[kanankiri]

hi all.

Would like to ask of why people use water to flush the collected PM out of collection plate in a wet ESP? As far as I know, the water will cause some sparks or even fire when you pour it out on a high voltage metal object.

I'm currently designing gas clean-up system for fluidized gasification plant. Wet ESP is favored because our treated PM is kind of sticky (i.e. tar). I'm no expert in electrical, but I still think that water will explode when we add water on the high voltage collection plate.

Already check on couple of books and pdfs on the net. They all said that water is really put in contact with collection plate by flushing out, not just used only for draining PM out of ESP after being hammered down by rapper which is the case for dry ESP.

Please help me if somebody know or familiar with this.

thanks

regards,
bernath

[kanankiri]

Dear All,

Is there anyone who can help me to answer above question or know someone who might be able to deliver the answer?

I've searched and raised question across 3 Chem-Eng forums and still not get anything yet.

Plz help guyz...

regards,
bernath

[Arkcon]

Sorry, but I'm not an engineer.  Maybe some of the newer engineers, or other scientists, on this board will be able to help, if you drop the jargon and identify your abbreviations.  PM?  ESP? Wet?  Hammer?

[kanankiri]

Sorry guys,

ESP = Electrostatic Precipitator is an air pollution control device which is use to capture Particulate Matter(PM) from process/gas waste in nearly all kind of industries.

ESP can be categorized into 2 types:
1. dry ESP
2. wet ESP

These 2 ESPs is categorized by means of how to collect the dust. Is it by hammering the collection plate so that the dust fell off which is the case with dry ESP or by watering or flushing the dust out of collection plate which is the case with wet ESP.

My question is, is it possible to pour out the water directly into the (high voltage) collection plate?

Plz answer if anybody know.

thank you

regards,
bernath

[ki98mama]

Hi,

having some experience with WESPs' I might be able to offer some input here.
Water is used because it is cheap and a pretty good solvent (in most cases).
I would not reccomend pouring water on the highvoltage plates in a WESP while they are operating as the water would short them out.

In the WESP I have worked on the Highvoltage electrode is dry and kept ~4 cm's away from the collecting plate (grounded). The collecting plate is continiously wetted from a water wier and is kept clean by a water film (which also carries the PMs' to the sump).

The highvoltage electrodes charges the incomming PMs' in the corona and the charged particals are carried towards ground (wetted wall of the percipitator). The electrode does get some particulates sticking to it but not much (needing a clean every 6 months or so). However our WESP is designed for "clean" silica powder handling, not sure how much cleaning is required for a tarry environment...

[Kaolin]

Hello Bernath,

With my experience in WESP's operation, flushing is one of the major operation done on a shift basis to remove the PM from the collector plates. Flusing is done on a shift basis by the operation or whenever the sprak rate increases drastically. Normally we flush the ESP's with high pressure water stream to remove all the stick particles. However you don't flush with water when the ESP is in operation. There is a SOP to flush WESPs. It is supplied by the OEM which explains the flushing procedure. Flusing of WESP is done by isolating the particular ESP or the ESP in series for a couple of minutes and take them back online. So nothing to worry about that. You can design your ESP without any worries. Please post, should you have any clarification.