Q&A

(2018) Question 47: Are there any operational parameters that can be manipulated to improve the operation of the slurry circuit and minimize fouling? Can you outline the slurry exchanger circuit recommended design practices to minimize fouling, plugging and erosion?

Temperature: From experience, the rate of coke build-up increases greatly when the bottoms temperature is > 700F (370°C). It is recommended to maintain the bottoms temperature below 680°F (360°C) to be on the safe side.

(2018) Question 49: As the demand for higher octane gasoline components increases and lobbying for a 95 RON gasoline standard continues, how are you adjusting your operations to meet the market demand? What FCC specific changes do you make to produce higher octane gasoline components?

Refiners are optimizing their gasoline blend components to maximize high octane components. Alkylate and reformate yields are becoming increasingly important, as well as minimizing low octane component yields. The emergence of tight oil feeds has created an increase in low octane natural gasoline and LPG saturate production.

(2018) Question 50: Butylene demand and prices in relation to other refined products reached a record level in 2017. What caused it and what can we do in the FCC to produce more butylenes?

Higher demand for butylene is result of octane shortage in the gasoline market stemming from several main causes.

(2018) Question 51: For advanced (closed) riser termination systems, where does coke form inside the reactor vessel? What is the typical amount accumulated during a run?

The quantity of coke is heavily dependent on reactor technology, feed quality, and operating conditions. In earlier termination devices the riser outlet was open to the reactor. The vapors would spend a lot of time in the reactor resulting in coking.

(2018) Question 53: In the Third Stage Separator (TSS), what is the expected life of swirl tubes or cyclones assuming good performing regenerator cyclones? Of these two types, which handle upsets/ variable particulate loadings better?

The performance of swirl tubes is comparable with cyclones in terms of separation efficiency. Swirl tubes have distinct advantages over cyclones in being more compact, much easier to construct and have high mechanical integrity.

(2018) Question 55: With new challenges presented by the Refinery Sector and Maintenance Venting Rules oil circuits are taking longer to prepare for maintenance; what successes and challenges have you had in staging shutdown operations to allow for safe entry to the FCC reactor/regenerator section prior to clearing other sections of the unit?

With new challenges presented by the Refinery Sector and Maintenance Venting Rules oil circuits are taking longer to prepare for maintenance; what successes and challenges have you had in staging shutdown operations to allow for safe entry to the FCC reactor/regenerator section prior to clearing other sections of the unit?

(2018) Question 56: Excluding nickel passivation. How does antimony use in the reactor riser impact the FCC operations and equipment?

Antimony functions by attaching to a fresh Nickel molecule in the FCC feed and preventing it from laying down on the surface of the catalyst. Efficiency of antimony in passivating Nickel and tendency to have side effects is highly dependent on the carrier and distribution method. Antimony can be water based or oil based, with oil-based antimony having a higher lay down efficiency (approx. 85% typical) as compared to water based (approx. 65%).

(2018) Question 57: How are you optimizing the use of wet gas scrubbers caustic use and SOx additives?

You can utilize a SOx additive in addition to a Wet Gas Scrubber system in order to reduce caustic consumption and minimize cost. Utilizing a SOx additive can be optimized by calculating the caustic savings + value of additional liquid sulfur produced - the cost of the Sox additive.

(2010) Question 34: What has been the experience of refiners operating selective hydrotreating of FCC naphtha regarding gum formation potential of the low sulfur gasoline? Is gum inhibitor addition a recommended practice?

Gum potential exists with unsaturated hydrocarbons (olefins or diolefins) stored in refinery operations with oxygen as a free radical. Organic sulfur and nitrogen compounds remaining in FCC gasoline product can form gums in the presence of olefins and oxygen.

(2010) Question 47: What are the best practices for corrosion probe selection, installation and reliability, especially in high temperature and/or high H2S environments?

Some things to consider when selecting and installing corrosion probes are to match the metallurgy of the probe to the pipe.

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