Ultrasonic flowmeter and method using partial flow measurements

Patent metadata

Field	Value
Publication number	US-10564017-B2
Application number	US-201716335084-A
Country	US
Kind code	B2
Filing date	Sep 19, 2017
Priority date	Sep 21, 2016
Publication date	Feb 18, 2020
Grant date	Feb 18, 2020

Abstract

Ultrasonic flowmeter for measuring the flowrate of a fluid based on transit times of opposite propagating ultrasonic wave packets, including two ultrasonic transducers arranged at a flow tube for transmitting and receiving the ultrasonic wave packets through a fluid; a control circuit configured for operating the ultrasonic transducers to transmit and receive co-propagating and counter-propagating ultrasonic wave packets, and to determine transit times between transmission and reception of the ultrasonic wave packets; wherein the control circuit is further configured to continuously determine the flowrate of the fluid based on sequential application of separate flow measurement sequences and flow estimation sequences, the flow measurement sequence including transmitting and receiving a co-propagating wave packet and a counter-propagating wave packet, determining a transit time difference between the co-propagating and the counter-propagating wave packets, determining the speed of sound in the fluid, and calculating the flowrate based on the transit time difference and the speed of sound; and the flow estimation sequence including transmitting and receiving a co-propagating wave packet and/or a counter-propagating wave packet, and based on the co-propagating or the counter-propagating wave packet, determining whether a fluid condition of the fluid has changed since the previous flow measurement.

First claim

The invention claimed is:

1. An ultrasonic flowmeter for measuring the flowrate of a fluid based on transit times of opposite propagating ultrasonic wave packets, comprising:
a flow tube with a through-going opening for passage of the fluid between an inlet and an outlet;
two or more ultrasonic transducers arranged at the flow tube for transmitting and receiving the ultrasonic wave packets through the fluid;
a control circuit configured for operating the ultrasonic transducers to transmit and receive co-propagating and counter-propagating ultrasonic wave packets;
wherein the control circuit is further configured to continuously determine the flowrate of the fluid based on sequential application of separate flow measurement sequences and flow estimation sequences:
the flow measurement sequences including transmitting and receiving a co-propagating wave packet and a counter-propagating wave packet, digitally sampling the received wave packets and storing the sampled wave packets in a memory associated with the control circuit, determining a phase difference between the wave packets, determining the speed of sound in the fluid, and calculating the flowrate based on the phase difference and the speed of sound; and
the flow estimation sequences including alternately transmitting and receiving at least a co-propagating wave packet or a counter-propagating wave packet, digitally sampling the received wave packet and comparing the sampled wave packet with the corresponding sampled co-propagating wave packet or sampled counter-propagating wave packet, obtained during the previous flow measurement sequences, to determining whether a fluid condition of the fluid has changed since the previous flow measurement.

2. The ultrasonic flowmeter according to claim 1 , wherein at least some of the flow estimation sequences include calculating a corrected flowrate based on a ratio between the phase difference calculated during the previous flow measurement sequence and the present phase difference between the co-propogating and counter propagating wave packets transmitted during the flow estimation sequence, under the assumption that the speed of sound in the fluid is identical to the speed of sound determined during the previous flow measurement sequence.

3. The ultrasonic flowmeter according to claim 1 , wherein at least one of the flow estimation sequences includes calculating the present phase difference based on the phase difference calculated during the previous flow measurement sequence and the phase differences between the present and the previous co-propagating wave packets and/or the present and the previous counter-propagating wave packets, under the assumption that the speed of sound in the fluid is substantially identical to the speed of sound determined during the previous flow measurement sequence.

4. The ultrasonic flowmeter according to claim 1 , wherein at least one of the flow estimation sequences includes determining whether a change in the phase difference is due to a change in flowrate or a change in fluid temperature, based on the phase differences between the present and the previous co-propagating wave packets and the phase difference between the present and the previous counter-propagating wave packets.

5. The ultrasonic flowmeter according to claim 1 , wherein the flow estimation sequences alternate between transmitting and receiving only the co-propagating wave packet or the counter-propagating wave packet.

6. The ultrasonic flowmeter according to claim 1 , wherein at least one of the flow estimation sequences includes digitally sampling the co-propagating wave packet and/or the counter-propagating wave packet at a sample rate lower than the sample rate used in the flow measurement sequences.

7. The ultrasonic flowmeter according to claim 1 , wherein the co-propagating wave packet and/or the counter-propagating wave packet transmitted during at least one of the flow estimation sequences is shorter in length than the wave packets transmitted during the flow measurement sequences.

8. The ultrasonic flowmeter according to claim 1 , wherein at least one of the flow estimation sequences includes sampling only a part of the received co-propagating and/or counter-propagating wave packets.

9. The ultrasonic flowmeter according to claim 1 , wherein a time interval between application of flow measurement sequences is controlled by changes in fluid condition determined under the flow estimation sequences.

10. A method for measuring the flowrate of a fluid based on transit times of opposite propagating ultrasonic wave packets, the method comprising the steps of:
implementing a flow measurement sequence including:
transmitting and receiving a co-propagating wave packet and a counter-propagating wave packet,
digitally sampling the received wave packets and storing the sampled wave packets in a memory,
determining a phase difference between the received wave packets,
determining the speed of sound in the fluid, and
calculating the flowrate based on the phase difference and the speed of sound; and

implementing a flow estimation sequence including:
alternately transmitting and receiving at least a co-propagating wave packet or a counter-propagating wave packet,
digitally sampling the received wave packet and comparing the sampled wave packet with the corresponding sampled co-propagating wave packet or sampled counter-propagating wave packet obtained during the previous flow measurement sequences to determine whether the wave packet of the flow estimation sequence differs from the corresponding wave packet of the flow measurement sequence, and
repeating the flow measurement sequence if the difference between the sampled wave packet of the flow estimation sequence and the corresponding sampled wave packet of the flow measurement sequence is indicative of a change in a fluid condition of the fluid, otherwise repeating the flow estimation sequence.

Assignees

• Kamstrup As

Inventors

• Nielsen Søren Tønnes
• Sørensen Jens Lykke
• Bendixen Paul Martin

Classifications

• G01F1/662 Primary

  Constructional details · CPC title

• G01F1/667

  Arrangements of transducers for ultrasonic flowmeters; Circuits for operating ultrasonic flowmeters · CPC title

• G01F1/668 Primary

  Compensating or correcting for variations in velocity of sound · CPC title

• G01F25/10

  of flowmeters · CPC title