RU2185416C1 - Method of simultaneous production of environmentally safe diesel fuel and aromatic solvent - Google Patents

Abstract

FIELD: petroleum processing and petrochemistry. SUBSTANCE: invention can be used for simultaneous production, from hydrofined diesel fraction, of (i) environmentally safe diesel fuel satisfying requirements for content of aromatic hydrocarbons and (ii) aromatic solvents containing at least 98 wt.% aromatic hydrocarbons. Method consists in extracting aromatic hydrocarbons from hydrofined diesel fraction with two solvents: one polar and the other nonpolar (pentane), the former being dimethylformamide or dimethylacetamide containing 3-5 wt.% of water and ratio of the former and the latter to raw material being, respectively, (3-5):1 and (1-1.5):1. Extract is concentrated to 98-99 wt.% in solvent-regeneration column using azeotropic rectification of extract phase with polar solvent present in extract phase. EFFECT: improved quality of products. 1 dwg, 2 tbl, 4 ex

Description

 The invention relates to the refining industry and can be used for the simultaneous production of environmentally friendly diesel fuel from a hydrotreated diesel fraction that meets the requirements for the content of aromatic hydrocarbons and aromatic solvents such as Nefras AR and Solvent Oil with an aromatic hydrocarbon content of at least 98 wt. %

 As a result of the hydrotreatment process of straight-run diesel fractions, the sulfur content decreases to 0.05-0.2 wt.%, But aromatic hydrocarbons are practically not hydrogenated, their concentration in the hydrotreated diesel fraction remains at the level of 25-35 wt.%. At the same time, the content of aromatic hydrocarbons in the diesel summer environmentally friendly fuel DLEC-V should not exceed 20 wt.% [Chulkov PV, Chulkov IP Fuel and lubricants. M .: Polytechnic, 1996. - 304 p.], Abroad, these restrictions are even more stringent - up to 10% by weight. [Oil and gas technology. 1995. - N2. - S. 52].

 For the extraction of arenas from middle distillate oil fractions, in particular from diesel fractions, methods are proposed using various extractants: furfural, imidazoline derivatives, N, N-dimethylimidazolidone, β-methoxypropionitrile, etc. [Krasnogorskaya N.N. and other Extraction of medium oil fractions. - M .: Chemistry, 1989. -72 p.]. The main disadvantage of all the proposed methods is the lack of selectivity of the extractants used for aromatic hydrocarbons and, as a result, the relatively low concentration of aromatic hydrocarbons in the extract and the low yield of raffinate - environmentally friendly diesel fuel.

 The closest in technical essence and the achieved effect to the proposed invention is a method of producing environmentally friendly diesel fuel by extraction of aromatic hydrocarbons with a heterogeneous mixture of solvents acetonitrile - pentane - water [RF patent 2148070, C 10 G 21/14, 21/20, 1999. BI 12 , 2000].

 The disadvantage of this method is the inability to simultaneously obtain raffinates that meet the requirements for environmentally friendly diesel fuel with an aromatic hydrocarbon content of not more than 10 wt.%, And extracts with an aromatic hydrocarbon content of at least 98 wt.% That satisfy the requirements for aromatic solvents such as Nefras AR, Solvent Petroleum, Solvesso, etc.

 In order to simultaneously produce environmentally friendly diesel fuel and an aromatic solvent, it is proposed to use more selective solvents — dimethylformamide or dimethylacetamide — instead of acetonitrile and use their ability to form azeotropic mixtures with saturated hydrocarbons of the extract to concentrate aromatic hydrocarbons in the extract by distillation of saturated hydrocarbons from the extract phase in the form of triple azeotropes saturated hydrocarbon - water - amide.

 Thus, the proposed method provides for a combined process of extraction and azeotropic distillation during the regeneration of the extractant from the extract phase.

 The drawing shows a diagram for the simultaneous production of environmentally friendly diesel fuel and aromatic solvents. Raw materials - hydrotreated diesel fraction and non-polar solvent (pentane) enter the lower part of the extraction column (1), to the upper part of which an aqueous polar solvent (dimethylformamide or dimethylacetamide containing 3-5 wt.%, Water) is fed. The raffinate phase enters the distillation column (2), where pentane is distilled off, then to the vacuum column (3) to distill off the main part of the polar solvent. Raffinate - the bottom product of the column (3) is washed with water in (4) and is used as a component of diesel fuel.

The extract phase enters the column (5), where pentane is distilled off, then to the column (6), where a fraction of up to 100 ^o С is separated - an azeotropic mixture of saturated hydrocarbons of the extract, a polar solvent (dimethylformamide or dimethylacetamide) and water, then to the column (7) where a pure polar solvent (amide) is distilled off and returned to the extractor (1). The bottom product of the column (7) after washing with water in the column (8) can be used as a petroleum aromatic solvent. The washing water from the columns (4) and (8) enters the column (9), where it is separated from the polar solvent and returned to the cycle.

In the table. 1 shows the conditions for a five-stage countercurrent extraction of aromatic hydrocarbons from a hydrotreated diesel fraction with the following physicochemical parameters:
boiling range - 222-375 ^o C
refractive index - n _D ²⁰ = 1.4684
density - ρ $\genfrac{}{}{0ex}{}{\text{20}}{\text{4}}$ = 0.836
aromatic hydrocarbon content - 24.8 wt.%
As follows from the data presented in table 2, the proposed method can simultaneously produce both environmentally friendly diesel fuel that meets the requirements for the content of aromatic hydrocarbons, and an aromatic concentrate containing 98-99 wt.% Aromatic hydrocarbons, which meets the most stringent requirements to petroleum aromatic solvents.

 The resulting raffinates contain from 9.9 to 12.8 wt.% Aromatic hydrocarbons and meet the requirements for environmentally friendly diesel fuel DLEC-V (no more than 20 wt.% Aromatic hydrocarbons according to TU 38.1011348-90, amendment 1), and the raffinate from experiment 1 corresponds to promising environmental requirements (not more than 10% by weight of aromatic hydrocarbons).

 According to the prototype, it is also possible to obtain environmentally friendly diesel fuel, however, the extracts obtained with this cannot be used as aromatic petroleum solvents such as Nefras AR 150/330, since the concentration of aromatic hydrocarbons in the extracts is only 78.5-94.9 wt. %, which is significantly lower than the required 98-99 wt.% (see materials of the prototype: RF patent 2148070, table. 2).

 A comparison of the results of experiment 2 of this application and experiment 7 of the prototype, carried out with the same ratio of polar extractant: raw materials 3: 1 and pentane: raw materials 1: 1, confirms the great effectiveness of the claimed method: the content of aromatic hydrocarbons in the raffinate and extract 12.8 and 98.4 wt.% Against 14.5 and 78.5 wt.% According to the prototype.

 The yield of raffinate according to the prototype is also significantly lower than by the proposed method: for example, when the concentration of aromatic hydrocarbons in the raffinate is 9.6 and 9.8 wt. The yield of raffinate is only 79.5 and 77.2%, respectively, while according to the proposed method with a close concentration of aromatic hydrocarbons in the raffinate of 9.9 wt.%, its yield on raw materials is 83%, which is 3.5 and 5.8% higher than in the prototype.

 Example 1

At the temperature of 30 ^{° C., a} hydrotreated diesel fraction (flow rate of 100 g / h) and pentane (100 g / h) are fed to the lower part of the packed extraction column with an efficiency of 5 theoretical stages, and dimethylacetamide with 5 wt.% Water (flow rate 400) is fed to the upper part g / h). As a result of countercurrent extraction, after reaching a stable regime, the raffinate and extract phases are simultaneously selected (189 and 411 g, respectively).

 Pentane (76.7 g), then dimethylacetamide (30.2 g, including 1.5 g of water) was distilled off from the raffinate phase on a distillation column with an efficiency of 20 theoretical plates as the overhead. The bottom residue of the column is raffinate (82.1 g, including 8.1 g of aromatic hydrocarbons, 9.9 wt.%).

 Pentane (23.3 g), an azeotropic mixture of dimethylacetamide (6.5 g) + saturated extract hydrocarbons (0.9 g) + water (18.5 g), pure dimethylacetamide (344.8 g) are successively distilled off from the extract phase in a distillation column (20 tt). The bottom residue (16.97 g) contains 98% sulfonated and can be used as aromatic petroleum solvent Nefras AR 150-330.

 Example 2

At the temperature of 30 ^° C, a hydrotreated diesel fraction (flow rate of 100 g / h) and pentane (100 g / h) are supplied to the lower part of the packed extraction column with an efficiency of 5 theoretical stages, and dimethylacetamide with 5 wt.% Water (flow rate 300) is fed to the upper part g / h). As a result of countercurrent extraction, after reaching a stable regime, the raffinate and extract phases are simultaneously selected (175 and 325 g, respectively).

 Pentane (80.6 g), then dimethylacetamide (8.4 g, including 1.0 g of water) was distilled off from the raffinate phase on a distillation column with an efficiency of 20 theoretical plates as the overhead. The bottom residue of the column is raffinate (85.5 g, including 11 g of aromatic hydrocarbons 12.85 wt.%).

 Pentane (19.4 g), an azeotropic mixture of dimethylacetamide (5.6 g) + saturated extract hydrocarbons (0.47 g) + water (14.0 g), pure dimethylacetamide (271.4 g) are successively distilled from the extract phase in a distillation column (20 tt). The bottom residue (14.03 g) contains 98.4% sulfonated and can be used as aromatic petroleum solvent Nefras AR 150-330.

 Example 3

At the temperature of 30 ^{° C., a} hydrotreated diesel fraction (flow rate of 100 g / h) and pentane (150 g / h) are fed into the lower part of the packed extraction column with an efficiency of 5 theoretical stages, and dimethylacetamide with 5 wt.% Water (flow rate 500) is fed to the upper part g / h). As a result of countercurrent extraction, after reaching a stable regime, the raffinate and extract phases are simultaneously selected (234.8 and 515.2 g, respectively).

 Pentane (125.6 g), then dimethylacetamide (25.9 g, including 1.3 g of water) is distilled off from the raffinate phase on a distillation column with an efficiency of 20 theoretical plates. The bottom residue of the column is raffinate (83.3 g, including 8.9 g of aromatic hydrocarbons - 10.7 wt.%).

 Pentane (24.4 g), an azeotropic mixture of dimethylacetamide (6.0 g) + saturated extract hydrocarbons (0.65 g) + water (23.7 g), pure dimethylacetamide (444.4 g) are successively distilled from the extract phase in a distillation column (20 tt). The bottom residue (16.05 g) contains 99% sulfonated and can be used as aromatic petroleum solvent Nefras AR 150-330.

 Example 4

At the temperature of 30 ^° C, a hydrotreated diesel fraction (flow rate of 100 g / h) and pentane (100 g / h) are supplied to the lower part of the packed extraction column with an efficiency of 5 theoretical stages, and dimethylformamide with 3 wt.% Water (flow rate 400) to the upper part g / h). As a result of countercurrent extraction, after reaching a stable regime, the raffinate and extract phases are simultaneously selected (162.8 and 437.2 g, respectively).

 Pentane (69.3 g), then dimethylformamide (11 g, including 0.3 g of water) is distilled off from the raffinate phase on a distillation column with an efficiency of 20 theoretical plates as the overhead of pentane (69.3 g). The bottom residue of the column is raffinate (82.5 g, including 8.25 g of aromatic hydrocarbons - 10.0 wt.%).

 Pentane (30.7 g), an azeotropic mixture of dimethylformamide (8.0 g) + saturated extract hydrocarbons (0.85 g) + water (23.7 g), pure dimethylformamide (381 g) are successively distilled off from the extract phase on a distillation column (20 tt). The bottom residue (16.9 g) contains 98% sulfonated and can be used as aromatic petroleum solvent Nefras AR 150-330.

Claims (1)

 A method for the simultaneous production of environmentally friendly diesel fuel and aromatic solvent Nefras AR-150/330 by liquid extraction of a hydrotreated diesel fraction with two solvents - polar and non-polar (pentane), characterized in that dimethylformamide or dimethylacetamide containing 3-5 wt. . % water, with a mass ratio of 3-5: 1 to raw materials, pentane to raw materials ratio of 1-1.5: 1, and arenas in the extract are concentrated in the solvent regeneration column by azeotropic distillation of the extract phase with the polar solvent present in the extract phase.

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