sun grant reporting - q2 - 2012...18! below! (fig! 2).! the! granules! were! normally!...
TRANSCRIPT
16
Low cost Granulation of lignocellulosic biomass Recipient Organization: University of Georgia Principal Investigator: Sudhagar Mani Project Location: University of Georgia Reporting Period: April 1, 2012 – June 30, 2012 Date of Report: August 1, 2012 Written by: Sudhagar Mani & Shahab Sokhansanj
1. Planned Activities:
Task 8c Granulation of lignocellulosic biomass-‐ Experimental investigation on various parameters: Effect of pine wood powder particle size on the quality of granules Milestones: To determine optimal particle size for generating high quality pine wood granules Deliverables: Optimized pine wood powder size to produce high quality biomass (wood) granules.
2. Actual Accomplishments:
Task 8c Granulation of lignocellulosic biomass-‐ Experimental investigation on various parameters: Effect of pine wood powder particle size on the quality of granules Materials Large volume of pine wood powders were prepared using both a hammer mill with 1.58 mm and a knife mill with 0.25 mm screen size to obtain three different range of biomass particles. The particle size ranges were selected based on the ability to make granules from the preliminary study. Binder preparation Corn starch (pellet bond™) was used in this experiment with a binder concentration of 5% (wt/wt) and binder percentage based on feedstock powder (wt/wt) of ~10% (Table 1). Binder was heated to 60ºC for dissolving the corn starch in the solution. All the binder solutions were heated to 60ºC prior to spraying. Granulation experiment A laboratory scale disk (pan) granulator was used for this study. The description of the granulator and general operating conditions were similar to the procedures reported in Task 5 (Q2 Progress Report in 2011). The pan angle and granulator rpm were maintained constant throughout the experiment. Each granulation run was replicated.
17
Table 1. Granulation runs with different powder size ranges
Run # Feedstock Powder size ranges (mm) Binder % (wt/wt) based on
feedstock powder mass
1 Pine wood 315-‐500 10.08
2 Pine wood 160-‐315 10.10
3 Pine wood <160 10.11
Results Granulation experiment Tables 2a-‐b show the granulation experimental results from two granulation trials. The yield percentage for all the runs is above 75% and there is an increase in yield % with decrease in powder particle size range. The final moisture content (%wb) for all the runs is around 64%. The residence time for all the runs is 25 min. Table 2a. Experimental data for particle size effect on granulation (Trial #1)
Run # Feedstock Powder size
ranges (mm)
Granulation residence time
(min) Yeild %
Wet granule moisture content (%wb)
1 Pine wood
315-‐500 16 75.39 63.76
2 160-‐315 25 89.27 64.63
3 <160 25 85.77 63.49
Table 2b. Experimental data for particle size effect on granulation (Trial # 2)
Run # Feedstock Powder size
ranges (mm)
Granulation residence time
(min) Yeild %
Wet granule moisture content (%wb)
1 Pine wood
315-‐500 20 87.56 63.50
2 160-‐315 25 91.16 64.77
3 <160 25 94.61 64.89
Pine wood powders with different particle size ranges were successfully granulated by using corn starch binder (Fig 1). The granule size distribution for these granules is given
18
below (Fig 2). The granules were normally distributed with a mean particle size of around 11 mm.
A) Pine wood (315-‐500 mm) B) Pine wood (160-‐315mm) C) Pine wood (<160mm)
Figure 1. Pine wood granules
Figure 2. Pine wood granules size distribution (pw: Pine wood)
Table 3 lists the summary of pine wood granules generated at three different particle sizes. The mean granule size of pine wood granules made from different powder size ranges are from 11 to 12 mm. The granules are very spherical in shape with mean sphericity of 0.9. The mean granule hardness was in the range from 160 to 100 N which is similar to the wood pellet hardness (~120N). The single granule density and bulk density were increased with a decrease in powder particle size. The hausner ratio and angle of repose values indicates that granules produced with different powder size ranges are having excellent flow properties. The pine wood powder below 160 mm produced the highest quality granules but it may be suitable to use 315-‐500 mm size powder for production of granules if the energy required for fine grinding.
0 2 4 6 8 10 12 14 16 18
0 5 10 15 20 25 30
Granu
le size
distrib
uUon
(%)
Granules size (mm)
Pine wood granules
pw (315-‐500)
pw (160-‐315)
pw (<160)
19
One-‐way ANOVA and multivariate comparison of granule properties at various particle size ranges are underway to evaluate the impact of powder particle size on granule properties.
Table 3. Physical and bulk flow properties of pine wood granules*
Properties of Granules Pine wood powder particle sizes
(315-‐500 mm) (160-‐315 mm) (<160 mm)
Geometric mean diameter dgw (mm) 11.00 12.52 11.25
Standard deviation of geometric mean diameter Sgw (mm) 2.41 3.36 3.56
Mean Sphericity 0.89 (0.0057) 0.92 (0.0083) 0.92 (0.0071)
Specific surface area (Sv (1/mm)) 0.57 (0.03) 0.50 (0.03) 0.60 (0.11)
Hardness (N) 48.47 (12.47) 51.97 (14.41) 100.25 (33.48)
Single granule density (kg/m3) 380.87 (55.43) 426.02 (60.26) 453.34 (56.84)
ASTM Bulk density (kg/m3) 259.53 (4.03) 269.58 (4.09) 272.58 (2.39)
Aerated Bulk density (kg/m3) 252.22 (2.52) 260.30 (2.47) 265.09 (2.19)
Tapped Bulk density (kg/m3) 265.19 (4.21) 272.59 (1.52) 275.55 (1.74)
Hausner ratio 1.05 (0.016) 1.05 (0.005) 1.04 (0.013)
Angle of repose (degrees) 28.67 (4.04) 25.67 (3.79) 32 (3.61)
*Feedstock powder particle size range is given in brackets and also the standard deviation is given in brackets next to mean value of each property.
3. Explanation of Variance: None
4. Plans for Next Quarter: The following research task is planned for the next quarter (July 1. 2012 – September 30, 2012)
20
Task 9 Surface properties of liquid binders Milestones: To determine surface tension, liquid density, viscosity and wettability of various binders and binder concentrations used in Tasks 8a-‐c. Deliverables: Properties of liquid binders used in the granulation study to
5. Budget:
a. Funds Expended to Date (End of Reporting Period): $134,000 b. Remaining Balance of Funds: $65,000
6. Patents: N/A
7. Publications / Presentations:
Yandapalli, V and S. Mani. 2012. Effect of particle sizes on the granulation of lignocellulosic biomass powders. Presentation at the 2012 ASABE Annual International Meeting, July 30, 2012, Dallas, TX. USA.