Using wood powder as fuel in lime kilns, pilot case study

Valmet has shown that wood powder firing in the last decade, has been developed to be a fully commercial, proven and most important safe solution for lime reburning kilns. It is therefore today possible to convert a pulp mill into a fossil-free mill and by that reduce the mills carbon footprint and fuel costs.

To successful implement a wood powder firing solution with high availability, it is important to understand and master each unit operation from drying, grinding and dosing to burning in the kiln. It is possible to substitute 100% of fossil fuel with wood powder without any negative impact on lime quality, lime kiln operation or capacity providing:

1. the moisture content is preferably less than 5%
2. the correct burner design is being used

More understanding of grindability of new possible wood sources is required as the wood powder solution is going to be used more and more on a global scale.

A white paper found HERE discusses the use of wood powder as a replacement lime kiln fuel, as well as the factors that must be considered when evaluating using wood powder as kiln fuel and the lessons learned from operating with wood powder. Södra has contributed to this paper based on their experience at Södra Värö mill with a wood powder firing system that was installed in 2014.

For more information on wood powder as a green fuel for lime kilns, contact your Valmet representative.