- Lat Tray 4 Temperature On The Distillation Column Figure 2 Is Controlled By A Current P Controller With 50 Proportion 1 (323.7 KiB) Viewed 41 times
LAT Tray 4 temperature on the distillation column (Figure 2) is controlled by a current P-controller with 50% proportional band. Temperature controller output (COT) adjusts the sctpoint of a steam flow controller with 100% proportional band. Column base level is controlled by a current proportional controller setting bottoms product withdrawal rate. Transmitter ranges are: Base level Bottoms flow 1-30 ft 0-30 gal/min 0-300 kg/h Steam flow Temperature (tray 4) 65-140°C Normal operating conditions are: Steam flow 195 kg/h Bottoms flow 23 gal/min 67% full Base level Tray 4 temperature 103°C The pressure drop over the control valve on the bottoms product is a constant 25 psi. The control valve co-efficient is 14.3. The formula for steam flow through a control valve (when the upstream pressure Ps in psia is greater than twice the downstream pressure) is W = 3P,f(x); where W = steam flowrate (kg/h); Cv = 3.8; f(x) = valve fraction 30 2 IT TO 51 Column CO 120 PM. FI FT Bottoms Figure 2. The bottom section of the Lehigh distillation column (0) Calculate the control signals from the PMT, PMF. PML, bottoms flow transmitter, COT, COF and COL. (22) What is the instantaneous effect of a -10°C step change in tray 4 temperature on the signals (new PMT and new CO,)? (6) D=${[15]}] LT ih p M