COAL
COMBUSTION AND FUELS
CARBON AND COAL
Carbon is a chemical element.
Coal is a solid fossil fuel
Carbon can exists in a certain allotropic forms including :
a) diamond
b) graphite
COMBUSTION AND FUELS
RESOURCES OF CARBON IN NATURE
a) freely in small amounts (graphite, diamond)
b) mainly connected in numerous chemical
compounds:
- carbonates (CaCO3, MgCO3 and in others),
- carbon dioxide in air (CO2),
- in organic compounds, fossil fuels:
natural gas, crude oil, coal and biomass.
COMBUSTION AND FUELS
ORIGIN OF COAL
• The origin of coal is organic
Lignite: cross section through xylite
COMBUSTION AND FUELS
NATURE OF COAL
•Coal is described as an organic sediment
•It is a combustible rock: biolite
•The major chemical elements in coal are:
carbon, hydrogen and oxygen.
COMBUSTION AND FUELS
COAL FORMATION
•The process of coal formation from organic
compounds includes two distinct phases:
biochemical and geochemical:
plant material – peat – lignite
biochemical phase
lignite – bituminous coal – anthracite
Geochemical phase
COMBUSTION AND FUELS
HISTORY OF COAL
Type of coal
Age (years)
Bituminous coal
300-200 mln
Brown coal
Lignite
Peat
before100 mln
before 70-2 mln
from 2 mln to now
COMBUSTION AND FUELS
STRUCTURES OF COAL
COMBUSTION AND FUELS
COAL PETROGRAPHY
Petrography is a science about the rocks.
The goal of coal petrography:
understand how coal was constituted
implement of most productive use of coal
COMBUSTION AND FUELS
PETROGRAPHIC STRUCTURES OF COAL
• Lithotypes (observed with the unaided eye):
vitrain, clarain, durain and fusain
(bright, halfbright, dull and black (gray-black) and porous and
friable)
• Microlithotypes (observable with the microscope)
• Macerals:
– vitrinite group,
– exinite group,
– inertinite group.
COMBUSTION AND FUELS
Podział makroskopowy
Skały
Podział mikroskopowy
Litotypy
Mikrolitotypy
Witryn (węgiel
błyszczący)
Witryt V
Klaryt V+E
Klaryn (węgiel
półbłyszczący)
Grupa
macerałów
Witrynit V
Witrynetryt V+I
Macerały
Submacerały
Odmiany
macerałów
Kryptomacerały
Telinit
Kolinit
Witrodetrynit
Telenit 1
Telenit 2
Telokolinit
Żelokolinit
Desmokolinit
Korpokolinit
Kordaitotelinit
Fungotelinit
Ksylotelinit
Lepidofitotelinit
Sigillariotelinit
Kryptotelinit
Kryptokorpokolinit
Trimaceryt V+I+E
Węgiel
Liptyt E
Duryn (węgiel
matowy)
Semifuzyt
Fuzyn (węgiel
włóknisty)
Egzynit (Liptynit)
E (L)
Sporynit
Kutynit
Rezynit
Alginit
Liptodetrynit
Inertynit I
Mikrynit
Makrynit
Semifuzynit
Fuzynit
Sklerotynit
Inertodetrynit
DurytI+E
Inertyt I
Fuzyt
Tenuisporynit
Krassisporynit
Mikrosporynit
Makrosporynit
Pila–Alginit
Reinschia–Alginit
Sklerotyt
Karbargilit
Karbankeryt
Łupek
palny
Łupek palny
Karbo–
mineryt
Karbosilicyt
Karbopiryt
Karbopolimineryt
Skała
płonna
Węgiel
Skała płonna
Skała płonna
Kennel
Węgiel sapropelowy
Boghed
Pirofuzynit
Degradofuzynit
Fungosklerotynit
Plektenchyminit
Korposklerotynit
Pseudokorposklerotynit
EXAMPLES
OF
MACERALS
COAL CONSTITUENTS
Coal consists three ingredients:
- organic matter (combustible),
- mineral matter,
- moisture.
COMBUSTION AND FUELS
CHEMICAL STRUCTURE OF COAL (organic matter)
Benzene
ring
COMBUSTION AND FUELS
COAL STRUCTURE
COMBUSTION AND FUELS
EVOLUTION OF COAL STRUCTURE
WITH THE RANK
typical structures of coal
rank of coal
lignite
higher carbonization
higher compression
lower oxygen content
coals for power
generation
coking coal
anthracite
CLASSIFICATION OF COAL
COMBUSTION AND FUELS
REASONS FOR CLASSIFICATION OF COAL
•variable characteristics of coal (complex material)
•different boiler furnaces in use,
•applications in chemical technology and metallurgy,
•extended trade of coal
COMBUSTION AND FUELS
STANDARDS USED IN COAL CLASSIFICATION
Origin and parameters of coal: (Polish Standards PN)
–
upper caloric value UCV ( in Polish Qs: PN-81/G-04513 or
PN-ISO 1928:2002),
–
blow up index (PN-81/G-04515),
–
volatile matter content VM (PN-G-04516:1998),
–
dilatometric index (PN-81/G-04517),
–
coking index (PN-81/G-04518).
COMBUSTION AND FUELS
ANALYSIS OF COAL
Proximate analysis – content (wt%) of:
- moisture M,
- ash A,
- volatile matter VM.
- caloric values: HCV and LCV.
Ultimate analysis: – (wt%):
- elements content: C, H, O, S, N, P, ...(wt%)
COMBUSTION AND FUELS
STATE OF SOLID FUELS
Analytical of air-dry (a), when moisture in coal is
in equilibrium with moisture of ambient air,
Dry (d lub wf), after 2-3 hours of drying at
temperature of 105-110 oC,
Dry and ash free (daf lub waf).
Raw (as burnt in boiler) (r).
COMBUSTION AND FUELS
the
Example of A and Qi in raw state (r), in dry
state (d) and dry-ash-free state (daf) of lignite
W rt
Ar
Q ri
Ad
Qdi
Qdafi
%
%
kJ/kg
%
kJ/kg
kJ/kg
Min.
53.9
3.7
8756
8.3
22272
25268
Medium
54.9
4.7
8949
10.3
22827
25454
Max.
56.0
5.7
9194
12.5
23334
26203
Value
COMBUSTION AND FUELS
Calculations of results of analysis of coal (solid fuels)
Type of
conversion
From raw
state r
From analytical
state a
From dry state d
From dry ash free
state daf
Coefficient of conversion:
Raw
r
1
1− W r + W a
1
1 −W r
1
1 − W r − Ar
1
Analytical
a
Dry
d
Dry ash free
daf
1
1
1−W r
1
1− W a
1
1 −W r − W a
1
1 −W a
1
1 − W a − Aa
1
1
1 − Ad
1
COMBUSTION AND FUELS
1 − W r − Ar
1
1 −W a − Aa
1
1 − Ad
1
COAL CLASSIFICATION ACCORDING TO ORIGIN
AND COAL RANK
Coal class
Content of C
Peat:
52-60%
Lignite:
58-77%
Bituminous coal: 76-93%
Anthracite:
91-93%.
COMBUSTION AND FUELS
POLISH CLASSIFICATION OF COAL
• In Poland coals are divided on:
– groups (classes)
– types,
– sorts.
COMBUSTION AND FUELS
GROUPS (CLASSES)
•Group is described by the two-digit number:
- first digit determines the group
according to the coal rank,
- the second digit determines the
position in the group.
COMBUSTION AND FUELS
COAL GROUPS (CLASSES)
•
•
•
•
•
•
Wood:
Peat:
Lignite:
Bituminous coal:
Anthracite:
Graphite:
01-09
11-19
21-29
31-39
41 and higher
50
COMBUSTION AND FUELS
Coals
for
power
generation
Classifying measurements
Type of coal
Volatile
matter
content
Vdaf
PN-81/
G-045516
Coking
ability
RI
Dilatometric
index
PN-81/
G-04517
PN-81/
G-4518
Name
Mark
31.1
Flame
coal
%
More
than
28
Blow up
index
SI
PN-81/
G-04515
%
Over or
equal
31000
Over or
equal to
5
More
than
28
Over 20
to 40
32.2
Gaseous
coal
33
PN-81/
G-04513
Over
31000
More
than
28
Over 40
to 55
Do wszystkich typów palenisk
pyłowych; do czadnic
pulverised coal furnaces; gas
generatrors
Do wszystkich typów palenisk;
do wytlewania i do czadnic
Over
5 to 20
32.1
Applications of coal
kJ/kg
31.2
Gaseous
-flame
coal
Upper
caloric
value
Qdaf
Without
standar
d
all types of coal furnaces;
gas generatrors
Without
standar
d
Do palenisk rusztowych,
komorowych i wszystkich
typów palenisk pyłowych;
węgiel do wytlewania i do
gazowni
Without
standard
grate furnaces, pulverised
coal furnaces; gasgeneratrors
Do palenisk rusztowych i
wszystkich typów palenisk
pyłowych; do pieców
przemysłowych o szczególnych
wymaganiach; do gazowni i do
mieszanki do produkcji koksu w
koksowniach
grate furnaces, pulverised
coal furnaces, industrial
kilns; gas generatrors;
coke production
Coal sorts
sort
group / name /symbol
grain size
upper / lower
CHARACTERISTIC OF MAJOR
COMPONENTS OF COAL
COMBUSTION AND FUELS
COAL COMPONENTS
Coal is combined with three components:
• Moisture (M)
• Mineral matter (A)
• Combustible (organic) matter
Moisture and mineral matter are ballast.
COMBUSTION AND FUELS
MAIN ELEMENTS IN COAL
Organic matter:
- basic:
- important:
- trace content:
C and H,
O, S, N and P
the rest.
COMBUSTION AND FUELS
Thermal decomposition of coal
COAL PYROLYSIS
Coal particle
Volatile matter
Char
Temperature
Coal pyrolysis is thermal decomposition of coal at the
temperature of 300-600 °C, depending on the coal type.
Results of pyrolysis:
- evaluation of volatile matter
- remaining
char.
COMBUSTION
AND FUELS
COAL COMPONENTS
mineral matter
coal in dry state
c+h+o+n+s+a+w=1
coal in air-dry (analytical) state
coal in raw state
w
transient moisture
(surface moisture)
ash
inherent moisture
in air-dry state
organic matter
volatile matter
from decomposition
of mineral matter
char
ANALYSIS OF ORGANIC FUELS
Fuel
Wood
Peat
Lignite
Hard coal
Anthracite
C
H
O
N+S
VM content, %
50
58
70
82
94
6
5,5
5
5
3
43
34,5
24
12
3
1
2
0,8
0,8
trace
75
65
50
35
5
COMBUSTION AND FUELS
INORGANIC MATTER IN COAL (2-60%)
Inorganic components in coal are classified:
- primary vegetable ash (inner m.m. – inherent plant matter
that formed coal)
- secondary minerals (outer m.m.: rocks and
clay) (mineral matter deposited by wind and water or by
water through the seams)
sand
and
percolation of
Inorganic matter of the primary type is dispersed in coal – impossible
to remove by the mechanical methods.
Inorganic matter of the secondary type usually consists of minerals
present in surrounding of a coal deposit.
COMBUSTION AND FUELS
SECONDARY INORGANIC MATTER
Main constituents (mainly minerals) of the
secondary inorganic matter:
- quartz,
- clay minerals (kaolinite, illite, ....)
- oxides (hematite)
- carbonates (dolomite, calcite,siderite, ...)
- sulphides (pirite, marcasite, zink suphide, ...)
- phosphates (apatite)
- others (chlorides, sulphates, nitrates, heavy metals).
COMBUSTION AND FUELS
MOISTURE IN COAL (5-60%)
Total moisture includes:
- air-dry loss moisture (transient) (loss of weight resulted of
partial drying of coal) (not linked to organic matter, can be removed by drying
at room temperature – air-dry state or analytical (a)),
- inherent moisture
(is connected with the substance of coal, and
can be removed from coal by heating it at the temperature in the range of 105110 oC (dry state (d))).
Water of hydratation of mineral matter.
COMBUSTION AND FUELS
SOME ELEMENTS IN COAL
Carbon C: 50-93%
Hydrogen H: 2-5%
Oxygen O: 1-3%
Sulfur S: 1-5 (11)%
in sulphites (FeS2)
in sulphates (CaSO4, FeSO4)
COMBUSTION AND FUELS
Polish bituminous coal for heat and power
production (type 31-33)
Coal mining
region
Jaworznicki
Mikołowski
Dąbrowskosiemianowski
Katowickochorzowski
Rybnicki
Lubelski
LCV
kJ/kg
Ash
content
%
Sulphur
content
%
Moisture
%
18 400
20 100
21 800
20−24
20
20
1.25−1.5
1.5
0.6
16−20
12
8
23 500
20
0.8
5
20 100
18 850
20−27
25
0.7−1.3
1.2
9
9
COMBUSTION AND FUELS
CHARACTERISTICS OF POLISH BITUMINOUS
COALS TYPE 31-33
LCV (Wu) =
18-25 MJ/kg
A=
7-25%
S=
1.2%
N=
0.6-2.8%
COMBUSTION AND FUELS
Polish lignites
Coal mining
region
LCV
kJ/kg
Ash
content
%
Sulphur
content
%
Moisture
%
Turoszowski
Koniński
Pątnowski
Adamowski
Bełchatowski
8 400
9 200
9 200
8 000
8 800
12,2−20
5,8−6,3
10,6
9,8
10,6
0,60
0,25−0,35
0,78
0,25
0,60
42−50
50−54
50
50
50
COMBUSTION AND FUELS
CHARACTERISTICS OF POLISH LIGNITES
LCV (Wu) =
5.6-11.7 (aver.8.5) MJ/kg
A=
4-25 (aver.12.0)%
S=
0.2-1.7 (aver. 0.7)%
N=
0.6-2.0%
COMBUSTION AND FUELS
BITUMINOUS COAL-FIELDS IN POLAND
Coal basins:
- Upper Silesia,
- Lower Silesia
- lubelskie
Reserves:
30 bln Mg
Total reserves:
100 bln Mg
COMBUSTION AND FUELS
Reserves and total reserves of bituminous coal
in Poland
Basin
GZW
DZW
LZW
Reserves, %
Total reserves, %
88.2
11.1
0.7
43.7
56.1
0.3
COMBUSTION AND FUELS
LIGNITE COAL-FIELDS IN POLAND
Coal basins:
-
adamowsko-konińskie
bełchatowskie (Szczerców)
turoszowskie
sieniawskie.
Total reserves:
40 bln Mg
Reserves:
13-14 bln Mg
Operational reserves:
3.5 bln Mg
COMBUSTION AND FUELS
LIGNITE COAL FIELDS IN POLAND
Deposits with coal mines
Other discovered deposits
RESERVES AND TOTAL RESERVES OF COAL
World
bln Mg
Poland
bln Mg
reserves
630
30
total
reserves
7000–14000
130
reserves
250
12–13
total
reserves
880
30–40
Fuel
Bituminous
coal
Lignite
COMBUSTION AND FUELS
PRODUCTION OF COAL
Yearly production of coal in Poland and in the world
Type of coal
World
109 Mg
Poland
mln Mg
Bituminous (hard)
4.2
84 (2009)
Lignite
0.944
64
Polish import/ export of hard coal in 2008
Export
7 mln Mg
Import
10 mln Mg
Reserves and production of bituminous coal
in Poland
Reserves ( x 109 t)
Production ( x 106 t)
1989-2005
COMBUSTION AND FUELS
Year
Production and the use of coal in Poland
Bituminous coal
Production/export
Amount, mln Mg
Production
Import
100.4
2.7
The use:
- production of other fuels
62.0
- direct use
- export
20.0
23.0
Lignite
Production of lignite was approx.58.2 mln Mg in 2002 r. and it was used
for electrical power production.
Bituminous coal price in USD/tonne
$/t
COMBUSTION AND FUELS
Costs of heat and electricity generation
in Poland
Cost of heat generation
PLN per 1 GJ
from
lignite
from
from
hard coal
natural gas
COMBUSTION
Cost of electicity generation
PLN per 1 MWh
including CO2 capture
from
from
ANDlignite
FUELS hard coal
from
natural gas