For injecting liquid into liquid, it does not make much difference whether the injection flow is co-current or counter-current. There are some resources (A. Sloley) quoting that even in cases of injecting liquid into vapor stream the orientation does not have significant effects: http://www.chemicalprocessing.com/articles/2012/do...

Top connections are preferred only for accessibility and maintenance reasons. Process wise, there is absolutely no difference.

The best thing to do is to provide injection point upstream of the pump or a control valve. Turbulence created across these devices will ensure proper mixing in all cases, regardless of the flow of main stream.

Dejan IVANOVIC
Process Engineer, MSChE

Also take into account that a bottom tapped CI point may jeopardise the operation of block valves and check valves that are on the CI line if there are solids in the residue heavy oil.

Thanks Dejan IVANOVIC & georgeverghese.

We decided to inject the chemical upstream residue pump after re-boiler (Heat exchanger residue /diesel) then after that will goes to 2 stages of exchangers( Crude/ Residue) finally will be stored to tanks.
Pipe specification 4 inch SS 316
Residue Tem 650 F and P=12 psi
Chemical type: Pour point (wax based & will be diluted with Naphtha DF=2)

Any concerns (Process, Corrosion....etc) will be raised gentlemen


Zayed

And your quill is made from a material that is extremely corrosion and erosion resistant, right?
I have seen so many pipe failures over the years because of failed quills that I don't count them any more.
A short piece of alloy 625 is cheap compared to a failure.

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P.E. Metallurgy, Plymouth Tube

Will this PPD survive in this resid at a temp of 650degF ? Have you checked with the PPD supplier?

Thank you Gents,
Our Quill is made from 316L SS; the rated Temperature (550 C to 800 C) is above the residue Temperature. Also system pressure is very low. Galvanic corrosion is not applicable (316 pipe and 316L), the question here what/why the failure will be occurred as such system.

Zayed

So the quill is sch80 or heavier? I would still look to see if I could get alloy 625.
It is stronger (especially at temperature), more corrosion resistant, and more erosion resistant.
I have seen quills fail in fatigue, corrosion , erosion, and mechanical damage (large debris). Once they fail the chemical being injected washes along the pipe wall and often causes corrosion issues there because it is concentrated.

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P.E. Metallurgy, Plymouth Tube

zayed78

To make the chemical injection on top side of the pipe is the good choice. If you didn´t chose this option after some time of operation the scale will plug your injection quill.

good luck

Luis Marques

zayed78

If you are dealing with a chemical injection, for naphtenic acid protection, alloy 625 is a good option. To avoid tubulance and corrosion your quill should be injecting the chemical into a 12" pipe.

Good luck

Luis Marques

Zayed, as Luis Marques just said, if you think about your daily operation with heavy oil product considering the possibles varietions of temperatures caused by process variations, I am sure that once you reduce strongly the flow rate of this pipe, the injection point will be blocked. So I would say that you have taken the best future thinking choice. I have been working with the vacuum waste oil for the past 8 years.
BRITTO.