[Gasification] Re: Gasification Digest, Vol 22, Issue 11
col
pesticolevy at optusnet.com.au
Thu May 11 09:55:01 CDT 2006
Hi all,
,,,,,, I find the discussion of burning velocities very interesting and
note that Kevin ask "what am I missing" as regards IC engines and piston
speed.
While the flame velocity may be important in fuel efficiency,surely
it is the explosion of the burnt gas in the cylinder that drives the
piston,not the flame velocity .
I had always presumed that the behaviour of a fuel in a cylinder
under considersble pressure was very different to combustion at atmospheric
pressure.This is ,of course ,an entirely non academic view of a retired
forest product's scientist.
----- Original Message -----
From: <gasification-request at listserv.repp.org>
To: <gasification at listserv.repp.org>
Sent: Thursday, May 11, 2006 9:21 PM
Subject: Gasification Digest, Vol 22, Issue 11
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> Today's Topics:
>
> 1. Burning velocity (Charles Coronella)
> 2. Re: ..back to defining gasification, was: cold/hot gas
> efficiency (Jigme Rangdrol)
> 3. Re: Burning velocity (Kevin Chisholm)
> 4. Re: Burning velocity (Daniel Chisholm)
> 5. Re: ..back to defining gasification, was: cold/hot gas
> efficiency (Arnt Karlsen)
> 6. Re: Properties of "hydrogen rich gas" (Arnt Karlsen)
> 7. Re: ..back to defining gasification, was: cold/hotgas
> efficiency (Dries Vansteenkiste)
> 8. Re: ..back to defining gasification (Jigme Rangdrol)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Wed, 10 May 2006 09:41:01 -0700
> From: "Charles Coronella" <coronella at unr.edu>
> Subject: [Gasification] Burning velocity
> To: gasification at listserv.repp.org
> Cc: rich_bain at nrel.gov, Ralph Overend <ralph_overend at nrel.gov>
> Message-ID:
> <1a042a880605100941kf91ee3ay1c44234d0d18b595 at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Tom,
>
> I don't understand why it might be useful to characterize the burning
> velocity of a fuel gas. I presume the burning velocity is a function of
the
> inherent homogeneous oxidation reaction kinetics. But the rate of
> combustion of fuel gases is typically limited by mass transfer
> considerations, isn't it? And that will vary greatly depending upon
> combustor configuration, especially rapid mixing of fuel and oxidant.
>
> As an academic researcher, I'm interested in identifying useful needs for
> the community, but, who's going to fund it? (US-DOE? yeah, right...)
>
> Chuck Coronella
>
> Date: Wed, 10 May 2006 07:04:16 -0600
> > From: Thomas Reed <tombreed at comcast.net>
> >
> >
> > BUT: It is relatively easy to make from all other fuels which are easy
> > to store and ship. It has a high burning velocity and can burn very
> > lean or very rich. And it has very low emissions compared to all other
> > fuels.
> >
> > The burning velocity of most fuels in air is 40-60 cm/sec. The burning
> > velocity of hydrogen is 300 cm/sec. The burning velocity of really pure
> > CO is 30 cm/sec, but a small amount of impurity makes it comparable to
> > all other fuels. So, "hydrogen rich gas" burns faster than most fuels
> > with a wider combustion limit.
> >
> > I wish that some laboratory would undertake the task of defining the
> > flame velocity and combustion limits of hydrogen rich gas. I have one
> > Dutch paper from the 1950s in my archives giving a linear dependence on
> > CO-H2 content up to 300 cm/sec and some combustion limits, but we need
> > more than that.
> >
> > Any volunteers?
> >
> > Yours truly,
> >
> > TOM REED THE BIOMASS ENERGY FOUNDATION
> >
> >
> >
>
>
> ------------------------------
>
> Message: 2
> Date: Wed, 10 May 2006 10:30:31 -0700
> From: Jigme Rangdrol <rangdrol at turboisp.com>
> Subject: Re: [Gasification] ..back to defining gasification, was:
> cold/hot gas efficiency
> To: gasification at listserv.repp.org
> Message-ID: <44622337.8060903 at turboisp.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Why should it require combustibility?
>
> Arnt Karlsen wrote:
>
> >On Wed, 10 May 2006 08:21:50 +0200, astrupgaard wrote in message
> ><20060510062143.TXLR21582.fep45.mail.dk at ag17276f29bb5e>:
> >
> >
> >
> >>- and that is why a gasifier definition should never include a demand
> >>for cooling of the gas! (Apparently that is the case in Californian
> >>legislation)
> >>
> >>
> >
> >..it should however require combustibility of the product gas in air,
> >say under standard athmosphaeric conditions like under standard
> >aviation conditions such as under the ICAO/ FAA standards,
> >15C/60F, 1013.25mb/760mmHg etc, which _any_ viable gasifier
> >can be set up to produce.
> >
> >
> >
>
>
>
>
> ------------------------------
>
> Message: 3
> Date: Wed, 10 May 2006 15:14:13 -0300
> From: "Kevin Chisholm" <kchisholm at ca.inter.net>
> Subject: Re: [Gasification] Burning velocity
> To: <coronella at unr.edu>, <gasification at listserv.repp.org>
> Cc: rich_bain at nrel.gov, Ralph Overend <ralph_overend at nrel.gov>
> Message-ID: <000101c67464$4967f860$889a0a40 at kevin28mxtjznn>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=response
>
> Dear Chuck
>
> I have a problem with "burning velocity" also. :-)
>
> A gasoline engine with a 4" stroke, running at 3600 RPM, does 60
revolutions
> per second. It thus takes 1/120 of a second for the piston to travel TDC
to
> BDC. This is an average piston speed of 40 feet per second. 300 CM/Second
is
> 3 meters per second, or basically 10 feet per second. This is 1/4 of the
> piston speed
>
> With "super fast hydrogen", the above numbers would suggest that it was
only
> 1/4 burned if it was ignited at TDC. Even if it was ignited at the start
of
> the compression stroke (the equivalent to 180 degrees of spark advance),
it
> would still only be 1/2 burned at the bottom of the power stroke (180
> degrees after TDC)
>
> We all know that IC engines with 4" strokes can work at 3600 rpm, but the
> above "flame speed analysis" says they can't.
>
> Could someone please tell me what I am missing here?
>
> Thanks!!
>
> Kevin
> ----- Original Message -----
> From: "Charles Coronella" <coronella at unr.edu>
> To: <gasification at listserv.repp.org>
> Cc: <rich_bain at nrel.gov>; "Ralph Overend" <ralph_overend at nrel.gov>
> Sent: Wednesday, May 10, 2006 1:41 PM
> Subject: [Gasification] Burning velocity
>
>
> Tom,
>
> I don't understand why it might be useful to characterize the burning
> velocity of a fuel gas. I presume the burning velocity is a function of
the
> inherent homogeneous oxidation reaction kinetics. But the rate of
> combustion of fuel gases is typically limited by mass transfer
> considerations, isn't it? And that will vary greatly depending upon
> combustor configuration, especially rapid mixing of fuel and oxidant.
>
> As an academic researcher, I'm interested in identifying useful needs for
> the community, but, who's going to fund it? (US-DOE? yeah, right...)
>
> Chuck Coronella
>
> Date: Wed, 10 May 2006 07:04:16 -0600
> > From: Thomas Reed <tombreed at comcast.net>
> >
> >
> > BUT: It is relatively easy to make from all other fuels which are easy
> > to store and ship. It has a high burning velocity and can burn very
> > lean or very rich. And it has very low emissions compared to all other
> > fuels.
> >
> > The burning velocity of most fuels in air is 40-60 cm/sec. The burning
> > velocity of hydrogen is 300 cm/sec. The burning velocity of really pure
> > CO is 30 cm/sec, but a small amount of impurity makes it comparable to
> > all other fuels. So, "hydrogen rich gas" burns faster than most fuels
> > with a wider combustion limit.
> >
> > I wish that some laboratory would undertake the task of defining the
> > flame velocity and combustion limits of hydrogen rich gas. I have one
> > Dutch paper from the 1950s in my archives giving a linear dependence on
> > CO-H2 content up to 300 cm/sec and some combustion limits, but we need
> > more than that.
> >
> > Any volunteers?
> >
> > Yours truly,
> >
> > TOM REED THE BIOMASS ENERGY FOUNDATION
> >
> >
> >
> _______________________________________________
> Gasification mailing list
> Gasification at listserv.repp.org
> http://listserv.repp.org/mailman/listinfo/gasification
> http://www.repp.org/discussiongroups/resources/gasification
>
>
>
> ------------------------------
>
> Message: 4
> Date: Wed, 10 May 2006 16:25:58 -0300
> From: Daniel Chisholm <dmc at danielchisholm.com>
> Subject: Re: [Gasification] Burning velocity
> To: Kevin Chisholm <kchisholm at ca.inter.net>
> Cc: rich_bain at nrel.gov, Ralph Overend <ralph_overend at nrel.gov>,
> gasification at listserv.repp.org, coronella at unr.edu
> Message-ID: <1147289159.18091.232.camel at strangejava.wort.ca>
> Content-Type: text/plain
>
> On Wed, 2006-10-05 at 15:14 -0300, Kevin Chisholm wrote:
> >
> > We all know that IC engines with 4" strokes can work at 3600 rpm, but
the
> > above "flame speed analysis" says they can't.
> >
> > Could someone please tell me what I am missing here?
>
> I suspect that the quoted flame speeds are at atmospheric pressure and
> ordinary temperature. In the higher pressure (density) and higher
> temperature gas in a cylinder at the moment of the ignition spark, the
> flame speed is likely higher. And as combustion progresses, not only is
> the continuing compression of the rising cylinder increasing the
> pressure density and temperature, but the volume is being reduced too.
> And the heat addition of the combustion is in turn increasing pressure
> and temperature (though not density).
>
> If I had to guess at the mechanics of gas flame speed, I would SWAG that
> flame speed is proportional to density (closer particles bump into each
> other more frequently), and also to the square root of the absolute
> temperature (i.e. mean particle speed - faster particles bump into each
> other more frequently).
>
> So if you ignite a charge at ~35BTDC, let's just assume that the
> temperature is 400C (from compression), and the volume is about 1/4 of
> max.
>
> the flame speed increase due to faster molecules would be
> sqrt(700K/300K) = 1.5X
>
> and the increase due to increased density would be 4X (gas is 4X
> denser).
>
> Combining these two, this would increase flame speed by 1.5*4 = 6X. So
> hydrogen (300cm/sec at atmos. temp and dens.) would have a flame speed
> of about 1800cm/sec, and pure CO (really slow at 30 cm/sec) would be
> 180cm/sec.
>
> To burn through that inch of headspace (call it 3cm), assuming the worst
> case of ignition at the end rather than the centre of the charge, would
> take (for slow-burning CO) 3cm/180cm/sec = 1/60th of a second.
>
> But it would actually take less than 1/60th of a second, that 180 cm/s
> is the _initial_ burn speed at ~35BTDC condition - remember, the burn
> speed is going to be increasing (hotter, denser gas), and the volume
> decreasing (piston still compressing), as the piston approaches TDC.
>
> So you see, I've just shown that an engine can run at 3600 rpm.... ;-)
>
>
>
> (for an extreme example of this, compare the burn speed of say a
> teaspoon of smokeless rifle powder in the open, to the burn speed of the
> same amount inside a loaded rifle cartridge. The former is about one
> second of a soft, quiet yellow flame. The latter is about 0.2-0.5ms,
> and anything but a soft quiet flame. Same thing going on - the burn
> rate increases as the charge burns, causing the pressure and temp to
> rise, and feed back into still further increasing the burn rate... there
> is an initial exponential growth rate)
>
>
> --
> - Daniel
> Fredericton, NB Canada
>
>
>
> ------------------------------
>
> Message: 5
> Date: Thu, 11 May 2006 01:42:34 +0200
> From: Arnt Karlsen <arnt at c2i.net>
> Subject: Re: [Gasification] ..back to defining gasification, was:
> cold/hot gas efficiency
> To: gasification at listserv.repp.org
> Message-ID: <20060511014234.5d0ea2c4.arnt at c2i.net>
> Content-Type: text/plain; charset=US-ASCII
>
> On Wed, 10 May 2006 10:30:31 -0700, Jigme wrote in message
> <44622337.8060903 at turboisp.com>:
>
> > Arnt Karlsen wrote:
> >
> > >On Wed, 10 May 2006 08:21:50 +0200, astrupgaard wrote in message
> > ><20060510062143.TXLR21582.fep45.mail.dk at ag17276f29bb5e>:
> > >
> > >
> > >
> > > >- and that is why a gasifier definition should never include a
> > > demand >for cooling of the gas! (Apparently that is the case in
> > > Californian >legislation)
> > >>
> > >>
> > >
> > > ..it should however require combustibility of the product gas in
> > > air, say under standard athmosphaeric conditions like under standard
> > > aviation conditions such as under the ICAO/ FAA standards,
> > > 15C/60F, 1013.25mb/760mmHg etc, which _any_ viable gasifier
> > > can be set up to produce.
> >
> > Why should it require combustibility?
>
> .."helps" legislators distinguish us from the incinerator people.
>
> --
> ..med vennlig hilsen = with Kind Regards from Arnt... ;o)
> ...with a number of polar bear hunters in his ancestry...
> Scenarios always come in sets of three:
> best case, worst case, and just in case.
>
>
>
> ------------------------------
>
> Message: 6
> Date: Thu, 11 May 2006 01:49:24 +0200
> From: Arnt Karlsen <arnt at c2i.net>
> Subject: [Gasification] Re: Properties of "hydrogen rich gas"
> To: gasification at listserv.repp.org
> Message-ID: <20060511014924.4089954d.arnt at c2i.net>
> Content-Type: text/plain; charset=US-ASCII
>
> On Wed, 10 May 2006 07:04:16 -0600, Thomas wrote in message
> <4461E4D0.5050109 at comcast.net>:
>
> > Dear Rant and All:
>
> ..I rant a lot, but my name's Arnt. ;o)
>
> > After all the oil and gas are gone or too expensive we will still have
> > "hydrogen rich gas" (our preferred name for producer gas, town gas,
> > syngas etc.) from biomass and coal by gasification and all other
> > fuels by reforming.
> >
> > We know the bad sides of this gas, since it was widely available to
> > the world from 1850 to 1950 and is coming back in China etc. It has
> > a low energy content relative to natural gas and propane, so is more
> > difficult to store and ship. The CO is deadly, so don't breathe it.
> >
> > BUT: It is relatively easy to make from all other fuels which are
> > easy to store and ship. It has a high burning velocity and can burn
> > very lean or very rich. And it has very low emissions compared to
> > all other fuels.
> >
> > The burning velocity of most fuels in air is 40-60 cm/sec. The
> > burning velocity of hydrogen is 300 cm/sec. The burning velocity of
> > really pure CO is 30 cm/sec, but a small amount of impurity makes it
> > comparable to all other fuels. So, "hydrogen rich gas" burns faster
> > than most fuels with a wider combustion limit.
> >
> > I wish that some laboratory would undertake the task of defining the
> > flame velocity and combustion limits of hydrogen rich gas. I have one
> > Dutch paper from the 1950s in my archives giving a linear dependence
> > on CO-H2 content up to 300 cm/sec and some combustion limits, but we
> > need more than that.
> >
> > Any volunteers?
>
> .."show me the money." ;o) There's some good stuff on this in Gengas,
> and I believe this part of your translation would be nice to see on a
> web site. ;o)
>
> > Yours truly,
> >
> > TOM REED THE BIOMASS ENERGY FOUNDATION
> >
> >
> >
> > Arnt Karlsen wrote:
> >
> > >On Wed, 10 May 2006 08:21:50 +0200, astrupgaard wrote in message
> > ><20060510062143.TXLR21582.fep45.mail.dk at ag17276f29bb5e>:
> > >
> > >
> > >
> > >>- and that is why a gasifier definition should never include a
> > >demand >for cooling of the gas! (Apparently that is the case in
> > >Californian >legislation)
> > >>
> > >>
> > >
> > >..it should however require combustibility of the product gas in air,
> > >say under standard athmosphaeric conditions like under standard
> > >aviation conditions such as under the ICAO/ FAA standards,
> > >15C/60F, 1013.25mb/760mmHg etc, which _any_ viable gasifier
> > >can be set up to produce.
> > >
> > >
> > >
> >
>
>
> --
> ..med vennlig hilsen = with Kind Regards from Arnt... ;o)
> ...with a number of polar bear hunters in his ancestry...
> Scenarios always come in sets of three:
> best case, worst case, and just in case.
>
>
>
>
> ------------------------------
>
> Message: 7
> Date: Thu, 11 May 2006 10:07:10 +0200
> From: "Dries Vansteenkiste" <Dries.Vansteenkiste at UGent.be>
> Subject: Re: [Gasification] ..back to defining gasification, was:
> cold/hotgas efficiency
> To: <gasification at listserv.repp.org>
> Message-ID: <001a01c674d1$e7924eb0$53c1c19d at UGent.be>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original
>
> ----- Original Message -----
> From: "Arnt Karlsen" <arnt at c2i.net>
> To: <gasification at listserv.repp.org>
> Sent: Thursday, May 11, 2006 1:42 AM
> Subject: Re: [Gasification] ..back to defining gasification, was:
> cold/hotgas efficiency
>
>
> > On Wed, 10 May 2006 10:30:31 -0700, Jigme wrote in message
> > <44622337.8060903 at turboisp.com>:
> >
> >> Arnt Karlsen wrote:
> >>
> >> >On Wed, 10 May 2006 08:21:50 +0200, astrupgaard wrote in message
> >> ><20060510062143.TXLR21582.fep45.mail.dk at ag17276f29bb5e>:
>
> >> > >- and that is why a gasifier definition should never include a
> >> > demand >for cooling of the gas! (Apparently that is the case in
> >> > Californian >legislation)
> >> >>
> >> >
> >> > ..it should however require combustibility of the product gas in
> >> > air, say under standard athmosphaeric conditions like under standard
> >> > aviation conditions such as under the ICAO/ FAA standards,
> >> > 15C/60F, 1013.25mb/760mmHg etc, which _any_ viable gasifier
> >> > can be set up to produce.
> >>
> >> Why should it require combustibility?
> >
> > .."helps" legislators distinguish us from the incinerator people.
> >
>
> extension of the question of Jigme (or did I misinterprete?):
> in analogy with the petrochemical industry, couldn't some components of
the
> gas be used as a feedstock in the chemical industry?
> in other words: is gas from biomass only produced for combustion?
> if not, this would call again for a very simple definition of a gasifier
>
>
>
> ------------------------------
>
> Message: 8
> Date: Thu, 11 May 2006 04:28:29 -0700
> From: Jigme Rangdrol <rangdrol at turboisp.com>
> Subject: Re: [Gasification] ..back to defining gasification
> To: gasification at listserv.repp.org
> Message-ID: <44631FDD.7050208 at turboisp.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Setting aside the ethical problems just for the moment.
>
> If the goal is to distance your chosen type of gasifier from the black
> brush strokes of the incinerator industries history, a requirement for
> combustibility is self defeating.
> In fact all use of the word combustion should be eliminated and the
> definition should be extremely simple and unique.
> A better definition for the Pols would be clearly understood by
> non-technical staffers [the folks who actually read the definitions]
> easy for "Experts" to sell [K street type experts] and difficult to pin
> down by anti-incinerators [the enemy].
>
> "A MSW Gasifier uses heat to extract fuel from MSW" Where MSW is any
> target feedstock.
>
> Ideally it would not even use the word "Heat".
>
> "A MSW Gasifier is a device that extracts fuel from MSW."
>
> Besides the ethical problem, all the gooblygook about temperature and
> mixture and on and on just gives the "Enemy" more ammunition and
> needlessly confuses and restricts the discussion
>
> It also runs the very real risk of painting all gasifiers with the same
> brush so that when one MSW gasifier [or chip or coal etc] fails or
> offends all the rest get needlessly dismissed out of hand - like
> incinerators.
>
> "A MSW fuel extractor is a device that extracts fuel from MSW."
>
> J.R.
>
>
> ------------------------------
>
> _______________________________________________
> Gasification mailing list
> Gasification at listserv.repp.org
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>
>
> End of Gasification Digest, Vol 22, Issue 11
> ********************************************
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