The invention relates to a separator device for separating a first liquid substance from a second substance, the two substances forming a mixture. The apparatus comprises a vessel with an inlet for receiving the mixture, a first outlet for discharge of a first fraction of the mixture, a second outlet for discharge of a second fraction of the mixture and a flow element. The flow element comprises a number of parallel tubular channels defining a flow path for the mixture, the channels having an gilet end for receiving the mixture and an outlet end for discharge of the first fraction, a length direction of the channels being inclined with respect to a horizontal direction, wherein in a transverse cross section through the flow element, the channels form a two-dimensional array of closed cells, each cell defining a boundary of a flow channel, the cells being arranged in at least two rows, each cell in a first row contacting with its perimeter a cell in the second row. The device comprises a return duct from a first outlet to the inlet via a gas mixing device.