[evan]

Hello –

I have participated in some vibration harmonic analysis of some units with severe vibration issues. One example had 1 hz period with a magnitude of deflection that exceeded 20 cm in some piping. The issues come and go but seem to be related to a number of issues…..

+ feed composition and vaporization rate in the transfer line
+ heater COT
+ Angle of inlet nozzle
+ Random channeling in the coke bed

Are you able to reproduce the problem with every drum or does it only occur on some drums?
Do you have skin TI around the coke drum to monitor for differential heating?

I’m not sure I understand what you mean about feed rate effects on 1 drum during decoking. I believe you only have a 2 drum unit at HDO so this should always be the case.

Have you considered the Deltavalve center feed device. If the problems are severe and consistent, this would be a good solution for your plant.

[evan]

Hello,

Sorry for the delay in responding… yes, your calculation is correct as I interpret your writings. 14lb vs 16lb seems reasonable. 600cSt should be more effective because of its higher MW. You might be able to use less than the 1 lb/1000bpd rule of thumb because that assumes a lower MW antifoam.

Are you just trying to save cat/chem cost for Solomon or having a AF effectiveness problem?

[evan]

Hello,

Sorry for the delay in responding… yes, your calculation is correct as I interpret your writings. 14lb vs 16lb seems reasonable. 600cSt should be more effective because of its higher MW. You might be able to use less than the 1 lb/1000bpd rule of thumb because that assumes a lower MW antifoam.

Are you just trying to save cat/chem cost for Solomon or having a AF effectiveness problem?

[evan]

Hello

I’m going to be in the Lake Charles area the first few weeks of April, I would like to meet the committee and hear more about this phenomenon if you have time. My email is “Evan at coking.local”

[evan]

Hello Coking Committee

Yes, many cokers use HCGO as drum vapor line quench and it works well. In fact, I believe it works better than LCGO because the higher boiling point keeps the oil in a liquid form and promotes a washing effect of the piping walls. LCGO can quickly cool the drum vapors but solids can still accumulate along the wall. IF your line velocities are very, solids could be washed away by the vapor but less likely.

However, the even better drum vapor quench medium is blowdown tower bottoms, if you ask me. It is a great way to recover slop internal to the unit.

Curious, how many people are in your committee and where are you based?

[evan]

Hello,

Good question, the rule of thumb is 1-lb of AF per 1000 bbl of feed per day.

Other things to consider are:
1. AF quality – higher cSt (300-600k) uses less versus 12.5k cSt
2. Feed types – highly foaming feeds like ultra heavy crude, bitumen and Orinoco type crudes, are know to foam more and require more AF.

Can you share with us what you are running?

Thanks

[evan]

Hello Jesus

I have a few questions to clarify your question….

1. you are talking about the sponge tower bottoms pump, yes?
2. Do you have any data of the composition of the polymer? There are many types of polymers to additional information would be helpful.
3. Do you have any photos of the material? Is is sticky or solid?
4. Where exactly is the poylmer found? Seal face, pump case, pipe around the pump
5. What temperature is the pump running at?

Many polymers in cokers are formed by di-olefins overheating and polymerizing. Reactions are a function of time and temperature. Eliminate high residence time dead zones or decrease the temperature.

[evan]

Hello Manish –

The rate of vapor heating a coke drum is controlled by the pressure balance of the system. To force more flow into the heating drum, you have to change the pressure balance in favor of the flow that direction. For instance you could….
– pinch overhead vapor valve
– open the condensate valve fully
– line up the condensate to a low pressure system (blowdown tower over the frac or condensate pot)
– other options may exist depending on your configuration.

Did this help?

[Author]

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