CN116358654A - Coriolis mass flow sensor and mass flowmeter - Google Patents

Abstract

The present application relates to coriolis flow sensors and mass flowmeters. The coriolis mass flow sensor includes: a sensing assembly comprising a measuring tube for guiding a fluid to be measured; a housing part in which the measuring tube is arranged; an interface assembly having a housing connected to the housing member and provided with a fluid inlet fitting and a fluid outlet fitting for introducing or removing fluid from the measuring tube; the interface assembly is provided with a vacuum-pumping joint communicated to the interior of the housing part, a sealed vacuum cavity is formed in the interior of the housing part, and the measuring tube is accommodated in the vacuum cavity. The Coriolis flow sensor and the mass flowmeter are particularly suitable for the ultralow temperature medium industry, and can improve the reliability, stability and accuracy of flow measurement.

Description

Coriolis mass flow sensors and mass flow meters

technical field

The invention relates to the field of flow measurement, in particular to a Coriolis mass flow sensor and a mass flow meter, especially a Coriolis mass flow sensor and a mass flow meter suitable for the ultra-low temperature medium industry.

Background technique

A Coriolis mass flow meter is an instrument that measures the mass flow rate of a fluid flowing through a measuring tube based on the Coriolis force effect. It has been widely used because of its high measurement accuracy, wide range of measurable fluids, and strong environmental applicability.

At present, the demand for Coriolis mass flowmeters in the ultra-low temperature medium industry is increasing, such as in liquid nitrogen, LNG (liquefied natural gas) and other industries. A Coriolis mass flow meter usually consists of two parts: a sensor and a transmitter. Existing mass flowmeter sensors generally use inert gas to be filled between the measuring tube and the casing to perform thermal insulation and slow down the corrosion of electronic components inside. When the mass flowmeter sensor is used in a low temperature environment for a long time, the heat conduction phenomenon is obvious, and the surface of the sensor is easy to freeze, resulting in uncertain changes in its own vibration. Furthermore, longer measuring tubes will also aggravate the heat conduction phenomenon, thereby affecting the real-time temperature measurement and reducing the accuracy of temperature compensation. In addition, the electronic components and their joints inside the sensor will also interfere with the accuracy and reliability of the electronic signal due to a small amount of floating ice, which will reduce the measurement accuracy and service life of the flowmeter and affect its measurement performance.

Contents of the invention

Therefore, the object of the present invention is to propose a Coriolis mass flow sensor and a corresponding mass flowmeter to at least partially overcome the defects in the prior art, especially applicable to the ultra-low temperature medium industry, for example, for Realize the flow measurement of liquid nitrogen, LNG, etc.

The present invention provides a Coriolis mass flow sensor, comprising: a sensing assembly, the sensing assembly includes a measuring tube for guiding the fluid to be measured; a housing part, the measuring tube is arranged in the housing part; an interface assembly, the The interface assembly has a housing connected to the housing part, and is provided with a fluid inlet joint and a fluid outlet joint for introducing or exporting fluid into or out of the measuring tube; the interface assembly is provided with a pump connected to the inside of the housing part. A vacuum connector, the inside of the shell part forms a sealed vacuum chamber, and the measuring tube is accommodated in the vacuum chamber.

The working principle of the Coriolis mass flow sensor is based on the Coriolis effect. The measuring tube acts as the sensitive element of the sensor, and the fluid to be measured flows through it when the measurement is performed. According to the technical solution proposed by the present invention, the measuring tube is housed in a vacuum chamber, that is, a "vacuum sheath" is formed around the measuring tube, thereby at least providing heat insulation protection measures for the measuring tube , At the same time, it also provides effective anti-corrosion protection measures for the measuring tube and other electronic components located in the housing parts, which is especially important for sensors used in industries with ultra-low temperature media (such as liquid nitrogen, LNG, etc.). With the vacuum chamber design, in addition to being able to reliably realize the above protection/isolation functions, its economy, convenience, and environmental friendliness are unmatched by existing technologies (such as the design scheme using inert gas).

According to an embodiment of the present invention, the absolute pressure of the vacuum chamber is less than 5 Pa, and a corresponding vacuum insulation layer is formed around the measuring tube.

Further, the vacuum joint includes a joint nut fixed in the housing of the interface assembly and a valve body screwed to the joint nut.

According to an embodiment of the present invention, the joint nut is configured with a conical mounting seat, and forms a conical seal with the valve body at the conical mounting seat.

Here, according to the present invention, the material of the vacuum joint (joint nut and valve body) can be stainless steel, the vacuum pump is connected with the vacuum joint through the vacuum auxiliary tooling, and the vacuum pump is started to reach a vacuum with an absolute pressure of less than 5 Pa in the closed space. In the state, tighten the valve body of the vacuum joint to achieve conical sealing, and then seal it to form a high-vacuum cavity, which can greatly reduce the internal and external heat conduction, reduce the degree of icing, and ensure that the sensor when flowing through the ultra-low temperature medium The vibration stability of the sensitive element, i.e. the measuring tube, increases the reliability and accuracy of the measurement.

Further, the measuring pipe has a U-like structure, including two straight pipe sections and an elbow section connecting the two straight pipe sections.

Advantageously, the curved pipe section extends in an arc shape, and the arc has a central angle greater than 180 degrees. Preferably, the arc has a central angle of 192 degrees.

Further, the sensing assembly further includes an excitation element arranged at the center of the curved pipe section inside the U-like shape and detection elements arranged at both ends of the curved pipe section.

It is advantageous if the inner and/or outer surface of the measuring tube is designed as a BA surface. The measuring tube can be made of stainless steel. The so-called BA surface stainless steel has the characteristics that the surface will not be oxidized and the surface is highly reflective. Using the BA surface on the inner and outer surfaces of the shell and the measuring tube can reduce heat conduction and energy exchange.

Advantageously, the housing part is configured as a cylindrical sleeve. This design is generally compact in structure and beautiful in appearance, and can realize a more reasonable space layout.

Further, the inner surface and/or the outer surface of the shell component is configured as a BA surface. Thus, the effects of reducing heat conduction and energy exchange as described above can also be achieved.

Further, the inner surface and/or the outer surface of the shell component is provided with a high reflective paint layer.

According to an embodiment of the present invention, the fluid inlet joint and the fluid outlet joint are respectively formed with connecting flanges.

According to an embodiment of the present invention, the interface assembly is also provided with a transmitter connector for connecting a transmitter.

According to the present invention, a mass flow meter is also proposed, including a sensor and a transmitter, and the sensor is configured as the aforementioned Coriolis mass flow sensor.

Advantageously, the sensor and the transmitter are connected through a transmitter joint provided at the interface assembly, and the transmitter joint can be configured as a pipe joint with a length of at least 150 mm. The design with longer pipe joints can avoid the generation of condensed water vapor and other influences on the reliability of the electronic circuit of the transmitter. It can be seen that the function of the transmission connection mechanism is to provide a safe working distance for the sensing mechanism and the external transmitter. In addition to the transmitter connector in this embodiment, other methods that can provide a safe working distance can also be used to achieve this purpose .

It is worth mentioning that the Coriolis mass flow sensor of the present invention is based on the traditional Coriolis mass flow sensor, and a suitable modification is proposed to make its measurement more accurate. The beneficial effects of the present invention and its preferred embodiments include at least:

(1) According to a design of the present invention, a vacuum state with an absolute pressure of less than 5Pa is formed in the closed space containing the measuring tube (and other electronic components), thereby greatly reducing the heat conduction inside and outside, and reducing the degree of icing , to ensure the stability of the vibration of the measuring tube when flowing through the ultra-low temperature medium, and improve the reliability and accuracy of the measurement;

(2) According to a design of the present invention, a U-shaped measuring tube is used, so that the spatial position of the sensing device is reduced by half, the length of the pipeline is reduced by half, the heat conduction area is greatly reduced, the temperature measurement followability will be better, and the temperature compensation It will be more accurate and further improve the accuracy of flow measurement; in addition, this structure also maintains good vibration characteristics. Under the same conditions, it is much stronger than the small flow signal of U-shaped structure, which is convenient for transmitter signal detection and calculation, and improves Reliability, stability and accuracy of flow measurement;

(3) According to a design of the present invention, the cavity between the measuring tube and the shell is in a high vacuum state, and the measuring tube pipeline is short and the surface of the measuring tube and the shell are all highly reflective BA surfaces, which can effectively reduce the The degree of heat conduction and icing ensures the stability of the measuring tube vibration;

(4) According to a design of the present invention, the transmitter joint is heightened to avoid failure of the electronic connector of the transmitter at low temperature and ensure the reliability of the loop signal; the sensor device has a compact structure and a beautiful appearance, which is beneficial to supporting pipelines , Instrumentation, etc. installation layout.

The features and advantages of the Coriolis flow sensor provided according to the first aspect of the present invention are also applicable to the mass flow meter of the second aspect of the present invention. Using the Coriolis flow sensor and mass flowmeter of the present invention can greatly improve the service life, economy and ease of maintenance of the product when used in the ultra-low temperature medium industry, broaden the use occasions of the product, and provide customers with better on-site solution.

Description of drawings

Exemplary embodiments of the invention are shown in the drawings. The embodiments and drawings disclosed herein are to be regarded as illustrative rather than restrictive. It is also worth noting that, for the sake of clarity of illustration, some structural details in the drawings are not drawn according to actual scale.

1 is a schematic diagram of a Coriolis flow sensor according to an embodiment of the present invention;

Fig. 2 is a cross-sectional view of a Coriolis flow sensor according to an embodiment of the present invention;

3 is a sectional view of an evacuation connection according to an embodiment of the invention.

Detailed ways

The technical solutions of the embodiments of the present invention will be described below with reference to the accompanying drawings. Apparently, the described embodiments only relate to some, but not all, implementations of the present invention. Based on the disclosed embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application. The terms "comprising" and "having" and any variations thereof in the description and claims of this application are intended to cover a non-exclusive inclusion. For example, a process, method, product or device comprising a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units not specifically listed, or optionally further includes For other steps or units inherent in these processes, methods, products or devices.

Those skilled in the art should understand that, in the description of the specification and claims of this application, the orientation or positional relationship indicated by certain terms is based on the orientation or positional relationship shown in the drawings, which is only for the purpose of It is convenient to describe the present invention and simplify the description, but does not represent or imply that the referred device, mechanism, structure or element must have a specific orientation, be constructed and operated in a specific orientation, so the above terms should not be construed as limiting the present invention.

Reference herein to an "embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one implementation of the invention. The occurrences of this phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is understood explicitly and implicitly by those skilled in the art that the embodiments described herein can be combined with other embodiments.

Unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meanings as commonly understood by those of ordinary skill in the art, and can be specifically defined according to their context in the context of related technical descriptions. explain.

The present invention will be described in detail below with reference to the accompanying drawings and examples.

The working principle of the Coriolis mass flow sensor of the present invention is based on the Coriolis effect. When no fluid passes through the measuring tube, the measuring tube always vibrates uniformly, and the internal phase sensing vibration is accurately recorded. When there is fluid flow, due to the Coriolis effect, the inlet and outlet parts of the pipeline vibrate in different directions at the same time, causing additional torsional vibration of the measuring tube, and the phase detection element acquires the temporal and spatial changes of the pipeline vibration , by recording the phase difference to measure and calculate the quality of the fluid currently flowing through the pipeline, the faster the flow rate and the greater the flow rate, the greater the deviation of the vibration of the measuring tube, the phase detection element can also record the frequency of the vibration, that is, the measurement The number of times the tube vibrates in one second. For example, a measuring tube filled with water vibrates more frequently than a measuring tube filled with honey. Therefore, the vibration frequency can directly reflect the density of the liquid. The vibration of the measuring tube can simultaneously detect the density of the liquid. Flow and density, and flow and density are independent of each other, this application can simultaneously measure multiple process variables in the pipeline, such as mass flow, volume flow, density, temperature, and even viscosity.

Figure 1 and Figure 2 schematically show the basic structure of the Coriolis flow sensor of the present invention, the Coriolis mass flow sensor includes: a sensing assembly, the sensing assembly includes a measuring tube 4 for guiding the fluid to be measured; a housing Part 1, the measuring tube 4 is placed in the housing part 1; an interface assembly 2, the interface assembly 2 has a housing connected to the housing part 1, and is provided with a fluid inlet joint and a fluid outlet joint for The fluid is introduced into or exported from the measuring tube 4; the interface assembly 2 is provided with a vacuum joint 5 connected to the inside of the shell part 1, and the inside of the shell part 1 forms a sealed vacuum chamber, and the measuring tube 4 is accommodated in the in the vacuum chamber.

Fig. 2 is a structural sectional view of a Coriolis flow sensor according to an embodiment of the present invention. The housing part 1 is provided with a measuring tube 4, an excitation element (such as an excitation coil), a vibration pickup element or a detection element (such as a phase detection element) and an induction circuit. Usually, the measuring tube 4 is configured as an axisymmetric structure, the excitation coil is arranged on the symmetric axis of the measuring tube 4, and the phase detection element is arranged at the inlet end and the outlet end of the measurement, and are symmetrical to the axisymmetric measuring tube 4. According to the spatial position of the measuring tube 4 and the analysis of the vibration mode of the shell part 1, the shell part 1 is selected to adopt a cylindrical sleeve shell, which is small in size and compact in structure, and is convenient for pipeline installation layout and integrated use with other instruments and meters. The working principle of the present invention is based on the Coriolis effect. When no fluid passes through the measuring tube, the excitation coil ensures that the measuring tube 4 maintains uniform vibration all the time, and the phase detection elements respectively record the vibration accurately. When the fluid flows, due to the Coriolis effect, the inlet and outlet parts of the pipeline vibrate in different directions at the same time, and the sensitive phase detection element acquires the temporal and spatial changes of the vibration of the pipeline, and by recording the phase difference, And transmit it to the induction circuit, which can directly measure and calculate the quality of the fluid currently flowing through the pipeline.

The present invention further stipulates that the absolute pressure of the vacuum chamber is preferably less than 5 Pa, and a corresponding vacuum insulation layer is formed on the periphery of the measuring tube 4 .

The two ports of the measuring tube 4 can be welded together with the interface assembly 2 .

3 is a cross-sectional view of a vacuum joint according to an embodiment of the present invention. The vacuum joint 5 includes a joint nut 8 fixed in the housing of the interface assembly 2 and a valve body 7 screwed to the joint nut 8. . Further, the joint nut 8 is configured with a conical mounting seat, and forms a conical seal with the valve body 7 at the conical mounting seat. Through the vacuuming process, the cavity between the shell and the measuring tube can form a vacuum state with an absolute pressure of less than 5Pa, which greatly reduces heat conduction.

The vacuum joint 5 forms a sealed vacuum cavity in the shell part 1 through external vacuum equipment or vacuum auxiliary tooling. The vacuum joint 5 includes a valve body 7 and a joint nut 8. As shown in Figure 3, the joint nut 8 can be Embedded and fixed (for example by welding) on the housing of the interface assembly 2 . The material of the vacuum joint (joint nut 8 and valve body 7) can be stainless steel, the vacuum pump is connected with the vacuum joint through the vacuum auxiliary tooling, and the vacuum pump is started until the absolute pressure in the closed space is less than 5Pa. The valve body of the vacuum joint realizes conical sealing, and then seals to form a high-vacuum cavity, which can greatly reduce the heat conduction inside and outside, reduce the degree of freezing, and ensure that the sensitive element of the sensor is measured when it flows through the ultra-low temperature medium The stability of the tube vibration improves the reliability and accuracy of the measurement.

As shown in FIG. 2 , the measuring pipe 4 has a U-like structure, which includes two straight pipe sections and an elbow section connecting the two straight pipe sections. Advantageously, the curved pipe section extends in an arc shape, and the arc has a central angle greater than 180 degrees. Preferably, the arc has a central angle of 192 degrees.

Further, the sensing assembly further includes an excitation element arranged at the center of the curved pipe section inside the U-like shape and detection elements arranged at both ends of the curved pipe section.

It is suitable that the above-mentioned measuring tube is similar in structure to the letter "U", which is referred to as "U-like" here. The so-called "U-like shape" is relative to the standard "U-shape". If the standard "U-shape" has symmetrical and parallel arms, the "U-like" arms here are symmetrical but Not parallel. Preferably, the bend angle of the U-like measuring pipe in the bend is 192 degrees. The spatial position of the sensing device is reduced by half, the length of the pipeline is reduced by half, the heat conduction area is greatly reduced, the temperature measurement followability will be better, the temperature compensation will be more accurate, and the accuracy of flow measurement will be further improved; in addition, the structure also maintains Better vibration characteristics. Under the same conditions, the small flow signal of U-like structure is much stronger than that of U-shaped structure, which is convenient for transmitter signal detection and calculation, and improves the reliability, stability and accuracy of flow measurement.

According to one embodiment of the invention, the inner and/or outer surface of the measuring tube 4 is configured as a BA surface. The housing part 1 is configured as a cylindrical sleeve. The inner and/or outer surface of the housing part 1 is designed as a BA surface. The inner surface and/or the outer surface of the housing part 1 is provided with a highly reflective paint layer.

It is suitable for this that the material of the measuring tube 4 and the shell part 1 is stainless steel, the inner and outer surfaces of both are BA surfaces, the surface roughness of the measuring tube 4 can reach Ra0.2 μm, the surface gloss is excellent, and there is a high High reflectivity, effectively reducing part of the heat conduction. In another embodiment of the present application, a layer of high-reflective paint is coated on the inner and outer surfaces of the housing component 1 to reduce external heat radiation energy and reduce heat conduction inside and outside the sensing device.

The fluid inlet joint and the fluid outlet joint are respectively formed with connecting flanges 3 .

The interface assembly 2 is also provided with a transmitter connector 6 for connecting a transmitter. The induction circuit is connected to one side of the transmitter connector 6 through the transmitter body 2, and the other side of the transmitter connector 6 is connected to the transmitter. In order to adapt to the use in the ultra-low temperature medium industry, the interface component 2 can be welded with a length The transmitter connector 6 of 150mm, through the setting of this distance, can avoid the generation of condensed water vapor inside the transmitter at low temperature, eliminate the virtual connection of the transmitter's electronic connection, ensure the normal use temperature of the transmitter, and improve the flowmeter's temperature. Measurement accuracy.

Suitably, for the convenience of debugging and maintenance, the shell part 1 and the interface component 2 can be connected by threads. In order to ensure a more stable structure, the interface assembly 2 and the transmitter joint 6 can usually be welded.

According to the present invention, the aforementioned Coriolis mass flow sensor can be configured as a sensor of a mass flow meter, and the mass flow meter is also a transmitter, and the sensor and the transmitter pass through the transmitter joint located at the interface assembly 2 6, the transmitter connector 6 is preferably configured as a pipe connector with a length of at least 150 mm.

It should be noted that the mass flow signal collected by the Coriolis flow sensor is converted into an original electrical signal, which is transmitted to an external transmitter through the transmitter connector 6, and the original electrical signal is processed by the transmitter and converted into Electrical signals that meet the requirements are further transmitted.

In the performance test experiment, the applicant used the medium LNG (liquefied natural gas) to test the low temperature performance of the mass flow sensor, and the result was: if the existing flow meter is used, the temperature difference between the inlet and outlet of the sensor is 15°C, while using the mass flow sensor of the present invention, its The temperature difference between the inlet and outlet is only 4°C. Experiments have proved that the mass flow sensor of the present invention greatly improves the real-time performance and accuracy of temperature measurement of the flowmeter, ensures the accuracy of temperature compensation calculation of the transmitter, and improves the measurement performance of the flowmeter.

The above description is only a preferred embodiment of the present application and an illustration of the applied technical principle. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solution formed by the specific combination of the above-mentioned technical features, but should also cover the technical solution formed by the above-mentioned technical features without departing from the inventive concept. Other technical solutions formed by any combination of or equivalent features thereof. For example, a technical solution formed by replacing the above-mentioned features with technical features with similar functions disclosed in (but not limited to) this application.

Claims (15)

1. A coriolis mass flow sensor comprising:

a sensing assembly comprising a measuring tube (4) for guiding a fluid to be measured;

a housing part (1) in which the measuring tube (4) is arranged;

an interface assembly (2) having a housing connected to the housing part and provided with a fluid inlet connection and a fluid outlet connection for introducing or removing fluid into or from the measuring tube;

the connector assembly is characterized in that the connector assembly (2) is provided with a vacuumizing joint (5) communicated to the inside of the shell part (1), a sealed vacuum cavity is formed in the inside of the shell part, and the measuring tube (4) is accommodated in the vacuum cavity.

2. The coriolis mass flow sensor of claim 1 characterized in that the absolute pressure of said vacuum chamber is less than 5Pa, forming a corresponding vacuum insulation layer around the periphery of said measuring tube (4).

3. The coriolis mass flow sensor of claim 1 characterized in that said vacuum nipple (5) comprises a nipple (8) fixed in the housing of the interface assembly (2) and a valve body (7) threadedly connected to said nipple (8).

4. A coriolis mass flow sensor of claim 3 characterized in that said union nut (8) is configured with a tapered mount where it forms a tapered seal with said valve body (7).

5. A coriolis mass flow sensor of any one of claims 1 to 4 characterized in that said measuring tube (4) is of U-like configuration comprising two straight tube sections and one bent tube section in communication with said two straight tube sections in between.

6. The coriolis mass flow sensor of claim 5 characterized in that said bend segment is arcuate in extension having a central angle of greater than 180 degrees.

7. The coriolis mass flow sensor of claim 5, wherein said sensing assembly further comprises an excitation element disposed centrally in said bend section and a detection element disposed at each end of said bend section inboard of said U-like shape.

8. The coriolis mass flow sensor of any one of claims 1 to 4, characterized in that an inner and/or outer surface of the measuring tube (4) is configured as a BA-face.

9. A coriolis mass flow sensor of any one of claims 1 to 4, characterized in that the housing part (1) is of cylindrical sleeve construction.

10. Coriolis mass flow sensor of claim 9, characterized in that the inner and/or outer surface of the housing part (1) is configured as BA-face.

11. Coriolis mass flow sensor of claim 9 characterized in that the inner and/or outer surface of the housing part (1) is provided with a highly reflective coating.

12. Coriolis mass flow sensor according to any of claims 1 to 4, characterized in that the fluid inlet and outlet connections are each formed with a connecting flange (3).

13. The coriolis mass flow sensor of any one of claims 1 to 4 characterized in that said interface assembly (2) is further provided with a transmitter joint (6) for connecting to a transmitter.

14. A mass flowmeter comprising a sensor and a transmitter, wherein the sensor is configured as the coriolis mass flow sensor of any one of claims 1 to 13.

15. The mass flow meter of claim 14, wherein the sensor and transmitter are connected by a transmitter connection (6) provided at the interface assembly (2), the transmitter connection being configured as a pipe joint having a length of at least 150 mm.

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