Vol 53, No 1 (2019)

The results of inspecting the systems monitoring the condition of navigation hydraulic structures of operating organizations are presented. Practical recommendations aimed at increasing the reliability of measurement results and development of systems for monitoring the condition of structures are formulated on the basis of an analysis and generalization of the data obtained.

Brief characteristics of the mineral raw material potential of the deep-sea deposits of ferromanganese nodules in the area of the Clarion-Clipperton Zone leased by Russia in the Pacific Ocean are presented. The creation at the Moscow Mining Institute (MGI) of the USSR’s first Scientific and Technical Problems Laboratory and the results of its work on extraction of minerals from the sea and ocean floor are reviewed. The research works carried out by MGI on underwater mining of ilmenite-rutile-zirconium sands on the Baltic Sea shelf and Iturup Island and tin under conditions of northern seas and the development of the technogenic placer of the East Siberian Sea are analyzed. The concept of using the kinetic energy of coaxially swirled fluid jets in hydrotransport-hoisting devices of vortex slurry preparation, which was tested in the Black Sea and an air-lift mud intake by mechanical and hydraulic loosening for extracting diamond-containing gravel-pebble rocks on the Namibia shelf is given.

Methods of systems reliability theory are applied to the results of an expert inspection of more than 1000 low-head hydraulic power systems in the Moscow region. The rates of failure of homogeneous earth dams are estimated. A state graph of a hydraulic structure, represented as a system that passes through discrete states from a normal to a dangerous level without maintenance or repair, is proposed. The constant failure rates for these states are calculated. The probabilistic characteristics of the safety level of low-head earth dams are predicted.

The technologies and results of an experimental determination of residual stresses in the impeller blades of a hydraulic unit of the Krasnoyarsk hydroelectric power plant obtained through technical diagnostics beyond the projected periods of use are presented. The investigations of the residual stresses were performed by strain measurement with excision of templates and the optical method of speckle interferometry. Factual values of the components of the residual stresses in two zones of the blade with nonuniform stress fields were obtained.

In model experiments on waves and ice effects on hydraulic structures, special attention should be paid to the modeling of wave and ice processes to obtain reliable data.

The results of laboratory experiments on modeling the processes of diffusion leaching of non-saline Sarmatian clays were analyzed, and a methodology is proposed for predicting the stability of leached clay.

The question of the optimal shape of a hydraulic turbine blade is the chief issue in hydraulic turbine construction. It is necessary to design and create a sample of a turbine impeller with maximum efficiency and high cavitation properties. In order to achieve this objective, studies are conducted that are based on hydrodynamic analysis of the hydraulic turbine water path and selection of the best turbine blade geometry, by bringing in methods of genetic optimization. The author of this article proposes a different method of creating a turbine impeller: adding additional blade-splitters to the design.

An analysis of the causes of erosion-induced wear of the metal in pipe bends of evaporator heating pipe surfaces is performed based on experience gained from the operation of the heat-recovery boilers of combined-cycle (steam-gas) power plants. Damage to the evaporator tubes of a low-pressure boiling circuit is caused by the destruction of the protective oxide film due to intensive turbulization of the near-wall layer of water (which is at saturation temperature) travelling through the bend, inducing cavitation due to the formation of steam bubbles and their condensation. The protective oxide film formed in the hydrate water chemistry regime possesses the greatest stability.

A study of the chemical composition of scale and metal on the outer surface of the superheater tube made of austenitic chromium-manganese (Cr-Mn) steel grade DI59 after prolonged operation is presented. It is shown that a modified layer is formed on the metal consisting predominantly of a ferromagnetic phase of á-Fe (ferrite). The thickness of the layer contains information about tube operating conditions. Results are provided for application of magnetic ferritometry to determine thermal inhomogeneity and steam heater residual life.

The basic design of the high-voltage thyristor valve developed for the Vyborg converter substation is described. The parameters of the design impulse voltage across the valve and the model of the converter bridge valve assembly are justified. It is established that when subject to a design lightning impulse voltage, the designed valve ensures safe operation in terms of the voltage amplitude and voltage rise rate in the thyristors. It is shown that the difference between the detailed and simplified model does not exceed 3%.

The article provides an overview of the methods of quantitative analysis of an additive. The specifics occurring when determining the additive using the most common chromatographic methods are discussed. The advantage of the near-infrared (NIR) technique is shown, which offers selectivity, rapidity, low labor intensity, high sensitivity and feasibility of being used in the automated monitoring systems.

This article is the first of a cycle dedicated to the experimental investigation and process optimization of the combustion of an air-fuel mixture with gas temperatures at exit from the combustion chamber of approximately 1700 °C, while satisfying the requirements relating to emissions. The article is divided into two stages. The first stage examines the possibilities of obtaining minimal NO_x and CO concentrations when using a traditional (single-stage) system for combustion of a prepared air-fuel mixture (AFM). It presupposes the presence of one burner unit (BU) through which fuel and air enter the combustor (COMB), and the combustion process is executed in flame stabilization zones that are formed in it due to swirl generators and/or bluff bodies. For such a system, the effect on NO_x and CO emissions over the range of exhaust temperatures from 1300 to 1700°C (CC excess air coefficient from 2.2 to 1.6) from the following was studied: the quality of preparation of the AFM, the pilot burner air, the flow speed in the COMB, and the air temperature at intake. The second stage examined the possibility of reducing harmful emissions due to the use of a two-stage sequential plan of fuel combustion. This presupposes the presence of two BUs, one of which, a traditional one (BU1), is placed at the inlet face of the COMB; and a second, sequential one (BU2), on the side walls of the COMB below the flow. Here, results are produced in testing BU2, in the form of an annular sudden flow constrictor with fuel-injection apertures arranged on its circumference. The total fuel flow is partitioned between the stages. In the first stage, combustion occurs for fuel in the form of the AFM, and in the second the remaining fuel is combusted in the hot flow of gases of the first stage, depleted by oxygen. The effect of the AFM temperature intake to the first stage and the speeds of its feed to the COMB on NO_x and CO emissions over the range of exhaust temperatures from 1300 to 1700°C is studied for this system. The results were obtained in tests on a model CC at a test station of JSC VTI. Multivariate parametric studies on this subject were published earlier [1–3].

The scale factor for the use of power plants of a certain type refers to the fraction of their use in the overall energy balance of the system. Energy production by wind power plants depends directly on the wind conditions in a particular location and is stochastic in character. Increasing the fraction of these installations in the overall balance of a system also requires an increase in the power reserve capacity. Here the time a power system remains in the power deficit zone is estimated as a function of the fraction of wind power plants in the system structure. Two approaches to the placement of wind power units within a power system are compared– individual components and a system of a set of components. It is concluded that even within a small power system, combining geographically distributed components with favorable and unfavorable wind conditions into a system can have a positive effect on all the components within certain ranges of the scale factor.

The information about the article source should read “Translated from Élektricheskie Stantsii, No. 8, August 2018, pp. 31 – 36.”