Dispersants for FCC Fractionators

Chloride Salt Control (CSC) is a patented, high-base strength chemistry that removes and prevents NH4Cl salt formation. The following case history demonstrates the numerous benefits this technology offers refiners.

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Challenge

Fluid Catalytic Cracking (FCC) fractionators are commonly susceptible to ammonium chloride (NH4Cl) salt formation. Due to the high concentration of ammonia and chloride in an FCC fractionator, the NH4Cl salt point is often above the overhead temperature or the reflux temperature, placing the tower at risk for salt fouling and corrosion. This can have a negative impact on fractionation, pressure drop, and overall reliability.

Solution

The Chloride Salt Control (CSC) technology is a patented, high-base strength chemistry that removes and prevents NH4Cl salt formation. In salt removal applications, the CSC replaces the ammonia or other weak bases in the existing deposits to form its own salt. In salt prevention, the CSC acts as a chloride scavenger that selectively forms a salt with the chloride in place of any weaker bases. The salt resulting from the CSC technology has multiple advantages, specifically excellent mobility and low corrosivity. It is easily removed from equipment, alleviating fractionation or pressure drop issues, and also mitigates corrosion risk.

Tower Cleaning Case

CSC technology can be used as an IMG FCCU Graph 1016.fw extendedeffective means to clean salt deposits from an FCC fractionator, as found by one refinery that was limited by pressure drop issues in the tower. The pressure drop was assumed to be due to NH4Cl salts, so a short-term cleaning with the CSC technology was implemented. Within the first 48 hours of the cleaning, the pressure drop was reduced significantly, indicating a quick response to the CSC technology. The adjacent graph illustrates this improvement .

Continuous Feed Case

Another refiner found success using the CSC technology as a continuous application to prevent NH4Cl salt formation. Prior to injecting the CSC, the refiner found their trays plugged and damaged by NH4Cl salts.

Continuous application of CSC at a maintenance dosage occurred after the turnaround. After one year, the refiner opened the tower to inspect the trays and found negligible deposits and corrosion. The images present the condition of the trays before and after the CSC application and show the benefits.

CSC-Before-and-After.png

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