CN116064092A

CN116064092A - Method and system for producing olefin by crude oil steam cracking

Info

Publication number: CN116064092A
Application number: CN202211338662.0A
Authority: CN
Inventors: 何细藕; 王子宗; 白飞; 孙丽丽; 范传宏; 袁晴棠; 邵晨; 赵永华; 林江峰
Original assignee: China Petroleum and Chemical Corp; Sinopec Engineering Inc
Current assignee: China Petroleum and Chemical Corp; Sinopec Engineering Inc
Priority date: 2021-10-29
Filing date: 2022-10-28
Publication date: 2023-05-05

Abstract

The present disclosure relates to a method and system for producing olefins by steam cracking of crude oil, comprising the steps of: the raw crude oil enters a fractionating tower to carry out first separation, and light distillation range components, middle distillation range components and heavy distillation range components are separated; enabling the heavy distillation range components and steam to enter a separation device for second separation, and separating out gas-phase mixed materials and liquid-phase heavy components; mixing the light-boiling-range component with steam to obtain a first mixed material, and mixing the medium-boiling-range component with steam to obtain a second mixed material; and enabling the first mixed material, the second mixed material and at least part of the gas-phase mixed material to enter a radiation section of a steam cracking device respectively after being heated for steam cracking to obtain cracking products containing ethylene and propylene. The method can meet the requirements of different crude oils as cracking raw materials, and improve the yield of olefins.

Description

Method and system for producing olefin by crude oil steam cracking

Technical Field

The present disclosure relates to the field of hydrocarbon processing, and in particular, to a method and system for producing olefins by steam cracking of crude oil.

Background

With the development of the economy in China, the demand of the low-carbon olefin organic chemical raw materials is increased year by year, and the production scale of the low-carbon olefin is also increased year by year, but the increasing production demand cannot be met at present. The production capacity of the ethylene in China in 2019 reaches 3066 ten thousand tons, which is increased by 534 ten thousand tons compared with that in 2018, however, the equivalent requirement of the ethylene in China in 2019 reaches 4720 ten thousand tons, and the market requirement can not be met. Therefore, a large amount of ethylene and its derivative products are still imported every year in our country. In recent years, the process for preparing the low-carbon olefin by the traditional naphtha line has the problems of high raw material cost and competitive deficiency due to the impact of cheap raw materials such as middle east light hydrocarbon, american shale oil and the like and coal chemical industry processes, and the development of new energy automobiles reduces the requirements of the automobiles on oil products, so that in order to cope with the impact of market competition, the raw material source of an ethylene cracking device is expanded, the treatment flow of an oil refining device is shortened, the raw material cost is reduced by taking crude oil as a steam cracking raw material, the restriction of raw material varieties is eliminated, the investment of the oil refining device is reduced, and the process becomes an effective means for reducing the cost and enhancing the efficiency of traditional ethylene enterprises.

Compared with the traditional cracking raw materials, when the crude oil is used as the raw material of the steam cracking furnace, the problems of high final boiling point (more than 540 ℃), high colloid content, difficult vaporization, easy coking and the like exist, and for different crude oil sources, it is required to determine which crude oil can be used as the cracking raw material and which crude oil needs secondary processing. Accordingly, the design of cracking furnaces and the production process flow need to be correspondingly processed and improved to adapt to the characteristics of crude oil from different sources. At present, the Extra-abroad mainly comprises ExxonMobil company, satex America company, IQ Stokes chemical company, lummes company and the like, which are conducted in deep research on crude oil cracking technology, and the domestic mainly comprises Shanghai completion chemical engineering design Limited company and the like.

The Shanghai Ming chemical engineering design Co., ltd discloses a combined processing method and device (CN 111196936A) for producing olefin by directly cracking crude oil, which adopts pretreatment such as desalting, dewatering and the like to remove impurities, then sends the impurities into an ethylene cracking convection section for heating, and sends the heated feed into a gas-liquid separator to separate lighter hydrocarbon gas, and sends the lighter hydrocarbon gas into the convection section and a radiation section for steam cracking reaction to produce olefin. The liquid from the gas-liquid separator contains components such as atmospheric residuum, etc., and is sent to the hydrogenation unit for further treatment and then returned to the convection section and the radiation section. In the method, the overheated crude oil is directly sent to a gas-liquid separator, so that the expected gas-liquid separation effect is difficult to achieve.

The company of lumes technology, limited liability, discloses a process for thermally cracking crude oil and heavy feeds in a pyrolysis reactor to produce olefins (CN 107001955B). The method describes the combination scheme of a convection section of a cracking furnace, a multi-stage (3 stages at most) separator and a fractionating tower, and can carry out multiple gas-liquid separation on a mixture of crude oil and steam and send the mixture with different severity into different radiant section furnace tubes for cracking. The process mentions that the crude oil is preheated in an external heat exchanger before entering the convection section of the pyrolysis furnace, but there is no clear source of heat source. The method carries out gas-liquid separation on the mixture through a multistage separator and a fractionating tower and cracks different fractions through different radiation furnace tubes, and the cracking selectivity is improved, but the equipment is complicated, the investment is large, and the method is not suitable for light crude oil.

The history of the Exxon Mobil company in developing ethylene by cracking crude oil has also been long known. As early as 1970, 1 month, the company ExxonMobil proposed the use of crude oil steam cracking to produce chemical raw materials. It should be noted that, the technique of cracking the crude oil by exxonmobil does not directly use the purchased crude oil in the steam cracker, but performs pretreatment first. The treatment process mainly comprises the following steps: raw material preparation, hydrotreating and flash evaporation/separation. 2 month 2005, the chinese patent CN100564484C, a method for steam cracking heavy hydrocarbon feedstock, was filed by the elkesen chemical patent company, and the above process is described in detail, wherein the heavy hydrocarbon feedstock mainly comprises: crude oil, naphtha, gas oil, fuel oil, natural gasoline (condensate), oil residue, etc., which illustrates the flash vaporization separation process, but it is difficult to separate the gas-liquid components well by simple flash vaporization, especially that which avoids entraining heavy components into the gas phase, thereby easily causing coking in the convection section and further causing serious coking in the radiant coil.

The process for the preparation of ethylene by cracking crude oil/condensate is described by the company ilex in the patents CN101528894a and CN101778929 a. CN101528894a describes that after the crude oil/condensate is preheated in the convection section, the separated light component is sent to the pyrolysis furnace to be superheated in the convection section and then sent to the radiation section to be cracked, the heavy component is sent to the vacuum tower of the atmospheric tower to be further separated, CN101778929a describes that the heavy raw material mixed with 30% of the raw material, such as crude oil or condensate, is sent to the upper part of the separation device to be separated to protect naphtha and lighter component after being preheated in the convection section, and the separated liquid phase is sent to the packing tower below to be further separated, but does not describe how to process the separated heavy component. The stripper column containing packing or trays used in the evaporation unit in the above two patents, wherein the upper evaporation zone contains a gas-liquid separator for gas-liquid separation, but the liquid phase after flash evaporation is relatively heavy and viscous, and the packing is easily blocked, and the tray openings are also easily blocked.

Disclosure of Invention

The purpose of the present disclosure is to provide a method and a system for producing olefins by crude oil steam cracking, which can adapt to the requirements of crude oil with different raw materials as cracking raw materials, and can effectively improve the yield of olefins.

To achieve the above object, a first aspect of the present disclosure provides a method for producing olefins by steam cracking of crude oil, comprising the steps of: s1, enabling raw crude oil to enter a fractionating tower for first separation, and separating light-distillation range components, medium-distillation range components and heavy-distillation range components; s2, mixing the light distillation range component with steam to obtain a first mixed material; mixing the middle-boiling range component with steam to obtain a second mixed material; s3, mixing the heavy distillation range component with steam, and then entering a separation device for second separation to separate out a gas-phase mixed material and a liquid-phase heavy component; s4, enabling the first mixed material and the second mixed material to enter a convection section of a steam cracking device respectively for overheating, and then enter a radiation section of the steam cracking device for steam cracking to obtain a cracking product containing ethylene and propylene.

Optionally, the final distillation point of the light distillation range component obtained by the first separation is 80-160 ℃; the initial boiling point of the middle-boiling range component is not higher than the final boiling point of the light-boiling range component, and is preferably 60-140 ℃; the final distillation point of the middle-distillation range component is 250-350 ℃; the initial boiling point of the heavy-boiling-range component is not higher than the final boiling point of the medium-boiling-range component, and is preferably 230-330 ℃; the final distillation point of the gas phase mixture obtained by the second separation is 350-460 ℃; the initial distillation point of the liquid phase heavy component is not higher than the final distillation point of the gas phase mixture; optionally, the crude oil is at least one of a paraffinic crude oil, a naphthenic crude oil, or an intermediate crude oil.

Optionally, the method further comprises: all the gas-phase mixture enters a convection section of a steam cracking device to be overheated, and then enters a radiation section of the steam cracking device to be subjected to steam cracking to obtain a cracking product containing ethylene and propylene; or a part of the gas-phase mixed material enters a convection section of a steam cracking device to be overheated, then enters a radiation section of the steam cracking device to be subjected to steam cracking, and the other part of the gas-phase mixed material enters an oil refining device to be continuously processed; preferably, before the gas-phase mixed material enters the oil refining device for continuous processing, the part of the gas-phase mixed material and the raw material to be preheated are respectively introduced into a cooler for heat exchange, so that preheated raw material oil and gas-phase mixed material are obtained for cooling liquid-phase material; then enabling the gas-phase mixed material to cool the liquid-phase material and enabling the liquid-phase material to enter an oil refining device for continuous processing; preferably, when the BMCI value of the crude oil component in the gas phase mixture is 30 or more, at least a portion of the gas phase mixture is sent to a refinery.

Optionally, along the height direction of the steam cracking device, the convection section is sequentially provided with a raw material preheating section, a first mixed superheating section, a second mixed superheating section, a third mixed superheating section, a fourth steam superheating section, a fifth mixed superheating section, a sixth mixed superheating section and an optional seventh mixed superheating section which are mutually independent from each other from top to bottom; the step S3 comprises the following steps: mixing the heavy distillation range component with a first part of steam, and then entering a first mixed superheating section of the steam cracking device for heating to obtain a heated heavy distillation range component first mixed material; mixing the heated first mixed material of the heavy-boiling-range components with the second part of steam to obtain a second mixed material of the heavy-boiling-range components; optionally, the temperature of the second mixture of heavy distillation range components is 200-410 ℃; and enabling the heavy distillation range component second mixed material to enter the separation device for second separation.

Optionally, along the height direction of the steam cracking device, the radiation section is arranged below the convection section; the step S4 includes: a. mixing the light distillation range component with a third part of steam, then entering a third mixed superheating section of the steam cracking device for heating, and then entering a fifth mixed superheating section of the steam cracking device for heating to 550-750 ℃ to obtain a first stream to be cracked; or mixing the light distillation range component with a third part of steam, then entering a third mixing superheating section of the steam cracking device for heating, then mixing with a fourth part of steam, and then entering a fifth mixing superheating section of the steam cracking device for heating to 550-750 ℃ to obtain a first stream to be cracked; b. mixing the middle-boiling range component with fifth part of steam, then entering a second mixed superheating section of the steam cracking device for heating, then mixing with sixth part of steam, and then entering a sixth mixed superheating section of the steam cracking device for heating to 450-700 ℃ to obtain a second stream to be cracked; optionally, c, enabling the gas-phase mixed material to enter a seventh mixing superheating section of the steam cracking device and heating to 400-650 ℃ to obtain a third stream to be cracked; enabling the first material flow to be cracked to enter a first cracking furnace tube of a radiation section of the steam cracking device for steam cracking to obtain a first cracking product; enabling the second stream to be cracked to enter a second cracking furnace tube of a radiation section of the steam cracking device for steam cracking to obtain a second cracking product; optionally, the third stream to be cracked enters a third cracking furnace tube of a radiation section of the steam cracking device for steam cracking to obtain a third cracking product; preferably, the first portion of steam, the second portion of steam, the third portion of steam, the fourth portion of steam, the fifth portion of steam and the sixth portion of steam are each independently superheated steam or unheated section steam; the method further comprises the steps of: the steam enters a fourth steam superheating section of the steam cracking device for superheating treatment and is divided into three parts which are respectively used as the second part of steam, the fourth part of steam and the sixth part of steam; preferably, the temperature of the steam after the overheat treatment in the fourth steam overheat section is 400-575 ℃; in step a, the weight ratio of the total weight of the third part of dilution steam and the optional fourth part of steam to the crude oil component in the light boiling range component is from 0.3 to 1, preferably in the range of from 0.4 to 0.7; in the step b, the weight ratio of the total weight of the fifth part of steam and the sixth part of dilution steam to the crude oil component in the middle-distillation range component is 0.35-1, and the preferable range is 0.6-0.8; in step S3, the weight ratio of the total weight of the first portion of steam and the second portion of steam to the crude oil component in the gas phase mixture is 0.45-1, and the preferred range is 0.7-0.9.

Optionally, the method further comprises: the liquid phase heavy component enters and is sent out after being buffered by a buffer tank; enabling crude oil and waste heat materials from a storage tank to enter a quenching water preheater respectively for first heat exchange to obtain first preheated crude oil and cooled materials; optionally, the temperature of the first preheated crude oil is 70-120 ℃; or the crude oil from the storage tank is introduced into a convection section of the steam cracking device to be continuously heated after undergoing first heat exchange by a quenching water preheater, and the obtained preheated crude oil is used as the first preheated crude oil; enabling the first preheated crude oil to enter a desalting pretreatment device for desalting pretreatment to obtain desalted crude oil; heating the desalted crude oil in a raw material preheating section of the steam cracking device to obtain second preheated crude oil; passing the second preheated crude oil as the feedstock crude oil to the fractionation column for the first separation; optionally, the temperature of the second preheated crude oil is 200-400 ℃; optionally, the method further comprises: subjecting crude oil to an external pre-heat treatment outside the convection section prior to entering the fractionation column; the heat source of the external preheating treatment is waste heat materials from any device in an ethylene device or a combined device; the external preheating treatment and the preheating treatment in the feed preheating section are independent of each other.

Optionally, the method further comprises: dividing the cooling heavy component into three parts, enabling the first part of cooling heavy component to enter a hydrogenation device for hydrogenation treatment, and enabling the second part of cooling heavy component to enter a catalytic cracking device for catalytic cracking treatment; refluxing a third portion of the cooled heavies into the surge tank; optionally, the method further comprises: allowing at least part of the liquid phase heavy components to enter a steam generator for treatment to generate steam; a portion of the steam may be used as make-up steam for one or more of the first portion of steam, the second portion of steam, the third portion of steam, the fourth portion of steam, the fifth portion of steam, and the sixth portion of steam.

A second aspect of the present disclosure provides a system for producing olefins by steam cracking crude oil, the system comprising a fractionating tower, a separation device and a steam cracking device, the steam cracking device comprising a convection section and a radiation section, the convection section being disposed above the radiation section along the height direction of the steam cracking device; the fractionating tower is provided with a raw material crude oil inlet, a light distillation range component outlet, a middle distillation range component outlet and a heavy distillation range component outlet; the separation device is provided with a raw material inlet to be separated, a steam first inlet, a gas phase mixture outlet and a liquid phase heavy component outlet; the heavy-range component outlet of the fractionating tower is communicated with the raw material inlet to be separated of the separating device; the radiation section of the steam cracking device is provided with a first raw material inlet to be cracked, a second raw material inlet to be cracked and a third raw material inlet to be cracked; the first raw material inlet to be cracked is communicated with the light distillation range component outlet of the fractionating tower, the second raw material inlet to be cracked is communicated with the middle distillation range component outlet, and the third raw material inlet to be cracked is communicated with the gas phase mixture outlet of the separating device.

Optionally, along the height direction of the steam cracking device, the convection section comprises a raw material preheating section, a first mixed superheating section, a second mixed superheating section, a third mixed superheating section, a fourth steam superheating section, a fifth mixed superheating section, a sixth mixed superheating section and a seventh mixed superheating section which are sequentially arranged from top to bottom; the raw material preheating section is provided with a crude oil preheating inlet and a crude oil preheating outlet, and the crude oil preheating outlet is communicated with a raw material crude oil inlet of the fractionating tower; the first mixed superheating section is provided with a heavy distillation range component heating inlet and a heavy distillation range component heating outlet; the second mixing superheating section is provided with a middle-boiling-range component inlet and a second mixed material outlet; the third mixing superheating section is provided with a light distillation range component inlet and a first mixed material outlet; the fourth steam superheating section is provided with a steam heating inlet and a steam heating outlet; the fifth mixing superheating section is provided with a first mixed material inlet and a first raw material outlet to be cracked; the sixth mixing superheating section is provided with a second mixed material inlet and a second raw material outlet to be cracked; the seventh mixing superheating section is provided with a gas-phase mixed material inlet and a third raw material outlet to be cracked; the light distillation range component inlet of the third mixed superheating section is communicated with the light distillation range component outlet of the fractionating tower through a first pipeline, and the first mixed material outlet is communicated with the first mixed material inlet of the fifth mixed superheating section through a second pipeline; the first raw material to be cracked outlet of the fifth mixing superheating section is communicated with the first raw material to be cracked inlet of the radiation section; optionally, a third part of steam inlet is arranged on the first pipeline, and a fourth part of steam inlet is arranged on the second pipeline; the middle-boiling-range component inlet of the second mixed superheating section is communicated with the middle-boiling-range component outlet of the fractionating tower through a third pipeline, and the second mixed material outlet is communicated with the second mixed material inlet of the sixth mixed superheating section through a fourth pipeline; the second raw material to be cracked outlet of the sixth mixing superheating section is communicated with the second raw material cracking inlet of the radiation section; optionally, a fifth part of steam inlet is arranged on the third pipeline, and a sixth part of steam inlet is arranged on the fourth pipeline; the heavy-boiling-range component heating inlet of the first mixed superheating section is communicated with the heavy-boiling-range component outlet of the fractionating tower through a fifth pipeline, and the heavy-boiling-range component heating outlet is communicated with the raw material inlet to be separated of the separating device; optionally, a first part of steam inlet is arranged on the fifth pipeline, and a second part of steam inlet is arranged on the sixth pipeline; optionally, the gas phase mixture inlet of the seventh mixing and superheating section is communicated with the gas phase mixture outlet of the separation device, and the third raw material to be cracked outlet is communicated with the third raw material to be cracked inlet of the radiation section; optionally, the radiant section includes a first cracking furnace tube, a second cracking furnace tube, and a third cracking furnace tube disposed independently of each other; the first cracking furnace tube is provided with a raw material inlet formed as a first raw material inlet to be cracked, the second cracking furnace tube is provided with a raw material inlet formed as a second raw material inlet to be cracked, and the third cracking furnace tube is provided with a raw material inlet formed as a third raw material inlet to be cracked; and the steam heating inlet of the fourth steam superheating section is communicated with a steam source, and the steam heating outlet of the fourth steam superheating section is respectively communicated with the second part of steam inlet, the fourth part of steam inlet and the sixth part of steam inlet.

Optionally, the system further comprises a buffer tank, a pump, a desalting preprocessor and a quenching water preheater, wherein the buffer tank is at least provided with a liquid-phase heavy component buffer inlet, a liquid-phase heavy component buffer outlet, a cooling heavy component reflux inlet, a steam purging port and a nitrogen purging port; the pump includes an input port and an output port; the desalting pretreatment device is provided with a crude oil desalting inlet and a crude oil desalting outlet; the quenching water preheater is provided with a quenching water heat exchange inlet, a quenching water heat exchange outlet, a crude oil heat exchange first inlet and a crude oil heat exchange first outlet; the crude oil heat exchange first outlet of the quenching water preheater is communicated with the crude oil desalting inlet of the desalting pretreatment device, and the crude oil desalting outlet is communicated with the crude oil preheating inlet of the raw material preheating section; the liquid-phase heavy component buffer inlet of the buffer tank is communicated with the liquid-phase heavy component outlet of the separation device, the liquid-phase heavy component buffer outlet is communicated with the input port of the pump, and optionally, the cooling heavy component outlet is used for being communicated with the raw material inlet of the catalytic cracking device and/or the raw material inlet of the hydrotreatment device; optionally, the system further comprises a flow control unit, wherein the flow control unit comprises a liquid level transmitter, a pump back flow control valve, a liquid level control valve, a pump outlet flowmeter, a heavy component delivery flowmeter and a crude oil feeding flowmeter; the top of the buffer tank is also provided with a heavy component backflow port; the flow control unit can determine the vaporization ratio of the separation device through the heavy component delivery flowmeter and the crude oil feeding flowmeter; the liquid level transmitter is communicated with the inner space of the buffer tank and used for controlling the liquid level in the buffer tank.

Through the technical scheme, the disclosure provides a method and a system for producing olefin by crude oil steam cracking, which at least have the following beneficial effects:

1. the method comprises the steps of introducing raw crude oil into a fractionating tower for first separation, carrying out second separation on the obtained light distillation range component, medium distillation range component and heavy distillation range component, obtaining a gas phase mixed material and a liquid phase heavy component, reducing the operation temperature of a tower kettle compared with the existing normal pressure tower, subdividing the raw crude oil component, selecting a fraction suitable for producing olefin as a steam cracking raw material according to the composition and processing requirements of the crude oil, and producing an aromatic hydrocarbon component or selling as an oil product from the fraction unsuitable for being used as the cracking raw material, wherein the aromatic hydrocarbon component is suitable for alkene, aromatic hydrocarbon and oil; and because of subdivision, each fraction used as a cracking raw material can be cracked under the optimal condition, and higher olefin yield can be obtained;

2. compared with other crude oil cracking technologies, the process fraction disclosed by the invention is clear in cutting, the existing steam cracking technology can be furthest applied, the technology is mature, and the operation is simple;

3. the heating furnace of the atmospheric and vacuum device is omitted, the flow is simplified, and the investment is saved;

4. The method has wide application range to crude oil, the separated fraction can be flexibly utilized, the quality improvement and the synergy with the existing integrated refining device are realized, and the method can also be used for producing olefins such as ethylene and the like by using the new integrated refining device; the new refining integrated device can be rarely built into oil refining devices such as atmospheric and vacuum pressure, reforming and the like, and the light paraffin-based crude oil can be separated to obtain light fractions which are all used as steam cracking raw materials, so that the oil refining device can be not built.

Additional features and advantages of the present disclosure will be set forth in the detailed description which follows.

Drawings

The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification, illustrate the disclosure and together with the description serve to explain, but do not limit the disclosure. In the drawings:

FIG. 1 is a schematic flow diagram of a system for producing olefins by steam cracking of crude oil according to one embodiment of the present disclosure;

fig. 2 is a schematic flow diagram of a system for producing olefins by steam cracking of crude oil according to one embodiment of the present disclosure.

Description of the reference numerals

1-a raw material preheating section, 2-a fractionating tower, 3-a first mixed superheating section, 4-a second mixed superheating section, 5-a third mixed superheating section, 6-a fourth steam superheating section, 7-a fifth mixed superheating section, 8-a sixth mixed superheating section, 9-a seventh mixed superheating section, 10-a separating device, 11-a radiation section, 12-a buffer tank, 13-a pump, 15-a desalting preprocessor, 16-a quenching water preheater, 101-crude oil (crude oil from a storage tank), H1-waste heat materials, 102-pretreated crude oil (desalted crude oil), 104-heated crude oil (second preheated crude oil), 105-a light distillation range component, 106-a middle distillation range component, 107-a heavy distillation range component, 108-third partial steam (primary dilution steam), 109-fourth partial steam (secondary dilution steam), 110-first stream to be cracked, 111-fifth partial steam (primary dilution steam), 112-sixth partial steam (secondary dilution steam), 113-second stream to be cracked, 114-first partial steam (primary dilution steam), 115-heated heavy ends component mixture, 116-second partial steam (secondary dilution steam), 117-gas phase mixture, 118-liquid phase heavy ends, 119-third stream to be cracked, 120-cooled heavy ends, 121-cracked, 122-cracked, 123-cracked products

Detailed Description

Specific embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the disclosure, are not intended to limit the disclosure.

In the present disclosure, unless otherwise indicated, the terms "first," "second," "third," and the like are used merely to distinguish between different components and do not have the actual meaning of a tandem connection sequence. In this disclosure, terms such as "upper and lower, top and bottom" are used to generally refer to the upper and lower, top and bottom, of the device in its normal use. "inner and outer" are for the device profile.

In this disclosure, the words "primary dilution steam", "secondary dilution steam", "first portion steam", "second portion steam", and the like are used only to distinguish introduced steam in different steps, and do not contain actual meanings of the nature of the steam itself.

A first aspect of the present disclosure provides a method for producing olefins by steam cracking of crude oil, as shown in fig. 1, comprising the steps of:

s1, enabling raw crude oil to enter a fractionating tower 2 for first separation, and separating light distillation range components, middle distillation range components and heavy distillation range components;

S2, mixing the light distillation range component with steam to obtain a first mixed material; mixing the middle-boiling range component with steam to obtain a second mixed material;

s3, mixing the heavy distillation range component with steam, and then entering a separation device 10 for second separation to separate out a gas-phase mixed material and a liquid-phase heavy component;

s4, enabling the first mixed material and the second mixed material to enter a convection section of a steam cracking device respectively for overheating, and then enter a radiation section 11 of the steam cracking device for steam cracking to obtain a cracking product containing ethylene and propylene.

The method comprises the steps of introducing raw crude oil into a fractionating tower for first separation, carrying out second separation on the obtained light distillation range component, medium distillation range component and heavy distillation range component to obtain a gas phase mixed material and a liquid phase heavy component, subdividing the raw crude oil component, selecting fractions suitable for producing olefin as steam cracking raw materials according to the composition and processing requirements of the crude oil, and producing aromatic hydrocarbon components or selling the fractions unsuitable for being used as cracking raw materials as oil products, wherein the aromatic hydrocarbon components are suitable for alkene, aromatic hydrocarbon and oil; and because of subdivision, each fraction used as a cracking raw material can be cracked under the optimal condition, and higher olefin yield can be obtained; compared with other crude oil cracking technologies, the process is simpler, the existing steam cracking technology can be applied to the maximum extent, the technology is mature, and the operation is simple; the heating furnace of the atmospheric and vacuum device is omitted, the flow is simplified, and the investment is saved; the method has wide application range to crude oil, the separated fraction can be flexibly utilized, the quality improvement and the synergy with the existing integrated refining device are realized, and the method can also be used for producing olefins such as ethylene and the like by using the new integrated refining device; the new refining integrated device can be rarely built into oil refining devices such as atmospheric and vacuum pressure, reforming and the like, and the light paraffin-based crude oil can be separated to obtain light fractions which are all used as steam cracking raw materials, so that the oil refining device can be not built.

In one embodiment, the light range components from the first separation comprise naphtha and lighter components; the middle-range component comprises kerosene fraction and light diesel fraction; the light components in the heavy distillation range components in the gas phase mixture obtained by the second separation comprise heavy diesel oil and lighter components.

In the present disclosure, steam is carried in each fraction separated by the fractionating tower 2 and the separating device 10, and the distillation range temperature of each fraction in the present disclosure is the crude oil component separated by the fraction except for the steam.

In a preferred embodiment, the light range component obtained by the first separation has a final boiling point of 80 to 160 ℃; the initial boiling point of the middle-boiling range component is not higher than the final boiling point of the light-boiling range component, and is preferably 60-140 ℃; the final distillation point of the middle-distillation range component is 250-350 ℃; the initial boiling point of the heavy-boiling-range component is not higher than the final boiling point of the medium-boiling-range component, and is preferably 230-330 ℃; the final distillation point of the gas phase mixture obtained by the second separation is 350-460 ℃; the initial distillation point of the liquid phase heavy component is not higher than the final distillation point of the gas phase mixture. It should be understood that the initial or final point of each cut in this disclosure is a range of values, and may be any temperature within the range of values in practice. And the present disclosure may select the fraction to be separated according to actual production needs.

In the present disclosure, fractionation column 2 is a device of choice conventional in the art; the separation device 10 is a separation integrated device such as a flash separation tank, a cyclone separation tank; preferably, the high-efficiency gas/vapor-liquid separation equipment is provided, and the gas (vapor) phase outlet of the gas-liquid separation tank can be one or more.

In one embodiment, the feedstock crude oil is at least one of a paraffinic, an intermediate, or a naphthenic crude oil.

In one embodiment, the method further comprises: all the gas phase mixture enters a convection section of a steam cracking device to be overheated, and then enters a radiation section 11 of the steam cracking device to be subjected to steam cracking to obtain a cracking product containing ethylene and propylene; or alternatively

Allowing all the gas phase mixture materials to enter an oil refining device for continuous processing; or alternatively

And (3) enabling one part of the gas-phase mixed material to enter a convection section of the steam cracking device for overheating, then enter a radiation section 11 of the steam cracking device for steam cracking, and enabling the other part of the gas-phase mixed material to enter an oil refining device for continuous processing.

The inventor of the present disclosure found that the gas phase mixture obtained by the second separation can be treated differently according to the types of the crude oil, the application range of the crude oil is wide, the separated fraction can be utilized flexibly, and the maximization of the resource utilization is realized. The following is a detailed description.

In a specific embodiment, the present disclosure further comprises the steps of: when the crude oil is paraffin-based crude oil, introducing at least part of the gas phase mixture into a refinery for treatment. In the embodiment, the gas phase mixture material distilled from the paraffin-based crude oil is introduced into the oil refining device for treatment, so that the fraction unsuitable for being used as the steam cracking raw material can be used for producing aromatic hydrocarbon oil products, namely, olefine and olefine can be realized, aromatic hydrocarbon and oil can be realized, and the flexible utilization of the fractions separated from different types of raw material crude oil can be realized.

In a specific embodiment, when the feedstock crude oil is naphthenic crude oil, the whole gas phase mixture is introduced into the radiant section of the steam cracker without introducing into the refinery to further increase the olefin yield.

In a preferred embodiment, before the gas-phase mixed material enters the oil refining device for continuous processing, the part of the gas-phase mixed material and the raw material to be preheated are respectively introduced into a cooler for heat exchange, so that preheated raw material oil and gas-phase mixed material are obtained for cooling liquid-phase material; and then enabling the gas-phase mixed material to cool the liquid-phase material and enabling the liquid-phase mixed material to enter an oil refining device for continuous processing. The raw oil to be preheated in the system can be the raw oil obtained in any step before entering the fractionating tower, and the cooler can be used in series with other devices for treating the raw oil before entering the separating tower in the system for further improving the heat utilization rate.

In a preferred embodiment, when the BMCI of the crude oil component in the vapor phase mixture is greater than 30, at least a portion of the vapor phase mixture is sent to a refinery. "BMCI" (U.S. Bureau of Mines Correlation Index) refers to the aromatic index, which represents the aromaticity index of an oil.

In one embodiment, as shown in fig. 1, along the height direction of the steam cracking apparatus, the convection section is sequentially provided with a first mixed superheating section 3, a second mixed superheating section 4, a third mixed superheating section 5, a fourth steam superheating section 6, a fifth mixed superheating section 7, a sixth mixed superheating section 8 and an optional seventh mixed superheating section 9, which are independent from each other, from top to bottom; the step S3 comprises the following steps:

mixing the heavy distillation range component with a first part of steam, and then entering a first mixed superheating section 3 of the steam cracking device for heating to obtain a heated heavy distillation range component first mixed material; mixing the heated first mixed material of the heavy-boiling-range components with the second part of steam to obtain a second mixed material of the heavy-boiling-range components; optionally, the temperature of the second mixture of heavy distillation range components is 200-410 ℃;

the second mixture of heavy ends is passed to the separation device 10 for the second separation. In this embodiment, the heavy distillation range component obtained by the first separation and the first part of steam (for example, primary dilution steam) are introduced into the convection section of the steam cracking device to heat, so that the heat utilization efficiency of the whole process can be improved, the heavy distillation range component is mixed with steam, and then the heated mixture is subjected to the second separation under the condition of the second part of steam (for example, secondary dilution steam), so that the second separation efficiency of the heavy distillation range component can be further improved. Meanwhile, the convection section is provided with a plurality of independent superheating sections, so that the convection section can be used for heating a plurality of components, and the heat utilization efficiency and the cracking yield are greatly improved.

In one embodiment, as shown in fig. 1, the radiation section 11 is disposed below the convection section along the height direction of the steam cracker; the step S4 includes:

a. mixing the light distillation range component with a third part of steam, then entering a third mixed superheating section 5 of the steam cracking device for heating, and then entering a fifth mixed superheating section 7 of the steam cracking device for heating to 550-750 ℃ to obtain a first stream to be cracked; or mixing the light distillation range component with a third part of steam, then entering a third mixing and superheating section 5 of the steam cracking device for heating, then mixing with a fourth part of steam, and then entering a fifth mixing and superheating section 7 of the steam cracking device for heating to 550-750 ℃ to obtain a first stream to be cracked;

b. mixing the middle-boiling range component with fifth part of steam, then entering a second mixed superheating section 4 of the steam cracking device for heating, then mixing with sixth part of steam, and then entering a sixth mixed superheating section 8 of the steam cracking device for heating to 450-700 ℃ to obtain a second stream to be cracked;

optionally c, enabling the gas-phase mixed material to enter a seventh mixing superheating section 9 of the steam cracking device and heating to 400-650 ℃ to obtain a third stream to be cracked;

Enabling the first material flow to be cracked to enter a first cracking furnace tube of a radiation section 11 of the steam cracking device for steam cracking to obtain a first cracking product; enabling the second stream to be cracked to enter a second cracking furnace tube of a radiation section 11 of the steam cracking device for steam cracking to obtain a second cracking product; optionally, the third stream to be cracked enters a third cracking furnace tube of the radiant section 11 of the steam cracking device for steam cracking to obtain a third cracking product.

In the embodiment, the light distillation range component and the middle distillation range component are mixed and heated with the third part of steam respectively, then the fourth part of steam is mixed and heated (wherein the light distillation range component can be not mixed with the fourth part of steam, and the adjustment is carried out according to the process requirement), so as to obtain a material flow to be cracked, steam is introduced into the light distillation range component and the middle distillation range component for steam cracking, and the heat is carried out in different superheating sections of the convection section, so that the heat utilization rate and the integral degree of the whole process are improved; in the embodiment, different raw materials to be cracked are respectively introduced into the corresponding cracking furnace tubes, so that the control of the cracking conditions of the different raw materials to be cracked is facilitated. The heat utilization rate is further improved; and the different fractions are subdivided and heated to different temperatures (e.g., across the temperature) so that each fraction as a cracking feedstock is cracked under optimum conditions to achieve high olefin yields.

Specifically, the conditions for steam cracking the first stream to be cracked, the second stream to be cracked, and the third stream to be cracked in the radiant section in the present disclosure may be conventional conditions in the art, and the catalyst may be selected from the types of catalysts known in the art.

In the present disclosure, conventionally selected separation devices may also be used to separate the steam cracking products obtained in the radiant section 11, and separate products such as ethylene, propylene, and the like.

In a specific embodiment, the first part of steam, the second part of steam, the third part of steam, the fourth part of steam, the fifth part of steam and the sixth part of steam are respectively and independently superheated steam or unheated section steam, and can be adjusted according to actual requirements. Further, the place for superheating the steam in the present disclosure may be a superheating section inside the steam cracking apparatus, or other heat sources may be used for superheating outside the steam cracking apparatus.

In a preferred embodiment, as shown in fig. 1, the method further comprises: the steam enters a fourth steam superheating section 6 of the steam cracking device for performing the overheat treatment and is divided into three parts which are respectively used as the second part of steam, the fourth part of steam and the sixth part of steam; preferably, the temperature of the steam after the overheat treatment by the fourth steam overheat section 6 is 400-575 ℃.

In a preferred embodiment, in step a, the weight ratio of the total weight of the third portion of dilution steam and optionally the fourth portion of steam to the crude oil component in the light range component is from 0.3 to 1, preferably in the range of from 0.4 to 0.7;

in the step b, the weight ratio of the total weight of the fifth part of steam and the sixth part of dilution steam to the crude oil component in the middle-distillation range component is 0.35-1, and the preferable range is 0.6-0.8;

in step S3, the weight ratio of the total weight of the first portion of steam and the second portion of steam to the crude oil component in the gas phase mixture is 0.45-1, and the preferred range is 0.7-0.9.

In the present disclosure, since the light-boiling-range components, the middle-boiling-range components, and the gas-phase mixture obtained by separation are all mixed with steam, the present disclosure is based on the mass of components from crude oil remaining after removal of steam in the light-boiling-range components, the middle-boiling-range components, and the gas-phase mixture when controlling the amount of steam introduced.

In one embodiment, as shown in fig. 1, the method further comprises:

the liquid phase heavy component enters and is sent out after being buffered by a buffer tank 12;

enabling crude oil and waste heat materials from the storage tank to enter a quenching water preheater 16 respectively for first heat exchange to obtain first preheated crude oil and cooled materials; optionally, the temperature of the first preheated crude oil is 70-120 ℃; or the crude oil from the storage tank is introduced into a convection section of the steam cracking device to be continuously heated after undergoing first heat exchange by a quenching water preheater 16, and the obtained preheated crude oil is used as the first preheated crude oil;

Feeding the first preheated crude oil into a desalting preprocessor 15 for desalting pretreatment to obtain desalted crude oil;

enabling the second preheated crude oil to enter a raw material preheating section 1 of the steam cracking device for heating to obtain the second preheated crude oil; passing said second preheated crude oil as said feedstock crude oil into said fractionation column 2 for said first separation; optionally, the temperature of the second preheated crude oil is 200-400 ℃.

In the embodiment, the crude oil from the storage tank and the waste heat materials are subjected to first heat exchange, and the desalted crude oil and the liquid phase heavy components are subjected to second heat exchange, so that heat exchange among various materials is realized, the temperature of the crude oil to be treated is increased, and the liquid phase heavy components of the output system can be cooled; and introducing the second preheated crude oil into a raw material preheating section for heating, so that the overall heat utilization rate of the process is further improved.

In one embodiment, the process sequence of crude oil preheating can also adopt the heat exchange of the waste heat of an ethylene device to replace the heat exchange of quenching water, and then the quenching water is subjected to heat exchange and preheating with high-temperature heavy oil obtained in the crude oil cracking process; the crude oil can also exchange heat with the waste heat of the ethylene device, then desalt, and exchange heat with the high-temperature heavy oil obtained by the crude oil cracking device flow.

The process flow provided by the disclosure has high energy utilization rate, fully combines the heat energy of the ethylene device with the heating requirement of the process flow, further reduces the energy consumption of the ethylene device, realizes heat energy recycling and also saves investment.

In one embodiment, as shown in fig. 1, the method further comprises: dividing the cooling heavy component into three parts, enabling the first part of cooling heavy component to enter a hydrogenation device for hydrogenation treatment, and enabling the second part of cooling heavy component to enter a catalytic cracking device for catalytic cracking treatment; a third portion of the cooled heavies is returned to said surge tank 12.

In the disclosure, the obtained gas phase mixture and liquid phase heavy components can be treated differently according to the weight of crude oil and the source and composition of crude oil, for example, whether the gas phase mixture is introduced into a steam cracking device as a raw material to be cracked or directly introduced into an oil refining device according to whether the crude oil is paraffin-based crude oil or cycloalkyl crude oil, or a part of the gas phase mixture is introduced into the steam cracking device as a raw material to be cracked, and the rest of the gas phase mixture is introduced into the oil refining device for secondary processing, so as to improve the overall utilization efficiency of the process.

In one embodiment the method further comprises: allowing at least part of the liquid phase heavy components to enter a steam generator for treatment to generate steam; a portion of the steam may be used as make-up steam for one or more of the first portion of steam, the second portion of steam, the third portion of steam, the fourth portion of steam, the fifth portion of steam, and the sixth portion of steam.

In one embodiment, the method further comprises: detecting the temperature of the liquid phase material in the buffer tank 12 to obtain a temperature signal; carrying out external preheating treatment on crude oil outside the convection section before the crude oil enters the fractionating tower 2, wherein a heat source of the external preheating treatment is waste heat materials from any device in an ethylene device or a combined device; the external preheating treatment and the preheating treatment in the feed preheating section 1 are independent of each other. Further improves the heat utilization effect, in particular to the utilization effect of waste heat materials obtained by other devices in the factory. The external preheating treatment of the material and the heating step in the superheating section of the steam cracking device are mutually independent, and can be selected according to actual conditions.

A second aspect of the present disclosure provides a system for producing olefins by steam cracking crude oil, as shown in fig. 1, the system comprising a fractionating tower 2, a separation device 10 and a steam cracking device, the steam cracking device comprising a convection section and a radiation section 11, the convection section being disposed above the radiation section 11 along the height direction of the steam cracking device; wherein, the liquid crystal display device comprises a liquid crystal display device,

The fractionating tower 2 is provided with a raw material crude oil inlet, a light distillation range component outlet, a middle distillation range component outlet and a heavy distillation range component outlet; the separating device 10 is provided with a raw material inlet to be separated, a steam first inlet, a gas phase mixed material outlet and a liquid phase heavy component outlet; the heavy-boiling-range component outlet of the fractionating tower 2 is communicated with the raw material inlet to be separated of the separating device 10;

the radiation section 11 of the steam cracking device is provided with a first raw material inlet to be cracked, a second raw material inlet to be cracked and a third raw material inlet to be cracked; the first raw material inlet to be cracked is communicated with the light-range component outlet of the fractionating tower 2, the second raw material inlet to be cracked is communicated with the middle-range component outlet, and the third raw material inlet to be cracked is communicated with the gas-phase mixture outlet of the separating device 10.

In this disclosure, the fractionation column 2 is a device routinely selected by those skilled in the art.

In a specific embodiment, the radiation section of the steam cracking device comprises a first cracking furnace tube, a second cracking furnace tube and a third cracking furnace tube which are arranged independently of each other, wherein the first cracking furnace tube is provided with a raw material inlet formed into a first raw material inlet to be cracked, the second cracking furnace tube is provided with a raw material inlet formed into a second raw material inlet to be cracked, and the third cracking furnace tube is provided with a raw material inlet formed into a third raw material inlet to be cracked. Optionally, the first cracking furnace tube, the second cracking furnace tube and the third cracking furnace tube may be different radiant section furnace tubes entering the same furnace chamber of the same cracking furnace; or the radiation furnace tubes in the hearths of different radiation sections of the same cracking furnace; or the radiation furnace tubes of different cracking furnaces can be arranged according to actual conditions.

In one embodiment, the separation device 10 is a gas-liquid separation tank; preferably, the gas-liquid separation tank is a high-efficiency gas/gas-liquid separation device, wherein the gas-vapor phase outlet of the gas-liquid separation tank can be one or more.

In one embodiment, as shown in FIG. 2, the system further comprises a refinery apparatus, the feedstock inlet of which is in communication with the vapor phase mixture outlet of the separation apparatus 10.

In one embodiment, as shown in fig. 1, along the height direction of the steam cracking device, a raw material preheating section 1, a first mixed superheating section 3, a second mixed superheating section 4, a third mixed superheating section 5, a fourth steam superheating section 6, a fifth mixed superheating section 7, a sixth mixed superheating section 8 and a seventh mixed superheating section 9 which are mutually independent are sequentially arranged in the convection section from top to bottom;

the raw material preheating section 1 is provided with a crude oil preheating inlet and a crude oil preheating outlet, and the crude oil preheating outlet is communicated with a raw material crude oil inlet of the fractionating tower 2;

the first mixed superheating section 3 is provided with a heavy-boiling-range component heating inlet and a heavy-boiling-range component heating outlet; the second mixed superheating section 4 is provided with a middle-distillation range component inlet and a second mixed material outlet; the third mixed superheating section 5 is provided with a light distillation range component inlet and a first mixed material outlet; the fourth steam superheating section 6 is provided with a steam heating inlet and a steam heating outlet; the fifth mixing superheating section 7 is provided with a first mixed material inlet and a first raw material outlet to be cracked; the sixth mixing superheating section 8 is provided with a second mixed material inlet and a second raw material outlet to be cracked; the seventh mixing superheating section 9 is provided with a gas-phase mixed material inlet and a third raw material outlet to be cracked;

The light distillation range component inlet of the third mixed superheating section 5 is communicated with the light distillation range component outlet of the fractionating tower 2 through a first pipeline, and the first mixed material outlet is communicated with the first mixed material inlet of the fifth mixed superheating section 7 through a second pipeline; the first raw material to be cracked outlet of the fifth mixing superheating section 7 is communicated with the first raw material to be cracked inlet of the radiation section 11; optionally, a third part of steam inlet is arranged on the first pipeline, and a fourth part of steam inlet is arranged on the second pipeline;

the middle-boiling-range component inlet of the second mixed superheating section 4 is communicated with the middle-boiling-range component outlet of the fractionating tower 2 through a third pipeline, and the second mixed material outlet is communicated with the second mixed material inlet of the sixth mixed superheating section 8 through a fourth pipeline; the second raw material to be cracked outlet of the sixth mixing superheating section 8 is communicated with the second raw material to be cracked inlet of the radiation section 11; optionally, a fifth part of steam inlet is arranged on the third pipeline, and a sixth part of steam inlet is arranged on the fourth pipeline;

the heavy distillation range component heating inlet of the first mixed superheating section 3 is communicated with the heavy distillation range component outlet of the fractionating tower 2 through a fifth pipeline, and the heavy distillation range component heating outlet is communicated with the raw material inlet to be separated of the separating device 10; optionally, the fifth pipeline is provided with a first part of steam inlet, and the sixth pipeline is provided with a second part of steam inlet;

Optionally, the gas phase mixture inlet of the seventh mixing and superheating section 9 is connected to the gas phase mixture outlet of the separation device 10, and the third raw material to be cracked outlet is connected to the third raw material to be cracked inlet of the radiant section 11.

In a specific embodiment, in the system disclosed by the disclosure, mixers can be respectively arranged at the steam inlets of the first part to the steam inlets of the sixth part, and the mixers are used for respectively mixing the light distillation range component, the middle distillation range component and the heavy distillation range component with steam, so that materials and the steam can be more uniformly mixed, and coking is prevented. Any mixer of the kind known in the art that satisfies the above mixing effect may be employed.

In a specific embodiment, the first mixed superheating section to the seventh mixed superheating section in the disclosure may be different heat exchange tubes of the upper mixed superheating section of the convection section of the same steam cracking device, or heat exchange tubes of the upper mixed superheating section of different steam cracking devices.

In one embodiment, radiant section 11 includes a first cracking furnace tube, a second cracking furnace tube, and a third cracking furnace tube disposed independently of each other; the first cracking furnace tube is provided with a raw material inlet formed as a first raw material inlet to be cracked, the second cracking furnace tube is provided with a raw material inlet formed as a second raw material inlet to be cracked, and the third cracking furnace tube is provided with a raw material inlet formed as a third raw material inlet to be cracked;

The steam heating inlet of the fourth steam superheating section 6 is communicated with a steam source, and the steam heating outlet of the fourth steam superheating section 6 is respectively communicated with the second part of steam inlet, the fourth part of steam inlet and the sixth part of steam inlet.

In one embodiment, the system further comprises a buffer tank 12, a pump 14, a desalination pre-processor 15, and a quench water preheater 16;

the buffer tank 12 is provided with at least a liquid-phase heavy component buffer inlet, a liquid-phase heavy component buffer outlet, a cooling heavy component return inlet, a steam purge port and a nitrogen purge port; the pump 13 includes an input port and an output port; the desalting preprocessor 15 is provided with a crude oil desalting inlet and a crude oil desalting outlet; the quenching water preheater 16 is provided with a quenching water heat exchange inlet, a quenching water heat exchange outlet, a crude oil heat exchange first inlet and a crude oil heat exchange first outlet;

wherein, the crude oil heat exchange first outlet of the quenching water preheater 16 is communicated with the crude oil desalting inlet of the desalting pretreatment device 15, and the crude oil desalting outlet is communicated with the crude oil preheating inlet of the raw material preheating section 1;

the liquid heavy component buffer inlet of the buffer tank 12 is communicated with the liquid heavy component outlet of the separation device 10, the liquid heavy component buffer outlet is communicated with the input port of the pump 13, and the output port of the pump 13 is used for being communicated with the raw material inlet of the catalytic cracking device and/or the raw material inlet of the hydrotreatment device.

In one embodiment, the system further comprises a flow control unit, wherein the flow control unit comprises a liquid level transmitter, a pump reflux control valve b, a liquid level control valve c, a pump outlet flowmeter d, a heavy component delivery flowmeter e and a crude oil feeding flowmeter f; the top of the buffer tank 12 is also provided with a heavy component reflux inlet; the flow control unit can determine the vaporization ratio of the separation device 10 through the heavy component delivery flow meter e and the crude oil feeding flow meter f; wherein, the liquid level transmitter is communicated with the inner space of the buffer tank 12 and is used for controlling the liquid level in the buffer tank 12.

The present disclosure will be further described with reference to specific examples.

Example 1

Taking a certain crude oil as an example, the crude oil API value is 41, the embodiment can realize the comprehensive utilization of different light and heavy fractions of the crude oil, and the embodiment adopts the system shown in FIG. 1 and specifically comprises the following steps:

the crude oil 101 is subjected to preliminary preheating (the temperature of the first preheated crude oil is 70-120 ℃ after first heat exchange) by a quenching water preheater 16, then the desalted and impurity-removed by a desalting preprocessor 15, the pretreated crude oil 102 enters a raw material preheating section 1 in a convection section of a steam cracking device to be heated (the temperature of the second preheated crude oil obtained by heating is 200-400 ℃), and the heated crude oil 104 as raw material crude oil enters a fractionating tower 2 to be subjected to light-heavy component separation (namely first separation), and the following fractions are separated: light-range components (including naphtha and lighter components, the final distillation point is 80-160 ℃) 105, medium-range components (kerosene fraction, light diesel below fraction, the initial distillation point of the medium-range components is 60-140 ℃, the final distillation point is 250-350 ℃) 106 and heavy-range components (the initial distillation point is 230-330 ℃) 107; according to the actual production requirement, the separated components can be subjected to the following steps, or can enter an oil refining device for secondary processing (not shown in the figure):

Mixing the light distillation range component 105 separated from the steps with unheated primary dilution steam (third part steam) 108, entering a third mixing superheat section 5 of a convection section of a steam cracking device, then mixing with secondary dilution steam (fourth part steam) 109 subjected to heating treatment in a fourth steam superheat section 6 (the weight ratio of the sum of the primary dilution steam 108 and the secondary dilution steam 109 to the crude oil component in the light distillation range component is 0.4-0.7), and then heating the mixture to a temperature of 550-750 ℃ in a fifth mixing superheat section 7 of the convection section to obtain a first stream 110 to be cracked; introducing the first stream to be cracked 110 into the furnace tube of the radiant section 11 for high-temperature steam cracking reaction to obtain a cracked product 121;

the middle-boiling-range component 106 separated after the steps is mixed with unheated primary dilution steam (fifth part steam) 111, then enters a second mixing superheating section 4 of a convection section of a steam cracking device, is mixed with secondary dilution steam (sixth part steam) 112 heated to 400-575 ℃ through a fourth steam superheating section 6 (the weight ratio of the sum of the primary dilution steam 111 and the secondary dilution steam 112 to the crude oil component in the middle-boiling-range component is 0.6-0.8), and then enters a sixth mixing superheating section 8 of the convection section and is heated to a temperature of 450-700 ℃ to obtain a second to-be-cracked material stream 113; introducing the second stream to be cracked 113 into the furnace tube of the radiant section 11 for high-temperature steam cracking reaction to obtain a cracked product 122;

Mixing the heavy-boiling-range component 107 separated by the steps with unheated primary dilution steam (first part steam) 114, heating to 200-410 ℃ in a first mixing superheating section 3 of a convection section of a steam cracking device, respectively feeding a heated heavy-boiling-range component mixture 115 and secondary dilution steam (second part steam) 116 into a separation device 10 for second separation (wherein the weight ratio of the sum of the primary dilution steam 114 and the secondary dilution steam 116 to the crude oil component in the gas-phase mixture is 0.7-0.9), and obtaining a gas-phase mixture 117 and a liquid-phase mixture 118 (the gas-phase mixture is a mixture containing light components and steam in the heavy-boiling-range component, the liquid-phase mixture contains heavy components in the heavy-boiling-range component, and the final distillation point of the gas-phase mixture is 350-460 ℃, and the initial distillation point of the liquid-phase heavy components is not higher than the final distillation point of the gas-phase mixture);

introducing the gas phase mixture 117 into a seventh mixing superheating section 9 of the convection section for heating to a temperature of 400-600 ℃ to obtain a third stream 119 to be cracked; introducing the third stream 119 to be cracked into the furnace tube of the radiant section 11 for high-temperature steam cracking reaction to obtain a cracking product 123;

The liquid heavy component 118 is introduced into the liquid heavy component and passed through the buffer tank 12, the heavy component is introduced into the oil refining apparatus for secondary processing, or is introduced into the hydrogenation apparatus for hydrogenation treatment, or is introduced into the steam generator for treatment, so as to obtain steam, and the obtained steam can be used as the supplementary steam of the steam in any of the above steps.

Example 2

Taking a certain crude oil as an example, the crude oil API value is 41, the embodiment can realize the comprehensive utilization of different light and heavy fractions of the crude oil, and the embodiment adopts the system shown in fig. 2, and specifically comprises the following steps, wherein the steam cracking conditions are the same as those of embodiment 1:

the gas phase mixture 117 is cooled to a liquid phase by a cooler, and then the cooled liquid phase gas phase mixture is sent to a refinery (not shown);

the heavy component is introduced into the oil refining device for secondary processing, or introduced into the hydrogenation device for hydrotreating, or introduced into the steam generator for processing to obtain steam, and the obtained steam can be used as the supplementary steam of the steam in any step.

In this embodiment, according to actual needs, part of the gas phase mixture 117 may be introduced into the seventh mixing superheating section 9 of the convection section to heat to a temperature of 500-600 ℃ to obtain a third stream 119 to be cracked; the third stream to be cracked 119 is introduced into the furnace tubes of radiant section 11 for a pyrolysis reaction (not shown).

Comparative example 1

A similar method to example 1 was employed, except that example 1 was: the heavy distillation range component 107 obtained by the first separation is not continuously introduced into the separation device 10 for the second separation, but after the heavy distillation component 107 is mixed with unheated primary dilution steam (first part steam) 114, the mixture enters a first mixed superheating section 3 of a convection section of a steam cracking device for heating to 200-410 ℃, the heated heavy distillation range component mixture 115 is mixed with secondary dilution steam (second part steam) 116 subjected to heating treatment by a fourth steam superheating section 6 and then is directly introduced into a seventh mixed superheating section 9 of the convection section for heating to 500-600 ℃, and the obtained material flow is used as a third material flow 119 to be cracked and introduced into furnace tubes of a radiation section 11 for high-temperature steam cracking reaction; nor is the treatment step involving liquid phase heavies carried out, yielding a cleavage product designated 123.

The yields of the main products obtained by the steam cracking process in example 1 and comparative example 1 above are listed in table 1 below.

TABLE 1

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As can be seen from the above table, compared with the pyrolysis product 123' obtained by pyrolysis of the heavy fraction not subjected to the second separation in comparative example 1, in the method provided in example 1 of the present application, the heavy fraction is introduced into the separation device to perform the second separation, and then the gas phase mixture obtained by the second separation is subjected to pyrolysis to obtain the pyrolysis product 123 with higher yields of ethylene, propylene, butadiene and aromatic hydrocarbons, especially with higher yields of lower olefins such as ethylene, propylene and butadiene, which means that the method provided in the present application can improve the yield of lower olefins.

The preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, but the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solutions of the present disclosure within the scope of the technical concept of the present disclosure, and all the simple modifications belong to the protection scope of the present disclosure.

In addition, the specific features described in the above embodiments may be combined in any suitable manner without contradiction. The various possible combinations are not described further in this disclosure in order to avoid unnecessary repetition.

Moreover, any combination between the various embodiments of the present disclosure is possible as long as it does not depart from the spirit of the present disclosure, which should also be construed as the disclosure of the present disclosure.

Claims

1. A process for producing olefins by steam cracking of crude oil, comprising the steps of:

s1, enabling raw crude oil to enter a fractionating tower (2) for first separation, and separating light distillation range components, middle distillation range components and heavy distillation range components;

s3, mixing the heavy distillation range component with steam, and then entering a separation device (10) for second separation to separate out a gas-phase mixed material and a liquid-phase heavy component;

s4, enabling the first mixed material and the second mixed material to enter a convection section of a steam cracking device respectively for overheating, and then enter a radiation section (11) of the steam cracking device for steam cracking to obtain a cracking product containing ethylene and propylene.

2. The process of claim 1 wherein the light range component from the first separation has a final boiling point of from 80 to 160 ℃; the initial boiling point of the middle-boiling range component is not higher than the final boiling point of the light-boiling range component, and is preferably 60-140 ℃; the final distillation point of the middle-distillation range component is 250-350 ℃;

The initial boiling point of the heavy-boiling-range component is not higher than the final boiling point of the medium-boiling-range component, and is preferably 230-330 ℃;

the final distillation point of the gas phase mixture obtained by the second separation is 350-460 ℃; the initial distillation point of the liquid phase heavy component is not higher than the final distillation point of the gas phase mixture;

optionally, the crude oil is at least one of a paraffinic crude oil, a naphthenic crude oil, or an intermediate crude oil.

3. The method according to claim 1, characterized in that the method further comprises: all the gas-phase mixture enters a convection section of a steam cracking device to be overheated, and then enters a radiation section (11) of the steam cracking device to be subjected to steam cracking to obtain a cracking product containing ethylene and propylene; or alternatively

A part of the gas-phase mixed material enters a convection section of a steam cracking device to be overheated, then enters a radiation section (11) of the steam cracking device to be subjected to steam cracking, and the other part of the gas-phase mixed material enters an oil refining device to be continuously processed;

preferably, before the gas-phase mixed material enters the oil refining device for continuous processing, the part of the gas-phase mixed material and the raw material to be preheated are respectively introduced into a cooler for heat exchange, so that preheated raw material oil and gas-phase mixed material are obtained for cooling liquid-phase material; then enabling the gas-phase mixed material to cool the liquid-phase material and enabling the liquid-phase material to enter an oil refining device for continuous processing;

Preferably, when the BMCI value of the crude oil component in the gas phase mixture is 30 or more, at least a portion of the gas phase mixture is sent to a refinery.

4. The method according to claim 1, characterized in that the convection section is provided with a raw material preheating section (1), a first mixed superheating section (3), a second mixed superheating section (4), a third mixed superheating section (5), a fourth steam superheating section (6), a fifth mixed superheating section (7), a sixth mixed superheating section (8) and an optional seventh mixed superheating section (9) which are independent from each other from top to bottom in sequence along the height direction of the steam cracking apparatus; the step S3 comprises the following steps:

mixing the heavy distillation range component with a first part of steam, and then entering a first mixed superheating section (3) of the steam cracking device for heating to obtain a heated heavy distillation range component first mixed material; mixing the heated heavy component first mixed material with a second part of steam to obtain a heavy component second mixed material; optionally, the temperature of the second mixture of heavy distillation range components is 200-410 ℃;

the second mixture of heavy ends is fed to the separation device (10) for the second separation.

5. A method according to claim 4, characterized in that the radiant section (11) is arranged below the convection section in the height direction of the steam cracker; the step S4 includes:

a. Mixing the light distillation range component with a third part of steam, then entering a third mixed superheating section (5) of the steam cracking device for heating, and then entering a fifth mixed superheating section (7) of the steam cracking device for heating to 550-750 ℃ to obtain a first stream to be cracked; or mixing the light distillation range component with a third part of steam, then entering a third mixing and superheating section (5) of the steam cracking device for heating, then mixing with a fourth part of steam, and then entering a fifth mixing and superheating section (7) of the steam cracking device for heating to 550-750 ℃ to obtain a first stream to be cracked;

b. mixing the middle-boiling-range component with fifth part of steam, then heating the mixture in a second mixed superheating section (4) of the steam cracking device, then mixing the mixture with sixth part of steam, and then heating the mixture in a sixth mixed superheating section (8) of the steam cracking device to 450-700 ℃ to obtain a second stream to be cracked;

optionally c, enabling the gas-phase mixture to enter a seventh mixing superheating section (9) of the steam cracking device and heating to 400-650 ℃ to obtain a third stream to be cracked;

enabling the first material flow to be cracked to enter a first cracking furnace tube of a radiation section (11) of the steam cracking device for steam cracking to obtain a first cracking product; enabling the second stream to be cracked to enter a second cracking furnace tube of a radiation section (11) of the steam cracking device for steam cracking to obtain a second cracking product; optionally, the third stream to be cracked enters a third cracking furnace tube of a radiation section (11) of the steam cracking device for steam cracking to obtain a third cracking product;

Preferably, the first portion of steam, the second portion of steam, the third portion of steam, the fourth portion of steam, the fifth portion of steam and the sixth portion of steam are each independently superheated steam or unheated section steam;

the method further comprises the steps of: the steam enters a fourth steam superheating section (6) of the steam cracking device for superheating treatment and is divided into three parts which are respectively used as the second part of steam, the fourth part of steam and the sixth part of steam; preferably, the temperature of the steam after the overheat treatment in the fourth steam overheat section (6) is 400-575 ℃;

in step a, the weight ratio of the total weight of the third part of dilution steam and the optional fourth part of steam to the crude oil component in the light boiling range component is from 0.3 to 1, preferably in the range of from 0.4 to 0.7;

6. The method of claim 4, further comprising:

the liquid phase heavy component enters and is sent out after being buffered by a buffer tank (12);

enabling crude oil and waste heat materials from a storage tank to enter a quenching water preheater (16) respectively for first heat exchange to obtain first preheated crude oil and cooled materials; optionally, the temperature of the first preheated crude oil is 70-120 ℃; or leading crude oil from a storage tank into a convection section of a steam cracking device for continuous heating after carrying out first heat exchange by a quenching water preheater (16), and taking the obtained preheated crude oil as the first preheated crude oil;

enabling the first preheated crude oil to enter a desalting pretreatment device (15) for desalting pretreatment to obtain desalted crude oil;

heating the desalted crude oil in a raw material preheating section (1) of the steam cracking device to obtain second preheated crude oil; passing the second preheated crude oil as the feedstock crude oil to the fractionation column (2) for the first separation; optionally, the temperature of the second preheated crude oil is 200-400 ℃;

optionally, the method further comprises: subjecting crude oil to external pre-heating treatment outside the convection section prior to entering the fractionation column (2); the heat source of the external preheating treatment is waste heat materials from any device in an ethylene device or a combined device; the external preheating treatment and the preheating treatment in the raw material preheating section (1) are independent from each other.

7. The method of claim 5, further comprising: dividing the cooling heavy component into three parts, enabling the first part of cooling heavy component to enter a hydrogenation device for hydrogenation treatment, and enabling the second part of cooling heavy component to enter a catalytic cracking device for catalytic cracking treatment; refluxing the third portion of the cooled heavies to the surge tank (12);

optionally, the method further comprises: allowing at least part of the liquid phase heavy components to enter a steam generator for treatment to generate steam; a portion of the steam may be used as make-up steam for one or more of the first portion of steam, the second portion of steam, the third portion of steam, the fourth portion of steam, the fifth portion of steam, and the sixth portion of steam.

8. A system for producing olefin by steam cracking of crude oil, which is characterized by comprising a fractionating tower (2), a separation device (10) and a steam cracking device, wherein the steam cracking device comprises a convection section and a radiation section (11), and the convection section is arranged above the radiation section (11) along the height direction of the steam cracking device; wherein, the liquid crystal display device comprises a liquid crystal display device,

the fractionating tower (2) is provided with a raw material crude oil inlet, a light distillation range component outlet, a middle distillation range component outlet and a heavy distillation range component outlet; the separation device (10) is provided with a raw material inlet to be separated, a steam first inlet, a gas phase mixed material outlet and a liquid phase heavy component outlet; the heavy distillation range component outlet of the fractionating tower (2) is communicated with the raw material inlet to be separated of the separation device (10);

The radiation section (11) of the steam cracking device is provided with a first raw material inlet to be cracked, a second raw material inlet to be cracked and a third raw material inlet to be cracked; the first raw material inlet to be cracked is communicated with the light distillation range component outlet of the fractionating tower (2), the second raw material inlet to be cracked is communicated with the middle distillation range component outlet, and the third raw material inlet to be cracked is communicated with the gas phase mixture outlet of the separating device (10).

9. The system according to claim 8, wherein the convection section comprises a raw material preheating section (1), a first mixed superheating section (3), a second mixed superheating section (4), a third mixed superheating section (5), a fourth steam superheating section (6), a fifth mixed superheating section (7), a sixth mixed superheating section (8) and a seventh mixed superheating section (9) which are sequentially arranged from top to bottom along the height direction of the steam cracking apparatus;

the raw material preheating section (1) is provided with a crude oil preheating inlet and a crude oil preheating outlet, and the crude oil preheating outlet is communicated with a raw material crude oil inlet of the fractionating tower (2);

the first mixed superheating section (3) is provided with a heavy distillation range component heating inlet and a heavy distillation range component heating outlet; the second mixing superheating section (4) is provided with a middle-distillation range component inlet and a second mixed material outlet; the third mixing superheating section (5) is provided with a light distillation range component inlet and a first mixed material outlet; the fourth steam superheating section (6) is provided with a steam heating inlet and a steam heating outlet; the fifth mixing superheating section (7) is provided with a first mixed material inlet and a first raw material outlet to be cracked; the sixth mixing superheating section (8) is provided with a second mixed material inlet and a second raw material outlet to be cracked; the seventh mixing superheating section (9) is provided with a gas-phase mixed material inlet and a third raw material outlet to be cracked;

The light distillation range component inlet of the third mixed superheating section (5) is communicated with the light distillation range component outlet of the fractionating tower (2) through a first pipeline, and the first mixed material outlet is communicated with the first mixed material inlet of the fifth mixed superheating section (7) through a second pipeline; the first raw material outlet to be cracked of the fifth mixing superheating section (7) is communicated with the first raw material inlet to be cracked of the radiation section (11); optionally, a third part of steam inlet is arranged on the first pipeline, and a fourth part of steam inlet is arranged on the second pipeline;

the middle-boiling-range component inlet of the second mixed superheating section (4) is communicated with the middle-boiling-range component outlet of the fractionating tower (2) through a third pipeline, and the second mixed material outlet is communicated with the second mixed material inlet of the sixth mixed superheating section (8) through a fourth pipeline; the second raw material outlet to be cracked of the sixth mixing superheating section (8) is communicated with the second raw material inlet to be cracked of the radiation section (11); optionally, a fifth part of steam inlet is arranged on the third pipeline, and a sixth part of steam inlet is arranged on the fourth pipeline;

the heavy distillation range component heating inlet of the first mixed superheating section (3) is communicated with the heavy distillation range component outlet of the fractionating tower (2) through a fifth pipeline, and the heavy distillation range component heating outlet is communicated with the raw material inlet to be separated of the separating device (10); optionally, the fifth pipeline is provided with a first part of steam inlet, and the sixth pipeline is provided with a second part of steam inlet;

Optionally, the gas phase mixture inlet of the seventh mixing superheat section (9) is communicated with the gas phase mixture outlet of the separation device (10), and the third raw material outlet to be cracked is communicated with the third raw material inlet of the radiation section (11);

optionally, the radiant section (11) comprises a first cracking furnace tube, a second cracking furnace tube and a third cracking furnace tube which are arranged independently of each other; the first cracking furnace tube is provided with a raw material inlet formed as a first raw material inlet to be cracked, the second cracking furnace tube is provided with a raw material inlet formed as a second raw material inlet to be cracked, and the third cracking furnace tube is provided with a raw material inlet formed as a third raw material inlet to be cracked;

the steam heating inlet of the fourth steam superheating section (6) is communicated with a steam source, and the steam heating outlet of the fourth steam superheating section (6) is respectively communicated with the second part of steam inlet, the fourth part of steam inlet and the sixth part of steam inlet.

10. The system according to claim 9, further comprising a buffer tank (12), a pump (13), a desalination pre-processor (15) and a quench water preheater (16);

the buffer tank (12) is at least provided with a liquid-phase heavy component buffer inlet, a liquid-phase heavy component buffer outlet, a cooling heavy component reflux inlet, a steam purging port and a nitrogen purging port; the pump (13) comprises an input and an output; the desalting preprocessor (15) is provided with a crude oil desalting inlet and a crude oil desalting outlet; the quenching water preheater (16) is provided with a quenching water heat exchange inlet, a quenching water heat exchange outlet, a crude oil heat exchange first inlet and a crude oil heat exchange first outlet;

Wherein the crude oil heat exchange first outlet of the quenching water preheater (16) is communicated with the crude oil desalting inlet of the desalting pretreatment device (15), and the crude oil desalting outlet is communicated with the crude oil preheating inlet of the raw material preheating section (1);

the liquid-phase heavy component buffer inlet of the buffer tank (12) is communicated with the liquid-phase heavy component outlet of the separation device (10), the liquid-phase heavy component buffer outlet is communicated with the input port of the pump (13), and the outlet of the pump (13) is optionally used for being communicated with the raw material inlet of the catalytic cracking device and/or the raw material inlet of the hydrotreatment device;

optionally, the system further comprises a flow control unit comprising a liquid level transmitter, a pump back flow control valve (b), a liquid level control valve (c), a pump outlet flowmeter (d), a heavy fraction delivery flowmeter (e), a crude oil feed flowmeter (f); the top of the buffer tank (12) is also provided with a heavy component return inlet; the flow control unit can determine the vaporization ratio of the separation device (10) through the heavy component delivery flowmeter (e) and the crude oil feeding flowmeter (f); the liquid level transmitter is communicated with the inner space of the buffer tank (12) and used for controlling the liquid level in the buffer tank (12).