PTQ Q1 2023 Issue

260

y = -0.0295x + 1558.4

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y = 0.0082x – 117.63

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NFIT Dorf Ketal period

Baseline NFIT

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Figure 7 Furnace inlet temperature vs time

time. It shows the impact of the EB and RAC desalting programme. During the baseline period, the average reduc- tion in furnace temperature was about 1°C per month. The Dorf Ketal programme eliminated the loss of temperature. The improvement translated to energy savings of approxi- mately $300,000 per year. Field data case history 3: Amine/ammonia removal The final case history demonstrates the ability of RAC to improve amine, ammonia, and salt removal to reduce salt- ing in the overhead. Reactive adjunct improves amine and ammonia removal through two mechanisms: 1) improved extraction of water-soluble contaminants, and 2) the chem- ical reaction between aldehydes and amines to form water- soluble imines. The mechanism of improved extraction efficiency is as demonstrated in Case histories 1 and 2. The synergy between the EB and RAC improves the speed of emulsion breaking in the oil phase and resolves in-situ the emulsion at the boundary layer. The combination of these effects

allows for increased mixing and more efficient mass trans - fer of water-soluble salts, amines, and ammonia into the water phase. Additionally, it is well known that aldehydes react with amines, as shown in Equation 1. The imine formed is water soluble and exits in the brine. The reduced concentration of amines reduces the partitioning of amines into the oil phase, and the conversion of amines to imines reduces the extent to which the amines increase brine pH.

R R’ C NR’’

R R’ C Aldehyde

R’’ NH

(Eq. 1)

Amine

Imine

The two mechanisms – improved extraction efficiency and amine-to-imine conversion – were evident in a refinery processing crude contaminated with ammonia and amines, causing salting in the second drum. The critical monitoring parameters were ammonia in the second drum boot, and the delta between dew point and ammonia salt point. With

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RAC Prog r am me

Dew point

Ammonia salting point

Figure 8a Salting in second drum due to crude contaminated with ammonia and amines: dew point vs ammonia salting point

PTQ Q1 2023