A method for calculating the installation distance of the guide pipe according to the diameter of the mixed flow nozzle

Abstract

The present invention relates to the technical field of mixed flow nozzle structure design, and specifically to a method for calculating the installation distance of a guide tube according to the diameter of a mixed flow nozzle. First, by obtaining the basic parameter of the nozzle diameter, an accurate starting point is provided for subsequent calculations. Next, the maximum axial stress is calculated based on the nozzle diameter, taking into account the actual working state of the nozzle. Then, the initial strength factor is calculated in combination with the cohesion of the deposition layer. This step takes environmental factors into consideration and improves the accuracy of the calculation. Finally, the installation distance is calculated through the initial strength factor to ensure a reasonable spacing between the guide tube and the mixed flow nozzle, avoiding efficiency reduction or safety hazards caused by improper spacing. Overall, the method is highly scientific and practical, and can significantly improve the application effect of the mixed flow nozzle. The present invention accurately calculates the installation distance of the guide tube through systematic steps, ensuring the efficiency and safety of the mixed flow nozzle during operation.

Description

Technical Field

[0001] The invention relates to the technical field of mixed flow nozzle structure design, in particular to a method for calculating a guide pipe installation distance according to a mixed flow nozzle diameter. Background Art

[0002] In many industrial fields such as chemical industry, petrochemical industry, environmental protection engineering, and material processing, the mixing, transmission and injection of fluids are widely present and crucial. Compared with other nozzles, the mixed flow nozzle can not only break up the sediment layer through the jet, but also enhance the fluid circulation, replenish the flow autonomously, and reduce the kinetic energy loss. It is suitable for mixing and stirring multiphase fluids that have been stratified due to long-term storage, and can better achieve the purpose of efficient and uniform mixing.

[0003] With the continuous development of industrial technology, the requirements for the accuracy, efficiency and stability of fluid mixing and injection are increasing. The most common mixed flow nozzle consists of an ordinary cylindrical nozzle and a guide pipe section installed in front of it. However, there is a lack of scientific and reasonable basis for determining the installation distance between the two.

[0004] Traditional engineering practices often rely on empirical judgment or rough estimates to determine the installation distance of the guide pipe section relative to the mixing nozzle. This approach has great limitations, as there are obvious differences in fluid injection characteristics between mixing nozzles of different diameters. For example, the nozzle diameter directly affects key parameters such as fluid velocity, flow distribution, injection angle, and mixing effect. If the installation distance is not selected properly, for a smaller diameter mixing nozzle, the fluid may be dispersed prematurely, and the guiding and restraining effects of the guide pipe section cannot be fully utilized, resulting in energy loss and uneven mixing; for a larger diameter mixing nozzle, if the installation distance is too close, it may cause turbulent instability, backflow and other adverse phenomena, affecting the normal operating efficiency of the entire fluid system, increasing energy consumption and equipment loss, and may even reduce product quality and production efficiency. It cannot meet the refined and efficient production needs of modern industry, so it needs to be solved urgently. Summary of the invention

[0005] In order to avoid and overcome the technical problems existing in the prior art, the present invention provides a method for calculating the installation distance of the guide pipe according to the diameter of the mixed flow nozzle. The present invention can more accurately calculate the installation distance between the guide pipe and the nozzle.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for calculating the installation distance of a guide pipe according to the diameter of a mixed flow nozzle comprises the following calculation steps:

[0008] S1. Obtain the nozzle diameter of the mixed flow nozzle;

[0009] S2. Calculate the maximum axial stress of the mixed flow nozzle based on the nozzle diameter;

[0010] S3. Calculate the initial strength factor based on the maximum axial stress and the cohesion of the sediment layer;

[0011] S4. Calculate the installation distance of the guide tube using the initial strength factor.

[0012] As a further solution of the present invention: in step S3, the initial intensity factor is calculated using an initial intensity factor calculation formula; the calculation formula of the initial intensity factor is expressed as follows:

[0013] ;

[0014] In the formula, represents the initial intensity factor; Indicates the cohesion of the sediment layer; represents the maximum axial stress; represents the internal friction angle of the sediment layer; Indicates the confining pressure in the tank; represents the cotangent function; represents the tangent function.

[0015] As a further solution of the present invention: in step S4, the installation distance is calculated using the installation distance calculation formula; the installation distance calculation formula is expressed as follows:

[0016] ;

[0017] In the formula, Indicates the installation distance between the guide pipe and the mixing nozzle; Indicates the nozzle diameter of the mixed flow nozzle.

[0018] As a further solution of the present invention: the specific steps of step S2 are as follows:

[0019] S21. Based on the nozzle diameter, the maximum axial velocity of the mixed flow nozzle is calculated in combination with the nozzle jet velocity calculation formula; the nozzle jet velocity calculation formula is expressed as follows:

[0020] ;

[0021] In the formula, Indicates the maximum axial flow velocity of the mixed flow nozzle; Indicates the nozzle flow rate of the mixed flow nozzle; represents pi;

[0022] S22. Calculate the maximum axial stress of the mixed flow nozzle based on the calculated maximum axial flow velocity and the maximum axial stress calculation formula; the maximum axial stress calculation formula is as follows:

[0023] ;

[0024] In the formula, represents the jet reflection angle; represents the jet density; Indicates the distance from any point in the current jet cross section to the jet axis; Indicates the jet radius of the current jet section.

[0025] As a further solution of the present invention: the specific steps of step S3 are as follows:

[0026] S31. Calculate the strength of the sedimentary layer using a sedimentary layer strength calculation formula; the sedimentary layer strength calculation formula is as follows:

[0027] ;

[0028] In the formula, Indicates the strength of the sedimentary layer; represents the normal stress on the shear surface of the sediment layer; Indicates the pore water pressure in the sediment layer; Indicates the total solid area in the current section of the sedimentary layer; Indicates the total area of ​​liquid in the current section of the sediment layer;

[0029] S32, determining the relationship between the strength of the sedimentary layer and the maximum axial stress; if the strength of the sedimentary layer is greater than the maximum axial stress, the sedimentary layer is removed by increasing the maximum axial stress or manually cleaning; otherwise, the initial strength factor is calculated using the initial strength factor calculation formula.

[0030] As a further solution of the present invention: in the process of jetting to remove the sediment layer, when the actual cleaning speed of the sediment layer is less than the expected cleaning speed and reaches a certain proportion, it is necessary to correct the initial intensity factor by a correction factor, and then substitute the corrected initial intensity factor into the installation distance calculation formula to recalculate the installation distance; the correction factor is calculated as follows:

[0031] ;

[0032] ;

[0033] In the formula, represents the correction factor; represents the correction factor; Indicates the actual cleaning rate of the sediment layer; Indicates the expected clearing rate of the deposited layer.

[0034] As a further solution of the present invention: the modified initial intensity factor is expressed as follows:

[0035] ;

[0036] In the formula, Represents the modified initial intensity factor.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1. The present invention uses systematic steps to accurately calculate the installation distance of the guide tube, thereby ensuring the efficiency and safety of the mixed flow nozzle during operation. First, by obtaining the basic parameter of the nozzle diameter, an accurate starting point is provided for subsequent calculations. Next, the maximum axial stress is calculated based on the nozzle diameter, taking into account the actual working state of the nozzle. Then, the initial strength factor is calculated in combination with the cohesion of the deposited layer. This step takes environmental factors into consideration and improves the accuracy of the calculation. Finally, the installation distance is calculated through the initial strength factor to ensure a reasonable spacing between the guide tube and the mixed flow nozzle, avoiding efficiency loss or safety hazards caused by improper spacing. Overall, this method is highly scientific and practical, and can significantly improve the application effect of the mixed flow nozzle.

[0039] 2. The calculation formula of the initial strength factor comprehensively considers the cohesion of the sediment layer, the maximum axial stress, the internal friction angle of the sediment layer, and the confining pressure in the tank, and can more comprehensively reflect the mechanical properties of the sediment layer. Through the use of cotangent function and tangent function, the formula realizes the accurate calculation of the strength factor of the sediment layer, providing a reliable basis for the subsequent calculation of the installation distance. In addition, the form of the formula is concise and clear, which is convenient for rapid calculation in practical applications.

[0040] 3. The installation distance calculation formula directly links the installation distance between the guide tube and the mixed flow nozzle with the nozzle diameter, making the calculation process more intuitive and convenient. Through simple mathematical operations, a reasonable installation distance can be obtained, avoiding the tedious trial and error process. At the same time, the formula also reflects the important influence of the nozzle diameter on the installation distance, providing clear guidance for engineers in the design process.

[0041] 4. First, the maximum axial velocity of the mixed flow nozzle is calculated, and then the maximum axial stress is calculated based on the velocity. This process fully considers the dynamic characteristics of the nozzle jet. By using the nozzle jet velocity calculation formula and the maximum axial stress calculation formula, an accurate description of the nozzle working state is achieved. In addition, the division of step S2 makes the calculation process clearer and more orderly, which is easier for engineers to understand and operate.

[0042] 5. By calculating the strength of the sedimentary layer and comparing it with the maximum axial stress, the stability of the sedimentary layer can be evaluated. If the strength of the sedimentary layer is insufficient, appropriate measures can be taken to ensure the accuracy and safety of subsequent calculations. At the same time, by using the sedimentary layer strength calculation formula, a quantitative description of the mechanical properties of the sedimentary layer can be achieved, providing reliable data for subsequent calculations.

[0043] 6. When the actual cleaning speed of the sedimentary layer is less than the expected cleaning speed and reaches a certain ratio, the initial intensity factor is corrected by introducing a correction factor to more accurately reflect the actual state of the sedimentary layer. This step improves the accuracy and reliability of the calculation and avoids subsequent problems caused by improper calculation of the initial intensity factor. At the same time, the calculation process of the correction factor also fully considers the difference between the actual cleaning speed and the expected cleaning speed, reflecting the flexibility and practicality of the method.

[0044] 7. The corrected initial strength factor more accurately reflects the actual mechanical properties of the deposited layer, providing more reliable data support for the subsequent calculation of the installation distance. Through the introduction and calculation of the correction factor, the calculation of the initial strength factor is more in line with the actual situation, improving the accuracy and reliability of the overall calculation. At the same time, the corrected initial strength factor is also easier for engineers to understand and accept, which is convenient for promotion and application in practical applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is the main calculation flow chart of the present invention.

[0046] Figure 2 It is a detailed calculation flow chart of the present invention. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] See also Figure 1 and Figure 2 In an embodiment of the present invention, a method for calculating the installation distance of the guide pipe according to the diameter of the mixed flow nozzle includes the following steps:

[0049] 1. Obtain the nozzle diameter of the mixed flow nozzle.

[0050] In a certain sediment crushing operation, the jet density of the jet used is 1.08 , nozzle flow rate of mixed flow nozzle 1.45 , nozzle diameter of mixed flow nozzle The measurement is rounded to 10 mm.

[0051] 2. Calculate the maximum axial stress of the mixed flow nozzle.

[0052] First, based on the nozzle diameter , combined with the nozzle jet velocity calculation formula shown in formula (1) to calculate the maximum axial velocity of the mixed flow nozzle; the nozzle jet velocity calculation formula is expressed as follows:

[0053] (1);

[0054] Then, the maximum axial velocity at the mixed flow nozzle outlet is calculated as , combined with the maximum axial stress calculation formula shown in formula (2) to calculate when the jet reaches the bottom of the tank, The maximum axial stress of the mixed flow nozzle at this time. At this time, the liquid level in the tank is about 1.4m, and the distance from the mixed flow nozzle to the bottom of the tank is 0.2m. When the jet is sprayed to the bottom of the tank, the maximum axial flow velocity is The attenuation is 12.4m / s, and the jet velocity at the bottom of the tank can be measured by the velocity sensor installed at the bottom of the tank. At this time, the sediment layer is cleaned by the flow rate of 12.4m / s. Jet reflection angle The current jet radius of the tank bottom jet section is 60°. The value is At this time, the maximum axial stress calculation formula at the tank bottom is expressed as follows:

[0055] (2);

[0056] 3. Calculate the initial strength factor.

[0057] First, according to the Mohr-Coulomb strength theory, the strength of the deposited layer is calculated by the deposited layer strength calculation formula shown in formula (3); the deposited layer strength calculation formula is expressed as follows:

[0058] (3);

[0059] In the formula, Indicates the strength of the deposited layer. Indicates the cohesion of the sediment layer, which is affected by the physical and chemical properties of the sediment particles. For non-cohesive sand . represents the normal stress on the shear surface of the sediment layer. It represents the pore water pressure in the sediment layer, which refers to the pressure exerted on the liquid phase in the sediment layer. represents the total solid area in the current section of the sedimentary layer, Indicates the total area of ​​liquid in the current section of the sediment layer. Generally, It can be approximately taken as 1. It represents the internal friction angle of the sediment layer, which reflects the friction characteristics between the particles inside the material.

[0060] Next, determine the relationship between the strength of the deposited layer and the maximum axial stress; if the strength of the deposited layer is greater than the maximum axial stress, increase the maximum axial stress or remove the deposited layer manually, that is, increase the jet density. or maximum axial velocity , or manually use other tools to clean up; otherwise, the initial intensity factor is calculated using the initial intensity factor calculation formula. =0, the installation distance is selected between 5.5D and 8.5D according to the situation (5.5D to 8.5D is defined as the jet transition zone). When the installation distance is determined according to the formula (the jet core area is defined as 0~5.5D).

[0061] Cohesion , internal friction angle =26°. The confining pressure in the tank is calculated based on the liquid volume and density. About 14700Pa.

[0062] The initial strength factor is calculated using the initial strength factor calculation formula shown in formula (4); the initial strength factor calculation formula is expressed as follows:

[0063] (4);

[0064] It can be seen that the current initial intensity factor .

[0065] The strength of the deposited layer is affected by many factors. The initial strength factor defined here is It is only used to judge the dominant factors (crushing effect dominant, mixing effect dominant), and needs to be corrected according to the actual situation. Therefore, in the process of jetting to remove the sediment layer, when the actual cleaning speed of the sediment layer is less than the expected cleaning speed and reaches a certain proportion, it is necessary to correct the initial intensity factor by the correction factor shown in formulas (5)-(7), and then substitute the corrected initial intensity factor into the installation distance calculation formula to recalculate the installation distance.

[0066] (5);

[0067] (6);

[0068] The modified initial intensity factor is expressed as follows:

[0069] (7);

[0070] For example, if the expected cleaning speed is 10 cm / min and the actual cleaning speed is 8 cm / min, then , before correction , then the corrected , the corrected initial intensity factor increases.

[0071] 4. Calculate the installation distance of the guide tube.

[0072] The installation distance is calculated using the installation distance calculation formula shown in formula (8); the installation distance calculation formula is expressed as follows:

[0073] (8);

[0074] The calculation can be obtained: .

[0075] The guide tube used in this embodiment is a commonly used hollow tube with trumpet-shaped ends and a cylindrical middle, and the overall length is 95mm. The inner diameter of the trumpet mouth close to the mixed flow nozzle is 90mm and the length is 20mm. The inner diameter of the cylindrical section is 25mm and the length is 50mm. The inner diameter of the trumpet mouth away from the mixed flow nozzle is 35mm and the length is 25mm.

[0076] The original installation distance was 5mm. After it was changed to 6.655mm, under the same conditions, the time it took for the sediment layer in the test chamber to be completely rolled up was shortened from 2min to about 1min, and the mixing efficiency was significantly improved.

[0077] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for calculating the installation distance of a guide pipe according to the diameter of a mixed flow nozzle, characterized in that: The calculation steps include: S1. Obtain the nozzle diameter of the mixed flow nozzle; S2. Calculate the maximum axial stress of the mixed flow nozzle based on the nozzle diameter; S21. Based on the nozzle diameter, the maximum axial velocity of the mixed flow nozzle is calculated in combination with the nozzle jet velocity calculation formula; the nozzle jet velocity calculation formula is expressed as follows: ； In the formula, Indicates the maximum axial flow velocity of the mixed flow nozzle; Indicates the nozzle flow rate of the mixed flow nozzle; represents pi; Indicates the nozzle diameter of the mixed flow nozzle; S22. Calculate the maximum axial stress of the mixed flow nozzle based on the calculated maximum axial flow velocity and the maximum axial stress calculation formula; the calculation formula for the maximum axial stress is as follows: ； In the formula, represents the maximum axial stress; represents the jet reflection angle; represents the jet density; Indicates the distance from any point in the current jet cross section to the jet axis; Indicates the jet radius of the current jet cross section; S3. Calculate the initial strength factor based on the maximum axial stress and the cohesion of the sediment layer; The calculation formula of the initial strength factor is as follows: ； In the formula, represents the initial intensity factor; Indicates the cohesion of the sediment layer; represents the internal friction angle of the sediment layer; Indicates the confining pressure in the tank; represents the cotangent function; represents the tangent function; S4. Calculate the installation distance of the guide tube using the initial strength factor.

2. A method for calculating the guide pipe installation distance according to the mixed flow nozzle diameter according to claim 1, characterized in that: The calculation formula for the installation distance is as follows: ； In the formula, Indicates the installation distance between the guide pipe and the mixing nozzle.

3. The method for calculating the guide pipe installation distance according to the mixed flow nozzle diameter according to claim 2, characterized in that: The specific steps of step S3 are as follows: S31, calculating the strength of the sedimentary layer by using a sedimentary layer strength calculation formula; S32, determining the relationship between the strength of the sediment layer and the maximum axial stress; if the strength of the sediment layer is greater than the maximum axial stress, removing the sediment layer by increasing the maximum axial stress or manually cleaning; Otherwise, the initial intensity factor is calculated using the initial intensity factor calculation formula.

4. The method for calculating the guide pipe installation distance according to the mixed flow nozzle diameter according to claim 3, characterized in that: The calculation formula of the sedimentary layer strength is as follows: ； In the formula, Indicates the strength of the sedimentary layer; represents the normal stress on the shear surface of the sediment layer; Indicates the pore water pressure in the sediment layer; Indicates the total solid area in the current section of the sedimentary layer; Represents the total liquid area in the current section of the sediment layer.

5. The method for calculating the guide pipe installation distance according to the mixed flow nozzle diameter according to claim 4, characterized in that: In the process of removing the sediment layer, when the actual cleaning speed of the sediment layer is less than the expected cleaning speed and reaches a certain ratio, it is necessary to correct the initial intensity factor by the correction factor, and then substitute the corrected initial intensity factor into the calculation formula of the installation distance to recalculate the installation distance; The correction factor is calculated as follows: ； ； In the formula, represents the correction factor; represents the correction factor; Indicates the actual cleaning rate of the sediment layer; Indicates the expected clearing rate of the deposited layer.

6. The method for calculating the guide pipe installation distance according to the mixed flow nozzle diameter according to claim 5, characterized in that: The modified initial intensity factor is expressed as follows: ； In the formula, Represents the modified initial intensity factor.

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