Re: How To Avoid Dew Point In Dust Collect Systems
Harold,
I am afraid that i know know your process but as a general comment, trying to design equipment for a system that is out of control is as you appear to have found, is very difficult.
I would suggets that investment in whatever control system is necessary to prevent these wild fluctuations and get the system under control would be a better investment than changin the equipment to cope with them.
Designing any filter system to reliably cope with anything from a sticky wet slurry to gas at the burning / melting point of the fabric does not sound easy. ■
Re: How To Avoid Dew Point In Dust Collect Systems
Have you considered baghouse insulation? Although it will not help if the gas T reaches dew point, it does help if the gas T gets close to dew point.
I also had similar problem with T variations and insulating the baghouse helped. For high T, you can think about (if your process chemistry and safety allow) having a valve upstream of the baghouse which can control ambient air flow - this way you lower the T, but of course, your air-to-cloth ratio goes up. Since, in my understanding, you have this T surge occasionally, cooling the dirty gas stream by mixing with ambient air when is cheaper than replacing the bags with the ones that have higher T rating.
But whatever you do, make sure you do your calculations first -
- final mixture T and RH
- air-to-cloth ratio
- cost of control vs. upgrading the filter bags
Optionally, fiberglass PTFE coated bags could solve the problem on low end side (hydrofobic), maybe..., but definitely on the high end side (I had them running @230 C continuously) ■
Dew Point In Dust Collection Systems
It is fundamental that you have to control the process rather than trying to make the baghouse cope with these upsets.
That will be cheaper in the long run than frequent stoppages for filter bag rejuvination and replacement.
Your baghouse and the ducting from the kiln will already be insulated. Heating the hopper with external electric heaters will keep the baghouse above dew point during shutdowns, help during low temp. excursions and help keep dust flowing.
Michael Reid. ■
How to avoid dew point in dust collect systems
Hi everybody
I have a "little" problem and I hope you can help me about it:
We have a Vertical Shaft Kiln for Clinker and also a Bag Filter System for taking out all the dust of the stack gas.
Besides the stack gas, my raw meal has 14% R.H. (required in the process)
In normal operation I have 100 - 110 ºC at stack gas, but usually there's a no control of this temperatures and it can go down (sometimes below 70 ºC, and the gases and dust go throught the dew point making a kind of slurry, so this slurry pollutes the final product when they get together and also there's humidy at bags, reducing its live time) and sometimes the temperature goes up 150ºC getting the bags close to burn out.
So if we can't keep between this limits we have troubles...
So when I have low temperatures and a dew point at stack gas, my bags are condensed and also they wouldn't work well (rising the differential pressure inside the bag filter)
Before my Bag Filter System I have a gravitational static precipitator when also this "slurry" is produced.
So my questions are:
- So Do you think that heating the stafk gas and dust before this point I could improve the process?
- Or Should I cool the stack gas and dust, so I could get the stack gas and dust complety condensed , making a controlled slurry so I could take out all the slurry and avoiding humidity at bags?
-Adding some baffles inside the gravitational static precipitator I could get more dust or more slurry?
- Do you think it's better to change the bags for other that can carry high temperatures or humidity?
- Usually the "product" of the bag filter system and the gravitational static precipitator join with the clinker product (but they are pollutant making a lower quality)?
- What about "Wet Scrubbers"?
Thanks for your support.
HAROLD ■