Showing papers on "Turbine published in 1997"

A variable speed wind turbine power control

Abstract: To optimize the power in a wind turbine, the speed of the turbine should be able to vary with the wind speed. A simple control scheme is proposed that will allow an induction motor to run a turbine at its maximum power coefficient. The control uses a standard V/Hz converter and controls the frequency to achieve the desired power at a given turbine speed.

Process for converting gas to liquids

Abstract: A process for converting a hydrocarbon gas (e.g. natural gas) to syngas which, in turn, is converted into a liquid hydrocarbon product wherein a substantial amount of the heat generated in the process is recovered for use in generating steam needed in the process or for conversion into mechanical energy. Further, tail gas produced by the process is used to fuel the gas turbine which, in turn, is used to power the compressor needed for compressing the air used in the process. By using tail gas to fuel the gas turbine, less of the compressed combustion-air is needed to cool the combustion gases in the turbine and, instead, can be used to provide a portion of the process-air required in the process; thereby possibly saving up to 20 to 30 percent of the horsepower otherwise needed to compress the required volume of the process-air.

Dynamic response of a stand-alone wind energy conversion system with battery energy storage to a wind gust

Abstract: A mathematical model of each element of a stand-alone wind energy conversion system is developed. The model variables are expressed in the d-q rotor reference frame. The wind turbine was considered as the only source of power in this study. Using this model, the system response to a recorded wind gust is investigated by calculating the generator current, the rectifier current, the load current, the battery charging current and the battery voltage. The calculated results are then verified by comparing them with actual values obtained from a data acquisition system. Good agreement was achieved between the experimental and analytical results.

Macro power from micro machinery

Abstract: S. D. Senturia Typical turbine engines generate about 100 MW of power. Scaled down to millimeter size, a turbine could generate tens of watts, enough for powering micromachinery. In their Perspective, Epstein and Senturia review past progress and recent developments in micromotor engineering.

Micro-heat engines, gas turbines, and rocket engines -the mit microengine project-

Abstract: This is a report on work in progress on microelectrical and mechanical systems (MEMS)-based gas turbine engines, turbogenerators, and rocket engines currently under development at MIT. Fabricated in large numbers in parallel using semiconductor manufacturing techniques, these engines are based on micro-high speed rotating machinery with the same power density as that achieved in their more familiar, full-sized brethren. The micro-gas turbine is a 1 cm diameter by 3 mm thick SiC heat engine designed to produce 10-20 W of electric power or 0.050.1 Nt of thrust while consuming under 10 grams/hr of H 2 . Later versions may produce up to 100 W using hydrocarbon fuels. A liquid fuel, bi-propellant rocket motor of similar size could develop over 3 lb of thrust. The rocket motor would be complete with turbopumps and control valves on the same chip. These devices may enable new concepts in propulsion, fluid control, and por table power generation.

Process and apparatus for achieving power augmentation in gas turbines via wet compression

Abstract: A power augmentation apparatus and process for effectively adding a mass flow of water to the working fluid acquired by the compressor of an industrial gas turbine, and especially for adding a mass flow of water to a fully-humidified working fluid for reducing the work of compression performed by the compressor and achieving a net augmentation of the power produced by the turbine, said apparatus and process preferably including the use of a spray rack group assembly having at least one spray rack water pipe and at least one spray rack water nozzle which assembly is ideally positioned a distance away from the compressor inlet. Water mass flow is added preferably in increments which correspond to the spray rack water pipes and associated nozzles. Monitoring of the temperature profile of fluid-cooled rotor blades in the turbine section with an optical pyrometer to detect clogging of cooling pathways in those rotor blades from impurities in the added water, monitoring of the working fluid's temperature in proximity to the gas turbine compressor inlet to guard against the possibility of icing, a deformation measurement device, and concurrent addition of heat and humidity, preferably steam, to the working fluid as a means to extend the utility of the process and apparatus to lower ambient air temperature operation are disclosed.

Effect of Squealer Tip on Rotor Heat Transfer and Efficiency

Abstract: Calculations were performed to simulate the tip flow and heat transfer on the GE-E 3 first-stage turbine, which represents a modern gas turbine blade geometry. Cases considered were a smooth tip, 2 percent recess, and 3 percent recess. In addition, a two-dimensional cavity problem was calculated. Good agreement with experimental results was obtained for the cavity calculations, demonstrating that the k-ω turbulence model used is capable of representing flows of the present type. In the rotor calculations, two dominant flow structures were shown to exist within the recess. Also areas of large heat transfer rate were identified on the blade tip and the mechanisms of heat transfer enhancement were discussed. No significant difference in adiabatic efficiency was observed for the three tip treatments investigated.

Power MEMS and Microengines

Abstract: MIT is developing a MEMS-based gas turbine generator. Based on high speed rotating machinery, this 1 cm diameter by 3 mm thick SiC heat engine is designed to produce 10-20 W of electric power while consuming 10 grams/hr of H/sub 2/. Later versions may produce up to 100 W using hydrocarbon fuels. The combustor is now operating and an 80 W micro-turbine has been fabricated and is being tested. This engine can be considered the first of a new class of MEMS device, power MEMS, which are heat engines operating at power densities similar to those of the best large scale devices made today.

Scavenger energy converter system its new applications and its control systems

Abstract: What has been invented is a series of scientific applications of the wideface energy converter device, be it in the form of a wideface solar heat receiver or a wideface fluid impeder device. The wider is the solar heat receiver, the more solar power is available for conversion. The wider is the sail of the boat, the more wind is available to push the boat. Wherefore, the wideface solar trap made up of multi-layer transparent roofs covering a heat insulated box is used to heat up a radiator tubings that contain water. The multilayer transparent roof, having spaces in between sheets, prevents solar heat from backing out hence the trap becomes hoter and hoter because the inner sheet is not in contact with the cold wind. This solar trap is now used to heat up radiator pipes of compressed air coming from a gas turbine engine and then returned back to the exhaust turbine of same engine. Applying the principle of the wind sail, the turbine blades of the compressor and the turbine blades of the exhaust turbine are made wideface as much as possible to produce maximum impedance against the expanding exhaust hot air and to produce maximum push upon the fresh air being compressed. This wideface fluid impeder is now expanded into an underwater platform from One Acre or much more and attached to floating hotels, large/small boats, and floating sea walls, to prevent oscillation by the surfs.

The energy conversion performance of several types of Wells turbine designs

Abstract: Several types of single-plane and multiplane Wells turbines are investigated and compared. The turbines’ aerodynamic losses and overall performances are presented and two successful methods of swirl energy recovery are studied in detail. Guide vanes were fitted to a monoplane turbine whereas the rotors of a biplane turbine were contra-rotated. A double-shaft biplane turbine was also tested. The contra-rotating turbine had an operational range which was similar to that of the monoplane turbine with guide vanes, achieved a similar peak efficiency, but performed better in the post-stall region and also was found to be able to accommodate a much higher pressure-flow ratio.

Annualized wind energy improvement using variable speeds

Abstract: To optimize the operation of a wind turbine, variable turbine speeds are desirable. To determine the advantages of a variable-speed turbine, the annualized energy production of the turbine needs to be considered. This is done by using a Rayleigh probability distribution to determine the number of hours of a particular wind speed which occur in a given year. This distribution is used with the aerodynamic power generated at a given average wind speed to determine the total energy generated during the year. The total energy for fixed- and variable-speed turbine control are compared. The variable-speed turbines show improved energy production over constant-speed systems.

Introduction to Semantics

Abstract: Introduction Composition and Quality Physical Properties and Process Conditions Measurement Concepts Orifice Flowmetre Ultrasonic Flowmetre Turbine Flowmetre Rotary Displacement Flowmetre Calculations Secondary and Tertiary Devices Electronic Gas Measurement Uncertainty Measurement System Design Orifice Flowmetre Design Ultrasonic Flowmetre Design Turbine Flowmetre Design Rotary Displacement Flowmetre Design Inspection, Testing, Verification, Calibration and Certification Index.

TBC experience in land based gas turbines

Abstract: This paper summarizes prior and on-going machine evaluations of thermal barrier coatings (TBC) for power generation, that is large industrial gas turbine applications. Rainbow testing of TBCs on turbine nozzles, shrouds, and buckets are described along with a test of combustor liners. General Electric Power Generation has conducted more than IS machine tests on TBC turbine nozzles with various coatings. TBC performance has been quite good, and additional testing, including TBCs on shrouds and buckets, is continuing. Included is a brief comparison of TBC requirements for power generation and aircraft turbines.

Method and system for wind turbine braking

Abstract: Stored rotational energy in an operating variable speed wind turbine is used to pitch blades and brake the wind turbine in the event of utility power grid failure. In one embodiment, a generator IGBT converter and the main power utility grid IGBT converter supply control and pitch servo power during turbine deceleration, and a ride-through capacitor on a DC emergency power supply bus and the main DC link capacitor provide additional energy storage. In another embodiment, a step-down DC/DC power converter adds to the intermediate DC link of the power conversion system with the secondary of the step down converter powering both the hub pitch controller and the wind turbine control system.

Characterization of Oscillations During Premix Gas Turbine Combustion

Abstract: The use of premix combustion in stationary gas turbines can produce very low levels of NO{sub x} emissions. This benefit is widely recognized, but turbine developers routinely encounter problems with combustion oscillations during the testing of new premix combustors. Because of the associated pressure fluctuations, combustion oscillations must be eliminated in a final combustor design. Eliminating these oscillations is often time-consuming and costly because there is no single approach to solve an oscillation problem. Previous investigations of combustion stability have focused on rocket applications, industrial furnaces, and some aeroengine gas turbines. Comparatively little published data is available for premixed combustion at conditions typical of an industrial gas turbine. In this paper, the authors report experimental observations of oscillations produced by a fuel nozzle typical of industrial gas turbines. Tests are conducted in a specially designed combustor capable of providing the acoustic feedback needed to study oscillations. Tests results are presented for pressures up to 10 atmospheres, theoretical considerations, it is expected that oscillations can be characterized by a nozzle reference velocity, with operating pressure playing a smaller role. This expectation is compared to observed data that shows both the benefits and limitations of characterizing the combustor oscillating behavior in termsmore » of a reference velocity rather than other engine operating parameters. This approach to characterizing oscillations is then used to evaluate how geometric changes to the fuel nozzle will affect the boundary between stable and oscillating combustion.« less

Method of power generation and load management with hybrid mode of operation of a combustion turbine derivative power plant

Abstract: The invention provides a stand-alone, hybrid combustion turbine derivative power generation system sized for the most efficient and cost-effective base load operation that is also capable of providing, using air storage techniques, short-duration peak power, which is approximately 200% of the base load rating, and short-duration intermediate load power over a whole a range of loads between a base load and a peak load. The peak/intermediate power is also delivered with the best practical efficiency possible. The hybrid system may employ a variety of combustion turbine thermal cycles, including a simple cycle combustion turbine plant, combustion turbine plants with intercooling, reheat, recuperation, steam injection and humidification, and combined cycle power plants.

Development of Blade Profiles for Low-Pressure Turbine Applications

Abstract: This paper describes a program of work, largely experimental, which was undertaken with the objective of developing an improved blade profile for the low-pressure turbine in aero-engine applications. Preliminary experiments were conducted using a novel technique. An existing cascade of datum blades was modified to enable the pressure distribution on the suction surface of one of the blades to be altered. Various means, such as shaped inserts, an adjustable flap at the trailing edge, and changing stagger were employed to change the geometry of the passage. These experiments provided boundary layer and lift data for a wide range of suction surface pressure distributions. The data were then used as a guide for the development of new blade profiles. The new blade profiles were then investigated in a low-speed cascade that included a set of moving bars upstream of the cascade of blades to simulate the effect of the incoming wakes from the previous blade row in a multistage turbine environment. Results are presented for two improved profiles that are compared with a datum representative of current practice. The experimental results include loss measurements by wake traverse, surface pressure distributions, and boundary layer measurements. The cascades were operated over a Reynoldsmore » number range from 0.7 {times} 10{sup 5} to 4.0 {times} 10{sup 5}. The first profile is a laminar flow design that was intended to improve the efficiency at the same loading as the datum. The other is a more highly loaded blade profile intended to permit a reduction in blade numbers. The more highly loaded profile is the most promising candidate for inclusion in future designs. It enables blade numbers to be reduced by 20%, without incurring any efficiency penalty. The results also indicate that unsteady effects must be taken into consideration when selecting a blade profile for the low-pressure turbine.« less

Operation method for integrated gasification combined cycle power generation system

Abstract: An integrated gasification combined cycle (IGCC) power generation system is operated at off-design conditions by introducing a supplemental fuel into the combustion turbine combustor to compensate for deviations from system design conditions. Such deviations include changes in ambient temperature and changes in the amount of extracted air required for the air separation system. The invention allows operation of the combustion turbine at or close to its maximum design power output and other components in the IGCC system at or close to their respective design points.

Gas-turbine condition monitoring using qualitative model-based diagnosis

Abstract: Gas turbines are critical to the operation of most industrial plants, and their associated maintenance costs can be extremely high. To reduce those costs and increase the availability of their gas turbines, plant operators have for many years relied on routine preventative maintenance-routinely checking and solving small problems before they grow into major ones. Recently, however, the power industry has moved sharply toward condition-based maintenance and monitoring. In this approach, intelligent computerized systems monitor gas turbines to establish maintenance needs based on the turbine's condition rather than on a fixed number of operating hours. By integrating several AI technologies-including qualitative model-based reasoning-the Tiger system significantly cuts costs and improves performance by using control-system information to perform condition monitoring for gas-turbine engines.

Detailed LDV Measurements for Visualization of the Flow Field Within a Stirred-Tank Reactor Equipped with a Rushton Turbine

Abstract: This paper presents the results obtained during investigations carried out on a multifunctional stirrer test rig which was established at the Institute of Fluid Mechanics at the University of Erlangen-Nuremberg. The objective of the research work was to generate a reliable data basis for the validation of numerical simulations of the flow field in stirred-tank reactors. For the measurements advanced laser Doppler velocimetry including full refractive index matching and automated data acquisition was used. The flow field in this case was induced by a Rushton turbine which was constructed of transparent material in order to gain access to the important flow field within the turbine for the first time. The presentation of the large-scale flow field conforms the results presented in previous publications, but a higher resolution was realized. Mean flow and turbulence characteristics are presented. The turbulence length scale L was found to be about half the blade height, which is in good agreement with the length scales reported by other authors for Rushton turbines. The total access to the flow field permitted the mean flow and the turbulence kinetic energy distribution within the stirrer element to be determined in detail.

Optical vortex tracking studies of a horizontal axis wind turbine in yaw using laser-sheet, flow visualisation

Abstract: Experimental studies have been conducted on a 0.9 m diameter, horizontal axis wind turbine (HAWT) placed in the open jet of a closed return wind tunnel. The turbine was tested in a three blade and a two blade configuration. The power coefficient of the turbine was measured and wake flow studies conducted for a range of yawed flows by tilting the rotor plane at various angles up to 30° to the incident wind direction. The motion of the shed vorticity was followed using laser-sheet flow visualisation with the overall wake deflection being measured. The results were compared with theoretical predictions and with studies conducted elsewhere.

Electrical system for turbine/alternator on common shaft

Abstract: An electrical system (1) for a turbine (10)/alternator (1) comprising a gas driven turbine (10) and permanent alternator (3) rotating on a common shaft comprised of an inverter circuit (17) connectable either to an ac output circuit or the stader winding of the alternator. A control circuit during a start up mode switches the inverter circuit to the stader winding of the alternator (3) and during a power out mode switches the inverter circuit (17) to the ac output circuit. Thus, during that start up mode, the alternator (11) functions as a motor to raise the speed of the turbine (10) to a safe ignition speed and in the power out mode the electrical system (1) outputs to the ac output circuit, k electrical power having a frequency unrelated to the rotational speed of the alternator (3).

Turbine engine with intercooler in bypass air passage

Abstract: A turbine engine (20) having bypass and core passages (30 and 40), a high pressure compressor (80) for compressing air in the core passage and an intercooler (120, 220) for cooling core air (42) in the core passage prior to discharge by the high pressure compressor. The intercooler includes a plurality of heat exchange elements (140) positioned in the bypass passage through which all or a portion of the core air is transported. Heat in the core air is transferred via the heat exchange elements to the relatively cool bypass air, thereby cooling the core air and heating the bypass air. The turbine engine may have a counterflow intercooler (120), a radial flow intercooler 220 or an intercooler of other configuration. The turbine engine may have a high pressure compressor with two sections (82 and 86), with core air transported to and from the intercooler between sections, or a single section high pressure compressor, with core air transported to and from the intercooler upstream of the high pressure compressor. The turbine engine may be of turbofan, turboshaft, turboprop or other design.

Integrated environmental control system

Abstract: An integrated environmental control system (10) is disclosed for providing conditioned supply air to loads such as a passenger cabin (56) of an aircraft. The system comprises at least two shafts (70, 78), each shaft having a fan (72, 80), compressor (74, 82), and turbine (76, 84) mechanically secured to the shaft (70, 78); common heat transfer components including primary (86) and secondary (88) heat exchangers, a reheater (90), and a condenser (92) with a water collector (130); fluid transfer lines that deliver the supply air separately through the compressors and turbines of each shaft (70, 78) and deliver the supply air in common through the common heat transfer components (86, 88, 90) to the load; and shutoff valves (96, 98) secured in fluid communication with each turbine (76, 84). Upon interruption in the the flow of cooled supply air out of a particular turbine (76, 84) secured to any of the shafts (70, 78), a shutoff valve (96, 98) shuts off transfer of the supply air to that particular turbine (76, 84) on that interrupted shaft (76, 78) and the remaining shafts and their respective fans (72, 80), compressors (74, 82), turbines (76, 84), and the common heat transfer components (86, 88, 90) continue to receive, condition and deliver the supply air to the load in a redundant operating mode.

Analysis of Hot Streak Effects on Turbine Rotor Heat Load

Abstract: The influence of inlet hot streak temperature distortion on turbine blade heat load was explored on a transonic axial flow turbine stage test article using a three-dimensional, multiblade row unsteady Euler code. The turbine geometry was the same as that used for a recently reported testing of hot streak influence. Emphasis was placed on elucidating the physical mechanisms by which hot streaks affect turbine durability. It was found that temperature distortion significantly increases both blade surface heat load nonuniformity and total blade heat load by as much as 10-30 percent (mainly on the pressure surface), and that the severity of this influence is a strong function of turbine geometry and flow conditions. Three physical mechanisms were identified that drive the heat load nonuniformity: buoyancy, wake convection (the Kerrebrock-Mikolajczak effect), and rotor-stator interactions. The latter can generate significant nonuniformity of the time-averaged relative frame rotor inlet temperature distribution. Dependence of these effects on turbine design variables was investigated to shed light on the design space, which minimizes the adverse effects of hot streaks.

Optimum performance of a regenerative Brayton thermal cycle

Abstract: The optimum performance of a regenerative Brayton cycle was analyzed. The model includes external and internal irreversibilities coming from four main sources: coupling to external heat reservoirs, turbine and compressor nonisentropic processes, pressure losses in the heater and the cooler, and the regenerator. In terms of the parameters accounting for each type of irreversibility, explicit numerical results are presented for the maximum efficiency, maximum power output, efficiency at maximum power output, power output at maximum efficiency, as well as for the pressure ratios required for maximum efficiency and maximum power. This analysis could provide a general theoretical tool for the optimal design and operation of real regenerative gas turbine power plants.

Implementation of wind turbine controllers

Abstract: Three of the important generic implementation issues encountered when developing controllers for pitch-regulated constant-speed wind turbines are considered; namely, accommodation of the strongly nonlinear rotor aerodynamics, automatic controller start-up-shut-down and accommodation of velocity and acceleration constraints within the actuator. Both direct linearization and feedback linearization methods for accommodating the nonlinear aerodynamics are investigated and compared. A widely employed technique for accommodating the nonlinear aerodynamics, originally developed on the basis of physical insight, is rigorously derived and extended to cater for all wind turbine configurations. A rigorous stability analysis of controller start-up is presented for the first time, and novel design guidelines are proposed which can significantly reduce the power transients at controller start-up. The relation to anti-wind-up is noted and several aspects of an existing wind-turbine controller start-up strategy are obser...

Membrane-augmented power generation

Abstract: A method for generating electric power from natural gas or the like that has a low Btu value and a high nitrogen content. The method involves a membrane separation step to remove a portion of the nitrogen from the gas. The upgraded gas is used as fuel for a turbine or other driver, which provides mechanical power to drive an electric power generator.

Closed loop air cooling system for combustion turbines

Abstract: Convective cooling of turbine hot parts using a closed loop system is disclosed. Preferably, the present invention is applied to cooling the hot parts of combustion turbine power plants, and the cooling provided permits an increase in the inlet temperature and the concomitant benefits of increased efficiency and output. In preferred embodiments, methods and apparatus are disclosed wherein air is removed from the combustion turbine compressor (22, 26) and delivered to passages internal to one or more of a combustor and turbine hot parts (100). The air cools the combustor and turbine hot parts via convection and heat is transferred through the surfaces of the combustor and turbine hot parts.