Spallation Drilling for Deep Heat Mining July 2, 2007 Tobias - PowerPoint PPT Presentation

Spallation Drilling for Deep Heat Mining July 2, 2007 Tobias Rothenfluh Karol Príkopský Philipp Rudolf von Rohr July 2, 2007 rothenfluh @ipe.mavt.ethz.ch, ETH Zurich

Background Over ervie view Spallati ation on Drilling ng Previous ous Work: SCWO Ideas for New Project July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich 1

Background Deep Heat Mining The Future of Geothermal Energy, MIT press, 2006 July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich 2

Spallation Drilling Conventional drilling Spallation Drilling Flame jet spallation Zhiyue Xu et al. (2004) Holes spalled by a pulsed Laser July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich 3

Spallation Drilling „Thermal Fragmentation“ is used in Russia: Surface mining: Narrow vein ore extraction Thermal drilling device July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich 4

Spallation Drilling: Costs US Patent, Potter et al.,1998 July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich 5

Spallation Drilling: Principle O 2 Tester Group, MIT, 2005 Cooling water Fuel Flaw 1 2 Heat Penetration New Spall 3 4 Buckling US Patent, Potter et al.,1998 July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich 6

Spallation Drilling: Theoretical Approach Flame T Rock x July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich 7

Spallation Drilling: Theoretical Approach Flame T 0 T S T Fusion T Rock x T T T s s 0 rock temperature change at spallation July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich 7

Spallation Drilling: Theoretical Approach 1. A very simple approach for T S (Gray, 1965) Flame mechanical rock properties: T 0 T S T Fusion T E, , , c Rock semi - ∞ ( 1 ) x c T S E T T T s s 0 rock temperature change at spallation July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich 7

Spallation Drilling: Theoretical Approach 2. A more elaborate approach for T S (Rauenzahn and Tester, 1989) Flame Temperature profile: T x T exp u x / a T s r 0 T 0 T S T Fusion T Heat flux at surface: dT  q c u T Rock p s dx x 0 Compressive stress load: E T S s ( 1 ) x Weibull distribution (theory of failure): T T T s s 0 m rock temperature V median condition G 1 exp dV 0 . 5 change at spallation 0 0 July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich 8

Spallation Drilling: Theoretical Approach 2. A more elaborate approach for T S (Rauenzahn and Tester, 1989) Flame m 3 3 3 m  ( 1 ) q 2 0 . 693 m o T S 2 c E a C T 0 T S T Fusion p r L T Rock q . Heat flux to plate Weibull parameters 0 , , m x T T T s s 0 rock temperature change at spallation July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich 9

Link to LTR Supercritical conditions downhole Our SCWO-reactor Methanol Water Water-filled hole Oxygen Cooling Water H > 2.3 km p > 221 bar T flame 1200 C p = 250 bar July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich 10

SCWO Autoignition of flame July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich 11

Project Ideas I Modifications on reactor Situation downhole conditions (p,T) nozzle geometry free jet July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich 12

Project Ideas II . q July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich 13

Project Ideas II . q m 3 3 3 m  ( 1 ) q 2 0 . 693 m o T S 2 c E a C p r L → prediction of spall thickness July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich 13

Project Ideas II Insertion of a flat plate: . q m 3 3 3 m  ( 1 ) q 2 0 . 693 m Heat flux sensors: o T S 2 c E a C - Heat flux p r L - Surface temperature → prediction of spall thickness July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich 13

Project Ideas II Impinging flame jets – Heat transfer mechanisms 1. Convective heat transfer 2. Thermochemical heat release (TCHR) Flame 3. Radiative heat transfer Plate 4. Condensation Research goals: • Comparison of experimental results: → Heat Transfer Enhancement/Detereoration → Estimation of heat radiation • Simplified model of overall heat transfer July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich 14

Project Ideas III Ignition of Flame (Autoignition) Stability of Flame - Blowoff-Experiments - Flashback-Experiments Process Design Realistic operation conditions p, T July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich 15

Thanks for your attention! July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich 16