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Topic: Determine the amount of HCl that should be vent to scrubber  (Read 3456 times)

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Offline Pingue2008

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Determine the amount of HCl that should be vent to scrubber
« on: August 11, 2012, 03:29:36 PM »
Hi all,
I just register with forum and having trouble posting a question could someone help? i navigate all the site and could find where to post and that explains why i am using this platform. i hope you don't mind me asking my question here.
I am working on environmental permit. the problem is to determine the amount of HCl that should be vent to scrubber. actually a 4%wt HCl solution is fed to a tank at 130F and the question is to know how much HCl should vent to the scrubber. the actual flow to the tank is 210mol/hr HCl solution.
What i did: I collected the partial pressure of HCl over aqueous solution of HCl from perry's handbook. to get the mole fraction of HCl in the vapor phase, i divided the partial pressure par the total pressure then i multiply the mole fraction by the 210 mol/hr to have the amount of HCl in the vapor. the problem is that i am not at peace with the number. please can someone help see below for my calculations
P    12.43   psig
A=   11.64   
B=   4471   
Temp   130   F
   327.6   K
HCl Partial P   0.009823333   mmHg
Total P   642.8   mmHg
Hcl mol frac in the vapor phase   0.0000153   
      
Total moles   210   mol
Hcl mol     0.003209169   mol
HCl MW   36.46094   g/mol
lb HCl in vapor phase   0.117009313   lb

{MOD Edit - split off topic, create new title}
« Last Edit: August 16, 2012, 09:08:24 PM by Arkcon »

Offline curiouscat

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Re: Determine the amount of HCl that should be vent to scrubber
« Reply #1 on: August 24, 2012, 08:53:06 AM »
1. You need to convert psig to psia

2. Flow rate of Liq ≠ Flow rate of vapor

I suspect your vapor loss here is mostly via diffusion; not flow. What fraction of the tank is full?
« Last Edit: August 24, 2012, 09:09:41 AM by curiouscat »

Offline awolokay

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Re: Determine the amount of HCl that should be vent to scrubber
« Reply #2 on: August 31, 2012, 03:38:56 PM »
I think all of your working is correct, except possibly right at the end.

You talk of a total of 210 mol of vapour. I would expect this to be gram-mols. If this is the case, then your answer of 0.117009313 is grams NOT lb!

If your 210 is lb-mol, then 0.117009313 is lb and is correct.

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