Apparatus and process for separating reaction effluent in the manufacture of cumene

An apparatus and process for separating propane and benzene from alkylation reaction products in cumene production. An integrated fractionation tower combines the functions of propane separation, recycle benzene recovery as well as system dewatering to eliminate the need for separate depropanizer and dehydration columns and thus save capital and operating expenses.

FIELD OF THE INVENTION 
The present invention relates to an apparatus and process for making 
cumene, and more particularly an apparatus and process for separating 
propane, benzene and water, if present, from an alkylation reaction 
effluent in an integrated fractionation tower. 
BACKGROUND OF THE INVENTION 
Isopropylbenzene (cumene) is widely used for making phenol, acetone and 
a-methylstyrene. Phenol is a feedstock in phenolic polymer manufacture and 
acetone is a by-product of the phenol production process. 
.alpha.-Methylstyrene is a feedstock for elastomeric polymers. Cumene is 
made by a direct alkylation reaction of propylene and benzene in the 
presence of an acidic catalyst. Cumene is then separated from reactants, 
by-products, contaminants and inert components in the reaction effluent by 
fractionation. 
Heretofore, cumene manufacturing processes have generally employed an 
acidic catalyst such as solid phosphoric acid (SPA), aluminum chloride, 
and the like. Catalysts such as SPA can require the presence of water for 
activation and produce an extremely corrosive sludge by-product. The use 
of such sludge-forming catalysts involves special design considerations 
regarding corrosion, safety and disposal which are expensive to 
accommodate. Similarly, aluminum chloride catalyst requires anhydrous 
hydrochloric acid for activation. This corrosive catalyst system requires 
expensive corrosion-resistant materials in the construction of the 
reactor, and the spent catalyst also presents disposal problems. More 
recently, the introduction of new non-corrosive catalysts have reduced the 
need for the corrosion resistant alloys previously required. 
U.S. Pat. No. 4,870,222 to Bakas et al. describes a process for the 
production of a monoalkylated aromatic compound which minimizes the 
production of undesirable alkylating agent oligomers, and produces 
monoalkylaromatics in high yields. The process entails the combination of 
an alkylation reaction zone, a separation zone and a transalkylation 
reaction zone wherein the alkylation catalyst and transalkylation catalyst 
are dissimilar and the catalysts comprise a silica-alumina material. 
U.S. Pat. No. 5,198,595 to Lee et al. describes an acidic mordenite zeolite 
catalyst useful for producing a monoalkylated benzene product. The zeolite 
catalyst has a silica/alumina molar ratio of at least 40:1. 
Other references in interest include U.S. Pat. Nos. 5,243,115, 5,055,627 
and 5,176,883 to Smith, Jr. et al., 5,262,576 to Smith, Jr., 5,080,871 to 
Adams et al., 5,149,894 to Holtermann et al., 5,081,323 to Innes et al., 
5,043,506 to Crossland, 4,950,834 to Arganbright et al., 4,347,393 to 
Miki, 3,855,077 to Bleser et al.; WO 91-18849; and WO 93-02027. 
SUMMARY OF THE INVENTION 
The functions of multiple individual fractionation columns previously used 
to separate propane and benzene from the combined 
alkylation/transalkylation reactor effluent are combined into a single 
fractionation tower in the present invention to accomplish substantial 
capital and energy savings over the prior art. 
As one embodiment of the present invention, a fractionation tower useful 
for separating propane and benzene from alkylation reactor products is 
disclosed. In the present fractionation tower, a first feed stage is 
provided for receiving cumene alkylation products comprising propane, 
benzene, cumene, diisopropylbenzene and heavier benzene alkylates. A 
bottom stage is provided in a heated stripping zone below the first feed 
stage for recovering a cumene stream containing diisopropylbenzene and 
heavier benzene alkylates essentially free of propane and benzene. An 
overhead partial condenser is provided for recovering a mixture of benzene 
condensate from an overhead vapor stream from the tower and forming a 
propane stream of reduced benzene content. A first line is provided for 
refluxing the benzene stream from the separator to a reflux stage of the 
tower. A second line is provided for recovering a benzene side-draw from a 
benzene recovery stage disposed between the first and second feed stages. 
In a preferred embodiment, the tower is operatively associated with an 
absorber for contacting the propane stream with a diisopropylbenzene 
stream to form a propane stream essentially free of benzene and a 
diisopropylbenzene recycle stream containing benzene suitable for recycle 
to a cumene alkylation reactor. Any water contained in a make-up benzene 
stream can be condensed and recovered by the overhead partial condenser to 
form a mixture of hydrocarbons and water condensate, and a separator is 
preferably provided for separating the hydrocarbon-water mixture to form 
hydrocarbon and water streams. A second feed stage is preferably provided 
above the first feed stage and below the reflux stage for receiving the 
wet make-up benzene. A side-stripper including a heated stripping zone and 
a vapor return line can be provided for stripping water from the benzene 
side-draw to form a dehydrated benzene stream suitable for recycle to the 
cumene alkylation reactor, and returning vapor from the side-stripper to 
adjacent the benzene side-draw line, respectively. 
As another embodiment, an apparatus for separating cumene alkylation 
reactor products is provided. The apparatus comprises a raw cumene feed 
stage for receiving a stream of alkylated benzene containing propane and 
benzene from the cumene alkylation reactor. A heated stripping zone is 
provided in fluid communication between the raw cumene feed stage and a 
bottoms stage. A line is provided for recovering a bottoms product stream 
from the bottoms stage, comprising alkylated benzene essentially free of 
benzene. A benzene rectification zone is provided in fluid communication 
between the raw cumene feed stage and a recycle benzene side-draw stage. A 
partial condenser and reflux accumulator are provided for partially 
condensing a vapor stream from the overhead stage to form a liquid 
hydrocarbon phase and a vapor stream comprising propane and a minor amount 
of benzene. An absorber is provided for contacting the vapor stream from 
the partial condenser with an alkylated benzene stream to form a propane 
stream essentially free of benzene and an alkylated benzene stream 
containing a minor amount of benzene. 
In a preferred embodiment, a water stripping zone is provided in fluid 
communication between a make-up benzene feed stream, and an overhead 
product stage is provided to dewater the make-up benzene feed and form an 
aqueous phase in the reflux accumulator. Lines are provided for decanting 
the aqueous phase from the accumulator and or refluxing the liquid 
hydrocarbon phase from the accumulator to the water stripping zone. 
As a further embodiment, the present invention comprises a process for 
separating a reactor effluent comprising propane, benzene, cumene, 
diisopropylbenzene and heavier benzene alkylate. In step (a), the reactor 
effluent is fed to a reactor effluent feed stage of a superatmospheric 
fractionation tower comprising lower, middle, and upper distillation 
zones, wherein the reactor effluent feed stage is in fluid communication 
between the lower distillation zone below and the middle distillation zone 
above. As step (b), the lower distillation zone is heated to strip benzene 
and form a bottoms product of reduced benzene content comprising cumene, 
diisopropylbenzene and heavier benzene alkylates. In step (c), a benzene 
stream is removed as a side draw from the tower at a side-draw stage in 
fluid communication between the middle distillation zone below and the 
upper distillation zone above. As tep (d), a vapor stream is removed 
overhead from the upper distillation zone. In step (e), benzene is 
condensed from the overhead vapor stream from step (d) to form a 
benzene-lean propane stream. 
In a preferred embodiment, as step (f), a make-up benzene stream is fed to 
a make-up benzene feed stage of the tower in fluid communication between 
the upper distillation zone below and a top distillation zone above. In a 
step (g), water is separated from the benzene condensed in step (e) to 
form a wet benzene stream. As step (h), the wet benzene stream from step 
(g) is refluxed to the top distillation zone. In a step (i), the bottom 
product from step (b) is preferably fed to a cumene column to obtain a 
cumene product stream essentially free of diisopropylbenzene and heavier 
benzene alkylates, and a bottoms stream comprising diisopropylbenzene and 
heavier benzene alkylates. In a step (j), the bottoms stream from step (i) 
is preferably fed to a diisopropylbenzene column to obtain a 
diisopropylbenzene stream essentially free of heavier benzene alkylates. 
As step (k), the propane stream from step (e) is contacted with the 
diisopropylbenzene stream from step (j) in an absorber to obtain a propane 
stream essentially free of benzene and a diisopropylbenzene stream 
containing benzene absorbed from the propane stream. The process can 
further comprise as step (l), compressing and cooling the propane stream 
from step (k) to form liquefied petroleum gas. The process can also 
comprise as step (m) feeding the benzene stream from step (c) to a heated 
side-stripper to form a dehydrated liquid benzene stream and a benzene 
vapor stream of enhances water content, and as step (n) returning the 
benzene vapor stream from step (m) to adjacent the side draw stage of step 
(c). 
In yet another embodiment, the present invention provides an improved 
method for making cumene. In a method comprising the steps of dehydrating 
make-up benzene, alkylating benzene and propylene and transalkylating 
benzene and diisopropyl benzene to form cumene reactor products, 
distilling the cumene reactor products to form steams of propane, recycle 
benzene, cumene, recycle diisopropylbenzene and heavier benzene alkylates, 
and recycling the recycle benzene stream to the alkylating and 
transalkylation steps and the recycle diisopropylbenzene stream to the 
transalkylating step, the improvement comprises the steps of: (a) feeding 
the cumene reactor products and the make-up benzene to separate feed 
stages of a first superatmospheric fractionation tower; (b) recovering a 
bottoms product from the first tower comprising cumene, diisopropylbenzene 
and heavier benzene alkylates essentially free of benzene; (c) recovering 
the benzene recycle stream as a side-draw from the first tower below the 
make-up benzene feed stage and above the cumene reactor products feed 
stage; (d) partially condensing an overhead stream from the first tower to 
form a propane vapor stream containing a minor amount of benzene and a 
liquid mixture of benzene and water; (e) separating the liquid mixture 
into an aqueous stream and a benzene condensate stream; (f) refluxing the 
benzene condensate stream to the first tower above the make-up benzene 
feed stage; (g) fractionating the bottoms product from the first tower to 
form streams of cumene, diisopropylbenzene and heavier benzene alkylates; 
(h) contacting the propane vapor stream from step (d) with the 
diisopropylbenzene stream from step (g) to form a propane stream 
essentially free of benzene and a diisopropylbenzene stream containing a 
minor amount of benzene; (i) supplying the benzene-containing 
diisopropylbenzene stream from step (h) as the recycle diisopropylbenzene 
stream to the transalkylation step.

DETAILED DESCRIPTION OF THE INVENTION 
The present invention permits integration of multiple fractionation columns 
used to recover propane and recycle benzene from alkylation reaction 
effluent into a single fractionation tower. In addition, the integrated 
tower can be used to dewater a wet benzene make-up stream and dry the 
recycle benzene stream. In such a manner, a separate high pressure 
depropanizer column and associated utility requirements are eliminated, 
and a separate benzene drying column can be omitted for significant 
capital and operational savings. 
Referring to FIG. 1, a cumene reactor effluent separation process 10 of the 
present invention comprises an alkylation stage 12 and a cumene recovery 
stage 14. In the present process, benzene is alkylated by propylene to 
produce cumene in the presence of a suitable catalyst, preferably a 
non-corrosive acidic zeolite catalyst. Preferred catalysts are exemplified 
by a special mordenite zeolite catalyst sold under the trademark 3DDM by 
the Dow Chemical Co. of Midland, Mich. and described in U.S. Pat. Nos. 
5,198,595; 5,004,841; and 4,891,448 which are hereby incorporated herein 
by reference. 
Using the preferred zeolite catalyst, propylene in the feed to the 
alkylation stage 12 is substantially completely reacted in an excess of 
benzene to produce monoisopropylbenzene, diisopropylbenzene (DIPB, para 
and meta isomers) and a very minor amount of triisopropylbenzene (TIPB). 
The amount of DIPB formed will depend on the quantity of excess benzene 
over propylene fed to the alkylation stage 12 and alkylation operating 
conditions. Other alkylbenzenes can be formed from olefinic impurities 
such as ethylene and butylene in the propylene feed as well as some 
n-propylbenzene. However, alkylation conditions are preferably chosen to 
maximize formation of cumene and avoid formation of n-propylbenzene and 
other impurities. 
The preferred zeolite catalyst is also preferably used to transalkylate 
DIPB to cumene and the transalkylation reaction conditions are chosen to 
favor cumene formation. Unlike the alkylation reaction which is rapid and 
exothermic, the transalkylation reaction is slow, equilibrium-limited and 
thermally neutral. Overall, cumene can be produced at very high purity 
(99.9 wt %) with a bromine index (for olefinic content) of less than 5. 
Propylene is introduced to the alkylation stage 12 via line 16. The 
propylene stream 16 typically comprises a significant but minor amount of 
propane which is inert. The amount of propane in the propylene stream 16 
can vary from about 1 to about 40 percent by weight depending on the 
source. Other common impurities include sulfur, propadiene, oxygenates, 
water, basic nitrogen, and the like. Such impurities are typically removed 
by pretreatment (not shown) with an adsorbent particulate such as 
molecular sieve or activated alumina, for example, or in a suitable 
distillation column. 
The propylene stream 16 is combined with a dry benzene reactant stream 
introduced through line 22 for feed to an alkylation reaction zone (not 
shown) in the alkylation stage 12. The alkylation reaction zone typically 
has a fixed catalyst bed wherein the benzene is alkylated to produce 
cumene, DIPB, and other minor alkylated by-products as mentioned above. A 
raw cumene reaction effluent primarily comprising cumene, unreacted 
benzene, and propane but essentially no propylene is typically obtained 
from the alkylation reaction zone. A DIPB recycle stream 24 is typically 
fed to a transalkylation reaction zone (not shown) in the alkylation stage 
12. The catalyst in the transalkylation zone converts the DIPB and an 
excess of benzene from line 22 to cumene. The effluents from the 
alkylation and transalkylation zones are typically combined into a single 
stream 30 for cumene recovery. Alternatively, the effluent from the 
alkylation zone can be fed to the transalkylation zone with the recycle 
DIPB and benzene, in which case the stream 30 is obtained primarily from 
the transalkylation reaction zone. 
In the practice of the present invention, the cumene recovery stage 14 
comprises an integrated fractionation tower 32 suitable for separating 
propane, recovering unreacted benzene and dewatering make-up benzene, if 
necessary. As is well known, propylene is produced by the catalytic or 
steam cracking of a hydrocarbon feedstock. Following separation of lighter 
and heavier components, a raw propylene stream having a significant amount 
of propane can be obtained. Typically, further distillation in a high 
pressure depropanizer column is carried out for the cumene process to 
remove the propane contaminant. However, in the present invention, the 
propane contaminant is inert and is not beneficially recycled to the 
alkylation stage 12 in the present process as an aid in heat removal (as 
in the SPA process). The propylene reactant is essentially completely 
reacted. Thus, the non-reacting propane can be recovered at a much lower 
pressure in the tower 32 used to obtain benzene for recycle. 
In addition, since water can be present in make-up benzene, such a wet 
make-up benzene stream is preferably introduced to the tower 32 via line 
34 for dewatering to less than 1 ppm (by weight) and thus eliminates the 
need for separate dehydration pretreatment. Water could otherwise 
deactivate the reaction catalyst and become a source of corrosion in the 
system. If water is present in the alkylation effluent stream 30, such as 
during start-up, or if the stream 30 is water washed as in the aluminum 
chloride process or is wet for other process reasons, a small, low cost 
side stripper 36 (see FIG. 2) can also be employed, if desired, to further 
reduce the water content in benzene recycled to the reaction stage 12. 
Although more costly, a benzene dehydration pretreatment column (not 
shown) could alternatively or additionally be used to dry the make-up 
benzene stream 34, in which case, dewatering in the tower 32 becomes 
unnecessary. 
As best seen in FIG. 2, the fractionation tower 32 comprises a first feed 
stage 38 receiving the raw cumene effluent stream 30 and preferably a 
second feed stage 40 for receiving a make-up benzene stream 34 which can 
contain water. (Underlined numerals S2, S4, S11, S12, S23, and S32 shown 
within the tower 32 in FIG. 2 are used to indicate exemplary tray or 
theoretical stage locations within the tower 32.) The make-up benzene 
stream 34, depending on the source, can comprise non-aromatic inerts such 
as cyclohexane in addition to a varying amount of water. 
The tower 32 includes a propane stripping zone 42 having a bottom stage 44 
below the first feed stage 38 wherein cumene, DIPB and heavier benzene 
alkylates are separated and recovered via line 46 as a bottoms stream. 
Another bottoms stream 48 is supplied to a thermosiphon reboiler 50 to 
generate a vapor-containing return stream 52. The reboiler 50 is 
preferably a steam reboiler, but could alternatively use hot oil or be a 
fired furnace, depending on the tower 32 operation pressure. 
The tower 32 also includes a cumene absorption zone 56 having a top stage 
58 above the first feed stage 38 wherein propane and water, if present, 
are concentrated and recovered via overhead line 60. The overhead line 60 
is partially condensed by a partial condenser 62 employing a cooling 
medium such as cooling water or ambient air to condense condensables 
(benzene and water). A partially condensed tream is introduced via line 64 
to an accumulator 66 wherein vapor and liquids are separated. A vapor 
stream substantially comprising propane s removed via line 68. A 
benzene-rich liquid stream is pumped by pump 70 as a reflux liquid to the 
absorption zone 56 via line 72. The accumulator 66 preferably has a leg 74 
wherein water which has a higher density than benzene can accumulate. A 
waste water stream is decanted from the accumulator leg 74 via line 76 for 
cleanup and disposal. 
A side-stream substantially comprising dry benzene is withdrawn from a 
benzene recovery stage 77 of the tower 32 via line 78 for recycle to the 
alkylation stage 12. The benzene recycle side-stream 78 can be introduced 
to a surge drum (not shown) and pumped by a pump 82 to the alkylation 
stage 12 via line 22 as previously mentioned. To facilitate operation of 
the tower 32, the liquid in line 78 is preferably drawn off using a 
chimney tray, and returned below the sidedraw tray by the pump 82 via line 
84. A purge stream (not shown) can be withdrawn from the recycle benzene 
stream 22 to reject any inert alkanes, such as, for example, i-butane, 
n-pentane, 3-methylpentane, 3-methylhexane, 2,3-dimethylpentane, n-hexane, 
cyclohexane, n-nonane, and the like. 
Prior to circulation to the alkylation stage 12, the benzene side-stream 78 
can be dehydrated, as mentioned above, if desired, by the optional 
side-stripper 36. Thus the benzene side-stream 78 can be introduced via 
line 88 to the side-stripper 36 wherein additional water is removed by a 
stripping vapor generated by a reboiler 90. A water-enriched overhead 
vapor is returned to the benzene recovery zone 77 via line 92. An 
essentially anhydrous benzene stream, thus formed, is recycled to 
alkylation stage 12 via line 94. Where the make-up benzene stream is dried 
in the pretreatment dehydration column (not shown), dry-make-up benzene 
could be combined directly with the recycle benzene stream 22. 
The fractionation tower 32 preferably has an operating pressure between 0.2 
and 6.0 MPa(g) and can be made of carbon steel due to a generally 
non-corrosive environment. A relatively large number of theoretical stages 
is required and approximately 33 are preferred with the first feed point 
38 at about the twenty-third stage S23 (from the top), the second feed 
point 40 at about the fourth stage S4, and the benzene recovery point 77 
at about the eleventh stage S11 (see FIG. 2). 
The cumene-rich bottoms steam 46 is fed to a cumene recovery column 96. The 
cumene column 96 comprises a DIPB absorption zone 100 above a feed stage 
102 and a cumene stripping zone 104 below the feed point 102. A 
benzene-containing stream can be removed overhead and substantially 
condensed by a condenser (not shown). A liquid benzene-containing stream 
can be accumulated in a surge drum (not shown) and pumped as a reflux 
liquid to the absorption zone 100. A portion of the reflux stream can be 
recycled to the benzene recovery tower 32. Non-condensable components 
lighter than benzene are removed via a small purge line (not shown) for 
disposal. The condenser preferably employs low pressure boiler feed water 
as cooling medium and can generate low pressure steam. 
A DIPB-rich bottoms stream is withdrawn from the cumene column 96 via line 
119 and pumped through a reboiler (not shown) to generate reboil vapor. 
The vapor stream is returned to the stripping zone 104. The reboiler is 
preferably a steam heated reboiler, but could be a fired furnace or heated 
with hot oil. 
A side stream substantially comprising a purified cumene product can be 
withdrawn from the cumene column 96 via line 128. The cumene product 
stream 128 is preferably cooled and pumped to a storage facility (not 
shown). 
The DIPB-rich bottoms stream 119 is pumped to a DIPB recovery column 130. 
The DIPB column 130 comprises a light impurity absorption zone 134 above a 
feed stage 136 and a DIPB stripping zone 138 below the feed point 136. A 
stream (not shown) containing components lighter than DIPB can be removed 
overhead, substantially condensed and accumulated in a surge drum (not 
shown). A light liquid impurity stream can be used as a reflux liquid to 
the absorption zone 134. A small purge stream (not shown) of light liquid 
impurity components can be removed in a continuous fashion from the surge 
drum to maintain a subatmospheric pressure in the DIPB column 130. The 
condenser preferably uses ambient air as a cooling medium. 
A bottoms stream containing heavy components is removed from the DIPB 
column 130 via line 150, and a portion thereof can be directed to a 
reboiler (not shown) to generate reboil vapor. The vapor stream is 
returned to the stripping zone 138. The reboiler can preferably employ the 
cumene column reboil vapor or liquid as a heating medium. The rest of the 
column bottoms in line 150 is removed for disposal as a fuel oil, for 
example. A portion of the reflux liquid stream (not shown) can also be 
diverted to fuel oil via the line 150. 
A side stream substantially comprising a purified DIPB product is withdrawn 
from the DIPB column 130 via line 166 and fed to the alkylation stage 12 
for transalkylation into cumene. Prior to transalkylation however, all or 
a portion of the DIPB stream 166 is used as a liquid absorbent for 
absorbing benzene from the propane-rich stream 68. The DIPB absorbent 
stream 166 can be cooled by a cooler (not shown) and introduced to an 
upper end of a benzene absorption column 174 via line 176. The cooler can 
preferably employ cooling water as a cooling medium. In the absorption 
column 174, the propane-rich vapor stream 68 is countercurrently contacted 
with the cooled liquid DIPB stream 176 to absorb residual benzene from the 
vapor stream 68. 
A substantially benzene free propane stream is removed overhead via line 
178 for further processing in a gas processing unit (not shown) depending 
on the initial propane content of the propylene feed 16. If the propane 
content of the propylene feed 16 is relatively high, the propane stream 
178 can be liquefied. In this case, a liquefied propane gas (LPG) product 
is produced. If the initial propane content in the propylene feed stream 
16 is relatively low or if propane fuel gas is preferable to LPG product, 
the propane stream 178 can be used in a fuel gas system (not shown). A 
DIPB-rich bottoms stream is removed from the absorber 174 via line 184, 
combined with that portion of the DIPB stream 166 not used as absorbent, 
if any, and directed via line 24 to the alkylation stage 12. 
EXAMPLE 1 
A non-corrosive cumene manufacture process (see FIGS. 1 and 2) based on the 
preferred zeolite catalyst employing the integrated tower 32 of the 
present invention to recover benzene and separate propane is simulated by 
computer algorithm using a 31,750 kg/hr (69,850 lb/hr) cumene production 
rate as basis for the calculations. The propylene feed contains 5 weight 
percent propane. The calculated design specifications of the tower 32 are 
33 theoretical trays in a tower with a 2.13 m (7 ft) diameter top portion 
and a 2.59 m (8.5 ft) bottom portion. Purified benzene is optimally 
recovered at tray 11. Reaction effluent is optimally introduced at tray 
23. The calculated design specifications of the absorption column 174 are 
10 trays and a 0.457 m (1.5 ft) diameter. Results in terms of feed, 
product and by-product stream compositions are given in Table 1. 
Calculated utility requirements are presented in Table 3. 
EXAMPLE 2 
A similar non-corrosive cumene manufacturing process to the process of 
Example 1 is simulated by computer algorithm except that the composition 
of one of the feed streams differs, the propylene contains 30 weight 
percent propane. The dimensions of the tower 32 are the same as in Example 
1, but the diameter of the absorption column 174 increases to 0.762 m (2.5 
ft) due to the larger propane flow. Results in terms of feed, product and 
by-product stream compositions are presented in Table 2. Energy 
utilization is presented in Table 3 with the data from Example 1. 
TABLE 1 
__________________________________________________________________________ 
Fresh 
Make-up 
Tower 
Tower 
Condensed 
DIPB To 
Absorber 
Absorber 
Tower 
Tower 
Propylene 
Benzene 
Feed 
Overhead 
Water Absorber 
Overhead 
Bottoms 
Sidedraw 
Bottoms 
Stream 16 34 30 68 76 176 178 184 22 46 
__________________________________________________________________________ 
Temperature (.degree.F.) 
70 70 300 119 119 95 118 140 272 450 
Pressure (psig) 
200 150 200 38.9 38.9 50 26.3 28.3 200 50.3 
Component 
MW FLOW RATE (LB/HOUR) 
Propane 
44 
1,298 1,490 
1,412 1,298 
114 78 
Propylene 
42 
24,668 
Cyolohexane 
84 35 11,743 
2 2 11,776 
Benzene 
78 46,026 
92,069 
245 0 245 137,850 
EB 106 3 3 
Cumene 
120 69,938 2 2 61 69,877 
NPB 120 9 9 
BB 134 6 6 
P-Cymene 
134 36 36 
M-Cymene 
134 18 18 
C11 148 801 49 49 801 
P-DIPB 
162 20,085 1,250 
2 1,248 20,085 
M-DIPB 
162 10,042 625 1 624 10,042 
C6-Benzene 
162 386 23 23 386 
TIPB 204 15 1 1 15 
Toluene 
92 37 37 
Heavies 
240 83 0 0 83 
Water 18 22 20 2 20 &lt;1 PPM 
TOTAL 25,966 
46,120 
206,723 
1,678 
2 1,950 
1,321 
2,307 
149,802 
101,360 
__________________________________________________________________________ 
TABLE 2 
__________________________________________________________________________ 
Fresh 
Make-up 
Tower 
Tower 
Condensed 
DIPB To 
Absorber 
Absorber 
Tower 
Tower 
Propylene 
Benzene 
Feed 
Overhead 
Water Absorber 
Overhead 
Bottoms 
Sidedraw 
Bottoms 
Stream 16 34 30 68 76 176 178 184 22 46 
__________________________________________________________________________ 
Temperature (.degree.F.) 
70 70 300 121 121 95 118 142 264 450 
Pressure (psig) 
350 150 350 38.9 38.9 50 26.3 28.3 350 50.3 
Component 
MW FLOW RATE (LB/HOUR) 
Propane 
44 
10,577 12,094 
11,484 10,575 
909 610 
Propylene 
42 
24,680 
Cyclohexane 
84 35 11,740 
29 29 11,746 
Benzene 
78 46,037 
93,919 
2,038 1 2,037 
137,918 
EB 106 3 3 
Cumene 
120 69,939 14 14 62 69,877 
NPB 120 9 9 
BB 134 6 6 
P-Cymene 
134 36 36 
M-Cymene 
134 18 18 
C11 148 800 385 385 800 
P-DIPB 
162 20,085 9,939 
18 9,921 20,085 
M-DIPB 
162 10,042 4,970 
9 4,961 10,042 
C6-Benzene 
162 386 185 185 386 
TIPB 204 15 4 4 15 
Toluene 
92 37 37 
Heavies 
240 83 3 3 83 
Water 18 23 21 3 21 &lt;1 PPM 
TOTAL 35,257 
46,133 
219,175 
13,573 
3 15,500 
10,624 
18,448 
150,373 
101,359 
__________________________________________________________________________ 
As seen in Table 3, the utilities consumptions are nearly identical in 
Examples 1 and 2; there is only a slight penalty for more propane in the 
propylene feed as long as the propane is obtained as a vapor from the 
tower 32. Utilities increase for the Example 2 case if the gas is 
compressed and condensed to produce LPG. Overall capital costs and 
utilities remain lower for the integrated tower 32 as compared to the 
individual columns of the prior art design. 
TABLE 3 
______________________________________ 
Utility Summary 
Single Column Design 
5% Propane 30% Propane 
(Example 1) (Example 2) 
HP Elec- 
HP Elec- 
Steam CW tricity 
Steam CW tricity 
Description lb/hr gpm kW lb/hr gpm kW 
______________________________________ 
Tower Condenser 62 2,219 2,247 
Tower Reboiler 50 
47,737 47,599 
Absorber Feed Cooler 5 37 
(not shown) 
DIPB Cooler (not shown) 
23 182 
Recycle Benzene Pumps 56 56 
82 
Tower Reflux Pumps 48 22 22 
DIPB Absorber Pumps 8 11 
(not shown) 
TOTAL 47,737 2,247 84 47,599 
2,466 
90 
______________________________________ 
The present cumene manufacturing process and apparatus are illustrated by 
way of the foregoing description which is intended as a non-limiting 
illustration, since many variations will become apparent to those skilled 
in the art in view thereof. It is intended that all such variations within 
the scope and spirit of the appended claims be embraced thereby.