A Theoretical Approach to Determining Flue Gas Acid Dew Point in a Crude Oil Refinery Distillation Unit Furnace

Acid dew point is a crucial factor in determining the low-temperature corrosion rate and the thermal efficiency of downstream process equipment such as stacks in a crude oil refinery. This research was conducted to determine the flue gas acid dew point of a furnace used to pre-heat the input of a crude distillation unit in a refinery. The furnace uses combination of fuel oil and fuel gas sourced from the refinery with a known elemental composition. Three scenarios were analyzed; fired from fuel oil, from fuel gas, and a combination of both. The third scenario is based on a day of which the feed rate of the unit was 5350 tons/day. Using the fundamental analysis of combustion chemistry and two methods of A.G. Okkes’ and Verhoff and Banchero’s, the theoretical acid dew point in each scenario was determined. It was 150.52 and 155.00°C in the latter scenario. The flue gas temperature was measured as 183°C. Hence, it was determined that the acid dew point was below the flue gas temperature. The determined results can be used as a benchmark to mitigate low-temperature corrosion in downstream equipment and to evaluate further thermal recovery if needed.