liquid Anhydrous Ammonia (15barg) expand to gas (1 bar)
liquid Anhydrous Ammonia (15barg) expand to gas (1 bar)
(OP)
Hi, we are introducing anhydrous ammonia at 15 bar gauge into a tank at 1 bara and 85 degrees Celcius. We meed to keep the temparatue at 85 and on expansion the anhydrous goes to -37 degrees. What is the safest method of introduction?





RE: liquid Anhydrous Ammonia (15barg) expand to gas (1 bar)
Or just do nothing, as the pressure in the tank increases, the temperature will increase to.
It all depends on what you want to do.
RE: liquid Anhydrous Ammonia (15barg) expand to gas (1 bar)
100°F is a nominal 200 psig. your 15 barg must be about 100°F so i would not heat the liquid until you really review the properties of ammonia at 85°C (about 185°F!) the vapor pressure of ammonia at 185°F (your 85°C) is 669 psi.
heating the liquid will only change what percent of the liquid will flash to a vapor. it will not change that most of it will still enter as a liquid.
you need to better define what you are doing:
what is in the tank when you add the ammonia?
is there a liquid in the tank or vapor?
is there ammonia vapors or is there just an inert such as nitrogen? this will impact the potential temperature of the liquid in the tank. if there is only nitrogen, then the tank will actually have a partial pressure of 0 psia ammonia and could cool below your proposed -37
what is the metallurgy of the tank?
can it withstand rapid localized cooling if the liquid is going to fall to the bottom of an empty tank?
RE: liquid Anhydrous Ammonia (15barg) expand to gas (1 bar)
I've been looking at trying an ammonia vaporiser but the ones available are for small scale use (for farmers) and the project doesn't want large amounts of cash spent(if one needs to be specially built).
We are keeping the temperature of the tank using heating coils and low pressure steam, therefore I can't allow the temperature of the anhydrous to drop the temperature inside the tank by too much.
It is also quite a problem to find a valve that can take both a liquid and a gas at high pressure even though we using a 2 inch line to convey the anhydrous ammonia
RE: liquid Anhydrous Ammonia (15barg) expand to gas (1 bar)
Good luck,
Latexman
RE: liquid Anhydrous Ammonia (15barg) expand to gas (1 bar)
Do you know of where I can get some information about anhydrous vaporization. I only seem to be finding small units used on farms, there are none that can deal with our flow of 5500 kg/h.
RE: liquid Anhydrous Ammonia (15barg) expand to gas (1 bar)
Even if max range ends with 4400kgs/hr, you can ask them for individual approach or consider use of two vaporisers working paralelly.
RE: liquid Anhydrous Ammonia (15barg) expand to gas (1 bar)
I gound that site before and have their info...I do however live in South Africa and this company is a US Company and I haven't been able to find any agents this side of the world.
RE: liquid Anhydrous Ammonia (15barg) expand to gas (1 bar)
I can suppose that some contact / materials / representatives shall be available still, try to find it locally.
RE: liquid Anhydrous Ammonia (15barg) expand to gas (1 bar)
i would not worry about looking specifically for an ammonia vaporizer. you really just need a "vaporizer" in general.
i have seen ammonia vaporized in the tubes with steam on the shell side (not ideal and i would not recommend) and also using waste heat from cooling water. the cooling water was in the tube side and ammonia in the shell of a kettle style reboiler.
have to be careful to maintain minimum pressure on the ammonia side if no water flowing or subject to freeze-ups.
the design of the vaporizer is going to be just as dependent on the rest of your deliver system and the sophistication of your controls.
since you need to only maintain enough pressure on the system to deliver into a 1 bara vessel, i would be most surprised that you cannot utilize some type of waste heat or even ambient sidearm heaters to keep pressure in the tank.
what are your normal ambient temperatures there?
RE: liquid Anhydrous Ammonia (15barg) expand to gas (1 bar)
RE: liquid Anhydrous Ammonia (15barg) expand to gas (1 bar)
if you have steam available, I can supose that you have some power plant in nearby. How about use of "waste" heat, i.e. hot cooling water after the condenser?
RE: liquid Anhydrous Ammonia (15barg) expand to gas (1 bar)
32barg steam would be overkill!
Good luck,
Latexman
RE: liquid Anhydrous Ammonia (15barg) expand to gas (1 bar)