Cyclone separator for separating a mixture containing solid particles, liquid and/or gas into a heavy fraction and a light fraction, the cyclone separator comprising: - an inner casing defining a flow space through which the mixture is to flow, the inner casing having an inlet for the mixture to be separated and an outlet for the discharge of either the heavy or light fraction of the mixture; - an elongated flow body arranged in the flow space along which the mixture to be separated can be carried; - at least one swirl-inducing element (31,32) arranged between the elongated flow body and the inner casing, the at least one swirl-inducing element being curved so as to set the incoming mixture into a rotating movement for the purpose of separating the mixture into the heavy fraction and the light fraction; - at least one first flow passage defined inside said at least one swirl-inducing element, the at least one first flow passage preferably comprising at least one enclosed flow channel adapted to permit flow between the inside of the elongated flow body and the outside of the inner casing; - a second flow passage defined inside the flow body and connecting to the at least one first flow passage in the at least one swirl-inducing element; - an outer casing arranged around the inner casing, the outer and inner casing defining a third flow passage connected to the at least one first flow passage; and - discharge means for discharging the separated heavy and light fraction, the discharge means comprising the at least one first flow passage, the second flow passage, the third flow passage, and one or more openings in the elongated flow body, wherein the openings connect to the second flow passage inside the elongated flow body, so as to discharge the separated light fraction from the cyclone separator via a flow path sequentially comprising at least the openings, the second flow passage, the at least one flow passage and the third flow passage, respectively, wherein the elongated flow body has a converging portion at the downstream end thereof and the openings are arranged at the position of the converging portion. - an inner casing defining a flow space through which the mixture is to flow, the inner casing having an inlet for the mixture to be separated and an outlet for the discharge of either the heavy or light fraction of the mixture; - an elongated flow body arranged in the flow space along which the mixture to be separated can be carried; - at least one swirl-inducing element (31,32) arranged between the elongated flow body and the inner casing, the at least one swirl-inducing element being curved so as to set the incoming mixture into a rotating movement for the purpose of separating the mixture into the heavy fraction and the light fraction; - at least one first flow passage defined inside said at least one swirl-inducing element, the at least one first flow passage preferably comprising at least one enclosed flow channel adapted to permit flow between the inside of the elongated flow body and the outside of the inner casing; - a second flow passage defined inside the flow body and connecting to the at least one first flow passage in the at least one swirl-inducing element; - an outer casing arranged around the inner casing, the outer and inner casing defining a third flow passage connected to the at least one first flow passage; and - discharge means for discharging the separated heavy and light fraction, the discharge means comprising the at least one first flow passage, the second flow passage, the third flow passage, and one or more openings in the elongated flow body, wherein the openings connect to the second flow passage inside the elongated flow body, so as to discharge the separated light fraction from the cyclone separator via a flow path sequentially comprising at least the openings, the second flow passage, the at least one flow passage and the third flow passage, respectively,