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Friday, April 22, 2022

Do you even Lith, Bro?

 "It is silly to try to escape other people's faults.  They are inescapable.  Just try to escape your own." - Marcus Aurelius

 I couldn't resist the opportunity for a pun.  Unfortunately it's a bit of an inside joke.

But first, the power plant pic of the day:  Escalante Generating Station near Thoreau, New Mexico.  I always loved the scenic backdrop with the stratified sandstone cliffs behind it.

Fun fact:  After I drove past this coal-fired station in 1995 while on vacation, it weighed on my mind for over a decade.  At one point I applied for a control room operator position, and flew there for an interview.  I was offered a position with a very generous salary.  Unfortunately, the local community lived in poverty, and the entire region did not have good schools.  I really would have enjoyed that job, had I accepted the offer.  I'm certain of that.

On to the post... 

There is an old meme "Do you even lift, bro?".  I'm not sure if it's a put-down in gym-rat culture, or just a silly internet meme.  The title of this post is a play on that.


 On the submarine, we had a cranky Air Conditioning unit called a Lithium Bromide absorption chiller - The "Lith-Bro".  Theoretically this thing should have been a bad-ass and very silent water chiller.  It used low-pressure aux steam to cool off chill water that ran throughout the ship for HVAC cooling.  

Makes sense, right?  Add steam and things get colder!  Yes it actually works that way.  It's daunting to attempt to explain something that I barely understand myself, so rather than butcher anyone's potential for understanding the process, I'll just put up a .gif of the process and direct you to a link.  Image courtesy of the linked website.


What *should* have been a nice, silent, trouble free water chiller was anything but.  We ran R-114 refrigeration units most of the time, and although they were noisy, they were quite reliable and trouble-free.

The captain or engineer would occasionally insist that the Machinist's Mates run the Lith-Bro, for proficiency, or training, or for whatever reason.  It would have been more effective as a boat anchor than as a water chiller, and below are the reasons:

The Lithium Bromide chiller required really high vacuum to work, and it was quite difficult to obtain the vacuum needed after a long lay-up period.  Lithium Bromide is pretty corrosive, and the pump seals would always leak once the machine was started.  It was almost inevitable that repairs would be needed right at the start.  The stuff made you itch after coming in contact with it.  It always leaked a bit, and we always had to keep it clean.  The brown stains never scrubbed off the paint after the solution had come into contact with it.

The lith-bro was always on the verge of "rocking up", meaning that the strong lithium bromide solution was about to solidify.  At that point it would become impossible to pump, and refrigeration would stop happening.  Thereafter, a long process of steaming it would dilute the hardened solution to the point where heat transfer could resume.  

Lastly, when the lith-bro got running, it liked to be left alone with a steady steam supply and a consistent quantity of water to chill.  Bear in mind that the lith-bro was installed on a warship that constantly ran training drills, and had upsets of all sorts, including loss of electrical power to the pumps.  Why that thing was ever installed on a submarine, I have no idea.


2 comments:

Anonymous said...

We rocked it up a lot also. The strange thing is that it works better in high inlet temp water than low temp inlet. It is truly the devil machine of the secondary plant. Yeah, even worse than the evaporator.

We also experimented with running both R-114s with the Bromide. Yes, it's not allowed on a 637. But we tried it. Very warm water (sort of a different area for a secop). Didn't work. Was still better with the bromide and one 114.

Mark said...

Thanks for the comment! I'm amazed you could get it to hold vacuum. Ours also seemed to line out a bit better with an R-114 in parallel with it - I'd forgotten the fine details until you mentioned that.