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

Spallation Drilling for Deep Heat Mining

July 2, 2007 rothenfluh @ipe.mavt.ethz.ch, ETH Zurich

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

• n Drilling

ng Previous

• us Work: SCWO

Ideas for New Project

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July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich

Background

The Future of Geothermal Energy, MIT press, 2006

Deep Heat Mining

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July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich

Spallation Drilling

Conventional drilling Spallation Drilling

Zhiyue Xu et al. (2004)

Flame jet spallation Holes spalled by a pulsed Laser

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July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich

Spallation Drilling

„Thermal Fragmentation“ is used in Russia: Surface mining: Narrow vein ore extraction Thermal drilling device

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July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich

Spallation Drilling: Costs

US Patent, Potter et al.,1998

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July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich

Spallation Drilling: Principle

O2

Tester Group, MIT, 2005

Fuel Cooling water

US Patent, Potter et al.,1998 2

Flaw

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New Spall

1

Heat Penetration

3

Buckling

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July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich

T x

Rock

Spallation Drilling: Theoretical Approach

Flame

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July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich

T x

Rock

TS T0 TFusion

Flame rock temperature change at spallation

T T T

s s

7

Spallation Drilling: Theoretical Approach

July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich

T x

Rock

TS T0 TFusion

• 1. A very simple approach for TS

(Gray, 1965)

E, , ,

c

mechanical rock properties:

Flame

E T

c S

) 1 (

semi - ∞ rock temperature change at spallation

T T T

s s

7

Spallation Drilling: Theoretical Approach

July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich

T x

Rock

TS T0 TFusion

Flame

T T T

s s

r s

T a / x u exp T x T

Temperature profile:

) 1 (

S s

T E

Compressive stress load: Heat flux at surface:

s p x

T u c dx dT q 

5 . exp 1

V m

dV G

Weibull distribution (theory of failure):

median condition

rock temperature change at spallation

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• 2. A more elaborate approach for TS

(Rauenzahn and Tester, 1989)

Spallation Drilling: Theoretical Approach

July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich

T x

Rock

TS T0 TFusion

Flame

T T T

s s

3 3 2 3

693 . 2 ) 1 (

m r L m

• p

S

a m C E c q T 

q Heat flux to plate

0 ,

, m Weibull parameters . rock temperature change at spallation

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• 2. A more elaborate approach for TS

(Rauenzahn and Tester, 1989)

Spallation Drilling: Theoretical Approach

July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich

Link to LTR

Supercritical conditions downhole

H > 2.3 km Water-filled hole

p > 221 bar

Our SCWO-reactor

Tflame 1200 C p = 250 bar

Methanol Water Oxygen Cooling Water

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July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich

SCWO

Autoignition of flame

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July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich

Project Ideas I

Situation downhole

nozzle geometry conditions (p,T) free jet

Modifications on reactor

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July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich

q .

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Project Ideas II

July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich

q . → prediction of spall thickness

3 3 2 3

693 . 2 ) 1 (

m r L m

• p

S

a m C E c q T 

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Project Ideas II

July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich

q . → prediction of spall thickness

3 3 2 3

693 . 2 ) 1 (

m r L m

• p

S

a m C E c q T  Heat flux sensors:

• Heat flux
• Surface temperature

Insertion of a flat plate:

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Project Ideas II

July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich

Flame Plate

Impinging flame jets – Heat transfer mechanisms

• 1. Convective heat transfer
• 2. Thermochemical heat release (TCHR)
• 3. Radiative heat transfer
• 4. Condensation

Research goals:

• Comparison of experimental results:

→ Heat Transfer Enhancement/Detereoration → Estimation of heat radiation

• Simplified model of overall heat transfer

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Project Ideas II

July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich

Ignition of Flame (Autoignition) Stability of Flame

• Blowoff-Experiments
• Flashback-Experiments

Process Design Realistic operation conditions

p, T

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Project Ideas III

July 2, 2007 rothenfluh@ipe.mavt.ethz.ch, ETH Zurich

Thanks for your attention!

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