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<p><font face="Liberation Sans">Hi James,</font></p>
<p><font face="Liberation Sans">We have had quite a lot of
experiences using candle filters for our project at CalForests
in California. They work well, but will clog in an eye blink if
start-up gas is not vented first. Life relates to mechanical
shock and flanged end seals, which we found shrinks so the
candle can leak and wobble. Any backfires into the filter will
also cause breakage which you don't see without opening the
filter from both sides. Inspection or access hatches can assist
with servicing, but there is no standard when these types of
filters are used for gasification applications. As our project
was one of staged development, I cannot tell you how many hours
were recorded in total, but we expected an annual replacement
based on seasonal heating requirements. According to the
manufacturers of the candles, our project was the first of it's
kind in the USA applied to gasification, so you may not get to
much practical information.<br>
</font></p>
<p><font face="Liberation Sans">They are really tops at removing the
solids if your gas is tar free, because any condensation will
block the candle. We used condensers down stream and at times
some very light pyrolysis oils showed up which destroys any
diaphragm in gas regulators. If it doesn't do that, then it
blocks the control ports in the regulator/mixers, but it all
depends on the overall quality of the gas. Good luck with
filtering pyrolysis gas, you could loose your shirt as I have
not heard of any success to date.</font></p>
<p><font face="Liberation Sans">You can expect to collect a lot of
very fine dust which is rather difficult to flow from under the
candles. Augers just drag out a core and the dust stacks up over
the trough, so you need some thought to extraction.</font></p>
<p><font face="Liberation Sans">This is just off the top of my head,
and it's been about 4 years since we changed the projects
direction from engine generation to hot water boiler heating. I
was on site late July and we discussed building a new candle
filter for the boiler, so we are sold on them at least for our
type of project. I haven't put up the latest photos from the
project as yet on the Fluidyne Archive </font>of the biochar
maker, but you can see a few photos of the candle filter
trials. <a class="moz-txt-link-freetext"
href="http://www.fluidynenz.250x.com/">http://www.fluidynenz.250x.com/
<br>
</a></p>
<p>Hope this helps a bit.</p>
<p>Doug Williams,</p>
<p>Fluidyne.<br>
</p>
<br>
<div class="moz-cite-prefix">On 31/10/17 12:48, James Joyce wrote:<br>
</div>
<blockquote type="cite"
cite="mid:503f81f5f6374fe2b54bc7af6eda36e2@jamesjoyce.com.au">
<pre wrap="">We are just about to order candles for a flue gas filtration application at 350 deg C. We have also been asked to design a 400 deg C candle filter system for pyrolysis gas, for installation ahead of a condenser.
This is one example (not necessarily the supplier we will use) <a class="moz-txt-link-freetext" href="http://www.herding.de/files/hGlobal/Downloads/Technical_product_descriptions/ALPHA/UK/Herding_ALPHA_Biomass_Filterunit_uk.pdf">http://www.herding.de/files/hGlobal/Downloads/Technical_product_descriptions/ALPHA/UK/Herding_ALPHA_Biomass_Filterunit_uk.pdf</a>
I have read some of the case studies for larger gasifiers. I am interested to know what experiences, if any, have been had with candle filters at the smaller scale (say 2-20 tonnes per day of biomass gasified). Reliability is my main interest, number of hours between replacement ... and performance as far as downstream equipment such as condensers and engines are concerned.
Regards,
James
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