Humidification in Evaporative Power Cycles

Evaporative gas turbine cycles (EvGT) show an exceptionalexhaust heat recovery potential, which makes them a strongcompetitor to other advanced gas turbine cycles, especiallyfrom small to intermediate sizes. Evaporative gas turbines aredistinguished by humidifying the working fluid beforecombustion at temperatures below the boiling point of water;and the heat required for evaporation of water is partly takenout of the exhaust gas. Thus, humidification is a key operationin these cycles. This thesis investigates, both theoreticallyand experimentally, two alternative approaches tohumidification: the packed-bed humidification tower and thetubular humidifier. Both these equipments involvecountercurrent contact between water and the working fluid.Humidifier design criteria are developed and criticalparameters such as flooding, wetting rate and entrainment arediscussed. The experimental parts were carried out on thepacked-bed tower in the EvGT pilot plant, and on a tubularhumidifier test rig especially erected for this purpose. Thetheoretical models were confirmed by the experiments.The height of a transfer unit, necessary for designingpacked beds, was calculated for the packing employed in theEvGT pilot plant. It was found that the data provided by themanufacturer may be used with minor corrections.The tubular test rig operated satisfactorily delivering hothumid air. The theoretical models coincided well with theexperimental results, verifying the design criteria developedhere. The heat transfer calculations indicated that mostresistance to heat transfer is on the exhaust gas side. Thus, asurface extended tube (Sunrod) was used in the test rig. Itcould be concluded that the tubular humidifier is a strongalternative to the packed-bedtower, especially in smallhigh-pressure gas turbines.Furthermore, the importance of the non-ideality of theair-water vapor mixture in modeling evaporative cycles wasfirst highlighted in this work. Through applying realthermodynamic properties of air-water vapor mixtures in cyclecalculations, it was found that the compressed air contains ahigher amount of moisture than indicated by the ideal gasmixture model. This affects the design of the heat recoverysystem and cannot be neglected.Key words:evaporative gas turbine, indirect-fired gasturbine, humidification, packed bed, tubular humidifier,evaporator, saturator.

[1]  V. S. Vaidhyanathan,et al.  Transport phenomena , 2005, Experientia.

[2]  Niklas Ågren.  Advanced Gas Turbine Cycles with Water-Air Mixtures as Working Fluid , 2000 .

[3]  Marie Anheden,et al.  Thermodynamic Performance Analysis and Economic Evaluation of Externally Fired Gas Turbine Cycles for Small Scale Biomass Cogeneration , 1999 .

[4]  Torbjörn Lindquist.  Evaluation, Experience and Potential of Gas Turbine Based Cycles with Humidification , 2002 .

[5]  Jinyue Yan,et al.  Saturated thermodynamic properties for the air¿water system at elevated temperatures and pressures , 2003 .

[6]  L. Greenspan,et al.  Functional Equations for the Enhancement Factors for CO2-Free Moist Air , 1976, Journal of research of the National Bureau of Standards. Section A, Physics and chemistry.

[7]  A. Colburn,et al.  Mass Transfer (Absorption) Coefficients Prediction from Data on Heat Transfer and Fluid Friction , 1934 .

[8]  Holger Venzke,et al.  Interpolation Correlations for Fluid Properties of Humid Air in the Temperature Range 100 °C to 200 °C , 1997 .

[9]  J. Prausnitz,et al.  Equilibrium Data for Wet-Air Oxidation. Water Content and Thermodynamic Properties of Saturated Combustion Gases , 1977 .

[10]  李幼升,et al.  Ph , 1989 .

[11]  A. Wexler,et al.  The Enhancement of Water Vapor in Carbon Dioxide-Free Air at 30, 40, and 50 °C. , 1973, Journal of research of the National Bureau of Standards. Section A, Physics and chemistry.

[12]  Ruixian Cai,et al.  Modeling HAT cycle and thermodynamic evaluation , 1997 .

[13]  J. H. Harker,et al.  Fluid flow, heat transfer and mass transfer , 1996 .

[14]  J. H. Harker,et al.  Coulson & Richardson's chemical engineering , 1996 .

[15]  P. Mazzei,et al.  Thermodynamic Analysis and Improvement of Energy Systems , 1989 .

[16]  Yunhui Wang,et al.  Analysis of Effects on Wet Compression on Surge Margin of a Small Gas Turbine , 2002 .

[17]  Jinyue Yan,et al.  Externally Fired Evaporative Gas Turbine With a Condensing Heat Exchanger , 1996 .

[18]  A. Wexler,et al.  The Second Interaction (Cross) Virial Coefficient for Moist Air. , 1973, Journal of research of the National Bureau of Standards. Section A, Physics and chemistry.

[19]  Robert M. Enick,et al.  A robust algorithm for high-pressure gas humidification , 1995 .

[20]  Ralph F. Strigle,et al.  Packed tower design and applications : random and structured packings , 1994 .

[21]  Mats Westermark,et al.  Design Study of Part Flow Evaporative Gas Turbine Cycles — Performance and Equipment Sizing:Part 2, Industrial Core , 2001 .

[22]  Jinyue Yan,et al.  Biomass Externally Fired Gas Turbine Cogeneration , 1996 .

[23]  Umberto Desideri,et al.  The Humid Air Cycle: Some Thermodynamic Considerations , 1993 .

[24]  C. Wormald,et al.  Excess enthalpies for (water + nitrogen)(g) up to 698.2 K and 12.6 MPa , 1983 .

[25]  Waldyr Luiz Ribeiro Gallo,et al.  A comparison between the hat cycle and other gas-turbine based cycles: Efficiency, specific power and water consumption , 1997 .

[26]  Ennio Macchi,et al.  An Assessment of the Thermodynamic Performance of Mixed Gas-Steam Cycles: Part B—Water-Injected and HAT Cycles , 1995 .

[27]  A. Wexler,et al.  FORMULATIONS FOR THE THERMODYNAMIC PROPERTIES OF THE SATURATED PHASES OF H2O FROM 173.15 TO 473.15 K. , 1983 .

[28]  Michael Bartlett.  Developing Humidified Gas Turbine Cycles , 2002 .

[29]  Mats Westermark,et al.  First Experiments on an Evaporative Gas Turbine Pilot Power Plant: Water Circuit Chemistry and Humidification Evaluation , 2002 .

[30]  R. Hyland,et al.  Formulations for the thermodynamic properties of dry air from 173.15 K to 473.15 K, and of saturated moist air from 173.15 K to 372.15 K, at pressures to 5 MPa , 1983 .

[31]  Jinyue Yan,et al.  Performance evaluation of biomass externally fired evaporative gas turbine system , 1994 .

[32]  R. Hyland.  A Correlation for the Second Interaction Virial Coefficients and Enhancement Factors for Moist Air. , 1975, Journal of research of the National Bureau of Standards. Section A, Physics and chemistry.

[33]  Packed tower design and applications , 1994 .

[34]  Mats Westermark,et al.  An analysis of the efficiency and economy of humidified gas turbines in district heating applications , 2004 .

[35]  J. J. Tuzson,et al.  Status of Steam-Injected Gas Turbines , 1992 .

[36]  Cyrus B. Meher-Homji,et al.  Inlet Fogging of Gas Turbine Engines: Part A — Theory, Psychrometrics and Fog Generation , 2000 .

[37]  Hiroshi Takeuchi,et al.  MASS TRANSFER COEFFICIENTS BETWEEN GAS AND LIQUID PHASES IN PACKED COLUMNS , 1968 .

[38]  Jacques De Ruyck,et al.  Progress of an Externally Fired Evaporative Gas Turbine Cycle for Small Scale Biomass Gasification , 1999 .

[39]  J. De Ruyck,et al.  REVAP® Cycle: A New Evaporative Cycle Without Saturation Tower , 1996 .

[40]  E. R. Gilliland,et al.  Diffusion of Vapors into Air Streams , 1934 .

[41]  Russell G. Wylie and,et al.  Molecular Interaction of Water Vapor and Air , 1996 .

[42]  Svend Bram,et al.  REVAP® cycle : A new evaporative cycle without saturation tower , 1996 .

[43]  P. B. Whalley,et al.  A comparison between flooding correlations and experimental flooding data for gas-liquid flow in vertical circular tubes , 1985 .

[44]  Mats Westermark,et al.  First Experiments on an Evaporative Gas Turbine Pilot Power Plant: Water Circuit Chemistry and Humidification Evaluation , 2000 .

[45]  Jinyue Yan,et al.  Thermodynamic Property Models for the Simulation of Advanced Wet Cycles , 2003 .

[46]  Jinyue Yan,et al.  Economic Assessment of Evaporative Gas Turbine Cycles With Optimized Part Flow Humidification Systems , 2003 .

[47]  K. D. Luks,et al.  Correlation of the Equilibrium Moisture Content of Air and of Mixtures of Oxygen and Nitrogen for Temperatures in the Range of 230 to 600 K at Pressures up to 200 Atm , 1976 .

[48]  J. H. Harker,et al.  Particle technology and separation processes , 1991 .

[49]  Mats Westermark,et al.  Design Study of Part Flow Evaporative Gas Turbine Cycles: Performance and Equipment Sizing: Part 1 — Aeroderivative Core , 2001 .

[50]  Jinyue Yan,et al.  An Investigation of the Heat Recovery System in Externally Fired Evaporative Gas Turbines , 1995 .

[51]  M. Muir.  Physical Chemistry , 1888, Nature.

[52]  I. N. Gosparovic,et al.  Gas turbines with heat exchanger and water injection in the compressed air , 1973 .

[53]  Qun Zheng,et al.  Thermodynamic Analyses of Wet Compression Process in the Compressor of Gas Turbine , 2003 .