TECHNOLOGY TO TURN THE CLIMATE TIDE

Technologies used to manufacture early biofuel pellets placed limitations on their use in blast furnaces and generating stations.

Traditional white pellets were characterized by poor moisture resistance, low energy density and high production costs.

Then torrefied pellets offered some promise but exhibited little product consistency caused by an intermittent production process. They also generated dangerous levels of flammable dust.

In recent years, Valmet’s BioTrac™ steam explosion system has emerged as the industry’s best method for producing advanced black pellets, a method that presents none of these issues.

BioTrac™ is now accepted as the gold standard in manufacturing high-performance black pellet biofuel for energy producers.

And PowerWood Canada Corp is leveraging Valmet’s engineering expertise to bring its leading-edge technology to the forefront of the North American energy market. This year it will commence the construction of two Valmet steam explosion pellet plants in Alberta.

Working with local and Indigenous communities in the quiet of Mackenzie County, PowerWood will harness BioTrac™ to produce millions of tons of an effective, scalable and sustainable drop-in replacement for coal – and support global net-zero targets.

Valmet’s BioTrac™ system is rightly lauded in much more effusive terms than these, because its design and development are made unique by many emending qualities.

When compiled, Valmet’s system advantages make clear why steam explosion is the long- awaited and ultimate answer to ending humanity’s reliance on fossil coal as a source of energy.

This article looks at BioTrac’s five most significant gains on previous pellet technologies:

BioTrac’s Superior Science

White pellets are made by compressing sawdust while torrefaction is a dry roasting process. It batch- heats biomass gradually in the absence of oxygen to create char that is pressed into pellets using chemical binders.

Valmet’s BioTrac™ system primes biomass for transformation with hydrothermal pre-treatment. Fire-damaged dead wood, fed continuously into a pressurized reactor, is penetrated uniformly with 18 bar, 240°C steam – causing all plant cell wall hemicellulose to hydrolyze, and its lignin to soften.

Sudden discharge to atmospheric pressure vaporizes all moisture in cells to explode them into a chemically-altered and activated uniform, granular powder. This is then bound into compact, energy-dense, waterproof pellets using the biomass’ resident lignin.

BioTrac’s Superior Product Quality

White wood pellets disintegrate on contact with water while torrefied pellets offer partial water- resistance, due to their brittle form. Torrefied pellets crumble easily, more so after contact with water, and create quantities of dangerous, volatile dust.

Steam explosion advanced black pellets are bound tightly by lignin, a natural polymer that makes plant life water-resistant. They can be pelleted with much greater bulk density than torrefied or white pellets. And, once pelleted, their lignin glaze renders them entirely waterproof – and storable outdoors.

Most importantly, they pack much more energy per unit shipped – greatly reducing logistics, handling and storage costs for downstream users. And they burn with up to 30 percent more volumetric energy than white pellets, and up to 24 percent more than torrefied ones.

Valmet’s BioTrac steam explosion pellet plants change biomass at molecular level to upgrade it into activated green fuel for generating stations.

BioTrac’s Superior Product Safety

Valmet’s BioTrac™ system produces viscous granular powder that is easily controlled before it is pelleted into transportable biofuel, and after when as it is ground for firing in furnaces. In pellet form it is robust and resilient, and doesn’t fragment or create dust.

Steam explosion advanced black pellets are an encouragingly safe biofuel to process at all points of the supply chain. Generating stations that switch to them from burning coal need not make upgrades to storage, handling or processing infrastructure.

Torrefied and white pellets present dust and explosion risks in proximity to station furnaces and generators – necessitating complex and expensive safety systems that include dry silo storage, conveyor modifications, and multiple humidifier, dust extraction and fire detection units.

BioTrac’s Superior Industrial Suitability

Torrefaction relies on batch processing, so new biomass can’t disrupt thermal conditions in the system’s primary kiln. Even in batches, the process struggles to consistently heat biomass throughout – resulting in an inconsistent product.

Valmet’s BioTrac™ system is truly set apart from competing biofuel technologies by its continuous operational design. Its proprietary plug screw feeder allows a constant inflow of biomass into a stable steam explosion reactor environment.

Its constant outflow produces much greater quantities of a highly homogenous, standardized product that has all undergone exactly the same degree of treatment. Industrial-scale end users can rely on it for better boiler stability, and strict and consistent amounts of energy production.

BioTrac’s Superior Pellet Consistency

Torrefaction’s primary drawbacks stem from difficulties with heat transfer and subsequent product uniformity. Maintaining the same temperature at the core of a wood chip as on its surface is a slow and delicate task.

When biomass is pushed through torrefaction at industrial speeds, kilns cannot maintain necessary isothermal conditions. Fluctuations lead to non-homogenous pellets. Over-torrefied biomass is too brittle to pelletize, under-torrefied has absolutely no water-resistance.

But, as torrefaction failed in reaching commercial maturity, Valmet was developing BioTrac™ steam explosion to provide the consistency in product attributes and supply that generating stations need. And, in doing so, it created the first truly viable green ‘drop in’ replacement for coal.

To learn more about PowerWood Canada Corp’s advanced black pellets, and its use of Valmet’s BioTrac steam explosion technology, please use the contact details available on this website.