Liquid distributor test for columns 1

[mhrizadi10]

in order of liquid distributors form internal suppliers such as SULZER,RASCHIG,... is it essential to ask liquid distributor test or not?
there are 2 type of tests: gravity test and max.min. flow rate tests.
which one is essential?

 

[siretb]

My experience is that such tests are essential.
What should be verified is the evenness (homogeneity) of the liquid distribution (m3/hr of liquid per m2 of section, at different areas, and at least at nominal and minimum flow rate.

 

[mhrizadi10]

thanks alot
another question
it should be considered for all distributors,collectors or not? what about redistributors ?

 

[siretb]

All liquid distributors, redistributors.

Poor distribution or maldistributions affect the column performances, and all the more if you need a pure product at any end (top or bottom)of the column.

 

[ae137]

Good day, if i may chime in, while it is best to test a liquid distributor from an unknown vendor, it is is common place to just ask the supplier for a performance guarantee, such as distribution quality or fouling resistance, depending on your goal.

When you specify a liquid flow rate, the vendor typically designs around an operating range, as a safety factor.

Different distributors have different capacities. Oftentimes, there is a size constraint, such as small columns (<36"), where you are limited to using a pan type or deck type (re)distributor.

I do not mean to violate any rules but i work for a mass transfer company so you can PM me if you need help AND if that is not a problem with the forum mods.

 

[sshep]

Another chime in: For spray nozzles it might be worth it, but for troughs the evenness of spray (assuming even holes)is determined by the liquid head. This head can (and should be) checked by calculation. Since the distributor tests are performed with water in air, the conditions may be far from what is inside the tower.

If you do the distributor test yourself, it is usually qualitative. You assemble the distributor on a scaffold and use a plank to peer into the spray. Again, in my experience I can only say these type tests have been useful with spray type nozzles. For troughs, if the levelness and head is good, the distribution is usually exactly as per the drip point density.

Lately we replaced some new feed distributors on 3 towers which were only recently (but poorly) designed by Koch, where we had poor seperation on start-up. The redesign gave a fantastic improvement. The problem was not with the distribution itself which was even. The problem was the recollected liquid from the bed above not mixing well with the feed, causing a concentration gradient along the length of the parting troughs. Some in-situ trough head measurements and observations with water were made, but such observations did not pick-up this mixing problem. You would have had to use a dye or something to see the mixing problem.

best wishes,
sshep

 

[jamesbanda]

Another chime ;

Yes yes and yes you should test them and take a look if you can -

1.sometimes the design is done else where to fabrication - so details can be missed. I had this issue .


2. For exotic materials often vendors make carbon steel trays to test even a mistake here is low risk and cheap


Anyhway my comments









2. For compe

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[mhrizadi10]

Dear Friends
as i consult with our vendor, they will give us the performance guaranty so any future problem is on his response so i think mentioned test are not essential. as you know the test price (specially for max-min flow rates) are high and in previous project we didn't ask vendors to do this test. about missed details in fabrication: the third party should check all items to avoid these errors.
anyway what do you recommend?
i have to place the test in my order or not? if you have any experiences please inform me.
to this time 2 of friends say the test is essential and 2 of them say it is not necessary! please help me

 

[jamesbanda]

This my comemnts on your notes

1. 3rd party inspection: They will only inspect per the drawings. And, wont pick up issues that will cuase poor operation - i've been next to a 3rd party inpsector and asked dont you think this will fall of on installation - oh yes.. but is just as the drawing. ! so if you go that route consider the quality of the people.

2. In my experience i've seen several distributors fail tests and have to be modified. Kister book will recommend pass tests. I've also had trays installed in columns in retro fits - we did not test them at site then to consider oh how are we going to seal that - it does not hold water(on a site water test) then having to get expensive sealant to retro fit on site.

Vendor warrenty - yes its good but check it only cover the purchase cost not the losses cost to you as operator.. it never will it only severs to ask the vendor to be professional.. not to mittage your risk.. i bet your production cost per hour or loss per hour is many times what the purchase order is for the column..