Last month’s Steam Turbine and Generator User Group 2019 conference, held in Manchester United’s Football Ground, UK, was not only an excellent opportunity to visit the famous football pitch but to learn the latest developments in the technical field. Organised by the Institution of Mechanical Engineers, the annual meeting attracted many international experts on steam turbine and generator assets and with about fifty presentations given in two parallel sessions it was a very informative event.
The conference began with the key note from Paul Evans, Station Manager at Drax. He described Drax power station which used to be the largest coal-fired plant in the UK. However, since converting four out of its six units to biomass, the station is now the largest single renewable source in the country and generates about 15% of the UK’s renewable electricity. As he highlighted, every aspect of using biomass such as storing, milling and burning, is more complicated than that of coal. Hence it was quite an evolution for the station to convert its units and needed significant investment including in the supply chain such as developing ports and train wagons in the UK and also four pellet production plants in the USA. Paul also talked about the future repowering of units 5 and 6, currently coal-fired, to run on gas as two combined cycle gas turbines (CCGT). Paul discussed Drax’s bioenergy carbon capture storage (BECCS) pilot project, the first of its kind in Europe, which, if successful, could make the renewable electricity produced there carbon negative. Additionally, he discussed how Drax is preparing for future market needs by acquiring new generation assets. These include: three pumped-storage hydroelectric power stations with a total capacity of nearly 570 MW, four CCGT of 2000 MW combined capacity and one biomass from waste facility.
With more intermittent renewable sources such as wind and solar being added to the grid worldwide, coal-fired power plants have to adapt to new operating regimes as they are pushed further down the merit order and are required to balance fluctuations from the power output of intermittent sources. In general, for existing power plants it means operating at off- design conditions. Off-design conditions mean new challenges such as reducing the lifespan of crucial components and increasing operating and maintenance costs and a subsequent need for new solutions. These were the topics of many of the presentations and are also areas I cover in my current report – ‘Power plant design and management for unit cycling’ (available in draft in May 2019).
Many excellent talks were presented, the full list can be found at this link. Here, I just want to mention a few of them. For example, George Cleaver from Siemens, UK talked about the development of the hot standby mode for flexible steam turbine operation. This solution can reduce turbine cold start up time up to 60% and reduce lifetime consumption of its components.
Andreas Schaaraschmidt (Siemens AG) gave an interesting presentation about how condition-based maintenance can not only prolong the life of steam turbine components but also double their inspection intervals which of course means higher availability and optimised maintenance cost.
James Stagnitti from GE Power described how use of advanced sealings maintains the correct clearances in the turbine during start-up which is an issue of concern. He also talked about solid particle erosion of the high-pressure turbine nozzles and how this can be avoided using appropriately designed nozzles and advanced coatings. Both solutions prevent steam efficiency losses.
Although there is a clear change in the role of coal in the energy mix worldwide and coal fired-stations are facing new challenges, the mood of the conference was positive and the high number of new solutions presented show that the industry is rising to the challenge of adapting to provide back up to intermittent renewables.
The Steam Turbine and Generator User Group 2019 conference took place on 13-14 March at the Manchester United Football Ground in Manchester, UK