Investigation of the Performance of a Three Stage Combined Power Cycle for Electric Power Plants

2019 ◽  
Author(s):  
Pereddy Nageswara Reddy ◽  
J. S. Rao
Keyword(s):  
Power Plant ◽  
Electric Power ◽  
Steam Turbine ◽  
Gas Turbine ◽  
Pressure Ratio ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Brayton Cycle ◽  
Atmospheric Air ◽  
Power Cycle

Abstract A three stage combined power cycle with a Brayton cycle as the topping cycle, a Rankine cycle as the middling cycle and an Organic Rankine Cycle (ORC) as the bottoming cycle is proposed in the present investigation. A two-stage Gas Turbine Power Plant (GTPP) with inter-cooling, reheating and regeneration based on the Brayton cycle, a single-stage Steam Turbine Power Plant (STPP) based on the Rankine cycle, and a two-stage ORC power plant with reheating based on ORC with atmospheric air as the coolant is considered in the present study. This arrangement enables the proposed plant to utilize the waste heat to the maximum extent possible and convert it into electric power. As the plant can now operate at low sink temperatures depending on atmospheric air, the efficiency of the combined cycle power plant increases dramatically. Further, Steam Turbine Exhaust Pressure (STEP) is positive resulting in smaller size units and a lower installation cost. A simulation code is developed in MATLAB to investigate the performance of a three stage combined power cycle at different source and sink temperatures with varying pressure in heat recovery steam boiler and condenser-boiler. Performance results are plotted with Gas Turbine Inlet Temperature (GTIT) of 1200 to 1500 °C, Coolant Air Temperature (CAT) of −15 to +25 °C, and pressure ratio of GTPP as 6.25, 9.0 and 12.25 for different organic substances and NH3 as working fluids in the bottoming ORC. Simulation results show that the efficiency of the three stage combined power cycle will go up to 64 to 69% depending on the pressure ratio of GTPP, GTIT, and CAT. It is also observed that the variation in the efficiency of the three stage combined power cycle is small with respect to the type of working fluid used in the ORC. Among the organic working fluids R134a, R12, R22, and R123, R134a gives a higher combined cycle efficiency.

Integration of a Pressurized-Air Solar Receiver Array to a Gas Turbine Power Cycle for Solar Tower Applications

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Peter Poživil ◽  
Aldo Steinfeld
Keyword(s):  
Gas Turbine ◽  
Pressure Ratio ◽  
Rankine Cycle ◽  
Power Input ◽  
Combined Cycle ◽  
Operating Conditions ◽  
Brayton Cycle ◽  
Power Cycle ◽  
Receiver Array ◽  
Solar Receiver

The thermal performance of an array of pressurized-air solar receiver modules integrated to a gas turbine power cycle is analyzed for a simple Brayton cycle (BC), recuperated Brayton cycle (RC), and combined Brayton–Rankine cycle (CC). While the solar receiver's solar-to-heat efficiency decreases at higher operating temperatures and pressures, the opposite is true for the power cycle's heat-to-work efficiency. The optimal operating conditions are achieved with a preheat stage for a solar receiver outlet air temperature of 1300 °C and an air cycle pressure ratio of 9, yielding a peak solar-to-electricity efficiency—defined as the ratio of the net cycle work output divided by the solar radiative power input through the receiver's aperture—of 39.3% for the combined cycle configuration.

Repowering: An Option for Refurbishment of Old Thermal Power Plants in Latin-American Countries

2010 ◽  
Author(s):  
Washington Orlando Irrazabal Bohorquez ◽  
Joa˜o Roberto Barbosa ◽  
Luiz Augusto Horta Nogueira ◽  
Electo E. Silva Lora
Keyword(s):  
Power Plant ◽  
Natural Gas ◽  
Steam Turbine ◽  
Gas Turbine ◽  
Power Plants ◽  
Thermal Power ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Fuel Oil ◽  
Thermal Power Plants

The operational rules for the electricity markets in Latin America are changing at the same time that the electricity power plants are being subjected to stronger environmental restrictions, fierce competition and free market rules. This is forcing the conventional power plants owners to evaluate the operation of their power plants. Those thermal power plants were built between the 1960’s and the 1990’s. They are old and inefficient, therefore generating expensive electricity and polluting the environment. This study presents the repowering of thermal power plants based on the analysis of three basic concepts: the thermal configuration of the different technological solutions, the costs of the generated electricity and the environmental impact produced by the decrease of the pollutants generated during the electricity production. The case study for the present paper is an Ecuadorian 73 MWe power output steam power plant erected at the end of the 1970’s and has been operating continuously for over 30 years. Six repowering options are studied, focusing the increase of the installed capacity and thermal efficiency on the baseline case. Numerical simulations the seven thermal power plants are evaluated as follows: A. Modified Rankine cycle (73 MWe) with superheating and regeneration, one conventional boiler burning fuel oil and one old steam turbine. B. Fully-fired combined cycle (240 MWe) with two gas turbines burning natural gas, one recuperative boiler and one old steam turbine. C. Fully-fired combined cycle (235 MWe) with one gas turbine burning natural gas, one recuperative boiler and one old steam turbine. D. Fully-fired combined cycle (242 MWe) with one gas turbine burning natural gas, one recuperative boiler and one old steam turbine. The gas turbine has water injection in the combustion chamber. E. Fully-fired combined cycle (242 MWe) with one gas turbine burning natural gas, one recuperative boiler with supplementary burners and one old steam turbine. The gas turbine has steam injection in the combustion chamber. F. Hybrid combined cycle (235 MWe) with one gas turbine burning natural gas, one recuperative boiler with supplementary burners, one old steam boiler burning natural gas and one old steam turbine. G. Hybrid combined cycle (235 MWe) with one gas turbine burning diesel fuel, one recuperative boiler with supplementary burners, one old steam boiler burning fuel oil and one old steam turbine. All the repowering models show higher efficiency when compared with the Rankine cycle [2, 5]. The thermal cycle efficiency is improved from 28% to 50%. The generated electricity costs are reduced to about 50% when the old power plant is converted to a combined cycle one. When a Rankine cycle power plant burning fuel oil is modified to combined cycle burning natural gas, the CO2 specific emissions by kWh are reduced by about 40%. It is concluded that upgrading older thermal power plants is often a cost-effective method for increasing the power output, improving efficiency and reducing emissions [2, 7].

Flexible Combined Cycle Gas Turbine Power Plant Utilising Organic Rankine Cycle Technology

2016 ◽  
Author(s):  
Michael Welch ◽  
Nicola Rossetti
Keyword(s):  
Power Generation ◽  
Power Plant ◽  
Steam Turbine ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Exhaust Gas ◽  
Operational Flexibility

Historically gas turbine power plants have become more efficient and reduced the installed cost/MW by developing larger gas turbines and installing them in combined cycle configuration with a steam turbine. These large gas turbines have been designed to maintain high exhaust gas temperatures to maximise the power generation from the steam turbine and achieve the highest overall electrical efficiencies possible. However, in today’s electricity market, with more emphasis on decentralised power generation, especially in emerging nations, and increasing penetration of intermittent renewable power generation, this solution may not be flexible enough to meet operator demands. An alternative solution to using one or two large gas turbines in a large central combined cycle power plant is to design and install multiple smaller decentralised power plant, based on multiple gas turbines with individual outputs below 100MW, to provide the operational flexibility required and enable this smaller power plant to maintain a high efficiency and low emissions profile over a wide load range. This option helps maintain security of power supplies, as well as providing enhanced operational flexibility through the ability to turn turbines on and off as necessary to match the load demand. The smaller gas turbines though tend not to have been optimised for combined cycle operation, and their exhaust gas temperatures may not be sufficiently high, especially under part load conditions, to generate steam at the conditions needed to achieve a high overall electrical efficiency. ORC technology, thanks to the use of specific organic working fluids, permits efficient exploitation of low temperatures exhaust gas streams, as could be the case for smaller gas turbines, especially when working on poor quality fuels. This paper looks at how a decentralised power plant could be designed using Organic Rankine Cycle (ORC) in place of the conventional steam Rankine Cycle to maximise power generation efficiency and flexibility, while still offering a highly competitive installed cost. Combined cycle power generation utilising ORC technology offers a solution that also has environmental benefits in a water-constrained World. The paper also investigates the differences in plant performance for ORC designs utilising direct heating of the ORC working fluid compared to those using an intermediate thermal oil heating loop, and looks at the challenges involved in connecting multiple gas turbines to a single ORC turbo-generator to keep installed costs to a minimum.

scholarly journals Why We Need Nuclear Power Plants

2018 ◽  
Vol 2 (1) ◽  
Keyword(s):  
Power Plant ◽  
Natural Gas ◽  
Gas Turbine ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Brayton Cycle ◽  
Gen Iv

The major growth in the electricity production industry in the last 30 years has centered on the expansion of natural gas power plants based on gas turbine cycles. The most popular extension of the simple Brayton gas turbine has been the combined cycle power plant with the Air-Brayton cycle serving as the topping cycle and the Steam-Rankine cycle serving as the bottoming cycle for new generation of nuclear power plants that are known as GEN-IV. The Air-Brayton cycle is an open-air cycle and the Steam-Rankine cycle is a closed cycle. The air-Brayton cycle for a natural gas driven power plant must be an open cycle, where the air is drawn in from the environment and exhausted with the products of combustion to the environment. This technique is suggested as an innovative approach to GEN-IV nuclear power plants in form and type of Small Modular Reactors (SMRs). The hot exhaust from the AirBrayton cycle passes through a Heat Recovery Steam Generator (HSRG) prior to exhausting to the environment in a combined cycle. The HRSG serves the same purpose as a boiler for the conventional Steam-Rankine cycle [1].

The Combined Reheat Gas Turbine/Steam Turbine Cycle: Part I—A Critical Analysis of the Combined Reheat Gas Turbine/Steam Turbine Cycle

1980 ◽  
Vol 102 (1) ◽  
pp. 35-41 ◽  
Author(s):  
I. G. Rice
Keyword(s):  
Power Plant ◽  
Steam Turbine ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Critical Analysis ◽  
Pressure Ratio ◽  
Rankine Cycle ◽  
Steam Turbines ◽  
Gas Generator ◽  
World Energy

The reheat gas turbine cycle combined with the steam turbine Rankine cycle holds new promise of appreciably increasing power plant thermal efficiency. Apparently the cycle has been overlooked and thus neglected through the years. Research and development is being directed towards other gas turbine areas because of the world energy crunch; and in order to focus needed technical attention to the reheat cycle, this paper is presented, using logic and practical background of heat recovery boilers, steam turbines, gas turbines and the process industry. A critical analysis is presented establishing parameters of efficiency, cycle pressure ratio, firing temperature and output. Using the data developed, an analysis of an actual gas generator, the second generation LM5000, is applied with unique approaches to show that an overall 50 percent efficiency power plant can be developed using today’s known techniques and established base-load firing temperatures.

Steam Turbine Driving Compressor for Gas-Steam Combined Cycle Power Plant

2009 ◽  
Author(s):  
Wancai Liu ◽  
Hui Zhang
Keyword(s):  
Power Generation ◽  
Power Plant ◽  
Steam Turbine ◽  
Gas Turbine ◽  
Combined Cycle ◽  
Thermodynamic Process ◽  
Combined Cycle Power Plant ◽  
Steam Cycle

Gas turbine is widely applied in power-generation field, especially combined gas-steam cycle. In this paper, the new scheme of steam turbine driving compressor is investigated aiming at the gas-steam combined cycle power plant. Under calculating the thermodynamic process, the new scheme is compared with the scheme of conventional gas-steam combined cycle, pointing its main merits and shortcomings. At the same time, two improved schemes of steam turbine driving compressor are discussed.

scholarly journals Operation and Test of a New 37 MW Gas Turbine Package Power Plant

1980 ◽  
Author(s):  
J. Jermanok ◽  
R. E. Keith ◽  
E. F. Backhaus
Keyword(s):  
Power Generation ◽  
Power Plant ◽  
Electric Power ◽  
Gas Turbine ◽  
Combined Cycle ◽  
Simple Cycle ◽  
Initial Operation ◽  
Design Features ◽  
Electric Power Generation ◽  
Gas Turbine Power Plant

A new 37-MW, single-shaft gas turbine power plant has been designed for electric power generation, for use in either simple-cycle or combined-cycle applications. This paper describes the design features, instrumentation, installation, test, and initial operation.

The Elephant in the Room–Gas Turbine Power

2010 ◽  
Vol 132 (12) ◽  
pp. 57-57
Author(s):  
Lee S. Langston
Keyword(s):  
Power Plant ◽  
Electric Power ◽  
Gas Turbine ◽  
Power Plants ◽  
Electrical Power ◽  
Electric Power Industry ◽  
Hydrocarbon Fuel ◽  
Combined Cycle ◽  
Electrical Generator ◽  
Gas Turbine Exhaust

This article presents an overview of gas turbine combined cycle (CCGT) power plants. Modern CCGT power plants are producing electric power as high as half a gigawatt with thermal efficiencies approaching the 60% mark. In a CCGT power plant, the gas turbine is the key player, driving an electrical generator. Heat from the hot gas turbine exhaust is recovered in a heat recovery steam generator, to generate steam, which drives a steam turbine to generate more electrical power. Thus, it is a combined power plant burning one unit of fuel to supply two sources of electrical power. Most of these CCGT plants burn natural gas, which has the lowest carbon content of any other hydrocarbon fuel. Their near 60% thermal efficiencies lower fuel costs by almost half compared to other gas-fired power plants. Their installed capital cost is the lowest in the electric power industry. Moreover, environmental permits, necessary for new plant construction, are much easier to obtain for CCGT power plants.

scholarly journals A Useful Equation for Gas Turbine Design

2018 ◽  
Vol 140 (03) ◽  
pp. S52-S53
Author(s):  
Lee S. Langston
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Gas Turbine ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Brayton Cycle ◽  
Nonlinear Superposition ◽  
Transient Conditions ◽  
One Dimensional ◽  
Turbine Design

This article presents three different gas turbine phenomena and design cases. The sketch in the article shows a schematic of a combined cycle powerplant consisting of a Brayton cycle (gas turbine) whose exhaust provides energy to a Rankine cycle (steam turbine). Frequently, one can use simple but exact one-dimensional (1D) heat conduction solutions to estimate the heat loss or gain of gas turbine components under transient conditions. These easy-to-use solutions are found in most undergraduate heat transfer texts. The article suggests that those three widely different gas turbine phenomena and design cases all have the simple, nonlinear superposition form.

Impact of Inlet Fogging on the Performance of Steam Injected Cooled Gas Turbine Based Combined Cycle Power Plant

2017 ◽  
Author(s):  
Anoop Kumar Shukla ◽  
Onkar Singh
Keyword(s):  
Power Plant ◽  
Gas Turbine ◽  
Film Cooling ◽  
Pressure Ratio ◽  
Steam Injection ◽  
Combined Cycle ◽  
Specific Power ◽  
Temperature Cycle ◽  
Inlet Temperature ◽  
Combined Cycle Power Plant

Gas/steam combined cycle power plants are extensively used for power generation across the world. Today’s power plant operators are persistently requesting enhancement in performance. As a result, the rigour of thermodynamic design and optimization has grown tremendously. To enhance the gas turbine thermal efficiency and specific power output, the research and development work has centered on improving firing temperature, cycle pressure ratio, adopting improved component design, cooling and combustion technologies, and advanced materials and employing integrated system (e.g. combined cycles, intercooling, recuperation, reheat, chemical recuperation). In this paper a study is conducted for combining three systems namely inlet fogging, steam injection in combustor, and film cooling of gas turbine blade for performance enhancement of gas/steam combined cycle power plant. The evaluation of the integrated effect of inlet fogging, steam injection and film cooling on the gas turbine cycle performance is undertaken here. Study involves thermodynamic modeling of gas/steam combined cycle system based on the first law of thermodynamics. The results obtained based on modeling have been presented and analyzed through graphical depiction of variations in efficiency, specific work output, cycle pressure ratio, inlet air temperature & density variation, turbine inlet temperature, specific fuel consumption etc.

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