Biomass energy provides a carbon neutral alternative to fossil fuels. Besides minimizing the amount of carbon dioxide in the atmosphere, utilization of biomass energy is advantageous in that fuel can be made with widely available materials such as wood chips, sawdust, agricultural debris and other materials that may otherwise be considered waste.
Biomass pellets are low in sulfur and nitrogen, and produce less ash when burned as fuel. It is convenient to use in that it can be produced at home, is inexpensive, burns cleanly and is a compact source of energy. These benefits complement the more altruistic, environmentally-focused reasons for using biomass pellets.
The choice of raw materials is important for two main reasons.
1. Each material has a different heat value, ash content and corrosive qualities.
2. Each material has to be prepared differently to make quality pellets.How Can We Troubleshooting Our Pellet Mill?
Pellet Mill Troubleshooting
1. Why won’t the pellets discharge?
a. Holes in the die at times become blocked and need to be cleared.
b. The material contains too much moisture.
2. Why has the pellet mill’s motor suddenly stopped?
a. The voltage is low.
b. There is too much pressure between the rollers and die.
3. Why are the pellets soft or powdery?
a. The die is worn.
b. The raw material is too dry.
4. Why has the roller become damaged?
a. The machine was operating for an extensive period of time without material.
b. Foreign objects, such as rocks, were in the raw material.
Before using pellet making machine , the die should be grinding-in as follows: Prepare 5kg raw materials and 1 kg silver sand, then mix them sufficiently and inject 1 kg used oil. Start the machine and put in all the mixed materials. Then adjusted the pressing roll bolt until it outputs normally. Keep the machine working with materials for an hour. Then put in normal raw materials and begin to produce. If the machine can’t work regularly, loosen the bolt until it works.
If the machine can’t output yet, clean the oily material or the dry material in the die by steel nail, then grinding-in again.
After a full day’s work, when there are no raw materials left in the pelletized tank, inject the oily material to avoid the die hole being blocked. You will save a lot of time for next work day.
The gap between the rollers and the die determines the granulating effect of the stock and amount of wear on the parts. This gap is typically set at 0.05 to 0.3 mm. If the gap exceeds 0.3 mm the material will spread in a thick and nonuniform manner across the die causing poor pellet quality. A gap smaller than 0.05 mm causes unnecessary wear on the pellet making machine
Pelletmakingmachine’s machines can be easily adjusted with a hex key; adjust both screws evenly in each turn.
Smaller pellet presses generally utilize a flat die with two rollers and are mostly for domestic use. Small pellet machines, despite their size, can still make pellets from a variety of biomass wastes such as sawdusts, agricultural debris, straw, husks and others. Pellets for animal feed can also be made using grain or corn. The process requires only a limited initial investment and is easy to operate.
Trade-offs exist when choosing dies of different depths and with holes of different diameters. A wide-holed shallow die will have higher output but at the expense of pellet density. The opposite is true with narrow-holed thicker dies. Users should choose the correct pellet mill die based on their requirements.
The Pellet Mill Mechanics is a machine used to produce wood pellets from readily available biomass materials (wood chips, sawdust, planer shavings, etc.). The machines vary in size, from three kilowatts to 375 kilowatts (five to 500 horsepower) or even larger. The production volume per pellet mill ranges anywhere from 90 kilograms to eight metric tons per hour. Loose raw materials can be compacted from about 100 kilograms per cubic meter to 650 kilograms per cubic meter for an incredibly dense and efficient energy source.
Pellets are produced in the mills by pressing the raw material against small round holes in the die. The material is pressed against the die and into the holes by the roller until reaching the desirable length. At this point the pellets are cut by a knife outside of the die and fall into a storage area. Before all of this happens the raw material is treated in the mill’s conditioner which may be utilized to add liquid to the raw material. This process enhances the machine’s capacity and results in firmer pellets.
Pellet mills generally contain one of two die types: the flat die or the ring die. The size of the holes in the die range from two to ten millimeters. The die plate’s thickness determines the durability of the pellets and may be as thick as 100 mm. These components are commonly made from metal alloys, stainless steel or chrome. This is to withstand high pressures within the die which may reach up to 172,000 kPa (25,000 psi).
In a pellet plant, the pellets are transferred from the pellet extruder, to a cooler/drier to eliminate the heat which is produced from pressurization. Moisture must also be allowed to escape the pellets for increased durability in storage and shipping. Pellets are then typically stored in silos or bins for bulk shipping or are processed by packaging systems.
Such pellets are utilized in energy producing systems such as industrial boilers and pellet stoves. Wood pellets are nearly homogenous in terms of energy content per unit of weight.
Pellet mill sizes vary, from large facilities used to fuel biomass power plants to smaller models designed for home use. The machines can be used across a variety of industries and for numerous purposes, but the basic principle behind the machinery nonetheless remains the same: to lessen the volume of raw material and to increase its density and uniformity by converting it into pellets. The product of the machinery – the pellet – can be categorized into three basic types.
Feed pellets offer a more convenient distribution to livestock. For over a century, pellet machines have been employed to decrease the volume of animal feed. Diverse mixtures can be created to enhance the feed’s nutritional content, then compressed using the pellet press.
Although wood shavings have traditionally been employed as animal bedding, it has been proved that the dust within the shavings can trigger problems in animals’ respiratory systems. By converting the wood shavings into pellets with a pellet press, these problems can be mitigated as pellets are more absorbent and create less dust.
Within the last decade wood pellets have been used as an alternative fuel source to fossil fuels. Wood pellets can be transported as a liquid and readily flow via hopper systems. The density of pellets increases the combustion temperature beyond that of simply burning logs.
We all know the working principles of ring die pellet mill and flat die pellet mill, but there are still some differences between them. 1. Feeding way: ring die pellet mill adopts machine forced feeding, materials enter the granulating chamber with high speed rotary and distribute through scraper to ensure feed evenly; while the flat die depends on the materials weight, it directly enters into the suppress room, it can feed evenly. 2. Pressure: in the same diameter mould, the pinch roller of ring die is limited by the mould diameter, so the pressure is restricted; however, the flat die can add the inside the bearing space, choose a big bearing to increase the bearing capability, which not only improve the press power of pinch roller, but also prolongs the life. 3. Discharging way: ring die belongs to high rotary speed, the materials percentage of damage is high, while the percentage of damage of flat die is low.
Our pellet mills can be equipped with a hammer mill to break the raw material down to a uniform size (3-6 mm). The hammer mill readily processes straw and grass, but wood must enter the unit in chipped form or must have a diameter of less than 1 inch (2.54 cm).
Your choice of biomass should be based primarily on what you have available to you, but also on what your boiler or stove can burn successfully without complications. Please check the properties section for a summary of some biomass fuel properties.