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Dear Prof Ganesh and ALL,
I completely agree with you about the DD gasifiers. Its the
best proven and commercialised gasifier w.r.t gas quality, ease
of operation etc.
However, I think its two major limitations are:-
1.0 It's unit capacity restriction -
which means that one has to resort to multiple units operating in parallel when
higher capacity is desired. (Anyone who can talk of a DD gasifier in operation
of higher than 3.0 metre ID?)
2.0 It's limitation w.r.t feed size. Since,
it cannot take feed of smaller size, it means, one has to resort to
briquetting ! That is not only adding a very costly processing step but also to
the best of my knowledge there, as yet, are no known satisfactory
briquetting machine which has been working commercially. Thus, using rice
husk as it is, without briquetting, in a DD gasifier is a NO!
NO!
I think these are probably some of the major reasons
why the emphasis in the Developed countries has been on FB rather than DD
gasifiers. After all, cleaning tar from fuel gas is a very very old
technology.
Regards
Kollol
----- Original Message -----
Sent: Tuesday, September 17, 2002 9:51
AM
Subject: Re: GAS-L: Tar Standards and
Codes
Dear Prof Reed and all,
The fact that we are already
saying that FB gasifiers have 10,000-50,000
ppm tar nd DD gasifiers have
only 100-1000ppm, shows that one has measured
them. If accuracy or
non-accuracy was not the issue, then it becomes very
important to define
these figures with reference to a particular method of
sampling and
analysis of these tars and particulates.
I will explain this more
explicitly. I have just complted a study on
comparison of three of the
sampling techniques commomnly used in India for
measurement of tar and
particulates. The final report is being made and
is not yet ready for
public disclosure. However, I am in a position to
give this
example.
On simultaneous measurement of tar and particlaute using two
of the
techniques, we found that for the same gasifier-system operating,
the tars
measured by one was about 10 times that by the other. The figure
for
particulates , however , was found to be of the same range using both
the
techniques. This still does not qualify the technique giving higher
values
as best or absolute, as we could have something better. Probably
what one
needs to know is, w.r.t. one method (could be any) what is the
tolerance
of
the end-user-- both numbers and quality/constituents
of
tar/particulate. Then with existing co-relations one could have an
option
of various techniques.
You may also be aware, that
India already has very clearly laid out
procedure for testing and
certification of updraft and downdraft gasifier
systems,.India also has a
procedure for monitoring the performance of
gasifiers on site.
Now
in view of the discrepency in values, one needs to set the standards
for
amounts of T &P w.r.t a particular sampling method and
analysis
procedure. Otherwise, a gsifier falling into a" good" gasifier
class may
be
declared as" bad" in terms of the T & P
generate , measured by two in
dependent groups using two different
techniques.
anuradda
Prof.Anuradda
Ganesh
Energy Systems Engineering,
I.I.T Bombay, Powai, Mumbai - 400
076.
Phone (W) 576 7886 (H) 576
8886, 572 0762
FAX (91)-22-572 6875, 572
3480
On Mon, 16 Sep 2002, Tom Reed wrote:
> Dear Thomas and
all:
>
> Thomas puts it very well when he says...
>
> > The problem about this protocol is that it is initiated by
researchers and driven forward by researchers.
>
> A second
problem is that the EEC (with tons of money) is mostly focussed on fluidized
bed gasifiers which make tars in the raw gas of 10,000-50,000 ppm. When
they reduce them by a factor of 100 they think they are doing well. But
downdraft gasifiers have only initially 100-1000 ppm tar in the raw gas when
properly operated. Tar measurements suitable for the first case don't
have the sensitivty required for the second case.
>
> A
third problem is that money and time is no object... the more the
better. While those of us in small gasifiers want to find a gas that is
clean enough for engines and don't care too much about the exact analysis of
the tar.
>
> So, we should all be interested in high
sensitivity, low cost, fast tests and many of us are working on it. The
Bacharach Smoke Meter (cost $75) comes pretty close to a good quality test and
I have been trying to make it quantitative with some success.
>
> Yours
truly,
TOM
REED
BEF GASWORKS
> ----- Original Message -----
> From: Thomas Koch
> To: Kollol Dey ;
Gas - L
> Sent: Monday, September 16, 2002 2:39
AM
> Subject: Re: GAS-L: Standards and Codes
>
>
> Dear Kollol
>
> That is
a very relevant subject you discuss.
>
> In EU there
have been a work ongoing on stardadisation on tar measurement going on for
some years.
> Search on "Tar protocol" to get more
information.
> The problem about this protocol is that it is
initiated by researchers and drive forward by researchers.
>
> Do you have the tiem to explain how you are used to
conduct performance test?
>
> New input would be very
helpfull for us in the biomass field.
>
>
>
Thomas KOch
>
>
>
>
> ----- Original Message -----
> From: Kollol Dey
> To: Gas - L
>
Sent: Monday, September 16, 2002 9:54 AM
>
Subject: GAS-L: Standards and Codes
>
>
> Dear ALL,
>
> 1.0 I wish to know the
internationally accepted standard codes that are available for conducting the
"Performance Test" of a bio gasifier - whether it be moving bed, fluidised bed
or entrained bed type. Can anyone help?
> I
understand that ASME has a PTC - 47 which is meant for an IGCC units. But have
no idea as to how much of this can be adopted in checking the performance of a
biomass gasifier? I also understand that ASME had a code for conducting
Performance Tests on a coal based producer gas plant - I think it was PTC -
16, but I believe this code has been with drawn for sometime.
> If someone is working on such a code - good !
> But if this is not so, then isn't it time
that a PTC for biomass gasifiers be drawn up ?
>
> 2.0 Further, the petroleum
and petrochemical industry rely on API for standards, codes and recommended
practices. Isn't it time that such things also be introduced in this industry
(biomass gasification) so that there are guidelines for buyers of
biomass gasifiers to go by? I am sure this will be interest of the industry
and will keep away a lot of "tall claims and counter claims"once the industry
sees such internationally accepted standards and codes.
>
> Comments please !!
>
> K.Dey.
>
>
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