Heavy oil supercritical extraction multistage parallel separation treatment system and treatment method
阅读说明：本技术 一种重油超临界萃取多级平行分离处理系统及处理方法 (Heavy oil supercritical extraction multistage parallel separation treatment system and treatment method ) 是由 吕云飞 邓宏达 王鑫 昝大鑫 刘哲 于 2020-06-29 设计创作，主要内容包括：本发明涉及一种重油超临界萃取多级平行分离处理系统,其包括进料单元、溶剂混合单元、N组平行设置的超临界萃取分离单元,各超临界萃取分离单元均包括沥青分离塔、沥青汽提塔、脱沥青油分离塔、脱沥青油汽提塔,各级混合器连接至各超临界萃取分离单元的沥青分离塔,沥青分离塔底部萃余相出口连接沥青汽提塔,沥青分离塔顶部萃取相出口连接至脱沥青油分离塔,脱沥青油分离塔底部物料出口连接脱沥青油汽提塔；各级沥青汽提塔及脱沥青油汽提塔顶部萃取溶剂出口经萃取溶剂回收单元连接至溶剂混合单元。本发明重油超临界萃取多级平行分离处理系统及处理方法,实现平行多级萃取,可同时生产多种不同规格脱沥青油或沥青产品,同时运行稳定,能耗低。(The invention relates to a heavy oil supercritical extraction multistage parallel separation treatment system, which comprises a feeding unit, a solvent mixing unit and N groups of supercritical extraction separation units which are arranged in parallel, wherein each supercritical extraction separation unit comprises an asphalt separation tower, an asphalt stripping tower, a deasphalted oil separation tower and a deasphalted oil stripping tower; and extraction solvent outlets at the tops of the asphalt stripping towers and the deasphalted oil stripping towers are connected to the solvent mixing unit through the extraction solvent recovery unit. The heavy oil supercritical extraction multistage parallel separation treatment system and the treatment method realize parallel multistage extraction, can simultaneously produce deasphalted oil or asphalt products with different specifications, and have stable operation and low energy consumption.)
1. A multistage parallel separation processing system of heavy oil supercritical fluid extraction which characterized in that: the method comprises the following steps:
a feeding unit: comprises a feeding buffer tank and a feeding pump;
a solvent mixing unit: the solvent pump is connected with the solvent cooler and then enters the N-stage mixer together with a feeding pipeline of a feeding pump;
n-stage supercritical extraction separation unit: the device comprises N groups of supercritical extraction separation units which are arranged in parallel, wherein each supercritical extraction separation unit comprises an asphalt separation tower, an asphalt stripping tower, a deasphalted oil separation tower and a deasphalted oil stripping tower;
An extraction solvent recovery unit: and extraction solvent outlets at the tops of the asphalt stripping tower and the deasphalted oil stripping tower of each supercritical extraction separation unit are connected to the solvent mixing unit through the extraction solvent recovery unit.
2. The multi-stage parallel separation processing system for heavy oil supercritical extraction as claimed in claim 1, wherein: the device comprises a solvent mixing unit, a solvent separation tower, an asphalt separation tower, a deasphalted oil separation tower and a main solvent cooler, wherein a feeding unit in each supercritical extraction separation unit is connected to the asphalt separation tower after passing through the solvent mixing unit, raffinate items at the bottom of the asphalt separation tower enter the asphalt stripping tower after passing through an asphalt removal oil heat exchanger and an asphalt removal oil heater, a bottom product outlet of the deasphalted oil separation tower enters the asphalt removal oil stripping tower after passing through the asphalt removal oil stripping tower heater.
3. The multi-stage parallel separation processing system for heavy oil supercritical extraction as claimed in claim 1, wherein: the extraction solvent recovery unit comprises a recovery solvent compressor, a recovery solvent cooler, a recovery solvent tank and a recovery solvent pump, and the extraction solvent outlet at the top of the asphalt stripping tower and the deasphalted oil stripping tower is connected to the solvent mixing unit after passing through the recovery solvent compressor, the recovery solvent cooler, the recovery solvent tank and the recovery solvent pump.
4. The multi-stage parallel separation processing system for heavy oil supercritical extraction as claimed in claim 1, wherein: the N-stage supercritical extraction separation unit can be 2-4 stages.
5. A multi-stage parallel separation processing method for heavy oil supercritical extraction is characterized in that: the method comprises the following steps:
1) feeding: a feeding pump sucks heavy oil from a feeding buffer tank and an extraction solvent from a solvent pump, the heavy oil and the extraction solvent are mixed and pressurized by a mixer and are respectively sent to an asphalt separation tower of a first-stage to N-stage supercritical extraction separation unit according to flow control;
2) subcritical extraction: performing subcritical extraction on an extraction solvent and heavy oil in an asphalt separation tower under a subcritical condition, wherein the volume ratio of the total extraction solvent to the heavy oil is 6-10:1, discharging an extraction phase from the top of the asphalt separation tower, wherein the extraction phase comprises heavy deoiled oil, deasphalted oil and the extraction solvent, discharging raffinate from the bottom of the asphalt separation tower, feeding the raffinate into an asphalt stripping tower to recover the extraction solvent, and discharging an asphalt product from the bottom of the asphalt stripping tower;
3) recovering the extraction solvent in a supercritical state: exchanging heat of the extract phase obtained in the step 2) in a deasphalted oil heat exchanger to raise the temperature, heating the extract phase to a temperature higher than the critical temperature of an extraction solvent by a deasphalted oil heater, entering a deasphalted oil separation tower, recovering the extraction solvent in a supercritical state in the deasphalted oil separation tower, extracting a bottom product of the deasphalted oil separation tower from the bottom under the control of an interface meter, conveying the bottom product to the deasphalted oil heater and a deasphalted oil stripping tower to recover the extraction solvent carried in the deasphalted oil heater, and discharging a deasphalted oil product from the bottom of the deasphalted oil stripping tower;
4) Solvent circulation: the solvents recovered in the asphalt stripping tower and the deasphalted oil stripping tower of each supercritical extraction separation unit are collected, conveyed to a recovered solvent cooler by a solvent compressor for cooling, then enter a recovered solvent tank, and then are conveyed to the inlet of a solvent pump by a recovered solvent pump; and the extraction solvent recovered by the deasphalted oil separation tower is cooled by the deasphalted oil heat exchanger and further cooled to the temperature close to the operation temperature of the asphalt separation tower by the main solvent cooler, and then is connected to the inlet of the solvent pump to complete the solvent circulation.
6. The multi-stage parallel separation processing method for heavy oil supercritical extraction as claimed in claim 5, characterized in that: the solvent ratio and the operation temperature of the N-stage supercritical extraction separation unit are adjusted according to the product requirements; the operation pressure of the first-stage asphalt separation tower is 4-5Mpag, and the operation temperature is 70-115 ℃; the operating pressure of the second-stage asphalt separation tower is 4-5Mpag, and the operating temperature is 65-110 ℃; the operation pressure of the first-stage deasphalted oil separation tower is 4-5Mpag, and the operation temperature is 100-165 ℃; the operation pressure of the secondary deasphalted oil separation tower is 4-5Mpag, and the operation temperature is 100-165 ℃.
7. The multi-stage parallel separation processing method for heavy oil supercritical extraction as claimed in claim 5, characterized in that: and (3) exchanging heat between the extraction phase in the deasphalted oil heat exchanger and the extraction solvent leaving the top of the deasphalted oil separation tower to raise the temperature.
8. The multi-stage parallel separation processing method for heavy oil supercritical extraction as claimed in claim 5, characterized in that: the extraction solvent is C3A mixed solvent of alkane and isobutane, a mixed solvent of normal butane and isobutane, or a mixed solvent of isobutane and isopentane.
9. The multi-stage parallel separation processing method for heavy oil supercritical extraction as claimed in claim 5, characterized in that: the heavy oil is atmospheric residue, vacuum residue, atmospheric residue-vacuum residue mixture or catalytic slurry oil.
Technical Field
The invention belongs to the technical field of supercritical extraction, and particularly relates to a multistage parallel separation treatment system and a treatment method for heavy oil supercritical extraction.
Background
The extraction solvent separation process is to treat liquid or liquid-solid mixture with one proper kind of extraction solvent and to dissolve the components to be separated in the mixture into the extraction solvent based on the characteristic of different solubility of the components in the mixture in the extraction solvent and the similar phase dissolving principle, so as to separate the components from other components.
The extraction solvent separation process is an important process in oil refining and chemical industry, and is widely applied to the oil refining industry. For example, deasphalting with an extraction solvent for obtaining a lubricating oil feedstock and a catalytic cracking feedstock from heavy oil, refining with an extraction solvent and dewaxing with an extraction solvent used in the production of lubricating oils, and extraction of aromatic hydrocarbons for extracting aromatic hydrocarbons from reformate oil or catalytic cracking cycle oil are all extraction solvent separation processes.
In the oil refining industry, the extraction solvent deasphalting process is mainly used for preparing high-viscosity lubricating oil base oil and catalytic cracking raw oil from vacuum residue, and the deasphalted asphalt can be used for producing road asphalt under the condition of proper raw materials. The main function of the extraction solvent deasphalting process is to remove the asphalt from the heavy oil to obtain deasphalted oil with lower carbon residue and improved color. The vacuum residue is added into catalytic cracking raw material gas oil to be an important way for improving the yield of light oil, but many vacuum residues contain more metals and substances which are easy to generate coke, and are not easy to be directly added into the catalytic cracking raw material, and most of the metals and the substances which are easy to generate coke can be removed through deasphalting of an extraction solvent, so that the quality of the heavy oil catalytic cracking feed is obviously improved.
The traditional deasphalting process of extraction solvent is operated under the conditions of temperature and pressure below the critical point of the extraction solvent. The process uses a large amount of extraction solvent, the ratio of the extraction solvent used is generally 3-5 (mass ratio), and the extraction solvent must be recovered and recycled. The investment and operating costs of the extraction solvent recovery section have a significant impact on the overall plant economics. Of the amount of extraction solvent to be recovered, about 90% comes from the extract (deasphalted oil phase) and the rest comes from the raffinate (deasphalted oil phase). Therefore, the recovery of the extraction solvent is important to recover the extraction solvent in the extraction liquid. In recent years, research and technical development have been greatly advanced on extraction with a supercritical extraction solvent and recovery of the supercritical extraction solvent, which are operated under conditions of temperature and pressure at or above the critical point of the extraction solvent. Compared with the traditional extraction solvent deasphalting technology, the supercritical extraction technology has qualitative leap in the aspects of energy consumption, operation reliability and the like.
The traditional extraction solvent deasphalting technology is two products, namely asphalt product and deasphalted oil product. Products with different specifications and qualities, such as lubricating oil base oil, can not be produced simultaneously, the products are classified in multiple ways and have different specifications, one device can only produce one specification product simultaneously, and if products with other specifications are produced, the operation conditions need to be adjusted, so that the device is not flexible. And the maximum treatment capacity is limited due to the limitation of manufacturing a high-pressure container, wherein an extraction tower and an extraction solvent separation tower belong to the high-pressure container, the operating pressure is 40-50bar, and the large-diameter container is difficult to manufacture.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a multistage parallel separation treatment system for heavy oil supercritical extraction.
The invention also aims to provide a multistage parallel separation treatment method for heavy oil supercritical extraction.
The technical problem to be solved by the invention is realized by the following technical scheme:
a multistage parallel separation processing system of heavy oil supercritical fluid extraction which characterized in that: the method comprises the following steps:
a feeding unit: comprises a feeding buffer tank and a feeding pump;
a solvent mixing unit: the solvent pump is connected with the solvent cooler and then enters the N-stage mixer together with a feeding pipeline of a feeding pump;
n-stage supercritical extraction separation unit: the device comprises N groups of supercritical extraction separation units which are arranged in parallel, wherein each supercritical extraction separation unit comprises an asphalt separation tower, an asphalt stripping tower, a deasphalted oil separation tower and a deasphalted oil stripping tower;
An extraction solvent recovery unit: and extraction solvent outlets at the tops of the asphalt stripping tower and the deasphalted oil stripping tower of each supercritical extraction separation unit are connected to the solvent mixing unit through the extraction solvent recovery unit.
And the feeding unit in each supercritical extraction separation unit is connected to the asphalt separation tower after passing through the solvent mixing unit, the raffinate at the bottom of the asphalt separation tower enters the asphalt stripping tower after passing through the asphalt stripping tower heater, the extract phase outlet at the top of the asphalt separation tower enters the deasphalted oil separation tower after passing through the deasphalted oil heat exchanger and the deasphalted oil heater, the bottom product outlet of the deasphalted oil separation tower enters the deasphalted oil stripping tower after passing through the deasphalted oil stripping tower heater, and the product outlet at the top of the deasphalted oil separation tower is connected to the solvent mixing unit through the main solvent cooler after passing through the deasphalted oil heat exchanger.
And, the extraction solvent recovery unit is including retrieving the solvent compressor, retrieve the solvent cooler, retrieve the solvent jar, retrieve the solvent pump, pitch stripper and deasphalted oil stripper top extraction solvent export is connected to after retrieving solvent compressor, retrieving the solvent cooler, retrieving the solvent jar, retrieving the solvent pump the solvent mixing unit.
Moreover, the N-stage supercritical extraction separation unit can be 2-4 stages.
A multi-stage parallel separation processing method for heavy oil supercritical extraction is characterized in that: the method comprises the following steps:
1) feeding: a feeding pump sucks heavy oil from a feeding buffer tank and an extraction solvent from a solvent pump, the heavy oil and the extraction solvent are mixed and pressurized by a mixer and are respectively sent to an asphalt separation tower of a first-stage to N-stage supercritical extraction separation unit according to flow control;
2) subcritical extraction: performing subcritical extraction on an extraction solvent and heavy oil in an asphalt separation tower under a subcritical condition, wherein the volume ratio of the total extraction solvent to the heavy oil is 6-10:1, discharging an extraction phase from the top of the asphalt separation tower, wherein the extraction phase comprises heavy deoiled oil, deasphalted oil and the extraction solvent, discharging raffinate from the bottom of the asphalt separation tower, feeding the raffinate into an asphalt stripping tower to recover the extraction solvent, and discharging an asphalt product from the bottom of the asphalt stripping tower;
3) recovering the extraction solvent in a supercritical state: exchanging heat of the extract phase obtained in the step 2) in a deasphalted oil heat exchanger to raise the temperature, heating the extract phase to a temperature higher than the critical temperature of an extraction solvent by a deasphalted oil heater, entering a deasphalted oil separation tower, recovering the extraction solvent in a supercritical state in the deasphalted oil separation tower, extracting a bottom product of the deasphalted oil separation tower from the bottom under the control of an interface meter, conveying the bottom product to the deasphalted oil heater and a deasphalted oil stripping tower to recover the extraction solvent carried in the deasphalted oil heater, and discharging a deasphalted oil product from the bottom of the deasphalted oil stripping tower;
4) Solvent circulation: the solvents recovered in the asphalt stripping tower and the deasphalted oil stripping tower of each supercritical extraction separation unit are collected, conveyed to a recovered solvent cooler by a solvent compressor for cooling, then enter a recovered solvent tank, and then are conveyed to the inlet of a solvent pump by a recovered solvent pump; and the extraction solvent recovered by the deasphalted oil separation tower is cooled by the deasphalted oil heat exchanger and further cooled to the temperature close to the operation temperature of the asphalt separation tower by the main solvent cooler, and then is connected to the inlet of the solvent pump to complete the solvent circulation.
Moreover, the solvent ratio and the operation temperature of the N-stage supercritical extraction separation unit are adjusted according to the product requirements; the operation pressure of the first-stage asphalt separation tower is 4-5Mpag, and the operation temperature is 70-115 ℃; the operating pressure of the second-stage asphalt separation tower is 4-5Mpag, and the operating temperature is 65-110 ℃; the operation pressure of the first-stage deasphalted oil separation tower is 4-5Mpag, and the operation temperature is 100-165 ℃; the operation pressure of the secondary deasphalted oil separation tower is 4-5Mpag, and the operation temperature is 100-165 ℃.
And in the step 3), the extract phase exchanges heat with the extraction solvent leaving the top of the deasphalted oil separation tower in the deasphalted oil heat exchanger and is heated.
And, the extraction solvent is C 3A mixed solvent of alkane and isobutane, a mixed solvent of normal butane and isobutane, or a mixed solvent of isobutane and isopentane.
And, the heavy oil is atmospheric residue, vacuum residue, atmospheric residue-vacuum residue mixture, or catalytic slurry oil.
The invention has the advantages and beneficial effects that:
1. the heavy oil supercritical extraction multistage parallel separation treatment system comprises a feeding unit, a solvent mixing unit, an N-stage supercritical extraction separation unit and an extraction solvent recovery unit, wherein the N-stage supercritical extraction separation unit can be 2-6 stages, and different operation parameters can be set for each stage of supercritical extraction separation unit, so that the product flexibility is increased, the production of products with different qualities is realized by sharing a solvent system, the productivity is increased, the flow operation is simplified, the online rate and the reliability of the device are improved, and the investment and the device occupation are reduced. Providing high quality feed to downstream process units.
2. The heavy oil supercritical extraction multistage parallel separation treatment system reduces the energy consumption of the device by sharing a solvent system, and is extremely favorable for ensuring the stability of the device.
3. The heavy oil supercritical extraction multistage parallel separation processing method of the invention realizes the purpose of producing products with different specifications by adjusting the operation conditions of N-stage supercritical extraction separation units, namely the solvent ratio and the operation temperature, for example, the temperature of the top of each corresponding asphalt separation tower is respectively controlled by each stage of solvent cooler, thereby controlling the yield of each stage of heavy deoiling and deasphalting oil.
4. The heavy oil supercritical extraction multistage parallel separation treatment system and the treatment method realize parallel multistage extraction, increase the processing capacity, can simultaneously produce deasphalted oil or asphalt products with different specifications, and have stable operation and low energy consumption.
Drawings
FIG. 1 is a flow chart of the system of the present invention.
Reference numerals:
1-buffer tank, 2-feeding pump, 3-solvent pump, 4-first solvent cooler, 5-second solvent cooler, 6-first mixer, 7-second mixer, 8-first asphalt separator, 9-first asphalt stripper heater, 10-first asphalt stripper, 11-first deasphalted oil stripper, 12-first deasphalted oil stripper heater, 13-first deasphalted oil separator, 14-first deasphalted oil heater, 15-recovered solvent compressor, 16-first deasphalted oil heat exchanger, 17-recovered solvent cooler, 18-recovered solvent tank, 19-recovered solvent pump, 20-second asphalt separator, 21-second asphalt stripper heater, 22-second asphalt stripper, 23-a secondary deasphalted oil stripping tower, 24-a secondary deasphalted oil stripping tower heater, 25-a secondary deasphalted oil separation tower, 26-a secondary deasphalted oil heat exchanger, 27-a secondary deasphalted oil heater and 28-a main solvent cooler.
Detailed Description
The present invention is further illustrated by the following specific examples, which are intended to be illustrative, not limiting and are not intended to limit the scope of the invention.
A multi-stage parallel separation treatment system for heavy oil supercritical extraction comprises:
a feeding unit: comprises a feeding buffer tank 1 and a feeding pump 2;
a solvent mixing unit: the device comprises a solvent pump 3, a primary solvent cooler 4, a secondary solvent cooler 5, a primary mixer 6 and a secondary mixer 7, wherein the solvent pump is respectively converged with a primary feeding pipeline and a secondary feeding pipeline of a feeding pump through the primary solvent cooler and the secondary solvent cooler and then respectively enters the primary mixer and the secondary mixer;
n-stage supercritical extraction separation unit: comprises N groups of supercritical extraction separation units which are arranged in parallel, and the N-level supercritical extraction separation units can be 2-6 levels. In this embodiment, the two-stage supercritical extraction separation unit includes a first-stage supercritical extraction separation unit and a second-stage supercritical extraction separation unit.
The primary supercritical extraction separation unit comprises a primary asphalt separation tower 8, a primary asphalt stripping tower 10, a primary deasphalted oil separation tower 13 and a primary deasphalted oil stripping tower 11, a primary mixer is connected to the primary asphalt separation tower of the primary supercritical extraction separation unit, a raffinate phase outlet at the bottom of the primary asphalt separation tower is connected with the primary asphalt stripping tower, an extract phase outlet at the top of the primary asphalt separation tower is connected to the primary deasphalted oil separation tower, and a material outlet at the bottom of the primary deasphalted oil separation tower is connected with the primary deasphalted oil stripping tower;
A feeding unit in a first-stage supercritical extraction separation unit is connected to a first-stage asphalt separation tower after passing through a solvent mixing unit, raffinate items at the bottom of the first-stage asphalt separation tower enter a first-stage asphalt stripping tower 10 after passing through a first-stage asphalt stripping tower heater 9, an extract phase outlet at the top of the first-stage asphalt separation tower enters the first-stage deasphalted oil separation tower after passing through a first-stage deasphalted oil heat exchanger 16 and a first-stage deasphalted oil heater 14, a bottom product outlet of the first-stage deasphalted oil separation tower enters the first-stage deasphalted oil stripping tower through a first-stage deasphalted oil stripping tower heater 12, and a top product outlet of the first-stage deasphalted oil separation tower passes through a first-stage deasphalted oil heat exchanger 16 and then.
The second-stage supercritical extraction separation unit comprises a second-stage asphalt separation tower 20, a second-stage asphalt stripping tower 22, a second-stage deasphalted oil separation tower 25 and a second-stage deasphalted oil stripping tower 23, a second-stage mixer is connected to the second-stage asphalt separation tower of the second-stage supercritical extraction separation unit, a raffinate phase outlet at the bottom of the second-stage asphalt separation tower is connected with the second-stage asphalt stripping tower, an extract phase outlet at the top of the second-stage asphalt separation tower is connected to the second-stage deasphalted oil separation tower, and a material outlet at the bottom of the second-stage deasphalted oil separation tower;
A feeding unit in the secondary supercritical extraction separation unit is connected to a secondary asphalt separation tower after passing through a solvent mixing unit, raffinate items at the bottom of the secondary asphalt separation tower enter a secondary asphalt stripping tower after passing through a secondary asphalt stripping tower heater 21, an extract phase outlet at the top of the secondary asphalt separation tower enters the secondary deasphalted oil separation tower after passing through a secondary deasphalted oil heat exchanger 26 and a secondary deasphalted oil heater 27, a bottom product outlet of the secondary deasphalted oil separation tower enters the secondary deasphalted oil stripping tower through a secondary deasphalted oil stripping tower heater 24, and a top product outlet of the secondary deasphalted oil separation tower is connected to a solvent pump of the solvent mixing unit through a main solvent cooler after passing through the secondary deasphalted oil heat exchanger 26.
An extraction solvent recovery unit: and the extraction solvent outlets at the tops of the primary asphalt stripping tower, the primary deasphalted oil stripping tower, the secondary asphalt stripping tower and the secondary deasphalted oil stripping tower of the primary supercritical extraction separation unit are connected to the solvent mixing unit through the extraction solvent recovery unit.
The extraction solvent recovery unit comprises a recovery solvent compressor 15, a recovery solvent cooler 17, a recovery solvent tank 18 and a recovery solvent pump 19, and an extraction solvent outlet at the top of a first-stage asphalt stripping tower, a first-stage deasphalted oil stripping tower, a second-stage asphalt stripping tower and a second-stage deasphalted oil stripping tower is connected to the solvent mixing unit through the recovery solvent compressor, the recovery solvent cooler, the recovery solvent tank and the recovery solvent pump.
A multi-stage parallel separation treatment method for heavy oil supercritical extraction comprises the following steps:
1) feeding: the heavy oil is sucked from the feeding buffer tank by the feeding pump and is mixed with the extraction solvent from the solvent pump by the mixer, the mixture is pressurized and is respectively sent to the asphalt separating tower of the first-stage and second-stage supercritical extraction separation units according to the flow control;
2) subcritical extraction: performing subcritical extraction on an extraction solvent and heavy oil in a first-stage asphalt separation tower and a first-stage asphalt separation tower under a subcritical condition, wherein the volume ratio of the total extraction solvent to the heavy oil is 8:1, discharging an extraction phase from the top of the first-stage asphalt separation tower, wherein the extraction phase comprises heavy deoiled oil, deasphalted oil and the extraction solvent, discharging raffinate from the bottom of the first-stage asphalt separation tower, respectively entering a first-stage asphalt stripping tower to recover the extraction solvent, and discharging an asphalt product from the bottom of the first-stage asphalt stripping tower;
3) recovering the extraction solvent in a supercritical state: the extract phase obtained in the step 2) is subjected to heat exchange and temperature rise in a primary deasphalted oil heat exchanger, then is heated to a temperature higher than the critical temperature of an extraction solvent by a primary deasphalted oil heater, enters a primary deasphalted oil separation tower, the extraction solvent is recovered in the supercritical state in the primary deasphalted oil separation tower, a bottom product of the primary deasphalted oil separation tower is extracted from the bottom under the control of an interface meter, and is sent to the primary deasphalted oil heater and a primary deasphalted oil stripping tower to recover the extraction solvent carried in the deasphalted oil heater, and a deasphalted oil product is discharged from the bottom of the primary deasphalted oil stripping tower; the extract phase exchanges heat with the extraction solvent leaving the top of the deasphalted oil separation tower in the deasphalted oil heat exchanger and is heated.
The step of recovering the extraction solvent from the subcritical extractant in the secondary supercritical extraction separation unit in a supercritical state is the same as the step 2) and the step 3) in the primary supercritical extraction separation unit, and the solvent ratio and the operation temperature of the primary supercritical extraction separation unit and the secondary supercritical extraction separation unit are adjusted according to the product requirements. The operation pressure of the first-stage asphalt separation tower is 4-5Mpag, the operation temperature is 70-115 ℃, the operation pressure of the second-stage asphalt separation tower is 4-5Mpag, the operation temperature is 65-110 ℃, the operation pressure of the first-stage deasphalted oil separation tower is 4-5Mpag, the operation temperature is 100-165 ℃, the operation pressure of the second-stage deasphalted oil separation tower is 4-5Mpag, and the operation temperature is 100-165 ℃.
4) Solvent circulation: the solvent recovered in a first-stage asphalt stripping tower, a first-stage deasphalted oil stripping tower of a first-stage supercritical extraction separation unit, a second-stage asphalt stripping tower and a second-stage asphalt oil stripping tower of a second-stage supercritical extraction separation unit are converged, conveyed to a recovered solvent cooler by a solvent compressor, cooled, then enters a recovered solvent tank, and then is conveyed to the inlet of a solvent pump by a recovered solvent pump; and the extraction solvent recovered by the deasphalted oil separation tower is cooled by the deasphalted oil heat exchanger and further cooled to the temperature close to the operation temperature of the asphalt separation tower by the main solvent cooler, and then is connected to the inlet of the solvent pump to complete the solvent circulation.
The extraction solvent is C3To C5One or a mixture of two or more of alkanes. Taking a solvent as C3A mixed solvent of alkane and isobutane, a mixed solvent of normal butane and isobutane, or a mixed solvent of isobutane and isopentane. The heavy oil is atmospheric residue, vacuum residue, atmospheric residue-vacuum residue mixture or catalytic slurry oil.
The process parameters of the treatment method are illustrated as follows:
1. the extraction solvent is propane;
the volume ratio of the extraction solvent of the first-stage asphalt separation tower to the heavy oil is 8: 1;
the volume ratio of the extraction solvent of the second-stage asphalt separation tower to the heavy oil is 8: 1;
the operation pressure of the first-stage asphalt separation tower is 4-5Mpag, and the operation temperature is 70-75 DEG C
The operation pressure of the second-stage asphalt separation tower is 4-5Mpag, and the operation temperature is 65-70 DEG C
The operation pressure of the first-stage deasphalted oil separation tower is 4-5Mpag, the operation temperature is 100-105 ℃, the operation pressure of the second-stage deasphalted oil separation tower is 4-5Mpag, and the operation temperature is 100-105 ℃. The yield and physical properties of the asphalt product obtained by the first-stage extraction and the deasphalted oil product are shown in Table 1.
TABLE 1 first order extraction product distribution and physical Properties
Physical Properties
Heavy oil
Asphalt
Deasphalted oil
Yield wt%
100
80.1
19.9
Yield, lv%
100
77.8
22.2
Specific gravity @15.6 DEG C
1.0130
1.0421
0.9108
API gravity
8.2
4.3
23.9
Nitrogen, wt%
0.3
0.4
0.1
Sulfur, wt.%
3.9
4.4
2.0
Residual carbon in wt%
17.0
20.9
1.5
Nickel wppm
30.0
37.4
0.3
Wppm of vanadium
93.0
116.1
0.3
Viscosity of the oil
[email protected]
100
C
615
3315
14
[email protected]
135
C
107
367
6
[email protected]
177
C
28
69
3
[email protected]
232
C
15
30
2
[email protected]
289
C
7
12
2
The yield and physical properties of the asphalt product obtained by the secondary extraction and the deasphalted oil product are shown in Table 2.
TABLE 2 Secondary extraction product distribution and Properties
As can be seen from Table 2, the same extraction solvent can obtain deasphalted oil with different qualities at different extraction temperatures, and the viscosity of asphalt products, the yield of the deasphalted oil, and the content of residual carbon and heavy metal are obviously different.
2. The extraction solvent was isobutane.
The supercritical heavy oil treatment of the present invention is carried out in a system as shown in fig. 1.
The volume ratio of the extraction solvent of the first-stage asphalt separation tower to the heavy oil is 8: 1;
the volume ratio of the extraction solvent of the second-stage asphalt separation tower to the heavy oil is 8: 1;
the operation pressure of the first-stage asphalt separation tower is 4-5Mpag, and the operation temperature is 110-115 DEG C
The operation pressure of the second-stage asphalt separation tower is 4-5Mpag, the operation temperature is 105-110 DEG C
The operation pressure of the first-stage deasphalted oil separation tower is 4-5Mpag, the operation temperature is 155-165 DEG C
The operation pressure of the secondary deasphalted oil separation tower is 4-5Mpag, the operation temperature is 155-165 DEG C
The yield and physical properties of the asphalt product obtained by the first-stage extraction are shown in Table 3.
TABLE 3 first order extraction product distribution and physical Properties
Physical Properties
Heavy oil
Asphalt
Deasphalted oil
Yield wt%
100
50.9
49.1
Specific gravity @15.6 DEG C
1.0130
1.0846
0.9480
Yield, lv%
100
47.6
52.4
API gravity
8.2
-1.0
17.8
Nitrogen, wt%
0.3
0.5
0.1
Sulfur, wt.%
3.9
5.1
2.7
Residual carbon in wt%
17.0
29.5
4.0
Nickel wppm
30.0
57.2
1.7
Wppm of vanadium
93.0
178.6
4.1
Viscosity of the oil
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100
C
615
65899
48
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135
C
107
3244
16
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177
C
577
58886
47
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232
C
9
48
3
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289
C
4
15
2
TABLE 4 Secondary extraction product distribution and Properties
In this example 4, it can be seen that, under different extraction temperatures, the same solvent can obtain deasphalted oil with different qualities, and the viscosity of asphalt products, the yield of deasphalted oil, and the content of carbon residue and heavy metal are significantly different.
Although the embodiments of the present invention and the accompanying drawings have been disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, alterations, and modifications are possible without departing from the spirit and scope of the invention and the appended claims, and thus the scope of the invention is not limited to the embodiments and drawings disclosed.
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