Q&A

(2015) Question 63: What type of facilities have you used to cool hot vacuum residue going to storage to avoid plugging problems and facilitate reprocessing?

I am going to focus on the system we have and also some of the issues we have experienced. The majority of our resid that is produced off the crude unit vacuum towers is sent through the hot resid system straight to the cokers. We have two crude unit trains.

(2015) Question 64: What are acceptable makeup water streams that can be used for coke cutting which will not affect the coke quality?

With regard to coke quality, a lot of the available streams are acceptable. A few of the additional considerations to take into account are: Is this makeup water stream going to add overall load to my wastewater treatment facility? Is this new water? Is this water that I can recycle? Streams that are acceptable are: stripped sour water. If you are not reusing this water at your desalters or FCC wet gas scrubbers, then it would be an acceptable stream.

(2015) Question 65: Discuss operating conditions and economic drivers to produce maximum diesel from the coker.

When your margins indicate the need to pull more diesel, you have two options: You can check the top of your tower, or you can adjust overhead temperatures and fractionations to confirm that you are pushing the maximum amount of heavy naphtha down into the diesel.

(2015) Question 66: Concerning new regulations for lower coke drum pressure prior to opening, what changes will you make?

Amec Foster Wheeler has several designs that could be incorporated in existing units to meet the expected EPA mandate of depressurizing the drums to 2 psig or less prior to opening the vent. Options include adding an ejector or vent gas compressor to lower the drum pressure.

(2014) Question 56: How will the recently announced EPA requirement to depressure coke drums to below 2 Psig prior to venting to atmosphere regulations impact your coker operation and design?

In order to meet the potential requirement of less than 2 psig prior to atmospheric venting, new units designed to operate at low coke drum pressure will require additional equipment such as an ejector system discharging to a condenser (potentially the blowdown or fractionator overhead condenser) to adequately reduce the coke drum pressure prior to atmospheric venting.

(2014) Question 57: If vacuum tower bottom feed to the Coker unit drops below unit minimum, what are your operating options available?

Increasing amount of tight oil production with hardly any residual fraction will lead to challenges in filling up the Delayed Coking Unit (DCU). In order to maintain the DCU capacity, external purchase of HFO or VR will have to be made.

(2014) Question 58: What are you using for velocity medium in coker heaters? Are you using boiler feed water?

If Condensate or BFW is used as velocity media or to clear the heater tubes during a heater trip, precautions must be taken as excess free water has the potential to overpressure the heater during a shut-in condition.

(2014) Question 59: What is your experience processing a crude oil that has been treated with a pour point depressant and/or wax dispersant agent?

Some laboratory simulation experience has demonstrated that there were no adverse impacts to processing crude oil treated with a certain pour point depressant relative to oil-water separation for desalting.

(2014) Question 60: How does the mercury in crude distribute in your refinery (e.g., what units are affected)? What operating procedures or technology are you using to mitigate this issue?

How does the mercury in crude distribute in your refinery (e.g., what units are affected)? What operating procedures or technology are you using to mitigate this issue?

(2014) Question 61: What measurement and/or predictive methods are you using to determine crude oil blend compatibility?

Various methods exist to determine blend compatibility; one method would be a comparative asphaltene instability point determination via an anti-solvent titration, or another method used is the Wiehe insolubility number to solubility blend number method.

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