Choose Best Raw Materials to Make Charcoal Briquettes
Which kind of raw material is best to make charcoal briquettes? According to the structure of raw material, two factors affect the quality of machine-made charcoal: the knot of fiber and the lignin content. The former directly affects the density and mechanical strength of charcoal briquettes and the latter affects the carbon content of briquettes.
Here is the analysis about the different raw materials.
1. Larch. It is commonly recognized the best raw material to make machine-made charcoal. Due to the close fiber structure, high lignin content and better density, larch can be made into charcoal briquettes with high density and better hardness at lower briquetting temperature and less extrusion force.
2. Other pines. Almost all pines are suitable for machine-made charcoal. But because of the different properties, some pines are not ideal raw materials. For example, the fiber structure of white pine is different to recover once it is damaged and it can’t be made into high quality machine-made charcoal briquettes even at high briquetting temperature and high pressure. In this situation, we need to mix other raw materials to improve adhesive capacity.
In addition, the density of some pines is not very good, such as camphor tree. Although it belongs to pine and the grow cycle is longer, the woodiness is a little soft. If we use camphor tree as raw material, it will have underfeeding situation and the briquettes are east to crack. We can adjust the spiral span or increase screw diameter of the propeller. Because of the different grow places and grow cycle, the proportion of ingredients and structure features are different. But if we can analyze it properly and reasonably and take measures accordingly, pines are still very ideal raw materials to make machine-made charcoal.
3. Hardwood. Hardwood has a great variety, such as birch, basswood, elm and most fruitwood and bamboo materials. Their growing year is usually between pine and softwood and the woodiness is hard. Most hardwood can be regarded as machine-made charcoal raw materials. But because different hardwood has distinctly differences, some hardwood materials may have worse adhesive capacity. This can’t be simply solved by adding some other materials, so using hardwood as raw materials needs high requirements of technology.
4. Agro-forest waste materials
Agro-forest wastes refer to the waste materials in agriculture and forest, such as rice husk, peanut shell, coconut shell, straws, stalks, etc.
Some agro-forest wastes can be also used to make machine-made charcoal, but most of them have disadvantages like high ash content and low calorific value, etc. And the briquetting is difficult because they need higher briquetting temperature and larger extrusion force. But this kind of raw materials is abundant and cheap and the categories are rich. This is the advantage of waste agro-forest materials. For example, some barbecue restaurants buy machine-made charcoal not to barbecue food, but to extend the flame by using the feature of long burning time. So it needs low requirement for the calorific value machine-made charcoal. They can buy machine-made charcoal made by these agro-forest wastes. If the briquetting technology and carbonization method are advanced, the machine-made charcoal made by agro-forest wastes has the same effect with it made by saw dust in both calorific value and combustion time.
In addition this, we should also consider the size of raw materials. If the materials are large, they need to be crushed first, such as wood shavings; if the materials are too small, they need to be added some larger size materials with high density, such as wood ashes, saw dust, sanding powder, etc.
The International Standard of Machine-made Charcoal
Different charcoal has different surface color in different carbonization temperature. The charcoal looks grey at carbonization temperature 2500C; machine-made charcoal looks black at carbonization temperature 300-4500C and machine-made charcoal looks black and has gloss at carbonization temperature above 7000C.
The mechanical strength of machine-made charcoal is largest at longitudinal direction; following by radial direction and chordwise direction. The strength of machine-made charcoal increases with the combustion time.
The density of machine-made charcoal is about 0.8-1.2g/cm3. Generally speaking, machine-made charcoal made by hardwood also has larger proportion.
The calorific value of machine-made charcoal is about 6500-8000kcal/kg. The higher carbonization temperature is, the larger carbon content and calorific value are.
The ash content of machine-made charcoal increases with the rise of carbonization temperature.
When the carbonization temperature is above 7000C, machine-made charcoal has conductivity; when the temperature is less than 6000C, it doesn’t have conductivity.
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