阅读说明：本技术 一种基于超临界甲醇的重油减黏与脱硫方法 (Heavy oil viscosity reducing and desulfurizing method based on supercritical methanol ) 是由 闫挺 罗璇 赵向勃 高晓明 付峰 杨春明 王传涛 于 2021-09-13 设计创作，主要内容包括：本发明公开了一种基于超临界甲醇的重油减黏与脱硫方法,在超临界甲醇环境下对重油进行改质反应,主要是通过温度与压力的控制,将重油置于超临界甲醇环境中保持一定时间,一方面调节超临界甲醇对于重油中各组分的溶解能力,使其中的大分子裂解成较小的分子的同时抑制大分子间的聚合,一方面调节甲醇供氢等反应性能,实现重油在抑制结焦前提下的减粘与脱硫。采用该方法不需要催化剂可以提高重油减黏反应的转化率、反应速率、避免体系的结焦现象,降低硫氮等杂原子含量。(The invention discloses a heavy oil viscosity reducing and desulfurizing method based on supercritical methanol, which is characterized in that heavy oil is subjected to modification reaction in a supercritical methanol environment, the heavy oil is placed in the supercritical methanol environment for a certain time mainly through temperature and pressure control, on one hand, the dissolving capacity of the supercritical methanol for each component in the heavy oil is adjusted, macromolecules in the heavy oil are cracked into smaller molecules, and meanwhile, the polymerization among the macromolecules is inhibited, on the other hand, the reactivity of methanol for hydrogen supply and the like is adjusted, and the viscosity reducing and desulfurizing of the heavy oil under the condition of inhibiting coking are realized. The method can improve the conversion rate and the reaction rate of heavy oil viscosity-reducing reaction without a catalyst, avoid the coking phenomenon of a system and reduce the content of heteroatoms such as sulfur, nitrogen and the like.)

1. A heavy oil viscosity reducing and desulfurizing method based on supercritical methanol is characterized by comprising the following steps:

step S1: preheating heavy oil, adding into reaction kettle, adding methanol in proportion, stirring, mixing, introducing N into the reaction kettle₂Discharging the air in the kettle, heating, continuously stirring, and then maintaining the temperature and the pressure for reaction;

step S2: and (4) stopping heating after the reaction in the step S1 is finished, quickly discharging the vaporized oil-water mixed material by using the pressure in the reaction kettle, condensing the discharged material through a heat exchanger, collecting the condensed material in a receiving container, standing and separating the condensed material into an oil phase and an alcohol phase, washing the oil phase in the reaction kettle by using a solvent, filtering and separating the solvent to obtain an eluate, and mixing the oil phase separated in the receiving container with the eluate in the reaction kettle to obtain the viscosity-reducing oil.

2. The method for viscosity breaking and desulfurization of heavy oil based on supercritical methanol according to claim 1, wherein the preheating temperature of heavy oil in step S1 is 80-120 ℃.

3. The method for viscosity breaking and desulfurization of heavy oil based on supercritical methanol according to claim 1, wherein the mass ratio of methanol added in step S1 to the heavy oil feedstock is 0.5-2: 1.

4. The method as claimed in claim 1, wherein the stirring speed in step S1 is 900-1000 r/min.

5. The method for reducing viscosity and desulfurizing heavy oil by supercritical methanol according to claim 1, wherein the temperature is raised to 350-420 ℃ in step S1, the pressure is 15-22 MPa, and the temperature raising rate is 10-15 ℃ min^-1。

6. The method for viscosity breaking and desulfurization of heavy oil based on supercritical methanol according to claim 1, wherein the reaction time in step S1 is 30-120 min.

7. The method for reducing viscosity and desulfurizing heavy oil by supercritical methanol according to claim 1, wherein the washing with the solvent in the reaction kettle in the step S2, and the specific method for filtering and separating the solvent to obtain the eluate are as follows: and (3) washing the reaction kettle with toluene at 100-150 ℃, filtering out toluene insoluble substances, and separating and recovering toluene to obtain an eluate, wherein the toluene is separated by using a rotary evaporation mode.

8. The method for viscosity breaking and desulfurization of heavy oil based on supercritical methanol according to claims 1 to 7, wherein the light oil product in the heavy oil accounts for 60 to 80% by weight of the heavy oil feedstock.

9. The method for viscosity breaking and desulfurization of heavy oil based on supercritical methanol according to claim 1, wherein the agitation mixing in step S1 is ultrasonic vibration mixing.

Technical Field

The invention relates to the field of heavy oil viscosity reduction and desulfurization, in particular to a heavy oil viscosity reduction and desulfurization method based on supercritical methanol.

Background

In recent years, rapid development of human society is not supported by fossil energy, and petroleum resources are currently used as the most widely demanded energy, and the reserves thereof are decreasing and the quality thereof is becoming more and more important. At present, oil sand bitumen, super heavy oil and other heavy oil products are used as one of the most energy sources in the world, the global storable and recoverable amount is about 4000 hundred million tons, which is 2.7 times of that of conventional crude oil, so that how to more reasonably and effectively utilize the heavy oil products is important in the key period that the current energy demand is continuously increased and the novel energy sources are not enough to comprehensively meet the social demand.

Although the existing heavy oil treatment processes such as hydrocracking, catalytic cracking, delayed coking and the like can effectively process and treat heavy oil, the production and environmental protection requirements of the technologies are increasingly not met due to inherent defects of the technologies in the aspects of economy, environmental protection, heavy oil utilization rate and the like. The supercritical hydrothermal upgrading process is a novel environment-friendly green process, and the basic idea is that the supercritical hydrothermal upgrading process is used as a solvent and a dispersant for heavy oil upgrading by utilizing the characteristic that water has high solubility to organic matters under a supercritical condition. Under the supercritical water-heat condition, small molecular hydrocarbons and macromolecular radical fragments generated by heavy oil cracking are continuously transferred from the oil phase to the supercritical water phase, so that the macromolecular radical fragments which are easy to collide with each other and coke are well dispersed in the supercritical water phase, and the heavy oil is continuously cracked into hydrocarbons with smaller molecular weight. In addition, the supercritical hydrothermal modification process of the heavy oil also has the effects of desulfurization, denitrification and reduction of heavy metal content.

The patent US7740065B2 discloses a method for upgrading full-component crude oil by using high-pressure hot water and reflux fluid, which mainly recycles fluid recovered in the process of crude oil upgrading to improve the extraction rate of crude oil, and carries out upgrading again on heavy components obtained after the extracted crude oil is flashed under the condition of supercritical water, wherein the reflux fluid in the method is mainly pressurized fluid consisting of CO2, N2, CH4 and water vapor. Although the method can improve the extraction rate and the upgrading effect of crude oil, the pressure resistance and corrosion resistance requirements on equipment and pipelines are increased due to the use of the pressurized recovery fluid.

Patent CN101970611A and patent CN102834489A disclose a method for upgrading heavy oil by hot pressurized water and an ultrasonic wave generating premixer and a method for mixing water, oxidant and heavy oil under supercritical temperature and pressure conditions and finally subjecting the mixture to microwave treatment, respectively, which mainly utilize ultrasonic wave or the combined action of oxidant and ultrasonic wave to promote the mixing of oil-water two phases and heavy oil cracking. Wherein the oxidant described in patent CN102834489A is selected from solid additives such as oxygen, air, hydrogen peroxide, organic peroxide, inorganic superoxide, sulfuric acid, nitric acid, etc.

Patent CN108251154A discloses a heavy oil visbreaking method based on supercritical benzene and its application. The method refers to placing heavy oil in a supercritical benzene environment in a specific thermodynamic state, so that visbreaking of the heavy oil is carried out from high viscosity to the supercritical benzene, and how to realize the specific supercritical benzene environment is not clear.

Patent CN107022373A discloses a process for reducing viscosity of heavy oil by hydrothermal cracking, which uses cracked light components as new diluent to mix with heavy oil to reduce its viscosity, and then shallow hydrothermal cracking is performed.

Patent CN111690429A is a supercritical hydrothermal viscosity reduction method for oil sand asphalt. But the method ignores the influence of supercritical water on equipment materials.

In order to solve the problems of harsh reaction conditions, low conversion rate, easy coking of a system and the like of the current heavy oil supercritical fluid processing technology, a heavy oil viscosity reducing and desulfurizing method based on supercritical methanol is provided, heavy oil is subjected to upgrading reaction in a supercritical methanol environment, the heavy oil is placed in the supercritical methanol environment for a certain time mainly through temperature and pressure control, on one hand, the dissolving capacity of the supercritical methanol on various components in the heavy oil is adjusted, so that macromolecules in the heavy oil are cracked into smaller molecules, on the other hand, the reactivity performance of methanol for hydrogen supply and the like is adjusted, and the viscosity reducing and desulfurizing of the heavy oil under the condition of inhibiting coking are realized. The method can improve the conversion rate of heavy oil viscosity-reducing reaction without a catalyst, avoid the coking phenomenon of a system and reduce the content of heteroatoms such as sulfur, nitrogen and the like.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a heavy oil viscosity reducing and desulfurizing method based on supercritical methanol, wherein heavy oil is subjected to modification reaction in a supercritical methanol environment, the heavy oil is placed in the supercritical methanol environment for a certain time mainly through temperature and pressure control, on one hand, the dissolving capacity of the supercritical methanol on each component in the heavy oil is adjusted, so that macromolecules in the heavy oil are cracked into smaller molecules, on the other hand, the reactivity of methanol for hydrogen supply and the like is adjusted, and the viscosity reducing and desulfurizing of the heavy oil under the condition of inhibiting coking are realized. The method can improve the conversion rate of heavy oil viscosity-reducing reaction without a catalyst, avoid the coking phenomenon of a system and reduce the content of heteroatoms such as sulfur, nitrogen and the like.

In order to realize the technical purpose, the following technical scheme is adopted:

a heavy oil viscosity reducing and desulfurizing method based on supercritical methanol comprises the following steps:

step S1: preheating heavy oil, adding into reaction kettle, adding methanol in proportion, stirring, mixing, introducing N into the reaction kettle₂Discharging the air in the kettle, heating, continuously stirring, and then maintaining the temperature and the pressure for reaction;

step S2: and (4) stopping heating after the reaction in the step S1 is finished, quickly discharging the vaporized oil-water mixed material by using the pressure in the reaction kettle, condensing the discharged material through a heat exchanger, collecting the condensed material in a receiving container, standing and separating the condensed material into an oil phase and an alcohol phase, washing the oil phase in the reaction kettle by using a solvent, filtering and separating the solvent to obtain an eluate, and mixing the oil phase separated in the receiving container with the eluate in the reaction kettle to obtain the viscosity-reducing oil.

Further, the preheating temperature of the heavy oil in the step S1 is 80-120 ℃.

Further, the mass ratio of the methanol added in the step S1 to the heavy oil raw material is 0.5-2: 1.

Further, the stirring speed in the step S1 is 900-.

Further, in the step S1, the temperature is raised to 350-420 ℃, the pressure is 15-22 MPa, and the temperature raising rate is 10-15 ℃ min^-1。

Further, the reaction time in the step S1 is 30-120 min.

Further, the specific method of washing the reaction kettle with the solvent in the step S2, and filtering and separating the solvent to obtain the eluate includes: and (3) washing the reaction kettle with toluene at 100-150 ℃, filtering out toluene insoluble substances, and separating and recovering toluene to obtain an eluate, wherein the toluene is separated by using a rotary evaporation mode.

Furthermore, the light oil product in the heavy oil accounts for 60-80% of the weight of the heavy oil raw material.

Further, the stirring and mixing in step S1 may be ultrasonic vibration mixing.

The invention has the beneficial effects that:

the invention discloses a heavy oil viscosity reducing and desulfurizing method based on supercritical methanol, which is characterized in that heavy oil is subjected to modification reaction in a supercritical methanol environment, the heavy oil is placed in the supercritical methanol environment for a certain time mainly through temperature and pressure control, on one hand, the dissolving capacity of the supercritical methanol for each component in the heavy oil is adjusted, so that macromolecules in the heavy oil are cracked into smaller molecules, on the other hand, the reactivity of methanol for hydrogen supply and the like is adjusted, and viscosity reduction and desulfurization of the heavy oil under the premise of inhibiting coking are realized. The method can improve the conversion rate of heavy oil viscosity-reducing reaction without a catalyst, avoid the coking phenomenon of a system and reduce the content of heteroatoms such as sulfur, nitrogen and the like.

Drawings

FIG. 1 is a flow chart of reaction separation analysis of a heavy oil + supercritical methanol system.

Detailed Description

The invention will be further described with reference to the accompanying drawings, without limiting the scope of the invention to the following:

in order to better understand the technical scheme of the invention, the reaction process is described as follows:

connecting the reaction kettle according to a design chart required by an experiment, carefully cleaning the inner wall and the kettle cover of the reaction kettle, and ensuring the tight sealing of the high-pressure reaction kettle.

1) Preheating heavy oil to 80 ℃, weighing a proper amount of heavy oil, placing the heavy oil in a high-pressure reaction kettle, and then adding a certain amount of methanol according to a preset mass ratio;

2) placing the autoclave filled with reactants in an ultrasonic cleaner, oscillating for 20min to preliminarily mix the heavy oil and the methanol, so that the methanol soluble part in the heavy oil is dissolved in the methanol;

3) taking out the reaction kettle after ultrasonic treatment, placing the reaction kettle in a heating electric furnace, covering the reaction kettle with a kettle cover for sealing, and introducing N into the reaction kettle₂Air in the kettle is discharged, so that the influence of oxygen on the reaction is avoided;

4) setting reaction temperature and stirring speed; when the temperature of the reaction kettle rises to 100 ℃, starting magnetic stirring, and adjusting the heating voltage to 10 ℃ min^-1The temperature rise rate of (1) is increased. Starting timing after the set temperature is reached, recording the pressure change in the kettle at the temperature, keeping the pressure at 15-22 MPa, keeping the temperature for reaction time, and stopping heating;

5) after the reaction time is up, collecting gas generated by the reaction through a gas bag, then unloading the autoclave cover, and separating the reaction product, namely the alcohol-oil system.

The product separation method comprises the following steps: the product separation process is shown in FIG. 1. The toluene wash collected all cracked products (containing methanol, oil and residual coke) were refluxed and allowed to stand overnight. Then toluene solution dissolved with liquid phase product is removed toluene and methanol by rotary evaporation to obtain liquid phase product.

The method comprises the following specific steps: adding a proper amount of toluene into the oil phase, carrying out ultrasonic treatment for 10min, standing for 30min, and filtering to obtain a filter cake and a toluene soluble filtrate. And (3) putting the filter paper into an extractor, performing primary extraction for 12 hours by using the toluene soluble filtrate until the solution in the extractor is colorless, and performing rotary evaporation on the toluene soluble filtrate to remove toluene to obtain the asphaltene and the maltha. Dissolving the asphaltene and the maltha with an n-heptane solvent, standing for 60min, and filtering to obtain a filter cake and an n-heptane soluble fraction filtrate. And performing Soxhlet extraction on the filter paper until the solution in the extractor is colorless. N-heptane was removed by rotary evaporation to give malthate (n-heptane soluble fraction). The residue on the filter paper was asphaltenes. Finally, the components collected after the solvent is recovered are put into a vacuum oven and are kept for a plurality of hours under the conditions that the temperature is 105-110 ℃ and the vacuum degree is 93 +/-1 kPa. Taking out the sample, cooling the sample to room temperature in a dryer filled with a drying agent, and weighing the sample to respectively obtain the mass of the n-heptane soluble component, the asphaltene and the residual coke.

All used experimental articles such as absorbent cotton, filter paper tube, beaker, flask, glass stick in this application are through dry constant weight.

The application defines asphaltenes and residual coke as polycondensation products and the components with a distillation range below 380 ℃ as light components. The calculation formula of the content of the polycondensation product and the content of the light component is as follows:

in the formula: m is_asphaltene、m_maltene、m_cokeAnd m_rawoilRespectively representing the quality of asphaltene, n-heptane soluble components, residual coke and raw heavy oil. Y is_m<380Represents the mass fraction of components with the distillation range of less than 380 ℃ in the n-heptane soluble component. In the experimental process, each group of experiments is carried out at least 3 times, and the experimental error is ensured to be within +/-5%. The error formula for the condensation product and the light product is shown below.

In the formula:andrespectively representing the average mass fraction of the condensation component and the light component in three experiments;andrespectively represent the average mass fraction of the grandma and the light component obtained in the ith experiment.

The analysis method comprises the following steps: the gaseous products were collected by a sample bag by differential pressure inside and outside and the components were analyzed by gas chromatography (TCD detector).

A chromatographic column: packed column, TDX-01;

temperature of the column box: 80 ℃;

the temperature of the detector is 150 ℃;

the injector temperature is 100 ℃;

detected product gas includes H₂、CO、CH₄And CO₂。

The distillation range of the n-heptane-soluble fraction was analyzed by JAS simulated distillation analysis chromatography (JAS6100, JAS, Germany).

Chromatographic working parameters:

a chromatographic column: CapillaryColumn, JASDimDis, No. 43305;

a detector: FID detector

Detector temperature: 430 ℃;

carrier gas: n is a radical of₂，20mL·min^-1；

Combustion gas: h₂，16mL·min^-1；

Combustion-supporting gas: air, 350 mL. min^-1；

The temperature of the column box is programmed temperature rise: the initial temperature is 40 ℃, and the heating rate is 13 ℃ min^-1The final temperature is 430 ℃, and the retention time is 3 min;

sample inlet temperature: 430 ℃;

sample introduction amount: 0.5. mu.L.

Using a Fourier infrared spectrometer (Vetex70, Bruker, Germany) at 4000-^-1The structure of asphaltenes in the feed and product was analyzed in the spectral range. The nature of the pyrolysis of the n-heptane soluble fraction and the structure of the pyrolysis product thereof were analyzed using a thermogravimetric infrared spectrometer (TG209F3, NETZSCH, TENSOR27, germany, Bruker, germany). Thermogravimetric analyzer at 10 ℃ min^-1The rate of (2) is increased from 30 ℃ to 800 ℃. And sampling and analyzing the pyrolysis gas at every temperature rise of 100 ℃ to obtain an infrared spectrogram. The elemental composition (C/H/N/S) of the product and the raw oil was analyzed using an elemental analyzer (Varioelcube, ELEMENT, Germany), the O ELEMENT content being obtained by the subtraction method.

Example 1

Heavy oil properties of feedstock

The reaction temperature is 350 ℃, the reaction pressure is kept at 15-22 MPa, the reaction time is 60min, the stirring speed is 900rpm, and the mass ratio of alcohol to oil is 1: 1; the yield of light components is 75 wt%, the yield of asphaltene is 21 wt%, residual coke can be almost ignored, and the mass conservation is 95%. Through detection, under the optimal condition, the content of components of the light product which is kept below 350 ℃ is 61 wt%, and the viscosity (80 ℃) is reduced to 76mPa & s; the S content of the oil product is reduced by 37 wt%.

Through infrared spectrum detection, the structural change of asphaltene in heavy oil in the reaction process is researched. Indicating that the raw material asphaltene generates certain cracking reaction under high temperature condition and generates certain amount of secondary asphaltene.

The supercritical methanol was reacted in CH 3O-form by thermogravimetric infrared detection. Supercritical methanol plays a role as both a hydrogen donor and a reaction solvent during the reaction.

The viscosity of the light oil product is greatly reduced, and the viscosity (80 ℃) of the obtained light product is reduced to 76mPa & s under the optimal reaction condition, which is reduced by 91% compared with the viscosity (80 ℃) of the raw material.

In summary, the invention discloses a heavy oil viscosity reducing and desulfurizing method based on supercritical methanol, which is characterized in that heavy oil is subjected to modification reaction in a supercritical methanol environment, the heavy oil is placed in the supercritical methanol environment for a certain time mainly through temperature and pressure control, on one hand, the dissolving capacity of the supercritical methanol for each component in the heavy oil is adjusted, so that macromolecules in the heavy oil are cracked into smaller molecules, on the other hand, the reactivity of methanol for hydrogen supply and the like is adjusted, and viscosity reduction and desulfurization of the heavy oil under the condition of inhibiting coking are realized. The method can improve the conversion rate of heavy oil viscosity-reducing reaction without a catalyst, avoid the coking phenomenon of a system and reduce the content of heteroatoms such as sulfur, nitrogen and the like.

Thus, it will be appreciated by those skilled in the art that while embodiments of the invention have been illustrated and described in detail herein, many other variations or modifications can be made which conform to the principles of the invention, as may be directly determined or derived from the disclosure herein, without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be understood and interpreted to cover all such other variations or modifications.