Tar vs Soot testing: Soluble separation method

Bear Kaufmann finished another run on the GEK test and datalogging rig and posted the results here: http://gekgasifier.pbworks.com/Instrumented-Walnut-Shell-Run-082409. This wiki page has a large collection of graphs and other data assemblies from the run. Bear is very clever. Someday he’ll get a Phd in all this. In the interim, we get to ponder his bi-weekly posting of dissertation worthy test runs and data visualizations. Thank you Bear.

The main issue he was/is trying to resolve in this test is how to measure tar. The usual “simplified tar testing method” with the greyscale seems very open to mixing the tar and soot signal on the filter paper. both tar and soot are “black”. Filtering before the sample tends to reduce both of them indiscriminately. So we’re trying instead to take the sample without any prefiltering, and dissolve the tar out of the sample with a solvent, and then measure the color/hue/greyscale of the liquid.

Does anyone here have any experience with this type of soluble tar testing method? Or otherwise have any input on the accuracy or import of the attempted tar-soot separation method?

In the pix above, and in the more detailed report linked above, you will see that most all the the test samples are black. But when these samples are put in a solvent solution, the dissolved results are quite distinct. And those results fortunately track well with how we would expect reactor conditions to vary tar production. Remember all these tar/soot tests are being done right at the reactor, before any of the filtering train of the rest of the gasifier system. We are trying to figure out the tar conditions/variations of the gasifier, not the filter performance. Here’s the graph of how the tar samples track against top of reduction temps, with both the dissolved liquid tar and greyscale of unprocessed sample plotted.

This test is a continuing series of experiments to explore the relationships between tar production and various critical measurements in the reactor. The goal is to be able to use temp and pressure readings for gasifier diagnostics and establish a formal set of “conditions needed” for clean gas production. Our hypothesis is that we can most accurately correlate tar production with temps maintained at the reduction restriction, which approximately measures how well x temp has spread and filled the hearth area for tar cracking. The graphs at the end of the report plot tar production against this top of reduction temp, as well as other variables that might be contenders for relevant control or indicating parameters.

We’re currently debating the particulars in the GEK forum here:  http://gekgasifier.com/forums/showthread.php?p=663#post663
jim

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