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Industrial Prospective for Hydrogen Utilization
- Safety Aspect -
10 September 2005
K.Takeno
Mitsubishi Heavy Industries, Ltd.
MHI’s 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.
Energy Chain through Hydrogen
Natural Energy (Wind, Solar, Biomass)
Steam Reformation
Gas Engine
(η ~44%)
Storage of
Hydrogen
Nuclear Energy
H2
Natural Gas
Fossil Energy (Natural Gas, Oil)
Electrolysis of Water
Electricity
Membrane Reformation
Direct Production from Water
Gas Turbine
(η ~41%)
PEFC
(η ~60%)
Special Use
(rocket etc)
H2
As the final conversion device from hydrogen, PEFC has highest efficiency
On-site hydrogen station
Role of Hydrogen in Natural Energy System
Wind Power
Methanol(Storage)
Electricity
DC/AC
Power Source
O2
H2
DC/AC
Solar Cell
Biomass Gasificationto produce H2 and
CO
Solid Polymer Water Electrolysis
Rechargeable battery
Polymer Electrolyte Fuel Cell
Solid Oxide Fuel Cell
If biomass gasification is combined, performance becomes higher (oxygen from electrolysis can be utilized and carbon from biomass can be fixed to liquid fuel).
Engine
Introduction of Future Plan (RERE System)* RERE(Renewable Energy based Rural Electrification)
Research on Safety
WindBuoyancy
Flow & Diffusion
Mixing of air with H2
EXPLOSION orEXPLOSION orDiffusion FlameDiffusion Flame
Leak of LH2 (Liquid) or GH2 (High-PressurizedGas)
H2Tank
LH2 : Evaporation Diffusion GH2 : Diffusion
Flammable H2/Air Mixture
Pressure WaveRadiation
Research on Safety (continued)
# Evaporation of LH2
# Diffusion of GH2
# Immediate Ignition ⇒ Diffusion Flame
# Delayed Ignition ⇒ Explosion# Spread of Flammable Mixture
# Scale of Diffusion Flame
# Propagation of Pressure Wave
# Radiation from High Temp. Steam
Hypothesis Accidents
Experiments
Computer Simulation
Evaluation of Safety
(Risk Analysis)
Probability study
Safety Regulation
Research on Safety (continued)
21m 3.6m
100
1000
10000
100000
0.0001 0.001 0.01 0.1 1 10 M (kg/ s)流量
Lf
(m
m)
火炎
長
10.0 5.02.0 1.170.53 0.32
噴出口径(mm)
16700・M0.5
Flow Rate of H2 Gas
Len
gth
of
Fla
me
Nozzle diam.
High-pressure H2 flame( d=10mm, P=28MPa)(Visualized by Na addition)
Lig=31.5mm
Schuliren photo image ( d=1mm , P=20MPa )(Flame is stabilized behind shock wave)
][:6.71/
2.399/48.0
max
5.0
MPaPPdr
PdL
f
f
Correlation of flame scale Lf: flame length rfmax: maximum flame diameter d: nozzle (opening) diameterThis formula is used for the Japanese regulation of hydrogen safety.
Research on Safety (continued)
75 ~ 90m/s
Large scale (300m3) explosion experiment, conducted by IAE / SRI(H2 (30%) / Air mixture)
Velocity of flame propagation
[Pa]
Typical result on the atmospheric diffusion of leaked H2 at an assumed hydrogen supply station.(40MPa-400m3, d=10mm opening, t=3s)
Pressure distribution at t=100ms
Natural Energy (Wind, Solar, Biomass)
Steam Reformation
Gas Engine
(η ~43%)
Storage of
Hydrogen
Nuclear Energy
H2
Natural Gas
Fossil Energy (Natural Gas, Oil)
Electrolysis of Water
Electricity
Membrane Reformation
Direct Production from Water
Gas Turbine
(η ~39%)
PEFC
(η ~60%)
Special Use
(rocket etc)
H2
Total Efficiency from NG
via H2 direct use ~29% ~42%
~27% ~39%
~42%
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.
Atomic Furnace
H2
Reformation
CH4
CH4+ H2O+heat→CO+3H2
Membrane
Catarist
City gas Steam
Heat Membrane
Catarist
Hydrogen
Membrane Reformer
This can be operated at low temperature (~ 550 ) and conversion efficiency is high (℃ ~ 75%)