[chand31]

Hey guys I would be grateful if you could help me with the following question (attached file). I was able to work backwards and determine the flow rates up to the F₄. However, from there the numbers don't seem to balance. And I made the assumption that there is 5% of water lost with the 95% pulp in the screen.

Thanks a lot for the help.

[Dan]

Please show what you did, it will help us help you and it's a forum rule.

[chand31]

Oh okay. Sorry I'm new here. Didn't know about the rules.
I've uploaded my working out. It's at the end that there is a problem. The masses (or flow rates) do  not seem to balance for the ''screen''. I fail to see why.

The last line in the working out should read ''500.1 is NOT EQUAL to 791.825''

[DrCMS]

Just having a quick look over it the errors I see are:

Steam F9 you've assumed is 100% sugar but it does not state that anywhere in the question that is the case but it does tell you to clearly state the assumptions you have used to solve the question.

Stream F7 is 35 mol% sugar but you have used 35% by weight.

Stream F4 is 15 mol% sugar but you have used 15% by weight.

[chand31]

Well I assumed that the end-product was pure.

Also I forgot to mention that it was said to assumed 15%mol to be 15% by weight for this question.

[Woopy]

I'll attempt the question tomorrow and let you know what I come up with, we must be taking a similar course because I'm learning mass balances too for multi unit processes.

[Woopy]

Ok so I attempted the problems using mass percents, and you will run into a problem where you have more sugar leaving F4 than entering from F3 if you assume mass percents, therefore you absolutely have to assume mole percents for the streams that the problem indicates you have to do it for.

[curiouscat]

I think the problem is wrong.

The balance across that mill itself doesn't seem to work out in a consistent fashion.