Showing papers on "Thermal power station published in 1995"

Combined cycle with steam cooled gas turbine

Abstract: In a method of operating a combined cycle system including a gas turbine, a steam turbine and a multi-pressure heat recovery steam generator, an improvement includes supplying gas turbine cooling duty steam from a high pressure section of the steam turbine and from an intermediate pressure evaporator in the multi-pressure heat recovery steam generator, conducting the gas turbine cooling duty steam to the gas turbine for cooling hot gas turbine parts, and then returning the gas turbine cooling duty steam to an intermediate pressure section of the steam turbine. In a start-up procedure, steam is extracted from a first pass of a high pressure superheater in the multi-pressure heat recovery steam generator, mixed with steam discharged from the high pressure superheater and then supplied to the gas turbine cooling duty system. In this same start-up procedure, the gas turbine cooling duty steam is returned to the system condenser, bypassing the intermediate pressure section of the steam turbine. Related apparatus is also disclosed.

Steam-turbine power plant and steam turbine

Abstract: A steam turbine in which principal components to be exposed to high temperatures are all made of ferritic steel, whereby the temperatures of main steam and reheat steam can be increased to 610 - 660 (°C). The rotor shaft (23 in Fig. 1) of the steam turbine is made of ferritic forged steel whose 100,000-hour creep rupture strength is at least 15 (kg/mm2) at the service temperature of the rotor shaft. Likewise, the casing (18) is made of ferritic cast steel whose 100,000-hour creep rupture strength is at least 10 (kg/mm2). The steam turbine of high thermal efficiency can be applied to a steam- turbine power plant.

Temperature-controlled water delivery system

Abstract: A combined safety shower and eyewash station utilizes steam to heat water in a heat exchanger. Cool water is combined with heated water from the water outlet of the heat exchanger by a temperature-regulated mixing valve. If the water at the water outlet of the heat exchanger becomes too hot, some of the water is fed to the steam inlet of the heat exchanger. This makes it easy for the mixing valve to regulate water temperature even though the shower uses water at a much higher rate than does the eyewash station. Steam is fed to the heat exchanger through a steam valve which is opened automatically when a demand for warm water is sensed by a pressure-drop flow sensor. An overtemperature responsive actuator overrides the demand sensor to shut off the steam. A steam trap at the inlet of the steam valve eliminates cold condensate so that the apparatus is able to deliver warm water substantially immediately upon demand.

Steam-Injected Gas Turbine Analysis: Steam Rates

Abstract: This paper presents an analysis of steam rates in steam-injected gas turbines (simple and reheat). In considering a gas turbine of this type, the steam-injection flow is separated from the main gas stream for analysis. Dalton`s and Avogadro`s laws of partial pressure and gas mixtures are applied. Results obtained provide for the accurate determination of heat input, gas expansion based on partial pressures, and heat-rejection steam-enthalpy points.

Method and apparatus for warming a steam turbine in a combined cycle power plant

Abstract: A combined cycle gas turbine power plant uses compressed air bleed from the gas turbine compressor discharge air as a source of warming air for the steam turbine at start-up by incorporating a bypass line from the compressor discharge to the steam chest. During this time period, the steam produced by the heat recovery steam generator is dumped to the condenser. After warming the steam turbine, the compressed air is directed to the heat recovery steam generator for discharge to atmosphere. Once the heat recovery steam generator is capable of generating steam at sufficient temperature and pressure for introduction into the steam turbine, a control valve in the bypass line is closed, thereby eliminating the warming air, and a control valve in the steam supply line from the heat recovery steam generator to the steam turbine is opened so that the steam turbine can be brought on line.

S cycle electric power system

Abstract: The S cycle electric power system embodies a separation condensation unit, a Rankine cycle and the S cycle including coal gasification. Coal, oxygen and steam are converted into high temperature and pressure fuel gas in a coal gasifier. The fuel gas is first utilized to heat recycled carbon dioxide and steam, then to drive a compressor turbine group to produce power. In a main gas turbine group, the fuel gas is burned in the recycled carbon dioxide. Three main turbines are operated at three different pressure levels. The exhaust of the third turbine is employed to heat the recycled carbon dioxide from a 6-stage compressor with intercooling, and to produce steam. Part of the steam goes to coal gasification. The rest of the steam generates power by expansion in a steam turbine. An integrated separation condensation unit produces pure oxygen on site, and captures carbon dioxide formed in fuel combustion. The system has high energy efficiency and zero pollutant emissions including carbon dioxide.

Coal burner combined power plant having a fuel reformer located within the coal furnace

Abstract: A coal burner combined power plant includes a gas turbine for burning coal in a furnace under the pressure and uses produced gas. A steam turbine is combined with an exhaust gas boiler using exhaust gas from the gas turbine. Another fuel is burned at an inlet of the gas turbine for allowing the temperature at the inlet of the gas turbine to rise. A fuel reformer reforms the other fuel and is located within the furnace.

Thermodynamic analysis of a coal-based combined cycle power plant

Abstract: A thermodynamic analysis of a combined cycle power plant using pressurized circulating fluidized beds for partial gasification and combustion of coal has been made on the basis of both first law and second law. The Redlich-Kwong equation of state is used for evaluation of properties of air at high pressures in the topping gas turbine plant. A dual pressure steam cycle is considered in the bottoming plant for reducing irreversibility in heat transfer from gas to water and steam. The effects of pressure ratio and peak cycle temperature ratio of the gas cycle and the lower saturation pressure of the steam cycle on the overal performance of the combined plant have been evaluated.

Seawater desalting device

Abstract: PROBLEM TO BE SOLVED: To desalt seawater by utilizing waste heat of a solar power generating device and to obtain power and fresh water at low cost even in a place, such as an isolated island where energy and water resources are scare. SOLUTION: Seawater pumped up by a seawater pump 5 is used as a waste heat recovering refrigerant for a solar power generating device, and is introduced into a heat exchanger for heat radiation 6 in which it exchanges heat with gas heated by solar heat in a condensing type heat receiver 1 and discharged from a gas turbine 2 of the solar power generating device, and is heated and evaporated. This evaporated steam is condensed in a condenser 7 to obtain fresh water.

Method and a system for accurately calculating pwr power from excore detector currents corrected for changes in 3-d power distribution and coolant density

Abstract: Excore detector measurements are used to generate on-line absolute reactor power in a pressurized water reactor (PWR) by calibrating detector current measurements to the reactor thermal power calculation made at a base time early in reactor cycle while the thermal reactor power measurement is still accurate. Measurements are also made at the base time of the three-dimensional core power distribution and the core inlet temperature. Present core power measurements are then made by measuring the present excore detector current, the most recent three-dimensional core power distribution and the present core inlet temperature. The present core power is then calculated as the ratio of the present detector current to the detector current at the base time multiplied by the reactor thermal power measurement at the base time. The product is then corrected for changes in three-dimensional power distribution as a function of the difference between the three-dimensional core power distribution at the base time and a most recent three-dimensional core power distribution. The product is also corrected for changes in core inlet temperature by a correction factor which is an exponential term in which the difference between the present core inlet temperature and the core inlet temperature at the base time is multiplied by a constant. This constant is empirically determined at two different temperatures, preferably during start-up.

Power plant topping cycle repowering

Abstract: Traditionally, power plant repowering is defined as the replacement of a worn-out steam generator with a new steam generator meeting the original steam requirements so that the remaining life in the steam turbine and balance-of-plant equipment can be used. Because it is also possible to upgrade older power plants with a variety of technology improvements that have become available since the original plants were built, a number of power plant upgrade technologies are now included in the definition of power plant repowering. Another change, besides equipment wear-and-tear and technology advancements, that has overtaken older power plants is more restrictive environmental regulations. Repowering technologies are available for economically meeting more stringent mission standards while concomitantly improving power plant performance. Technology upgrades can be used to achieve a variety of improvements over the original power plant. These include low-cost capacity increases, lower heat rates, improved fuel flexibility, greater plant operating flexibility, reduced O and M costs, increased availability and reliability, along with achieving and maintaining environmental compliance. A figure provides ranges for the value of the savings available from the many identified repowering technologies. In many cases it will be necessary to identify many distinct savings to fully capture the benefits ofmore » a competitive repowering opportunity. The various repowering technologies will each have their own potential benefits; the size of these benefits will also depend on the existing site, power plant equipment, and competitive business environment.« less

Method for utilizing acidic geothermal fluid for generating power in a rankine cycle power plant

Abstract: A method for utilizing acidic geothermal fluid (e.g., fluid having a pH of less than about 3.5) containing non-condensable gases in a geothermal power plant includes separating the geothermal fluid into steam and brine, applying the steam to a device from which power and steam condensate is produced. Such device can be a back-pressure steam turbine whose exhaust can be cooled by organic fluid to produce organic vapor that is expanded in an organic vapor turbine. Alternatively, the steam can be applied to the steam-side of an indirect contact heat exchanger containing a liquid organic working fluid for producing steam condensate and vaporized working fluid. In such case, the steam condensate produced by the heat exchanger is less acidic than the brine. The vaporized working fluid is expanded in an organic vapor turbine for producing electricity and expanded working fluid, and the expanded working fluid is condensed for producing condensed organic fluid which is preheated and supplied to the heat exchanger. Preheating of the condensed organic fluid is achieved using heat contained in both the steam condensate and brine which are cooled thereby. The dilution of the brine by the steam condensate causes the concentration of acids, e.g., hydrochloric acid, and salts in the brine, to return to less than their original values in the geothermal brine.

Numerical Modeling of Power Station Steam Condensers - Part 1: Convergence Behavior of a Finite-Volume Model.

Abstract: Computer simulation models of the flow and heat transfer in power station steam condensers have the potential for becoming important design tools These computer models may be used to improve existing designs by identifying ways to improve condenser vacuum and to minimize flow-induced tube vibration To date, such models seem to have experienced convergence problems, or require information to be specified that would not normally be known a priori This article describes components of a finite-volume model that is thought to be typical of those used by several investigators The convergence characteristics of this model are described when it is applied to two problems This model, and its convergence characteristics, provide a baseline against which improvements can be measured The impact of various improvements to this model are reported in a companion article

Energy supply system utilizing gas and steam turbines

Abstract: An energy supply system includes a gas turbine which drives an air compressor. Heat generated by adiabatic compression of air in the air compressor is recovered by a heat exchanger. The air from which the heat has been recovered is used to operate an air turbine. The air turbine drives a generator. Adiabatic expansion of the air in the air turbine produces air at low temperature. Thermal energy at low temperature of the air is recovered by another heat exchanger. The waste heat from the gas turbine is recovered by a boiler system of a heat recovery type.

Direct‐contact steam condensation with simultaneous noncondensable gas absorption

Abstract: Experimental results are reported on simultaneous heat transfer and gas dissolution during the direct-contact condensation of steam on water in the presence of CO[sub 2]. A column filled with structured packing is used as condenser with the water in counterflow with the steam/CO[sub 2] mixture. The region along the column where the bulk of condensation takes place is controllable by suitable choice of the steam/water ratio. Measured local heat-transfer coefficients change by roughly an order of magnitude from the bottom to the top of the column. The extent of CO[sub 2] dissolution in the water/condensate under most conditions is unexpectedly high and depends strongly on the exit liquid temperature. A driving force based on the interfacial CO[sub 2] concentration, not the overall concentration difference used in conventional absorption operations, is suggested as more appropriate to describe the phenomenon. The data are complemented with preliminary results from a computational model based on the integration along the column of local heat and mass-transfer rates. Direct-contact condensation of steam on water in the presence of noncondensable gases is encountered in various applications such as power-plant condensers, ocean thermal energy conversion systems, and geothermal installations. It is also relevant to the nuclear industry inmore » certain safety evaluation scenarios. The application motivating this study is the separation of noncondensable gases from high pressure geothermal steam upstream of the turbines.« less

A method of operating a combined cycle steam and gas turbine power generating system with constant settable droop

Abstract: A method of operating a combined-cycle gas and steam turbine power generating system on a single shaft (16) uses as a feedback to the speed control or governor a signal (22) representing the total power output of the generator less the total output of the steam turbine (12), which is then correlated with the error signal beetween the actual and reference speeds to alter the fuel flow to the gas turbine. By compensating the measured generator output by subtracting a value (24) representative of the steam turbine output so that the compensated signal (26) represents the contribution of only the gas turbine (10) to the generator output, a constant settable droop speed control system may be used in a single-shaft combined-cycle steam turbine and the gas turbine system to compensate for variable heating fuel value and/or changing combustion efficiency in dry low NOx combustion systems.

Method of operating a waste-to-energy plant having a waste boiler and gas turbine cycle

Abstract: A waste-to-energy plant which is designed and operated to burn municipal waste (in 2) combines a high pressure steam turbine/generator cycle and a combustion turbine/generator cycle, wherein the exit gas from the combustion turbine (6) is utilized to superheat (in 4) high pressure steam (from 2) prior to entering the steam turbine (8). The combination of the combustion turbine/generator cycle with the steam turbine/generator cycle enables operation of the waste-to-energy plant at high pressure and high temperature resulting in greatly increased thermal cycle efficiency while eliminating superheater surfaces from the waste heat recovery boiler, thereby greatly reducing corrosion problems associated with waste heat recovery boilers.

Particle-induced x-ray emission (pixe) analysis of coal fly ash

Abstract: Analysis of trace element in coal fly ash has been brought to the attention of the general public in recent years primarily as it concerns in pollution problem with coal-fired power plants. Indian coal used in the thermal power plants has quite high content of ash (upto 55%). Therefore, in order to assess the environmental impact of the coal fuel cycle, coal fly ash samples from Captive Power Plant (CPP) of National Aluminium Company (NALCO) in Angul industrial area have been analysed for heavy elements by PIXE technique. Sample preparation procedures, experimental setup and spectrum analysis are discussed.

Computerized Analysis of Low-NO x Coal-fired Utility Boilers

Abstract: Mathematical modelling and simulation can be used to assess the effect of modifications of the combustion process and pollutant formation. In this paper two pulverized coal combustion plants are considered. The first plant is a bituminous coal-fired furnace with eight swirl burners and a thermal power of 490 M W. In order to reduce NO x -formation, the furnace system was modified using a different burner design and a modified burnout air arrangement for realizing the staging of combustion air. Both cases were investigated. The second plant is a brown coal-fired furnace with an electric power of 150 MW. The goal was to reduce CO-emissions and to improve the burnout of the coal. For a more flexible discretization of the domain a method was developed which allows that each burner can be discretized by an independent grid system. Using this method, details of the burner geometry can be considered and the governing processes of pollutant formation in the near-burner zone may be described in more detail.

Steam raising apparatus for performance enhanced gas turbine powerplants

Abstract: A steam raising apparatus for a gas turbine driven powerplant in which fuel and water are introduced into a heat exchanger at multiple pressures and steam/fuel mixtures are removed from the heat exchanger at multiple pressures, some of which are above the desired pressure for combustion and some of which are below. The higher pressure flows are reduced in pressure by using them to drive a steam turbine coupled to a steam compressor, and the lower pressure flows are increased in pressure by means of the compressor. The resultant flows are then be combined into a single flow at the required pressure and routed to the combustor. Alternatively, multiple steam jet ejectors forming a thermocompressor assembly are used instead of the steam turbine/steam compressor assembly.