Ny gasturbinteknik 2012-2014 Gas Turbine Developments Rapport 2013 Elforsk rapport 14:20 Magnus Genrup and Marcus Thern, LTH Maj 2014 Ny gasturbinteknik 2012-2014 Gas Turbine Developments Rapport 2013 Elforsk rapport 14:20 Magnus Genrup and Marcus Thern, LTH Maj 2014 ELFORSK Förord Projektet är en direkt fortsättning på Elforsk-projekt 2537 som avrapporterats i slutrapporten 12:27 med målet att säkerställa beställarkompetens avseende moderna gasturbinkombianläggningar hos de i projektet deltagande parterna. Föreliggande rapport är den andra årliga rapporten inom ramen för det fortsatta treårsprojektet (Elforsk-projekt 25099). Ansvarig för projektet är Magnus Genrup, Lunds Universitet. Treårsprojektet har finansierats av E.ON Värmekraft Sverige AB, Göteborg Energi AB och Öresundskraft. Projektet har följts av en styrgrupp med följande medlemmar: Fredrik Olsson och Matilda Lindroth, E.ON Värmekraft, Thomas Johnson, Göteborg Energi, Fredrik Joelsson, Öresundskraft, och Bertil Wahlund, Elforsk. Elforsk tackar styrgruppen för värdefulla insatser i projektet. Maj 2014 Bertil Wahlund Programområde El- och värmeproduktion Elforsk AB ELFORSK Executive Summary The last three years have certainly been a game changer with respect to combined cycle efficiency and operational flexibility. All major manufacturers are able to offer plants with efficiencies around 61 percent. Siemens has a TÜV-certified performance of 60.75 percent at the Kraftwerke Ulrich Hartmann (formerly Irsching 4) site outside Ingolstadt. The old paradigm that high performance meant advanced steam-cooled gas turbines and slow started bottoming cycles has definitely proven false. Both Siemens and General Electric are able to do a hot restart within 30 minutes to, more or less, full load. This is, by far, faster than possible with steam cooling and the only technology that is capable of meeting the future flexibility requirements due to high volatile renewable penetration. All major manufacturers have developed air-cooled engines for combined cycles with 61 percent efficiency. Steam cooling will most likely only be used for 1,600°C firing level since there will be an air shortage for both dry low emission combustion and turbine cooling. The increased combined cycle efficiency is a combination of better (or higher) performing gas turbines and improved bottoming cycles. The higher gas turbine performance has been achieved whilst maintaining a 600°C high pressure admission temperature – hence the gain in combined cycle performance. The mentioned requirements of both high gas turbine performance and sufficient exhaust temperature, should impose both an increase in pressure ratio and increased firing level. The price level (2012) was on average 30-35 percent higher than the minimum level in 2004. The cost of ownership (or per produced unit of power) is strongly governed by the difference between the electricity and the fuel price. The importance of evaluating all factors (like degradation and de-icing operation) in the economic model cannot be stressed too much since it may have a profound impact on the analysis. The test code guarantee verification test is indeed an important verification that the plant fulfills the expectations. One important thing, however, is not to accept the test uncertainty as a test tolerance since it will provide the manufacturer overwhelming and unfair odds. Siemens, General Electric, Alstom and Mitsubishi have all developed new versions of their combined cycle platforms. The key for 61 percent efficiency is high performing gas turbines, which includes components, pressure ratio and firing temperature. In addition, the exhaust temperature has to be at a level for maximum bottoming cycle performance. Today, most manufacturers have 600°C steam turbine admission temperature capability and the optimum exhaust gas temperature should therefore be on the order of 25-30°C higher. Both Siemens and General Electric have presented advanced admission data (170 bar/600°C and 165 bar/600°C) for their bottoming cycles. It is probably safe to assume that the other manufacturers are at the same level. The striking point is that both Siemens and General Electric appear to have no start-up time/ramp-rate penalty despite the advanced steam data. There have also been several high-performing simple-cycle units presented during the project duration. ELFORSK Nowadays, it is common to have a maintenance agreement at some level for risk mitigation. There are different levels of contractual services ranging from parts agreement to full coverage “bumper-to-bumper” LTSA services. One can chose to use either the OEM or another (third party) service provider. In many cases, the financing organs or insurer requires an LTSA (or better) for risk mitigation to level the insurance cost at a reasonable level. There are ways of potentially reducing the maintenance spending and one should always avoid lumped methods with equivalent hours. The word “lumped” is used in a sense that the two different ageing mechanisms (creep, oxidation, regular wear and tear and stresses related to thermal gradients during start and stop) are evaluated as equivalent time by e.g. assuming that a start consumes time rather being a low cycle. A competent monitoring system can be a good investment - even if only a single failure can be avoided. The total world-wide gas turbine fleet is in the order of 47,000 units and the total value of the gas turbine aftermarket was 2009 13.8 B€ (13.8×109 €). The after-market is, indeed, valuable to the manufacturers since all 47,000 units requires maintenance on a regular basis. Certain in-house produced parts may be offered with several hundred percent’s margin – in contrast to about ten percent for a complete new turn-key power plant. The reward for the user, by having a LTSA, is discounted parts and prioritized treatment by the supplier. The combined cycle has about half the carbon dioxide emission compared to a coal fired plant. The large difference is driven by the higher efficiency and the higher hydrogen content in natural gas. This in combination with the flexibility makes combined cycles attractive for both flexible non-spinning and spinning reserve power – with comparably low emissions of greenhouse gas. The partial pressure of carbon dioxide is low when compared to coal firing. The lower partial pressure makes the sequestration process more difficult. There is also a much larger flue gas mass flow since a typical combined cycle has around 1.5 kg/s flue gas per MW (kg/MWs or kg/MJ) in contrast to approximately 0.95 for a coal fired plant. The low partial pressure can be increased by introducing recirculation of flue gases. In addition to the discussed post-combustion process, there are other technologies being developed based on e.g. oxyfuel and IGCC/H2. All suggested technologies come with a significant efficiency penalty. A gas turbine can be made carbon dioxide neutral by firing renewables. Most manufacturers have quite wide fuel capability ranges but no true omnivorous gas turbine exists yet. There are several issues related to the fuel system (valves and pressure drops) and combustor (fuel nozzles, vortex break-down, etc.). There is also a turbomachinery dimension related to stability, forced response and potential flutter problems. The latter is forces acting on the blading which are functions of the displacement, velocity, or acceleration of the blades – and these forces feed energy into the system. The high penetration of volatile production like wind and solar (both CSP and PV) have been a game changer for the combined cycles. It is safe to assume that the role for the gas turbine based plants will change from base and mid- merit load to daily cycling and peakers. ELFORSK Sammanfattning Under projektets senare år har både verkningsgraden och flexibiliteten för kombianläggningar blivit avsevärt bättre. Idag erbjuder alla större tillverkare verkningsrader uppemot 61 procent. En lyftkyld kombi kunde tidigare nå maximalt runt 58-59 procents verkningsgrad medan ångkylda låg runt 60 procent. Vid EONs kraftverk Ulrich Hartmann i Irsching, utanför Ingolstadt, har TÜV certifierat verkningsgraden på Siemens SGT58000H anläggningen till 60,75 procent. Förr trodde man att ångkylning var enda sättet att nå verkningsgrader över 60 procent. Det gav gasturbiner med avancerad ångkylning och svårstartade bottencykler pga. höga ångdata. Här har det skett ett paradigmskifte. Både Siemens och General Electrics gaskombianläggningar klarar idag en varmstart på mindre än 30 minuter, upp till full last. Det är betydligt snabbare än vad ångkylda maskiner klarar. Lyftkylda anläggningar är den enda teknik som klarar att möta de krav på flexibilitet som är kopplade till framtidens flyktiga elproduktion. De större tillverkarna har idag utvecklat luftkylda gasturbiner för kombiprocesser och nått 61 procents verkningsgrad. Ångkylning är idag förmodligen bara ett alternativ för maskiner med eldningstemperaturer över 1,600°C, där luften inte räcker till både för kylning och låga emissioner. Att kombianläggningarnas verkningsgrad har ökat är ett resultat av att både gasturbinens- och ångcykelns prestanda har blivit bättre. Detta har skett med bibehållen admissionstemperatur för HP- och IP ånga på 600°C, vilket gör att hela kombianläggningens prestanda ökar. Kraven på både hög gasturbinprestanda och tillräcklig utloppstemperatur gör att tryckförhållande och eldningstemperatur ökar. Prisnivån för den här typen av anläggningar ligger (2012) 30-35 procent högre än den låga nivån 2004. Ekonomin