th3_particle size, drying method, water temperature and husk-to-bran ratio are important factors...
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3rd Africa Rice Congress Theme 3: Rice processing and marketing Mini symposium: Adding value to Africa’s rice: rice-derived products Author: Mbazzi et al.TRANSCRIPT
Particle size, drying method, water temperature and husk-to-bran ratio are
important factors influencing the hardness of briquettes at constant pressure
S.A. Ndindeng, J.E.G. Mbassi*, M. Bih-Loh Achu, W.F. Mbacham, J.T. Manful
IntroductionIn regions of the world where rice is produced especially in SSA countries, poor treatment and disposal of rice by-products is a serious problem as this results in pollution.
In these communities rubber roll mills are advantageous not only because they produce better quality milled rice but also because they produce separate husk and bran
PolishingDe-husking
Rubber roll mill
IntroductionRice bran is often used in in SSA countries as an ingredient in the production of livestock feed.
Recently some authors have pointed out the possibility of using rice bran as a supplement in the production of biscuits and cookies (Bunde, 2010; Yadav, 2011).Unlike the bran, rice husk is not used for any purpose in SSA countries and the huge mounts behind rice mills is usually set on fire and it burns slowly as it is produced.
Some authors have indicated the possibility of using rice husk ash as a partial substitute for cement (Brown, 2012).
HUSK
BRAN
IntroductionHowever, in areas where Engelberg-type mills are common, the husk is usually mixed with the bran, making both by-products unsuitable for livestock feed production.
Briquetting of husk from rubber roll mills and husk mixed with bran from Engelberg mills for fuel wood has been suggested as alternative means to add-value to these by-products especially for communities that need fuel wood for other rice processing activities such as parboiling.
Such a briquetting process must also ensure that it does not incorporate material in the briquettes that will render the ash unusable either as a cement substitute or in ceramics.
De-husking and Polishing
Briquettes
ObjectivesOverall To add value to husk and husk mixed with bran through briquetting to achieve the required hardness and burning parameters.
Specific• Produce a briquetting machine• Use machine to produce briquettes while varying the following
factors:• Particle size• Husk : Bran ratio• Water temperature• Drying method
• Measure the hardness of different briquettes
Methodology of briquette productionBiomass
collection
Grinding
Mixing
Briquetting (press)
Drying
Strength analysis on briquettes
Water[Hot = 97 oC] [Cold = 27oC]
•Open –air•In the oven (70°C)
Husk
Bran
Sieving Large, Pore size (mm2) = 2<PS ≤ 67Medium Pore size = 0,49<PS ≤2Fine, Pore size = PS ≤ 0,49
Ratio
Results and Discussions
Support
Piston
Pressure pump
Lid Cylindrical tube
Bar
Lever Open/closed pump
Hydraulic Pump briquetting machine (2 tons)
•Influence of proportion of husk and bran on the hardness of briquettes
More bran leads to harder briquettes
Drying method= Sun, Drying time = 14 days, water proportion= 1,5, water temp= hot (97°C),
Particle size =fine,
33336N =
Ratio of husk to bran
2:10:11:01:21:1
Mean
+- 2
Std
Err
Hard
ness
(Kg)
14
12
10
8
6
4
2
Sokhansanj and co-workers (2005) identified that feed material containing higher proportions of starch and protein will produce higher quality briquettes than material high in cellulosic material.
Results and Discussions
•Influence of drying method on the hardness of briquettes
Michel and Autio (2001): During drying, the amylopectin portion of the starch granule recrystallizes, and increases the rigidity of starch gels
Drying time = 7, water proportion= 1,5, water temp= hot, Particle size =fine, Ratio husk to bran=1:1
Sun drying had the best effect on the hardness of the briquettes.
32N =
Drying method
Sun onlyOven and Sun
Mean
+- 2
Std
Err
Hard
ness
(Kg)
8.0
7.5
7.0
6.5
6.0
5.5
Results and Discussions
•Influence of temperature of water used for mixture on the hardness
Warm water influence positively on the hardness of briquettes
Drying method= Sun, Drying time = 14, Particle size =fine, water proportion= 1,5, Ratio husk to bran=1:1
56N =
Water temp for briquetting (oC)
Cold (27)Hot (97)
Me
an
+-
2 S
td E
rr H
ard
ne
ss
(K
g) 10
8
6
4
2
0
Results and Discussions
Hot water modifies physico-chemical properties (gelatinization of starch, denaturation of protein) and binding between particles is greatly enhanced resulting in improved physical briquettes quality (Thomas et al. 1997)
•Influence of Particle size on the hardness of the briquettes
Drying method= Sun, Drying time = 21, water proportion= 1,5, water temp = hot, Ratio husk to bran=1:1
33N =
Particle size
MediumFine
Mean
+- 2
Std
Err
Hard
ness
(Kg)
12
11
10
9
8
7
6
5
4
Mani and co-workers (2003) report that smaller particle sizes produce higher density briquettes.
Fine Medium Large
Results and Discussions
Conclusions and Recommendations• Husk-Bran mixture of 1:1 from Engelberg mills and husk alone
(1:0) from rubber roll mills gave briquettes of good hardness (7-9 kg).
• The highest hardness were achieved from a combination of the following factors:
Drying method: Sun drying/Open air
Water temperature: Hot (97°C)
Particle size: Fine (PS ≤ 0,49)
Drying time: 21 days
Combination
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