CFD Modelling of Calciner Combustion

HRL utilised Computational Fluid Dynamics (CFD) modelling to analyse and understand the combustion process in the calciner. The model encompassed raw material feed, natural gas fuel, wood fuel, combustion air, and air leakage.

Flow, energy, chemical reaction, and mass transfer were simulated in the model to account for not only the combustion of fuel, but also the heat uptake and flow path of the raw material.

HRL also addressed another calciner process issue of unburned natural gas collecting in the raw material downstream of the calciner which was resulting in trip of the plant. The burner layout was optimised to improve the gas flow path, thereby reducing the likelihood of methane collection, and increasing plant availability.

Results

The results and observations from the CFD modelling analysis are as follows:

• The revised configuration of the calciner, with the new gas lances installed to increase swirl, resulted in more stabilised combustion in the lower part of the calciner and improved burn-out of the wood.
• The introduction of a new wood inlet into the calciner allowed for a higher throughput of wood and reduced the consumption of natural gas.
• Adjusting burner orientation reduced the likelihood of methane collection and related plant trips.
• Further recommendations were provided based on the CFD modelling analysis, including further modifications to the gas lance configuration and the addition of a third raw feed inlet to the calciner.

Overall, the CFD modelling analysis conducted by HRL provided valuable insights into the combustion process in the calciner. The results helped to identify areas for improvement and to propose solutions to enhance the combustion of wood and prevent plant trips.