Vol 51, No 6 (2016)

We present a review of combustion promoters, including the major classes of organic compounds that can be used in internal combustion engines. We also consider compounds developed that have high promoter action. We give a comparative evaluation of the considered promoters based on analysis of the mechanism of action for the promoters.

We have experimentally studied the effect of anti-knock additives on the tendency of gasolines to undergo oxidation and to form gums during blending and storage. We propose a statistical approach to estimating the significance of the effect of anti-knock additives on the chemical stability of gasolines, and have established regression models for the variation in chemical stability as a function of the anti-knock additive content in the gasolines.

The tribological properties of a new anticorrosion additive for hydrocarbon lube oils that consists of a composite of heteroatomic compounds, namely, ammonium dialkyldithiophosphates and tetraalkylthiuram disulfides, are studied. It is shown that the composite is tribologically active when the component mass ratios are equal.

Low-freezing coolants for automotive engines are analyzed before and after oxidation. It is shown that ion chromatography can be used to monitor the composition change of ethylene-glycol-based coolants and to formulate recommendations for optimizing the method based on current specifications for automotive engine performance. Results for the corrosive effects of coolants on various metals at elevated temperatures are reported. The corrosion depends on the amount of ethylene-glycol oxidation products and the nature of the corrosion inhibitors.

A method and a device are developed to determine the undissolved water content in jet engine fuels under dynamic conditions. The device consists of a sampler, a thermostatically controlled chamber, an undissolved water separation unit, and a unit for measuring the dielectric constant of dewatered and water-containing fuel. Dewatered fuel acts as internal ethanol, and the dielectric constant of ethanol and dewatered fuel is measured at the same temperature.

A review has been made of the methods and technical solutions for ensuring purity of fuels and oils at all stages of their life cycle. The developed designs of filters and filter components for purification of oil products from mechanical impurities, organic contaminants, and emulsified water are analyzed.

Parameters are proposed for estimating longevity of fuel storage facilities by limited tests and operation based on determination of percentage range of operating life. An algorithm is developed to determine the original and extended service life of a fuel storage facility, including durability and strength studies made of its constituent parts with allowance of the time of safe operation.

The physicochemical properties of liquid products from pyrolysis of wood biomass alone and its blend with residual fuel oil are compared. The characteristics of the liquid pyrolysis products with residual fuel oil in the mixed feedstock show a tendency to vary. Thermal conversion of combined sawdust and residual fuel oil in a 1:3 ratio provides the maximum yield and the best physicochemical properties of the liquid bioproduct. The possibility of utilizing the middle-distillate fractions of the pyrolysis products as diesel fuel components is examined.

Kinetic inhibition of formation of methane hydrate (CS-I) and methane-propane (CH₄ + C₃H₈ in 95.66 + 4.34 mole %) hydrate (CS-II) by the polymeric reagents Luvicap 55W and Luvicap EG is studied in the 40-120 bar pressure range. Cooling at the constant rate of 1°C/hr was used to assess the effectiveness of kinetic inhibition. It is shown that the kinetic hydrate formation inhibitors (KHI) Luvicap 55W and Luvicap EG in identical proportion of 5000 ppm are capable of inhibiting methane hydrate formation at a supercooling temperature twice as low (6-7°C) as in the case of hydrates of methane-propane mixture (13-14°C). In the presence of KHI, hydrates appear in the system in the form of visually discernible opacity of the initially transparent aqueous solution at a temperature that is 1-2°C higher than the temperature at the point of deviation of the P(T) curve from the straight line, i.e., they appear earlier than appearance of signs of gas absorption. Formation of such trace quantities of hydrate do not cause a marked deviation of the P(T) curve from the straight line and can be discerned only by more sensitive physicochemical methods. The inhibiting properties of Luvicap EG and Luvicap 55W with respect to methane hydrate differ insignificantly, but the former is more effective in inhibiting crystal growth. The experimental data indicate that Luvicap 55W is more effective than Luvicap EG in inhibiting nucleation and growth of methane-propane hydrate crystals.

We have used a numerical simulation to study the temperature distribution, thermal stress, and thermal displacements during in-situ heating of shales. We have observed that the heater temperature and the temperature at the position of the casing do not change much, while the water temperature in the wellbore and in the region of the cement ring drops quickly. The temperature in layers below the wellbore reach the melting point of the shale after continuous heating for 10-100 hours, while it reaches the heater temperature after 1000 hours. The heating efficiency drops rapidly because of significant convection, which does not permit effective heating of the strata. At the same time, thermal expansion leads to a change in the displacement in the X direction and the equivalent stress. Both the indicated parameters reach a maximum on the well wall and remain unchanged as the distance from the borehole increases. Under these conditions, the casing – cement ring interface and the cement ring – stratum interface slip considerably, separating the two interfaces, and the equivalent stress leads to yield of the casing, the cement ring, and the stratum. The results obtained can be useful for cementing and completion of wells.

A procedure for calculating the pressure and power of a mud pump used in drilling an extendedreach well is described. A method is proposed for determining the hydraulic extension limit length in the drilling process depending on the rated pressure and power of the pump. An example is given of maximum well depth calculation with allowance for the limitations of a specific pump having fixed characteristics.

Thermoextractive conversions of oil shale are studied in the 450-500°C range using supercritical fluids like toluene, decalin, tetralin, tetradecane, gas oil fractions, etc. It is shown that toluene and tetralin in 1:1 extractant:rock weight ratio are the best extractants. The composition of a specific synthetic oil was determined by chromato-mass spectrometry.

A bentonite-free water-based drilling fluid (BFDF) with high-temperature tolerance (up to 200°C) was developed for protecting reservoirs in deep wells. The fluid is composed of heatresistant polymeric thickener and starch, sodium sulfite, etc. A series of methods including environmental scanning electron microscopy (ESEM), linear expansion and hot-rolling dispersion test, and core-flow experiments and measurements of the rheological parameter, filtrate, and biotoxicity were used to evaluate the performance of the BFDF formulation. Laboratory results indicate that the fluid has excellent high-temperature tolerance. Its yield point and plastic viscosity ratio is up to 0.38 even after aging at 200°C for 16 h with API filtrate of 9.8 mL. Its apparent viscosity, plastic viscosity, and yield point at 180°C are 30 mPa·s, 17 mPa·s, and 14.5 Pa, respectively, which show its good well-cutting carrying performance and wellbore purification capacity. The BFDF formulation exhibits a strong ability to restrain the linear expansion rate of bentonite and shale powder, to improve cutting recovery, to protect the well reservoir by cutting down water blocking and lowering permeability damage, and to minimize biotoxicity with a high EC₅₀ value and is suitable for drilling deep wells in environmentally sensitive areas.

This article presents experimental and theoretical data on the catalytic cracking of oil sludge mixed with vacuum gas oil with and without activation of the feedstock by electromagnetic radiation. Mathematical models of the catalytic cracking of oil sludge in the presence of aluminosilicate zeolite catalysts are constructed. It is demonstrated that preactivation of the feedstock enhances gasoline and diesel yield upon cracking. Cracking of activated feedstock occurs with a lower activation energy.

Based on dynamic corrosion experiments, we propose a new model for predicting corrosion rate that is based on an alternating conditional expectation (ACE) algorithm. This model lets us more accurately predict the corrosion rate for a broad range of temperatures, pH, and concentrations of Ca²⁺, HCO₃⁻, Mg²⁺, Cl^–, SO₄^2 − ions. Based on tests performed on a testing sample group, we have confirmed the reliability of the model and have also demonstrated its high accuracy. Sensitivity analysis based on a rank correlation coefficient revealed that the major factor influencing the corrosion rate of N80 steel is the pH value. We have also carried out a comparison analysis of the results obtained when using the ACE algorithm and the results obtained when using a backpropagation neural network (BPNN) and the support vector regression (SVR) method. As a result, we found that the model based on the ACE algorithm is more accurate than other currently used models.