Advanced Surface Protection to Enable Carbon abatement Technologies (ASPECT)

Project Title
Advanced Surface Protection to Enable Carbon abatement Technologies (ASPECT)
Project partners and grant funding
Doosan Babcock Energy Ltd (co-ordinator) £204,722
E.ON UK (partner) £107,130
RWE UK (partner) £73,731
Cranfield University (partner) £538,328
National Physical Laboratory (partner) £171,266
Sulzer Metco (partner) £15,590
Monitor Coatings (partner) £163,585
Total grant £1,274,352
Project description
The ASPECT project is concerned with the developments in materials necessary for the successful implementation of advanced coal-fired utility boiler technologies, with advanced steam conditions and high efficiencies, and fitted with CO2 capture and storage technologies. The reduction of greenhouse gas production from power generation is a key element of the British government's Carbon Abatement Technology strategy, and is a core priority of the Materials for Energy programme.
The more arduous operating environments associated with the emerging Carbon Capture and Storage (CCS) technologies and with biomass co-firing are of specific concern. Both the fireside and steam-side of the superheaters/reheater tubes, and the internal surfaces of the steam pipework will be subject to increased wastage rates, as both steam temperatures and pressures are increased in pursuit of the increased cycle efficiencies required to compensate for the efficiency penalties associated with CO2 capture technologies. The Surface Engineering of both the fireside and steam-side surfaces represents one of the preferred options for the mitigation of risks to the key high temperature boiler components.
An existing project, funded through the former DTI Technology Programme (Modelling Fireside Corrosion of Heat Exchanger Materials in Advanced Energy Systems), which was completed in 2011, was concerned with the development of the modelling capability to predict the levels of damage that might be expected with the introduction of oxy-combustion and biomass co-firing in existing and new power station boilers. It became clear from the results of this work that there are significant concerns that the materials used in existing boilers, and those being specified for future plant may not be able to deliver the reliability expected from modern power station, principally due to the increased risks of excessive rates of fireside corrosion and steam side oxidation.
One of the potential responses is to develop a new generation of protective coatings for key components. To be successful, the fireside coatings have to be suitable for in-situ application in boilers, for installation and repair purposes, while the steam-side coatings have to be applied before the installation of the boiler tubes, and should not cause problems with boiler component fabrication. This approach to the development of protective systems for protection against corrosion in large coal boilers is relatively novel.
For the fireside, the emphasis is on the development of a portfolio of sprayable, particulate-based coating compositions and application technologies that can be used in-situ in either new build or retrofit applications, as well as for repair purposes. One of the key innovations here will be to investigate the use of ‘exothermic reaction synthesis’ (ERS) to consolidate coatings of appropriate thicknesses, following their application using cheap, low temperature spraying methods.
For steam-side protection, the emphasis is on the development and testing of diffusion coating systems and application methods for the protection of the internal surfaces of boiler tubes and steam pipework. The key issue here is the development of cost-effective application methods for diffusion or slurry coatings, which can be used inside tubular components of many metres in length. The application will probably be after they have been formed into the required shapes, but prior to installation. These components will then be welded together during installation. The coating technology will have to be compatible with these operations both for new build applications and for replacement/repair in plant following periods of service
The ASPECT Work Programme is divided into the following tasks:
Task 1 Boiler Environments (led by Doosan Babcock Energy Ltd.)
This task builds on the knowledge developed in the existing project on modelling corrosion in the fireside environment, and adds similar information for the range of steam-side environments in existing and advanced boilers. A key deliverable from this task is the definition of the components at greatest risk, the description of the metal wastage mechanisms and the specification of the required protective properties of the coatings. The proposed work in this task will also help to define in detail the more practical issues associated with the application and performance of the coatings.
Task 2 Coating Design (led by Cranfield University)
This task is aimed at building on corrosion data from existing coating compositions to identify the preferred compositions to resist the forms of attack on the fireside and steam-side, as defined in Task 1. For the fireside, this information will be combined with knowledge of the reactive elements required to drive the ERS process for the formulation of powders suitable for spraying the required coating composition. The required compositions will be produced by depositing surface layers on to existing powders using a new facility at Cranfield. Trials of coatings made from these powders will then take place to relate the powder compositions to the ‘fired’ coating compositions.
For the steam-side, it is envisaged that existing coating chemistries which are expected to provide good oxidation resistance under the relevant conditions, will be used in vapour or slurry form.
The basic characteristics of both types of coating in providing protection from fireside corrosion and stem side oxidation will be evaluated at laboratory scale.
Task 3 Coating Application (led jointly by Sulzer Metco and Monitor Coatings)
This task is focused on the application methods for both fireside and steam side protection. As indicated above, existing cold spraying methods are preferred for the fireside coatings. Sulzer Metco will develop these methods, within the constraints established for in-situ application in boilers. They will prepare test coupons for screening trials, and further coupons and sub-components for evaluation under Task 4, below.
For the steam-side, the coating applications will be further developed by Monitor and coated coupons and test specimens will be prepared for the screening and performance trials.
Task 4 Performance Trials and Benchmarking (led jointly by Cranfield and NPL)
This task is intended to provide the critical performance data on the new fireside and steam-side coatings, and benchmark this performance against existing alloys and coatings. The metal wastage rate data and coating performance information will come from medium term, i.e. >1000 hour, laboratory tests to assess the coating behaviour under the ranges of expected fireside and steam-side environments, and the results of shorter term tests in pilot scale rigs.
Task 5 Plant Trials (led jointly by E.ON and RWEnpower)
The final technical task involves the performance of two validation trials in host coal power plants. These start in the final year of the project and run on past the end date. Work started in preparation for this at the beginning of year 2 of the project, leading on to the fabrication of the parts in the second half of year 2. Installation and execution of the trials took place in year 3/4.
Task 6 Cost Benefit Analysis and Guidelines (led jointly by Sulzer Metco and Monitor)
To assist the rapid deployment of these newly developed fireside and steam-side coatings, a technical and commercial guideline document on the coating technologies and their application, with a number of appropriate illustrative Case Studies, will be prepared.
Task 7 Project Management, Dissemination and Exploitation (led by Doosan Babcock Energy Ltd.)
Dissemination of the outcomes from the project to the global power generation market place is being pursued through a range of measures. These include the preparation of press releases and technical articles for appropriate publications, participation in relevant international conferences and, where appropriate, the direct organisation of awareness events.