a cooling solution with water so that the nozzle is infusible
6 Likes
Do we know what the temperatures with and without running exhaust and/or water to be able to melt the nozzles??
1 Like
In a biomass boiler core behind steel, you have a blade of water, it is found that the steel does not lamination, because behind, the water holds a constant temperature maintain by its controlled circulation speed, for the nozzle type gohin poulenc the process is identical, just control the water flow rate to get the desired cooling by having a water tank above to work in gravity.
2 Likes
i love this solution from Jeff Davis…
A baby Pedrick plate…
2 Likes
It is too early to call it a solution but thanks for the kind words! One mistake is that it should have protruded further into the produce because the out side of the producer gets hot enough to soften the plastic filter that is close to that hot spot.
The big out side pipe I would make a larger diameter. More heat sink and help preheat the water vapor and air. Tha water drips into this pipe that is welded to the back of the oxidation plate. I think this pipe will be called the outer pipe. This is the pipe with the elbow screwed to it.
The inner pipe is shorter in length. Diameter is just larger than the hole in the oxidation plate. It helps to cool the oxidation plate and preheat the steam/air. It might also focus the air stream.
However, this is just talk at this point. Ask me in two years, how is it holding up?
2 Likes
2 Likes
i also stumbled on this site, have some info about the nozzles and a lot of fun stuff to read, with drawings, in englisch
http://knowledgepublications.com/hydrogen/hydrogen_generator_gas_vol_5_detail.htm
3 Likes
Loving my afternoon reading material Thanks Koen .
2 Likes
Regarding silicon carbide nozzles, I found these (and similar) made in a sintering process. …seems inexpensive and perhaps worth a try?
1 Like
Thanks Steve , i have just ordered one ,and should get it by the end of September , i’m not sure if it will hold up any better than the Boron carbide one i tried, but i have gone this far on my search for the holy grail of nozzles so why stop now .
Will update when i get around to testing this one out , should be ready for a new nozzle in about 4 or 5 weeks if the one i have in is anything like the Boron one i took out the other day .
Dave
2 Likes
Great spirit…
I have read another one, forgot whom’s…
“Don’t bother to live near me for a day, try to imagine being in my brain and hold out for 10 seconds…”
Yup, the holy grail has many forms…
@ Steve, Smaresca: wow, great find
1 Like
Steve,
How would you attach this to something? Might make good nozzles for a ceramic blanket wood gasifier.
Rindert
@r_wesseling I’ve been chewing on that question myself. I think it would be feasible to fix it within a containing (probably sacrificial) tube using refractory mortar of some kind. Cutting a groove in the outer surface of the cylinder would probably help too.
I think these alumina bushings are another potentially viable solution because they have a step that would make it easy to be held in a pipe cap or something.
Other stuff from the glass working industry is likely to be helpful…molten glass chemistry is extremely weird at high temp, and the materials involved tend to be super tough.
On the other hand, such things are usually considered consumables…which is probably the most useful hint here despite the temptation to find a long-lasting nozzle material: Simple and replaceable nozzles are probably the best route, even if some of the more exotic materials would suffice. Of course, if we find that some carbide or alumina material lasts years, then that’s probably a great trade-off.
2 Likes
Steve,
A factor that we have to consider is the different rates of thermal expansion for different materials. Alumina - 8.1, Steel - 11-12.5, Silicon Carbide 2.77 units (10-6 m/(m K)).
https://www.engineeringtoolbox.com/linear-expansion-coefficients-d_95.html
Still, I know it can be done somehow. A.S Richards, see post #87, is attaching silicon carbide to steel. And I have seen a lot of silicon carbide grinding cones with a steel insert that allow them to be used with an angle grinder.
Rindert
1 Like
I ordered a couple of these as well. BTW, so far no degradation on my copper nozzle with 1/4 wall thickness, but I only have 100+ miles on my MGB. Also no corrosion on one-ended horizontal copper nozzle run for a few hours with no EGR on a small gasifier. I am looking for something other than copper for those wanting a less expensive, but durable option for small engines.
I’m thinking that I will slip the silicone carbide tube about half way over a 1/2" SS nipple. The expansion of SS is far greater than the silicon carbide so must be much smaller diameter than the nozzle. My thinking is that 1/2" will give good air velocity and the carbide will take the reaction temperature and prevent catastrophic oxidation of the recessed SS nipple.
The nozzle will hang loosely in a refractory cradle/notch allowing back and forth/end to end movement without crawling off of the nipple. The slight venturi effect sucking in CO2 from reaction into the nipple end of the nozzle should not overwhelm the entering air volume and might even help cool the reaction a bit?
Other’s thoughts are welcome.
3 Likes
An insert for grinding isnt surprising, as the grinding and spinning in air will largely dissipate grinding heat. If you applied heat to the steel mandrel I wouldn’t be surprised to see it split the carbide.
1 Like
@taitgarry00 Agree, definitely critical given the wildly different expansion coefficients between the materials (and the relative brittleness of carbide ceramics).
@bsoutherland’s idea (post 106) could work here because it can tolerate some degree of slop. And Bruce a passing thought – given the movement/vibration while driving in the MG, probably want to cushion with a bit of ceramic wool or something so it doesn’t bang around too much when everything is at operating temp.
2 Likes
Garry, Steve,
The website I found for A.S. Richards in post #87 seems to have gone dead. Maybe they found out I was talking about them.
But here is one with a reinforcing pipe in the center. https://www.jms-se.com/catalog/Silicon_Carbide_Silicon_Nitride_Protection_Tubes_Ordering_Page.pdf
How is this even possible? Are ALL these guys playing shenanigans?!?!
Rindert
1 Like
When i bought my bag of refractory cement they asked me what grade i wanted and explained the alumina content in each type , so i explained what i wanted it for , and they mentioned that 90% alumina content would probably be too much because of the thermal shock of the material and they suggested trying a 76% alumina filled bag instead , i have made about 8 nozzles so far since buying it and so far they all stood up to the temp change that water drip causes and heating and cooling off of the nozzles , and only changed them over when they had more or less melted away , and thats around the 120 hour of use time .
Bruce instead of slipping the carbide over the SS tube why don’t you slip the silicon carbide just a few mm inside of a SS tube thats ground out to a plug fit for the carbide ,thats how i have done mine and no problem with expansion at all .they all seem to stay in place, plus when they have oxidized away down close to the SS nipple the shut of tap on the air inlet gets warm/hot and thats a early sign that the nozzle needs changing .
Dave
6 Likes