27 replies to this topic

[latexman]

 

BP Pf5 84.55 C

BP Hf 19.5 C

check with your process engineer.

I think you missed -sign in BP of PF5. It is around -84oC

 

When I Googled PF5, the Google summary on the top, RHS made the error.  It says nbp = +84.55 C.  I sent them feedback on it.

[breizh]

Hi,

You mentioned 10 years old plant (may be more), structured packing. No details about internals of the column, distributor, redistributors.

A few questions:

* What is the metallurgy of the column and internals?

* Was the performance of the unit better when it was new? Less impurities below 100 ppm? Is the level of impurities going up and down over the time?

*How often did they perform turn around on this column, how often did they change the packing?

*If they change the packing, did they purchase the original brand and/or from a reputable company? I believe the structured packing is BX type.

Note: 

Packing should be installed by skilled people to prevent any damage. I've seen people walking on them.

 

* Did they notice bypass within the packing and/or damage at the bottom of the beds? Risk of liquid carry over.

I've experience on a touchy process where BX was purchased from a local supplier because of the price, it looked like the original but needed to be replaced to get the right performance. BX from Sulzer.

What about the distributor, they must be cleaned and level check (horizontal) before starting up to prevent maldistribution of the liquid.

 

Note: I believe the pall rings are there to prevent carryover.

 

*Did you check the disengagement height at the top of the column, sufficient enough,or do you have a device to mitigate liquid carryover?

 

About your process, you did not give us much information, what is the mass balance? Same for the operating procedure! Did you check with the plant. I believe there is accumulation of impurities at the bottom of the reactor and time to time they are draining the heavies and restart their process with fresh material. Check their cycle time. I encourage you to discuss with the operation team.

 

Note: an external HX will improve the heating process in addition to the jacket.

 

I cannot offer more. Hope this going to help you.

Good luck

Breizh

[shvet1]

@breizh

 

Give up, these are electronics people, not chemical on. They behave another way as we do. 

 

Process team leader wants to add more theoretical trays betting on this might help somehow as this is the simplest way to respond on product specifications tightening. How this looks like - a huge modern overexpensive semiconductors plant and a small ordinary cheap plastic gas generator placed somewhere in the faraway building corner, phhhh. A source of a minor chemical supply is not worth one's time and efforts even that is extremely dangerous as no one at that place has encountered problems before, reported, published and widely accepted ones ("what did not exist does not exist" (с)).

 

I bet they do not even have a proper overpressure protection so there is no point to optimize design. The plan is clear - if one section will not allow to reach 10 ppm then just to add one more. And so on and on. Overprice/inefficiency and time loss is negligible comparing to total cost of future production site.

 

The question is - do they really need 10 ppm downstream as in that industry many specifications are based on precautions rather on proven tests or similar. And note that the teamleader might understand this very well so even 90 ppm would become enough.

Edited by shvet1, 07 July 2023 - 09:14 AM.