Science case study: Advanced measurement techniques on steam wetness (GE)
GE Power is a world leader in power generation with deep domain expertise to help customers deliver electricity from a wide spectrum of fuel sources. It is transforming the electricity industry with the digital power plant, the world’s largest and most efficient gas turbine, full balance of plant, upgrade and service solutions as well as its data-leveraging software. GE’s innovative technologies and digital offerings help make power more affordable, reliable, accessible and sustainable.
To support this vision, GE caries out significant levels of research and development, both within its own Global Research Centre’s and through partnerships with key external organisations. One such partnership is with the CCSEFE and its predecessor organisation the EFET lead by University of Nottingham.
Dr Scott Barham
Lead Engineer, Testing
The EngD Centre has offered an excellent environment allowing us to combine our customers’ requirements with the deep technical knowledge of the supervisors at the University of Nottingham to create something commercially viable and novel
Dr Scott Barham
GE and previously Alstom have sponsored some 10 EngDs. The technical work undertaken by the students has provided valuable and industrially relevant data and knowhow which has impacted on GE’s power businesses, primarily in the areas of steam and gas turbines. In addition, the centre has provided highly trained talent with technical and leadership skills relevant to industry. Consequently, GE and Alstom have so far employed 5 of the sponsored students in its UK businesses. As an example of the high quality research carried by the EngDs, the advanced measurement techniques on steam wetness are described.
Within power plant cycles, when steam and water are present simultaneously as a two phase flow it is referred to as ‘wet steam’. The presence of wet steam causes direct reductions in the efficiency and durability of steam turbines, where turbine efficiency reduces by approximately 1% for a 1% increase in steam wetness. Because of the effects of steam wetness, developing new systems to accurately monitor it is a crucial part of improving power plant efficiencies.
Currently in the market there is no method of real time accurate wetness measurement. Companies can use chemical or radioactive tracers to accurately measure wetness in power plants. However to complete this measurement accurately takes in excess of 10 hours making this tracer technology unsuitable for power plant feedback control. For this reason, General Electric (GE) and the University of Nottingham have been developing new methods of real time steam wetness measurement for commercialisation. These methods will then allow power plant operators the opportunity to fine tune their systems to improve both efficiency and also better understand the life of their plant equipment.
Real time wetness measurements (>1,000 Hz) will allow operators to better tune the power plant processes increasing efficiency and power output, whilst also improving knowledge about equipment and allowing developers to improve the efficiency of the products supplied, where a 0.1% increase in output on new plants such as Hinckley Point C would equate to an additional 22,000MWh/year of electricity.
Studentships
Initially the work on the project was completed by Scott Barham from 2009-2013, where during this time a number of novel methods of steam wetness measurement were investigated, in addition the project helped to perform wetness measurements in two Swedish nuclear power stations to correctly understand the customer requirements. Following this, a wet steam test rig was prepared in Switzerland and a capacitance wetness real time measurement system was successfully tested and patented (EP2985597 A1 Steam wetness measurement device, August 2014).
As a result of the successful test completion of this test campaign, the second stage of the project was continued with a second studentship.
In a related project on "Determination of the influence of downstream blockages on the performance of steam turbine exhaust diffusers", the aim was to enhance capability of identifying and rectifying issues due to downstream blockages in exhaust diffusers during retrofit of new generation turbines. During the project, Kristopher Vernon designed and prototyped a measurement probe for coarse water size and velocity in wet steam. This is key for understanding wet steam losses and for validation of theoretical models and whilst not the final solution, the product of the research represents a significant step forward to achieving this goal.
After completing the EngD programme, Scott Barham’ joined the company and became industrial supervisor for the current project on steam wetness. This is progressing well with the second EngD, David Walker building a calibration test rig at the University to start detailed validation of the system prior to the third stage of commercialisation.
Future work
Interest in the project and its commercialisation has been high with EDF Energy expressing a direct interest in the technology and its application to their plants (along with other technologies which could be tested at the rig in Nottingham). This partnership has helped us both to expand our knowledge, start to solve a real problem and also to recruit key members of our team directly from EngD studentships.