Refinery shut down

[zayed78]

Hi,

We have small refinery called Topping Plant we only produce Diesel from it in Our Field. I Have one concern about temporary shut down from this plant for only ( 1 to 2 months) not for maintenance only due to security situation.

My question here any procedure will be applied when such shutdown for this plant ( procedure for Suspended the plant).

Thanks

 

[EmmanuelTop]

It depends on what are the concerns you have. Theft? Fire/explosion? Corrosion? What is is that you want to protect (from)?



Dejan IVANOVIC
Process Engineer, MSChE

 

[zayed78]

Thanks Dejan,

Corrosion concern Sir

 

[EmmanuelTop]

If shutdown is going to last for 1 or 2 months, one can usually follow procedures similar to those used for plant turnarounds - with the exception that asset/plant owner might decide to de-inventory all vessels and piping, in order to reduce damages caused by sabotage and/or intentional ignition of Hydrocarbon inventory of the plant. This is a likely scenario, given the fact that shutdown is driven by security issues.

This means - isolate, drain, vent, purge and inertize all vessels, rotating equipment and piping, and maintain it under slight positive pressure. Ideally use Nitrogen because it is not flammable. In normal circumstances one could also use dry fuel gas, but since you are facing potential security problems it is the best if you keep your systems free of anything that can burn or explode. I'm thinking that even leaving the entire plant exposed to atmospheric air (after purging) is a better option than filling it with fuel gas. No real damage should happen within 1-2 months if equipment is open to ambient air.

Non-hazardous and non-corrosive systems (i.e. Instrument Air, N2, fire water etc.) can be left as-is, meaning no draining and purging will be required.

If for any reason there are chances for this shutdown to last for 6 months or more, you should be looking at mothballing of the entire plant. This is much more complex thing and it requires inert fluids, greasing chemicals, coating agents, rust prevention chemicals etc.).

Dejan IVANOVIC
Process Engineer, MSChE

 

[zayed78]

Appreciate your help Dejan. It is clear now. Actually in the first time we just circulating the crude through the plant but when we don’t have enough crude we are forced to shutdown the plant.

 

[georgeverghese]

If this crude has some wax in it, you may find water trapped under wax in the column - which can cause corrosion due to the bacteria in the water and mineral salts in it. A closed loop hot solvent clean of the column (and all associated equipment that crude has come into contact with) followed by the steps Dejan has suggested may be required.

 

[georgeverghese]

Instead of a hot solvent, steam may do just as well, plus it is a lot easier to use.

 

[zayed78]

Thanks Very Much georgeverghese. last question I have about the chemicals which are used in normal operation we are using 3 chemicals ( Anti-foulant, filming amine and Neutralizer amine)
in the circulating case I have used only Anti-foulant, so I am in the correct a way ??

Note that the injection location of Anti-foulant at crude feed pump and filming amine at over head tower


Thank you

Zayed

 

[EmmanuelTop]

I wouldn't use continuous injection of any chemical in the circulation mode. The reason being simple - these are all closed-loop circuits and makes no sense to keep adding chemicals to the loop. In addition to that, the circulation temperatures are significantly lower than operating temperatures, so the potential of fouling is very low.

Dejan IVANOVIC
Process Engineer, MSChE

 

[zayed78]

Thanks EmmanuelTop in our case circulation cold crude but as open loop I mean the crude comes from crude tank which is in off/on loading. However, I will recommend to decrease the chemical dosage to minimum rate ( Anti-foulant).