Heat Recovery Steam Generator Design for a Graz Cycle Prototype Power Plant for CO2 Capture

Author(s):  
I. Giglmayr ◽  
J. Paul ◽  
W. Sanz

The introduction of closed cycle gas turbines with their capability of retaining combustion generated CO2 can offer a valuable contribution to the Kyoto goal and to future power generation. Therefore, research and development at Graz University of Technology has lead to the GRAZ CYCLE, a zero emission power cycle of highest efficiency. The GRAZ CYCLE is still on a theoretical level, first tests with the turbo-machinery equipment were performed. In the GRAZ CYCLE fossil fuels are burned with pure oxygen which enables a cost-effective separation of the combustion generated CO2 by condensation. Cycle efficiencies as high as 63% can be reached. Taking the efforts for the oxygen supply into account the efficiency is reduced to 55% [1]. This work presents a further step towards a GRAZ CYCLE prototype plant, with special emphasis on the layout and design of the heat recovery steam generator (HRSG). The hot exhaust gas of the turbine consists mainly of CO2 and H2O. This exhaust gas causes higher demands on the HRSG. A faster corrosion of the heat exchangers and the recirculation of the cycle fluid have to be considered. Based on the design of conventional HRSGs, the necessary adaptations are discussed and economically evaluated.

Author(s):  
P. J. Dechamps

The last decade has seen remarkable improvement in gas turbine based power generation technologies, with the increasing use of natural gas-fuelled combined cycle units in various regions of the world. The struggle for efficiency has produced highly complex combined cycle schemes based on heat recovery steam generators with multiple pressure levels and possibly reheat. As ever, the evolution of these schemes is the result of a technico-economic balance between the improvement in performance and the increased costs resulting from a more complex system. This paper looks from the thermodynamic point of view at some simplified combined cycle schemes based on the concept of water flashing. In such systems, high pressure saturated water is taken off the high pressure drum and flashed into a tank. The vapour phase is expanded as low pressure saturated steam or returned to the heat recovery steam generator for superheating, whilst the liquid phase is recirculated through the economizer. With only one drum and three or four heat exchangers in the boiler as in single pressure level systems, the plant might have a performance similar to that of a more complex dual pressure level system. Various configurations with flash tanks are studied based on commercially available 150 MW-class E-technology gas turbines and compared with classical multiple pressure level combined cycles. Reheat units are covered, both with flash tanks and as genuine combined cycles for comparison purposes. The design implications for the heat recovery steam generator in terms of heat transfer surfaces are emphasized. Off-design considerations are also covered for the flash based schemes, as well as transient performances of these schemes, because the simplicity of the flash systems compared to normal combined cycles significantly affects the dynamic behaviour of the plant.


2002 ◽  
Vol 124 (3) ◽  
pp. 496-502 ◽  
Author(s):  
B. E. Lee ◽  
S. B. Kwon ◽  
C. S. Lee

Computational and experimental studies are performed to investigate the effect of swirl flow of gas turbine exhaust gas (GTEG) in an inlet duct of a heat recovery steam generator (HRSG). A supplemental-fired HRSG is chosen as the model studied because the uniformity of the GTEG at the inlet plane of the duct burner is essential in such applications. Both velocity and oxygen distributions are investigated at the inlet plane of the duct burner installed in the middle of the HRSG transition duct. Two important parameters, the swirl angle of GTEG and the momentum ratio of additional air to GTEG, are chosen for the investigation of mixing between the two streams. It has been found that a flow correction device (FCD) is essential to provide a uniform gas flow distribution at the inlet plane of the duct burner.


Author(s):  
H. Jericha ◽  
W. Sanz ◽  
E. Go¨ttlich

Introduction of closed cycle gas turbines with their capability of retaining combustion generated CO2 can offer a valuable contribution to the Kyoto goal and to future power generation. Therefore research and development work at Graz University of Technology since the nineties has led to the Graz Cycle, a zero emission power cycle of highest efficiency. It burns fossil fuels with pure oxygen which enables the cost-effective separation of the combustion CO2 by condensation. The efforts for the oxygen supply in an air separation plant are partly compensated by cycle efficiencies far higher than for modern combined cycle plants. Upon the basis of the previous work the authors present the design concept for a large power plant of 400 MW net power output making use of the latest developments in gas turbine technology. The Graz Cycle configuration is changed insofar, as condensation and separation of combustion generated CO2 takes place at the 1 bar range in order to avoid the problems of condensation of water out of a mixture of steam and incondensable gases at very low pressure. A final economic analysis shows promising CO2 mitigation costs in range of 20–30 $/ton CO2 avoided. The authors believe that they present here a partial solution regarding thermal power production for the most urgent problem of saving our climate.


Author(s):  
H. Jericha ◽  
W. Sanz ◽  
E. Göttlich

The introduction of closed cycle gas turbines with their capability of retaining combustion generated CO2 can offer a valuable contribution to the Kyoto goal and to future power generation. Therefore research and development work at the Graz University of Technology since the 1990s has led to the Graz Cycle, a zero emission power cycle of highest efficiency. It burns fossil fuels with pure oxygen which enables the cost-effective separation of the combustion CO2 by condensation. The efforts for the oxygen supply in an air separation plant are partly compensated by cycle efficiencies far higher than for modern combined cycle plants. Upon the basis of the previous work, the authors present the design concept for a large power plant of 400 MW net power output making use of the latest developments in gas turbine technology. The Graz Cycle configuration is changed, insofar as condensation and separation of combustion generated CO2 takes place at the 1 bar range in order to avoid the problems of condensation of water out of a mixture of steam and incondensable gases at very low pressure. A final economic analysis shows promising CO2 mitigation costs in the range of $20–30/ton CO2 avoided. The authors believe that they present here a partial solution regarding thermal power production for the most urgent problem of saving our climate.


1979 ◽  
Author(s):  
L. F. Fougere ◽  
H. G. Stewart ◽  
J. Bell

Citizens Utilities Company’s Kauai Electric Division is the electric utility on the Island of Kauai, fourth largest and westernmost as well as northernmost of the Hawaiian Islands. As a result of growing load requirements, additional generating capacity was required that would afford a high level of reliability and operating flexibility and good fuel economy at reasonable capital investment. To meet these requirements, a combined cycle arrangement was completed in 1978 utilizing one existing gas turbine-generator and one new gas turbine-generator, both exhausting to a new heat recovery steam generator which supplies steam to an existing steam turbine-generator. Damper controlled ducting directs exhaust gas from either gas turbine, one at a time, through the heat recovery steam generator. The existing oil-fired steam boiler remains available to power the steam turbine-generator independently or in parallel with the heat recovery steam generator. The gas turbines can operate either in simple cycle as peaking units or in combined cycle, one at a time, as base load units. This arrangement provides excellent operating reliability and flexibility, and the most favorable economics of all generating arrangements for the service required.


2021 ◽  
Vol 65 (1) ◽  
pp. 93-104
Author(s):  
Onkar Singh ◽  
Gaitry Arora ◽  
Vinod Kumar Sharma

Heliostat-based solar thermal power system consisting of a combination of the Brayton cycle, Rankine cycle, and organic Rankine cycle is a potential option for harnessing solar energy for power generation. Among different options for improving the performance of solarized triple combined cycle the option of introducing intercooling and reheating in the gas turbine cycle and utilizing the waste heat for augmenting the power output needs investigation. Present study considers a solarized triple combined cycle with intercooling and reheating in gas turbines while using the heat rejected in intercooling in heat recovery vapour generator and heat recovery steam generator separately in two different arrangements. A comparison of two distinct cycle arrangements has been carried out based on Ist law and IInd law of thermodynamics with the help of thermodynamic parameters. Results show that triple combined cycle having intercooling heat used in heat recovery vapour generator offers maximum energy efficiency of 63.54% at 8 CPR & 300K ambient temperature and maximum exergetic efficiency of 38.37% at 14 CPR & 300 K. While the use of intercooling heat in heat recovery steam generator offers maximum energy and exergetic efficiency of 64.15% and 39.72% respectively at 16 CPR & 300 K ambient temperature.


Author(s):  
P. Shukla ◽  
M. Izadi ◽  
P. Marzocca ◽  
D. K. Aidun

This paper evaluates the possibility of combining an intercooled gas turbine power cycle with a steam turbine cycle and the application of the intercooler as a feed-water heater for the heat recovery steam generator. In advance gas turbines the intercooler is used to improve the overall efficiency of the simple cycle but a noticeable amount of heat is wasted to the atmosphere. However, this energy can be recovered by using the proposed method in the current study. Accordingly, a thermodynamic study is done to investigate the improvement in efficiency achieved by feed-water heating. First the effect of intercooler parameters on the outlet condition of the water is studied. The bottoming cycle is then studied in details for the effect of feed-water temperature. An estimate of the energy saving by using the proposed method will be reported. The results show that less heat input will be required for the same amount of steam generation. The current study provides a theoretical support for waste heat recovery from the intercooler.


Author(s):  
Raphael Duarte ◽  
Sandro Ferreira ◽  
Rafael Barbosa

The heavy duty gas turbines evolution led to higher combined cycle efficiencies. Thus, more complex heat recovery steam generators were developed in order to maximize the use of that energy potential. Therefore, computational models capable to predict the operational conditions of the equipment may be needed in order to analyze the system behavior for different situations. This article describes a computational model able to simulate the off-design behavior of a heat recovery steam generator (HRSG) operating in a combined cycle power plant. The model was developed so that it can be used in both model-based diagnostics systems and performance evaluation systems. Each heat exchanger inside the HRSG was designed individually and arranged according to the analyzed equipment. The computer code’s architecture was built in such a way that it can be easily changed, allowing the analysis of other HRSG’s configurations with simple structural changes, given the program’s modularity. In order to deal with the lack of details of the power plant equipment, which means not enough geometrical information of each heat exchanger, a generic algorithm tool was used to calibrate the heat exchangers models using only the measured data of the power plant SCADA. The developed program was validated against operational data from a real plant and showed satisfactory results, confirming the robustness of this model.


Author(s):  
Peter Eisenkolb ◽  
Martin Pogoreutz ◽  
Hermann Halozan

Gas-fired combined cycle power plants (CCP) are presently the most efficient systems for producing electricity with fossil fuels. Gas turbines have been and are being improved remarkably during the last years; presently they achieve efficiencies of more than 38% and gas turbine outlet temperatures of up to 610°C. These high outlet temperatures require modifications and improvements of heat recovery steam generators (HRSG). Presently dual pressure HRSGs are most commonly used in combined cycle power stations. The next step seems to be the triple-pressure HRSG to be able to utilise the high gas turbine outlet temperatures efficiently and to reduce exergy losses caused by the heat transfer between exhaust gas and the steam cycle. However, such triple-pressure systems are complicated considering parallel tube bundles as well as start up operation and load changes. For that reason an attempt has been made to replace such multiple pressure systems by a modified Rankine cycle with only a single-pressure level. In the case of the same total heat transfer surfaces this innovative single-pressure system achieves approximately the same efficiency as the triple-pressure system. By optimising the heat recovery from the exhaust gas to the steam/water cycle, i.e. minimising exergy losses, the stack temperature is much higher. Increasing the heat transfer surfaces means a decrease of the stack temperature and a further improvement of the overall CCP-efficiency. Therefore one has to be aware that the proposed system offers advantages not only in the case of a foreseeable increase of gas turbine outlet temperatures but also for presently available gas turbines. Using existing highly efficient gas turbines and subcritical steam conditions, power plants with this proposed Eisenkolb Single Pressure (ESP_CCP) heat recovery steam generator achieve thermal efficiencies of about 58.7% (LHV).


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