See comments below. On Tue, May 14, 2013 at 6:03 PM, Tuong DoDuc <[email protected]> wrote: > Thanks Paul Oliver, > > I went through your presentation several times before. > I must say that It is very convincing and inspiring as well. > > Regarding the continous feed concept, I think it is a trade-off.
It's not really a trade-off of equals. So much depends on the application. If someone needs to cook a simple meal, why use a continuous gasifier? Cooking a meal is generally a batch process. Does it make sense to situate a complicated and rather large continuous gasifier in an ordinary household kitchen? It is quite messy to be loading rice hulls and scrapping out char in a kitchen where food is being prepared. Why not offer the user a device that is small, lightweight and mobile? I once designed and tested a "V"-shaped gasifier with updraft and downdraft barrels. This concept works to a limited extent, but only in batch mode. Even then, the syngas contained a lot of CO2. Rice hulls often have a negative angle of repose, and they easily bridge when confined to small spaces. The moment bridging occurs, a lot of CO2 is generated, and the reactor overheats. For this reason it is ideal that rice hulls are not in motion within the gasification process. I also abandoned the the concept of a double-barrel reactor because it is quite costly to fabricate. Imagine the cost of making such a reactor in high-quality stainless steel. Thanks. Paul > One one side, we will tell the users all the pros anc cons and let them > decide to choose what they like. > In this case, we will leave several different options for the users by a > field test of different gasifier models. > The user will tell. At this development stage of the continuous gasifier, I > can't tell which (batch or continuous) suits the user most. Especially, > there is no one-size-fits-all solution > > Best regards, > > Tuong > > > On Tue, May 14, 2013 at 10:12 AM, Paul Olivier <[email protected]> > wrote: >> >> The moment one goes from batch to continuous, the process gets really >> complicated. Nothing beats the simplicity of a static batch reactor. >> It provides ideal gasification conditions. The problem regarding the >> length of the batch cycle can be overcome if the fuel is densified. If >> the reactor is filled with pellets, the length of the cycle can be >> extended to well over five hours. Imagine: for a five full hours, the >> operator does not have to intervene. There is no loading of rice hulls >> or scrapping out of biochar during this entire period. >> >> https://dl.dropboxusercontent.com/u/22013094/Paper/Presentations/Gasification.ppsx >> The time to empty, reload and relight a batch reactor is less than one >> minute. >> Several reactor tubes can be operated at the same time. >> >> Thanks. >> Paul Olivier >> >> >> On Tue, May 14, 2013 at 8:23 AM, Tuong DoDuc >> <[email protected]> wrote: >> > Dear Dr.TLUD, Paul Oliver, and others, >> > >> > The team in SNV Vietnam is adopting the continous gasifier model >> > developed >> > by Belonio. The manual has been obtained from the CRHET. >> > Watch our first propotype: http://www.youtube.com/watch?v=xQGS-VQIj5M >> > We were able to control the fire, load fuel without affecting the fire, >> > and >> > easily remove char at the bottom of the reactor. >> > >> > We also adopted the computer fan-casing by a cheaper, more popular fan >> > in >> > Vietnam (often used for coal and fixed wood stove). Fan costed 2USD >> > (while >> > to replicate Belonio's fan-casing, we bought the adapter for 5USD and a >> > computer fan for 1.5USD) >> > >> > However, this is just our first step and we still have so many problems >> > to >> > fully control the fire and ease the operation. >> > 1) For instance, uncontrolled moment happened when combustion occurs >> > rigt on >> > top of the fuel hopper, a lot of smoke was produced and later the fire >> > burnt >> > the fan. >> > https://www.dropbox.com/s/43fkjs0axuye4oj/uncontrollable_moment.jpg >> > https://www.dropbox.com/s/rd1g1cg0a9ue8qt/fan_casing.jpg >> > >> > 2) Another problem is that a lot of tar is produced. It deposits on pot >> > bottom, burner and other part of the stove. That would also harm the >> > user. >> > An idea is to create a layer of char in the burner pipe (to filter the >> > tar). >> > Not tried yet. >> > >> > 3) We observes 5-10% of the gas leaked out through the char removal >> > door. We >> > burnt them, but user may not know (or they simply just don't care) that >> > it >> > is toxic. >> > >> > 4) One more, it is very hard to control the final minutes of the >> > gasificatoin process. It always cause inverted combustion to the fuel >> > hopper. >> > >> > By this email, I would like to ask if some of you have done similar work >> > with continuous gasifier like this to share more experience. We can thus >> > reduce our time and effort in localizing this technology. >> > >> > Best regards, >> > >> > Do Duc Tuong, >> > >> > Renewable Energy Advisor >> > SNV Vietnam >> > >> > >> > >> > _______________________________________________ >> > Stoves mailing list >> > >> > to Send a Message to the list, use the email address >> > [email protected] >> > >> > to UNSUBSCRIBE or Change your List Settings use the web page >> > >> > http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org >> > >> > for more Biomass Cooking Stoves, News and Information see our web site: >> > http://stoves.bioenergylists.org/ >> > >> > >> >> >> >> -- >> Paul A. Olivier PhD >> 26/5 Phu Dong Thien Vuong >> Dalat >> Vietnam >> >> Louisiana telephone: 1-337-447-4124 (rings Vietnam) >> Mobile: 090-694-1573 (in Vietnam) >> Skype address: Xpolivier >> http://www.esrla.com/ >> >> _______________________________________________ >> Stoves mailing list >> >> to Send a Message to the list, use the email address >> [email protected] >> >> to UNSUBSCRIBE or Change your List Settings use the web page >> >> http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org >> >> for more Biomass Cooking Stoves, News and Information see our web site: >> http://stoves.bioenergylists.org/ >> > > > _______________________________________________ > Stoves mailing list > > to Send a Message to the list, use the email address > [email protected] > > to UNSUBSCRIBE or Change your List Settings use the web page > http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org > > for more Biomass Cooking Stoves, News and Information see our web site: > http://stoves.bioenergylists.org/ > > -- Paul A. Olivier PhD 26/5 Phu Dong Thien Vuong Dalat Vietnam Louisiana telephone: 1-337-447-4124 (rings Vietnam) Mobile: 090-694-1573 (in Vietnam) Skype address: Xpolivier http://www.esrla.com/ _______________________________________________ Stoves mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org for more Biomass Cooking Stoves, News and Information see our web site: http://stoves.bioenergylists.org/
