Page 557 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

Applied Process Design 523

Table 7-30 (E) Plastics
continued continued
(E) Plastics Vinyl
Chlonde/
Erhvlcnc.'
Median Minimum Vinyl
particle explosive Ks, Dust Acetylene
size, concenrrarion Pmu• (dP/dl)mu, bar-m Hazard Swpension
Material iim g/m' bar ga bar/sec sec Class �mer 60 60 8.3 98 98 1
Reprinted with permission, NFPA Code 68, Venting of Deflagrations ( 1988)
(poly)
Acryla- National Fi1·e Protection Association, Quincy, MA 02269 [27]. This
mide IO 250 5_9 12 12 reprinted material is not the official position of the National Fire Pro-
(poly} tection Association on the referenced subject which is represented only
Acryloni-
rrile 25 8.5 121 121 by the standard in its entirety.
(poly)
Ethylene
(Low
Pressure DIERS Final Reports
Process) <IO so 8.0 156 156
Epoxy
Resin 26 30 7.9 129 129 Refer to the bibliography at the end of this chapter for
Melamine a listing of the final reports of this program [67].
Resin 18 125 10.2 110 110
Melamine.
molded Flares/Flare Stacks
(Wood
flour and
Mineral- Flares are useful for the proper disposal of waste or
filled Phe-
nol-Form- emergency released gas/vapors and liquids. The effects
aldehyde 15 60 7.5 41 41 on the environment and the thermal radiation from the
Melamine,
0
molded flare must be recognized and designed for. Flares may be
(Phenol- "ground" flares or they may be mounted on a tall stack to
Cellulose) 12 6() 10.0 127 127
(poly) move the venting away from immediate plant areas. Fig-
Methyl ure 7-69 illustrates a plant flare stack system. The flow
Acrylate 21 30 9.4 269 269
(poly) noted "from processes" could also include pressure relief
Methyl valve discharges when properly designed for backpres-
Acrylate,
Emulsion sure. This requires proper manifold design and, for safe-
Polymer 18 10.l 202 202 2 ty, requires that the "worst case" volume condition be
Phenolic
Resin <10 15 9.3 129 129 used, particularly assuming that all relief devices dis-
(poly) charge at the same time and any other process vents are
Propylene 25 30 8.4 101 IOI
Terpcne- also flowing. The piping system sequence of entrance of
Phenol the flare is important to backpressure determination for
Resin lO 1:, 8.7 143 143
Urea- all respective relief devices.
Formalde The knock-out drums or separator tanks/pots can be
hyde/
Cellulose. designed using the techniques offered in the chapter on
Molded 13 60 10.2 136 136 Mechanical Separation, and will not be repeated here.
(poly)
Vinyl API-RP 521 [13] specifies 20-30 minutes holdup liquid
Acct ate/ capacity from relief devices plus a vapor space for dropout
Ethylene
Copclymer 32 30 8.6 119 119 and a drain volume.
(polv) The unit should have backup instrumentation to ensure
Vinyl
Alcohol 25 60 8.9 128 128 liquid level control to dispose of the waste recovered liquid.
(polv) The seal tank/pot is not a separator but a physical liquid
Vinyl
Bur yr al 63 30 8.9 147 14 i seal (Figure 7-70) to prevent the possibilities of backflash
(poly) from the flare from backing into the process manifolds. It
Vinyl
Chloride 1 Oi 200 7.6 •16 46 is essential for every stack design.
(poly) The backpressure created by this drum is an additive to
Vinyl
Chloride' the pipe manifold pressure drops and the pressure loss
Vinyl through the separator. Therefore, it cannot be indepen-
Accr yk-ne
Emulsion dently designed and not "integrated" into the backpres-
Copolymer 3:> 60 8.2 sure system. The flow capacity of the relief valve(s) must
(polv)
(Cexl continued on page 526)