scholarly journals A Direct Steam Generation Solar Power Plant With Integrated Thermal Storage

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Jürgen Birnbaum ◽  
Markus Eck ◽  
Markus Fichtner ◽  
Tobias Hirsch ◽  
Dorothea Lehmann ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Storage System ◽  
Thermal Storage ◽  
Market Potential ◽  
Steam Generation ◽  
Parabolic Trough ◽  
Power Block ◽  
Direct Steam ◽  
Solar Field ◽  
Operating Points

For the future market potential of parabolic trough power plants with direct steam generation (DSG), it is beneficial to integrate a thermal storage system. Heat storage media based on phase change materials offer heat transfer at constant temperatures needed for the evaporation process. Different options for a plant layout are presented and discussed. The interactions between the three subsystems—solar field, power block, and thermal storage—are analyzed, and boundary conditions arising from the thermal storage system are identified. Compared with a system without storage the number of operating points increases significantly since different combinations of storage charge and discharge operations go along with a varying power output of the solar field. It is shown that the large number of theoretical operating points can be reduced to a subset with practical relevance. Depending on the live steam parameters a reheat is necessary within the power block. Compared with parabolic trough fields with a single phase heat transfer medium such as oil, a special heat exchanger configuration is needed for a DSG plant. Different alternatives based on available technologies are presented and evaluated.

Development of a Thermal Energy Storage System for Parabolic Trough Power Plants With Direct Steam Generation

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Doerte Laing ◽  
Thomas Bauer ◽  
Dorothea Lehmann ◽  
Carsten Bahl
Keyword(s):  
Heat Transfer ◽  
Power Plants ◽  
Storage System ◽  
Thermal Power ◽  
Sensible Heat ◽  
Steam Generation ◽  
Parabolic Trough ◽  
Two Phase ◽  
Solar Thermal Power ◽  
Direct Steam

For future parabolic trough plants direct steam generation in the absorber pipes is a promising option for reducing the costs of solar thermal power generation. These new solar thermal power plants require innovative storage concepts, where the two-phase heat transfer fluid poses a major challenge. A three-part storage system is proposed where a phase change material (PCM) storage will be deployed for the two-phase evaporation, while concrete storage will be used for storing sensible heat, i.e., for preheating of water and superheating of steam. A pinch analysis helps to recognize interface constraints imposed by the solar field and the power block and describes a way to dimension the latent and sensible components. Laboratory test results of a PCM test module with ∼140 kgNaNO3, applying the sandwich concept for enhancement of heat transfer, are presented, proving the expected capacity and power density. The concrete storage material for sensible heat was improved to allow the operation up to 500°C for direct steam generation. A storage system with a total storage capacity of ∼1 MWh is described, combining a PCM module and a concrete module, which will be tested in 2009 under real steam conditions around 100 bars.

Development of a Thermal Energy Storage System for Parabolic Trough Power Plants With Direct Steam Generation

2009 ◽  
Author(s):  
Doerte Laing ◽  
Thomas Bauer ◽  
Dorothea Lehmann ◽  
Carsten Bahl
Keyword(s):  
Heat Transfer ◽  
Power Plants ◽  
Storage System ◽  
Thermal Power ◽  
Sensible Heat ◽  
Steam Generation ◽  
Parabolic Trough ◽  
Two Phase ◽  
Solar Thermal Power ◽  
Direct Steam

For future parabolic trough plants direct steam generation in the absorber pipes is a promising option for reducing the costs of solar thermal power generation. These new solar thermal power plants require innovative storage concepts, where the two phase heat transfer fluid poses a major challenge. A three-part storage system is proposed where a phase change material (PCM) storage will be deployed for the two-phase evaporation, while concrete storage will be used for storing sensible heat, i.e. for preheating of water and superheating of steam. A pinch analysis helps to recognize interface constraints imposed by the solar field and the power block and describes a way to dimension the latent and sensible components. Laboratory test results of a PCM test module with approx. 140 kg NaNO3, applying the sandwich concept for enhancement of heat transfer, are presented, proving the expected capacity and power density. The concrete storage material for sensible heat was improved to allow the operation up to 500 °C for direct steam generation. A storage system with a total storage capacity of approx. 1 MWh is described, combining a PCM module and a concrete module, which will be tested in 2009 under real steam conditions around 100 bar.

Assessment of a Molten Salt Heat Transfer Fluid in a Parabolic Trough Solar Field

2003 ◽  
Vol 125 (2) ◽  
pp. 170-176 ◽  
Author(s):  
D. Kearney ◽  
U. Herrmann ◽  
P. Nava ◽  
B. Kelly ◽  
R. Mahoney ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Molten Salt ◽  
Mojave Desert ◽  
Storage System ◽  
Eutectic Mixture ◽  
Heat Transfer Fluid ◽  
Diphenyl Oxide ◽  
Parabolic Trough ◽  
Electricity Cost ◽  
Solar Field

An evaluation was carried out to investigate the feasibility of utilizing a molten salt as the heat transfer fluid (HTF) and for thermal storage in a parabolic trough solar field to improve system performance and to reduce the levelized electricity cost. The operating SEGS (Solar Electric Generating Systems located in Mojave Desert, California) plants currently use a high temperature synthetic oil consisting of a eutectic mixture of biphenyl/diphenyl oxide. The scope of this investigation included examination of known critical issues, postulating solutions or possible approaches where potential problems exist, and the quantification of performance and electricity cost using preliminary cost inputs. The two leading candidates were the so-called solar salt (a binary salt consisting of 60% NaNO3 and 40% KNO3) and a salt sold commercially as HitecXL (a ternary salt consisting of 48% CaNO32, 7% NaNO3, and 45% KNO3). Assuming a two-tank storage system and a maximum operation temperature of 450°C, the evaluation showed that the levelized electricity cost can be reduced by 14.2% compared to a state-of-the-art parabolic trough plant such as the SEGS plants. If higher temperatures are possible, the improvement may be as high as 17.6%. Thermocline salt storage systems offer even greater benefits.

Comparative System Analysis of Direct Steam Generation and Synthetic Oil Parabolic Trough Power Plants With Integrated Thermal Storage

2011 ◽  
Author(s):  
Jan Fabian Feldhoff ◽  
Kai Schmitz ◽  
Markus Eck ◽  
Lars Schnatbaum-Laumann ◽  
Doerte Laing ◽  
...  
Keyword(s):  
Power Plant ◽  
Power Plants ◽  
System Analysis ◽  
Storage System ◽  
Steam Generation ◽  
Parabolic Trough ◽  
Synthetic Oil ◽  
Direct Steam ◽  
Oil Plant ◽  
Steam Parameters

Parabolic trough power plants are currently the most commercially applied systems for CSP power generation. To improve their cost-effectiveness, one focus of industry and research is the development of processes with other heat transfer fluids than the currently used synthetic oil. One option is the utilization of water/steam in the solar field, the so-called direct steam generation (DSG). Several previous studies promoted the economic potential of DSG technology [1–3]. Analyses’ results showed that live steam parameters of up to 500°C and 120 bars are most promising and could lead to a reduction of the levelized electricity cost (LEC) of about 11% [4]. However, all of these studies only considered plants without thermal energy storage (TES). Therefore, a system analysis including integrated TES was performed by Flagsol GmbH and DLR together with Solar Millennium AG, Schott CSP GmbH and Senior Bergho¨fer GmbH, all Germany. Two types of plants are analyzed and compared in detail: a power plant with synthetic oil and a DSG power plant. The design of the synthetic oil plant is very similar to the Spanish Andasol plants [5] and includes a molten salt two-tank storage system. The DSG plant has main steam parameters of 500 °C and 112 bars and uses phase change material (PCM) for the latent and molten salt for the sensible part of the TES system. To enable comparability, both plants share the same gross electric turbine capacity of 100 MWel, the same TES capacity of nine hours of full load equivalent and the same solar multiple of the collector field of about two. This paper describes and compares both plants’ design, performance and investment. Based on these results, the LEC are calculated and the DSG plant’s potential is evaluated. One key finding is that with currently proposed DSG storage costs, the LEC of a DSG plant could be higher than those of a synthetic oil plant. When considering a plant without TES on the other hand, the DSG system could reduce the LEC. This underlines the large influence of TES and the still needed effort in the development of a commercial storage system for DSG.

scholarly journals Comparative system analysis of direct steam generation and synthetic oil parabolic trough power plants with integrated thermal storage

Solar Energy ◽  
2012 ◽  
Vol 86 (1) ◽  
pp. 520-530 ◽  
Author(s):  
Jan Fabian Feldhoff ◽  
Kai Schmitz ◽  
Markus Eck ◽  
Lars Schnatbaum-Laumann ◽  
Doerte Laing ◽  
...  
Keyword(s):  
Power Plants ◽  
System Analysis ◽  
Thermal Storage ◽  
Steam Generation ◽  
Parabolic Trough ◽  
Synthetic Oil ◽  
Direct Steam

Study of Different Configurations of ISCC Parabolic Trough

2014 ◽  
Author(s):  
Dolores Duran ◽  
Rafael Almanza ◽  
Ivan Martínez
Keyword(s):  
High Pressure ◽  
Power Plants ◽  
Low Pressure ◽  
Pressure Level ◽  
Combined Cycle ◽  
Design Parameters ◽  
Steam Generation ◽  
Parabolic Trough ◽  
Direct Steam ◽  
Solar Field

This work shows the study of different configurations of integrated solar combined cycle (ISCC) parabolic-trough power plant with Direct Steam Generation (DSG). This paper is a sequel of previous works (Duran), but in this case six different configurations are analyzed: two pressure level without reheater (2P), 2P considering the solar field the high pressure economizer of the heat recovery steam generator, 2P considering the solar field the low pressure superheater, two pressure level with reheater (2PR), 2PR considering the solar field the low pressure superheater, 2PR considering the solar field the high pressure economizer. The main objective is to achieve the thermoeconomic optimization (based on Thermodynamic 1st. Law) of the HRSG including the solar field, to determine the optimal design parameters of both systems. It is applied a genetic algorithm (GA) methodology employed in previous works for the optimization of combined cycle power plants. Also, a sensitivity analysis with respect to the variation of solar radiation is done for the configurations that yield better results. As a result it would be obtained the optimal parameters of the HRSG and the optimal solar energy contribution for the configurations analyzed.

Performance Analysis of Direct Steam Generation-Central Receiver Systems

2012 ◽  
Author(s):  
Javier Sanz-Bermejo ◽  
José Gonzalez-Aguilar ◽  
Manuel Romero
Keyword(s):  
Power Plants ◽  
Superheated Steam ◽  
System Analysis ◽  
Live Steam ◽  
Saturated Steam ◽  
Steam Generation ◽  
Central Receiver ◽  
Power Block ◽  
Direct Steam ◽  
Solar Field

This work presents a comparative study between direct steam generation central receiver solar power plants working at live steam conditions similar to those found in commercial plants. PS10 and PS20 by Abengoa Solar use a single-receiver, producing saturated steam, whereas Sierra SunTower by e-Solar and Ivanpah Solar Electric Generating System (ISEGS) by BrightSource use dual-receiver technology producing superheated steam. The system analysis includes individual studies for each subsystem: solar field, receiver and Rankine power block; as well as the overall-analysis of a 66.7 MWth plant. PS10 working conditions were analysed with and without intermediate reheat step. It was assumed that Sierra SunTower-configuration has non-reheat turbine and Ivanpah-cycle includes an intermediate reheat step. The reheat process in PS10 configuration was performed using a fraction of live steam coming from the receiver; while for Ivanpah-configuration exhaust steam from high pressure turbine stage was sent back to the superheated steam section of the dual-receiver. These concepts make possible to avoid hybridisation and assure special regimes (such as Spanish feed-in tariff). The analysis of the heliostat field for dual-receiver concepts reveals that the aiming strategy on the absorbers has not relevant influence on optical performances. However, receiver efficiency decreased from 91.9%, working with saturated steam, to 87.86–84.14% working with superheated steam related to operating temperatures and heat exchange surface area. This study reveals that the improvement achieved in the power block under Ivanpah configuration was able to compensate higher thermal losses at the receiver, increasing net power production by 25.5% compared with saturated steam conditions.

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