advertisement

your_name

Problem SM.3 Questions date

**1.**

**You must compare the normal boiling points and composition of all chemical components leaving the decanter in the aqueous stream. What are the normal boiling points (nbp) for all of those chemical components? What are their mole fractions? List the components and their nbp in order of increasing boiling point in the first two columns of the table below, using the data found in the “Flowsheet Thermodynamic Data” section of Chapter 1 in this HYSYS manual. Then, list the mole fractions of the same chemical components in the third column of the table. **

**Chemical **

**Component **

**T nbp**

**, **

**C at 1 atm **

**Mole Fractions in **

**Stream S15 for Reactor **

R1 Inlet of ________°C hydrogen methanol water toluene ethylbenzene styrene monomer

**2.**

**In the table above, where you entered in the first three columns the chemical components, their normal boiling points, and their mole fractions leaving the decanter aqueous stream, you are to complete the fourth and fifth columns. What is the feed type of each chemical component, i.e. state whether each component is a LK, HK, non-LK, or non-HK? What is the qualitative distribution of each component by stating which stream or streams ( i.e., distillate and/or bottoms ) the chemical component appears in, and in what relative amount, such as all, most or little? **

**Remember that the column is being designed to separate methanol from water.**

**Chemical **

**Component **

**T nbp**

**, **

**C at 1 atm **

Feed Type Distribution hydrogen methanol water toluene ethylbenzene styrene monomer

**3.**

**A detailed description of a simple distillation column is given Appendix L of this HYSYS manual. What are the three main parts of a distillation column? **

The __________, the equilibrium __________, and the ___________ are the three main parts of a distillation column.

Page 1 of 3

your_name

Problem SM.3 Questions date

**The overall mathematical model for a column consists of a series of smaller math models, one for each of these column parts. In what order are the overall mathematical model equations solved in the column algorithm? **

The mathematical model equations are solved __________________ in the mathematical algorithm presented in Appendix L; that is, iterate all unknowns in _______ equations.

**How does the column mathematical algorithm in Appendix L differ from the HYSYS simulation algorithm? Why? **

The column mathematical algorithm in Appendix L shows that you must specify the pressure of each stage in addition to the other given variables. The HYSYS simulation algorithm needs only the __________ and __________ pressures, not the pressure of every stage, because HYSYS estimates the stage pressures automatically from the

___________ and ___________ pressures.

**4.**

*How might the value for the vent ratio be estimated? flow rate sum of all non-condensables in the feed vent ratio*

total flow rate of the feed

*_______ 16 vent ratio*

_______ 16

A value ten times greater like 1×10 -6 should be used for the vent ratio of the condenser vapor stream, because this value is less likely to constrain the iterative process that converges the material and energy balances of the distillation column. A stricter vent ratio like 1×10 -7 will lead to an iteration error of “two liquid phases were found on the condenser stage.” Using

1×10 -6 eliminates this error.

**What are the feed, vent, distillate, and bottoms flow rates in kg/h? What are the mole fractions of the LK in the distillate and the HK in the bottoms? **

LK – methanol

HK – water

**Reactor R1 Inlet of ________°C **

Feed S16 , kg/h

Vent S17v , kg/h

Distillate S17 , kg/h

Bottoms S18, kg/h z

D,LK

, mol. frac. z

B,HK

, mol. frac.

Page 2 of 3

your_name

Problem SM.3 Questions date

**What are the composition profiles of just the LK and HK in the distillation column? **

**Use the Performance/Plots page to print these profiles. Note that methanol is the light key and water is the heavy key in this problem.**

Below is the composition profile of methanol and water for a reactor inlet temperature of

________°C.

Use Snipping Tool to copy and paste graph here.

Page 3 of 3