A radioactive material exhaust filtration system

Abstract

The utility model provides a kind of radioactive material exhaust filter system, including frequency conversion exhaust fan, exhaust pipe, regulating valve, nuclear grade air filter, pressure tap plate, multiple pressure sensors, PLC controller, frequency converter and data transmission line. System is through real-time monitoring filter and the pressure difference before and after hole plate, and the air volume is calculated by PLC controller and adjusts fan frequency, maintains exhaust volume stable. When filter resistance increases to initial value two times, it is automatically alarmed to replace filter element. The system realizes air volume automatic control and filter state real-time monitoring, effectively guarantees exhaust effect and operation safety, while fan low-frequency operation significantly reduces energy consumption, with efficient, energy-saving, reliable characteristics.

Description

Technical Field

[0001] This utility model relates to the field of ventilation and air purification equipment technology, and in particular to an exhaust filtration system containing radioactive materials. Background Technology

[0002] In nuclear facilities, laboratories, or production workshops, air containing radioactive materials cannot be directly discharged and must be purified by nuclear-grade air filters. During operation, nuclear-grade air filters continuously trap radioactive particles, causing their resistance to gradually increase, thus affecting the system's airflow. Traditional fixed-frequency exhaust systems cannot automatically adjust airflow, leading to a gradual decrease in system airflow, affecting the indoor negative pressure environment and personnel health. Furthermore, fixed-frequency fans always operate at rated power, resulting in high energy consumption and poor energy efficiency.

[0003] In existing technologies, the need to replace filter cartridges is typically determined by manually checking the filter differential pressure periodically. This method has low automation and poses health risks. Therefore, there is an urgent need for an exhaust filtration system that can automatically adjust airflow, monitor filter status in real time, and achieve energy-saving performance. Utility Model Content

[0004] The purpose of this invention is to provide an exhaust filtration system containing radioactive materials. Through the coordinated operation of a variable frequency fan, a PLC controller, a pressure measuring orifice plate, and multiple pressure sensors, it can achieve automatic adjustment of air volume, real-time monitoring and alarm of filter status, and significantly reduce system energy consumption.

[0005] According to the purpose of this utility model, this utility model provides an exhaust filtration system containing radioactive materials, including a variable frequency exhaust fan, an exhaust duct, a nuclear-grade air filter, a pressure measuring orifice plate, multiple pressure sensors, a PLC controller, and a frequency converter. One end of the exhaust duct is connected to the room where the radioactive materials are emitted, and the other end of the exhaust duct leads to the outside. The nuclear-grade air filter, the pressure measuring orifice plate, the regulating valve, and the variable frequency exhaust fan are sequentially arranged on the exhaust duct. The pressure sensors are respectively arranged at the front end of the nuclear-grade air filter, the rear end of the nuclear-grade air filter, and the rear end of the pressure measuring orifice plate. The PLC controller is connected to the pressure sensors and the frequency converter.

[0006] Furthermore, the number of pressure sensors is three, and the three pressure sensors are respectively disposed at the front end of the nuclear-grade air filter, the rear end of the nuclear-grade air filter (i.e., the front end of the pressure measuring orifice plate), and the rear end of the pressure measuring orifice plate.

[0007] Furthermore, the PLC controller is connected to each of the pressure sensors and the frequency converter via a data transmission line.

[0008] Furthermore, the pressure measuring plate is provided with pressure measuring holes for measuring the pressure difference on both sides of the plate.

[0009] Furthermore, the regulating valve is disposed in the exhaust pipe, and the regulating valve is located between the nuclear-grade air filter and the variable frequency exhaust fan.

[0010] Furthermore, the frequency converter is electrically connected to the variable frequency exhaust fan and is used to adjust the fan speed.

[0011] Furthermore, the PLC controller has data storage and historical query functions.

[0012] Furthermore, the pressure measuring orifice plate is a standardized orifice plate, and its flow coefficient k has been calibrated experimentally.

[0013] Furthermore, the system is used in nuclear facilities or sites containing radioactive materials.

[0014] Furthermore, all pressure sensors are differential pressure sensors, used to monitor the pressure at various points in real time and transmit the data to the PLC controller.

[0015] This utility model's technical solution achieves automatic and stable adjustment of the exhaust system's airflow through the coordinated control of a variable frequency fan, PLC controller, and multiple sensors. This effectively overcomes the airflow attenuation problem caused by increased filter resistance, ensuring a stable and reliable negative pressure environment in rooms where radioactive materials are emitted. The system can monitor filter pressure differential changes in real time and automatically alarm when resistance increases significantly, greatly improving the timeliness and safety of filter replacement and avoiding the health risks of manual on-site inspections. Simultaneously, the fan operates at a consistently low frequency, resulting in significantly reduced energy consumption and remarkable energy-saving effects. The overall system has a reasonable structure, sensitive response, and high reliability, making it highly practical and worthy of widespread application. Attached Figure Description

[0016] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of an embodiment of the present utility model; Figure 2 This is an embodiment of the present utility model. Figure 1 Sectional view of 1-1; In the diagram: 1. Variable frequency exhaust fan; 2. Regulating valve; 3. Exhaust duct; 4. Pressure sensor; 5. Pressure measuring orifice plate; 6. Nuclear-grade air filter; 7. PLC controller; 8. Frequency converter; 9. Data transmission line; 10. Pressure measuring orifice. Detailed Implementation

[0018] The technical solution of this utility model will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0019] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0020] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0021] Example 1 like Figure 1 and Figure 2 As shown, a radioactive material exhaust filtration system includes a variable frequency exhaust fan 1, an exhaust duct 3, a regulating valve 2, a nuclear-grade air filter 6, a pressure orifice plate 5, three pressure sensors 4, a PLC controller 7, a frequency converter 8, and a data transmission line 9, wherein: The exhaust duct 3 is installed in the room where radioactive materials are emitted, with the other end of the exhaust duct 3 located outdoors. A nuclear-grade air filter 6, a pressure measuring orifice plate 5, a regulating valve 2, and a variable-frequency exhaust fan 1 are sequentially installed on the exhaust duct 3. This system is used in nuclear facilities or locations containing radioactive materials. Air containing radioactive materials is filtered by the nuclear-grade air filter 6, and the clean air flows through the pressure measuring orifice plate 5 before being discharged by the variable-frequency exhaust fan 1.

[0022] Pressure sensors 4 are installed before and after the nuclear-grade air filter 6 and before and after the pressure measuring orifice plate 5, respectively, to monitor the pressure at each point in real time and transmit the signals to the PLC controller 7 through the data transmission line 9.

[0023] The PLC controller 7 calculates the air volume in real time based on the pressure difference across the pressure measuring orifice plate and controls the fan frequency by adjusting the frequency converter to stabilize the system air volume at the set value. When the pressure difference across the nuclear-grade air filter reaches twice the initial value, the PLC issues an alarm signal, prompting the filter element to be replaced.

[0024] In this embodiment, the nuclear-grade air filter 6 is used to filter air containing radioactive materials. The regulating valve 2 is used for initial system balance adjustment and is at a fixed opening during operation.

[0025] In this embodiment, three pressure sensors 4 are respectively located at the front end of the nuclear-grade air filter 6, the rear end of the nuclear-grade air filter 6 (i.e., the front end of the pressure measuring orifice plate 5), and the rear end of the pressure measuring orifice plate 5.

[0026] The pressure measuring orifice plate 5 is provided with pressure measuring holes 10 for measuring the pressure difference across the orifice plate. The pressure measuring orifice plate 5 is a standardized orifice plate with a calibrated flow coefficient k.

[0027] The PLC controller 7 is connected to each pressure sensor 4 and the frequency converter 8 via data transmission line 9. The PLC controller 7 also has data storage and historical query functions.

[0028] The airflow control method for the above-mentioned exhaust filtration system includes the following steps: Real-time monitoring of the pressure difference across the pressure measuring orifice plate 5; Calculate the real-time air volume based on the pressure difference; The real-time air volume is compared with the set air volume, and the frequency of the variable frequency fan is adjusted by the PLC controller 7 to maintain a stable air volume.

[0029] The formula for calculating air volume is: ; Where v is wind speed, k is flow coefficient, ΔP is pressure difference, and ρ is air density.

[0030] When the air volume is lower than the set value, PLC controller 7 controls the frequency converter to increase the fan frequency; when the air volume is higher than the set value, PLC controller 7 controls the frequency converter to decrease the fan frequency.

[0031] Simultaneously, the pressure difference across the nuclear-grade air filter is monitored in real time; when the pressure difference reaches twice the initial pressure difference, the PLC controller 7 issues an alarm signal. The alarm signal can be an audible and visual alarm or a remote notification signal.

[0032] The variable frequency fan of this system operates at a frequency lower than the power frequency, and the operating power of the fan is proportional to the cube of the frequency, thereby achieving energy saving.

[0033] Specifically, based on Bernoulli's constant total flow equation in fluid mechanics, the calculation formula for the relationship between the wind velocity v flowing through the pressure measuring orifice plate and the pressure difference ΔP across the orifice plate is as follows: ; Where: k --- flow coefficient, experimental calibration v --- Air velocity flowing through the orifice plate (m / s); ΔP --- Pressure difference across the orifice plate (Pa); ρ --- air density (kg / m³) 3 ).

[0034] By measuring the pressure difference across the pressure measuring orifice plate 5, the wind speed flowing through the orifice plate can be calculated in real time, and thus the air volume flowing through the orifice plate can be calculated in real time, achieving the purpose of real-time monitoring of the exhaust system's air volume. After calibration and molding, the pressure measuring orifice plate 5 is easy to process, low in cost, simple to install, and has no easily damaged parts, making it reliable and durable, further ensuring the reliability of the radioactive material filtration system.

[0035] While nuclear-grade air filters remove radioactive materials, their filtration performance continuously declines. The standard for determining substandard filtration performance is that when the air resistance reaches twice the initial resistance, the filtration performance no longer meets the requirements and timely replacement is necessary. Conventional nuclear-grade air filters come with differential pressure gauges, requiring operators to be on-site to observe whether the differential pressure reaches twice the initial pressure. This results in insufficient system automation and inadequate assurance of a healthy monitoring environment.

[0036] In use, the exhaust duct 3 containing radioactive material first passes through a nuclear-grade air filter 6, where the radioactive material is removed. The clean exhaust air then passes through a pressure measuring orifice plate 5 and is discharged outdoors by a variable frequency exhaust fan 1. Pressure sensors 4 at the front and rear of the nuclear-grade air filter 6 (i.e., the pressure sensor 4 at the front of the pressure measuring orifice plate 5) monitor the pressure values ​​at various points in real time and transmit these pressure values ​​to the PLC controller 7 via data transmission lines.

[0037] After the nuclear-grade air filter 6 filters out radioactive materials, the air resistance increases, leading to increased resistance in the exhaust system and reduced airflow. The PLC controller 7 calculates that the pressure difference across the pressure measuring orifice plate 5 at the rear of the nuclear-grade air filter 6 has decreased and deviated from the set value. The PLC controller 7 issues a command to control the frequency converter 8 to increase the frequency and increase the airflow of the variable frequency fan. When the PLC controller 7 calculates that the pressure difference across the pressure measuring orifice plate 5 has reached the set value, it stops sending the frequency increase command to maintain the system airflow at the set value, and vice versa.

[0038] After the nuclear-grade air filter 6 filters out radioactive materials, the air resistance increases, and the pressure difference between its two ends increases. When the PLC controller 7 calculates that this pressure difference value reaches twice its initial pressure difference setting value, the PLC controller issues an alarm signal to remind the staff to replace the nuclear-grade air filter element in time to ensure that the purification performance of the nuclear-grade air filter is always within the required range.

[0039] In actual operation, the system resistance of this exhaust filtration system will always be less than the resistance when the nuclear-grade air filter is replaced. The variable frequency fan always operates in a low-frequency mode lower than the power frequency. Since the operating power of the fan is proportional to the cube of the frequency, the actual operating power consumption of the system is lower than that of the conventional fixed-frequency exhaust system, and the system has extremely high energy efficiency.

[0040] This utility model includes a radioactive material exhaust filtration system that monitors the resistance changes of nuclear-grade air filters in real time, ensuring stable airflow during operation and that the purification performance of the nuclear-grade air filters remains within the required range. At the same time, the exhaust system always operates at a low frequency using a variable frequency fan, resulting in good energy efficiency.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A ventilation filtration system containing radioactive materials, characterized in that, The system includes a variable frequency exhaust fan, an exhaust duct, a nuclear-grade air filter, a pressure orifice plate, a regulating valve, multiple pressure sensors, a PLC controller, and a frequency converter. One end of the exhaust duct is connected to a room where radioactive materials are released, and the other end of the exhaust duct leads to the outside. The nuclear-grade air filter, the pressure orifice plate, the regulating valve, and the variable frequency exhaust fan are sequentially installed on the exhaust duct. The pressure sensors are respectively installed at the front end of the nuclear-grade air filter, the rear end of the nuclear-grade air filter, and the rear end of the pressure orifice plate. The PLC controller is connected to the pressure sensors and the frequency converter.

2. The exhaust filtration system according to claim 1, characterized in that, The number of pressure sensors is three, and the three pressure sensors are respectively disposed at the front end of the nuclear-grade air filter, the rear end of the nuclear-grade air filter (i.e., the front end of the pressure measuring orifice plate), and the rear end of the pressure measuring orifice plate.

3. The exhaust filtration system according to claim 1, characterized in that, The PLC controller is connected to each of the pressure sensors and the frequency converter via a data transmission line.

4. The exhaust filtration system according to claim 1, characterized in that, The pressure measuring plate is provided with pressure measuring holes for measuring the pressure difference on both sides of the plate.

5. The exhaust filtration system according to claim 1, characterized in that, The regulating valve is installed in the exhaust pipe, and the regulating valve is located between the nuclear-grade air filter and the variable frequency exhaust fan.

6. The exhaust filtration system according to claim 1, characterized in that, The frequency converter is electrically connected to the variable frequency exhaust fan and is used to adjust the fan speed.

7. The exhaust filtration system according to claim 1, characterized in that, The PLC controller has data storage and historical query functions.

8. The exhaust filtration system according to claim 1, characterized in that, The pressure measuring orifice plate is a standardized orifice plate, and its flow coefficient k has been calibrated by test.

9. The exhaust filtration system according to claim 1, characterized in that, The system is used in nuclear facilities or sites containing radioactive materials.

10. The exhaust filtration system according to claim 1, characterized in that, All pressure sensors are differential pressure sensors, used to monitor the pressure at various points in real time and transmit the data to the PLC controller.

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