Abstract: A multiphase flow rate measurement device including a gas-liquid separator (100) that includes a container (10) having a top section (11), a bottom section (12) and a hollow body section (13), an inlet section (20) that is provided in the body section (13), a liquid outlet section (21) that is provided in the bottom section (12), a gas outlet section (22) that is provided in the top section (11), an inner pipe (30) that is connected to the top section (11), and a lower end of the inner pipe (30) being open at a position lower than a lower end of the inlet section (20), and a guide plate lower section (42) that is provided on an outer side surface of the inner pipe (30), a space (90) being formed in at least part of an area between a guide plate lower section (42) and the body section (13).

Abstract: A gas-liquid separator (1) is configured so that the inner side surface of a body section (13) and the outer side surface of an inner pipe (50) are concentric when viewed from above, an inlet pipe (20) extending toward the center axis of the body section (13) when viewed from above, a guide plate (60) including a guide plate side section (61) that extends in a non-horizontal direction, and a guide plate lower section (62) that extends in a non-vertical direction and is continuous with the guide plate side section (61), the guide plate side section (61) being at least disposed on the inner side surface of the body section (13) at a position on one side of an inlet opening (132), or on the outer side surface of the inner pipe (50) at a position on one side of an area opposite to the inlet opening (132), the guide plate lower section (62) being at least disposed on the outer side surface of the inner pipe (50) at a position directly under an area opposite to the inlet opening (132) and along the outer side surfa