scholarly journals Stand-By Forced Draft Fan Versus Supercharging Gas Turbines for Pre-Combustion Air to Fully Fired Boilers in Combined Cycles

Author(s):  
J. O. Stephens

The purpose of this paper is to analyze the technical features of two different arrangements of supplying fresh air to the boilers in fully fired combined cycles for continuous boiler operation using a forced draft fan when the gas turbine is out of service. The first case is the conventional stand-by forced draft fan and the second is the supercharged fan arrangement. Two methods of separating the cycles are reviewed in detail: a) Cold start-up of system. b) While operating in the combined cycle mode, the gas turbine trips. c) While operating the boiler with fresh air firing the gas turbine is started for combined cycle operation. d) Normal shut down of the gas turbine. e) While operating in the combined cycle mode, the boiler trips. This paper presents the results of a study of a 350-MW combined cycle power plant for Alsands Energy Ltd., of Calgary, Alberta, Canada.

Author(s):  
Hsiao-Wei D. Chiang ◽  
Pai-Yi Wang ◽  
Hsin-Lung Li

With increasing demand for power and with shortages envisioned especially during the peak load times during the summer, there is a need to boost gas turbine power. In Taiwan, most of gas turbines operate with combined cycle for base load. Only a small portion of gas turbines operates with simple cycle for peak load. To prevent the electric shortage due to derating of power plants in hot days, the power augmentation strategies for combined cycles need to be studied in advance. As a solution, our objective is to add an overspray inlet fogging system into an existing gas turbine-based combined cycle power plant (CCPP) to study the effects. Simulation runs were made for adding an overspray inlet fogging system to the CCPP under various ambient conditions. The overspray percentage effects on the CCPP thermodynamic performance are also included in this paper. Results demonstrated that the CCPP net power augmentation depends on the percentage of overspray under site average ambient conditions. This paper also included CCPP performance parametric studies in order to propose overspray inlet fogging guidelines for combined cycle power augmentation.


Author(s):  
H. Arimura ◽  
Y. Iwasaki ◽  
S. Shiozaki ◽  
Y. Fukuizumi ◽  
C. Koeneke

This paper reports progress on Mitsubishi’s first commercial introductions of the M501G1 and M701G2 gas turbines for 60Hz and 50Hz, respectively. The first fire of the 50 Hz gas turbine took place late 2006 at Tokyo Electric Power Company’s (TEPCO’s) Kawasaki Thermal Power Station in Japan, and the 60 Hz unit in January 2007 at Portland General Electric’s Port Westward power plant at Portland, Oregon in the USA. The M501G1 and M701G2 gas turbines are upgrades to Mitsubishi G-series technology that was first introduced a decade ago utilizing steam from the bottoming cycle to cool the combustion liner, instead of compressor discharge air. In the abovementioned upgrades steam-cooling application is now extended to cool the turbine blade-rings thereby enabling better blade tip clearance control particularly during start-up transient conditions. It additionally benefits performance and reliability. Upgrades were also made to the row 1 and 2 vanes and row 1 blades utilizing advances in design technology since the original introduction of the G-series in 1997. Long-term reliability verification testing of the M501G1 gas turbine has been continuing at the Mitsubishi’s T-Point combined cycle power plant located at Takasago, Japan, since May 2003. This paper provides an update of that upgraded gas turbine with over three years of operating experience.


2011 ◽  
Vol 133 (05) ◽  
pp. 30-33 ◽  
Author(s):  
Lee S. Langston

This article explores the increasing use of natural gas in different turbine industries and in turn creating an efficient electrical system. All indications are that the aviation market will be good for gas turbine production as airlines and the military replace old equipment and expanding economies such as China and India increase their air travel. Gas turbines now account for some 22% of the electricity produced in the United States and 46% of the electricity generated in the United Kingdom. In spite of this market share, electrical power gas turbines have kept a much lower profile than competing technologies, such as coal-fired thermal plants and nuclear power. Gas turbines are also the primary device behind the modern combined power plant, about the most fuel-efficient technology we have. Mitsubishi Heavy Industries is developing a new J series gas turbine for the combined cycle power plant market that could achieve thermal efficiencies of 61%. The researchers believe that if wind turbines and gas turbines team up, they can create a cleaner, more efficient electrical power system.


Author(s):  
Edgar Vicente Torres González ◽  
Raúl Lugo Leyte ◽  
Martín Salazar Pereyra ◽  
Helen Denise Lugo Méndez ◽  
Miguel Toledo Velázquez ◽  
...  

In this paper is carried out a comparison between a gas turbine power plant and a combined cycle power plant through exergetic and environmental indices in order to determine performance and sustainability aspects of a gas turbine and combined cycle plant. First of all, an exergetic analysis of the gas turbine and the combined is carried out then the exergetic and environmental indices are calculated for the gas turbine (case A) and the combined cycle (case B). The exergetic indices are exergetic efficiency, waste exergy ratio, exergy destruction factor, recoverable exergy ratio, environmental effect factor and exergetic sustainability. Besides, the environmental indices are global warming, smog formation and acid rain indices. In the case A, the two gas turbines generate 278.4 MW; whereas 415.19 MW of electricity power is generated by the combined cycle (case B). The results show that exergetic sustainability index for cases A and B are 0.02888 and 0.1058 respectively. The steam turbine cycle improves the overall efficiency, as well as, the reviewed exergetic indexes. Besides, the environmental indices of the gas turbines (case A) are lower than the combined cycle environmental indices (case B), since the combustion gases are only generated in the combustion chamber.


Author(s):  
R. Chacartegui ◽  
D. Sa´nchez ◽  
F. Jime´nez-Espadafor ◽  
A. Mun˜oz ◽  
T. Sa´nchez

The development of high efficiency solar power plants based on gas turbine technology presents two problems, both of them directly associated with the solar power plant receiver design and the power plant size: lower turbine intake temperature and higher pressure drops in heat exchangers than in a conventional gas turbine. To partially solve these problems, different configurations of combined cycles composed of a closed cycle carbon dioxide gas turbine as topping cycle have been analyzed. The main advantage of the Brayton carbon dioxide cycle is its high net shaft work to expansion work ratio, in the range of 0.7–0.85 at supercritical compressor intake pressures, which is very close to that of the Rankine cycle. This feature will reduce the negative effects of pressure drops and will be also very interesting for cycles with moderate turbine inlet temperature (800–1000 K). Intercooling and reheat options are also considered. Furthermore, different working fluids have been analyzed for the bottoming cycle, seeking the best performance of the combined cycle in the ranges of temperatures considered.


Author(s):  
Weimar Mantilla ◽  
José García ◽  
Rafael Guédez ◽  
Alessandro Sorce

Abstract Under new scenarios with high shares of variable renewable electricity, combined cycle gas turbines (CCGT) are required to improve their flexibility, in terms of ramping capabilities and part-load efficiency, to help balance the power system. Simultaneously, liberalization of electricity markets and the complexity of its hourly price dynamics are affecting the CCGT profitability, leading the need for optimizing its operation. Among the different possibilities to enhance the power plant performance, an inlet air conditioning unit (ICU) offers the benefit of power augmentation and “minimum environmental load” (MEL) reduction by controlling the gas turbine inlet temperature using cold thermal energy storage and a heat pump. Consequently, an evaluation of a CCGT integrated with this inlet conditioning unit including a day-ahead optimized operation strategy was developed in this study. To establish the hourly dispatch of the power plant and the operation mode of the inlet conditioning unit to either cool down or heat up the gas turbine inlet air, a mixed-integer linear optimization (MILP) was formulated using MATLAB, aiming to maximize the operational profit of the plant within a 24-hours horizon. To assess the impact of the proposed unit operating under this dispatch strategy, historical data of electricity and natural gas prices, as well as meteorological data and CO2 emission allowances price, have been used to perform annual simulations of a reference power plant located in Turin, Italy. Furthermore, different equipment capacities and parameters have been investigated to identify trends of the power plant performance. Lastly, a sensitivity analysis on market conditions to test the control strategy response was also considered. Results indicate that the inlet conditioning unit, together with the dispatch optimization, increases the power plant’s operational profit by achieving a wider operational range, particularly important during peak and off-peak periods. For the specific case study, it is estimated that the net present value of the CCGT integrated with the ICU is 0.5% higher than the power plant without the unit. In terms of technical performance, results show that the unit reduces the minimum environmental load by approximately 1.34% and can increase the net power output by 0.17% annually.


Author(s):  
S. Can Gülen

Duct firing in the heat recovery steam generator (HRSG) of a gas turbine combined cycle power plant is a commonly used method to increase output on hot summer days when gas turbine airflow and power output lapse significantly. The aim is to generate maximum possible power output when it is most needed (and, thus, more profitable) at the expense of power plant heat rate. In this paper, using fundamental thermodynamic arguments and detailed heat and mass balance simulations, it will be shown that, under certain boundary conditions, duct firing in the HRSG can be a facilitator of efficiency improvement as well. When combined with highly-efficient aeroderivative gas turbines with high cycle pressure ratios and concomitantly low exhaust temperatures, duct firing can be utilized for small but efficient combined cycle power plant designs as well as more efficient hot-day power augmentation. This opens the door to efficient and agile fossil fuel-fired power generation opportunities to support variable renewable generation.


Author(s):  
Maher A. Elmasri

A fast, interactive, flexible computer program has been developed to facilitate system selection and design for gas turbine based power and cogeneration plants. A data base containing ISO performance information on forty-two gas turbines is coupled to an off-design model to predict engine characteristics for different site and installation parameters. A heat recovery steam generator (HRSG) model allows boiler size and cost to be estimated as a function of the system’s technical parameters. The model can handle HRSG’s with up to two live steam pressures plus a third feedheating/deaerating drum. Five basic types of combined cycle are covered with up to four different process steam streams for cogeneration or gas turbine injection. Two additional feedheating steam bleeds are supported for condensing combined cycles. The program is intelligent with some internal decision making capabilities regarding process steam sourcing and flow directions and will automatically select the appropriate heat and mass balance procedures to cover a wide variety of process flow schematics. The program provides plotter outputs to show the cycle process flow schematic, T-s and h-s diagrams, and HRSG temperature profiles. An application of GTPRO in analyzing some technical and economic performance trade-offs for two-pressure combined cycles is presented.


1995 ◽  
Vol 117 (4) ◽  
pp. 673-677 ◽  
Author(s):  
C. S. Cook ◽  
J. C. Corman ◽  
D. M. Todd

The integration of gas turbines and combined cycle systems with advances in coal gasification and gas stream cleanup systems will result in economically viable IGCC systems. Optimization of IGCC systems for both emission levels and cost of electricity is critical to achieving this goal. A technical issue is the ability to use a wide range of coal and petroleum-based fuel gases in conventional gas turbine combustor hardware. In order to characterize the acceptability of these syngases for gas turbines, combustion studies were conducted with simulated coal gases using full-scale advanced gas turbine (7F) combustor components. It was found that NOx emissions could be correlated as a simple function of stoichiometric flame temperature for a wide range of heating values while CO emissions were shown to depend primarily on the H2 content of the fuel below heating values of 130 Btu/scf (5125 kJ/NM3) and for H2/CO ratios less than unity. The test program further demonstrated the capability of advanced can-annular combustion systems to burn fuels from air-blown gasifiers with fuel lower heating values as low as 90 Btu/scf (3548 kJ/NM3) at 2300°F (1260°C) firing temperature. In support of ongoing economic studies, numerous IGCC system evaluations have been conducted incorporating a majority of the commercial or near-commercial coal gasification systems coupled with “F” series gas turbine combined cycles. Both oxygen and air-blown configurations have been studied, in some cases with high and low-temperature gas cleaning systems. It has been shown that system studies must start with the characteristics and limitations of the gas turbine if output and operating economics are to be optimized throughout the range of ambient operating temperature and load variation.


1981 ◽  
Vol 103 (4) ◽  
pp. 772-775 ◽  
Author(s):  
Akifumi Hori ◽  
Kazuo Takeya

A new reheat gas turbine system is being developed as a national project by the “Engineering Research Association for Advanced Gas Turbines” of Japan. The machine consists of two axial flow compressors, three turbines, intercooler, combustor and reheater. The pilot plant is expected to go into operation in 1982, and a prototype plant will be set up in 1984. The major objective of this reheat gas turbine is application to a combined cycle power plant, with LNG burning, and the final target of combined cycle thermal efficiency is to be 55 percent (LHV).


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