Life Prediction of Power Plant Components with Welds under Flexible, Thermal-Mechanical Loadings and Operation Cycle Optimization

Application deadline - August 2020 

Project Description

 

The current market conditions are such that combined cycle gas turbine (CCGT) plants are now considering double two-shift operation, so potentially accruing upwards of 600 starts per year. The pressure to reduce the extent of pressure system inspections and repairs continues to increase, with the most recent capacity auction clearing prices for generation showing a significant reduction when compared to previous years. For operators of large generation facilities, the key consideration is the through life revenue return, which will guide decisions on new plant builds and any capital investments on plant currently operating. On this basis the need for effective life prediction and condition monitoring tools to support the supply chain (designer, fabricator, operator and technical service provider) is evident.

 

Over the years, significant development has been made on the 9–12%Cr creep strength enhanced ferritic (CSEF) steels. Traditionally, in material development for power plant components, creep ductility, which can be treated as resistance to damage, has received much less attention. However, the risk of catastrophic failure due to low damage tolerance is a real challenge, in particular, in the situation where mechanical and metallurgical constraints are present. In addition, due to the increasing frequency of cyclic operations, i.e. starts up and shut downs for main steam pipelines of power plants, low cycle creep fatigue failure due to low ductility of the materials has become an important concern.

 

The aim of the PhD project is to investigate creep and creep fatigue behaviour which takes into account the variable ductility for CSEF power plant steels subject to realistic plant loading cycles, through a comprehensive theoretical, experimental and computational programme.

 

Specific objectives will include:

1. Data acquisition and analysis and literature review on the currently available models and assessment procedure.

2. Experimental investigation of LCF behaviour and microstructure characterization of the candidate power plant steel/weld (possibly MARBN).

3. Development of a cyclic visco-plasticity model for PM, WM and HAZ which takes into account the cyclic softening and damage.

4. Application of the model for component assessment using plant operational data and considering typical plant component geometries and plant operator requirements for condition assessment.

5. Exploring early life contributors to damage such as severe plant operation, impact of poor design and creep brittle properties.

 

High temperature mechanical testing and physical characterization will be carried out using well-established facility. The theoretical and modelling work will be carried out using finite element package ABAQUS through user defined subroutines.

The candidate must have a high-grade qualification, at least the equivalent of a UK 1st or 2.1 class degree in an engineering or science discipline (e.g. mechanical engineering or applied mechanics). A strong background of Mechanics of Solids and Computational Modelling is preferable. The students must possess excellent presentation and communication skills and be able to write high quality academic papers.

The PhD project is of four years duration, starting October 2019, within the EPSRC Centre for Doctor Training (CDT) “Resilient decarbonised Fuel Energy Systems”. The studentship which will cover full university fees and a tax-free, enhanced annual stipend of £18,757 to UK and EU candidates. A limited amount of partial funding is available for exceptional international applicants who are highly qualified and motivated. Due to the nature of this funding, the CDT would only be able to cover the cost of the Home/EU fees and therefore the applicant would need to either find alternative funding or self-fund the fee difference.

Informal inquiries may be sent to Dr Tao Liu, Tao.Liu@nottingham.ac.uk but please see below to apply

 

 Please apply here http://www.resilient-decarbonised-energy-dtc.ac.uk/how-to-apply/how-to-apply.aspx or use the "how to apply" tab above

 

Modelling Creep-Fatigue Damage and Life Prediction for Gas Turbine Rotors

Recruitment for student start date of October 2021 

Project Description

 

The current market conditions are such that combined cycle gas turbine (CCGT) plants are now considering double two-shift operation, so potentially accruing upwards of 600 starts per year. This increased thermal cycling has a detrimental effect on component life. One critical component is the gas turbine rotor. The ability to accurately calculate the remaining life of the rotors through prediction of creep and fatigue damage will enable reduction of financial and environmental costs associated with premature replacement. Ultimately these cost reductions could benefit the consumer and the economy.

 

RWE Generation operates gas (CCGT), biofuel and coal power stations across Europe. It is one of the largest electricity generation companies within Europe. Since its power station components operate at high temperatures and pressures, RWE has technical interest in component life prediction and extension through modelling, plant performance optimisation, metallurgy, welding and new materials.

 

A previous research programme, conducted over the last 3 years at Nottingham, has involved development of a visco-plastic material model for one of the rotor steels, determination of the material model parameters through experimental testing and development of a finite element model of the rotor with some limited life prediction capability.   

 

The aim of the current project is to continue this research to fully develop a model which can provide accurate life predictions for the rotor given the correct thermal boundary conditions.

 

Specific objectives will include:

  1. Further development of a 3D finite element model of the rotor including all potential high damage regions (e.g. including blade root to rotor contact).
  2. Refinement of the visco-plastic model to better simulate creep-fatigue interaction during turbine start up and shut down.
  3. Extension of the visco-plastic model to include damage/life prediction.
  4. Material testing to provide model parameters for the second rotor material.

 

High temperature mechanical testing and physical characterization will be carried out using well-established facility. The theoretical and modelling work will be carried out using finite element package ABAQUS through user defined subroutines.

 

We are seeking applicants to start in September 2020.

 

Candidates should have a first or high 2.1 class honours degree in an engineering or science discipline (e.g. mechanical engineering, applied mechanics or applied mathematics). A strong background of Mechanics of Solids, Mathematics and Computational Modelling is preferable.

 

The scholarship on offer (to eligible students) comprises a tax-free stipend of £15,285 (2020/2021) a year for four years, and paid UK/EU tuition fees. Due to funding restrictions, this position is only available for UK or EU candidates.

 

This project will be partly funded by RWE UK. The student will have opportunity to work with RWE experts. The Industrial Supervisor is Dr Jeremy Hughes at RWE UK.

 

The PhD student will work within the EPSRC Centre for Doctor Training (CDT)Resilient decarbonised Fuel Energy Systems

 

Informal enquiries may be sent to Prof Wei Sun (w.sun@nottingham.ac.uk). Please note that applications sent directly to this email address will not be accepted.

 

Please apply here http://www.resilient-decarbonised-energy-dtc.ac.uk/how-to-apply/how-to-apply.aspx or use the "how to apply" tab above

 

Innovate surface treatment and coatings for thermal power plant components

Recruitment for student start date of October 2021 

The UK was the first major economy in the world to pass laws to end its contribution to global warming by 2050. This ambitious target towards zero net emissions, or “carbon neutrality”, will be pursued in this 30 years timespan through promoting reforestation, carbon capture and storage, but also by transitioning to renewable energy while enhancing current power plants efficiency.

 

The transition towards renewable energy leads an overall lower demand to existing power plants, but at the same time this demand is concentrated within shorter and intermitted time frames, due to the intermittent nature of for instance solar and wind energy supply. Therefore, power plants which were designed to operate continuously are being demanded increased flexibility in intermittent operation, posing some parts to unexpectedly frequent thermal cycling leading to parts failure.

 

The goal of this PhD project is to improve the performance and life span of components used in power plants by means of surface treatment and coatings to understand the failure mechanisms induced by thermal cycling, corrosion and wear. This project will focus on developing and testing a range of suitable surface treatments by advanced coating deposition through a novel suspension plasma spray for high temperature components including valves, heat exchangers and boiler parts.

 

The project will involve the commissioning of testing rigs, requiring design, assembling and computer controlling of the necessary components. The test rig will allow us to understand coating performance under real service operating conditions as informed by BF2RA industrial partners. Material characterisation will include advanced techniques as high-resolution scanning and transmission electron microscopy and Raman spectroscopy.

 

 

Close collaboration with BF2RA industrial partners will allow the candidate to work on and solve real life problems making an impact on current and future power plant technologies.

 

Funding Notes:

 

The position is only open to EU and UK candidates due to funding restrictions. The candidate must have at least a UK 2.1 class degree in materials/mechanical/ manufacturing engineering, or in a relevant discipline. We are committed to diversity and we are keen to hear from candidates who are under-represented in research. The University of Nottingham offers leading experimental facilities in thermal spray and mechanical testing at Coatings and Surface Engineering Group, and materials characterisation  at the Nanoscale and Microscale Research Centre (nmRC).

Informal Enquiries to  Dr Tanvir Hussain (Tanvir.Hussain@nottingham.ac.uk)

 

Please apply here http://www.resilient-decarbonised-energy-dtc.ac.uk/how-to-apply/how-to-apply.aspx or use the "how to apply" tab above