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					                                   Module 1c

                  Biomass Fuel Characteristics
                      and Pre-treatment




             Content

             1.    Fuel characteristics

             2.    Pre-treatment of biomass




                  Training course on Renewable Energy   1
slide 2/34




                                                            1
      1                  Biomass Fuel Characteristics

                         Items:
                         •      The meaning of reference bases
                         •      Moisture content
                         •      Ash content
                         •      Volatile matter content of biomass
                         •      Elemental composition of biomass
                         •      Proximate and ultimate analysis
                         •      Calorific value
                         •      Bulk density
                         •      Biomass characteristics related to the environment
                         •      Fuel characteristics and biomass versus fossil fuels
                         •      Ash properties


                                              Training course on Renewable Energy                                                                                                                                                                                                            2
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      Composition
     Biomass consist mainly of C, H, O: CxHyOz

                                                                                 Feedstock composition(wt%) dry

                    60

                    50
                                                                                                                                                                                                                                                                                   C(wt%)
                    40                                                                                                                                                                                                                                                             H(wt%)
        (wt%) dry




                                                                                                                                                                                                                                                                                   O(wt%)
                    30                                                                                                                                                                                                                                                             N(wt%)
                                                                                                                                                                                                                                                                                   S (wt%)
                    20                                                                                                                                                                                                                                                             Cl(wt%)
                                                                                                                                                                                                                                                                                   F(wt%)
                    10
                                                                                                                                                                                                                                                                                   Br(wt%)
                     0
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                                              Training course on Renewable Energy
slide 4/34




                                                                                                                                                                                                                                                                                                 2
      Composition




                        io as o p s n
             Figur e 1 B m sc m o itio




                        Training course on Renewable Energy
slide 5/34




      Reference bases

      ISO 1170:                                          This course:
      •      As-received basis                           •      Wet basis
      •      Air dried basis                             •      Wet basis
      •      Dry basis                                   •      Dry basis
      •      Dry and mineral matter                      •      Dry and mineral matter
             free basis                                         free basis
      •      Dry and ash free basis                      •      Dry and ash free basis




                        Training course on Renewable Energy                              6
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                                                                                             3
              Recalculation from one basis to another

                    wet basis to dry basis:
                                                                  dry basis to wet basis:




               dry basis to dry and ash free basis:           dry and ash free basis to wet basis:




             Recalculation of a fuel quantity at one reference moisture content (MC1)
             to another (MC2):


                                                                                1



                        Training course on Renewable Energy                                           7
slide 7/34




Proximate analysis                                            Ultimate analysis

MC (Moisture Content)                measured                 MC                      measured


 (ash content)                      measured                                        measured


Volatile                                                      C (carbon)              measured
matter                               measured

Fixed                                calculated               H (Hydrogen)            measured
carbon                               by difference


                                                              others
                                                              (N, S, etc.)            measured

                                                              O                       calculated
                                                                                      by difference

                        Training course on Renewable Energy                                           8
slide 8/34




                                                                                                          4
              Heating values (MJ/kg):
                                   Constant pressure                 Constant volume

              Water present HHVp:                                    HHVv:
              as liquid     Higher Heating Value                     Higher Heating Value at
                            at constant pressure.                    constant volume.
                            Also called GCV,
                            Gross Calorific value
              Water present LHVp:                                    LHVv:
              as vapour     Lower Heating Value at                   Lower Heating Value at
                            constant pressure.                       constant volume.
                            Also called NCV (Net
                            Calorific Value)



               Source and further reading: Tariq et al, “Biomass Combustion Systems”, NRI, ISBN 0-
               85954-385-4, 1994


                     Training course on Renewable Energy                                             9
 slide 9/34




    Heating value: general
   Energy                                   Energy                                          Energy
   input                                    converter                                       output


                                                     Conversion losses

          Energy input: massflow[ kg s ] * heatingvalue[ J kg ]
                     m  HHV (or LHV )
                     Pnuttig   Energy input  Conversion losses
   Efficiency:             
                   m  HHV             Energy input


                     Training course on Renewable Energy
slide 10/34




                                                                                                         5
    HHV emphirical calculation
    from Milne in MJ/kg (dry)

HHVdry  0,341 YC  1,322  YH  0,0686  YS  0,12  YN  0,12  YO  0,0153  Yash


                      Database on various types of biomass:

                                                                                                    http://www.ecn.nl/phyllis




                                                     Training course on Renewable Energy
slide 11/34




       Heat Energy Content
                                                                       Heating values Feedstocks
                                            HHV(MJ/kg)
                                25          LHV(MJ/kg)
      Heating value(MJ/kg)dry




                                20


                                15


                                10


                                5


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Source: ECN Phyllis
                                                     Training course on Renewable Energy
slide 12/34




                                                                                                                                                                                                                                6
 Determining HHVdry bomcalorimeter




                     Training course on Renewable Energy
slide 13/34




Heating value vs moisture content

              20000

              15000
              10000

              5000

                 0

              -5000
                   0%         20%    40%      60%      80%
                                Moisture content (wet basis)

                                LHV v,d                    LHV p,d
                                HHV v,d                    HHV p,d

                                                                     11

                     Training course on Renewable Energy
slide 14/34




                                                                          7
 Heating value vs moisture content

              20000

              15000

              10000

              5000

                   0

              -5000
                   0%        20%    40%      60%      80%            100%
                               Moisture content (wet basis)

                              LHV v,w                    LHV p,w
                              HHV v,w                    HHV p,w


                                                                              12
                   Training course on Renewable Energy
slide 15/34




Typical Characteristics of various Biomass Fuels
Type                          LHVw (MJ/kg)                MCw (%)           d (%)
Cotton residues:
- stalks                            16                     10 - 20          0.112
- gin trash                         14                        9
Maize:
- cobs                            13 – 15                  10 - 20           2
- stalks                                                                   3–7
Peat                               9 - 15                  13 - 15        1 – 20
Straw                               12                       10             4.4
Wood                              8,4 – 17                 10 - 60      0.25 - 1.7
Charcoal                          25 - 32                   1 - 10       0.5 - 6




                   Training course on Renewable Energy                               13
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                                                                                          8
 2            Logistics and pre-treatment:

 Requirements
 •     well-defined input specifications bioenergy installation
 •     high efficiencies
 •     suitable biomass storage properties
 •     suitable biomass transport properties
 •     biomass available throughout the year

 Goal
 •    Biomass conversion to energy with the highest possible
      efficiency and at the lowest costs




                    Training course on Renewable Energy           14
slide 17/34




          Steps in pre-treatment:

          •       Harvest
          •       Storage
          •       Sizing
          •       Drying
          •       Densification, liquefaction or carbonisation
          •       Transport and logistics




                    Training course on Renewable Energy           15
slide 18/34




                                                                       9
 Drying:

 Why?
 •    Sometimes for storage (against degradation, combustion)
 •    Can lower transport costs
 •    To facilitate thermal conversion or densification

 Drying methods
 •     Without heat production (air drying, mechanical drying)
 •     Convective heat transfer (band drying, pneumatic drying)
 •     Combination convection/conduction (rotating dryer)

 Result
 •      Increase in Lower Heating Value (LHV), and
 •      Decrease in total mass

                Training course on Renewable Energy               16
slide 19/34




  Drying (2):

  Where?
  •     If possible natural drying near harvest area, befor
  transportation
  •     If not possible drying with waste heat from conversion
        installation

  Energy use
  •     About 13.5% of the LHV is lost for drying from MCW =
  50% to
        MCW = 15% at 85% efficiency

  Costs
  •     Ca. 2 Euro/GJ
                Training course on Renewable Energy               17
slide 20/34




                                                                       10
 Sizing:

 Why?
 •    Input conditions conversion installation
 •    Facilitates transport and handling

 Various sizes
       Chain saw                  logs                                                      > 10 cm
       Chipper/chunker            chips/chunks                                              0.5 - 10 cm
       Hammer mill                powder                                                    <0.5 cm

 Where?
 •    At the conversion installation, to reduce the bulk density
      (lower transport and storage costs) and the risk of degradation
 •    Near the harvest area giving better handling and integrating
      harvesting and sizing

               Training course on Renewable Energy                                                                    18
slide 21/34




 Sizing (2):

 Energy use                                                      3000
 •     Rises steeply with
                                      Energy use (MJ/tonne ds)




                                                                 2500
       decreasing
                                                                 2000
       particle size
                                                                 1500
 •     3 - 19% of
                                                                 1000
       LHV biomass
                                                                 500

                                                                   0
                                                                        blokken   chips    2-3 mm   1-2 mm    < 1mm
                                                                         logs     chips   2-3 mm    1-2 mm   < 1mm


 Cost estimates
 •     Strong dependence on final particle size
 •     From 10 euro/tonne for logs, to 80 Euro/tonne for powder


               Training course on Renewable Energy                                                                    19
slide 22/34




                                                                                                                           11
              Mechanical Densification:

              Mechanical Densification increases the bulk and
              specific density
              •      Usually lower transport costs
              •      Decreases storage and handling costs
              •      Makes fuels suitable for specific applications

              Mechanical techniques:
              •    (Baling)                     •           Pelletisation
              •    Briquetting                  •           Agglomeration

              Characteristics:

                             specific density       bulk density     diameter   length
                                  kg/m3                kg/m3            cm        cm
      pellets                 1,000 - 1,300          500 -700         1 - 2.5   0.5 - 5
      briqettes                 600 - 1,200          400 - 600        3 - 10    2 - 20



                      Training course on Renewable Energy                         20
slide 23/34




              Densification (2):

              Techniques for briquetting
              •     Screw
              •     Piston

              Energy use
              •     1 - 5% of the LHV of biomass

              Cost estimates
              •     From 20 Euro/tonne to over 100 Euro/tonne




                      Training course on Renewable Energy                         21
slide 24/34




                                                                                          12
     Transport and logistics:

     Dependent on distance
     •    Road transport                          •      Rail transport
     •    Water transport

     Energy density is of major influence and depends on
     •     Moisture content             •     Bulk density

     Energy use (Road transport)
     •     Usually negligible compared to energy content of biomass
           indication 0.1 - 0.5% of LHV at 100 km

     Costs (Road transport)
     •     Rough indication: 7 - 20 Euro/tonne ds per 25 km


                   Training course on Renewable Energy                           22
 slide 25/34




 Pretreatment of lignocellulosic biomass

 Several routes under development:
   – Steam pretreatment
   – Wet oxidation
   – Mild alkaline pretreatment
   – Mild-acid/thermal pretreatment
   – Ammonia Fiber Explosion (AFEX)
   – ………..


 No cost-effective industrial pretreatment technology available
 Most commonly researched processes (mild acid hydrolysis + steam pre-
  treatment), still suffer from major drawbacks: formation of inhibitors, high
  operational temperatures and pressures, high cost etc.




                   Training course on Renewable Energy
 slide 26/34




                                                                                      13
    Ecerxise: formulaes for re-
    calculating the characteristics
      Assumption:
      W wm = 1 kg wet biomass material consists of
      Wdaf = 0,80 kg dry ash-free material
      Wash = 0,05 kg ash
      WH2O = 0,15 kg water


      Thus, W wm = W daf + W ash + W H2O



                Training course on Renewable Energy
slide 27/34




      Moisture content




                Training course on Renewable Energy
slide 28/34




                                                      14
    Ash content




              Training course on Renewable Energy
slide 29/34




    Higher heating value




              Training course on Renewable Energy
slide 30/34




                                                    15
    Higher heating value




              Training course on Renewable Energy
slide 31/34




    Lower heating value




              Training course on Renewable Energy
slide 32/34




                                                    16
    Lower heating value




                        Training course on Renewable Energy
slide 33/34




    Boiling 1 liter of water
  How much wood is needed to bring one litre of water to the boil?


  Data
  Specific heat capacity of water = 4200 J kg-1 K-1
  Mass of 1 litre of water = 1 kg
  Heat value of wood = 15 MJ kg-1
  Density of wood = 600 kg m –3
  1 cubib centimetre ( 1 cm3 = 10-6 m3)
  Calculation
  Heat energy needed to heat 1 litre of water from 20 ºC to 100 ºC = 80 x 4200 J = 336 kJ
  Heat energy released in burning 1 cm3 of wood = 15 x 600 x 10-6 MJ = 9.0 kJ
  Volume of wood required = 336 + 9.0 = 37 cm3.
  Experience suggests that on an open fire much more than two thin 20 cm sticks would be needed. But a well-
  designed stove using small pieces of wood could boil the water with as little as four times ‘input’ – an
  efficiency of 25%.



                        Training course on Renewable Energy
slide 34/34




                                                                                                               17
THANKS FOR YOUR ATTENTION

      TERIMAH KASIH




                            18

				
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