scholarly journals Optimization and Comparison of Two Combined Cycles Consisting of CO2 and Organic Trans-Critical Cycle for Waste Heat Recovery

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 724
Author(s):  
Liya Ren ◽  
Huaixin Wang
Keyword(s):  
Heat Recovery ◽  
High Efficiency ◽  
Waste Heat ◽  
Combined Cycle ◽  
Parameters Optimization ◽  
Exergy Loss ◽  
Cycle Performance ◽  
Compact Size ◽  
Intermediate Heat Exchanger ◽  
Combined Cycles

CO2-based trans-critical and supercritical cycles have received more and more attention for power generation in many applications such as solar and nuclear energy due to the desirable thermal stability and properties of CO2 and the high efficiency and compact size of the plant. In this study, two combined cycles driven by the flue gas exhausted from the LM2500+ gas turbine, CO2-TC+OTC (organic trans-critical cycle) and CO2-TC/OTC, which can achieve a good trade-off between thermal efficiency and utilization of the waste heat, are investigated. Parameters optimization is carried out by means of genetic algorithm to maximize the net power output of the combined cycle and the effects of the key parameters on the cycle performance are examined. Results show that the exergy efficiency of CO2-TC+OTC is about 2% higher than that of CO2-TC/OTC. In CO2-TC+OTC, the recuperation process of CO2 causes the largest exergy loss; in CO2-TC/OTC, the largest exergy loss occurs in the heat recovery vapor generator, followed by the intermediate heat exchanger due to the larger variation of the specific heat capacity of CO2 and organic fluid in the heat addition process.

Decay of Excitation Load From Heat Recovery Steam Generators (HRSG) to Attached Piping System As a Function of Pipe Supports Locations

2019 ◽  
Author(s):  
Emmanuel Appiah ◽  
Kshitij Gawande
Keyword(s):  
Gas Turbine ◽  
Heat Recovery ◽  
High Efficiency ◽  
Acoustic Resonance ◽  
Combined Cycle ◽  
High Mass ◽  
Piping System ◽  
Steam Generation ◽  
System Integrity ◽  
Compact Size

Abstract Construction of combined cycle gas turbine (CCGT) plants, which are combination of a simple cycle gas turbine (Brayton cycle) and a steam power cycle (Rankine cycle), have increased in recent years due to their high efficiency, low emissions, relative compact size, and minimal delivery time, among other advantages. One key component of CCGT is a heat recovery steam generator (HRSG). The HRSG is basically a heat exchanger composed of a series of preheaters (economizers), evaporator, reheaters, and superheaters. Combustion gas from gas turbine is used as an energy source for steam generation in the HRSG. Due to high mass flowrate of combustion turbine exhausts gas and injection of water to reduce NOx contents, high vibration and severe noise are created. The noise induces acoustic resonance in the HRSG duct cavities. The high vibration together with the acoustic resonance creates large forces. These forces have been attributed to excitation mechanisms including fluid elastic instability, random turbulence excitation, and periodic wake shedding. Some of the forces are transmitted to the attached pipes. Integrity of the piping system to withstand the forces depends on rigid and variable pipe supports. It is therefore paramount to determine the load induced into the supports to design them adequately. The purpose of this paper is to provide relative magnitude of loads experienced at various pipe supports as a function of distance from the HRSG (load decay). This knowledge is expected to help support designers to optimize material allocation to ensure pipe system integrity at optimum cost.

MODELING AND SIMULATION OF THERMOELECTRIC PLANT OF COMBINED CYCLES AND ITS ENVIRONMENTAL IMPACT

2005 ◽  
Vol 4 (1) ◽  
pp. 83
Author(s):  
J. F. Mitre ◽  
A. I. Lacerda ◽  
R. F. De Lacerda
Keyword(s):  
Power Plant ◽  
High Efficiency ◽  
Waste Heat ◽  
Combined Cycle ◽  
Steam Power ◽  
Operational Conditions ◽  
Thermoelectric Plant ◽  
Combined Cycles ◽  
Absolute Quantity ◽  
The Impact

The impact any power plant has upon the environment must be minimized as much as possible. Due to its high efficiency, low emission levels and low cooling requirements, combined cycle plants are considered to be environmentally friendly. This study evaluates the effect of operational conditions on pollutants (CO, CO2, SOx, NOx) emissions levels, waste-heat and wastewater of a combined-cycle natural gas and steam power plant. The HYSYS process simulation was used for modelling and simulation. The study clearly shows that the absolute quantity of pollutants emitted is high. Also, it was possible to verify that the unit operate in the condition of minimal emissions regarding the maximum possible, and thus a reduction or elimination of such pollutants is not possible.

scholarly journals Once-Through Heat Recovery Steam Generators Working With Sub- and Supercritical Steam Conditions for Combined Cycles

1997 ◽  
Author(s):  
P. J. Dechamps ◽  
J.-F. Galopin
Keyword(s):  
Heat Recovery ◽  
High Pressures ◽  
Combined Cycle ◽  
Cycle Performance ◽  
Steam Generators ◽  
Advantages And Disadvantages ◽  
Circulation Mode ◽  
Combined Cycles ◽  
Supercritical Steam Conditions ◽  
Plant Efficiency

This paper characterizes the performances of once-through heat recovery steam generators in combined cycle applications. Although the concept of once-through boilers has been extensively used for fired boilers, this circulation mode is rather new in combined cycles. Once-through circulation is required at very high pressures, including supercritical conditions, for which there is a possible advantage in terms of the plant efficiency. The concept is also certainly the best solution for high subcritical pressures, such as those required by repowering applications. In addition to cycle performance, this paper describes the advantages and disadvantages of the once-through in heat recovery applications. The operational behaviour of such heat recovery steam generators is discussed, together with the main design implications. A prototype plant running in supercritical steam conditions is also described, as well as some of its possible applications.

MODELING AND SIMULATION OF THERMOELECTRIC PLANT OF COMBINED CYCLES AND ITS ENVIRONMENTAL IMPACT

2005 ◽  
Vol 4 (1) ◽  
Author(s):  
J. F. Mitre ◽  
A. I. Lacerda ◽  
R. F. De Lacerda
Keyword(s):  
Power Plant ◽  
High Efficiency ◽  
Waste Heat ◽  
Combined Cycle ◽  
Steam Power ◽  
Operational Conditions ◽  
Thermoelectric Plant ◽  
Combined Cycles ◽  
Absolute Quantity ◽  
The Impact

The impact any power plant has upon the environment must be minimized as much as possible. Due to its high efficiency, low emission levels and low cooling requirements, combined cycle plants are considered to be environmentally friendly. This study evaluates the effect of operational conditions on pollutants (CO, CO2, SOx, NOx) emissions levels, waste-heat and wastewater of a combined-cycle natural gas and steam power plant. The HYSYS process simulation was used for modelling and simulation. The study clearly shows that the absolute quantity of pollutants emitted is high. Also, it was possible to verify that the unit operate in the condition of minimal emissions regarding the maximum possible, and thus a reduction or elimination of such pollutants is not possible.

Hybrid direct carbon fuel cell-thermoradiative systems for high-efficiency waste-heat recovery

2019 ◽  
Vol 198 ◽  
pp. 111842
Author(s):  
Xin Zhang ◽  
Jianying Du ◽  
Yee Sin Ang ◽  
Jincan Chen ◽  
Lay Kee Ang
Keyword(s):  
Fuel Cell ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
High Efficiency ◽  
Waste Heat ◽  
Direct Carbon Fuel Cell

Effect of supplementary firing on the performance of an integrated gasification combined cycle power plant

2000 ◽  
Vol 214 (1) ◽  
pp. 53-60 ◽  
Author(s):  
S De ◽  
P K Nag
Keyword(s):  
Power Plant ◽  
Heat Recovery ◽  
Combined Cycle ◽  
Exergy Loss ◽  
Temperature Ratio ◽  
Integrated Gasification Combined Cycle ◽  
Specific Heats ◽  
Second Law Analysis ◽  
Integrated Gasification ◽  
Igcc Power Plant

The effect of supplementary firing on the performance of an integrated gasification combined cycle (IGCC) power plant is studied. The results are presented with respect to a simple ‘unfired’ IGCC power plant with single pressure power generation for both the gas and the steam cycles as reference. The gases are assumed as real with variable specific heats. It is found that the most favourable benefit of supplementary firing can be obtained for a low temperature ratio R T only. For higher R T, only a gain in work output is possible with a reverse effect on the overall efficiency of the plant. The second law analysis reveals that the exergy loss in the heat-recovery steam generator is most significant as the amount of supplementary firing increases. It is also noteworthy that, although the total exergy loss of the plant decreases with higher supplementary firing for a low R T (= 3.0), the reverse is the case for a higher R T (= 6.0).

High efficiency GeTe-based materials and modules for thermoelectric power generation

2021 ◽  
Author(s):  
Tong Xing ◽  
Qingfeng Song ◽  
Pengfei Qiu ◽  
Qihao Zhang ◽  
Ming Gu ◽  
...  
Keyword(s):  
Power Generation ◽  
Thermoelectric Power ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
High Efficiency ◽  
Waste Heat ◽  
Thermoelectric Performance ◽  
Thermoelectric Generators ◽  
Thermoelectric Power Generation

GeTe-based materials have a great potential to be used in thermoelectric generators for waste heat recovery due to their excellent thermoelectric performance, but their module research is greatly lagging behind...

Design Criteria and Optimization of Heat Recovery Steam Cycles for High-Efficiency, Coal-Fired, Fischer-Tropsch Plants

2012 ◽  
Author(s):  
Emanuele Martelli ◽  
Thomas G. Kreutz ◽  
Manuele Gatti ◽  
Paolo Chiesa ◽  
Stefano Consonni
Keyword(s):  
Heat Recovery ◽  
High Efficiency ◽  
Thermal Power ◽  
Combined Cycle ◽  
Synthesis Process ◽  
Integrated Gasification Combined Cycle ◽  
Fischer Tropsch ◽  
Ft Synthesis ◽  
Optimization Methodology ◽  
Integrated Gasification

In this work, the “HRSC Optimizer”, a recently developed optimization methodology for the design of Heat Recovery Steam Cycles (HRSCs), Steam Generators (HRSGs) and boilers, is applied to the design of steam cycles for three interesting coal fired, gasification based, plants with CO2 capture: a Fischer-Tropsch (FT) synthesis process with high recycle fraction of the unconverted FT gases (CTL-RC-CCS), a FT synthesis process with once-through reactor (CTL-OT-CCS), and an Integrated Gasification Combined Cycle (IGCC-CCS) based on the same technologies. The analysis reveals that designing efficient HRSCs for the IGCC and the once-through FT plant is relatively straightforward, while designing the HRSC for plant CTL-RC-CCS is very challenging because the recoverable thermal power is concentrated at low temperatures (i.e., below 260 °C) and only a small fraction can be used to superheat steam. As a consequence of the improved heat integration, the electric efficiency of the three plants is increased by about 2 percentage points with respect to the solutions previously published.

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.

Design, Part Load and Transient Operation of Combined Cycle Plants With Water Flashing

1995 ◽  
Author(s):  
P. J. Dechamps
Keyword(s):  
High Pressure ◽  
Steam Generator ◽  
Gas Turbines ◽  
Heat Recovery ◽  
Vapour Phase ◽  
Pressure Level ◽  
Combined Cycle ◽  
Saturated Steam ◽  
Heat Recovery Steam Generator ◽  
Combined Cycles

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.

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