Advances in Gas Turbine Technology Part 9 doc

Advances in Gas Turbine Technology 230 Figures 13 and 14 give the modeling results. Figure 13 shows the evolution of the heat exchange surface versus the inlet radius. The greater the volute, the smaller the surface to volume ratio. Small turbomachines therefore have a higher surface to volume ratio. The necessity of taking into account heat transfer in small turbomachines is largely confirmed by Figure 14: the heat losses in the volute are relatively greater. In this study, when the inlet radius is halved, the surface to volume ratio doubles and the heat losses are multiplied by about 2.5 Fig. 13. Ratio of heat exchange surface (S) and the volume (V) of the volute versus the inlet radius Influence of Heat Transfer on Gas Turbine Performance 231 Fig. 14. Heat transfer in the volute versus the size of the machine 4. Conclusion Internal and external heat transfer induces a drop in the performance of gas turbines. This study shows that the performance of small turbomachines evaluated with the assumption of adiabaticity is not accurate. For a given operating point, the mass flow and the compression ratio recorded on the maps and the calculated performance do not correspond to the actual characteristics when the machine operates with heat transfer. The assumption that heat losses represent 15% of the work of adiabatic turbines, of which 60% is received by the compressor (non-insulated), leads to overestimating the power by 35% and the energy efficiency by 23% Insulation of the turbine, although it seems to be a solution to maintain the operating characteristics of adiabatic turbines, leads in fact to increasing the drop in performance. For the insulated version, the net power is overestimated by 51% and efficiency by 26.6%. In the absence of an adiabatic gas turbine (ideal machine), which provides the best performance, we must avoid insulating the turbine in order not to decrease performance still further. To maintain the level of performance, and in particular the net power produced by the gas turbines, despite heat transfer, adjustments are needed. They consist mainly in increasing the fuel flow, resulting in an increase in the turbine inlet temperature. In the case of our study, the fuel flow increase is 3.5% in the non-insulated version and 8.5% in the insulated version. The turbine inlet temperature increase is 6.4% in the insulated version and 11.8% in the non-insulated version. Advances in Gas Turbine Technology 232 Finally, this study confirms that the assumption of adiabaticity is not valid in turbochargers, micro and ultra-micro gas turbines. Compared to the available thermal energy at the turbine inlet, heat losses increase with the surface to volume ratio which decreases in small-sized machines. The quality of operation of small turbomachinery cannot be characterized with isentropic efficiency which has no physical meaning because of the relative importance of heat transfer. The proposal of a new performance indicator and the development of new maps available for any type of thermal turbomachines will therefore be the subject of our forthcoming investigations. 5. Acknowledgment The authors would like to acknowledge the French Cooperation EGIDE for funding this study. 6. Appendix: Energy balance calculations 1. Adiabatic gas turbine: Data: (see page 6) Power of the gas turbine: P GT Compressor power : Pc   2i1Cmpi PqcTT ;  γ-1 0,4 γ i2 i1 1,4 i2 i1 i1 C p T 288 T =T + -1 =288+ 7 -1 =555.71K p η 0,8                Cpi2i1 =q c T -T =20 1 555.71-288 =5354.2 m PkW Turbine power P T :  T p i4 i3 =q c T -T m P ; γ-1 0.33 γ 1.33 i4 i4 i3 i3 T i3 p1 T=T+ -1T×η =973+ -1 ×973×0.85=665.64K p6.42                   Tpi4i3 = q c T -T = 20 1.13× 665.64-973 =6946.4kW m P  GT = =6946.4-5354.2-66=1526.2 kW TCml PPPP Thermal power supplied by combustion chamber: Q cc The fuel flow is neglected     pi3i2 =q c T -T =20 1.13× 973-555.71 =9430.7kW cc m Q  Influence of Heat Transfer on Gas Turbine Performance 233 Thermal power lost in the exhaust gas: Q exh =Q -P -P =9430.7-66-1526.2=7838.5kW exh CC ml GT Q 2. Non insulated gas turbine: Data:  c = 7.17 (Figure 6); q m = 19.8 kg.s -1 (From the adiabatic compressor map). T i2 = 604.20 K; Q 12 = 625.2 kW (thermal power received by the compressor). Power of the gas turbine: P GT Thermal power received by the compressor: Q 12 12 Tad Q = 0.15×0.6×P =0.15×0.6 6946.4=625.2 kW  P Tad : adiabatic turbine power Compressor power: Pc   -1 2 1 i2 i1 γr 0.287×1.4 h -h = T -T = × 604.20-288 =317.62kJ.k g γ-1 0.4   12 m 12 ΔH=q Δh =317.62×19.8=6288.9 kW 12 12 P=ΔH -Q =6288.9-625.2=5663.7 kW C Turbine power P T : GT TGTCml P =1526.2 kW P =P +P +P =1526.4+5663.7+66=7256.1kW Search for new turbine inlet temperature The variation in the expansion ratio of the turbine versus the reduced mass flow (Figure 3) shows that when the expansion ratio is greater than two (2), the reduced mass flow remains constant (Pluviose M., 2005). This reduced flow constant calculated in adiabatic conditions enables the new turbine inlet temperature (T i3 ) corresponding to the new pressure (p i3 ) to be determined by the following equations.  33 5 5 33 973 20 92.55 10 6.42 1.05 10 ii mm m reduced ii ad nonins TT qq q pp             ad: adiabatic Non ins: non insulated 31 0.95 0.95 7.17 1.01325 6.902 i nonins Cnonins i pp bars      2 2 55 3 3 92.55 10 6.902 10 1040.6 19.8 inonins m reduced inonins mnonins qp TK q               Advances in Gas Turbine Technology 234 γ-1 0.33 γ 1.33 i4isentropic i3 T 11 T =T =1041.6× =652.90K π 6.57       i4nonins T =671.23K Thermal power supplied by the combustion chamber: Q cc The fuel flow is neglected     pi3i2 =q c T -T =19.8 1.13× 1040.6-604.2 =9764kW cc m Q  Thermal power lost in the exhaust gas =Q -P -P -P =9764-66-625.2/0.6-1526.4=7129.56kW exh CC ml thl GT Q P thl : power of thermal losses . 3. Insulated gas turbine: Data:  c = 7.22 (Figure 6); q m = 19.5 kg.s -1 (from the adiabatic compressor map). T i2 = 622.68 K, Q 12 = 1042 kW (thermal power received by the compressor) Power of the gas turbine: P GT Thermal power received by the compressor: Q 12 12 Tad Q =0.15×P =0.15×6946.4=1042 kW P Tad : Adiabatic turbine power Compressor power: P C   -1 2 1 i2 i1 γ r 0.287×1.4 h -h = T -T = × 622.68-288 =336.19kJ.k g γ-1 0.4   12 m 12 ΔH=q Δh =317.62×19.5=6555.6 kW 12 12 P=ΔH -Q =6555.6-1042=5513.6 kW C Turbine power P T : TAG T TTAGCml P =P =1526.2 kW P =P +P +P =1526.4+5513.6+66=7105.8kW Search for new turbine inlet temperature  33 5 5 33 973 20 92.55 10 6.42 1.05 10 ii mm m reduced ii ad ins TT qqq pp             ad : adiabatic 31 0,95 0.95 7.22 1.01325 6.95 i ins Cins i p pbars     Influence of Heat Transfer on Gas Turbine Performance 235  2 2 55 3 3 92.55 10 6.95 10 1088 19.5 i insulated m reduced iinsulated minsulated qp TK q              γ-1 0.33 γ 1.33 i4isentropic i3 T 11 T =T =1088× =680.70K π 6.62       i4 T =690K Thermal power supplied by the combustion chamber: Q CC The fuel flow is neglected     pi3i2 =q c T -T =19.5 1.13× 1088-622.68 =10253kW CC m Q  Thermal power lost in the exhaust Q exh =Q -P -P -P =10253-66-1042-1526.2=7618.8kW ech CC ml thl TAG Q 7. References Berger, M., Gostiaux, B., 1992, Géométrie différentielle: variétés, courbes et surfaces France Presses universitaires de Paris, ISBN : 2-13-044708-2. Cormerais, M. 2007, Caractérisation expérimentale et modélisation des transferts thermiques au sein d'un turbocompresseur d’automobile, Thèse de doctorat de l’école centrale de NANTES, pp. 1-243. Diango, A., 2010, Influence des pertes thermiques sur les performances des turbomachines. Thèse de doctorat du Conservatoire national des arts et métiers, Paris, pp. 1-244. Kreith, F., 1967, Principles of heat transfer, Masson, [trad.] Kodja Badr-El-Dine, Université d'ALEP (Syrie), Colorado, International textbook Company Scranton, Pennsylvania, 1967. pp. 1-654. Moreno, N., 2006, Modélisation des échanges thermiques dans une turbine radiale, Thèse de doctorat de l'École nationale supérieure d'arts et métiers, pp. 158. Padet, J., 2005, Convection thermique et massique, Techniques de l'ingénieur, BE 8206. Pluviose, M., 2005. Conversion d'énergie par turbomachines, Ellipses, pp. 1.277.ISBN 2-7298- 2320-4. Pluviose, M., 2002, Machines à fluides, Ellipses, pp. 1-276, ISBN 2-7298-1175-3. Pluviose, M., 2005, Similitude des turbomachines à fluide compressible, Techniques de l'ingénieur, BM 468007.2005. Pluviose, M. & Perilhon, C.(2002). Mécanismes de conversion de l'énergie, echniques de l'ingénieur. BM 4281, 10-2002 Pluviose , M., Perilhon, C., 2002, Bilan énergétique et applications, Techniques de l'ingénieur, BM 4283, 04.2003. Rautenberg & Al., 1981, Influence of heat transfer between turbine and compressor on the performance of small turbocharger, International Gas Turbine Congress, Tokyo, Asme paper, 1981. Advances in Gas Turbine Technology 236 Ribaud, Y., 2004, Overall Thermodynamics Model of an Ultra Micro turbine, Journal of Thermal Science. 2004, Vol. 13, 4, pp. 297-301. Sacadura, J. F., 1993, Initiation aux transferts thermiques, Lavoisier Tec & Doc, Vol. 4 ème tirage 1993, pp. 1-439, ISBN. 2-85206-618-1. Verstraete, T. & al., 2007, Numerical Study of the Heat Transfer in Micro Gas Turbines, Journal of Turbomachinery. ASME, Octobre 2007, Vol.129, DOI: 10.1115/1.2720874, pp 835-841. Part 4 Combustion [...]... Coal Gasification Repowering Plant (Roll, 199 5) in the United States, in operation since 199 5; the Texaco process at the Tampa power station (Jenkins, 199 5), in commercial operation since 199 6; and an integrated coal gasification fuel cell combined cycle pilot plant, consisting of a gasifier, fuel cell generating unit and gas turbine, in test operation since 2002 by Electric Power Development Co Ltd in. .. concerning the IGCC system and gas turbine combustor using oxygenblown gasified coal fuel include: The Cool Water Coal Gasification Project (Savelli & Touchton, 198 5), the flagship demonstration plant of gasification and gasified fueled gas turbine generation; the Shell process (Bush et al., 199 1) in Buggenum, the first commercial plant, which started test operation in 199 4 and commercial operation in 199 8;... LNG gas turbine power generation 240 Advances in Gas Turbine Technology COAL GASIFIER HOT GAS CLEANUP Heat Gasifier exchanger GAS TURBINE Heat recovery steam generator (Desulfurizing/ Char collecting) Gas turbine Stack Gen erator Coal Char Char recovery equipment Air Steam turbine Trans former Gasification agent Pulverizer Slag hopper Compressor Cooling water Gen erator Fig 1 Schematic diagram of... any gas turbine load On the other hand, combustion Developments of Gas Turbine Combustors for Air-Blown and Oxygen-Blown IGCC 255 efficiency shows around 100 percent in the case where the gas turbine load was 25 percent or higher, by bypassing nitrogen to premix with the combustion air at low load conditions NOx(16%O2 ) ppm 99 .9 20 By-passing N2 in low-load condition, stable flame is maintained 15 99 .8... air-blown two-stage entrained-flow coal gasifier (Kurimura et al., 199 5), a hot/dry synthetic gas cleanup system (Nakayama et al., 199 0), and 150MW, 1773K(1500°C)class gas turbine combustor technologies for low-Btu fuel (Hasegawa et al., 199 8a) In order Developments of Gas Turbine Combustors for Air-Blown and Oxygen-Blown IGCC 241 to accept the various IGCC systems, 1773K-class gas turbine combustors of medium-Btu... using the oxygen-blown gasification are in their final stages for commencing commercial operations overseas 1.2 Progress in gas turbine combustion technologies for IGCCs The plant thermal efficiency has been improved by enhancing the turbine inlet temperature, or combustor exhaust temperature The thermal-NOx emissions from the gas turbines increase, however, along with a rise in exhaust temperature In. .. synthetic gas is then fed into the high-efficiency gas turbine topping cycle, and the steam cycle is equipped to recover heat from the gas turbine exhaust This IGCC system is similar to LNG fired gas turbine combined cycle generation, except for the gasification and the synthetic gas cleanup process, primarily IGCC requires slightly more station service power than an LNG gas turbine power generation 240 Advances. .. Developments of Gas Turbine Combustors for Air-Blown and Oxygen-Blown IGCC Takeharu Hasegawa Central Research Institute of Electric Power Industry Japan 1 Introduction From the viewpoints of securing a stable supply of energy and protecting our global environment in the future, the integrated gasification combined cycle (IGCC) power generation of various gasifying methods has been introduced in the world Gasified... Table 3 Combustion Intensity at the design point is 2.0×102 W/(m3•Pa) Tair Tfuel Tex P 700K 633K 1773K 1.4MPa 0.62 2.0×102 W/(m3•Pa) ex Combustion Intensity Table 3 Rated test conditions 3.1.2.1 Combustion emission characteristics 100 80 C.R ％ 100 99 .9 60 99 .8 40 99 .7 20 99 .6 HHV=4.2MJ/m3 CH4=1.0% NH3=1000ppm 0 0 20 40 60 80 Gas turbine load ％ Fig 10 Combustion emission characteristics 99 .5 100 η　％ Combustion... Concerning research into low-NOx combustion technology using oxygen-blown medium calorific fuel, other studies include: Hasegawa et al ( 199 7), investigation of NOx reduction technology using a small burner; and studies by Döbbeling et al ( 199 4), on low NOx combustion technology (which quickly mixed fuel with air using the double cone burner from Alstom Power, called an EV burner); Cook et al ( 199 4), on effective . resulting in an increase in the turbine inlet temperature. In the case of our study, the fuel flow increase is 3.5% in the non-insulated version and 8.5% in the insulated version. The turbine inlet. operation in 199 8; the Wabash River Coal Gasification Repowering Plant (Roll, 199 5) in the United States, in operation since 199 5; the Texaco process at the Tampa power station (Jenkins, 199 5), in. operation since 199 6; and an integrated coal gasification fuel cell combined cycle pilot plant, consisting of a gasifier, fuel cell generating unit and gas turbine, in test operation since 2002