CN118028023A

CN118028023A - Integrated light hydrocarbon separation device and method

Info

Publication number: CN118028023A
Application number: CN202211356167.2A
Authority: CN
Inventors: 孙丽丽; 赵百仁; 彭勃
Original assignee: China Petroleum and Chemical Corp; Sinopec Engineering Inc
Current assignee: China Petroleum and Chemical Corp; Sinopec Engineering Inc
Priority date: 2022-11-01
Filing date: 2022-11-01
Publication date: 2024-05-14

Abstract

The invention belongs to the field of olefin production devices, and discloses an integrated light hydrocarbon separation device and method, wherein the device comprises the following components: a catalytic cracking system, a steam cracking system, and a shared system; the catalytic cracking system comprises a catalytic cracking unit, a fractionation unit, a compression and pre-separation unit and a catalytic thermal separation unit which are connected in sequence; the steam cracking system comprises a steam cracking unit, a quenching unit, a compression and pre-deethanization unit and a steam thermal separation unit which are connected in sequence; the shared system comprises a carbon-cooling separation unit and an ethylene rectification unit which are connected in sequence; the carbon two outlets of the compression and pre-separation unit and the carbon two outlets of the compression and pre-deethanization unit are connected with the inlet of the carbon one cold separation unit. The technical scheme of the invention reduces the number of equipment, reduces occupied area, saves investment, reduces energy consumption and improves the recovery rate of the two carbon materials in catalytic pyrolysis. Meanwhile, products with larger property differences are not mixed back, separation and utilization of high added value components with relatively concentrated concentration are not affected, and economic benefit is maximized.

Description

Integrated light hydrocarbon separation device and method

Technical Field

The invention belongs to the field of olefin production devices, and particularly relates to an integrated light hydrocarbon separation device and method.

Background

At present, the oil refining capacity and the oil products in China are excessive, the traditional refinery is impacted by new energy, and the transformation from the refinery to the chemical industry is a necessary way for sustainable development under the large background of carbon peak and carbon neutralization. The oil refining and chemical engineering are combined, so that the main contradiction is grasped, the problem is solved, the contradiction specificity is closely focused, and the optimal configuration of the process is realized.

There are two currently known ways of integrating catalytic cracking with steam cracking.

One is that the catalytic cracking device adopts the traditional oil absorption and separation processes of fractionation, stable absorption, double desorption, gas separation and the like to separate various heavy products with three or more carbons, and the light components with two or more carbons are produced in a mixture form, namely the catalytic dry gas, and the specific process flow is shown in figure 1. The early catalytic dry gas is used as refinery fuel gas, and has low utilization value; the technology of preparing ethylbenzene/styrene by dilute ethylene is effectively utilized, but the application range is limited; and then, after the catalytic dry gas is subjected to impurity removal, pressure swing adsorption, shallow cold oil absorption and the like to concentrate carbon II, the catalytic dry gas is sent to an ethylene device (namely a steam cracking device) for recovery, so that the yield of the polymerization grade ethylene is increased. However, in the processes of oil absorption and separation of catalytic dry gas and carbon two-concentration of various processes, the loss of carbon two components is generally 5-15%, and the recovery rate is still to be improved. Such a fusion separation mode is called fusion, and the actual fusion degree is very limited.

The other is that on a heavy oil catalytic pyrolysis (CPP) device and a naphtha catalytic pyrolysis (such as K-COT) device, the reaction-regeneration and fractionation of the catalytic pyrolysis are separated from the pyrolysis unit and the quenching zone of the steam pyrolysis, and the separation system is completely integrated from the compression of rich gas/pyrolysis gas, so that an integrated structure of two ends and one tail is formed, and the specific process flow is shown in figure 2.

The fusion separation mode has the deepest integration degree, and the pyrolysis gasoline and the following light components are completely mixed together and separated, so that the reduction amplitude of equipment number, device occupation, investment and the like is largest. But suffer from the following disadvantages: firstly, the catalytic cracking products have more impurities and little alkyne/diene content, while the steam cracking products have less impurities and more alkyne/diene content, and after being mixed together, the impurity treatment capacity and treatment equipment of both sides are increased. And secondly, the components of the catalytic carbon four and the steam cracking carbon four and the components of the catalytic gasoline and the steam cracking gasoline are greatly different, and the latter contains a large amount of diene/alkyne, so that the directions of the two products of steam cracking are seriously influenced after the two products are mixed, and the utilization value is reduced.

Therefore, the fusion mode is only suitable for occasions where steam cracking is used as an auxiliary material, cracking raw materials are light, more than three-carbon heavy products are fewer, and all the four-carbon products and gasoline products are used as catalytic products.

Disclosure of Invention

Aiming at the problems existing in the prior art, the invention aims to provide a brand new integrated separation scheme, in the technical scheme, the common products are integrated and separated to the maximum extent, the recovery rate of the products is improved, and the investment is reduced; and products with different properties are separated respectively and are not interfered with each other, so that the aim of maximizing economic benefit is fulfilled.

In order to achieve the above object, a first aspect of the present invention provides an integrated light hydrocarbon separation apparatus, comprising: a catalytic cracking system, a steam cracking system, and a shared system;

the catalytic cracking system comprises a catalytic cracking unit, a fractionation unit, a compression pre-separation unit and a catalytic thermal separation unit which are connected in sequence;

The steam cracking system comprises a steam cracking unit, a quenching unit, a compression and pre-deethanization unit and a steam thermal separation unit which are connected in sequence;

the shared system comprises a carbon-cooling separation unit and an ethylene rectification unit which are connected in sequence;

The carbon two outlets of the compression and pre-separation unit and the carbon two outlets of the compression and pre-deethanization unit are commonly connected with the inlet of the carbon one cold separation unit.

The second aspect of the invention provides an integrated light hydrocarbon separation method, which comprises the following steps:

(1) The catalytic cracking raw oil is subjected to catalytic cracking to obtain reaction oil gas, the reaction oil gas is fractionated to obtain light hydrocarbon components, and the light components are compressed, impurity removed and pre-separated to obtain a light component A with carbon two and below and a heavy component A with carbon three and above;

(2) Sending the heavy component A with three or more carbon atoms into a catalytic thermal separation unit for separation;

(3) Steam cracking raw oil is subjected to steam cracking to obtain pyrolysis gas, and the pyrolysis gas is subjected to quenching, compression, impurity removal and pre-deethanization separation to obtain a light component B with two or less carbon atoms and a heavy component B with three or more carbon atoms;

(4) Sending the heavy component B with three or more carbon atoms into a steam thermal separation unit for separation;

(5) And combining the light component A with the light component B to be sent to a carbon one cold separation unit for separation to obtain a carbon two fraction, and sending the carbon two fraction to an ethylene rectification unit for further separation.

The invention has the following effects:

(1) The light components of the second carbon and below separated in the scheme of the invention are integrated together to carry out integrated separation, and the integrated separation comprises a front cooling and first carbon cooling separation area and an ethylene rectification unit. The original propylene refrigerating system and the original ethylene refrigerating system of the ethylene device are shared by public works such as waste heat of the two devices, steam, circulating cooling water and the like. In the scheme of the invention, the heavy components of three or more carbon atoms of catalytic pyrolysis and steam pyrolysis are still separated independently, and the product quality is kept unchanged.

(2) According to the scheme, products (heavy products such as carbon four and gasoline) with different properties of catalytic pyrolysis and steam pyrolysis are separated independently and are not mixed back, so that concentrated high-added-value components in the products can be separated and recycled directly, and the maximum economic benefit is achieved.

(3) The invention properly integrates the separation flow of catalytic cracking and steam cracking by optimizing and adjusting the treatment mode of the light hydrocarbon components of the catalytic cracking, and separates the light components such as hydrogen, methane, ethylene, ethane and the like in the catalytic cracking and the common components of an ethylene device one by one, wherein the concentration of hydrogen and nitrogen (H ₂+N₂) in the crude hydrogen is more than or equal to 95mol percent, methane tail gas is used as fuel, the purity of ethylene (more than or equal to 99.95mol percent) reaches a polymerization grade, and the ethane returns to a steam cracking furnace for cyclic cracking so as to increase the yield of ethylene.

(4) Compared with the prior method for recovering the oil absorption and separation and the catalytic dry gas by concentrating by adopting the traditional catalytic cracking, the scheme of the invention can furthest recover the high added value carbon two components in the catalytic cracking, and the recovery rate can be improved by at least 5-10 percent and reaches more than 99.6 percent; meanwhile, the number of equipment can be moderately reduced, the occupied area is reduced, and the investment is reduced; and the scale of the ethylene unit integration unit is enlarged, which is more beneficial to exerting the advantage of the scale effect.

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

Drawings

The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings.

FIG. 1 is a block diagram of a conventional catalytic cracking and steam cracking integrated separation process.

FIG. 2 is a block diagram of a process flow of a second conventional catalytic cracking and steam cracking integrated separation mode.

FIG. 3 is a process flow block diagram of an integrated light hydrocarbon separation method of the present invention.

Detailed Description

Preferred embodiments of the present invention will be described in more detail below. While the preferred embodiments of the present invention are described below, it should be understood that the present invention may be embodied in various forms and should not be limited to the embodiments set forth herein.

The invention provides an integrated light hydrocarbon separation device, which comprises: a catalytic cracking system, a steam cracking system, and a shared system;

In the present invention, the catalytic cracking reaction-regeneration and steam cracking furnaces, i.e. "two heads", are still discrete.

In the invention, the fluidized bed reaction product of catalytic cracking is provided with catalyst powder and contains various impurities such as carbon dioxide (CO ₂), hydrogen sulfide (H ₂ S), organic sulfur, nitrogen oxide (NO _x) and the like; while steam cracked gas contains a large amount of steam, alkyne/diene, a small amount of carbon dioxide (CO ₂) and hydrogen sulfide (H ₂ S), and other impurities are very small. The fractionation, compression and de-impurity/pre-separation unit of the catalytic cracking is still separate from the quenching, compression and pre-deethanization hydrogenation unit of the steam cracking.

In the invention, the pre-separation refers to the separation of catalytic cracking or steam cracking before entering a carbon-cold separation unit, the pre-separation can adopt a process of deethanizing before the sequence, and the separation processes adopted by the catalytic cracking and the steam cracking can be the same or different. Similar separation schemes are used for catalytic cracking and steam cracking, but the operating values (pressure, temperature) will vary depending on the composition.

According to the invention, the propane outlet of the catalytic thermal separation unit, the propane outlet of the steam thermal separation unit and the ethane outlet of the ethylene rectification unit are connected with the steam cracking unit.

According to the invention, the catalytic cracking unit is selected from any one of a fluidized catalytic cracking device, a deep catalytic cracking device, a heavy oil high-efficiency catalytic cracking device and a heavy oil catalytic cracking device.

The invention also provides an integrated light hydrocarbon separation method, which comprises the following steps:

According to the invention, the catalytic thermal separation unit separates out a refinery-grade polymerization grade propylene product, propane, a carbon four fraction and a catalytic pyrolysis gasoline product; the steam thermal separation unit separates out a polymerization grade propylene product, propane, a mixed carbon four and a crude pyrolysis gasoline product.

According to the invention, the carbon two fraction is separated in an ethylene rectification unit into a polymer grade ethylene product and ethane.

Preferably, the method further comprises the steps of:

(6) And the ethane separated by the propane and ethylene rectification units and separated by the catalytic heat separation unit and the steam heat separation unit is sent back to the steam cracking unit for cyclic cracking.

The separated light components with two carbon and below are integrated together to carry out integrated separation, and the integrated separation comprises a front cooling and carbon-cooling separation area and an ethylene rectification unit. The original propylene refrigerating system and the original ethylene refrigerating system of the ethylene device are shared by public works such as waste heat of the two devices, steam, circulating cooling water and the like.

The separation flow of catalytic cracking and steam cracking is properly integrated by optimizing and adjusting the treatment mode of the light hydrocarbon components of the catalytic cracking, and the light components such as hydrogen, methane, ethylene, ethane and the like in the catalytic cracking are separated together with the common components of an ethylene device one by one, wherein the concentration of (H ₂+N₂) in crude hydrogen is more than or equal to 95mol percent, methane tail gas is used as fuel, the purity of ethylene is more than or equal to 99.95mol percent, and the polymerization grade is achieved, and the ethane returns to a steam cracking furnace for cyclic cracking so as to increase the yield of ethylene.

According to the invention, the pre-separation adopts a deep cooling separation process of pre-deethanization.

The front deethanization adopts a deep cooling separation process of front deethanization and front hydrogenation.

Preferably, the reaction oil gas is fractionated to obtain slurry oil and cracked light oil components.

The pyrolysis gas is quenched to obtain pyrolysis diesel oil and pyrolysis fuel oil components.

The heavy components of three or more carbon atoms of catalytic pyrolysis and steam pyrolysis are still separated independently, and the product quality is kept unchanged.

Products (heavy products such as carbon four and gasoline) with different properties of catalytic pyrolysis and steam pyrolysis are separated independently and are not mixed back, so that concentrated high-added-value components in the products can be separated and recycled directly, and the economic benefit is maximized.

Preferably, the carbon-cold separation unit also separates crude hydrogen, methane.

The present invention will be described in more detail with reference to examples.

Comparative example

The process flow of conventional catalytic cracking and steam cracking fusion separation is shown in figure 1, raw materials such as 240 ten thousand tons/year heavy oil of petrochemical DCC are adopted, oil gas obtained by catalytic cracking reaction is subjected to fractionation unit to remove heavy fractions such as slurry oil, light diesel oil and the like, rich gas and crude gasoline enter an absorption stabilization unit to separate catalytic gasoline, the light gas/liquid fraction is subjected to double-stripping to obtain desulfurized catalytic dry gas and liquefied gas, a liquefied gas feeding device is used for separating propylene products, propane, catalytic carbon four and the like, and the catalytic dry gas is treated by a dry gas recovery device to obtain enriched ethylene gas and methane/hydrogen tail gas. Propane and ethylene-rich gas are sent to a steam cracking device as raw materials. Meanwhile, a petrochemical 60 ten thousand tons/year ethylene device (namely a steam cracking device) mainly takes naphtha and the like as raw materials, cracking gas obtained by steam cracking is subjected to quenching unit separation to obtain cracking fuel oil (PFO), cracking diesel oil (PGO), heavy cracking gasoline and other heavy products, and the cracking gas is subjected to compression, cold separation and heat separation to obtain crude hydrogen, methane tail gas, polymer grade ethylene, polymer grade propylene, mixed carbon four, crude cracking gasoline and other products.

Examples

An apparatus for light hydrocarbon separation as shown in fig. 3 is employed, which comprises: a catalytic cracking system, a steam cracking system, and a shared system;

The integrated light hydrocarbon separation method of the embodiment comprises the following process flows:

(1) Compressing, removing impurities and pre-separating light hydrocarbon components obtained after catalytic pyrolysis fractionation, wherein the pre-separating adopts a deep cooling separation process route of pre-deethanization; the cracking gas of steam cracking is quenched, compressed and pre-deethanized hydrogenation cryogenic separation process is adopted, the separated second carbon component and the light components below are converged, and the two components are subjected to pre-cooling, demethanizing and ethylene rectification similar to an ethylene device to obtain crude hydrogen and methane tail gas, and further polymer grade ethylene and ethane are produced in an ethylene rectification unit.

(2) And (3) delivering the heavy components with three carbon atoms and more separated from catalytic cracking compression and pre-separation/pre-deethanization to a thermal separation zone (similar to a gas separation device) of catalytic cracking to separate the products of the pyrolysis gasoline with three carbon atoms, four carbon atoms and the pyrolysis gasoline, namely the polymerization grade propylene, propane, catalytic carbon four and catalytic gasoline of oil refining.

(3) The heavy components separated by hydrogenation before vapor cracking compression and pre-deethanization are sent to a thermal separation zone (hot zone) of an ethylene device to separate the three-carbon, four-carbon and gasoline products, namely chemical polymerization grade propylene, propane, mixed three-carbon and crude pyrolysis gasoline.

(4) The separated ethane and propane are all sent back to the ethylene cracking furnace for circulating steam cracking, so as to improve the yield of ethylene and propylene.

In this example, the catalytic cracking and fractionation, steam cracking and quenching were maintained for each unit (i.e., the catalytic cracking light diesel, slurry oil and ethylene unit pyrolysis diesel, pyrolysis fuel oil were unchanged).

Test example 1

The production amounts of the main products of the catalytic cracking and steam cracking combined separation processes of the examples and the comparative examples were tested, and the production amounts of the main products were measured in tens of thousands of tons/year, and the production amounts of the main products are shown in table 1.

TABLE 1 comparison of yields of Main products

As can be seen from Table 1, the dry gas of catalytic cracking can be recovered in an ethylene device after carbon secondary concentration by Pressure Swing Adsorption (PSA), oil absorption and the like, the carbon secondary recovery rate is between 85 and 95 percent, and a part of ethylene and ethane can be always lost into methane/hydrogen tail gas by adopting a conventional separation flow.

By adopting the device integration method of the embodiment, hydrogen generated by catalytic pyrolysis can also enter crude hydrogen of an ethylene device for direct recovery, the yield of the crude hydrogen is increased (from 2.52 ten thousand tons/year to 3.48 ten thousand tons/year), but the total content of hydrogen and nitrogen (H ₂+N₂) is still about 95mol percent. The recovery rate of the second carbon can be improved to more than 99.6 percent, and almost all the second carbon is recovered, so that the yield of ethylene can be increased, and at least 1.2 ten thousand tons of ethylene can be produced more per year, which is equivalent to the economic benefit of 1 hundred million yuan. Polymerization grade propylene is still classified as refinery grade and chemical grade.

Test example 2

The number of equipment required for the catalytic cracking and steam cracking fusion separation process of the examples and the comparative examples is subjected to comparison test, and the comparison test data of the number of equipment is shown in table 2.

Table 2 device count comparison test

As can be seen from table 2, with the device integration method of the embodiment, after integration, the modified units mainly comprise stable absorption, double desorption, carbon two recovery and gas separation of the catalytic cracking device, and the cold separation and refrigeration system of the ethylene device mainly comprise scale up. Compared with the conventional separation process, the embodiment can reduce the number of equipment by about 125, and the equipment accounts for more than 17% of the total number of the two sets of equipment.

Test example 3

The investment and land occupation comparison test for the catalytic cracking and steam cracking combined separation process of the examples and the comparative examples is shown in table 3, wherein the investment is in hundred million yuan, the land occupation is in hectare.

TABLE 3 comparison of investment and occupation of land

As can be seen from Table 3, the investment of the examples is about 1.7 hundred million yuan, the occupied area is about 1.3 hectares, and the investment is reduced by about 4% and 8% respectively compared with the traditional separation.

Test example 4

The energy consumption required for the catalytic cracking and steam cracking fusion separation process of the examples and the comparative examples is compared and tested.

In terms of energy consumption, the recovery rate of products such as ethylene is improved, the product yield is increased, and the unit energy consumption calculated by ethylene products is reduced by 2.1 percent.

The foregoing description of embodiments of the invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the various embodiments described.

Claims

1. An integrated light hydrocarbon separation device, comprising: a catalytic cracking system, a steam cracking system, and a shared system;

2. The apparatus of claim 1, wherein a propane outlet of the catalytic thermal separation unit, a propane outlet of the vapor thermal separation unit, and an ethane outlet of the ethylene rectification unit are connected to the steam cracking unit.

3. The apparatus according to claim 1, wherein the catalytic cracking unit is selected from any one of a fluidized catalytic cracking unit, a deep catalytic cracking unit, a heavy oil high efficiency catalytic cracking unit, and a heavy oil catalytic cracking unit.

4. An integrated light hydrocarbon separation process employing the apparatus of any one of claims 1-3, said process comprising the steps of:

(1) The method comprises the steps of carrying out catalytic pyrolysis on catalytic pyrolysis raw oil to obtain reaction oil gas, fractionating the reaction oil gas to obtain a light hydrocarbon component, compressing the light hydrocarbon component, removing impurities and pre-separating the light hydrocarbon component to obtain a light component A with carbon number two and below and a heavy component A with carbon number three and above;

5. The method of claim 4, wherein the catalytic thermal separation unit separates a refinery grade polymerization grade propylene product, propane, a carbon four fraction, and a catalytic pyrolysis gasoline product; the steam thermal separation unit separates out a polymerization grade propylene product, propane, a mixed carbon four and a crude pyrolysis gasoline product.

6. The process of claim 5 wherein the carbon two fraction is separated from the polymer grade ethylene product and ethane in an ethylene rectification unit.

7. The method of claim 6, further comprising the step of:

8. The method of claim 4, wherein the pre-separation employs a cryogenic separation process of pre-deethanization;

9. The method of claim 4, wherein the reaction oil gas is fractionated to obtain slurry oil and pyrolysis light oil components;

10. The method of claim 4, wherein the carbon-cold separation unit further separates crude hydrogen, methane.