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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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27

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

DEVOLITISASII PROSES PEMBAKARANI29/01/2017 63

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

• Measurement of the combustion rate of carbon deposits29/01/2017 112

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