1

化学反応、燃焼とCO2隔離Chemical Reaction ,Combustion and CO2 sequestration

Bill

ion

ton

(oil)

/ ye

ar

coal

oil

natural gas

atomic power

waterpower

New energy ?

Oil shock (2nd)

Oil shock (1st)

Increase of fossil-fuel consumption

Increase of CO2 concentration

futurepast

Global warming

Measures for CO2 mitigation

Oil :45 yearsNatural gas :65 yearsCoal :230 years

(1) promotion ofenergy saving

(2) renewable energy

(3) sequestration of CO2

Present talk

Promotion ofenergy saving

Polymer electrolyte fuel cells (PEFCs)

vehicle applications local on- site power generation system

Sequestration of CO2

CO2 ocean / underground Sequestration

Understanding mass transport phenomenaincluding reactionin PEFC and CO2 ocean sequestration is necessary for implementation

Phase diagram of H 2O- CO2 - hydrate

100

50

10

5

1

ｐ[M

Pa]

275 280 285 290

T [K]

Hydrate｜Liquid CO2｜H2O

Liquid CO2｜H2O

CO2 gas｜H2O

Hydrate｜CO2 gas｜H2O

Intermediate and deep ocean

Liquid CO 2 H2O

CO2 hydrate

Large cage Small cage

CO2 molecule

mass transport phenomena in CO 2 ocean sequestration

2

Liquid CO 2 droplets

Direct dissolution of CO 2

CO2 dissolved seawater

Initial stage

Liquid CO2

H2O

Pipe wall

massivehydrate plugs liquid CO2 to discharge

liquid CO 2could be discharged if hydrate keeps thin film

Liquid CO2

H2O

What is the conditions to distinguish these two types?

P=400[kgf/cm2] , T=7.2[℃]

Polycarbonate wall

Stainless wall

Liquid CO 2

Hydrate film

H2O

Stainless wall Polycarbonate wall

massive hydrate formation

No massive hydrate formation

low-polar-surface free energy

high-polar-surface free energy

use of low-polar surface free energy material for pipe wall would prevent massive hydrate growth to plug liquid CO 2 discharge

direct dissolution typedirect dissolution type

CO2 droplet dissolution must finish before arriving seasurfaceCO2 droplet dissolution must finish before arriving seasurface

Control of released liquid CO2 droplet sizeControl of released liquid CO2 droplet size

Fundamental understanding of liquid CO2 injection behavior with hydrate

Fundamental understanding of liquid CO2 injection behavior with hydrate

Injection and Boiling of

Liquid CO2 with Hydrate

direct dissolution typedirect dissolution type

Control of released liquid CO2 droplet sizeControl of released liquid CO2 droplet size

Liquid CO2 injection behaviorwith hydrateLiquid CO2 injection behaviorwith hydrate

CO2 droplet dissolution must finish before arriving seasurfaceCO2 droplet dissolution must finish before arriving seasurface

500m

Boiling of liquid CO2 with hydrate due to decompressionBoiling of liquid CO2 with hydrate due to decompression

gas

liquidP

Experimental apparatus for injection behavior

Hydrate filmNozzle diameter 1.6(mm)

LiquidCO 2

3

Map of injection behavior of liquid CO2 with hydrate varying injection velocity and temperature

0

5

10

15

20

25

30

35

0 1 2 3 4 5 6 7 8 9 10 11

Temperature [ ℃]

Inje

ctio

n ve

loci

ty [

cm/s

ec]

(a ) sphere -like droplet separation

(b) Slenderdropletformation

(c) Dropletformation fromthe hydratecolumn

Hydrateformation

Tension of hydrate LargeSmall

Propagation velocity of hydrateLarge Small

(1) Single droplet perfectly covered with the hydrate film

(3) Droplet formation from laminar flow

(2) Single droplet not perfectly covered with the hydrate film

Map of injection behavior of liquid CO2 with hydrate varying injection velocity and temperature

0

5

10

15

20

25

30

35

0 1 2 3 4 5 6 7 8 9 10 11

Temperature [ ℃]

Inje

ctio

n ve

loci

ty [

cm/s

ec]

(1) Single droplet perfectly covered with the hydrate film

(2) Single dropletnot perfectlycovered with thehydrate film

(3) Droplet formation from laminar flow

(a ) sphere -like droplet separation

(b) Slenderdropletformation

(c) Dropletformation fromthe hydratecolumn

Hydrateformation

Map of injection behavior of liquid CO2 with hydrate varying injection velocity and temperature

0

5

10

15

20

25

30

35

0 1 2 3 4 5 6 7 8 9 10 11

Temperature [ ℃]

Inje

ctio

n ve

loci

ty [

cm/s

ec]

(1) Single droplet perfectly covered with the hydrate film

(2) Single dropletnot perfectlycovered with thehydrate film

(3) Droplet formation from laminar flow

(a ) sphere -like droplet separation

(b) Slenderdropletformation

(c) Dropletformation fromthe hydratecolumn

Hydrateformation

Map of injection behavior of liquid CO2 with hydrate varying injection velocity and temperature

0

5

10

15

20

25

30

35

0 1 2 3 4 5 6 7 8 9 10 11

Temperature [ ℃]

Inje

ctio

n ve

loci

ty [

cm/s

ec]

(1) Single droplet perfectly covered with the hydrate film

(2) Single dropletnot perfectlycovered with thehydrate film

(3) Droplet formation from laminar flow

(a ) sphere -like droplet separation

dropletformation

(c) Dropletformation fromthe hydratecolumn

Hydrateformation

(b) Slender

4

Map of injection behavior of liquid CO2 with hydrate varying injection velocity and temperature

0

5

10

15

20

25

30

35

0 1 2 3 4 5 6 7 8 9 10 11

Temperature [ ℃]

Inje

ctio

n ve

loci

ty [

cm/s

ec]

(1) Single droplet perfectly covered with the hydrate film

(2) Single dropletnot perfectlycovered with thehydrate film

(3) Droplet formation from laminar flow

(a ) sphere -like droplet separation

(b) Slenderdropletformation

Hydrateformation

(c) Dropletformation fromthe hydratecolumn

Map of injection behavior of liquid CO2 with hydrate varying injection velocity and temperature

0

5

10

15

20

25

30

35

0 1 2 3 4 5 6 7 8 9 10 11

Temperature [ ℃]

Inje

ctio

n ve

loci

ty [

cm/s

ec]

(1) Single droplet perfectly covered with the hydrate film

(2) Single dropletnot perfectlycovered with thehydrate film

(3) Droplet formation from laminar flow

(a ) sphere -like droplet separation

(b) Slenderdropletformation

(c) Dropletformation fromthe hydratecolumn

Hydrateformation

Injection Behavior with Lateral Flow(Typical case)

P

P

Hydrate film Nozzle diameter 1.6(mm)

Liquid CO2

5

Lateral water flowLiquid CO2 droplet with and without hydrate film

Buoyancy

Water flow

Boiling of Liquid CO2 by Decompression with Hydrate Film

Decrease of pressure Boiling

10

100

0 2 4 6 8 10 12 14 16Temprature（degree）

Pres

sure （

kgf/c

m2 ）

with hydrate, dP/dt; ～0.1 (kgf/cm2/sec)with hydrate, dP/dt; 0.1～1.0 (kgf/cm2/sec)with hydrate, dP/dt; 1.0～ (kgf/cm2/sec)

without hydrate, dP/dt; 0.1～1.0 (kgf/cm2/sec)without hydrate, dP/dt; 1.0～ (kgf/cm2/sec)

50

40

30

20

60

70

8090

CO2(gas)CO2 (gas)+

hydrate

CO2(liq)CO2 (liquid)

+hydrate

Effect of decompression rate on boiling

Effect of hydrate film on boiling

Boiling starts as soon as pressure is lowered beyond the liquid-gas boundary in the case with hydrate.

Decompression rate

Time [sec]

Pres

sure

[kg

f/cm

2 ]

Small decompression rate(Same order of rising liquid CO2 droplet in ocean)

Large decompression rate

Liquid

Gas

Video Video (High speed camera)

Large decompression rate

Decompression rate (Small)Same order of rising liquid CO2 droplet in ocean

6

Liquid CO2 injection in CO2 saturated water

• Remarkable ruggedness was formed on the hydrate film

Temperature 281K

Pressure 39.2MPa(4000m depth)

Simulation of dissolution of liquid CO 2 droplet with hydrate film

( )oM k A C Ct ∞

∂ = − −∂

Hydrate film

Liquid CO 2

Surface concentration of hydrate

Dissolution of CO 2

with hydrate

20

30

40

50

60

70

80

90

5 10 15 20 25 30 35 40

T=13.0℃ (Without hydrate)T=8.0℃ (With hydrate)T=5.5℃ (With hydrate)T=3.0℃ (With hydrate)

C0 (

kg/m

3 )

P (MPa)

0.02

0.04

0.06

0.08

0.1

275 280 285 290

CO

2 co

ncce

ntra

tion

(-)

T (K )

C0 Surface concentration of hydrate

P = 30.4 MPaWith hydrate

Solubility (Aya et al., 1997)

Solubility (Dodds, 1956)

Liquid CO2

CO2 surface concentration of hydrate

Hydrate film

Large decomposition rate of hydrate (CO2-nH2O) to surface

Small mass transport rate of surface to water

Surface concentration of CO 2

= CO2solubility

深海底貯留Sequestration of CO2at sea floor

7

・58,400,000tonが全て溶解するのに240年・It takes 240years for dissolution of 58,400,000ton of CO2

Hydrate film

地下帯水層へのCO2 隔離Underground disposal of CO2

• 帯水層への圧入

• Injection of CO2 into aquifer

p owe r plan t

CO2 se para tion

in je ction site

aquife rs

CO2 pipe -line

van derMeeret a l . , GHGT-6

T

T

P

P

MRI

test cell

high pressureregulator

pump

t hermostat ic bath

water injection system

air blowerair heater

CO2

P

CO2 injection system

pre ssure cont rolcylinder (100ml ,re sis ting pre ssure20MPa)

帯水層に圧入された超臨界 CO2 の可視化

Visualization of super-critical CO2 in aquifer

inlet exit(a) (b) (c) (d)

450 glass beads in a pixel

MR signal

1H(a)(b)(c)(d)

17.4

CO2圧入前Before CO2 injection

8

inlet temperature 49.1℃

inlet pressure 11 MPa exit pressure 9.87MPaexit temperature 36.4℃

inlet exit(a) (b) (c) (d)

0 1CO2saturation

packedbed ofglass beads

spongefilter

0 1CO2 saturation

2 minutes 10 minutes 14 minutes 19 minutes

超臨界CO2 の浮力による移動Super-critical CO2 behavior due to buoyancy

0 0.2 0.4 0.6 0.8 10

0.2

0.4

0.6

0.8

1

1.2

CO2 Saturation φ

Rel

ativ

e Pe

rmea

bilit

y

CO 2H2O

φ=0.32

縮流部をすぎるCO2と水Numerical simulation of CO2 - water through

contraction

φ=0.47

Promotion ofenergy saving

Polymer electrolyte fuel cells (PEFCs)

vehicle applications local on- site power generation system

Sequestration of CO2

CO2 ocean / underground Sequestration

Understanding mass transport phenomenaincluding reactionin PEFC and CO2 ocean sequestration is necessary for implementation

Polymer Electrolyte Fuel Cell (PEFC)

Vehicles and local on- site power generation system

High efficiency & high power density

Water management is very important because…

-. Solid Polymer Electrolyte (SPE) membrane shows high proton conductivity only in the wet (hydrated) state.

H2 O2

SPE membrane

H+

SPE membranePorous electrode (Cathode)(Anode)

H2

O2,N2

④H2OH+

e-

Load

H2O① Accompanied

water

③ Production of water

② inflow water vapor

⑤ Diffusion

Water transport in PEFC

We need to know water behaviors inside PEFC.Especially,-. Water diffusion-. Water distribution under PEFC operation.

But not easy to measure by conventional method.

To control hydration of the SPE membrane properly...

How about NMR/MRI?

9

Magnetic Resonance Imaging (MRI) technique

・In- vivo and in- situ measurement・Visualization of molecules that include 1H inside the medium non- optically accessible,

e.g. porous media, polymer, complex flow system, etc...・3D Flow and temperature measurements・Chemical spices can be identified.・Self- diffusion coefficient can be measured.

Advantages and potential

Disadvantages

・nuclei limited (normally 1H, 13C, 19F…)・difficulties on gas phase・materials used in experimental apparatus ・temporal resolution

Exp. apps. (Diffusion measurement)

PEM

アクリル板

Magnet

Pre-amp.

Gradient power supplyNMR

console Work station

container

SPE membrane-. Nafion117-. Flemion

Acrylic plate

SPE membrane

Self-diffusion coefficient of water in the SPE membrane

JJ

JJJ

J

JJ

EE

EE

E

E

0

1

2

3

4

5

6

7

8

0 5 10 15 20 25

Dif

fusi

on c

oeff

icie

nt

cm2 /

s

water content n H2O/SO3H

J Nafion

E Flemion

×10-6

-. Self-diffusion coefficient decreases with decrease of water content in the membrane.-. In the most hydrated condition, self-diffusion coefficient is as 1/3 as that of pure water. -. Similar behaviors in both Nafion117(1100EW) and Flemion(1000EW)

H2, H2O

O2, H2O

A

e-

AH2, H2O

O2, H2O

Circuit: Open

Suddenly closed

Experimental condition for measurement of H2O

H2O & H+

H2O & H + & e- starts to move

How does the H2O in SPE membrane changes?

SPE membrane: Aciplex 340 µmSpatial resolution: 25 µm×780 µmSlice thickness: 10 mmAveraged image: 128Acquisition time: 40 min/image

Water distribution in the SPE membrane with various output current density

• MRI can probe water behaviors, especially water distribution, in the SPE membrane under the fuel cell operation.

• The SPE membrane gradually gets dried after the cell starts.

J

J

J

J

J

J

00.10.20.30.40.50.60.70.80.9

0 50 100 150 200 250

Vol

tage

V

Output current density mA/cm2

A

BC

DE

814[mV], 0[mA]

481[mV], 122[mA]

693[mV] ,47.0[mA]

395[mV] ,147[mA]

570[mV] ,92.0[mA]

23[mV] ,142[mA]

A B C

D E

SPE membrane

High H2O content

Low H2O content

化学反応・燃焼と環境問題(chemical reaction, combustion and environmental problems)

化学反応chemical reaction

エネルギーの抽出extraction of energy

物質の生成formation of substance

電気エネルギーelectric energy

熱エネルギー（燃焼反応）thermal energy(combustion)

10

H2

H2

O2

H2O

H2O

化学反応Chemical reaction(燃料電池）Fuel cell

電気エネルギーElectric energy

H2

H2

O2

H2O

H2O燃焼combustion

熱エネルギーThermal energy

サイクルcycle

電気エネルギー・仕事Electric energy ・work

2 2 21

H O H O2

+ →

熱エネルギーThermal energy

電気エネルギーElectric energy 2228.6kJ/molH

2241.8kJ/molH反応熱(heat of reaction)

rH∆ =

G∆ =

25℃，0.1013MPa（１気圧）で安定な物質Substance stable at 25℃，１atm

標準物質(reference substance)

H2, O2, N2, C, S

標準生成エンタルピー(standard enthalpy of formation)f H∆ o

標準物質からある物質を生成するときのエンタルピーEnthalpy to form a substance from reference substance

標準生

成エ

ンタ

ルピ

ー(kJ/m

ol)

0 C N2S O2

CO2

SO 2

H 2O

COCH 4

NO2C 2H 4

NO

C2H2

100

200

-200

-100

-300

-400

H2

stan

dard

ent

halp

y of

for

mat

ion

エン

タル

ピー

基準

生成物

反応物

反応熱

r eactfH

Hr

pr odfH

enth

alpy heat of

reaction

reactant

product

11

O2H2

H2O

2

oH O

241.826kJ/molfH = -

生成物

2

oO

0kJ/molfH∆

2

oH

0kJ/molfH∆

標準

生成

エン

タル

ピー

0

-200

-100

-300

H2 O2H2 O2

反応物

標準物質

=

=

reactantreference substance

product

stan

dard

ent

halp

y of

for

mat

ion

エン

タル

ピー

基準

生成物

反応物

反応熱

r eactfH

Hr

pr odfH

enth

alpy heat of

reaction

reactant

product

=0 kJ/molH2

= -241.8 kJ/molH2

= -241.8 kJ/molH2

25℃，0.1013MPa（１気圧）で安定な物質Substance stable at 25℃，１atm

標準物質(reference substance)

H2, O2, N2, C, S

標準生成ギブス自由エネルギー(standard Gibbs free energy of formation)

標準物質からある物質を生成するときのギブス自由エネルギーGibbs free energy to form a substance from reference substance

f G∆ o

標準

生成

自由

エネ

ルギ

ー(k

J/mol

)

0 C N2S O2

CO2

H2O

CO

CH4

O

NO

H

100

200

-200

-100

-300

-400

H2OH

stan

dard

Gib

bs f

ree

ener

gy o

f fo

rmat

ion

生成物H2O

反応物H2+1/202

仕事電気エネルギー

0

-100

-200

-300

reactant

product

WorkElectric energy = -228.6 kJ/molH2

H2

H2

O2

H2O

H2O燃焼combustion

熱エネルギー Thermal energy

サイクル cycle

電気エネルギー・仕事 Electric energy ・work

= -241.8 kJ/molH2 (2000 K)

= -161.5 kJ/molH2

燃料電池Fuel cell

電気エネルギー・仕事 Electric energy ・work = -228.6 kJ/molH2

12

水素からエネルギーを抽出する場合について，燃焼させるよりも燃料電池を用いる方が効率がいいことを示しているが，これは理論値を示しているだけで，実際のエネルギーの有効利用を考えるには，各種損失やエネルギーの輸送まで含めた全体のシステムとして評価することが重要となる．Energy extraction from H2 shows that efficiency using fuel cell is higher than combustion. It is noted that it just demonstrates a theoretical value. Efficient utilization of energy must evaluate whole system including loss, energy transportation.

Compare two CO2 mitigation strategies; CO2 sequestration and application of fuel cell to automobiles. How much would be the CO2 mitigation for these two in case of Japan. Consider the case for various parameters, for example, how many automobiles are changed from internal combustion engines to fuel cell.