Figure 4 Additive impact and comparison – second tray observation (second foulant collection location)
Suncor has conducted a preliminary analysis which shows that the foulant is consistent with polymeric coke. Even though the nano-additive is advertised as a high- temperature asphaltene dispersant, it was considered with two other additives to address the lighter hydrocarbon thermal fouling mechanism (also known as polymeric coke formation). The three additives considered are noted in Table 2, with some typical properties for reference. First-stage testing: evaluating impact of additives Replicating the proper operating conditions and allowing for residence time promoted the regeneration of foulant to better evaluate the impact of different additives. Iron shav- ings were added to accelerate fouling. The fouling gener- ated in the pilot unit was analysed as polymeric coke. During the testing of each additive, the injection rate of the
additive was maintained at 300 ppm with similar operating conditions. Testing indicated that all three additives prevented foulant generation and build-up on the top tray. However, on the second tray, the amount of foulant build-up differed across the additive samples, as seen in Figure 4 . Additive #1 (nano-additive) was the only one to exhibit no fouling, while additives #2 and #3 were better than no additive. In all cases, the largest foulant build-up occurred in the bottom of the vessel, as observed in Figure 5 . Again, addi- tive #1 exhibited the least amount of foulant, ~1g, although all the additives reduced foulant generation to a certain degree. For comparison, in Table 3, the mass of foulant mate- rial collected, the pressure differential across the distilla- tion tower, and the effectiveness in fouling reduction are provided for each additive. The comparative analysis of the
Figure 5 Additive impact and comparison – vessel bottom observation (third foulant collection location)
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PTQ Q2 2023
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