CL-304 (PED-II) Instructor: Prof. Ashok Kumar Dasmahapatra Group 8 PROCESS EQUIPMENT DESIGN TERM PROJECT Process & Mechanical Design of a Packed Bed Extractor Group Members: Namrata Das (130107034) Nayan Gupta (130107035) Nilesh Raj (130107036) Niraj Chetry (130107037)
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CL-304 (PED-II) Instructor: Prof. Ashok Kumar DasmahapatraGroup 8
PROCESS EQUIPMENT DESIGNTERM PROJECT
Process & Mechanical Design of a Packed Bed Extractor
Group Members:Namrata Das (130107034)Nayan Gupta (130107035) Nilesh Raj (130107036)Niraj Chetry (130107037)
Problem Statement:
Extraction of Benzene is desired from a mixture of Benzene & 1-Hexene containing 78 mole% 1-Hexene and 22 mole% Benzene.
Flow rate of the feed solution is 6000 kg/hr.
Tetra-methylene Sulphone is to be used as the solvent for 96% extraction of benzene from the feed mixture.
12. Column Height:o Using the above two values of HtoC & NtoC , we get the column height: H = HtoC * NtoC
13. Comparison of Packing Materials:o We repeat the steps 1-11 for each of the packing material type and tabulate the results to compare all 3 types of material choice:
It is evident from the calculated results that “Lessing Rings” would be the optimum choice as a packing material for the desired extraction
Solution Procedure: Process calculations
Mechanical Design: Specifications
Diameter of the tower, Di =1mHeight of the tower, H = 2.9mWorking Pressure = 1atm =10.1325 kg/cm2= 0.101325 MPa Design Pressure, P = 1.13atm = 11.4497 kg/cm2= 0.114497 MPaShell Material: Plain Carbon Steel, Grade 2B (IS : 2002-1962)Permissible Tensile Stress, ft = 950 kg/cm2 ~ 95 MPaInsulation thickness = 100mmDensity of insulation = 770 kg/m3
Top disengaging space= 1mBottom separator space= 1mDensity of material of column = 7700 kg/m3
Wind Pressure = 130 kg/m2 ~ 1.275MPa
Mechanical Design: Calculations
1. Shell Thickness: o Using the formula: ts = PDi/(2fJ+P) + c , we get the shell thickness
2. Head Design:o Working Pressure Range: 0.1~1.5 MPa Choice of Head: Shallow dished & Torispherical We calculate the thickness of head by: t= PDoC/2fJ
3. Stress calculations: o Stress in the mechanical design due to various contributors are calculated: Axial Stress (compressive): fap= PD/4(ts-c) Compressive stress due to weight of shell upto a distance ‘x’ : fds=ρsgx Compressive stress due to weight of insulation: fd(ins)= ᴨDinstinsρins / ᴨDmt Compressive stress due to weight of liquid and tray: fdl= Wliq/ ᴨDm(ts-c) Stress due to weight of attachments: fd(att)= Wa/ᴨDmt Total compressive dead weight stress at height ‘x’: fdb= fap+fds+fd(ins)+fdl
Stress due to wind load at distance ‘x’: fws= 1.4Pwx2/ ᴨDot Stress in upwind side: fmax=fws+fap-fds
Stress in downwind side: fmax=fws+fap+fds
Calculating the failure location ‘x’ verifies the earlier calculated value of “Column Height”
Mechanical Design: Specifications
4. Internal Packing Support:o For column diameter upto 1.2m, we can use the GIS/EMS Random Packing Support
Grid in such small columns
(Ref: Internals for packed column, SULZER Chemtech)
5. Distributor:o For low interfacial tension value in LLX, Extraction Distributor VRX can be used.
(Ref: Internals for packed column, SULZER Chemtech)
Results: Design Details
The design specifications based on the optimum choice of packing material are listed below:
Graph:
Bibliography:
Mass Transfer Operations, 3e, Robert E. Treybal Mass Transfer Operations, A. Suryananarayana Mass Transfer Operations, B.K.Dutta Packed Tower Design & Applications, Ralph F. Strigle Perry’s Handbook, 8th Edition, Section-15, Mc Graw Hill Education Packed Column Design & Performance, L.Klemas & J.A.Bonilla Structured Packings: for Distillation, Absorption & Reactive Distillation, by SULZER Chemtech Ltd. Liquid-Liquid Extraction Technology, by SULZER Chemtech Ltd. Design Practice for Packed Liquid-Liquid Extraction Column, by SULZER
Chemtech Ltd. Internals for Packed Columns, by SULZER Chemtech Ltd.