Make Biomass Pellets from Sugarcane Bagasse

During sugarcane manufacturing process in tropical and subtropical district, over one million tons of bagasse are produced. The economic value of direct burning or throwing away is very low, so a new applying method of making wood pellets from them has been developed and put into use. As one of the energy obtaining ways with easy operation and cheap raw material, bagasse biomass pelletizing provides customers with not only great profits but also cozy living environment. From the three parts described blow, the information about feedstock, making process as well as end products can be known in detail.

bagassesPart One: Brief Introduction of Bagasse
This part gives brief introduction of bagasse from three aspects: origin, application and composition.
1.Origin: Bagasse is the dross left behind after extraction process of sugarcane manufacturing, so it mainly comes from sugar mill and other related factories. In average, nearly 2-3 tons of bagasse can be got when one ton of sugar is produced.
2.Application: Bassage can be further processed into something a lot worthier than its original value. Aside from wood pellet manufacturing talked about here, alcohol, paper and fodder can all be made right from this material.
3.Composition: Different composition of a certain substance leads to different uses and processing methods. That of dried bassage is listed in the following table for your reference.(Before drying, the moisture content is 45~50%.)

 Item  Cellulose Hemi-cellulose  Lignin   Ash
 Content  32~48%  19~24% 23~32%   1~4%

 

Part Two: Information of Bagasse Biomass Pelletizing
1.Process of bagasse biomass pelletizing
Same as many other raw materials for wood pelletizer, the process of bagasse biomass pelletizing is also: crushing-drying-pelletizing-cooling-packing
1.1.Crushing: Before all other procedures, crush bagasses into smaller particles with diameter of 3-5mm.
1.2.Drying: Dry crushed bagasse particles with wood dryer until their moisture content reduces to 10%-15%.
1.3.Pelletizing: Make wood pellets in specially designed pelletizing chamber with the help of pressure, high temperature, impact and extrusion.
1.4.Cooling: Cool produced bagasse pellets down to normal temperature so that no harm won’t be caused to either subsequent device or pellets themselves.
1.5.Packing: Pack end products properly to make the storage, transportation and application convenient.

2.Available wood pelletizer for bagasse biomass pelletizingsugarcane bagasse pellets
Two alternative wood pelletizers are available: ring die type and flat die type.
2.1.Ring die wood pelletizer: With customized die size, gear drive and overload protection, ring die wood pellet maker is a choice for customers who require large capacity and low energy consumption.
2.2.Flat die wood pelletizer: As the other pelletizer type for the core procedure of wood pellets manufacturing, flat die type has simple and compact structure which makes it easy to move and convenient to operate.
2.3.Comparison of these two wood pelletizer
A.Die structure: Vertical for flat type and horizontal for ring type.
B.Output: In spite of the structure advantages of flat die wood pelletizer, it has smaller output, 40-1800kg/h.
C.Feeding mode: Raw materials for flat die wood pelletizer go into pelletizing chamber vertically in virtue of their own weight, while those for ring die are forced in mechanically.
D.Application: Ring die wood pelletizer is more suitable for large-scale industrial production and flat die for small family workshop.
Of course, only one machine is not enough in order to make wood pellets successfully and smoothly. Actually, wood crusher, wood dryer, pellet cooler and pellet packing machine are all required in the process.

3.Molding of bagasse biomass pelletizing
The structure change and molding of bagasse pellets rely on the additive role of lignin as well as skeleton role of cellulose and hemi-cellulose. When lignin begins to soften and plastify at 180℃, the pressure exerted by die and rollers makes it adhere tightly with cellulose and adjacent particles. In this way, separate sugarcane residues are produced into regular pellets with fixed geometrical shapes.

4.Influence of pressure on bagasse biomass pelletizing
The molding process of raw materials has close relation with the transformation of those perpendicular to principal stress direction. For feedstock with same size, larger pressure makes more significant extension and larger density.

5.Influence of moisture on bagasse biomass pelletizing
Fresh sugarcane bagasses should be dried first before wood pellets manufacturing. Otherwise, excessive moisture will evaporate under the action of heating and extruding, which may lead to the failure of molding or coarse surface of bagasse pellets. However, raw materials shouldn’t be over dried either because that will make end products easy to loosen and break.

6.Influence of size on bagasse biomass pelletizing
The size of raw materials for wood pelletizer should be 3-5mm, which is why bassages are crushed first before other processes. Too large may lead to clogging while too small will affect the quality and output of end products. Within given standard, the smaller they are, the larger molding density is.

bagasse pellet usePart Three: Information of Produced Bagasse Pellets
1.Advantages to process bagasse into biomass pellets
1.1. Make great profits: The main investments on bagasse biomass pelletizing include raw materials, equipment, manpower and electricity. Thanks to beneficial market condition and reasonable machine design, costs of all relative factors are low, which ensures fast and high return on investment.
1.2.Reduce environmental pollution: Without pelletizing or other process, the random throwing away or piling up of bagasses will not only do harm to environment but also damage surrounding living atmosphere.
1.3.Change properties of bagasses: On one hand, the combustion feature of produced bagasse pellets is much better than original materials. On the other hand, molded biomass fuel with regular shape and small volume takes up less space, making both transportation and storage more convenient than before.
1.4.Improve energy shortage situation: The shortage of energy has attracted more and more development of biomass fuel. As one form of that, bagasse pellets manufacturing plays its own role in the wave of novel heating source exploitation.

2.Quality of produced bagasse pellets
With changeable customized size, produced bagasse pellets have low moisture and high calorific value. Little ash and zero SO2 content makes them free from pollution.

 Moisture  Ash Calorific value   Size  SO2
 12%  14%  4600kcal/kg  6,8,10,12…mm  0%

Although the above characteristics are very important, making sugarcane bagasse into wood pellets is not just for heat value increasing and environmental pollution reducing. It should also meet the requirements of application, transportation and storage. Therefore, apart from combustion features, density and durability become two vital indicators to measure the quality of produced bagasse pellets.

2.1.Density: The density of produced bagasse pellets is high because their inner porosities are reduced to the minimum by appropriate compressing time as well as properly enhanced pressure and temperature.
2.2.Durability: Durability reflects the adhesive property of a certain substance, refining in deformation resistance, shatter resistance, water resistance, etc. Appropriate heating temperature, low moisture content, proper molding pressure and high density contribute to excellent aging quality of produced bagasse pellets.

3.Application of produced bagasse pellets
3.1.Industrial boiler: Produced bagasse pellets can be used as fuel to supply energy for power station, paper mill, fertilizer factory, etc.
3.2.Home warming: Development of wood pellets manufacturing improves the shortage situation of civil heating resources, enabling people to own a cozy warm environment in winter.
3.3.Animal feed: With the help of a feed pellet mill, bagasse pellets can be used to feed horse, cattle, dairy, etc.
3.4.Animal bedding: Produced bagasse pellets can also be used as animal bedding to provide your pets or poultry with a cozy and clean home.

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