In order to create torrefied wood, commercial-grade thermal processing equipment is required. The equipment must create an atmosphere that will heat biomass without allowing it to burn.   Temperatures and conditions suitable for a thermo-chemical change in the wood must be sustained within the equipment.

The Global NRG process uses an indirect heat source to continuously process bulk materials that are combustible, potentially contaminating and thermally sensitive. Low moisture wood is fed into a rotating torrefier shell, which is enclosed and heated from the exterior in a stationary furnace. This guarantees complete separation of heat source and biomass during processing. The rotation and slope of the rotary shell motivates the material through the chamber from feed point to the discharge at the opposite end.

Heat from the torrefier causes the wood to give off water vapor, volatile organic compounds (VOCs) and other gases. The combustion of these off gases is recovered by the torrefier and is used to heat the process. For high moisture feed material, a rotary dryer can be added to the starting point. The dryer will reduce the moisture content in the material so that  it can then be moved to the torrefier.

Alternately heat can be provided via DOALL furnace which can use mixed biowaste with up to 60% moisture as a feedstock. This opens up the potential to use biowastes such as tree trimmings, grass cuttings, green waste and agricultural wastes that might otherwise be sent to landfill.

Global NRG’s drying and processing equipment ensures that biomass undergoes a full treatment process without damaging the end product.  This means the torrefied wood being produced will not degrade in quality over time.

Under optimal conditions, the Global NRG equipment would be located near the source of the feedstock, to greatly improve the economics of using biomass as a viable energy source. The cost associated with transportation from the feedstock source to the customer is greatly reduced by the increase in energy density of the material through torrefaction.

Torrefied wood, also known as bio coal, can be blended with currently-used coal as feed into the boiler to moderate the change. Blending torrefied wood in the boiler feed has been proven to improve boiler efficiency and reduce sulfur dioxide (SO2) emissions. This offers significant advantages over 100% coal usage on a same-cost basis, including the overall reduction in power plant emissions.

Global NRG’s pilot plant testing laboratory can determine the appropriate processing conditions for all applications. From a test to a small toll run, our lab facility can provide the scalable data to determine the exact criteria for your process.

Uses For Torrefied Wood

Wood that has been torrefied can be used in a variety of commercial operations, and can help power plants operate with lower carbon dioxide emissions. Power plants that utilize coal as a basis of energy can add torrefied wood to their firing processes.  Factories, such as steel plants, that utilize coal or other resources to heat metals can add torrefied biomass to their processes as well.  There is also a growing demand for biomass- fueled residential heating systems. Wood heaters are already in use to heat homes and water, and torrefied wood may make mass production of such systems practical.

Torrefied wood fuels can be easily applied as:

■    High-grade smokeless fuels for industrial, commercial and domestic

       (residential heating or backyard grilling) use

■    Solid fuel for direct co-firing with pulverized coal at electric power plants

■    Upgraded feedstock for fuel pellets, briquettes and other densified biomass fuels

■    Feedstock in gasification processes

■    Soil additive to improve plant growth and health

Reasons To Use Bio-Coal

In addition to the positive impact on the environment, there are many reasons to use torrefied wood in addition to or in place of other heating and energy resources. They include:

■    The energy density of torrefied wood is 5–6 times higher than wood chips and about 1.5 times      higher than ordinary wood pellets

■    The torrefaction process creates such a dense product that transportation costs are reduced. More quantities of fuel can be packed into the same amount of space, reducing the number of loads required to provide the same amount of energy.

■    Wood that has been fed through the torrefaction process is more efficient in plant processes due to the chemical and physical  properties of the resulting material.

■    Beyond the capital cost of the torrefaction equipment itself, the cost of producing torrefied wood is affordable.

Highlights of torrefied biomass

■    Process uses no chemicals or toxic substances

■    Nearly nonexistent moisture content

■    Resistant to biodegradation

■    Can be stored for long periods of time

■    Resistant to insects

■    Treated through the core

■    Utilizes the same material handling and pulverizing equipment as coal