Performance Analysis of a Rankine-Goswami Combined Cycle

2011 ◽  
Author(s):  
Ricardo Vasquez Padilla ◽  
Antonio Ramos Archibold ◽  
Gokmen Demirkaya ◽  
Saeb Besarati ◽  
D. Yogi Goswami ◽  
...  
Keyword(s):  
Power Plants ◽  
Rankine Cycle ◽  
Ammonia Concentration ◽  
Combined Cycle ◽  
Working Fluid ◽  
Base Case ◽  
Water Mixture ◽  
Solar Power Plants ◽  
Combined Cycles ◽  
The Cost

Improving the efficiency of thermodynamic cycles plays a fundamental role in reducing the cost of solar power plants. These plants work normally with Rankine cycles which present some disadvantages due to the thermodynamic behavior of steam at low pressures. These disadvantages can be reduced by introducing alternatives such as combined cycles which combine the best features of each cycle. In this paper a combined Rankine-Goswami cycle (RGC) is proposed and a thermodynamic analysis is conducted. The Goswami cycle, used as a bottoming cycle, uses ammonia-water mixture as the working fluid and produces power and refrigeration while power is the primary goal. This bottoming cycle, reduces the energy losses in the traditional condenser and eliminates the high specific volume and poor vapor quality presented in the last stages of the lower pressure turbine in the Rankine cycle. In addition, the use of absorption condensation in the Goswami cycle, for regeneration of the strong solution, allows operating the low pressure side of the cycle above atmospheric pressure which eliminates the need for maintaining a vacuum pressure in the condenser. The performance of the proposed combined Rankine-Goswami cycle, under full load, was investigated for applications in parabolic trough solar thermal plants for a range from 40 to 50 MW sizes. A sensitivity analysis to study the effect of the ammonia concentration, condenser pressure and rectifier concentration on the cycle efficiency, network and cooling was performed. The results indicate that the proposed RGC provide a difference in net power output between 15.7 and 42.3% for condenser pressures between 1 to 9 bars. The maximum effective first law and exergy efficiencies for an ammonia mass fraction of 0.5 are calculated as 36.7% and 24.7% respectively for the base case (no superheater or rectifier process).

Performance Analysis of a Rankine Cycle Integrated With the Goswami Combined Power and Cooling Cycle

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Ricardo Vasquez Padilla ◽  
Antonio Ramos Archibold ◽  
Gokmen Demirkaya ◽  
Saeb Besarati ◽  
D. Yogi Goswami ◽  
...  
Keyword(s):  
Power Plants ◽  
Rankine Cycle ◽  
Ammonia Concentration ◽  
Working Fluid ◽  
Base Case ◽  
Water Mixture ◽  
Solar Power Plants ◽  
Combined Cycles ◽  
The Cost ◽  
Net Power Output

Improving the efficiency of thermodynamic cycles plays a fundamental role in reducing the cost of solar power plants. These plants work normally with Rankine cycles which present some disadvantages due to the thermodynamic behavior of steam at low pressures. These disadvantages can be reduced by introducing alternatives such as combined cycles which combine the best features of each cycle. In this paper, a combined Rankine–Goswami cycle (RGC) is proposed and a thermodynamic analysis is conducted. The Goswami cycle, used as a bottoming cycle, uses ammonia–water mixture as the working fluid and produces power and refrigeration while power is the primary goal. This bottoming cycle, reduces the energy losses in the traditional condenser and eliminates the high specific volume and poor vapor quality presented in the last stages of the lower pressure turbine in the Rankine cycle. In addition, the use of absorption condensation in the Goswami cycle, for regeneration of the strong solution, allows operating the low pressure side of the cycle above atmospheric pressure which eliminates the need for maintaining a vacuum pressure in the condenser. The performance of the proposed combined Rankine–Goswami cycle, under full load, was investigated for applications in parabolic trough solar thermal plants for a range from 40 to 50 MW sizes. A sensitivity analysis to study the effect of the ammonia concentration, condenser pressure, and rectifier concentration on the cycle efficiency, network, and cooling was performed. The results indicate that the proposed RGC provide a difference in net power output between 15.7% and 42.3% for condenser pressures between 1 and 9 bars. The maximum effective first law and exergy efficiencies for an ammonia mass fraction of 0.5 are calculated as 36.7% and 24.7%, respectively, for the base case (no superheater or rectifier process).

scholarly journals HTR-Based Power Plants’ Performance Analysis Applied on Conventional Combined Cycles

2015 ◽  
Vol 2015 ◽  
pp. 1-11
Author(s):  
José Carbia Carril ◽  
Álvaro Baaliña Insua ◽  
Javier Romero Gómez ◽  
Manuel Romero Gómez
Keyword(s):  
Carbon Dioxide ◽  
Power Plants ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Working Fluid ◽  
Safety Standards ◽  
Intermediate Heat Exchanger ◽  
Combined Cycles ◽  
Effective Cost ◽  
Cycle Structures

In high temperature reactors including gas cooled fast reactors and gas turbine modular helium reactors (GT-MHR) specifically designed to operate as power plant heat sources, efficiency enhancement at effective cost under safe conditions can be achieved. Mentioned improvements concern the implementation of two cycle structures: (a), a stand alone Brayton operating with helium and a stand alone Rankine cycle (RC) with regeneration, operating with carbon dioxide at ultrasupercritical pressure as working fluid (WF), where condensation is carried out at quasicritical conditions, and (b), a combined cycle (CC), in which the topping closed Brayton cycle (CBC) operates with helium as WF, while the bottoming RC is operated with one of the following WFs: carbon dioxide, xenon, ethane, ammonia, or water. In both cases, an intermediate heat exchanger (IHE) is proposed to provide thermal energy to the closed Brayton or to the Rankine cycles. The results of the case study show that the thermal efficiency, through the use of a CC, is slightly improved (from 45.79% for BC and from 50.17% for RC to 53.63 for the proposed CC with He-H2O operating under safety standards).

Biomass combined cycles based on externally fired gas turbines and organic Rankine expanders

2011 ◽  
Vol 225 (8) ◽  
pp. 1066-1075 ◽  
Author(s):  
C M Invernizzi ◽  
P Iora ◽  
R Sandrini
Keyword(s):  
Gas Turbines ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Economic Feasibility ◽  
Maximum Efficiency ◽  
Working Fluid ◽  
Inlet Temperature ◽  
System A ◽  
Combined Cycles

This article investigates the possibility to enhance the performance of a biomass organic Rankine cycle (ORC) plant by adding an externally fired gas turbine (EFGT), yielding a combined EFGT + ORC system. A typical ORC configuration is first modelled and validated on data available from an existing unit 1.5 MW reference plant. Then, different working fluids belonging to the methyl-substituted benzene series and linear methylpolysiloxanes have been evaluated for the ORC section on the basis of both thermodynamics considerations and design issues of the regenerator and the turbine. Results of the simulations of the combined cycle (CC) referred to a furnace size of about unit 9 MW, assuming a maximum GT inlet temperature of 800 °C, show a maximum efficiency of 23 per cent, obtained in the case where toluene is adopted as a working fluid for the bottoming section. This value is about 4 points per cent higher than the efficiency of the corresponding simple ORC. Finally, to conclude, some preliminary considerations are given regarding the techno-economic feasibility of the combined configuration, suggesting the need of a further investigation on the possible technological solution for the furnace which represents the main uncertainty in the resulting costs of the CC.

scholarly journals Combined Closed Cycle (C3) Systems for Underwater Power Generation

1992 ◽  
Author(s):  
Aristide Massardd ◽  
Gian Marid Arnulfi
Keyword(s):  
Power Generation ◽  
Power Plants ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Primary Energy ◽  
Combined Cycle ◽  
Working Fluid ◽  
Mass Reduction ◽  
Efficiency Increase

In this paper three Closed Combined Cycle (C3) systems for underwater power generation are analyzed. In the first, the waste heat rejected by a Closed Brayton Cycle (CBC) is utilized to heat the working fluid of a bottoming Rankine Cycle; in the second, the heat of a primary energy loop fluid is used to heat both CBC and Rankine cycle working fluids; the third solution involves a Metal Rankine Cycle (MRC) combined with an Organic Rankine Cycle (ORC). The significant benefits of the Closed Combined Cycle concepts, compared to the simple CBC system, such as efficiency increase and specific mass reduction, are presented and discussed. A comparison between the three C3 power plants is presented taking into account the technological maturity of all the plant components.

Organic Rankine Cycle as Bottoming Cycle to a Combined Brayton and Clausius - Rankine Cycle

2013 ◽  
Vol 597 ◽  
pp. 87-98
Author(s):  
Dariusz Mikielewicz ◽  
Jan Wajs ◽  
Elżbieta Żmuda
Keyword(s):  
Power Plant ◽  
Power Plants ◽  
Large Scale ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Working Fluid ◽  
Preliminary Evaluation ◽  
Organic Fluids ◽  
Steam Cycle

A preliminary evaluation has been made of a possibility of bottoming of a conventional Brayton cycle cooperating with the CHP power plant with the organic Rankine cycle installation. Such solution contributes to the possibility of annual operation of that power plant, except of operation only in periods when there is a demand for the heat. Additional benefit would be the fact that an optimized backpressure steam cycle has the advantage of a smaller pressure ratio and therefore a less complex turbine design with smaller final diameter. In addition, a lower superheating temperature is required compared to a condensing steam cycle with the same evaporation pressure. Bottoming ORCs have previously been considered by Chacartegui et al. for combined cycle power plants [ Their main conclusion was that challenges are for the development of this technology in medium and large scale power generation are the development of reliable axial vapour turbines for organic fluids. Another study was made by Angelino et al. to improve the performance of steam power stations [. This paper presents an enhanced approach, as it will be considered here that the ORC installation could be extra-heated with the bleed steam, a concept presented by the authors in [. In such way the efficiency of the bottoming cycle can be increased and an amount of electricity generated increases. A thermodynamic analysis and a comparative study of the cycle efficiency for a simplified steam cycle cooperating with ORC cycle will be presented. The most commonly used organic fluids will be considered, namely R245fa, R134a, toluene, and 2 silicone oils (MM and MDM). Working fluid selection and its application area is being discussed based on fluid properties. The thermal efficiency is mainly determined by the temperature level of the heat source and the condenser conditions. The influence of several process parameters such as turbine inlet and condenser temperature, turbine isentropic efficiency, vapour quality and pressure, use of a regenerator (ORC) will be presented. Finally, some general and economic considerations related to the choice between a steam cycle and ORC are discussed.

A Comparative Thermoeconomic Study of Hybrid Solar Gas-Turbine Power Plants

2013 ◽  
Author(s):  
James Spelling ◽  
Björn Laumert ◽  
Torsten Fransson
Keyword(s):  
Gas Turbine ◽  
Power Plants ◽  
First Generation ◽  
Combined Cycle ◽  
Parabolic Trough ◽  
Electricity Cost ◽  
Trade Offs ◽  
Combined Cycle Plant ◽  
Solar Power Plants ◽  
Combined Cycles

The construction of the first generation of commercial hybrid solar gas-turbine power plants will present the designer with a large number of choices. To assist decision making, a thermoeconomic study has been performed for three different power plant configurations, namely simple- and combined-cycles as well as simple-cycle with the addition of thermal energy storage. Multi-objective optimization has been used to identify Pareto-optimal designs and highlight the trade-offs between minimizing investment costs and minimizing specific CO2 emissions. The solar hybrid combined-cycle plant provides a 60% reduction in electricity cost compared to parabolic trough power plants at annual solar shares up to 20%. The storage integrated designs can achieve much higher solar shares and provide a 7–13% reduction in electricity costs at annual solar shares up to 90%. At the same time, the water consumption of the solar gas-turbine systems is significantly lower than conventional steam-cycle based solar power plants.

Parametric Study of a Combined Power and Cooling Thermodynamic Cycle for Low Temperature Heat Sources

2009 ◽  
Author(s):  
Ricardo Vasquez Padilla ◽  
Gokmen Demirkaya ◽  
D. Yogi Goswami ◽  
Elias L. Stefanakos
Keyword(s):  
Low Temperature ◽  
Parametric Study ◽  
Waste Heat ◽  
Ammonia Concentration ◽  
Combined Cycle ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Working Fluid ◽  
Basic Solution ◽  
Water Mixture

A combined power/cooling cycle, which combines the Rankine and absorption refrigeration cycles, uses ammonia-water mixture as a working fluid and produces power and refrigeration while power is the primary goal. This cycle, also known as the Goswami Cycle, can be used as a bottoming cycle using waste heat from a conventional power cycle or as an independent cycle using low temperature sources such as geothermal and solar energy. This paper presents a parametric analysis of the combined cycle. Parametric study of the cycle was carried out in the commercial software Chemcad 6.1. The thermodynamic property data used in simulations were validated with experimental data. Chemcad model was also compared with simulations previously carried out in the process simulator Aspen Plus. The agreement between the two sets has proved the accuracy of the model developed in Chemcad. Then, optimum operating conditions were found for a range of ammonia concentration in the basic solution, isentropic expander efficiency and boiler pressure. It is shown that the cycle can be optimized for net work, cooling output, effective first and exergy efficiencies.

scholarly journals Applying Kalina Technology to a Bottoming Cycle for Utility Combined Cycles

1987 ◽  
Author(s):  
A. L. Kalina ◽  
H. M. Leibowitz
Keyword(s):  
Combined Cycle ◽  
Cycle Performance ◽  
Working Fluid ◽  
Water Mixture ◽  
Pinch Point ◽  
Kalina Cycle ◽  
Pressure Steam ◽  
Combined Cycles ◽  
Steam Plant ◽  
Steam Cycle

A new power generation technology often referred to as the Kalina cycle, is being developed as a direct replacement for the Rankine steam cycle. It may be applied to any thermal heat source, low or high temperature. Among several Kalina cycle variations there is one that is particularly well suited as a bottoming cycle for utility combined cycle applications. It is the subject of this paper. Using an ammonia/water mixture as the working fluid and a condensing system based on absorption refrigeration principles the Kalina bottoming cycle outperforms a triple pressure steam cycle by 16 percent. Additionally, this version of the Kalina cycle is characterized by an intercooling feature between turbine stages, diametrically opposite to normal reheating practice in steam plants. Energy and mass balances are presented for a 200 MWe Kalina bottoming cycle. Kalina cycle performance is compared to a triple pressure steam plant. At a peak cycle temperature of 950° F the Kalina plant produces 223.5 MW vs. 192.6 MW for the triple pressure steam plant, an improvement of 16.0 percent. Reducing the economizer pinch point to 15° F results in a performance improvement in excess of 30 percent.

Evaluation of the Effect of Firing Temperature, Cycle, Engine Configuration, Components, and Bottoming Cycle on the Overall Thermal Efficiency of an Indirectly Coal-Fired Gas Turbine Based Power Plant

2006 ◽  
Author(s):  
Richard P. Johnston
Keyword(s):  
Power Plant ◽  
Gas Turbine ◽  
Thermal Efficiency ◽  
Power Plants ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Working Fluid ◽  
Turbine Engine ◽  
Combined Cycle Plant ◽  
Plant Power

Potential LHV performance of an indirect coal-fired gas turbine-based combined cycle plant is explored and compared to the typical LHV 35–38 % thermal efficiencies achievable with current coal-fired Rankine Cycle power plants. Plant performance with a baseline synchronous speed, single spool 25:1 pressure ratio gas turbine with a Rankine bottoming cycle was developed. A coal-fired High Temperature Advanced Furnace (HITAF) supplying 2000° F. (1093° C.) hot pressurized air for the gas turbine was modeled for the heat source. The HITAF concept along with coal gas for supplemental heating, are two important parts of the clean coal technology program for power plants. [1,2] From this baseline power plant arrangement, different gas turbine engine configurations with two pressure ratios are evaluated. These variations include a dual spool concentric shaft gas turbine, dual spool non-concentric shaft arrangement, intercooler, liquid metal loop re-heater, free power turbine (FPT) and post HITAF duct burner (DB). A dual pressure Heat Recovery Steam Generator (HRSG) with varying steam pressures to fit conditions is used for each engine. A novel steam generating method employing flash tank technology is applied when a water-cooled intercooler is incorporated. A halogenated hydrocarbon working fluid is also evaluated for lower temperature sub-bottoming Rankine cycle equipment. Current technology industrial gas turbine component performance levels are applied to these various engines to produce a range of LHV gross gas turbine thermal efficiency estimates. These estimates range from the lower thirties to over forty percent. Overall LHV combined cycle plant gross thermal efficiencies range from nearly forty to over fifty percent. All arrangements studied would produce significant improvements in thermal efficiency compared to current coal-fired Rankine cycle power plants. Regenerative inter-cooling, free power turbines, and dual-spool non-concentric shaft gas turbine arrangements coupled with post-HITAF duct burners produced the highest gas turbine engine and plant efficiency results. These advanced engine configurations should also produce operational benefits such as easier starting and much improved part power efficiency over the baseline engine arrangement. An inter-turbine liquid metal re-heat loop reduced engine thermal efficiency but did increase plant power output and efficiency for the example studied. Use of halogenated hydrocarbons as a working fluid would add to plant power output, but at the cost of significant additional plant equipment.

Analysis of a Combined Cycle Plant Using a Small Particle Receiver to Drive a Primary Brayton Cycle

2015 ◽  
Author(s):  
Matthew Miguel Virgen ◽  
Fletcher Miller
Keyword(s):  
Heat Exchanger ◽  
Gas Turbine ◽  
Small Particle ◽  
Power Plants ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Efficiency Gains ◽  
Steam Cycle

All current commercial CSP plants operate at relatively low thermodynamic efficiency due to lower temperatures than similar conventional plants and due to the fact that they all employ Rankine conversion cycles. We present here an investigation on the effects of adding a bottoming steam power cycle to a hybrid CSP plant based on a Small Particle Heat Exchange Receiver (SPHER) driving a gas turbine as the primary cycle. Due to the high operating temperature of the SPHER being considered (over 1000 Celsius), the exhaust air from the primary Brayton cycle still contains a tremendous amount of exergy. While in the previous analysis this fluid was only used in a recuperator to preheat the Brayton working fluid, the current analysis explores the potential power and efficiency gains from instead directing the exhaust fluid through a heat exchanger to power a Rankine steam cycle. Not only do we expect the efficiency of this model to be competitive with conventional power plants, but the water consumption per kilowatt-hour will also be reduced by nearly two thirds as compared to most existing concentrating solar thermal power plants as a benefit of having air as the primary working fluid, which eliminates the condensation step present in Rankine-cycle systems. Coupling a new steam cycle model with the gas-turbine CSP model previously developed at SDSU, a wide range of cases were run to explore options for maximizing both power and efficiency from the proposed CSP combined cycle gas turbine (CCGT) plant. Due to the generalized nature of the bottoming cycle modeling, and the varying nature of solar power, special consideration had to be given to the behavior of the heat exchanger and Rankine cycle in off-design scenarios. The trade-offs of removing the recuperator for preheating the primary fluid are compared to potential overall power and efficiency gains in the combined cycle case.

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