Presentaci

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NATIONAL INSTITUTE OF AEROSPACE TECHNOLOGY
OPTIMIZATION OF A SOLAR HYDROGEN STORAGE SYSTEM
SAFETY CONSIDERATIONS
Rosa Mª Rengel Gálvez Marina B. Gutiérrez
García-Arias
11/09/2007
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NATIONAL INSTITUTE OF AEROSPACE TECHNOLOGY

• Public organization for aerospace technology
  research and development.
• Since the early seventies, renewable and
  alternative energies have been one of the RD
  areas in which INTA has dedicated a continuous
  effort.
• In 1989, INTA started a program focussed on the
  use of hydrogen as a storage medium for solar
  electricity.
• Since 1990, interest in terrestrial use of fuel
  cells and hydrogen technologies.
• Facilities in Torrejón de Ardoz (Madrid) and El
  Arenosillo (Huelva).

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Hydrogen production from renewable energy,
mainly solar and wind.- Development of new
hydrogen storage systems.- PEMFC testing. -
Integration of PEMFC in transport applications.-
Development of hydrogen production systems from
fossil or renewable fuels.- Simulation of
hydrogen systems (energy and CFD aspects) .-
Safety.
AREAS OF INTEREST
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INTA SOLAR HYDROGENSTORAGE FACILITY

• Built up in the period 1992-1996.
• Original design passive and active safety
  measures ? legislation and good engineering
  practices , but not a specific risk assessment
  was done
• ATEX
• Pressure vessel regulations.
• Operational period additional safety
  recommendations from international standards ?
• ISO/TR 15916 Basic consideration for the safety
  of hydrogen system

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STORAGE FACILITY CHARACTERISTICS

• Hydrogen production rate 1.2 Nm3/h
• Hydrogen storage capacity enough for an
  operation week (25-30 Nm3)
• Operation during 48 weeks per year
• Charging cycles number higher than discharging
  cycles number
• Availability and reasonable cost for small
  facilities
• Other requirements availability, auxiliary
  systems, etc.

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RISK ASSESSMENT
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QUANTITATIVE RISK ASSESSMENT (QRA)
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HAZARD IDENTIFICATION
The objective is to determine a list of potential
incidents might be occurred to the accidents.

• WHAT CAN GO WRONG?

• METHODS
• FMEA
• HAZOP
• What-if analysis
• Check list analysis
• Fault tree analysis
• Event tree analysis

BEFORE THE PROJECT IS FULLY IMPLEMENTED OR A
REDESIGN OF A PLANT
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FMEA

• Qualitative method.
• FMEA systematic methodology to identify product
  and process problems, assessing their
  significance, and identifying potential solutions
  that reduce their significance.
• Each failure mode has a cause and a potential
  effect.
• Can be performed by two different approaches
  bottoms-up / top down.

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METHODOLOGY

• FMEA to the three different solar hydrogen
  storage systems gt failure modes, causes and
  effects.
• FMEA is an ongoing process and must be updated
  every time design or process changes are made gt
• Top-down approach.
• For a good quality hazard identification,
  complete information about the system must be
  compiled.
• The data was provided to a team with expertise on
  various aspects of hydrogen.

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FMEA Results for each hydrogen storage section
Process Hydrogen Storage    
Section Low pressure storage    
Design intent Store up to 6 Nm3 of hydrogen at 6 bar Store up to 6 Nm3 of hydrogen at 6 bar  
Nº Failure Mode Cause Effects
1 Storage tank failure Mechanical failure, corrosion, hydrogen embrittlement Release of hydrogen. Potential risk of fire or explosion
2 Piping/valves leak Mechanical failure Release of hydrogen. Potential risk of fire or explosion
3 Charging process fail Mechanical failure in hydrogen inlet valve, human error No hydrogen stored. Negative influence on electrolyzer
4 Discharging processfail Mechanical failure in hydrogen outlet valve,human error No hydrogen supply to metal hydride, high pressure sections nor fuel cells
5 Faulty PRD activation Defect/Fault in PRD, mechanical failure Release of hydrogen. Potential risk of fire or explosion
6 Overpressure combinedwith failure of PRD to open Mechanical failure in PRD, purge line closed Potential risk of catastrophic rupture of the storage unit
7 Formation of hydrogen/nitrogen mixtures in storage tank Mechanical failure in nitrogen inlet valve, human operation error Negative effects on metal hydrides kineticLess efficiency in fuel cells
8 Storage tank failure External fire Release of hydrogen. Potential risk of fire or explosionPotential risk of catastrophic rupture of the storage unit
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Process Hydrogen Storage    
Section Metal hydride storage    
Design intent Store up to 24 Nm3 of hydrogen in metal hydride Store up to 24 Nm3 of hydrogen in metal hydride  
Nº Failure Mode Cause Effects
9 Container failure Mechanical failure, corrosion, hydrogen embrittlement Release of hydrogen to atmosphere/cooling water.Potential risk of fire or explosion
10 Piping/valves leak Mechanical failure Release of hydrogen to atmosphere.Potential risk of fire or explosion
11 Overpressure in metal hydride container Fault in cooling water supply Potential risk of catastrophic rupture of the storage unit
12 Metal hydride failure High content of nitrogen in hydrogen Decrease of hydrogen charge rate. No safety hazard
13 Metal hydride failure Impurities in hydrogen gas Decrease of hydrogen charge ratePoisoning of metal hydride and loss of storage capacity. No safety hazard
14 Discharging process fail Fault in heating water supply No hydrogen supply to high pressure section or fuel cells. No safety hazard
15 Shell failure Mechanical failure, corrosion, hydrogen embrittlement Lack of cooling/heating water. No safety hazard
16 Cooling circuit piping/valves leak Mechanical failure Lack of cooling/heating water. No safety hazard
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Section High pressure storage    
Design intent Compress and store up to 36 Nm3 of hydrogen at 200 bar Compress and store up to 36 Nm3 of hydrogen at 200 bar  
Nº Failure Mode Cause Effects
17 Compressor suctionline failure Mechanical failure of line or fitting Release of hydrogen and potential fire or explosion
18 Lubrication systemfailure Loss of fluid Compressor failure and hydrogen leak with potential fire or explosion
19 Seal failure Mechanical failure Release of hydrogen and potential fire or explosion
20 Compressor suction ordischarge valve failure Mechanical failure No hydrogen supply to cylindersNo safety hazard
21 Pressure relief device fails open Mechanical failure Release of hydrogen. Potential risk of fire or explosion
22 Air driven supply fail Mechanical failure or human error and failure in compressed air line No hydrogen compression.No safety hazard
23 Valve on discharge of compressor fails closed Mechanical failure or human error and failure of pressure relief valve to open Overpressure compressor and rupture line. Release of hydrogen and potential fire or explosion
24 High pressure (200 bar)hydrogen supply line failure Mechanical failure Release of hydrogen and potential fire or explosion
25 Overpressure and fail storage tank Mechanical failure in hydrogen pressure regulator at compressor outlet Overpressure storage tank. PRV releases hydrogen with potential fire or explosion
26 Relief device failure (on cylinders) fails open Mechanical failure Release of hydrogen to atmosphere and potential fire or explosion
27 Storage tank failure Mechanical failure, corrosion, hydrogen embrittlement Release of hydrogen to atmosphere and potential fire or explosion
28 Piping/valves leak Mechanical failure Release of hydrogen to atmosphere and potential fire or explosion
29 High pressure fitting failure Mechanical failure, human error Release of hydrogen and potential fire or explosionPotential hazard due to high pressure
30 Storage tank failure External fire Potential failure of tank due to overheating of metal
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CONCLUSIONS

• Main potential failure modes
• container or cylinders failure,
• piping leaks and valves fails, originated by
  mechanical or material failure, corrosion or
  hydrogen embrittlement,
• human error.
• The results of the study have helped to identify
  a design inherent safety for the new facility,
  and identify potential prevention and/or
  mitigation corrective actions.
• Suitable choice of materials and the need of
  training of personnel are essential for safety
  purposes.

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Thanks for your attention.
rengelgrm_at_inta.es gutierrezgamb_at_inta.es