Multi-cyclone installation
Multi-cyclone installation
(OP)
Hello everyone, we work on wood fired boilers and use multicyclones for flyash separation. These seem to work fairly well and we are generally satisfied with the performance we get out of them.
However, we are looking at a system with sludge as fuel and the ash content is much higher. I am wondering if anyone has tried using two multicyclones in series to further reduce particulate emissions and what sort of results you may have got from this setup.
I will be talking to our supplier about this soon, but would like to get some outside opinions as well.
Cheers
However, we are looking at a system with sludge as fuel and the ash content is much higher. I am wondering if anyone has tried using two multicyclones in series to further reduce particulate emissions and what sort of results you may have got from this setup.
I will be talking to our supplier about this soon, but would like to get some outside opinions as well.
Cheers





RE: Multi-cyclone installation
The primary reason it was done where I did it was for fan protection and it worked well. The fan exihibited very little wear over a lot of years while units with single multiclones had horrific fan wear problems.
Keep the hopper access doors shut and sealed and use a good brand of rotary valve for the dust extraction. A leaking rotary valve can cause fires that can trash dust collector hoppers.
rmw
RE: Multi-cyclone installation
We currently use 9" tubes and I do not see us going to anything smaller. We would likely use 9" tubes on both.
What fuel were you burning?
RE: Multi-cyclone installation
If the objective is to reduce partilce erosion in downstream equipment, I seem to recall tha only particles larger than ( 30 um ?) and of mineral matter harder than steel will contribute to erosion. ( as per published Mitsui Babcock papers) . So the cut size of 2nd stge multi clone does not have to consider particles smaller than 30 um.
RE: Multi-cyclone installation
RE: Multi-cyclone installation
The main reason for looking at multicyclones in series was to reduce overall emissions, not reduce erosion. It was not until that was pointed out by RMW that erosion came up.
RE: Multi-cyclone installation
In some applications there were jokers in the deck because of phenolics from product scraps also burned in the furnace.
I can't picture any jurisdiction in this fine country of ours where multiclones, even in series (unless you had more than a few) would meet current pollution laws. You need a scrubber or a baghouse to meet environmental laws of today.
IMHO.
Also, do you have a particle size distribution efficiency curve from your prospective multiclone vendor?
The fine ash that multiclones don't get out is what makes the plume that is objectionable.
You may want to use a 7 inch tube for your second stage, and if you are compelled to stay with 9", then at least use the conical discharge boots on the bottom of the tubes. They are much better for the fine stuff.
rmw