Abstract: In the past, it has proven difficult to separate dirt and water from petroleum emulsions of the type found, e.g. in settling ponds. A relatively simple apparatus for effecting such separation includes a sifter or screening device for removing large solid impurities from the emulsion, a preheater for reducing the viscosity of the emulsion, a centrifuge or filter for separating most of the dirt particles from the emulsion, a settling tank for receiving the emulsion from the dirt separator, and an evaporator for separating most of the water from the petroleum. The dirt removed in the dirt separator with residual oil attached thereto is mixed with a fuel oil and burned to create the heat necessary to evaporate the water. The petroleum separated in the evaporator is cycled through the preheater for heating incoming dirty petroleum emulsion. The evaporator contains trays carrying a plurality of rows of tubes. The water-containing emulsion is fed into the uppermost tray into heat exchange contact with the tubes.