a) Use Clapeyron's equation to plot the phase diagram of the solvent (liquid-gas and solid-liquid line). Find the triple point, the vapour pressure at 35 °C, and the boiling point at 1.5 bar. Compare your results with values from Aspen. b) Air heated to 90 °C is used for the process. Find the wet bulb temperature 78 at the entrance of the gas stream. Find the adiabatic saturation temperature Te (the final temperature of the gas stream in a very long dryer). How much does the wet bulb temperature change? c) The solid (Fw=1100 kg-dry solid/h) must be dried from initial Wo = 0.15 kg- solvent/kg-dry solid to Wsp < 0.005. Find the minimum residence time 7min needed to achieve the specifications under a great excess of air. Find the minimum gas flow Gy,min needed to achieve the specifications in an infinitely large dryer. d) Assume that you operate at Gy = 1.23×Gy,min. Find the respective 7 from the design equation for constant rate of evaporation. Add to this +20%, to account for the falling rate stage of drying and heat losses. Calculate the capital cost and operating cost per year. Parameters: use NIST, DETHERM or Aspen to find any thermodynamic parameters you may need for the solvent; use the Lewis numbers from Table 1. For the gas, Cp = Cp,Y= 20 J-mol¹.K-¹. Use Am = 0.12 m²/kg-dry solid for the exposed wet area and h = 11 W/m²K for the heat transfer coefficient. The cost of the dryer is proportional to the residence time r. 1 h corresponds to £420,000. The cost of the 90 °C-hot air is £2/ton. Missing units of a number means problem not solved.

Introduction to Chemical Engineering Thermodynamics

8th Edition

ISBN:9781259696527

Author:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart

Publisher:J.M. Smith Termodinamica en ingenieria quimica, Hendrick C Van Ness, Michael Abbott, Mark Swihart

Chapter1: Introduction

Section: Chapter Questions

Problem 1.1P

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Question

acetone with these parameters: po:=101325; #Standard atmospheric pressure in Pa
Tfo:=273.15-94.45; #Melting temperature in K
Tvo:=273.15+56.15; #Boiling temperature in K
Hv:=31270; #Enthalpy of vaporization in J/mol
R:=8.314; #Gas Constant in J/mol*K
NLe:=1.76; #Lewis number for acetone
Mw:= 0.05808 ; #kg/mol molecular weight of acetone
W0:= 0.15;
Wsp:=0.005;
Am:= 0.12; #m^2/kg dry solid for the exposed wet area
h:= 11; #W/m^2K for heat transfer coefficient
tau__min:= Hv*(W0-Wsp)/Mw/Am/h/(T8-TS);
tau__min/60;