Supercritical Steam power cycle for Line-Focus Solar Power Plants

Coco Enriquez, Luis and Muñoz Antón, Javier and Martínez-Val Peñalosa, José María (2014). Supercritical Steam power cycle for Line-Focus Solar Power Plants. In: "4th International Conference On Nuclear And Renewable Energy Resources (NuRER 2014)", 26-29 Oct 2014, Antalya, Turquia.

Description

Title: Supercritical Steam power cycle for Line-Focus Solar Power Plants
Author/s:
  • Coco Enriquez, Luis
  • Muñoz Antón, Javier
  • Martínez-Val Peñalosa, José María
Item Type: Presentation at Congress or Conference (Article)
Event Title: 4th International Conference On Nuclear And Renewable Energy Resources (NuRER 2014)
Event Dates: 26-29 Oct 2014
Event Location: Antalya, Turquia
Title of Book: 4th International Conference On Nuclear And Renewable Energy Resources (NuRER 2014)
Date: 2014
Subjects:
Freetext Keywords: Supercritical steam solar power plant, Supercritical Rankine power cycle, Direct Steam Generation, Molten salt, Line-focus solar collector, Parabolic Trough, Linear Fresnel
Faculty: E.T.S.I. Industriales (UPM)
Department: Ingeniería Energética y Fluidomecánica [hasta 2014]
Creative Commons Licenses: Recognition - No derivative works - Non commercial

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Abstract

The supercritical Rankine power cycle offers a net improvement in plant efficiency compared with a subcritical Rankine cycle. For fossil power plants the minimum supercritical steam turbine size is about 450MW. A recent study between Sandia National Laboratories and Siemens Energy, Inc., published on March 2013, confirmed the feasibility of adapting the Siemens turbine SST-900 for supercritical steam in concentrated solar power plants, with a live steam conditions 230-260 bar and output range between 140-200 MWe. In this context, this analysis is focused on integrating a line-focus solar field with a supercritical Rankine power cycle. For this purpose two heat transfer fluids were assessed: direct steam generation and molten salt Hitec XL. To isolate solar field from high pressure supercritical water power cycle, an intermediate heat exchanger was installed between linear solar collectors and balance of plant. Due to receiver selective coating temperature limitations, turbine inlet temperature was fixed 550ºC. The design-point conditions were 550ºC and 260 bar at turbine inlet, and 165 MWe Gross power output. Plant performance was assessed at design-point in the supercritical power plant (between 43-45% net plant efficiency depending on balance of plantconfiguration), and in the subcritical plant configuration (~40% net plant efficiency). Regarding the balance of plant configuration, direct reheating was adopted as the optimum solution to avoid any intermediate heat exchanger. One direct reheating stage between high pressure turbine and intermediate pressure turbine is the common practice; however, General Electric ultrasupercritical(350 bar) fossil power plants also considered doubled-reheat applications. In this study were analyzed heat balances with single-reheat, double-reheat and even three reheating stages. In all cases were adopted the proper reheating solar field configurations to limit solar collectors pressure drops. As main conclusion, it was confirmed net plant efficiency improvements in supercritical Rankine line-focus (parabolic or linear Fresnel) solar plant configurations are mainly due to the following two reasons: higher number of feed-water preheaters (up to seven)delivering hotter water at solar field inlet, and two or even three direct reheating stages (550ºC reheating temperature) in high or intermediate pressure turbines. However, the turbine manufacturer should confirm the equipment constrains regarding reheating stages and number of steam extractions to feed-water heaters.

More information

Item ID: 33466
DC Identifier: http://oa.upm.es/33466/
OAI Identifier: oai:oa.upm.es:33466
Official URL: http://nurer2014.org/
Deposited by: Memoria Investigacion
Deposited on: 19 Jan 2015 16:57
Last Modified: 18 Aug 2017 11:16
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