RES: [Gasification] RE: Bagasse uses

Fri May 5 09:46:46 CDT 2006

Hi Luiz;

Late reply --

The fire tube boilers are just as efficient for heat transfer as any other
style -- but are limited in the ability to super heat or run at pressure --
steam -- thus can only produce low quality steam. Which is very inefficient
in transferring heat to mechanical power.

The ORC turbines using refrigerant as working fluid get the same working --
heat to power -- efficiencies at these temperatures as a mid pressure/temp
steam boiler would at 1000 F or greater.

However -- the ORCs do it at less cost and much great reliability.

ORMAT even goes so fat to suggest using a thermal oil at no pressure as
heat transfer medium -- then the fire tube boiler can operate at the 450 --
500 F range -- and reaps even greater efficiencies.

As mentioned -- these system exist and have for many years -- and all is
well proven.

But the ability for conventional thermal power plant operators to grasp
these concepts is rare indeed.

It seems to take at least 100 years to introduce changes in thermal power
plant concepts -- very entrenched field of endeavor.

Peter

At 02:42 PM 4/18/2006 -0300, luiz.pellegrini wrote:
>
>Dear Peter,
>
>I quite didn't understand your point. Are you proposing the use of fire tube
>boilers? It doesn't seem very efficient to me... I mean, why should I
>produce steam in a low pressure saturate conditions, if I may consume the
>same amount of bagasse to produce superheated steam?
>In Brazil, and I believe in other countries too, sugarcane mills use
>cogeneration systems based on bagasse water tube boilers, producing
>superheated steam at 21-60 bar... They got almost (in Brazil, all) all power
>and heat they need.
>Studies that are currently being developed aim at ways to reduce steam
>consumption in the process and/or increasing the power generation.
>I remember you that gasification systems are only feasible if there is a
>significant reduction in current mills.
>I hope I am discussing things that are relevant.
>
>Regards,
>
>Luiz F. Pellegrini
>Brazil
>
>-----Mensagem original-----
>De: gasification-bounces at listserv.repp.org
>[mailto:gasification-bounces at listserv.repp.org] Em nome de Peter Singfield
>Enviada em: terça-feira, 18 de abril de 2006 12:30
>Para: gasification at listserv.repp.org
>Assunto: [Gasification] RE: Bagasse uses
>
>
>Manuel;
>
>The basic problem with bagasse thermal plants are that due to fuel
>conditions -- boiler tubes burn out fast.
>
>Ergo -- the industry standardized on a very simple -- plain -- vertical
>fire tube design -- which sits over a pile (heap) of burning bagasse at the
>bottom.
>
>Fire tube boilers are not suited for high quality steam -- they tend to
>explode at higher pressures  -- and as they have huge reservoirs of
>pressurized water in them -- are extremely deadly when they do explode.
>
>However -- the low quality steam produced in such boilers means terrible
>over all power extraction ratios.
>
>The "industry" attempted to over come this through the building of stronger
>fire tube boilers -- and actually got to the 1200 F - 800 Psi range -- thus
>increasing efficiencies to 16 to 18%
>
>But at great capital costs -- and even greater maintenance/servicing costs
>-- so that is side lined for now.
>
>At the same time -- there was a mad rush to look at gasification as
>optional system of power production. But that ends up even more problematic
>than the high pressure fire tube boilers.
>
>OK -- why not go to single pass very high pressure water tube boilers which
>is the modern industry standard and does achieve efficiencies better than
>40%!!
>
>Because of the fuel conditions -- burning bagasse eats boilers -- and worse
>-- it plates boiler tubes with crud -- silicates -- which then insulates
>parts of them -- and destroys their efficiencies greatly.
>
>Ergo -- change the tubes every season -- or else!!
>
>Changing the tubes in a large water tube single pass boiler -- is basically
>changing the boiler!!
>
>Changing straight pass -- large diameter -- fire tube in a fire tube boiler
>is a simple deal.
>
>OK -- so here we sit now -- best way to burn bagasse and extract something
>in energy -- fire tube boilers over a heap of burning bagasse.
>
>Now -- I repeated this over and over and over -- yet you still missed the
>point -- totally.
>
>Instead of piping that low quality steam to a steam turbine -- pipe it to a
>geothermal power plant that runs at much better over all efficiencies on
>low quality steam -- 
>
>Yet -- here you state:
>
>>I just wonder something: from where 
>>will i get a lava vein in escuintla??... i mean... where the sugar mills 
>>are?... another thing... when did i say i want to transport the whole thing
>
>>to another place.
>
>The ignorance in this statement simply overwhelms me -- you must be related
>to Kevin??
>
>Manuel -- steam is steam -- if it comes off a lava vein or out of a bagasse
>boiler -- it is still steam.
>
>You move the Geothermal power plant to the sugar factory.
>
>It is quite economic to do -- as pointed out already.
>
>However --
>
>>The only thing i am curious about is the fact you can 
>>transform biomass into gas...!!!!!
>
>That is the "dead-horse"
>
>As for:
>
>>what sugar mill in the world are they using 60 psi steam in the process?...
>
>>i think you got it wrong there... we use around 10 psi for the robert
>evaps.
>
>It is very expensive in large piping to deliver 10 PSI steam (especially
>the insulation required!!) -- so they often go some higher pressure for
>more efficient delivery to distant locations in a steam processing system
>-- tempering -- reducing -- pressure at the point of use.
>
>Manual -- there are a large number of sharks circling out there quite
>willing to come in and feast on 3rd world sugar producers that are some
>what naive about thermodynamics --
>
>It is not about what you personally want to hear -- cause they can give you
>all of that you wish -- it is all about what can -- and what cannot work!
>
>Your getting honest comments from me -- I am not trying to hustle you into
>a multi million dollar scam -- that comes later though -- if you keep
>dreaming of gasifying bagasse!!
>
>You can buy a small Ormat geothermal setup of 250 kw plus a small fire tube
>boiler that is designed to burn Bagasse -- from Apin in Chili -- put those
>two together -- and produce all kinds of power from bagasse -- at good
>efficiency levels -- run it for years to observe -- and learn everything
>that needs learning -- for total Turn Key costs of about $800,000 US.
>
>You'll pass the million mark fast with trying the same gasifying -- and you
>will never run a day even without tearing it down for some kind of tuning
>or repairs.
>
>The bagasse furnaces -- as existing -- in your mill -- runs and runs and
>runs -- right??
>
>The Ormats are hermetically sealed devices -- need nothing -- they run and
>run and run -- for 35 years plus --
>
>Again -- disconnect the Ormat from the geothermal steam and hook it to the
>bagasse boiler steam -- buy a geothermal unit -- pipe steam from bagasse
>boiler to it -- got that now??
>
>Peter
>
>
>At 11:36 PM 4/17/2006 -0600, Manuel Escamilla wrote:
>>Dear Peter:
>>
>>A couple of things to say here:
>>
>>First of all if there is something i like is to check how the list does the
>
>>things. I am not here to bang horses or whatever it is that you call it.
>>
>>I was in zunil last year... cool place. I just wonder something: from where
>
>>will i get a lava vein in escuintla??... i mean... where the sugar mills 
>>are?... another thing... when did i say i want to transport the whole thing
>
>>to another place. The only thing i am curious about is the fact you can 
>>transform biomass into gas...!!!!! I know just a few on this subject...
>that 
>>is why I ASK the list.
>>
>>Mr. Lewis Smith has given me a lot of valuable info on such matter. Not
>only 
>>tech stuff but also some economic facts... and by the way... ummmm... in 
>>what sugar mill in the world are they using 60 psi steam in the process?...
>
>>i think you got it wrong there... we use around 10 psi for the robert
>evaps.
>>
>>Another fact i don't get is why you say the steam is not good here?... got 
>>some troubles... fixed them. No prob.
>>
>>A one million tons per year mill??.. yeah... small
>>
>>Don't get like these Peter... really... perhaps i sounded like a bastard 
>>when i commented on the list but the thing is that i signed up here TO
>LEARN 
>>from you... not to test you all... not to humilliate anyone... just trying 
>>to LEARN...
>>
>>The other day one guy got so hostile about the turbines... i was just 
>>checking if what i knew was right... actually, i found another site which 
>>holds both the old and new schools of engineers. We get along pretty well. 
>>We learn from each other, we don't get all worked up because of one
>comment. 
>>I am not who to critizise anyone... so i will just stick to the facts here.
>>
>>So no... i am not interested in discussions with little letter between the 
>>lines. There is no need for that. Yes... we are in the 3rd world country
>but 
>>runninga 1st world industry and trying to be great in anything we do...
>>
>>I am sorry, again, if i ofended you in any way... i just love to learn from
>
>>the old horses... they have ran the track many times... i am just starting.
>>
>>My apologies to you. Hope i can keep in touch with you.
>>
>>Best Regards
>>
>>Manuel
>>
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>>
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