scholarly journals Optimizing a Pressurized Fluidized Bed Combustion Combined Cycle With Gas Turbine Topping Cycle

1993 ◽  
Author(s):  
D. Bohn ◽  
G. H. Dibelius ◽  
R. U. Pitt ◽  
R. Faatz ◽  
G. Cerri ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Coal Gasification ◽  
Pressure Ratio ◽  
Combined Cycle ◽  
Fluidized Bed Combustion ◽  
Steam Generation ◽  
Combined Cycles ◽  
Set Up ◽  
Topping Cycle ◽  
Pressurized Fluidized Bed Combustion

Combined Cycles for the generation of electricity or co-generation of heat and power with Pressurized Fluidized Bed Combustion (PFBC) of coal and a gas turbine topping cycle fired with a fuel suitable for gas turbines have been studied to set up optimum process parameters with respect to net efficiency, emissions including CO2, and keeping in mind the feasibility of the plant components. As a basic approach, natural gas has been considered as a fuel for the topping gas turbine. Net efficiencies up to 50% (LHV) are acheived. For the calculations, a Recursive Equality Constraint Quadratic Programming Method (RECQPM) is applied. The method is semi-implicit, i. e. the equations describing the process are solved using a non-linear equations system solver; the modular structure of the cycle is, however, made up for by programme modules set up for the relevant components/units. With the process layouts studied, the PFBC should be operated at a pressure level to allow for a compact design of the PFBC steam generator and the Hot Gas Clean-Up Unit (HGCU), and to take advantage of the pressure with respect to combustion efficiency, in-bed sulfur retention and NOx-reduction. The overall pressure ratio of the topping gas turbine, e. g. consisting of an LP-compressor plus a free running HP spool, and exhausting to the PFB combustor, should be in the range of 30. Further developments of gas turbine technology with respect to pressure ratio and turbine inlet temperature can be incorporated into the process and will be associated with an increase of overall efficiency. The heat to be extracted from the coal fired PFBC at the typical combustion temperature of 850°C allows for steam generation at conventional live steam and reheat temperatures (and pressures). The incorporation of advanced steam cycle parameters, as actually considered for pulverized coal fired boilers, would again increase the overall net efficiency of the cycle by some 5% with an increase of both the live steam and the reheat temperature from 540°C to 600°C. In contrast to conventional combined cycles with an unfired waste heat boiler for steam generation, the overall efficiency of the PFBC combined cycle with gas turbine topping cycle is only marginally affected by dual pressure steam cycle arrangements, except for very sophisticated and costly designs. To use gas from an integrated coal gasification unit rather than natural gas as a fuel for the topping gas turbine would result in an entirely coal based process. Due to the capability of the PFBC to burn residues of coal gasification and gas purification, this process, compared to pure Integrated Gasification Combined Cycles (IGCC), is less sensitive to the carbon conversion acheived. Even more, the raw gas purification might be simplified, and the process efficiency might be increased as a result of the sulphur removal to be acheived in the PFBC rather than in a raw gas sweetening process. Some preliminary findings for a process with an integrated partial gasification unit are discussed.

Study of Pressurized Fluidized Bed Combustion Combined Cycles With Gas Turbine Topping Cycle

1992 ◽  
Author(s):  
D. Bohn ◽  
G. H. Dibelius ◽  
R. U. Pitt ◽  
R. Faatz ◽  
G. Cerri ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Gas Turbine ◽  
Energy Input ◽  
Fluidized Bed Combustion ◽  
High Pressure High Temperature ◽  
Combined Cycles ◽  
Topping Cycle ◽  
Pressurized Fluidized Bed Combustion ◽  
High Temperature Gas

Coal based combined cycles for efficient generation of electricity or cogeneration of thermal and mechanical (electrical) power can be realized making use of Pressurized Fluidized Bed Combustion (PFBC). A draw-back with respect to the efficiency, however, is imposed from the combustion system limiting the temperature to some 850°C. This threshold may be overcome by integrating a high pressure, high temperature gas turbine topping cycle into the process. In a first step, the high pressure, high temperature gas turbine is fired by natural gas, and the exhaust gas of the turbine is fed to the PFB combustor as an oxygen carrier. In a future advanced system, the fuel gas may be provided by an integrated coal gasification process. A basic reference case has been established based on commercially available gas turbine equipment, hot gas filtration systems as actually tested in various pilot installations, and on a conservative steam cycle component technology. With an ISO gas turbine inlet temperature of 1165°C and an overall compression ratio of 16 up to 30, the entire process yields a net efficiency of some 46% (LHV) and an overall power output of some 750 MW with the gaseous fuel making up for some 50% of the overall energy input. Both the efficiency and the power output have been found rather insensitive with respect to a variation of the overall compression ratio. However, for a non-intercooled compression, an increase of the maximum process pressure would allow for the energy input to be shifted towards coal (and to reduce the natural gas input), and in particular for an elevated PFB combustor pressure considered mandatory for compactness as well as for combustion efficiency including emissions. The numerous calculations for the design, the optimization and the prediction of part-load operation of complex systems are efficiently performed with a semi-implicit method, the results of which have been checked carefully against those of a more conventional sequential approach and found in good agreement.

Analysis of Intermediate Temperature Combined Cycles With a Carbon Dioxide Topping Cycle

2008 ◽  
Author(s):  
R. Chacartegui ◽  
D. Sa´nchez ◽  
F. Jime´nez-Espadafor ◽  
A. Mun˜oz ◽  
T. Sa´nchez
Keyword(s):  
Carbon Dioxide ◽  
Power Plant ◽  
Gas Turbine ◽  
High Efficiency ◽  
Solar Power ◽  
Combined Cycle ◽  
Inlet Temperature ◽  
Pressure Drops ◽  
Combined Cycles ◽  
Topping Cycle

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.

scholarly journals Effect of Pressure on Second-Generation Pressurized Fluidized Bed Combustion Plants

1994 ◽  
Vol 116 (2) ◽  
pp. 345-351 ◽  
Author(s):  
A. Robertson ◽  
D. Bonk
Keyword(s):  
Gas Turbine ◽  
Fluidized Bed ◽  
Coal Gasification ◽  
Second Generation ◽  
Electrical Power ◽  
Fluidized Bed Combustion ◽  
Fuel Gas ◽  
Combustion Gas ◽  
New Type ◽  
Pressurized Fluidized Bed Combustion

In the search for a more efficient, less costly, and more environmentally responsible method for generating electrical power from coal, research and development has turned to advanced pressurized fluidized bed combustion (PFBC) and coal gasification technologies. A logical extension of this work is the second-generation PFBC plant, which incorporates key components of each of these technologies. In this new type of plant, coal is devolatilized/carbonized before it is injected into the PFB combustor bed, and the low-Btu fuel gas produced by this process is burned in a gas turbine topping combustor. By integrating coal carbonization with PFB coal/char combustion, gas turbine inlet temperatures higher than 1149°C (2100°F) can be achieved. The carbonizer, PFB combustor, and particulate-capturing hot gas cleanup systems operate at 871°C (1600°F), permitting sulfur capture by time-based sorbents and minimizing the release of coal contaminants to the gases. This paper presents the performance and economics of this new type of plant and provides a brief overview of the pilot plant test programs being conducted to support its development.

scholarly journals Performance Analysis With Different Means of Cooling in a Combined Cycle

1995 ◽  
Author(s):  
Onkar Singh ◽  
R. Yadav
Keyword(s):  
Gas Turbine ◽  
Power Plants ◽  
Pressure Ratio ◽  
Combined Cycle ◽  
Inlet Temperature ◽  
Optimum Pressure ◽  
Cooling Medium ◽  
Cooling Technology ◽  
Improved Performance ◽  
Topping Cycle

Combined cycle based power plants and their development and application for energy efficient base load power generation necessitates enforced cooling to maintain the topping cycle gas turbine blade temperature at permissible levels, attributed to the increased turbine inlet temperature and compressor pressure ratio, for the improved performance and reliability of combined cycle. The mathematical model based on expansion path inside gas turbine considering dilution of mainstream and aerodynamic mixing losses for a range of cooling medium has been developed based on internal, film, transpiration cooling technologies and a combination of these. It is found that the appreciation of a cycle configuration as well as the optimum pressure ratio and peak temperature vary significantly with types of cooling technology adopted. Steam cooling for rotor appears to be a very potential cooling medium, when employed with an appropriate cooling technology. This paper deals with the thermodynamic analysis of turbine cooling using, different means of cooling i.e. air, water and steam.

System Evaluation and LBTU Fuel Combustion Studies for IGCC Power Generation

1995 ◽  
Vol 117 (4) ◽  
pp. 673-677 ◽  
Author(s):  
C. S. Cook ◽  
J. C. Corman ◽  
D. M. Todd
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Coal Gasification ◽  
Flame Temperature ◽  
Combined Cycle ◽  
Gas Turbine Combustor ◽  
Gas Cleaning ◽  
Wide Range ◽  
Cycle Systems ◽  
Combined Cycles

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.

Effect of Bottoming Cycle Alternatives on the Performance of Combined Cycle

2003 ◽  
Author(s):  
R. Yadav
Keyword(s):  
Gas Turbine ◽  
Pressure Ratio ◽  
Positive Influence ◽  
Combined Cycle ◽  
Exhaust Temperature ◽  
Compressor Pressure Ratio ◽  
Topping Cycle ◽  
Steam Parameters ◽  
Cycle Efficiency ◽  
Steam Cycle

The increase in efficiency of combined cycle has mainly been caused by the improvements in gas turbine cycle efficiency. With the increase in firing temperature the exhaust temperature is substantially high around 873 K for moderate compressor pressure ratio, which has positive influence on steam cycle efficiency. Minimizing the irreversibility within the heat recovery steam generator HRSG and choosing proper steam cycle configuration with optimized steam parameters improve the steam cycle efficiency and thus in turn the combined cycle efficiency. In this paper, LM9001H gas turbine, a state of art technology turbine with modified compressor pressure ratio has been chosen as a topping cycle. Various bottoming cycles alternatives (sub-critical) coupled with LM9001H topping cycle with and without recuperation such as dual and triple pressure steam cycles with and without reheat have been chosen to predict the performance of combined cycle.

A Review of the Efficacy of Silicon Carbide Hot-Gas Filters in Coal Gasification and Pressurized Fluidized Bed Combustion Environments

1996 ◽  
Vol 118 (3) ◽  
pp. 500-506 ◽  
Author(s):  
R. R. Judkins ◽  
D. P. Stinton ◽  
J. H. DeVan
Keyword(s):  
Silicon Carbide ◽  
Fluidized Bed ◽  
Coal Gasification ◽  
Relevant Literature ◽  
Combined Cycle ◽  
Fluidized Bed Combustion ◽  
Gas Cleaning ◽  
Hot Gas ◽  
Hot Gas Cleaning ◽  
Pressurized Fluidized Bed Combustion

Reviews of relevant literature and interviews with individuals cognizant of the state of the art in ceramic filters for hot-gas cleaning were conducted. Thermodynamic calculations of the stability of various ceramic phases were also made. Based on these calculations, reviews, and interviews, conclusions were reached regarding the use of silicon carbide-based ceramics as hot-gas filter media. Arguments are presented that provide the basis for our conclusion that high-purity silicon carbide is a viable material in the integrated coal gasification combined cycle (IGCC) and pressurized fluidized-bed combustion (PFBC) environments we examined. Clay-bonded materials are, we concluded, suspect for these applications, their extensive use not-withstanding. Operations data we reviewed focused primarily on clay-bonded filters, for which a great deal of experience exists. We used the clay-bonded filter experience as a point of reference for our review and analysis.

EFFECT OF OPERATING VARIABLES ON THE PERFORMANCE OF A COMBINED CYCLE COGENERATION SYSTEM WITH MULTIPLE PROCESS HEATERS

2009 ◽  
Vol 33 (1) ◽  
pp. 65-74
Author(s):  
B Law ◽  
B. V. Reddy
Keyword(s):  
Gas Turbine ◽  
Power Plants ◽  
Pressure Ratio ◽  
Combined Cycle ◽  
Operating Conditions ◽  
Operating Variables ◽  
Cogeneration System ◽  
Multiple Process ◽  
Process Heat ◽  
Topping Cycle

Combined cycle power plants with a gas turbine topping cycle and a steam turbine bottoming cycle are widely used due to their high efficiencies. Combined cycle cogeneration has the possibility to produce power and process heat more efficiently, leading to higher performance and reduced green house gas emissions. The objective of the present work is to analyze and simulate a natural gas fired combined cycle cogeneration unit with multiple process heaters and to investigate the effect of operating variables on the performance. The operating conditions investigated include, gas turbine pressure ratio, process heat loads and process steam extraction pressure. The gas turbine pressure ratio significantly influences the performance of the combined cycle cogeneration system. It is also identified that extracting process steam at lower pressures improves the power generation and cogeneration efficiencies. The process heat load influences combined cycle efficiency and combined cycle cogeneration efficiency in opposite ways. It is also observed that using multiple process heaters with different process steam pressures, rather than a single process heater, improves the combined cycle cogeneration plant efficiency.

A Review of the Efficacy of Silicon Carbide Hot Gas Filters in Coal Gasification and Pressurized Fluidized Bed Combustion Environments

1994 ◽  
Author(s):  
Roddie R. Judkins ◽  
David P. Stinton ◽  
Jackson H. DeVan
Keyword(s):  
Silicon Carbide ◽  
Fluidized Bed ◽  
Coal Gasification ◽  
Relevant Literature ◽  
Combined Cycle ◽  
Fluidized Bed Combustion ◽  
Gas Cleaning ◽  
Hot Gas ◽  
Hot Gas Cleaning ◽  
Pressurized Fluidized Bed Combustion

Reviews of relevant literature and interviews with individuals cognizant of the state-of-the-art in ceramic filters for hot-gas cleaning were conducted. Thermodynamic calculations of the stability of various ceramic phases were also made. Based on these calculations, reviews, and interviews, conclusions were reached regarding the use of silicon carbide-based ceramics as hot-gas filter media. Arguments are presented that provide the basis for our conclusion that high-purity silicon carbide is a viable material in the integrated coal gasification combined cycle (IGCC) and pressurized fluidized-bed combustion (PFBC) environments we examined. Clay-bonded materials are, we concluded, suspect for these applications, their extensive use notwithstanding. Operations data we reviewed focused primarily on clay-bonded filters, for which a great deal of experience exists. We used the clay-bonded filter experience as a point of reference for our review and analysis.

scholarly journals Effect of Pressure on Second-Generation Pressurized Fluidized Bed Combustion Plants

1993 ◽  
Author(s):  
Archie Robertson ◽  
Donald Bonk
Keyword(s):  
Gas Turbine ◽  
Fluidized Bed ◽  
Coal Gasification ◽  
Second Generation ◽  
Electrical Power ◽  
Fluidized Bed Combustion ◽  
Fuel Gas ◽  
Combustion Gas ◽  
New Type ◽  
Pressurized Fluidized Bed Combustion

In the search for a more efficient, less costly, and more environmentally responsible method for generating electrical power from coal, research and development has turned to advanced pressurized fluidized bed combustion (PFBC) and coal gasification technologies. A logical extension of this work is the second-generation PFBC plant, which incorporates key components of each of these technologies. In this new type of plant, coal is devolatilized/carbonized before it is injected into the PFB combustor bed, and the low-Btu fuel gas produced by this process is burned in a gas turbine topping combustor. By integrating coal carbonization with PFB coal/char combustion, gas turbine inlet temperatures higher than 1149°C (2100°F) can be achieved. The carbonizer, PFB combustor, and particulate-capturing hot gas cleanup systems operate at 871°C (1600°F), permitting sulfur capture by lime-based sorbents and minimizing the release of coal contaminants to the gases. This paper presents the performance and economics of this new type of plant and provides a brief overview of the pilot plant test programs being conducted to support its development.

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