GEK Wiki / Instrumented Softwood Chip Run 091609
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Instrumented Softwood Chip Run 091609

Page history last edited by bk 11 years, 4 months ago

Date: 2009/09/16




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.


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.



This run was intended to repeat the same conditions and method of the 08/24/09 run with softwood chips. A previous run on 8/31/09 ran into issues with fuel binding in the long auger which lead to only a partial run. For this run the auger was switched to the short auger/drying bucket design (as used for the TOTTI) (the auger remained strictly for reactor filling, the cowling gas->drying bucket pathway was not connected).


Gas out flowmeter was switched from a union-based flowmeter to hardwelded flowmeter (1.5" pipe, 0.76" orifice).



Diagram of the experimental setup. Not shown: Tar fence, fuel detect "plunger". Not to scale.



Softwood Chips

  • bulk density: 195 kg/m3 (wet) (3 sample average, 1L vessel)
  • void space: 53% (water in 1L vessel)
  • moisture content: 12.4% dry basis, 11.0% wet basis (microwave method)


Start Up


Experimental Run


Tar Sampling



Fuel and Air Mass Flow

With measurements taken for this run we can compute the air to biomass mass flow ratio.

A figure of 1.6 kg of air per 1 kg biomass is provided on Modeling Gasifier Mass Flow. Measurements from this run allow us to compute this value (integrated over the entire run).

The run comsumed 83% of a hopper barrel of softwood chip fuel over a run of roughly 3 hours 20 minutes.

This is 0.0648 m^3 of fuel (62 cm * pi *  (36.5/2 cm)^2) or 12.64 kg wet (0.0648 m^3 * 195 kg/m^3) or 11.25 kg dry (12.64 kg -12.64 kg * 11.0%).

Integrating airflow measurements over the entire run gives 13.66 m^3 input air or 16.4 kg air (13.66 m^3 * 1.2 kg/m^3).

Dividing air input over wood input: 16.4 kg air/11.25 kg dry wood = 1.46 kg of air per 1 kg biomass.


This figure is very close to the expected value. Note, however, that there are a number of places for introduced error, especially from the low flow/low resolution region of the air flowmeter. 


Critical Temperatures

Reactor Flows

Gas flowmeter replaced. Gas out compensation still needs updated (do not use for calculations).



Reactor Vacuum


Contour Plot of Vertical Temperature Distribution with Time



Reactor Conditions

Measured Tar Correlations with Reactor Conditions

The saturation meaurement for these exceded the detectable upper bound on a number of the higher tar concentration samples. Black line is tred temperature scaled to 600-900°C bottom to top.



Run Description

Run Name: Instrumented Softwood Chip Run
Run Location: Shipyard, Berkeley, CA
Operators: Bear, Michael
Date: 09/16/09
Type: Softwood Chips (Scrap Lumber)
Moisture Content: 12.4% dry basis, 11.0% wet basis (09/16/09)
Angle of Repose: ND
Ash Content: ND
Void Space: 53% (water in 1L vessel)
Bulk Density: 195 kg/m3 (wet) (3 sample average, 1L vessel)
Version: v3
Reactor Type: Imbert
Air Nozzle Size: 3/8" street 90°C with 3/8" cap drilled on center with 5.5 mm dia. hole, 2.75" above reduction top
Reduction Cone Height: 6
Top Reduction Diameter: 3
Bottom Reduction Diameter: 6
Tar Fence: yes
Tar Fence Height:  
Filter: v3
Filter Media: New char, 1/8"-1" (walnut/mesquite)
Fill Height:  
Gas Motive Force  
Ejector yes
Jet Nozzle Type (eg barb, plug): drilled plug
Jet Exit Position:  
Fan no
Power Source/Voltage:  
Engine no


GCU Setup Form

Run Name: Instrumented Softwood Run
Date: 09/16/09
GCU Version: 1.0
Firmware: in development (PID control of reactor with servo controlled ejector air, timed grate shaking (1 min intervals, ~40° fwd/back rotation)
TC0 T_bred - bottom of reduction - 1" in from cone bottom, through manometer port
TC2 T_tred - top of reduction - inside 1/4" mild steel pipe quarter round, welded closed and positioned on the top edge of the reduction cone
TC3 T_air_in - air in - inside air riser, through hole drilled co-axially with the riser tube through street 90°. 1 1/2" below top of riser.
TC4 T_comb - combustion - first TC of profile assembly. centered by ring rod assembly, 1" in front of air nozzle hole, at same elevation. Sheathed in 2" length of alumina tube, extending 1/2" below TC (1/4" OD, 1/8" ID).
TC5 T_1in - 1" above combustion. 2nd TC of assembly...
TC6 T_2in - 2" above combustion.
TC7 T_3in - 3" above combustion.
TC8 T_4in - 4" above combustion.
TC9 T_6in - 6" above combustion.
TC10 T_8in - 8" above combustion.
TC11 T_gas_out - installed in cowling gas exit port
TC12 T_flare - installed in 1 1/2" tangential entrance tube
TC13 T_gas_flowmeter - installed in 1 1/2" to 1/2" reducing T just after filter, before union based gas flowmeter
FET2 Grate Fwd Relay (30A automotive) (FET # not confirmed)
FET3 Grate Rev Relay (30A automotive)
SERVO1 Ejector Air Control
Pressure: Part (7002,5004,4006,7007,5010,7025,5050)
P0 7007 - P_comb - pressure at combustion, via profile assembly
P1 7007 - P_reactor - taken from reactor manometer port
P2 7002 - P_gas_out - gas out flowmeter differential pressure
P3 7002 - P_air_in - air in flowmeter differential pressure (flowmeter installed on V3 air cowling inlet)
ANALOG0 P_filter sensor input from breadboard (7007)
ANALOG2 Auger plunger on sense (12V motor line, through voltage divider)
Frequency Counter



Comments (1)

jay said

at 3:41 pm on Sep 20, 2009

Bear, this is great. Will you have the new flow meter calibration soon for the compensation in the calculations?
Beautiful graphs!

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