Environmental Engineering Reference
In-Depth Information
Injection molding:
Mold clamping (36%), barrel heating (19%), drive
mechanism (18%), resin drying (6%), and process chilling (4%)
Blow molding:
Drive mechanism (38%), process cooling (19%), resin
drying (7%), granulator (6%), and finishing equipment (7%)
Significant energy savings can be accrued in the fabrication or processing
of plastics by making fairly modest process modifications.
Table 4.7
summarizes such improvements in processing that deliver substantial
energy savings.
Table 4.7
Energy-saving Opportunities in Plastics Processing
Source: From the Canadian Plastics Industry Association (2007).
Process
Improvement
Energy
saving
(%)
Extruder
drive system
Improve drive mechanism by matching size and
speed of motor. Investigate high-efficiency motors
20
Extruder
barrel
heating
Insulate barrel in extruders or molding machines 15
Mold closing
and
clamping
system
Use variable hydraulic power to match load
requirements. Explore the use of variable speed
drives, variable displacement pumps,
accumulators, and control systems
45
Hydraulic
system
Use a single centralized hydraulic power system to
supply a group of machines
50
Compressors Use compressors of proper size that are well
maintained and “staged”
20
4.4.2 Atmospheric Emissions from Plastics Industry
Both globally and in the US, greenhouse gases (GHG) released to the
atmosphere are dominated by CO
2
from combustion of fossil fuels. Most of
and natural gas (20%). The annual US emissions of about 30 MMT of CO
2
(based on 2007 data) amount to about 20% of global emissions. Industry is
