KEROSENE/ LIGHT DIESEL 2

[padovano]

The gap,i.e the temperature at 95% distillation of Kerosene minus the temperature of Light diesel at 5% distillation is about 4. This that the fractionation is not good, the is a good quantity of kerosene which remains in the Light diesel. Can some body give me an idea on how I can go about this.

 

[JLSeagull]

C or F?
Are you looking for a lab or online technique for 95% End Boiling Point analysis?

 

[JLSeagull]

ASTM D 86 Standard Test Method for Distillation of Petroleum Products at Atmospheric Pressure

ASTM D 1160 Standard Test Method for Distillation of Petroleum Products at Reduced Pressure

ASTM D 2887 Test Method for Boiling Range Distribution of Petroleum Fractions by Gas Chromatography

ASTM D 2892 Test Method for Distillation of Crude Petroleum (15-Theoretical Plate Column)

ASTM D 6352 Standard Test Method for Boiling Range Distribution of Petroleum Distillates in Boiling Range from 174 to 700°C by Gas Chromatography

ASTM D 7169 Standard Test Method for Boiling Point Distribution of Samples with Residues Such as Crude Oils and Atmospheric and Vacuum Residues by High Temperature Gas Chromatography

IP 123 Petroleum Products—Determination of Distillation Characteristics

IP Standard Methods for Analysis and Testing of Petroleum and Related Products 1996—Appendix A

 

[EmmanuelTop]

If you want to increase the fractionation efficiency between Kerosene and LGO, it can be done by implementing following operational changes:

1) Reduce LGO pumparound rate
2) Reduce Kerosene draw-off rate

By doing this, you will raise the efficiency of fractionating trays between Kerosene and LGO - by allowing for higher internal reflux rates.

 

[hanon]

The most effective way is to increase stripping steam in diesel side-stripper. This way the lights compounds will be evaporated from the diesel and they will go into the kero stream. Reducing the kerosene drawn-off sometimes is not possible since the cut point will be modified from the planned target

 

[gedomin]

It seems your degree of fractionation is like typical for 5 or 6 actual trays between cuts. You can check against simulations. You've got to determine actual cut point between cuts, in order to set your running plans.

 

[UmeshMathur]

In my opinion, the only way to determine the best option to improve fractionation is to use a calibrated column simulation model to provide reliable guidance. The model calibration must be done against averaged on-line data (gathered over at least a few hours of steady operation, with lab samples gathered for product quality). This is a non-trivial exercise.

Then, running the base model against various cases and simple plotting of the pertinent variables provides great insight.

Options to consider include:
(1) Increase feed preheat
(2) Adjust pumparound / overhead reflux duties to increase internal L/V ratio in the tower section under consideration
(3) Adjust product draw rates
(4) Adjust side-stripper steam

The final answer would likely be a combination of all of the above.

You might also need to run pumparound exchanger rating calculations because, beyond a certain point, increasing circulation does not increase duty appreciably. Also, significant changes in column or furnace loading might require checking against equipment capacity limits (tray hydraulics and furnace tube metal temperature, etc.).

It's a lot of work, but that's what process engineers should do.