Over the years I have been told time and time again that there are two absolutes in ammonia refrigeration. #1 – we do not have “temporary operational conditions” so we have no need for “temporary operating procedures” and #2 – there is no “process chemistry” in ammonia refrigeration. But it dawned on me this week that I had beaten the “temp operating procedures” to death over the past 20 years but a friend pointed out that he was unable to find anything about “process chemistry” requirements in ammonia refrigeration, as such we had discussed for years. So here it goes.
First things first, what does PSM/RMP require in terms of process chemistry…
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1910.119(d)(2) Information pertaining to the technology of the process. 1910.119(d)(2)(i)(B) Process chemistry; |
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(c) Information pertaining to the technology of the process. (1) Information concerning the technology of the process shall include at least the following: (i) A block flow diagram or simplified process flow diagram; (ii) Process chemistry; |
So where does the chemistry come into play in an ammonia refrigeration process?
When the ammonia refrigeration process has a “diffuser tank” tied into their pressure relief system(s), the “scrubbing” of the ammonia gas in the water is “process chemistry”.
NH3 + H2O = NH4OH (Ammonium Hydroxide)
And that is the basic chemistry that is happening inside our ammonia refrigeration process that is equipped with a “diffuser tank”.