The best way to liquefy Ammonia

[pranj5]

Suppose, there is an amount of Ammonia vapour at atmospheric pressure and very very close to the boiling point say at -33°C. I want to know what's the best way to liquefy the Ammonia in terms of economy and energy. I know that it can be liquefied with cold fluids like liquid Nitrogen etc., but what's the most economic way?

 

[strive]

Pressurization.
You increase the gass pressure, at which point gas temperature also rizes - and hence keeps NH3 in gaseous state.
You let the gass cool down and when the pressure/temperature ratio falls to the right ratio the NH3 liquefies.

 

[pranj5]

I can understand, but how to maintain the temperature at such low level.

 

[strive]

You said you already have NH3 at -33°C, i presumed you meant at some high altitude (or polar region) which means you just need to keep the gass there.

If you are in STP conditions, you would need a well made vacuum flask for insulation, and you can keep it cool by circulating liquefied gas at -33°C inside it. To cool that cooling gass/liquid you use expansion.

An alternative would be to use a peltier module but i think efficiency would be lower (i'm not sure though) than with the above method.

 

[pranj5]

The Ammonia is at -33°C doesn't mean that the surrounding temperature is like this. This simply means that the Ammonia to be liquefied is at -33°C i.e. very close to its boiling point at atmospheric pressure. Question is what's the best and energy efficient way to liquefy the Ammonia. Kindly clarify what do you mean by using expansion. Can you suggest some kind of machinery that can do the job?

 

[strive]

Check Linde's Process and Claude's Process. You will find patents and blueprints/schematics for both on google.

Expansion - when you increase the volume of a gas while keeping its mass the same its temperature decreases. Return the process for increassing the temperature.
Most modern refridgeration and air conditioning systems work in this manner.

 

[pranj5]

Thanks! But I need machinery and information about what kind of manufacturers can make such machinery.

 

[strive]

Ok, for the processes read this: http://www.sciencedirect.com/science/article/pii/S1876610216000539

For manufacturers/price you are looking for 'industrial refridgeration units'. This page is the first i found: http://www.ashirwadco2.com/industrial-refrigeration-unit.html

 

[russ_watters]

Ammonia is used as the refrigerant in low temperature chillers. Just google for that.