DOI : 10.17577/IJERTV2IS3236
- Open Access
- Total Downloads : 545
- Authors : Amit M. Patil , Dr. R.S Bindu
- Paper ID : IJERTV2IS3236
- Volume & Issue : Volume 02, Issue 03 (March 2013)
- Published (First Online): 11-03-2013
- ISSN (Online) : 2278-0181
- Publisher Name : IJERT
- License:
This work is licensed under a Creative Commons Attribution 4.0 International License
Determination of Effect Angular Poisoning of Legs on the Structural Stability of Pressure Vessel by Using Non-linear Finite Element Analysis (FEA)
Amit M. Patil Dr. R.S Bindu
Mechanical Engg. Department Mechanical Engg. Department
D.Y Patil College of Engineering D.Y Patil College of Engineering
Abstract
The objective of the pressure vessel is to have production of phenol and acetone. Cumene process is an industrial process of producing phenol (C6H5-
OH) and acetone (CH3-CO-CH3) from benzene (C6H6) and propene (C3H6). The term stems from isopropyl benzene or cumene (C6H5-CH (CH3)2), the intermediate material during the process. With the
help of this process two relatively cheap materials, benzene and propene are converted into two more valuable products such as phenol and acetone. For this process other required reactants are oxygen from air and small amounts of a free radical initiator. Most of the worldwide production of phenol and acetone are now based on this method.
The pressure vessel is being designed to implement the cumene process. The process is extremely sensitive to pressure and temperature conditions and requires a lot of control systems to monitor it. These control systems are to be placed below the vessel for effective monitoring. The current range of Pressure Vessels in the market of AZ series come either in skirt support or supported by 8 legs equidistance from each other. However, a custom made pressure vessel has been ordered for the cumene process. The custom made vessel has to have a lot of controls for the cumene process; hence 8 legs are not feasible. Six legs support with a non- symmetric distribution was tried out initially. However the current requirement is to have more floor space.
-
Introduction
Type of support used depends on the orientation and pressure of the pressure vessel. Support from the pressure vessel must be capable of withstanding heavy loads from the pressure vessel, wind loads and seismic loads. Pressure on pressure vessel design is not a consideration in designing support. Temperature can be a consideration in designing the support from the
standpoint of material selection for the different thermal expansion.
-
Need of Work
It is observed that although a lot of work has been done in the field of pressure vessel. The current range of Pressure Vessels in the market of AZ series come either in skirt support or supported by 8 legs equidistance from each other. Six legs support with a non- symmetric distribution was tried out initially. However the current requirement is to have more floor space.
It is decided to improvise on the design and introduce angular supports. It has an advantage of increased floor space to mount the controls.
-
Objective of Work
Typically most of the pressure vessel are either skirt or leg supported and observation is that legs are primarily vertical. However in case vertical expansion of the vessel either due to thermal expansion or due to vertical loading the legs are susceptible to buckling.
Hence, objective of this work is to determine whether creating an angle in the legs in combination with unsymmetrical distribution affects the structural stability of the system.
Figure 1 Vertical drum on inclined leg support
-
Methodology
-
Material Selection
According to ASME code for manufacturing of pressure vessel number of materials are specified but the selection depends purely upon nature of application. In accordance with number of material selection factors and rules and regulation led down by ASME code specifications material need to be decided. Since this work primarily focus on the analysis of vertical leg supports. Finally end user will decide which material to be used. The material used for this vessel is structural steel and its properties are listed below.
Table 1
Sr .
No.
Material
Structural Steel
1
Youngs Modulus (Mpa)
2e5
2
Density Kg/ m3
7850
3
Poissons Ratio
0.3
4
Yield Strength (Mpa)
250
5
Tensile Strength (Mpa)
460
.
-
Geometry Modelling
The vessel geometry modelling has been done in Ansys
12.01 workbench itself.
-
Mesh Generation
Meshing has been done by using the method of Tetrahedron. In Tetrahedron method the component is been divided into small triangle on its surface which gives no of nodes and elements of that component. The meshing has been done by changing the mesh size of the various component of the pressure vesssel. Due to change in the density of the meshing, it results in the variation of the no of nodes and elements of the meshed parts.
The result of this mesh density change affects the value of the stress and deformation of the component. For fine meshing that is for small mesh size the values of no of nodes and elements are high but as the element size is gradually increased it result in increase in the value of no of nodes and elements. For small variation in mesh size that is of 1E-03 m the values are showing small variation in no of nodes and elements and also it shows the same amount of variation in the values of stress and deformation for the given mesh size. But for large variation in mesh size the values of no of nodes and elements are also vary in large amount.
-
Boundary Condition
In case of FEA analysis on has to make sure that the boundary condition applied for particular analysis must be correct or it may cause misleading results.
The nature of analysis will decide the boundary conditions need to be applied. As in this work the leg supports are more important from analysis point of view and sine pressure vessel is vertically standing on ground the following boundary conditions were applied.
1 .Wind load acting on the vessel
-
Internal pressure of the vessel
-
All the supports need to be fixed to the ground
-
-
Structural Analysis
The Ansys 12.01 workbench will give the results in terms of the maximum deformation as well as the stress subjected by the pressure vessel assembly.
Here, in this work there will be small increment in the angular positioning of legs by 1 degree upto 30 degree. This increment will result in the considerable amount of deformation as well as stress in the leg supports. The tabular results for stress and deformation for 1 to 30 degree are as shown in Table 2. The nature of this analysis is based upon Section VIII Division 1 for the targeted compliance of the stress values in the pressure vessel assembly.
Figure 2 3D Model
Figure 2 Meshing
Figure 4 Total Deformation
Figure 3 Boundary Condition
Figure 5Von Mises Stress
Table 2 Stress and deformation values for no. of angles
60 Angle Vs Von Mises Stress
Von mises Stress (Mpa)
Von mises Stress (Mpa)
50
50
48.757
Angle
Von Mises Stress (Mpa)
Total Deforma tion(mm
)
No. of Nodes
No.of Element s
1
25.702
0.125
99795
48693
2
28.709
0.158
99635
48700
3
29.127
0.140
95532
46172
4
33.312
0.178
99909
48907
5
39.280
0.147
99514
48584
6
40.827
0.144
100505
49023
7
44.336
0.149
99807
48784
8
48.757
0.151
100373
48982
9
48.188
0.155
99928
48816
10
47.196
0.158
101329
49619
11
52.103
0.165
100512
49345
12
54.729
0.172
101560
49783
13
58.183
0.166
100882
49291
14
65.696
0.118
102215
50113
15
49.538
0.196
101291
49571
16
49.282
0.202
101728
49712
17
54.798
0.210
101942
49847
18
49.087
0.217
101902
49750
19
63.028
0.224
102404
50078
20
59.741
0.230
103396
50628
21
70.871
0.237
102390
50134
22
74.037
0.243
103947
51031
23
80.392
0.250
103571
50714
24
82.293
0.257
103721
50681
25
84.569
0.264
104716
51251
26
88.839
0.271
104830
51303
27
92.682
0.278
105381
51571
28
10.95
0.285
105956
51724
29
105.38
0.293
107247
52557
30
107.74
0.301
107039
52327
Angle
Von Mises Stress (Mpa)
Total Deforma tion(mm
)
No. of Nodes
No.of Element s
1
25.702
0.125
99795
48693
2
28.709
0.158
99635
48700
3
29.127
0.140
95532
46172
4
33.312
0.178
99909
48907
5
39.280
0.147
99514
48584
6
40.827
0.144
100505
49023
7
44.336
0.149
99807
48784
8
48.757
0.151
100373
48982
9
48.188
0.155
99928
48816
10
47.196
0.158
101329
49619
11
52.103
0.165
100512
49345
12
54.729
0.172
101560
49783
13
58.183
0.166
100882
49291
14
65.696
0.118
102215
50113
15
49.538
0.196
101291
49571
16
49.282
0.202
101728
49712
17
54.798
0.210
101942
49847
18
49.087
0.217
101902
49750
19
63.028
0.224
102404
50078
20
59.741
0.230
103396
50628
21
70.871
0.237
102390
50134
22
74.037
0.243
103947
51031
23
80.392
0.250
103571
50714
24
82.293
0.257
103721
50681
25
84.569
0.264
104716
51251
26
88.839
0.271
104830
51303
27
92.682
0.278
105381
51571
28
10.95
0.285
105956
51724
29
105.38
0.293
107247
52557
30
107.74
0.301
107039
52327
44.336
40.827
49.188
47.196
40 33.312
29.
28.709 127
30
20 25.702
10
0
39.28
0 5 10 15
Angle
0.148
0.148
0.158
0.155
0.158
0.155
0.147 0.149
0.151
0.144
0.147 0.149
0.151
0.144
Total Deformation (mm)
Total Deformation (mm)
Figure 6 Angle Vs Von Mises Stress
Angle Vs Total Deformation
0.200
0.158
Angle Vs Total Deformation
0.200
0.158
0.150
0.140
0.150
0.140
0.100 0.125
0.050
0.000
0
0.100 0.125
0.050
0.000
0
5
5
Angle 10
Angle 10
15
15
Figure 7 Angle Vs Total Deformation
.
-
-
-
Conclusion
The table 2 shows the various values of stress and deformation irrespective of the change in the angle. We have plotted 2 graphs as shown in Figure 6 Angle Vs Von Mises Stress and Figure7Angle Vs Total Deformation for a instance both graph are plotted up to first 10 results.
The first graph will lead the information that with corresponding increase in the angle the value of the stress in the vessel is also having gradual increase.
Similarly, for corresponding change in the angle deformation is also increasing. On the other hand if we se e that Table 2 will show that at 30 degree the Von Mises Stress around the leg support is 107.74 Mpa and which is maximum but less than the yield strength and tensile strength resulting into safe design.
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References
-
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Troy Alvin Smith, Analysis of axisymmetric shell structures under axisymmetric loading by the exibility method, Journal of Sound and Vibration, Vol. 318, pp. 428-460, 2008.
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E. Gutman, J. Haddad, R. Bergman, Stability of thin walled high-pressure vessels subjected to uniform corrosion, International Journal of Pressure Vessels and Piping, Vol. 38, pp. 43-52, 2000.
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Prof. R. M. Tayade, Mr. Vinay Patil, Imran M. Jamadar,
Structural Analysis of Inclined Pressure vessel Using FEM, International Journal of Engineering Research &Technology (IJERT), ISSN: 2278-0181, 2012.
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L. P. Zick, Stresses in large horizontal cylindrical vessels pressure vessels on two saddle supports, The welding journal research supplement, pp.959-970, 1951.
International Journal of Engineering Research & Technology (IJERT)
ISSN: 2278-0181
Vol. 2 Issue 3, March – 2013
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