No Slide Title by HC120809095355

VIEWS: 7 PAGES: 15

									Department of Chemical & Process Engineering




                                               The high pressure interactions of coal with CO2
                                               Implications for CO2 disposal and CH4 displacement from coal seams




                                                                           By :
                                                                    Mojtaba Mirzaeian


                                                             Supervisor: Professor Peter.J.Hall
Department of Chemical & Process Engineering   INTRODUCTION




                                                  Coal is the most abundant fossil fuel and the world depends
                                                   heavily on it and will continue to do so for years to come.

                                                  There is overwhelming evidence for a gradual build up of
                                                   atmospheric CO2 levels and strong evidence that this is
                                                   contributing to global warming.


                                                  Unminable deep coal seams are attractive as options for
                                                   the permanent sequestration of CO2
Department of Chemical & Process Engineering    OBJECTIVES




                                                Which coals are most effective for sequestration?


                                                Field tests are expensive and a set of laboratory tests
                                                    to screen coals is needed to:

                                                   Determine the irreversible storage capacity.
                                                   Measure how tightly bound CO2 is to different coals.
                                                  Determine the physical state of CO2 in coal.
                                                 Experimental


                                                A variety of Experimental techniques have been used :
Department of Chemical & Process Engineering




                                                       Differential scanning calorimetry
                                                         Phase change in high pressure CO2
                                                         Irreversible sorption capacity
                                                         Thermodynamics

                                                      Temperature programmed desorption
                                                            Binding energy of CO2

                                                     Small angle neutron scattering
                                                            Physical state/location of CO2 in structure
                                                  DSC results

                                               Glass transition in coal:
Department of Chemical & Process Engineering




                                                                             0                                                               0
                                                                                                                                    exo
                                                                           -0.5

                                                                                                                                    endo
                                                                            -1                                                               -0.5




                                                                                                                                                    H eat flow (W /g )
                                                       H eat flow (W /g)




                                                                           -1.5


                                                                            -2                                                               -1

                                                                                   third s can
                                                                                                              first s can
                                                                           -2.5


                                                                            -3                                                               -1.5


                                                                           -3.5                  s econd s can


                                                                            -4                                                               -2
                                                                                  40   60        80     100      120    140   160    180   200
                                                                                                                        o
                                                                                                      T em pera ture ( C )


                                                      D SC for W yodak coal (held in 30 bar C O atmospher for 24h )
                                                                                                                              2
                                               DSC results

                                                                           3
                                                                                                                                      exo
Department of Chemical & Process Engineering




                                                                           2
                                                                                                                                     endo



                                                       H eat flow (W /g)
                                                                           1



                                                                                     30 bar
                                                                           0

                                                                                     20 b ar
                                                                           -1        10 bar

                                                                                     5 b ar

                                                                           -2




                                                                           -3
                                                                                40    60       80       100    120       140   160   180    200
                                                                                                                     o
                                                                                                    T em p era ture ( C )


                                                   The dependence of glass transition tem perature
                                                         of W yadak on the pressure of CO
                                                                                                                                             2
Department of Chemical & Process Engineering   DSC results



                                               Evidence for plasticisation of Coal by CO2.


                                                                               second scan                     third scan
                                                CO2 Pressure (bar)     Tg (oC)       Cp (J/g K)     Tg (oC)        Cp (J/g K)
                                                        0               121.1           0.12           121.6                0.16
                                                        5               86.6            0.14           81.7                 0.12
                                                        10              83.2            0.21           78.2                 0.2
                                                        20              82.4             0.2           77.8                 0.17
                                                        30              81.1            0.18           75.7                 0.14
                                                The glass transition characteristics of Wyodak at different CO2 pressures
                                                                            DSC results


                                                                            Irreversible strong interactions of coal with CO2
Department of Chemical & Process Engineering




                                                                       1                                                                                 3
                                                                                                                     exo                                                                               e xo

                                                                     0.5                                                                                 2
                                                                                                                     en do                                                                             e nd o
                                               H eat flo w (W /g )




                                                                                                                                   H eat flo w (W /g )
                                                                       0
                                                                                                                                                         1


                                                                     -0.5
                                                                                                                                                         0

                                                                      -1

                                                                                                                                                         -1
                                                                     -1.5
                                                                              ____ First scan
                                                                              ____ Second scan                                                           -2
                                                                                                                                                              ____ First scan
                                                                      -2                                                                                      ____ Second scan
                                                                              ____ Third scan
                                                                                                                                                              ____ Third scan
                                                                     -2.5                                                                                -3
                                                                            -50    0       50       100        150           200                              -50    0          50       100     150            200
                                                                                                          o                                                                               o
                                                                                       T em p eratu re ( C )                                                             T em p eratu re ( C )



                                                                        D SC for W yodak in N atm osphere                                   DS C for W yodak in CO atm osphere
                                                                                                          2                                                                                2
                                                 DSC results


                                                      Thermodynamic of coal/CO2 interactions
Department of Chemical & Process Engineering




                                                                         first scan            second scan                  third scan
                                                    Coal        H (W/g)      Peak (oC)   H (W/g)    Peak (oC)   H (W/g)       Peak (oC)

                                                North Dakota     23.46          -36.6       23.02       -12.1       23.17          -12.1
                                                  Wyodak         27.40          -39.9       20.6          -5        18.72           -3.8
                                                 Illinois #6     20.51          -36.4       11.58        -7.3       11.28           -6.2
                                                Pittsburgh #8    10.23          -35.4       6.78         0.7         6.79           1.9
                                               Characteristics of exothermic peaks associated with the adsorption of CO2 on coal samples
                                                TPD-MS results                                                                5 10
                                                                                                                                     -11




                                                                                                   Desorption rate (arb.un)
                                                                                                                                     -11                     Sam ple load ed w ith 24 b ar C O for 25h.
                                                                                                                              4 10                                                                                                              2



                                                                                                                                     -11
                                                                                                                              3 10
                                               CO2 desorption from                                                                   -11
                                                                                                                              2 10
Department of Chemical & Process Engineering




                                               coal is an activated                                                           1 10
                                                                                                                                     -11

                                                                                                                                                       F resh sam ple

                                               process.                                                                               0
                                                                                                                                           300         350                   400                                        450                    500                 550
                                                                                                                                                                                     T em peratu re (K)


                                                                                                                                           TPD-M S spectra of CO from Pittsburgh#8
                                                                                                                                                                                                                       2



                                                                                                                              -11




                                                                                                                                                                 D esorption rate (arb.un.)
                                                                                                   8 10                                                                                       8 10
                                                                                                                                                                                                      - 11


                                                                                                                                                                                                               E = 11202 cal/mole




                                                                      D esorption rate (arb.un.)
                                                                                                                                                                                              6 10
                                                                                                                                                                                                      - 11         d                             R edh ead Eq u .
                                                                                                                                                                                                               ß = 20 ° K /min
                                                                                                                                                                                                      - 11                          -1
                                                                                                                              -11
                                                                                                                                                                                              4 10             K =105378.86 S                       Ex p. Data
                                                                                                                                                                                                                   d
                                                                                                   6 10
                                                                                                                                                                                                      - 11
                                                                                                                                                                                              2 10



                                               CO2 desorption from                                                            -11
                                                                                                                                                                                                       0
                                                                                                                                                                                                                                                     R esid u al


                                                                                                   4 10                                                                                       -2 10
                                                                                                                                                                                                      - 11


                                                                                                                                                                                                             300       310    320        330        340     350     360


                                               coal follows a first                                                                                                                                                          T em pe ratu re (°K)


                                                                                                                              -11
                                                                                                   2 10                                                                                                        Exp. D ata
                                               order kinetic model.                                                                              Redhea d Equ.

                                                                                                                               0
                                                                                                                                    300               350                                      400                             450                          500
                                                                                                                                                                                              Tem perature (°K )
                                                                                                                                            TP D -M S spectrum o f C O ad sorbed on
                                                                                                                                                                                                                              2

                                                                                                                                            P ittsburgh#8 co al at 15 bar for 20 ho urs
Department of Chemical & Process Engineering   TPD-MS results




                                               Desorption characteristics of CO2 from Pittsburgh #8 coal



                                                 CO2 Pressure (bar)         Edes (Kcal/mol)           Correlation factor
                                                         5                      10.271                      0.908
                                                        10                      11.094                      0.941
                                                        15                      11.202                      0.996
                                                        20                      11.190                      0.844
                                                    Binding energy of CO2 for Pittsburgh #8 coal at various pressures
                                                                                                                                    1000
                                                  SANS results




                                                                                       )
                                                                                      -1
                                                                                       S cattering cross section (cm
                                                                                                                                                                                              0 bar CO2
                                                                                                                                             100
                                                                                                                                                                                              25bar CO2
                                                                                                                                                                                              32bar CO2
                                                                                                                                              10

                                               Decrease in scattering intensities                                                              1
Department of Chemical & Process Engineering




                                                after loading with CO2 gives
                                                                                                                                              0.1
                                               evidence that CO2 can access to
                                                                                                                                             0.01
                                               entire pores in coal.                                                                                0.01                          0.1                             1
                                                                                                                                                                                              o -1
                                                                                                                                                           S cattering w ave vecto r q (A            )

                                                                                     SANS on Illinois #6 at various CO pressures for 2h.
                                                                                                                                                                                        2



                                                                                                                                             1000




                                                                                                             )
                                                                                                -1
                                                                                                                                                                                        35 bar CO2 10 min




                                                                                                             S cattering cross section (cm
                                                                                                                                              100                                       35   bar   CO2   20 min
                                                                                                                                                                                        35   bar   CO2   30 min
                                                                                                                                                                                        35   bar   CO2   1 hr
                                                                                                                                               10                                       35   bar   CO2   1.5 hr
                                                                                                                                                                                        35   bar   CO2   2 hrs
                                               No change in scattering intensities
                                                                                                                                                1
                                               with time shows that CO2 can not
                                                                                                                                              0.1
                                               diffuse through the coal matrix in
                                               the time scale of experiment.                                                                 0.01
                                                                                                                                                    0.01                         0.1                                  1
                                                                                                                                                                                           o -1
                                                                                                                                                              Scattering w ave vector q (A      )


                                                                                     SANS on Illinois #6 at 35 bar CO at various tim es
                                                                                                                                                                                         2
                                                  Conclusions

                                                Coal/CO2 interactions are strong and irreversible.
Department of Chemical & Process Engineering




                                                The values of energy of Coal/CO2 interactions decrease with
                                                 increase in coal rank suggesting low rank coals are better
                                                 for CO2 sequestration.

                                                CO2 causes significant plasticisation effect in coal and
                                                 changes coal structure.

                                                CO2 desorption from coal is an activated process and
                                                 follows a first order kinetic model.

                                                Coals offer an attractive means for the long term
                                                 sequestration of CO2 .
                                                      Thank-You
Department of Chemical & Process Engineering




                                                           &

                                                      Questions



                                               mojtaba.mirzaeian@strath.ac.uk
Department of Chemical & Process Engineering

								
To top