4 replies to this topic

[yclee99]

what is liquid heat enthalpy, heat of vaporization, vapor heat enthalpy for acrolein (or acrolyne)...
besides, anyone know the market price for acrolein?

I try to seach on internet, I can't get it.

[mbeychok]

yclee99:

Acrolein is C₃H₄O, the CAS Number = 56.06 and it is also known as Propenal or Acrylic Aldehyde.

[yclee99]

i managed to get the equilibrium data from Roult's Law.
Now trying to draw H vs x,y graph. but got problem. Anyone know how to get saturated liquid enthalpy and saturated vapor enthalpy for binary system? (acrolein n water)

[MrShorty]

As noted in the other post, Acrolein/water is nonideal enough to split into two liquid phases. Raoult's law (aka ideal) is going to do a very poor job of accurately representing the VLE (and won't predict LLE at all) of this system. What resources do you have access to (Dechema has a couple of pages worth of data, I can't take the time to enter all of that for you)? University library? Interlibrary loan? Simulator package? Journal database search engines? others??
What kind of project are you working on? If this is an excercise in "how to do," then estimating using Raoult's law might be good enough, because you can practice all of this. But, if this project is supposed to have be a reflection of reality or have any application to reality, you're going to need to do better than Raoult's law.
I don't know how accurate UNIFAC would be at calculating activity coefficients for this system, but it would likely be better than Raoult's law.

[yclee99]

This is group assignment for 3 year chemical engineering (combined mass transfer operations, and process plant engineering). It takes 30% of my mass transfer operations and 25% of my process plant engineering. The project required to construct a distillation column to purified acrolein from 90% to 95%. Basically, I just learn Roault's Law in mass transfer operation. So, I think is good enough if I use this law to get my equilibrium data. Actually, really or more accurate data if preferable but since the library in uni don't have these data (the library is very very very small). By the way, I get the vapor pressure from equation ... is like below
ln P = a+b/(T+c)+...... and the coefficient I get it from Hysys 3.1(software).
I also get the formular and coefficient (H = a+bT+cT^2+....) from Hysys for acrolein and water separately. But I don't know how to use these H to get my saturated liquid enthalpy and saturated vapor entalpy.
My group have decide use Ponchon graphical method to get number of stages in distallation column.

Scope of work:
1. Design distillation column using either packs or trays
2. Reboiler and condenser duties and operating costs
3. Column and piping pressure drops, pump design and costs
4. Estimates of equipments costing for column and internals, including trays or packing, pumps and piping design, and heat exchange equipment
5. Preparation of specification sheets for all the units
6. Selection of materials of construction for all the units
7. Operating costs for three reflux ratios, including heating and cooling costs, pumping compressor and vaacuum pump energy, if appropriate
8. Estimation of optimum reflux ratio