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LS-DYNA has been one of Predictive’s core analysis tools pretty much since we got started in 1995.  It is an amazing numerical workhorse from the basic linear mechanics (think ANSYS or Nastran) to simulating well nigh the impossible.  At least that is the way I feel at times when the model is not solving and spitting out arcane error messages and I’m basically questioning my sanity for accepting this project from hell that has a deadline at the end of the week.  Which brings me to my favorite project management image – “trough of despair followed by wiggles of false hope then crash of ineptitude and finally the promised land” but I’ll leave that for another blog. 

Our latest CFD case study covers our work on a newly built recovery boiler to estimate operational temperatures, CO emissions, and NOx emissions. The recovery boiler is fueled solely by black liquor that is sprayed into the lower furnace.

The coal combustion model defined by Lagrangian particles was used in STAR-CCM+ to model the drying, devolatilization, and char burning reactions that occur to the black liquor. One challenging aspect of black liquor combustion is the droplets swell in size (4 to 5 times original diameter) during the drying and devolatilization reactions. These effects were captured by using customized functions to simulate particle swelling during combustion. Analysis results were comparable to results obtained from previous analyses on comparable boilers.

CFD CASE STUDY - Simulation of Recovery Boiler Combustion

LS-DYNA has been a mainstay at Predictive Engineering for roughly 20 years.  It has been an amazing journey and on most days, LS-DYNA is the all-time, most favorite code of my simulation existence.  But, as we all know, there are moments when the model is not running, the manual must have been written in Greek, un-explicable error messages are flying past you on the screen and basically you are questioning your sanity as the clock tolls 2:00 am in the morning.  Nevertheless, in general, 99.999% of the time, you just love the power and flexibility of LS-DYNA.  One of our more fun projects was this high-speed cone crusher where big rocks are crushed into smaller rocks.  Rock comminution was one of my specialties when I worked for the US Bureau of Mines as a scientist, so this project had a special twist since we now had a chance to make a virtual rock pile and then crush it.  The LS-DYNA model used Lagrangian rocks that were then crushed within the rotating, rigid-body cone crusher.  Loads were extracted and then applied to a FEA model.  The rock crushing model was simply used to create loads for the stress model.  As we know in FEA, the three most important things that determine the accuracy of your FEA model are: Loads, Loads and Loads.  Yeah – another simulation joke.