Control of Volatile Organic Compounds Emissions from Manufacturing

used in maki fig shopping bags. Forty percent of a1 1 HDPE is blow molded;
another 22 percent is injection molded. Film and sheet combined account
for only six percent of HDPE use. Other uses account for 32 percent.
End use sectors for HDPE include packagi ng (45 percent), consumer/i nsti -
tutional (11 percent), bui 1 ding and construction (9 percent), and other
sectors (35 percent).3
From 1973 t o 1979, production of HDPE grew from 1,196 Gg to 2,273 Gg,
'a growth rate of 11.3 percent. C.H. Kline projects growth at 7.0 percent
for 1978 t o 1983.4 SRI International projected growth from 1976 t o 1980
at 10 percent.5
2.3.2 Model Plant
The Phillips particle form process serves as the basis for this
model plant, but it is intended to represent all other liquid phase
slurry processes.
This model plan specifically includes an unreacted monomer recycling
system. There are other similar liquid-phase processes that do not use
such systems and have larger emissions. The plant capacity for the
model HDPE plant is 214 Gg/yr. This is based on plants 1 ocated in
nonattainment areas. .The existing HDPE plants known to be in the current
ozone nonattainment areas are listed in Table 2-5.
2.3.2.1 Process Description. Referring to the schematic for thi s
process, Figure 2-2, the feed section includes catalyst purification and
activation. The prepared catalyst is then fed to the reactor continuously
by being slurried in a stream of process diluent (pentane or isobutane).
Ethylene monomer and comonomer (1-butene or hexene), after purification,
are also fed to the reactor where polymerization takes place in process
sol vent. The reactor, for the particle-form process, is usually a
closed loop pipe reactor. The product HDPE is separated from unreacted
monomer and di luent by flashing from a 1 ow pressure to a vacuum and by
steam stripping. The wet polymer solids are dewatered in a centrifuge
and then dried in a closed-loop nitrogen or air-fluidized drying system
prior to extrusion.
The unreacted monomer and diluent vapors are sent through a diluent
recovery unit where most of the di luent is separated and recycled back
to the reactor. The rest of the stream is then sent to the ethylene