Wood Pellet Mill

Applications Of Wood Pellet Mill

As a wood pellet machinery supplier, Richi Machinery manufactures and supplies the key wood pellet processing machine and othe processing machine in the wood pellet production line. RICHI wood waste pellet machine can be used for wood and various agricultural and forestry wastes, which is applicable for all kinds of biomass materials. We also offer single machines for the production of biomass wood pellets, solid biofuel, and waste pellets.

The global warming impact, the increasing prices of fossil fuel, and the need to produce thermal and electrical energy stimulated the creation of an industry leaning toward energy production by renewable sources. Biomass is a widespread renewable source to provide energy demand in terms of electricity and heat. Of course, wood pellets have many other uses, such as cat litter, organic fertilizer, etc.

Wood is by far one of the oldest and most abundant types of biomass raw materials. In addition to cord word, other types of forest products residues such as tree tops, branches, bark, logging slash, and saw mill waste can be used as sources of biomass energy.

As a raw material; wood (hard and soft woods), wood chips, sawdust, hull, tree branches, tree leaves and similar forest residues are used.

• Hardwoods; Mahogany, Walnut, Oak, Ash-tree, Birch, Maple, Cherry-tree, Beech etc.
• Softwoods; Pine, Larch, Picea etc.

Technical Features Of Wood Pellet Mill

1. The wood pellet mill main shaft system uses double support structure without shake to offer more extrusion force from ring die.

2. The wood waste pellet machine control device of ring die and roller is external to realize gap adjustment without stop-working.

3. The wood pellet machine rollers use circulating water cooling, realizing lower temperature and longer service time of bearings, and lower oil consumption.

4. The bearings of main shaft and roller with temperature measuring device, which can monitor the working status of wood pellet making bearings.

5. The wood pellet maker key components like main shaft, driving wheels and gears are made of high strength forged alloy steel. Gears are processed by high precision gear grinding machine.

6. The wood pelletizer driving system uses imported bearings to ensure the reliability and long service time of the equipment.

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Working Principle Of Wood Pellet Mill

Typically any wood raw material will require some form of processing prior to being pelletized. This can range from debarking if using whole logs (round wood) to shredding or grinding of pallets, or ag products. Once the product is shredded or ground, it could require further processing through a wood pellet hammer mill, depending on how it was received.

If the wood waste raw material is wet (over 15%) it will need to be dried. After sizing and drying if needed, the product is now ready to be pelletized. Pellets can be made in a wide range of diameters and bulk densities, which is typically determined by the end use of the pellet. The wood pellet machine ring die specifications can be changed, allowing for multiple sizes to be produced from the same wood waste pellet machine.

In most cases pellets will exit the wood pellet production machine hot (100-170 degrees) and must be cooled. This is done with a pellet cooler by pulling ambient air through the pellets. Once the wood pellet is cooled to ambient temperature, the pellets are screened to remove any fines that may have been created during the wood pellet production process. The wood pellets are now ready to be packaged by wood pellet packing machine, stored or sold in bulk.

Wood Pellet Machine Price & Specification

Energy content for various wood residue(dry weight basis)

The application of wood residue pellets is increasingly widespread, but the application as fuel pellets is still dominant. Therefore, it is still necessary to discuss the raw materials of wood pellets.

How Are Wood Pellets Produced By Complete Wood Pellet Plant?

In global market, wood pellets are mostly produced from sawdust, wood shavings and other woody byproducts. Traditionally, wood pellet production line units are located on or nearby sawmills and other wood processing sites, representing complementary outlet for these wood pellet manufacturing plants. In this context, a first crucial step for wood pellet producers consists of grinding and drying the moist wood residues.

The energy needed for this is mainly made available by the burning of bark or any low quality wood, which likewise accumulates on site. In many cases, not only is heat produced by burning the bark, but also electricity that can be optimally used to run unit. After the wood waste is dried, it is fed into a biomass wood pellet mill. Within the wood pellet maker, dry woody materials are squeezed through a die with holes of the required size (normally 6 mm diameter, sometimes 8 mm or larger) called a matrix.

The high pressure of the wood pellet pressing machine causes the temperature of the wood to increase greatly, causing the surface to plasticise slightly to form a natural "glue" that binds the wood pellet together as it cools. To facilitate the wood pellet pressing process and improve quality parameters, small quantities (max. 2%) of natural binder such as starch can be added, but no glues enter the composition of wood pellets.

Newly compressed pellets are now ready to be cooled and sieved to remove any residual particles. Finally, wood pellets can be stored and/or bagged by wood pellet packing machine prior being delivered to end consumers.

Complete wood pellet manufacturing process is shown below: (Related post: how to set up a complete wood pellet plant or biomass wood pellet production line)

Types of wood pellet mills for sale

According to the shape of the pressing die, pellet mill for sale can be classified as:

In both cases, there has to be a rotary element, which can be the die or the rollers. In the case of flat dies, the rollers are the moving element, whereas the most common design of ring dies is where the die is powered and rotating, and the rollers move due to the friction and movement of the die.

• Ring die pellet mills, which are applied to small, medium and large-scale pellet production industries. In other words, unless it is a scale of tens of kilograms or less than 100 kilograms, the ring die wood pelletizer can be applied to any size of wood pellet production business.
  
  In the wood pellet machine ring die, there are radial slots throughout the die. The die is positioned vertically, powder is fed into the centre of the die and spreaders evenly distribute the powder. Two or more rollers then compress the powder through the die holes. Two cutters are used to cut the wood pellets free from the outside of the die.
• Flat die wood pellet mills, is a kind of homemade wood pellet machine, which are used for very small scale wood pellet manufacturing (for home use, for mini scale). Flat die wood pellet makers use a flat die with slots. The powder is introduced into the top of the die and, as the die rotates, a roller presses the powder through the holes in the die. A wood pellet machine cutter on the other side of the die cuts the exposed pellet free.

Ring die pellet mill or flat die pellet mill, which is better?

Although we also design and manufacture flat die wood pelletizers, with the continuous improvement of the processing technology of wood pellets, the characteristics of the flat die wood pellet manufacturing equipoment are not as good as the absolute advantages of the ring die wood pellet press machine.

As a professional wood pellet mill manufacturer, we must sincerely tell everyone that the wood granulator technology must move forward, and the ring die wood granulator is the final trend. Considering the quality of equipment, durability, maintenance cost, and quality of finished pellets and other aspects, if the output you need allows, try to choose a ring die wood pelleting machine.

Usually you can see many flat die wood pellet makers on the Internet, which will confuse many customers who are in the wood pellet processing industry for the first time. In fact, well-known and professional wood pellet mill manufacturers do not recommend purchasing flat die pellet mills for wood and biomass pellets, because the quality of the actual processed pellets is not good, and the output cannot keep up.

When you browse the official websites of groups such as CPM and Buhler, you can easily see that there is only a ring die pellet mill machine (which can also be a wood pellet extruder or feed pellet extruder), and there will never be a flat die biomass wood pellet making machine.

Types of wood pellet mill die

There are different die types of RICHI ring die pellet mill for wood pellet plant that vary with regard to hole depth, hole pitch, hole width and die material.

• The depth of the hole is not related to the length of the pellet. It establishes the time the material is exposed to heat and pressure. Longer holes are recommended for materials with low lignin content to achieve better melting and, therefore, a harder, denser pellet.
• The pitch angle of the hole influences pellet compression, and it should be designed according to the feedstock.
• For biomass pellets, the most common diameters are 6 and 8 mm. These diameters, as well as the length of the pellets, are limited by the Pellet Standards to assure that the wood pellets can be fed by the screw conveyors of standardized stoves and boilers without blocking the feeding systems.
  
  Experience has shown that thinner pellets allow a more uniform combustion rate than thicker ones, especially in small furnaces. The length of the pellets affects the fuel feeding properties: the shorter the pellets, the easier to arrange for continuous flow.
• Wood pellet pressing machine ring dies are made from several different types of metal. Dies for wood pellet makers must be resistant to abrasion, strong enough to handle the forces of pellet production and corrosion resistant without negatively affecting productivity.
  
  The materials most often used are carbon steel alloy, stainless steel alloy and high chrome alloy. Obviously, the most expensive materials ensure higher resistances and productivities of the wood waste pellet machines.

These parameters have to be optimized in view of the particular feedstock to guarantee good productivity and to avoid blocking the wood pelletizing machine dies. Blocked dies can be found when:

1. The wood pellet raw material generates more resistant force while passing through the die than the force generated by the roller;
2. The wood pellet machine die hole is corroded.

If the wood pellet making machine ring die gets blocked, the material has to be drilled out. To facilitate this process, it is best to work when the die is still warm, previous to the formation of hard pellets within the die holes.