Industrial Prospective for Hydrogen Utilization - Safety Aspect -

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Industrial Prospective for Hydrogen
Utilization- Safety Aspect -

• 10 September 2005
• K.Takeno
• Mitsubishi Heavy Industries, Ltd.

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MHIs Activities for Hydrogen
MHI, general machinery and power plant maker,
focuses on two aspects concerning hydrogen. 1.
When hydrogen is used as the alternative energy
resources from fossil energy, we should provide
the high-quality and high-efficiency devices for
hydrogen production, storage, and utilization. 2.
Utilization as the media of energy chain among
natural reproducible energy (wind, solar,
geothermal, water, biomass, etc.), and nuclear
energy.
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Energy Chain through Hydrogen
On-site hydrogen station
As the final conversion device from hydrogen,
PEFC has highest efficiency
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Role of Hydrogen in Natural Energy System
Electricity
DC/AC
DC/AC
H2
Wind Power
O2
Solid Polymer Water Electrolysis
Polymer Electrolyte Fuel Cell
Solar Cell
Rechargeable battery
Methanol (Storage)
Solid Oxide Fuel Cell
Engine
Biomass Gasification to produce H2 and CO
Power Source
If biomass gasification is combined, performance
becomes higher (oxygen from electrolysis can be
utilized and carbon from biomass can be fixed to
liquid fuel).
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Introduction of Future Plan (RERE System)
RERE(Renewable Energy based Rural
Electrification)
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Research on Safety
Wind
Mixing of air with H2
Buoyancy
Flow Diffusion
LH2 Evaporation Diffusion GH2 Diffusion
Flammable H2/Air Mixture
EXPLOSION or Diffusion Flame
Pressure Wave Radiation
Leak of LH2 (Liquid) or GH2
(High-PressurizedGas)
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Research on Safety (continued)
Hypothesis Accidents
Probability study
Evaporation of LH2 Diffusion of GH2
Immediate Ignition ? Diffusion Flame
Delayed Ignition ? Explosion
Experiments Computer Simulation
Spread of Flammable Mixture Scale of
Diffusion Flame Propagation of Pressure Wave
Radiation from High Temp. Steam
Evaluation of Safety (Risk Analysis)
Safety Regulation
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Research on Safety (continued)
High-pressure H2 flame(d10mm,P28MPa) (Visualized
by Na addition)
Correlation of flame scale Lf flame
length rfmax maximum flame diameter
d nozzle (opening) diameter This
formula is used for the Japanese regulation of
hydrogen safety.
Schuliren photo image(d1mm,P20MPa) (Flame is
stabilized behind shock wave)
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Research on Safety (continued)
Large scale (300m3) explosion experiment,
conducted by IAE / SRI (H2 (30) / Air mixture)
Typical result on the atmospheric diffusion of
leaked H2 at an assumed hydrogen supply
station. (40MPa-400m3, d10mm opening, t3s)
Velocity of flame propagation
Pressure distribution at t100ms
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Principal Conclusion and Perspectives
Problem seems to be the energy efficiency. It
is difficult to overcome the direct use of
natural gas to gas engine or turbine. At the
standpoint of industrial researcher, it is the
urgent demand to raise the conversion efficiency
from NG or nuclear energy to hydrogen.
Specially, MHI expects membrane reformer, which
can be operated at low temperature (550?) and
conversion efficiency is high (75). From CO2
problem, the use of natural renewable energy is
expanding globally. If hydrogen is the core of
energy flow, many kinds of natural energy can be
combined.
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Membrane Reformer
CH4H2Oheat?CO3H2
This can be operated at low temperature (550?)
and conversion efficiency is high (75)