Average Antifoam Usage

[rwienandParticipant]

I understand that the amount of antifoam used in each DCU will vary with operating differences, but what is the industry standard for antifoam usage in the unit per bbl feed?

[Evan HydeKeymaster]

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

[rwienandParticipant]

Hi Evan,

Thanks for the response. We are using 600k cSt antifoam and our refinery does not process extremely heavy feeds so it sounds like the 1-lb of AF per 1000 bbl of feed should be a good general guideline for our unit.

I want to make sure that I am doing the calculation correctly. For example, if the unit was running 16,000 bpd, following the rule of thumb we would need to use 16 lb of antifoam in a day, correct?

By my calculations for our DCU, we’re averaging ~14 lb AF per 1000 bbl of feed per day.

This doesn’t seem correct because it does not feel like we are using an excessive amount of antifoam for the unit.

[Evan HydeKeymaster]

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 HydeKeymaster]

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?

[bsudhakarParticipant]

Hello,
It is not just the numbers that matter. For maintaining inventory or to take care of re-order levels, these numbers might serve well. Any sincere optimization efforts can cut it down by at least 50%.This is not only a Opex (Operating expenses) saver but will mitigate downstream unit difficulties with silicone chemistry. Real optimization requires monitoring of coke, heavy oil, water, vapor phase Levels on a continuous basis on DCS screen and concomitant actions in field(like calibration of metering pumps, calibration of instruments, timely operator actions – when to start/stop AF dosing pumps at what dosage rate etc.)

[Evan HydeKeymaster]

Bsudhakar, I could not agree more.

+ Down gauging the AF pump is important to really know your dosage.
+ Measuring Si in Naphtha and LCGO is important. >20 ppm could cause downstream catalyst issues.
+ Consider injecting only carrier early in the foam observation, then switch to carrier+AF later in the cycle
+ Use continuous level (if you have them) to optimize dosage timing.

[Claudio CarmonaParticipant]

Bsudhakar,

As Evan mentioned, it is strictly necessary to know the curve of your AF injection pump and to monitore SI concentration in Nafta and LCGO. With all those measurements we discovered several years ago that we had AF carryover at the top of the drum. So, we changed the injection configuration and we drastically optimized AF dosage.

[Hedewandro LucrediParticipant]

Hi Evan
What do you mean when you refer to this rule of thumb ? Is it 1 lb/1000 bbl of the comercial NALCO EC 9019A product or the PDMS that it contains ? And this rule applies perfectly to the 100.000 cST or what ? Thank you

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