PTQ Q4 2026 Issue

Likewise, recurring failures were reported in rotating equipment, particularly in mechanical seals of pumping systems, as well as risks asso- ciated with the performance of the wet gas compressor, demonstrating that the issue extended beyond the fraction- ation system and affected the unit’s overall reliability. From an operational standpoint, controlling the phenomenon involved the implementation of recurring

0.4 0.5 0.6 0.7 0.8 1 0.9 1.1

1.06

1.05 1.06

1.03 1.00

0.95 0.94

0.83

0.80

0.78

0.76 0.74

0.75

0.69 0.68 0.70 0.71

0.63

Month

Figure 2 Fractionator overhead differential pressure

corrective measures. Among them were online washing of the overhead system, increasing the operating temperature to move conditions away from the dew point, and injecting salt dispersants. However, these actions proved insufficient to eliminate the recurrence of the problem, only temporarily mit- igating its effects. As a result, the unit operated under restric- tions, including limitations on the processed feed, increased operating costs, and a higher frequency of interventions. Operational comparison of the FCC unit For this analysis, two distinct operating periods were con- sidered, in which the impact of salt formation, specifically NH₄Cl, on the operation of the main fractionator and the quality of light naphtha was evaluated. Since 2019, the unit has recurrently presented problems associated with the formation and accumulation of salts in the fractionator overhead system. Starting in November 2021, coinciding with the change of catalyst supplier, a pro- gressive reduction in the differential pressure in the upper section of the fractionator began to be observed, as shown in Figure 2 . This behaviour marked a turning point in the unit’s operation, as the decrease in ΔP occurred steadily, without the need for additional operational interventions. Consistent with this evolution, since December 2021 it was no longer necessary to continue injecting salt disper- sants or to carry out washes in the fractionator overhead system, representing a significant change from the behav - iour observed in previous years. This operational change, not associated with relevant modifications in the feed or operating conditions, prompted a more detailed analysis of the system, aimed at identifying possible variations in the chloride balance. In this context, the hypothesis of a possible contribution of the catalyst as a source of chlorinated species in the system was proposed. Based on this observation, the comparison between two operational periods was defined: a first period characterised by the recurrent presence of deposits in the fractionator overhead system, and a second period in which the phenom- enon ceased to occur, allowing the observed changes in the unit’s performance to be assessed comparatively. Chloride balance analysis Chlorides measurements in the acid water streams dur - ing both periods clearly show the impact of the system’s

Chloride balance of the unit

Balance of Cl (NH₄)

Period 1

Period 2

Feed, kg/d

13.2 27.2 15.4

7.9 8.7 0.8

Sour, water kg/d

Delta, kg/d

Table 1

behaviour on salt formation, accumulation, and removal. During the first period, a higher presence of chlorides in the feed is observed compared to the second period (see Table 1 ). However, the main difference is evident in the chloride output through the sour waters, which is significantly higher than the input from the feed. This imbalance indicates the existence of an additional source of chlorides in the system, as well as a dynamic behaviour characterised by the accumulation of salts in the fractionator and their subsequent release into the process streams. This period coincides with the operation of the unit using a catalyst formulated with a chloride-contain- ing binder, which incorporates chloride-based compounds in its technology. Under unit conditions, these compounds can release chlorinated species into the system, contribut- ing to an increase in the chloride inventory beyond what is expected solely from the feed quality. In contrast, during the second period, there is an almost direct correspondence between the chlorides present in the feed and those removed through the acid waters. The low delta value indicates a system without significant salt accu - mulation, with a chloride balance close to closure and stable operation. This behaviour is consistent with the elimination of the need for corrective actions, since from the end of 2021 it was no longer necessary to carry out washes in the fractionator overhead or maintain salt dispersant injection, demonstrat- ing a sustained deposit-free operating condition. Impact on light naphtha quality The performance of the fractionation system was directly reflected in the quality of the light naphtha stream (see Table 2 ). During the first period, an atypical distribution of sulphur compounds is evident, with a significant fraction of sulphur present above the final boiling point (FBP). This behaviour

PTQ Q4 2026