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Seal Leg For H2 Safety Tank


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#1 Guest_MDHernandez_*

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Posted 25 May 2010 - 09:19 AM

I am in the process of designing a small 6.5 ft safety tank to be used for a H2 line. The tank is to have an overflow for water to an open drain and I have been trying to determine how tall the seal leg (water will overflow but the purpose of the seal leg is to keep the H2 from escaping the system) from the overflow should be. I've been searching the internet for any type of information leading to answering this question. Some rules of thumb indicate pressure of the system as a basis for height but I do not fully comprehend the reasoning behind this. Does any body have any idea on how or where to find any articles that might help me design this seal leg? Thank you all

#2 Art Montemayor

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Posted 25 May 2010 - 12:48 PM


Monica:

I am concerned that you don’t have experience in the fluid mechanics (& statics) involved in this application. You really should have a complete command of the hydraulics involved in “designing” a seal tank - particularly one for hydrogen service.

I’ve done a lot of these designs – especially on low pressure hydrogen generation and utilization pipe work or transport systems. The basic concept is very simple and involves only a basic knowledge of hydraulics – but that knowledge must be thorough. I will guide you through what I believe you should apply, but I will have to generate sketches or drawings to show you the basic principles of how such a “seal” tank is supposed to work.

I don’t understand what you mean by the terms “a small 6.5 ft safety tank” – I believe I can make an accurate guess at what you mean, but I need for you to confirm that. Refer to my follow-up post tomorrow that will have an attached Excel workbook for an explanation and feel free to make comments, ask questions, and voice any concerns. Do this with call-outs or text boxes – but make sure you question anything you don’t understand.

Right now I’m on my way out the door to a wine-tasting contest here in Madrid, Spain and I probably won’t get home until late. There is no rest for serious and dedicated wine tasters – especially in this country. I have spent the last year searching through Spain for the perfect wine bottle – and I haven’t found it yet, although I’ve come close to the goal. Like Don Quixote, my quest goes on and I won’t give up until I find the perfect bottle.


#3 Guest_MDHernandez_*

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Posted 25 May 2010 - 01:26 PM

Dear Art,

For some time now I've come to the conclusion that Engineering out in the industry has fallen in a pseudo state, just like all the other fields. I've tried to be careful with the systems that I've been asked to work on since very few people (i.e. seniors) seem to be able to explain the reasons behind certain rules of thumb but I don't feel comfortable "following" certain guidelines without being sure they come from a reliable source. With my involvement on hazard studies I've developed a sense of moral and ethical responsibility towards the work I do and I feel that I must understand in order to avoid future issues with the same.
I appreciate your taking the time to help me analyze the system. I will also work on a sketch to show the safety tank as we already have the conceptual design.
Oh before I forget please let me know if you found the perfect wine, I might want to try it when I decide to visit Spain (In my list of things to do in the future I'd love to visit Santiago de Compostela and of course it will have to include a bottle of wine, bread and cheese), by the way are you living over there now? lovely!! although I should add Texas always needs good Engineers!!

Take care and enjoy your time en el Viejo Mundo

Monica

#4 Guest_MDHernandez_*

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Posted 25 May 2010 - 03:54 PM

Here's the diagram of the system.

Attached Files



#5 Art Montemayor

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Posted 26 May 2010 - 07:17 AM


Monica:

Thank you for your submittal.

Attached are my submittals. I hope they help you out.

Attached Files



#6 Guest_MDHernandez_*

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Posted 26 May 2010 - 02:00 PM

Dear Art,

Thank you for the post, I read it this morning and came to find out I have a lot of thinking to do in respect to my system, I still have some time though. Your reply opened up a different world, by the way reading your previous posts on different subjects and all the questions you post on people's questions has proven to be very helpful. I will keep you updated in regards to my project. To tell you the truth the safety tank (it's a fire arrester tank) is already designed, I am currently designing/reviewing the details on the seal leg (overflow) on the side of the tank but I want to have a better understanding of the concept behind.

Take care and keep us updated on the wine testing exercises in Spain, by the way I reviewed your summary on wines, good pin pointers, although to me it’d be very difficult to follow somebody’s guidelines based on a point system, have you tried it? What are your experiences on this?

Regards

Monica

#7 bmk

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Posted 26 May 2010 - 03:54 PM

The seal pipe --inverse U--- must be minimum 11.0236 m above the level of water in the seal pot. This is calculated as the ht of water column corresponding to hydrogen pressure of 434 in water abs.

#8 Guest_MDHernandez_*

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Posted 01 June 2010 - 01:50 PM

Hi Art,

I continue to review the conditions of my system and while it is not identical to your system, there are some similarities, (i.e. the initial working conditions of the system and thus the increase in water lever, so it has raised some awareness and thus I will have to suggest changes to the design I am reviewing)
On the other hand, the seal pot you are describing seems to be very similar to a pressure relief system for water hammering reduction, I am also working on this but haven’t done much, perhaps I should post something different in regards to the new system, I will do this in the near future when I start dedicating more time on this other project. On that same page at the end of your post you mentioned “Art's Vessel Volumes Workbook”. How can I obtain a copy of this workbook? I am very interested, if you don't mind please let me know.
Thank you and have a nice week

Monica

#9 Art Montemayor

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Posted 02 June 2010 - 03:11 AM


Monica:

Please read carefully the scope of work I assumed and which is on the workbook titled “Monica’s Seal Pot”. This explains a scope that I have to assume since you have not explained that nor given us details on what is your scope. A seal pot, by any other name, is still simply a relief device.

On the same post and directly below the workbook you downloaded is another workbook, albeit, compressed. That “zipped” file is “Art's Vessel Volumes Workbook”. Click on it and you will be able to download it.


#10 Guest_MDHernandez_*

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Posted 03 June 2010 - 01:00 PM

Art,

The system we are trying to implement is actually a system that is already installed at one of our sister plants. I am concerned because of the difference in operating conditions and so a few changes have to be made. I will continue working today on a small diagram and I will post it later. Thanks for the reply for the workbook. I will try to locate a copy of the pressure vessel workbook. By the way, I did follow your previous advise and got a copy of Crane TP 410. It's been great at giving more detail on gas flow. It has led to great discussions among the peers around here.




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