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Thread: Dust from Pneumatic Conveying

  1. #1
    bbhaskar Guest

    Dust from Pneumatic Conveying


    We use pneumatic conveying in our foundry for conveying sand and use bag filters in the destination hopper for ventilation. To shake the bags peridically, we are considering installing 'pulse jet' shakers to the bag filters.

    The question is, does pulse jet shaker require dry air? Our compressed air system does not have air dryers but only line filters to drain out water from the air. Is this sufficient for 'pulse jet'

    What are the other types of equipment available to release dust from the bags?

  2. #2
    Michael Reid

    Michael Reid

    Managing Director

    APC Engineering Associates Pty. Ltd.

    APC Engineering Associates Pty. Ltd.

    Professional Experience 5 Years / 6 Month Michael Reid has 5 Years and 6 Month professional experience

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    Dust from pneumatic conveying

    A pulse jet filter is the correct dust collector to use for foundry sand. If the sand is dry, you do not need refrigerated dryers, just a good quality coalescing filter. Give it regular maintenance.

    Buy your bagfilter from a reputable contractor/supplier. Specify a filtering velocity (through the filters) of no more than 2.4 m/min.

    Michael Reid.

  3. #3
    Dennis Hauch - Freeport, TX, USA Guest

    Pulse-Jet Air Quality

    bbhaskar,

    Pulse-jet cleaning systems do indeed require dry air. To assess how dry it must be, one must consider the thermodynamic properties of moist air.

    For example, assume outdoor air at 100 F having a dew point of 72 F is drawn into the compressor suction. After compression to 100 psig and cooling back to 100 F (using either a cooler or by simply storing it in an accumulator) the free water is removed. The air, now saturated at 100 psig and 100 F, enters the pulse-jet nozzle. It leaves the nozzle at essentially atmospheric pressure; expansion has reduced the dew point to (+) 40 F.

    But the expansion process has also effectively cooled the nozzle surface to something less than +10 F. The resulting condensation could easily blind the filter bags over time. This can be avoided by additional cooling of the compressed air or by the installation of a desiccant dryer.

    Normally, the manufacturers of pulse-jet clean systems require the air supply to be instrument quality, specifically, air having a dew point of (-) 40 F.

    Regards,

    Dennis Hauch

  4. #4
    erik opitz Guest

    Use of Compressed Air Dryer

    Dear sir:

    According with my experience on dust collectors, the best performance os working with dry air; assuming that the dust collector design has benn well done.

    The use of dry air increase the bag lifes, it helps you with the clean process, reduce maintenance problems with the rest of the dust collector components (diafragms, solenoid valves, pipes, etc.).

    I can tell you this because I have experienced this with my equipments.

    I have very good experience with Hankison Dryers from USA (dessicant towers). They are very cheaps and almost with no maintenance. But, you need to have good and stable energy for them; otherwise, put elctric stabilizers to have stble voltages.

    If you can, try with dessicant dryers.

    You will be very happy.

    Erik

  5. #5
    It seems that you have the "ancient" shaker type dust collectors which are shaken on a time cycle by a mechanical device. From your question, it appears that you would like to modify these shaker type dust collectors by installing a "pulse jet" system. If my reading is true, the best option would be to replace the shaker type with pulse jet type dust collectors. It is almost impossible to modify a shaker type dust collector with venturis, tube sheet, and plenum chamber, etc. Replacement will cost less than the modifications.

    Amrit Agarwal
    Pneumatic Conveying Consultants
    www.powderandbulk.com/pcc
    email: polypcc@aol.com
    Fax: 304 346 5125

  6. #6
    Marco Aurelio Flores-Verdugo

    Marco Aurelio Flores-Verdugo

    Consultant

    Tecmen S.A. de C.V.

    Tecmen S.A. de C.V.

    Professional Experience 5 Years / 4 Month Marco Aurelio Flores-Verdugo has 5 Years and 4 Month professional experience

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    Know-How Design (142) Marco Aurelio Flores-Verdugo used this tag 142 times, Pneumatic Conveying (80) Marco Aurelio Flores-Verdugo used this tag 80 times, Training (15) Marco Aurelio Flores-Verdugo used this tag 15 times

    DRY air

    Dear friend.


    India is not the run of the mill place , Some years ago working for a steel technology supplier we helped in the design of a large installation in INDIA , during the monzoon your air humidity goes to 100% ,and all the rules change, your shaker dust collector has been working for some years I pressume. if your air compressor has no after cooler and knock out drum you might run into problems when using direct feed air for reverse cleanup or blasters . if you cannot install dryers try at least to install a knock out drum, with appropiate water purges. other wise you can find yourselves with water hammers instead of shakers.

    marco
    TECMEN
    Consultant in:
    Sponge Iron (DRI) handling
    Sponge Iron DRI Automated Storage Firefighting and Root Cause Analysis
    Pneumatic Conveying Consultants
    Phone 5281 8300 4456.

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