COMBUSTION AND FUELS 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 organicLignite: 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 – lignitebiochemical phase
lignite – bituminous coal – anthraciteGeochemical phase
COMBUSTION AND FUELS
HISTORY OF COAL
Age (years)Type of coal
from 2 mln to nowPeat
before100 mln
before 70-2 mln
Brown coal
Lignite
300-200 mlnBituminous coal
COMBUSTION AND FUELS
COAL PETROGRAPHY
The goal of coal petrography:
� understand how coal was constituted
� implement of most productive use of coal
Petrography is a science about the rocks.
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.
Podział makroskopowy Podział mikroskopowy
Skały Litotypy MikrolitotypyGrupa
macerałówMacerały Submacerały
Odmiany
macerałówKryptomacerały
Węgiel
Witryn (węgiel
błyszczący)Witryt V
Witrynit VTelinit
Kolinit
Witrodetrynit
Telenit 1
Telenit 2
Telokolinit
Żelokolinit
Desmokolinit
Korpokolinit
Kordaitotelinit
Fungotelinit
Ksylotelinit
Lepidofitotelinit
Sigillariotelinit
Kryptotelinit
Kryptokorpo-
kolinitKlaryn (węgiel
półbłyszczący)
Klaryt V+E
Witrynetryt V+I
Trimaceryt V+I+E
Liptyt E
Egzynit (Liptynit)
E (L)
Sporynit
Kutynit
Rezynit
Alginit
Liptodetrynit
Tenuisporynit
Krassisporynit
Mikrosporynit
Makrosporynit
Pila–Alginit
Reinschia–Alginit
Duryn (węgiel
matowy)DurytI+E
Fuzyn (węgiel
włóknisty)
Inertyt I
Semifuzyt
Fuzyt
Sklerotyt
Łupek
palnyŁupek palny
Karbo–
mineryt
Karbargilit
Inertynit I
Mikrynit
Makrynit
Semifuzynit
Fuzynit
Sklerotynit
Inertodetrynit
Pirofuzynit
Degradofuzynit
Fungosklerotynit
Plektenchyminit
Korposklerotynit
Pseudo-
korposklerotynit
Karbankeryt
Karbosilicyt
Karbopiryt
Karbopolimineryt
Skała
płonnaSkała płonna Skała płonna
WęgielWęgiel sapropelowy
Kennel
Boghed
COMBUSTION AND FUELS
COAL CONSTITUENTS
Coal consists three ingredients:
- organic matter (combustible),
- mineral matter,
- moisture.
typical structures of coal rank of coal
lignite
coals for powergeneration
coking coal
anthracite
higher carbonization higher compression
lower oxygen content
EVOLUTION OF COAL STRUCTURE WITH THE RANK
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
Ultimate analysis: – (wt%):
- elements content: C, H, O, S, N, P, ...(wt%)
Proximate analysis – content (wt%) of:
- moisture M,
- ash A,
- volatile matter VM.
- caloric values: HCV and LCV.
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 the
temperature of 105-110 oC,
�Dry and ash free (daf lub waf).
�Raw (as burnt in boiler) (r).
COMBUSTION AND FUELS
Example of A and Qi in raw state (r), in dry state (d) and dry-ash-free state (daf) of lignite
262032333412.591945.756.0Max.
254542282710.389494.754.9Medium
25268222728.387563.753.9Min.
kJ/kgkJ/kg%kJ/kg% %
QdafiQd
iAdQ riArW rtValue
COMBUSTION AND FUELS
Calculations of results of analysis of coal (solid fuels)
Coefficient of conversion: Type of
conversion Raw
r
Analytical
a
Dry
d
Dry ash free
daf
From raw
state r 1 ar WW −−1
1
rW−1
1
rr AW −−1
1
From analytical
state a 1
1 ar WW +− 1 aW−1
1
aa AW −−1
1
From dry state d 1
1 rW−
11 aW−
1 dA−1
1
From dry ash free
state daf 1
1 rr AW −−
1
1 aa AW −−
1
1 dA− 1
COMBUSTION AND FUELS
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: 01-09
• Peat: 11-19
• Lignite: 21-29
• Bituminous coal: 31-39
• Anthracite: 41 and higher
• Graphite: 50
Coals for
power genera-
tion
Type of coal
Classifying measurements
Applications of coal
Volatile matter content
Vdaf
PN-81/G-045516
Coking ability
RIPN-81/G-4518
Dilato-metric indexPN-81/
G-04517
Blow up index
SIPN-81/
G-04515
Upper caloric valueQdaf
PN-81/G-04513
Name Mark % % kJ/kg
Flame coal
31.1 More than 28
Over or equal to
5
Without standar
d
Without standar
d
Over or equal 31000
Do wszystkich typów paleniskpyłowych; do czadnic
pulverised coal furnaces; gasgeneratrors
31.2Over 31000
Gaseous-flame coal
32.1
More than28
Over5 to 20
Without standard
Do wszystkich typów palenisk; do wytlewania i do czadnic
all types of coal furnaces;gas generatrors
32.2Over 20
to 40
Do palenisk rusztowych, komorowych i wszystkichtypów palenisk pyłowych; węgiel do wytlewania i do gazowni
grate furnaces, pulverisedcoal furnaces; gasgeneratrors
Gaseous coal
33More than28
Over 40 to 55
Do palenisk rusztowych i wszystkich typów paleniskpyłowych; do piecówprzemysłowych o szczególnychwymaganiach; do gazowni i do mieszanki do produkcji koksu w koksowniachgrate furnaces, pulverisedcoal furnaces, industrialkilns; gas generatrors;coke production
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: C and H,
- important: O, S, N and P
- trace content: the rest.
COMBUSTION AND FUELS
Thermal decomposition of coalCOAL PYROLYSIS
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.
Volatile matter
Char
Coal particle
Temperature
organic matter ash
mineral matter
wcoal in dry state
c + h + o + n + s + a + w = 1
coal in air-dry (analytical) state
coal in raw state
char volatile matter
fro
m d
eco
mp
osi
tion
of
min
era
l ma
tte
r
inh
eren
t m
ois
ture
in a
ir-d
ry s
tate
tran
sien
t m
ois
ture
(su
rfa
ce m
ois
ture
)
COAL COMPONENTS
COMBUSTION AND FUELS
ANALYSIS OF ORGANIC FUELS
Fuel C H O N + S VM content, %
WoodPeatLigniteHard coalAnthracite
5058708294
65,5553
4334,524123
12
0,80,8
trace
756550355
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 sand and
clay) (mineral matter deposited by wind and water or by percolation of water through the seams)
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 105-110 oC (dry state (d))).
Water of hydratation of mineral matter.
COMBUSTION AND FUELS
SOME ELEMENTS IN COAL
Carbon C: 50-93%
Oxygen O: 1-3%
Sulfur S: 1-5 (11)%in sulphites (FeS2)in sulphates (CaSO4, FeSO4)
Hydrogen H: 2-5%
COMBUSTION AND FUELS
Polish bituminous coal for heat and power production (type 31-33)
Coal mining region
LCVkJ/kg
Ashcontent
%
Sulphurcontent
%
Moisture%
JaworznickiMikołowskiDąbrowsko-siemianowskiKatowicko-chorzowskiRybnickiLubelski
18 40020 10021 800
23 500
20 10018 850
20−242020
20
20−2725
1.25−1.51.50.6
0.8
0.7−1.31.2
16−20128
5
99
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 miningregion
LCVkJ/kg
Ashcontent
%
Sulphurcontent
%
Moisture%
TuroszowskiKonińskiPątnowskiAdamowskiBełchatowski
8 4009 2009 2008 0008 800
12,2−205,8−6,3
10,69,810,6
0,600,25−0,35
0,780,250,60
42−5050−54
505050
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 Reserves, % Total reserves, %
GZWDZWLZW
88.211.10.7
43.756.10.3
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
RESERVES AND TOTAL RESERVES OF COAL
FuelWorldbln Mg
Polandbln Mg
Bituminouscoal
reserves
total reserves
630
7000–14000
30
130
Lignitereserves
total
reserves
250
880
12–13
30–40
Type of coal World109 Mg
Polandmln Mg
Bituminous (hard) 4.2 84 (2009)
Lignite 0.944 64
Yearly production of coal in Poland and in the world
10 mln Mg7 mln Mg
Import Export
Polish import/ export of hard coal in 2008
PRODUCTION OF COAL
COMBUSTION AND FUELS
Reserves and production of bituminous coal in Poland
Res
erve
s (
x 10
9t)
1989-2005
Pro
duct
ion
( x
106
t)
Year
Production/export Amount, mln Mg
ProductionImport
100.42.7
The use:- production of other fuels
- direct use- export
62.0
20.023.0
Production of lignite was approx.58.2 mln Mg in 2002 r. and it was used for electrical power production.
Bituminous coal
Lignite
Production and the use of coal in Poland