Impact of process changes on heat transfer and scaling rates in kraft black liquor evaporators

Purpose and goal:

The transition to a bioeconomy requires not only that we use more biobased raw materials but also that we have resource-efficient manufacturing processes. Since black liquor evaporation is very energy-intensive and often a bottleneck, its performance is very important to ensure efficient operation of the entire pulp mill. The aim of the project is to determine how various process changes such as temperature and dry solids affect the heat transfer and the scaling rate in black liquor evaporators.

Expected results and effects:

The project strengthens Swedish competitiveness through expected research results and new fundamental knowledge related to the development of resource-efficient black liquor evaporators, which in turn intensifies the pace of innovation in the transition to a circular economy. The project contributes to the industry´s innovation capacity through technology development and training of people who can implement process-oriented research in the industry.

Approach and implementation:

The project will involve experiments in a world-unique pilot evaporator and use numerical simulations to achieve the prescribed goals. The heat transfer and scaling rate dependence on temperature, dry and salt content will be investigated experimentally. A numerical framework for simulating crystallization under industrially relevant conditions will be formulated to understand the experimentally observed crystallization on the heat transfer surfaces.