Make Pellet from Green Pine Sawdust

1. Introduction
Pines are conifer trees in the genus Pinus, in the family Pinaceae. There are evergreen, coniferous resinous trees (or rarely shrubs) growing 3-80 m tall, with the majority of species reaching 15-45 m tall. Pine is also used as firewood. But, the direct combustion of Pine, not only economic, but also low combustion efficiency, and will release large amounts of carbon monoxide, carbon dioxide and other soot Cause environmental pollution. If make it into wood pellet, its combustion efficiency will be more than 80%. The emission of sulfur dioxide, ammonia compounds and dust is less.

Pellet fuels (or pellets) are fuels made from compressed organic matter, or, biomass. Wood pellets are the most common type of pellet fuel and are generally made from compacted sawdust, related industrial wastes from the milling of lumber, manufacturing of wood products and furniture, etc. Pellets are categorized by their heating value, moisture and ash content, and dimensions. They can be used as fuels for power generation, commercial or residential heating, and cooking. Pellets are extremely dense and can be produced with a low moisture content (below 10%) that allows them to be burned with very high combustion efficiency. Further, their regular geometry and small size allow automatic feeding with very fine calibration. They can be fed to a burner by auger feeding or by pneumatic conveying. Their high density also permits compact storage and rational transport over long distance. They can be conveniently blown from a tanker to a storage bunker or silo on a customer's premises.
With the surge in the price of fossil fuels since 2005, and the EU 2020 policy targets, the demand for pellet heating has increased in Europe and North America, and a sizable industry is emerging. According to the International Energy Agency Task 40, wood pellet production has more than doubled between 2006 and 2010 to over 14 million tons. It’s a good time to be pellet business. The feasibility analysis of make pellet from green pine sawdust as discussed in detail further in the present report.

2. The Technical Feasibility of Use Wet Pine Sawdust to Produce Pellet

pine wood pellets

2.1 Wood Pellets Formation Mechanism
The proximate chemical composition of wood is Cellulose, Hemi-Cellulose and Lignin. Cellulose is the major component of plant cell wall, the higher its content, the more the plant cell wall tissue. Hemi-Cellulose in plant cell walls serves to cellulose and lignin through effect. Lignin can enhance the mechanical strength of the plant itself, plant binder fibers.
At the beginning of compressed, the solid particles are arranged loosely packed structure began to change. Under pressure, the mutual position of the particles occurs constantly change during operation, the air between the particles of the raw material extruded. Larger lignocelluloses particles under tremendous pressure molding began to break, while plastic flow, due to the engagement between the raw material particles to each other becomes very tight. In the direction perpendicular to the main stress on the continuous extension of the raw material particles continue to fill the voids. The high pressure of the pressure roller causes the temperature of the wood to increase greatly, and the lignin plasticizes slightly forming a natural "glue" that holds the pellet together as it cools.

2.2 The Chemical Composition of Pine
The chemical composition of pine wood (other genera are similar) is approximately: 42% cellulose, 25% hemicellulose, 30% lignin, and 3% pectin, starch, ash, other. The principal component cellulose is a polymer of glucose (about 10,000 glucose units per cellulose molecule) which forms tiny microfibrils which aggregate to form larger elementary fibrils, the principal constituent of the tracheid walls. The shorter chain hemicelluloses (150 - 200 glucose units) fill spaces between cellulose chains and various size fibrils. The lignin is a phenolic compound (benzene with attached methoxy, propyl and hydroxy groups) which is tightly bound to the cellulose.
Pines belong to the softwood. Softwood pellets generally have higher heat output and lower ash. This is where softwood wins. Below is information from a study done by the wood industry.
White Oak 8810 BTU/pound
Yellow Pine 9610 BTU/pound
A softwood pellet will produce 10-20% more BTU's per pound than hardwood depending on the species and create a lighter ash.

2.3 Pine Pellets Manufacturing
Our company’s pellet production equipment and technology is very advanced, and highly cost-effective. The overall process of manufacturing fuel pellets involves raw material receiving, crushing, drying, pelleting, cooling, and packaging. Each step must be carried out with care if the final product is to be of acceptable quality.
Figure 1 the production process of a wood pellet exporter

pine wood pellets making

(1) Raw Material Receiving
The production of wood pellets begins with the generation of the raw material. Quality of raw materials determines the quality of the pellets. Make sure the wet pine sawdust is clean (no bark or dirt). Furthermore, sawdust should not be exposed to the weather, which can protect the sawdust from some harmful elements.
(2) Crushing
The raw material needs to be pressed through a flat die with small holes (6mm for wood pellet) drilled into it. If wet pine sawdust larger than this size, it should be crushed. The suitable hammer mills are required to crush this sawdust into small particle sizes.
(3) Drying
Maintaining an appropriate moisture level in your feedstock is vital for overall quality of the final pellets. For wood, the required moisture level of the feedstock is at or near 15 percent. Moisture can be removed from the feedstock by oven-drying or by blowing hot air over or through the particles.
(4) Pelleting
The pellet is actually created in this step. A roller is used to compress the biomass against a heated metal plate called a “die.” The die includes several small holes drilled through it, which allow the biomass to be squeezed through under high temperature and pressure conditions. If the conditions are right, the biomass particles will fuse into a solid mass, thus turning into a pellet. A blade is typically used to slice the pellet to a predefined length as it exits the die. Sawdust is an especially suitable feedstock for pelleting because the lignin that is naturally present in the wood acts as a glue to hold the pellet together.
(5) Cooling
Pellets, as they leave the die, are quite hot (~150°C) and fairly soft. Therefore, they must be cooled and dried before they are ready for use. The heat and moisture are removed in our specially modified cooling equipment. The final moisture content of the pellets should be no higher than 8 percent.
(6) Packaging
Once the pellets are formed and cooled, they are packaged in bags or stored in bulk. Pellets can be stored indefinitely but they must be kept dry to prevent deterioration.

3. The Economic Feasibility of Use Wet Pine Sawdust to Produce Pellet
3.1 Opportunities for the Pine Sawdust Pellet

(1) Rural Users
Where natural gas is not available, pine sawdust pellet has a significant market opportunity. It is principally in the rural areas of the state where natural gas is not available; these are considered prime areas to develop pine sawdust pellet markets.
(2) In-State Anchor Tenants
Commercial, institutional and industrial facilities that currently use fuel oil, residual oil/waste oil and propane are potential anchor tenants to support the development of the pine sawdust pellet market. These include food processing facilities; department of corrections facilities; asphalt, concrete and petrochemical companies; and schools.
(3) Build Demand Then Build Supply
It is first focusing on building base load demand in larger facilities. When volume reaches sufficient levels, a pellet mill will be developed to meet that demand.
(4) Export Markets
European wood pellet consumption ranked first in the world. Current EU pellet consumption for energy is more 15 million tons and total energy consumption of bioenergy is about 102 million tons. Energy market experts expect the wood pellet market to grow by about 25 million tons in 2020.

3.2 Cost Analysis of Use of Wet Pine Sawdust to Produce Pellet
The world’s largest wood pellet producer is USA. Its production is more than twice the second largest producer. This determines the price of wood pellets. In 2013, Yifei Qian analyzed the value chain of wood pellet that made in the southern United States and exports to Europe. The study found, under the assumed scenario, feed stock cost accounts for about 52% of the total cost, while plant operation cost and delivery cost to ports are around 39% and 9% respectively. If pellet producers deliver their goods at $155/tone, they can achieve a gross margin of 20.7%. This profit margin is lower than the average for the manufacturing industry, which is around 30%, but higher than many other forest industry profit margins.

Table1 Cost Break-down at pellet production center

Assumed Scenario
Percentage of Total Cost
Feedstock Cost
Plant operation cost
Total cost
Fixed cost
Depreciation of assets
   Fixed O&M cost
Variable cost
Delivery cost to ports
Direct production costs
FOB wood pellet prices

US wood pellets are mostly made of hardwood. Pines belong to the softwood. It is tends to be cheaper. This is due to the fact that softwood trees tend to grow faster and hence are easier and cheaper to produce. This also makes softwood more environmentally friendly, as it can be more readily renewable than hardwood.

4. Conclusion
From the above analysis, our technology of making pine sawdust is quite mature and advanced. Pine sawdust is the high quality raw material to make wood pellet. Without the use of additives in the pellet process, so that the pellet process is easy to control and reduce the defect rate. In terms of the relative hardwood, pine grows faster, so the cost is lower. And, pin wood pellets heat value higher calorific value, lower ash content. The pine sawdust pellet has a broad and bright market.

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