Environmental Engineering Reference
In-Depth Information
1931). This method required shutting down the opera-
tion to regenerate the aluminosilicate catalyst. Warren K.
Lewis and Edwin R. Gililand introduced a moving-bed
arrangement, with the catalyst circulating between the
reaction and the regeneration vessels. By 1942, 90% of
all U.S. aviation fuel came from catalytic cracking.
An even greater yield of high-octane gasoline was
achieved in 1942 with the commercialization of airborne
powdered catalyst (Campbell et al. 1948). This fluid cat-
alytic cracking, invented by a group of four Standard Oil
chemists in 1940, was improved in 1960 with the addi-
tion of synthetic zeolite, a crystalline aluminosilicate with
uniform pores, to act as an exceptionally active and stable
catalyst facilitating the cracking of heavy hydrocarbons
(Plank and Rosinski 1964). Zeolite Y improved the gaso-
line yield by as much as 15%. During the 1950s, Union
Oil Company developed hydrocracking, which combines
catalysis at temperatures above 350 C with hydrogena-
tion at relatively high pressures (10-17 MPa). Large-
pore zeolites loaded with a heavy metal (Pt, W, or Ni)
serve as dual function catalysts to produce high yields of
gasoline and low yields of less desirable CH 4 and C 2 H 6 .
Large refineries process in excess of 100,000 bbl/day,
or at least 5 Mt/a of crude (input rating 6.6 GW).
The average for Texas refineries is twice as large, and the
state's largest refinery processes annually nearly 28 Mt of
crude oil (input rating 37 GW). In the early 2000s the
world's largest refineries were in South Korea, where
Ulsan's capacity was nearly 44 Mt/a and Yosu's 32
Mt/a, and in Singapore, where Exxon's Jurong Island
rated 30 Mt/a. Europe's largest facility was Pernis in the
Netherlands (nearly 21 Mt/a) and the Middle East's was
Saudi R ¯ s Tan ¯ ra (26 Mt/a). Crude oil refining, produc-
ing a wide variety of highly flammable gases and liquids,
requires safety precautions in locating the processing and
storage facilities, preventing spills, and facilitating fire
fighting.
Minimum spacing of 60-75 m is mandatory to sepa-
rate many parts within a refinery; large storage units can-
not be placed closer than one-sixth to one-third of the
sum of adjacent tank diameters. The standard planning
requirement for modern refineries prorated to through-
puts of about 3300 W/m 2 during the last quarter of the
twentieth century (Gary and Handwerk 1984). Actual
footprints depend on the extent of buffer zones and on-
site storage, on the mode of crude oil delivery and pro-
cessing, and on areas reserved for possible expansion. As
a result, actual throughput power densities range from as
low as 60 W/m 2 at the Los Angeles refinery complex to
more than 7 kW/m 2 at Exxon's huge Baton Rouge re-
finery in Louisiana. Values of 1-4 kW/m 2 are perhaps
most common for large operations; the largest U.S. re-
finery, Exxon's Baytown in Texas, rates nearly 4 kW/m 2 .
The chemical energy of fossil fuels is converted to heat
by combustion, the rapid oxidation of carbon and hy-
drogen (reaction times are 0.1 ms for gases, 1 s for
pulverized coals), which is the single most important
anthropogenic energy conversion in industrial civiliza-
tion. Combustion temperatures range from the mini-
mum needed to support a stable flame (just short of
1000 C) to maxima posed by the practical difficulties
of containing the hot flame within solid walls. The hot-
test firebox flame in large boilers is about 1600 C. Com-
plete combustion of 1 g of carbon requires 2.66 g of O 2
(11.53 g of air), producing 3.66 g of CO 2 and releasing
33 kJ/g. The corresponding figures for complete com-
bustion of hydrogen are 7.94 g of O 2 (34.34 g of air),
producing 8.94 g of H 2 O and releasing 121 kJ/g.
Oxidation of
sulfur or H 2 S represents a negligible
contribution.
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