11 replies to this topic

[trungphu]

My distillation column was design at working temperature of 70 ^oC.
Is it more economical if I made a insulation for it? I mean whether the cost of insulation wall is higher the energy saved cost or not. The ambient temperature is about 30 ^oC.

Could someone give me some advance? Should I made a insulation for my distillation column?

Regards.

Edited by trungphu, 08 November 2012 - 01:10 PM.

[trungphu]

The diameter of column is 0.9 m.

[fallah]

trungphu,

At 70 C, i think you should apply the insulation on the column for personel protection. Then it can function as thermal insulation as well.

Fallah

[SUPRIYAPRA]

At 70 degree centigrade, no insulation is required.

[fallah]

DHIREN,

It depends on relevant project spec; but in most projects specs the temperature limitation below which no need to insulation for personnel protection is 60 C.

Fallah

[SUPRIYAPRA]

I fully agree with you Fallah, 60 degree is Exxon and international projects specifications requirements.

[ontherun]

The general rule of thumb for personnel protection would be:

If the outer surface is likely to reach a temperature range of between 60 - 65°C at a height of 2m or 1m outward of walkways & access platforms where thermal insulation is not applied, then personnel protection should be considered. If for example, you have a particular issue with CUI and the option is not to install thermal insulation. Wired mesh cage guards is a reasonable option.

OTR

[Art Montemayor]

This is an issue that hits directly on safety and human values.

It also involves practical, common sense and should be devoid of applying general rules of thumb that do not apply. I totally agree with Fallah’s comment. From every aspect, this column should be insulated. There is no reason, in my mind, to leave it bare. Consider the obvious, real-life conditions of this application:

This column – as proposed – is a very tall and slender one. It will require extensive supports and a steel structure just to stay vertical and stable. That means it will have to be located outside of a building, without cover or protection from the weather. It will be located at a university in Vietnam. Am I to assume that it doesn’t rain much in Vietnam? Well, if it ever does, the column will be inoperative – or totally unstable due to the excessive heat transfer loss through its external shell.

I defy anyone reading this to wrap his hand around a steel object that is at a temperature of 70 ^oC. If that fails, try 60 ^oC – and keep your hand wrapped around that object as if your life depended on it. You will immediately find that you can’t; and that is exactly what happens out in industry under actual, working conditions when a worker or operator stumbles on a platform and reaches out with his hand to grab anything he/she can hold on to in order to avoid falling from an elevated platform or structure and suffering a grave and horrible fall. In the 51 years I’ve spent as an engineer, I have seen this happen far too often – even to myself. Therefore, I write this with first-hand experience and I would never allow my workers to be exposed to having to hold on to a 70 ^oF object or fall from a dangerous height. I am frankly very disappointed that this important, potential hazard has not been discussed and assessed here.

Even if this column is installed indoors, the heat build-up around it due to the heat transfer loss would make it impractical to go near it.

This column should be insulated in order to ensure stable, and steady operation during a university laboratory operation where important data is surely going to be taken and used for other purposes. Students will surely want to witness its operation and results. The fact that this column will surely be operated by students and/or non-professional operators make it doubly important to make sure no one gets hurt or injured.

[Art Montemayor]

No one has made any further comments on this safety (not insulation) issue, so I'll close it by stating that I've always applied 48 ^oC (120 ^oF)as my temperature limit for personnel protection. However, I should note that circumstances, situation, and time duration also are factors. Please read the attached NASA document that seems to strengthen my argument.

Attached Files

•  NASA Human Touch Temperature Standards.pdf   2.53MB   97 downloads

[trungphu]

Mr. Art

I didn't access Cheresources for a long time. Once again, you give great answers and sharing to the Forum.
I really admire your 51 years working as an engineer.

Could you make some comment about potential hazard in my process? I also know that benzene is a carcinogen. Thank you!

Ps: Actually, it rains much in Vietnam.

Edited by trungphu, 01 December 2012 - 04:42 AM.

[Neelakantan]

ART,

i am sorry you expected some one to say a comment once you have said which is mostly considered as the final word on this!?

as an operating engineer who worked on plants (hands-on! and used to climb the ladders and feel the heat of the Un-insulated towers), i had hard time to make our HSE people to insulate anything above 50 deg c (in india summer temp can be as high as 45 deg and reputed engineering companies still talk about 60 deg C and 70 deg C limits for pp insulation and get away with wiremesh!)

Any engineer who has handled shift personnel and operations group knows that ~50 deg C is the maximum possible for a few minutes contact and nothing above is unacceptable.

regards
neelakantan

[S.AHMAD]

1. 45C is probably the safe limit for touching with bare hands.
2. It is a good practice to wear gloves when entering process unit in addition to others PPE (hat, shoes, FRC, ear muff, specs etc.).
3. Therefore, 60C is still a valid figure and probably the most cost effective figure.