Integrated Solar Combined Cycle System Research Articles

Simulation and Energy Analysis of Integrated Solar Combined Cycle Systems (ISCCS) Using Aspen Plus

The aim of this research is to simulate and analyze a combined power cycle (Steam turbine and gas turbine cycles) by studying the effect of changing the natural gas flow rate on the developed power. Therefore, reducing the amount of used natural gas in the combustion chamber of the gas turbine cycle from 9.2 to 4 kg/s showed a significant drop in the power produced by the gas turbine, i.e., from 123.7 to 57.7 MW. Additionally, this change in the combusted natural gas amount affected the heat recovered in both heat recovery steam generators (HRSGs), i.e., from 219.79 to 100.35 MW, respectively. Consequently, the amount of generated steam in the high pressure HRSGs and the power developed in the steam turbine changed from 60.88 to 27.79 kg/s and from 56.39 to 27.13 MW, respectively. A heat exchanger (HFHX) utilizing a heating fluid was used as an external source of energy to compensate the reduction in the generated heat and to increase the amount of generated steam up to 157.32 kg/s, which keeps the power plant capacity at 180 MW. Existing combined local plant data were used in this study and were simulated in Aspen Plus software V11. A sensitivity analysis was made to optimize the cycle operating conditions that use less natural gas and produce the same amount of power.

Design and Performance Analysis of a Novel Integrated Solar Combined Cycle (ISCC) with a Supercritical CO2 Bottom Cycle

The integrated solar combined cycle (ISCC) system is a proven solution for grid-connected power generation from solar energy. How to further improve the ISCC system efficiency and propose a more efficient system solution has become a research focus. A novel gas turbine combined cycle (GTCC) benchmark system is proposed by replacing the conventional steam Rankine bottom cycle with a supercritical CO2 Brayton cycle, whose output power and efficiency are increased by 9.07 MW and 1.3%, respectively, compared to those of the conventional GTCC system. Furthermore, the novel ISCC systems are established with the parabolic trough solar collector (PTC) and the solar tower (ST) collector coupled to the novel GTCC system. Thermal performance analysis, exergy performance analysis, and the sensitivity analysis of the ISCC systems have been performed, and the results show that the system efficiencies of both ISCC systems are lower than that of the GTCC system, at 57.1% and 57.5%, respectively, but the power generation of the ISCC system with PTC is greater than that of the benchmark system, while that of the ISCC system with ST is less than that of the benchmark system. The photoelectric efficiency of the ISCC system with PTC is 27.6%, which is 2.1% greater than that of ISCC system with ST. In the ISCC system with PTC, the components with the highest exergy destruction and the lowest exergy efficiency are the combustion chamber, and PTC, respectively. ST is the component with the highest exergy destruction and the lowest exergy efficiency in the ISCC system with ST. With the increase in direct normal irradiance (DNI), the total output power, solar energy output power, and photoelectric efficiency of the ISCC system with PTC increase, while the system efficiency decreases; the solar energy output power and photoelectric efficiency of the ISCC system with ST increase, while the total output power and system efficiency decrease. The photoelectric efficiency of the ISCC system with PTC is greater when the DNI is greater than 600 W/m2; conversely, the photoelectric efficiency of the ISCC system with ST is greater. After sensitivity analysis, the optimal intercooler pressure for the ISCC system is 11.3 MPa.

Integration Optimization of Integrated Solar Combined Cycle (ISCC) System Based on System/Solar Photoelectric Efficiency

Integrated solar combined cycle (ISCC) systems play a pivotal role in the utilization of non-fossil energy; however, the efficient application of solar energy has emerged as a primary issue in the study of ISCC systems. Therefore, it is extremely urgent to propose the best optimization scheme for ISCC under different operating conditions. In this paper, according to the idea of temperature matching and cascade utilization, the optimization of the ISCC system is carried out with the genetic algorithm for the whole working conditions, and the optimization schemes with the highest photoelectric efficiency and system efficiency under different working conditions are derived. In comparison with two optimization schemes with different objective functions, the conclusion can be drawn that: At 100% gas turbine load—30% DNI and 100% gas turbine load—100% DNI working conditions, respectively, the maximum system efficiency of 56.32% and the maximum solar photoelectric efficiency of 35.5% are attained. With the decreasing of gas turbine load, the solar energy integration position will gradually change from the topping cycle to the bottom cycle; with the gas turbine load variation from 100% to 75%, the optimal photoelectric efficiency model prefers two-stage integration, and up to 141.3 MW of solar energy could be integrated, which is greater than the maximum value of 127.1 MW for the optimal system efficiency model. Regarding the heat collection choice of bottom cycle, the optimal photoelectric efficiency model prefers the high-pressure boiler (HPB), while the optimal system efficiency model prefers the high-pressure superheater (HPS). The comparison between the optimal solution and the actual cases confirms the correctness of the optimization results and provides guidance for the subsequent ISCC study.

Integrated solar combined cycle system with steam methane reforming: Thermodynamic analysis

The present paper considers an integrated solar combined cycle system (ISCCS) with an utilization of solar energy for steam methane reforming. The overall efficiency was compared with the efficiency of an integrated solar combined cycle system with the utilization of solar energy for steam generation for a steam turbine cycle. Utilization of solar energy for steam methane reforming gives the increase in an overall efficiency up to 3.5%. If water that used for steam methane reforming will be condensed from the exhaust gases, the overall efficiency of ISCCS with steam methane reforming will increase up to 6.2% and 8.9% for β = 1.0 and β = 2.0, respectively, in comparison with ISCCS where solar energy is utilized for generation of steam in steam turbine cycle. The Sankey diagrams were compiled based on the energy balance. Utilization of solar energy for steam methane reforming increases the share of power of a gas turbine cycle: two-thirds are in a gas turbine cycle, and one-third is in a steam turbine cycle. In parallel, if solar energy is used for steam generation for a steam turbine cycle, than the shares of power from a gas and steam turbine are almost equal.

A comparative study between two different techniques of solar integrated systems

• Integrated solar system based on SPT offers the best annual thermal performances. • The solar power tower allows HRSG to operate in fired mode. • Ganapathy’s method is adopted to evaluate the steam mass flow generation. • Noticeable enhancement in solar-to-electric efficiency with a value of about 21%. • ISCC saves about 20.12 million $ of fuel and 0.5 million ton of CO 2 during 30 years. A comparative study between two techniques of solar integration in Integrated Solar Combined Cycle system power plant in terms of thermal performances and economic assessment is carried out in this work. The first system power plant is based on parabolic trough collector technology where solar heat is introduced in the steam power block as a latent heat and the second system runs with a solar power tower technology. The latter integrates solar thermal energy as a sensible heat to heat up the flue gases from the gas turbine till the fired temperature before entering the heat recovery steam generator. Thermodynamic investigations show high thermal performance for both thermal power plants, but the system plant with solar tower exhibits the best annual performances efficiency value of about 57.2%. Furthermore, in terms of solar conversion to electricity, the plant based on solar tower reveals noticeable enhancements; almost constant values during the year of about 20.8% have been registered. In terms of economic analysis, both power plants show approximately the same Levelized cost of energy of 0.0395 $/kWh and 0.0355 $/kWh for the plant based solar tower and that based parabolic collector respectively.

Simulation Study of Integrated Solar Combined Cycle Systems: Medium Scale Plant in Irbid City

Simulation Study of Integrated Solar Combined Cycle Systems: Medium Scale Plant in Irbid City

Exergy, Exergoeconomic, Exergoenvironmental, Emergy-based Assessment and Advanced Exergy-based Analysis of an Integrated Solar Combined Cycle Power Plant

The high amount of solar energy as clean and sustainable energy has increased awareness in solar energy concentration, especially in integrated concepts. One of the best and promising hybrid configurations for converting solar energy into power is an integrated solar combined cycle system (ISCCS). In this study, conventional and advanced analysis tools for the ISCCS located in Yazd (Iran) have been investigated. In this paper, thermodynamic simulation, exergy, exergoeconomic, and exergoenvironmental analysis based on Life Cycle Assessment (LCA) have been performed. In addition, an emergy-based concept, including emergoeconomic and emergoenvironmental assessment, has been performed. In-depth analysis of exergy, exergoeconomic, and exergoenvironmental modelling, advanced exergy analysis based on endogenous/exogenous and avoidable/unavoidable parts have been done. In this regard, MATLAB code has been developed for thermodynamic simulation, exergy, exergoeconomic, exergoenvironment, emergoeconomic and emergoenvironment analysis. Furthermore, THERMOFLEX (commercial software) applied for thermodynamic simulation and verification. The Sankey diagram based on each analysis tool has been constructed. Furthermore, the priority of improvement based on each analysis has been identified. The thermal efficiency and net power generation of ISCCS are 48.25% and 419600 kW, respectively. It was obsereved that in most equipment, less than 10% of exergy destruction and cost and environmental impact rates were avoidable/endogenous.

General performance evaluation method of integrated solar combined cycle (ISCC) system

As a novel solar energy utilization method, integrated solar combined cycle (ISCC) system has the advantages of low investment and high efficiency, and has been paid more and more attention. How to evaluate the effectiveness of solar energy integration in different ISCC systems has become a significant issue. In this paper, based on the second law of thermodynamics and the principle of energy cascade utilization, according to different kinds of integration methods, different kinds of basic ISCC system models are divided and established; Compared with the gas turbine combined cycle (GTCC) system and solar energy generating system (SEGS), the effects caused by the integration of solar energy are revealed: the superimposed effect of the fuel saving factor and the efficiency enhancement of efficiency promotion factor are given. The comprehensive evaluation factor with simultaneous consideration of both the fuel saving factor and the efficiency promotion factor is put forward. Meanwhile, the applications of this evaluation factor in actual cases of this evaluation factor are also studied. This paper provides a novel evaluation method for comprehensively evaluate two different ISCC systems which will propose valuable guidance for further evaluation research of ISCC system.

Comprehensive evaluation of integrated solar combined cycle system regarding fuel-savability under unified framework

Integrated Solar Combined Cycle (ISCC) system is considered as a promising route to efficiently utilize both solar energy and fossil fuel. However, due to the absence of a unified framework, it is difficult to fairly compare the performance between numerous proposed integration schemes. In the present work, firstly, a generalized model of ISCC system is proposed with validation, based on which the unified expression of fuel-savability is derived for performance evaluations between different integration schemes under a common framework. Secondly, the “allocation effect” expressed by the “bridging” term of the unified expression is revealed that the proportion of total input exergy allocated to the Brayton and Rankine cycles varies due to the solar integration. Thirdly, the “superposition effect” is revealed that the total system fuel-savability is comprehensively determined by the superposed sum of the “basic” term, which is the direct benefit of local solar integration, the “floating” term, which stands for the explicit influence of solar integration on each main component, and the “bridging” term, which stands for the implicit inter-cycle influence of solar integration. Fourthly, six individual cases of ISCC schemes have been evaluated by the proposed unified expression as the example of practical application. Finally, the two above-mentioned effects have been further extended to be compatible with more complicated solar-integrated multicycle-combined system and the unified expression form of fuel-savability is rationally generalized, which may provide theoretical guidance for the future research and applications.

Hybrid concentrating solar-landfill gas power-generation concept for landfill energy recovery

In the present study, new approaches for Landfill gas (LFG) energy recovery from operating and decommissioning landfills were examined. LFG energy recovery is already a reality in several developed and developing countries. Here, to improve performance in the electricity generation, the hybridization of LFG with other landfill-readily available energy sources, namely solar thermal, waste incineration and syngas from waste gasification, is explored through numerical simulation. The arrangement examined comprised of Integrated Solar Combined Cycle System. Several scenarios were tested with different configurations and operational modes. Results have shown that the hybridization of LFG powered gas turbine with solar energy in a combined cycle arrangement made it possible to more than double system power rating when compared to gas turbine alone. However, power generation would be highly dependent on the ratio between the solar field and landfill areas. The addition of a supplementary of landfill-readily available energy source, either by waste incineration or gasification, compensates for this drawback and might be the best option for landfill power generation or combined heat and power. Economic analysis showed promising results but with some uncertainty.

Survey about impact voltage instability and transient stability for a power system with an integrated solar combined cycle plant in Iraq by using ETAP

The Analyses for power systems are more necessary for the designing, operating phase execution control and to make sure safe network operations by sufficient protection project settings. In this article, we have prepared a sufficient scientific survey about the electrical model of a 340 MW integrated solar combined cycle system (ISCCS) located in the Iraqi southern, is developed and simulation by a program called Electrical Transient Analyzer Program (ETAP) and carry out throw this program the load flow, voltage stability and short circuit analyses for this power plant with part of the national grid in Al-Basra city in an industrial region. The effect of voltage instability for the grid on system buses (load buses) of the power system is estimated. By using load flow analysis as a case study by using the Newton-Raphson algorithm, when the load buses operating at down voltage because of instability voltage of the power grid are specified and their voltages are should to improved according to given voltage limitations that are depended on buses criticality with regard to loads. The appliance on-load tap changers of the transformer and reactive power compensation are used to improve steady-state voltage stability for any instability system. The method of the optimal position for capacitor banks placement is meaning the number of capacitor banks is proposed to adding to the weak buses by using the optimal capacitor placement module of ETAP. Energy is actually required for the expansion of our country. To sustain the generation of electric power at an adequate level power system supplies power to different types of loads that are located far away from the generating plants using transmission lines.

Solar desalination tower, novel design, for power generation and water distillation using steam only as working fluid

The use of sustainable energy resources is indispensable nowadays. This paper studies a new solar chimney plant for electrical power generation and water distillation. The operating mechanism of the power plant is based on evaporating seawater using concentrated solar power techniques. The novelty of the proposed system is using steam only as working fluid; also, the collector area is separated away from the solar chimney. The solar field absorbs and transfers solar energy into the steam generator. As steam passes through the chimney, the vapor exchanges the heat with the outside environment resulting in water condensation at the inner surface of the chimney. A set of equations have been developed, and a hybrid integrated solar combined cycle (ISCC) is constructed for comparison purposes. In general, the results show that the proposed system can improve the efficiency of the solar utilization of the new solar chimney with 78% more than the conventional ISCC system. The geometrical dimensions of the solar field and chimney of the new system are smaller than the traditional one; therefore, the estimated capital cost ($/m2) will be relatively less.

Operation strategy and dynamic performance study of integrated solar combined-cycle system

Integrated solar combined-cycle (ISCC) system has better thermal performance than the original gas steam combined-cycle system and a lower initial investment than stand-alone solar thermal plants. However, due to the uncertainty of meteorological conditions, the operation condition of the ISCC system changes continuously. In this study, a dynamic model of the ISCC system is built, and the operation strategies of two ISCC systems with and without the heat storage system are proposed. Accordingly, the dynamic performances of these two ISCC systems on a typical day are compared and analyzed, and the response characteristics of main operation parameters, such as main steam parameters and solar energy power generation, concerning direct normal irradiance (DNI) are obtained. The results show that the stability and security of the ISCC system with a heat storage system are superior to those without the heat storage system during the operation. To verify whether the operation strategy of the ISCC system with heat storage system is universally adaptable under different meteorological conditions, the dynamic performances of the ISCC system are further studied on a good-weather day with a strong DNI and a bad-weather day with weak DNI, respectively.

Off-design performance characteristics study on ISCC system with solar direct steam generation system

Integrated solar combined cycle (ISCC) system can make full use of solar energy, improves the system thermal efficiency and reduces the fossil fuel consumption. In this paper, the model of ISCC system is established by using the Aspen Plus and Ebsilon. The off-design operation performance characteristics of the gas turbine cycle (GTC), steam turbine cycle (STC) and ISCC system are investigated under different gas turbine off-design operation modes. And the thermal performances of ISCC system under different environmental conditions are also analyzed. The research results show that the impact of the gas turbine off-design operation mode on the STC is more significant than that on the GTC, so in order to obtain the optimum operation performance of the ISCC under off-design conditions, the inlet guided valve (IGV) of air compressor should be adjusted accordingly, which can ensure that the efficiency of STC keeps at a high level. The effect of environmental conditions on the GTC is greater than that on the STC. The influence of the ambient temperature on ISCC system is greater than the influence of DNI on ISCC system. The achievements from this paper will provide valuable references for system design and operation optimization of ISCC system.

Recent Developments in Integrated Solar Combined Cycle Power Plants

Global concern for depleting fossil fuel reserves have been compelling for evolving power generation options using renewable energy sources. The solar energy happens to be a potential source for running the power plants among renewable energy sources. Integrated Solar Combined Cycle (ISCC) power plants have gained popularity among the thermal power plants. Traditional ISCC power plants use Direct Steam Generation (DSG) approach. However, with the DSG method, the ISCC plant’s overall thermal efficiency does not increase significantly due to variations in the availability of solar energy. Thermal Energy Storage (TES) systems when integrated into the solar cycle can address such issues related to energy efficiency, process flexibility, reducing intermittency during non-solar hours. This review work focuses and discusses the developments in various components of the ISCC system including its major cycles and related parameters. The main focus is on CSP technologies, Heat Transfer Fluid (HTF), and Phase Change Material (PCM) used for thermal energy storage. Further, study includes heat enhancement methods with HTF and latent heat storage system. This study will be beneficial to the power plant professionals intending to modify the solar-based Combined Cycle Power Plant (CCPP) and to retrofit the existing Natural Gas Combined Cycle (NGCC) plant with the advanced solar cycle.

Enhanced exergy-based malfunction diagnosis of an integrated solar combined cycle system: parametric study and multi-objective optimisation

In this research, a malfunction diagnosis method based on the enhanced exergy concept is applied to quantify the anomalies' sources in a real integrated solar combined cycle system (ISCCS). A comprehensive parametric study is performed to evaluate the malfunction indicators and the overall performance of the power plant by varying the substantial operating parameters under single and multi-malfunction conditions. Then, the fast and elitist non-dominated sorting genetic algorithm (NSGA-II) is applied to maximise the net power and minimise the total exergy destruction rate of the system under a multi-malfunction condition.

Enhanced exergy-based malfunction diagnosis of an integrated solar combined cycle system: parametric study and multi-objective optimisation

In this research, a malfunction diagnosis method based on the enhanced exergy concept is applied to quantify the anomalies' sources in a real integrated solar combined cycle system (ISCCS). A comprehensive parametric study is performed to evaluate the malfunction indicators and the overall performance of the power plant by varying the substantial operating parameters under single and multi-malfunction conditions. Then, the fast and elitist non-dominated sorting genetic algorithm (NSGA-II) is applied to maximise the net power and minimise the total exergy destruction rate of the system under a multi-malfunction condition.

Thermodynamic Investigation of an Integrated Solar Combined Cycle with an ORC System.

An integrated solar combined cycle (ISCC) with a low temperature waste heat recovery system is proposed in this paper. The combined system consists of a conventional natural gas combined cycle, organic Rankine cycle and solar fields. The performance of an organic Rankine cycle subsystem as well as the overall proposed ISCC system are analyzed using organic working fluids. Besides, parameters including the pump discharge pressure, exhaust gas temperature, thermal and exergy efficiencies, unit cost of exergy for product and annual CO2-savings were considered. Results indicate that Rc318 contributes the highest exhaust gas temperature of 71.2℃, while R113 showed the lowest exhaust gas temperature of 65.89 at 800 W/m2, in the proposed ISCC system. The overall plant thermal efficiency increases rapidly with solar radiation, while the exergy efficiency appears to have a downward trend. R227ea had both the largest thermal efficiency of 58.33% and exergy efficiency of 48.09% at 800W/m2. In addition, for the organic Rankine cycle, the exergy destructions of the evaporator, turbine and condenser decreased with increasing solar radiation. The evaporator contributed the largest exergy destruction followed by the turbine, condenser and pump. Besides, according to the economic analysis, R227ea had the lowest production cost of 19.3 $/GJ.

Study and Analysis the Performance of Two Integrated Solar Combined Cycle

The performance of two layouts of integrated solar combined cycle (ISCC) are analyzed and compared with reference combined cycle in this study. Detailed models of the proposed cycles were developed in Mathcad environment to evaluate the cycle’s performance. The results show that the power of steam bottoming cycle is increased to about 43 MW that is about 8 % of total power of ISCC represent the solar fraction of the plant in summer period. Less increase is observed of about 12 MW at midday in winter months with soar fraction reaches to 3%. Moreover, an annual evaluation of the ISCC system’s output power is carried out, to assess the annual performance of the cycles.

Performance Study of a Novel Integrated Solar Combined Cycle System

Based on a traditional integrated solar combined cycle system, a novel integrated solar combined cycle (ISCC) system is proposed, which preferentially integrates the solar energy driven lithium bromide absorption refrigeration system that is used to cool the gas turbine inlet air in this paper. Both the Aspen Plus and EBSILON softwares are used to build the models of the overall system. Both the thermodynamic performance and economic performance of the new system are compared with those of the traditional ISCC system without the inlet air cooling process. The new system can regulate the proportions of solar energy integrated in the refrigerator and the heat recovery steam generator (HRSG) based on the daily meteorological data, and the benefits of the solar energy integrated with the absorption refrigeration are greater than with the HRSG. The results of both the typical day performance and annual performance of different systems show that the new system has higher daily and annual system thermal efficiencies (52.90% and 57.00%, respectively), higher daily and annual solar photoelectric efficiencies (31.10% and 22.31%, respectively), and higher daily and annual solar photoelectric exergy efficiencies (33.30% and 23.87%, respectively) than the traditional ISCC system. The solar energy levelized cost of electricity of the new ISCC system is 0.181 $/kW·h, which is 0.061 $/kW·h lower than that of the traditional ISCC system.