Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Operational Improvements for Startup Time Reduction in Solar Steam Turbines
KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. (Concentrating Solar Power)ORCID iD: 0000-0002-8888-4474
Lund University. (Department of Energy Sciences)
Siemens Industrial Turbomachinery.
KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. (Concentrating Solar Power)
Show others and affiliations
2015 (English)In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 137, no 4, 042604Article in journal (Refereed) Published
Abstract [en]

Solar steam turbines are subject to high thermal stresses as a result of temperature gradients during transient operation, which occurs more frequently due to the variability of the solar resource. In order to increase the flexibility of the turbines while preserving lifting requirements, several operational modifications for maintaining turbine temperatures during offline periods are proposed and investigated. The modifications were implemented in a dynamic thermal turbine model and the potential improvements were quantified. The modifications studied included: increasing the gland steam pressure injected to the end-seals, increasing the back pressure and increasing the barring speed. These last two take advantage of the ventilation and friction work. The effects of the modifications were studied both individually as well as in different combinations. The temperatures obtained when applying the combined modifications were compared to regular turbine cool-down (CD) temperatures and showed significant improvements on the startup times of the turbine.

Place, publisher, year, edition, pages
ASME Press, 2015. Vol. 137, no 4, 042604
Keyword [en]
Steam Turbines, Start-up time
National Category
Energy Engineering
Research subject
Energy Technology
Identifiers
URN: urn:nbn:se:kth:diva-148147DOI: 10.1115/1.4028661ISI: 000350145500024Scopus ID: 2-s2.0-84940473273OAI: oai:DiVA.org:kth-148147DiVA: diva2:735706
Funder
Swedish Energy Agency
Note

QC 20150408

Available from: 2014-07-30 Created: 2014-07-30 Last updated: 2017-08-11Bibliographically approved
In thesis
1. Steam Turbine Thermal Modeling for Improved Transient Operation
Open this publication in new window or tab >>Steam Turbine Thermal Modeling for Improved Transient Operation
2014 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The growing shares of renewable energy sources in the market and solar thermal power applications have set higher requirements on steam turbine operation.These requirements are related to flexibility during transients. A key aspect sought of such flexibility is the capability for fast starts. Due to the varying temperature gradients during start-up, the speed at which the turbine can start is constrained by thermal stresses and differential expansion. These phenomena either consume component lifetime or may result in machine failure if not carefully controlled. In order to accomplish faster starts while ensuring that lifing requirements are preserved, it is important to analyze the thermal behavior of the machine. For this, a transient thermal model was developed with a focus on adaptability to different turbine sizes and geometries. The model allows for simple and fast prediction of thermo-mechanical properties within the turbine metal, more importantly, of the temperature distribution and the associated thermal expansion. The next step of this work was to validate the assumptions and simplifications of the model. This was done through the study and comparison of two turbines against measured operational data from their respective power plants. Furthermore,validation studies also included comparisons concerning the geometric detail level of the model. Overall, comparison results showed a large degree of agreement with respect to the measured data and between the geometric detail levels. The validated model was then implemented in studies related to reducing start-up times and peak differential expansion. For this, the potential effects of turbine temperature maintaining modifications were investigated and quantified.The modifications studied included: increasing gland steam pressure, increasing back pressure and increasing barring speed. Results yielded significant improvements starting from 9.5% in the start-up times and 7% in the differential expansion.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. 63 p.
Series
TRITA-KRV, ISSN 1100-7990 ; 14:06
Keyword
steam turbines, transients, start-up, finite element model, heat transfer
National Category
Mechanical Engineering
Research subject
Energy Technology
Identifiers
urn:nbn:se:kth:diva-156196 (URN)978-91-7595-367-0 (ISBN)
Presentation
2014-12-05, Sal Learning Theater (M235), Brinellvägen 68, KTH, Stockholm, 11:00 (English)
Opponent
Supervisors
Note

QC 20141128

Available from: 2014-11-28 Created: 2014-11-24 Last updated: 2014-11-28Bibliographically approved
2. Improving Concentrating Solar Power Plant Performance through Steam Turbine Flexibility
Open this publication in new window or tab >>Improving Concentrating Solar Power Plant Performance through Steam Turbine Flexibility
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The amount of incoming solar energy to earth is greater than any other source. Among existing technologies to harness solar energy there is concentrating solar power (CSP). One advantage of CSP is that is dispatchable, meaning that it can provide power even when the sun is not shining. However, CSP is undergoing challenges which hinder its development such as operating variabilities caused by the fluctuations of the sun or the fact that these systems are not yet cost competitive with respect to other technologies.  

One way of improving the performance of CSP plants (CSPPs) is by increasing their operational flexibility, specifically their capability for fast starts. In this way it is possible for the CSPP to harness the solar energy as soon as possible, thus producing more energy and increasing its profitability. Over 90% of CSPPs use a steam turbine to generate electricity. Steam turbines are not currently designed with the flexibility required by the CSP application. Steam turbine start-up is limited by thermal stress and differential expansion. If not carefully controlled, these phenomena either consume lifetime or even result in machine failure.

The aim of this work was to understand the improvement potential of steam turbine start-up and quantify this in terms of CSPP performance indicators. For this, a thermo-mechanical steam turbine model was developed and validated. The model was then used to analyze potential improvements and thermal constraints to steam turbine start-up operation. Furthermore, a CSP plant techno-economic model was developed including steam turbine details. This modeling approach including two levels of detail allowed for the particularities of the component to be included within the dynamics of the plant and thus be able to connect the perspectives of the equipment manufacturer with those of the plant operator. Reductions of up to 11.4% in the cost of electricity were found in the studies carried out.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2017. 75 p.
Series
TRITA-KRV, 17/04
Keyword
Concentrating Solar Power, Steam Turbines, Transients, Start-up
National Category
Energy Engineering
Research subject
Energy Technology
Identifiers
urn:nbn:se:kth:diva-211780 (URN)978-91-7729-388-0 (ISBN)
Public defence
2017-09-08, M3, Brinellvägen 64, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
Swedish Energy Agency
Note

QC 20170814

Available from: 2017-08-14 Created: 2017-08-11 Last updated: 2017-08-15Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Authority records BETA

Topel, Monika

Search in DiVA

By author/editor
Topel, MonikaSpelling, JamesLaumert, Björn
By organisation
Heat and Power Technology
In the same journal
Journal of engineering for gas turbines and power
Energy Engineering

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 228 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf