Progetto Hydrosyn by niusheng

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									      Cold model testing of an internal
        circulating fluid bed gasifier
Mr. Cesare Freda
Mr. Emanuele Fanelli



                                       ENEA
Mr. Giuseppe Canneto
Mr. Paolo Mariotti
                                                                 -Trisaia
Mr. Antonio Molino
Mr. Giacobbe Braccio
mail to cesare.freda@trisaia.enea.it

Italian National Agency for New Technology, Energy and Enviroment




                                  BIOGASTECH 9th to 11th April              1
                                  2008, Gebze/Istanbul, Turkey
             1 MWth INTERNAL CIRCULATING FLUID
                        BED GASIFIER
                                                                                                    torch




                     hopper
biomass                                             Air pre heater

                              screw
                                                                                                       Blow down
                                                 cycloon

                                                                                   Water coooler
                                                                                                             water
                                      gasifier
                                                                             scrubber
                                                                                                            Engine 160
                                                                                                              KWe
                                                                                                    Gas
                                                                                                   holder
                                      screw      screw
    Storage
                                                                     air blower     water pump
      silo               ash sand                       Fine
                                                     particulate



                                                                                                                2
              elevator
Internal circulating fluid bed reactor




            BIOGASTECH 9th to 11th April   3
            2008, Gebze/Istanbul, Turkey
Gasifier in ENEA- Trisaia
                                      CO2 (% vol)    16
                                      CO (% vol)     14
                                      CH4 (% vol)    4
                                      H2 (% vol)     7
                                      N2 (% vol)     51
                                      H2O (% vol)    8
                                      LHV (MJ/Nm3)   4
                                      Tar (g/Nm3)    10




       BIOGASTECH 9th to 11th April                       4
       2008, Gebze/Istanbul, Turkey
             Steam-oxygen gasifier
C10H8 + 10H2O = 10 CO +14 H2        (1162 KJ/mol)          Naphtalene steam reforming

C(s) + H2O = CO + H2               (+131,3 KJ/mol)         Carbon steam reforming

CO +H2O = CO2 +H2                  (- 41,23 KJ/mol)        Water gas shift reaction

CH4 + H2O = 3H2 + CO               (+206,1 KJ/mol)         Methan steam reforming


    The oxygen gasification allows to obtain a syngas with LHV of 9-11
    MJ/Nm3 suitable for application in gas turbine

    Compared to air gasification there is an increase of about 100% of LHV

    The nitrogen absence increases the gasification reaction rates
    dC/dt = K[r]a


                            BIOGASTECH 9th to 11th April                          5
                            2008, Gebze/Istanbul, Turkey
                    Dynamic similarity
Requirments are:
● geometric symilarity                                    r     fluid density

Equality of dimensionless number between                  rp particles density
 cold model and gasifier                                  dp particles diameter
                                                              g gravity acceleration
● De = r/rp                                                   m fluid viscosity
                                                              U gas velocity

● Ar = (dp3 rp ( rp – r) g)/m2                                L lenght



● Fr = U/(gL)0.5
                           BIOGASTECH 9th to 11th April                                6
                           2008, Gebze/Istanbul, Turkey
                                        Gasifier                    Cold model


                                (T= 800°C; P= 1 atm)          (T= 20°C ; P= 1 atm)
Gas density (kg/m 3 )                     0.32                         1.2
Gas viscosity (Pa*s)                     4*10^5                      1.8*10^5
Particles density (kg/m3)                 2400                        9000
Particles diameter (mm)                    500                         125
Geometrical scale ratio                                    4 : 1
Gas velocity ratio                                         2 : 1
Volumetric gas flux ratio                                  32 : 1
Times ratio                                                2 : 1




                            BIOGASTECH 9th to 11th April                         7
                            2008, Gebze/Istanbul, Turkey
       Materials for the dynamic similarity
              copper particles                           Glass spheres




                                      Coffe beans


                Cracking catalyst
Flour, talc




Dp (mm)                             122             Dp (mm)              2-2.4
rp (kg/m3)                          8822            rp (kg/m3)           2600
Umf (cm/sec)                        4.9
emf                                 0.4                                          8
              Cold model
Mechanical team
    Mr. Bellino
  Mr. Battafarano
   Mr. Petrocelli
   Mr. Corrado
    Mr. Villani




                           9
Up-flowing
chamber

                 Down-flowing
                 chamber




             >
                            10
                   Experimentals
Measure of the minimal fluidization rate

Measure of the pressure drop at the bottom of the two chambers
  at different fluidization conditions

Recirculation tests of the glass spheres at different fluidization
  conditions in the two chamber

Measure of times spent by the spheres in the up-flowing chamber

Recirculation tests of the spheres varying the height of the bottom
  orefice



                        BIOGASTECH 9th to 11th April                 11
                        2008, Gebze/Istanbul, Turkey
            Minimal fluidization rate
                  3.9

                  3.7

                  3.5
                            Packed bed

                  3.3
            KPa




                                            Umf=5.5 cm/sec
                  3.1
                                                      DP=mg/Ds
                  2.9

                  2.7                                         decreasing Uf
                                                              rising Uf
                  2.5
                        0      2    4      6          8           10          12       Umf=4.9 cm/sec
                                         cm/sec
Ergun eq.
                                            (1  e mf )2            1.75r g umf 2 (1  e mf )
g ( r s - r g )(1  e mf )  150mumf                            
                                               d e mf
                                                  2       3
                                                                                   d e mf 3
                                                                                                 12
    Pressure drop between the chambers
              1.3
                        bubbling
              1.1
                                          slugging         Udfc=1.7 Umf
              0.9
        KPa




                                                           Udfc= 1.5 Umf
              0.7


              0.5


              0.3


              0.1                                        h bed height
                    1   2          3      4          5
                                                         Ad distributor area/holes
Darton et al.                Uufc/Umf
                                        0.8
db  0.54(U  U mf )0.4(h  4 Ad ) g 0.2            ~ 7 cm                 13
                Recirculation tests
Recirculation test of the glass spheres at different fluidising condition
   in the two chambers, were executed simultaneously feeding one
hundred glass spheres in the down-flowing chamber and storing their
 recirculation time, throughout the interconnecting bottom window
  (having height of 3cm), from the down-flowing chamber to the up-
     flowing chamber, and from this latter to the first jumping the
   separating plate. When the spheres returned in the down flowing
chamber a metallic holed basket, welded to separating plate, stopped
      their run, without interfering with the fluidizing phenomena

                                             Up- flowing
                                                           Down-flowing
   spheres                                   chamber
                                                            chamber




                                                                          14
                                                Fluidizing agent
           Recirculation tests at Udfc =1.7 Umf
                                                                                           Average
                         1                                                            recirculation time
                        0.9                                                                (hours)
                        0.8                                           Uufc =3.5 Umf
                                                                                         0.29 + 0.15
                        0.7
recirculated fraction




                                                                                         0.50 + 0.26
                        0.6                                           Uufc=3Umf

                        0.5                                                              0.72 + 0.37
                                                                      Uufc=2.5Umf
                        0.4
                                                                                         1.77 + 0.99
                        0.3                                           Uufc=2Umf

                        0.2
                        0.1
                         0
                              0   1    2           3         4
                                      hours


                                              BIOGASTECH 9th to 11th April                                 15
                                              2008, Gebze/Istanbul, Turkey
Recirculation tests at Udfc =1.5 Umf
                          1
                                                                                                   Average
                                                                                              recirculation time
                         0.9
                                                                                                    (hours)
                         0.8
                                                                                                 0.19 + 0.09
 recirculated fraction




                         0.7                                                    Uufc=3.5Umf

                         0.6                                                    Uufc=3Umf        0.30 + 0.17
                         0.5
                                                                                Uufc=2.5Umf      2.35 + 1.27
                         0.4
                         0.3                                                    Uufc=2Umf
                                                                                                 2.86 + 1.53
                         0.2
                         0.1
                          0
                               0   1   2     3       4     5     6
                                           hours




                                                 BIOGASTECH 9th to 11th April                                  16
                                                 2008, Gebze/Istanbul, Turkey
     Times spent by the spheres in the up-
              flowing chamber
  Measure of the times of jumping of twenty spheres over the separating
  plate from the bottom of up-flowing chamber to the down-flowing chamber
  for different fluidising condition in the two chambers. Also in these tests a
  metallic holed basket was used to stop the spheres



All the spheres jumped the plate
                                                           Up- flowing
in every fluidizing condition!                             chamber       Down-flowing
                                                                          chamber
  Uufc     Average jumping        Average jumping
             time at Udfc = 1.7     time at Udfc = 1.5
                Umf (sec)              Umf (sec)
 2 Umf          57 + 27               117 + 42
 2.5 Umf        72 + 40               146 + 60
 3 Umf          83 + 45               190 + 91
 3.5 Umf        88 + 41               172 + 81

                                                                                    17
                                                              Fluidizing agent
Spheres path in the cold model
 Uufc          Jumping              Jumping
          time/Recirculation   time/Recirculation
                 time                 time
          at Udfc = 1.7 Umf     at Udfc = 1.5 Umf
                                                    During recirculation and jumping tests it was
2 Umf           0.01                 0.01           observed that the spheres chaotically move up
2.5 Umf         0.03                 0.02           and down in the chambers.
                                                    In down-flowing chamber they move towards the
3 Umf           0.05                 0.17           bottom of chamber driven by the particles flow,
3.5 Umf         0.08                 0.25           until they meet, during their path, a bubble that
                                                    drags them towards the top.
                                                    The spheres repeat this chaotic path until they
                                                    reach the bottom of the chamber at the depth of
                                                    the window, where pushed by the pressure drop
                                                    between the two chamber cross the window and
                                                    get into the up-flowing chamber.
                                                    In this chamber they are pushed towards the top
                                                    surface of the bed because of their lower density
                                                    compared to the bed density and because of the
                                                    ascending path of the bubbles.
                                                    A little fraction of spheres stops in down-flowing
                                                    chamber in bed fluidized places.




                                                                                                  18
                     Build-up gasifier
To improve the recirculation of spheres it will be given to their path a major
horizontal component tilting the base of down flowing chamber




         Uufc > Udfc                                   Uufc > Udfc
                            BIOGASTECH 9th to 11th April                    19
                            2008, Gebze/Istanbul, Turkey
Recirculation tests varying bottom
           window area
  One hundred spheres were fed in down flowing chamber and
  their recircutation times were stored at different height of the
      bottom window (3 , 5 and 7 cm) maintaining the same
  condition of fluidisation in the two chambers (Uufc= 2.5 Umf,
                          Udfc=1.7 Umf).


                             1
                            0.9                                                 Average
                                                                           recirculation time
                            0.8
                                                                                (hours)
    recirculated fraction




                            0.7
                            0.6                                               0.72 + 0.37
                                                                    3 cm
                            0.5                                               0.65 + 0.34
                                                                    5 cm
                            0.4                                               0.20 + 0.12
                                                                    7 cm
                            0.3
                            0.2
                            0.1
                             0
                                  0   0.5   1       1.5   2   2.5
                                                                                                20
                                                hours
                    Theoretical bed particles flow through an orefice
                                                                                      C = particle discharge coefficient
Ws = Cso ecfa2.35*(2rdfcDP)0.5 Kuramoto, kunii eq.      so

                                                       e = vacuum fraction
Cso = 0.1
                                                       d = bubble fraction
eufc = dufc  (1 dufc) emf
                                                       r  density
rdfc= r (1 edfc)
edfc = ddfc  (1 ddfc) emf                  Theoretical bed particles periods at
                                                                    different fliudizing condition
                        Udfc=1.7 Umf        Udfc=1.5 Umf

               80                                                                  Udfc = 1.7 Umf     Udfc =1.5 Umf
                                                                         500
               70

               60
                                                                         450
                                                                         400
 Kg/(m2*sec)




               50




                                                               seconds
               40                                                        350
               30                                                        300
               20                                                        250
               10
                                                                         200
               0
                    1             2                3       4
                                                                         150
                                                                               1           2              3           4
                                       Uufc/Um f
                                                                                               Uufc/Umf

                                                                                                                          21
                       Conclusions
A minimal fluidization rate of 5.5 cm/sec was measured for the copper
powder in the cold model
A slugging regime was observed in up-flowing chamber at U ~ 4 Umf
To recirculate spheres it is necessary that Udfc > 1.5 Umf
At Udfc =1.5 Umf , the recirculation was satisfactory (>90 %), at Uufb > 3 Umf;
at Udfc =1.7 Umf the recirculation was satisfactory yet at Uufb > 2.5 Umf ,
anyway both at Udfc =1.5 Umf both at Udfc =1.7 Umf it never was 100%
The spheres spend most time in the down-flowing chamber, up to 99% of
recirculation time, where a little fraction stops in bad fluidized zones,
instead very quickly cross the up-flowing chamber
The recirculation of spheres is helped by the increase of area of the
bottom orefice



                                                                                  22

								
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