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Sulfuric Acid Production / Partial Pressure Of H2So4

sulfuric acid partial pressure double contact final absorption tower

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#1 Jon K

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Posted 22 September 2023 - 07:17 AM

Guys,

 

 

I'm struggling with SO3/H2SO4 Emissions in the offgas of a sulfuric acid production plant (double contact, 98.5%, sulfur burning).

 

What kind of emissions will I find in the offgas? Certainly acid mist (depending on efficiency of the mist eliminators located at the last absorption tower). Acid mist means extremely fine LIQUID particles, right? In addition there should be gaseous H2S04, right? And I believe that mist eliminators does not filter gaseous H2SO4, right?

 

 

According to Perry's handbook the partial pressure of H2SO4 over aqueous sulfuric acid (98.5%) is approx. 6.5E-6 (T=80°C, p =1 bar)

Is it correct to calculate the mole fraction of H2SO4 in the gas phase by using y_H2SO4  = p_H2SO4/p? Or is this incorrect because sulfuric acid solution is strongly non-ideal?

 

 

Assuming the above mentioned calculation of the amount of gaseous H2SO4 is correct. This should be a physical limit for lowest emissions? Or am I making a mistake in my thinking here?

 

 

Btw.: If anyone knows where to find more accurate data, please let me know.

 

 

Thanks a lot!

Jon

 



#2 breizh

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Posted 23 September 2023 - 06:12 AM

Hi,

https://www.dedietri...-acid-treatment

 

Breizh



#3 shvet1

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Posted 25 September 2023 - 12:02 AM

Actually it is not clear what you are looking for - you are dealing with overcooled gas you are trying to implement gas law to overcooled liquid, correct?

 

Emission of H2SO4 as gas depends on absorber efficiency. Acid mist fractional composition depends on process and eliminator type. A rule of thumb is mist<250 µm and spray >250 µm.

 

Emissions of H2SO4 as mist depends on mist eliminator efficiency. Eliminator does not affect the gaseous portion of the gas.

 

You should start with

https://www.amazon.c...g/dp/0080444288

and particularly chap. 9

http://www.sulphuric...he-Web/home.htm


Edited by shvet1, 25 September 2023 - 02:11 AM.


#4 Jon K

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Posted 25 September 2023 - 04:34 PM

Thanks for the answers so far. I know this book (blue cover).

My main question is how much gaseous H2S04 can be expected in the gas leaving the absorption tower.
Mist due to (shock) cooling is another thing. Well described in several books. But no one talks about the gaseous emissions. So probably I get it wrong...

#5 shvet1

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Posted 25 September 2023 - 11:28 PM

Blue cover?

 

I am not familiar with wet scrubbing of H2SO4. Is there H2SO4g upstream of scrubber? Or SO3?



#6 Jon K

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Posted 26 September 2023 - 02:18 AM

That's basically what I asked myself.

So the gas entering the absorption tower consists of >90 vol % Nitrogen, 6 % oxygen, little amount of s03 und traces of so2.

The circulating liquid entering the tower consist of >98 wt% H2S04 and <2% Water.

The water instantly reacts more or less completely with the so3 to form new H2So4.

My question is: Having good contact between liquid and gas can I assume gas saturation with H2SO4(g). I would say yes.
But what would we the amount/concentration?


With blue cover I meant the book of king and davenport. Saw this with a blue cover

#7 breizh

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Posted 29 September 2023 - 06:35 AM

Hi,

Consider this document to support your work

Breizh






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