On the first 2 hour run I got 8 oz of water and 2 ounces of tar. Hearth hit 1200 C. Rag on top of packed bed was well coated and dirty. Much rust on lid of filter and grate.
On the second run of only 30 minutes I got the same amount of liquid in the jar. Hearth hit 540 C. Reactor vacuum was 4". Vacuum at ignition port was 1".
Running wood fireplace pellets.
The questions:
Do I need to run a Totti or other device to help with moisture and tar processing?
Was the charcoal in the reactor to start what gave me the high temps on the first run?
How do I drive the reactor to the 600 C range? Will it help the tar?
1
3 replies to this topic
#2
bear@apl
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Posted 12 May 2011 - 07:54 AM
Hi Driven,
Standard wood pellets are a bit on the fine side for the GEK.
If you had a starting load of coarse charcoal in the reduction bell this may have given those first high temperature results at lower reactor pull rates.
Once things settle in on pellets, pulling 4 inH2O is going to be low to maintain reasonable temperatures (the finer material packs the reduction bell more, leading to lower flows at a given reactor vacuum). The pressure ratio of 1/4 = 0.25 (P_comb/P_reactor) indicates a constricted flow through the reduction bell. When automating systems, we start shaking the grate more frequently when the ratio falls below 0.3.
In short, for pellets you'll need to run the reactor at a higher vacuum to maintain reasonable temperatures. Ideally you want to see the top of reduction above 800°C to get reasonable tar cracking.
This graph shows temperatures vs. reactor vacuum with different fuels. You can see pellets ran cooler for a given reactor vacuum.
Cheers,
Bear
Standard wood pellets are a bit on the fine side for the GEK.
If you had a starting load of coarse charcoal in the reduction bell this may have given those first high temperature results at lower reactor pull rates.
Once things settle in on pellets, pulling 4 inH2O is going to be low to maintain reasonable temperatures (the finer material packs the reduction bell more, leading to lower flows at a given reactor vacuum). The pressure ratio of 1/4 = 0.25 (P_comb/P_reactor) indicates a constricted flow through the reduction bell. When automating systems, we start shaking the grate more frequently when the ratio falls below 0.3.
In short, for pellets you'll need to run the reactor at a higher vacuum to maintain reasonable temperatures. Ideally you want to see the top of reduction above 800°C to get reasonable tar cracking.
This graph shows temperatures vs. reactor vacuum with different fuels. You can see pellets ran cooler for a given reactor vacuum.
Cheers,
Bear
#3
Driven Energy
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Posted 12 May 2011 - 02:12 PM
If I add a fixed pull such as an engine, can I decrease nozzle size to increase vacume? Or is there another way?
#4
Driven Energy
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Posted 13 May 2011 - 09:48 PM
I did another run. With the most my compressor could put out and a lot of grate shaking.....
I got 736C at the hearth and 775C below. The vac at the ignition port was 3 3/4" and blow was 6 1/4".
It flared a ton of gas. I think it would take a large engine to produce that much suck. Maybe pellets are not going to work, even for testing.
I got 736C at the hearth and 775C below. The vac at the ignition port was 3 3/4" and blow was 6 1/4".
It flared a ton of gas. I think it would take a large engine to produce that much suck. Maybe pellets are not going to work, even for testing.
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