Triple Effect Evaporator - DOC

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					                             Triple Effect Evaporator Simulation

CHEN 4130                                                            Senior Lab
Fall 2007

MEMORANDUM for: Process Engineering Teams, CHEN 4130

From: The Instructors, CHEN 4130

The triple effect evaporator uses a saturated steam input to heat solutions to boiling. As
the solvent is boiled off, the solution becomes more concentrated in each successive
evaporator, and the boiling point elevation caused by the increase in solute
concentration can become an important issue. Evaluate the flow rate needed to
achieve a product composition of 15% (wt.) for the following feed stocks: 8% (wt.)
sucrose / 92% (wt.) H2O and 8% (wt.)/ 92%(wt.) Na2OH.

      1. Using AspenPlus or HYSYS, simulate the sucrose experiment using to
         specify the heat duty and pressure of each effect for the range of
         feed rates specified below. Note the heat duty and pressure of each

In reporting your investigations, please address the following items, including any
additional points based upon your study of the problem:

      Compare the boiling point elevation when operating with sucrose and
     sodium hydroxide. Compare the results of your simulations with information
     from the literature. Discuss the operating conditions (Ti, Pi, qfeed, qcool,)
     needed to run the process with each solution.
      Simulate the operation with two effects at the same flow rate obtained in
     Part 1 above for both the aqueous sugar and sodium hydroxide feeds?
      Can it be operated in a countercurrent flow configuration?
      Can the unit be operated under vacuum? Would a vacuum configuration
     be helpful in reaching the target composition for any of the feeds?

Aspen Plus and HYSYS Notes
AspenPlus is available on the computers in the Borgmann Lab. HYSYS is available on
the the computers in the Borgmann and ITLL-HP Labs.

View the AspenPlus and HYSYS tutorials, which can be found on the web at:

Use the University of Colorado Plus System to create your student accounts in the
Magellan computing center. *HYSYS will be available on the computers in the
Borgmann and ITLL-HP lab, but it is unable to model electrolytes. Consult with the
instructor before attempting to use HYSYS. (HYSYS hint: each effect can be modeled
using an appropriate combination of a cooler and a separator.)
Operational Guidelines:

   Use a steam pressure of 30 psig. Do not exceed steam pressures of 40 psig.
   Use a feed flow rate from 0.2 to 0.4 gpm to achieve the targeted product for the
    sugar solution.
   Other data that may be useful for the sugar solution:
     Patm = ~13 psia
     T1 = ~122.1˚C
     Water Density: 998.23 kg/m3 at 20˚C


       Felder, R.M. and Rousseau, R.W., Elementary Principles of Chemical Processes,
        Wiley (1986).