1. Development of a Laboratory ScaleReactor Facility to
Generate HydrogenRich Syngas via ThermochemicalEnergy
ConversionMandeep SharmaMasters Candidate, Mechanical
EngineeringLouisiana State University
2. 2Outline Objective Background Information Conical Spouted
Bed (CSB) Reactor Thermochemical Energy conversion Cold Flow
Hydrodynamic Studies Thermodynamic Equilibrium Analysis
Experimental Results for Homogeneous Fuel Reforming Preliminary
Study for Heterogeneous Fuel Reforming Conclusions Recommendations
and Future Work Acknowledgement
3. 3Objective To develop a laboratory scale CSB reactor
facility for the purpose of producing H2 rich synthesis gas from
sustainable hydrocarbon fuels and various biomass wastes* via
thermochemical routes of gasification /reforming.H2 rich synthesis
gas (Syngas) mainly consists of H2 and CO, and traces of CO2, H2O
and lower hydrocarbons. Clean H2 rich syngas has applications in
fuel cells, gas turbines and engines for clean and efficient power
generation. Validation tests with Propane , Long term biomass waste
: Glycerol*
4. 4Fuel SelectionGlycerol (C3H8O3): (long term fuel) byproduct
of biodiesel production, has been considered an excellent candidate
for H2 production. For every 9 kg of biodiesel produced, about 1 kg
of a crude glycerol by-product is formed. Only in the US, biodiesel
production has increased dramatically from 500,000 gallons in 1999
to 70 million gallons in 2005 [1].Propane (C3H8): (used in present
study) High potential as hydrogen carrier for future power
applications [2]. More stored energy per unit volume and thus
releases more heat compared to methane. higher boiling point (-42
C) than methane (-164 C), so it can be liquefied even at low
pressures i.e. at 9 bar, and hence is easier to store and
transport. [1]. National Biodiesel Board, 2006. [2]. G. Kolb, R.
Zapf, V Hessel, and H. Lowe. Propane steam reforming in
micro-channels: Results from catalyst screening . and optimization.
Applied Catalysis A: General, 277:155166, 2004.
5. 5Background Introduction
6. 6Conical Spouted Bed (CSB) Reactor Mathur and Gishler
initially introduced spouted beds in 1954 as an alternative method
for drying moist wheat grains. Recent applications include
pyrolysis of solid wastes, e.g. rice husk, sawdust, plastic wastes,
scrap tires, etc. Potential for syngas generation from biomass
wastes (glycerol) and hydrocarbon fuels.Advantages of CSB reactor
Perfect mixing Very efficient heat transfer because of cyclic
movement Very short residence time Suitable for sticky, moist,
irregular shaped bed material
7. 7 CSB Concept Contacting of solids with fluid by injecting a
steady axial jet of fluidizing medium (air/N2/steam).Schematic of
CSB actual reactor model Spouting behavior of CSB cold flow model
The jet entrains particles, which are carried through the central
spout, forming a fountain before being deposited in an annular
region. This mechanism creates a regular circulation pattern of
particles through the bed.
8. 8Thermochemical ConversionAt operating conditions, chemical
reaction occurs that producesynthesis gas or syngas , a mixture of
predominantly H2 and CO.
9. 9 ContdA thermochemical conversion of hydrocarbon fuel,
propane,into syngas involves four main types of fuel reforming
routes:Dry Reforming (DR): (endothermic)fuel(C3H8) a H2 + other HCs
(...CH4, C2H2, C2H6, etc.) + c CPartial Oxidation (POX):
(exothermic)C3H8 + 3O2 + nN2 9/4 H2 + CO + CO2 + CH4 + 3/2H2O + 3n
N2Steam Reforming (SR): (endothermic)C3H8 + 3H2O 7 H2 +
3COAutothermal Reforming (ATR): (endoth., exoth.,
thermo-neutral)C3H8 + 3O2 +3H2O + nN2 CH4 + CO + CO2 + 2H2 + 3H2O +
3n N2
10. 10Cold Flow Hydrodynamic Study
11. 11 Cold flow studies were conducted to establish stable
spouting range. Stable spouting occurs over a specific range of gas
velocity called min. spouting velocity (ums). Different Spouting
RegimesKnowledge of (ums) is of fundamental importance in the
design and operation ofspouted beds. ums is the minimum gas
velocity needed to maintain spoutingoperation.
12. 12CSB Cold Flow SetupExperiments were carried out at
atmosphericconditions using Alumina powder (=3960 Kg/m3)as bed
material and air as spouting gas. Schematic of experimental set-up:
(1) air manifold, (2) air filter (3), control valve, (4/5)
rotameters, (6) air inlet pipe, (7/8) pressure taps at bed inlet
and outlet, (9) U-tube manometer, (10) conical contactor, (11) bed
material, and (12) cylindrical column.
13. 13Experiment Summary of operating parameters tested * **
Indicates the best set of testing parameters which shows uniform
cyclic behavior of CSB.
14. 14Effect of System Parameters on (ums)o Effect of different
Ho, Do and dp on (ums)o
15. 15 Evaluation of all existing correlations for (ums)o
Source Correlation Eqn.Markowski (1)(1983)Choi (1992) (2)Gorshtein
(3)(1964)Mukhlenov (4)(1965)Tsvik (1967) (5)Olazar (1992) (6)Olazar
(1996) (7)Bi (1997) (for (8)Db/Do 1.66) They used CSBs which were
significantly larger than the model investigated in present study.
In theory, predictions should match experimental data, i.e. the
best performing correlations will align with the diagonal
line.
16. 16Evaluation of Correlations (contd)Correlations
predictions comparison with experimental resultsfor a particular
set of operating parameters
17. 17Poor performance of correlations:
18. 18Proposed Correlation Proposed correlation shows excellent
agreement with experiments 75 o Present Study, 60 cone angle 70 +
16.3 % 0.483 mm dp, 6.350 mm Do 65 0.483 mm dp, 4.572 mm Do 60
0.483 mm dp, 3.302 mm Do 55 1.092 mm dp, 6.350 mm Do Predicted
(ums)o, m/s 50 1.092 mm dp, 4.572 mm Do - 17.15 % 45 1.092 mm dp,
3.302 mm Do 40 35 30 25 20 15 10 5 0 0 5 10 15 20 25 30 35 40 45 50
55 60 65 70 75 Experimental (ums)o, m/s
19. 19Summary (Cold Flow Studies) Available correlations for
calculating min. spouting velocity have shortcomings for
small-sized laboratory scale CSB studies. Developed Simple
empirical correlation for (ums)o which showed excellent agreement
with experimental findings. Cold flow hydrodynamic study provides a
foundation for design of hot flow CSB reactor facility. Hot flow
tests are also needed to carefully examine the stable spouting at
high temperatures.
20. 20Thermodynamic Equilibrium Analysis
21. 21 I. Thermodynamic Equilibrium Analysis Used as reference
tool to qualitatively choose operating conditions such as pressure,
temperature and reactants feed ratio irrespective of reaction
kinetics, reactor design and operation. Used for assessment of
homogeneous (non-catalytic) DR, POX, SR and ATR of propane.
Canteras chemical equilibrium solver (Goodwin 2009), which involves
nonstoichiometric approach (element potential method), is used.
GRI-Mech 3.0*, (53 species) and solid carbon databases are used to
evaluate the thermodynamic properties of the chemical species
considered in the model. The initial amount of propane is assumed
to be 1 mol.*G. P. Smith, D. M. Golden, M. Frenklach, N. W.
Moriarty, B. Eiteneer, M. Goldenberg, C. T. Bowman, R. K. Hanson,
S. Song, Jr. W. C. Gardiner, V. V. Lissianski, and Z. Qin. GRI-Mech
3.0. http://www.me.berkeley.edu/gri_mech/version30/, 1999.
22. 22 Pressure and Temperature Selection Low pressures favors
H2 production. 1 atm pressure is selected throughout present study.
High pressure experiments can be expensive and dangerous.
23. 23Reactants Feed Ratio Selectiona) Homogeneous DR: 2 cases
of CPRs 10 and 24 are takenPropane cracking reactions: C3H8 4H2 +
3C and CH4 2H2 + C
25. 25Ternary Diagram ContdA ternary system diagram, also known
as Gibbs triangle,graphically represents the ratios of three
variables aspositions in an equilateral triangle. Three variables
(concentrations here) conveniently plotted in a two- dimensional
graph. Any point within this triangle represents the overall
composition (100%) of a ternary system at a fixed temperature and
pressure.
26. 26Ternary Diagram Contd 2. 25% A, 40% B, 35% C and their
sum is 100%. *In present study, ternary system diagram is used as a
convenient way to decide an optimum ratios of reactants mixture for
SR, POX and ATR.
27. 27Homogeneous POX Carbon Mole Fraction T = Tad - TR
28. 28Homogeneous POX Contd H2 Mole Fraction CO Mole
Fraction
29. 29Homogeneous SR Carbon Mole Fraction T = Tad - TR
30. 30Homogeneous SR Contd H2 Mole Fraction CO Mole
Fraction
31. 31Homogeneous ATR Carbon Mole Fraction T = Tad - TR
32. 32Homogeneous ATR Contd H2 Mole Fraction CO Mole
Fraction
33. 33 Operating Parameters Selection SummaryCPR : Carrier to
Propane gas ratio, APR : Air to Propane gas ratio, WPR : Water to
Propane ratio, : Equivalence ratio = (F/A) / (F/A)stoic
34. 34Homogeneous Reforming Comparisons H2 the order of H2
production: ATR >SR >POX >DR
35. 35 Contd CO
36. 36 Contd C carbon formation increasing order: ATR<
SR< POX< DR
37. 37 Efficiencies Comparisons at 1 atm and 1000C*Reactants
feed ratios are discussed in slide 32.
38. 38Summary (Thermodynamic Equilibrium Analysis) Lower
pressure favors hydrogen production. Temperature range selected for
performing homogeneous DR, POX, SR and ATR is 600 ~ 1000C. Used as
a reference tool to select optimum reactants feed ratios for carbon
free reactions without harming the reaction system. A homogeneous
ATR is most efficient to produce. Qualitatively choose operating
conditions such as pressure, temperature, reactants feed ratios
irrespective of reactor design, reaction kinetics and operation. It
uses idealized thermodynamic state with maximum entropy which
requires infinite residence time for all chemical reactions to
complete, which in actual practice it is not feasible. Therefore,
experimental tests for homogeneous processes are required for
quantitative analysis.
40. 40 Experimental Setup Schematic Diagram*A simpler plug flow
reactor system in experimental investigations is meant toprovide
preliminary results that are used to evaluate different
reformingapproaches, which will eventually be applied in a CSB
reactor in the third phase
41. 41Results: I. Exhaust Gas Composition a) Homogeneous
DR:
42. 42 Contdb) Homogeneous POX:
43. 43 Contdc) Homogeneous SR:
44. 44 Contdd) Homogeneous ATR:
45. 45II. Homogeneous Processes Performance Evaluation a) C3H8
Conversion Efficiency:
46. 46 Contdb) H2 Production Efficiency: Thermodynamic
Equilibrium Experiment
47. 47 Contdb) CO Production Efficiency: Thermodynamic
Equilibrium Experiment
48. 48Summary (Experiments) ATR is most suitable whereas DR is
least suitable for not only producing hydrogen rich syngas but also
in terms of clean and carbon free process. The experiment tests,
however, provides similar trends compared to thermodynamic
equilibrium in terms of major syngas species, propane conversion,
H2 and CO production efficiencies. The difference between
theoretical qualitative predictions and experiment quantitative
results is attributed to inclusion of solid carbon in product
stream in the thermodynamic equilibrium analysis whereas the carbon
in actual tests is converted to ethane and acetylene. Homogeneous
reforming processes requires temperature more than 700C to break
down into lower hydrocarbon species if no catalysts are used.
50. 50Literature Review a) Catalyst Selection Very limited
resources are available for non-noble metal based catalysts
favoring heterogeneous fuel reforming. In literature, the order of
catalysts (both noble and non-noble) reactivity for DR and SR of
propane is Ru > Rh > Ni > Pt > Pd. Due to low cost and
ready availability of nickel (Ni) metal, the supported Ni
metal-based catalyst is the preferred choice for the present
investigation of heterogeneous fuel reforming. Bare Ni is not
sufficient as a catalyst for fuel reforming applications, because
of its deactivation and coke formation issues at high
temperatures.
51. 51 Contd b) Catalyst Support Selection Catalyst support is
a material, usually a solid with a high surface area, to which the
catalyst is affixed. Typically supports are inert which include
various kinds of carbon, alumina, and silica. In the present study,
alumina (Al2O3) is selected as catalyst support, since it causes
higher syngas production as compared to other supports i.e. MgO ,
CaO etc. c) Additive Promoter Selection Ni/Al2O3 catalysts
performance in terms of its reactivity, stability and coke
resistance can be improved either by making strong metal- support
interaction, addition of CeO2 into Ni/support catalyst, or by using
smaller Ni particle size and its higher dispersion.
52. 52 Contd Nickelous aluminum oxide (Ni/Al2O3) is selected as
non-noble base catalyst than precious metals whereas cerium oxide
(CeO2) is selected as an additive promoter in the present thesis.
For preliminary studies, 15 wt% cerium oxide doped in 10 wt%
Ni/Al2O3 catalyst is used for heterogeneous ATR. some of the
results appeared as expected, but a significant different behavior
of heterog- eneous ATR than homogeneous cases is observed. Reason?
Need more study on it. Can improve? Yes, by testing Tested under
same operating conditions as were used in homogeneous ATR.
catalysts with multiple compositions.
53. 53Thesis Conclusions
54. 54 The thesis provides data needed for development of
conical spouted bed (CSB) reactor for the purpose of producing
hydrogen rich syngas. Cold flow hydrodynamic study provides a
foundation for design of hot flow CSB reactor facility. Developed
Simple empirical correlation for (ums)o showed excellent agreement
with experimental findings. The selection of operating conditions
for experiments reactants feed ratio, pressure and temperature is
guided by results from thermodynamic equilibrium (TE). TE and
experimental results reveal that the homogeneous ATR is most
efficient and DR is least efficient in terms of syngas production.
The difference between theoretical qualitative predictions and
experiment quantitative results is attributed to inclusion of solid
carbon in product stream in TE whereas the carbon in actual tests
is converted to ethane and acetylene.
55. 55 Propane in homogeneous reforming processes requires
temperature more than 700C to break down into lower hydrocarbon
species if no catalysts are used.
56. 56Recommendations and Future Work
57. 57Cold Flow Hydrodynamic Studies:Additional tests using
varying particle densities and cone angles arerequired for the
development of a universally applicable correlation for Ums.A data
reduction in pressure drop and flow rates measurements can
beimproved by using DAQ system.Heterogeneous Reforming:More
catalyst samples of different CeO2 and Ni loadings on Al2O3
metalsupport need to be prepared and tested to access the
detailedcharacterization of catalysts performance for heterogeneous
DR, POX, SRand ATR processes.Construction of Bench Top CSB
reactor:third phase of CSB reactor facility eventually involves the
construction of abench top laboratory scale CSB for the follow-up
research where similartests need to be performed.
58. 58Construction of Bench Top CSB reactor Proposed geometry
for CSB reactor system
59. 59Questions?Acknowledgements:1. Advisor, Dr. Ingmar Schoegl
and Committee, Dr. Ram Devireddy and Dr. Ying Wang2. Louisiana
State University Council on Research Faculty Research Grant
Program3. Research Group: Avishek, Mohsen, Khurshida, Joseph,
Matthew and Joe4. Zianqing Zhao, graduate student of Dr. Wangs
research group5. Friends and Family
60. 60Backup Slides
61. 61Cold Flow Studies
62. 62Evolution of Spouting regimes
63. 63 Evaluation of CorrelationsFor one particular data set -
e.g. 60, 483 m, 6.35 mm Do best performing correlations align with
the diagonal line
64. 64Evaluation of Correlations contd Comparison of Gorshtein
correlation for all data sets
65. 65Evaluation of Correlations contd Comparison of Mukhlenov
correlation for all data sets
66. 66Evaluation of Correlations contd Comparison of Tsvik
correlation for all data sets
67. 67Evaluation of Correlations contd Comparison of Choi
correlation for all data sets
68. 68Pressure Drop Measurements Effects of Ho and Do on stable
pressure drops and maximum pressure drops
69. 69Thermodynamic Equilibrium Studies
70. 70Homogeneous DR: (Thermodynamic Equilibrium) Product
Species Mole Fractions
71. 71Homogeneous POX: (Thermodynamic Equilibrium) Product
Species Mole Fractions
72. 72Homogeneous SR: (Thermodynamic Equilibrium) Product
Species Mole Fractions
73. 73Homogeneous ATR: (Thermodynamic Equilibrium) Product
Species Mole Fractions
74. 74ADVANTAGES OF FLUIDIZED BED Rapid mixing of solids,
uniform temperature andconcentrations. Applicable for large or
small scale operations. Heat and mass transfer rates between gas
and particlesare high as compared to other modes of contacting.
There is no moving part and hence a fluidized bed reactoris not
mechanically agitated reactor. So, maintenance cost can be low. The
reactor is mounted vertically and save space.The beds have a static
pressure head due to gravity, given by 0gh,