That, I will agree with :) If anyone out there has more information on the impact of lower than atmospheric pressure on the temperature difference adjustment that it causes on the principal of water to gas shift, I would greatly appreciate it.
Greg. On Sun, Mar 18, 2012 at 10:30 AM, <[email protected]> wrote: > Greg, > > I can't answer why you are seeing higher temps than calculated. It > certainly does prove the impact of moisture on gasification, though. > > Stephen > -----Original Message----- > From: Greg Manning <[email protected]> > To: Discussion of biomass pyrolysis and gasification > <[email protected]> > Sent: Sun, Mar 18, 2012 11:12 am > Subject: Re: [Gasification] On the subject of H2 and O (was N2 removal) > > lol, Stephen > I understand you, it's just that in the core, in the restriction, I > was reading Tom Reeds Superficial Velocity paper, and IMO the flow > rate at 4 in/wc suction would cause quite a drop with a velocity of > +300 ft/sec. (NOT VOLUME) > What I'm saying is that when there is too much moisture I understand > the energy transfer to the water is quite great, and the W/G Shift is > low (or none), however, with inlet air that has been run through an > "air dryer" (like the ones used in automotive paint booths) AND, very > dry feedstock, the core temperature (just under the hearth) is WAY > higher than if I run just normal air, and reasonably dry feedstock, > The difference is greater than the energy balance that I calculate, > so one of two is the answer, > A) my balance is skewed, OR, > B) there is "extra" heat energy in the later portion of the process, > that I cannot account for. (assuming a greater W/G shift, would bring > it back in line) > Greg > On Sun, Mar 18, 2012 at 9:54 AM, <[email protected]> wrote: >> Hi Greg, >> >> Sure. Let's to a simple example so my feeble mind can follow it. When I >> drop cold chips in my gasifier there is some moisture content in the >> chips...this is liquid water in the wood cells. As the chips burn down >> into >> the hearth they get hot and the water changes to steam. This phase change >> absorbs some amount of energy. Then as the steam goes through the char, >> some of it does the water gas shift if there is enough heat. This absorbs >> even more energy. The remaining steam ends up as condensate in the >> cooler. >> >> The steam produced in cavitation is like putting water in a bell jar and >> pulling a vacuum. If there is enough vacuum the water will boil, >> converting >> it's temperature into energy for the phase change. Eventually you end up >> with a chunk of ice in the bell jar. >> >> The water gas shift will not happen in the phase change because there >> isn't >> sufficient activation energy availble to make the reaction go. If it did >> work that way, there would be hydrogen bubbles coming off boat propellers. >> That would make a COOL rooster tail! >> >> Gasifiers do not run a low enough pressure to vaporize the water, like the >> bell jar. I can get the numbers if you want, but you need to be in -13psi >> range. That's way more than we pull. >> >> Any clearer or still muddy?? >> >> Stephen >> -----Original Message----- >> From: Greg Manning <[email protected]> >> To: Discussion of biomass pyrolysis and gasification >> <[email protected]> >> Sent: Sun, Mar 18, 2012 10:09 am >> Subject: Re: [Gasification] On the subject of H2 and O (was N2 removal) >> >> Hi Stephen, thanks for the reply. >> OK, I somewhat understand you, BUT, wouldn't water be doing a phase >> change in the core of a gasifier as well ? >> What I was getting at, is if steam is produced in cavitation in cold >> water, then wouldn't the shift effect also happen within the core >> during phase transition (from water as a liquid, to water as a vapor, >> when heated by the core) within the same boundaries of effect as water >> to steam in the trailing edge of a propeller ? (all of these >> situations involve lower that normal pressure zones). >> Aren't contrails produced in water vapor on the wing tips of an >> airplane because of this same pressure drop phase shift, causing a >> dew-point change? >> The core of most gasifiers runs in a dynamic lower than atmospheric >> pressure ( a very low internal barometric pressure) (suction based >> units), so the same shifts should apply during phase transition, >> shouldn't they ? >> I understand that a pressure fed gasifier would behave differently >> (and I've personally observed this) than a suction based one, I'm >> speaking about suction based gasifiers. >> Somewhat lost, >> Greg >> On Sun, Mar 18, 2012 at 8:26 AM, <[email protected]> wrote: >>> Greg, >>> >>> The energy doesn't change. The bond energy in the water is constant >>> regardless of pressure. >>> >>> The cavitation issue is different. It is a phase change phenomenon, not >>> a >>> chemical change one. >>> >>> Stephen >>> -----Original Message----- >>> From: Greg Manning <[email protected]> >>> To: Discussion of biomass pyrolysis and gasification >>> <[email protected]> >>> Sent: Sun, Mar 18, 2012 9:02 am >>> Subject: [Gasification] On the subject of H2 and O (was N2 removal) >>> >>> Greetings List. >>> Since we are speaking input air, I thought I might ask a somewhat >>> related question. >>> Water gas shift. I know there are many that have talked about this, >>> and I understand the basics. >>> However, here is the question. >>> At what negative pressure ( negative in/wc) does the shift move down >>> the temperature scale, to the point of being within the 1000 - 1200 c >>> area ? >>> We all know that propeller cavitation produces steam in water that is >>> 10 c (or there abouts), I have to assume (not being a chemist) that >>> the same negative pressure effect would also apply to other principals >>> when dealing with water. >>> -- >>> Regards, >>> Greg Manning, >>> Brandon, Manitoba, Canada >>> _______________________________________________ >>> Gasification 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/gasification_lists.bioenergylists.org >>> for more Gasifiers, News and Information see our web site: >>> http://gasifiers.bioenergylists.org/ >>> >>> >>> _______________________________________________ >>> Gasification 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/gasification_lists.bioenergylists.org >>> >>> for more Gasifiers, News and Information see our web site: >>> http://gasifiers.bioenergylists.org/ >>> >> -- >> Regards, >> Greg Manning, >> Brandon, Manitoba, Canada >> _______________________________________________ >> Gasification 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/gasification_lists.bioenergylists.org >> for more Gasifiers, News and Information see our web site: >> http://gasifiers.bioenergylists.org/ >> >> >> _______________________________________________ >> Gasification 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/gasification_lists.bioenergylists.org >> >> for more Gasifiers, News and Information see our web site: >> http://gasifiers.bioenergylists.org/ >> > -- > Regards, > Greg Manning, > Brandon, Manitoba, Canada > _______________________________________________ > Gasification 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/gasification_lists.bioenergylists.org > for more Gasifiers, News and Information see our web site: > http://gasifiers.bioenergylists.org/ > > > _______________________________________________ > Gasification 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/gasification_lists.bioenergylists.org > > for more Gasifiers, News and Information see our web site: > http://gasifiers.bioenergylists.org/ > -- Regards, Greg Manning, Brandon, Manitoba, Canada _______________________________________________ Gasification 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/gasification_lists.bioenergylists.org for more Gasifiers, News and Information see our web site: http://gasifiers.bioenergylists.org/
