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(2016) Question 33: Can you share your experience with chemical additives to prevent fouling in the naphtha hydrotreater feed side of the feed/effluent heat exchangers or resolve reactor pressure drop issues?

The answer is partially the same as the one given to Question 28. First, the root cause needs to be determined. If the dP is caused by corrosion products due to corrosion in the upstream refinery units, the corrosion in these units can be reduced by applying the proper corrosion control program.
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(2016) Question 34: The cycle life of a high-pressure ULSD unit operating for maximum aromatic saturation and liquid yield is limited by aromatics equilibrium at elevated temperatures. What strategies or solutions do you employ to extend operation with maximum liquid yield?

This question is more related to EOR conditions when you have employed all of the operational techniques but wish to further optimize the EOR performance without yield decline. If you are already maximizing H2 pp (partial pressure), achieving full catalyst utilization with state-of-the art reactor internals, and adjusting bed profiles at MOR/EOR (middle-of-run/end-of-run) to remain in region of optimum aromatic saturation, the following example illustrates the benefits of optimizing the nickel-molybdenum catalyst for your application.
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(2016) Question 18: The increased production of light straight-run (LSR) from crude units is likely to have an impact on refiners’plans for Tier 3 compliance. What strategies do you employ in order to manage this issue?

Tier 3 drives hydrotreating of essentially all light naphtha streams. Since most United States refineries have FCCs, it is usually desirable to hydrotreat other gasoline streams more completely to minimize the FCC naphtha olefin saturation and the associated octane loss
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(2016) Question 24: How do you manage reactor maldistribution once identified?

Reactor maldistribution is a phenomenon that is typically caused by inadequately designed or installed reactor internals, improperly/unevenly loaded catalyst bed, catalyst migration from an upstream bed, or process fouling. The main problems generated by flow maldistribution are the overuse of part of a catalyst inventory and the formation of hot spots, which can create a process safety risk, as well as limit the performance of the cycle.
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(2016) Question 25: For refinery complexes considering grassroots or brownfield expansion of gas oil conversion capacity, what are your typical capital expenditure (capex) costs and relative refinery margin improvement between FCC (fluid catalytic cracking) and hydrocracking? What are the key technology features that impact your economic decision? What are the crucial considerations that, if they include both technologies, to allow for future integration, especially around the changing gasoline/diese

In general, Marathon’s economic viewpoint is that hydrocrackers have better projected margins going forward than FCCUs, as they maximize higher valued ULSD over gasoline and have higher volume expansion (see Figure 1). This is driven by many factors mentioned in the primary response and is particularly attractive when ULSD is strong relative to gasoline and when natural gas or hydrogen) is inexpensive. Each company has a different viewpoint on this topic, so the opinion will vary somewhat across the industry.
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