Ammonia refrigeration

[ali2u]

Hi,

I have a qestion regarding the ammonia refrigeration section. specifically ammonia refrigeration compressor vs the capacity of ammonia condser.We are using cooling water in the ammonia condenser. However, we are experiencing much heavier load on ammonia compressor in the summers compared with winter. What is the reason is it something to do with the lower degree of cooling in ammonia conderser in summer?
What about synthesis loop pressure , what doues high/vs low pressure influence the ammonia refrigeration section.

I am looking forward to a interesting discussion.

Thanx,

 

[Montemayor]

ali2u:

You are right. This could be the beginning of a very interesting thread. However, you've got to give some basic data in order to stimulate some logical and meaningful comments. You have yet to tell us what your "ammonia refrigeration section" is and what are its characteristic design, it's performance and it's shortcomings (if any).

You ask: "What about synthesis loop pressure?" I would ask: What about it? You haven't told us anything about what it is, how it operates, or what is troubling it (if anything). We need basic data! We haven't received any data from you and we can't discuss anything intelligently like engineers until we get the facts - all the facts!



Art Montemayor
Spring, TX

 

[25362]

As your question is general, so will be this comment.
A refrigerating compressor discharges against system pressure, which in this case is determined by the (equlibrium) condensing temperature. So, in summer time warmer cooling water would result in a higher discharge pressure for the same load.

As for synthesis pressure in a typical Haber-Bosch process, taken as a single operating variable, it is known that an increase in pressure increases the equilibrium percent of ammonia and the rate of the reaction. As to what effect would that have on the compressor's performance it is for you to analyse considering recycling and purging.

 

[quark]

25362 is right on. The power drawn by a refrigerating compressor is equal to the mass flow rate times the enthalpy difference at superheated suction condition and discharge conditions(and reciprocal of efficiency). If the discharge pressure is high, the compressor draws more power.

If you have an air cooled condenser, the difference in power consumption will be substantial. If water cooled, then it depends upon your cooling tower design, its controls and ambient wet bult temperature.

What do you mean by a synthesis loop?

If you want the discussion to be interesting, then you should provide us some details as suggested by Mr Montemayor

Regards,


Eng-Tips.com : Solving your problems before you get them.

 

[smckennz]

Hi Ali2U
you have told us that your heat rejection system performance is dependent on the season.
Have you applied Carnots equation and basic heat transfer theory to your performance variation? It is not uncommon for refrigeration performance to decrease when it is warm.

Cheers

Steve2U