Highly competitive and volatile energy markets are currently observed, as resulting from the increased use of intermittent renewable sources. Gas turbine combined cycle power plants (CCPP) owners therefore require reliable, flexible capacity with fast response time to the grid, while being compliant with environmental limitations. In response to these requirements, a new operation concept was developed to extend the operational flexibility by reducing the achievable Minimum Environmental Load (MEL), usually limited by increasing pollutant emissions. The developed concept exploits the unique feature of the GT24/26 sequential combustion architecture, where low part load operation is only limited by CO emissions produced by the reheat (SEV) burners. A significant reduction of CO below the legal limits in the Low Part Load (LPL) range is thereby achieved by individually switching the SEV burners with a new operation concept that allows to reduce load without needing to significantly reduce both local hot gas temperatures and CCPP efficiency. Comprehensive assessments of the impact on operation, emissions and lifetime were performed and accompanied by extensive testing with additional validation instrumentation. This has confirmed moderate temperature spreads in the downstream components, which is a benefit of sequential combustion technology due to the high inlet temperature into the SEV combustor. The following commercial implementation in the field has proven a reduction of MEL down to 26% plant load, corresponding to 18% gas turbine load. The extended operation range is emission compliant and provides frequency response capability at high plant efficiency. The experience accumulated over more than one year of successful commercial operation confirms the potential and reliability of the concept, which the customers are exploiting by regularly operating in the LPL range.

BackgroundUpper patellar tendinopathies remain often chronic and rebel to a thorough conservative treatment. Moreover, the option of a surgical treatment could be disappointing. New treatments are being developed. Injection of PRP is one of these. Platelets contain lot of growth factors which would have the potentiality to enhance the healing process of tendons. Even if in vitro and animal experiments have demonstrated this stimulation of tendon healing process,1clinical series are subject to controversy.2MethodsTwenty patients with chronic upper patellar tendinopathy were enrolled. Assessments [VAS, clinical examination with an algometer, algofunctional scores (IKDC and VISA-P), functional assessments (isokinetic and Optojump) and imagery (ultrasounds and MRI)] were made before infiltration of PRP, and 6 weeks and 3 months after. The PRP was obtained by an apheresis system (COM.TEC, Fresenius). Six millilitres of PRP were injected without local anaesthetic. One week after infiltration, patients started a 6-week standardised sub-maximal eccentric reeducation.ResultsWe observed a very significant improvement of the algofunctional status as soon as 6 weeks after the infiltration of PRP, and continued to a lesser extent up to 3 months. During functional evaluation, pain decreased as well, but without significant improvement of performances. No significant improvements in the imagery were observed. Interestingly, patients who had a VAS equal or below 1 after 3 months post-infiltration were younger (24.7 vs 32.2 y.o.). Moreover, these younger patients had a significant increase of the IKDC score (p=0.003), a significant improvement of pain during isokinetic evaluations (p<0.05), and during Optojump assessments (p=0.01). Seventy-five percent of subjects were able to return to sport, even if only half of these patients recovered the same level than before the tendinopathy.Discussion/ConclusionsThis study demonstrates that a local infiltration of PRP associated with a submaximal eccentric protocol is efficient to improve symptoms of chronic upper patellar tendinopathies, non-responsive to classical conservative treatments. However, up to now, there is no consensus on the method to prepare the PRP. Indeed, each technique could provide a very different PRP (variations in the platelet concentrations and of the amount of red and white cells).