Page 98 - Plant design and economics for chemical engineers

76 PLANT DESIGN AND ECONOMICS FOR CHEMICAL ENGINEERS

TABLE 6
!hquence of steps in developing a project?
Time sequence
Process identification
Laboratory verification
‘Reaction flow schematic
Preliminary flow process
Preliminary economic evaluation
Process development
Mass and energy balance
Process flow scheme
Site selection
Project steps Refined economic evaluation
Design fixed
Detailed economic evaluation
Engineering flow scheme
Basic design
Detailed construction plan
Detail design
Procurement
Construction
Startup
t Modified from Ann. Occup. Hyg., 30~232 (1986).

The disposal of waste streams that contain large amounts of water is
another challenge which faces a process engineer. Deep-well injection has been
used in the past, but this method has been constrained by regulatory agencies.
Recently, refinery wastewater and storm water runoff has been subject to more
stringent Best Available Technology (BAT) effluent controls. The agreement
covers nonconventional pollutants such as phenolic compounds, ammonia sul-
fide, and toxic pollutants such as chromium and hexavalent chromium.
Hydrocarbon emissions is an environmental problem which is prominent
in some areas of the country. In these areas, pollutant levels occasionally exceed
the national ambient air quality standard. One source of these pollutants
involves emissions from refineries where about 85 percent of the hydrocarbons
emitted to the atmosphere are from fugitive emissions. The principal contribu-
tors generally are valves, flanges, pumps, and compressors. Since 1981, valves
and flanges must be repaired if they have emission concentrations greater than
10,000 ppm, when measured at the source with a hydrocarbon analyzer. They
must be inspected every six months to a year. Pumps and compressors, however,
need to be checked every shift to verify that they meet current emission
standards.
It is becoming increasingly clear that chemical engineers must be versed in
the latest federal and state regulations involving environmental protection,
worker safety, and health. This need is especially great for engineers in