Gasification Archive for September 2001

But Mark -- I have very little doubts that flow diagram -- as presented --
would steam reform a continuous run of biomass. Remember - -takes just 30
seconds under those conditions to accomplish the conversion. So just
depends on tube diameter -- not length -- what production would be achieved.

Plus -- rather than deal with high pressure at a very hot temperature using
large diameter tubes -- would be better to just put in multiple small
diameter tubes -- as in an old fashioned vertical fire tube boiler. Only
molten Zinc die cast alloy number three surrounding the tubes in that
jacket -- and biomass slurry being pumped through the multiple "fire-tubes".

If I was building this in my old shop I would first order up a 20 foot long
tubing of A106 carbon steel. 2 in. ID and 4 in OD.

I would use a small hydraulic motor attached to a stone type honer and
polish the entire length -- (a trick they use for making long hydraulic
cylinders)

I would then apply the appropriate bends. Finally joining by welding to the
heat exchanger section -- where temps go down.

The heat exchanger would be a 3 in ID by 5 in OD A106 steel tube -- with
bushings welded in at each ends -- allowing the passage of the intake 2 in
ID tube. From the end of that run to the 1st "separator" would be
relatively cold material -- still at 5000 PSI -- so much lighter tubing can
be used.

Now -- if we want to start math modeling -- how much biomass could be
gasified passing though -- say -- 6 feet of liquid metal boiler contact?
Figuring 30 seconds as reaction time??

What is the biomass content of that slurry?

The first though that comes to my mind -- can be a pretty thick slurry --
and still have to more super critical H20 than is required for the process.

As example -- 85% water -- 15% solids. Which just happens to be what citrus
wastes are -- and we have a huge problem with those here in Belize.

Also -- I believe citrus factories around the world are all looking for a
better mousetrap there!

Easy to "blend" that to a slurry.

And -- what about sewage? A light filter belt pressing -- bringing it to
85% H2O -- 15% solids.

At present -- biomasses such as these incur a terrific cost for fuel
conditioning -- namely drying them down to at least 50% H2O and 50% solids.

With the system I am proposing -- fuel conditioning becomes very simple.

Also -- what about Pulp and paper mill wastes -- black water -- etc.

Surely -- we can see some valid potential??

Now folks -- show me some real reasons this can't work. 

And finally -- if one put wet sawdust through this same device -- that is
55% H20 and 45% solids -- why would than not "reform" (of course it will!)

Or bagasse at the same criteria?? 

Or wood chips.

None of these are going to plug up a 2 in ID channel with 6000 psi pushing
it though!

Of course -- you realize that the power for "pressing" the charge through
this flow diagram comes from the blow down?? That pumps a hydraulic system
-- with accumulator -- so that a big piston easily pushes a smaller piston
at 6000 psi "ram" pressure.

Hate to have any loose ends in the energy losses department.

Bad enough to have that 2000 PSI invested in the tanks -- but then one
could always recover some refrigeration from the expansion from the tank to
the engine intake.

Ergo -- recovering energy as refrigeration. At the very least -- that cold
could be used to really cool gas at manifold entrance -- increasing charge
density -- and getting some extra efficiency out of the IC cycle.

And all so very easy to do!! No heat to absorption refrigeration system
crap! Just expand the gas through an orifice.

>I doubt that high pressure washers operate above 3200 psi, though there
>is a new generation of washers that use CO2 above its critical pressure
>for cleaning in applications that used to involve solvents frowned on by
>the EPA.

OK Marc -- how about high pressure cutting devices running water at 45,000
PSI and over?? Used for cutting sheet metal when I left Montreal -- in the
mid 80's -- replacing laser cutters (Which had replaced stamp presses and
robot torch cutters)??

Always look on the "shelf" of "proven" available processes from as broad a
selection as possible - saves a lot of re-inventing the wheel.

Take processes down from that shelf -- and bolt them together.

That is what I am doing here.

As example -- if you hit any engineer cold with the concept of molten metal
bath heat exchangers they will all say "impossible" -- as a molten metal
will surely dissolve the metal container in no time.

Well, I took zinc die cast allow number 3 of the above shelf -- dusted it
of -- and bolted it on. It is a given -- that allow does not dissolve its
steel molds at any great rate.

Or -- you can't find tubing to hold 5000 psi at 600 C -- but plenty of
modern steam turbine plants are operating at higher stress specs. and very
reliably.

Or the catalytic burner.

All from those same shelves -- all developed technology -- all easy to take
down and apply.

Or sticking a wood burning stove catalytic converter at the hot product end
of a gasifier!

If only our grandfathers had been doing this -- then probably people on
this list would look at it??

Now -- hit me with some hard points -- this is all to easy.

Peter Singfield
Belize, Central America

*************************************

At 10:28 AM 9/4/2001 +0800, you wrote:
>Peter Singfield wrote:
>
>> 
>> Not at 100 Deg. Centigrade!!
>
>You're right. I dug up my thermo texts. Above critical pressure the only
>thing that changes as you remove heat is that the substance changes from
>a supercritical fluid to a liquid without going through saturation. So
>yes, there is a phase change possible once you drop below Tcrit, which
>for water is about 275 degrees C. At that temperature and pressure,
>hydrogen will still be above its critical point. The hydrogen will be
>much less dense than the water, but I'm curious about solubility and
>diffusivity, both of which will influence separation. Do you have the
>necessary data? If so, can you post them? This is terra incognita for
>me.
>
>> Or, technically -- all high pressure water washers are operating super
>> critical?
>
>I doubt that high pressure washers operate above 3200 psi, though there
>is a new generation of washers that use CO2 above its critical pressure
>for cleaning in applications that used to involve solvents frowned on by
>the EPA.
>
>Marc de Piolenc
>
>
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