Patent ID: 7827869

Claim:
A multi-phase flowmeter comprising: a gas-liquid two-phase flow rate measurement portion for measuring an each-phase flow rate of a gas-liquid two-phase flow in a three-phase flow consisting of gas and two kinds of liquid; a mixture liquid density measurement portion for measuring a mixture density of mixture liquid as a liquid phase of the gas-liquid two-phase flow; and an each-phase flow rate calculating portion which obtains a mixing ratio of the mixture liquid from the mixture density and which calculates each flow rate of the mixture liquid from the mixing ratio and the mixture liquid flow rate, wherein the mixture liquid density measurement portion includes a mixture liquid extraction portion and a density measurement portion connected to the mixture liquid extraction portion, wherein the mixture liquid extraction portion includes a pressure difference generator provided in a pipe line through which the three-phase flow is passed, a pair of communication pipes connected to upstream and downstream sides of the pressure difference generator, a gas-liquid extraction tank which serves as a place connected to the pair of communication pipes and adapted to take in a part of the three-phase flow and which serves as a place utilizing a change in pressure between input and output sides of the pressure difference generator to forcibly agitate the part of the three-phase flow, a gas-liquid discharge pipe connected to the gas-liquid extraction tank and adapted to discharge gas including the liquid phase, a liquid storage tank connected to the gas-liquid extraction tank and adapted to take in at least the mixture liquid for density measurement required at the density measurement portion and to store the same, and a liquid flow rate adjustment valve provided at least on a downstream side of the liquid storage tank, and wherein the density measurement portion includes a density measurement portion main body adapted to perform density measurement by using the mixture liquid for density measurement, and a gas-liquid return pipe connected to the density measurement portion main body and the pipe line.