Question

Chemical reactors sometimes use batch processes to heat chemical compounds in a transient heating operation. Assume that a chemical compound of density p = 1400 kg/m and specific heat c = 2500 J/kg/K is in a batch reactor of volume of V = 3.5 m in an insulated vessel. The chemical is to be heated from cold storage temperature of T; = 260 K, to a process temperature of T = 420 K by passing saturated steam at Th = 500 K through a coiled, thin-walled, 22-mm-diameter tube in the vessel. Steam condensation within the tube maintains an interior convection coefficient of h; = 8 kW/m/K, while the highly agitated liquid in the stirred vessel maintains an outside convection coefficient of h = 2 kW/m/K. If the chemical compound is to be heated in 30 min, what is the required length of the submerged tubing?

Answer 1

Given that,

Chemical compound density,$\rho$ = 1400 kg/m³

Specific heat, C = 2500 J/kg/K

Volume, v = 3.5 m³

Cold storage temperature, T_i = 260 K

T = 420 K

T_h = 500 K

Interior convection coefficient, h_f = 8 kW/m²/K

Outside convection coefficient, h_g = 2 kW/m²/K

Time, t =30min

Answert steam condensation. Sook H501 Book Chemical heating mass of chemical SXV - 100 X3.5 - M900kg Energy required to heat chemical focom sook to hook cm CAT 4900 x23500 x 500 -420) =4900 X 2500 x 80 Time requires - 980,000,000 J. Go minutes of time Power- 980,000,000 - 60x60 = 980,000,000 369-26 87222.2 3 watts

The wall en pering of the tube transferred yousm steam to tube : q tansferred from steam to tube q goransfered from tube to chomical. Assurne, the conductivity of the tube neglected AT on steam the outside 500 - Tway Thall - 2060 112 8(500 - Twall) = 2 (Twal - 2.60) 4000 - swall = 2 Tual - 5200 I Stuall=3480 Twall = 348k Met heat resistance between steam and Chomico dedition. YnA гр. — Convection in chamical connection in

- - + 22 23 (soo - 26c)XA. —- - 25 +22 23 - 20 ХА - 2 12 2 2 - 3 3х40 А — = 24222.. 3 2+22 2.3*5 2ңo Хg А з 10.87 | 27.0 Т. 2 = 11 ну 103 1 - о. 89 2у. L - 10.99 глу lіx 163 . . . 10 690 8 - (ISO kono+L. = 10 2.6 = 1025-6