Stoves Committee

Results for 2/14/2012

Haiti Clean Stove Project - UIUC

Planned to do a WBT on the Chip Energy Stovepipe Stove, but mass scale battery died. Instead, we used the emissions analyzer for the first time on the stovepipe stove.

Fuel is 8 cups of wood pellets. Used fire-starting wax and paper.

Emissions probe inserted through an improvised flue

At first, the stove was not starting properly. We realized that we had the primary air holes closed. This would be important for stove users to know: primary air must be open when lighting. The stove produced a lot of smoke; a bed of embers started but there was not a flame on top.


Stages of Gasification in the Stovepipe Stove

High Power Start

Largest yellow flame

Probe was in flame, we are not sure about emission measurements. O2 and CO2 are basically atmospheric.

O2 = 20.2%

CO = 76... 21... 146 ppm

CO2 = 0.4%

Measured T=524C next to but not touching flame

T=750C with probe in flame

“Yellow pyrolysis flame”

Yellow flame decreases in size

Appearance of blue at the base of the flame, immediately at the secondary air holes.

O2 = 10.6%

CO2= 10%

CO = 0 ~ 10 ppm

NO = 88 ppm

Lowest O2,

Highest CO2,

Lowest CO,

Highest NO

“End of yellow pyrolysis flame”

Yellow flame is greatly reduced

Blue flame jets are prominent, coming from intermediate holes below main flame

O2 = 11.3%

CO = 9 ppm

CO2 = 9.3%

NO = 68 ppm

“Blue Char Flame”

Blue flame is dominant

CO is very high

O2 = 15.2%

CO = 362 ppm

CO2 = 4.5%

NO = 7 ppm

Highest CO

“Yellow Char Flame” (?)

Flame retreats downwards

More yellow

O2 = 17.4%

CO = 190.. 207 ppm

CO2 = 3.4%

NO = 7 ppm

T = 283 C

Approx 50 minutes after lighting.

We can see that, throughout the course of one batch of fuel, the gasification processes are constantly shifting.

When first lit, we measured some CO in the flame. This makes sense because the flame is directly on the solid fuel, which is associated with production of CO and PM. However, we are not confident about the readings at this time and would not draw any strong conclusions.

Then, the “TLUD operation” emerges with a large yellow flame. This flame is running entirely on gas and comes out as jets from the secondary air holes. It is at this time that we see O2 get the lowest: it is being consumed in the oxidation reactions of combustion of volatiles. We also see CO2 at its highest, and CO at its lowest. The reaction kinetics are complex, with different reactions being favored at different temperatures and depending on heat transfer and species transport. Perhaps CO2 is high because H2O is available as water is driven off the drying fuel. It may also be that almost all CO is being converted to CO2 at this time in both the shift and oxidation reactions.

As pyrolysis of biomass proceeds, we see a transition to higher O2 %, lower CO2 %, decreased NO, and increased CO. This corresponds with the flame decreasing in size over time, with increasing amounts of blue flame and decreasing amounts of yellow flame.