separator; And / or, the microwave cracking unit (3) comprises a tubular reactor and a microwave generator fixed outside the tubular reactor, and preferably the microwave generator comprises a magnetron; And / or, the catalytic cracking unit (7) comprises a fluidized reactor comprising a riser and a bed reactor, preferably the fluidized reactor comprises a first riser, a second riser, a bed reactor and a stripping section; Preferably, the system further comprises a preheating unit, and preferably the preheating unit comprises an electric heating device; Preferably, the system further comprises a separation unit (8) for separating the microwave cracking gas and / or the catalytic cracking gas to obtain light olefins.

10. Use of the method according to any one of claims 1 to 7, and / or the system according to claim 8 or 9, in improving the target product yield, selectivity and / or extending the operation cycle of preparing light olefins by direct cracking of crude oil.

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