Page 304 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

274 Applied Process Design for Chemical and Petrochemical Plants

Table 4-12A
Partial List of Commercial Crossflow Microfilter
Media-materials and Geometries

Tubulw
1. Po/ymtll"8

Polyvlnylldene fluortm
Ac:ryllc

Alumlnll
. ' ,
,
�
Zlrconle,'carbon , • ,
j
Silica ' . ' ,
Slllcon C8rt)lde ' . "
3. Slntem:I ,,,.,.,
1Typo·11--1 •11C=Multktlannel monolllhlc ••••ta

Other alloys

By permission, Michaels, S. L. [38].

The woven fabrics have various yarn patterns for dif- varies, but one promise seems to be that higher tem-
ferent spacings between the yarn fabrics (Table 4-14). peratures will be handled.
There is a wide variety of choices for not only the
materials of construction but the tightness of weave New cartridge designs for bag houses will allow
and the size of the yarn. All of these factors along with improved servicing and cleaning techniques.
the others noted earlier, make the selection of bag fab-
ric an art that requires manufacturer's and plant's It is important to keep bolts, nuts and other poten-
actual field tests. Woven fabrics have a low ratio of tially loose items to a minimum inside the unit, as
weave openings for yarn area and generally have a lim- vibration from air/ gas flow and bag cleaning can
ited face velocity for air flow of about 1.5 to 3.0 cu loosen nuts, break small welds, and ultimately tear
ft/min/sq ft [47]. holes or rip bags. The bag construction is likewise
extremely important, since loose edges and
Newer fabrics, not in common use but in develop- "unlocked" seams will fray and tear, allowing fibers
ment, test, and field trials, are described for higher into the product dust. The bag construction must have
temperature applications by Reference [50]. Applica- straight seams in order for them to bend and flex
tion to 400°F-2100°F are potentially available using properly on cleaning and/or loading.
ceramic fibers Nextel 312®, laminated membrane of
expanded PTFE on a substrate, polyimid fiber P-84, Cartridge filters may be single units or clusters in a sin-
Ryton® polyphenylene sulfide, and woven fiberglass. gle container or canister. Figures 4-68 to 4-74 illustrate
The heat and acid resistance of these new materials typical units. These may be designed to filter suspended