ICHS - October 2015 Jérôme Daubech 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

Introduction Context of the present study Objectives 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

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

Preliminary tests matrix with steel cylinders No Sample Fire condition Volume [L] Position Fire source Distance heat source / cylinder [mm] impacted surface [%] 1a 36 Horizontal Radiation F1 300 100 1b Radiation F2 1c Radiation F3 1d Radiation F4 1e Radiation F5 2 Heptane 3 600 4 Radiation 100 (soot from 3) 5 50 6 Vertical 7 19 8 Hydrogen Q2 / 9 Hydrogen Q1 10 Propane Q1 11 12 Horizontal + cover

Instrumentation of steel cylinders 14/25 thread for pressure sensor Thermocouples crossing Thermocouples fixation and position Copper sealing

Preliminary tests matrix with steel cylinders No Sample Fire condition Volume [L] Position Fire source Distance heat source / cylinder [mm] impacted surface [%] 1a 36 Horizontal Radiation F1 300 100 1b Radiation F2 1c Radiation F3 1d Radiation F4 1e Radiation F5 2 Heptane 3 600 4 Radiation 100 (soot from 3) 5 50 6 Vertical 7 19 8 Hydrogen Q2 / 9 Hydrogen Q1 10 Propane Q1 11 12 Horizontal + cover 6 6

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

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.

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

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

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

Gas fire tests First observations: Numerical results: 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

Thermal aggression comparison 36 L cylinders 19 L cylinders Fire condition Temperature at 5 mn Temperature at 10 mn Pool – 10 cm distance – 36 L 170 °C 300 °C Gas fire – Hydrogen – Q2 – 36 L 320 °C Pool – 10 cm distance – 19 L 200 °C 400 °C Gas fire – Hydrogen – Q2 – 19 L 180 °C Test stopped before gas fire – Hydrogen – Q2 + cover – 19 L 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

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

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