Date: 2009/08/31

Purpose

This is a continuing series of tests 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.

This run used the same tar testing methodology and pressure setpoint experimental design as used on the Instrumented Walnut Shell Run 082409.

The primary change in this run was a switch to softwood chips from scrap lumber (which we believe to be pine and douglas fir).  The wood chips were made with a commerical disk chipper, then the fines screened out.

Other tests in this series are linked to from the GEK User Pages and Run Reports page.

Methods

This run was intended to repeat the same conditions and method of the 08/24/09 run with softwood chips. There were a few instrumentation and auger issues that did not yield a complete repetition of the previous run (the GCU was reset during the second ramp up/down "pyramid") and the run called short. The run should, none-the-less, yield some useful information.  What is below is still a very partial report.  It will get finished after a short vacation for the rest of this week.

Start Up

Experimental Run

Tar Sampling

Results

Critical Temperatures

The drop in combustion temperatures at 157 min is perplexing, sensor failure may be best explaination.

Reactor Flows

The gas out lines experienced some condensation in the latter part of the run. The condensation was removed on one occasion, leading to 0 flow readings. Condensation in the lines will bias measurements. Air in measurements are unaffected.

Reactor Vacuum

Combustion pressure line was not connected until 110 min.

Contour Plot of Vertical Temperature Distribution with Time

Combustion reading is anomalous after 160 min (values caused by failure of the combustion thermocouple [oxidation]).

Reactor Conditions

The auger fuel feed had binding issues (excess of overly long chips?), leading to the long periods of the auger being on.

Tar vs. Reaction Conditions Relationships

The points with T_comb around 400°C were likely from the period after the combustion thermocouple failed (after 160 minutes above), invalidating this graph.