12 replies to this topic

[v8landy]

Hi

We are about to convert one of our columns for IAA drying via cyclo hexane.

Will be looking to feed to a mid point on the column, but it currently does not have one?

The column has structured packing, 12m x 1 high, with return feed currently to the top of the column via it current distributor ring.

There is a man-way mid way, so without taking the column down what options can I use?

[Art Montemayor]

Your description is not very clear as to what you have and how you want/need to modify the column. What I understand you want to do is depicted in the attached sketch.

I have done this type of modification(s) several times in the field and don't see this as a difficult job. However, I may be mis-interpreting your description.

I hope this helps.
 Packed_Column_Feed_Modifications.xls   24KB   85 downloads

[v8landy]

Art your sketch is exactly what I want to do.

Due to the size of the column, removing it to the ground would be simplest way to perform the work required - i.e., remove top sections of packing, weld in support grid, and add liquid distributer pan.

Welding (hot work ) on-site is always very difficult to obtain and if it can be done out of the zoned area, it is simpler.

Thanks

[v8landy]

Addtional

I have always bought off the self liquid distribution rings, they "look" simple is it somthing I could have buit up from my own simple design?

PS what software did you use to draw the above sketch?

[Art Montemayor]

I'm glad I was able to interpret your intent correctly. I didn't know if we were both on the same page and consequently only dedicated a few minutes during lunch to slap together a quick sketch that I didn't put very much effort into. I could have put something more professional and detailed together, but time didn't permit.

Not knowing the dimensions and weight of your column, I was hesitant to assume that you could remove it and subject it to a shop where skilled workers and controlled facilities can guarantee a first-class modification. If you can justify putting the column in a shop under controlled conditions, that's the way to go – especially if the work is to be done to Code and the column is going to operate under elevated pressures and temperatures. The personnel safety issue is another greater concern when doing this type of modification – especially at elevations and confined spaces.

I was trained and worked as a boilermaker when working my way through university. My preference has always been to design and fabricate my own tower internals design. When I supervised plants overseas I even did my own cutting and welding whenever I had the time or justification.

The only software I use to draw in Excel is embedded in my brain. I draw, sketch, and illustrate in Excel using only the standard drawing tools that Microsoft furnishes. For a short and quick tutorial on this subject go to:

http://www.cheresources.com/invision/index.php?showtopic=3684&hl=draw+excel

and you will find an Excel Workbook that serves as an example of what can be done.

Hope this helps.

[Zauberberg]

V8landy,

Why do you have concerns regarding tower modification on-site? I think this is the most common way of doing it, assuming you have prepared all that is required as per the procedure(s). Amongst some cases, I have witnessed a huge (6m-diameter) ADU tower revamp, supervised by Koch-Glitsch, and executed on site: the purpose of the revamp was to increase the number of trays in tower bottom section, which has been done by cutting the existing tray support rings and welding new support rings at different locations in the tower. The entire work went quite smooth. The problems may arrive if the tower is too small, making it more difficult to execute the work inside the confined space, as Art mentioned.

Have you checked the impact of reduced number of mass transfer units when middle section of random/structured packing is removed? Make sure you don't lose separation efficiency once when you introduce the side-feed.

Good luck,

[v8landy]

Saftey is always priority.

If work can be done out of the zone i.e move it it is genrally the best. A 100T crane will romve the column in not time Simple! It is realy only a toy column compaired to what some of you are working on.

BUT if we do have to do hot work, all the regulations are and can be met, but this is ALWAYS after ALL other routes have been exhausted.

GOOD news!

We have very limited historical data on our site equipment, but I have found a drawing of the column which does sugest a mid point (distribution ring + packing above support grid)

Still is currently off for heating tube repairs, so I plan to get the suspected feed port opened up for internal investigation.

Thanks anyway for your adivice, I am sure one day I will have to do it.

I have only just finsished another jub of repacking a smaller column (10 m x 1m) but again this was just craned to the shop for work, easy!

Thanks

[Qalander (Chem)]

Dear v8landy Hello,

This is really Nice/Heartening to see your safety loving attitude;
definitely with smaller sized (less heavier,less bulkier) pieces of equipment this sounds good& manageable.

But at times the crane safe operation and maneuvering modalities do become real safety concern on running or H_C containing plants.

Best regards
Qalander

[v8landy]

Dear v8landy Hello,
This is really Nice/Heartening to see your safety loving attitude;

Qalander

Thanks for your compliments.

In my view saftey leads, if you have saftey you can progress and improve any site.

Cranes always have their own special saftey issues, but like any task, by risk assessing in introducing control measures the risk and be reduced or eliminated.

Also by taking the item to the shop, it makes for a better working enviroment for the welders etc rather than being X meters in the air on a bit of scaffold board!

Problem solved, on with the project, until the next time I need to ask a question.

[v8landy]

See attached a drawing of the column

Attached Files

•  Column_6_Spec0001.pdf   47.71KB   71 downloads

[Qalander (Chem)]

Dear v8landy Hello,

It is true if the vessels, Columns, and equipments are removable and shifted to some safer workshop or other location with needful, positively ensured gas-freeing etc, Risks and site related Hazards are minmized.

It is also true that with proper safegurds thorough implemetation, we can manage better easier and quicker job out of active unit locations.

Look forward to mutual learning exchange.
Best Regards
Qalander

[v8landy]

I am currently managing the replacment of the thermal oil heating coils in on of my distilation stills.

A still can not be moved, so confined space entry is required, gas testing, hot work permits required etc.

The still had to be draind first, then high pressure water cleaned. Old coils "cold cut", bund areas foamed down for cutting.

Now waiting 2 weeks for new coils to be made.

Will then require welding in place.

All of this work can be done just needs risk assessing and planning.

Even with all of the above, working in a still is not nice.

[Qalander (Chem)]

I am currently managing the replacment of the thermal oil heating coils in on of my distilation stills.

A still can not be moved, so confined space entry is required, gas testing, hot work permits required etc.

The still had to be draind first, then high pressure water cleaned. Old coils "cold cut", bund areas foamed down for cutting.

Now waiting 2 weeks for new coils to be made.

Will then require welding in place.

All of this work can be done just needs risk assessing and planning.

Even with all of the above, working in a still is not nice.

Dear,
It's All about about taking challenges
proper Risk Review/Estimation.
Taking all the necessarry or an edge more counter measures
to handle possible emergencies safely
Even then one has to be extra cautious/extremely vigilant alongwith the team.
Best Regards
Qalander