Orifice plate flowmeter

Abstract

The invention discloses an orifice plate flowmeter, and belongs to the technical field of flowmeters.A detachable horn-shaped nozzle is installed in a penetrating hole in an orifice plate, a first sliding-out hole for the orifice plate and the nozzle to slide out is formed in one end of a shell, the end of the shell is fixedly connected with an auxiliary shell, and a sliding-in hole right opposite to the first sliding-out hole is formed in the end face of the auxiliary shell; a second sliding-out hole for the pore plate and the nozzle to slide out is formed in the side, away from the sliding-out hole, of the auxiliary shell, a first gear is rotationally installed in the shell, a second gear is rotationally installed in the auxiliary shell, and a first rack perpendicular to the axial direction of the nozzle is fixed to the position, close to the edge, of the pore plate. A sealing plate is slidably mounted at an opening of the sliding-in hole, a second rack is fixed to the position, close to the edge, of the sealing plate, and the second rack is meshed with a third gear rotationally mounted in the shell so that the nozzle on the hole plate can slide out of the auxiliary shell. The orifice plate flowmeter not only can well resist erosion of media, but also can directly take out the orifice plate on line, and is convenient to overhaul and maintain.

Description

Technical Field

[0001] The present invention relates to the technical field of flow meters, in particular to an orifice flow meter. Background Art

[0002] Orifice flowmeter is a commonly used flow measurement instrument, widely used in industrial production processes to measure the flow of various fluids, such as gas and liquid. Orifice flowmeters generally include several core components such as orifice plates, pressure measuring devices, and differential pressure measuring instruments. The orifice plate is a plate with a circular opening located in the center of the plate, and its diameter is smaller than the inner diameter of the pipe. The orifice flowmeter is mainly based on the throttling principle of fluid flow. When the fluid filling the pipe flows through the orifice plate in the pipe, the flow beam will form a local contraction at the orifice plate opening, and the flow rate will increase. According to the Bernoulli equation, the static pressure energy of the fluid will be converted into kinetic energy, thereby generating a static pressure difference before and after the orifice plate. There is a certain functional relationship between this static pressure difference and the flow rate of the fluid. By measuring the static pressure difference before and after the orifice plate, the flow rate of the fluid can be calculated; specifically, the flow rate is proportional to the square root of the pressure difference before and after the orifice plate.

[0003] When conveying and measuring media containing particulate impurities, such as shale gas, the circular opening of the orifice plate is easily eroded due to its high pressure and high sand content. This can easily cause blockage of the pressure lead pipe and inaccurate pressure measurement, thus affecting the metering accuracy of the orifice plate flowmeter. Therefore, the orifice plate must be frequently repaired and replaced. During repair and replacement, the flowmeter must be completely disassembled from the pipeline, and the outer casing and a series of accessories must be opened one by one to remove the orifice plate and replace it, which is very troublesome. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the present invention provides an orifice flowmeter to solve the problem in the existing technology that media containing particulate impurities such as shale gas easily corrode the orifice plate, and the flowmeter must be removed before the orifice plate can be inspected and replaced.

[0005] To achieve the above object, the present invention provides the following technical solutions: An orifice flowmeter comprises a housing and an orifice plate mounted in the housing, a detachably mounted nozzle is mounted in a perforation on the orifice plate, the nozzle orifice is a trumpet-shaped structure, and the nozzle supplies a medium to flow from the inlet end of the housing to the outlet end; one end of the housing is provided with a first slide-out hole for the orifice plate and the nozzle to slide out, and the housing is fixedly connected to a sub-housing at this end, and a slide-in hole is provided on the end surface of the sub-housing that is opposite to the first slide-out hole; a second slide-out hole is provided on the side of the sub-housing that is away from the slide-out hole for the orifice plate and the nozzle to slide out, and the second slide-out hole is sealed by a seal detachably mounted on the sub-housing. The closing strip is sealed; a first gear is rotatably installed in the outer shell, a second gear is rotatably installed in the auxiliary shell, and a first rack perpendicular to the nozzle axis is fixed at the edge of the orifice plate; a sealing plate is slidably installed on the orifice of the slide-in hole, and a second rack is fixed at the edge of the sealing plate, and the second rack is engaged with a third gear rotatably installed in the outer shell to drive the sealing plate to open the slide-in hole, and the first rack is engaged with the first gear and the second gear in sequence to make the nozzle on the orifice plate slide out of the auxiliary shell through the first slide-out hole, the slide-in hole, and the second slide-out hole.

[0006] Furthermore, the first gear is also engaged with the second rack. At the initial moment, the orifice plate and the sealing plate are spaced apart, and when the second rack moves with the sealing plate to completely expose the sliding hole, the orifice plate moves to the opening of the sliding hole; a gear tooth at the end of the second rack is elastically slidably mounted on the second rack by two return springs symmetrically arranged on both sides thereof.

[0007] Furthermore, the sealing plate has a Π-shaped strip groove in its interior, the length direction of the strip groove is parallel to the moving direction of the second rack, and the strip groove passes through the sealing plate on one side toward the third gear.

[0008] Furthermore, drainage pipe sections are coaxially threadedly installed in the inlet and outlet ends of the shell, and sealing gaskets are fixed on the ends of the two drainage pipe sections facing each other. When the drainage pipe sections are screwed into the corresponding ports of the shell to the limit, the two sealing gaskets are squeezed into contact with the corresponding end faces of the orifice plate, and the nozzle is located on the inner side of the sealing gasket.

[0009] Furthermore, a positioning ring is provided at one end of the nozzle, and a cylindrical threaded section is provided on the nozzle. When the nozzle is axially inserted into the through-hole, the positioning ring is squeezed into contact with the sink at one end of the through-hole through a sealing ring, and the other end of the nozzle extends out of the orifice plate, and a threaded pressure ring is threadedly sleeved on the cylindrical threaded section, which fixes the nozzle on the orifice plate.

[0010] Furthermore, when the threaded pressing ring is rotated to the limit, the threaded pressing ring is fixed on the orifice plate by screwing a fastening bolt into a screw hole reserved on the end surface of the threaded pressing ring.

[0011] Furthermore, one first rack is fixed on each of the upper and lower edges of the orifice plate, and two first gears and two second gears are rotatably installed respectively; one second rack is fixed on each of the upper and lower edges of the sealing plate, and the two second racks correspond to the two third gears arranged upper and lower respectively.

[0012] Furthermore, the sealing plate is slidably fitted with a contact plate, and the contact plate is fixed on the end face of the auxiliary shell; Z-shaped guide rails are respectively fixed at the upper and lower edges of the contact plate, and the upper and lower ends of the sealing plate are respectively L-shaped to slidably fit with the guide rails, and the contact plate is provided with a through hole that is consistent in shape and size with the sliding hole, and the through hole is aligned with the sliding hole.

[0013] Furthermore, the gear shafts of all the gears are exposed outside the orifice flowmeter and are threadedly fastened with locking nuts to fix the gear shafts in an axially extruded manner.

[0014] Furthermore, a diaphragm-type pressure gauge and a temperature sensor are also provided on the shell.

[0015] Beneficial effects: The present invention provides an orifice flowmeter with the following beneficial effects: the orifice flowmeter can not only effectively resist the erosion under high pressure of shale gas, but also has a more stable and reliable structure, and can quickly disassemble and replace the orifice plate online, and timely repair and maintenance. Specifically, the nozzle in the present invention adopts an arc-shaped trumpet-shaped structure, which greatly reduces the erosion of shale gas. In the application conditions, it fully meets the erosion of sand-containing shale gas, and it has the function of replacing the orifice plate online, or replacing the nozzle on the orifice plate. Even if the orifice plate or nozzle is damaged, it can be directly replaced online without disassembling the entire flowmeter, and repair and maintenance are very convenient. In addition, diaphragm pressure measurement can also be used. Compared with the traditional pressure-inducing pipe for measuring pressure and the pressure-inducing pipe having a very small diameter, it is less likely to cause the pressure-inducing pipe to be blocked in the sand-containing shale gas working condition, and the pressure measurement is more accurate, preventing pipeline blockage. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a three-dimensional structural diagram of the appearance of the present invention; Figure 2-Figure 3 Schematic diagrams of the explosion structure of the present invention from two perspectives; Figure 4 A perspective view of the mounting element at the end of the auxiliary housing; Figure 5 is a three-dimensional diagram of the auxiliary housing; Figure 6 for Figure 2 A top view of the relative installation position structure of the first gear, the second gear and the first rack; Figure 7This is a schematic diagram of the first structure of two rack linkage; Figure 8 for Figure 7 A schematic top view of a portion of the structure shown; Figure 9 It is a schematic diagram of the orifice plate sliding into the contact plate; Figure 10 This is a schematic diagram of the second structure of two rack linkage; Figure 11 for Figure 10 A schematic top view of a portion of the structure shown; Figure 12 It is an axial cross-sectional view of the present invention at the housing; Figure 13 is a structural schematic diagram of the second rack; Figure 14 This is a schematic diagram of the third structure of two rack linkage.

[0017] In the figure: the outer shell 1, the auxiliary shell 2, the sliding hole 201, the orifice plate 3, the nozzle 4, the cylindrical threaded section 401, the first gear 5, the locking screw sleeve 6, the auxiliary screw sleeve 6a, the closing strip 7, the first rack 8, the second rack 9, the third gear 10, the sealing plate 11, the strip groove 1101, the guide rail 12, the contact plate 13, the through hole 1301, the positioning ring 14, the threaded pressure ring 15, the drainage pipe section 16, the sealing gasket 17, the fastening bolt 18, the valve 19, the plug 20, the slide 21, the gear teeth 22, and the return spring 23. DETAILED DESCRIPTION

[0018] This specification will clearly and completely express the technical solutions in the following embodiments based on the drawings of the embodiments of the present invention. The implementation methods described in this specification are only some of the embodiments of the present invention, not all of them. All other embodiments derived from these embodiments in this application by persons of ordinary skill in the art without any creative effort should fall within the scope of protection of the present invention.

[0019] like Figure 1-3The orifice flowmeter shown in the figure specifically includes a housing 1 and an orifice plate 3 installed in the housing 1. A detachable nozzle 4 is installed in the perforation of the orifice plate 3. The nozzle 4 has a trumpet-shaped structure, and the outlet end of the nozzle 4 is a circular opening so that the nozzle 4 can be disassembled when necessary to avoid the problem that the hole of the orifice plate 3 for shale gas to flow out affects the metering due to erosion. In this embodiment, the nozzle 4 allows shale gas to flow from the inlet end to the outlet end of the housing 1, that is, the outlet end of the nozzle 4 is used as the circular opening of the orifice plate 3, so as to achieve detachable replacement and improve erosion resistance. Specifically, in this embodiment, one end of the housing 1 has a first sliding-out hole (not shown in the figure) for the orifice plate 3 and the nozzle 4 to slide out. Its structural shape is adapted to the orifice plate 3 so that the orifice plate 3 can freely pass through the housing 1, and the housing 1 is fixedly connected to the sub-housing 2 at this end. The two can be connected by respective integrally formed rectangular flange plates. A sliding-in hole 201 is provided on the end face of the sub-housing 2, which is opposite to the first sliding-out hole. The structure of this sliding-in hole 201 is as shown in FIG. Figure 5 As shown. A second sliding hole for the orifice plate 3 and the nozzle 4 to slide out is provided on the side of the sub-shell 2 away from the sliding hole. The second sliding hole is blocked by a sealing strip 7 detachably mounted on the sub-shell 2 and is opened only when the nozzle 4 needs to be replaced. The setting of the sub-shell allows the orifice plate 3 to be completely removed from the outer shell 1 so that the orifice flowmeter can be fully maintained. For example, the internal condition of the outer shell 1 can be fully inspected through its two ports. In the process of removing the orifice plate 3 mentioned below, the orifice plate 3 can transition and move within the sub-shell 2 to extend the moving distance, so that the position where the orifice plate 3 is removed is as far away from the outer shell 1 as possible, thereby away from the delivery pipeline where the orifice flowmeter is located, making it easier to replace the nozzle 4. At the same time, as Figure 2-Figure 3 As shown, a first gear 5 is rotatably mounted in the housing 1, and a second gear (not shown in the figure) is rotatably mounted in the auxiliary housing 2. Figure 2 A secondary screw sleeve 6a is shown, which is coaxially arranged with the second gear. The second gear is similar to the first gear 5 in the mounting structure. In the specific production, a first rack 8 perpendicular to the nozzle 4 axis is fixed to the edge of the orifice plate 3. If two first racks 8 are provided, they are respectively located at the upper and lower edges of the orifice plate 3. In this embodiment, Figure 2-Figure 4A sealing plate 11 is slidably mounted at the opening of the slide-in hole 201. The specific sliding structure design is as follows: the sealing plate 11 is slidably fitted with a contact plate 13, which is fixed to the end face of the auxiliary housing 2. Furthermore, Z-shaped guide rails 12 are fixed to the upper and lower edges of the contact plate 13. The upper and lower ends of the sealing plate 11 are both L-shaped, so as to slidably fit with the guide rails 12 and guide the sealing plate 11 to move perpendicularly to the direction of movement of the orifice plate 3. Furthermore, a through hole 1301 having the same shape and size as the slide-in hole 201 must also be provided on the contact plate 13. The through hole 1301 is aligned with the slide-in hole 201, so that when the through hole 1301 of the contact plate 13 is fully exposed by the sealing plate 11, the slide-in hole 201 is also fully exposed simultaneously.

[0020] A second rack 9 is fixed to the edge of the sealing plate 11, and the second rack 9 is engaged with a third gear 10 rotatably mounted in the housing 1 to drive the sealing plate 11 to move in a direction perpendicular to the sliding direction of the orifice plate 3, thereby opening the slide-in hole 201, allowing the orifice plate 3 and its nozzle 4 to enter the slide-in hole 201, and then slide out of the sub-housing 2. In more detail, during the movement of the orifice plate 3, the first rack 8 is engaged with the first gear 5 and the second gear in sequence, that is, the first gear 5 can be rotated, and then the orifice plate 3 can be slid, and then engaged with the second gear, so that the nozzle 4 on the orifice plate 3 can slide out of the sub-housing 2 through the first slide-out hole, the slide-in hole 201, and the second slide-out hole, so that it can be disassembled, replaced, or inspected and cleaned.

[0021] In this embodiment, Figure 7-Figure 9 As shown, the first rack 8 and the second rack 9 are controlled in linkage, that is, the first gear 5 is also meshed with the second rack 9. At this time, the first rack 8 and the second rack 9 can be moved simultaneously by rotating the first gear 5, and the movement directions of the two are perpendicular to each other. The second rack 9 brings the sealing plate 11 to expose the sliding hole 201. Accordingly, the first rack 8 and the orifice plate 3 move toward the sliding hole 201. As one of the implementation structures, at the initial moment, the orifice plate 3 and the sealing plate 11 are kept apart, and are not as Figure 6 Keep in contact as shown, but as Figure 7-Figure 8 When the second rack 9 moves with the sealing plate 11 to completely expose the sliding hole 201, as shown in FIG. Figure 9 , the orifice plate 3 moves to the orifice of the sliding hole 201. Moreover, it is very important that Figure 13 As shown, a gear tooth 22 at the end of the second rack 9 must be elastically slidably mounted on the second rack 9 through two return springs 23 symmetrically arranged on both sides thereof, so that when the orifice plate 3 retreats and slides into the housing 1, it will not be stuck because the end of the second rack 9 or the side of the sealing plate 11 conflicts with the orifice plate 3. In addition, the sealing plate 11 and the second rack 9 can also have a longer length without having to be as Figure 8 and Figure 11In this way, the sealing plate 11 and the second rack 9 cannot face the sliding hole 201 in the normal state, and the second rack 9 and the sealing plate 11 can only be set with their axes biased to one side of the sliding hole 201 in the normal state. Figure 12 As shown, a ram 21 can be designed on the upper and lower sides of the shell 1 or the auxiliary shell 2, or if the structure allows, the upper and lower sides of the orifice plate 3 can be directly in sliding contact with the upper and lower sides of the shell 1 and the auxiliary shell 2.

[0022] In order to ensure that the orifice plate 3 smoothly enters the sliding hole 201 under the linkage mechanism of the two racks, further Figure 10-11 As shown, a Π-shaped strip groove 1101 is provided in the sealing plate 11. The length direction of the strip groove 1101 is parallel to the moving direction of the second rack 9, and the strip groove 1101 passes through the side of the sealing plate 11 facing the third gear 10, so that when the orifice plate 3 slides toward the sealing plate 11, for example Figure 11 As shown, when the orifice plate 3 moves to the right and the sealing plate 11 and the second rack 9 move upward, one side of the orifice plate 3 can enter the strip groove 1101, and when the second rack 9 slides relatively until the orifice plate 3 leaves the strip groove 1101, the sliding hole 201 is completely exposed, that is, when the through hole 1301 mentioned above is exposed.

[0023] When the two racks are linked, in addition to the above two structural designs, you can also press Figure 14 The structure shown is designed, and a pair of first gears 5 are arranged at intervals on the upper and lower sides, that is, the position of the second gear is adjusted to between each pair of first gears 5, and the three gears are arranged at an angle, so that the distance between the end of the first rack 8 and the sealing plate 11 can be increased, so that the second rack 9 has sufficient moving stroke, which can better expose the sliding hole 201 in advance.

[0024] Regarding the movement control of the orifice plate 3 and the sealing plate 11, whether to design them as linkage or not, and which of the above-mentioned multiple implementation structures to choose, those skilled in the art can make a choice according to actual needs. The present invention recommends adopting linkage control on the premise of meeting other design requirements.

[0025] In order to achieve better sealing, Figure 1-Figure 3 as well as Figure 12As shown, a drainage pipe section 16 is coaxially threadedly installed in the inlet and outlet ends of the housing 1. The drainage pipe section 16 can be made into a structure with a flange plate for easy installation and positioning. In practice, the drainage pipe section 16 can be made into a corresponding shape on the side facing the orifice plate 3 according to specific needs, and is not limited to a circular tube shape. In addition, a sealing gasket 17 is fixed to the ends of the two drainage pipe sections 16 facing each other. When the drainage pipe sections 16 are screwed into the corresponding ports of the housing 1 to the limit, the two sealing gaskets 17 are squeezed into contact with the corresponding end faces of the orifice plate 3 to achieve sealing at the nozzle 4. Moreover, the nozzle 4 is located on the inner side of the sealing gasket 17, so that the shale gas can only flow out through the nozzle 4.

[0026] As a specific implementation structure, such as Figure 12 A positioning ring 14 is provided at one end of the nozzle 4, and a cylindrical threaded section 401 is provided on the nozzle 4. When the nozzle 4 is axially inserted into the through-hole, the positioning ring 14 is squeezed into contact with the sink at one end of the through-hole through a sealing ring (not shown in the figure), while the other end of the nozzle 4 extends out of the orifice plate 3. A threaded pressure ring 15 is threadedly sleeved on the cylindrical threaded section 401. When the threaded pressure ring 15 is tightened to the limit, the nozzle 4 is fixed to the orifice plate 3, thereby achieving fixed installation of the nozzle 4. In order to improve the fixing reliability, when the threaded pressure ring 15 is rotated to the limit, a fastening bolt 18 is screwed into the screw hole reserved on its end face, thereby firmly fixing the threaded pressure ring 15 to the orifice plate 3.

[0027] In all the above embodiments, Figure 2-Figure 3 , the first rack 8 used is fixed with one on each of the upper and lower edges of the orifice plate 3, and two first gears 5 and two second gears are respectively rotated and installed to improve the stability and reliability of the movement. Similarly, the second rack 9 is fixed with one on each of the upper and lower edges of the sealing plate 11, and the two second racks 9 correspond to the two third gears 10 arranged above and below. When the orifice plate 3 is moved into place, its position needs to be fixed. In this design, the gear shafts of all gears are exposed outside the orifice flowmeter, and are threadedly fastened with locking screws 6, that is, the locking screws 6 are screwed onto the surface of the corresponding outer shell 1 or the auxiliary shell 2 to fix the gear shaft by axial extrusion to prevent the corresponding gear from rotating. The auxiliary screw 6a mentioned above is the locking screw 6 on the gear shaft of the second gear.

[0028] Finally, the remaining functional components of the orifice flowmeter can be configured with reference to the prior art, such as the pressure-taking device, the differential pressure measuring instrument, and the corresponding transmitter for converting the differential pressure to the flow rate. This embodiment will not be described in detail. In practice, a diaphragm-type pressure gauge and a temperature sensor can be provided on the housing 1. The diaphragm-type pressure measurement is used, and the pressure is transmitted to the calculation model for flow conversion to prevent pipeline blockage. For example, a valve 19 can be installed on the housing 1 to connect an external detection element such as a pressure-taking element, and a sampling hole closed by a screw plug 20 can be provided. A temperature sensor can be installed after removing the screw plug 20.

[0029] It should be explained here that, in this specification, terms such as first and second are only used to distinguish one feature from another, and do not mean that there is a certain relationship or order between these technical features. The terms "include" and "comprise" refer to the inclusion of one or certain technical means or features, specifically meaning that there are other existing or non-existing technical features that have not been included. The discussion in the above embodiments is only a referential example for the present invention, and is by no means the only restrictive constraint feature. Those skilled in the art should understand that, without departing from the technical content recorded in all claims of this application, some simple replacements and modifications can be made, thereby changing or becoming equivalent to other specific embodiments and application scenarios. However, no matter how the adaptive changes are made, these embodiments will inevitably fall within the scope of protection of the present invention.

Claims

1. An orifice flowmeter comprising a housing (1) and an orifice plate (3) mounted in the housing (1), characterized in that: A detachably mounted nozzle (4) is installed in the perforation on the orifice plate (3), the spray hole of the nozzle (4) being a trumpet-shaped structure, and the nozzle (4) allows the medium to flow from the inlet end toward the outlet end of the housing (1); one end of the housing (1) is provided with a first slide-out hole for the orifice plate (3) and the nozzle (4) to slide out, and the end of the housing (1) is fixedly connected to a sub-housing (2), and a slide-in hole (201) facing the first slide-out hole is provided on the end surface of the sub-housing (2); a second slide-out hole for the orifice plate (3) and the nozzle (4) to slide out is provided on the side of the sub-housing (2) facing away from the slide-out hole, and the second slide-out hole is blocked by a closing strip (7) detachably mounted on the sub-housing (2); A first gear (5) is rotatably mounted in the housing (1), a second gear is rotatably mounted in the auxiliary housing (2), a first rack (8) perpendicular to the axial direction of the nozzle (4) is fixed to the edge of the orifice plate (3); a sealing plate (11) is slidably mounted on the opening of the slide-in hole (201), a second rack (9) is fixed to the edge of the sealing plate (11), the second rack (9) is engaged with a third gear (10) rotatably mounted in the housing (1) to drive the sealing plate (11) to open the slide-in hole (201), the first rack (8) is engaged with the first gear (5) and the second gear in sequence, so that the nozzle (4) on the orifice plate (3) slides out of the auxiliary housing (2) through the first slide-out hole, the slide-in hole (201), and the second slide-out hole.

2. The orifice flowmeter according to claim 1, characterized in that: The first gear (5) is also engaged with the second rack (9). At the initial moment, the orifice plate (3) and the sealing plate (11) are spaced apart, and when the second rack (9) moves with the sealing plate (11) to completely expose the sliding hole (201), the orifice plate (3) moves to the opening of the sliding hole (201); a gear tooth (22) at the end of the second rack (9) is elastically slidably mounted on the second rack (9) by two return springs (23) symmetrically arranged on both sides thereof.

3. The orifice flowmeter according to claim 2, characterized in that: The sealing plate (11) has a Π-shaped strip groove (1101) therein, the length direction of the strip groove (1101) is parallel to the moving direction of the second rack (9), and the strip groove (1101) passes through the sealing plate (11) toward the side of the third gear (10).

4. The orifice flowmeter according to claim 1, characterized in that: Drainage pipe sections (16) are coaxially threadedly installed in the inlet and outlet ends of the housing (1), and sealing gaskets (17) are fixed to the ends of the two drainage pipe sections (16) facing each other. When the drainage pipe sections (16) are screwed into the corresponding ports of the housing (1) to the limit, the two sealing gaskets (17) are in extrusion contact with the corresponding end faces of the orifice plate (3), and the nozzle (4) is located on the inner side of the sealing gasket (17).

5. The orifice flowmeter according to claim 1, characterized in that: One end of the nozzle (4) has a positioning ring (14), and the nozzle (4) has a cylindrical threaded section (401). When the nozzle (4) is axially inserted into the through hole, the positioning ring (14) is in squeeze contact with the sink at one end of the through hole through a sealing ring. The other end of the nozzle (4) extends out of the orifice plate (3), and a threaded pressure ring (15) is threadedly sleeved on the cylindrical threaded section (401). The threaded pressure ring (15) fixes the nozzle (4) on the orifice plate (3).

6. The orifice flowmeter according to claim 5, characterized in that: When the threaded pressing ring (15) is rotated to the limit, the threaded pressing ring (15) is fixed on the orifice plate (3) by screwing a fastening bolt (18) into a screw hole reserved on the end face of the threaded pressing ring (15).

7. The orifice flowmeter according to claim 1, characterized in that: The first rack (8) is fixed one at each of the upper and lower edges of the orifice plate (3), and two first gears (5) and two second gears are rotatably mounted thereon respectively; the second rack (9) is fixed one at each of the upper and lower edges of the sealing plate (11), and the two second racks (9) correspond to the two third gears (10) arranged above and below respectively.

8. The orifice flowmeter according to claim 1, characterized in that: The sealing plate (11) is fitted with a contact plate (13) in a sliding manner, and the contact plate (13) is fixed on the end face of the auxiliary housing (2); a Z-shaped guide rail (12) is fixed at the upper and lower edges of the contact plate (13); the upper and lower ends of the sealing plate (11) are both L-shaped to slide with the guide rail (12); the contact plate (13) is provided with a through hole (1301) of the same shape and size as the sliding hole (201), and the through hole (1301) is aligned with the sliding hole (201).

9. The orifice flowmeter according to claim 1, characterized in that: The gear shafts of all the gears are exposed outside the orifice flowmeter and are threadedly fastened with locking screw sleeves (6) to fix the gear shafts in an axially extruding manner.

10. The orifice flowmeter according to claim 1, characterized in that: The housing (1) is also provided with a diaphragm-type pressure gauge and a temperature sensor.

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