What are the barrier to run a process at 600bar 1700C 2

[ManTicora]

I was simulating an acqueous reaction (Na2SO4+H2O<=>2NaOH+SO2)
and got a maximum rate at 600bar 1700C.
What are potential physical (not economical) limitations that could prevent the design/development of such a process.
The final product has to be cooled down to 200C.
Thank you all for your suggestions and contributions.

 

[LittleInch]

Melting point of steel ? ( 1350C) springs immediately to mind. So you're into blast furnace type linings / kilns etc, but how you transport it and then cool it / de-pressurize it becomes a real big issue. Generally kiln type linings are not pressure containing.

600 bar is also very high, even at relatively normal pressures.

Definelty bespoke items.

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[jari001]

You need a catalyst ASAP. Keeping people and instruments safe from this reactor will also be a bit of a challenge if you need to work on it during() or just after a run. You'll perhaps need vacuum protection with this kind of potential dT because of flashing followed by cooling after depressurization, but you can probably avoid this by cleverly cooling.

Also, if there was ever a reason to do heat capture, you have it.

 

[ManTicora]

@ LittleInch (Petroleum)
...but how you transport...?
The molten material could be transported using a refractory line pipe

http://www.sunnysteel.com/ceramic-lined-pipe.php#.V7XRj_krKJA

The steel shell of the lined pipe will be exposed to about 500C. It should be able to handle 600bars without issue.

@ jari001 (Chemical)
How to find a catalyst to use?

Still unclear on how to cool and depressurize the final product...

 

[Compositepro]

Doesn't the reaction go the other way at lower temperature and pressure? In that case the separation would need to be before cooling and depressuring. An electrolytic method seems more realistic.

 

[jari001]

If you don't have some development colleagues to turn to, a literature search can't be helped, and even then I would think some small scale trial experiments would be necessary to develop the process parameters. My guess is that some common iron salt catalysts might work.

Can you consider options like Compositepro mentioned? This seems to be a very difficult way to make some caustic.

 

[LittleInch]

Are you sure - the link says up to 800C for the pipe.

Getting heat in and out would seem to be quite difficult also.



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[moltenmetal]

No chemical process would EVER be carried out at 600 bar and 1700 C. That goes double for something as mundane as decomposing sodium sulphate and water back into sodium hydroxide and SO2...

You can have high pressure simultaneous with high temperature ONLY if the source of the high temperature is internal to the process. But even in that case, such extremes of simultaneous P and T are only done when they are absolutely necessary. Generally, very hot processes aren't also done at high pressure, and very high pressure processes are done at much more modest temperatures.

Refractory lined pipe relies on separating the heat from the pressure retaining boundary by means of the refractory insulation. The pipe remains cold to resist the pressure. But there are always losses across the insulation, and the pipe itself must dissipate all that heat leakage to avoid getting hot itself.

 

[jari001]

Just curious, are you being tasked to develop this process or are you doing this as a sort of exercise? Those parameters are bananas, particularly the pressure for me.

 

[ManTicora]

Alternatevely run the process at high temperatures (1700C) at mild pressures (5 bars) and quench the product mixture, below NaOH boiling point (1350C), to prevent NaOH for recombining with SO2.
jari001 (Chemical) you are right but I know more expensive process than this one to make caustic.

 

[georgeverghese]

Do the correlations you have for the activity coeff for each of these reactants and products, from which you would have obtained the thermodynamic reaction K value, extend up to 600bar , 1700degC ? Or some sort of extrapolation has been assumed? At 1700degC, would presume there would be many other side reactions also - the simulator probably cannot tell you what these other products might be. Small quantities of contaminants in the reactants may also trigger other reactions.

 

[moltenmetal]

I agree with george that this is likely an artifact of the simulator running beyond the limits of its thermo.