Straight-run Diesel Research Articles

Oxidation and stabilization of hydrocarbon fuels in contact with rock salt

Underground storage is the most ecologically clean and economical method for extended storage of natural gas, crude oil, and petroleum products. Such storage reservoirs are created in stable rock (granites, gneisses, limestone, etc.), rock salt deposits, clays, abandoned mines, and permafrost formations. In this investigation of the influence of rock salt deposits on the oxidation of hydrocarbons (summer-grade straight-run diesel fuel L and automotive gasoline A-76 [unleaded, low-octane]), the authors carried out a kinetic study of hydroperoxide accumulation during the oxidation of these fuels after contact with a saturated solution of rock salt (brine). The experiments were performed in a bubbler-type unit with various ratios of brine to fuel.

Production of low-pour diesel fuels by catalytic dewaxing

Catalytic dewaxing is performed with a catalyst based on high-silica zeolites of the TsVM type, with a preassigned pore structure; high-freezing straight-chain paraffinic hydrocarbons can be removed from straight-run diesel distillates by means of this process. In the studies reported here, they used a straight-run 200-360/sup 0/C diesel fuel cut from medium-sulfur mixed West Siberian crudes, and also the same cut after hydrotreating. These cuts corresponded in distillation range to standard summer-grade diesel fuels, and they contained approximately 20% straight-chain paraffinic hydrocarbons. Three different schemes were used in performing the experiments: single-step, without any preliminary hydrotreating of the feed; single-step two-stage, with hydrotreating catalysts charged to the first reactor, and with the gas-product mixture form the first stage fed to the dewaxing stage without any intermediate fractionation; and two-step, with hydrotreating of the feed in the first step.

Flammability of diesel fuels with various compositions

This paper reports on a study of the flammability of a number of fuels and blends, in relation to their physicochemical properties, particularly the volatility; these studies were performed in a specially designed simulator. The following fuels were used in the studies: a hydrotreated straight-run diesel fuel L; a catalytic gas oil; diesel fuel A; blends of diesel fuels L and A with cetaine, alpha-methylnaphthalene, undecane, and docosane; and a blend of fuel L, A-72 gasoline, and the additive TsGN. The physicochemical properties of the test fuels are shown. It is shown that the flammability of fuels with various compositions in a diesel engine is more correctly evaluated on the basis of the ignition delay period, which can be calculated from the cetane number and other physicochemical property indexes of fuels for a particular set of engine operating conditions.

Thermooxidative stability of diesel fuels

The authors present results from an investigation of the thermooxidative stability, under static and dynamic conditions, of diesel fuels before and after hydrotreating. Data are reported on the influence of catalytic gasoil on the stability of diesel fuels. The physicochemical properties of the test fuels are listed. The determination of thermooxidative stability under static conditions was performed in TSRT-2 apparatus at temperatures of 150, 170, and 190 degrees C, for a period of 5 hours. It was found that for diesel fuels, the temperature dependence of thermooxidative stability may be extremal. Hydrotreated diesel fuel, in comparison to the straight-run, is higher in thermooxidative stability. In order to improve this quality index for blends of straightrun diesel fuel and catalytic gasoil, the fuel blend may be hydrotreated, or additives may be used--materials that improve the thermooxidative stability of diesel fuels.

Preparation of sulphide concentrates from petroleum distillates by extraction with organic solvents

1. 1. A system was developed from a study of the selectivity of extraction agents and conditions selected for the isolation of sulphide concentrates from straight-run diesel fractions by two-stage sequential extraction with furfural and phenol. 2. 2. From fractions of Arlan crude sulphide concentrates with an overall sulphur content of 8:9% and sulphide content of 7:8.3% were obtained. The method proposed for extraction enables 38–45% sulphides contained in the fraction to be isolated, which is comparable with results of single-stage sulphuric acid extraction. 3. 3. A study was made of advantages of furfural-phenol extraction to sulphuric acid extraction and methods of further improvements as a result of the optimization of process parameters and the use of extraction reagents of increased selectivity.

Use of an ashless additive to improve the anticorrosion properties of hydrotreated diesel fuels in the presence of water

Either hydrotreated or low-sulfur straight-run diesel fuels, when wet, may cause corrosion of fuel-system metals in power units. For corrosion protection of fuel systems of shipboard power units when operating on wet hydrotreated fuels, it is necessary to use anticorrosion additives. In this report results of a test program are presented which showed that the addition of 0.04% of a sulfonate made from lubricating oil, neutralized with ammonia solution of urea (tradenamed BMP) gives complete corrosion protection of fuel-system metals when either fresh or salt water is present in the fuel.

Fuels for the north

1. The A-76 and AI-93 nonethylated winter gasolines and “A” and “DA” diesel fuels being produced by refineries for the northern regions satisfy consumer requirements in most respects. 2. The resources of diesel fuels with low solidification points can be expanded by producing fuels from hydrofined and dewaxed sulfur crude, and by adding to the fuels 20–40% of low-octane gasoline fractions (60–160°C). 3. Wide-cut fuels may be used unmixed in diesel and gas-turbine motors. 4. We can recommend the manufacture of domestic boiler fuel with low solidification points from straight run diesel fractions and thermally cracked kerosene fractions or other secondary petroleum refining processes after corresponding treatment.

Experience in producing gasoline and diesel fuel from high-sulfur crudes

1. Possibility was shown for obtaining commercial diesel fuel with sulfur content up to 1% from high-sulfur crudes by means of treating heavy high-sulfur diesel fractions in the 43–102 unit operating under conditions of destructive adsorption desulfurization (390–420°C temperature in the reactor center, charging stock velocity 1.2–1.8/h) and subsequently blending them with straight-run light diesel components. 2. The cost of diesel fuel with 1% sulfur content prepared according to this technological variant is 20% lower than the cost of similar commercial fuel obtained by means of blending high-sulfur fractions with hydrotreated low-sulfur component. 3. Use of the 43–102 unit for partial desulfurization of high-sulfur diesel fractions may be acknowledged as expedient with the scarcity of heavy charging stock for catalytic cracking. 4. Possibility was shown for accomplishing partial desulfurization of high-sulfur thermally cracked gasoline in 43–102 units at 410–420°C temperature and space velocity of 0.75/h. 5. It requires eight times less fraction-thinner when used with the thermally treated gasoline in the A-66 stream than in the case of compounding it with the initial product.

Hydropurification of diesel fuel with reduced consumption of hydrogen in an industrial unit

1. The long operation time of an industrial hydropurification unit confirmed the correctness of the recommendations of the Bashkirian Scientific Research Institute of Oil Industry and the All-Union Scientific Research Institute of Oil Industry as to the possibility of reducing the hydrogen consumption. 2. The yearly average of the hydrogen consumption in 1963 during the hydropurification of straight-run and secondary diesel fuel at the reactor temperature of 380°C and the pressure of 28–36 atm amounted to 0.46, i.e., was 1.5 times lower than the design value. 3. Lowering of the pressure in the reactor from 34–36 to 28–30 atm enabled us to reduce the hydrogen consumption 1.3 times without deterioration of the product quality. The operation time of the catalyst between regeneration was eight months. 4. It has been shown that the activity of the catalyst drops faster in the first than in the next reactors. The degree of removal of sulfur compounds drops below 50% in the first reactor when 1200 t of feed per 1 m3 of catalyst have been treated, whereas in the second reactor this level is reached after purification of 2300 t of feed per 1 m3 of catalyst.