scholarly journals Application of RQL Coal Combustor Technology to Large Utility Gas Turbines

1993 ◽  
Author(s):  
C. Wilkes ◽  
R. A. Wenglarz ◽  
P. J. Hart ◽  
H. C. Mongia

This paper describes the application of Allison’s rich-quench-lean (RQL) coal combustor technology to large utility gas turbines in the 100 MWe+ class. The RQL coal combustor technology was first applied to coal derived fuels in the 1970s and has been under development since 1986 as part of a Department of Energy (DOE)-sponsored heat engine program aimed at proof of concept testing of coal-fired gas turbine technology. The 5 MWe proof of concept engine/coal combustion system was first tested on coal water slurry (CWS); it is now being prepared for testing on dry pulverized coal. A design concept to adapt the RQL coal combustor technology developed under the DOE program to large utility-sized gas turbines has been proposed for a Clean Coal V program. The engine and combustion system modifications required for application to coal-fueled combined cycle power plants using 100 MWe+ gas turbines are described. Estimates for emissions and cycle performance are given. Included are comparisons with a conventional pulverized coal plant that illustrates the advantages of incorporating a gas turbine on cycle efficiency and emission rate.

Author(s):  
S. Can Gulen ◽  
Raub W. Smith

A significant portion of the new electrical generating capacity installed in the past decade has employed heavy-duty gas turbines operating in a combined cycle configuration with a steam turbine bottoming cycle. In these power plants approximately one third of the power is generated by the bottoming cycle. To ensure that the highest possible combined cycle efficiency is realized it is important to develop the combined cycle power plant as a system. Doing so requires a solid understanding of the efficiency entitlement of both, topping and bottoming, cycles separately and as a whole. This paper describes a simple but accurate method to estimate the Rankine bottoming cycle power output directly from the gas turbine exhaust exergy utilizing the second law of thermodynamics. The classical first law approach, i.e. the heat and mass balance method, requires lengthy calculations and complex computer-based modeling tools to evaluate Rankine bottoming cycle performance. In this paper, a rigorous application of the fundamental thermodynamic principles embodied by the second law to the major cycle components clearly demonstrates that the Rankine cycle performance can be accurately represented by several key parameters. The power of the second law approach lies in its ability to highlight the theoretical entitlement and state-of-the-art design performances simultaneously via simple, fundamental relationships. By considering economically and technologically feasible upper limits for the key parameters, the maximum achievable bottoming cycle power output is readily calculable for any given gas turbine from its exhaust exergy.


Author(s):  
Steven J. Bossart

The Morgantown Energy Technology Center (METC) of the U.S. Department of Energy (DOE) is actively sponsoring research to develop coal-based power generation systems that use coal more efficiently and economically and with lower emissions than conventional pulverized-coal power plants. Some of the more promising of the advanced coal-based power generation systems are shown in Figure 1: pressurized fluidized-bed combustion combined-cycle (PFBC), integrated gasification combined-cycle (IGCC), and direct coal-fueled turbine (DCFT). These systems rely on gas turbines to produce all or a portion of the electrical power generation. An essential feature of each of these systems is the control of particles at high-temperature and high-pressure (HTHP) conditions. Particle control is needed in all advanced power generation systems to meet environmental regulations and to protect the gas turbine and other major system components. Particles can play a significant role in damaging the gas turbine by erosion, deposition, and corrosion. Erosion is caused by the high-speed impaction of particles on the turbine blades. Particle deposition on the turbine blades can impede gas flow and block cooling air. Particle deposition also contributes to corrosive attack when alkali metal compounds adsorbed on the particles react with the gas turbine blades. Incorporation of HTHP particle control technologies into the advanced power generation systems can reduce gas turbine maintenance requirements, increase plant efficiency, reduce plant capital cost, lower the cost of electricity, reduce wastewater treatment requirements, and eliminate the need for post-turbine particle control to meet New Source Performance Standards (NSPS) for particle emissions.


Author(s):  
U. Ruedel ◽  
V. Stefanis ◽  
A. D. Ramaglia ◽  
S. Florjancic

This paper provides an overview of the ongoing development activities for the Ansaldo Energia gas turbines AE64.3A, AE94.2, AE94.2K, AE94.3A, GT26 (2006), GT26 (2011), GT36-S6 and GT36-S5. The improvements significantly reduce the energy consumption in gas turbine combined cycle (GTCC) power plants and are directed towards improved operational and fuel flexibility, increased GT power output, GT efficiency and improved component lifetime. The collaborative development, validation and application of the constant pressure sequential combustion system (‘CPSC’) for the GT36 engine will be introduced. Based on the well-established sequential burner technology as installed since 1994 on all legacy GT26 gas turbines, the operation turndown, fuel flexibility and the overall system robustness is described. The development and engine validation of the first stage burner for Improved Durability and Turndown as well as the design of a Combustor Sequential Liner within a can combustion system is shown. The reconstruction and analysis of the acoustic transfer matrix of the flame in the sequential burner together with the applied air and fuel management facilitate emission and dynamics control at both, the extremely high and low firing temperature ranges. The axial flow turbine of the GT36 heavy duty gas turbine, which has evolved from the existing and proven GT26 design, consists of an optimized annulus flow path, higher lift airfoil profiles, optimized aerodynamic matching between the turbine stages and a new and improved cooling systems of the turbine vanes and blades. A major design feature of the turbine has been to control and reduce the aerodynamic losses, associated with the airfoil profiles, trailing edges, blade tips, end walls and coolant ejection. The advantages of these design changes to the overall gas turbine efficiency have been verified via extensive experimental testing.


Author(s):  
S. Can Gülen ◽  
Raub W. Smith

A significant portion of the new electrical generating capacity installed in the past decade has employed heavy-duty gas turbines operating in a combined cycle configuration with a steam turbine bottoming cycle. In these power plants approximately one-third of the power is generated by the bottoming cycle. To ensure that the highest possible combined cycle efficiency is realized it is important to develop the combined cycle power plant as a system. Doing so requires a solid understanding of the efficiency entitlement of both, topping and bottoming, cycles separately and as a whole. This paper describes a simple but accurate method to estimate the Rankine bottoming cycle power output directly from the gas turbine exhaust exergy, utilizing the second law of thermodynamics. The classical first law approach, i.e., the heat and mass balance method, requires lengthy calculations and complex computer-based modeling tools to evaluate Rankine bottoming cycle performance. In this paper, a rigorous application of the fundamental thermodynamic principles embodied by the second law to the major cycle components clearly demonstrates that the Rankine cycle performance can be accurately represented by several key parameters. The power of the second law approach lies in its ability to highlight the theoretical entitlement and state-of-the-art design performances simultaneously via simple fundamental relationships. By considering economically and technologically feasible upper limits for the key parameters, the maximum achievable bottoming cycle power output is readily calculable for any given gas turbine from its exhaust exergy.


2006 ◽  
Vol 128 (05) ◽  
pp. 36-39
Author(s):  
Lee S. Langston

This paper focuses on research and innovation in the gas turbine industry. The production of nonaviation gas turbines was $3.6 billion in 1990, only 15% of total production. With improvement in thermal efficiency, increases in unit size, and the building of record breaking combined-cycle electric power plants fueled by cheap natural gas, nonaviation production zoomed to a euphoric high of $25.8 billion in 2001. The US Department of Energy announced last year the award of $130 million for 10 new projects to integrate hydrogen-burning gas turbines and turbine subsystems into integrated gasification combined cycle (IGCC) central power stations. Nuclear generation is also a zero-emissions technology, and Pebble Bed Modular Reactor Ltd, a South African company, is developing a gas turbine-nuclear reactor electric power plant, with participating companies that include Westinghouse, MHI of Japan, Nukem of Germany, and South Africa's Eskom.


Author(s):  
Hiwa Khaledi ◽  
Roozbeh Zomorodian ◽  
Mohammad Bagher Ghofrani

Gas turbine performances are directly related to site conditions. The use of gas turbines in combined gas-steam power plants, also applied to cogeneration, increases such dependence. In recent years, inlet air cooling systems have been introduced to control air temperature at compressor inlet, resulting in an increase in plant power and efficiency. In this paper, the dependence of outside conditions for a simple gas turbine and a combined cycle plant is studied, using absorption chiller as inlet air cooling system. We used, as case study, a simple plant equipped with one frame E gas turbine and a combined cycle with a two pressure level heat recovery steam generator (HRSG). It was found that inlet air cooling with absorption chiller has great positive influence on power and less on efficiency of the gas turbine plant. Two steam sources (External and Internal) have been considered for chiller. External source has large positive influence on power but keep the efficiency of the combined cycle unchanged, while internal source causes a reduction in steam turbine mass flow. Consequently power production and efficiency of the combined cycle decrease. This reduction is lower in mid temperature (25 to 35°C) but higher in high temperature (35 to 45°C). Inlet cooling would result in lowering turbine exhaust temperature, thus decreasing the efficiency of HRSG.


Author(s):  
Peter J. Stuttaford ◽  
Khalid Oumejjoud

CO2 emissions generated by power plants make up a significant portion of global carbon emissions. Although there has been a great deal of focus on new power sources incorporating state of the art environmental protection systems, there has been little focus on addressing the issues of existing power plants. The purpose of this work is to address the options available to existing gas turbine based power plants to retrofit CO2 reduction measures cost effectively at the source of emissions, the combustor. Pre-combustion decarbonization is a highly efficient method of carbon removal, as only a small fraction of the gas turbine system flow needs to be addressed. This results in the requirement to burn a hydrogen based fuel, which presents challenges due to its highly reactive nature. The properties of hydrogen/syngas combustion are reviewed with emphasis on solutions for premixed combustion systems. Premixed combustion as opposed to diffusion combustion systems are key to retrofit solutions for existing gas turbines. Premixed systems provide the life cycle cost benefit, and heat rate benefit of not requiring the addition of diluent to the cycle to control emissions. Fuel flexibility is critical for retrofit systems, allowing operators to run on high hydrogen fuels as well as back-up standard natural gas to maximize power plant availability. Pre-combustion decarbonization may occur remote from the power plant at a centralized fuel processing facility, or it may be integrated into the combined cycle gas turbine power plant. Existing combined cycle power plants operating on natural gas could be modified to incorporate fuel decarbonization into the cycle, minimizing the parasitic loss of such a system while capturing carbon credits which are likely to become of increasing monetary value. An example cycle to address such integrated systems is presented. The focus of this work is to present a cycle to provide decarbonized fuel, cost effectively, from existing natural gas systems, as well as centralized coal/petcoke based fuel processing facilities. An additional focus is on the combustion system design requirements to burn such fuels, which are retrofitable to existing heavy duty gas turbine based power plants.


2015 ◽  
Vol 5 (2) ◽  
pp. 89
Author(s):  
Munzer S. Y. Ebaid ◽  
Qusai Z. Al-hamdan

<p class="1Body">Several modifications have been made to the simple gas turbine cycle in order to increase its thermal efficiency but within the thermal and mechanical stress constrain, the efficiency still ranges between 38 and 42%. The concept of using combined cycle power or CPP plant would be more attractive in hot countries than the combined heat and power or CHP plant. The current work deals with the performance of different configurations of the gas turbine engine operating as a part of the combined cycle power plant. The results showed that the maximum CPP cycle efficiency would be at a point for which the gas turbine cycle would have neither its maximum efficiency nor its maximum specific work output. It has been shown that supplementary heating or gas turbine reheating would decrease the CPP cycle efficiency; hence, it could only be justified at low gas turbine inlet temperatures. Also it has been shown that although gas turbine intercooling would enhance the performance of the gas turbine cycle, it would have only a slight effect on the CPP cycle performance.</p>


Author(s):  
Abbie Layne ◽  
Scott Samuelsen ◽  
Mark Williams ◽  
Patricia Hoffman

A hybrid heat engine results from the fusion of a heat engine with a non-heat-engine based cycle (unlike systems). The term combined cycle, which refers to similar arrangements, is reserved for the combination of two or more heat engines (like systems). The resulting product of the integration of a gas turbine and a fuel cell is referred to here as a hybrid heat engine or “Hybrid” for short. The intent of this paper is to provide, to the gas turbine community, a review of the present status of hybrid heat engine technologies. Current and projected activities associated with this emerging concept are also presented. The National Energy Technology Laboratory (NETL) is collaborating with other sponsors and the private sector to develop a Hybrid Program. This program will address the issues of technology development, integration, and ultimately the demonstration of what may be the most efficient of power plants in the world — the Hybrid System. Analyses of several Hybrid concepts have indicated the potential of ultra-high efficiencies (approaching 80%). In the Hybrid, the synergism between the gas turbine and fuel cell provides higher efficiencies and lower costs than either system can alone. Testing of the first Hybrid concept has been initiated at the National Fuel Cell Research Center (NFCRC).


1979 ◽  
Author(s):  
H. C. Daudet ◽  
C. A. Kinney

This paper presents a discussion of the significant results of a study program conducted for the Department of Energy to evaluate the potential for closed cycle gas turbines and the associated combustion heater systems for use in coal fired public utility power plants. Two specific problem areas were addressed: (a) the identification and analysis of system concepts which offer high overall plant efficiency consistent with low cost of electricity (COE) from coal-pile-to-bus-bar, and (b) the identification and conceptual design of combustor/heat exchanger concepts compatible for use as the cycle gas primary heater for those plant systems. The study guidelines were based directly upon the ground rules established for the ECAS studies to facilitate comparison of study results. Included is a discussion of a unique computer model approach to accomplish the system analysis and parametric studies performed to evaluate entire closed cycle gas turbine utility power plants with and without Rankine bottoming cycles. Both atmospheric fluidized bed and radiant/convective combustor /heat exchanger systems were addressed. Each incorporated metallic or ceramic heat exchanger technology. The work culminated in conceptual designs of complete coal fired, closed cycle gas turbine power plants. Critical component technology assessment and cost and performance estimates for the plants are also discussed.


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