Q&A

(2018) Question 31: How does emulsion breaker performance compare when injected in the crude or wash water? What is your method to inject emulsion breaker for 2 stage desalters?

For the desalter system as a whole, the typical emulsion breaker is injected into the crude stream as far upstream as possible in order to provide intimate contact. In this case, the emulsion breaker is one that has a hydrocarbon solvent and so is hydrophilic which wants to stay in the oil phase. There are cases where injecting this emulsion breaker into the water phase can help reduce the impact of surfactants that surround the water droplets.

(2018) Question 32: Have you developed processes to successfully extract the emulsion layer from the desalter, so the emulsion can be treated separately? Please describe your chemical treatment programs and equipment that have been implemented successfully to treat this extracted emulsion.

Emulsion extraction headers, sometimes called cuff headers, have been an option and have been installed in desalters for decades. The removal of the emulsion layer solves one problem and creates another as this emulsion layer can be very difficult to treat.

(2018) Question 33: When processing cracked stocks in a crude unit, what potential issues do you expect? What changes in operations or treatment programs can you mitigate these issues?

If the site does not have a Delayed Coker, then reprocessing cracked stocks through the FCC fractionator is the next option. Again, this keeps the cracked materials separate from the straight run products.

(2018) Question 34: What is considered your practical limit on TAN (Total Acid Number) of blended crude diet before monitoring, treatment, or metallurgy upgrades should be considered to avoid naphthenic acid corrosion issues?

Understanding the mechanism of naphthenic acid corrosion, we model the hot circuits looking at the potential TAN of the stream, metallurgy and fluid velocity within the circuit. Once this has been done, we evaluate the options, if the corrosion potential is high enough.

(2018) Question 35: For deep cut vacuum tower designs what is your experience with heater coking and typical run lengths? Are you using on-line cleaning (like coker heater spalling)?

For a properly designed vacuum heater, it should be possible for the heater to last the entire run between cycle ending turnarounds without having to decoke the heater. This requires the heater to have been designed with the appropriate heat flux and mass flux rates.

(2018) Question 36: How do you manage the potential negative impacts of H2S Scavengers in imported coker feed?

How do you manage the potential negative impacts of H2S Scavengers in imported coker feed?

(2018) Question 37: Do you extend the time between de-coking the furnace by cutting coil outlet temperature or cutting furnace charge? How often are spallings done in coker furnaces? What is the temperature recovery after spalling?

Heater fouling is dependent on several variables that include the process film temperature, residence time at temperature and coke precursor concentration. I like to target a coke drum outlet temperature of 825°F before quench injection, which normally requires a Coker heater outlet temperature of 925°F.

(2018) Question 38: How does coke morphology vary with changes in feed quality? What feed tests do you require to quantify the impact on coke quality?

Predicting coke morphology from feed properties has not been 100% successful as the Coker operating conditions can make a difference if the feed is close to the shot coke vs. sponge coke threshold. The traditional approach uses the asphaltene content of the feed divided by the concarbon value of the feed.

(2018) Question 39: What operating conditions increase the generation of coke fines? What reliability issues do you associate with increased fines production?

Coke fine generation is really a function of the coke cutting process. Feed stock and coke drum operations during the actual drum fill cycle have very little to nothing to do with the generation of coke fines.

(2018) Question 40: What is your experience, design and opportunities for on-line crude blending coupled with near infra-red?

What is your experience, design and opportunities for on-line crude blending coupled with near infra-red?

Find the answer to your technical question in AFPM's extensive Q&A database.

Q&A