Combustion characteristics of mixtures of certain hydrocarbon fuels in air

© 2020 Published under licence by IOP Publishing Ltd. A theoretical study of the combustion of hydrocarbon fuel mixtures in water heating unit was carried out. The effect of hydrogen impurities and propane-butane fuel on the optimal (α = 1) combustion of natural gas in air is established

Construction of a mathematical model of the vibrational process of pipelines under internal and external loads

© 2020 Published under licence by IOP Publishing Ltd. The article proposes a modal analysis of the natural vibrations of polyethylene pipelines, which is a calculation of the vertical and lateral pressure exerted by the soil on the pipelines, on the basis of which an oscillation study was conducted in the Ansys software package. The results of modal analysis for polyethylene pipes are presented for a laying scheme with inclined walls and various soils

Full compensation of reactive power in electric networks 0.4-10kV

© 2020 Published under licence by IOP Publishing Ltd. The most important task in electric networks is to reduce energy losses. According to Network Company, in distribution electric networks with a voltage of 0.4-10 kV, they account for 62% of the total number of losses. One way to save energy is reactive power compensation. From Order of the Ministry of Energy of the Russian Federation dated June 23, 2015 No. 380 "On the Procedure for Calculation of the Ratio of Consumption of Active and Reactive Power for Individual Energy Receiving Devices (Groups of Energy Receiving Devices) of Electric Power Consumers" at a voltage of 0.4 kV, the reactive power coefficient should not exceed the value 0.35, and on the side of 10 kV-values of 0.4. In practice, in distribution electric networks, reactive power compensation devices are not installed in most cases, and the reactive power factor is 2-3 times higher than the standard values. Since compensating devices are expensive equipment, it is necessary to evaluate the feasibility of deep reactive power compensation, in the range of reactive power factor changes from its standard value to zero. The article discusses the economic and technical feasibility of deep reactive power compensation. The use of a generalized parameter of the electric network for determining the voltage at substations of distribution electric networks is proposed. The need for the coordinated use of reactive power compensation devices and booster transformers to ensure the quality of electricity is shown

CFD-modeling of the pulsed combustion in vortex chamber

© 2020 Published under licence by IOP Publishing Ltd. The article is a review of existing mathematical methods used in modeling the combustion process of gaseous fuels in order to determine the most suitable model for pulsed combustion

Thermodynamic combustion analysis of methane-hydrogen and methane-propane-butane mixture in a water heating installation

In this research considers the combustion of methane mixtures with hydrogen or propane-butane fuel as applied to water heating installation. The determination of conditions under which the considered mixtures have a stoichiometric composition, and the heat release rate is equal to the value that corresponds to the combustion of only methane. It is shown that the air consumption is equal in all cases. It has been established how it is necessary to change the fuel consumption depending on the concentration of gases in a mixture with methane in order to implement these conditions

Promotion of hydrate formation with the use of polyatomic and cyclic alcohols sulfosuccinates: Studies under dynamic conditions

As the most environmentally friendly fossil fuel, natural gas has been consumed intensively around the world. However, transportation and storage difficulties still pose a serious constraint to its efficient use. Of all methods for storing natural gas, solidified natural gas technology relying on gas hydrate formation, looks feasible and promising because it is green and safe, as well as assumes moderate thermobaric conditions and easy regasification. The large-scale adoption of this technology is hindered by the low rate of hydrate formation, which can be increased with the help of chemical additives called hydrate formation promoters. This article presents new promoting agents based on sulfosuccinates of cyclic and polyatomic alcohols. We studied their promoting activity in high-pressure autoclaves, foamability, and interfacial tension. The obtained results show that the synthesized reagents enhance the formation of hydrates as compared to pure water, and, unlike the well-known commercial reagent sodium dodecyl sulfate, they do not form a stable foam, which is essential for the operational properties of promoters

Analysis of the effect of combustion chamber length on the gas oscillations characteristics

In this paper, the case of the influence of a change in the length of the vortex combustion chamber on the amplitude-frequency characteristics of gas oscillations is considered. Experimental data were obtained, on the basis of which the graphs of the dependence of the amplitude and frequency of the combustion chamber on the excess air ratio were received

Laboratory studies for design of a foam pilot for reducing gas channeling from gas cap in production well in messoyakhskoye field

Messoyakhskoye field, operated by Gazprom Neft, is currently experiencing gas channeling from gas cap in production wells because of strong heterogeneity. Foam for a long has been considered as a good candidate for gas blocking, (Svorstol I. et al., 1996), (Hanssen, J. E., & Dalland, M. 1994), (Aarra, M. G. et al., 1996). However, foam injection for gas blocking in injection well is different from that in production well, where it is necessary to selectively and long-term impact on gas-saturated highly permeable areas without affecting the phase permeability of oil in the reservoir. This paper provides detailed laboratory studies that show how to determine suitable foam systems for gas blocking in production well. For gas blocking in production well, a long half-life time is required to sustain stable foam because a continuous shear of surfactant solution/gas can't be achieved like in injection well. Therefore, reinforced foam by polymer is chosen. Four polymer stabilizers and five foam agents were evaluated using bulk test to determine foaming ability, foam stability, and effect of oil by comparing foam rate and half-life time to determine the suitable foam system. Furthermore, filtration experiments were conducted at reservoir conditions to determine the optimal injection mode by evaluating apparent viscosity, breakthrough pressure gradient, resistance factor, and residual resistance factor. Polymer can significantly improve half-life time (increase foam stability), and the higher the polymer concentration, the longer the half-life time. But simultaneously, a high polymer concentration will increase the initial viscosity of solution, which not only decreases the foam rate, but also increases difficulties in injection. Therefore, an optimal polymer concentration of about 0.15-0.2 wt% is determined considering all these influences. Filtration experiments showed that the apparent viscosity in core first increased and then deceased with foam quality (the ratio of gas volume to foam volume (gas + liquid). The optimal injection mode is co-injection of surfactant/polymer solution and gas to in-situ generate foam at the optimal foam quality of about 0.65. Filtration experiments on the different permeability cores showed that gas-blocking ability of polymer reinforced foam is better in high-permeability cores, which is beneficial for blocking high permeability zone. It should be also noted that under a certain ratio of oil to foam solution (about lower than 1 to 1), the presence of oil slowly decreased foam rate with increasing oil volume, but significantly increased half -life time, which is favorable for foam treatment in production well. This work highlights the difference between foam injection for gas blocking in production well and injection well, and emphasizes the use of polymer reinforced foam. Moreover, this work shows systematic experimental methods for choosing suitable foam systems for gas blocking in production well considering different factors, which provides a guide regarding what kinds of foaming agents and polymer stabilizers should be used and how to evaluate them for designing a pilot application

Performance of Waterborne Polyurethanes in Inhibition of Gas Hydrate Formation and Corrosion: Influence of Hydrophobic Fragments

The design of new dual-function inhibitors simultaneously preventing hydrate formation and corrosion is a relevant issue for the oil and gas industry. The structure-property relationship for a promising class of hybrid inhibitors based on waterborne polyurethanes (WPU) was studied in this work. Variation of diethanolamines differing in the size and branching of N-substituents (methyl, n-butyl, and tert-butyl), as well as the amount of these groups, allowed the structure of polymer molecules to be preset during their synthesis. To assess the hydrate and corrosion inhibition efficiency of developed reagents pressurized rocking cells, electrochemistry and weight-loss techniques were used. A distinct effect of these variables altering the hydrophobicity of obtained compounds on their target properties was revealed. Polymers with increased content of diethanolamine fragments with n- or tert-butyl as N-substituent (WPU-6 and WPU-7, respectively) worked as dual-function inhibitors, showing nearly the same efficiency as commercial ones at low concentration (0.25 wt%), with the branched one (tert-butyl; WPU-7) turning out to be more effective as a corrosion inhibitor. Commercial kinetic hydrate inhibitor Luvicap 55 W and corrosion inhibitor Armohib CI-28 were taken as reference samples. Preliminary study reveals that WPU-6 and WPU-7 polyurethanes as well as Luvicap 55 W are all poorly biodegradable compounds; BODt/CODcr (ratio of Biochemical oxygen demand and Chemical oxygen demand) value is 0.234 and 0.294 for WPU-6 and WPU-7, respectively, compared to 0.251 for commercial kinetic hydrate inhibitor Luvicap 55 W. Since the obtained polyurethanes have a bifunctional effect and operate at low enough concentrations, their employment is expected to reduce both operating costs and environmental impact