The part-load performance of a gas turbine engine with two turbines working in parallel (original) (raw)
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As renewables are progressively displacing thermal plants in the power generation scene worldwide, the vocation of stationary Gas Turbines (GT) is deeply evolving. In this irreversible move GT plants are called upon to become cycling units with increasingly variable load profiles. This is dictated by the need to compensate for the fluctuations of renewable energy sources and secure the spinning reserve that is indispensable for the stability of the grids. This new scenario creates a serious challenge for gas turbine designers and operators in terms of investment policy, plant management and equipment lifetime. Indeed, operating a gas turbine at part, variable load requires reducing its firing temperature and possibly its air flow. While part load operation entails efficiency losses with respect to the full load mode, load variations cause maintenance penalties due the premature component ageing tied namely with thermal and low cycle fatigue effects on machine materials. As far as efficiency is concerned, an exergy analysis of a contemporary, air-based Brayton cycle is useful for quantifying and comparing the losses incurred by the various engine components. Such study reveals the high sensitivity of compressor efficiency to load decreases. Among possible countermeasures , heating the air at the compressor intake represents a simple mitigation measure, as it enables reducing the air flow rate while preserving to some extent the efficiency of the compressor and consequently GT efficiency.
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Performance analysis of a steam turbine power plant at part load conditions
Power consumption highly increases which is related with the growing of the industrial plants and daily using. Increasing power demand can be supplied with building up more efficient plants or optimized old power plants. One of the most important items of a power plant is steam turbine which is designed according to defined parameters (inlet pressure and temperature, flow rates, outlet pressure and power) which also effect the dimensions and performance of the turbine. Turbine loses and irreversibilities are minimum and so efficiencies and power generation are maximum at design conditions. However, power plants always have to operate at off-design or part-load conditions because of the changing of power demands and drop outs of the turbines and other items of the plants. In this study, it is aimed to analyses the isentropic efficiency of a high pressure steam turbine and thermal efficiency of power plant at different load conditions. Analyses showed that both steam turbines and power plant performance were reduced when the power plant operates at partial load conditions. INTRODUCTION Power consumption highly increases which is related with the growing of the industrial plants and daily using. Increasing power demand can be supplied with building up more efficient plants or optimized old power plants. The thermal efficiency depends on the all equipment (turbines, boilers, pump, etc.) performance so how the equipment are efficient thermal efficiency and cost are optimum. The most important items of a power plant are steam or gas turbines therefore their design and operating conditions are very important. Steam turbine design is based on some characteristic features such as inlet pressure and temperature, flow rate, outlet pressure etc. and turbine geometry, dimensions and performance are defined with this characteristic features. Turbine loses and irreversibilities are minimum and performance and power generation are maximum at design conditions. However, a steam turbine does not always operate at design conditions because of changing of power demand and turbine loses and this means that it always operates lower efficiency. Estimating and defining of characteristics of steam turbines at off-design conditions have been studied since 1900 and today the studies are going on more different variables and modern tools.
Energy, 2016
A small scale gas turbine jet engine is analyzed in this study. To understand the performance of the jet engine, experiments are conducted at four different load types (idle, part load one, part load two and full load). According to the load types, the energy and exergy flows of the engine components and the overall jet engine are investigated. Parameters such as specific fuel consumption, fuel exergy depletion, relative exergy consumption and exergetic improvement potential rate are studied to compare the effects of four load types. Exergy efficiencies and exergy destructions are calculated to explain the thermodynamic inefficiencies. The effect of the load type on the exergy efficiency is analyzed for the components and jet engine itself. At the idle and the part load one cases, the maximum exergy efficiencies took place in the gas turbine as 67.8% and 79.4% respectively. For the part load two and the full load cases, the maximum exergy efficiencies are calculated in the combustion chamber as 81% and 80.6% respectively. The maximum exergy destructions took place in the combustion chamber for all of the load types. They were found to be 35 kW, 40.3 kW, 36.6 kW and 47.9 kW.
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Applied Thermal Engineering, 2004
Recent advances in gas turbine development have led to wider usage of combined power plant for electrical power generation, and made it possible to reach a thermal efficiency of 55-60%. This was a result of introducing higher turbine inlet temperature (TIT) and other factors. However, this temperature is restricted by the metallurgical limit of turbine blades of about 800°C. Thus, need arises to design efficient cooling systems to cool the turbine components subjected to such high temperatures.