An apparatus (1) for conveying polyolefin particles, particularly foamed polyolefin particles, from a first location (L1) to a second location (L2), the apparatus (1) comprising: a pressurizing unit (2) for generating a pressurized particle conveying fluid stream, particularly comprising polyolefin particles in a pressurized fluid, the pressurized particle conveying fluid stream having a first pressure level; a decompressing unit (3) for decompressing the pressurized particle conveying fluid stream from the first pressure level to generate a decompressed particle conveying fluid stream having a second pressure level, wherein the decompressing unit (3) comprises: a first chamber (6) for receiving the pressurized particle conveying fluid stream and a second chamber (7) surrounding the first chamber (6), wherein the first chamber (6) is delimited by a first wall structure (6.1) and the second chamber (7) is delimited by a second wall structure (7.1); wherein the first wall structure comprises (6.1) at least one first opening (6.1.1) through which an inner volume of the first chamber (6) is connected with an inner volume of the second chamber (7) and the second wall structure (7.1) comprises at least one second opening (7.1) through which the inner volume of the second chamber (7) is connectable or connected with at least one dampening device (8).