93% to 50% Sulfuric Acid Dilution: Heat Balance Question

[Subystud]

Hello -

I am looking to design / sub-out a skid for diluting 93% H2SO4 to 50%. I have some questions regarding the heat balance.

1. From the enthalpy-concentration diagram, I obtained a value of -64 BTU/lb to do the dilution at the listed conditions.
Is this all the heat that needs to be accounted for?? Or, is this simply the delta_Enthalpy for 50% acid from 230F to 120F? Do I also need to consider the heat capacity of the sulfuric acid and the energy associated with lowering the temperature of the hot, diluted mixture from 230F to 120F?

2. Integral Heats of Mixing. These are listed as ratios of solute:acid in molar form at 25C. The energy that outputs from this equation is the energy that must be removed to get the final mixture at 25C. Is this correct?

I am having some difficulty on when to use what...

Thanks,

Rob

 

[Latexman]

1. The heat of mixing is what raised the temperature of the two combined streams (i.e. the resulting 50% stream) to 230F. -64 BTU/lb is needed to cool the resulting 50% stream from 230F to 120F. That's all. No need to consider anything else in this part of the problem, however this does NOT address the recycle steam shown.

2. Yes. It's the heat that must be removed (or added) to remain isothermal (constant temperature).

Good luck,
Latexman

Technically, the glass is always full - 1/2 air and 1/2 water.

 

[Latexman]

Recycle stream. Sorry.

Good luck,
Latexman

Technically, the glass is always full - 1/2 air and 1/2 water.

 

[moltenmetal]

Diluting 93% sulphuric acid to 50% is a nightmare waiting to happen. Not only is the heat of dilution a big issue, but it will also eat any metallic material you intend to use in contact with it. If, as in the other thread, you are using this for water treatment, use the acid undiluted, and add less.

 

[racookpe1978]

It will help you to inject the concentrated acid in aas many small streams as possible, NOT in one larger pipe but 4, 6, or 8 small ones widely separated from each other.

 

[all015]

The 50% Sulfuric Acid will corrode through the SS HX very fast. moltenmetal is 100% correct in his/her suggestion