In tissue and towel divisions, there are winder dust systems. For the fine paper industry, there are sheeter dust systems. In the corrugated industry, the shredders emit large amounts of dust, especially with recycled board, which is also true in the folding carton industry. Some of the densest volumes have been in the printing industry, regarding binderies.
ASDI has installed various types of filter systems behind both separators and cyclones. In recent years, we have installed these filters with a negative air handling fan and a VFD on the negative side of the filter. These systems have been proven to be much cleaner than positive air systems. A negative system increases production in the plant. Since the air handling fan and VFD speedup to overcome the filter media as it gets dirty, the paper handling fans never lose their suction pressure. It also keeps the down pressure in the baler chute constant and to a minimum, therefore, more dust is also conveyed to the filter and not into the baler.
Some of these have been wet scrubbers and dry filters such as cartridge collectors and bag houses. It is important that the proper filter is matched to a particular type and size of dust. There are many other areas in which a decision on the type of filter to use should be considered. Today, now more than ever, the guidelines by the National Emphasis Program, in cooperation with the NFPA, FM and OSHA, can alter the decision toward a certain type of filter.
For example, if a filter needs to be installed inside a plant, but cannot be located near an exterior wall. The explosion vents will need to go out through the roof or the use of chemical suppression will have to be used. The location of the filter can sometimes dictate which filter should be used to satisfy the type and quantity of vents that will be required.
In addition, not all filters are roof vented or sidewall vented; which must be factored in. One item is clear by the new directive, and that is the vents must be straight with no elbows, the chute must be less than ten (10) feet, and in some cases even shorter. There are new mathematical equations that must be used to satisfy not just the Kst value, but the bar.
Due to some of the unfortunate accidents in other types of facilities, the agencies mentioned above will all look for dust settled in every part of a plant. ASDI is familiar with the new regulations and can direct customers in the right direction to correct their issues and show them how to maintain a "Clean Plant Environment".
Retractable Dust Hood