Distillation Essay -- essays papers

Distillation Abstract This report outlines the steps taken to separate a 50:50 by volume ethanol and isopropanol side stream. The resulting separation must contain no more than 3% alcohol impurity in each product. A laboratory column, run at total reflux, was utilized to scale up to a forty foot high by one foot diameter column. The laboratory column allowed the team to determine vapor velocities and HETP values for the 0.24 inch Pro-Pakq packing. HETP is defined as the height of packing divided by the number of theoretical column stages. The column consisted of four main sections: packing, controls, a reboiler, and a condenser. To complete the vapor velocity vs. HETP relationship, the vapor velocity must be found. The vapor velocity was found using a system energy balance. The design vapor velocity was determined to be 4.85 ft/hr. However, this vapor velocity did not result in the column flooding; therefore the scaled-up column is not designed to its full potential. Ideally, distillation columns should be designed at 70-80% of the flooding velocity. The column HETP was found by use of the Fenske equation and was determined to be an average of 4.55 inches. As a result of the design parameters from the experimental column, the following design is proposed: the column will run at a vapor velocity of 4.85 ft/hr and will have a HETP of 4.30 inches. This will result in a packing height of 38.7 feet. The reboiler will have an area of 113.52 ft2 and the area of the condenser will have a value of 45.54 ft2 in which heat exchange will take place. Introduction A chemical plant spends approximately 50 to 90% of capital investment on separation equipment (1,1) Therefore, the ability to utilize a small laboratory column and to scale-up a column is an important skill for a chemical engineer. This report will outline the steps taken to design a packed distillation column. The column needs to separate a 50:50 mixture of ethanol and isopropanol into a distillate stream containing no more than 3 wt% isopropanol and a bottoms stream containing no more than 3 wt% ethanol. The design of the full-scale column was based on a laboratory simulation column. This column allowed the team to determine vapor velocities and HETP values for the 0.24 inch Pro-Pakq packing. Once the simulation vapor velocities are determined, they can ... .../hr)/*(1/0.0154 kmol/L)*(1/(p(.25)2ft2)*(0.0159 kmol/L) (p(1)2(ft)) = 6.857567 kmol/hr MWAVG,D = 46.493 kg/kmol VD = (6.857567 kmol/hr) * (46.493 kg/kmol) VD = 318.82886 kg/hr *Equation of Top Operating Line y = (L/V)x + (1-(L/V))xD = (RACT / RACT +1)x + (1/ RACT +1)(0.97) = 0.912779x + 0.084605 *Distillate Rate R = (V-D)/D = 10.4651 318.82886 (kg/hr) - D = 10.4651D D = 27.808642 (kg/hr) R = L/D = 10.4651 * 27.808642 (kg/hr) = L L = 291.02022 (kg/hr) *Bottoms Flow Rate L/V = R (z -xB) + q (xD - xB) R(z -xB) + q(xD-xB) -(xD-z) z= Feed mole fraction of ethanol q= 1 (feed assumes to be liquid) L/V = 10.4651(0.567-0.03) + 1(0.97-0.03) 10.4651(0.567-0.03) + 1(0.97-0.03) -(0.97-0.567) L/V = 1.05 L/V = (VB + 1)/ VB = 1.05 VB = 20 B = V/ VB = (318.82886 kg/hr)/20 = 15.941443 (kg/hr) *Feed Flow Rate F = D + B = 15.941443 (kg/hr) + 318.82886 (kg/hr) = 334.7703 kg/hr *Bottom Operating Line y = (L/V)x - ((L/V)-1) xB = 1.05x - 0.0015 * Condenser Heat Duty QCOND = V * DHVAP DHVAP = xETOH * DHVAP,ETOH + xISOP * DHVAP,ISOP QCOND =