Ha ! ok speak too soon and you get your wish , yesterday’s daily run , i noticed no orange glow from the lighting/nozzle tube after putting the gas torch to it for 10 seconds ,normaly after pointing the gas gun under the drum for a few seconds i put my hand under the tube and see a reflection of the glow on my hand, but yesterday nothing , but i knew it was alight as i was getting gas and a flare from the other end after 2 mins , and engine fired up and ran for about 2 or 3 hours .
This morning i have emptied out about 100 litres of charcoal from the drum leaving a very pretty volcano on the bottom of my drum and covering up my boron carbide nozzle , anyway after carefully tapping away at my glass volcano i ended up with what is left of the Boron carbide nozzle all 1/2 inch of it , this first one was 1 and a half inches in length , so thats lasted inside 45days , and i worked out that would have been roughly 30 days running @ a average hourly rate of 4 hours , and thats about length of time i was getting from my home made refractory nozzles made out of store bought material .
Anyway i have this new supposedly tungsten/boron carbide nozzle to install now and shall be running that in a couple of hours time , again with no water drip or EGR ,and in the mean time i shall try and get hold of a proper Tungsten Carbide nozzle to play with .
Here are a few terrible quality pics taken on my phone just so you can get an idea
Hey Dave, Thanks for the info and sharing with us how your different nozzle materials hold up. Looks like the boron carbide is not the best choice either. I have my fingers crossed for the tungsten carbide nozzle.
Gary in PA
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.
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?
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 .
@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.
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
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?
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.
@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.
