Q&A

(2018) Question 1: What are the benefits of alumina treating in sulfuric acid alkylation and HF alkylation? Has this technology been proven commercially?

In the sulfuric acid alkylation process, droplets of acid are found in the effluent stream from the reactor. These droplets, which are formed primarily from the alkylation chemistry itself and the formation of intermediates, are small and stable and cannot be removed by gravity settling and / or coalescing alone.

(2018) Question 2: What metallurgy works well and does not work well for use in alkylation units? In what applications does the alternate metallurgy perform better/worse?

The standard metallurgy for use throughout HF alkylation units is carbon steel. Showing a high degree of corrosion resistance in both low and very high acid concentrations, carbon steel is also useful for its relatively low cost compared to more exotic materials.

(2018) Question 3: What type of release mitigation safety systems do you use for sulfuric acid and HF alkylation units?

Sulfuric acid alkylation units do not require the robust safety systems as the HF Alky units since sulfuric acid is a liquid at atmospheric conditions. The release mitigation safety systems typically used are curbed and/or diked areas to contain the liquid sulfuric acid in event of a leak.

(2018) Question 52: What are your best practices for wet flue gas scrubber water supply and system monitoring (sampling frequency, instrumentation verification, etc.)? How do you handle the effluent water and any new emerging trends?

Water supply should be managed depending on the system design. The water source used by Motiva is clarified water. Due to the stainless-steel material and the chloride concentration in both the water and the caustic for neutralization the inlet duct temperature is monitored and controlled to prevent Chloride Stress Corrosion Cracking.

(2010) Question 28: The Clean Air Act required refineries to develop and implement a Leak Detection and Repair (LDAR) program to control fugitive emissions. What is the current status of this implementation and who is responsible for it in a typical refinery management structure: production, maintenance or EHS?

Since the inception of the Clean Air Act of 1955 and multiple amendments through 1990, Leak Detection and Repair or LDAR regulations have been a part of air pollution control. Today’s LDAR programs are governed by Federal and State regulations and agreed orders (consent decrees) that provide the control of fugitive emission leaks from process equipment by requiring equipment inspections and leaking equipment repair.

(2010) Question 29: What technologies do you use for treating or recovering VOCs from small-scale truck loading terminals? Discuss the merits associated with each?

The three main VOC treating systems for small scale truck loading are vapor combustion system, flare gas recovery unit, and an adsorption/absorption vapor recovery system.

(2010) Question 30: What process parameters can affect alkylate T90? What are the critical variables you monitor in both sulfuric and HF units? Discuss processing schemes, feed impacts and operating variables.

The type of feed is very significant for T90. Amylenes make alkylate with higher T90 in both sulfuric and HF units. Propylene generally makes lower T90 than butylene in HF units. However, with sulfuric-catalyzed technologies, propylene can increase T90 as discussed below.

(2010) Question 31: In your experience, when sampling the HF Alky iso-recycle stream, how and where is the sample neutralized prior to analysis? Can this approach be used for online GC analysis as well?

The isobutane recycle sample can be neutralized at the sample location using a chamber filled with alumina or KOH pellets. If using a KOH chamber, it is best to add a filter downstream to filter out any fines.

(2010) Question 32: In your experience, what contributes to Monel denickelification in the HF Acid Regenerator circuit? What are the potential problems associated with this?

Oxygen is a major cause of monel denickelfication. Oxygen can enter the circuit during loading operations. Care should be taken to avoid pressuring air contained within loading pipes/hoses into the unit.

(2010) Question 33: How do refiners avoid De-isobutanizer (DIB) column/reboiler fouling in sulfuric acid alkylation? What process conditions on the column do you use to detect this fouling? What process modifications do you take to minimize the impact of this fouling?

Fouling in the DIB column is almost always caused by salt deposits. These salts are typically sodium sulfate and sodium sulfite but can also contain calcium or magnesium if the effluent treating water is not demineralized. If these water-soluble salts are present in the DIB feed, the water will evaporate once inside the column leaving the solids behind.

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