The specification for a sieve plate column is given below. Make a preliminary me

Question

The specification for a sieve plate column is given below. Make a preliminary mechanical design for the column. Your design should include: Column wall thickness Selection and sizing of vessel heads Type of support The maximum possible external pressure that this column could withstand without collapsing You need not design the plates or plate supports. You should consider the following design loads: Internal pressure Wind loading Dead weight of vessel and contents (vessel full of water) There will be no significant loading from piping and external equipment. Earthquake loading need not be considered Length of cylindrical section 37 m Internal diameter 1.5 m Heads, standard ellipsoidal 50 sieve plates Two 0.6 m diameter access ports (manholes) situated 1.0 m above the bottom and 1.5 m below the top of the column Access ladder with platforms Insulation, mineral wool, 50 mm thick Materials of construction: Vessel: stainless steel (304) Skirt: killed carbon steel Operating pressure 2000 kN/m^2 Maximum operating temperature 200 degree C Corrosion allowance 2 mm degree C

Explanation / Answer

Di Internal Dia meter 1.5 m 1500 mm Do Outer diameter, to be determined C Corssosion Allowance 2 mm L Length of the vessel 37 m Thickness 't' is computed based on t= pd/(2fJ) +C p Internal pressure 2000 kPa 2 Mpa f Allowable Working stress for Stainless Steel, taken from reference books. 304 has with 10% Cold work has Yield strength of 480 MPa and UTS of 680 Mpa. However we have to consider the working temperature as 200oC. Allowable stress at that temperature is about 86 MPa 86 MPa j Joint efficiency = 100% considered 1 C Corssosion Allowance 2 mm. Given d Internal dia of vessel 1500 mm. Given t Now Calculate t 19.44186047 Choose t 20 mm Hoop Stress due to internal pressure 75 Mpa Now Compute dead loads Internal volume of Vessel Volume of Cylindrical portion = /4d2L 65.3843971 m3 Volume of Sphereical ends = /6d3 1.767145868 m3 Internal volume of Vessel= Cyl + Sph portion 67.15154297 m3 Dead weigth due to water 67151 Kgf 671 kN Self weight of the Vessel = surface area *thickness x Density 7.85t/m3 28.48403519 tons 284 kN Axial load due to inetrnal pressure = d2/4* internal pressure 3534.291735 kN Total axial load = Dead load + self weight + Internal pressure 4489.291735 kN Longitudinal stress due to dead load= Load/Area, here area dt= 94250 mm2. 48 Mpa Now Compute Wind Loads taking wind speed of 100km/h C1 Loads Due to Wind Pressure : First estimate wind pressure pw = 1/2 CdV2A is approximated by pw =0.05V2 N/mm2 In this case height of vessel is small. Hence we take wind pressure uniform along the height of the column. wind velocity 100km/h 27.77777778 m/s pw 38.58024691 N/m2 Load due to wind pressure : Pw*Projected area = pw*(37 x 1.5) 2.141203704 kN Load due to wind pressure is low and hence neglected. Thus the final thickness of the Vessel 20 mm

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