Compressor

A compressor, comprising:

• a rotor including a rotor shaft rotatable around an axis and a compression unit that rotates integrally with the rotor shaft and compresses fluid;
• a casing for covering the rotor from an outer side in a radial direction with the axis as a center;
• a sealing mechanism for sealing an annular space formed between the rotor shaft and the casing with a sealing gas;
• a sealing gas supply line for supplying the sealing gas to the annular space;
• and
• a gas lead-out line for leading the sealing gas in the annular space to a suction port of the compression unit, wherein
• the sealing mechanism includes
• a first sealing portion,
• a second sealing portion disposed at an interval from the first sealing portion in an axial direction so as to be separated from the compression unit, and
• a third sealing portion disposed at an interval from the second sealing portion on a side opposite to the first sealing portion in the axial direction,
• the second sealing portion has a sealing property stronger than that of either the first sealing portion or the third sealing portion, and includes a carbon ring seal disposed on the outer side in the radial direction with respect to the rotor shaft and extending in a circumferential direction around the axis,
• the second sealing portion divides the annular space into a high-pressure space close to the first sealing portion in the axial direction with respect to the second sealing portion and a low-pressure space close to the third sealing portion in the axial direction with respect to the second sealing portion and having a pressure lower than that of the high-pressure space between the first sealing portion and the third sealing portion, and
• the gas lead-out line connects the high-pressure space and a suction port of the compression unit having a pressure lower than that of the low-pressure space to each other.