MSc thesis defense presentation at Frank Walk Room, LSU

Development of a Laboratory Scale
Reactor Facility to Generate Hydrogen
Rich Syngas via Thermochemical
Energy Conversion
Mandeep Sharma
Masters Candidate, Mechanical Engineering
Louisiana State University

2

Outline
• 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

Objective
 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

Fuel Selection
Glycerol (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 ºC) than methane (-164 ºC), 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, 277:155–166, 2004.

6

Conical 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

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

Thermochemical Conversion
At operating conditions, chemical reaction occurs that produce
synthesis gas or “syngas” , a mixture of predominantly H2 and CO.

9

…Cont’d
A 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 HC‟s (...CH4, C2H2, C2H6, etc.) + c C

Partial Oxidation (POX): (exothermic)

C3H8 + 3O2 + nN2 ⇒ 9/4 H2 + CO + CO2 + CH4 + 3/2H2O + 3n N2

Steam Reforming (SR): (endothermic)
C3H8 + 3H2O ⇒ 7 H2 + 3CO

Autothermal Reforming (ATR): (endoth., exoth., thermo-neutral)
C3H8 + 3O2 +3H2O + nN2 ⇒ CH4 + CO + CO2 + 2H2 + 3H2O + 3n N2

10

Cold Flow Hydrodynamic Study

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 Regimes

Knowledge of (ums) is of fundamental importance in the design and operation of
spouted beds. ums is the minimum gas velocity needed to maintain spouting
operation.

12

CSB Cold Flow Setup
Experiments were carried out at atmospheric
conditions using Alumina powder (ρ=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

Experiment

Summary of operating parameters tested

*

*

* Indicates the best set of testing parameters which shows uniform cyclic
behavior of CSB.

14

Effect of System Parameters on (ums)o

Effect of different Ho, Do and dp on (ums)o

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

…Evaluation of Correlations (cont’d)
Correlations‟ predictions comparison with experimental results
for a particular set of operating parameters

17

Poor performance of correlations:

18

Proposed 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

Summary (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

Thermodynamic Equilibrium Analysis

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.
• Cantera’s 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

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

Reactants Feed Ratio Selection
a) Homogeneous DR: 2 cases of CPRs 10 and 24 are taken

Propane cracking reactions:
C3H8 ⇒ 4H2 + 3C and CH4 ⇒ 2H2 + C

24

Reactants Feed Ratio Selection …Cont’d

a) Homogeneous POX:

Propane + Air + Nitrogen

b) Homogeneous SR:

Propane + Steam + Nitrogen

c) Homogeneous ATR:

Propane + Steam + (Air + Nitrogen)

Ternary Diagram?

25

Ternary Diagram …Cont’d

A ternary system diagram, also known as Gibbs triangle,
graphically represents the ratios of three variables as
positions 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

Ternary Diagram …Cont’d

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

Homogeneous POX

Carbon Mole Fraction ΔT = Tad - TR

28

Homogeneous POX …Cont’d

H2 Mole Fraction CO Mole Fraction

29

Homogeneous SR


30

Homogeneous SR …Cont’d


31

Homogeneous ATR


32

Homogeneous ATR …Cont’d


33

Operating Parameters Selection Summary

CPR : Carrier to Propane gas ratio, APR : Air to Propane gas ratio, WPR : Water to Propane ratio,
φ : Equivalence ratio = (F/A) / (F/A)stoic

34

Homogeneous Reforming Comparisons
• ηH2

the order of H2 production: ATR >SR >POX >DR

35

…Cont’d
• ηCO

36

…Cont’d
• ηC

carbon formation increasing order: ATR< SR< POX< DR

37

Efficiencies Comparisons at 1 atm and 1000°C

*Reactants feed ratios are discussed in slide 32.

38

Summary (Thermodynamic Equilibrium Analysis)
• Lower pressure favors hydrogen production. Temperature range
selected for performing homogeneous DR, POX, SR and ATR is 600
~ 1000°C.
• 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.

39

Experimental Results for
Homogeneous Fuel Reforming

40

Experimental Setup

Schematic Diagram
*A simpler plug flow reactor system in experimental investigations is meant to
provide preliminary results that are used to evaluate different reforming
approaches, which will eventually be applied in a CSB reactor in the third phase

41

Results:
I. Exhaust Gas Composition
a) Homogeneous DR:

42

…Cont’d
b) Homogeneous POX:

43

…Cont’d
c) Homogeneous SR:

44

…Cont’d
d) Homogeneous ATR:

45

II. Homogeneous Processes Performance Evaluation
a) C3H8 Conversion Efficiency:

46

…Cont’d
b) H2 Production Efficiency:

Thermodynamic Equilibrium Experiment

47

…Cont’d
b) CO Production Efficiency:

Thermodynamic Equilibrium Experiment

48

Summary (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
700°C to break down into lower hydrocarbon species if no catalysts
are used.

49

Preliminary Studies for
Heterogeneous Fuel Reforming

50

Literature 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

…Cont’d
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

…Cont’d

• 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.

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

• Propane in homogeneous reforming processes requires temperature
more than 700°C to break down into lower hydrocarbon species if no
catalysts are used.

56

Recommendations and Future Work

57

Cold Flow Hydrodynamic Studies:
Additional tests using varying particle densities and cone angles are
required for the development of a universally applicable correlation for Ums.
A data reduction in pressure drop and flow rates measurements can be
improved by using DAQ system.

Heterogeneous Reforming:
More catalyst samples of different CeO2 and Ni loadings on Al2O3 metal
support need to be prepared and tested to access the detailed
characterization of catalysts performance for heterogeneous DR, POX, SR
and ATR processes.

Construction of Bench Top CSB reactor:
third phase of CSB reactor facility eventually involves the construction of a
bench top laboratory scale CSB for the follow-up research where similar
tests need to be performed.

58

…Construction of Bench Top CSB reactor

Proposed geometry for CSB reactor system

59

Questions?

Acknowledgements:

1. Advisor, Dr. Ingmar Schoegl and Committee, Dr. Ram Devireddy and Dr. Ying
Wang
2. Louisiana State University Council on Research Faculty Research Grant
Program
3. Research Group: Avishek, Mohsen, Khurshida, Joseph, Matthew and Joe
4. Zianqing Zhao, graduate student of Dr. Wang‟s research group
5. Friends and Family

62

Evolution of Spouting regimes

63

Evaluation of Correlations

For one particular data set - e.g. 60°, 483 µm, 6.35 mm Do

best performing correlations align with the
diagonal line

64

Evaluation of Correlations …cont’d
Comparison of Gorshtein correlation for all data sets

65

Comparison of Mukhlenov correlation for all data sets

66


Comparison of Tsvik correlation for all data sets

67


Comparison of Choi correlation for all data sets

68

Pressure Drop Measurements

Effects of Ho and Do on stable pressure drops and
maximum pressure drops

69

Thermodynamic Equilibrium Studies

70

Homogeneous DR: (Thermodynamic Equilibrium)
Product Species Mole Fractions

71

Homogeneous POX: (Thermodynamic Equilibrium)

72

Homogeneous SR: (Thermodynamic Equilibrium)

73

Homogeneous ATR: (Thermodynamic Equilibrium)

74

ADVANTAGES OF FLUIDIZED BED

 Rapid mixing of solids, uniform temperature and
concentrations.
 Applicable for large or small scale operations.
 Heat and mass transfer rates between gas and particles
are high as compared to
other modes of contacting.
 There is no moving part and hence a fluidized bed reactor
is 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 ρ0gh,

MSc thesis defense presentation at Frank Walk Room, LSU

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