A method for collaborative selection and calculation of a ventilation system of a boiler room of a thermal power plant

Abstract

The application discloses a kind of boiler room ventilation system collaborative selection calculation method of thermal power plant, it is related to building ventilation system design technical field.The method first obtains boiler room geometry, heat source and design temperature parameter, calculates theoretical ventilation quantity;Vertical temperature gradient model is established and neutral plane height is iteratively solved, the air density at air inlet and air outlet is determined;Flow-pressure system balance equation including air inlet louvers and streamline roof ventilator series resistance is constructed, area ratio coefficient is defined, and equations are simultaneously solved to iteratively solve the area combination of air inlet and air outlet with theoretical ventilation quantity as target.The present application realizes the system coupling of thermal pressure drive and component resistance, greatly improves design accuracy, ensures that design ventilation quantity is consistent with actual operation effect, while reducing the dependence on personal experience, improves design reliability and economy.

Description

Technical Field

[0001] This invention relates to the field of building ventilation system design technology, specifically to a collaborative selection calculation method for ventilation systems in boiler rooms of thermal power plants. Background Technology

[0002] As the core production building of a thermal power plant, the boiler room is characterized by its large size, dense heat sources, and enormous heat dissipation. The boiler itself, steam pipes, and various auxiliary machines continuously emit a large amount of waste heat. If this heat cannot be effectively dissipated in a timely manner, it will cause a sharp rise in indoor temperature, seriously threatening the safe operation and service life of equipment, and endangering the health of maintenance personnel. Therefore, establishing an efficient and reliable ventilation and heat dissipation system is a key aspect of boiler room design. A composite ventilation mode, primarily based on natural ventilation, has become the preferred solution for boiler room ventilation design both domestically and internationally due to its advantages such as no power consumption, simple operation and maintenance, and high reliability. The core air intake and exhaust components of this system are typically rainproof air intake louvers located at the lower part of the exterior walls and streamlined roof ventilators installed on the roof ridge. Together, they form a "chimney effect" ventilation loop driven by the density difference between indoor and outdoor air.

[0003] However, current industry practices for designing and selecting components for ventilation systems generally rely on empirical air change rate methods or isolated calculation methods based on simplified thermal balance, which have significant drawbacks. Empirical air change rate methods completely disregard actual heat dissipation, estimating ventilation volume solely based on volume, leading to either insufficient or excessive heat removal capacity, and the ratio of inlet and outlet areas lacks scientific basis. While simplified thermal balance methods incorporate heat dissipation calculations to determine theoretical exhaust volume, they assume uniform indoor temperature and ignore the strong vertical temperature stratification in large spaces, distorting the calculation basis for the thermal pressure driving force of ventilation. Furthermore, these methods treat inlet louvers and roof ventilators as independent, zero-resistance openings, failing to consider their actual series resistance components in the ventilation loop. Their individual resistance characteristics affect the total system airflow, causing component selection to be out of sync with actual operating points, resulting in failures where the designed ventilation volume far exceeds the system's actual achievable ventilation volume. In addition, existing methods lack quantitative iterative optimization tools for determining the optimal ratio of inlet and outlet areas to achieve maximum ventilation efficiency or optimal economy under a given thermal pressure, heavily relying on design experience, leading to blind and unreliable selection results. The aforementioned problems, such as model distortion, system decoupling, and design blindness, have become technical bottlenecks restricting the refined design of boiler room ventilation systems. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a collaborative selection and calculation method for ventilation systems in boiler rooms of thermal power plants. This method achieves system coupling between thermo-pressure drive and component resistance, significantly improves design accuracy, ensures consistency between designed ventilation volume and actual operating performance, reduces reliance on personal experience, and enhances design reliability and economy.

[0005] To achieve the above objectives, the embodiments of this invention provide the following technical solutions:

[0006] This application provides a collaborative selection calculation method for the ventilation system of a boiler room in a thermal power plant, characterized by the following steps: S1, obtaining the geometric parameters, heat source parameters, and design temperature parameters of the boiler room. The geometric parameters include the length, width, eaves height, ridge height, and roof slope of the boiler room. The heat source parameters include the heat output of each fixed heat source and its corresponding spatial location height. The design temperature parameters include the outdoor ventilation design temperature and the indoor expected average temperature. S2, calculating the theoretical ventilation volume based on the total heat dissipation of all fixed heat sources and the energy balance formula. The expression of the energy balance formula is: ;in, Expressed as theoretical ventilation volume, This represents the total heat dissipation from all fixed heat sources. Expressed as standard air density, Expressed as the specific heat capacity of standard air at constant pressure. This is expressed as the desired average indoor temperature. S3. Establish a vertical temperature gradient model that reflects the change of indoor temperature with building height, determine the center height of the air inlet louvers and the throat height of the streamlined roof ventilator, and iteratively solve for the neutral plane height when the system reaches pressure equilibrium under given conditions. Then, based on the vertical temperature gradient model, determine the indoor air density at the center height of the air inlet louvers. Indoor air density at the throat height of the streamlined roof ventilator S4. Construct the flow-pressure system balance equation with the air inlet louvers and streamlined roof ventilator as series resistance components, and establish the flow continuity equation; the expression of the flow continuity equation is: The expression for the flow-pressure system balance equation is as follows: ;in, Expressed as outdoor air density, This refers to the center height of the air intake louvers. This refers to the throat height of the streamlined roof ventilator. Represented as the height of the neutral surface. This represents the indoor air density at the center height of the air intake louvers. This represents the indoor air density at the throat height of the streamlined roof ventilator. Expressed as gravitational acceleration, This is expressed as the local resistance coefficient of the air intake louver. This is expressed as the overall resistance coefficient of the streamlined roof ventilator. This represents the wind speed at the air intake side of the louvers. This refers to the throat velocity of the streamlined roof ventilator. This represents the total effective ventilation area of ​​the streamlined roof ventilator. S5, Defines the area ratio coefficient, representing the effective net ventilation area of ​​the louvers. By simultaneously solving the flow-pressure system balance equation and the flow continuity equation, and using the theoretical ventilation volume as the design objective, the following solution is obtained: and The combined solution.

[0007] Furthermore, the vertical temperature gradient model in S3 adopts a linear distribution model, a piecewise linear distribution model, or an exponential distribution model. The linear distribution model determines a constant temperature gradient along the height direction based on the ground temperature and the temperature under the roof ridge. The piecewise linear distribution model divides the factory building along the height into a lower region, a middle heat source dense region, and an upper region, and each region sets a different temperature gradient value according to its corresponding internal heat source intensity.

[0008] Further, the specific process of iteratively solving the neutral surface height in S3 includes: S31, setting an initial value for the neutral surface height, which can be the arithmetic mean of the center height of the air inlet louvers and the throat height of the streamlined roof ventilator; S32, calculating the indoor temperature and corresponding air density at the center height of the air inlet louvers, and the indoor temperature and corresponding air density at the throat height of the streamlined roof ventilator, based on the vertical temperature gradient model; S33, based on... Calculate the inlet side thermal pressure, based on Calculate the thermal pressure on the exhaust side; S34, make a judgment and Check if the pressure balance condition is met. If not, adjust the initial value of the neutralization surface height and return to S32 for recalculation until... and If the deviation is within the preset range, obtain the convergent solution of the initial value of the neutral surface height.

[0009] Further, the specific process of iterative solution in S5 includes: S51, setting the initial value of the effective net ventilation area of ​​the louvers and the initial value of the area ratio system, and calculating the corresponding total effective ventilation area of ​​the streamlined roof ventilator; S52, calculating the air velocity at the louver inlet and the air velocity at the throat of the streamlined roof ventilator based on the flow continuity equation; S53, substituting the air velocity at the louver inlet and the air velocity at the throat of the streamlined roof ventilator into the right side of the flow-pressure system balance equation to calculate the total resistance loss, the expression of which is: S54. Calculate the total thermal-pressure driving force on the left side of the flow-pressure system equilibrium equation. Its expression is: S55. Compare the total resistance loss and the total driving force of thermal pressure. If the total resistance loss and the total driving force of thermal pressure are not equal within the preset deviation, keep the initial area ratio coefficient unchanged, adjust the initial value of the effective net ventilation area of ​​the louvers until the difference between the total resistance loss and the total driving force of thermal pressure meets the convergence condition, and obtain a combination that satisfies the theoretical ventilation volume, the initial value of the effective net ventilation area of ​​the louvers and the total effective ventilation area of ​​the streamlined roof ventilator.

[0010] Furthermore, the following steps are also included: S6, verifying the combination of the initial value of the effective net ventilation area of ​​the louvers obtained by iterative solution and the total effective ventilation area of ​​the streamlined roof ventilator, including calculating the wind speed at the air inlet of the louvers and verifying whether it meets the rainproof requirement limit, and calculating the wind speed at the throat of the streamlined roof ventilator and verifying whether it is within the high-efficiency operating wind speed range of the streamlined roof ventilator. If any verification is not satisfied, the area ratio coefficient is adjusted and the process is returned to S5 to iterate and solve again.

[0011] Furthermore, the rainproof requirements are as follows: the wind speed at the louver inlet surface is ≤2.5m / s, and the high-efficiency operating wind speed range is 2m / s ≤ the wind speed at the throat of the streamlined roof ventilator ≤8m / s. When the wind speed at the louver inlet surface exceeds the rainproof limit, the area ratio coefficient is increased to increase the total effective ventilation area of ​​the streamlined roof ventilator and reduce the effective net ventilation area of ​​the louvers. When the wind speed at the throat of the streamlined roof ventilator exceeds the high-efficiency operating range, the area ratio coefficient is adjusted in the opposite direction.

[0012] Furthermore, the following steps are also included: S7, for different area ratio coefficient values, execute S5 respectively to obtain the initial value of the effective net ventilation area of ​​the corresponding louvers and the total effective ventilation area of ​​the streamlined roof ventilator, and calculate the corresponding total area of ​​the air inlet and outlet; draw the relationship curve between the actual achievable ventilation volume and the area ratio coefficient, and the relationship curve between the total area of ​​the air inlet and outlet and the area ratio coefficient; within the range of the area ratio coefficient values ​​where the actual achievable ventilation volume meets the theoretical ventilation volume, select the interval with the smallest total area of ​​the air inlet and outlet as the optimal area ratio interval, and determine the final design selection parameters.

[0013] Furthermore, the local resistance coefficient of the air inlet louver and the total resistance coefficient of the streamlined roof ventilator are data obtained from empirical tests and data measured by a standard wind tunnel test model, respectively.

[0014] Furthermore, the center height of the air inlet louver is determined as: the height of the bottom edge of the louver installation + the height of the louver itself / 2; the throat height of the streamlined roof ventilator is determined based on the ridge height and the structural dimensions of the ventilator itself.

[0015] The beneficial effects of this invention are as follows: By constructing a complete closed-loop calculation process from parameter input to area calculation and then to optimization output, it organically combines the thermal pressure driving model with the series resistance network model for the first time, realizing the coordinated selection of air inlet louvers and streamlined roof ventilators. This fundamentally solves the problems of system decoupling and model distortion, ensuring that the designed ventilation volume is highly consistent with the actual achievable ventilation volume of the system, greatly improving the accuracy and reliability of the design. At the same time, it transforms the complex principles of fluid mechanics and heat transfer into standardized steps that engineers can follow, reducing reliance on personal experience and improving the uniformity of design efficiency and quality. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating a collaborative selection calculation method for a boiler room ventilation system in a thermal power plant, provided as an embodiment of this application. Detailed Implementation

[0017] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0018] In this invention, the terms "system" and "network" are used interchangeably. "Multiple" refers to two or more; therefore, in this invention, "multiple" can also be understood as "at least two." "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. Additionally, the character " / ", unless otherwise specified, generally indicates that the preceding and following related objects have an "or" relationship. Furthermore, it should be understood that in the description of this invention, terms such as "first" and "second" are used only for descriptive purposes and should not be construed as indicating or implying relative importance or order.

[0019] like Figure 1 As shown in the figure, this application provides a collaborative selection calculation method for the ventilation system of a boiler room in a thermal power plant. The method includes the following steps: S1, obtaining the boiler room's geometric parameters, heat source parameters, and design temperature parameters. The geometric parameters include the boiler room's length, width, eaves height, ridge height, and roof slope. The heat source parameters include the heat output of each fixed heat source and its corresponding spatial location height. The design temperature parameters include the outdoor ventilation design temperature and the indoor expected average temperature. S2, calculating the theoretical ventilation volume based on the total heat dissipation of all fixed heat sources and an energy balance formula. The expression for the energy balance formula is: ;in, Expressed as theoretical ventilation volume, This represents the total heat dissipation from all fixed heat sources. Expressed as standard air density, Expressed as the specific heat capacity of standard air at constant pressure. This is expressed as the desired average indoor temperature. S3. Establish a vertical temperature gradient model that reflects the change of indoor temperature with building height, determine the center height of the air inlet louvers and the throat height of the streamlined roof ventilator, and iteratively solve for the neutral plane height when the system reaches pressure equilibrium under given conditions. Then, based on the vertical temperature gradient model, determine the indoor air density at the center height of the air inlet louvers. Indoor air density at the throat height of the streamlined roof ventilator S4. Construct the flow-pressure system balance equation with the air inlet louvers and streamlined roof ventilator as series resistance components, and establish the flow continuity equation; the expression of the flow continuity equation is: The expression for the flow-pressure system balance equation is as follows: ;in, Expressed as outdoor air density, This refers to the center height of the air intake louvers. This refers to the throat height of the streamlined roof ventilator. Represented as the height of the neutral surface. This represents the indoor air density at the center height of the air intake louvers. This represents the indoor air density at the throat height of the streamlined roof ventilator. Expressed as gravitational acceleration, This is expressed as the local resistance coefficient of the air intake louver. This is expressed as the overall resistance coefficient of the streamlined roof ventilator. This represents the wind speed at the air intake side of the louvers. This refers to the throat velocity of the streamlined roof ventilator. This represents the total effective ventilation area of ​​the streamlined roof ventilator. S5, Defines the area ratio coefficient, representing the effective net ventilation area of ​​the louvers. By simultaneously solving the flow-pressure system balance equation and the flow continuity equation, and using the theoretical ventilation volume as the design objective, the following solution is obtained: and The combined solution.

[0020] In another possible embodiment, the geometric parameters, heat source parameters, and design temperature parameters of the boiler room are first obtained. The geometric parameters are directly extracted from the boiler room architectural design drawings, including the length, width, eaves height, ridge height, and roof slope of the boiler room. The heat source parameters are obtained through equipment nameplate parameters or plant-wide heat balance calculations, including the calorific value of each fixed heat source and its corresponding spatial position height. Here, fixed heat sources specifically refer to all equipment that dissipates heat into the room, such as the boiler body, steam drum, main steam pipeline, induced draft fan, and forced draft fan. The spatial position height is the vertical height of the geometric center of the heat source from the ground. The design temperature parameters are determined based on the meteorological data and process requirements of the project site, including the outdoor ventilation design temperature and the indoor expected average temperature. The outdoor ventilation design temperature adopts the summer ventilation outdoor calculation temperature specified in the "Code for Design of Building Structures" of the project site. The indoor expected average temperature is determined based on the process equipment operation requirements and the "Hygienic Standard for Industrial Enterprise Design", usually a value between 35°C and 40°C. Next, based on the total heat dissipation of all fixed heat sources and the energy balance formula, the theoretical ventilation volume is calculated. First, the heat output of all fixed heat sources is added together to obtain the total heat dissipation of the boiler room. Then, the total heat dissipation is substituted into the energy balance formula to calculate the theoretical ventilation volume. In the formula The standard air density is usually taken as 1.165 kg / m³, corresponding to the density of dry air at 30°C. Taking the standard air specific heat capacity at constant pressure as 1.005 kJ / (kg・℃), the theoretical ventilation volume... This refers to the minimum ventilation volume required to discharge the total heat dissipation of the boiler room and maintain the desired indoor temperature. This is expressed as the desired average indoor temperature. This is represented as the outdoor ventilation design temperature. Then, a vertical temperature gradient model reflecting the indoor temperature variation with building height is established to determine the center height of the air intake louvers. throat height of streamlined roof ventilator The height of the neutral surface when the system reaches pressure equilibrium under given conditions is iteratively solved. Then, based on the vertical temperature gradient model, the indoor air density at the center height of the air inlet louvers was determined. Indoor air density at the throat height of streamlined roof ventilators The vertical temperature gradient model is a mathematical model describing the increase in air temperature with increasing height inside a tall boiler room. It is used to characterize the temperature stratification phenomenon caused by the rising of hot air. (The center height of the air inlet louvers is also mentioned.) This refers to the vertical height of the geometric center of the louvers from the ground, and the height of the throat of the streamlined roof ventilator. This refers to the vertical height of the center of the ventilator throat section from the ground, and the neutral plane height. This refers to the height of the neutral plane in the ventilation system where the indoor and outdoor static pressures are equal. Above this plane, the indoor pressure is higher than the outdoor air, which is discharged through the roof ventilator. Below this plane, the indoor pressure is lower than the outdoor air, which enters the room through the louvers. By iteratively solving for the neutral plane height, the effective thermal pressure difference acting on the air inlet and outlet can be accurately calculated. Then, a flow-pressure system equilibrium equation is constructed, treating the air inlet louvers and streamlined roof ventilator as series resistance components. A flow continuity equation is also established, based on the law of conservation of mass, and its expression is: In the formula This represents the actual ventilation volume of the system. The effective net ventilation area of ​​a louver is the net area that air is actually allowed to pass through after deducting all obstructions such as the slats, frame, insect screen, and rainproof panel. The wind speed at the air intake side of the louvers. The total effective ventilation area of ​​the streamlined roof ventilator is the net area at the ventilator throat where air is allowed to pass through. For the throat velocity of the streamlined roof ventilator, the flow-pressure system balance equation is established based on the law of conservation of energy, and the expression is: In the formula Outdoor air density is based on outdoor ventilation design temperature. calculate, Take the acceleration due to gravity as 9.8 m / s². The local resistance coefficient of the air inlet louver. The equation represents the overall resistance coefficient of the streamlined roof ventilator. It shows that the total thermal pressure driving force of the system equals the sum of the resistance losses of the air inlet louvers and the streamlined roof ventilator, reflecting their series coupling relationship. Finally, the area ratio coefficient is defined. By simultaneously solving the flow-pressure system equilibrium equations and the flow continuity equation, and using the theoretical ventilation volume as the design objective, the following solution is obtained: and Combinatorial solution, area ratio coefficient This is the ratio of the total effective ventilation area of ​​the streamlined roof ventilator to the effective net ventilation area of ​​the air inlet louvers. It is the core optimization variable of this invention. After solving the above two equations, we can... elimination by substitution Get only contains and The equation, then using the theoretical ventilation volume Adjust the target through iterative calculation The value of is taken until the calculated actual ventilation volume of the system meets the requirements. ≥ Thus, the corresponding and The combined solution.

[0021] By constructing a complete closed-loop calculation process from parameter input to area calculation and then to optimization output, the thermal pressure driven model and the series resistance network model were organically combined for the first time. This enabled the coordinated selection of air inlet louvers and streamlined roof ventilators, fundamentally solving the problems of system decoupling and model distortion. It ensured that the designed ventilation volume was highly consistent with the actual achievable ventilation volume of the system, greatly improving the accuracy and reliability of the design. At the same time, it transformed the complex principles of fluid mechanics and heat transfer into standardized steps that engineers could follow, reducing reliance on personal experience and improving the uniformity of design efficiency and quality.

[0022] In this embodiment of the application, the vertical temperature gradient model in S3 adopts a linear distribution model, a piecewise linear distribution model, or an exponential distribution model. The linear distribution model determines a constant temperature gradient along the height direction based on the ground temperature and the temperature under the roof ridge. The piecewise linear distribution model divides the factory building along the height into a lower region, a middle heat source dense region, and an upper region, and each region sets a different temperature gradient value according to its corresponding internal heat source intensity.

[0023] In another possible embodiment, when establishing the vertical temperature gradient model, a suitable model can be selected based on the distribution of heat sources within the boiler room. When the heat source distribution is relatively uniform, a linear distribution model is used. This model determines a constant temperature gradient along the height direction based on the ground temperature and the temperature under the roof ridge. For example, when the ground temperature is 32℃, the temperature under the roof ridge is 47℃, and the total height of the boiler room is 52m, the temperature gradient is (47-32) / 52≈0.288℃ / m, where the indoor temperature at any height h is... When the heat source distribution is uneven, a piecewise linear distribution model is used. This model divides the plant into a lower region, a middle region with concentrated heat sources, and an upper region along its height. Each region is assigned a different temperature gradient value based on the intensity of its corresponding internal heat source. For example, the 0-15m range is designated as the lower region, where there are fewer heat sources, and the temperature gradient is 0.15℃ / m. The 15-30m range is designated as the middle region, where the main heat sources such as the boiler body and steam drum are concentrated, and the temperature gradient is 0.40℃ / m. The 30-52m range is designated as the upper region, where there are no concentrated heat sources and heat transfer relies solely on the rising heat plume, and the temperature gradient is 0.25℃ / m. When the heat plume rises in a concentrated manner, an exponential distribution model is used. In this model, the indoor temperature changes exponentially with height. The distribution curve can be obtained through CFD numerical simulation pre-analysis fitting. During fitting, the temperature field inside the boiler room is first simulated using CFD software to extract temperature values ​​at different heights, and then an exponential function is used to fit the expression for temperature variation with height.

[0024] By providing three vertical temperature gradient models—linear distribution, piecewise linear distribution, and exponential distribution—it can be flexibly selected according to the actual characteristics of the heat source distribution in the boiler room. It can more accurately simulate the indoor temperature distribution under different operating conditions, significantly improve the accuracy of thermal pressure driving force calculation, and is especially suitable for complex operating conditions with uneven heat source distribution, making the calculation results more consistent with actual operating conditions.

[0025] In this embodiment of the application, the specific process of iteratively solving the neutral surface height in step S3 includes: S31, setting an initial value for the neutral surface height, wherein the initial value can be the arithmetic mean of the center height of the air inlet louver and the throat height of the streamlined roof ventilator; S32, calculating the indoor temperature and corresponding air density at the center height of the air inlet louver, and the indoor temperature and corresponding air density at the throat height of the streamlined roof ventilator, based on the vertical temperature gradient model; S33, based on... Calculate the inlet side thermal pressure, based on Calculate the thermal pressure on the exhaust side; S34, make a judgment and Check if the pressure balance condition is met. If not, adjust the initial value of the neutralization surface height and return to S32 for recalculation until... and If the deviation is within the preset range, obtain the convergent solution of the initial value of the neutral surface height.

[0026] In another possible embodiment, when iteratively solving for the neutral surface height, an initial value for the neutral surface height is first set. The initial value can be taken as the center height of the air inlet louvers. throat height of streamlined roof ventilator The arithmetic mean is Next, the center height of the air inlet louvers is calculated based on the vertical temperature gradient model. Indoor temperature and the corresponding air density and the throat height of the streamlined roof ventilator Indoor temperature and the corresponding air density Air density is calculated using the ideal gas law, expressed as follows: In the formula Air temperature, in °C. This refers to air density, expressed in kg / m³. Then, based on... Calculate the inlet side thermal pressure and based on Calculate the exhaust-side thermal pressure. The intake-side thermal pressure refers to the pressure difference that drives outdoor air into the room, and the exhaust-side thermal pressure refers to the pressure difference that drives indoor air out of the room. Finally, determine whether the intake-side and exhaust-side thermal pressures meet the pressure balance condition. If not, adjust the initial value of the neutralization surface height and return to S32 for recalculation until the deviation between the intake-side and exhaust-side thermal pressures is within a preset range, typically ≤0.1 Pa. Obtain the convergent solution for the neutralization surface height. When adjusting the neutralization surface height, if the intake-side thermal pressure is greater than the exhaust-side thermal pressure, increase the neutralization surface height; if the intake-side thermal pressure is less than the exhaust-side thermal pressure, decrease the neutralization surface height.

[0027] By accurately calculating the neutralization surface height based on the actual temperature distribution and the location of the air inlet and outlet, the error caused by the fixed neutralization surface assumption is eliminated, providing a reliable basis for the calculation of the thermal pressure driving force. At the same time, the iterative process is clear and explicit, and the calculation results have good repeatability and consistency.

[0028] In this embodiment, the specific process of iterative solution in S5 includes: S51, setting the initial value of the effective net ventilation area of ​​the louvers and the initial value of the area ratio system, and calculating the corresponding total effective ventilation area of ​​the streamlined roof ventilator; S52, calculating the wind speed at the louver inlet and the wind speed at the throat of the streamlined roof ventilator based on the flow continuity equation; S53, substituting the wind speed at the louver inlet and the wind speed at the throat of the streamlined roof ventilator into the right side of the flow-pressure system balance equation to calculate the total resistance loss, the expression of which is: S54. Calculate the total thermal-pressure driving force on the left side of the flow-pressure system equilibrium equation. Its expression is: S55. Compare the total resistance loss and the total driving force of thermal pressure. If the total resistance loss and the total driving force of thermal pressure are not equal within the preset deviation, keep the initial area ratio coefficient unchanged, adjust the initial value of the effective net ventilation area of ​​the louvers until the difference between the total resistance loss and the total driving force of thermal pressure meets the convergence condition, and obtain a combination that satisfies the theoretical ventilation volume, the initial value of the effective net ventilation area of ​​the louvers and the total effective ventilation area of ​​the streamlined roof ventilator.

[0029] In another possible embodiment, during iterative solution and When solving the combined solution, first set the initial value of the effective net ventilation area of ​​the louvers. and the initial value of the area ratio coefficient And calculate the total effective ventilation area of ​​the corresponding streamlined roof ventilator. The initial value can be selected based on engineering experience, for example... A value between 1.2 and 1.5 can be used. Then, the air velocity at the louver inlet face is calculated based on the flow continuity equation. and the throat velocity of the streamlined roof ventilator Then adjust the airflow speed on the louvered inlet side. and the throat velocity of the streamlined roof ventilator Substituting into the right side of the flow-pressure system balance equation, calculate the total resistance loss. Then, the total thermal pressure driving force on the left side of the flow-pressure system equilibrium equation is calculated. Finally, compare the total resistance loss with the total driving force of hot pressing. If the total resistance loss and the total driving force of hot pressing are not equal (the preset deviation is usually ≤0.1 Pa), then maintain the initial value of the area ratio coefficient. Keep the initial value of the effective net ventilation area of ​​the louvers unchanged. If the total resistance loss is less than the total driving force of thermal pressure, it indicates that the current area is too large and the system resistance is insufficient. The actual ventilation volume will exceed the design value, and it needs to be reduced. To increase wind speed and resistance, if the total resistance loss exceeds the total driving force of thermal pressure, it indicates that the current area is too small and the system resistance is too high. The actual ventilation volume will be lower than the design value, and it is necessary to increase the area. To reduce wind speed and resistance, repeat steps S52 to S55 until the difference between the total resistance loss and the total driving force of thermal pressure satisfies the convergence condition, and obtain the effective net ventilation area of ​​the louvers that meets the theoretical ventilation volume. Total effective ventilation area of ​​streamlined roof ventilator The combination of .

[0030] By keeping the area ratio constant and adjusting the louver area, the total system resistance loss and the total thermal pressure driving force are balanced, ensuring that the calculated area combination can achieve the theoretical ventilation volume.

[0031] In this embodiment of the application, the following steps are also included: S6, verifying the combination of the initial value of the effective net ventilation area of ​​the louvers obtained by iterative solution and the total effective ventilation area of ​​the streamlined roof ventilator, including calculating the wind speed at the air inlet of the louvers and verifying whether it meets the rainproof requirement limit, and calculating the wind speed at the throat of the streamlined roof ventilator and verifying whether it is within the high-efficiency operating wind speed range of the streamlined roof ventilator. If any verification is not satisfied, the area ratio coefficient is adjusted and the process is returned to S5 to iterate and solve again.

[0032] In another possible embodiment, after obtaining the initial area combination, the combination of the effective net ventilation area of ​​the louvers and the total effective ventilation area of ​​the streamlined roof ventilator obtained by iterative solution is checked. First, the wind speed at the air inlet surface of the louvers is calculated. Verify whether it meets the rainproof requirements, and then calculate the wind speed at the throat of the streamlined roof ventilator. Verify whether it is within the high-efficiency operating wind speed range of the streamlined roof ventilator. If any verification fails, adjust the area ratio coefficient. Then return to S5 to iterate and solve again. When adjusting the area ratio coefficient, increase It will increase , reduce Thus reducing ,improve , reduce It will decrease Increase thereby improving ,reduce .

[0033] After obtaining the initial area combination, the system automatically checks the rain protection requirements and high-efficiency operation requirements. If they are not met, the system automatically adjusts the area ratio coefficient and recalculates, which improves the system's operational reliability and economy, while ensuring that the system can operate stably and efficiently under various working conditions.

[0034] In this embodiment, the rainproof requirement limit is: the wind speed at the louver inlet surface is ≤2.5m / s, and the high-efficiency operating wind speed range is 2m / s ≤ the wind speed at the throat of the streamlined roof ventilator ≤8m / s. When the wind speed at the louver inlet surface exceeds the rainproof limit, the area ratio coefficient is increased to increase the total effective ventilation area of ​​the streamlined roof ventilator and decrease the effective net ventilation area of ​​the louvers. When the wind speed at the throat of the streamlined roof ventilator exceeds the high-efficiency operating range, the area ratio coefficient is adjusted in the opposite direction.

[0035] In another possible embodiment, when performing engineering constraint verification, the rainproof requirement limit is ≤2.5m / s for the air velocity at the louver inlet surface. This is because when the air velocity at the louver inlet surface exceeds 2.5m / s, rainwater will be carried into the room by the high-speed airflow, damaging internal electrical equipment and instruments. The efficient operating air velocity range is 2m / s ≤ streamlined roof ventilator throat velocity ≤8m / s. This is because when the streamlined roof ventilator throat velocity is below 2m / s, the airflow inside the ventilator becomes turbulent, significantly reducing ventilation efficiency. When the throat velocity is above 8m / s, the ventilator resistance increases sharply and is prone to vibration and noise. When the air velocity at the louver inlet surface exceeds 2.5m / s, the area ratio coefficient can be increased. To reduce the air velocity at the louver inlet, the total effective ventilation area of ​​the streamlined roof ventilator is increased while the effective net ventilation area of ​​the louvers is reduced. When the throat velocity of the streamlined roof ventilator is below 2 m / s, the area ratio coefficient is reduced. To increase the ventilator's throat velocity, the total effective ventilation area of ​​the streamlined roof ventilator is reduced while the effective net ventilation area of ​​the louvers is increased. When the throat velocity of the streamlined roof ventilator exceeds 8 m / s, the area ratio coefficient is increased. The total effective ventilation area of ​​the streamlined roof ventilator is increased while the effective net ventilation area of ​​the louvers is reduced, thereby lowering the ventilator throat velocity.

[0036] In this embodiment of the application, the following steps are also included: S7, for different area ratio coefficient values, S5 is executed respectively to obtain the initial value of the effective net ventilation area of ​​the corresponding louvers and the total effective ventilation area of ​​the streamlined roof ventilator, and the corresponding total area of ​​the air inlet and outlet is calculated; the relationship curve between the actual achievable ventilation volume and the area ratio coefficient, and the relationship curve between the total area of ​​the air inlet and outlet and the area ratio coefficient are plotted; within the range of the area ratio coefficient values ​​where the actual achievable ventilation volume meets the theoretical ventilation volume, the interval with the smallest total area of ​​the air inlet and outlet is selected as the optimal area ratio interval, and the final design selection parameters are determined.

[0037] In another possible embodiment, after obtaining the area combination that satisfies the engineering constraints, global optimization is performed for different area ratio coefficients. The value, for example =0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, respectively, and obtain the corresponding effective net ventilation area of ​​the louvers and the total effective ventilation area of ​​the streamlined roof ventilator through S5, and calculate the corresponding total area of ​​the air inlet and outlet. Then plot the actual ventilation volume. With area ratio coefficient The relationship curve, and the total area of ​​the air inlet and outlet. With area ratio coefficient The relationship curve shows that the actual achievable ventilation volume meets the theoretical ventilation volume. Within the range of area ratio coefficient values, identify platform areas where ventilation volume changes gradually. When it changes within a certain range The total area of ​​the air inlet and outlet remains basically unchanged within the platform area. The smallest interval is taken as the optimal area ratio interval, and the final design selection parameters are determined.

[0038] By introducing a global optimization step and plotting system performance curves under different area ratio coefficients, the platform area with a gradual change in ventilation volume is identified. Within the platform area, the ratio scheme with the smallest total intake and exhaust area is selected. Under the premise of ensuring ventilation performance, the initial investment is reduced to the maximum extent, achieving the optimal balance between technology and economy, while providing designers with intuitive decision-making basis.

[0039] In this embodiment, the local resistance coefficient of the air inlet louver and the total resistance coefficient of the streamlined roof ventilator are data obtained from empirical tests and data measured by a standard wind tunnel test model, respectively.

[0040] In another possible embodiment, the local drag coefficient of the air inlet louver... The specific construction of the louvers, including blade type, blade angle, whether they have insect screens, and whether they have rainproof panels, should be considered. Data from third-party testing provided by the manufacturer should be used, or industry-recognized typical values ​​specified in the *Industrial Ventilation Design Manual* should be adopted. For example, the local resistance coefficient of a 45° rainproof fixed slanted louver with an insect screen is typically 8 to 10, while that without an insect screen is typically 5 to 7. The overall resistance coefficient of streamlined roof ventilators should also be considered. The data was obtained from wind tunnel tests based on the GB / T14295 "Air Filters" standard provided by the manufacturer. This data reflects the resistance characteristics of the ventilator at different wind speeds. For example, the overall resistance coefficient of commonly used throat-type streamlined roof ventilators is usually 2 to 3.

[0041] In this embodiment, the center height of the air inlet louver is determined as: the height of the bottom edge of the louver installation + the height of the louver itself / 2; the throat height of the streamlined roof ventilator is determined based on the ridge height and the structural dimensions of the ventilator itself.

[0042] In another possible embodiment, when determining the center height of the air inlet louver and the throat height of the streamlined roof ventilator, the center height of the air inlet louver is determined as the height of the bottom edge of the louver installation plus half the height of the louver itself. The air inlet louver is usually installed on the lower part of the side wall. The height of the bottom edge of the installation is the vertical height of the bottom of the louver from the ground, generally taken as 0.5m to 1.5m to avoid water accumulation on the ground. The height of the louver itself is the vertical dimension of the louver, usually taken as 3m to 5m. For example, if the bottom edge height of the louver installation is 1.5m and the height of the louver itself is 4m, then the center height is... The throat height of a streamlined roof ventilator is determined based on the ridge height and the ventilator's own structural dimensions. The streamlined roof ventilator is installed at the ridge, and the throat height is the ridge height minus half the ventilator's own height, or it can be determined directly from the product sample provided by the ventilator manufacturer. For example, if the ridge height is 52m and the ventilator's own height is 3m, then the throat height... .

[0043] The optional embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above embodiments. Within the scope of the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical solutions of the embodiments of the present invention, and these simple modifications all fall within the protection scope of the embodiments of the present invention.

[0044] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not describe the various possible combinations separately.

[0045] Furthermore, various different implementations of the present invention can be combined arbitrarily, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed in the present invention.

Claims

1. A method for collaborative selection and calculation of a ventilation system for a boiler room of a thermal power plant, characterized in that, Includes the following steps: S1. Obtain the geometric parameters, heat source parameters, and design temperature parameters of the boiler room. The geometric parameters include the length, width, eaves height, ridge height, and roof slope of the boiler room. The heat source parameters include the calorific value of each fixed heat source and its corresponding spatial location height. The design temperature parameters include the outdoor ventilation design temperature and the indoor expected average temperature. S2. Calculate the theoretical ventilation volume based on the total heat dissipation of all fixed heat sources and the energy balance formula. The expression for the energy balance formula is: ;in, Expressed as theoretical ventilation volume, This represents the total heat dissipation from all fixed heat sources. Expressed as standard air density, Expressed as the specific heat capacity of standard air at constant pressure. This is expressed as the desired average indoor temperature. This is expressed as the outdoor ventilation design temperature; S3. Establish a vertical temperature gradient model that reflects the change in indoor temperature with building height, determine the center height of the air inlet louvers and the throat height of the streamlined roof ventilator, and iteratively solve for the neutral plane height when the system reaches pressure equilibrium under given conditions. Then, based on the vertical temperature gradient model, determine the indoor air density at the center height of the air inlet louvers. Indoor air density at the throat height of the streamlined roof ventilator ; S4. Construct the flow-pressure system balance equation with the air inlet louvers and streamlined roof ventilator as series resistance components, and establish the flow continuity equation. The expression for the flow continuity equation is: ； The expression for the flow-pressure system balance equation is as follows: ； in, Expressed as outdoor air density, This refers to the center height of the air intake louvers. This refers to the throat height of the streamlined roof ventilator. Represented as the height of the neutral surface. This represents the indoor air density at the center height of the air intake louvers. This represents the indoor air density at the throat height of the streamlined roof ventilator. Expressed as gravitational acceleration, This is expressed as the local resistance coefficient of the air intake louver. This is expressed as the overall resistance coefficient of the streamlined roof ventilator. This represents the wind speed at the air intake side of the louvers. This refers to the throat velocity of the streamlined roof ventilator. This represents the total effective ventilation area of ​​the streamlined roof ventilator. This represents the effective net ventilation area of ​​the louvers; S5. Define the area ratio coefficient. By simultaneously solving the flow-pressure system balance equation and the flow continuity equation, and using the theoretical ventilation volume as the design objective, the following solution is obtained: and The combined solution.

2. The method of claim 1, wherein, The vertical temperature gradient model in S3 adopts a linear distribution model, a piecewise linear distribution model, or an exponential distribution model. The linear distribution model determines a constant temperature gradient along the height direction based on the ground temperature and the temperature under the roof ridge. The piecewise linear distribution model divides the factory building along the height into a lower region, a middle heat source dense region, and an upper region, and each region sets a different temperature gradient value according to its corresponding internal heat source intensity.

3. The method of claim 2, wherein the method is characterized by, The specific process of iteratively solving the height of the neutral surface in S3 includes: S31. Set an initial value for the height of the neutral surface. The initial value can be the arithmetic mean of the center height of the air inlet louver and the throat height of the streamlined roof ventilator. S32. Calculate the indoor temperature and corresponding air density at the center height of the air inlet louver, and the indoor temperature and corresponding air density at the throat height of the streamlined roof ventilator, based on the vertical temperature gradient model. S33、based on calculating the air intake side thermal pressure, based on calculating the air exhaust side thermal pressure; S34, Judgment and Check if the pressure balance condition is met. If not, adjust the initial value of the neutralization surface height and return to S32 for recalculation until... and If the deviation is within the preset range, obtain the convergent solution of the initial value of the neutral surface height.

4. The method of claim 1, wherein, The specific process of iterative solution described in S5 includes: S51. Set the initial value of the effective net ventilation area of ​​the louvers and the initial value of the area matching system, and calculate the total effective ventilation area of ​​the corresponding streamlined roof ventilator. S52. Calculate the air velocity at the louver inlet and the air velocity at the throat of the streamlined roof ventilator based on the aforementioned flow continuity equation. S53, the louver inlet face wind speed and streamline roof ventilator throat wind speed are substituted into the right side of the flow-pressure system balance equation, the total resistance loss is calculated, and the expression is: ; S54, the thermal pressure total driving force on the left side of the flow-pressure system balance equation is calculated, which is expressed as: ; S55. Compare the total resistance loss and the total driving force of thermal pressure. If the total resistance loss and the total driving force of thermal pressure are not equal within the preset deviation, keep the initial area ratio coefficient unchanged, adjust the initial value of the effective net ventilation area of ​​the louvers until the difference between the total resistance loss and the total driving force of thermal pressure meets the convergence condition, and obtain a combination that satisfies the theoretical ventilation volume, the initial value of the effective net ventilation area of ​​the louvers, and the total effective ventilation area of ​​the streamlined roof ventilator.

5. The method of claim 4, wherein the method is characterized by, It also includes the following steps: S6. Verify the combination of the initial value of the effective net ventilation area of ​​the louvers obtained by iterative solution and the total effective ventilation area of ​​the streamlined roof ventilator. This includes calculating the wind speed at the air inlet of the louvers and verifying whether it meets the rainproof requirements, and calculating the wind speed at the throat of the streamlined roof ventilator and verifying whether it is within the high-efficiency operating wind speed range of the streamlined roof ventilator. If any verification fails, adjust the area ratio coefficient and return to S5 to iterate and solve again.

6. The method of claim 5, wherein the method is characterized by, The rainproof requirements are as follows: the wind speed at the louver inlet surface is ≤2.5m / s, and the high-efficiency operating wind speed range is 2m / s ≤ the wind speed at the throat of the streamlined roof ventilator ≤8m / s. When the wind speed at the louver inlet surface exceeds the rainproof limit, the area ratio coefficient is increased to increase the total effective ventilation area of ​​the streamlined roof ventilator and reduce the effective net ventilation area of ​​the louvers. When the wind speed at the throat of the streamlined roof ventilator exceeds the high-efficiency operating range, the area ratio coefficient is adjusted in the opposite direction.

7. The method of claim 1, wherein the method is characterized by: It also includes the following steps: S7. For different area ratio coefficient values, execute S5 to obtain the initial value of the effective net ventilation area of ​​the corresponding louvers and the total effective ventilation area of ​​the streamlined roof ventilator, and calculate the corresponding total area of ​​the air inlet and outlet; plot the relationship curve between the actual achievable ventilation volume and the area ratio coefficient, and the relationship curve between the total area of ​​the air inlet and outlet and the area ratio coefficient; within the range of area ratio coefficient values ​​where the actual achievable ventilation volume meets the theoretical ventilation volume, select the interval with the smallest total area of ​​the air inlet and outlet as the optimal area ratio interval, and determine the final design selection parameters.

8. The collaborative selection calculation method for the ventilation system of a thermal power plant boiler room according to claim 1, characterized in that, The local resistance coefficient of the air inlet louvers and the total resistance coefficient of the streamlined roof ventilator are data obtained from empirical tests and data measured by a standard wind tunnel test model, respectively.

9. The method of claim 1, wherein the method is characterized by, The center height of the air inlet louver is determined as follows: height of the bottom edge of the louver installation + height of the louver itself / 2; the throat height of the streamlined roof ventilator is determined based on the ridge height and the structural dimensions of the ventilator itself.

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