Hydropyrolysis of a spanish lignite

Fuel Processing Technology, 15 (1987)

101-111

101

Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands

HYDROPYROLYSIS

OF A S P A N I S H

R. C Y P R E S I a n d

R. M O L I N E R 2

iUniversit~

Libre

Carbochimie. 2Consejo

50,

de B r u x e l l e s . Av.

Superior

Carboqu~mica.

LIGNITE

F.D.

de

Plaza

Service

Roosevelt.

1050

Investigaciones Paralso,

i.

de

Chimie

Generale

Bruxelles.

Cientlficas.

50004

et

Belgium.

Instituto

- Zaragoza.

de

Spain.

ABSTRACT Hydropyrolysis preparative sis

(Py).

water

fixed

The

yields

bed

reactor

external is l e s s

(Hypy)

as

from

in a H 2 a t m o s p h e r e .

in He a n d H 2 o c c u r an e x o t h e r m i c rank

coals

at t h e

peak.

These

is c o n t r o l l e d

composition, primary

of m o r e

with

radicals

the and

much more

The

by the

hydrogen

in

the

pyrolytar

incorporated

which

show that

initiation

in a

of

hydrogen

Hypy

steps

of

role

them to escape

of

rate

coincides

the

and

in the

devolatilization

temperature,

results

tar than

extraction

higher

coal

in the gas,

hydrogen

efficient

same

allowing

low rank

incorporated

the total

products~ char

yields

hydrogen

than

a result

of a S p a n i s h

rate

with

of l o w

thermal

de-

stabilizing

the

as v o l a t i l e

matter.

INTRODUCTION Spain's only used before low

for

from

chars

a i m of t h i s

Teruel,

from this

lignite

generation.

(2) w o u l d

residual The

coals

power

combustion

sulfur

nite

considerable

Spain~

area.

Hydropyrolysis

provide

for

feedstock

power

research which

reserves

(i)

are

(Hypy) for

so

of

industry

far

coals and

generation. is t o s t u d y

is

the

representative

Pai-6634 of

lig-

several

102

EXPERIMENTAL The Preparative

analyses

Hypy

is a iOO g gas the

final

min -I.

was

swept~

gas

on a p r e v i o u s l y

O.1

g at

TABLE

3MPa

out bed

and h e a t i n g

ULB

apparatus

reactor.

i00

decribed

are g i v e n

in the

and v a r i e d was

coal

between 1 h -I.

of

20

TGA

apparatus

rate

Heating K

(3)

rate min

and

(4),

in T a b l e

DTA

(5),

and

was

on

which

depends

-i

I

of

iO

K

carried

samples

of

i0 K m i n -I

I

Analyses

of the

Proximate

Pai-6634

Analyse

Volatile

Ultimate

matter

Ash Carbon

Higher

CaloriFic

Vitrinite

PRODUCT

coal.

:

Moisture

Fixed

fixed

flowrate

out

Pai-6634

carried

temperature

The

of the

Analyse

15.85

C

63.85

27.O1

H

4.50

"

17.24

N

0.57

"

39.89

S

(Total)

3.96

(dry)

S

(organic)

1.71

(dasf)

O

(by d i F F e r e n c e )

29.37

(dasf)

yields

From

Value

ReFlectance

19.350

(dasf)

kJ/kg

O.37

DISTRIBUTION

Temperature

eFFects

Figure the

preparative

Tar

yields

tar

yield

i (a)

experiments

are m u c h under

shows

higher

the at

3 MPa

under

H 2 is o b t a i n e d

gas,

at

tar and

H 2 than 798

K.

and w a t e r diFFerent under Water

He.

temperatures. The

yields

maximum increase

103 with

increasing

yields

are

temperature

similar

under

and

are

higher

in

H2 a n d

He,

increasing

H2 t h a n

in

linearly

He.

Gas

with

te E

perature. Figure tuents:

Under

constituents.

ce

humic

increase

constituent.

Pressure

The

CO

H2 a n d

only

in

dioxide are

and

very

Both

gas

consti-

methane

high

as

CO 2

and

the

most

are

the

a consequen-

methane

yields

methane

yields

is

increase

slowly

important

with

gas

temperature,

He p r e s s u r e .

2 shows

slightly

an

surface

low

inert

area

of

lignites tar

ry

reaction

rate

is

pressure

the

coal

is

of

that even

decrease

as

the

at

773

at

product

K

yields

pressure

the

which and

low

general

highly

char.

is

seconda

The

seconda

not

can

pressure.

observed

coals,

increases,

active

volatiles

external trend

chan-

favours

unreactive

subbituminous

pressure

the

to

gas

only

the

and

yields

He t h e

to

pyrolysis,

particle

bituminous

lignites

yielding

As a c o n s e q u e n c e , pyrolysis

Under

attributed

during

high

He.

and tar

changes.

of

molecules so

water

H2 a n d

atmosphere

of

from

gas,

sensitivity

reactions

escape

the of

with

ry

yields

different

temperature.

pressures

The ges

of

effects

different

vary

yields

carbon

H2 p r e s s u r e ,

Figure and

the

decarboxylation.

increasing

with

under

shows

T h e CO 2 y i e l d s

acid

Under

both

(b)

He a t m o s p h e r e ,

major of

1

for

in

the

which

tar

found

for

this

lignite. Under little with

variation

pressure

described in t a r

H2 with

from,

by H o w a r d

yield

atmosphere,

occurs

pressure.

1 to

3 MPa

et el. at

water Tar which

and

yields

1 MPa.

(6)

yields

increase

differs

for b i t u m i n o u s

gas

from

continously

the

coals where

exhibit

behaviour a

minimum

104 12

~20 ~18

"~10P-3

f Q

•

~4-

773

6~3

a~3

'~÷3 ' '

o

673

Temperature K

773

873

973

TemperQture R

Figure i. Hydropyrolysis and Pyrolysis of the Pal 6634 lignite. a) Overall yields. • Tar. Hp. ~ Tar. He; • Gas . Hp; 0 Gas. He; • Water. H9; a Water. He? b) Gas composition:• ~ Methane. H~; 0 Methane.-He; • CO 2. H^" m CO_. He; • CO. H_. 0 CO. de. L ' Z -I Z --1 Pressure: 3HPa. Heating Rage: I0 K min . Gas Flow. i00 lh ,

20

....

/

2~)

.

015

lb 1:5 2b Pr-essure (MPQ)

2~5

3~0

Figure 2. Hydropyrolysis and Pyrolysis of the Pal 6634 lignite. Pressure effect: • Gas. H2; <> Gas. He; • Tar. H_; Q Tar. He; • Wa~ te~. H ; A Water. He. Temperature 773 K; Heating Rate:lO K minGas Fl~w: i00 lh -I.

105

Carbon

and

liydro~en

Figure among of

the

me

and

and

carbon

trends

as

the

strong

increase

hydrocarbon

and

pyrolysis

the

tars

under

hydrogen

products.

produced

H 2 and

He

at

distribution The

percentage

different

are

very

temper~

similar,

contents

in t h e

tar

fractions

follow

yields.

In t h e

gas

fraction,

the

tar

yields in

carbon

the

with carbon

increasing and

temperatur

hydrogen

content

higher

removal

the

from

much

removal

the

sa-

strong

in-

e leads in

to

the

more

from

temperature,

char.

It

effective

is

the

more

interesting

than

helium

effective

a

CI-C 4

to for

remark

is

the

that

hy-

hydrogen

char.

HYDROGEN

~60~ CARBON

4ot

t

so

fraction. The

is

in

both

hydrogen

in m e t h a n e

carbon

the and

hydrogen

crease

drogen

shows

pressures

and

hydrogen

3

hydropyrolysis

carbon

tures

Distribution

e~3

~3

a~3

g~3

e~a

7~a

a~3

~

TemperatureK

Figure 3. Hydropyrolysis and Pyrolysis of the Pal Carbon and Hydrogen Distribution: • Char. H ; ~ Char He; • Tar. H ; O Tar. He; • C 2 C] " 2 I carbons. H • C - C. Hydrocarbons. He; , C O , H^" ' 4 --I X Z' Pressure: ~MPa; ~eating Rate: i0 K min ; Gas Flow:

6634

lignite.

- C. ; Hydro<>C~ .He; i00 ~h -~.

and

106 Hydrogen Consumption The h y d r o g e n c o n t e n t produced content

from

the

in the gas,

hydropyrolysis

in the parent coal.

is

In order

higher to

t i o n of h y d r o g e n c o n s u m p t i o n a m o n g the the model

in figure 4 is

assumed.

tar,

than

evaluate

H 2

which

atmosphere,

except

is used to make tar,

mosphere. external

for

hydrogen

hydropyrolysis

products,

it

is

same

hydrogen

gas and water

The rest of the n e c e s s a r y

the

char

distribu-

Briefly,

the

and

the

the h y d r o g e n from coal is d i s t r i b u t e d in the and

water

assumed way

staying

that

under in

char,

f r a c t i o n s under H 2

hydrogen

is

taken

He

at-

from

the

hydrogen. PYROLYSIS

~'TAR ~_..~GAS COAL. HYDROGEN~---'-~"PH20

Figure 4. H y p o t h e t i c a l

HYDROPYROLY~S

:q TAR_ - , :=,GA Sv,,,.'~----~ ~...vH204---->-EXTERNAL

Distribution

HYDROGEN

of h y d r o g e n from coal

in the

Hydropyrolysis.

Table at d i f f e r e n t

2 shows the d i s t r i b u t i o n

temperatures

hydrogen removed sumption

from char under H 2

is lower than

the tars~

water

and p r e s s u r e s .

the

and gases. is

external hydrogen

amount In

fact,

the of

of h y d r o g e n c o n s u m p t i o n As a c o n s e q u e n c e external

hydrogen the

sed from the coal which has not been t a k e n

Heteroatom

hydrogen

con-

imcorporated

in

consumption

of

actual

lower due to the e l e m e n t a l

of the

hydrogen

relea-

into account here.

distribution Figure

5

shows

the

and oxygen in the p y r o l y s i s

distribution

of

sulfur,

and the h y d r o p y r o l y s i s

nitrogen

productS as

a

107 2.

TABLE

Distribution Basis:

of

100 g of

the

Hydrogen

coal

charged

Tar

Gas

773 K

1.03

873 973

consumption

in

Hydropyrolysis.

(dry)

Water

Char

External Hydrogen

0.38

0.41

-0.50

1.32

0.74

1.01

0.44

-0.28

1.91

0.50

1.85

0.34

-o.61

2.08

0.1

0.19

0.12

0.03

-0.30

0.04

O.5

O.48

0.46

O.3O

-O.17

1.O7

3

1.O3

0.38

0.41

-0.50

1.32

Temperature

P=3MPa

Pressure T=773

MPa

K

OXYGEN

.e-..,,----o- ' ~ ' R ~

e

n

:

w

673

773

873

Temperature K

FiEure 5. H y d r o p y r o l y s i s and P y r o l y s i s o f the Pal 6634 lignite. Sulfur, N i t r o g e n and Oxygen Distribution. Char: • H 2. ~ He; Gas: I H . Q He; Tar: • H . 0 He; Water: 4~.H~. < > H e . 2 2 Pressure: 3MPa; H e a t i n E Rate lO K m i n - L ; Z G a s Flow: lO0 lh -I

973

108

function ted

by i n c r e a s i n g

ve t h a n the

of t e m p e r a t u r e .

Heliun

removed

ducts

HEAT

Heteroatom

the t e m p e r a t u r e .

for e l i m i n a t i o n

heteroatoms

appear

in t h e

is

promo-

is m u c h m o r e

gas

effecti

f r o m char.

fraction

of

Most the

of

pro-

BALANCE 6 shows

DTA of the

Under

He t h e r e

682 K w i t h

peaks

at 364 K (Peak

1173

K

3)

and

peaks

is

isothevmicity 1026

Under with

Hydrogen

of h e t e r o a t o m s

mospheres.

(Peak

from char

of h y d r o p y r o l y s i s .

Figure

to

removal

at

great

exothermic

(Peak

4)

with

is

K (Peak

H2 t h e r e

363

a drop

is

endothermal I) a n d

zone

522 K (Peak

predominant

with

an endothermal

1)

are

at

under

He a n d H 2 a ~ from 2).

peaks

298 From

at

893

and

524

observed K.

zone

K (Peak at

720

for

2).

Above

K (Peak

The endothermic

298

peak

3) at

642 and 523

5

"

IX_

:

i

'

-=I

::I -5.1

682

730

to

AT

-,

to

K

4).

K (Peak peaks

an

Pai-6634

t,~.

,.

,,

? "4

1

]/

"i°~

'J

Temperature K

Figure 6. Differential Thermal analyses • • H pressur_~ ; O H e pressure. Pressure: 3MPa; Heating Rate, TO K min .

642 K K two 1049 K

K is

109 generally The

peak

attributed a t 720

drogenation

K can

tile

tensities the

they

occur

is

more

and the

[,*(,(.vest, i u g

same

are

that

higiler

under

hydrogenation

3.

more

total

TABLE Heat

the

1049

t, l l a t

H 2

I|e a n d

than

forming

hy-

forming

under

the

exoLhermic but

He.

same

hydrogen

peaks

the

This

under

peak could

He a n d

pressure

inmean

ii 2 b u t

because

there

that

and

the

calculated

exthermic

heat

for

areas

the

are

balance

in

the

under

He

pressure

endothermal

peaks

shown

in

temperature and

and Ta-

range

strongly

H 2 pressure.

3

He

(Joule/g

2.5

H2

dry coal).

~

388.7

-41.8 -1283.3

668.8

isothermal

Pai-6634

under

Total

~

7

shows

He a n d

up to 698 K.

this

twice

the

devolatilization

cases.

Endo

Exo

-238.3

493.2

-242.4

-647.9

668.8

-2445.3

thermogravimetric

H 2 pressure

Above that

the

H 2 is a b o u t highest

~

Balance

250.8 -1776.5

Kinetics

Figure

both

-

methane

H2,

under

are

enthalpies

endothermic

under

balance

tical

K to

the

Peaks

Non

tar

reactions.

hydrogen.

is s l i g h t l y

exothermal

at

under

intensively

It s h o w s

studied

to

Lo n o t e

reaction

Tile r e a c t i o n

ble

peak

temperature

available

fox" t h e

attributed

endothermic

J'eaci,iotls.

1(, i s at

be

reactions

hydr¢)genation

occur

to the w a t e r - f o r m i n g

under

It c o n f i r m s

that

(3 M P a ) .

temperature, He.

The

rates

Both the

derivative

are

reached

the h y d r o p y r o l y s i s

analyses curves weight

of

are

iden-

loss

under

curves

show

at a b o u t

753

rate

the

that K

in

essentially

110 depends

oil t i l e

ture

the

of

tiation

ltypy

steps

ponds

with

which

indicates due

allowing

rate rate

thermal

is

of

temperature that

the

hydrogenation

them

to

and

it

determined

maximum

of

with by

the

the

radical

rate

higher

as

hydropyrolysis

maximum

of

na

the

heat

rate

release

from

devolatilization

reactions

escape

agrees

ini

decomposition~

temperature

the

to

whose

of

The

are

pyrolysis

rates

stabilizing

volatile

the

corresthe

DTA,

under

H2

radicals

and

matter.

100

90.

~,5

®

80.

~

~.4

70.

60.

o ==50.

<).3

0.2~

3O. 20. 10

0.1

3~3

5~3

7"~3

~73

'

~'73

Temperature K

Figure 7. Thermogravimetric Analyses. i. Helium pressure. 2 Hydr~ gen pressure. Pressure: 3MPa; Heating Rate: lO K min CONCLUSIONS Hydropyrolysis lorizate are red.

low

obtained

rank

coals

and

efficient

Hydrogen

favourable

due

comsumption to

highly

is

a very

because

interesting

high

yields

heteroatom is

low

exothermic

technology of

removal

and

the

tar from

energetic

hydrogenation

to

and char

va-

methane is

balance reactions.

achie is

iii REFERENCES

I.

Inventario

dios

de recursos

de la Energia.

de carbon

Ministerio

de

en Espafia.

Industria

Centro

y

de

Energia.

Estu-

Febrero

1979. 2.

R.

CyprUs.

Preliminary

power-plants. September

Fifth

Hydropyrolysis

International

i st - 5 th,

1980.

of

coal

Conference

Dfisseldorf.

to

on

be burned

Coal

Federal

in

Research.

Republic

of Ger

many. 3. R. Cyprbs hydrogen

pressure

4. M. Ghodsi thermal tion

and S.

of coals.

with two

a

d y i n g the g a s i f i c a t i o n

6.

D.B.

Rapid Fuel

Acta,

Anthony,

Y.B.

5_~5, 121.

pans

(1983)

D.

Planchon

of coal under

hydrogen

coal 60, of

direct

62

thermal

Howard,

1981,

for

differential

9_~4, (1985),

devolatilization 1976,

Acta,

Fuel,

of

The c o n s t r u c t i o n

symmetrical

C. B r a e k m a n - D a n h e u x , of

pyrolysis

rates.

- Tilte.

Thermochimica

"The c o n s t r u c t i o n

Thermochimica

Fixed-bed

at low h e a t i n g

and C. Newman

balance

5. R. Cyprbs,

Furfari.

under

768-778. an

iso-

hydrogena-

1-7. and

F.

analyser

Goosens. for

stu-

pressure".

359-365 H.C.

Hottel

and h y d r o g a s i f i c a t i o n

and

H.P.

Meismer.

of b i t u m i n o u s

coal.