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transcript
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I Nyoman Suprapta Winaya
Jakarta 24-25 Agustus 2016
“Combustion in Circulating Fluidized Beds”
Workshop Peningkatan kehandalan dan efisiensi boiler PLTU CFB
Mechanical Engineering Department -Udayana University, Bali-Indonesia
BIOGRAFI SINGKAT� I Nyoman Suprapta Winaya is a professor in the Udayana
University, Bali, Indonesia. He currently serves as Head of Doctoral Study Program in Engineering Science. Winaya received Bachelor”s degree from Udayana University, his Master from Dalhousie University of Canada and his Ph.D from Niigata University of Japan. His main research is in biomass using Fluidized Bed Combustion and Gasification system.
� Dr. Winaya was pointed as a Professor on 2013 by Indonesia’s Ministry of Educational and Cultural in the field of energy conversion system at Udayana University. Presently, he leads the Renewable Energy Research Laboratory especially in the field of gasification and biogas. He has approved some essential innovations of high volatile matter fuels especially using porous solids as a bed material. A new method has been developed to evaluate horizontal dispersion of loaded solids at high bed temperatures that resemble those of commercial operations. As the first step to scaling-up of the fluidized bed (FB) system using carbon loaded solids prepared by capacitant effect the developed model is considered to be applicable to large scale FBs if the solid dispersion coefficient can be predicted. Prof. Winaya’s passion is to transfer research results into industrial practice having commitment to spread an advanced knowledge into the globe.
� Prof. Winaya is a senate member of Udayana University, a member of Indonesian’s Association of Mechanical Engineering, a member of Indonesia’s Association of Fuel Expert, a member of Indonesian’s Association of Engineer, a member of American’s Society of Mechanical Engineering, a member of Japanese’s Society of Chemical Engineering.
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Paten Fluidized Bed Pertama
“Manufacturing Fuel Gas”Fritz Winkler, Luwigshafen-am-RhineApplied: 1923Granted: 1928Assigned to I.G. Farbenidustrie Aktiengesellschaft
Fritz Winkler, pada tanggal 16 Desember 1921 di Jerman memperkenalkan suatu aliran gas hasil pembakaran yang dihembuskan di bawah sebuah wadah yang terdiri dari partikel – partikel batu arang. Kejadian ini menandai dimulainya hal yang sangat penting di dalam teknologi moderen. Winkler melihat partikel – partikel diangkat oleh tarikan gas, dan masa partikel dilihat seperti cairan yang mendidih.
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BOILER BFB-CFBSEJARAH KONVERSI
(Cat Cracker , petroleum )Lewis&Gilliland
*all solid fuelsCFB
USSR
Winkler gasifier BFB, Lignite, biofuel , ,*
19901950 20101920 1960
YEAR1980 20001930 1940 1970
BFB all solid fuels BFB biomass&wastes
69th IEA-FBC Technical Meeting, Aix-en-Provence,
September 2014
“Process of Producing Chemical Reactions”William W. Odell, Pittsburgh*Applied: 1926 (Original)**Granted: 1934Assigned to Standard Oil Development Company
*Odell was with the US Bureau of Mines**Originally Rejected Due to Winkler Filing, Application Refiled with Legal Assistance of Standard Oil
Paten Fluidized Bed Pertama
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SOVIET DEVELOPMENT at Moscow Energy Institute 1945-From HA Cemenenko, LH Cidelkovski, ”Particularities and experiences from the application of fluidized bed”, Teploenergetika No 3, 1954
To burn fine residual particles of low-reactive fuels.No cooling tubes in these figures!
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CHINESE DEVELOPMENT
Starting at Tsinghua University1969 with a 14 t/h boiler.
1980 there were over 2000FBC boilers in China
The figure shows a 130 t/hpower boiler from 1980
Zhang XuYi Proc 6th Int. Cong. On FBC US DoE, 1980.
EUROPEAN- NORTH AMERICAN DEVELOPMENTOF BFB 1970-1985
One of the last boilers inthis period: GeorgetownFBC 50 t/h boiler, 1980(FOSTER WHEELER)
REMARKS TERHADAP BFBBFB was not further used for coal combustion from the 1980sbecause of
1.
2.
3.
erosion on in-bed heat transfer tubes
unfavourable
unfavourable
sulphur capture and combustion efficiency.
scale-up properties
Figure from B. Broadfield, P.F. Lipari, R.S. Slone,Engineering studies of atmospheric FBC electric power
plants in the USA, VDI Berichte Nr 322, 1978.
CFB: THE FIRST SUGGESTION
The advantage of high velocity fluidization for chemicalreactions was observed by Lewis and Gilliland whoissued their patent 1940-50.
Lewis 1941-44 was the first topropose a CFB reactor “Reactionbetween solids and gases”
Lewis, W.K., (Standard Oil Dev.Co), “Reaction between solidsand gases”, US Patent 2,343,780, (Patented March, 1944,application August 1941).
CFB: THE FIRST SUGGESTION
The advantage of high velocity fluidization for chemicalreactions was observed by Lewis and Gilliland whoissued their patent 1940-50.
Lewis 1941-44 was the first topropose a CFB reactor “Reactionbetween solids and gases”
Lewis, W.K., (Standard Oil Dev.Co), “Reaction between solidsand gases”, US Patent 2,343,780, (Patented March, 1944,application August 1941).
FIRST COMBUSTION CFB
Stahl, Becuwe 1972-74Rhone Progil, France:Procedure forcombustion of industrialor household wastes
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A FAST AND SLOW BED BOILER, J. Yerushalmi, S.Erlich, EPRI,(March) 1977-78, US4103646
PROCESS FOR BURNING CARBONACEOUS MATERIALSCollin, Flink, Reh, Metallgesellschaft, (May) 1977-79,
US 4111158, US 4165717
••
Primary-secondary airSuspension densityabove secondary air 10-40 kg/m3.Gas velocity 5-15 m/sContinous solids densitygradient from thebottom of the fluidizedbedto the top of thereactor.Particle size 30-250 μm
••
•
THE ”SQUARE” CYCLONE: Centrifugal separator, THyppänen and R Kuivalainen, A. Ahlström Co. Finland
US 5281398, 1992-94
THE ORIGINAL LURGI CF B COMBUSTOR
Proposed 1976 forcombustion of oilshale in Swedenand South Africa.
L.Plass, G Daradimos, H Beisswenger, Deveopmentof the circulating athmospheric fluidized bed to anenvironment –conservong combustiontechnology, VGB Kraftwerkstechnologie 67(5),399-405 (1987).
THE CFB PROCESS ACCORDING<1995
I. Abdulally et al., The 5th Int. Power Generation Exhibition & Conf., Orlando Fl,1992.
TO FOSTER WHEELER
“The Foster Wheeler process is characterized by the presence of a pronounced bedin the bottom few feet of the furnace and a relatively solids-lean freeboard above it.
An alternative process, i.e., fast fluidized or highly expanded bed, is characterizedby having the solids spread over a substantial height of the furnace with the absenceof a pronounced bed at the bottom of the furnace …..”
CFB MANUFACTURERS AND THEIR RELATIONS
-
USt-ish coal, Renfrew (Babcock)Bri -
Metallgesellschaft ( Lurgi )
1989
Pu1995
1996 License toDongfang 1995
-
Technology transfer 2003
EtcValmet
2000 Alstom
Dongfang Harbin Shanghai
Metso
1987, 1993 (Lurgi license)ABB (1989) Combustion
Engineering
Kvaerner2003 Envirotherm
Generator
Götaverken
1996/97 Lurgi Lentjes(1993) Babcock, EVT,2007 AE&E Lentjes2011 Doosan Lentjes
TampellaAhlström 1981 CFB Ahlstrom-Pyropower
FosterWheelerBFB 1978-1990 GeorgetownCFB 1988-1995
Pu rchase
BHEL
-DorrOliver
China 1965-
Lurgi patent license
Lurgi patent license
Metallgesellschaft ( Lurgi1970 s first CFB patentsDuisburg 1983Keeler
UK 1970
Rivesville 19-76
USSR 1940- 60CFB Catcracker: Lewis Gilliland 1950
Petroleum &
Chemical industry
Winkler gasifier 1922 65
69th IEA-FBC Technical Meeting, Aix-en-Provence,
September 2014
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The designs are approaching each other. Thereremains some individual features such as seen below:
Bottom parts with external heat exchangers
Valmet(previouslyMetso)
Alstom Foster Wheeler
RECENT INTEREST
• Scale up
• Oxy-fuel, high oxygen concentration
• Other CO2looping
capture methods: Calcium looping, Chemical
SCALE-UP OF A CFB BOILER FROM 300 TO 600 MWeDimensions in m
16
8
5040
30 30
600 MW300 MW
AN OXY-FUEL CFB BOILER @ 60% O2
8 7
300 MW CFBAir vs oxy (60%)Dimensions in m
40 50
30 14
HISTORI PERKEMBANGAN PALING AKHIR
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LECKNER 2016
STATUS CIRCULATING FLUDIZED BED (CFB)
• Public Utility Regulatory Policy Act (1978)-Independent Power Producers– Qualifying Facility Status for Fluidized Bed-
Friendly Fuels• CFB Boiler Installed Capacities grow to 300
MW (Sub-Critical), 460 MW (Supercritical) at Lagiza-Katowice area of southern Poland
• The bigest capacity today: 600-MW supercritical CFB (SC CFB) at the Baima power plant China
• Fuels:– Coal– Coal Waste– Pet Coke– Biomass– MSW
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1) 2)
cyclone
secondary air
bedfuel
primary air
DUA GENERASI CFB:1. Cyclone separator 2. Inner separator
TIPE DESAIN CIRCULATING FLUDIZED BED (CFB)
KAPASITAS UNIT (MWe)600
SECONDGENERATION DESIGN
550
500Lagisza
450
400
350 FIRST GENERATIONDESIGN JEA300
Turow 5250 Turow 1
200
150 NPSima
100
50 KokkolaKuhmo
Pilot plantThai Kraft
01970 1975 1980 1985 1990 1995 2000 2005….... 2014
TAHUN AWAL OPERASI
Nov a ScotiaVaskiluodon Vo
Kajaani
Tri-StateLeykam
Pilot plant Pihlav a Kauttua
TREND PERKEMBANGAN CFB
Baima
INTERNATIONAL CFB CONFERENCE• CFB-1, Halifax, Canada, 1985• CFB-2, Compiegne, France, 1988• CFB-3, Nagoya, Japan, 1990• CFB-4, Hidden Valley, USA, 1993• CFB-5, Beijing, China, 1996• CFB-6, Würzburg, Germany, 1999• CFB-7, Niagara Falls, Canada, 2002• CFB-8, Hangzhou, China, 2005• CFB-9, Hamburg, Germany, 2008• CFB-10, Sunriver, USA, 2011• CFB-11, Beijing, China, 2014• CFB-12, Krakow, Poland, 2016..........September 30...
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mm
Boiler Temperature Fuel Fuel sizing Ash/slaging
PF High:1100-1400 oC
Hard coal 31-33Lignite < 0.3
mm
Melted/yes
CFB Low:800-900 oC
Hard coal, lignite, biomass, wastes
3-30
Not melted/no
PERBANDINGAN BOILER PULVERIZED FUEL (PF) DAN CIRCULATING FLUIDIZED BED (CFB)
COMBUST ON AND FUELS
qA, MW/m
qv, MW/m
Type of boilerParameter CFB BFB PC
Surface thermal load:
2 1.8-2.5 1.2-1.5 3.0-5.5
Volume thermal load
3 0.2-0.4I
0.1-0.2 0.08-0.2
PERBANDINGAN BOILER PULVERIZED FUEL (PF) DAN CIRCULATING FLUIDIZED BED (CFB)
Compound PF CFB
CaO SiO2
SO3
Al2O3Fe2O3MgONa2OLOI
2-1240-550.5-613-304-171.8-8
0.3-0.70.7-15
2526
10.89.615.40.80.42-12
PERBANDINGAN ABU HSIL PEMBAKARAN BOILER PF DAN CFB
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Fluidisasi didefinisikan sebagai suatu operasi dimana hamparan zat padat diperlakukan seperti fluida yang ada dalam keadaan berhubungan dengan gas atau cairan
KONSEP DASAR “FLUDISASI”
Jika hamparan itu dimiringkan, permukaan atasnya akan tetap horizontal dan benda-benda besar akan mengapung atau tenggelam di dalam hamparan itu tergantung pada perbandingan densitas dari partikel tersebut.
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Kecepatan aliran gas
Fixed bed Pnematic transport
Circulating fluidized bed
Bubbling fluidized bed
FENOMENA FLUDISASI
Abu /char
Klasifikasi GELDART
Klasifikasi GELDART dan karakteristiknya
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Increasing Gas Velocity
FixedBed
ParticulateRegime
BubblingRegime
Slug FlowRegime
TurbulentRegime
FastFluidization
PneumaticConveying
Gas
Solid
s Ret
urn
Solid
s Ret
urn
Solid
s Ret
urn
Uch
UUmf Umb
U
REZIM FLUIDISASI
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REZIM FLUIDISASI
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Pressure dropvs.velocity:
fixed →fluidised bed
HUBUNGAN ANTARA KECEPATAN FLUIDISASI DENGAN PENURUNAN TEKANAN DAN KETINGGIAN HAMPARAN
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Fluidisation:effect of gas distributor
type
HUBUNGAN ANTARA TIPE PLAT DISTRIBUTOR TERHADAP FLUIDISASI
Behavior of bubbles just above the distributor
Porousplate
Perforatedplate
Nozzle-typetuyere
Bubble captuyere
HUBUNGAN ANTARA TIPE PLAT DISTRIBUTOR TERHADAP FLUIDISASI
The Kunii-Levenspiel model2Gas flow =
gas flow via emulsion+ gas flow via bubbles
mf
i.e., with bed area A,and superficial velocity uo :
s s, up s,down
flow (uo-umf)*Avia bubblesub − umf
flow umf *Avia emulsion ub − umf
1Rise velocity of bubbles : ub = 0.711( gdb )
umfRise velocity of emulsion phase : ue = ε
Superficial rise velocity of emulsion gas : umf
Rise velocity of solids : u = u = u = 0
u0 − umfFraction of bed in bubbles : δ =
ub − u0Fraction of emulsion in bed
1-δ =
BEBERAPA MODEL PERSAMAAN KECEPATANThe Kunii-Levenspiel bubbling bed model
Bed height and bubble size
u0 − umf Bed height vs. velocity H − H mf
:=
H ubBubble diameter(Ao ~ bottom distributorplate
:0.4 0.8− + 40.54( u0 umf ) ( h A0 )= dbarea) 0.2
g
ub = ( u0 −1
) + 0.711( gdb )umf2Bubble rise velocity:
(Davidson & Harrison)
MENGHITUNG TINGGI HAMPARAN DAN UKURAN BUBBLE
Particlefragmentation,
attrition, abrasion, ...
Formasi bahan bakar batu bara
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Good solid/fluid contactGood heat transfer
→ →
Gas/solid reaction → →
Intensive mixing
Solid phase :Gas phase :
perfectly mixedplug flow
GAS ( or liquid) VELOCITY : determined by1. minimum fluidisation velocity Umf
2. terminal (settling) velocity of particles Ut
Fluidised Bed Combustion (FBC) Fluidised Bed Combustion (FBC)
Bubbling FBC Circulating FBC950°CTemperature
PressureGas velocityParticle sizeHeat transfer
750 -1 (→6 - 15~ 0.2
1 - 20 bar1 - 3 m/s~ 1 - 2 mm250 - 300 W/m²K
20) barm/s- 0.5mm
80 - 250W/m²Kat wall
POWER OUTPUT (MW/m²)≈ 0.7 × gas velocity(m/s)
× pressure(bar)
PEMBAKARAN BAHAN BAKAR PADAT
Sumber: fossil fuels (incl. peat), biomass, Renewable versus non-renewable
waste-derived fuelsfuels (↔ CO2)
Klasifikasi: chemical & physical properties, calorific valueGas-Liquid-Solid ; Proximate analysis, ultimate analysis
Fuel and pollutant-forming components : heat versus pollution
Objektif: heat, electricity, transport, incineration, coke, ......
BAHAN BAKAR
Fuels : examplesnatural gas, solid fuel gasification product gas, coke-gas,
Gas:landfillgas
Cair: gasoline, light fuel oil, heavy fuel oil, diesel fuel, biodiesel,methanol, ethanol, Orimulsion®, black liquor
Padat: coal, lignite, peat, wood, bark, municipal solid waste(MSW), refuse-derived fuel (RDF), packaging-derived fuel (PDF), tyre-derived fuel (TDF),sewage sludge, hospital waste, construction waste,agriculture andfood-processing waste, electronic & electricequipment(E&EE) waste, auto shredder residue (ASR), ....
KARAKTERISTIK BAHAN BAKAR
Fuel characteristics
Gaseous :
inertsCalorific value, sulphur content, (N2,CO2,water)
Liquids :
Calorific value, viscosity, volatility, coke residue and ash content,
surface tension, water content, colloidalstability, metallic components (V, Ni, Cu),
cetane-number
KARAKTERISTIK BAHAN BAKAR
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KOMPOSISI GAS BUANG DARI BERBAGAI BAHAN BAKAR
Important forsolid fuels
characterisation:
FUEL RATIO=
fixed carbonvolatiles
coal : FR ~ 1...10peat : FR ~ 0.3
wood : FR ~ 0.1plastics : FR ~ 0
ANALISIS PROKSIMAT DAN ULTIMAT BAHAN BAKAR
37.2
32.5HHV
(MJ/kg)27.9
23.2
18.6
13.9
ANALISIS PROKSIMAT BEBERAPA BAHAN BAKAR PADAT Fossil fuels, biomass and waste-derived fuel
(kJ / kg) 20220 22080 23240 32540 22540
Fossil fuels, biomass and waste:comparison 1
Vo latiles Mo istu re Ca rbon fix Ash Fu el ra tio HHV%wt %wt %wt %wt - MJ/kg
Coal (bit.) 30 5 45 20 1.5 26Pea t 65 7 20 8 0.30 22
Wo od 85 6 8 1 0.10 19Pap er 75 4 11 10 0.15 13
Se wa ge slu dge 30 5 20 45 0.66 12MSW 33 40 7 20 0.21 10RDF 60 20 8 12 0.13 15PDF 73 1 3 13 0.04 21TDF 65 2 30 3 0.46 37
PE,P P,P S 100 0 0 0 0 45+ prin t/co lo r 98 0 0 2 0 41
PVC 93 0 7 0 0.08 21
Fossil fuels, biomass and waste:comparison 2
C H N O S Cl%wt %wt %wt %wt %wt %wt
Coal (b it.) ~ 60 - 80 ~ 3 - 5 ~ 1- 2 ~ 10 ~ 1 - 5 ~ 0.01 - 0.1Coal (lign ite) ~ 50 - 60 ~ 5 ~ 1 – 2 ~ 20 - 30 ~ 1 - 4 ~ 0.01 - 0.1
Peat ~ 50 ~ 6 ~ 2 ~ 40 ~ 0.5 ~ 0.01Wo od ~ 40 - 50 ~ 6 ~ 0.2 ~ 45 ~ 0.1 ~ 0 .01Paper ~ 35 ~ 5 ~ 0.1 ~ 45 ~ 0.01 ~ 0 .01
Se wa ge sludge ~ 25 ~ 4 ~ 3 ~ 15 ~ 1 ~ 0.05MSW ~ 25 ~ 3 ~ 0.5 ~ 20 ~ 0.2 ~ 0.5RDF ~ 45 ~ 5 ~ 0.5 ~ 35 ~ 0.2 ~ 0.5PDF ~ 50 ~ 6 ~ 1 ~ 40 ~ 0.2 ~ 1TDF ~ 80 ~ 6 ~ 1 ~ 9 ~ 2
PE,PP,PS ~ 85 ~ 14 ~ 1PVC ~ 40 ~ 5 ~ 1 54 !!!
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Municipal solidwaste- typical composition
MSW
GlassCompostabl
e waste
RDF /SRF
PaperMetal
Refuse derived fuel /Solid recovered fuel
Plastics and their heating value in MSW
Fraction in MSW MJ /kgAvera ge pla stics ~ 31
Poly ethylene PE ~ 44Poly propylene PP ~ 43Poly uretha ne PU ~ 36
Poly vinyl chloride PVC ~ 15PET ~ 24
Nylon PA ~ 28Poly styrene PS ~ 39
ABS, SAN ~ 39Thermosets ~ 25
Rubber ~ 23Newspapers ~ 18
Carton paper ~ 16Wood ~ 15Food ~ 7
100 %
75 %
50 % Ash %wtFixed carbon %wt
25 % Moisture %wtVolatiles %wt
0 %
foamidue
at ntoale ste uel PS r VC
Pood.c W Paperludge r
100 %
Ash %wtFix d carbon %Moistur %wtVolatiles %wt
0 %
75 %
50 %
25 %
e i
%d
ra e
wt
ANALISIS PROKSIMAT DAN ULTIMAT BAHAN BAKAR FOSIL DAN LAINNYA
REAKSI PEMBAKARAN
Combustion with OxygenC + O2 CO2
2H2 + O2 2H2O
S + O2 SO2
C + 1/2O2 CO2
FUEL
Oxygen
HEAT
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CaSO4
CaO ½ O2
CO2CO2 H2O CO2SO2CO2 H2Osplash-zoneCnHm
CnHmCO CO2
½ O2CaO coalparticle
CO CO2
CaO fines CO2
CO2 CO bedCOcharsorbent
O2 CO2
MEKANISME PEMBAKARAN PROSES PENTING PADA PEMBAKARAN BATU BARA
coal particlep-coal,
devolatilization
volatiles
char
homogeneouscombustion
heterogeneouscombustion
CO2, H2O, …
CO2, H2O, …
tchar=1-2sectvolatiles=50-100mstdevolatile=1-5ms
t
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EMISI UDARA DARI PEMBAKARAN BATU BARA• CO2
• CO• NOx• SOx• Particulate matter• Trace metals• Organic compounds
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EMISI TOTAL KARBON DIOKSIDA UNTUK SETIAP NEGARA DARI KONSUMSI ENERGI (2011)
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Pembakaran batu bara
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KARBON DIOKSIDA, CO2
C + O2 CO2
Almost 99% of C in coal is converted to CO2.In order to lower CO2 emission levels, coal power plants will have to leave steam-based systems (37% efficiency) and go towards coal gasification technology (60% efficiency)
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Carbon monoxide, CO
C + ½O2 CO
CO is minimized by control of the combustion process (air/fuel ratio, residence time, temperature or turbulence).
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Particulate Matter
PM composition and emission levels are a complex function of:
1. Coal properties,2. Boiler firing configuration,3. Boiler operation,4. Pollution control equipment.
Bottom Ash Fly Ash
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PM controls Mainly post combustion methods:
Electrostatic precipitator (ESP)
99% (for 0.1>d(µm)>10)<99% (for 0.1<d (µm)<10)
Fabric filter (or baghouse) As high as 99.9%
Wet scrubber 95-99%
Cyclone 90-95% (d(µm)>10)
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Coal-S (CS, S2, S, SH)
char
COS, CS2H2S
SO SO2 SO3
O2, M-SO4
SO2 molecule
radicals
SOx Formation
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SOx reduction• Pre combustion removal:
• Physical cleaning (30-50% removal inorganic sulfur)• Chemical and biological cleaning (90% removal organic sulfur)
• Combustion configuration:• No benign sulfur species!• gasification combined-cycle systems (IGCC systems)
• Post-combustion removal:• Wet Flue Gas Desulfurization (FGD) (80-98%)
• In situ sulfur capture:• Dry Sorbent Injection (DSI) (50%)
• Sulfur Capture by Sorbent (Limestone) in CFB:����� → ��� + ���
��� + 12� �� + ��� → �����
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Nitrogen in Coal (1-2%)
Name Structure ~ Relative amount
Stability
Pyridine1 15-40% More stable
Pyrrole1 60% Less stable
Aromatic amines
6-10% Stable··
··
1Including structures made up of 2-5 fused aromatic rings.29/01/2017 70
Main NO Mechanisms
1. Thermal NO
2. Prompt NO
3. Fuel NO: volatiles-NO and char-NO
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Thermal NO(Zeldovich mechanism)
N2 + O ↔ NO + N
N + O2 ↔ NO + O
Strong temperature-dependence: >1300-1500°C
Not a major source of NO in coal utility boilers.
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Prompt NO
N2 + CHx ↔ HCN + N + …
N + OH ↔ NO + H
Prevalent only in fuel-rich systems.
Not a major source of NO in coal utility boilers.
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Fuel NO (-N in volatiles)
Fuel-N HCN/NH3volatiles
(formation)
(destruction)
HCN/NH3 + O2
N2
NO
NO + HCN/NH3
The major source of NO in coal utility boilers (>80%).
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Char NO (-N in the char)
Char-N + ½O2 → NO
Char-C + NO → ½N2 + Char(O)
(formation)
(destruction)
[char-NO = ~25%] < [volatiles-NO = ~75%]
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NO ReductionCombustion controls:1. Modification of combustion configuration:
• Reburning• Staged Combustion (air/fuel)
Post combustion controls:1. Injection of reduction agents in flue gas.2. Post-combustion denitrification processes.
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Reburning
devolatilization
volatiles
char
homogeneouscombustion
heterogeneouscombustion
CO2, H2O, NO…
Excess air
CO2, H2O, NO…
CO2, H2O, N2…
CHi·
CHi· + NO ↔ HCN
HCN + NO ↔ N2 + …
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Staged Combustion
devolatilization
volatiles
char
homogeneouscombustion
heterogeneouscombustion
CO, CO2, H2O, N2…
Fuel Rich
CO, CO2, H2O, N2…
CO2, H2O, N2…
O2
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FB COMBUSTION
SOME LABORATORY STUDIES
Fluidized Bed Combustion
Poor reactionHigh volatile
Fuel feed point
Tar, HC, Dioxin
NOx Formation
Gas fluidization
FuelTemperature Spot
Local flame
Feed rateFluidization VelocityOperation TemperaturePorous bedFuel Composition
Gas Producer:CO, H2, CH4
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I
USING VARIOUS BED MATERIAL
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Using porous bed material
• Mechanism of carbon deposit: Carbon Capture
Porous Solid
Porous particles capture V.M. at high temperature (capacitance effect); carbon deposit is formed within pores increase residence time
carbon depositV.M.
pore
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Properties of Bed Materials
* A: surface area, **V : pore volume.
Composition [wt%]
MS MS1B MSC AB1 AB2 QS
Al 2O3 91.3 84.7 93.7 69.4 69.4 -
SiO2 - 2.2 - 7.2 7.2 100TiO2 - 1.1 - 13.0 13.0 -Fe2O3 0.54 5.8 0.3 8.4 8.4 -CaO 0.07 0.8 - 0.3 0.3 -SO3 2.1 3.8 1.9 0.8 0.8 -
size[m] 690 399 200 385 287 273A* [m2/g] 187 195 211 63 63 -
V** [cm3/g] 0.44 0.32 0.45 1.18 1.18 -
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FB Apparatus for Devolatilization Experiments
Gas Analyzers
Pellet Feed
Data Processor
Filter Cooling
Electric FurnaceFlame sensor
Flow meter
O2 Gas Cylinder N2 N2 Gas Cylinder
O2
Flow meter
Fuel: PE pellet 1cm diam. X 1cm lengthBatch feed
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Effect of various bed materials on the onset of devolatilization
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Effect of solid type on formation of carbon deposit over bed material at high temperature
V.M. evolution Deposit carbon combustion
Capacitant effect
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Effect of solid type on formation of carbon deposit over bed material at high temperature
V.M. evolution Deposit carbon combustion
QS
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Relationship between onset of devolatilization and V.M. capture
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Effect of gas velocity and solid bed type on heat transfer coefficient at high temperature
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Onset of flame detection vs. heat transfer coefficient
Due to high volatile matter capture by the fine AB, the concentration of volatile matter in the freeboard could not be sufficient to maintain flame combustion
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Onset of flame detection vs. onset of CO2 detection
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Onset of flame, CO2 CO detection vs. Heat Transfer Coefficient
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II
A new method to evaluate horizontal solid dispersion
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• The extent of solid dispersion is evaluated by measuring the horizontal concentration profile of CO
• A carbon-loaded bed material prepared using the capacitance effect is used as a tracer
Principle of new tracer method
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carbon depositV.M.
Principle of new tracer method
(B) Carbon-loaded solid
pore
(A) Raw porous solid (contact with V.M./Tar)
(C) Gasfication(act as tracer)
CO
CO2
(D) Carbon removal(regeneration)
CO, CO2
O2
C + CO2 2CO
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Experimental sectionShutter method
Batch method
Horizontal dispersion measurement experiments
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Shutter method
Horizontal dispersion measurement experiments
Cross section : 16cm x 4 cm
Height : 71 cm
To CO analyzer
Left
wal
l
Bed material : MS1-B
Bed height : 10 cm
Tube inlet height : 20 cm
Bed temperature : 943 K & 1073 K
Experimental conditionC + CO2 2CO
PE pellet
X(0, L) = Xinit for 0<L< Lsht
X(0, L) = 0 for Lsht < L
Two-dimensional FB reactor
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Batch method
Cross section : 16cm x 4 cm
Height : 71 cm
To CO analyzer
Left
wal
l
Bed material : MS1-B
Bed height : 10 cm
Tube inlet height : 20 cm
Bed temperature : 943 K & 1073 K
Experimental conditionTsurumi-coal
X(0, L) = δ (Lbatch)
Horizontal dispersion measurement experiments
C + CO2 2CO
Two-dimensional FB reactor
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Thereby, the solid dispersion can be treated as a one-dimensional diffusion to the horizontal direction
• X(t,L) = mass fraction of tracers in the bed material• Dh = Horizontal solid dispersion coefficient (m2/s)• t = a function of time (s)• L = a function of length (m)
Horizontal Dispersion of Bed Material in a Two-dimensional Bubbling Bed
• Vertical solid mixing is very good• Horizontal solid mixing is poor
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The equation can be rewritten in a discrete form as
Horizontal Dispersion of Bed Material in a Two-dimensional Bubbling Bed
The transient change in X with a time step of △t is simplified as:
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The shutter method results:
The CO evolution rate dropped with the solid dispersion in the horizontal direction.
The concentration increased at the beginning and became steady after attaining complete solid mixing.
Dispersion model 0.0003 m2/s
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The batch method results:
The concentration increased at the beginning and became steady after attaining complete solid mixing. 29/01/2017 102
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IIIModel of combustion and dispersion of carbon-loaded solids
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Commercial scaling-up requires a model that simultaneously assesses carbon deposit combustion and horizontal solid dispersion.
Model of combustion and dispersion of carbon-loaded solids
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Commercial scale-up requirements
1. Combustion rate :
Reaction rate constant, k, can be controlled by changing temperature, oxygen concentration, superficial gas velocity and mass of fuel.
The parameter k is determined as:
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• C = Carbon loading in the bed• Dh = Horizontal solid dispersion coefficient (m2/s)• k = First order reaction rate constant (1/s)• L = Width of combustor (m)
2. Horizontal dispersion:
Dh/kL2 [-]
Commercial scale-up requirements
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Horizontal dispersion of carbon deposit over bed material is governed by deposit combustion rate, solid dispersion rate and horizontal scale of combustor.
Carbon deposit mixing
Carbon deposit combustionHigh reaction rate, poor mixing, large scale
Carbon deposit mixing
Carbon deposit combustionSlow reaction rate, good mixing, small scale
Commercial scale-up requirements
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One-dimensional Bubbling Bed
1. Horizontal solid mixing is assumed to be uniform because its small horizontal cross-sectional area
The bubbling fluidized bed model proposed by Kunii and Levenspiel is used to simulate the carbon deposit combustion
2. Vertical solid mixing is also assumed to be uniform because vigorous solid mixing induced by rising bubbles
Consequently, only a one-dimensional concentration profile of the gaseous component is examined.
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Model of carbon deposit combustion
The change concentration in the bubble:
The change concentration in the emulsion:
The fluidized bed consists of two phases: bubble and emulsionThe change in concentration in the bubble (Cb) and that in the emulsion (Ce) along the bed height is determined as
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Two-dimensional modelIn the two-dimensional bubbling fluidized bed reactor, horizontal dispersion of the carbon deposits takes place.
The mass flow rate of carbon deposit by solid dispersion in each cell is calculable as
At both ends of the reactor, the carbon mass flow through the wall is zero; consequently, the mass flow of carbon deposit is
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Experimental works
• Measurement of the combustion rate of carbon deposits in a one-dimensional combustor
• Measurement of the horizontal CO2concentration profile in a two-dimensional combustor during continuous combustion of carbon deposits
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Effect of operating conditions and oxygen concentration on k
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Calculated O2 concentration profile along bed height by one-dimensional model (temperature = 943 K, t = 0)
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Horizontal profile of CO2 concentration at upper surface of bed: comparison of experimental results and those of the two-dimensional model
High combustion rate Low combustion rate
Calc. O2: 5 %Calc. O2: 21 %
Calc. O2: 21 %
Carbon-loaded solid
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SOME REMARKS IN CFB
FB COMBUSTION
• Teknologi Pembakaran CFB telah secara selektif diaplikasikan di dunia untuk mengkoversi bahan bakar dari high sulphur refinery residues, lignite, etc.
• Teknologi CFB lebih SUPERIOR dibandingkan teknologi PC : Formasi Nox yang lebih rendah dan kemampuan menagkap SO2 dengan menginjeksikan limestone ke dalam reaktor
Boiler CFB
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• Bahan bakar yang fleksibel: CFB dapat menggunakanberbagai jenis bahan bakar seperti batu bara berkalorirendah, lignit, antrasit, sampah, limbah, dll.
• Renovasi & Modernisasi (R&M) and Life Extension (LE) terhadap pembangkit yang tua adalah pilihan yang efektif untuk menjadikan pembangkit hijau
• Perkembangan regulasi lingkungan memaksa keberadaan utilitas boiler yang sudah lama untuk di-revamping menggunakan boiler yang ramah lingkungan seperti CFB.
Boiler CFB
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Tidak ada desain paten yang dominanThe various designs prevailing have converged into a few groups1) Foster Wheeler with its compact design forms a unique trend
by itself.Envirotherm administers licences to various companies basedon the Lurgi technology. The largest manufacturer whosedesign originated from Lurgi is Alstom.The general design with hot or cooled cyclones, internal wing-wall heat transfer surfaces, and possibly a heat exchanger inthe loop seal, is followed by a great number of manufacturerslike the Jacksonville type of Foster Wheeler’s design (especiallyUSA), Alstom without external heat exchangers, Valmet etc.The most important development and application at presenttakes place in Asia, especially in China.
2)
3)
4)
69th IEA-FBC Technical Meeting, Aix-en-Provence,
September 2014
Desain CFB
TERIMA KASIH