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How to make high quality biomass pellets / Briquette ?

Time:2018年11月26日      Hits:

How to make high quality biomass pellets / Briquette ?

Nowadays, all kinds of biomass pellets / Briquette are applied by home users, small and medium scale power plants, heating boiler and so on. Among different kinds of biomass pellets, sawdust pellets  / Briquette are most widely used, not only because of their broad raw material origin, but also because of their high heat value (3700-5000kcal/kg, higher than other biomass pellets). 

As the sawdust arrived in the wood pellet machine plant, the moisture content should be tested. The moisture content gives the proportion of evaporable water in the total weight of material. The sawdust with high moisture content should be stored separately from the low moisture content sawdust. The production of 1 ton pellets needs the about 7 bulk m3 sawdust with the moisture content around 50-55%. The optimum moisture content of the sawdust is 10-15%. The sawdust with higher moisture content should be dried before entering the wood pellet machine while the lower one can skip the procedure. If you want to know more about raw material moisture, read this article.

Raw Materials :

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Wood pellets are usually made from clean conifer sawdust and planer shavings. The wood must have been debarked prior to passing through the saw mill. Sawdust of hardwoods can be missed in with that of softwood, but successful production of hardwood pellets without binders is more difficult. If at all possible, dry sawdust and shaving(less than 15% moisture content) are used, because then the drying step can be skipped. If the sawdust is wetter, a drying process is needed before pellets can be pressed.

Screening:

The screening of the sawdust is to remove the stones, plastics, metals, or other hard materials that may damage the equipment. The stones and stone like hard materials are removed by a stone trap when the sawdust passes over the screen while the metals are picked up by a magnet. Sawdust should also be passed over a magnet that removes metal objects. Foreign particles in the sawdust are likely to damage the press or could conceivably cause sparks in the hammer-mill, which might lead to a dust explosion.

Storage: 

For storage it is preferable to separate wet and dry sawdust. Wet sawdust can be stored for a short period out in the open. The moisture content is not too badly affected if some rain falls on the base materials, and wet sawdust does not blow about as easily. Dry sawdust should be stored indoors immediately to prevent the materials getting wet. If the material is stored outside, the sawdust can blow about and create dust hazards.

Drying

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The wet sawdust should be dried before size reduction because the wet sawdust consumes more power to be hammered than the dried one does. And also the wet sawdust may risk the screening by clogging or smearing the screen. Drying can be done by the dryers, a so-called flash drier that works with high temperatures, or on a flatbed dried, which works at a relatively low temperature. The first option is better suited for fine material, while coarse material needs a lower temperature. So, if chips are going to be mixed in, a flatbed drier is preferable.

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The heat for the sawdust drier machine can be supplied by any kind of fuel, e.g. gas, oil or even biomass. The biomass boiler could use bark, wood chips, short rotation coppice or other wood waste that is not suitable for pellet production.

Pelletizing

sawdust dryer, sawdust drying machine, sawdsut drying system

When the sawdust goes into the pelletizing chamber of the wood pellet machine, the lignin of the sawdust will be heated up to 120-130°C by the heat produced by the running wood pellet machine and by which the lignin will be plasticized and binds the particles together to help to mold the pellets. The pellets are molded by being pressed through the pellet dies of the wood pellet machines and then are cut off by the cutter with the desired length. During the pelletizing, the binder may be needed to improve the pellet strength and durability. Vegetable oil is added to lubricate the last pellets at the end of a working period.

The sawdust rotary dryer by sunco machinery has the features as follows:

Sawdust Rotary Dryer is special designed Inner 7 Chamber, and it is Concurrent Dryer.

It has the advantages as follows:

01. New design by Sunco for drying low humidity material with surface water in bulk production.

02. Compact Structure, less space occupation. 

03. Special 7 chambers inner design, when working, each part's weight of the dryer is balance. Less motor power needed.

04. The material will be flipped 7 times inside the dryer, and the flipping times is 2.3 times of the traditional drum dryer. Thus the material can be dispersed more sufficiently, and to be heated and dried by the hot air more sufficiently. As a result, the heat exchanging efficiency is higher, and its fuel consumption is lower.

05. The material falling height inside the dryer is reduced much, thus the material abrasion to the lifting plates and dryer drum is less.

06. Higher heat efficiency.

07. The material output moisture content can be controlled by adjusting the exhaust air temperature and the drying time in the dryer.

08. In actual operation, its water evaporation intensity is more than 2 times of the traditional dryer, thus it has higher heat efficiency, and the operation cost is lower.

09. It adopts Gear Drive with better stability . 

Note: For Gear Drive type, can add lubrication oil between the roller and ring to reduce the friction, reduce the abrasion of roller and Ring.

     For Roller Drive Type. it is use the friction between the Roller and Ring to transfer the power and make the dryer drum rotates, and it is not suitable to add lubrication oil between the Roller and Ring. Thus the abrasion of the Roller and Ring is much more, and its lifetime is shorter.

The dryer totally has 4 sets of Roller ASSY, and each set of Roller ASSY consists of 2 rollers. It means that totally there are 8 supporting point for the dryer machine, and the loading weight on each roller is only half of the loading weight on each roller of the traditional Triple Drum Dryer, thus it increases the running stability of the dryer machine.

If you are in need of Output Capacity 1.0 Tons Per Hour Sawdust Drying System, please supply more information as follows:

--- What is the usual initial moisture content (%) of your wet sawdust ?

--- What is the output moisture content (%) of the dry sawdust needed ?

--- What kind of fuel will you prefer to use for the sawdust drying system, such as coal, waste wood, diesel, or natural gas, etc ?

--- What is the output capacity (ton per hour) of the sawdust drying machine needed ?

For more detail of sawdust drying machine , please directly contact us:

--- Email: suncomachinery@hotmail.com

--- Tel./ WhatsApp: +86-15838214261

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