Vol 52, No 3 (2018)

A work package for filling the voids under the pumped-storage powerhouse and pressure grouting to strengthen the foundation soil is described. The compositions of the injectable grouts and specially designed composite material are presented. The results are analyzed.

To justify that hydroelectric power plants operating in seismic areas are safe, it is necessary to analyze the resonance phenomena in the generating unit. The analysis was performed using a finite-element model of the powerhouse-foundation-equipment system of the Lower Bureya HPP. The resonance phenomena occurring when the disturbance frequency at the elevation of the stator supports is close to the first natural frequency and speed of the water turbine were studied.

The article examines problems of real-time remote monitoring of the geometric form of the upper alignment and natural frequencies of oscillations of a dam using a radiogeodetic method with accuracy to ± 1 mm from a distance up to 1000 m. At the foundation of the method is the use of active radar and miniature switched re-radiators in the form of slot antennas located in a linear row along the top edge of a dam. By contrast with the method of telemetry that uses high-precision optical devices — tachometers, levelers, etc. — the radiogeodetic method can be executed in real time with minimum effect from weather conditions.

Some results of generalizing and analyzing long-term on-site observations of the construction and operation of high-head concrete dams with consideration of geodynamic effect and imperfection of the designs of dams in tectonically unstable regions are briefly presented.

Experience gained from sprayed concrete operations in the construction of several tunnels around Sochi and reconstruction of the Kurort Prospekt in the city as well as devices for sprayed concrete reinforcement of open slopes along automobile roadways is described. The compositions of different types of sprayed concrete are given and the strength indicators in the initial periods of hardening are indicated. Certain parts of the production process are demonstrated and practical recommendations presented.

A new graphical-and-analytical method for design of reinforced-concrete scroll casings with trapezoidal cross-sections of water turbines is proposed. This method generalizes the methods currently used to determine the trapezoidal cross-section dimensions of scroll casings, given the dimensions of their inlet cross-section. This method allows considering different laws of variation in the cross-section average tangential velocity along the scroll length: the velocity can increase, be constant, decrease, or vary differently within different sections of the scroll. The necessary formulas are derived by an analytical method. The design procedure is described by way of examples.

Preheating of forced air in a surface-type heat exchanger prior to supplying it to the air heater of the boiler by using flue gases while cooling them below the dew point is proposed. Athermal calculation of the condensing heat exchanger installed downstream of the boiler (model BKZ-420-140 NGM) was performed to determine the thermal capacity of the heat exchanger, flow rate of flue gases required to preheat forced air supplied to the boiler while cooling them below the dew point, flow rate of the water vapor condensate obtained from the gaseous fuel combustion products, temperature of flue gases at the outlet of the boiler unit, and fuel utilization factor of the boiler resulting from the use of the condensing heat exchanger. The water vapor condensate obtained from flue gases in the surface heat exchanger can be used as make-up water for the heat network. It was established that depending on the ambient air temperature, the percentage of flue gases directed to the heat exchanger for preheating forced air of the BKZ-420-140 NGM boiler assuming their cooldown below the dew point constitutes 3.9 to 20.7 and 7.6 to 24.4% of their total amount, when heating air to 20 and 30°C, respectively. The economic effect in the monetary terms due to installation of the condensing heat exchanger downstream of the BKZ-420-140 NGM boiler amounts to 12, 691.7 and 17,242.2 thousand RUB/year, when heating forced air to 20 and 30°C, respectively. Considering five power-plant boilers installed at the Samara CHP operated by “Samarsky” branch of the PJSC “T Plus,” the amount of savings should reach 63.5 and 86.2 million RUB/year, respectively.

The results of the development and study of the start-up sequence for an E-240-13.8-560KT steam boiler are presented. Criteria of reliable operation of boiler components during start-up are proposed. The change in the main operating conditions of the boiler during start-up is described. The use of emergency start-up injection is justified. The effect of the wall thickness of the drum on the start-up of the boiler is analyzed.

Favourable experience is summarized for manufacturing, welding, storage, and operation of superheaters made of heat-resistant chromium-manganese steel DI59, and a mechanism is described for overall corrosion breakdown and oxidation over pipe metal grain boundaries under action of active components fuel combustion products of V₂O₅ and sulfur compounds.

Polymer materials used in protected wires are very sensitive to the temperature increase that occurs in the course of a short circuit (SC) current. Heating the insulation of the wire above the admissible temperature for it may make it necessary to replace the damaged wires. A methodology is proposed for calculating the admissible SC current for the protected wires of an OHL, taking into account the periodic and aperiodic components of the SC current. The materials of this article can be used in designing and using lines made with protected wires.

It is shown that the basic variations in the energy market are related to increasing requirements designed to assure ecological cleanliness as well as increase efficiency, reliability, and maneuverability. The ability of the technology underlying the combustion of solid fuels in a circulating fluidized bed to respond to these variations is demonstrated using concrete examples. It is noted that the efficiency of the circulating fluidized bed technology is determined basically by the quality of the fuel and the capacity of the power station with specified constraints imposed on discharges of harmful substances. Attainment not only of the norms on harmful substances existing in the Russian Federation, but also of prospective norms without the use of desulfurization and denitrogenization devices, is an important condition for optimal use of the technology. Another major advantage is the diversification of fuel deliveries. The first boiler in Russia employing a circulating fluidized bed was built at Unit No. 9 of a condenser type electricity-only thermal power station (GRES) at Novocherkassk, Rostov oblast’. Delivery of the boiler was performed by the firm of JSC EMAl’yans Inzhiniring while delivery of certain critical parts and auxiliary equipment, by the firm of Amec Foster Wheeler (now Sumitomo Foster Wheeler, or SFW). The first results of the operation of a circulating fluidized bed boiler are presented and an analysis of trial data on the thermal balance of the heating surfaces is presented. In the case of similar values of the trial and design heat absorption of the boiler guard screens, the temperature of the gases in the boiler is substantially higher than the design temperatures. Certain difficulties associated with the technology of combustion are identified in the process of adjustment and early use of the circulating fluidized bed boiler in Unit No. 9 of the Novocherkassk GRES. The need for a more detailed study of the processes involved in production of additional measurements and of studies on operational development of the equipment and thermal circuit, and optimization of the operating conditions is demonstrated.

In a centralized emergency control system (CECS) with a third-generation algorithm, emergency control actions (CA) are selected under conditions of preventing disruption of dynamic stability, providing the required margin of stability in post-emergency condition, as well as preventing overcurrent and restricting voltage in network nodes to admissible limits. A methodology for selecting CAs for these last two conditions is described.