[Gasification] Candle filter experiences

[Doug]

Hi James,

Sorry for slow response but have been a bit ill these last ten days.

The bad news is that ESP isn't going to work either with wet carbon 
soot. It shorts out all the anodes causing arcing and explosions. The 
European guys had several "incidents" so not sure they are even legal to 
use, other than for dry boiler fly ash, etc. I'm sure Bjorn has more to 
add, but save your $$ and time.

Regards,

Doug Williams,

Fluidyne.


On 02/11/17 12:16, James Joyce wrote:
> Thanks for the advice Doug, Bjorn and Leland. Hopefully you can prevent others from exploring again some of the many dead ends that gasification presents to us "starry eyed" technologists !
>
> I am certainly more nervous that I was before. The flue gas application might go ok, as long as we keep the start-up emissions out of it ... but the pyrolysis gas application looks like trouble. I will have to follow up on ESP for that, however the last time I looked that the cost of the electrical items was more than twice the cost of the rest of the plant combined.
>
> I had considered burn-off as the option for tar fouling in the flue gas application. We will be running at 350 deg C with 30-40% excess air, so it might not need much encouragement to burn off any tars once it gets to temperature.
>
> We were going to use a flooded auger for dust removal, recognising that a smouldering hopper fire is all but inevitable, because we can get ember carryover from our thermal oxidiser. Will have to look at how to manage the hold-up of the soot/ash. I have considered a sonic horn for that. They are used for soot/ash release in large coal fired furnaces ... not cheap and may present some risk to the candles.
>
> Sounds like cyclones ahead are a bad idea ... just as well as I had no intention of doing that figuring the cake needed the larger particles to give it some "body".
>
> Great to get some actual numbers on pressure drop. Unifrax were suggesting to keep it below 10" to avoid stressing the candles. In the flue gas application, we can use compressed air for the back-pulse, so we don't have to be as conservative as you would be with inert gas. For the pyrolysis gas application I can see this being another reason to have a good look at the electrostatic precips again ...or perhaps batch filtering with deep bed sand filters that are water washed once the pressure drop is too high ?
>
> regards,
>
> James
>
>
>