Influence of the steam generator on the exergetic and exergoeconomic analysis of solar tower plants

Abstract

Solar power tower plants differ from conventional power plants in the steam generator design due to the higher heat duty. In this work, the influence of the steam generator heat exchangers (preheater, evaporator, superheater and reheater) on a solar power plant with molten salt receiver and thermal storage is studied for the first time. Energy, exergy and exergoeconomic analyses give a complete view of the cost flows within the system. The pinch point temperature difference in the evaporator is used as the main variable as it changes the steam generator design and the operating conditions of the plant, such as the inlet temperature of the receiver and the salt mass flow. All heat exchangers are designed and optimized at minimum cost for each pinch point to fulfill the thermomechanical limitations of TEMA standards and Pressure Vessel code. The field of heliostats, molten-salt receiver and the power-block (110 MWe) designs are kept constant throughout the paper. A low pinch point should be used to minimize the plant exergy destruction while the exergoeconomic approach obtains an optimum pinch point around 2-3ºC. Furthermore, the low exergoeconomic factor values show that the heat exchangers of the SG are crucial for the plant operation.

Design parameter modelling of solar power tower system using adaptive neuro-fuzzy inference system optimized with a combination of genetic algorithm and teaching learning-based optimization algorithm

“…Economic and exergetic analyses by González-Gómez et al [33] and Gómez-Hernández et al [34] have shown steam generator relevance to the whole SPTS performance. Gómez-Hernández et al [35] proposed a new steam generator design with dual-pressure level evaporation working with a higher inlet pressure up to 165 bar, aiming to improve the power block efficiency.…”

Molten Salt Storage for Power Generation

“…-Heat exchangers for flue gas from a gas turbine peak power plant [57] -Heat exchangers for thermal oil [58] -Steam generators [59][60][61][62][63] Besides power and storage components, there are some additional molten salt components, as well as fundamental and process technology related aspects of technological importance. Objectives are for example enhanced reliabilities, higher operation temperatures and higher measurement accuracies, as well as reduced OPEX and CAPEX.…”

Review on Performance Analysis of the Power Block in Concentrated Solar Power Plants

“…[ 43 ] Gomez–Hernandez et al investigated the influence of the pinch point temperature difference of CSP heat exchangers on exergy destruction and exergy efficiency, including preheater, evaporator, superheater, and reheater, on the operation performance of the steam generator system. [ 41 ] The results in Figure 7 show that the increase in pinch point will increase exergy destruction and reduce exergy efficiency.…”

“…Then, they presented the cost rate balance equation and the auxiliary equations for each device to conduct exergoeconomic analysis. [41] Li et al developed a fully coupled multidimensional model to analyze energy and exergy efficiency. [38,42] Cocco et al developed a mathematical model to conducted exergy analysis of a CSP plant where electricity was generated in an ORC.…”

“…Gomez-Hernandez et al optimized those pinch point temperatures according to the economic analysis and second law of thermodynamics. These authors concluded that economic performance is the best when the pinch point temperature difference of the evaporator is nearly 2-3 C. [41] Yilmazoglu et al analyzed the effect of HTF and condenser types on the performance of a 10 MW parabolic trough CSP plant; they also conducted economic analysis of the HTF under two boundary conditions: outlet HTF temperature of the solar field or its safety margin is constant. [36] Duratherm 630 is the most economical option in the former condition, whereas nitrate is the most economical one in the latter condition.…”