Oval Corporation

Norio Sukemura

Yuichi Nakao

Seiji Kobayashi

Hirokazu Kitami

Yasushi Ito

Yutaka Ogawa

Shingo Gomi

Katsuichi Uchida

Takeshi Motomiya

Provided is a Coriolis flowmeter capable of achieving suppression of a pressure loss of a manifold and the like. A channel () of a manifold () includes a pipe-side opening portion (), tube-side opening portions (), and a channel branching portion () as shaping portions therefor, and the channel sectional area in a range of from the channel branching portion () toward the tube-side opening portions () is linearly decreased. A branching wall tip end () of a branching wall () extending from a position of the channel branching portion () to the other end of a manifold body () is arranged at the channel branching portion (). The sectional shape of the channel () is a circular shape at a position of the pipe-side opening portion (), and is changed to D-shapes at the position of the channel branching portion () by the branching wall tip end ().

Coriolis flowmeter having a cross-sectional area of channels of the manifolds enabling a reduction in pressure loss

A first inlet portion, a second inlet portion, a first outlet portion, and a second outlet portion are fixed to a fixing member, and a connecting tube portion is provided between the first outlet portion and the second inlet portion. Further, the first inlet portion and the second inlet portionare arranged in a non-parallel state such that the distance between the two increases as they depart from the fixing member. The first outlet portion and the second outlet portion are similarly arranged in a non-parallel state, the first inlet portion and the second inlet portion and the first outlet portion and the second outlet portion being arranged symmetrically. Further, the first outlet portion, the second inlet portion, and the connecting tube portion are arranged such that their three tube axes are in a straight line.

Coriolis flowmeter having a fixing member with non-parallel inlet and outlet portions

In order that a flow tube of a Coriolis flowmeter may be vibrated in a tertiary mode using one drive device, the drive device is arranged at an antinode in the center of tertiary mode vibration, and vibration detecting sensors are arranged at two antinodes other than the antinode in the center of tertiary mode vibration. Moreover, the displacement polarity of the drive device is opposite to that of the vibration detecting sensors so that the vibration phases of the flow tube are in a relation of mutually opposite phases. Furthermore, in a positive feedback loop of an excitation circuit portion for exciting tertiary mode vibration of the flow tube and the vibration detecting sensors , the excitation circuit portion is structured so that the relation between the displacement polarities where the vibration phases of the flow tube are opposite to one another is converted to the relation where the vibration phases of the flow tube are in phase.

Tertiary mode vibration type Coriolis flowmeter

A first inlet portion, a second inlet portion, a first outlet portion, and a second outlet portion are fixed to a fixing member, and a connecting tube portion is provided between the first outlet portion and the second inlet portion. Further, the first inlet portion and the second inlet portion are fixed so as to be in a non-parallel state such that the distance between the two increases as they depart from the fixing member, and the first outlet portion and the second outlet portion are similarly arranged in a non-parallel state. The first and second inlet portions and the first and second outlet portions are fixed so as to be arranged symmetrically. Further, the first outlet portion, the second inlet portion, and the connecting tube portion are arranged such that their tube axes are in a straight line. Further, the distance between driven portions is made small.

Coriolis flowmeter

Two flow tubes and of a Coriolis mass flow meter are formed into an arch shape, with the tubes bent in only one direction. Entry-side and exit-side manifolds are smoothly bent from the inlet of the entry-side manifold and the outlet of the exit-side manifold to joints connecting the two flow tubes to the manifolds, and connected to the flow tubes and at the joints at a predetermined angle in the same direction. By making the flow tubes into a parallel arched tube structure having good stress distribution and shock resistance, effects on the flow meter of external oscillations, installation conditions, piping stresses and thermal stresses can be reduced.

Coriolis mass flow meter

Each of two flow tubes assumes an arcuate shape consisting of a central arcuate segment and two linear segments located on opposite sides of the central arcuate segment. The inside diameter of the flow tubes and the linear distance between end points of each of the flow tubes are determined on the basis of a target pressure loss arising from passage of a fluid to be measured through a manifold and the flow tube at the maximum flow rate, a target time phase difference between sine wave outputs from vibration sensors at the maximum flow rate, and a target natural frequency of the flow tubes. The length of the linear segments is selected so as to reduce thermal stress induced from an abrupt change in the temperature of the fluid to be measured, and the shape of the flow tubes is determined so as to reduce the vertical height of the flow tubes, so long as the thermal stress is substantially constant even when the length of the linear segments is varied. Thus, the shape of the flow tubes is determined in such a manner as to suppress, to a predetermined low value, stress arising upon abrupt change in the temperature of the fluid to be measured and as to be most compact.

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Tokyo, Japan

Norio Sukemura