Biomass Co-Combustion and Gasification6pr.kpk.gov.pl/images/prezentacje/info/energy-conf/... · GAS...
Transcript of Biomass Co-Combustion and Gasification6pr.kpk.gov.pl/images/prezentacje/info/energy-conf/... · GAS...
CZESTOCHOWA UNIVERSITY OF TECHNOLOGYCZESTOCHOWA UNIVERSITY OF TECHNOLOGYCZESTOCHOWA UNIVERSITY OF TECHNOLOGY
TECHNICAL UNIVERSITYOF CZĘSTOCHOWA
TECHNICAL UNIVERSITYOF CZĘSTOCHOWA
ENERGY ENGINEERINGLABORATORY
ENERGY ENGINEERINGLABORATORY
Biomass Co-Combustion and Gasification
Wojciech Nowak
The largest potential and The largest potential and priority for thermal and priority for thermal and utility utility
power plants power plants as well as as well as activation the agricultural activation the agricultural
terrains and the farm terrains and the farm implement of waste landsimplement of waste lands
BIOMASSBIOMASS
The local development of biomass utilization in scale of municipal and village governments creates the large chance of development of these areas as well as the chance of improvement of natural environment
Acquisition of energy from biomass creates the new workplace in sector of power industry, agriculture, forestry as well as production and service of devices and technology, the competitiveness of Polish agriculture and forestry
Barriers to conquest
Accessibility of biomass in proper
Time
Place
With proper price and required properties
Biomass gathered from approx. 80 km gives continuous production approx. 60 MWth
In many cases it is difficult to accumulate biomassthat can guarantee heat production of 30 MWth
Co-Combustion
Why co-combustion?
� Possibility of biomass utilization in already existing heat and power generating plants
� A number of fluidized bed boilers � Risk minimization in price fluctuations and
accessibility of biomass� Lower emissions of atmospheric pollutants� Providing a CO2 neutral fuel source� Low investment costs (it is no necessary to
construct the separate feeding line when 5% of biomass is fired)
Co-combustion of biomass with coal in existing boilers- the most competitive source of renewable energy
� Mixture should be uniform� Mixture should posses proper
heating value and should be stable� Lower gas pollutant emissions� Lower coal consumption
Driving forces of co-combustion
New environmental requirementsSO2, NOx, CO, Dust
Local biomass and wood residues utilizationbark, saw dust, sludges, logs and paper
Cost savings compared to new boiler
Short delivery time
odpady biomasa
wêgielwegiel odpady
biom asa
wegiel
dodatkowe palenisko
Direct combustion in PC boilers
1 � milling system (capacity, wear) 2 � furnace (slagging) , 3 �superheater (corrosion); 4 �convective heat exchanger (fouling, erosion); 5 � DeNOx (deactivation, capacity, erosion); 6 �ESP (capacity); 7 � ash (utilization); 8 � DeSOx (capacity); 9 � DeSOx residue (utilization); 10
� flue gas (emission)
Co-combustion in PC boilersAreas of Concern
Unterrsberg S. Bio-Energy, Budapest, 2003
Circulating Fluidized Bed Boilers
CFB technology offers wide fuel flexibility
Coal- Anthracite- Bituminous- Sub-Bituminous- Lignite
Waste Coal- Bituminous Gob- Anthracite Culm- Coal Slurry
Petroleum Coke- Delayed- Fluid
Wood Residues- Bark- Chips- Wood Dust- Forest Residue- Demolition Wood
Peat
Oil Shale
Gas- Natural- "Off" Gases
Sludge- Paper Mill- De-Inking- Municipal
Refuse Derived Fuel
Paper Waste
Tires
Agricultural Waste- Straw- Olive Waste
Biomass feeding into existing CFB boilersA.Feeding into coal before the combustion chamber B.Feding directly into the combustion chamber
Biomass feeding line
Existing coal feeding line
FW materials, 2003
Temperature distribution in the combustion chamberTemperature distribution in the combustion chamber
CoalCoal
Coal Coal + + biomassbiomass
`Local heat transfer flux in the combustion chamberof CFB boiler with ununiform fuel feeding
Heat flux[kW/m2]
Area of concern
Agglomeration & Defluidization
• Poor mixing or low gas velocity, Tbed>Tashsoft
• Parameters: ug, T, mbed, dp,bed, λλλλ, O2
Important: fuel & bed composition (Na, Ca, K, CaSO4,silicates, aluminasilicates: problems)
Getting rid of agglomeration:uniform temperature, change of fuel or sorbent,ev. their PSD (from coarse to fine ones)
Problems of CofiringProblems of CofiringProblems of CofiringProblems of Cofiringof Coal and Alternative Fuelsof Coal and Alternative Fuelsof Coal and Alternative Fuelsof Coal and Alternative Fuels
• Agglomeration and Defluidization
• Fouling
• Corrosion
• Fuel composition - fluctuations
• Toxic byproducts in flue gas and ashes:CO, NOx, SOx, PM, VOC, DXNs, PAH,
Trace elements, alkalis
• Ash reuse/management
Surface corrosion
Caused mainly by acids in FG.Kinetics affected by fuel composition (mainly HCl)
Low oxygen and chlorine above 0.1% – critical
Counteractions:Separation of chlorine, HCl/Cl2 capture (in the furnace,
FGD, ESP)
Getting rid of chlorine by sorbent injection (eg. Na2O,Na2CO3, CaCO3)
Fuel composition & its fluctuation• Fluctuation of oxygen concentration in the furnace• Effect: emission of toxic byproducts
Waste combustion: emission control - difficultbiomass – O.K.
Lowest emission of CO & other carbon compounds at 6-10% O2in the flues gas
Counteractions:good mixing of fuel and oxygen, fuel change, higher temperature,more uniform fuel composition (eg. segregation, etc.)
Counteractions: Air staging, SNCR, SCR
NOxNONONONOxxxx from FBC: mainly NO (>90%) and NO2FBC: less NOx than from PC, CFB: less than BFB
Creation of NOx:fuel, thermal & fast NOx
FB: NOx mainly from fuel
Emission increase with air ratio, temperature, concentration in fuel
N2O
0 100 200 3000
100
200
300
N2O
[ppm
, prz
y 6%
O2]
NO2 [ppm, przy 6% O2]
Węgie l A Węgie l B Węgie l C Węgie l D
CounteractionsCounteractionsCounteractionsCounteractions:
higher temperature, less O2,
more CaCO3, combustion
of poor fuels (during devolatization
NH3 rather than HCN is created)
p=patm, λλλλ>1: sulfationReductive condition: CaS
Most efficient at 800-9000C
Dolomite – more sorbent, expensive, attritionbut acts agains defluidyzation
Desulfurization:dry, semi-dry and wet methodNew sorbents (synthetic, zeolites,
fly ash based sorbents, etc.
SOx
Lower emission:filters, bagfilters, ESPs, cyclones, multicyclones, ceramic
barrier filters (T<12000C)Also wet methods: scrubbers, spray towers
Coarse solids: gravitation, centrifugal, fine solids: electrostatics
PM 2.5 PM 2.5 PM 2.5 PM 2.5 –––– ultraultraultraultrafinesfinesfinesfines!!!!!!!!!!!!
PM
Trace elementsEmission from FBC lower than PC:
lower temperaturegood gas-solids separation (cyclones)good FG cool down
FBC: roughly 90% of metals is captured in the fly ash
DIOXINS=PCDDs, PCDFs, Co-Planar PCBs
Source ofSource ofSource ofSource of CreationCreationCreationCreation::::C, OC, OC, OC, O2222, H, H, H, H2222, Cl, Cl, Cl, Cl2222 + + + + Temperature Temperature Temperature Temperature Br, F (?)
O
O
12
346
98
7
O
12
346
98
7
12 3
4
6 5
co-planar PCBs
1'2'3'
4'
6'5'
PCDDs
PCDFs
SOME ‘DIOXIN PEOPLE’:SOME ‘DIOXIN PEOPLE’:SOME ‘DIOXIN PEOPLE’:SOME ‘DIOXIN PEOPLE’:H. Rghei, G. Eiceman, Chemosphere, 1982
F. Karasek, L. Dickson, Science, 1987Vogg, Stieglitz, Gullett, Bruce, Hiraoka, Hagenmaier, Milligan, Altwicker
DXNs – Some Facts:
• Chlorine source:
NaCl, PTFE, PVC, herbicides, etc.
• No effect of chlorine source
(organic, nonorganic) on DXN formation
• Chlorine Content: ?
• Required:
Reaction Time (>2s), Temperature,
Components, Free Oxygen (>1%)
Average Chlorine Content in Various FuelsAverage Chlorine Content in Various FuelsAverage Chlorine Content in Various FuelsAverage Chlorine Content in Various Fuels(% (% (% (% dry mass basisdry mass basisdry mass basisdry mass basis))))
Wood 0.08-0.13 Municipal Waste 0.05-0.25Bark 0.02-0.4 RDF 0.3-0.8Straw 0.1-1.5 Packages 1-4Refuse Dump Gas 0.005 Car Tyres 0.05-0.07Textiles 0.25 Auto Shredder Dust 0.5-2Newspaper 0.11 Computer parts 0.1-0.5Sewage Sludge 0.03-1 Plastic Waste 3.5PVC 50 Medical Waste 1-4
101 102 103 104 1051E-4
1E-3
0,01
0,1
1
10
100Municipal waste
Hospitalwaste
PCP-treated wood
Dio
xin
Emis
sion
[µg/
kg]
Chlorine Concentration [ppm]
Biomass Thomas & Spiro’sU.S. Summary Data
Low Emission of DXNs:• Less chlorine in fuel (PVC, NaCl separated)• 3T Technique (high Temperature, long residence Time,
better Turbulence) + Quick Quench of the flue gas
Other options:• High Temperature (>5500C) FG – ash separation system
(ceramic filters, ESP, cyclones)• Low Temperature (<1500C) FG – ash separation system• No deposition of fly ash in the flue gas duct• AC injection before the filter (HCl capture)• Flue Gas Recirculation• Injection of inhibitors (ammonia, urea, Na2SO3) and less O2
in the flue gas• Co-combustion with coal (SO2 reacts with chlorine and
steam, DXN formation decreased). FBC advantage!
No DXNs above 600-6500C – low concentration in the furnance
Main Problem:Formation in the FG Duct and Fly Ash Separator (de novo,
100x more behind the ESP than at the furnance outlet
The majorityThe majorityThe majorityThe majority od od od od DXNsDXNsDXNsDXNsis included in the Fly Ashis included in the Fly Ashis included in the Fly Ashis included in the Fly Ash!!!!
OurOurOurOur ApproachApproachApproachApproach::::Fly Ash Pelletization and Reburning in Fly Ash Pelletization and Reburning in Fly Ash Pelletization and Reburning in Fly Ash Pelletization and Reburning in
a a a a Fluidized BedFluidized BedFluidized BedFluidized Bed
Fouling
Condensation of alkalis from th egas phase & fouling on the surfaces
More alkalis (eg. biomass) – more troubles (when the flue gasis cooled down)
Counteractions:• separation of fines from the FG duct,• surface cleaning,• change of composition of fuel & bed,• different shape of surfaces (shorter contact time & area)
BoilerBoiler efficiency with biomassefficiency with biomass
0,0 0,1 0,2 0,3 0,4 0,5 0,60,60
0,65
0,70
0,75
0,80
0,85
0,90
ηη ηη k
X [kg H2O / kg paliwa]
Performance test results
Brown coal Brown coalBiomass
Biomass % (energy) 0 30Load % 100 100Efficiency % 92.7 91.6SO2 mg/m3n 476 356Limestone kg/s 1,18 1.0NOx mg/m3n 224 171CO mg/m3n 26 28
CONCLUSIONS
�Cofiring coal and biomass has been demostrated successfully in several CFB boilers
� Biomass can contain harmfull components like alkalis and chorine, which increase slagging and corrosion
� When converting existing CFB boiler for biomass cofiring, the save share of biomass depends on biomass and coal properties as well as boiler design, and must be determined case by case
�Combined heat and power results in more efficient use of biomass and couls contribute significantly to the economic viablility of electricity from biomass
Biomass gasification
FW CFB Gasifier
850°C
900°C
BOTTOM ASH COOLING SCREW
HOT LOW CALORIFICGAS (750 - 650 °C)
UNIFLOW CYCLONE
BIOFUEL FEED
REACTOR
BOTTOM ASH
GASIFICATION AIR FAN
COOLING WATER
AIR PREHEATER
RET
UR
N L
EG
• Developed in the late 1970s • Driving force the dramatic
increase in oil price• Foster Wheeler has supplied
7 commercial scale CFB/BFB gasifiers producing low CV gasfor different applications
FW materials, 2004
CFB Gasification Advantages� Cheap solid fuels can be converted to gas for
replacing expensive oil or gas � Waste wood� Bark� Other fuel fractions
� Allows the use of local fuel resources� A multi-fuel unit with good fuel flexibility
� Co-combustion in a PC boiler provides also a high electric efficiency for the biomass or waste utilized
Reference list of the atmospheric fluidized bed gasifier
Customer SizeMW
Fuel Application Year
Hans Ahlstrom Laboratory, Finland 3 Misc. Test unit 1981
Oy W. Schauman Ab, Finland 35 Bark,sawdust Lime kiln fuel 1983
Norrsundet Bruks Ab, Sweden 25 Bark Lime kiln fuel 1984
ASSI Karlsborg, Sweden 27 Bark Lime kiln fuel 1984
Portucel, Rodao, Portugal 15 Bark Lime kiln fuel 1985
Kemira Oy, Vuorikemia, Finland 4 1986
Lahden Lämpövoima Oy, Finland 40-70 Biofuels Hot raw gas toboiler
1997
Coal, peat
Test unit, clean gas
Corenso United Ltd., Finland 40 2000Aluminiousplastic waste
Cyclone cleanedgas to boiler
Electrabel, Belgium 50 Biofuels Hot raw gas toboiler
2002
FW materials, 2004
Biofuel/Multifuel Gasifier at Kymijärvi Power Plant, Lahti, Finland
� Direct gasification of wet fuels in an atmospheric CFB gasifier
� Atmospheric CFB gasifier produces 40 � 70 MWth low CV product gas to be co-combusted in a 125 MWe PC boiler
� Product gas replaces part of the utilized coal in the boiler
� Main fuels in the gasifier are local biomasses, industrial waste, paper and plastics
BIOMASS GASIFICATION - COAL BOILER - LAHTI PROJECT
Bottomash
Gasifier
Coal
540 °C/170 bar
Processing
Biomass
Fly ash
Pulverized coal flames
Gas flame
Natural Gas
50 MW
300 GWh/a -15 % fuel input
1050 GWh/a -50 %
350 MW
650 GWh/a -35 %
Power* 600 GWh/aDistrict Heat* 1000 GWh/a
CO2 Reduction -10 %
Biofuel/Multifuel Gasifier at Kymijärvi Power Plant, Lahti, Finland
CFB Gasifier at the Kymijärvi Power Plant
Lahti CFB Gasifier Design DataTotal fuel input to main boiler 2 000 000
MWh/aTotal input to gasifier 300 000
MWh/a
Substitution of fossil fuelsCoal 21.300 tonsNatural gas 15.7 milj.m3
Total energy 15%
Annual operating time of gasifier 6500 h(depending on heat load requirement)
Lahti CFB Gasifier Fuels
Gasifier Effect on Main Boiler Emissions
NOx Decrease by 10 mg/MJ (5 to 10%)SOx Decrease by 20 � 25 mg/MJCO No changeHCl Increase by 5 mg/MJ, base level
lowParticulates Decrease by 15 mg/nm3
Heavy metals Increase in some elements, base level low
Dioxins, etc. No change
Gasifier � PC Boiler Combustion Offers
� Lower environmental emissions� use of coal is reduced � lower CO2, SO2 and NOx emissions
� Better fuel flexibility� Possibility to use local fuel (biomass, recycled
industrial waste, plastics, etc.) resources in high efficiency steam cycle
� Low investment and operation costs� Utilization of existing power plant capacity� Only small modifications to the main boiler� High plant availability
Ruien Design� Plant owner is Electrabel, Belgium
� Gasifier fuel input 50 MW with 50% fuel moisture
� Process electrical efficiency 34% � Main boiler 36%, gasifier energy efficiency 98%
� Produced green electricity 17 MWe
� Annual production 120 GWh
Ruien Gasifier Lay-out
RUIEN
BRUSSELS
Main boiler
Main boiler ESP
Gasifier island
FW materials, 2004
Main boiler feed water
Main boiler furnace
Recycled fuels
CFB gasifier
Pulsing gas
Cooling water
Flare
LP steam
Filters
Fly ash
Bed materials
Gas cooler boiler
Fuel feed system
Gasification of Recycled Fuels
Summary � Development Work
� Gasification as a process proven technology for several fuel types
� Specific fuels e.g. ASR (Auto Shredder Residue) require further testing and development work
� Regarding the concept, development work at the moment is concentrated on clean gas production
� Gas cooling� Gas cleaning� Filter ash final treatment
Summary � Current Commercial Status
Fuels: Status:
- Wood, bark, shavings, saw dust - Commercial
- Recycled industrial waste, paper & -Commercialplastics
- Coal, straw, peat, RDF -Demonstrated
- ASR, other specific wastes - To be developed
Present Status of FW Atmospheric Gasifier Systems
Gasification is a way to high efficiency power production
from biomass and wastes
� Gasification� Gas combustion/co-firing in an existing boiler
Commercial technology
� Lahti 70 MW � Corenso 50 MW� Ruien 50 MW
Authothermal fuel upgradingAuthothermal fuel upgrading
Problems encountered when biomass is co-fired with coal can be avoided
Biomass is initially prepared before final combustion in the boiler
!! increasing carbonification of fuel and increasing energy densityincreasing carbonification of fuel and increasing energy density
!! moremore uniform uniform size distributionsize distribution
!! highhigh--efficient efficient „„distillationdistillation” ” of sulfurof sulfur, , chlorinechlorine, , mercury compoundsmercury compoundsand other gas pollutants from biomass and other gas pollutants from biomass by by lowlow--temperature temperature (750 (750 ooCC) ) heating through the wall without oxygen heating through the wall without oxygen
Biomasswastes
Fuel preparation
GrindingSegragation
Storage
Drying Thermolysis
Combustion
Combustion
Heat recovery Flue gascleaning
Pirolytic gases
to atmosphere
to atmosphere
Clean and upgrading fuel intoPC, CFB, stocker boilers etc
Schematic process of biomass and wasteSchematic process of biomass and wasteupgradingupgrading
Reactor Reactor for for biomass upgradingbiomass upgrading
BIOCARBON
PREBIOCARBON
Products of thermolysisProducts of thermolysis
Volume reductionVolume reduction
BiomassBiomass and biocarbon parametersand biocarbon parameters
Biomass I BBiocarboniocarbon II Biomass II BiocarbonBiocarbon IIIIWa [%] 4 0,7 20 1,0Wh [%] 4,8 4 3 1,9Wt
r .[%] 8,8 4,7 23 2,9Aa [%] 3 17,7 0,6 8,8Va [%] 84,2 32,2 76,3 43(F.C)a [%] 7,8 46,3 20,1 48,3Sa [%] 0,096 0,1 0,075 0,08Ca [%] 36,7 59 39,1 64,3Wg
a [kJ/kg] 18 720 26 790 18 150 24 400Wd
a [kJ/kg] 17 480 25 940 16 860 23 200
Biomass I – mixture of sawdust, wood chips, grass, leafs Biomass II –sawdust
Upgrading processUpgrading process
0 10 20 30 40 50 60 70 80 90 10015
20
25
30
35
40
4,5
Biocarbon II
35 SŁOMA40
4550
556065
7075
c = 80 %
6,5
6,05,5
5,04,5
4,0h = 3,5 %
DREWNO
WĘGIEL BRUNATNY
WĘGIEL KAMIENNY
ANTRACYT
Cie
pło
spal
ania
[M
J/kg
]
Substancje lotne [%]
Biocarbon I
0,0 0,1 0,2 0,3 0,4 0,5 0,60,5
0,6
0,7
0,8
0,9
1,0ηη ηη k
,η,η ,η,ηA
WP
,η,η ,η,ηk(
bioc
arbo
n) , δδ δδ
bioc
δδδδbioc
ηηηη AWP
ηηηη k
ηηηη k(biocarbon)
X [kgH2O/ kgpaliwa]
Biomasaw stanie roboczym
Cieplo do zagospodarowania
ComparisionComparision ofof efficiencesefficiences
Heat densityHeat density
1 2 30
5
10
15
20
25
BiocarbonBiomas aWęgiel kamienny
Cie
pło
spal
ania
[ G
J/m
3 ]
Upgrading network near power and heat generating plantsUpgrading network near power and heat generating plants
Conclusions
� The development of a bioelectricity industry will depend on the competitiveness of bioelectricity with coal
� Policies and regulations have a fundamental role in promoting energy from biomass and in ensuring the sustainability of biomass fuel chain
� There is a little market for biomass feedstocks for electricity generation in utility power plants
� Bioelectricity needs greater integration between energy, environment, and agricultural and foresty policies and a careful selection of technology aimed at the energy
� There is need for advanced conversion technologies such as gasification, upgrading and integration with gas turbines and fuel cells