On the gas handling capacity of vertical dust filtration vessels using candles

H. W. Dries*, Advisor Cat-Cracking Technology, Netherlands; A.C. Hoffmann; University of Bergen, Norway

Dust filtration vessels have a tube-sheet from which candle filters hang down. These candles are cleaned using reverse pressure pulses. The raw-gas inlet is placed low in the vessel and the collected dust, blown off the filters as filter-cake fragments by these pulses, leaves the vessel underneath. Usually the raw gas moves up counter currently to the falling dust-cake fragments. In general, the capacity may be increased by increasing the filtration area (number or length of candles, pleating).

However, we show that there are limits to how much the gas-mass may be increased (by increasing either the pressure and thus the density, ρg , or the velocity, vg) as otherwise blockage will occur. In fact, this is similar to flooding of demisters in gas/liquid separators under conditions at which, following the Souders-Brown approach, the value of ρg.vg2 is increased to above a limit-value. Placing the mouth of the raw-gas inlet higher, giving predominantly co-current flow, was the design change that could be made under strict time constraints prior to the commissioning of an otherwise too-tightly designed separator. This work is an illustration of applying O'Keeffe's "business-beyond-the-box" (BBB) thinking, to deliver a breakthrough result by a vessel modification under tight time constraints...

Session: G11 - Short Oral + Poster Presentations
Day: 12 October 2016
Time: 14:45 - 16:45 h

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