Yu. M. Brodov

Analysis of Indicators Characterizing the Reliability of Cogeneration Turbines

Results from an analysis of indicators characterizing the reliability of cogeneration turbines produced by the ZAO Ural Turbine Works for a long time of their operation are presented. The most typical defects of cogeneration turbines that revealed themselves under field conditions are presented together with the main factors causing failures of the turbine as a whole and failures of its individual assemblies (parts).

Experience gained from development of modernized oil coolers for the oil supply system used in 800-MW turbines

Problems encountered during retrofitting of oil coolers in operating steam turbine units are discussed. Results obtained from numerical simulation of oil leaks occurring in the gaps between the tube bundles of oil coolers are presented. Different design versions of a modernized MB-270–330 oil cooler are calculated, and the effect of different design parameters on the performance characteristics of such apparatuses is analyzed. The adopted technical solutions made it possible to develop the oil cooler that has been installed in 13 of the 15 800-MW turbine units that are currently in operation in Russia.

Condensers for Cogeneration Steam-Turbine Units of the Ural Turbine Works

The designs of condensers used as part of the steam-turbine units equipped with cogeneration turbines developed by specialists of Ural Turbine Works are presented. Special features pertinent to the design and calculation of the apparatuses and stemming from the conditions under which they operate as part of the thermal schemes of cogeneration turbines are pointed out.

Controlling the startup modes of cogeneration steam turbines operating as part of combined-cycle power plants

The results obtained from investigations of combined-cycle power plants produced by the Ural Turbine Works aimed at achieving high maneuverability, reliability and longevity of cogeneration steam turbines taking into consideration the possibilities of modern automated process control systems are presented. The dynamic models for simulating the heating of a steam turbine cylinder’s parts with the use of limited computation capacities are developed.

A comprehensive analysis of the reliability indicators for heat exchangers of steam turbine units

Results are presented from analyzing, using an expert method, the indicators characterizing the operational reliability of different shell-and-tube heat exchangers used in the circuits of steam turbine units. Cause-and-effect relations for the failure rates of the tube systems of such apparatuses are considered on the basis of reports on failures of the power equipment of steam turbine units at thermal power stations.

Investigation of the effect of pressure increasing in condensing heat-exchanger

The effect of pressure increase was observed in steam condensation in the intermediate coolers of multistage steam ejector. Steam pressure increase for ejector cooler amounts up to 1.5 kPa in the first ejector stage, 5 kPa in the second and 7 kPa in the third one. Pressure ratios are equal to 2.0, 1.3 and 1.1 respectively. As a rule steam velocities at the cooler inlets do not exceed 40...100 m/s and are subsonic in all regimes.The report presents a computational model that describes the effect of pressure increase in the cooler. The steam entering the heat exchanger tears the drops from the condensate film flowing down vertical tubes. At the inlet of heat exchanger the steam flow capturing condensate droplets forms a steam-water mixture in which the sound velocity is significantly reduced. If the flow rate of steam-water mixture in heat exchanger is greater than the sound velocity, there occurs a pressure shock in the wet steam.On the basis of the equations of mass, momentum and energy conservation the authors derived the expressions for calculation of steam flow dryness degree before and after the shock. The model assumes that droplet velocity is close to the velocity of the steam phase (slipping is absent); drops do not come into thermal interaction with the steam phase; liquid phase specific volume compared to the volume of steam is neglected; pressure shock is calculated taking into account the gas-dynamic flow resistance of the tube bundle. It is also assumed that the temperature of steam after the shock is equal to the saturation temperature.The calculations have shown that the rise of steam pressure and temperature in the shock results in dryness degree increase. For calculated flow parameters the velocity value before the shock is greater than the sound velocity. Thus, on the basis of generally accepted physics knowledge the computational model has been formulated for the effect of steam pressure rise in the condensing heat exchanger.

Gas Dynamics And Heat-and-mass Transfer In Multistage Steam Jet Pumps With Intermediate Condensers

To specify the gas dynamics physical model and the design methods for ejectors, as well as the intermediate coolers functioning features, a range of complications has been formulated. It has been proven that the coefficient defining the critical section position of the secondary stream and characterizing the entrainment ratio of the ejector first stage depends on the characteristics of “a sound pipe” zone. Within this zone the velocity of the secondary stream can exceed sonic speed while the shock waves in the primary stream decrease. The optimum axial dimensions of the ejector are determined by the characteristics of “a sound pipe”. The experimental investigations results reveal that the flow rate portion of steam condensed in the first stage cooler is about 70–80% of the full flow rate of steam entering the cooler and virtually doesn’t depend on the air content in steam. The cooler efficiency depends on steam pressure, which is determined by the performance of the subsequent stage ejector and also by the cooling water temperature and flow rate.

Heat Transfer Augmentation During WaterSteam Condensation On Twisted Profile Tubes

Some results are presented of experimental and theoretical research of hydrodynamics and heat transfer during condensation of water steam (both stationary and slowly moving) on twisted profile tubes (TPT). For a heat transfer coefficient during condensation of stationary steam on TPT two characteristic areas were observed. At small values of condensate film Reynolds numbers a TPT heat transfer coefficient can be 10–15% below that of the plain tubes depending on profile parameters. With the rise of both condensate film Reynolds number and profile parameter h/s heat transfer coefficient increases up to 50% in comparison to a plain tube. During slowly moving steam condensation the TPT heat transfer coefficient increases up to 70% as compared to a plain tube. Conducted research and industrial tests results showed that the assured effect of a heat transfer coefficient increase in TPT heat exchangers could reach for turbine condensers 15%, for low cycle heaters 35–40%. The heat exchangers hydraulic resistance increases by 40–70%.

Single-phase media hydrodynamics and heat transfer in heat exchangers with twisted profile tubes

A profiled heat exchanger tube is the one in which some features have been incorporated into the tube geometry for heat transfer enhancement. They offer a perspective method of steam turbine shell-and-tube heat exchangers improvement. Twisted profile tubes (TPT) are widely used in power engineering. This paper presents some results of experimental and theoretical research of hydrodynamics and heat transfer in TPTs. It is revealed that the heat transfer coefficient for water flow in a TPT increases up to 80% compared to that of a plain tube. With a rise of media Reynolds number, the heat transfer rate in a TPT decreases in comparison to that of a plain tube, but for air flow in a TPT the heat transfer coefficients ratio does not depend on the Reynolds number value. Water flow hydraulic losses in TPTs increase from 15 to 100% depending on the tube profile parameters.

Gland seal heaters and steam jet ejectors with surface coolers used in the steam units produced by the Ural Turbine Works

The designs of coolers for gland seal heaters, as well as the main ejectors and seal ejectors, used as part of cogeneration steam turbine-based steam turbine units developed by specialists of the Ural Turbine Works are described. The design features of the apparatuses connected with the specific features of their operation as part of combined-cycle plants equipped with cogeneration turbines are shown.