Controlling the Droplet Size and Initial Velocity of Flashing Black Liquor Sprays – Initial Results from a Modelling Approach, 2016 Pulping, Engineering, Environmental, Recycling, Sustainability (PEERS) Conference Proceedings

The current trend in modern Kraft Recovery boilers is that the dry solids content of the black liquor fired is very high, typically 75-85 %. In order to pump and spray black liquor with this high dryness and high resulting viscosity, its temperature needs to be high, typically 135-145 °C, which means that the spraying takes place significantly above the atmospheric boiling point. This means that flashing takes place in the spraying, already inside the nozzle tube and results in a high initial velocity and due to this, a smaller droplet size. Two phase flows are often quite unstable and therefore, the control of the spraying situation can be very challenging.

the objective of this paper is to study how the initial velocity and the droplet size in the flashing case could be effectively controlled by adjusting the spraying parameters. As a tool to describe the multiphase flow inside the nozzle tube, we used our detailed two phase nozzle flow model developed and widely published earlier. These flow simulation results were combined with droplet sizes estimated using a correlation based on a broad data set of our different small and full scale spraying experiments. The paper will give initial results easily applicable to practical boiler cases on how to adjust spraying parameters such as temperature, pressure and nozzle geometry to maintain stable combustion and a constant droplet size if for example, the dry solids content suddenly changes. 

TAPPI conference proceedings and presentations, technical papers, and publication articles provide technical and management data and solutions on topics covering the Pulp, Paper, Tissue, Corrugated Packaging, Flexible Packaging, Nanotechnology and Converting Industries.

Simply select the quantity, add to your cart and your conference paper, presentation or article will be available for immediate download.

Author: Mika Järvinen,, Ari Kankkunen, and Pasi Miikkulainen
Controlling the Droplet Size and Initial Velocity of Flashin
Controlling the Droplet Size and Initial Velocity of Flashing Black Liquor Sprays • Initial Results from a Modelling Approach, 2016 PEERS

New Releases


Kraft Recovery Boilers, Third Edition  

Sponsored by the Recovery Boiler Program R&D Subcommittee of the American Forest & Paper Association (AF&PA) and published by TAPPI Press.



Handbook For Pulp and Paper Technologists (The SMOOK Book), Fourth Edition

The best-selling text to introduce the entire technology of pulp and paper manufacture.



Guidelines for Safe Assessment and Operation of Yankee Dryers  

A project of the Yankee Dryer Safety & Reliability Committee.



Check our newest additions.

TAPPI Press offers some of the most in-depth resources and references for the forest products and related industries. 

See More


Available for Purchase – Conference Proceedings

TAPPI maintains a record of key conference papers, presentations, and other conference publications, available for purchase in a variety of formats.

See More