A method for optimizing the pressure of deodorizing air shafts for pig farming in buildings

Abstract

The present invention belongs to the technical field of pig farming in buildings, and specifically discloses a method for optimizing the deodorizing air shaft pressure for pig farming in buildings, comprising: bringing the air shaft structural characteristics and wind characteristics into the along-the-line pressure formula to calculate the along-the-line pressure of the air shaft, the air shaft structural characteristics including the air shaft equivalent diameter, and the wind characteristics including air density, viscosity, and flow velocity; based on the calculated along-the-line pressure, adjusting the air shaft structural characteristics to reduce the along-the-line pressure; obtaining the air shaft pressure data and airflow trajectory cloud map of the adjusted air shaft structure through a computational fluid dynamics simulation system, and setting a guide plate in the air shaft structure based on the air shaft pressure data and airflow trajectory cloud map to reduce the local pressure of the air shaft structure. This application analyzes the problem of high air shaft pressure caused by the air shaft structure itself, optimizes the air shaft structure from two aspects, namely, along-the-line pressure and local pressure, and finally obtains an air shaft structure with better deodorizing effect.

Description

Technical Field

[0001] The invention belongs to the technical field of pig farming in buildings, and in particular relates to a deodorizing air shaft pressure optimization method for pig farming in buildings. Background Art

[0002] Centralized air shafts can centrally treat the exhaust gas in pig houses on each floor of a building, so they have the advantages of high deodorization efficiency, saving equipment investment costs, and reducing equipment operating costs. At the same time, centralized air shafts have a chimney effect, which can effectively use the pressure difference caused by the height difference to increase air flow and improve the ventilation volume of the pig house. However, there are also the following problems in the actual production process: (1) Due to the existence of centralized air shafts, there are large differences in the ventilation volume in each floor of the pig house, especially the air volume in the bottom floor is the smallest. (2) The air volume of the fan in the air shaft is reduced and the power consumption is increased. (3) The ideal wind speed through the deodorization curtain is about 2.0m / s, which can ensure that the odor is fully in contact with the deodorization equipment. However, due to the existence of centralized air shafts, the air volume of each floor is collected in the air shaft, and finally deodorized by the deodorization equipment at the top of the air shaft. Compared with single-layer deodorization, the wind speed through the deodorization curtain is often greater than 2.0m / s, thereby reducing the deodorization effect of the wet curtain.

[0003] Therefore, the existing technology still needs to be further developed and improved. Summary of the Invention

[0004] In view of the various deficiencies of the existing technology and to solve the above problems, a method for optimizing the pressure of the deodorizing air shaft for pig farming in buildings is proposed. The present invention provides the following technical solutions:

[0005] A method for optimizing the pressure of a deodorizing air shaft for pig farming in a building, comprising:

[0006] Substituting the structural characteristics and wind characteristics of the wind shaft into the along-the-line pressure formula to calculate the along-the-line pressure of the wind shaft, the structural characteristics of the wind shaft include the equivalent diameter of the wind shaft, and the wind characteristics include air density, viscosity and flow velocity;

[0007] Based on the calculated pressure along the shaft, the structural characteristics of the ventilation shaft are adjusted to reduce the pressure along the shaft;

[0008] The air shaft pressure data and air flow trajectory cloud map of the adjusted air shaft structure are obtained through the computational fluid dynamics simulation system. Based on the air shaft pressure data and air flow trajectory cloud map, guide plates are set in the air shaft structure to reduce the local pressure of the air shaft structure.

[0009] Furthermore, the pressure formula along the process is: Among them, R m is the pressure drop per meter, λ is the resistance coefficient along the way, ρ is the density, v is the flow velocity, and D is the equivalent diameter.

[0010] Furthermore, the equivalent diameter Among them, A is the cross-sectional area of ​​the wind shaft, and L is the cross-sectional perimeter.

[0011] Furthermore, the drag coefficient λ along the path is calculated using the Coriolis formula: Where Re is the Reynolds number, k is the surface roughness of the concrete;

[0012] The Reynolds number Re=ρvD / μ, where μ is the viscosity coefficient.

[0013] Furthermore, the acute angle between the guide plate and the inner wall of the air shaft is set to 30 degrees.

[0014] Furthermore, the method of adjusting the structural characteristics of the air shaft to reduce the pressure along the way includes constructing an air shaft body structure at the side exhaust outlet of a multi-story building, the air shaft body including a lower shaft covering the side exhaust outlet of the ground floor, an upper shaft covering the side exhaust outlet of the high-rise building, and downwind outlets and upwind outlets respectively arranged at the top of the lower shaft and the upper shaft, the tops of the downwind outlet and the upwind outlet are covered with deodorizing curtains, the downwind outlet and the upwind outlet are staggered, and the lower shaft and the upper shaft are not connected.

[0015] Furthermore, the method for reducing local pressure includes adding a guide plate structure, wherein a first guide plate for guiding the wind direction is provided at the connection between the upper shaft side wall and the upper air outlet, and the first guide plate is provided on the side away from the building; a second guide plate for guiding the wind direction is provided at the connection between the upper shaft side wall and the bottom plate, and the second guide plate is provided on the side away from the building; a third guide plate for guiding the wind direction is provided at the connection between the lower shaft side wall and the bottom plate, and the third guide plate is provided on the side away from the building.

[0016] Furthermore, the width of the lower shaft is greater than the width of the upper shaft.

[0017] Furthermore, the lower shaft is a Z-shaped shaft, including an outer shaft arranged opposite the lower wellhead and an inner shaft arranged opposite the bottom end of the upper shaft. The side walls of one end of the outer shaft and the inner shaft are connected to each other, and the bottom end of the outer shaft is higher than the bottom end of the inner shaft.

[0018] Furthermore, a first maintenance platform for inspecting the fan at the exhaust outlet is provided under each floor exhaust outlet. The first maintenance platform extends outward along the floor plate direction. The first maintenance platform is a porous structural plate. The bottom end of the air shaft body serves as a second maintenance platform for inspecting the fan at the lowest exhaust outlet of the lower shaft or upper shaft.

[0019] Beneficial effects:

[0020] 1. By analyzing the problem of high air shaft pressure caused by the air shaft structure itself, the air shaft structure was optimized from two aspects: along-line pressure and local pressure. Finally, a air shaft structure with better deodorization effect was obtained.

[0021] 2. Obtain the air shaft pressure data and air flow trajectory cloud map of the adjusted air shaft structure through a computational fluid dynamics simulation system. Based on the air shaft pressure data and air flow trajectory cloud map, a guide plate is installed in the air shaft structure to reduce the local pressure of the air shaft structure;

[0022] 3. Calculate the pressure along the shaft based on the structural characteristics of the shaft and optimize the shaft length and equivalent diameter;

[0023] 4. By setting up a double wellbore method to reduce the pressure along the way, the wellhead area at the top of the air well is increased, and the installation area of ​​the deodorizing curtain installed at the wellhead is also expanded, so that the wind speed passing the curtain meets the optimal wind speed requirement, thereby improving the deodorizing quality;

[0024] 5. By setting up staggered upper and lower shafts and leaving space at the bottom of the lower shaft, the shaft structure can be improved while avoiding land occupation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of a building structure with a deodorizing air shaft in a specific embodiment of the present application;

[0026] Figure 2 This is a schematic diagram of the structure of a deodorizing air shaft for pig farming in a building according to a specific embodiment of the present application;

[0027] Figure 3 This is a comparison diagram of the CFD simulated airflow trajectory cloud diagram of the original air shaft structure and the optimized air shaft structure in the specific embodiment of the present application;

[0028] In the accompanying drawings: 100, lower shaft; 110, lower air outlet; 120, third guide plate; 200, upper shaft; 210, upper air outlet; 220, first guide plate; 230, second guide plate; 300, first maintenance platform; 400, exhaust outlet. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is clearly and completely described below in conjunction with the drawings of the present invention. Based on the embodiments in this application, other similar embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of this application. In addition, the directional words mentioned in the following embodiments, such as "up", "down", "left", "right", etc., are only reference to the directions of the drawings. Therefore, the directional words used are used to illustrate rather than limit the invention.

[0030] A method for optimizing the pressure of a deodorizing air shaft for pig farming in a building, comprising:

[0031] Substituting the structural characteristics and wind characteristics of the wind shaft into the along-the-line pressure formula to calculate the along-the-line pressure of the wind shaft, the structural characteristics of the wind shaft include the equivalent diameter of the wind shaft, and the wind characteristics include air density, viscosity and flow velocity;

[0032] Based on the calculated pressure along the shaft, the structural characteristics of the ventilation shaft are adjusted to reduce the pressure along the shaft;

[0033] The air shaft pressure data and air flow trajectory cloud map of the adjusted air shaft structure are obtained through the computational fluid dynamics simulation system. Based on the air shaft pressure data and air flow trajectory cloud map, guide plates are set in the air shaft structure to reduce the local pressure of the air shaft structure.

[0034] This application analyzes the problem of high air shaft pressure caused by the air shaft structure itself, optimizes the air shaft structure from two aspects: along-the-line pressure and local pressure, and finally obtains an air shaft structure with better deodorization effect. Due to the existence of the centralized air shaft, the pressure in the air shaft forms a positive pressure environment, and the ventilation volume of the fan is negatively correlated with the pressure, that is, the greater the pressure, the smaller the air volume. In addition, most of the fans currently used for ventilation of livestock and poultry houses are negative pressure fans, which have limited ability to resist positive pressure, and ultimately lead to the above problems. The pressure is divided into local pressure and along-the-line pressure. First of all, to optimize the pressure distribution of the air shaft, it is necessary to determine whether it is caused by local pressure or along-the-line pressure.

[0035] Furthermore, the pressure formula along the process is: Among them, R m is the pressure drop per meter, λ is the resistance coefficient along the way, ρ is the density, v is the flow velocity, and D is the equivalent diameter.

[0036] Furthermore, the equivalent diameter Among them, A is the cross-sectional area of ​​the wind shaft, and L is the cross-sectional perimeter.

[0037] Furthermore, the drag coefficient λ along the path is calculated using the Coriolis formula: Where Re is the Reynolds number, k is the surface roughness of the concrete;

[0038] The Reynolds number Re=ρvD / μ, where μ is the viscosity coefficient.

[0039] Substitute it into the pressure formula along the way, and calculate the wind shaft R m It is 0.5Pa / m, and the length of the wind shaft is 31.5m, that is, the resistance along the way is 15.75Pa.

[0040] Furthermore, the acute angle between the guide plate and the inner wall of the wind shaft is set to 30 degrees. Through on-site measurement of the wind shaft pressure, it was found that the local pressure at the bottom of the wind shaft is about 80Pa, and the local pressure of the wind shaft gradually decreases along the height direction of the wind shaft. Therefore, the bottom is the key area for optimization. Through CFD (computational fluid dynamics simulation system), it was found that the sudden increase in bottom pressure is caused by the backlog of poor airflow movement. Therefore, how to ensure the smooth movement of the bottom airflow is an effective way to solve the sudden increase in pressure. For this purpose, CFD was used to simulate the flow field distribution after installing guide plates of different angles at the bottom of the wind shaft. By extracting the wind shaft pressure data and the airflow trajectory cloud map, it was finally determined that when the guide plate angle is 30 degrees, the local pressure of the wind shaft structure is the smallest.

[0041] like Figure 1-2 As shown, the air shaft structure includes an air shaft body fixed to the exhaust vents 400 on the side of a multi-story building. The air shaft body includes a lower shaft 100 covering the exhaust vents 400 on the ground floor, an upper shaft 200 covering the exhaust vents 400 on the high-rise floors, and a lower air vent 110 and an upper air vent 210 respectively arranged at the top of the lower shaft 100 and the upper shaft 200. The tops of the lower air vent 110 and the upper air vent 210 are covered with deodorizing curtains. The lower air vent 110 and the upper air vent 210 are staggered, and the lower shaft 100 and the upper shaft 200 are not connected. By splitting the existing air shaft into two independent lower shafts 100 and upper shafts 200, and providing corresponding lower and upper wellheads, the ventilation pressure in the air shaft is shared, and the installation area of ​​the deodorizing curtain is increased, thereby improving the deodorizing effect. In this embodiment, an eight-story building is selected as the improved structure. Exhaust outlets 400 on floors 1-4 share a lower shaft 100, while exhaust outlets 400 on floors 5-8 share an upper shaft 200. The dual shaft arrangement also increases the area of ​​the shaft's top wellhead, which in turn increases the installation area for the deodorizing curtain installed at the wellhead. This ensures that the air velocity over the curtain meets the optimal speed requirement, improving deodorization quality.

[0042] As a preferred embodiment of this technical solution, a first deflector 220 is installed at the junction of the sidewall of the upper well 200 and the upper air outlet 210 to guide the wind direction. The first deflector 220 is located on the side away from the building. The installation of the first deflector 220 forms a closed structure at the upper well opening, enhancing the chimney effect of the upper well 200 and improving the smoothness of airflow within the upper well 200.

[0043] As a preferred embodiment of this technical solution, a second deflector 230 is installed at the junction of the sidewall and the bottom plate of the upper hoistway 200 to guide the wind direction. The second deflector 230 is located on the side away from the building. By installing the second deflector 230, the guiding effect of the inclined surface structure is utilized to reduce the local pressure of the airflow hitting the wall, ensuring the smoothness of the airflow organization and movement.

[0044] As a preferred embodiment of this technical solution, a third deflector 120 is installed at the junction of the sidewall and the floor of the lower shaft 100 to guide the wind direction. This third deflector 120 is located on the side away from the building. By installing this third deflector 120, the guiding effect of the inclined surface structure is utilized to reduce the local pressure of the airflow hitting the wall, ensuring the smoothness of the airflow organization and movement.

[0045] As a preferred embodiment of the present technical solution, the width of the lower shaft 100 is greater than that of the upper shaft 200. Existing air shafts typically widen the entire width of the shaft body to improve deodorization and reduce fan pressure. However, this approach occupies a large building area and increases construction costs. This application, however, only partially widens the lower shaft 100. This significantly reduces costs and the floor space occupied by the shaft body, thereby reducing enterprise investment costs, compared to increasing the width of the entire shaft body.

[0046] As a preferred embodiment of the present technical solution, the lower well 100 is a Z-shaped well, including an outer well arranged opposite the lower wellhead and an inner well arranged opposite the bottom end of the upper wellhead 200. The side walls of the outer wellhead and the inner wellhead are connected to each other, and the bottom end of the outer wellhead is higher than the bottom end of the inner wellhead. The outer wellhead and the inner wellhead are arranged side by side, and the third guide plate 120 is arranged at the bottom end of the inner wellhead. The bottom end of the outer wellhead is higher than the bottom end of the inner wellhead so that the ground area below the outer wellhead is not occupied, thereby improving the utilization rate of the ground space. In this embodiment, the upper wellhead and the upper wellhead 200 are staggered, and the lower wellhead and the inner wellhead are staggered, so that the odor discharged from the exhaust port 400 has sufficient wind pressure travel space, thereby reducing the ventilation rate of the deodorizing curtain at the upper wellhead and the lower wellhead, and avoiding overload affecting the deodorizing effect.

[0047] As a preferred solution of the present technical solution, a first maintenance platform 300 for inspecting the fan at the exhaust outlet 400 is provided below each floor exhaust outlet 400, and the first maintenance platform 300 extends outward along the floor plate direction.

[0048] As a preferred solution of this technical solution, the outward extension length of the first maintenance platform 300 is no more than half the distance from the air shaft body to the side of the building. The first maintenance platform 300 is set as short as possible to avoid excessive interference with the normal flow of wind.

[0049] As a preferred solution of this technical solution, the first maintenance platform 300 is a plate with a porous structure. The plate with a porous structure is light in weight and does not affect the flow of air in the well.

[0050] As a preferred solution of this technical solution, the bottom end of the air shaft body serves as a second maintenance platform for inspecting the fans at the lowest exhaust outlet 400 of the lower shaft 100 or upper shaft 200. Utilizing the bottom ends of the upper shaft 200 and lower shaft 100 as second maintenance platforms reduces the number of maintenance platforms required, thereby lowering the company's building configuration costs.

[0051] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

[0052] The present invention has been described in detail above. The above description is only a preferred embodiment of the present invention and should not limit the scope of implementation of the present invention. That is, all equivalent changes and modifications made within the scope of this application should still fall within the scope of the present invention.

Claims

1. A method for optimizing the pressure of a deodorizing air shaft for pig farming in a building, characterized in that: include: Substituting the structural characteristics and wind characteristics of the wind shaft into the along-the-line pressure formula to calculate the along-the-line pressure of the wind shaft, the structural characteristics of the wind shaft include the equivalent diameter of the wind shaft, and the wind characteristics include air density, viscosity and flow velocity; Based on the calculated pressure along the shaft, the structural characteristics of the ventilation shaft are adjusted to reduce the pressure along the shaft; The air shaft pressure data and air flow trajectory cloud map of the adjusted air shaft structure are obtained through a computational fluid dynamics simulation system. Based on the air shaft pressure data and air flow trajectory cloud map, guide plates are set in the air shaft structure to reduce the local pressure of the air shaft structure; The method for adjusting the structural characteristics of an air shaft to reduce the pressure along the way includes constructing an air shaft body structure at the side exhaust outlet of a multi-story building, the air shaft body including a lower shaft covering the side exhaust outlet of a ground floor, an upper shaft covering the side exhaust outlet of a high-rise building, and downwind outlets and upwind outlets respectively arranged at the top of the lower shaft and the upper shaft, the tops of the downwind outlet and the upwind outlet are covered with deodorizing curtains, the downwind outlet and the upwind outlet are staggered, and the lower shaft and the upper shaft are not connected.

2. The method for optimizing the deodorizing air shaft pressure for pig farming in a building according to claim 1, characterized in that: The pressure formula along the process is: ,in, is the pressure drop per meter, is the resistance coefficient along the path, is the air density, is the flow rate, is the equivalent diameter.

3. The method for optimizing the deodorizing air shaft pressure for pig farming in a building according to claim 2, characterized in that: Equivalent diameter ,in, is the cross-sectional area of ​​the wind shaft, is the cross-sectional perimeter.

4. The method for optimizing the deodorizing air shaft pressure for pig farming in a building according to claim 2, characterized in that: The along-the-line resistance coefficient Calculated by Koch's formula: ,in, is the Reynolds number, is the surface roughness of concrete; The Reynolds number ,in, For viscosity.

5. The method for optimizing the deodorizing air shaft pressure for pig farming in a building according to claim 1, characterized in that: The acute angle between the guide plate and the inner wall of the air shaft is set to 30 degrees.

6. The method for optimizing the deodorizing air shaft pressure for pig farming in a building according to claim 1, characterized in that: The method for reducing local pressure includes adding a guide plate structure, wherein a first guide plate for guiding the wind direction is provided at the connection between the upper shaft side wall and the upper air outlet, and the first guide plate is provided on the side away from the building; a second guide plate for guiding the wind direction is provided at the connection between the upper shaft side wall and the bottom plate, and the second guide plate is provided on the side away from the building; a third guide plate for guiding the wind direction is provided at the connection between the lower shaft side wall and the bottom plate, and the third guide plate is provided on the side away from the building.

7. The method for optimizing the deodorizing air shaft pressure for pig farming in a building according to claim 1, characterized in that: The width of the lower shaft is greater than the width of the upper shaft.

8. The method for optimizing the deodorizing air shaft pressure for pig farming in a building according to claim 1, characterized in that: The lower shaft is a Z-shaped shaft, including an outer shaft arranged opposite the lower wellhead and an inner shaft arranged opposite the bottom end of the upper shaft. The side walls of one end of the outer shaft and the inner shaft are connected to each other, and the bottom end of the outer shaft is higher than the bottom end of the inner shaft.

9. The method for optimizing the deodorizing air shaft pressure for pig farming in a building according to claim 1, characterized in that: A first maintenance platform for inspecting the fan at the exhaust outlet is provided under each floor exhaust outlet. The first maintenance platform extends outward along the floor plate direction. The first maintenance platform is a porous structural plate. The bottom end of the air shaft body serves as a second maintenance platform for inspecting the fan at the lowest exhaust outlet of the lower shaft or upper shaft.

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