Q&A

(2016) Question 6: What is your experience with having a vent depropanizer off-gas unit in order to manage tower pressure, and what might be the cause of and solution to the problem?

The typical and probably most obvious driver for the need to vent from a depropanizer column is the presence of non-condensable gases. Most commonly, this is ethane and ethylene that come in with the feed.

(2016) Question 7: How is propane content in the refrigeration loop optimized against the compressor capacity to minimize contractor temperature? Do you have a good process model to predict the optimum propane content?

There is an optimum propane concentration in the refrigerant that will allow the alkylation unit to operate at a maximum alkylate throughput when the unit is up against limitations of both the compressor and the reaction zone heat removal capability. That optimum concentration of propane will vary from unit to unit and can be different seasonally. It can also be different from night to day or if exchangers are fouled, etc.

(2016) Question 38: What do you see for the future of ebullated bed technology considering changes in crude quality and availability?

With the worldwide requirement for higher conversion of residue into lighter, more valuable transportation fuels such as diesel remaining firmly in place, we very much see ebullated-bed (EB) residue hydrocracking building on its current trend as a bottom-of-the-barrel upgrading technology of choice going forward. Investment in this commercially proven, well-established technology is a way to increase complexity and ensure long-term survival in an increasingly volatile marketplace.

(2016) Question 39: Please summarize the current status of slurry hydrocracking technology commercialization.

Slurry hydrocracking technology has been commercialized in China (VCC) and Italy (EST) in the past two to three years. Both facilities have demonstrated expected performance, including conversion and selectivity. The reliability of slurry hydrocracking is still an open question as these units have only been in operation for a short time. Additional VCC commercial units are scheduled for startup in the next 12 months.

(2016) Question 41: What are the considerations you use for extending hydrogen plant catalyst life cycles (i.e., lower production rates, furnace tube failure, etc.)?

There are many parameters affecting the hydrogen plant catalyst life cycles, such as lower production rates, furnace tube failure, unplanned plant shutdowns, larger catalyst volumes, elevated energy consumption, and finite ZnO/S (zinc oxide/sulfur) capacity. Lower Production Rates will obviously result in longer catalyst lifetime due to a lower gas velocity over the catalyst.

(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.

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