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Fast pyrolysis for bioenergy and biofuels Fast pyrolysis for bioenergy and biofuels

Fast pyrolysis for bioenergy and biofuels - PowerPoint Presentation

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Fast pyrolysis for bioenergy and biofuels - PPT Presentation

Tony Bridgwater Bioenergy Research Group European Bioenergy Research Institute Aston University Birmingham B4 7ET UK Biofuels2015 Valencia Spain 25 August 2015 2 What is pyrolysis ID: 437222

liquid pyrolysis fast oil pyrolysis liquid oil fast biomass bio hydrogen char catalysts yield phase vapour cracking water solids

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Slide1

Fast pyrolysis for bioenergy and biofuels

Tony BridgwaterBioenergy Research GroupEuropean Bioenergy Research InstituteAston University, Birmingham B4 7ET, UK

Biofuels-2015, Valencia, Spain 25 August 2015Slide2

2

What is pyrolysis?Biomass is heated in the absence of air or oxygen to decompose or devolatilise the biomass into:

Solid char

Liquid as bio-oil, tar or pyroligneous liquor

Gas

Three

products are always produced

Product yields depend on biomass, vapour and solids residence time, and temperature

There are several modes of pyrolysis ...............Slide3

Pyrolysis modes

Mode

Conditions

Wt % products

Liquid

Char

Gas

Fast ~ 500ºC; very short hot vapour residence time (RT) ~1 s; short solids RT75%12%13% Inter-mediate ~ 400ºC; short HVRT ~10-30 s; moderate solids RT40% in 2 phases40%20%Slow~ 400ºC; long HVRT; very long solids RT35%35%30%Torre-faction~ 300ºC; long HVRT; long solids RTVapours85% solid15% vapoursGasif-ication~ 800-900ºC; short HVRT; short solids RT1-5%<1% (all burned)95-99%

3Slide4

Fast pyrolysis products

Fast pyrolysis aims to maximise organics as liquids. This comes from very high heating rates from small particle sizes of generally <3mm in

size

and < 10%

moisture

Clean wood

gives highest liquid yield up to 75 wt.% on dry biomass feed. This is single phase, low viscosity. Ash causes catalytic vapour cracking, hence lower organic yields, higher water and potential phase separationThe charcoal forms about 10-15 wt.% of the products. It retains virtually all the alkali metals. It is usually consumed in the process to provide process heat.4Slide5

5

Bio-oil yield from Aspen Poplar

Char

Gas

400 450 500 550 600 650

Reaction temperature, C

Yield, wt.% of dry feed

Organics

Reaction water

80%

70%

60%

50%

40%

30%

20%

10%

0%Slide6

6Fast pyrolysis requirements

Organics

provides the energy in the product and can be converted into chemicals and/or fuels. The organic yield is thus critical.

Fast pyrolysis requires:

High heating rates:

Small particle sizes needed as biomass has low thermal conductivity

Dry biomass

(<10wt.% water): Feed moisture goes into bio-oil product plus reaction waterCarefully controlled temperature: ~500C is optimum temperature for maximising liquid yieldRapid and effective char removal: Char and alkali metals are catalytic and reduce liquid yieldShort hot vapour residence time: Thermal cracking reduces liquid yieldSlide7

Catalysts

All biomass contains inorganic materials which act as a catalyst as well as contaminants.

C

atalysts can be added to the biomass prior to, during, or after fast pyrolysis.

Natural catalysts

Alkali metals (e.g. K, Ca, Na) as “ash”

Contaminants

Heavy metals (e.g. Fe) from soil and wastesNon-metals (e.g. S, Cl, P) may also be presentProductsChar (which contains the biomass ash)Synthetic catalysts for product enhancement In-situ Close coupled (ex-situ) RemoteSlide8

Effects of ash and contaminants

Catalysts as ash and char

crack

organic products from pyrolysis into water and carbon dioxide leading to:

a

lower organic content

vapour and liquid with less energy

And potentially a phase separated liquid product Potassium is the most active alkali metal in crackingChar is also catalytic from the alkali metal contentAsh contents of typically more than 3 wt.% ash can cause phase separation in the liquid. Phase separation is non-reversible and can only be remedied by addition of high proportions of ethanol or similar solvents.Slide9

Typical fast pyrolysis reaction system

BIOMASS

Gas

recycle

C

HAR

process heat

or exportQuenchGASBIO-OILESPGrindingDryingPyrolysis reactorChar removal9Slide10

Fast pyrolysis reactors

Fluid bed

Spouted fluid bed

Transported bed

Rotating cone

Ablative

Circulating fluid bed

VortexCentrifuge reactorAugur or ScrewRadiative-convectiveEntrained flowMicrowaveMoving bed and fixed bedCeramic ball downflowVacuumCommercial activities10Slide11

CFB or Transported bed reactor

BIO-OIL

BIOMASS

H

ot flue

gas

Gas recycle

Sand+CHARCombustorPyrolyserAirHot sandGASexportQuenchESPCyclones11Slide12

Fast pyrolysis: commercialisation

Ensyn (CA)

:

100 t/d

transported bed in

Canada +

8 or 9 in USA

BTG (NL) : 125 t/d Empyro 12Fortum (FI) & Metso (FI):Slide13

Fast pyrolysis liquid – bio-oil

13

Moisture content

25 %

pH

2.5

Specific gravity1.20Elemental analysis C H O N Ash56.4 %6.2 %37.3 %0.1 %0.1 %HHV as made17 MJ/kgViscosity (at 40°C)40-100 cpSolids (char)0.05 %Vacuum distillation residueMax. 50%Slide14

Decentralised fast pyrolysis

14

Bulk density

Biomass density can be as low as 100 kg/m

3

Bio-oil density is

1200 kg/m

3Bio-oil liquid storage, handling and transportTanks and pumps are used No windblown refuse, vermin, or mechanical handlingProvides optimum use of loading weight restrictionsCentral processor e.g. for biofuelSlide15

Direct use of whole bio-oil

Heat and power

15

Electricity

Heat

Boiler

Turbine

Fast pyrolysis to liquidsCHPEngineChemical substitution Phenolics in wood resinsPreservativesSlide16

Bio-oil for biofuels

Ind

irect

production

G

asification

of bio-oil followed by hydrocarbon or alcohol

synthesis. There are many technical and economic advantages of gasification of liquid bio-oil rather than solid biomass Direct productionVia catalytic upgrading of liquid or vapourCatalyst can be added to biomass; incorporated into the fluid bed material; use of a close coupled reactor; use of a remote reactorEx-situ or secondary reaction offers independent control over process conditions; 16Slide17

Direct routes

Indirect routes

Pyrolysis

routes to biofuels

Hydrocarbons, BioSNG,

Syndiesel

, Syngasoline, BioLPGSyngasZeolitecrackingLiquid bio- oilAlcoholsGasificationHydro-treatingConversion e.g. Fischer TropschMethanol + MTG etc.Fast pyrolysisAdditives

Esters

Blends

BiomassSlide18

Vapour cracking

Zeolite cracking

rejects oxygen as CO

2

Vapour processing in a close coupled

process

No hydrogen requirement, no pressure

Projected yield of around 18wt.% aromatics This is now being developed by e.g. Kior and othersZSM-5 has attracted most attention due to shape selectivity to aromatics, with promoters such as Ga or Ni.The catalyst rapidly cokes which requires frequent regeneration as in an FCC unit. Oxygen is thus removed as CO and CO2 compared to H2O in hydroprocessing. Production of aromatics is also likely to be of significant interest to the chemicals sector.Slide19

Hydrodeoxygenation (HDO)

Hydro-deoxygenation

rejects oxygen as H

2

O

Liquid processing with

hydrogen and high pressureProjected yield of around 15wt.% for refiningOriginal research used sulphided CoMo or NiMo catalysts on aluminosilicate which tended to hydrolyse due to waterMore recently, precious metal catalysts on inert supports have been developed with a preference for Pd and RuExtent of deoxygenation depends on:Severity of upgrading conditions – pressure, temperature, catalyst and residence timeBio-oil production process and feedstockIt is likely that multiple upgrading steps will be neededSlide20

HDO

2

Coking

limits catalyst performance and life

Complete deoxygenation is very difficult especially with phenols

Recent research has moved to

partial

HDO, but all processes are high pressure (<200 bars) and moderate temperature (<400C) Provision of hydrogen remains a major challenge. Low hydrogen conversion requires costly recycling with hydrogen separation and compression. Completion of partial upgrading in conventional refineries is an attractive opportunityHydrodeoxygenation has been combined with other techniquesSlide21

Hydrogen

Since the hydrogen requirement is significant, it should be renewable and sustainable. Few refineries have a hydrogen surplus

Hydrogen can be generated by

gasification

of biomass, shifting CO to H

2

followed by scrubbing CO

2Bio-oil can be phase separated. The organic phase containing typically 20% water can be hydroprocessed and the aqueous phase can be steam reformed to hydrogen. The necessary purity of hydrogen is unknown, but some CO shifting may take place in the hydroprocessing reactor removing the need for dedicated shift reactors.Slide22

Other upgrading methods

A variety of methods and catalysts have been investigated in recent years as exemplified below:

Acid cracking in supercritical ethanol

Aqueous-phase reforming + dehydration + hydrogenation

Blending

Dicationic

ionic liquid C

6(mim)2−HSO4Esterification of pyrolysis vapoursEsterification of liquid bio-oilHydrogenation−esterification over bifunctional Pt catalystsReactive distillationSolid acid catalysts 40SiO2/TiO2−SO42- Solid base catalysts 30K2CO3/Al2O3−NaOHSteam reforming ZnO, MgO and Zn-Al and Mg-Al mixed oxidesSlide23

EsterificationSlide24

C

hemicals

Fractionated oil

Liquid

smoke (commercial)

Anhydrosugars

Asphalt

De-icersFuel additivesHydrogenPreservativeResin precursorsSlow release fertiliserSpecific chemicalsAcetic acid (commercial)FurfuralHydroxyacetaldehydeLevoglucosanLevoglucosenoneMaltolPhenol and phenolicsSlide25

Combinations

Biomass

Liquid

Vapour

Whole oil

Chemicals

Hydrocarbons

Improved bio-oilHydrogenCatalysisFast pyrolysisWaterExtractionAqueousOrganicRefiningCatalytic fast pyrolysisSeparationModific-ationCatalysisSlide26

Fast pyrolysis for primary conversion

Hydro-treating

Zeolite cracking

Hydrogen separation

Electricity

Heat

Fast pyrolysis

GasificationSynthesisTransport fuelsRefiningSlurryCharLiquidChemicals26Slide27

Slow pyrolysis and chemical recovery

Usine Lambiotte

carbonisers

and liquid

tar processing

Usine Lambiotte primary distillation columnSlide28

Opportunity from ~100,000 t/y wood

t/year

€/t

k€/

y

%

Charcoal

25,000*1002,50031.5Total pyroligneous liquid40,000Water30,000Organics10,000Acids and alcohols3,8304521,73221.8Oils3101,258390Fine chemicals5649,7322,78535.1Fuel5,80490522Total organics10,0005435,42968.5Total income7,92928Slide29

Conclusions

Pyrolysis is very

flexible

in the process and products.

Fast pyrolysis provides a

liquid

as an energy carrier

The liquid is alkali metal free Decentralised pyrolysis plants offer improvementsBio-oil can be used for fuel, chemicals and/or biofuelsFast pyrolysis technology needs to be improved to reduce costs and increase liquid yield and qualityFast pyrolysis liquid upgrading needs to be developed and demonstrated 29Slide30

Thank you