Chapter 4, Problem 4.22P

A liquid mixture containing ethanol (55.0 wt%) and the balance water enters a separation process unit at a rate of 90.5 kg/s. A technician draws samples of the two product streams leaving the separator and analyzes them with a gas chromatograph, obtaining values of 86.2 wt% ethanol (Product Stream 1) and 10.9% ethanol (Product Stream 2). The technician then reads a manometer attached to an orifice meter mounted in the pipe carrying Product Stream 1, converts the reading to a volumetric flow rate using a calibration curve, and converts that result to a mass flow rate using the average density of ethanol and water. The result is 54.0 kg/s. Finally, the technician calculates the mass flow rate of the second product stream using a material balance and reports the calculated product stream flow rates and compositions to you. You examine them, do some calculations, and reject them.

1. Draw and label a flow chart of the separation process.

Carry out the calculations that led you to reject the submitted results and explain how you knew the values were wrong.

List up to five possible reasons for the incorrect results. For each one, briefly state how you might determine whether it was in fact a cause of error and what you might do to correct it if it was.