Steam Microturbines in Distributed Cogeneration

This book presents the most recent trends and concepts in power engineering, especially with regard to prosumer and civic energy generation. In so doing, it draws widely on his experience gained during the development of steam microturbines for use in small combined heat and power stations based on the organic Rankine cycle (CHP-ORC). Major issues concerning the dynamic properties of mechanical systems, in particular rotating systems, are discussed, and the results obtained when using unconventional bearing systems, presented. Modeling and analysis of radial-flow and axial-flow microturbines are addressed in detail, covering rotor analysis with different bearing systems, simulation modal analysis, and stress analysis. Furthermore, experimental studies of the dynamic properties of microturbine elements are extensively described. Interest in distributed generation and CHP-ORC is growing rapidly, and the potential market for such systems promises to be very large. This book will be of value for engineers and scientists involved in the design, modeling, operation, and diagnostics of various types of turbomachinery, especially steam microturbines. Preface 5 Contents 8 1 Distributed Cogeneration. Civic Power Engineering. New Ideas 11 Abstract 11 1.1 New Energy Policy of the European Union. Civic Energy Generation 11 1.2 Installations for Distributed Energy. The Examples of DESRES Devices and Technologies 14 1.3 Domestic CHP ORC Units 15 1.4 Autonomous Energy Regions (ARE) 20 1.5 Research Center in Jabłonna 23 1.6 Concluding Remarks 25 References 26 2 Introduction to Microturbines Vibration Analysis 27 Abstract 27 2.1 Characteristics of Microturbines 27 2.2 Introduction to Vibrations of Mechanical Systems 30 2.2.1 The Equation of Motion 30 2.2.2 Free Vibrations 31 2.2.3 Damping of Vibrations in Mechanical Systems 32 2.2.4 Forced Vibrations 33 2.3 Vibrations of Rotating Systems 33 2.3.1 Hydrodynamic Instability 36 2.3.2 Kinetostatic Analysis 37 2.3.3 Analysis in the Scope of Linear Dynamics 38 2.3.4 Analysis in the Scope of Non-linear Dynamics 40 2.4 Modern Research Methods and Tools 41 2.4.1 Software 41 2.4.2 Test and Measurement Apparatus 44 References 46 3 Unconventional Bearings 48 Abstract 48 3.1 General Information about Microbearings 49 3.2 Bearings Lubricated with a Low-Boiling Medium 51 3.2.1 Hydrodynamic Bearings 53 3.2.2 Hybrid Bearings 55 3.3 Foil Bearings 57 3.3.1 Geometry of Foil Bearings 59 3.3.1.1 Simplified 2-D Model 65 3.3.2 Numerical Model of the Foil Bearing Structure 69 3.3.2.1 Simplified 2-D Model 76 3.3.3 Verification of the Structural Model 80 3.3.3.1 Verification in the Range of Static Loads 81 3.3.3.2 Verification in the Scope of Dynamic Loads 86 3.3.4 Modelling the Fluid-Structure Interaction 90 3.3.5 Experimental Verification of the Model 93 3.3.5.1 Analysis of Rotor with Foil Bearings 105 3.4 Other Bearing Methods 112 3.4.1 High-Speed Rolling Bearings 112 3.4.2 Magnetic Bearings 115 References 119 4 Modelling and Analysis of Vibrations of Microturbines 121 Abstract 121 4.1 Radial Microturbine 122 4.1.1 Analysis of Rotor with Slide Bearings 123 4.1.2 Analysis of Rotor with Gas Bearings 126 4.1.3 Analysis of Rotor with Foil Bearings 134 4.1.4 Modal Analysis of the Rotor 138 4.1.5 Modal Analysis of the Microturbine 140 4.1.6 Analysis of Kinetostatic Stresses 143 4.1.7 Analysis of Thermal Loads 145 4.1.8 Analysis of Stiffness of Bearing Supports 151 4.2 Axial Microturbine 157 4.2.1 Analysis of Rotor with Slide Bearings 158 4.2.2 Analysis of Rotor with Rolling Bearings 161 4.2.3 Modal Analysis of the Rotor 164 4.2.4 Modal Analysis of the Microturbine 166 4.2.5 Analysis of Kinetostatic Stresses 169 4.3 Summary 170 References 171 5 Measurements of Vibrations of Microturbine Elements 173 Abstract 173 5.1 Experimental Modal Analysis of the Rotor 174 5.1.1 Method of Testing 176 5.1.2 Test Results 179 5.2 Vibrations of the Rotor with Ceramic Rolling Bearings 182 5.2.1 Method of Testing 182 5.2.2 Test Results 184 5.3 Vibrations of the Radial Microturbine 195 5.4 Vibrations of an Ultrasonic Microturbine 202 5.4.1 Time Courses 205 5.4.2 Frequency Analysis 207 5.4.3 Evaluation of the Dynamic State 210 5.5 Vibrations of the Microturbine Supporting Structure 212 5.5.1 Method of Testing 213 5.5.2 Test Results 214 References 219 Index 221 Front Matter....Pages i-xi Distributed Cogeneration. Civic Power Engineering. New Ideas....Pages 1-16 Introduction to Microturbines Vibration Analysis....Pages 17-37 Unconventional Bearings....Pages 39-111 Modelling and Analysis of Vibrations of Microturbines....Pages 113-164 Measurements of Vibrations of Microturbine Elements....Pages 165-212 Back Matter....Pages 213-219