WO2018068764A1 - Large-diameter ultrasonic flow meter - Google Patents

Abstract

A large-diameter ultrasonic flow meter comprises a tubular housing (1) and transducer components (2). Positioning holes (17) are provided at two ends of the tubular housing (1). The positioning holes (17) are perpendicular to a central axis of the tubular housing (1). The transducer components (2) are disposed in the positioning holes (17). One set of the transducer components (2) comprises two transducer components (2) operating together. The ultrasonic flow meter provides, in a finite length of the tubular housing, a maximum projection distance on the central tube axis and between the transducers, increasing a turndown ratio and measurement precision of the ultrasonic flow meter.

Description

Large diameter ultrasonic flowmeter Technical field

The invention relates to the field of flow measurement, and particularly relates to a large-diameter ultrasonic pipe section structure.

Background technique

Ultrasonic flowmeter has high measurement accuracy compared with traditional mechanical flowmeter and electromagnetic flowmeter, and is hardly affected by parameters such as temperature, pressure and density of the fluid to be measured. It has strong adaptability to pipe diameter, easy to use and easy to digitize. Management and other advantages. At present, ultrasonic flowmeters have been widely used in industrial flow measurement fields such as large-caliber heat meters and large-diameter water meters. In practical applications, there is a higher demand for the range and measurement accuracy of the ultrasonic flowmeter.

There are two main ways to improve the flowmeter's measuring range and metering accuracy: one is to neck the flowmeter tube section to increase the fluid flow speed, but the disadvantage of this method is to increase the pipeline resistance; the other is limited. As far as possible, the distance between the transducers, that is, the acoustic wave propagation path, is increased within the length of the tube, and the flow resistance of the pipeline is not increased while increasing the range and the measurement accuracy. The range and metering accuracy of the ultrasonic flowmeter is proportional to the projection distance of the line between the two transducers on the axis of the pipe segment.

The transducer mounting position in the ultrasonic flowmeter disclosed in the authorization publications CN 201993129 U, CN 204855038 U and CN 204330187 U is limited by the machining process of the inclined aperture and the design of the structure itself, so that the transducer can only be mounted at a distance The farther position of the flange greatly reduces the projection distance of the connection between the transducers on the axis of the pipe segment.

Ensure the mechanical processing convenience of the transducer assembly and its installation does not affect the installation of the instrument flange bolts, while maximizing the projection distance of the connection between the two transducers on the axis of the pipe segment, the transducer Position selection and transducer mounting structure optimization has become a difficult issue.

Summary of the invention

The transducer is installed in a relatively close position to the existing ultrasonic flowmeter, so that the projection distance between the two transducers on the axis of the pipe segment is short, which reduces the problem of the flowmeter's measuring range and measurement accuracy, and the present invention A large diameter ultrasonic flow meter is provided.

A large-aperture ultrasonic flowmeter comprising a pipe segment housing and a transducer assembly, the pipe segment housing being provided at both ends with a positioning hole, the positioning hole being perpendicular to an axis of the pipe segment housing, the transducer assembly Provided in the positioning hole, the transducer components are two in a group, and the two used transducer assemblies are used for transmitting and receiving ultrasonic waves, the ultrasonic wave propagation path and the pipe segment The axis of the housing is at an angle.

The beneficial effects of the invention:

1. Positioning hole vertical pipe section housing axis setting, compared with the prior art inclined setting positioning hole, the positioning hole in the processing process is the vertical pipe section housing diameter, the path of the cutter does not interfere with the flange, The processing difficulty is reduced, the processing precision is easily ensured, the processing cost is reduced, and the scribing alignment is simpler.

2. The installation of the transducer assembly does not interfere with the flange and does not interfere with the installation of the bolts on the flange, so the positioning can be placed closer to the flange. Under the condition that the length of the pipe section is constant, the closer the position of the transducer assembly is to the flange, the greater the sound path of the ultrasonic wave.

DRAWINGS

1 is a schematic structural view of Embodiment 1;

2 is a schematic view showing the overall structure of Embodiment 2;

Figure 3 is a front elevational view of Embodiment 2;

Figure 4 is a cross-sectional view along line A-A of Figure 3;

Figure 5 is a partial enlarged view of a portion B of Figure 4;

6 and 7 are exploded views of the transducer assembly of Embodiment 2;

Figure 8 is a schematic diagram of the calculation principle of the flow meter measurement principle.

Figure 9 is a comparison diagram of the present invention and the prior art.

detailed description

The technical solution of the present invention will be further described below in conjunction with the drawings in the embodiments of the present invention.

The invention provides a large-caliber ultrasonic flowmeter comprising a pipe segment housing 1 and a transducer assembly 2. Both ends of the pipe casing 1 are provided with positioning holes 17 which are perpendicular to the axis of the pipe casing 1 for fixing the transducer assembly 2. The transducer assemblies 2 are two in a group and used together. The two transducer assemblies 2 used in combination are used for transmitting and receiving ultrasonic waves, and the ultrasonic wave propagation path is at an angle with the axis of the pipe casing 1 , and the flanges 13 are respectively disposed at both ends of the pipe casing 1 .

In the prior art, the tilting manner of the positioning hole, for example, the patent document with the authorization bulletin number CN 204855038 U, makes the positioning hole not too close to the flange 13 for two reasons: one is in the process of processing the inclined hole, The path of the cutter will interfere with the flange 13 and leave enough space for the cutter. Secondly, when the transducer assembly 2 is installed, it is easy to interfere with the flange 13 and hinder the installation of the bolt on the flange 13. Leave enough room for installation.

The positioning hole 17 of the present invention is perpendicular to the arrangement of the pipe segment housing 1 and overcomes the above two technical problems. Compared with the prior art (authorization bulletin number CN 204855038 U), the positioning hole is inclinedly arranged, so that the positioning hole 17 is in the process. The middle pass route is the diameter of the vertical pipe section housing 1, and the path of the cutter does not interfere with the flange 13, which reduces the processing difficulty, is easy to ensure the processing precision, reduces the processing cost, and the scribing alignment is simpler; The mounting of the assembly 2 does not interfere with the flange 13 and does not interfere with the mounting of the bolts on the flange, so the positioning 17 can be placed closer to the flange 13. Under the condition that the length of the pipe casing 1 is constant, the closer the position of the transducer assembly 2 is to the flange 13, the greater the sound path of the ultrasonic wave.

Ultrasonic waves carry information about the fluid flow rate as they propagate through the flowing fluid. Therefore, the flow rate of the fluid can be detected by the received ultrasonic wave, and converted into a flow rate. The two transducer assemblies 2 used in conjunction with each other simultaneously emit ultrasonic waves and then receive the transmitted ultrasonic waves. As shown in Fig. 8, the liquid flow in the pipe casing 1 can be calculated based on the received time difference Δt:

c ₁ =c+V _a =c+V _average ·cosα, downstream sound velocity

c ₂ = cV _a = cV _average · cosα, countercurrent sound velocity

t ₁ = L / c _1, downstream time

t ₂ =L/c ₂ , countercurrent time

c>>V _average

Now the chip time difference [Delta] t is possible to calculate the minimum time difference is 2.5ns, can be seen from the above equation, the increase in L value Δt = 2.5ns same conditions can effectively reduce the _average V value That flowmeter can be less The flow rate increases the turndown ratio of the flow meter.

Δt is limited by chip accuracy, Δt _minimum = 2.5ns

Formulate a constant K,

among them:

c = the speed of the ultrasonic wave in the liquid to be tested

c ₁ = outgoing ultrasonic speed

t ₁ = departure time

c ₂ = return ultrasonic speed

t ₂ = return time

Δt=go backhaul time difference

V _average = the smallest average flow rate of the liquid (gas) body that can be measured

α = angle between the direct beam of the transducer and the axis of the pipe section

L = the distance between the transducers, ie the sound path

Vα represents the velocity of the fluid in the direction of the direct beam of the transducer (for a horizontal pipe, it is a diagonal line, which is a component of the horizontal amount)

A and B are transducers used in pair with each other

It can be seen that when K is constant, the pipe casing 1 is set according to the national standard. When the diameter and length of the pipe casing 1 are constant, the larger the L, the smaller α, the larger the cosα value, so the V _average is inversely proportional to L. That is, the larger the L, the smaller the V _average .

At present, the advanced time difference chip can calculate the minimum value of the time difference Δt is 2.5nS. This value is (the chip and the circuit). At a certain distance and a certain speed, the flow meter can obtain the minimum time difference that the measured flow rate meets the requirement of 1%. value. It can be seen from the above formula that under the condition that Δt=2.5 ns is constant, increasing the L value can effectively reduce the V _average , that is, the flow meter can measure a smaller flow rate, thereby increasing the range ratio of the flow meter.

among them:

The flowmeter's turndown ratio = Q3/Q1,

Q3 is the common flow rate of a certain type of flow meter, which is a fixed value.

Q1 is the minimum flow that meets the national standard error requirement.

Q=S*V*T,

Q-fluid flow,

S-sectional area,

V-flow rate,

T-time.

When the pipe diameter D is determined, the sectional area S is determined, the flow rate Q1 proportional to _{the average} flow velocity V per unit time, i.e., _{the average} V, the smaller Q1, and the range / larger than Q3 Q1.

The flowmeter disclosed in the present invention is disposed through the vertical pipe section housing 1 of the positioning hole 17, so that the transducer assembly 2 is disposed as close as possible to the flange 13, and the maximum ultrasonic sound path L is obtained on the pipe casing 1 of a certain length. , thereby reducing the V _average , the flow meter can measure the minimum flow is smaller, and the flowmeter's turndown ratio is improved.

As shown in Fig. 9, taking the nominal diameter DN300 (the diameter of the tube is 300mm) as an example, if the positioning hole 17 in the prior art is placed obliquely, α is 55°, the maximum sound path is 367 mm, and the sound path is in the pipe segment. The projection distance on the axis of the housing 1 is 211 mm. With the vertical positioning mode of the positioning hole 17 of the present invention, the obtained α is 45°, the maximum sound path is 389 mm, and the projection distance of the sound path on the axis of the pipe casing 1 is 275 mm. Compared with the prior art, the sound path is The projection distance on the axis of the pipe segment housing 1 is increased by 30.5%.

The ratio of the minimum flow ratio when α is 55° to the minimum flow ratio when Q _{55 is minimum} and α is 45° is the smallest ratio of Q ₄₅ :

Therefore, the range ratio of the flow meter in which the positioning hole 17 of the present invention is vertically disposed is 1.304 times that of the prior art.

As shown in FIG. 1, two flanges 13 are respectively disposed at two ends of the pipe casing 1, and the flange 13 is provided with bolts. Hole, a pipe that connects the flow to be measured by bolting. Two positioning holes 17 are disposed at two ends of the pipe casing 1 near the flange 13, respectively located at the lower side and the upper side of the left and right ends of the pipe casing 1, and the positioning holes 17 are used for mounting the positioning transducer assembly 2, the positioning hole 17 It is disposed perpendicular to the pipe section housing 1. The transducer assembly 2-1 is used in conjunction with the transducer assembly 2-2, one transducer 202 being disposed in each of the two transducer assemblies 2, and the transducer 202 is partially exposed outside the transducer assembly 2. The direction of emission of the two transducers 202 is at an angle to the axis of the segment housing 1. The circuit case 4 is disposed at an intermediate portion of the pipe section housing 1, and a controller is disposed in the circuit case 4. The wires of the transducer 202 are connected to the controller via a conduit 5. In order to improve the range and metering accuracy of the flowmeter within a certain length of the pipe length, the positioning hole 17 should be disposed close to the flange 13 to the maximum extent without affecting the installation and processing, so as to increase the surface between the two transducers 202. The projection distance of the firing pitch on the axis of the pipe segment housing 1. In order not to hinder the mounting of the flange 13, the outer edge height of the positioning hole 17 should be lower than the height of the bolt hole of the flange 13.

It can be understood that a plurality of transducers 202 can be disposed in the transducer assembly 2, and two transducers 202 are disposed in one transducer assembly 2 as a preferred solution. The transducer assemblies 2 that are used in conjunction with each other can be set in groups of two. When measuring fluid flow. The plurality of sets of transducer assemblies 2 can be compared to each other to prevent inaccurate flow measurements of individual transducer assemblies 2, and other transducer assemblies 2 can be left in reserve. For example, the pipe segment housing 1 is a nominal DN300 aperture, and the transducer assembly 2 is a group of two, a total of eight transducer assemblies 2 are provided, and each transducer assembly 2 is provided with two transducers 202. .

Embodiment 2, as shown in Figures 2, 3 and 4, two sets of transducer assemblies 2 are provided in the pipe section housing 1, the first group: the transducer assembly 2-1 is used in conjunction with the transducer assembly 2-2 Second set: The transducer assembly 2-3 is used in conjunction with the transducer assembly 2-4.

As shown in FIGS. 5, 6, and 7, the transducer assembly 2 includes a housing 201 and two transducers 202. The housing 201 is provided with a positioning surface 208 that cooperates with the positioning hole 17. The housing 201 is also provided with a positioning surface 208. Two oblique mounting holes 203 and two transducers 202 are respectively mounted in the two mounting holes 203. The end of the transducer 202 has a table The step surface cooperates with the step surface on the mounting hole 203, and the transducer 202 is fixedly fixed to the outside of the housing and protrudes into the tube housing 1.

As shown in FIGS. 6 and 7, in order to fix the transducer 202, the transducer assembly 2 further includes a fixed plate 211 and a seal ring 210. The fixing plate 211 and the housing 201 are detachably connected by a screw 212. The seal ring 210 is disposed between the fixed plate 211 and the transducer 202 in order to prevent liquid from flowing into the housing 201 through the gap between the mounting hole 203 and the transducer 202.

As shown in FIGS. 6 and 7, in order to fix the housing 201 in the positioning hole 17, the transducer assembly further includes a pressure ring 207, an upper seal ring 205, and a lower seal ring 204. As shown in FIG. 5, a stepped surface 171 is provided in the positioning hole 17, and cooperates with the positioning surface 208. The lower sealing ring 204 is disposed on the positioning surface 208 for preventing liquid from flowing into the interior of the housing 201 through the gap between the housing 201 and the positioning hole 17. In order to press the housing 201 and the positioning hole 17, the pressure ring 207 is screwed to the positioning hole 17, but is not limited thereto. The upper seal ring 205 is disposed between the pressure ring 207 and the housing 201 to prevent external impurities from entering the inside of the housing 201.

As shown in FIGS. 6 and 7, in order to prevent the transducer assembly 2 from rotating in the positioning hole 17, the transducer assembly 2 further includes a positioning platen 206 and a positioning pin 213. The positioning platen 206 is provided with a first positioning hole 2062 that is adapted to the positioning pin 213. The housing 201 is provided with a second positioning hole 214 adapted to the positioning pin 213. The positioning pin 213 passes through the first positioning hole 2062 and the second positioning hole 214 to prevent the housing 201 from rotating relative to the positioning platen 206, and the positioning pin 213, One or more of the first positioning hole 2062 and the second positioning hole 214 should be provided, and three are provided in this embodiment. The positioning platen 206 is provided with an anti-rotation protrusion 2061. The positioning hole 17 is provided with a card slot adapted to the anti-rotation protrusion 2061 to prevent the positioning platen 206 from rotating relative to the positioning hole 17. The positioning platen 206 is disposed between the upper sealing ring 205 and the pressure ring 207, and the spacer 209 is disposed between the positioning platen 206 and the pressure ring 207. The gasket 209 is a polytetrafluoroethylene gasket. For the convenience of installation, the positioning pressure plate 206 and the pressure ring 207 are prevented from being damaged by friction.

As shown in FIG. 5, in order to prevent external impurities from entering the positioning hole, an end cover 14 and an O-ring 11 are provided, The end cap 14 is screwed to the positioning hole 17, and the O-ring 11 is disposed between the end cap 14 and the positioning hole 17.

Claims (8)

A large-caliber ultrasonic flowmeter, comprising: a pipe section housing (1) and a transducer assembly (2), wherein the pipe section housing (1) is provided with positioning holes (17) at both ends thereof, the positioning holes (17) perpendicular to the axis of the pipe segment housing (1), the transducer assembly (2) is disposed in the positioning hole (17), and the transducer assembly (2) is used in combination, The two transducer assemblies (2) used in combination are respectively for transmitting and receiving ultrasonic waves, and the ultrasonic propagation path is at an angle to the axis of the pipe segment housing (1). The large-caliber ultrasonic flowmeter according to claim 1, wherein said transducer assembly (2) comprises a housing (201) and a transducer (202), and said positioning hole (17) is provided with a step a surface (171), the housing (201) is provided with a positioning surface (208) that cooperates with the stepped surface (171) of the positioning hole (17), and the housing (201) is also provided with an oblique mounting A hole (203), the transducer (202) is mounted in the mounting hole (203). The large-caliber ultrasonic flowmeter according to claim 2, wherein said transducer assembly (2) further comprises a fixing plate (211) and a sealing ring (210), said fixing plate (211) and the housing (201) detachably connected by a screw (212) for fixing the transducer (202), the sealing ring (210) being disposed on the fixing plate (211) and the transducer (202) between. A large-caliber ultrasonic flow meter according to claim 3, wherein said transducer assembly (2) further comprises a pressure ring (207), an upper seal ring (205) and a lower seal ring (204), a lower sealing ring (204) is disposed on the positioning surface (208), the pressure ring (207) is screwed to the positioning hole (17), and the pressure ring (207) is used for fixing the housing (201). The sealing ring (205) is disposed between the pressure ring (207) and the housing (201). A large-caliber ultrasonic flowmeter according to claim 4, wherein said transducer assembly (2) further comprises a positioning platen (206), a gasket (209) and a positioning pin (213), said positioning platen (206) is provided with a first positioning hole (2062) adapted to the positioning pin (213), the housing (201) being provided with a positioning pin (213) an adapted second positioning hole (214), the positioning pin (213) passes through the first positioning hole (2062) and the second positioning hole (214), the positioning platen (206) An anti-rotation protrusion (2061) is disposed, the positioning hole (17) is provided with a card slot adapted to the anti-rotation protrusion (2061), and the positioning platen (206) is disposed on the upper sealing ring Between the (205) and the pressure ring (207), the spacer (209) is disposed between the positioning platen (206) and the pressure ring (207), the positioning pin (213), the first positioning One or more holes (2062) and second positioning holes (214) are provided. A large-caliber ultrasonic flowmeter according to claim 5, further comprising an end cap (14) and an O-ring (11), said end cap (14) being threadedly coupled to the positioning hole (17), The O-ring (11) is disposed between the end cap (14) and the positioning hole (17). A large-caliber ultrasonic flowmeter according to claim 1, further comprising a controller and a circuit box (4), said circuit box (4) being disposed outside the pipe section housing (1), said controller setting In the circuit box (4), the controller is electrically coupled to the transducer (202). The large-caliber ultrasonic flowmeter according to any one of claims 1 to 7, wherein two transducers (202) are disposed in the one transducer assembly (2), and the transducer assembly (2) Several groups can be set.

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