RU2359993C1 - Method of receiving of aromatic oil - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: invention relates to oil processing field, particularly to processing of oil vacuum fractions. Method of aromatic oil receiving includes double-stage raw materials selective treatment- oil fractions- dissolvent with receiving of extract of the first and the second stages, solvent solution of the first stage and raffinate of the second stage and usage of solvent solution of the first stage in the capacity of raw materials for the second stage of selective treatment, extract of the second stage is additionally subject to dewaxing in solvent and contact afterpurification by adsorbent with receiving of desired product- aromatic oil, and solvent solution of the second stage is subject to additional separation in decanter with separation of light and hard phase with usage of additional cooling or water feeding, with following return of hard solvent phase of the second stage in raw materials of the first stage, and light solvent phase of the second stage is used for receiving of base lubricating oil with viscosity index not lower the 95.

EFFECT: method provides receiving of aromatic oil with improved ecological characteristics (content of "ПЦА" not higher 3,0% and carcinogenic compound less 15 mg/kg) and simultaneously basic lubricating oils of high quality and provides increasing of base product yield approximately for 3 wt %, as compared with famous technology.

3 cl, 4 tbl, 2 dwg

Description

The invention relates to the field of oil refining, in particular to the processing of oil vacuum fractions, and can be used for the production of aromatic oils with improved environmental characteristics and at the same time high-quality base lubricating oils.

Aromatic oils belong to the group of process oils and have a wide range of applications, for example, as a filler in the production of a variety of products from natural and synthetic rubbers, in particular as softeners in the manufacture of tires and rubber products, as a plasticizer for thermoplastic polymers, printing ink solvent, as a softener for regenerated asphalt, etc.

Aromatic hydrocarbons in the composition of aromatic oils are necessary, as you know, for good compatibility in the composition of the filler with rubber and positively affect the service life of tires. In connection with stricter environmental requirements, modern aromatic oils should have improved environmental characteristics: the content of polycyclic aromatic hydrocarbons is not more than 3.0 wt%, the content of carcinogenic compounds (benzo (α) pyrene and its homologs) in the amount of not more than 15 mg / kg. Moreover, the requirement for the total content of aromatic hydrocarbons is not less than 30% of the mass. it is defined as interrelated quantities with a norm to the content of polycyclic aromatic hydrocarbons "not more than 3.0% by mass."

A known method of producing technological oils, which are used as fillers for the production of products from natural and synthetic rubbers and satisfying the following requirements: the content of polycyclic aromatic hydrocarbons is not more than 3% by mass., Aromatic hydrocarbons is not less than 18% by mass, polar compounds 11-25% by mass ., kinematic viscosity 10-70 mm ² / s at 100 ° С, flash point 210 ° С and higher.

The invention is known (US patent No. 6399697, 04/04/2002), in which the raw material for the production of process oil is a mixture of residual and distillate base oils containing polycyclic aromatic hydrocarbons 3-20% wt., Aromatic hydrocarbons 15-40% wt., polar compounds 5-30% of the mass., asphaltenes 2% of the mass. and less, with a kinematic viscosity of 10-100 mm ² / s (at 100 ° C), 5% vol. fractions of which are distilled at a temperature of 370 ° C and above.

The first component - residual oil - contains asphaltenes from 0.1 to 2 wt.%, Polycyclic aromatic hydrocarbons not more than 20 wt.%, Aromatic hydrocarbons not less than 20 wt.%, 5% vol. fractions are distilled at a temperature of 370 ° C and above.

The second component, a lubricating base oil, is characterized by a content of polycyclic aromatic hydrocarbons of not more than 10 wt%, aromatic hydrocarbons of not less than 5 wt%, 5% vol. fractions are distilled at a temperature of 370-530 ° C.

Mixed raw materials include residual oil in an amount of 20-90% vol. (40-80% vol.) And distillate lubricating base oil - 10-80% vol. (60-80% vol.).

For the extraction of oils, a polar solvent is used: furfural, phenol, N-methylpyrrolidone (preferably furfural). The volume ratio of solvent: oil is 0.5-2.5 (1.0-2.0), the top temperature of the extraction column is 60-115 ° C (70-110 ° C), the bottom temperature of the column is 45-80 ° C (50- 70 ° C). In this process, undesired polycyclic aromatic hydrocarbons, together with other harmful impurities, such as asphaltenes, are removed from the bottom of the extractor. Technological oil containing polycyclic aromatic hydrocarbons of not more than 3% of the mass is obtained from the raffinate fraction.

The disadvantage of this method is the complexity of the technological scheme, including separate preparation of each component and quality control. Constant regulation of the composition and quality control of mixed raw materials allows extraction in one step, but additional distillation, dewaxing and selective post-treatment are necessary to obtain high-quality process oil. In addition, the process oil is obtained from raffinate (thereby reducing the production of base oils), and the entire extract enriched with polycyclic aromatic hydrocarbons is removed from the process as a by-product of an unskilled product. The economic efficiency of such a process is not obvious.

Closest to the invention (US Patent No. 6,029,060, 10/12/2004) is a method for producing process oil, including aromatic oil, in the process of selective purification of petroleum distillate in two stages, which includes: contacting the feed with a polar solvent in an extraction column of the first stage ( bottom temperature 30-80 ° C); withdrawal of the raffinate of the first stage; contact of the raffinate of the first stage with a polar solvent in the extraction column of the second stage. In an intermediate distillation column, 70-100% (preferably 95-100%) of the polar solvent is removed from the first stage raffinate from the first stage of extraction. Moreover, in the extractor of the second stage, the bottom temperature is higher (60-90 ° C) than the temperature of the bottom of the extractor of the first stage. After removal and regeneration of the solvent, an extract of the second stage containing aromatic hydrocarbons of at least 20% of the mass leaves the extraction column of the second stage. and polycyclic aromatic hydrocarbons of not more than 3 wt. -%, which is the target product.

Extraction columns can have different hardware design, however, it is desirable to have the same apparatus for both stages.

The ratio of raw materials: solvent depends on the fractional composition of the raw materials, the properties of the original oil and is at the first stage 70-300% vol. (120-170% vol.) And in the second stage from 100 to 400% vol. (200-250% vol.).

For the first and second extraction stages, polar solvents are used: furfural, phenol and N-methylpyrrolidone (preferably furfural).

The resulting process oils, including aromatic oils, are used as solvents, anti-dust coatings, plasticizers and / or fillers for synthetic and natural rubbers, and printing ink solvents.

The main disadvantage of this method is the lack of requirements for the content of carcinogenic aromatic compounds in the process oil, in this regard, the proposed technology cannot guarantee the necessary environmental properties of the product: the content of benzo (α) pyrene and its homologues in the amount of not more than 15 mg / kg.

The objective of the present invention is to develop a method for producing aromatic oils with improved environmental characteristics with a total aromatic hydrocarbon content of not less than 30 wt.%, Polycyclic aromatic hydrocarbons not more than 3.0 wt.%, Carcinogenic compounds (benzo (α) pyrene and its homologs) in the amount of not more than 15 mg / kg.

The problem is solved by the developed method for producing aromatic oil, which includes a two-stage selective purification of raw materials - oil fractions with a polar solvent to obtain extracts of the first and second stages and raffinate of the second stage. The method is characterized in that the second-stage extract is additionally subjected to dewaxing and post-treatment with an adsorbent to obtain the target product, and the second-stage raffinate solution is subjected to additional separation in a decanter with separation of light and heavy phases using additional cooling or water supply, followed by the return of the heavy raffinate phase the second stage in the raw materials of the first stage, and the light phase of the raffinate of the second stage is used to obtain a base lubricating oil with a viscosity index not lower than 95.

Moreover, the dewaxing of the extract of the second stage is carried out at low crystallization rates (not higher than 20 ° C per hour) under conditions of a small degree of supersaturation of the suspension (5-7 ° C), and the spent contact aftertreatment adsorbent is subjected to full or partial regeneration in a continuous mixing apparatus.

The raw materials used are petroleum fractions boiling at temperatures above 400 ° C.

The second stage extract is a concentrate of aromatic hydrocarbons. Subsequent dewaxing of the extract of the second stage with additional contact aftertreatment ensures the production of aromatic oils with improved environmental characteristics, containing not more than 2.9% of the mass. polycyclic aromatic hydrocarbons, carcinogenic compounds (benzo (α) pyrene and its homologs) in the amount of not more than 15 mg / kg and the total content of aromatic hydrocarbons is not less than 30% of the mass.

The raffinate of the second stage of selective cleaning is processed in a known manner: by dewaxing and subsequent hydrorefining to obtain a base lubricating oil with a viscosity index of at least 95.

The heaviest aromatic hydrocarbons are removed from the feed with an extract of the first stage, which, after isolation of the solvent, is sent, for example, to the production of fuels.

The extract of the second stage containing aromatic hydrocarbons from 30% of the mass. and above, polycyclic aromatic hydrocarbons no more than 2.9% by weight, carcinogenic compounds (benzo (α) pyrene and its homologs) in the amount of up to 50 mg / kg, after dewaxing to a pour point below 0 ° C, deep contact post-treatment is performed adsorbent to remove benzo (α) pyrene and its homologs to a total content of not more than 15 mg / kg and to stabilize the quality of the resulting aromatic oil.

As a polar solvent in the first stage and second stage of the selective purification of vacuum distillate, it is better to use N-methylpyrrolidone, which has advantages (Kolesnik I.O., J. "World of Petroleum Products)), 2003, No. 2, p.4) before phenol and furfural (table 1):

- the optimal combination of selectivity and solvent capacity, especially polycyclic aromatic hydrocarbons;

- less toxic (by several orders of magnitude) and the most environmentally friendly solvent currently known;

- pour point is much lower than that of phenol;

- thermo-oxidizing ability is much higher than that of furfural, which removes a number of problems associated with the oxidation and decomposition of the solvent, as well as coking of heat exchange equipment;

- the mode of regeneration of the solvent is milder than when using phenol.

For a better understanding of the invention, figure 1 presents a block diagram of the claimed method, which shows the following blocks (Arabic numerals) and the flows of raw materials, intermediate and final products (Roman numerals):

1 - the first stage of selective cleaning;

2 - the second stage of selective cleaning;

3 - selective dewaxing;

4 - adsorption treatment;

5 - regeneration of the adsorbent.

I - raw materials;

II - raffinate solution of the first stage;

III - extract of the first stage;

IV - raffinate of the second stage;

V - extract of the second stage;

VI - dewaxed extract of the second stage;

VII - gach;

VIII - aromatic filler oil;

IX - adsorbent for regeneration;

X is a fresh adsorbent;

XI - regenerated adsorbent;

XII - adsorbent regeneration products

The raw material enters the first stage (1) of selective purification in an extraction column, from the top of which a raffinate solution of the first stage is discharged through line II, which is sent to the second stage (2) of selective purification, from the bottom of the extraction column of the first stage in line III after solvent recovery first-stage extract containing a concentrate of polycyclic aromatic hydrocarbons and other impurities.

In the second stage of selective purification (2) from the bottom of the extraction column through line V, the extract of the second stage after solvent regeneration is fed to dewaxing (3). After dewaxing, the temperature of the extract decreases to 0 ° C and lower due to the removal of solid hydrocarbons. The dewaxed extract of the second stage is sent along line VI to contact post-treatment (4). In addition, a solid hydrocarbon concentrate is discharged from the dewaxing unit (3) through line VII.

To improve the crystalline structure of paraffin, which reduces the frequency of washing of vacuum filters and increases the filtration rate of the suspension, dewaxing of the extract of the second stage of selective purification is carried out at low crystallization rates (not higher than 20 ° C per hour) under conditions of a small degree of supersaturation of the suspension (5-7 ° C )

With deep contact post-treatment (4) on the adsorbent, carcinogenic compounds (benzo (α) pyrene and its homologs) are removed from the extract to a total content of not more than 15 mg / kg while stabilizing the quality of the obtained aromatic oil, the target product of this process.

The spent adsorbent from the contact aftertreatment unit (4) is discharged via line IX to the continuous adsorbent regeneration unit (5), from which the regenerated adsorbent is returned to the process via line XI. In addition, fresh adsorbent partially enters this block (5) along the X line.

Figure 2 shows a diagram of the additional separation of the raffinate of the second stage, which shows the following blocks (Arabic numerals) and the flow of raw materials and products (Roman numerals):

1 - the first stage of selective cleaning;

2 - the second stage of selective cleaning;

6 - refrigerator;

7 - decanter.

I - raw materials;

II - raffinate solution of the first stage;

III - extract of the first stage (after regeneration of the solvent);

IV - raffinate solution of the second stage;

V - extract of the second stage (after regeneration of the solvent);

XIII - the light part of the raffinate of the second stage (after regeneration of the solvent);

XIV - heavy raffinate phase of the second stage.

The raffinate solution of the first stage (II) passes through an extraction column of the second stage (2) of selective purification and is sent from the upper part of the extraction column through line IV to additional separation by additional cooling in the refrigerator (6) or by supplying water and separation in a decanter (7). The heavy phase of the second stage raffinate solution is discharged along line XIV from the bottom of the decanter (7) and returns to the feed in front of the extraction column (1), which makes it possible to increase by 3% by weight. yield of aromatic oil with improved environmental characteristics. The light phase of the second stage raffinate solution after regeneration of the solvent through line XIII is sent to the production of base lubricating oil with a viscosity index of at least 95.

The decanter is a vertical or horizontal apparatus equipped with a wettable product with a metal mesh or a synthetic wettable bag designed to improve the conditions for the separation of the raffinate solution of stage II into light and heavy phases. The decanter undergoes the process of kaoliscence of dispersed droplets and sedimentation of the heavy phase.

Table 2 shows examples of process conditions for the production of aromatic oils with improved environmental characteristics, containing aromatic hydrocarbons> 30 wt.%, Polycyclic aromatic hydrocarbons <2.9 wt. and carcinogenic compounds (benzo (a) pyrene and its homologs) in the amount of not more than 15 mg / kg.

The yield of aromatic oil with improved environmental characteristics depends on the hydrocarbon composition and the quality of the initial oil fractions.

Examples of key quality indicators for sample 1 and sample 2 of aromatic oil are shown in table 3.

Various variations of these examples are possible if they do not distort the essence of the present invention.

Examples of conditions for the production processes and quality indicators of samples of the base lubricating oil obtained from stage II raffinate are shown in table 4.

table 2
Environmental process conditions for aromatic oils with improved environmental properties Indicators Aromatic oil Sample 1 Sample 2 Selective purification with N-methylpyrrolidone I stage Solvent: Raw Material Mass Ratio 1.3: 1.0 1.0: 1.0 The temperature in the extractor, ° C top 65 60 bottom 55 fifty II stage Solvent: Raw Material Mass Ratio 1.3: 1.0 1.2: 1.0 The temperature in the extractor, ° C top 85 80 bottom 70 70 Selective dewaxing The composition of the solvent,% vol .: - methyl ethyl ketone fifty - toluene fifty The mass ratio of solvent: raw materials, including 3: 1 3: 1 - for dilution 2: 1 2: 1 - for flushing 1: 1 1: 1 Filtration Temperature, ° С Minus 15 Minus 25 The cooling rate, ° C / hour twenty twenty Contact cleaning Adsorbent Süd-Chemic AG bleaching earth Processing temperature, ° С 80-90 80-90 The amount of adsorbent,% mass. 5 5 Contact time, min thirty thirty

Table 3
Examples of quality indicators of aromatic oil samples with improved environmental performance No. p / p Indicators Valid Values Prototype Test methods one 2 one. Density at 15 ° С, kg / m ³ 950-970 940.1 945.2 GOST 3900 or ASTM D 4052 2. Refractive index at 20 ° C 1.5150-1.5250 1,5183 1,5230 GOST 18995.2 or ASTM D 1218 3. Kinematic viscosity at 100 ° С, mm ² / s 18-22 18.1 20.5 GOST 33 or ASTM D 445 four. Viscous-weight constant 0.900 ± 0.040 0.8746 0.8790 ASTM D 2140 5. Pour point, ° C No higher than 0 Minus 10 Minus 16 GOST 20287 or ASTM D 97 6 Flash point determined in a closed crucible, ° С Not less
220 225 225 GOST 6356 or ASTM D 93 7. Mass fraction of sulfur,% No more than 3.0 1,1 1,1 GOST 1437 8. Aniline point, ° С 60-75 78 74 GOST 12329 9. The content of aromatic hydrocarbons,% wt. thirty 65 75 ASTM D 2007 10. The content of polycyclic aromatic hydrocarbons,% wt. No more than 2,9 2.2 2.9 IP 346 eleven. The content of carcinogenic hydrocarbons benzo (α) pyrene and its homologues in total, mg / kg No more than 15 10.5 12,4 ^one) Note. ¹⁾ Guidance document on the control of air pollution PD 52.04.) 186-89 (GOST).

Table 4 Examples of conditions for the production processes and quality indicators of samples of the base lubricating oil obtained from stage II raffinate The name of indicators Sample 1 Sample 2 Selective Cleaning * Stage II raffinate characterization Kinematic viscosity at 100 ° С, mm ² / s 10.5 10.8 Pour point, ° C 48 49 Density at 20 ° С, kg / m ³ 878 879 Refractive Index at 50 ° C 1.4770 1.4790 Selective dewaxing Conditions: The composition of the solvent,% vol. - methyl ethyl ketone fifty fifty - toluene fifty fifty Solvent: Raw Material Mass Ratio 5.5: 1 5.5: 1 including:
- for dilution 4.0: 1 4.0: 1 - for flushing 1.5: 1 1.5: 1 Filtration Temperature, ° С minus 25 minus 25 Characteristics of dewaxed oils Kinematic viscosity at 100 ° С, mm ² / s 12,4 12.8 Pour point, ° C minus 16 minus 16 Hydrotreating Conditions: The partial pressure of hydrogen in the reactor, 4.0 4.0 MPa The temperature in the reaction zone, ° C 280 290 Volumetric feed rate, h ^-1 1,5 1,5 Base Oil Characterization Kinematic viscosity at 100 ° С, mm ² / s 11.9 12.3 Viscosity index 95 95 Refractive index at 20 ° C 1.4850 1.4855 Pour point, ° C minus 15 minus 15 Sulfur content,% wt. 0.2 0.22 * The conditions for the selective cleaning process are given in table.2 upon receipt of samples 1 and 2 of aromatic oil.

Claims (3)

1. The method of producing aromatic oil by two-stage selective purification of raw materials - oil fractions - with a solvent to obtain an extract of the first and second stages, a raffinate solution of the first stage and a raffinate of the second stage using a raffinate solution of the first stage as a raw material for the second stage of selective cleaning, characterized in that the extract of the second stage is additionally subjected to dewaxing in a solvent and contact post-treatment with an adsorbent to obtain the target product - aromatic oil, the second-stage raffinate solution is subjected to additional separation in a decanter with separation of the light and heavy phases using additional cooling or water supply, followed by the return of the second-stage heavy raffinate phase to the first-stage raw materials, and the second-stage light raffinate phase is used to obtain a base lubricating oil with an index viscosity not lower than 95. 2. The method according to claim 1, characterized in that the dewaxing of the extract of the second stage is carried out at low crystallization rates (not higher than 20 ° C per hour) under conditions of a low degree of supersaturation (5-7 ° C). 3. The method according to claim 1, characterized in that the spent adsorbent contact tertiary treatment is subjected to continuous regeneration by thermal means.

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