Should all ammonia tanks be fitted with sprinkler systems. What flow rates should I use, or where can I find on the web design guides for ammonia sprinklers?
By "ammonia sprinklers" I think you mean that you would be introducing the liquid NH3 into the tank through spray nozzles located in the internal vapor space. I believe the intent here is to produce some cooling effect through expansion of the liquid NH3 across the nozzles.
Although I have never used this method (nor seen it used), I have had a lot of liquid NH3 storage and transfer operations experience. I believe the spray system is used in the U.K. and some parts of Europe. All I've ever used is simple liquid injection through a pipe and refrigerated the tanks with a separate recompressor & condenser. I do know that you need not have an NH3 spray system to make the liquid transfer system work and work well. I am interested in knowing the justification for putting in such a system and the merits it can add to the operation. If it can refrigerate the tank contents (bring the vapor pressure down) without the need for a recompressor, it would be a great help. Maybe some Forum members can add their experience on this subject.
Like Art, I've heard references to such a system, though never seen or heard of one installed. We had two "Horton Spheres" that held anhydrous NH3 that used Vapor Recompression and Auto Refrigeration. These spheres were supplemented with high pressure bullets. Liquid HH3 from the compressors was piped both ways. All of the inlet nozzles were in the liquid. Due to cracking and potential cracking in the spheres, this storage system was replaced with a Cryogenic NH3 storage system. There was talk of installing such as spray system at as part of discussions on ways and means to prevent roll-overs of the contents. Whether is was installed I don’t know, but will try to find out.
I think Olmedo is referring to a water system around the ammonia tank. If the tank were to leak anhydrous ammonia into the atmosphere, it could be harmful, if not deadly. I would first check ANSI K61.1 for flowrates.
I think Craig Tiras has pointed it out more correctly. If it is about water sprinkler system around an ammonia storage tanks, I would also like to know more about whether similar can be applied to handling ammonia gas in cylinders. Should the gas leak from the top, is there a sprinkler system byw which one can completely ensure that the leaking gas is absorbed only by water sprinkler and does not escape to the atmosphere?
We have three 18,000 tons of refrigerated ammonia storage tanks. The small water spray system is installed on top of the vent valves.
We also have two warm ammonia storage tanks with 100ton capacity. These tanks are installed with water spray system.
<Built horizontal with dished ends>
DIA: 144", Length: 50ft
Design: 275psig, @124'F(19.4kg/cm2, 51'C)
Rated Press': 200psig (14.08kg/cm2)
The warm ammonia tank are like surge drum.
The water flow for the sprinker is some 400GPM for one tank.
During the hot summer, we often water-spray the tank to control the internal pressure.
You may also want to look at the Handbook of Compressed Gases prepared by the Compressed Gas Association, Inc. (otherwise known as CGA). If you don't have a copy, you may want to consider obtaining one. I've found this to be a good overall reference to add to your personal library.
Anyway, the handbook has a section discussing Ammonia (anhydrous) and the Safe Storage, Handling and Use. In that section they reference the ANSI K61.1 mentioned in a previous post and also CGA G-2.
Looking at the CGA website, it appears that CGA G-2.1 may have replaced or incorporated the ANSI K61.1. You can obtain a copy from them over the internet.
I don't know what you can find in CGA G-2.1 but the referenced handbook also has a section Handling Leaks and Emergencies where they mention using water applied through spray or fog nozzles to reduce ammonia vapor in air but do not give a rate of application.
They do discuss what is considered sufficient water to put on liquid ammonia spills (100 parts water to 1 part ammonia) and also indicate liquid ammonia can be disposed of by discharging liquid ammonia into a vessel containing 10 parts water to 1 part ammonia.
The handbook does warn about applying water to a leaking ammonia vessel that may be colder than the water since the warmer water may tend to heat the ammonia and aggravate the leak.
For further information, the handbook references the Emergency Services Guide for Selected Hazardous Materials, published by the U.S. Department of Transportation or the Emergency Response Guide from Transport Canada.
