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Details of Grant 

EPSRC Reference: EP/S028757/1
Title: Investigating Corrosion in Supercritical Fluids
Principal Investigator: Sumner, Dr J
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Doosan Power Systems National Physical Laboratory Siemens AG (International)
Siemens plc (UK)
Department: School of Water, Energy and Environment
Organisation: Cranfield University
Scheme: New Investigator Award
Starts: 01 April 2019 Ends: 30 September 2021 Value (£): 282,727
EPSRC Research Topic Classifications:
Eng. Dynamics & Tribology Materials Characterisation
EPSRC Industrial Sector Classifications:
Energy
Related Grants:
Panel History:
Panel DatePanel NameOutcome
06 Feb 2019 Engineering Prioritisation Panel Meeting 6 and 7 February 2019 Announced
Summary on Grant Application Form
This project proposes to study how turbine materials may fail in a new specialist energy production environment. The materials to be studied are superalloys, which are nickel- and cobalt-based alloys that can resist and work at high temperatures. These superalloys can be coated with thin ceramic layers, known as a thermal barrier coating (TBC), or metallic layers, to help protect them when they are in a high temperature environment.

It is important to know how the materials respond because they may be used in a new type of power plant which will expose them to an environment which is very unusual. This power cycle burns a fuel to drive a turbine and generate electricity when there is demand. The fuel can be natural gas or a synthetic gas made from coal, biomass or waste meaning that fuel supply is secure and power can be dispatched when needed. Unlike current power cycles using combustion, only oxygen, rather than air, is present with the fuel meaning carbon dioxide (CO2) and steam are the main products. The steam can be condensed out, and the CO2 kept. The CO2 then flows past the turbine at such high temperatures and pressures that it enters a special condition where it is neither liquid nor gas and is called supercritical-CO2.

This new type of power cycle has many potential advantages. As the superciritcal-CO2 is very dense, it's very good at pushing the turbine, so the energy from burning the fuel has a high efficiency of conversion into electricity, meaning electricity may be cheaper. It also means the turbine can be very small compared to other power cycles, so the new power plant can fit into small parcels of land, and can be put next to existing industrial structures for localised power generation. Finally, because the CO2 from burning the fuel is captured to drive the turbine, it doesn't have to be released into the atmosphere where it may contribute to climate change. Instead this CO2 can be captured, transported and used or stored. CO2 can be captured at 99% purity; this is better than specialist plant trying to remove CO2 from other power cycles, which aim to have 90% CO2 purity. This means the cycle can help make low-CO2 power while other renewable energy sources and storage options are developed.

However, in the supercritical-CO2 going through the turbine, there can be small amounts of chemical contaminants that can degrade the materials it is made from. As this power cycle recycles CO2 before transportation and use (it is a 'semi-closed' system), these chemicals can build up in concentration. To make sure that the plant built lasts for a long time and that there are no unexpected interruptions to power generation, it is important to know whether the turbine materials can survive these conditions as the supercritical-CO2 is at very high temperatures and pressures. By investigating the reliability of these materials, we can contribute to the confidence in these new, cleaner energy production systems, driving investment in and the spread of these options, rather than other cycles which may give off more CO2.

To meet this project's aim of understanding materials' degradation in this contaminated supercritical-CO2 operating environment experimental research much be carried out. Superalloy and ceramic coated samples will be provided by industry (see letters of support). These will be exposed at high temperatures (metal samples at 800-1000 C; TBC samples at 1100 C to simulate the cooling gradient anticipated through the component under operational conditions), high pressures (300 bar) and with chemical contaminants (such as H2O, SOX and NOX). Different superalloys will be used to see how differences in their chemistry, manufacturing and internal microstructure alters their reaction with supercritical-CO2. After a thousand hours exposure the samples will be looked at using specialist microscopy techniques to see how much metal has been lost and if any changes have taken place with the internal structure.
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Organisation Website: http://www.cranfield.ac.uk