Biomass conversion Technologies for energy.pdf

Biomass conversion technology

1. 中美应用技术教育“双百计划”
Biomass to Energy

2. 中美应用技术教育“双百计划”
What is biomass?
•According to the United States Information
Administration (EIA), biomass
•Organic material comes from plants and
animals
•Renewablesource of energy
•Stored energy from sun, when biomass
burned releases energy as heat
•Examples—woodand woodprocessing
wastes, agriculturalcrops, food, yard, and
wood waste

3. 中美应用技术教育“双百计划”
BiomassSources

4. 中美应用技术教育“双百计划”
Biomass-to-energy conversion technologies
•Biomass can be converted to fuels, electricity
•In this section, we will discuss technologies to
convert Biomass into energy Technologies

5. 中美应用技术教育“双百计划”
Biomass-to-energy conversion technologies
Source –Green chemistry, sustainable agriculture and processing systems:
A Brazilian overview, Agriculture and Human Values, DO -10.1186/s40538-
014-0005-1
Source –BiomassConversion Technologies, Science Direct,
https://doi.org/10.1016/B978-0-08-101036-5.00008-2

6. 中美应用技术教育“双百计划”
Thermochemical conversion technologies

7. 中美应用技术教育“双百计划”
Thermochemical conversion technologies
Combustion Pyrolysis Gasification
Process objective Maximumconversionoffeedstockto
heatenergyandfluegases(mostly
CO
2andH
2O).
Maximumthermaldecompositionof
feedstockintoliquidandgaseous
products.
Maximumconversionoffeedstockto
highsyngas(mainlyCO,H
2andCH
4).
Operational conditions
Environment Oxidantamountgreaterthanthat
neededforstoichiometriccombustion
(Oxidizing).
Absenceofanyoxidant. Oxidantlessthanthatneededfor
stoichiometriccombustion.
Reactant gas Air None pureO
2,Air,steam,steam+O
2,
supercriticalwater,CO
2
Temperature 850
o
Cand1400
o
C 400
o
Cand700
o
C Generallygreaterthan700
o
C
Pressure Mostlyatmospheric. Slightover-pressure. Mostlyatmospheric.
Process products
Gaseous products CO
2,H
2O CO,H
2,CH
4andC
nH
m CO,H
2,CO
2,H
2O,CH
4
Pollutants SO
2,NOx,HCl,PCDD/F,particulate H
2S,HCl,NH
3,HCN,tar,particulateH
2S,HCl,COS,NH
3,HCN,tar,alkali,
particulate
Ash Bottomashcouldbetreatedforthe
recoveryofmetalsandinertmaterials.
Disposedofasindustrialspecialwaste
aftertreatment.
Bottomashisusuallyproducedas
vitrifiedslagandusedasroad
constructionmaterial.
Gas cleanup Airpollutioncontroldevicesareneeded
tomeetemissionlimits.
Syngascleanupisneededasper
differentapplications(i.e.energy
conversionorchemicalsproduction)
requirementsandstandards.
Syngascleanupisneededasper
differentapplications(i.e.energy
conversionorchemicalsproduction)
requirementsandstandards.
Tab. 1-2 Comparison of main thermochemical conversion processes
[6]

8. 中美应用技术教育“双百计划”
What is pyrolysisand gasification?
Pyrolysis
•Distillation and combustionwithout oxygen
•Develops solid, liquid, gas
•Heatadds to feed
•Products formed:
•Gases formed require cleaning prior to use
•High temp(gases), low temp (solids)

9. 中美应用技术教育“双百计划”
What is pyrolysisand gasification?
Gasification
•Modification of pyrolysisat higher temps
•Limited amount of oxygenand heat
•Oxygen= pureoxygen, air, water
•Can be endothermicor exothermic
•Carbon in waste and oxygen creates a combustible gas
•Factors
•Gasificationagent—air, O
2, steam, CO
2
•Temperature—increase reaction rate, gas yield
•Pressure—gas production dependent
•Moisture—typically between 10 and 15%
•Heatingmethod

10. 中美应用技术教育“双百计划”
Advantages and Disadvantages
Advantages of Pyrolysis
•Produces little air pollutants due to operation at low
pressure and oxygen
•Lowash production
•Simplegas cleaning
•Produces viable fuels
•Reduce and prevents corrosion and emissions,
dioxin/furan formation, reduce thermal NO
xformation

11. 中美应用技术教育“双百计划”
Advantages and Disadvantages
Disadvantages of Pyrolysis
•Waste must be shreddedor separated
•Oils and tars may contain toxic/carcinogenic
compounds
•Products must be further treatedand may be cost-
extensive

12. 中美应用技术教育“双百计划”
Advantages and Disadvantages
Advantages of Gasification
•Furansand dioxinsdo not form
•Gas is cleaned of particulates before used
•Gas equipment is lessexpensive
•Ash from gasification forms a useful slag

13. 中美应用技术教育“双百计划”
Advantages and Disadvantages
Disadvantages of Gasification
•Sufficient amount of plastics, paper, and food are
required for process
•Products from gasification can cause environmental
problems

14. 中美应用技术教育“双百计划”
Types of Pyrolysis
Types of pyrolysis
•Slow –longretention times (hours/days), 400°Cheating
temp, produces charcoal
•Conventional –retention times of 5-30 min, 400-600°C
heating temp, produces char, liquid, syngas
•Fast/flash –short retention times (low as < 1 sec),
products at various temperatures (liquids, 400-650°C,
liquid/syngas 650-900°C, syngas at 1000-3000°C)

15. 中美应用技术教育“双百计划”
Pyrolysis Processes
Pyrolysis Processes
•Waste into bunker, crane mixeswaste, waste moves into
shredder
•Waste fed into gas tight hopper, screw or piston feeder
mixes and shreds waste
•Waste enters reactor(heated rotary drum) at
atmosphericpressure, no oxygen
•Thermal conductionapplies thermal energy through
reactor walls, reactor is filled with gas

16. 中美应用技术教育“双百计划”
Pyrolysis Processes
Pyrolysis Processes
•Waste enters reactor(heated rotary drum) at atmosphericpressure, no
oxygen
•Waste dried at 100-200°C
•Decompositionof H
2S, H
2O, CO
2at 250°C
•Bonds of aliphatic substances are brokenat 340°C
•Carbon materials enrichedat 380°C
•Bonds of C-O and C-N broken at 400°C
•Coal tar materialsconverted into fuel and tar at 400-600 °C
•Heat-resistant materials decomposed, aromatics formed(600°C)
•Aromatics produced, H
2 removedfrom organics (>600 °C)

17. 中美应用技术教育“双百计划”
Pyrolysis Reactors
Types of Pyrolysis Reactors
•Drum, kiln-shapedtube –externally heated
•Entrained-flow
•Fixed-bed
•Cyclonegasifier
•Fluidized bed
•Plasmafurnace

18. 中美应用技术教育“双百计划”
Non-thermal Pyrolysis Process
Catalytic pyrolysis/cracking
•Pyrolysis with catalystto reduce temperature and time
•Acidic materials,zeolites, alkaline compounds
•Treats low densitypolyethylene, high density
polyethylene, polypropylene, polystyrene
•Hydrocracking
•Feed with hydrogenandcatalystwith moderate
temperaturesand pressure

19. 中美应用技术教育“双百计划”
What is pyrolysisand gasification?
Process
•Complex chemical polymers of long chains are pyrolysized
into chains and moleculeswith lower molecular weights

20. 中美应用技术教育“双百计划”
Types of Gasification
Conventional
•Preprocessing of solid waste creating refuse derived fuel
(RDF) and recyclables
•RDF, air, oxygen, steamenters gasifier produce syngas
and ash/slag
•Part of the raw syngas can be used for power generation
•Cleanedsyngas for power or chemical/liquid fuels

21. 中美应用技术教育“双百计划”
Types of Gasification
Thermal Arc Gasification
•Waste is introduced into plasma field, intenseheat breaks
down compounds
•Produced gas scrubbedto remove impurities, used for
electricity
•Plasma gas has high temperature (<15,000°C), reactor
heats to 2000°C

22. 中美应用技术教育“双百计划”
Gasification Processes
Gasification Processes
•Drying –waste heatedbelow 200°C, evaporation
releases moisture
•Pyrolysis –waste heated to high temperaturew/o air/O
2,
breaks down into charcoal, tar gases, liquids
•Direct heated gasification –release of light hydrogen-rich
volatile hydrocarbons
•Indirectheated gasification –steam adds hydrogen to
system, forms methane, reduces temps

23. 中美应用技术教育“双百计划”
Gasification Processes
Gasification Processes
•Cracking –large complex molecules into lightergases by
heat, ensures proper combustion
•Combustion –fueledby tar gasses/char from pyrolysis,
good mixand high tempformation
•Reduction–oxygen molecules are strippedoff combustion
products, molecules will be burnedagain; CO
2/water vapor
across hotcharcoal

24. 中美应用技术教育“双百计划”
Gasification Configurations
Gasification Processes
•Fixed bed—waste fed at top of reactor moving slowly through bed,
ash/char removed at bottom
•Up-draft –countercurrentflow; air moves from bottomand
waste from top; gas exits at top
•Down-draft–co-current flow; waste added in middle or top
moving downward drying and pyrolyzing
•Cross-draft–air inlet and gas outlet are on opposite sides in
middle of reactor
•Hybrid fixed bed—combination of up-draftand down-draft

25. 中美应用技术教育“双百计划”
Gasification Configurations
Gasification Processes
•Fluidized bed —fluidized inert material and
feedstock by stream of air
•Bubbling Fluidized Bed–highgas
velocity to lift solid particles within an
expandingand bubblingbed material
•Circulating Fluidized Bed(entrained
flow)–no difference in dense solid zone
and dilute solids zone; gases are at a
higher velocity, feedstock is entrained
(trapped in gases) and moves to top

26. 中美应用技术教育“双百计划”
Gasification Configurations
Gasification Processes
•Slagginggasification —melt inorganics present in waste
•Slag is inert and recyclable as construction material
•Requires high temperatures, utilizesoxygen
•Performance Criteria
•Coldgasefficiency—energy producedby syngas
divided by energyproduced by combustionofproduct
augmented by energy for thermalprocesses

27. 中美应用技术教育“双百计划”
Gasification Configurations
Performance Criteria
•Fuel gas production
•Coldgasefficiency

28. 中美应用技术教育“双百计划”
Gasification Configurations
•H
2and CO yields
•H
2yield is ratio of H atoms in syngas to H atoms in the injection
•CO yield is ratio of C atoms formed in CO to C atoms injected
•Tar content in syngas
•Challenging issue, effects gasification performance and design
•Mixture of condensablehydrocarbons or organic compounds with
molecular weight higherthan benzene(C
6H
6)

29. 中美应用技术教育“双百计划”
Gasification Configurations
•Tar content in syngas
•Must be cleanedof tar –physical, thermo-chemicaland
catalyticprocesses
•Tar levels depend on design(updrift-dirty, 100 (gN/m
3
) and
downdrift-clean, 1 (gN/m
3
))
•Factors—Particle size, morphology, moisture content, ash
content

30. 中美应用技术教育“双百计划”
Gasification Configurations
Plasma Gasification
•Waste is introduced into plasma field, intenseheat breaks
down compounds
•Produced gas scrubbedto remove impurities, used for
electricity
•Plasma gas has high temperature (<15,000°C), reactor
heats to 2000°C

31. 中美应用技术教育“双百计划”
Gasification Configurations
Plasma Gasification
•Plasmaarcgasifier
•Plasmaassisted—plasma torchesin reactor, heat breaksapart chemical
bonds in feedstock and formsgas; inoragnics collectedat bottom
•Plasmacoupledwithtraditionalthermalgasification
•Arrangements
•Updraft–insert feed at chambertopmoving downward, oxidizing agent
in middle/bottom, syngas exits at reactor top
•Preventstar formation, high temperatures (>1000)
•Design—size, moisture content, calorificvalue

32. 中美应用技术教育“双百计划”
Gasification Configurations
Plasma Gasification
•Plasma arc gasifier system
•Plasma furnace, metal and slag collection
•Secondary combustion chamber
•Water quencher
•Cyclone or baghouse
•Scrubber
•Hydrogen sulfide absorber
•Filters or precipitators
•Activated carbon filters
•Fans

33. 中美应用技术教育“双百计划”
Gasification Configurations
Issues with Plasma Arc Gasification
•Stabilityandservicelifeofrefractoryliningsbecauseofhigh
temperatures
•Reductionof electrodelifedue to waste characteristics and
corrosivegases formed
•Vaporizedmaterials (Cd, Hg, Pb, HCl, NH
3, H
2S) can be emittedto
atmosphere following combustionchamber
•Highof amount of external, electricalenergy required

34. 中美应用技术教育“双百计划”
Task
Explain Why we are not adopting Biomass energy conversion
technologies on a large scale as we are adopting Fossil fuel base
technologies.