Q&A

(2011) Question 53: Asphaltenes are known to destabilize at higher crude preheat temperature. Are there guidelines that can be used to determine the maximum allowable desalter operating temperature before the asphaltenes begin to drop out of solution and come out in the desalter brine?

We have worked with several refining organizations that process heavy Canadian crude oils to find the optimum desalter operating temperature. In general, raising temperature reduces the crude oil viscosity, which is desirable from a Stokes’ Law stand point as it makes breaking the emulsion easier.

(2011) Question 54: Please discuss the pros and cons of the various forms of desalter level indicator technologies

Please discuss the pros and cons of the various forms of desalter level indicator technologies.

(2011) Question 55: Many refiners complain of fouling, plugging, and corrosion problems in the effluent water exchangers downstream of their desalters. What modifications have you made to mitigate these problems?

On some occasions more frequent, or continuous mudwash may help dilute effluent water, thus reducing high concentrations of solids slugging the effluent water exchangers during the mudwash cycle.

(2011) Question 56: What experience do you have using lower pH wash water at desalters to minimize amine in treated crude?

What experience do you have using lower pH wash water at desalters to minimize amine in treated crude?

(2011) Question 57: What is your best practice and expected efficiency in removal of calcium napthanates in higher calcium crudes? Has anyone experienced severe fouling in downstream unit equipment (i.e., Vacuum Heater, Coker heater) when processing high calcium crudes? What are the concerns when processing resid containing high Calcium content?

We have extensive experience removing calcium and other metals from crude oils, with over 20 successful applications removing contaminants spanning the last 8 years.

(2011) Question 58: Some crudes contain fine particles which result in poor desalting and/or high sludge generation. How are you managing this? Are there specific strategies for treating desalter brine separately (ahead of the wastewater plant)?

Along the lines of Ron’s last point on secondary treatment of brine, some refineries have installed diversion tanks to receive the effluent water when the mud wash is being used.

(2011) Question 59: What are revamp best practices to minimize fouling in crude preheat trains? What services are typically the most difficult? What exchanger technologies have proven most successful?

What are revamp best practices to minimize fouling in crude preheat trains? What services are typically the most difficult? What exchanger technologies have proven most successful?

(2011) Question 60: Assuming good desalting, what are the common / best practices, control ranges and testing frequency of overhead boot water for chlorides - with and without caustic injection?

While general limits are assigned for overhead chloride levels, the reality is that these are simple rules of thumb and should not be relied on to provide satisfactory corrosion control for most systems.

(2011) Question 61: What test methods identify acids (other than HCl) in crude tower overhead water?

What test methods identify acids (other than HCl) in crude tower overhead water?

(2011) Question 62: What options do you use to manage or mitigate high carboxylic acids/TAN in jet/kerosene?

What options do you use to manage or mitigate high carboxylic acids/TAN in jet/kerosene?

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