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Kerosene Flash Point Troubleshooting


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#1

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Posted 25 October 2009 - 09:14 PM

Dear All,

Hi , I am zuber , from refinery in Melacca Malaysia, I am a Panel man 16 years experience in distillation. This is my first time experience about kerosene offspec on flash and freezing. Flash point light but Kerosene freezing Heavy.

Appreciate if anybody can help me regarding to flash point result for Straight run kerosene off specification. We should maintain result kerosene flash at 40-42 current result 36 d celcius. Scenario of the control scheme.
1) Top temperature 133
2) COT = 354
3) Stripping steam for kero stripper already increase from 0.8 t/hr (LP Steam) to 3.3 Ton Hr to remove lighter component.
4) Kerosene RD already reduce to 80M3hr from 130m3hr to correct freezing point , to make it -47 (current result still at -44)
5) Wall temp and draw temp different 1 deg celcius (is it this tray already flooding)

My question are.
1) Why sr kerosene flash point not change after we increase stripping steam to 3.3 ton hr.
2) Why kerosene freezing not affect, if Flash point light it can contribute to freezing light also.But in my tower , Flash result light but Kero freezing indicate heavy ..last result -44
3) What can i do , if i want to maintain Feed throughput at same time product on specc.

Appreciate for your feedback

Thanks

Regards
Zuber Attan
Melaka Refinery Malaysia

#2 Qalander (Chem)

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Posted 26 October 2009 - 05:05 AM

Dear,Hello/Good afternoon,

I don't see if the results are for R/Down Product or Local Distillation Tower draw-off pipeline's sample results.If latter is not the case Problem may be extent"Out of box"i.e. distillation column or stripper column.

e.g. Contamination with lighter endsof some type out of distillation tower or Kerosene stipper tower.

Otherwise

excessive dumping of lighter ends with reflux contaminated unknowingly by very light component(s)

or

the stripping steam itself is (somehow) highly contaminated with very light end(s) e.g.LPG like materials finding there way back into the stripping steam elsewhere(un-noticed)

Hope this sows way forward.

#3 Root

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Posted 26 October 2009 - 12:33 PM

Dear All,

Hi , I am zuber , from refinery in Melacca Malaysia, I am a Panel man 16 years experience in distillation. This is my first time experience about kerosene offspec on flash and freezing. Flash point light but Kerosene freezing Heavy.

Appreciate if anybody can help me regarding to flash point result for Straight run kerosene off specification. We should maintain result kerosene flash at 40-42 current result 36 d celcius. Scenario of the control scheme.
1) Top temperature 133
2) COT = 354
3) Stripping steam for kero stripper already increase from 0.8 t/hr (LP Steam) to 3.3 Ton Hr to remove lighter component.
4) Kerosene RD already reduce to 80M3hr from 130m3hr to correct freezing point , to make it -47 (current result still at -44)
5) Wall temp and draw temp different 1 deg celcius (is it this tray already flooding)

My question are.
1) Why sr kerosene flash point not change after we increase stripping steam to 3.3 ton hr.
2) Why kerosene freezing not affect, if Flash point light it can contribute to freezing light also.But in my tower , Flash result light but Kero freezing indicate heavy ..last result -44
3) What can i do , if i want to maintain Feed throughput at same time product on specc.

Appreciate for your feedback

Thanks

Regards
Zuber Attan
Melaka Refinery Malaysia

Hi,
Check your relux flow meter, may be this indicating less flow while you are putting more reflux, stripping steam does not play any role for FF.
Good luck

#4 shan

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Posted 26 October 2009 - 03:56 PM

Dear All,

Hi , I am zuber , from refinery in Melacca Malaysia, I am a Panel man 16 years experience in distillation. This is my first time experience about kerosene offspec on flash and freezing. Flash point light but Kerosene freezing Heavy.

Appreciate if anybody can help me regarding to flash point result for Straight run kerosene off specification. We should maintain result kerosene flash at 40-42 current result 36 d celcius. Scenario of the control scheme.
1) Top temperature 133
2) COT = 354
3) Stripping steam for kero stripper already increase from 0.8 t/hr (LP Steam) to 3.3 Ton Hr to remove lighter component.
4) Kerosene RD already reduce to 80M3hr from 130m3hr to correct freezing point , to make it -47 (current result still at -44)
5) Wall temp and draw temp different 1 deg celcius (is it this tray already flooding)

My question are.
1) Why sr kerosene flash point not change after we increase stripping steam to 3.3 ton hr.
2) Why kerosene freezing not affect, if Flash point light it can contribute to freezing light also.But in my tower , Flash result light but Kero freezing indicate heavy ..last result -44
3) What can i do , if i want to maintain Feed throughput at same time product on specc.

Appreciate for your feedback

Thanks

Regards
Zuber Attan
Melaka Refinery Malaysia

My answer are:
1) Steam is used to strip out light ends. If the light ends were basically stripped out at 0.8 t/h, more steam will not offer any improvement.

2) The kerosene freezing point is controlled by the heavy components. As mentioned above, steam is used to strip light components not heavers.

3) To lower kerosene freezing point, you need to remove some heavy components from your kerosene stream. You may run the tower colder to leave the heavy component in the diesel stream.

#5

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Posted 27 October 2009 - 02:34 AM


Dear All,

Hi , I am zuber , from refinery in Melacca Malaysia, I am a Panel man 16 years experience in distillation. This is my first time experience about kerosene offspec on flash and freezing. Flash point light but Kerosene freezing Heavy.

Appreciate if anybody can help me regarding to flash point result for Straight run kerosene off specification. We should maintain result kerosene flash at 40-42 current result 36 d celcius. Scenario of the control scheme.
1) Top temperature 133
2) COT = 354
3) Stripping steam for kero stripper already increase from 0.8 t/hr (LP Steam) to 3.3 Ton Hr to remove lighter component.
4) Kerosene RD already reduce to 80M3hr from 130m3hr to correct freezing point , to make it -47 (current result still at -44)
5) Wall temp and draw temp different 1 deg celcius (is it this tray already flooding)

My question are.
1) Why sr kerosene flash point not change after we increase stripping steam to 3.3 ton hr.
2) Why kerosene freezing not affect, if Flash point light it can contribute to freezing light also.But in my tower , Flash result light but Kero freezing indicate heavy ..last result -44
3) What can i do , if i want to maintain Feed throughput at same time product on specc.

Appreciate for your feedback

Thanks

Regards
Zuber Attan
Melaka Refinery Malaysia

My answer are:
1) Steam is used to strip out light ends. If the light ends were basically stripped out at 0.8 t/h, more steam will not offer any improvement.

2) The kerosene freezing point is controlled by the heavy components. As mentioned above, steam is used to strip light components not heavers.

3) To lower kerosene freezing point, you need to remove some heavy components from your kerosene stream. You may run the tower colder to leave the heavy component in the diesel stream.


Asalam Alaikom Zuber
Did you check the color of kerosene, second thing check diff.pressure in the draw off trays
you need also to decrease the 1-2celious bottom temp or decrease reflux little bit and wait for 15 minutes and run test again, I have good book in trouble shootong ,i'll try to convert it to soft copy and send you ,when i am free or i'll send you the auther
best regard

#6

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Posted 27 October 2009 - 03:52 AM



Dear All,

Hi , I am zuber , from refinery in Melacca Malaysia, I am a Panel man 16 years experience in distillation. This is my first time experience about kerosene offspec on flash and freezing. Flash point light but Kerosene freezing Heavy.

Appreciate if anybody can help me regarding to flash point result for Straight run kerosene off specification. We should maintain result kerosene flash at 40-42 current result 36 d celcius. Scenario of the control scheme.
1) Top temperature 133
2) COT = 354
3) Stripping steam for kero stripper already increase from 0.8 t/hr (LP Steam) to 3.3 Ton Hr to remove lighter component.
4) Kerosene RD already reduce to 80M3hr from 130m3hr to correct freezing point , to make it -47 (current result still at -44)
5) Wall temp and draw temp different 1 deg celcius (is it this tray already flooding)

My question are.
1) Why sr kerosene flash point not change after we increase stripping steam to 3.3 ton hr.
2) Why kerosene freezing not affect, if Flash point light it can contribute to freezing light also.But in my tower , Flash result light but Kero freezing indicate heavy ..last result -44
3) What can i do , if i want to maintain Feed throughput at same time product on specc.

Appreciate for your feedback

Thanks

Regards
Zuber Attan
Melaka Refinery Malaysia

My answer are:
1) Steam is used to strip out light ends. If the light ends were basically stripped out at 0.8 t/h, more steam will not offer any improvement.

2) The kerosene freezing point is controlled by the heavy components. As mentioned above, steam is used to strip light components not heavers.

3) To lower kerosene freezing point, you need to remove some heavy components from your kerosene stream. You may run the tower colder to leave the heavy component in the diesel stream.


Asalam Alaikom Zuber
Did you check the color of kerosene, second thing check diff.pressure in the draw off trays
you need also to decrease the 1-2celious bottom temp or decrease reflux little bit and wait for 15 minutes and run test again, I have good book in trouble shootong ,i'll try to convert it to soft copy and send you ,when i am free or i'll send you the auther
best regard


Waalaikummussalm,

Noted Thanks, Appreciate for the ideas, really hope u can emel to me the soft copy.

My g mail: zackviet@gmail.com

Thanks

#7 Zauberberg

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Posted 28 October 2009 - 05:44 AM

It appears that the origin of your problem is downstream of the Main Atmospheric Tower - otherwise the operating changes you have made would obviously result in altering kerosene properties (IBP, FBP).

Kerosene stream is often used for preheating incoming crude oil in the upstream exchanger train. If the exchanger is leaking, it's possible to have mixing of crude oil and kerosene which would affect both front end and back end of kerosene distillation curve (and therefore the flash point and the freezing point).

If reducing kerosene draw-off rate and the stripping steam rate do not affect kerosene properties,then (assuming that the Main Frac is not flooding), the problem is almost 100% in the equipment downstream.

Good luck,

#8 Qalander (Chem)

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Posted 28 October 2009 - 10:34 AM

Thanks, My friend Zauberbrge,

I also tried to tell that some contamination Vs low flash material (Crude preheat heat exchanger train e.g. Top Pump Around or other pre-desalter HX)

or

low flash material(ghost)entry into the stripping stream.

or

physical problem with tower internals etc. are to be looked at.

#9 Root

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Posted 28 October 2009 - 02:12 PM

It appears that the origin of your problem is downstream of the Main Atmospheric Tower - otherwise the operating changes you have made would obviously result in altering kerosene properties (IBP, FBP).

Kerosene stream is often used for preheating incoming crude oil in the upstream exchanger train. If the exchanger is leaking, it's possible to have mixing of crude oil and kerosene which would affect both front end and back end of kerosene distillation curve (and therefore the flash point and the freezing point).

If reducing kerosene draw-off rate and the stripping steam rate do not affect kerosene properties,then (assuming that the Main Frac is not flooding), the problem is almost 100% in the equipment downstream.

Good luck,



Hi Zauberberg,

He not explained about the heat exchange route in his posting and you just estimated, we are using kero draw for steam stipper heat exchanging, therefore, if heat exchange scheem is not as you might think then is this possible again to reduce the kero Flash point and IBP.
Even though some light material mixed but this can be recoverd from over head receiver as wild naphtha.
Could shed more light on these assumptions.
Thanks
Toor

#10

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Posted 28 October 2009 - 08:31 PM


It appears that the origin of your problem is downstream of the Main Atmospheric Tower - otherwise the operating changes you have made would obviously result in altering kerosene properties (IBP, FBP).

Kerosene stream is often used for preheating incoming crude oil in the upstream exchanger train. If the exchanger is leaking, it's possible to have mixing of crude oil and kerosene which would affect both front end and back end of kerosene distillation curve (and therefore the flash point and the freezing point).

If reducing kerosene draw-off rate and the stripping steam rate do not affect kerosene properties,then (assuming that the Main Frac is not flooding), the problem is almost 100% in the equipment downstream.

Good luck,



Hi Zauberberg,

He not explained about the heat exchange route in his posting and you just estimated, we are using kero draw for steam stipper heat exchanging, therefore, if heat exchange scheem is not as you might think then is this possible again to reduce the kero Flash point and IBP.
Even though some light material mixed but this can be recoverd from over head receiver as wild naphtha.
Could shed more light on these assumptions.
Thanks
Toor


HELLO ,

Dear All,

Thanks for your good feedback, currently i am already solve the problem, operation back to normal.May be i like to share my findings, there are several factors contribute to the problem.

1) Proccesing high light end.
2) Crude tank , not enough time for better mixing and settle down time.
3) Adjustment to fast , and sampling time to fast , not enough time to wait until it back normal CUT POINT and normal Parameters.
4) Field Tech not flush line above than 5 min during sampling.

Anyway thanks to all, appreciate for your valuable time and idea to help me.

Thanks

Regards
Zuber

#11 Qalander (Chem)

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Posted 29 October 2009 - 01:49 AM

Thanks Very much zuberattan,

for prompt update;definitely confirming as if few contributory factors were outside of main box(atmospheric distillation tower);whereas


haste i.e. "NOT PERMITTING SUFFICIENT TIME TO THE SYSTEM TO RESPOND" has also been the factor.

This post of yours will help many others refraining from second part as occassinally some of us operating staff become somewhat ignorant to the fact

that certain amount of ral time is always needed to accurately witness the effect of our adjustment(s) as per any of the system(s) complexity and size.

Just keep it up.




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