COMBUSTION AND FUELS - fluid.wme.pwr.wroc.pl

COMBUSTION AND FUELS

COAL


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


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.


ORIGIN OF COAL

• The origin of coal is organicLignite: cross section through xylite


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.


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


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


STRUCTURES OF COAL


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.


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

EXAMPLES OF

MACERALS


COAL CONSTITUENTS

Coal consists three ingredients:

- organic matter (combustible),

- mineral matter,

- moisture.


CHEMICAL STRUCTURE OF COAL (organic matter)

Benzene ring


COAL STRUCTURE

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


CLASSIFICATION OF COAL


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


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).


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.


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).


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


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


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%.


POLISH CLASSIFICATION OF COAL

• In Poland coals are divided on:

– groups (classes)

– types,

– sorts.


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.


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

Coal sorts sortgroup / name /symbol

grain sizeupper / lower


CHARACTERISTIC OF MAJOR COMPONENTS OF COAL


COAL COMPONENTS

Coal is combined with three components:

• Moisture (M)

• Mineral matter (A)

• Combustible (organic) matter

Moisture and mineral matter are ballast.


MAIN ELEMENTS IN COAL

Organic matter:

- basic: C and H,

- important: O, S, N and P

- trace content: the rest.


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


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


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.


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).


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.


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%


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


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%


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


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%


BITUMINOUS COAL-FIELDS IN POLAND

Coal basins:

- Upper Silesia,

- Lower Silesia

- lubelskie

Reserves: 30 bln Mg

Total reserves: 100 bln Mg


Reserves and total reserves of bituminous coal in Poland

Basin Reserves, % Total reserves, %

GZWDZWLZW

88.211.10.7

43.756.10.3


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

Deposits with coal mines

Other discovered deposits

LIGNITE COAL FIELDS IN POLAND


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


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


Bituminous coal price in USD/tonne

$ / t


Costs of heat and electricity generationin Poland

Cost of heat generationPLN per 1 GJ

Cost of electicity generationPLN per 1 MWhincluding CO2 capture

from lignite

fromhard coal

fromnatural gas

from lignite

fromhard coal

fromnatural gas

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COMBUSTION AND FUELS - fluid.wme.pwr.wroc.pl