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From: lektric.dan on 21 May 2010 13:57 (no, this isn't spam...) My boss came to me with another brain-stretching problem. We're looking at designs for a new microreactor. We need to heat a section of 1/2" dia. quartz tubing to 1000 oC in 1 second (heating zone is about 1 inch. How to go about this? Inductive coil? Radiant quartz lamps? RF? Microwave? What else is out there? Would prefer commercial to build-it-ourselves. (the material that will be going through the reactor is the same finely ground organic material that resembles pepper or oregano).
From: Bob Eld on 21 May 2010 14:16 <lektric.dan(a)gmail.com> wrote in message news:6cb52649-d4f5-4c75-aff8-5d8d93340791(a)j9g2000vbp.googlegroups.com... > (no, this isn't spam...) > My boss came to me with another brain-stretching problem. We're > looking at designs for a new microreactor. We need to heat a section > of 1/2" dia. quartz tubing to 1000 oC in 1 second (heating zone is > about 1 inch. How to go about this? Inductive coil? Radiant quartz > lamps? RF? Microwave? What else is out there? Would prefer > commercial to build-it-ourselves. > (the material that will be going through the reactor is the same > finely ground organic material that resembles pepper or oregano). A thousand deg C in one second?? Have you calculated the power to do that? What's in the tube. Pepper or oregano? Organics will just carbonize. You need to be more specific. Obviousy methods that require electrical conductivity wont work well if at all. Most likely such a reactor would use resistance heating with nichrome or kanthal or other heating wire surrounding the quartz tube. Dump tons of power for a short time to get the required rate. How about using a silicon carbide tube and running current through the carbide to heat it? It would help to know what you are trying to do, with not only the rate but max temp and power required.
From: ian field on 21 May 2010 16:48 "Bob Eld" <nsmontassoc(a)yahoo.com> wrote in message news:ht6ima$hj1$1(a)news.eternal-september.org... > > <lektric.dan(a)gmail.com> wrote in message > news:6cb52649-d4f5-4c75-aff8-5d8d93340791(a)j9g2000vbp.googlegroups.com... >> (no, this isn't spam...) >> My boss came to me with another brain-stretching problem. We're >> looking at designs for a new microreactor. We need to heat a section >> of 1/2" dia. quartz tubing to 1000 oC in 1 second (heating zone is >> about 1 inch. How to go about this? Inductive coil? Radiant quartz >> lamps? RF? Microwave? What else is out there? Would prefer >> commercial to build-it-ourselves. >> (the material that will be going through the reactor is the same >> finely ground organic material that resembles pepper or oregano). > > A thousand deg C in one second?? Have you calculated the power to do that? > What's in the tube. Pepper or oregano? Organics will just carbonize. You > need to be more specific. Obviousy methods that require electrical > conductivity wont work well if at all. Don't know about quarz, but glass becomes conductive at red heat.
From: lektric.dan on 21 May 2010 16:48 On May 21, 1:16 pm, "Bob Eld" <nsmontas...(a)yahoo.com> wrote: > > A thousand deg C in one second?? Have you calculated the power to do that? Yep. A "metric boatload" depending upon method and effeciency. > What's in the tube. Pepper or oregano? "A finely ground organic substance like pepper or oregano" is all I can tell you in a public newsgroup. It's legal, if that's what you're thinking. > Organics will just carbonize. That's kinda the idea. Actually, they will pyrolyze (decompose by heating in the absence of oxygen). > You need to be more specific. Obviousy methods that require electrical > conductivity wont work well if at all. > > Most likely such a reactor would use resistance heating with nichrome or > kanthal or other heating wire surrounding the quartz tube. Dump tons of > power for a short time to get the required rate Could do that...it would have to be very high gauge wire to carry the current (power) needed to get that hot/quick. Why would this be better than a series of quartz lamps? > How about using a silicon carbide tube and running current through the > carbide to heat it? That's an idea...I'll pass it by the boss. > It would help to know what you are trying to do, with not only the rate but > max temp and power required. If you promise not to tell anyone - we're designing a micropyrolysis reactor. You have the specs I have about reactor (section) design and heating requirements. The only other thing I can tell you is that we will probably use either nitrogen or argon as a carrier gas. Sorry I have to be so vague. I'm just looking for general ideas and suggestions for technology right now. Don't be upset you can't design the entire heating system for me (grin).
From: Bob Eld on 21 May 2010 17:25
<lektric.dan(a)gmail.com> wrote in message news:d43e9f5c-c0b6-478b-83c1-597cb0f7ef1e(a)m4g2000vbl.googlegroups.com... On May 21, 1:16 pm, "Bob Eld" <nsmontas...(a)yahoo.com> wrote: > > A thousand deg C in one second?? Have you calculated the power to do that? Yep. A "metric boatload" depending upon method and effeciency. > What's in the tube. Pepper or oregano? "A finely ground organic substance like pepper or oregano" is all I can tell you in a public newsgroup. It's legal, if that's what you're thinking. > Organics will just carbonize. That's kinda the idea. Actually, they will pyrolyze (decompose by heating in the absence of oxygen). > You need to be more specific. Obviousy methods that require electrical > conductivity wont work well if at all. > > Most likely such a reactor would use resistance heating with nichrome or > kanthal or other heating wire surrounding the quartz tube. Dump tons of > power for a short time to get the required rate Could do that...it would have to be very high gauge wire to carry the current (power) needed to get that hot/quick. Why would this be better than a series of quartz lamps? > How about using a silicon carbide tube and running current through the > carbide to heat it? That's an idea...I'll pass it by the boss. > It would help to know what you are trying to do, with not only the rate but > max temp and power required. >If you promise not to tell anyone - we're designing a micropyrolysis >reactor. You have the specs I have about reactor (section) design and >heating requirements. The only other thing I can tell you is that we >will probably use either nitrogen or argon as a carrier gas. Sorry I >have to be so vague. I'm just looking for general ideas and >suggestions for technology right now. Don't be upset you can't design >the entire heating system for me (grin). Here's a thought: Heat the carrier gas in a separate tube long enough to insure the gas easily gets to temp. That way you shouldn't have to dump so much instantaneous power to get the rate. Then inject the hot gas into the reactor stream. Now, the rate of temp change of the material only involves the carrier and the reactant and not the quartz, heating elements, etc. There would be much less thermal mass to worry about. Furthermore, you can control the temp and the ratio of reactants precisely |