VGOHT Feed Filter Pressure Drop 2

[DDSpetro]

Dear all ,

The VGO Hydrotreater feed filteration system is facing problem of higher pressure drop , The feed is the mixture of Heavy vaccum gas oil,Light Vaccum gas oil and Heavy Coker Gas oil.The culpit is seen the quality of Heavy Coker Gas oil.Whenever, Coker unit,Ratio of HCGO Hot wash / Coker T'put is lower than 94 , the problem is more aggravated in Downstream VGOHT units which calls for very frequent filter stoppage , cleaning as well as some time reduction of VGOHT t'put also.

The correlation of VGOHT feed filter Delta P vz. Ratio of Coker Hot wash/Coker T'put is attached for your reference.

The constraint in the coker side is that higher ratio will call for reduction of Coker T'put as well.

PTQ forums says VGO Feed asphaltene should be less than 500 ppm which in this case it is 2 to 3 times measured and it is seen 500 ppm, ASTM D-1500 Color also remains <8 to ensure oil compatability and diene test.

Kindly give your expert openion to mitigate the problem.

http://files.engineering.com/getfil...learance_for_VGOHT_Feed_Filter_DP_Project.ppt

 

[RogerH]

DDSpetro
What type of filter do you have? For similar units like HCU which have backwashable filters this shouldn't affect the throughput.
The relation of less wash oil in the coker and shorter run lengths on the filter sound logic.
One common problem with cokers is the cyclic behaviour and foaming that can result in quality variations and "kicks" of particles to the downstream hydroprocessing unit.
If you can investigate the quality variation on HCGO during a cycle it would be useful.
If you can use the diluted D1500 method (if needed) it gives some better resolution in the readings.
Since it is particles and not directly asphaltenes that is getting trapped in the filters a filtration test on the samples might provide you with the necessary info.

 

[DDSpetro]

Yes, it is backwashable filters with 23 elements.
Another theory is about conjugated olefin
i.e.Polymerization of diolefin.which is another potential factor.To analyze this, should the material/sample of filter while open can be better to do TOC test or Thermography analysis - TGA would be better ?