Origins of the Wood Pellet

History of the manufacture of wood pellets begin from the energy crisis of oil in the 1970s. Wood pellet making technology itself is adopted from animal feed/fish pellet technology  that had already been applied.  Along with the development of various technological modernization in line with the characteristics of raw materials, product specifications or market demands according to international standards, production efficiency and capacity of the plant to meet market needs. Efforts to create alternative energy from renewable sources  with several quality improvements of raw material into the solution at that time. After the oil crisis of the 1970s ended the production of wood pellets decreased. But when the problem of global warming, climate change and efforts to increase the added value of woody biomass and the rapid depletion of fossil fuels began in the 1990s finally wood pellets again received great attention.

Woody biomass in particular is said to be a source of alternative energy that can be renewed only if the production is done in a sustainable manner. Forest plantations or energy crops is an attempt to sustainable production of biomass sources in addition to the utilization of wood wastes from various industrial timber that must also be traced if from legal sources. Sawdust in particular is the best raw material for the production of wood pellets, but because of its availability is usually not a big plus if collected from a number of sawmill waste for example, and so much demand that should be observed when actually be used for the production of wood pellets. 

The wood logs are part of a plant or tree are best to produce pellets. If the premium quality woodpellets (pellets Class A1) produced,  the debarking process must also be done to minimize its ash content. While part of trees or other plants that have a higher ash content so it can not be used for the production of premium quality wood pellets. Wood pellets have the best quality lowest ash content and high calorific value and are generally only used for the home heating in some European countries, the U.S. and Canada. While wood pellets with a lower quality than that its use in industry. 

Log wood for premium wood pellet feedstock after debarking

In contrast to European countries and the U.S. are generally using wood pellets for domestic consumption as heating, in Asia generally digunakansebagai wood pellet fuel or power generation industries. The differences in consumption patterns due to climatic conditions, among others, as a result of its geographical location and the awareness of the environmental impact.  Various advantages of wood pellets for industrial and domestic applications and a wide range of driving factors on environmental issues, climate change, global warming and the economy makes it increasingly massive demand for the commodity. 

Wood Pellet and Briquette For Food and Beverage Industry

Fuels as an energy source in the food and beverage industry is the primary need is always required.  Environmentally friendly fuel, easy handling, cheap and easily available always wanted by the producers of the food and beverage industry. The biomass-based fuel, pellets and briquettes are the ideal choice for those needs it. The advantages of pellets and briquettes are:

1.     Environmentally friendly fuels and renewable

2.     High calorific value is generally more than 4000 kcal / kg

3.     Low ash content and minimum fly ash when burned

4.     Consistent high burning efficiency due to low moisture content

5.     High density thus saving transportation costs

6.     Uniform shape so as to facilitate the transportation, storage, feeding and burning

7.     The burning  is more homogeneous than coal

8.     Pollution is very low due to the sulfur content of nearly zero

9.     The more demanded because of the increase of fossil fuel

A number of industries have done the conversion from fossil fuel or firewood with burning of pellets or briquettes because of the excellences. Here are some types of wood pellet burner with automatic feed burner that is widely used namely:

1.     Stoker burner boiler

Stoker boiler burner boilers are the most simple, which has a small grate mounted directly at the end of the feed auger. In a small stoker boilers burner only comes with a single fan so it is difficult to separate the primary air supply to the grate of the combustion zone above the end of the grate. As a result of overheating and the potential formation of a deposit on the grate is very high, and some boiler makers adding cooling water circuit in the grate as a preventive.

2.     Underfed stoker boiler

In underfed stoker boiler, fuel pushed up through the inverted conical pile formed like a dome where combustion occurs. Almost all stoker boilers have air duct separate primary and secondary air to provide independent control of the combustion zone on the grate and in the end gas combustion.

3.     Moving grate boiler

Moving grate boiler is also known as, stepped grate boiler or inclined grate boiler, allows the greatest flexibility in the design of the boiler. These boilers can use the auger or ram stoker type feeder. As in underfed stoker boiler, moving grate boiler has primary and secondary air duct, and on the largest boiler tertiary air duct was added to ensure the complete combustion of wood gas at all. 

Briquettes have a larger size than the pellets. Therefore the size of the briquettes can be cut into smaller pieces to match the needs of its users. Below is an example of briquettes for boiler applications.

Besides being used in the food and beverage industry, pellets and briquettes can also be used for a variety of industrial fuel (thermal application) include: power generation, ceramic industry, chemical industry and others. 

Scenarios of Forest Waste Utilization

Forestry wastes in Indonesia is very large amount and need to be utilized optimally. There are currently largely untapped. Multiple scenarios are proposed according to the characteristics of the forestry wastes, market needs and technological processing.

Biomass densification technology such as pelleting and briquetting is one interesting scenario to be implemented. Pellets and briquettes visually distinct because of its dimensions. The dimensions of wood pellets with a diameter varying between 6 and 25 mm and an average length is around 40 mm, while the diameter of its products if more than 25 mm is referred to as briquettes. By utilization of forest waste into briquettes is more advisable, because the size of the particle from size reduction, moisture content, and ash content of less restrictive requirements in briquette making. As for pellets particular A1 class  pellets (premium pellets) must use stem wood and do debarking. A1 class pellet or premium pellet are pellets with the lowest ash content and high calorific value. But if only for the production of quality standard pellet is not a problem. Pellets as well as briquettes can be for almost any industrial consumption as an environmentally friendly fuel substitution of coal.

 

However if the source location of the forestry waste is close to industries that require a lot of fuel such as cement plants, power plants and so on, then the forest waste can be directly chipping (reduced in size to the size of a few centimeters) to be directly used to fuel the industry.

Whereas if forestry waste sites are also still lack electricity or need other sources of energy or heat, then another better way is to use continuous pyrolysis technology. With this technology will produce products such as charcoal, biooil and syngas, which three can be used as an energy source. Charcoal can be sold to cement plants or power plants as fuel or increase soil fertility with enriched various nutrients to soil. Then charcoal for this application commonly called biochar. Biooil can also directly as fuel although only about half the calorific value of diesel oil and methane-rich syngas which is the excess of the portion used for the pyrolysis process itself, so that one can be used for power generation more easily with Internal Combustion (IC) engine as a gas engine generator.