Dear All, am working as operations engineer of an atmospheric distillation unit. Recently, the water content of light and heavy gasoil coming out from their respective coalescer drums gave a value of 0.1% for a maximum value of 0.05%. I reduced the stripping ratios of the 02 gas oils by half but I still obtained the same results. I sampled the light and heavy gas oils before and after their various coalescer drums and found out that the water content before and after the drum was 0.1%. I would like to know if this can be as a result of dysfunctionning of the coalescer mesh in the drum.
( The flow meter of stripping steam has been checked, the temperature of coalsecer drums are ok, around 35°C,).
Also I would like to state that even though the stripping ratios of light and heavy gasoils are the same, 20kg/t, the appendix of the drum of light gasoils fills up every 24 hours with water. This water is rapidly evacuated by the on-ff valve while that of heavy gas oil takes about 10 days to fill up. ( Draw temperature of Heavy gas oil, 330°C and that of light gas oil is 270°C, the temperature difference between the draw temperature and the bottom temperature of the 02 stripping columns is 15°C, temperature of stripping steam 380°C and 4 barg pressure, pressure of coalescer drums 2.1barg).