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Vertical auger in hopper fuel feed

Page history last edited by jim mason 15 years, 1 month ago

The traditional way to get a dynamic fuel feed, with integrated heat recycling to the incoming fuel, is via a double jacketed horizontal auger. This is most famously the method used in the DTU Viking Gasifer. Of course it works great as an immaculate research solution. But it is also quite complicated to build and materials/dollars heavy-- thus non-ideal for small scale low dollar deployment. So here's some thoughts on how to get the same thing with significantly less trouble, using a variety of "hopper still on top" designs, with vertical drive fuel metering systems.

The main benefit of a vertical drive is you are not fighting multi-orientation drive problems. Your fuel feed drive is in the same axis as your fuel stirrer/agitator (which you are going to want if you are going to all this effort towards a failsafe machine). In fact, some of the architectures keep the feed screw exactly in line with the agitator rod, and thus the two can be combined into one. One motor to do both jobs. Maybe we can put the rotary ash grate drive on the same motor too. So three motor jobs potentially combined into one drive rod.

The vertical solutions are also attractive as you can integrate the new drive guts into the existing hopper. Thus vertical designs tend to require signficantly less new construction and dedicated assemblies than horizontal augers. The middle design below shows how you can do it with about zero new added transport housing. Just the usual vessels, but now with the very important fuel feed rate enabled.

All the solutions below integrate a new heat exchange annular shell in the hopper for the product gas to rise up through, and give up heat to the fuel. Added circulation holes at the base allow a passive convection currents to circulate in the hopper for a monorator type drying/condensing cycle.

And finally, note that we can also use this annular heat exchange shell as the vessel for the packed bed filter. Thus the filter (and its heat) can be in the hopper actually doing useful thermal work, still with easy access to it through the hopper lid. Less things hanging off the side of the gasifier too.

As usual, less is always more. And embedding hot things needing to be cool, inside cool things needing to be hot, is similarly good.

Let's figure out which one of these we want to build, or some new elaboration beyond them, and build the particulars soon. An automated fuel feed and heat recycling / fuel drying system will be critical in the longer run to achieve fully robust gasification systems.