EXERCISES Section 2.1 2.1. Minimum work of separation. A refinery stream is separated at 1,500 kPa into two products under the conditions shown below. Using the data given, compute e minimum work of separation, Wmins in kJ/h for To 298.15 K. kmol/h Component Feed Product 1 Ethane Propane n-butane n-pentane n-hexane 30 200 370 350 50 30 192 4 0 Product 1 Vapor 25,040 Feed Product 2 Phase condition Temperature, K Enthalpy, kJ/kmol Entropy, kJ/kmol-K Liquid 364 19,480 Liquid 394 25,640 36.64 33.13 54.84

2 A triple-acting evaporator with direct current power must concentrate 15000 kg/h of an aqueous solution entering 25 C from 10% to 40% by weight. For the heating is available live steam at 2.2 at, and on the third effect a vacuum is maintained that allows the solution to boil at 30ºC. The dissolution does not present an appreciable increase in the point of boiling and its specific heat is equal to the unit for all concentrations. The integral heat transmission coefficients for effects I, II, III, in Kcal/m2*h*ºC, they are worth 2800, 2500 and 1600. Apply to each effect: a) Hourly consumption of heating steam b) Boiling temperature c) The heating surface.

Tomato pulp (40% solids content) is heated by flowing it into a steam injection heater at a rate of 500 kg / hour. 85% quality steam under 180 kPa is supplied to the heater at a rate of 40 kg / hour. If it is assumed that the heat exchanger efficiency is 85% and the initial slurry specific heat is 3.2 kJ / (kg K), the slurry specific heat during the heating process corresponds to the function Cp = Cpw (water fraction) + Cps (solids fraction). a. Determine the temperature of the product leaving the heater when the initial temperature is 35 ° C. =....° C. b. Determine the total solids fraction of the product after heating. = ...%