Question

[20] Question 3 Crude oil is to be heated from 22 °C to 58 °C by heat exchange with the bottom product froma distillation column. The bottom product, flowing at 30 kg/s, is to be cooled from an initial temperature of 145 °C to 105 °C. The following shell and tube heat exchanger is available: 600 mm ID (1 shell pass) Shell inside diameter Tube configuration 2 passes 19.05 mm Tube outside diameter 2.1 mm Tube wall thickness 1.25 x OD square tube pitch Tube arrangement 324 Number of tubes 3.66 m Tube length Baffle Spacing 250 mm 25% Baffle cut Thermal Conductivity, kw 45 W/m2. C The properties of the two streams are Tube side Shell side (Crude Oil) (Bottoms Product) 825 870 Density (kg/m) 1 985 2 200 Heat capacity (/kg K) 0.0029 0.0052 Viscosity (N s/m2) Thermal conductivity (Wim-K) 0.119 0.136 Fouling resistance (K-m2W) 0.0003 0.0006 Allowable pressure drop (kPa) 70 50 Determine whether the heat exchanger will be suitable by calculating the following: 3.1. The heat duty and mass flowrate of the arude oil. (2) 3.2. The mean temperature difference. (5) 3.3. The total available area of the heat exchanger and the overall heat transfer coefficient. (3) 3.4. The tube side velocity (4) 3.5. The tube side heat transfer coefficient. (5) 3.6. The shell side velocity. (3) 3.7. The shell side heat transfer coefficient. (5) 3.8. The required area of heat exchanger. 3.9. The tube side and shell side pressure drop. (5) (6) 3.10.Based on these calculations, state whether the heat exchanger will be suitable for the service or not (2) 140] TOTAL MARKS: 75

Answer 1

145C TI &autian 22c 3.1. Meat duty T2.105C CmpaT) battomproduct (m (p AT) Crude oil 30 k 2 200 (145-10)k X 2.64000J/A 2640kTs Cudeail Cp AT cude ail 2640000 1385x(58-22) m vude = 3 3-2 1shell bass & 2 ube þasses Regex LMTD COxrection exchanger lot en actor 8-22 6.29 T,-t 145-22 F O.97 T-T2 t,-ti 145-10S l1 1 = S8-22 oa AT T--) LMTD or couter T2-t 84.98 - FAT Txue LMTD =0.97 x 84 g& Tue LHTD= 8 2.43 Pa 1

FAT 3.3 UA brener,A Tatel area for heat .tubes x2TC L 324 K 2 K TCX19.05SK1O 3.66 A Gutex area d tubes no. 2 70.9子m2 A - 2640000 Q U A (FATM 70. 97x 82.43 U=4 S 3.4 Tube did velouby chude a elodity 入 A elocity) tubea CrOSs-sectim tule mo. X A tube crossctiom Cude oil 3 6.34 2 324 x 25 X TC x (13.05- 10.38 m/ Pa. 2