3 replies to this topic

[drilling2013]

Hello every one,

 

We have field small refinery to produce diesel ~10000 BFD API =36, BS&W=0.05 and salt= max 4 PTB in our plant already designed one stage deslater my question in such case need to operate this unit I mean mix crude with service water or no need. See below the water and crude desalter in/out result: (see attached file)

 

We faced problem with over head water accumulator with high chloride and iron content and ph fluctuating value out of range (5.5-6.5) as you can see from attached file results.

 

Note that we injecting neutralized amine which is diluted with service water 1:3 with total rate is 7 gpd ( naphtha reflux to crude tower injection point) and corrosion inhibitor with rate 8 gpd (upstream of overhead condenser exchanger).

 

Moreover, over head exchanger is experienced high corrosion, tubing crack at inlet ends no fouling problem has been reported for desalter downstream (Heat exchanger tubing) we used Antifoulant chemical (crude discharge pumps).

 

Using water wash is the root cause of corrosion and high chloride level at over head accumulator. What the source of high chloride level (our crude is very low PTB & BS &W).

It is worth to mention that we closed deslater operation for long time but we face same problem high chloride, iron and ph value fluctuating. What the source of chloride our crude feed low salt and BS&W values.

 

Your recommendation is highly appreciated

 

Zayed

Attached Files

•  Crude & Desalter water injection Sample.xls   34.5KB   49 downloads

[Arsal]

check organic chloride in your feed.

 

organic chlorides are not removable in desalter.

 

What is ACID NO of your Crude?

[drilling2013]

Thank you Arsal

 

Organic chloride less than 1 ppm

ACID NO 0.1 -0.03

 

Zayed

[Napo]

Drilling2013,

 

What are the parameters of design of your desalter (in-out ptb)? I see that efficiency is low, but the 2 ptb is a low value, that is acceptable for atmospheric distillation.

 

A reduction of content of chlorine salts in crude oil does not eliminate hydrogen corrosion of equipment. If your Acid Number is between 0.1 and 0.3, and usually is greater than 0.2 mg KOH/g there are the possibility of corrosión if the material is not adequate.

 

Do you employ steam in the bottom the main tower?

 

Do you have corrosion coupon in the overhead?, maybe you need to change the dosification of neutralizer and corrosion inhibitor. The rule of thumb is 2 gal neutralizer/1000 bbl, 1 gal corrosion inhibitor/1000 bbl and 1 gal demulsifier/1000 bbl (if you use).

 

Napo.