Multi-point matrix type square double-venturi structure

Abstract

The utility model discloses a flow guide pipe which is arranged and vertically extends into a pipeline to be measured, a purging interface and a differential pressure measurement interface are respectively arranged at the port of the flow guide pipe, and a plurality of groups of measurement units for measuring fluid parameters in the flow guide pipe are arranged at the extending end of the flow guide pipe. Each group of measuring units comprises a branch pipeline, the branch pipeline is obliquely arranged on the side of the flow guide pipe, and one of two measuring devices, namely a negative pressure venturi tube which is used for measuring negative pressure related parameters and is obliquely arranged along the direction of the pipeline, and a negative pressure venturi tube which is used for measuring negative pressure related parameters are respectively arranged at the end of the branch pipeline; and the other positive pressure square venturi tube is used for measuring positive pressure related parameters and is vertically arranged. The device is reasonable in structural design, the measured differential pressure value is increased, the flow field is stabilized, the blockage problem is solved, data accuracy is ensured, a power plant is assisted to reasonably control the air-coal ratio, cost reduction and efficiency improvement are achieved, and powerful support is provided for sustainable development.

Description

Technical Field

[0001] This utility model relates to the field of measuring instrument structure technology, specifically a multi-point matrix square double Venturi structure. Background Technology

[0002] During the operation of power plant units, the air volume is measured at the primary air, secondary air, return air, coal feeding air, and flue gas locations. Primary air, also known as pulverized coal air, provides pulverized coal fuel for combustion inside the boiler. Primary air is divided into cold primary air and hot primary air. Hot primary air is used to ensure that the pulverized coal has a certain temperature when it enters the boiler, thereby improving energy utilization. Cold primary air is used to adjust the temperature of hot primary air to ensure maximum heat exchange effect. Because coal mills have many pulverized coal feeding pipes, the straight pipe sections are relatively short in the design. In addition to impurities in the air itself, there is also a small amount of pulverized coal at the outlet of the pulverized coal pipe, making the measurement of primary air volume very complex. Secondary air: also known as combustion air, provides oxygen for the combustion of pulverized coal inside the boiler. It is generally blown in by the fan, passes through the air preheater, and enters the furnace directly, where it gradually mixes with the primary air. Since it contains air, there are also many straight pipe sections, making the measurement of this part of the air volume less difficult. Return air: flue gas at a certain flow rate enters the spiral cyclone separator, where heavier pulverized coal particles fall off and are blown into the boiler by the return air for complete combustion. Coal spreading air: allows the coal from the coal feeder to be better spread into the furnace, preventing accumulation and improving combustion efficiency. It is generally provided by a dedicated coal spreading fan, or hot primary air is used as the coal spreading air. Flue gas location: generally installed on the horizontal flue in front of the chimney. The straight pipe section is short, there is a lot of dust, and the flow field is unstable, making the measurement of this part more difficult and is also the focus of this study.

[0003] Common measuring devices include: airfoil-type airflow measuring devices, which are suitable for measuring the airflow of primary and secondary air in boilers, but they generate significant pressure loss, are not energy-efficient, and are very difficult to clean once the pressure taps are clogged; Venturi tubes are widely used for boiler airflow measurement, calculating airflow by measuring the pressure difference of the fluid within them; however, when selecting this device for large-diameter pipes in power plants, especially square pipes, the cost is too high, and square pipes are difficult to manufacture, so its practical application is limited; averaging pitot tube flow meters (Barrel-type flow meters) calculate airflow by measuring the pressure difference at multiple points within the cross-section of the pipe, but they are less effective for long straight pipe sections. The requirements for airflow are quite strict, but the actual situation on site often makes it difficult to meet these requirements, which leads to frequent instability in measurement. Thermal mass flow meters measure airflow using the principle of thermal diffusion and are more suitable for high-temperature and high-pressure environments. Ultrasonic gas flow meters measure wind speed and then calculate airflow by measuring the time difference of ultrasonic wave propagation. Similar to Venturi tubes, they are too expensive and difficult to manufacture for large-diameter pipes, especially square pipes, so they are not widely used. Although matrix airflow measurement devices solve the problem of flow field instability of averaging pitot tube flow meters, the differential pressure generated in most measurements is small, which reduces the accuracy of the measurement.

[0004] The challenges of measuring air volume in power plants are not only reflected in the measuring equipment itself, but are also affected by a variety of external factors.

[0005] From the perspective of the measuring devices themselves, clogging and wear are prominent issues. Due to the high dust content in the primary and secondary air ducts of power plants, the measuring devices are prone to clogging and wear, which in turn affects the measurement accuracy. For example, the primary and secondary air measuring devices of coal-fired power plant boilers often experience clogging problems due to excessive dust content, making it difficult for operators to accurately judge the boiler's operating condition.

[0006] Limitations in pipeline layout are also an important factor. Many power plants are constrained by space and have non-standard pipeline designs, such as insufficient straight pipe sections and pipe bends. These problems make it difficult to install measuring devices properly, or even if they are installed, the measurement accuracy will be greatly reduced. For example, the primary air ducts of some power plant boilers are compact and lack sufficient straight pipe sections, making it impossible for measuring devices to work properly.

[0007] Measurement errors and accuracy issues are equally important. The properties of fluids are very complex. Not only does the dust content change, but the flow rate is also unstable. In addition, the design of the measuring device is unreasonable. These factors work together to cause large measurement errors. For example, the primary air volume measuring device in some power plants has a large measurement deviation due to large changes in the opening degree.

[0008] High maintenance costs are also a major concern for power plants. Traditional measuring devices require frequent cleaning and maintenance, which undoubtedly increases maintenance costs. For example, traditional devices such as Barcol tubes require regular manual purging. While new multi-point array measuring devices reduce maintenance workload to some extent, their initial investment costs are high.

[0009] Equipment selection and installation issues can also have a serious impact on measurement results. If the equipment is not selected properly or not installed correctly, it will lead to distorted measurement data. Some power plants have encountered problems in this regard, resulting in measurement results that cannot accurately reflect the actual air volume.

[0010] Low automation is also a significant shortcoming of current power plant air volume measurement systems. Many power plant air volume measurement systems lack automation functions and rely on manual operation, which is not only inefficient but also prone to errors. For example, traditional measuring devices require manual purging, which increases the difficulty of operation and the possibility of errors.

[0011] To address these issues, the power plant has undertaken technological upgrades, such as adopting anti-clogging and self-cleaning devices and optimizing pipeline design. The development of the multi-point matrix square double Venturi structure described in this application has yielded significant results, improving the measured differential pressure value, stabilizing the flow field, solving the clogging problem, ensuring data accuracy, and helping the power plant to rationally control the air-coal ratio, thereby reducing costs and increasing efficiency, and providing strong support for sustainable development. Utility Model Content

[0012] The purpose of this invention is to overcome the defects and shortcomings of the existing technology and provide a multi-point matrix square double Venturi structure, which solves the various problems existing in the existing technology.

[0013] To achieve the above objectives, this utility model provides the following technical solution:

[0014] A multi-point matrix-type square double Venturi structure includes a guide tube that extends vertically into the pipe to be measured. The guide tube has a purge port and a differential pressure measurement port at its ends. Multiple sets of measurement units for measuring fluid parameters within the guide tube are installed at the insertion end of the guide tube. Each measurement unit includes a branch pipe, which is inclined along the side of the guide tube. Two types of measuring devices are installed at the ends of the branch pipes: a negative pressure Venturi tube inclined along the pipe direction for measuring negative pressure-related parameters, and a vertically arranged positive pressure square Venturi tube for measuring positive pressure-related parameters. The positive pressure square Venturi tube and the negative pressure Venturi tube are combined in a one-to-one correspondence.

[0015] The interface axis of the purging port is parallel to the axis of the guide tube, and the interface axis of the differential pressure measurement port should be perpendicular to the axis of the guide tube.

[0016] The installation position of the pipe to be tested is provided with an installation hole, and a flange is welded at the installation hole position. The transition part of the guide pipe extension end is sealed to the pipe to be tested through a flange and a gasket.

[0017] Both the guide pipe and the branch pipe have square cross-sections.

[0018] The inclination angle between the branch pipe and the guide pipe is 65-85 degrees.

[0019] The guide tube is equipped with eight sets of measuring units for measuring fluid parameters inside the guide tube. Among the eight sets of measuring units, positive pressure square venturi tubes and negative pressure venturi tubes are combined in a one-to-one correspondence to form four sets. The four sets are symmetrically arranged on both sides of the guide tube.

[0020] The inner sides of the positive pressure square venturi tube and the negative pressure venturi tube.

[0021] The negative pressure venturi tube includes a square pipe, the upper middle part of which is connected to a branch pipe, and a differential pressure sensor is installed inside the pipe for accurately measuring the pressure difference generated by the venturi effect inside the pipe.

[0022] The positive pressure square Venturi tube includes a square pipe with beveled ends at the top and bottom, the bevels facing the direction of airflow entry. The middle inner side of the pipe is connected to a branch pipe. A differential pressure sensor is installed inside the pipe to accurately measure the pressure difference generated by the Venturi effect within the pipe.

[0023] Compared with the prior art, the beneficial effects of this utility model are:

[0024] To effectively solve the difficulties in wind measurement mentioned above, this utility model adopts the following structure:

[0025] 1. The negative pressure side adopts a double Venturi structure. According to Bernoulli's law, the flow rate of the medium entering the Venturi increases and the pressure decreases, which effectively increases the negative pressure value and ultimately increases the product differential pressure value.

[0026] 2. The product's vertical and inclined structural design reduces the possibility of clogging to a limited extent. In addition, the upper part of the product adopts a purging design, which can effectively prevent clogging.

[0027] 3. The product's positive pressure test adopts multi-point measurement, and the negative pressure test also adopts multi-point double Venturi to equalize the product's differential pressure, effectively solving the problems of insufficient straight pipe section and unstable flow.

[0028] Practical testing results have proven that the structure of this application significantly improves the measured differential pressure value, stabilizes the flow field, and solves the problem of easy clogging caused by dust in the medium, as well as the limitations of traditional air volume measurement methods in terms of accuracy and adaptability. Through multi-point measurement, it can more accurately reflect changes in the flow field and improve measurement accuracy. The double Venturi tube design reduces pressure loss and is suitable for applications requiring low pressure loss. This structure is small in size, easy to install and maintain, highly adaptable, and suitable for circular or rectangular pipes. In addition, it has good anti-clogging performance and is particularly suitable for measurement environments with dusty airflow, making it an excellent choice for power plant air volume measurement. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of this utility model.

[0030] Figure label:

[0031] 1. Pipe to be tested; 2. Guide pipe; 3. Purge interface; 4. Differential pressure measurement interface; 5. Branch pipe; 6. Negative pressure square Venturi tube; 7. Positive pressure square Venturi tube; 8. Beveled end. Detailed Implementation

[0032] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present utility model.

[0033] See appendix Figure 1 A multi-point matrix-type square double Venturi structure includes a guide tube 2 that extends vertically into the pipe to be measured 1. A purge port 3 and a differential pressure measurement port 4 are respectively provided at the ends of the guide tube 2. Multiple sets of measurement units for measuring fluid parameters within the guide tube 2 are provided at the extended end of the guide tube 2. Each measurement unit includes a branch pipe 5, which is inclined to one side of the guide tube 2. Two types of measuring devices are installed at the ends of the branch pipes 5: a negative pressure square Venturi tube 6 inclined along the pipe direction for measuring negative pressure-related parameters, and a positive pressure square Venturi tube 7 vertically positioned for measuring positive pressure-related parameters. The positive pressure square Venturi tube 7 and the negative pressure square Venturi tube 6 are combined in a one-to-one correspondence.

[0034] Furthermore, the interface axis of the purge port 3 is parallel to the axis of the guide pipe 2, and the interface axis of the differential pressure measurement port 4 should be perpendicular to the axis of the guide pipe 2. The design of the purge port's interface axis to be parallel to the axis of the guide pipe aims to reduce the direct impact of fluid flow on the purge port during flow within the guide pipe, ensuring the stability of the purge operation. Conversely, the interface axis of the differential pressure measurement port should be perpendicular to the axis of the guide pipe. This design avoids interference from the dynamic pressure generated by fluid impact on static pressure measurement through a vertical layout, thus ensuring the accuracy of pressure measurement data. An installation hole is provided at the installation position of the pipe to be tested 1, and a flange is welded at the installation hole. The transition point of the guide pipe 2's insertion end is sealed to the pipe to be tested 1 via a flange and gasket. The flange enables the connection between the guide pipe and the pipe to be tested, and the gasket seal ensures the airtightness of the connection point during installation.

[0035] Furthermore, both the guide pipe 2 and the branch pipe 5 have square cross-sections. The square cross-section reduces eddies and resistance during fluid flow within the pipe, resulting in a more uniform fluid distribution and improved flow efficiency. Simultaneously, the square pipe structure facilitates installation and fixation, contributing to enhanced stability and reliability of the entire pipeline system. The inclination angle between the branch pipe 5 and the guide pipe 2 is 65-85 degrees. This angle range is determined based on fluid mechanics principles; when fluid flows through the inclined pipe, this angle effectively utilizes the gravitational component to promote smooth fluid flow, reducing turbulence and energy loss, while also preventing fluid from impacting the pipe wall or causing backflow due to excessively steep angles. This design significantly improves transport efficiency in engineering applications while reducing pipe wear and noise, ensuring long-term stable system operation.

[0036] Furthermore, eight sets of measuring units for measuring fluid parameters within the guide tube 2 are installed at its inlet end. Among these eight sets, four sets are formed by one-to-one combinations of positive-pressure square Venturi tubes 7 and negative-pressure square Venturi tubes 6, symmetrically arranged in pairs on both sides of the guide tube 2. The positive-pressure square Venturi tubes 7 and negative-pressure square Venturi tubes 6 are located inside each other. The negative-pressure Venturi tube device is mainly composed of square pipes, and its design principle is based on the Venturi effect—when fluid flows through the contraction section of the pipe, the increased flow velocity leads to a decrease in static pressure, thus creating a pressure difference within the pipe. Specifically, the upper middle part of this square pipe connects to a branch pipe, forming a fluid contraction-diffusion flow path. When the fluid flows through the contraction section, the flow velocity increases and the pressure decreases; after passing through the diffusion section, the flow velocity recovers and the pressure rises again. To accurately capture this pressure change process, a high-precision differential pressure sensor is installed inside the pipeline. This sensor can measure the pressure difference between the constriction and diffusion sections of the pipeline in real time. By quantitatively relating the pressure difference to the flow velocity, it provides crucial data support for fluid flow calculation and negative pressure monitoring. The positive pressure square Venturi tube device mainly consists of a square pipe. Its design is based on the Venturi effect principle—when fluid flows through the constriction section of the pipeline, the increased flow velocity leads to a decrease in static pressure, thus creating a measurable pressure difference between the constriction section and the throat or diffusion section. Both the upper and lower ends of this square pipe are beveled, with the bevel precisely facing the airflow inlet direction. This structure effectively reduces local resistance when the airflow enters, allowing the fluid to smoothly and rapidly enter the constriction section, thereby improving the stability and accuracy of the pressure difference measurement. The inner middle of the pipe connects to a branch pipe through a specific interface. The branch pipe is used to guide the fluid or serve as a pressure transmission path. To accurately measure the pressure difference generated by the Venturi effect, a high-precision differential pressure sensor is installed inside the pipeline. This sensor can capture the pressure change between the contraction section and a reference position such as the throat or expansion section in real time, and convert the data into a quantifiable signal output, providing key parameter basis for flow calculation, system monitoring or process control.

[0037] The design principle of the aforementioned multi-point matrix square double Venturi structure is based on the fundamental theory of fluid mechanics, combining Bernoulli's equation and the continuity equation; its design features include:

[0038] 1. Multi-point measurement and matrix layout: This structure employs a multi-point measurement method, arranging multiple measurement points on the pipe cross-section to improve measurement accuracy and stability. This matrix layout can effectively address the gas flow measurement needs under complex media composition and low flow rate conditions.

[0039] 2. Double Venturi Combination: A double Venturi combination consists of two Venturi tubes of different sizes. It utilizes the contraction of the fluid at the throat to create negative pressure, thereby achieving high-precision differential pressure signal amplification. This design significantly improves measurement accuracy and is particularly suitable for gas measurements with large diameters and high flow rates.

[0040] 3. Optimized flow field design: In order to improve the uniformity of the flow field, this structure usually incorporates components such as flow straightening grids or averaging tubes inside the pipe to ensure uniform distribution of airflow within the measurement cross section, thereby reducing measurement errors;

[0041] 4. Anti-clogging performance: The multi-point matrix square double Venturi structure also has good anti-clogging performance, making it suitable for applications in complex working conditions such as dust and airflow. This is due to its special probe design and dust removal device, which can effectively prevent the measuring components from being blocked by dust accumulation.

[0042] 5. Computational Model and Wind Tunnel Test Support: The computational model of this structure is based on Bernoulli's equation, the continuity equation, and the equation of motion for one-dimensional steady gas flow. It is optimized by combining wind tunnel test data to ensure its reliability and accuracy in practical applications.

[0043] In summary, the design principle of the multi-point matrix square double Venturi structure is to achieve high-precision and high-stability gas flow measurement by combining fluid mechanics theory, matrix layout and optimized flow field design, which is particularly suitable for complex working conditions and large-diameter scenarios.

[0044] Although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0045] Therefore, the above description is only a preferred embodiment of this application and is not intended to limit the scope of this application; that is, all equivalent modifications made in accordance with the scope of the claims of this application shall be within the protection scope of the claims of this application.

Claims

1. A multi-point matrix-type square double Venturi structure, characterized in that: The device includes a guide tube (2) that extends vertically into the pipe (1) to be tested. The port of the guide tube (2) is provided with a purge port (3) and a differential pressure measurement port (4). The extension end of the guide tube (2) is provided with multiple sets of measurement units for measuring fluid parameters in the guide tube (2). Each set of measurement units includes a branch pipe (5). The branch pipe (5) is inclined on one side of the guide tube (2). At the end of the branch pipe (5), one of two measuring devices is installed. One is a negative pressure square venturi tube (6) that is inclined along the pipe direction for measuring negative pressure related parameters. The other is a positive pressure square venturi tube (7) that is vertically arranged for measuring positive pressure related parameters. The positive pressure square venturi tube (7) and the negative pressure square venturi tube (6) are combined in a one-to-one correspondence.

2. The multi-point matrix-type square double Venturi structure according to claim 1, characterized in that: The interface axis of the purge interface (3) is parallel to the axis of the guide tube (2), and the interface axis of the differential pressure measurement interface (4) should be perpendicular to the axis of the guide tube (2).

3. The multi-point matrix-type square double Venturi structure according to claim 1, characterized in that: The test pipe (1) has an installation hole at its installation position, and a flange is welded at the installation hole position. The transition of the guide pipe (2) at its extension end is sealed to the test pipe (1) through a flange and a gasket.

4. The multi-point matrix-type square double Venturi structure according to claim 1, characterized in that: Both the guide pipe (2) and the branch pipe (5) have square cross sections.

5. The multi-point matrix-type square double Venturi structure according to claim 1, characterized in that: The inclination angle between the branch pipe (5) and the guide pipe (2) is 65-85 degrees.

6. The multi-point matrix-type square double Venturi structure according to claim 1, characterized in that: The guide tube (2) is provided with eight sets of measuring units for measuring fluid parameters inside the guide tube. Among the eight sets of measuring units, the positive pressure square venturi tube (7) and the negative pressure square venturi tube (6) are combined in a one-to-one correspondence to form four sets. The four sets are symmetrically arranged on both sides of the guide tube (2).

7. The multi-point matrix square double Venturi structure according to claim 1, characterized in that: The inner sides of the positive pressure square venturi tube (7) and the negative pressure square venturi tube (6) are described.

8. The multi-point matrix square double Venturi structure according to claim 1, characterized in that: The negative pressure square Venturi tube (6) includes a square pipe, the upper middle part of which is connected to a branch pipe (5), and a differential pressure sensor for accurately measuring the pressure difference generated by the Venturi effect in the pipe is installed inside the pipe.

9. The multi-point matrix square double Venturi structure according to claim 1, characterized in that: The positive pressure square Venturi tube (7) includes a square pipe with beveled openings (8) at the top and bottom, respectively, and the beveled openings (8) are oriented toward the direction of airflow entry. The middle inner side of the pipe is connected to a branch pipe (5). A differential pressure sensor for accurately measuring the pressure difference generated by the Venturi effect in the pipe is installed inside the pipe.

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