A liquid separator for draining liquid from a moving black liquor slurry stream of liquid and solid material, such as wood chips, pins, and fines, in an in-line drainer of a pulping system, the liquid separator comprising: a cylindrical housing having an inlet proximate to a first end of the cylindrical housing, a first outlet proximate to a second end of the cylindrical housing, a second outlet proximate to the first end of the cylindrical housing, and an internal chamber between the inlet and first outlet, wherein the internal chamber extends along an axis of the cylindrical housing; a screen basket mounted in the internal chamber of the cylindrical housing, the screen basket formed of a plate having side edges which are joined to form a black liquor slurry stream flow chamber, wherein the inlet and first outlet of the cylindrical housing are in fluid communication with the black liquor slurry stream flow chamber; and a liquid collection chamber formed between an outer surface of the screen basket and an inner surface of the cylindrical housing, the second outlet on the cylindrical housing being in fluid communication with the liquid collection chamber; the screen basket including slots extending through the screen basket to provide liquid flow passages from the black liquor slurry stream flow chamber to the liquid collection chamber; said slots each having a length substantially greater than a width of the slot, the width of the slots being selected to retain solid particles of the moving black liquor slurry stream within the black liquor slurry stream flow chamber and block the solid particles from entering the liquid collection chamber, and the slots having a length dimension which forms an oblique angle with respect to the axis of the cylindrical housing, the oblique angle having a dimension of between about five degrees to ninety degrees, and the slots each having a corner edge adjacent to an inside surface of the screen basket facing the black liquor slurry stream flow chamber, characterized in that the corner edge of each slot is at least one of curved, rounded, chamfered, sloped or inclined, the slots are arranged in rows on the screen basket, the rows are separated by land areas of the screen basket, and the slots of any of the rows are uniform throughout the row in dimensions, orientation, and shape. a cylindrical housing having an inlet proximate to a first end of the cylindrical housing, a first outlet proximate to a second end of the cylindrical housing, a second outlet proximate to the first end of the cylindrical housing, and an internal chamber between the inlet and first outlet, wherein the internal chamber extends along an axis of the cylindrical housing; a screen basket mounted in the internal chamber of the cylindrical housing, the screen basket formed of a plate having side edges which are joined to form a black liquor slurry stream flow chamber, wherein the inlet and first outlet of the cylindrical housing are in fluid communication with the black liquor slurry stream flow chamber; and a liquid collection chamber formed between an outer surface of the screen basket and an inner surface of the cylindrical housing, the second outlet on the cylindrical housing being in fluid communication with the liquid collection chamber; the screen basket including slots extending through the screen basket to provide liquid flow passages from the black liquor slurry stream flow chamber to the liquid collection chamber; said slots each having a length substantially greater than a width of the slot, the width of the slots being selected to retain solid particles of the moving black liquor slurry stream within the black liquor slurry stream flow chamber and block the solid particles from entering the liquid collection chamber, and the slots having a length dimension which forms an oblique angle with respect to the axis of the cylindrical housing, the oblique angle having a dimension of between about five degrees to ninety degrees, and the slots each having a corner edge adjacent to an inside surface of the screen basket facing the black liquor slurry stream flow chamber, characterized in that the corner edge of each slot is at least one of curved, rounded, chamfered, sloped or inclined, the slots are arranged in rows on the screen basket, the rows are separated by land areas of the screen basket, and the slots of any of the rows are uniform throughout the row in dimensions, orientation, and shape.