Ultrasonic flowmeter, method for operating an ultrasonic flowmeter, measuring system and method for operating a measuring system

Abstract

An ultrasonic flowmeter having a measuring tube, a control unit, at least one first ultrasonic measuring unit and a second ultrasonic measuring unit, the measuring tube having a measuring tube interior and a measuring tube longitudinal axis, wherein each of the ultrasonic measuring units is arranged on the measuring tube, wherein each ultrasonic measuring unit has a first ultrasonic transducer and a second ultrasonic transducer, the first and the second ultrasonic transducers spanning a sound measuring section with a sound axis. The sound measuring section and the sound axis penetrate the measuring tube interior for carrying out ultrasonic measurements. To provide an ultrasonic flowmeter for reliable measurement of a multi-phase medium, the sound axis of the first ultrasonic measuring unit and the sound axis of the second ultrasonic measuring unit span a sound measuring plane which extends substantially parallel to the longitudinal axis of the measuring tube.

Claims

1. A method for operating an ultrasonic flowmeter having a measuring tube, a control unit and at least one first ultrasonic measuring unit and a second ultrasonic measuring unit, wherein the measuring tube has a measuring tube interior and a measuring tube longitudinal axis, wherein each of the ultrasonic measuring units is arranged on the measuring tube, wherein each ultrasonic measuring unit comprises: a first ultrasonic transducer and a second ultrasonic transducer, wherein the first and the second ultrasonic transducers of each ultrasonic measuring unit span a sound measuring section with a sound axis, and wherein the sound measuring section and the sound axis penetrate the measuring tube interior, wherein the control unit is constructed for carrying out ultrasonic measurements with the ultrasonic measuring units, and wherein the sound axis of the first ultrasonic measuring unit and the sound axis of the second ultrasonic measuring unit span a sound measuring plane which extends substantially parallel to the longitudinal axis of the measuring tube, the method comprising: flowing a medium having at least one liquid and one gaseous phase through the measuring tube and assigning at least one of the first and second measuring units to measuring of the gaseous phase, determining a first sound velocity of a first measurement signal in said sound measuring plane at a sound measuring section of the first ultrasonic measuring unit, and if the first sound velocity is below a limiting sound velocity then the first sound velocity is assigned to the gaseous phase, determining a second sound velocity of a second measurement signal in said sound measuring plane at a sound measuring section of the second ultrasonic measuring unit, and if the second sound velocity is below the limiting sound velocity then the second sound velocity is assigned to the gaseous phase, determining a flow velocity of the gaseous phase from at least one sound velocity determined for the gaseous phase.

2. The ultrasonic flowmeter according to claim 1, wherein the sound axis of the first ultrasonic measuring unit and the sound axis of the second ultrasonic measuring unit cross one another.

3. The ultrasonic flowmeter according to claim 2, wherein the sound measuring plane is above the measuring tube longitudinal axis.

4. The method according to claim 1, wherein both sound velocities are assigned to the gaseous phase, and said flow velocity is determined from both of the sound velocities.

5. The method according to claim 1, further comprising, after carrying out said method a first time, wherein at least one sound velocity is assigned to the gaseous phase, performing said method a second time without assigning said the first and second sound velocity to the gaseous phase, and wherein a flow velocity of the gaseous phase is determined from the at least one sound velocity from the first time the method is carried out.

6. The method according to claim 5, wherein information about the flow is determined using at least one property of at least one of the first or the second measurement signal.

7. The method according to claim 1, wherein the presence of surges in the measuring tube is determined using at least one of the first or second sound velocity.

8. The method according to claim 1, wherein information about the composition of the gaseous phase is determined from the sound velocity of at least one of the first or the second measurement signal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a side view of first embodiment of an ultrasonic flowmeter according to the invention,

(2) FIG. 2 is a view of the first embodiment of an ultrasonic flowmeter according to the invention in cross section from above,

(3) FIG. 3 is a flow chart of a first embodiment of a method according to the invention for operating an ultrasonic flowmeter,

(4) FIG. 4 is a schematic first embodiment of a measuring system according to the invention,

(5) FIG. 5 is perspective view of a second embodiment of a measuring system and

(6) FIG. 6 is a flow chart of a first embodiment of a method according to the invention for operating a measuring system.

DETAILED DESCRIPTION OF THE DRAWINGS

(7) FIG. 1 shows a first embodiment of an ultrasonic flowmeter 1 with a measuring tube 5, with a control device 6 and with a first ultrasonic measuring unit 7 and with a second ultrasonic measuring unit 8.

(8) The measuring tube 5 has a measuring tube interior 9 and a measuring tube longitudinal axis 10, wherein the measuring tube longitudinal axis 10 runs through the center of the measuring tube cross section.

(9) The first ultrasonic measuring unit 7 has a first ultrasonic transducer 7a and a second ultrasonic transducer 7b, which is hidden in FIG. 1, but shown in FIG. 2. The second ultrasonic measuring unit 8 has a first ultrasonic transducer 8a and a second ultrasonic transducer 8b, which is also hidden in FIG. 1, but shown in FIG. 2. The arrangement of the four ultrasonic transducers 7a, 8a, 7b, 8b can be seen in FIG. 2.

(10) FIG. 1 further shows that the ultrasonic transducers 7a, 8a, are arranged above the measuring tube longitudinal axis 10 (the same being true for the ultrasonic transducers 7b, 8b which are on the same plane as can be seen from FIG. 2), so that the ultrasonic flowmeter shown is particularly suitable for the reliable detection or determination of the flow velocity of a gaseous phase of a multi-phase medium.

(11) FIG. 2 shows the first embodiment of the ultrasonic flowmeter 1 in which the first ultrasonic transducer 7a and the second ultrasonic transducer 7b of the first ultrasonic measuring unit 7 span a first sound measuring section 11 with a first sound axis 13. The first ultrasonic transducer 8a and the second ultrasonic transducer 8b of the second ultrasonic measuring unit 8 span a second sound measuring section 12 with a second sound axis 14.

(12) The sound axis 13 of the first ultrasonic measuring unit 7 and the sound axis 14 of the second ultrasonic measuring unit 8 together span a sound measuring plane 15, which, in the embodiment shown, runs parallel to the measuring tube longitudinal axis 10.

(13) In that the sound measurement plane 15 is aligned parallel to the longitudinal axis 10 of the measuring tube, it is ensured that the same phase, preferably the gaseous phase, is measured redundantly when measuring a multi-phase medium.

(14) FIG. 3 shows a first embodiment of a method 2 for operating an ultrasonic flowmeter 1.

(15) In a first step 16, a first sound velocity of a first measurement signal over the sound measuring section 11 of the first ultrasonic measuring unit 7 is determined and assigned to the gaseous phase if the first sound velocity is below a limiting sound velocity.

(16) In a second step 17, a second sound velocity of a second measurement signal over the sound measuring section 12 of the second ultrasonic measuring unit 8 is determined and assigned to the gaseous phase if the second sound velocity is below a limiting sound velocity.

(17) In a next step 18, if at least one of the sound velocities is assigned to the gaseous phase, a flow velocity of the gaseous phase is determined from the at least one sound velocity.

(18) The flow velocity or velocities is/are then output 19 via a display unit or an interface for further evaluation.

(19) FIG. 4 schematically shows a first embodiment of a measuring system 3 consisting of a multi-phase flowmeter 20 and an ultrasonic flowmeter 1, wherein the ultrasonic flowmeter 1 is arranged downstream of the multi-phase flowmeter 20 when viewed in the direction of flow.

(20) The multi-phase flowmeter 20 is connected to the ultrasonic flowmeter 1 via a, preferably wireless, communication system 21, so that the measuring devices 20, 1 can, for example, exchange measured values for further processing. This allows, on the one hand, the range of application of the measuring devices 1, 20 to be extended, and on the other hand, more information about the medium being measured to be determined.

(21) In the measuring system 3 shown in FIG. 5, the multi-phase flowmeter 20 is designed as a nuclear magnetic flowmeter. In addition, there is a pressure measuring device 22 for measuring the pressure inside the measuring tube. During operation of the measuring system 3, the flow velocity of the gaseous phase of the medium determined by the ultrasonic flowmeter 1 is transmitted to the control unit 23 of the nuclear magnetic flowmeter and further processed if the gas velocity is particularly high and/or if the pressure measured by the pressure measuring device 22 is particularly high.

(22) FIG. 6 shows a first embodiment of a method 4 for operating the measuring system 3.

(23) In a first step, the multi-phase flowmeter 20 determines a proportion of the liquid phase in the total flow.

(24) In a next step 25, which can also take place simultaneously, the ultrasonic flowmeter 1 determines a flow velocity of the gaseous phase.

(25) In a next step 26, the proportion of the gaseous phase in the total flow is determined using the proportion of the liquid phase.

(26) Finally, if the flow velocity of the gaseous phase determined by the ultrasonic flowmeter 1 is above a limiting flow velocity, the flow of the gaseous phase is determined using the flow velocity of the gaseous phase determined by the ultrasonic flowmeter 1 and the proportion of the gaseous phase 27.

(27) As a result, the flow of the gaseous phase of a multi-phase medium can be reliably determined by this method even under critical conditions.