FLUID METER

Description

[0001] The invention relates to the field of fluid meters. BACKGROUND OF THE INVENTION

[0002] A gas meter is designed to assess the gas consumption of a customer's installation in order to bill the customer for the gas consumption.

[0003] A gas meter typically includes a main channel and a device for measuring gas flow by emitting and receiving ultrasonic signals.

[0004] To measure the gas flow rate, the gas velocity in the main channel is evaluated by emitting an ultrasonic signal along a defined path and measuring the travel times of the ultrasonic signal to travel this path from upstream to downstream and from downstream to upstream. The gas velocity is then estimated from the defined path length and the difference between the travel times, and the gas flow rate is deduced from the gas velocity.

[0005] However, gas consumption billing does not depend solely on the gas flow rate (or the volume of gas consumed), but is based on the energy supplied to the installation. Therefore, to bill for gas consumption, the gas flow rate must be converted into energy. This conversion takes into account the gas composition as well as the pressure and temperature at the installation. A set of sensors that measure both the flow rate and the composition of a combustible gas to determine its calorific value is considered state-of-the-art according to publication FR 2 776 776 A1.

[0006] The gas supplied is a mixture of different gases injected into the network from various sources. The gas composition is measured using measuring devices installed at the inlet of the gas distribution network and at several intermediate points within the network. Therefore, the measured gas composition does not exactly correspond to the gas supplied to the installation. Consequently, the assessment of the energy supplied to the installation and the billing for gas consumption are inaccurate. SUBJECT OF THE INVENTION

[0007] The invention aims to improve the accuracy of billing for a fluid supplied to an installation. SUMMARY OF THE INVENTION

[0008] To achieve this goal, a fluid meter is proposed comprising a main channel and a flow measurement device for measuring the flow rate of the fluid circulating in the main channel; the fluid meter further comprises a device for measuring the composition of the fluid, including: partitions defining a chamber; at least one inlet port made in one of the partitions, the inlet port being arranged so that a portion of fluid enters the chamber; an infrared emitter and an infrared receiver located in the chamber and arranged to measure the composition of the portion of fluid by infrared spectroscopy, the inlet port opening into the chamber near the infrared emitter or infrared receiver; a conduit connecting the chamber and the main channel, the conduit being arranged so that the portion of fluid is drawn out of the chamber by Venturi effect to escape from the chamber and enter the main channel, the conduit opening into the main channel upstream of the inlet port and upstream of the flow measurement device.

[0009] The fluid meter according to the invention therefore includes a device for measuring the fluid composition, which is integrated into the fluid meter. The fluid composition used to bill the customer for fluid consumption thus corresponds precisely to the fluid consumed and can be dynamically evaluated to take into account any variations in the fluid composition.

[0010] The choice of infrared spectroscopy to measure the composition of the fluid, and the use of the infrared emitter and infrared receiver positioned in the chamber, make it possible to obtain a compact fluid composition measurement device that is easily integrated into the fluid meter.

[0011] It should be noted that, since the conduit of the fluid composition measurement device opens into the main channel upstream of the flow measurement device, the portion of fluid used to measure the fluid composition is indeed included in the flow measurement. Therefore, measuring the fluid composition does not degrade the accuracy of the fluid flow measurement.

[0012] Furthermore, since the inlet opening into the chamber is located near the infrared emitter or receiver, the fluid entering the chamber sweeps away the infrared emitter or receiver, thus preventing dust from settling on it. Of course, using two inlet openings, one near the infrared emitter and the other near the infrared receiver, allows for sweeping of both the emitter and the receiver simultaneously.

[0013] Other features and advantages of the invention will become apparent from the following description of a particular, non-limiting embodiment of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Reference will be made to the attached drawings, including: there figure 1 represents a fluid meter according to the invention; the figure 2 represents a main channel, a flow measurement device, and a device for measuring the composition of the fluid of the fluid meter according to the invention; the figure 3 is a view equivalent to that of the figure 2 , in perspective and with a different orientation; the figure 4 is a cross-sectional view along plane IV-IV of a conduit in the fluid composition measurement device; the figure 5 is a view equivalent to that of the figure 3 , from below and stripped at the level of the duct. DETAILED DESCRIPTION OF THE INVENTION

[0015] With reference to figure 1 à 5 The fluid meter according to the invention is here a gas meter 1 comprising a sealed casing 2 including an inlet port 3 and an outlet port 4. The inlet port 3 and the outlet port 4 allow the gas meter 1 to be connected to a pipe which links a gas distribution network to a gas consuming installation.

[0016] The gas meter 1 also includes a main channel 5 and a flow measurement device for measuring the flow of gas circulating in the main channel 5. The length Lc of the main channel 5 is approximately 100mm, and the width lc of the main channel 5 at its outlet is approximately 30mm.

[0017] The gas flows in the main channel 5 from upstream to downstream, in the direction of arrow 7.

[0018] Plates 6 are positioned at the inlet of the main channel 5. These plates 6 extend in planes parallel to the lateral walls of the main channel 5. The plates 6 ensure that the gas flow in the main channel 5 is laminar and non-turbulent. These plates 6 improve the accuracy of the gas flow measurement.

[0019] The gas flow measurement device comprises a first ultrasonic transducer 8a, a second ultrasonic transducer 8b and a measuring module 9 (shown schematically on the figure 1 The measurement module 9 includes a processor. The measurement module 9 drives the first ultrasonic transducer 8a and the second ultrasonic transducer 8b and performs processing on the gas flow measurements.

[0020] To measure the gas flow rate, the measuring module 9 evaluates the gas velocity in the main channel 5.

[0021] The measuring module 9 generates an electrical signal and transmits it to the first ultrasonic transducer 8a, which emits an ultrasonic measurement signal. This ultrasonic measurement signal travels a defined path from upstream to downstream and is received by the second ultrasonic transducer 8b. The measuring module 9 then calculates the travel time of the ultrasonic measurement signal to cover the defined path from upstream to downstream.

[0022] Then, the measuring module 9 produces an electrical signal and transmits it to the second ultrasonic transducer 8b, which emits an ultrasonic measurement signal. The ultrasonic measurement signal travels along a defined path from downstream to upstream and is received by the first ultrasonic transducer 8a. The measuring module 9 then calculates the travel time taken by the ultrasonic measurement signal to travel along the defined path from downstream to upstream.

[0023] The measurement module 9 then evaluates the gas velocity and therefore the gas flow rate from the difference between the upstream to downstream travel time and the downstream to upstream travel time.

[0024] The minimum gas flow rate in the main channel 5 is on the order of 0.3 l / min, which gives an average gas velocity in the main channel 5 of about 2.5 cm / s.

[0025] The maximum gas flow rate in the main channel 5 is around 170 l / min, which gives an average gas velocity in the main channel 5 of approximately 1m / s.

[0026] The gas meter 1 also includes a device for measuring the composition of the gas 10.

[0027] The gas composition measurement device 10 includes a housing 12 located on a side wall 13 of the main channel 5, outside the main channel 5.

[0028] The case 12 has a rectangular parallelepiped shape.

[0029] The housing 12 is made up of a plurality of partitions defining a chamber 14 inside the housing 12. The partitions include two first partitions 15a, 15b parallel to each other and perpendicular to the lateral wall 13 of the main channel 5, two second partitions 16a, 16b parallel to each other and perpendicular to the first partitions 15, a front partition 17 (transparent on the figures 2 , 3 And 5 ), and an internal partition 18. A portion of the side wall 13 of the main channel 5 forms a rear partition of the housing 12.

[0030] Among the two second partitions 16, there is a second upper partition 16a and a second lower partition 16b.

[0031] The internal partition 18 is parallel to the second partitions 16a and 16b and divides chamber 14 into a first compartment 14a and a second compartment 14b. The first compartment 14a is an upper compartment, so the second upper partition 16a forms an upper partition of the first compartment 14a. The second compartment 14b is a lower compartment, so the second lower partition 16b forms a lower partition of the second compartment 14b.

[0032] The internal partition 18 has an opening 21 which is here formed in a central portion of the internal partition 18. The opening 21 is actually a space between a first half of internal partition 18a and a second half of internal partition 18b.

[0033] Inside room 14 are located an infrared emitter 25 and an infrared receiver 26.

[0034] The infrared transmitter 25 includes a light-emitting diode for emitting infrared measurement signals. The infrared receiver 26 includes a sensor for receiving the infrared measurement signals.

[0035] The infrared transmitter 25 and the infrared receiver 26 are both connected to the measuring module 9.

[0036] The infrared emitter 25 and the infrared receiver 26 are located inside the first compartment 14a of chamber 14.

[0037] The infrared emitter 25 is positioned on the first partition 15a, while the infrared receiver 26 is positioned on the first partition 15b.

[0038] The infrared emitter 25 and the infrared receiver 26 are therefore located opposite each other.

[0039] A first entry orifice 27a and a second entry orifice 27b are made in the second upper partition 16a. The first entry orifice 27a and the second entry orifice 27b are circular holes of small diameter.

[0040] The first inlet 27a is located near the infrared emitter 25, above the infrared emitter 25. The first inlet 27a opens into the first compartment 14a of chamber 14 with respect to the infrared emitter 25. The first inlet 27a is located within a zone 28a defined by a distance La from the first wall 15a on which the infrared emitter 25 is positioned. The distance La is here equal to one-quarter of the length L of the second partitions 16.

[0041] The second inlet 27b is located near the infrared receiver 26, above the infrared receiver 26. The second inlet 27b opens into the first compartment 14a of chamber 14 opposite the infrared receiver 26. The second inlet 27b is located within a zone 28b defined by a distance Lb from the first wall 15b on which the infrared receiver 26 is positioned. The distance Lb is here equal to one-quarter of the length L of the second partitions 16.

[0042] When the gas meter 1 is connected to the pipe which links the gas distribution network to the gas consuming installation, the sealed box 2 is filled with gas.

[0043] The gas flows in the main channel 5 from upstream to downstream to be directed, via the main channel 5 and the outlet port 4, to the gas consuming installation.

[0044] A first portion of gas 30a then enters the first compartment 14a of chamber 14 via the first inlet orifice 27a, and a second portion of gas 30b then enters the first compartment 14a of chamber 14 via the second inlet orifice 27b.

[0045] The infrared transmitter 25 emits an infrared measurement signal. The infrared measurement signal passes through the first compartment 14a of chamber 14, filled with the first portion of gas 30a and the second portion of gas 30b, and is received by the infrared receiver 26.

[0046] The measurement module 9 acquires an electrical measurement signal generated by the infrared receiver 26 from the received infrared measurement signal.

[0047] The electrical measurement signal is digitized. The processor of measurement module 9 performs calculations on the digitized electrical measurement signal to define and process the infrared spectrum of the received infrared measurement signal. Measurement module 9 thus produces mole fractions of the gas and obtains the gas composition. Measurement module 9 can also perform compensation of gas flow measurements for pressure, temperature, and compression (PZT compensation).

[0048] Thanks to the small sizes of the first inlet orifice 27a and the second inlet orifice 27b, the gas velocity is relatively high when the first portion of gas 30a enters the first compartment 14a of chamber 14 via the first inlet orifice 27a, and the gas velocity is relatively high when the second portion of gas 30b enters the first compartment 14a of chamber 14 via the second inlet orifice 30b.

[0049] This results in a first gas stream and a second gas stream which sweep with a significant flow rate respectively over the surface of the infrared emitter 25 and the surface of the infrared receiver 26. This prevents the deposition of dust on the infrared emitter 25 and on the infrared receiver 26.

[0050] The fluid composition measurement device further includes a conduit 32 which connects the second compartment 14b of chamber 14 and the main channel 5. The conduit 32 is arranged so that the first portion of fluid 30a and the second portion of fluid 30b are drawn from chamber 14 by Venturi effect to escape from chamber 14 and enter the main channel 5.

[0051] Thus, the first portion of gas 30a and the second portion of gas 30b enter the first compartment 14a of chamber 14 respectively via the first inlet orifice 27a and the second inlet orifice 27b, then are drawn into the second compartment 14b of chamber 14 via the opening 21 of the internal partition 18, and then exit chamber 14 via the conduit 32 to enter the main channel 5. The gas therefore follows the path 33. The first inlet orifice 27a and the second inlet orifice 27b ensure that the first compartment 14a of chamber 14 is constantly filled with gas.

[0052] Note that a portion of the gas composition measurement device 10 extends downstream of at least a portion of the flow measurement device. Here, for example, on the figure 2 , the second half of internal partition 18b is positioned to the right (or downstream, taking into account the direction of gas flow) of a left part (or upstream part) of the first ultrasonic transducer 8a.

[0053] The conduit 32 of the gas composition measuring device 10 opens into the main channel 5 upstream of the first inlet port 27a and the second inlet port 27b. The conduit 32 of the gas composition measuring device 10 also opens into the main channel 5 upstream of the gas flow measurement device, and therefore upstream of the first ultrasonic transducer 8a and the second ultrasonic transducer 8b. Thus, the measured gas flow rate corresponds to the total volume of gas flowing through the main channel 5 to be distributed to the gas-consuming installation via the main channel 5 and the outlet port 4.

[0054] An upstream section SI of the main channel 5 upstream and near conduit 32 is smaller than a downstream section S2 of the main channel 5 downstream and near conduit.

[0055] The main channel 5 therefore has a local narrowing at the level of the conduit 32.

[0056] The local constriction tends to accelerate the gas at the point where conduit 32 opens into the main channel 5. The acceleration of the gas creates a low-pressure area by the Venturi effect, which draws the gas from chamber 14 towards the main channel 5 (see again path 33 on the figure 4 ).

[0057] The local narrowing results in particular from an inclination of the slope 34 of the side wall 13 upstream of the conduit 32 and in the vicinity of the conduit 32. The inclination of the slope locally directs the gas flow towards the center of the main channel 5. The inclination of the slope 34 also increases the acceleration of the gas in the vicinity of the conduit 32 and prevents a portion of the gas from entering the chamber 14 via the conduit 32.

[0058] The conduit 32 is a slot formed in the side wall 13. The slot is defined by a first local end 36 and a second local end 37 of the side wall 13, opposite each other. The first local end 36 of the side wall 13 is beveled. The second local end 37 is right-angled.

[0059] An edge 38 of the second local end 37, shaped like a right angle, is closer to the main channel 5 than an edge 39 of the first local end 36, shaped like a bevel. This prevents a vortex effect of the gas that would tend to oppose the passage of gas from the second compartment 14b of chamber 14 to the main channel 5.

[0060] It is noted that the second compartment 14b on the one hand, and the central position of the opening 21 of the internal wall 18 which separates the chamber on the other hand, make it possible to maintain a homogeneous distribution of the gas in the first compartment 14a of the chamber 14. Indeed, as the conduit 32 through which the gas escapes from the chamber 14 is eccentric with respect to the chamber 14, the use of a single compartment would tend to concentrate the gas on the side of the conduit 32.

[0061] Of course, the invention is not limited to the embodiment described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0062] Although a gas meter has been described here, the invention can be implemented on a meter for any type of fluid. Similarly, the flow rate is not necessarily measured by emitting and receiving ultrasonic signals: any type of flow measurement device can be used.

Claims

1. A fluid meter (1) including a main channel (5) and a flow rate measurement device (8a, 8b, 9) for measuring the flow rate of a fluid flowing in the main channel (5), the fluid meter (1) further including a fluid composition measurement device (10) comprising: • partitions (15a, 15b, 16a, 16b, 17, 18) defining a chamber (14); • at least one inlet orifice (27a, 27b) formed in one of the partitions, the inlet orifice being arranged so that a portion (30a, 30b) of the fluid penetrates into the chamber (14); • an infrared emitter (25) and an infrared receiver (26) situated in the chamber and arranged to measure the composition of the portion of the fluid (30a, 30b) by infrared spectroscopy, the inlet orifice (27a, 27b) opening out into the chamber in the proximity of the infrared emitter (25) or of the infrared receiver (26); • a duct (32) putting the chamber (14) into communication with the main channel (5), the duct (32) being arranged so that the portion of the fluid (30a, 30b) is sucked from the chamber by the Venturi effect in order to escape from the chamber and penetrate into the main channel (5), the duct (32) opening out into the main channel upstream from the inlet orifice and upstream from the flow rate measurement device (8a, 8b, 9).

2. A fluid meter (1) according to claim 1, including a first inlet orifice (27a) opening out into the chamber (14) in the proximity of the infrared emitter (25) and a second inlet orifice (27b) opening out into the chamber in the proximity of the infrared receiver (26).

3. A fluid meter (1) according to claim 2, wherein the partitions comprise two mutually parallel first partitions (15a, 15b) and a second partition (16a) perpendicular to the two first partitions, the infrared emitter and the infrared receiver each being positioned on a distinct of the two first partition (15a, 15b), the first inlet orifice (27a) and the second inlet orifice (27b) being made in the second partition (16a), the first inlet orifice (27a) opening out into the chamber (14) in register with the infrared emitter (25) and the second inlet orifice (27b) opening out into the chamber (14) in register with the infrared receiver (26).

4. A fluid meter (1) according to claim 1, wherein the partitions include an internal partition (18) with an opening (21) and that subdivides the chamber (14) into a first compartment (14a) and a second compartment (14b), the infrared emitter (25) and the infrared receiver (26) being positioned in the first compartment (14a), the duct (32) opening out into the second compartment (14b).

5. A fluid meter (1) according to claim 4, wherein the opening (21) of the internal partition (18) is formed in a central portion of the internal partition (18).

6. A fluid meter (1) according to claim 1, wherein an upstream section (S1) of the main channel (5) upstream from and in the proximity of the duct (32) is smaller than a downstream section (32) of the main channel (5) downstream from and in the proximity of the duct (32).

7. A fluid meter (1) according to claim 1, wherein the duct (32) is a slot defined between a first local end (36) and a second local end (37) of a wall (13) of the main channel (5), the first local end (36) having a chamfer shape and the second local end (36) having a right angle shape.

8. A fluid meter according to claim 7, wherein an edge (38) of the second local end (37) is closer to the main channel (5) than an edge (39) of the first local end (36) .