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7/28/2019 CHE Plant Design I Example
http://slidepdf.com/reader/full/che-plant-design-i-example 1/7
Example
Benzene, Toluene and Xylenes are important upstream products widely used inpetrochemical industry. They can be produced from naphtha by catalytic reforming reaction. '
Reaction products from reforming reactor are separated and purified to produce high qualitygrade Benzene, Toluene and Xylenes. During production process, contaminated product
stream (product stream with several compounds mixed together) is also produced as a
byproduct. A sample composition of the byproduct stream is shown in Table 1. Thisbyproduct stream can be converted to valuable products by additional processes such as
hydrodealkylation, isomerization and dismutation processes.
. Table 1
Composition of Byproduct Stream
v,tto/o
Benzene 6Toluene 47
Ethylbenzene 11
m-Xylene* 34
o-Xylene Balance
Hydrodealkylation of Toluene, Ethylbenzene and Xylene can be operated with or withoutcatalyst. Operating conditions of the reactor depend on the operating mode selected. Ourresearch laboratory conducted several experiments using special type of catalyst and
concluded that the reactions proceed as follow
CaHs-CHt + Hz - CaHa + CHd, (l)CaCs-CzHs + Hz - CaHa + CzHa (2)
CaHs-(CHz)z + 2Hz - 2CoHa + 2CHt, (3)
2CaHe ' CeHs-CaHs + Hz (4)
Reaction (4) is the only side reaction occured. Each reaction proceeds at different rate andgives different conversion at reactor outlet. Using data available from our experiments it is
estimated that conversion of reactions (2) to (4) are as follow
xz = 1 - 0.381rr
x3 = 0.746 xr
x4 = 0.012 (xr + xz)
Where xt, x2, J[3 and x4 ara conversions of Toluene, Ethylbenzene, Xylenes and Benzene,
respectively. Conversions of reactions (1) to (3) are estimated at the reactor inletconcentration of each reactant but conversion of reaction (4) is estimated at the reactor outletconcentration.
7/28/2019 CHE Plant Design I Example
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High purity grade product and byproduct are to be produced from_.this process. Hydrogenfeedstream is not a pure hydrogen gas and it contains approximately 5.8 wtTo of methane. Anexcess amount of hydrogen is required at the reactor inlet and at the process inlet.
The company plans to design a catalytic hydrodealkylation process for the production ofBenzene at Toluene conversion (x1) of 0.8. High purity Toluene or mixed Xylene can also
produced as byproducts if desired. Product stream has a capacity of 350,000 tonnes per year
ofBenzene.
7/28/2019 CHE Plant Design I Example
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7/28/2019 CHE Plant Design I Example
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7/28/2019 CHE Plant Design I Example
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7/28/2019 CHE Plant Design I Example
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7/28/2019 CHE Plant Design I Example
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