Excel for Chemical Engineers I 16 I Material balance (5/5) [Reactive systems with recycle 2]
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- เผยแพร่เมื่อ 8 ก.พ. 2025
- This video shows how to use Microsoft Excel to do material balance calculations for reactive systems with recycle streams using the tearing technique. The idea of the tearing technique was discussed in the previous video.
There is a wrong calculation done in minute 4:24 on calculating the rate of reaction, it was calculated based on stream 1 while it should be calculated from stream 2. The right calculations are available in this file:
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![Excel for Chemical Engineers I 17 I Energy balance (1/5) [Introduction]](http://i.ytimg.com/vi/6-THVm-46n4/mqdefault.jpg)
![Excel for Chemical Engineers I 17 I Energy balance (1/5) [Introduction]](/img/tr.png)
![Excel for Chemical Engineers I 14 I Material balance (3/5) [Reactive systems]](http://i.ytimg.com/vi/5CKKhrou1-o/mqdefault.jpg)
Dear Sir, I do very appreciate the way you present the topic. Not all of the lectures are so clear. Thanks!
Thanks for the great videos, they were a wonderful refresher!
Great video sir
Awesome work!
Is it the same method if you have two recycle streams?
Hi sir! Thanks for the tutorial. It helps me a lot. I want to ask what if we get negative value for one of the molar flowrate after calculaing using solver? How to solve this since it doesn't make sense to me. Thanks.
Hi Syahir,
I'm glad the video help you!
The molar flow rates should always be greater than or equal zero. Getting a negative value can be due to :
- A wrong value, so check the givens well and make sure your write them correctly in the spreadsheet. It is pretty common to be a unit conversion error.
- An error in the balance equations, just one wrong sign or bracket is enough to mess up all the calculations. So check the balance equations and make sure there are no errors in them.
- If all the numbers and equations are right, then this could mean that the stream is flipped. Which means that the stream is going the other way. In this case change the stream direction and accordingly the equations and see if the problem is resolved.
- If you still have negative stream flow rates values then this is most probably an issue with the problem givens.
Hope this helps!
If you are having trouble with your solver giving negative values (which may be mathematically correct, but not physically correct of course), you can always add constraints to the solver, specifying that the values it is iterating must be greater than 0.
In this exercise, Mr. Mohammed does nothing that is not known. Mr. Mohammed uses the concepts of Professor Reklaitis (1985), but remains in them. What little he adds them is the solution of the exercises using excel. No more. And excel it is not necessary to solve these exercises Balance. Furthermore, many of the concepts of Reklaitis are obsolete. The iterative method is unnecessary. I have a better way to resolve any problem material balance without using Excel or global balances. The exact answers to this problem are: N2 = 1592.170131; N3 = 983.688261; N4 = 325.421451, 657.966811 = N5, N6 = 65.796681;
N7 = 592.170131, r1 = 304.240934.
+BEN-HUR VALENCIA VALENCIA Thanks for your comment!
I did not claim that I am doing something new, if you watch the series from the beginning you will know that I am interested in introducing Excel as a tool for solving various chemical engineering problems using the known methods (like Professor Reklaitis method in this video). Please let me know if I said something different.
Definitely this is not the only method for solving such type of systems, but it works. I will be glad to know more about your method.
And your better way is.......?