Q&A

(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.

(2014) Question 62: What are the advantages and disadvantages to constructing “modular" refining process units versus traditional "stick built" units? What are the issues with each construction approach?

What are the advantages and disadvantages to constructing “modular" refining process units versus traditional "stick built" units? What are the issues with each construction approach?

(2014) Question 63: For the operating company, what are your crude unit typical run lengths between shutdowns? What factors do you consider when setting this run cycle?

For the operating company, what are your crude unit typical run lengths between shutdowns? What factors do you consider when setting this run cycle?

(2014) Question 64: Some crudes appear to have chlorides that are not readily removed in the desalter. What are sources for these un-desalted chlorides? How are the various un-desalted chlorides detected and mitigated?

The main source seems to be crystalline salt. A relatively new method to determine total chlorides is the Chlora instrument, desaltable chlorides can be determined by the extraction method, and the difference is taken as un-desaltable chlorides.

(2014) Question 65: What are the advantages and issues with different desalter wash water sources in a refinery? What issues do you experience by combining wash water from multiple sources?

The advantage is a reduction of freshwater use and sometimes a reduction in the load of contaminants(phenols) to the WTP. We have developed desalter washwater specs to prevent negative effects on desalter performance, fouling and corrosion. Oxygen, Ammonia, Hardness, TDS and Filterable are solids, the most obvious ones.

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