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    Design of Distillation Column

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    Urva
    This document provides information needed to design a distillation column to separate a benzene-toluene mixture. It gives the specifications of the feed stream, desired purities of overhead and bottoms streams, reflux ratio, and various physical property data. The design tasks are to: (1) determine the number of theoretical plates and feed location, (2) calculate the reboiler duty, (3) compute the column height, and (4) determine the column diameter based on vapor velocity.

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    Design of Distillation Column

    Uploaded by

    Urva
    31 views5 pages
    This document provides information needed to design a distillation column to separate a benzene-toluene mixture. It gives the specifications of the feed stream, desired purities of overhead and bottoms streams, reflux ratio, and various physical property data. The design tasks are to: (1) determine the number of theoretical plates and feed location, (2) calculate the reboiler duty, (3) compute the column height, and (4) determine the column diameter based on vapor velocity.

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    This document provides information needed to design a distillation column to separate a benzene-toluene mixture. It gives the specifications of the feed stream, desired purities of overhead and bottoms streams, reflux ratio, and various physical property data. The design tasks are to: (1) determine the number of theoretical plates and feed location, (2) calculate the reboiler duty, (3) compute the column height, and (4) determine the column diameter based on vapor velocity.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    31 views5 pages

    Design of Distillation Column

    Uploaded by

    Urva
    This document provides information needed to design a distillation column to separate a benzene-toluene mixture. It gives the specifications of the feed stream, desired purities of overhead and bottoms streams, reflux ratio, and various physical property data. The design tasks are to: (1) determine the number of theoretical plates and feed location, (2) calculate the reboiler duty, (3) compute the column height, and (4) determine the column diameter based on vapor velocity.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 5

    Design of distillation column

    Design of distillation column

    Number of theoretical stages

    (a) Column height (H)


    For a given tray
    efficiency
    Ex. 30 %
    The actual number
    of plates required
    ∆𝐻𝑓
    𝑞 =1+ 𝑁𝑡 −1
    𝜆𝑠 (𝑁𝑎 ) =
    ή𝑝
    ∆𝐻𝑓 = (𝐻𝑓𝑠 − 𝐻𝑓 ) = 𝐶𝑝 𝑇𝑠𝑓 − 𝑇𝑓

    𝑞
    𝑠𝑙𝑜𝑝𝑒 =
    𝑞−1 H = (𝑁𝑎 − 1) x Plate spacing (P) + 2 P
    𝑥𝐷
    𝐼𝑛𝑡𝑒𝑟𝑐𝑒𝑝𝑡 =
    𝑅+1
    • Column diameter (D) (at the top)

    • Vapor rate 𝑉 = 𝐷(𝑅 + 1) = 𝑛ሶ


    𝑅𝑇
    ሶ
    • Volume of vapour rate 𝑄 = 𝑛ሶ
    𝑃
    𝜌𝐿 −𝜌𝑉
    • Vapour velocity (v ) = 𝐾𝑉 (m/s)
    𝜌𝑉

    𝑉𝑜𝑙 𝑣𝑎𝑜𝑝 𝑟𝑎𝑡𝑒 𝑄ሶ m3/𝑠


    • Cross sectional area of the column (C.S.A) = 𝑚 =m
    2
    Vapour velocity (v ) 𝑠
    𝐶.𝑆.𝐴 𝑥 4
    • Column diameter (D) =
    𝜋
    A feed mixture containing 44 mole% benzene and balance toluene is fed to a continuous fractionating column at the rate of 9
    ton/hr to yield an overhead product of 97.4% mole benzene and a bottom product of 2.3% mole benzene. A reflux ratio of 3.5
    is to be used. The molar latent heat of benzene and toluene may be taken and 30 MJ/K mol. The feed is liquid at 295K and has
    a boiling point of 370.4 K. Design a suitable fractionating column and compute the following:
    a) The number of theoretical plates and position of feed plate.
    b) The quantity of steam at 240 kN/m2 required in the reboiler
    c) The column height for a plate spacing of 450 mm.
    d) The column diameter if it operates at atmospheric pressure and vapour velocity of 60 cm/s. (or)
    e) The permissible velocity of the vapour related to the total cross-sectional area of the column in m/sec is given by Brown
    Souders equation:
    𝝆𝑳 −𝝆𝑽
    Vapour velocity (m/s) = 𝑲𝑽 𝝆𝑽
    𝑲𝑽 = constant = 0.0428
    𝝆𝑳 𝒂𝒏𝒅 𝝆𝑽 are the densities of the liquid and vapour respectively in kg/m3
    Data:
    Feed mean molecular weight = 86.4 Kg/Kmol
    Molecular weight of benzene = 78 Kg/Kmol
    Molecular weight of toluene = 92 Kg/Kmol
    Vapour flow in the stripping section = 2.48
    Kmol/ mole of feed Kmol
    Boiling point of benzene= 353.3K
    Boiling point of toluene = 383.6K
    Specific heat of feed = 1.84 kJ/Kg K
    Tray spacing = 450 mm
    Tray efficiency = 50%

    Equilibrium data for benzene-toluene system:


    x 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00
    y 0.22 0.38 0.51 0.63 0.70 0.78 0.85 0.90 0.96 1.00

    Where
    x= Mole fraction benzene in liquid
    y= Mole fraction benzene in vapour.

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