Method and system for producing olefin by cracking wide fraction hydrocarbon

Abstract

The invention provides a method and a system for producing olefin by cracking wide-fraction hydrocarbon, which are characterized in that the wide-fraction hydrocarbon, primary diluted steam and a cooling medium are mixed and then enter a gas-liquid separator (7) to be mixed, and then first separation is performed to obtain a first gas-phase material and a first liquid-phase material; mixing the secondary diluted steam with a gas stripping aid to obtain a gas stripping medium, and enabling the gas stripping medium to enter a gas-liquid separator (7) to be in countercurrent contact with the first liquid-phase material to obtain a second gas-phase material and a second liquid-phase material; mixing the first gas-phase material with the second gas-phase material to obtain a third gas-phase material; the third gas-phase material is subjected to second heating and then enters a radiation section (5) of a steam cracking device to be subjected to steam cracking, and a product containing olefin is obtained. According to the method, the wide-fraction hydrocarbon can be flexibly used for directly cracking to produce the olefin, a pretreatment device arranged in a traditional oil refining device is greatly reduced, and the olefin is produced in the shortest process with low energy consumption to the maximum extent.

Description

Technical Field

[0001] The present application relates to the field of petrochemical technology, and in particular to a method and system for producing olefins by cracking wide-fraction hydrocarbons. Background Art

[0002] With the development of the economy, the demand for low-carbon olefin organic chemical raw materials has increased year by year. Although the production scale of low-carbon olefins has also increased year by year, it is currently unable to meet the growing production demand. In 2019, the ethylene production capacity exceeded 30 million tons, an increase of more than 15% compared with 2018. However, the equivalent demand for ethylene in 2019 exceeded 45 million tons, which still cannot meet the market demand. In addition, in recent years, due to the impact of cheap raw materials and coal chemical processes, the traditional naphtha line process for preparing low-carbon olefins has problems of high raw material costs and lack of competitiveness. Therefore, in order to cope with the impact of market competition, expanding the raw material source of ethylene cracking units, using crude oil as the raw material for steam cracking, reducing raw material costs, getting rid of the constraints of raw material varieties, and improving production flexibility have become effective means for traditional ethylene companies to reduce costs and increase efficiency.

[0003] Compared with traditional cracking raw materials, crude oil used as a steam cracking furnace raw material has problems such as high final distillation point (greater than 540°C), high colloid content, difficulty in vaporization, and easy coking. Therefore, corresponding treatment and improvement are needed in the design of the cracking furnace and the production process to adapt to the characteristics of crude oil.

[0004] CN111196936A discloses a combined processing method and device for producing olefins by cracking wide-fraction hydrocarbons, which first removes impurities by pre-treatment such as desalting and dehydration, and then feeds the ethylene cracking convection section for heating. The heated feed is fed into a gas-liquid separator, and the lighter diesel and lighter components are separated and fed into the convection section and the radiation section for steam cracking reaction to produce olefins. The liquid phase coming out of the gas-liquid separator contains components such as atmospheric residue oil, which are fed into a hydrogenation unit for further treatment and then returned to the convection section and the radiation section. In this method, the preheated crude oil is directly fed to the gas-liquid separator. Due to the limitation of the preheating temperature, the components after direct flash evaporation of the first part are relatively small. In order to improve the utilization rate of the crude oil, the heavy components are hydrogenated and then separated by gas and liquid. The separated gas phase further separates light naphtha as the raw material for ethylene cracking and feeds it into the ethylene cracking furnace. The separated heavy naphtha, kerosene and other components that are not suitable for cracking are sent out as by-products, and the liquid phase is cracked, the components are too heavy, there is a coking problem, and the process is too complicated.

[0005] CN100587030A discloses a method for feeding or cracking a wide-cut hydrocarbon feedstock containing non-volatile hydrocarbons, which comprises: heating the wide-cut hydrocarbon feedstock, mixing the wide-cut hydrocarbon feedstock with a fluid and / or a first dilution steam stream to form a mixture, flashing the mixture to form a vapor phase and a liquid phase, and changing the amount of the fluid and / or the first dilution steam stream mixed with the wide-cut hydrocarbon feedstock according to at least one selected operating parameter of the method, such as the temperature of the flash stream before entering the flash tank. CN100564484A discloses a method for cracking wide-cut hydrocarbons, which comprises heating the wide-cut hydrocarbon feedstock, mixing the wide-cut hydrocarbon feedstock with a fluid and / or a first dilution steam stream to form a mixture, flashing the mixture to form a vapor phase and a liquid phase, separating and cracking the vapor phase, and cooling the product discharge in a transfer line exchanger, wherein the amount of the fluid and / or the first dilution steam stream mixed with the wide-cut hydrocarbon feedstock will vary according to at least one selected operating parameter of the method (such as the temperature of the flash stream before entering the flash / separator vessel). CN102057018A discloses a method and apparatus for cracking a liquid hydrocarbon feedstock using a gas-liquid separator to process a heated gas-liquid mixture to provide an overhead product with a reduced residual oil content. The hot liquid bottoms stream from the separator is heat exchanged with a cold hydrocarbon feedstock for cracking to provide a cooled liquid bottoms stream and a preheated feedstock. At least a portion of the preheated feedstock is directed to a convection section of a pyrolysis furnace for additional heating and subsequent cracking.

[0006] CN101528894A and CN101778929A introduce the process technology of preparing ethylene by cracking crude oil / condensate. CN101528894A introduces that after crude oil / condensate is preheated in the convection section, the separated light components enter the convection section of the cracking furnace for overheating and then enter the radiation section for cracking, and the heavy components are sent to the atmospheric tower and / or the vacuum tower for further separation. CN101778929A introduces that the raw materials mixed with 30% heavy raw materials such as crude oil or condensate enter the upper part of the separation device after preheating in the convection section to separate the protective naphtha and lighter components, and the separated liquid phase enters the packing tower below for further separation. How to deal with the separated heavy components is not introduced. The evaporation units of these two patents use a stripping tower containing packing or trays, wherein the upper evaporation zone contains a gas-liquid separator to achieve gas-liquid separation.

[0007] CN109694730A discloses a method and device for preparing low-carbon olefins by cracking wide-fraction hydrocarbons. The method uses a cyclone separator to separate the crude oil into gas and liquid, and the gas phase is cracked. ， This method can reduce coking and blockage in the radiation section and quenching section of the cracking furnace and reduce operating costs, but the method does not specify the control means for gas-liquid separation.

[0008] The information disclosed in the background technology section of the present invention is only intended to deepen the understanding of the general background technology of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to those skilled in the art. Summary of the invention

[0009] The purpose of the present invention is to provide a method and system for producing olefins by cracking wide-fraction hydrocarbons, which simplifies the atmospheric and vacuum devices in the traditional methods and systems, has a simple and efficient control scheme, realizes long-term operation of the cracking furnace, and reduces the energy consumption of the ethylene device.

[0010] In order to achieve the above object, the present disclosure provides a method for producing olefins by cracking wide-fraction hydrocarbons in a first aspect, the method comprising:

[0011] S1, mixing the preheated wide-cut hydrocarbons with at least a portion of the primary dilution steam to obtain a first mixed material;

[0012] S2, heating the first mixed material and introducing the first mixed material and the cooling aid into a gas-liquid separator for mixing, and then performing a first separation to obtain a first gas phase material and a first liquid phase material;

[0013] Mixing at least part of the secondary dilution steam with a stripping aid to obtain a stripping medium; allowing the stripping medium to enter a gas-liquid separator and countercurrently contact with the first liquid phase material to obtain a second gas phase material and a second liquid phase material; mixing the first gas phase material with the second gas phase material to obtain a third gas phase material;

[0014] S3, subjecting the third gaseous material to a second heating and then entering the radiation section of a steam cracking device for steam cracking to obtain a product containing olefins.

[0015] Optionally, the temperature of the preheated wide-cut hydrocarbon is 90-250°C, preferably 120-200°C; the wide-cut hydrocarbon is a wide-cut hydrocarbon crude oil with an API value of not less than 35 and a final boiling point of not less than 540°C;

[0016] The weight ratio of the wide-cut hydrocarbon to the primary dilution steam is 1:(0.1-0.5), preferably 1:(0.2-0.4);

[0017] The temperature of the first mixed material is 150-300°C, preferably 200-250°C;

[0018] The temperature of the first mixed material after the first heating is not higher than 400°C, preferably 250-350°C.

[0019] The cooling aid comprises water and / or liquid hydrocarbons; the final distillation point of the liquid hydrocarbons is lower than the final distillation point of the wide-fraction hydrocarbons; preferably, the final distillation point of the liquid hydrocarbons is 200-540°C, more preferably 250-450°C, and most preferably 300-400°C.

[0020] Optionally, the method of introducing the cooling aid includes: along the axial direction of the gas-liquid separator, the water introduction position is above or below the liquid hydrocarbon introduction position; or, the water introduction position and the liquid hydrocarbon introduction position are in the same plane.

[0021] Optionally, the method further comprises online analysis or periodic offline analysis of target parameters of the third gas phase material from the gas-liquid separator, wherein the target parameters comprise impurity types and contents thereof; the impurities comprise one or more of colloids, asphaltenes, metal impurities, sulfur, oxygen, nitrogen and heavy components; and,

[0022] Determine a preset amount of the cooling aid to be introduced into the gas-liquid separator; introduce the cooling aid into the gas-liquid separator using the preset amount; and then adjust the amount of the cooling aid introduced during the gas-liquid separation process according to target parameters of the gas phase material obtained through online monitoring or offline analysis.

[0023] The weight ratio of the wide-cut hydrocarbon to the cooling aid is 1:(0.01-0.2), preferably 1:(0.05-0.15);

[0024] The weight ratio of the wide-cut hydrocarbon to the secondary dilution steam is 1:(0.2-0.8), preferably 1:(0.3-0.65).

[0025] The weight ratio of the wide-cut hydrocarbon to the stripping aid is 1:(0.1-0.5), preferably 1:(0.1-0.2).

[0026] The gas stripping auxiliary agent is one or more selected from kerosene, light diesel oil and heavy diesel oil.

[0027] Optionally, the method further comprises: allowing the secondary dilution steam to enter a third heating section for heating to obtain superheated secondary dilution steam;

[0028] The temperature of the superheated secondary dilution steam is 400-630°C, preferably 450-600°C;

[0029] The temperature of the third gas phase material is 240-420°C, preferably 290-380°C;

[0030] The temperature of the third gas phase material after the second heating is 500-600°C, preferably 520-560°C; the temperature of the stripping medium is not higher than 550°C, preferably 500-550°C.

[0031] Optionally, the method further comprises: subjecting the wide-cut hydrocarbons to be preheated to desalting treatment and then entering the first heating section for preheating to obtain preheated wide-cut hydrocarbons;

[0032] The third gas phase material contains entrained steam and light components in the wide-cut hydrocarbon feedstock, and the second liquid phase material contains heavy components in the wide-cut hydrocarbon feedstock; the final distillation point of the light components is not higher than 540°C, and the initial distillation point of the heavy components is not higher than the final distillation point of the light components.

[0033] A second aspect of the present disclosure provides a system for producing olefins by cracking wide-fraction hydrocarbons, the system comprising a steam cracking device and a first gas-liquid separator; the steam cracking device comprises a heating section and a radiation section arranged in sequence from top to bottom;

[0034] The first gas-liquid separator is configured to allow the first mixed material and the cooling aid to enter the first gas-liquid separator respectively for mixing, and then perform a first gas-liquid separation to obtain a first gas phase material and a first liquid phase material; and allow the gas stripping medium to enter the first liquid phase material in countercurrent contact to obtain a second gas phase material and a second liquid phase material;

[0035] The radiant section of the steam cracking is configured to allow the third gas phase feed to enter therein for steam cracking to obtain products containing olefins.

[0036] Optionally, the heating section of the steam cracking device is provided with a first heating section, a second heating section, a third heating section and a fourth heating section in order from top to bottom; the first gas-liquid separator is provided with a first mixed material inlet, a cooling aid inlet, a stripping medium inlet, a third gas phase material outlet and a second liquid phase material outlet;

[0037] The radiant section includes a steam cracking inlet and a steam cracking outlet;

[0038] The heating inlet of the first heating section is used to introduce the wide-fraction hydrocarbon feedstock to be preheated; the heating outlet of the first heating section is connected to the heating inlet of the second heating section; the heating outlet of the second heating section is connected to the first mixed material inlet of the gas-liquid separator, and the heating inlet of the third heating section is formed as a secondary dilution steam inlet for introducing secondary dilution steam; the heating outlet of the third heating section is connected to the gas stripping medium inlet of the gas-liquid separator via a first pipeline, and a gas stripping auxiliary agent inlet is provided on the first pipeline; the third gas phase material outlet of the gas-liquid separator is connected to the heating inlet of the fourth heating section, and the heating outlet of the fourth heating section is connected to the steam cracking inlet of the radiation section; the second liquid phase material outlet of the gas-liquid separator is connected to a post-processing device;

[0039] A primary dilution steam inlet is arranged on the connecting pipeline between the heating outlet of the first heating section and the heating inlet of the second heating section; along the flow direction of the logistics, the primary dilution steam inlet is arranged upstream of the secondary dilution steam inlet.

[0040] Optionally, a first mixer is further provided in the gas-liquid separator, and the first mixer is configured to mix the first mixed material and the cooling aid therein;

[0041] Optionally, the system further comprises a desalination preprocessor, the desalination preprocessor comprising a desalination inlet and a desalination outlet, the desalination inlet is used to introduce wide-fraction hydrocarbons to be preheated, and the desalination outlet is connected to the heating inlet of the first heating section.

[0042] Optionally, the cooling aid inlet includes a water inlet and / or a liquid hydrocarbon inlet;

[0043] Along the axial direction of the gas-liquid separator, the water inlet is located above the first mixed material inlet; preferably, the water inlet is located 0.1-10m above the first mixed material inlet; more preferably, the water inlet is located 1-5m above the first mixed material inlet;

[0044] Optionally, along the axial direction of the gas-liquid separator, the water inlet is arranged above the liquid hydrocarbon inlet; or the water inlet is arranged below the liquid hydrocarbon inlet, or the water inlet and the liquid hydrocarbon inlet are located in the same plane.

[0045] Through the above technical scheme, the method and system for producing olefins by cracking wide-fraction hydrocarbons provided by the present disclosure have many beneficial effects: (1) The present disclosure sets a gas-liquid separator, introduces the wide-fraction hydrocarbons and the cooling aid into the gas-liquid separator respectively, and makes the cooling aid and the first mixed material after heating be fully mixed in the upper part of the gas-liquid separator, which can condense the heavy components in the gas phase material to the greatest extent, release the light components in the liquid phase material, control the entrainment of heavy components and impurities in the gas phase material entering the radiation section, and avoid rapid coking in the radiation section; (2) The present disclosure uses hydrocarbons as gas stripping aids, which are mixed with secondary dilution steam and then introduced into the gas-liquid separator. On the one hand, the hydrocarbon gas aid can control the temperature after mixing with the secondary dilution steam to be no higher than 550°C, and then This can avoid the occurrence of cracking reaction with the first liquid phase material at too high a temperature in the gas-liquid separator to produce coking products, which are carried into the radiation section and cause coking in the radiation section; on the other hand, it can reduce the requirements on the material of the gas-liquid separation device, thereby reducing production costs; and it can introduce as many light components in the first liquid phase material as possible into the first gas phase material to improve the utilization rate of wide-fraction hydrocarbons; (3) The method and system for cracking wide-fraction hydrocarbons to produce olefins provided by the present invention can be used for direct steam cracking of wide-fraction crude oil to produce ethylene, replacing the atmospheric and vacuum devices of traditional oil refining plants, and can make greater use of the experience of atmospheric and vacuum heating furnaces in oil refining plants and existing steam cracking technology to produce olefins, and the control scheme and process are simpler, reducing investment and operating costs.

[0046] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0048] Figure 1 The present invention provides an exemplary flow chart of wide-range hydrocarbon cracking to produce olefins.

[0049] Description of Reference Numerals

[0050] 1-first heating section; 2-second heating section; 3-third heating section; 4-fourth heating section; 5-radiation section; 6-first mixer; 7-gas-liquid separator. DETAILED DESCRIPTION

[0051] The specific embodiments of the present disclosure are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure, and are not used to limit the present disclosure.

[0052] In the present disclosure, unless otherwise stated, the words "first", "second", "third", etc. are used only to distinguish different components and do not have actual meanings such as the order of connection. In the present disclosure, the directional words used, such as "upper, lower, top, bottom", generally refer to the upper and lower, top and bottom of the device in normal use. "Inside and outside" refer to the outline of the device.

[0053] In the present disclosure, the terms "primary dilution steam", "secondary dilution steam" and the like are used only to distinguish the steam introduced in different steps, but do not contain any actual meaning such as the properties of the steam itself.

[0054] Each device used in the present disclosure is a structure conventionally selected in the art.

[0055] A first aspect of the present disclosure provides a method for producing olefins by cracking wide-fraction hydrocarbons, the method comprising:

[0056] S1, mixing the preheated wide-cut hydrocarbons with at least a portion of the primary dilution steam to obtain a first mixed material;

[0057] S2, after first heating the first mixed material, introducing it and the cooling aid into the gas-liquid separator 7 for mixing, and then performing a first separation to obtain a first gas phase material and a first liquid phase material;

[0058] Mixing at least part of the secondary dilution steam with a stripping aid to obtain a stripping medium; allowing the stripping medium to enter a gas-liquid separator 7 and countercurrently contact with the first liquid phase material to obtain a second gas phase material and a second liquid phase material; mixing the first gas phase material with the second gas phase material to obtain a third gas phase material;

[0059] S3, subjecting the third gaseous material to a second heating and then entering the radiation section 5 of the steam cracking device for steam cracking to obtain a product containing olefins.

[0060] The present invention provides a method for producing olefins by cracking wide-fraction hydrocarbons. A gas-liquid separator is provided, and the process is simple. Not only can more olefins be produced, but also the wide-fraction hydrocarbons and a cooling aid are introduced into the gas-liquid separator respectively, and the cooling aid is in countercurrent contact with the gas phase material in the wide-fraction hydrocarbons, so that the entrainment of heavy components and impurities in the gas phase material entering the radiation section can be controlled, so that rapid coking in the radiation section can be avoided, and the operation period of the cracking furnace can be extended to more than 10%, or even to more than 15%.

[0061] The wide-cut hydrocarbons disclosed herein include mixed hydrocarbons of wide cuts, with an API value of not less than 35 and a final boiling point of not less than 540° C. For example, the wide-cut hydrocarbons may be wide-cut hydrocarbons with an initial boiling point temperature of 15° C. and a final boiling point temperature of more than 750° C., or a hydrocarbon mixture containing components that are prone to coking under cracking furnace operating conditions; or the wide-cut hydrocarbons may be liquid hydrocarbons containing non-volatile components.

[0062] The wide-cut hydrocarbon feedstock used in the present disclosure includes one or more of the following feedstocks: paraffin-based crude oil, intermediate-based crude oil, naphthenic crude oil, condensate oil, gasoline, kerosene, diesel, tail oil, fuel oil, reformed oil, etc. processed by refineries through atmospheric and vacuum distillation, reforming, catalysis, coking and other refining units.

[0063] The inventors of the present disclosure unexpectedly discovered that, instead of controlling the temperature and pressure of the mixed material before it enters the gas-liquid separator 7, a cooling aid is used in the gas-liquid separator 7 to control the temperature of the gas phase material in the mixed material. This is simpler, more direct, and more efficient for the overall steam cracking process, and can avoid coking in the radiation section, thereby achieving long-term operation.

[0064] In one embodiment, the temperature of the preheated wide-cut hydrocarbons is 90-250°C, preferably 120-200°C;

[0065] The wide-cut hydrocarbon is a wide-cut hydrocarbon crude oil having an API value of not less than 35 and a final boiling point of not less than 540°C;

[0066] The weight ratio of the wide-cut hydrocarbon feedstock to the primary dilution steam is 1:(0.1-0.5), preferably 1:(0.2-0.4);

[0067] The temperature of the first mixed material is 150-300°C, preferably 200-250°C;

[0068] The temperature of the first mixed material after the first heating is not higher than 400°C, preferably 250-350°C.

[0069] The cooling aid comprises water and / or liquid hydrocarbons; the final distillation point of the liquid hydrocarbons is lower than the final distillation point of the wide-fraction hydrocarbons; preferably, the final distillation point of the liquid hydrocarbons is 200-540°C, more preferably 250-450°C, and most preferably 300-400°C.

[0070] Optionally, the method of introducing the cooling aid includes: along the axial direction of the gas-liquid separator 7, the water introduction position is above or below the liquid hydrocarbon introduction position; or, the water introduction position and the liquid hydrocarbon introduction position are in the same plane.

[0071] In one embodiment, the weight ratio of the wide-cut hydrocarbon to the cooling aid is 1:(0.01-0.2), preferably 1:(0.05-0.15); the weight ratio of the wide-cut hydrocarbon to the secondary dilution steam is 1:(0.2-0.8), preferably 1:(0.3-0.65); the weight ratio of the wide-cut hydrocarbon to the stripping aid is 1:(0.1-0.5), preferably 1:(0.1-0.2); the stripping aid is one or more selected from kerosene, light diesel and heavy diesel.

[0072] In one embodiment, the method further comprises: allowing the secondary dilution steam to enter the third heating section 3 for heating to obtain superheated secondary dilution steam; mixing the superheated secondary dilution steam with a stripping aid to obtain a stripping medium;

[0073] The temperature of the superheated secondary dilution steam is 400-630°C, preferably 450-600°C;

[0074] The temperature of the third gas phase material is 240-420°C, preferably 290-380°C;

[0075] The temperature of the third gas phase material after the second heating is 500-600° C., preferably 520-560° C.;

[0076] The temperature of the stripping medium is not higher than 550°C, preferably 500-550°C.

[0077] In one embodiment, the method further comprises: subjecting the wide-fraction hydrocarbons to be preheated to desalting treatment and then entering the first heating section 1 for preheating to obtain preheated wide-fraction hydrocarbons.

[0078] In one embodiment, the method further includes: subjecting the wide-fraction hydrocarbons to preheating treatment outside the heating section before entering the steam cracking furnace, wherein the heat source for the preheating treatment is waste heat materials from any device in the ethylene device or the combined device; the external preheating treatment is independent of the preheating treatment in the first heating section 1 of the steam cracking furnace, thereby improving the utilization efficiency of waste heat materials obtained from other devices.

[0079] The second gas phase material contains entrained steam and light components in the wide-cut hydrocarbon feedstock, and the second liquid phase material contains heavy components in the wide-cut hydrocarbon feedstock; the final distillation point of the light components is not higher than 540°C, and the initial distillation point of the heavy components is not higher than the final distillation point of the light components.

[0080] The second aspect of the present disclosure provides a system for producing olefins by cracking wide-fraction hydrocarbons, the system comprising a steam cracking device and a gas-liquid separator 7; the steam cracking device comprises a heating section and a radiation section 5 arranged in sequence from top to bottom;

[0081] The gas-liquid separator 7 is configured to allow the first mixed material and the cooling aid to enter therein respectively for mixing, and then perform a first gas-liquid separation to obtain a first gas phase material and a first liquid phase material; and allow the gas stripping medium to enter therein for countercurrent contact with the first liquid phase material to obtain a second gas phase material and a second liquid phase material;

[0082] The radiant section 5 of the steam cracking is configured to allow the third gaseous material to enter therein for steam cracking to obtain products containing olefins.

[0083] In one embodiment, the heating section of the steam cracking device is provided with a first heating section 1, a second heating section 2, a third heating section 3 and a fourth heating section 4 from top to bottom; the gas-liquid separator 7 is provided with a first mixed material inlet, a cooling aid inlet, a stripping medium inlet, a third gas phase material outlet and a second liquid phase material outlet;

[0084] The radiation section 5 includes a steam cracking inlet and a steam cracking outlet;

[0085] The heating inlet of the first heating section 1 is used to introduce the wide-fraction hydrocarbon feedstock to be preheated; the heating outlet of the first heating section 1 is connected to the heating inlet of the second heating section 2; the heating outlet of the second heating section 2 is connected to the first mixed material inlet of the gas-liquid separator 7; the heating inlet of the third heating section 3 is formed as a secondary dilution steam inlet for introducing secondary dilution steam; the heating outlet of the third heating section 3 is connected to the stripping medium inlet of the gas-liquid separator 7; the third gas phase material outlet of the gas-liquid separator 7 is connected to the heating inlet of the fourth heating section 4, and the heating outlet of the fourth heating section 4 is connected to the steam cracking inlet of the radiation section 5; the second liquid phase material outlet of the gas-liquid separator 7 is connected to a post-processing device;

[0086] A primary dilution steam inlet is arranged on the connecting pipeline between the heating outlet of the first heating section 1 and the heating inlet of the second heating section 2; along the flow direction of the logistics, the primary dilution steam inlet is arranged upstream of the secondary dilution steam inlet.

[0087] In one embodiment, the gas-liquid separator 7 is further provided with a first mixer 6, and the first mixer 6 is configured to mix the first mixed material and the cooling aid therein;

[0088] In one embodiment, the cooling aid inlet includes a water inlet and / or a liquid hydrocarbon inlet;

[0089] Along the axial direction of the gas-liquid separator 7, the water inlet is located above the first mixed material inlet; preferably, the water inlet is located 0.1-10m above the first mixed material inlet; more preferably, the water inlet is located 1-5m above the first mixed material inlet;

[0090] Optionally, along the axial direction of the gas-liquid separator 7, the water inlet is arranged above the liquid hydrocarbon inlet; or the water inlet is arranged below the liquid hydrocarbon inlet, or the water inlet and the liquid hydrocarbon inlet are located in the same plane.

[0091] Specifically, using Figure 1 The specific process flow of the system shown in the figure for steam cracking wide-fraction hydrocarbons to produce olefins includes:

[0092] S1, allowing the wide-cut hydrocarbons from the storage tank to enter the electric desalting device 11 for desalting treatment; allowing the wide-cut hydrocarbons to enter the first heating section 1 for preheating to obtain preheated wide-cut hydrocarbons; mixing the preheated wide-cut hydrocarbons with primary dilution steam to obtain a first mixed material;

[0093] S2, after the first mixed material enters the second heating section 2 for first heating, it is introduced into the gas-liquid separator 7 with the separation aid for mixing, and then subjected to first separation to obtain a first gas phase material and a first liquid phase material;

[0094] Mixing at least a portion of the secondary dilution steam superheated by the third heating section 3 with a stripping aid to obtain a stripping medium; allowing the stripping medium to enter the gas-liquid separator 7 and countercurrently contact with the first liquid phase material to obtain a second gas phase material and a second liquid phase material; mixing the first gas phase material with the second gas phase material to obtain a third gas phase material;

[0095] S3, subjecting the third gaseous material to a second heating and then entering the radiation section 5 of the steam cracking device for steam cracking to obtain a product containing olefins; and subjecting the second liquid-phase material to a post-processing device, such as a buffer tank.

[0096] The present disclosure is further described in detail below through examples. The raw materials used in the examples can all be obtained through commercial channels.

[0097] Example 1

[0098] The process of this embodiment is as follows Figure 1 As shown: Taking the wide-fraction hydrocarbon as paraffin-based crude oil 1 as an example, the API value of the crude oil is 41, and the gas stripping aid and the cooling aid are both diesel.

[0099] The specific steps include:

[0100] The wide-cut hydrocarbons to be preheated after the electric desalination are sent to the first heating section 1 of the steam cracking furnace heating section for first heating to obtain preheated wide-cut hydrocarbons at a temperature of 200-230° C. The preheated wide-cut hydrocarbons are mixed with primary dilution steam to obtain a first mixed material, and the first mixed material is sent to the first mixer 6 in the gas-liquid separator 7 with a cooling aid after first heating in the second heating section 2 for first mixing, and then first separation is performed in the first separator 7 to obtain a first gas phase material and a first liquid phase material;

[0101] The weight ratio of the wide-cut hydrocarbon to the primary dilution steam is 1:0.2, and the temperature of the first mixed material is 190° C.; the weight ratio of the wide-cut hydrocarbon to the cooling aid is 1:0.1;

[0102] S2, allowing the first mixed material to enter the second heating section 2 for first heating, and the temperature of the first mixed material after the first heating is 240° C. The first mixed material after the first heating and the cooling aid are respectively introduced into the gas-liquid separator 7 for mixing, and then subjected to the first separation to obtain a first gas phase material and a first liquid phase material;

[0103] The secondary dilution steam is overheated in the third heating section 3, and the temperature of the secondary dilution steam after overheating is 450°C; the superheated secondary dilution steam is mixed with a stripping agent to obtain a stripping medium, and the stripping medium enters the gas-liquid separator 7 to contact with the first liquid phase material obtained by the first separation to obtain a second gas phase material and a second liquid phase material; the first gas phase material and the second gas phase material are mixed to obtain a third gas phase material; the weight ratio of the wide-fraction hydrocarbon to the stripping agent is 1:0.1, and after the stripping agent is introduced, the temperature of the mixed material in the gas-liquid separator 7 is controlled below 550°C.

[0104] The impurities in the third gas phase material obtained by gas-liquid separation are monitored online, and the final distillation point and colloid / impurity content of the gas phase material are adjusted by injecting water and liquid hydrocarbons. The sulfur content in the liquid hydrocarbon is less than 200ppm, and other metal impurities and non-metallic impurities are significantly less than the impurities in the feed raw material; the weight ratio of wide-cut hydrocarbon to water is 1:0.05, and the weight ratio of wide-cut hydrocarbon to liquid hydrocarbon is 1:0.1; after the introduction of water and liquid hydrocarbon, the final distillation point of the third gas phase material finally obtained is reduced from 470°C to 455°C, and the temperature is 320°C; the colloid mass content in the third gas phase material is controlled to be less than 0.1% by weight; along the axial direction of the gas-liquid separator 7, the water inlet is located 1.5m above the inlet of the first mixed material;

[0105] The weight ratio of wide-cut hydrocarbons to superheated secondary dilution steam is 1:0.5;

[0106] S3, the third gas phase material is transported from the top of the gas-liquid separator 7 to the fourth heating section 4 of the steam cracking furnace for second heating to a crossover temperature of 550° C., and then enters the radiation section 5 of the steam cracking device for steam cracking to obtain a product containing olefins; the steam cracking temperature is 810° C. and the time is 0.25 s;

[0107] The second liquid phase material after gas-liquid separation is transported from the liquid phase material outlet at the bottom of the gas-liquid separator 7 to a post-processing device, such as a buffer tank.

[0108] Comparative Example 1

[0109] The method of this comparative example is the same as that of Example 1, the only difference being that no cooling aid is introduced into the gas-liquid separator 7; the coking risk of the gas-liquid separator 7 is greatly increased, and the coking phenomenon in the radiation section is relatively serious compared with Example 1.

[0110] Compared with Comparative Example 1, the operation period of the cracking furnace in Example 1 is increased by 15%.

[0111] Comparative Example 2

[0112] The only difference between this comparative example and Example 1 is that the cooling aid is mixed with the first heated first mixed material before entering the gas-liquid separator 7 .

[0113] Mixing in the pipeline requires a separate mixer, which affects the pipeline layout of the entire device, and also affects the mixing and gas-liquid separation effects, causing more heavy components to be entrained into the radiation section and aggravating the coking phenomenon in the convection section and radiation section.

[0114] Compared with Comparative Example 2, the operation period of the cracking furnace in Example 1 is increased by 10%.

[0115] The preferred embodiments of the present disclosure are described in detail above; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0116] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0117] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A method for producing olefins by cracking wide-fraction hydrocarbons, characterized in that: The method comprises: S1, mixing the preheated wide-cut hydrocarbons with at least a portion of the primary dilution steam to obtain a first mixed material; S2, heating the first mixed material and introducing the first mixed material and the cooling aid into a gas-liquid separator (7) for mixing, and then performing a first separation to obtain a first gas phase material and a first liquid phase material; Mixing at least part of the secondary dilution steam with a stripping aid to obtain a stripping medium; allowing the stripping medium to enter a gas-liquid separator (7) and countercurrently contact with the first liquid phase material to obtain a second gas phase material and a second liquid phase material; mixing the first gas phase material with the second gas phase material to obtain a third gas phase material; S3, subjecting the third gaseous material to a second heating and then entering the radiation section (5) of the steam cracking device for steam cracking to obtain a product containing olefins.

2. The method according to claim 1, wherein: The temperature of the preheated wide-cut hydrocarbons is 90-250°C, preferably 120-200°C; The wide-cut hydrocarbon is a wide-cut hydrocarbon crude oil having an API value of not less than 35 and a final boiling point of not less than 540°C; The weight ratio of the wide-cut hydrocarbon to the primary dilution steam is 1:(0.1-0.5), preferably 1:(0.2-0.4); The temperature of the first mixed material is 150-300°C, preferably 200-250°C; The temperature of the first mixed material after the first heating is not higher than 400°C, preferably 250-350°C.

3. The method according to claim 1, wherein: The cooling aid comprises water and / or liquid hydrocarbon; the final boiling point of the liquid hydrocarbon is lower than the final boiling point of the wide-fraction hydrocarbon; preferably, the final boiling point of the liquid hydrocarbon is 200-540°C, more preferably 250-450°C, and most preferably 300-400°C; Optionally, the method of introducing the cooling aid includes: along the axial direction of the gas-liquid separator (7), the water introduction position is above or below the liquid hydrocarbon introduction position; or, the water introduction position and the liquid hydrocarbon introduction position are in the same plane.

4. The method according to claim 1, wherein: The weight ratio of the wide-cut hydrocarbon to the cooling aid is 1:(0.01-0.2), preferably 1:(0.05-0.15); The weight ratio of the wide-cut hydrocarbon to the secondary dilution steam is 1:(0.2-0.8), preferably 1:(0.3-0.65); The weight ratio of the wide-cut hydrocarbon to the stripping aid is 1:(0.1-0.5), preferably 1:(0.1-0.2); The gas stripping auxiliary agent is one or more selected from kerosene, light diesel oil and heavy diesel oil.

5. The method according to claim 1, wherein: The method further comprises: allowing the secondary dilution steam to enter a third heating section (3) for heating to obtain superheated secondary dilution steam; mixing the superheated secondary dilution steam with the stripping auxiliary agent to obtain a stripping medium; The temperature of the superheated secondary dilution steam is 400-630°C, preferably 450-600°C; The temperature of the third gas phase material is 240-420°C, preferably 290-380°C; The temperature of the third gas phase material after the second heating is 500-600° C., preferably 520-560° C.; The temperature of the stripping medium is not higher than 550°C, preferably 500-550°C.

6. The method according to claim 1, wherein: The method further comprises: subjecting the wide-fraction hydrocarbons to be preheated to desalting treatment and then entering the first heating section (1) for preheating to obtain preheated wide-fraction hydrocarbons; The third gas phase material contains entrained steam and light components in the wide-fraction hydrocarbons, and the second liquid phase material contains heavy components in the wide-fraction hydrocarbons; the final distillation point of the light components is not higher than 540°C, and the initial distillation point of the heavy components is not higher than the final distillation point of the light components.

7. A system for producing olefins by cracking wide-fraction hydrocarbons, characterized in that: The system comprises a steam cracking device and a gas-liquid separator (7); the steam cracking device comprises a heating section and a radiation section (5) arranged in sequence from top to bottom; The gas-liquid separator (7) is configured to allow the first mixed material and the cooling aid to enter therein respectively for mixing, and then perform a first gas-liquid separation to obtain a first gas phase material and a first liquid phase material; and allow the gas stripping medium to enter therein for countercurrent contact with the first liquid phase material to obtain a second gas phase material and a second liquid phase material; The radiant section (5) of the steam cracking is configured to allow the third gaseous material to enter therein for steam cracking to obtain a product containing olefins.

8. The system according to claim 7, wherein: The heating section of the steam cracking device is provided with a first heating section (1), a second heating section (2), a third heating section (3) and a fourth heating section (4) in order from top to bottom; the gas-liquid separator (7) is provided with a first mixed material inlet, a cooling aid inlet, a stripping medium inlet, a third gas phase material outlet and a second liquid phase material outlet; The radiation section (5) comprises a steam cracking inlet and a steam cracking outlet; The heating inlet of the first heating section (1) is used to introduce wide-fraction hydrocarbons to be preheated; the heating outlet of the first heating section (1) is connected to the heating inlet of the second heating section (2); the heating outlet of the second heating section (2) is connected to the first mixed material inlet of the gas-liquid separator (7); the heating inlet of the third heating section (3) is formed as a secondary dilution steam inlet for introducing secondary dilution steam; the heating outlet of the third heating section (3) is connected to the stripping medium inlet of the gas-liquid separator (7) via a first pipeline; a stripping agent inlet is provided on the first pipeline; The third gas phase material outlet of the gas-liquid separator (7) is connected to the heating inlet of the fourth heating section (4), and the heating outlet of the fourth heating section (4) is connected to the steam cracking inlet of the radiation section (5); the second liquid phase material outlet of the gas-liquid separator (7) is connected to a post-processing device; A primary dilution steam inlet is provided on the connecting pipeline between the heating outlet of the first heating section (1) and the heating inlet of the second heating section (2); Along the flow direction of the material flow, the primary dilution steam inlet is arranged upstream of the secondary dilution steam inlet.

9. The system according to claim 7, wherein: The gas-liquid separator (7) is further provided with a first mixer (6), wherein the first mixer (6) is configured to allow the first mixed material and the cooling aid to be mixed and contacted therein; Optionally, the system further comprises a desalination pre-processor (11), the desalination pre-processor (11) comprising a desalination inlet and a desalination outlet, the desalination inlet is used to introduce wide-fraction hydrocarbons to be preheated, and the desalination outlet is connected to the heating inlet of the first heating section (1).

10. The system according to claim 7, wherein: The cooling aid inlet includes a water inlet and / or a liquid hydrocarbon inlet; Along the axial direction of the gas-liquid separator (7), the water inlet is located above the first mixed material inlet; preferably, the water inlet is located 0.1-10 m above the first mixed material inlet; more preferably, the water inlet is located 1-5 m above the first mixed material inlet; Optionally, along the axial direction of the gas-liquid separator (7), the water inlet is arranged above the liquid hydrocarbon inlet; or the water inlet is arranged below the liquid hydrocarbon inlet, or the water inlet and the liquid hydrocarbon inlet are located in the same plane.

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