ICHS - October 2015 Jérôme Daubech

1. FULL SCALE EXPERIMENTAL CAMPAIGN TO DETERMINE THE ACTUAL HEAT FLUX PRODUCED BY FIRE ON COMPOSITE STORAGES - CALIBRATION TESTS ON METALLIC VESSELS ICHS - October 2015 Jérôme Daubech

2. Introduction • Context of the present study • It is a part of a project whose main objectives are to characterize: • The behaviour of composite vessels under fire • The conditions that are required to prevent from bursting • It deals with preliminary calibration tests performed with steel cylinders Objectives • Definition of thermal aggression to be used as a reference for testing real reservoirs • Define the best conditions of tests to ensure reliability, reproducibility and safety of the test • Check that the tests performed at large scale in laboratory are representative of real fire scenarii and worst case scenarii

3. General concerns • Input from risk analysis • A heat flux in the surface of the cylinder of 125 kW.m-2 should be reached. • The fire should be well ventilated so as to maximize the power of fire. • The passive barriers such as metallic shields should not be used for the tests. • An engulfing fire should be performed. • several fire sources have to be studied and hierarchized Methodology of classification of thermal loads • The methodology developed has two purposes: • Classify by intensity the different thermal loads • “Translate” a complex load into a simple incident radiative heat flux • Use of steel cylinder to prevent from composite burning impact • Use of radiant panels to develop abacuses

4. Preliminary tests matrix with steel cylinders

5. Instrumentation of steel cylinders • Steel cylinders: • 19 L • 36 L • 14/25 thread for pressure sensor • Thermocouples crossing • Thermocouples fixation and position • Copper • sealing

6. Preliminary tests matrix with steel cylinders 6

7. Radiative tests results • 5 tests from 30 to 80 kW/m² • 20 mn maximum • Curves fit between average internal calculation (dot) and pressure calculation (line) • => Usefull for non-ungulfing fires comparison • Panels don’t provide enough power to compare with real fires tests • => Necessity of extrapolation for fictive higher radiant panels power Radiant panels at 30 cm of the cylinder Thermal shield

8. Radiative tests extrapolation • Model developed taking into account: • Dimensions of cylinder and radiant panels • Physical characteristics of steel cylinder • Relative position of cylinder and radiant panels • Will be used for superimposition of curves obtained during real fire tests • => Input data for development and validation of numerical approach.

9. Pool fire tests • Circular tank 1 m² • Between 10 and 20 mn of test • 10 cm or 60 cm between the top of the tank and the cylinder • For 50 % impacted surface: 0.5 to 0.6 m² • For vertical test: • 10 cm between the top of the tank and the cylinder

10. Pool fire tests • First observations: • Flame strongly impacted by ventilation • Hard to maintain an engulfing fire • After 10 mn, with “red curve” as reference: • Strong influence of the cylinder volume: 100°C difference • Strong influence of the impacted surface: 200°C difference • Medium influence of the orientation of the cylinder: 40 °C difference • Low influence of the distance from the pool: < 10°C

11. Gas fire tests • Hydrogen: • 4 injectors DN 8 • D1: 2,8 g/s • D2: 6 g/s • ∆Hc=140 MJ/kg • 10 to 20 mn • Tests performed on 36L • and 19 L cylinders, with • various configurations • Test with propane: • 8 g/s per injector • ∆Hc=50 MJ/kg • 15 to 20 mn • Test performed on 36 L • => The amount energy Q1 which is provided to cylinder is equivalent between propane test and D1 hydrogen test

12. Gas fire tests • First observations: • Low impact of the ventilation on the Flame due to momentum of the jet • Numerical results: • Strong influence of the flow rate of combustible: 250°C difference after 10 mn • Less influence of vessel size than with pool fire • In the tested conditions, for the same amount of energy provided, evolution of temperature is similar with propane and hydrogen

13. Thermal aggression comparison • For 36 L cylinders, the injection retained allow to meet bonfire test results • For 19 L cylinders, a confinement is needed to reach the energy provided to cylinder in bonfire tests => Use of confinement allows to be at least equivalent to pool bonfire tests 36 L cylinders 19 L cylinders

14. Learning and perspectives Hydrogen gas fire will be retained because: Realistic scenario: • Hydrogen is the combustible that we every time find near an hydrogen storage … Not too complex and not too expensive experimental test: • The best way to do is with radiant panels, that will be destroyed after each test : not realistic • Standard pool bonfires involve repeatability issues • Gas fire allows to control the time of thermal aggression Projection to normative test: • Characterization of the test is quite easy (Mass flow, injector diameter, distance …) • Repeatability is better than with pool fire (low influence of ventilation and vessel size) => In the conditions tested, the amount of energy provided by an hydrogen gas fire is at least equivalent to pool bonfires performed

15. Learning and perspectives • Output data: • Due to previous considerations, Hydrogen gas fire is retained • Use of 4 injectors, with at least 1,5 g/s flow rate per injector • Use of confinement so as to increase the energy received by the cylinder • Experimental fire tests keep on going on • real composite H2 storage tanks