Extraction of aromatic hydrocarbons from a kerosene fraction

 

(57) Abstract:

The invention relates to the refining industry and can be used to remove aromatic hydrocarbons from straight-run kerosene fraction. The method consists in the allocation of aromatic hydrocarbons from a kerosene fraction liquid extraction, and as an extractant use acetone containing 15-20 wt.% water, when the mass ratio of the aqueous acetone to raw 2-6,1, as well as a second, is not miscible with the extractant solvent is n-pentane at mass ratio to raw materials 0.5 to 1: 1. The technical result - obtaining high-quality jet fuel that meets the requirements for the content of arenes and a minimum height of mecoptera flame. 3 tab., 1 Il.

The invention relates to the refining industry and can be used to remove aromatic hydrocarbons from straight-run kerosene fraction with the aim of obtaining high-quality jet fuel that meets the requirements for the content of arenes and a minimum height of mecoptera flame.

In recent years, stricter environmental requirements for jet fuels for robodragon (not more than 3 wt.%) and the minimum height of mecoptera flame 26 mm [Nasirov R. // Oil of Russia. - 1997. - N 11. - S. 38-42]. The high content of aromatic hydrocarbons in jet fuel leads to increased formation in engines and potential aircraft accidents. In addition, the combustion products increases the emission of solid particles, the content of carbon monoxide into the atmosphere.

Known methods of extraction of aromatic hydrocarbons from kerosene, gas oil fractions 3-methoxypropionitrile [Application 1431727, UK, 1976; C 10 G 21/20], N,N-dimethylimidazolidine [A. S. 941341, USSR, 1982, C 07 C 7/10], diethylmalonate or dimethylsuccinic [A. S. 432116, USSR, 1974, C 07 C 7/10, 15/00], mixtures of furfural to furfuryl alcohol [US 3546108, 1970, NCI 208/323]. The disadvantage of all these methods is the proximity of the boiling points of extractants and raw components, which complicates the regeneration of the extractants. The most common method of regeneration - rectification - cannot be used because of the formation of azeotropic mixtures with components of raw materials.

Closest to the technical essence of the present invention a method of dearomatization heavy gasoline and kerosene acetone from 1-15 wt.% water [PL 153738, 1991, 10 G 21/16]. Acetone does not form azeotropic mixtures with carbohydrate the phase rectification.

The main disadvantage of this method is the low selectivity of aqueous acetone, and therefore the concentration of arenes in the extract is just 38-50 wt. % and the yield of raffinate is low. In addition, the density of acetone (2400.7908) is close to the density of the kerosene fraction, which complicates the separation of the equilibrium phases.

To improve the selectivity and efficiency of the process of separating aromatic hydrocarbons from a kerosene fraction as extractant is proposed to use a heterogeneous mixture of solvents acetone - water - pentane. Pentane, concentrating in rafinate phase, reduces its density (the density of pentane2400.6262), which also increases the difference between the densities of the extract and raffinates phases, significantly accelerates splitting, which leads to improving the performance of the extractor.

The raw material used straight-run kerosene fraction "Kirishinefteorgsintez" next fractional composition,oC: N. K.- 140; 10% - 166; 30% - 178; 50% - 190; 70% - 201; 90% - 222; K. K. - 239.

Physico-chemical properties of raw materials:

The refractive index of nD20= 1.4417

Density240where) 41oC

Height mecoptera flame - 19 mm

The content of aromatic hydrocarbons - 23.3 wt.%

The sulfur content of 0.9 wt.%

Preliminary experiments single-stage extraction arenes from kerosene fractions at 40oC and the mass ratio of the aqueous acetone to raw materials 3:1 was the optimum water content in acetone (PL. 1).

With a water content of 10 wt. % achieved a high degree of extraction arenes, but because of the low selectivity of the solvent content of arenes in the extract is low and the output of the raffinate is only 36.6 wt.%. When the water content in acetone 30 wt. % received highly concentrated aromatic extracts, but the degree of extraction arenes insufficient to obtain a raffinate that meets environmental requirements for jet fuel. Therefore, further experiments multistage extraction was carried out at the preferred water content in acetone of 15-20 wt.%.

As follows from the results presented in table. 2, the extraction of arenes in the presence of pentane can significantly increase the concentration of arenes in the extract and raffinate with relatives other process indicators. Quite a few to increase the ratio of water a compared with the process without pentane (experiments 2 and 6, table. 2). At the same time increases the ratio of aqueous acetone to raw materials, for example from 3:1 to 6: 1 without addition of pentane (experiments 2 and 3, PL. 2), leads to a decrease in the content of arenes in the extract and increase the degree of extraction, but is accompanied by a sharp decrease in the concentration in the extract and raffinate output.

Increasing the ratio of pentane to raw materials at other invariable indicators of process (experiments 7 and 8, PL. 2) increases the concentration of arenes in the extract and to increase the yield of raffinate, i.e. more selective allocation of arenes. However, due to the competing effects of pentane greater number of arenes remains in the raffinate and the degree of extraction decreases.

Increasing the temperature of the extraction process (experiments 5 and 9, table. 2) leads to the opposite results change process: the degree of extraction arenes increases, a smaller number of them remains in the raffinate, but the rest of the results deteriorate, due to the decrease in the selectivity of the solvents.

Schematic diagram of extraction arenes from a kerosene fraction aqueous acetone shown in the drawing.

Regeneration of pentane and acetone from the raffinate and extract phases of production is oratore 7 and is used as extragent a small amount of acetone, remaining in the raffinate. Using this proposed scheme is a vicious cycle and excludes energy used for the evaporation of water contained in aqueous acetone.

Characteristics of the raffinate obtained a five-stage counter-current extraction arenes from straight-run kerosene fraction aqueous acetone with pentane (experiment 5, table. 2), are presented in table. 3.

The resulting raffinate meets the requirements for jet fuel TC-1 highest grade. Height mecoptera flame for the raffinate is much higher than that required for fuel TC-1 and Jet a-1. Extraction purification was subjected dehydroacetate faction, but even in sulfur content of the raffinate meets the requirements for jet fuel. The degree of extraction of organic sulfur compounds - 88.3 wt.%, i.e. higher than arenes.

Received vysokoavtomatizirovannyh extract after Hydrotreating can be used for the production of valuable aromatic petroleum solvents such Nefras AR-120/200, oil Solvent (TU 38001196-79), Solvesso 100, Solvesso 150, and technical detergents, synthetic aromatic lubricating oils, etc.

Example 1 (experiment 5, table. 2)

In the lower part of the Packed extraction the share (consumption of 100 g/h) and pentane (50 g/h), and in the upper part of the aqueous acetone (flow rate of 300 g/h), containing 80 wt.% acetone and 20 wt.% water. In the countercurrent extraction after stable mode simultaneously selected raffinate and extract phase in the number 192 and 258 g/h, respectively. Of 258 g of the extract phase to a distillation column efficiency 20 theoretical plates 10 g distilled pentane and 179 g of acetone. VAT residue is cooled to 10oC, in a separating funnel to separate the lower layer 57 g of water and obtain 12.0 g of extract containing 98.1 wt.% aromatic hydrocarbons. The extract yield 12 wt.% for raw materials.

From 192 g rafinate phase to a distillation column efficiency 20 theoretical plates 40 g distilled pentane and 60 g of acetone. VAT residue is cooled to 10oC and extracted the remaining therein a small amount of acetone (1.0 g) 57 g of water, separated from the extract phase. The output of the upper layer of the raffinate 88 g, or 88 wt.% for raw materials. The content of aromatic hydrocarbons in the raffinate 13.1 wt.%. The output of the lower water layer 61 g, the content of acetone - 1.64 wt.%.

Example 2 (experiment 2, table. 2)

In the lower part of the Packed extraction columns efficiency 5 theoretical stages is served at temperaturerise 80 wt.% acetone and 20 wt.% water. In the countercurrent extraction after stable mode simultaneously selected raffinate and extract phase from which the method is similar to that described in experiment 1, after distillation distillation of the acetone from the extract phase and separation of water-hydrocarbon heterogeneous mixture allocate 22.4 g of extract containing 61.5 wt. % aromatic hydrocarbons. From rafinate phase rectification remove most of the acetone, the remaining impurities acetone (about 0.8 g) extravert water and receive 77.5 g of raffinate containing 12.2 wt.% aromatic hydrocarbons.

Experiments 1 and 3 (without the use of pentane) was carried out according to the method described in example 2.

Experiments 4, 6-9 were carried out according to the method described in example 1.

Extraction of aromatic hydrocarbons from a kerosene fraction aqueous acetone, characterized in that the use of acetone containing 15 - 20 wt. % of water at a mass ratio of aqueous acetone to the raw material 2 - 6 : 1, with simultaneous feed to the extraction column second, immiscible with the aqueous acetone solvent is n-pentane at mass ratio to raw materials 0.5 to 1 : 1.

 

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