RU2762728C1 - Method for producing a depressor additive to middle-distillate commercial grade fuels - Google Patents

Abstract

FIELD: petroleum industry.

SUBSTANCE: invention relates to the field of petroleum refining and petrochemistry, in particular, to a method for producing a depressor additive to fuels. The method for producing a depressor additive to diesel fuel and low-viscosity marine fuel includes the following stages: the light part from low molecular weight polyethylene of high-pressure polyethylene production is extracted using low-boiling individual hydrocarbons or hydrocarbon fractions with a boiling point in the temperature range of 25 to 100°C, followed by steam stripping of the extractant and mixing the resulting product of the extraction process with the hydrotreated diesel fuel in a ratio of 20:80 wt.% to produce a commercial grade form of a depressor additive to diesel and low-viscosity marine fuel.

EFFECT: production of a depressor additive exhibiting high depressor properties, providing the requirements for the indicator of the filtering capacity coefficient.

1 cl, 10 tbl

Description

The invention relates to the field of oil refining and petrochemistry, in particular, to the production of mid-distillate commercial fuels (diesel and low-viscosity marine fuels) intended for use in engines of cars, sea and river vessels.

It is known that to ensure the required low-temperature properties of diesel and marine fuels in terms of "pour point" and "limiting temperature of filterability", depressant and depressor-dispersant additives are introduced into them [R.A. Depressor additives for oils, fuels and oils. - M .: Chemistry, 1990,].

As a depressant and depressant-dispersant additives, various high-molecular compounds are used, mainly copolymers of ethylene with vinyl acetate [A.A. Gureev, S.R. Lebedev N.A. Kuzmina, A.V. Nazarov Improvement of low-temperature properties of diesel fuels. Thematic review, TsNIITEneftekhim, 1980, p. 35-44]. Despite the high efficiency of depressant and depressant-dispersant additives based on ethylene-vinyl acetate copolymers, they have a high cost and complex production technology using synthesis proceeding at high pressures up to 30 MPa. As a result, it is of great practical interest to develop methods for producing depressant and depressant-dispersant additives using polymers of a different nature and simpler and more cost-effective methods of their production.

An analogue of the invention under consideration is a depressant additive for diesel fuels "Sandal-1B" [Danilov A.M., The use of additives in fuels: a reference book. - 3rd ed., Add. - SPb .: Khimizdat, 2010 - P. 225], obtained on the basis of low molecular weight polyethylene (hereinafter LMPE) or a copolymer of ethylene with vinyl acetate in the presence of a hydrocarbon solvent (aromatic compounds). However, at present, this additive does not find application due to the negative effect on such an indicator of the quality of diesel fuels as the "filterability coefficient" (hereinafter CF) according to GOST 19006-73 (the norm is not more than 3.0) and low efficiency of action on such a quality indicator diesel fuels as the "limiting filterability temperature" (hereinafter PTF). In addition, the fuel is unstable during storage; some of the heavy structures of NMPE fall out during storage.

In addition, analogs of the present invention include a method for producing a bifunctional diesel fuel additive that improves depressant and lubricating properties, based on 10-30% of the mass. NMPE and distillation residue of butyl alcohols (the rest) [RF Patent 2568263 copyright holder FGBOU VO "UGNTU", authors Zinatullina GM, Baulin OA, Rakhimov MN Published: 20.11.2015 Bul. No. 32]. However, along with good depressant properties, the additive obtained by this method can be characterized by such a negative quality as high corrosiveness and hygroscopicity due to the presence of various oxygen-containing compounds in the bottoms of butyl alcohols hereinafter (hereinafter referred to as COBS). In addition, the introduction of this additive, due to the presence of high-molecular compounds in the NMPE, negatively affects such an indicator of the quality of diesel fuels as KF. In addition, the fuel is unstable during storage; some of the heavy structures of NMPE fall out during storage.

The prototype of the claimed invention is a depressant additive for diesel fuel based on ethylene copolymers [RF Patent 2599778 JSC "Angarsk Polymer Plant", authors Raskulova T.V., Prokhorchenko I.M., Tyutrin E.G. et al. Published: 20.10.2016, Bul. No. 29], which is obtained by synthesis based on NMPE and styrene, and the subsequent dissolution of the copolymer in an organic solvent and a fraction of diesel fuel with a boiling point range of 200-360 ° C with the following ratio of components:

- copolymer - 10-30% wt.

- organic solvent - 70-90% wt.

- copolymer: diesel fuel - 1: 3 or 1: 5.

The disadvantages of this method of obtaining a depressant additive include the fact that additives based on copolymers of ethylene with other comonomers require a copolymerization stage and the presence of several types of raw materials, which complicates and increases the cost of their production process. In addition, the introduction of this additive negatively affects such an indicator of the quality of diesel fuels as CF. In addition, the fuel is unstable during storage; some of the heavy structures of NMPE fall out during storage.

The objective of the present invention is to create a depressant additive for diesel and marine fuels, which has high depressant properties, meeting the requirements for the KF index, obtained by low-cost production technology.

The task is solved by the formation of a depressant additive from NMPE by removing unwanted poorly soluble high molecular weight compounds from it, by mixing NMPE with low-boiling individual hydrocarbons or hydrocarbon fractions (acting as extractants), followed by settling or centrifugation and separation of poorly soluble high molecular weight compounds with further separation of light-soluble high molecular weight compounds with NM hydrocarbons (extractant) and dissolving the resulting polymer in diesel fuel.

The resulting depressant additive has high depressant properties in relation to diesel and marine fuels in terms of "pour point" and PTF, and also ensures the production of diesel fuels of the required quality in terms of CF.

The use of the obtained depressant additive in the composition of diesel and marine fuels is characterized by the following essential features that distinguish it from the prototype discussed above and make it possible to achieve the stated technical results:

1. The presence of a significant effect on both low-temperature indicators: pour point and PTF.

2. Ensuring the required CF indicator for diesel fuels - no more than 2 according to the requirements of qualification tests of JSC "VNII NP" and no more than 3 for summer diesel fuel according to GOST 305.

3. Fuel with a depressant additive is stable, during storage the additive does not fall out of the fuel.

Experimental studies, confirming the claimed technical result, were carried out on the basis of the Testing Center - Quality Control Department of JSC ANHK.

Hydrotreated summer diesel fuel, used for the production of Euro grade C diesel fuel according to GOST 32511-2013, and the base base for the production of low-viscosity marine fuel according to TU 38.101567-2014 were used as base fuels for testing the additives.

Samples of depressants for testing were prepared as follows:

1. NMPE was mixed in a ratio of 1: 4 with individual hydrocarbons or low-boiling fractions (extractants) isolated during the direct distillation of oil, or fractions obtained in the processes of catalytic processing of hydrocarbon raw materials. Mixing is carried out at a temperature of 50-60 ° C. The names of individual hydrocarbons and hydrocarbon fractions are presented below.

2. The resulting mixtures were poured into separating funnels and kept for 48-120 hours to separate the solution into two layers - the upper, a solution of the light part of the NMPE in hydrocarbons, and the bottom, a suspension of the heavy part of the NMPE in hydrocarbons. To accelerate stratification in some experiments, we used the method of centrifugation of a mixture of NMPE and extractants in a laboratory centrifuge at a temperature of 50-60 ° C and a speed of 3000 rpm.

3. Further, the two layers isolated in the separating funnel were separated, first the lower layer was poured - a suspension of the heavy part of the NMPE in hydrocarbons, and then - the upper layer, a solution of the light part of the NMPE in hydrocarbons. The resulting solutions were tested as depressants by metering diesel or low-viscosity marine fuel into samples.

4. The samples obtained under item 3, using heptane, pentane-hexane fraction as solvents, were subjected to evaporation in order to remove the solvent. The obtained light and heavy parts of NMPE were then dissolved in hydrotreated diesel fuel in a ratio of 20: 80% wt. The resulting solutions were tested as depressants by metering (according to the active substance) into samples of diesel fuel or low-viscosity marine fuel. The following individual hydrocarbons and hydrocarbon fractions were used as solvents under item 1:

- Pentane-hexane fraction from the unit for isomerization of hydrocarbons С ₅ , С ₆ , boiling away within 25-70 ° С (hereinafter PTF);

- Heptane with a boiling point of 98.4 ° C;

- Straight-run gasoline fraction boiling away within 70-100 ° С (hereinafter PBF 70-100);

- Straight-run gasoline fraction boiling out within 95-180 ° С (hereinafter PBF 95-180);

- Kerosene fraction boiling within 140-240 ° С (hereinafter referred to as KF);

- Diesel fuel summer hydrotreated, boiling within 180-360 ° C (hereinafter DTL g / o);

- Gasoline fraction of the catalytic reforming unit, boiling out in the range of 50-90 ° C (hereinafter BFR 50-90);

- KOBS, a by-product of the production of individual butyl alcohols.

As a prototype (reference sample) for the experiments, a solution of a copolymer of NMPE with styrene in hydrotreated diesel fuel in a ratio of 20: 80 wt% was prepared.

As an analogue (reference sample) for the experiments, a solution of the initial LMPE in KOBS was prepared in a ratio of 20: 80% wt.

The obtained samples of depressant additives were introduced in various amounts (indicated in the tables) into samples of diesel fuel or low-viscosity marine fuel at a temperature of 40-60 ° C and thoroughly mixed. After that, the following key quality indicators were determined in the obtained samples of diesel fuel and low-viscosity marine fuel with depressants: pour point (according to GOST 20287-91); PTF (according to GOST 22254-92); flash point in a closed crucible (according to GOST ISO 2719-2017, method A); КФ (according to GOST 19006-73); stability and uniformity (visual); corrosiveness (corrosion of a copper plate according to GOST ISO 2160-2013).

The test results of three samples of DTL g / o with depressants obtained by the above method are presented in tables 1-3.

From the results presented in Table 1, it can be seen that DTL g / o with depressant additives prepared by analogy and the prototype do not meet the requirements of GOST in terms of CF (the indicator is not determined, since the filter is clogged with heavy copolymers of NMPE) and stability. The same negative phenomena are observed when using the heavy part of the NMPE. A depressant additive obtained from NMPE (light part) using heptane provides a decrease in the pour point and PTF, subject to the requirements for CF and diesel fuel stability in accordance with GOST 32511-2013 and GOST 305.

Further, studies were carried out on the extraction of the target light part of the LMPE with low-boiling hydrocarbons - heptane and PTF. The separation of the light part of the NMPE was carried out by two methods described in paragraph 2 of page 5. The depressant additives obtained in this way, when added to DTL with g / o, provide an improvement in low-temperature properties (pour point and PTF), low CF and fuel stability (Table 2).

Then, studies were carried out to determine the influence of the fractional composition of hydrocarbon fractions on the effectiveness of the depressant additive based on the light part of the NMPE. Additionally, in addition to the low-temperature properties of diesel fuel, another critical indicator was determined, "flash point in a closed crucible", which is standardized for diesel fuels in accordance with GOST 32511-2013 - above 55 ° C. Hydrocarbon fractions boiling up to 100 ° C provide selective extraction of the light part of NMPE, when introduced into DTL g / o, good low-temperature indicators and CF are observed, but at the same time the flash point of diesel fuel drops below the required one according to GOST 32511-2013 (the norm is higher 55 ° C). Hydrocarbon fractions boiling above 100 ° C provide selective extraction of the light part of the NMPE, which, when introduced into the DTL with g / o, provides good low-temperature performance and a higher flash point in a closed crucible, but at the same time has a negative effect on CF

To exclude the negative effect of low-boiling hydrocarbon solvents on the flash point of DTL g / o, depressants were obtained according to item 4 of page 5 using NMPE of various periods of production in 2019 - samples 1 and 2. For sample 1, heptane was used as an extractant, for sample 2 - PTF. The obtained light and heavy parts of the NMPE were tested for a number of physical parameters presented in Table 4.

The quality indices of depressants obtained by mixing the light and heavy parts of the NMPE with DF g / o are presented in Table 5.

The depressants obtained by the above described method were tested at various dosages (calculated as NMPE) in DTL g / v. The test results are presented in Table 6. The test results showed that the introduction of the indicated depressants in the range of 100-700 g per ton of DTL g / o provides an effective decrease in the pour point and PTF, the required CF and fuel stability.

The depressant additives obtained by the above method showed high efficiency when added to the base base of low-viscosity marine fuel (TMS). Since the TMS does not standardize the parameters of PTF and CF, the indicator "pour point" was determined. The introduction of a depressant additive based on the light part of NMPE showed its effectiveness in reducing the pour point of TMS (table 7).

During the period of obtaining solutions of the light part of the NMPE in various individual hydrocarbons and hydrocarbon fractions, solutions of the heavy part of the NMPE were obtained in the same individual hydrocarbons and hydrocarbon fractions. Experiments on the involvement of solutions of the heavy part of the NMPE into the basic base of TMS showed the possibility of using the heavy part of the NMPE to reduce the pour point of TMS (Table 8).

On the basis of the isolated heavy part of the NMPE, a depressant additive was prepared by mixing with DTL g / v in a ratio of 20: 80 wt%. (the quality of the obtained depressant is shown in Table 9), which showed efficiency when added to the base TMS base.

The results of testing samples of low-viscosity marine fuel with depressant additives are presented in Table 10. It is shown that with the introduction of a depressant additive based on the heavy part of NMPE at the level of 700, 900 g per ton of TMS (according to NMPE), the requirements for a pour point of no more than minus 10 ° C are achieved. ...

Claims (1)

A method of obtaining a depressant additive for diesel fuel and low-viscosity marine fuel, characterized by the fact that the light part is extracted from low-molecular-weight polyethylene produced by high-pressure polyethylene using low-boiling individual hydrocarbons or hydrocarbon fractions, which boil out in the temperature range of 25-100 ° C, followed by stripping extractant and mixing the resulting product of the extraction process with hydrotreated diesel fuel in a ratio of 20: 80% wt. to obtain a commercial form of a depressant additive for diesel and low-viscosity marine fuel.