Negative pressure gradient analysis method and device, selection method, adjustment method and system

Abstract

The present invention provides a method for analyzing the negative pressure gradient of a factory building, comprising: establishing a three-dimensional geometric model of the factory building ventilation system; importing the three-dimensional geometric model of the factory building ventilation system into FLUENT software, and performing simulation calculations on the negative pressure values of each room of the factory building ventilation system under the design air volume; respectively determining the difference between the negative pressure value of each room and the corresponding value required by each specification, and adjusting the air supply volume of the corresponding room based on the determination result and performing simulation calculations again until the negative pressure value approaches the corresponding value required by each specification, so as to obtain a factory building negative pressure gradient that meets the specification requirements. Furthermore, a method for selecting a supply air blower, a method for adjusting a ventilation system, an analysis device for a negative pressure gradient, and a ventilation system adjustment system are also provided. This method for analyzing the negative pressure gradient of a factory building can obtain a factory building negative pressure gradient that meets the specification requirements and is consistent with actual working conditions, thereby improving design accuracy and preventing post-processing plant workers from being exposed to radioactive pollutants.

Description

Technical Field

[0001] The present invention relates to the field of ventilation technology, and in particular to a method and device for analyzing a negative pressure gradient in a factory building, a method for selecting an air supply fan in a ventilation system, and a method and system for adjusting a ventilation system. Background Art

[0002] Every room in a post-processing plant needs to maintain negative pressure, and the required negative pressure varies depending on the level of pollution in each room. The plant's ventilation system design requires airflow from low-pollution areas to high-pollution areas. Therefore, ensuring that the negative pressure gradient meets regulatory requirements is crucial. During the design phase, the post-processing plant's ventilation system calculates the exhaust volume for each room based on the required air changes or the air volume required to remove excess heat, as specified in the regulations. The supply air volume is then calculated directly based on 90% of the exhaust volume. This results in design values for the exhaust and supply air volumes, ensuring the plant meets the regulatory negative pressure gradient.

[0003] Since the sealing level of each room is different and the length and width of the door and window gaps are different, the negative pressure value of each room obtained by the design value of the supply and exhaust air volume calculated according to the above method cannot be equivalent to the negative pressure value of the actual working conditions of each room, resulting in the negative pressure value of the actual working conditions of the room being inconsistent with the negative pressure value required by the specification, which in turn leads to the destruction of the pressure gradient of the factory building and the flow of pollutants to the low-pollution area, posing a safety threat to the post-processing plant staff. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the above-mentioned deficiencies in the prior art and provide a method and device for analyzing the negative pressure gradient of a plant, a method for selecting a supply air blower for a ventilation system, and a method and system for adjusting the ventilation system, so that the designed negative pressure gradient of the plant can conform to actual working conditions and meet regulatory requirements, thereby improving design accuracy and preventing reprocessing plant workers from being exposed to radioactive pollutants.

[0005] In a first aspect, the present invention provides a method for analyzing the negative pressure gradient of a factory building, comprising: establishing a three-dimensional geometric model of a factory building ventilation system; importing the three-dimensional geometric model of the factory building ventilation system into FLUENT software, and simulating and calculating the negative pressure value of each room of the factory building ventilation system under the design air volume to obtain the negative pressure value of each room, wherein the design air volume includes the supply air volume and the exhaust air volume; respectively judging the size between the negative pressure value of each room and the corresponding value required by each specification, and adjusting the supply air volume of the corresponding room according to the judgment result and simulating and calculating it again until the negative pressure value of each room approaches the corresponding value required by each specification, so as to obtain a factory building negative pressure gradient that meets the requirements of the specification.

[0006] Preferably, establishing a three-dimensional geometric model of the factory ventilation system specifically includes: using ICEM software to establish a three-dimensional geometric model of the factory ventilation system.

[0007] Preferably, the use of ICEM software to establish a three-dimensional geometric model of the factory ventilation system specifically includes: using ICEM software to establish a three-dimensional geometric model of all rooms and pipes in the factory ventilation system; for the three-dimensional geometric model, setting the boundary condition of the air flow inlet to a velocity inlet, and setting the boundary conditions of the ground, walls and room ceiling to wall surfaces, and setting the wall to an insulated wall, and setting the boundary condition of the exhaust outlet to a pressure outlet; dividing the three-dimensional geometric model into an unstructured grid.

[0008] Preferably, the three-dimensional geometric model is divided into an unstructured grid, specifically including: keeping the density change of the grid in the solution domain consistent with the gradient change of the variable being solved; keeping the grid unit change in the solution domain as a smooth change; keeping the width-to-height ratio of the grid unit less than or equal to the second ratio.

[0009] Preferably, before establishing the three-dimensional geometric model of the factory ventilation system, the analysis method of the factory negative pressure gradient also includes: calculating the exhaust volume of the factory ventilation system based on the number of air changes or the method of discharging waste heat; and calculating the supply air volume based on the fact that the supply air volume is equal to the exhaust air volume multiplied by the first ratio to obtain the design air volume.

[0010] Preferably, the air supply volume of the corresponding room is adjusted according to the judgment result and simulated again until the negative pressure value of each room approaches the corresponding specification requirement value, specifically including: when the judgment result is that the absolute value of the negative pressure value of a single room is greater than the absolute value of its specification requirement value, the supply air volume is gradually increased by a step size obtained by multiplying the difference between the exhaust volume and the supply air volume by the third ratio, and then simulated again until the negative pressure value of the single room approaches the specification requirement value; when the judgment result is that the absolute value of the negative pressure value of the single room is less than the absolute value of the specification requirement value, the supply air volume is gradually reduced by a step size obtained by multiplying the difference between the exhaust volume and the supply air volume by the third ratio, and then simulated again until the negative pressure value of the single room approaches the specification requirement value; when the judgment result is that the absolute value of the negative pressure value of the single room is equal to the absolute value of the specification requirement value, it is determined that the negative pressure value of the single room is in an ideal state of approaching the specification requirement value.

[0011] In a second aspect, the present invention also provides a method for selecting an air supply fan for a ventilation system, comprising the following steps: obtaining the air supply volume corresponding to the negative pressure gradient of the factory building that meets the specification requirements according to the analysis method of the negative pressure gradient of the factory building described in the first aspect; and selecting the air supply fan of the factory building ventilation system according to the air supply volume.

[0012] In a third aspect, the present invention also provides a method for adjusting a ventilation system, comprising the following steps: obtaining an air supply volume corresponding to a negative pressure gradient of a factory building that meets the requirements of the specification according to the analysis method of the negative pressure gradient of the factory building described in the first aspect; and adjusting valves in the pipelines of the factory ventilation system according to the air supply volume so that the factory ventilation system obtains a negative pressure gradient of the factory building that meets the requirements of the specification.

[0013] In a fourth aspect, the present invention also provides an analysis device for the negative pressure gradient of a factory building, comprising a modeling module, a calculation module and a judgment module.

[0014] The modeling module is used to establish a three-dimensional geometric model of the factory ventilation system. The calculation module is connected to the modeling module and is used to import the three-dimensional geometric model of the factory ventilation system into the FLUENT software stored therein, and simulate and calculate the negative pressure value of each room in the factory ventilation system under the design air volume to obtain the negative pressure value of each room, where the design air volume includes the supply air volume and the exhaust air volume. The judgment module is connected to the calculation module and is used to judge the difference between the negative pressure value of each room and the corresponding value required by each specification, and adjust the supply air volume of the corresponding room based on the judgment result and send it back to the calculation module for simulation calculation until the negative pressure value of each room approaches the corresponding value required by each specification, so as to obtain a factory negative pressure gradient that meets the requirements of the specification.

[0015] In a fifth aspect, the present invention further provides a ventilation system adjustment system, comprising: the plant negative pressure gradient analysis device described in the fourth aspect, configured to determine the air supply volume corresponding to a plant negative pressure gradient that meets regulatory requirements; and a control device, connected to the analysis device, configured to adjust valves in the plant ventilation system ducts based on the air supply volume, so that the plant ventilation system achieves a plant negative pressure gradient that meets regulatory requirements.

[0016] The present invention provides a method and device for analyzing the negative pressure gradient of a factory building, a method for selecting a supply air blower for a ventilation system, and a method and system for adjusting the ventilation system. By establishing a three-dimensional geometric model consistent with actual working conditions (such as the length and width of actual door and window gaps in the factory building), and using three-dimensional flow field simulation software to simulate the calculation of the room negative pressure value for the established three-dimensional geometric model, the air supply volume is adjusted accordingly based on the difference between the calculation result and the value required by the specification. Compared with the prior art of calculating the supply and exhaust air volume based on the number of room ventilation times or the discharge of waste heat, the accuracy of the design calculation is improved, so that the negative pressure value obtained by the simulation calculation approaches the value required by the specification, thereby ensuring that the designed negative pressure gradient is consistent with the actual working conditions and reducing the exposure of post-processing plant workers to radioactive pollutants. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the method for analyzing the negative pressure gradient of a plant in Example 1 of the present invention;

[0018] Figure 2This is a schematic structural diagram of the analysis device for the negative pressure gradient of a plant according to Example 4 of the present invention. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0020] Example 1:

[0021] like Figure 1 As shown, this embodiment provides a method for analyzing the negative pressure gradient of a factory building, including:

[0022] Step 101: Create a three-dimensional geometric model of the factory ventilation system.

[0023] In this embodiment, a three-dimensional geometric model of the factory ventilation system can be established using ICEM software, CAD software, PROE software, or other three-dimensional modeling software with a matching interface with three-dimensional flow field simulation software (such as FLUENT software). The established three-dimensional geometric model reflects the length and width of the door and window gaps in each room of the factory ventilation system under actual working conditions.

[0024] Step 102: Import the three-dimensional geometric model of the factory ventilation system into FLUENT software, and simulate and calculate the negative pressure value of each room of the factory ventilation system under the design air volume to obtain the negative pressure value of each room, wherein the design air volume includes the supply air volume and the exhaust air volume.

[0025] In this embodiment, a 3D geometric model of the factory ventilation system is imported into 3D flow field simulation software (e.g., FLUENT) via an interface. The negative pressure values in each room at the designed air volume are simulated and calculated to obtain the negative pressure values in each room. Because the established 3D geometric model is consistent with the actual operating conditions of the factory ventilation system, the negative pressure values in each room obtained by simulating the 3D geometric model are consistent with the actual negative pressure values in each room.

[0026] Step 103, respectively judge the size between the negative pressure value of each room and the corresponding specification requirement value, and adjust the air supply volume of the corresponding room according to the judgment result and simulate it again until the negative pressure value of each room approaches the corresponding specification requirement value, so as to obtain the factory negative pressure gradient that meets the specification requirements.

[0027] In this embodiment, using a nuclear power plant as an example, each room has a corresponding regulatory requirement for negative pressure. When the negative pressure in each room meets the corresponding regulatory requirement, the plant's negative pressure gradient meets the regulatory requirement. When determining the difference between the simulated negative pressure value and the regulatory requirement, if only Room A's negative pressure differs from the regulatory requirement, only Room A's airflow needs to be adjusted and the simulation calculation for Room A repeated until the final adjusted airflow brings Room A's negative pressure closer to the regulatory requirement.

[0028] Optionally, step 101: establishing a three-dimensional geometric model of the factory ventilation system specifically includes: using ICEM software to establish a three-dimensional geometric model of the factory ventilation system.

[0029] In this embodiment, since ICEM software has powerful CAD model repair capabilities, automatic mid-surface extraction, unique mesh "sculpting" technology, mesh editing technology and extensive solver support capabilities, it is a software with powerful pre-processing functions. Therefore, this embodiment preferably uses ICEM software to establish a three-dimensional geometric model of the factory ventilation system.

[0030] Optionally, ICEM software is used to establish a three-dimensional geometric model of the factory ventilation system, specifically including: using ICEM software to establish a three-dimensional geometric model of all rooms and pipes in the factory ventilation system; for the three-dimensional geometric model, setting the boundary condition of the air flow inlet to the velocity inlet, and setting the boundary conditions of the ground, wall and room ceiling to the wall surface, and the wall is set to an insulated wall, and setting the boundary condition of the exhaust outlet to the pressure outlet; dividing the three-dimensional geometric model into an unstructured grid.

[0031] In this example, a 3D geometric model is created for all rooms and ducts in the factory ventilation system, including the room walls, associated ventilation ducts, and key entrances and exits (e.g., doors, windows, air supply and exhaust vents). Furthermore, because the walls of the factory area are relatively thick and adjacent rooms have similar functions, heat transfer between rooms is not considered. The system is designed as an insulated wall system, specifically, the heat transfer coefficient between rooms is set to 0.

[0032] Optionally, the three-dimensional geometric model is divided into an unstructured grid, specifically including: keeping the density change of the grid in the solution domain consistent with the gradient change of the variable being solved; keeping the change of the grid unit in the solution domain smooth; keeping the width-to-height ratio of the grid unit less than or equal to the second ratio.

[0033] In this embodiment, the density change of the grid in the solution domain is kept consistent with the gradient change of the variable being solved. Specifically, if the pressure calculation result of a certain area is of interest, the grid division of this area should be denser. For example, the grid division for places with gaps in doors and windows needs to be denser, and the grid division for open areas in the room (such as the center of the room) needs to be sparser, so that the density change of the grid division is consistent with the gradient change of the pressure. The grid unit change in the solution domain is kept smooth. Specifically, the tetrahedrons generated during grid division should have as many obtuse angles as possible. If there are more acute angles, it means that the grid unit changes are not smooth. The grid quality tool in the ICEM software can be used to automatically check and judge whether the grid unit change is smooth. If the judgment result is qualified, it means that the change of the grid unit is smooth. The width-to-height ratio of the grid unit is kept less than or equal to the second ratio (for example, the second ratio is 5:1). When the grid division in this embodiment meets the above three maintenance measures, the pressure value obtained by the subsequent simulation calculation is more accurate and more consistent with the actual working condition.

[0034] Optionally, before step 101: establishing a three-dimensional geometric model of the factory ventilation system, the method for analyzing the negative pressure gradient of the factory also includes: calculating the exhaust volume of the factory ventilation system based on the number of air changes or the method of discharging waste heat; and calculating the supply air volume based on the fact that the supply air volume is equal to the exhaust air volume multiplied by the first ratio to obtain the design air volume.

[0035] In this embodiment, the exhaust air volume is calculated based on conventional methods for ventilation rate or waste heat removal. The supply air volume is then calculated based on a first ratio of the supply air volume to the exhaust air volume (e.g., 80% or 90%) to obtain the design air volume. Three-dimensional flow field simulation software is then used to simulate the room negative pressure values of the three-dimensional geometric model established under the design air volume (including exhaust and supply air volumes), yielding room negative pressure values that conform to actual operating conditions. The simulated negative pressure values for each room are then compared with the corresponding negative pressure values required by the relevant regulations. Based on the supply air volume, combined with air volume adjustment measures for the plant ventilation system (such as replacing the supply air blower or adjusting valves in the air supply duct), the supply air volume is gradually adjusted to bring the room negative pressure values closer to the required values. The purpose of obtaining the supply air volume in this embodiment is to facilitate the rapid acquisition of an air volume result that approximates the required values, thereby reducing the computational effort required to adjust the data. It should be noted that in nuclear power plant regulations, the exhaust air volume and ventilation rate for each room are fixed values and cannot be modified.

[0036] Optionally, step 103 adjusts the air supply volume of the corresponding room according to the judgment result and performs simulation calculation again until the negative pressure value of each room approaches the corresponding standard requirement value, specifically including:

[0037] When the judgment result is that the absolute value of the negative pressure value of a single room is greater than the absolute value of the value required by the specification, the supply air volume is gradually increased by a step size obtained by multiplying the difference between the exhaust volume and the supply air volume by the third ratio, and then the simulation calculation is performed again until the negative pressure value of the single room approaches the value required by the specification; when the judgment result is that the absolute value of the negative pressure value of the single room is less than the absolute value of the value required by the specification, the supply air volume is gradually reduced by a step size obtained by multiplying the difference between the exhaust volume and the supply air volume by the third ratio, and then the simulation calculation is performed again until the negative pressure value of the single room approaches the value required by the specification; when the judgment result is that the absolute value of the negative pressure value of the single room is equal to the absolute value of the value required by the specification, it is determined that the negative pressure value of the single room is in an ideal state where it approaches the value required by the specification.

[0038] In this embodiment, when the absolute value of the negative pressure value of a single room is greater than the absolute value of the standard requirement value of the single room, the supply air volume is increased by "(exhaust air volume - supply air volume) * 20%" and the negative pressure value of the single room is simulated and calculated again; when the absolute value of the calculated negative pressure value is still greater than the absolute value of the standard requirement value, the supply air volume is increased by "(exhaust air volume - supply air volume) * 20%" and the negative pressure value of the room is simulated and calculated again, and the increase is repeated until the negative pressure value of the single room obtained by the final simulation is close to the standard requirement value, which indicates that the negative pressure value of the room meets the standard requirements. It should be noted that if the absolute value of the negative pressure value of a single room is equal to the absolute value of the standard requirement value, it indicates that the negative pressure value of the room is in an ideal state of meeting the standard requirement value.

[0039] The analysis method of the factory building negative pressure gradient of this embodiment ensures that the exhaust volume and air exchange rate of the room meet the requirements of the specification. By using three-dimensional modeling software to establish a three-dimensional geometric model consistent with the actual working conditions of the factory building ventilation system, the established three-dimensional geometric model is simulated and calculated for the room negative pressure value. Then, it is judged whether the simulation calculation result is close to the negative pressure value required by the specification. If the simulation calculation result is judged to be the negative pressure value that does not meet the requirements of the specification, the air supply volume of the three-dimensional geometric model of the factory building ventilation system is continuously adjusted until the simulation calculation result meets the requirements of the specification. In this way, the negative pressure value of each room of the factory building ventilation system under the actual working conditions that meet the requirements of the specification is obtained, and the factory building negative pressure gradient that meets the requirements of the specification is obtained. In addition, based on the accurate negative pressure value, it can also provide direct adjustment means and methods for the later commissioning and operation of the factory building, guide the commissioning work, and reduce the workload of the later commissioning; it can also provide a basis for the reasonable selection of the air volume of the blower, thereby saving operating energy consumption and reducing operating costs.

[0040] Example 2:

[0041] This embodiment provides a method for selecting an air supply fan for a ventilation system, comprising the following steps:

[0042] Step 201 : According to the analysis method of the negative pressure gradient of the factory building described in Example 1, the air supply volume corresponding to the negative pressure gradient of the factory building that meets the requirements of the specification is obtained.

[0043] Step 202: Select an air supply fan for the factory ventilation system according to the air supply volume.

[0044] The method for selecting the air supply fan of the ventilation system of this embodiment can provide a basis for reasonably selecting the air volume of the air supply fan, thereby saving operating energy consumption and reducing operating costs.

[0045] Example 3:

[0046] This embodiment provides a method for adjusting a ventilation system, comprising the following steps:

[0047] Step 301 : According to the analysis method of the negative pressure gradient of the factory building described in Example 1, the air supply volume corresponding to the negative pressure gradient of the factory building that meets the requirements of the specification is obtained.

[0048] Step 302: Adjust the valves in the air supply duct of the ventilation system according to the air supply volume, so that the factory ventilation system obtains a factory negative pressure gradient that meets the regulatory requirements.

[0049] Example 4:

[0050] like Figure 2 As shown, this embodiment provides an analysis device for negative pressure gradient in a factory building, including a modeling module 41 , a calculation module 42 and a judgment module 43 .

[0051] The modeling module 41 is used to establish a three-dimensional geometric model of the factory ventilation system.

[0052] The calculation module 42 is connected to the modeling module 41 and is used to import the three-dimensional geometric model of the factory ventilation system into the FLUENT software stored therein, and simulate and calculate the negative pressure value of each room of the factory ventilation system under the design air volume to obtain the negative pressure value of each room, wherein the design air volume includes the supply air volume and the exhaust air volume.

[0053] The judgment module 43 is connected to the calculation module 42, and is used to judge the size between the negative pressure value of each room and the corresponding specification requirements, and adjust the air supply volume of the corresponding room according to the judgment result and send it to the calculation module 42 for simulation calculation again until the negative pressure value of each room approaches the corresponding specification requirements, so as to obtain the factory negative pressure gradient that meets the specification requirements.

[0054] Optionally, the modeling module 41 is used to establish a three-dimensional geometric model of the factory ventilation system using ICEM software stored therein.

[0055] Optionally, the modeling module 41 includes a modeling unit, which is used to establish a three-dimensional geometric model of all rooms and pipes in the factory ventilation system using ICEM software, and for the three-dimensional geometric model, is used to set the boundary condition of the air flow inlet to the velocity inlet, and is used to set the boundary conditions of the ground, wall and room ceiling to the wall surface, and the wall is set to an insulated wall, and is used to set the boundary condition of the exhaust outlet to the pressure outlet; and is used to divide the three-dimensional geometric model into an unstructured grid.

[0056] Optionally, the modeling unit is used to divide the three-dimensional geometric model into an unstructured grid, specifically, to keep the density changes of the grid in the solution domain consistent with the gradient changes of the variable being solved; to keep the changes of the grid units in the solution domain smooth; and to keep the width-to-height ratio of the grid units less than or equal to a second ratio.

[0057] Optionally, the plant negative pressure gradient analysis device further includes a pre-module. The pre-module is connected to the calculation module 42 and is configured to calculate the exhaust volume of the plant ventilation system based on the number of air changes or the method of exhausting excess heat; calculate the supply air volume based on the principle that the supply air volume is equal to the exhaust air volume multiplied by a first ratio to obtain the design air volume, and transmit the design air volume data to the calculation module 42.

[0058] Optionally, the judgment module 43 includes a first judgment unit, a second judgment unit and a third judgment unit.

[0059] The first judgment unit is used to, when the judgment result is that the absolute value of the negative pressure value of a single room is greater than the absolute value of its standard requirement value, gradually increase the supply air volume by a step size obtained by multiplying the difference between the exhaust air volume and the supply air volume by the third ratio, and then send it to the calculation module 42 for simulation calculation again until the negative pressure value of the single room approaches its standard requirement value.

[0060] The second judgment unit is used to, when the judgment result is that the absolute value of the negative pressure value of a single room is less than the absolute value of its standard requirement value, gradually reduce the supply air volume by a step size obtained by multiplying the difference between the exhaust volume and the supply air volume by the third ratio, and then send it to the calculation module 42 for simulation calculation again until the negative pressure value of the single room approaches its standard requirement value.

[0061] The third judgment unit is configured to determine that the negative pressure value of the single room is approaching an ideal state of the negative pressure value of the single room when the judgment result is that the absolute value of the negative pressure value of the single room is equal to the absolute value of the negative pressure value of the single room.

[0062] Example 5:

[0063] This embodiment provides a ventilation system adjustment system, including: the plant negative pressure gradient analysis device described in Example 4, used to obtain the air supply volume corresponding to the plant negative pressure gradient that meets the regulatory requirements.

[0064] The regulating device is connected to the analyzing device and is used to adjust the valves in the factory ventilation system pipeline according to the air supply volume, so that the factory ventilation system can obtain the factory negative pressure gradient that meets the requirements of the specifications.

[0065] It will be understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present invention, and the present invention is not limited thereto. Those skilled in the art will appreciate that various modifications and improvements can be made without departing from the spirit and substance of the present invention, and such modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A method for analyzing negative pressure gradient in a factory building, characterized in that: include: Establish a three-dimensional geometric model of the factory ventilation system; Import the 3D geometric model of the factory ventilation system into FLUENT software, and simulate and calculate the negative pressure value of each room in the factory ventilation system under the design air volume to obtain the negative pressure value of each room. The design air volume includes the supply air volume and the exhaust air volume. Determine the difference between the negative pressure value of each room and the corresponding standard requirements, and adjust the air supply volume of the corresponding room based on the judgment results and perform simulation calculations again until the negative pressure value of each room approaches the corresponding standard requirements, so as to obtain the negative pressure gradient of the factory building that meets the standard requirements; The air supply volume of the corresponding room is adjusted according to the judgment result and the simulation calculation is performed again until the negative pressure value of each room approaches the corresponding specification requirement value, which specifically includes: When the absolute value of the negative pressure value of a single room is determined to be greater than the absolute value of the value required by the specification, the supply air volume is gradually increased by a step size obtained by multiplying the difference between the exhaust air volume and the supply air volume by the third ratio, and the simulation calculation is performed again until the negative pressure value of the single room approaches the value required by the specification. When the absolute value of the negative pressure value of a single room is determined to be less than the absolute value of the value required by the specification, the supply air volume is gradually reduced by a step size obtained by multiplying the difference between the exhaust air volume and the supply air volume by the third ratio, and the simulation calculation is performed again until the negative pressure value of the single room approaches the value required by the specification. When the absolute value of the negative pressure value of the single room is equal to the absolute value of the value required by the specification, it is determined that the negative pressure value of the single room is approaching the ideal state of the value required by the specification; Dividing the three-dimensional geometric model into unstructured grids, Dividing the three-dimensional geometric model into an unstructured grid specifically includes: Keep the density change of the grid in the solution domain consistent with the gradient change of the variable being solved; Keep the mesh unit changes in the solution domain smooth; Keep the width-to-height ratio of the grid cells less than or equal to the second ratio.

2. The method for analyzing the negative pressure gradient of a factory building according to claim 1, characterized in that: Establish a 3D geometric model of the factory ventilation system, including: ICEM software was used to establish a three-dimensional geometric model of the factory ventilation system.

3. The method for analyzing the negative pressure gradient of a factory building according to claim 2, characterized in that: The three-dimensional geometric model of the factory ventilation system is established using ICEM software, specifically including: Use ICEM software to create a 3D geometric model of all rooms and pipes in the factory ventilation system; For the three-dimensional geometric model, the boundary condition of the air flow inlet is set to the velocity inlet, and the boundary conditions of the ground, wall and room ceiling are set to the wall surface, and the wall is set to an insulating wall, and the boundary condition of the exhaust outlet is set to the pressure outlet.

4. The method for analyzing the negative pressure gradient of a factory building according to claim 1, characterized in that: Before establishing the 3D geometric model of the plant ventilation system, the following steps are also included: Calculate the exhaust volume of the factory ventilation system based on the number of air changes or the method of removing waste heat; The supply air volume is calculated based on the fact that the supply air volume is equal to the exhaust air volume multiplied by the first ratio to obtain the design air volume.

5. A method for selecting an air supply fan for a ventilation system, characterized in that: The steps include: According to the analysis method of the negative pressure gradient of the plant according to any one of claims 1 to 4, the air supply volume corresponding to the negative pressure gradient of the plant that meets the requirements of the specification is obtained; Select the air supply fan of the factory ventilation system according to the air supply volume.

6. A method for regulating a ventilation system, characterized in that: The steps include: According to the analysis method of the negative pressure gradient of the plant according to any one of claims 1 to 4, the air supply volume corresponding to the negative pressure gradient of the plant that meets the requirements of the specification is obtained; Adjust the valves in the factory ventilation system pipes according to the air supply volume so that the factory ventilation system can obtain a factory negative pressure gradient that meets the requirements of the specifications.

7. An analytical device for negative pressure gradient in a factory building, characterized in that: Including modeling module, calculation module and judgment module, Modeling module, used to build a three-dimensional geometric model of the factory ventilation system, The calculation module is connected to the modeling module and is used to import the three-dimensional geometric model of the factory ventilation system into the FLUENT software stored therein, and simulate the negative pressure value of each room of the factory ventilation system under the design air volume to obtain the negative pressure value of each room, wherein the design air volume includes the supply air volume and the exhaust air volume. The judgment module is connected to the calculation module and is used to judge the difference between the negative pressure value of each room and the corresponding standard requirements, and adjust the air supply volume of the corresponding room according to the judgment result and send it to the calculation module for simulation calculation again until the negative pressure value of each room approaches the corresponding standard requirements, so as to obtain the negative pressure gradient of the factory building that meets the standard requirements; The air supply volume of the corresponding room is adjusted according to the judgment result and the simulation calculation is performed again until the negative pressure value of each room approaches the corresponding specification requirement value, which specifically includes: When the absolute value of the negative pressure value of a single room is determined to be greater than the absolute value of the value required by the specification, the supply air volume is gradually increased by a step size obtained by multiplying the difference between the exhaust air volume and the supply air volume by the third ratio, and the simulation calculation is performed again until the negative pressure value of the single room approaches the value required by the specification. When the absolute value of the negative pressure value of a single room is determined to be less than the absolute value of the value required by the specification, the supply air volume is gradually reduced by a step size obtained by multiplying the difference between the exhaust air volume and the supply air volume by the third ratio, and the simulation calculation is performed again until the negative pressure value of the single room approaches the value required by the specification. When the absolute value of the negative pressure value of the single room is equal to the absolute value of the value required by the specification, it is determined that the negative pressure value of the single room is approaching the ideal state of the value required by the specification; Wherein, the three-dimensional geometric model is divided into unstructured grids, Dividing the three-dimensional geometric model into an unstructured grid specifically includes: Keep the density change of the grid in the solution domain consistent with the gradient change of the variable being solved; Keep the mesh unit changes in the solution domain smooth; Keep the width-to-height ratio of the grid cells less than or equal to the second ratio.

8. A ventilation system adjustment system, characterized in that: include: The plant negative pressure gradient analysis device according to claim 7 is used to obtain the air supply volume corresponding to the plant negative pressure gradient that meets the specification requirements. The regulating device is connected to the analyzing device and is used to adjust the valves in the factory ventilation system pipeline according to the air supply volume, so that the factory ventilation system can obtain the factory negative pressure gradient that meets the requirements of the specifications.

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