Conversion of Biomass Particles

Transcription

1 Conversion of Biomass Particles Prof.dr.ir. Gerrit Brem Energy Technology (CTW) 4th of March 2015, Enschede Contents of the lecture Conversion of Biomass Particles Introduction on Sustainable Energy Energy from biomass Combustion of Biomass Particles Pyrolysis of Biomass Particles Biorefinery 1

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4 80 Million barrels oil per day! Energy scenario s Present consumption of 80 Mbarrels/day In 2030: 120 Mbarrels/day Half of present production sites will be exhausted in 2030 So we need another 80 Mbarrels/day 8 4

5 Drivers for sustainable energy Energy resource scarcity in the long term Costs (oil 150 $ / barrel, ) Environmental and Climate change Mankind s CO 2 emissions Security of supply Matter of politics, Self-sufficiency Decentral electricity production Alternatives! Sustainable energy sources Solar PV Solar heat Wind Biomass Geothermal 5

6 Biomass: closed CO 2 cycle Biomass characteristics Renewable Large quantities available Can be stored & transported Contains C, H (& O) production of conventional (oxygenated) hydrocarbon chemicals & fuels Sustainable (under strict conditions) 6

7 Sustainability Criteria minister Cramer Reduction greenhouse gases No competition with food chain Biodiversity Environmental impact (soil, water,air) Local prosperity Local welfare Biofuels - generations 1 st generation edible 2 nd generation non-edible Waste / Residue Energy crops Sugar Cane Sawdust Grass Vegetable Oil Rice Husk Algae 7

8 Biomass to products Heat Electricity Fuels Chemicals Materials Resources Primary conversion Intermediate Secondary conversion Application Biomass (wood, straw etc) Wet biomass Liquid waste streams Sugar Starch Oil crops Combustion Gasification Pyrolysis Hydro-thermal upgrading Digestion Super Critical Gasification Hydrolysis + Fermentation Extraction + Esterification Producer gas Syn-gas Bio oil Bio crude Biogas Hydrogen Syn-gas Bioethanol Fermentation broth Biodiesel Fischer-Tropsch synthesis Extraction + Esterification Hydrocracking Methanisation De-oxygenation Hydrolysis + Fermentation Heat Electricity Fuel Chemicals 16 8

9 Thermal conversion of biomass Thermal Conversion of Biomass Particles 100 Moisture 100 C 400 C Moisture Volatiles Fixed Carbon Ash Sample Weight [%] Volatiles 900 C Fixed C Ash 0 Nitrogen time, temp. Air 9

10 Combustion CH 1.4 O O 2 CO H 2 O H=-17.5 MJ/kg Process Complete oxidation of the organic material in an air or oxygen environment at high temperatures Conditions T > 850 C air/o 2 Products Heat CO 2, H 2 O and ash Biomass particle heat in the high temp. flue gase air/o 2 Ash 06 March

11 Single Particle Model (mass balances) Single Particle Model (dimensionless) 11

12 Single Particle Model (mechanisms) Single Particle Model (energy balance) Particle overshoot temperature 12

13 Combustion systems Characteristics of Combustion Systems 13

14 Fluidized Bed Combustion (FBC) flue gas steam generation C coal lime stone ash withdrawal combustion air Comparison of Fluidised Bed and Pulverised Fuel Firing fluidised bed bubbling circulating pulverised fuel firing air velocity [m/s] flue gas velocity [m/s] < flue gas temperature [ C] average grain [µm] fuel/inert material [%] 0,5-1 (5) 0, air ratio 1,2 1,2 1,2-1,5 cross sectional heat ,5-6,5 release rate [MW/m²] firing efficiency [%]

15 Gasification CH 1.4 O O 2 CO H 2 Process Thermal degradation of the organic material and partial oxidation of the decomposition products Conditions T = C, T > 1350 C P = 1 70 bar O 2 /H 2 O Products Fuel gas (CO, CO 2, H 2, C n H m, H 2 O, tars) Synthesis gas (CO, H 2, H 2 O, CO 2,) Ash and heat O 2 /H 2 O biomass particle heat fuel gas heat Gasification 15

16 Gasification cher Tropsch (1/2) Flash pyrolysis HEAT Gas (15%) O 2 Biomass particle Oil (70%) HEAT Char (15%) 16

17 Decomposition of biomass decomposition to vapours hemi cellulose cellulose wood lignin temperature o C Elementary processes in pyrolysis heat transfer to the biomass particle intra particle heat transfer primary cracking of the biomass intra particle mass transfer of products external particle mass transfer secondary vapour cracking in the reactor 17

18 Rate determining step Biot number: Bi = h 2r p /λ p Bi << 1 external heat transfer limitation Bi >> 1 internal heat transfer limitation Pyle number: Py = λ p /k b c p ρ p r p 2 Py << 1 internal heat transfer limitation Py >> 1 kinetics controlling factor (external/internal heat transfer resistance) (internal heat transfer/reaction kinetics) Ext. Pyle number: Py = h/k b c p ρ p r p (external heat transfer/reaction kinetics) Py << 1 external heat transfer limitation Py >> 1 kinetics controlling factor With: h = external heat transfer coefficient r p = particle radius λ p = thermal conductivity of particle λ g = thermal conductivity of gas k b = kinetic constant ρ p = particle density c p = specific heat of particle Reaction mechanisms in pyrolysis Pyrolysis: dissociation of biomass many parallel and sequent reactions many products complex to describe biomass primary cracking secondary cracking k g k o k c gas bio-oil char k sg k sc gas char 18

19 Flash pyrolysis of biomass Wood pyrolysis on lab scale - movie 19

20 RPS filter integrated in cyclone Drag force Rotation Centifugal force Particles Gas flow A A Accumulated partic A A Particle separation W p = W gas for small particles = f (flow, D c ) u p = f ( d p, Ω, ρ p η g, r ) 100 % separation if: L d > c w gas u p100% 20

21 particle collection efficiency 100 collection eficiency [%] tobacco smoke [0.55] corn oil [0.27] atmosph. dust [0.57] NaCl [0.42] fly ash [0.76] combust. residue [0.98] theoretical result dimensionless particle diameter [-] PyRos reactor Combustor Regenerator 21

22 Pyrolysis Oil Quality Improvement by Catalysis PyRos pilot-plant 30 kg/h biomass feed 22

23 Near-future applications for pyrolysis oil Biomass Gas condenser PYROLYSIS REACTOR Char Separation Bio-oil Heat Char BIOREFINERY 23

24 Biobased economy In 2030 biobased raw materials can supply at least 30% of the need for raw materials and energy in the Netherlands! More specific: 60% of transport fuels 25% of chemicals and materials 17% of space heating 25% of the electricity demand. 47 Potentials of Biomass The End 48 24