I ran my GEK for the first two hours today. Reactor temps at the hearth restriction were 960-1200 C. I was running lignetics pellets and got about 1" of condensate in the mason jar. This seems like a lot. Is this typical? How can I reduce the moisture? Also, how hot is too hot in the reactor?
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Moisture from wood pellets.
Started by Driven Energy, Apr 30 2011 03:43 AM
2 replies to this topic
#2
jimmason
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Posted 30 April 2011 - 05:33 AM
this is an odd combination of factors. if this hot in the reactor you'd think it would be more difficult to have condensation in the cyclone can. but some counter-intuitive scenarios can create this situation.
we rarely see over 1000c at the restriction. if it goes above this it usually means there is a bridge and the hearth has voided. or, the bell has packed up completely with fines and the entire show is happening right at the top and temps can similarly spike.
an inch of condensation is not unusual in cold weather running. once the weather is non winter, we usually do not get any condensation in the cyclone jar, only soot. you can insulate the cyclone to get the same result in colder weather, but unless you are using the totti components, you are trying to maximize passive cooling in the downstream components. either way, it better to get your condensate only in the filter base. there is a 4" or so pool area at the under the filter grate to hold condensate water.
if you are getting an usual amount of condensate in the cyclone, it might also follow that reduction is not completing in the hearth. this actually could relate to high temps at the restriction. if you have packed up the bell completely with fines, you'll get very high temps at the top, and little reduction on the way out, so you'll have a large amount of h20 in the gas, thus more to condense.
given that you are running pellets, and pellets can easily degrade to fines in the reduction section, i'll go with the later theory for the moment.
can you give us more details on the pellets? size, shape, hardness, material? also what pull rates are you seeing on the manometer?
if you want to see if the bell is packing, you can switch one leg of the manometer to the lighting port, which gives you the pressure right at the nozzles in the bed, before the hearth section. monitoring the ratio between the combustion area and post reduction will show you when the bed starts packing. you want to see a ratio of about 0.3:1 nozzle:bed pressure ratio drop. this is the measurement and ratio we use to determine when to shake the grate on the power pallet.
thanks for posting about what you are seeing.
jim
we rarely see over 1000c at the restriction. if it goes above this it usually means there is a bridge and the hearth has voided. or, the bell has packed up completely with fines and the entire show is happening right at the top and temps can similarly spike.
an inch of condensation is not unusual in cold weather running. once the weather is non winter, we usually do not get any condensation in the cyclone jar, only soot. you can insulate the cyclone to get the same result in colder weather, but unless you are using the totti components, you are trying to maximize passive cooling in the downstream components. either way, it better to get your condensate only in the filter base. there is a 4" or so pool area at the under the filter grate to hold condensate water.
if you are getting an usual amount of condensate in the cyclone, it might also follow that reduction is not completing in the hearth. this actually could relate to high temps at the restriction. if you have packed up the bell completely with fines, you'll get very high temps at the top, and little reduction on the way out, so you'll have a large amount of h20 in the gas, thus more to condense.
given that you are running pellets, and pellets can easily degrade to fines in the reduction section, i'll go with the later theory for the moment.
can you give us more details on the pellets? size, shape, hardness, material? also what pull rates are you seeing on the manometer?
if you want to see if the bell is packing, you can switch one leg of the manometer to the lighting port, which gives you the pressure right at the nozzles in the bed, before the hearth section. monitoring the ratio between the combustion area and post reduction will show you when the bed starts packing. you want to see a ratio of about 0.3:1 nozzle:bed pressure ratio drop. this is the measurement and ratio we use to determine when to shake the grate on the power pallet.
thanks for posting about what you are seeing.
jim
#3
Driven Energy
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Posted 01 May 2011 - 04:03 AM
I am running the basic Lignetics wood stove pellets. They are 1/4" ish diameter by 3/4" long. I know they suck up moisture and thinking about it they were stored out back at the hardware store.
I flared for two hours and only burned about half a bag. I had to keep the manometer down in the 1-3" to keep it from going into the 100 Deg. range. It seemed like I could have melted the thing down if I wanted to. I will see what the ignition port vac. looks like.
I flared for two hours and only burned about half a bag. I had to keep the manometer down in the 1-3" to keep it from going into the 100 Deg. range. It seemed like I could have melted the thing down if I wanted to. I will see what the ignition port vac. looks like.
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