Post on 18-Jun-2018
USE OF SECONDARY FUELS IN THE CEMENT MANUFACTURING:
A CASE STUDY
Dr. C. TSILIYANNIS1, I. FOTINOPOULOU1, Dr. M. GEORGIOPOULOU2 and Prof. G. LYBERATOS2
1ANION Environmental Ltd, Em. Lykoudi 26, 11141, Athens, Greece2National Technical University of Athens, Athens, Greece
4th International Conference on Sustainable Solid Waste ManagementCYPRUS 2016
Based on a stoichiometric balance of Alternative Fuels (AFs) combustion, the present study assesses the use of more than 20 distinct AFs, classified according to Eurocodes, in cement production
The operational efficiency and the emission rates in an actual dry process clinker plant are analyzed.
Alternative Fuels investigated in the Case Study (Decisions 2000/532/EC & 2014/955/EU)
CODE DESCRIPTION CODE (EUROPEAN LIST OF WASTE)
1 02 01 03 Plant tissue waste 2 02 01 04 waste plastics (except packaging)
3 03 01 05 sawdust, shavings, cuttings, wood, particle board and veneer other than those mentioned in 03 01 04
4 04 02 21 wastes from unprocessed textile fibres 5 04 02 22 wastes from processed textile fibres 6 12 01 05 plastics particles 7 13 05 07 * oily water from oil/water separators 8 13 05 08 * mixtures of wastes from grit chambers and oil/water separators 9 15 01 01 paper and cardboard packaging
10 15 01 02 plastic packaging 11 15 01 03 wooden packaging 12 16 01 03 end-of-life tyres 13 16 01 19 plastic 14 17 02 01 wood 15 19 08 05 sludges from treatment of urban waste water 16 19 12 01 paper and cardboard 17 19 12 04 plastic and rubber 18 19 12 07 wood other than that mentioned in 19 12 06 19 19 12 08 textiles
20 19 12 12 other wastes (including mixtures of materials) from mechanical treatment of wastes other than those mentioned in 19 12 11
21 19 12 11* other wastes (including mixtures of materials) from mechanical treatment of waste containing dangerous substances
22 19 02 03 / 19 02 04* premixed waste composed only of wastes marked as hazardous* or not
23 19 08 11* sludges containing dangerous substances from biological treatment of industrial waste water
24 19 08 12 sludges from biological treatment of industrial waste water other than those mentioned in 19 08 11
25 19 12 10 combustible waste (refuse derived fuel)
Cement plant investigated in Drepanon, Achaia, Greece
1.500.000 ton/year clinker, dry-process cement plant. 2 parallel kiln / precalciner / cyclone preheater lines. Current utilization of fossil fuels (70%Pet Coke and 30% Coal). Total Fuel Energy Demand: 4.600 TJ/year. Specific Energy Consumption (ε): 3.550 kJ/kg clinker.
Use of alternative fuels (AFs) for 30% thermal Pet Coke substitution is investigated in this work, leading to an energy mixture of Pet Coke 40%, Coal 30% and AF 30%.
Cement Plant Flow Diagram
Clinker Production
Air Pollution Control Systems
Cement Production/Packaging
Fuel Air Soil materials
Gypsum
Cement
Cleaned flue gas (off gas)
Flue gas
Clinker
Soil Mill
Cyclone Preheater, Precalciner, Rotary Kiln
Coal and Petcoke Mill
Rotary Kiln/ Calciner /Preheater and Soil Mill APCS
Fuel Mill APCS
Fuel Air Soil materials
Air
Air
Water Quen-cher
Flue gas flow
1-θ
θ
Compound operation Direct operation
Direct and compound operation diagram(mostly operated under compound mode)
Case study: Cement plant emission points and offgas flows (compound operation).
Main emission point is the kiln –soil mill APCS (2 stacks with a total of 577.000 Nm3/h offgas flowrate)
95.000 m3/h
Kiln/Soil Mill APCS
Kiln-soil mill offgasVksm=577.000 m3/h Mass fraction θ of kiln
fluegases
Fuel Mill APCS
Dusty air from Raw materials Homogenization silo
Soil Press APCS
20.000 m3/h
Homogen-ization silo APCS
35.000 m3/h
Clinker Cooler APCS
250.000 m3/h Dusty hot air from clinker cooler not used as combustion air
Mass fraction 1-θ of kiln fluegases
Mass fraction 1-θ of kiln fluegases
Schematic description of the method for assessing offgas emissions (compound)
K iln stoichiometry (Fuel Combustion) Ultimate as received
analysis of conventional and alternative fuels
Main kiln combustion fluegas flowrates: overall, CO2, O2 , N2 and H 2O (fraction θ of combustion fluegases)
Offgas flowrates(fraction θ of overall kiln f luegases + CO 2 lime + soil mill air + exhaust air draft)
Assume emitted concentrations at the standardized maximum limit
Actually emitted pollutant concentrations
actual emission rates (mg pollutant /sec) = actual releases to the environment
Soil mill air (fraction αsm of raw meal fluegases)
Exhaust air draft (fraction ψ of overall fluegas flowrate)
Clinker production Raw meal
Lime dissociation (fraction θ οf CO 2 lime)
Overall kiln fluegases’ f lowrates
Kiln Stoichiometry and Mass Balance
A. Fuel Combustion Stoichiometry
CxHyOzClwSvNu + (1+E) (x + φ + v -0,5 z) Ο2 + (1+E) 79/21 (x + φ + v -0,5 z)N2
x CO2 + 2φ H2O + (x + φ + v -0,5 z) E O2 + w ΗCl + v SO2 +
(0,5 u + (1+E) 79/21 (x + φ + v - 0,5 z)) N2 (1)
whereCxHyOzClwSvNu is the empirical formula of the fuel and
φ = 1/4 (y - w) if y > w (2)φ = 0 if y ≤ w (3)
The operation of the rotary kilns at high temperatures (>1.450 oC) is described by the reactions:
Kiln flue gas species’ flowrates under AF utilization (30% thermal petcoke substitution) without including the CO2 generated by lime dissociation
Kiln fluegases (combustion and lime dissociation)
0
100
200
300
400
500
600
700
800
Baseli
ne02
01 03
02 01
0403
01 05
04 02
2104
02 22
12 01
0513
05 07
*13
05 08
*15
01 01
15 01
0215
01 03
16 01
0316
01 19
17 02
0119
08 05
19 12
0119
12 04
19 12
0719
12 08
19 12
1219
12 11
*
19 02
03 / 1
9 02 0
4*19
08 11
*19
08 12
19 12
10
Fuels
SO2 x
4, H
Cl (t
n/ye
ar)
0
200 000
400 000
600 000
800 000
1 000 000
1 200 000
1 400 000
1 600 000
1 800 000
CO2 ,
H2O
, O2 ,
N2 (t
n/ye
ar)
SO2 HCl CO2 H2O O2 N2
B. Lime dissociation
CaCO3 CaO + CO2 (4)
mCO2,lime,0 = η MWCO2 (mclinker – fuel ash)0 (5)
VCO2,lime,ο = η 22.400 ( mclinker - fuel ash)0 (6)
Raw meal required = mCO2,lime (1+ η MWCO2 ) / η MWCO2 (7)
where
η =ζ /56*(1- MWCO2 ζ/56)-1 (8)
ζ= %w CaO in CaCO3 (9)
Kiln Stoichiometry and Mass Balance
C. Determination of offgas flow rates (main APCS, kiln-soil mill) From overall mass balances (AF- baseline):
Vk,sm = Vk,sm, 0 + Vk,sm, 0 {(1+ψ)θ Vfg MWfg - (1+ψ)θ Vfg, 0 MWfg,0 } /
{θ Vfg, 0 MWfg, 0 +θ VCO2,lime, 0 MWCO2 + υ αsm mCO2,lime,0 (1+ η MWCO2 ) / η MWCO2 + υ θ
ψ (mfg, 0 + mCO2,lime, 0 ) } (11)
where ψ = the mass fraction of induced air draft from main exhaust blower with respect to overall kiln flue gasesMW = molecular weightVfg = flue gas volumetric flow rate.
The actual pollutant emission rates are given by ri = xi,l/ SF (12) Where SF is the standardization factor,
Kiln Stoichiometry and Mass Balance
PP
TT
OHOSF s
ssmksmk ,2,2 ]%[100100
]%[211021
and xl denotes the standardized emission limit for any pollutant set by legislation.
Determination of standardization factor
Off gas water and oxygen concentrations are found in terms of fluegas, exhaust air draft and soil mill water and oxygen content
[H2O] = Vk,sm H2O =100 (VH2Ofg + Vpseudo air moisture + Vsoil mill air moisture ) / Vk,sm (14)
[O2] = Vk,sm O2 = 100 (V O2fg + Vpseudo air O2 + Vsoil mill O2) / Vk,sm (15)
Flue gas (Vfg) and offgas (Vksm) flowrates under AF utilization (30% thermal petcoke substitution)
Flue gas (Vfg) and offgas (Vk,sm) of conventional & secondary fuels in chimney
100 000
200 000
300 000
400 000
500 000
600 000
700 000
Baseli
ne02
01 03
02 01
0403
01 05
04 02
2104
02 22
12 01
0513
05 07
*13
05 08
*15
01 01
15 01
0215
01 03
16 01
0316
01 19
17 02
0119
08 05
19 12
0119
12 04
19 12
0719
12 08
19 12
1219
12 11
*
19 02
03 / 1
9 02
04*
19 08
11*
19 08
1219
12 10
Fuels
V fg,V
k,sm
(Νm
3 /h)
Vk,sm (Nm3/h)Vfg
Results
NOx emission rates based on maximum emission limit (800 mg/m3
under conventional fuel, 500 mg/m3, dry, 10%v O2 , under AF utilization) (AF: 30% thermal petcoke substitution)
ΝOx emissions based on maximum emission limit (baseline 800 mg/m3, AF 500 mg/m3, dry, 10% v.v. Ο2)
0
10 000
20 000
30 000
40 000
50 000
60 000
70 000
80 000
Baseli
ne02
01 03
02 01
0403
01 05
04 02
2104
02 22
12 01
0513
05 07
*13
05 08
*15
01 01
15 01
0215
01 03
16 01
0316
01 19
17 02
0119
08 05
19 12
0119
12 04
19 12
0719
12 08
19 12
1219
12 11
*
19 02
03 / 1
9 02 0
4*19
08 11
*19
08 12
19 12
10
Fuel
Act
ual N
Ox
offg
as e
mis
sion
rate
/ R
otar
y K
iln 1
& R
otar
y K
iln 2
(mg/
sec)
SO2 emission rates based on maximum emission limit (60 mg/m3 under conventional fuel, 50 mg/m3 under AF utilization,
dry, 10%v O2) (AF: 30% thermal petcoke substitution)
SO2 emissions based on maximum emission limit (baseline 60 mg/m3, AF 50 mg/m3, dry, 10% v.v. Ο2)
0
1 000
2 000
3 000
4 000
5 000
6 000
Baseli
ne02
01 03
02 01
0403
01 05
04 02
2104
02 22
12 01
0513
05 07
*13
05 08
*15
01 01
15 01
0215
01 03
16 01
0316
01 19
17 02
0119
08 05
19 12
0119
12 04
19 12
0719
12 08
19 12
1219
12 11
*
19 02
03 / 1
9 02 0
4*19
08 11
*19
08 12
19 12
10
Fuel
Act
ual S
O 2 o
ffgas
em
issi
on ra
te
/ Rot
ary
Kiln
1 &
Rot
ary
Kiln
2 (m
g/se
c)
TSP emission rates based on maximum emission limit (10 mg/m3 under conventional fuel, 30 mg/m3 under AF utilization, dry, 10%v O2, AF: 30% thermal petcoke substitution)
TSP emissions based on maximum emission limit (baseline 10 mg/m3, AF 30 mg/m3, dry, 10% v.v. Ο2)
0
500
1 000
1 500
2 000
2 500
3 000
3 500
Baselin
e02
01 03
02 01
0403
01 05
04 02
2104
02 22
12 01
0513
05 07
*13
05 08
*15
01 01
15 01
0215
01 03
16 01
0316
01 19
17 02
0119
08 05
19 12
0119
12 04
19 12
0719
12 08
19 12
1219
12 11
*
19 02
03 / 1
9 02 0
4*19
08 11
*19
08 12
19 12
10
Fuel
Act
ual T
SP o
ffgas
em
issi
on ra
te
/ Rot
ary
Kiln
1 &
Rot
ary
Kiln
2
(mg/
sec)
CO2 emission rates under AF utilization (30% thermal petcoke substitution)
CO2 emissions
0
50
100
150
200
250
Baseline
02 01 03
02 01 04
03 01 05
04 02 21
12 01 05
13 05 07
15 01 01
15 01 02
15 01 03
16 01 03
16 01 19
19 02 03
19 08 05
19 08 11
19 08 13 & 19 0
8 1419 12
0419 12
1119 12
12
CO
2 em
issi
ons
(m3 /tn
clin
ker)
Overall (with lime dissociation) and overall non biogenic CO2 emission rates under AF utilization (30% thermal petcoke substitution)
CO2 emissions
30 000
35 000
40 000
45 000
50 000
55 000
60 000
65 000
Baseline
02 01 0302 01 0403 01 0504 02 2104 02 2212 01 0513 05 07 *13 05 08 *
15 01 0115 01 0215 01 0316 01 0316 01 1917 02 0119 08 0519 12 0119 12 0419 12 0719 12 0819 12 1219 12 11*
19 02 03 / 19 02 0
4*19 08 11*
19 08 1219 12 10
Fuel
CO
2 offg
as e
mis
sion
rate
/ R
otar
y K
iln 1
& R
otar
y K
iln 2
(m3 /h
)
Total CO2 (m3/h) with lime dissociationNon Biogenic CO2 (m3/h) with lime dissociation