Flexible electricity dispatch for CSP plant using un-fired closed air Brayton cycle with particles based thermal energy storage system (original) (raw)
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SOLARPACES 2019: International Conference on Concentrating Solar Power and Chemical Energy Systems
In this work, it is investigated about the application of an Integrated Solar Combined Cycle (ISCC) that uses particles as heat transfer fluid at the receiver and as the storage medium to provide flexible electricity dispatch without any supplementary gas burning. The paper investigates two cornerstones' of concentrating solar power technologies (CSP); i.e., the application of highly efficient power cycles and the ability to meet grid demand throughout flexible dispatch strategy. Using particles for the solar loop allows meeting both requirements at the same time. On the one hand, very high temperature can be achieved on the solar receiver which enables the use of highly-efficient power cycles according to thermodynamics second statement. On the other hand, particles ease for handling and storage makes them suitable for thermal storage at CSP applications which results into flexible electricity dispatch of the power block. Results shown in this paper prove the feasibility of flexible electricity dispatch of particles-based ISCC following real curve demand.
Optimal Dynamic Dispatch of Wind Integrated Thermal Generators with Compressed Air Energy Storage
International Journal of Renewable Energy Research, 2014
Maintaining reliability of power supply is a big challenge when renewable energy sources (RES) are integrated in the traditional power grid. Allocation of adequate storage of energy is essential in order to maintain power balance with changing demand levels and uncertain and intermittent renewable power generation. After the Kyoto protocol on climate change there is global focus on limiting emissions from fossil fuels. As a result increasing number of RES is being integrated with existing power grids. Their intermittent and uncertain nature however creates difficulty in maintaining reliability particularly when large scale integration of these resources is planned. Efficient energy storage systems are therefore essential to store surplus power when renewable generation is in abundance and to release it during periods when renewable generation is insufficient. This paper explores the viability of operating wind farm coupled with compressed air energy storage (CAES) system to meet the demand in a reliable manner and control the electricity prices during peak loads. The optimal dispatch of thermal units is computed using an improved particle swarm optimization (PSO) such that all thermal, wind generator and CAES system constraints are satisfied. A 24-hour dispatch period is considered by applying thermal generator ramp-rate limits between consecutive time periods. Two separate models are employed for optimizing cost and profit. The proposed method is tested on a test power system consisting of six thermal generating units integrated with 50 wind turbines.
A Case of Study of a Concentrating Solar Power Plant with Unfired Joule-Brayton Cycle
Energy Procedia, 2015
A solar closed air Brayton cycle, with rated power of 50 MW, was considered. The system is composed of a concentrating solar tower with volumetric receiver, an intercooling and regenerating gas turbine and an evaporative tower cooling system. The characteristic feature of the system is a control strategy able to adjust the plant in a large range of load, maintaining net electric conversion efficiency almost constant. The concentrating solar power (CSP) plant operates without adding fuel and can heat air up to a maximum temperature of 850 °C, at the solar tower outlet. The numerical analysis was performed by SAM for the solar tower and by Thermoflex © for the assessment of the performance of the whole system. The thermal energy input was calculated on the basis of the DNI of the TMY from Seville. Results show an electricity production greater than 75GWh per year, with a significant sparing fossil fuel consumption and avoided CO 2 emissions.
The CSP (Concentrated Solar Power) Plant with Brayton Cycle: A Third Generation CSP System
American Journal of Modern Energy
The main goal of this study is that electricity unit price is lower than 6 cents (US) producing in a CSP (Concentrated Solar Power) plant. For this goal, the paper suggests an integrated facility with thermal energy storage. The plant includes heliostat area, air cavity receiver, gas turbine package (compressor, combustion chamber and generator), steam turbine and generator, heat exchanger, sensible thermal energy storage system and condenser. The process details are heated air through SIC (Silicon Carbide) air cavity tube receiver will be sent to the gas turbine (Brayton Cycle) and hot air from output of gas turbine will be source to heat exchanger to steam production. Steam from output of the heat exchanger will be supplied to the TES (Thermal Energy Storage) for its charging and second turbine (Rankine Cycle) for to generate electricity. Thus, the total efficiency of the plant reaches 55% during sunshine. Assumptions that is to calculate unit price are several schedules and interest rates for every year and amortization and taxation are ignored. With these assumptions, the paper's aim is achieving the goal with 5.7 US ¢/kWh e for 13 years return time, %3 interest rate without subsidizing.
Preliminary tests of an integrated gas turbine-solar particle heating and energy storage system
AIP Conference Proceedings, 2018
Worldwide research efforts are aiming to push the operating temperature limit of CSP systems to improve efficiency and, as a result, the levelized cost of electricity. Furthermore, with higher operating temperatures, a number of new concepts become feasible, the most important of which are supercritical CO2 cycles and air Brayton cycles. Hybrid CSP-fossil fuel systems fall within the air Brayton family of concepts, where the solar field is used to preheat air, while a fossil fuel is burned to bring the air temperature to the firing temperature of a gas-fired Brayton turbine. To make this approach more attractive and environmentally friendly, it is desirable to maximize the solar "contribution" and minimize fuel assistance. This can be done by using novel receivers that increase the air temperature significantly and/or employing a recuperator, where the operating pressure and temperature are lower than conventional Brayton cycles. This paper presents information about an experimental integrated gas turbine-solar particle heating system that uses the hybrid approach. The system is located on the campus of King Saud University in Riyadh, Saudi Arabia and has a peak thermal power of 300 kW. In addition to providing details about the individual components and how they are integrated, the paper explains the start-up procedure, which consists of preheating the system with the heliostat field, followed by additional heating from the turbine itself until the nominal heat exchanger operating temperature is reached, at which point on-sun operation can commence. The study shows that solar preheating requires one to two days to complete, followed by a few hours of heating by the turbine to bring the temperature to about 560°C. Furthermore, with a temperature rise of up to 180°C in the particle heating receiver (and a drop of 10°C in the particle conveyor), the maximum particle temperature will approach 730°C, making the solar contribution significant. As larger scale systems will naturally allow for larger particle drop heights and higher temperature rises in the receiver, it is envisaged that maximum particle tempertures in those systems will approach the firing temperatures of recuperated turbines, making this solution technically, economically, and environmentally worth considering.
2016
Flexible dispatch able solar thermal electricity plants applying state of the art power cycles have the potential of playing a vital role in modern electricity systems and even participating in the ancillary market. By replacing molten salt via particles, operation temperatures can be increased and plant efficiencies of over 45 % can be reached. In this work the concept for a utility scale plant using corundum as storage/heat transfer material is thermodynamically modeled and its key performance data are cited. A novel indirect fluidized bed particle receiver concept is presented, profiting from a near black body behavior being able to heat up large particle flows by realizing temperature cycles over 500°C. Specialized fluidized bed steam-generators are applied with negligible auxiliary power demand. The performance of the key components is discussed and a rough sketch of the plant is provided.
International Journal of Heat and Technology, 2016
In this paper, a solar tower power plant with a closed Joule-Brayton cycle, of 5 MW rate power, with molten salts thermal storage, located in Seville is presented. The peculiarity of the cycle, using air like fluid work, is to vary, by an auxiliary compressor and a vent valve, the pressure, so that fluid average density, at gas turbine inlet. An adjustment of the mass flow rate, in order to regulate the exit air temperature from the receiver of concentrating solar tower, is obtained. During energy surplus production, the thermal storage energy is loaded. Particular attention is placed to the energy thermal storage, which uses molten salt KCl-MgCl2, suitable for this application due to its high melting temperature, in double tank configuration. The thermodynamic model of the entire plant was implemented using Thermoflex ® software, while, for the concentrating tower, WinDelsol software was used. Using time data relating to the locations, the performance of the entire plant, during a year, has been simulated. Preliminary results show that this plant can achieve relevant benefits in total energy production and equivalent operation hours per year, therefore it is competitive with conventional energy production systems. Furthermore, a performances estimation with a cost analysis, using a LCOE parametric analysis, has been performed.
Integrated power generation cycle (Kalina cycle) with auxiliary heater and PCM energy storage
Energy Conversion and Management, 2018
Kalian cycle is a modified Rankine cycle for power generation, that its working fluid is a mixture of ammoniawater instead of pure water and can be driven in higher temperatures comparing to the Rankine cycle. In this study a hybrid Kalina power cycle and solar thermal flat plate collector using phase change material (PCM) as thermal energy storage material is introduced and analyzed. Bandar Aabas (a city in south of Iran), because of its sunny days and use of the Persian Gulf sea water for cooling in the condenser has been selected. The amount of solar fraction in year is 83.8%. This integrated process requires 53.85 GWh heat load during the year that 45.13 GWh of energy per year in the system, is supplied by the sun during the hours of 7-19 and released energy from the PCM during the night from 19.01 to 6.59. Rest of the needed heat load for the integrated system of 8.72 GWh per year is provided with auxiliary heater. By using energy and exergy balance equations, all components were analyzed. According to the results, thermal efficiency of the Kalina cycle is 6.12%. Results of the exergy analyses show 23.21% of the total destroyed exergy in the cycle, occurred in one of the heat exchangers as the main component wasting exergy. Also it was found that most the exergy efficiency is related to the one of the heat exchangers and flash separator with 99.24% and 99.11%, respectively.
International Journal of Renewable Energy Research, 2014
The renewable resource, mainly the solar energy, can be used to produce electric energy on a large scale in solar thermal power stations, which concentrate sunlight at temperatures which range between 200° to 1200° C and even more. This paper presents a conceptual configuration of a solar powered combined cycle power plant with a topping air Brayton cycle and a bottoming steam Rankine cycle. The conventional gas turbine (GT) combustion chamber is replaced by a high-temperature solar thermal air heating system. During the daytime, a part of the exhaust air from the GT is bypassed to produce superheated steam in the heat recovery steam generator (HRSG), which in turn runs a steam turbine and the remaining exhaust air from GT is utilized to charging molten salt, which acts as a storage medium. The heat energy of the molten salt is utilized to generate steam for 4 hours in another HRSG, when sunlight is not available. From the thermodynamic analysis, it is found that for the base case GT pressure ratio of 4, power obtained from the GT block is 1.75 MW, while total power obtained from the combined cycle is 2.28 MW. The overall thermal efficiency of the combined cycle at this pressure ratio is 25.39%. The pressure ratio of the gas turbine has been varied from 2 to 20 and the optimum pressure ratio has been found out where total power output of the combined cycle plant is maximum.