Precise differential pressure control system and method for clean areas in pharmaceutical manufacturing workshops

Abstract

This invention discloses a precise differential pressure control system and method for clean areas in pharmaceutical production workshops, including a supply fan, an exhaust fan, a return air volume detection device, an air volume control valve, a differential pressure gauge, a gas flow meter, an angle sensor, and a monitoring module. The monitoring module stores a preset pressure range and a preset adjustment time for each clean area. When the monitoring module detects that the actual pressure value of the clean area is outside the preset pressure range, it generates a corresponding control command based on the magnitude of the deviation and the preset adjustment time. The control module receives the control command and adjusts the speed of the exhaust fan and the opening of the air volume control valve accordingly. This invention achieves intelligent adjustment of clean room pressure by controlling the air volume of the clean room through the monitoring module. Furthermore, the monitoring module can intelligently adjust the speed of the exhaust fan according to the actual pressure, thereby achieving rapid adjustment of the negative pressure clean room pressure.

Description

Technical Field

[0001] This invention relates to the field of cleanroom differential pressure control technology, and particularly to a precise control system and method for differential pressure in cleanrooms of pharmaceutical production workshops. Background Technology

[0002] A cleanroom is a specially designed room that removes pollutants such as microparticles, harmful gases, and bacteria from the air within a certain space, and controls the indoor temperature, humidity, cleanliness, pressure difference, air volume, airflow speed and distribution, noise, vibration, illuminance, and static electricity within the relevant standard requirements.

[0003] Meeting the design requirements for pressure gradient is a mandatory indicator in pharmaceutical manufacturing workshops. Pressure gradient refers to the cleanliness levels of a pharmaceutical manufacturing workshop, categorized into four levels: A, B, C, and D. A includes B, B includes C, and C is separated from the outside. The airflow path is from A to B to C to D and then to the outside. Therefore, the room pressure within A, B, C, and D increases along a certain pressure gradient. In actual production, these specifications must be met before pharmaceutical manufacturing can proceed. Maintaining the pressure gradient between different cleanliness levels, and between different functions within the same area, is a crucial part of the BMS / EMS system.

[0004] Existing negative pressure cleanroom differential pressure control generally adopts a constant supply and variable exhaust method, that is, keeping the air volume supplied to the cleanroom constant and adjusting the cleanroom pressure by changing the cleanroom exhaust and return air volumes. Currently, valves are generally installed in the cleanroom exhaust ducts, and the exhaust volume is adjusted by regulating the valve opening. However, when the actual cleanroom pressure is much higher than the set pressure, valve adjustment alone cannot achieve rapid pressure recovery. Moreover, when the cleanroom door is opened, due to the pressure difference between cleanrooms, gas will flow between adjacent cleanrooms. When the door is closed, there will be a certain lag in adjusting the cleanroom pressure, which will inevitably increase the risk of gas flowing out of the cleanroom. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides a precise differential pressure control system and method for clean areas in pharmaceutical production workshops. This system solves the problem that existing technologies rely solely on valves, which cannot achieve rapid pressure regulation in cleanrooms and thus increase the risk of cross-contamination.

[0006] To achieve the above objectives, the technical solution of the precise differential pressure control system for the clean area of ​​a pharmaceutical production workshop according to the present invention includes:

[0007] A blower is provided, which is connected to each clean area via air supply ducts, and is used to deliver gas into each clean area.

[0008] An exhaust fan is connected to each clean area via exhaust ducts, and the exhaust fan is used to exhaust the gas in the clean area.

[0009] Return air volume detection device, used to detect the return air volume of cleanroom;

[0010] An air volume control valve is installed in each of the exhaust ducts, and the air volume passing through the exhaust duct is increased by increasing the opening of the air volume control valve;

[0011] Differential pressure gauges are installed in each clean area to detect the absolute pressure difference between the clean area and the external environment.

[0012] A gas flow meter is installed on the door between the exhaust duct and the adjacent clean area. The gas flow meter acquires and records the first gas flow velocity passing through the exhaust duct per unit time when the air volume control valve is at different opening degrees, and the second gas flow velocity passing through the door when the door is open.

[0013] An angle sensor is installed on the door, and the angle sensor is used to detect the opening angle of the door;

[0014] A monitoring module is connected to the exhaust fan, the differential pressure gauge, the gas flow meter, and the angle sensor. The monitoring module stores a preset pressure range and a preset adjustment time for each clean area. When the monitoring module detects that the actual pressure value of the clean area is outside the preset pressure range, it generates a corresponding control command based on the magnitude of the deviation and the preset adjustment time. When the door is opened, the monitoring module adjusts the first gas flow rate based on the second gas flow rate to reduce pressure fluctuations within the clean area. The monitoring module determines the required adjustment value of the first gas flow rate when the door is opened using a first formula: Where Q2 is the second gas flow rate, h is the height of the door, w is the width of the door, θ is the opening angle of the door, and s is the cross-sectional area of ​​the exhaust duct;

[0015] The control module receives the control command and adjusts the speed of the exhaust fan and the opening of the air volume control valve according to the control command to regulate the pressure in the clean area.

[0016] Further, the system includes at least clean zones A, B, C, and D; a constant pressure chamber located above each clean zone and corresponding to the differential pressure gauge; pressure stabilizing chambers W1-W4 located above clean zones A and D; an inflation chamber C1 located above pressure stabilizing chambers W1 and W2; and an inflation chamber C2 located above pressure stabilizing chambers W3 and W4. A first pressure gauge is installed in inflation chamber C1, and a second pressure gauge is installed in inflation chamber C2. Inflation chambers C1 and C2 are connected to the blower via a first valve and a second valve, respectively. Each clean zone is connected to the pressure stabilizing chamber... A lower differential pressure valve is provided between each pressure stabilizing chamber and the inflation chamber. An upper differential pressure valve is provided between each pressure stabilizing chamber and the inflation chamber. A pressure gauge is provided in the inflation chamber. The control module opens the first valve and the second valve in a pulse manner based on the pressure values ​​of the first pressure gauge and the second pressure gauge to maintain the pressure of the inflation chamber C1 and the inflation chamber C2 at P. The pressures of the pressure stabilizing chambers W1-W4 are the preset pressures P1-P4 of the clean area AD, respectively. The lower differential pressure valve is configured to open when the pressure of the clean area and the pressure of the corresponding pressure stabilizing chamber exceed a threshold. The upper differential pressure valve is configured to open when the pressure of the pressure stabilizing chamber and the pressure of the corresponding inflation chamber exceed a threshold.

[0017] Furthermore, the present invention also provides a method for precise control of differential pressure in the clean area of ​​a pharmaceutical production workshop. This method is based on the aforementioned control system and includes:

[0018] Step S1: Obtain the pressure relationship function V0 = f(P1 - P2), where V0 is the gas volume required for the cleanroom to reach the second pressure value P2 from the first pressure value P1.

[0019] Step S2: The monitoring module obtains the actual pressure value of the clean area and determines whether the actual pressure value is lower than the lower limit of the preset pressure range. If yes, the monitoring module calculates the gas volume required for the clean room to reach the lower limit of the preset pressure range from the actual pressure value based on the pressure relationship function, and reduces the opening of the air volume control valve according to the required gas volume and the preset adjustment time. If no, proceed to step S3.

[0020] Step S3: The monitoring module determines whether the actual pressure value is higher than the upper limit of the preset pressure value range. If so, the monitoring module calculates the gas volume required for the cleanroom to reach the upper limit of the preset pressure value range from the actual pressure value based on the pressure relationship function, and increases the opening of the air volume control valve and the speed of the exhaust fan according to the required gas volume and the preset adjustment time.

[0021] Further, step S2 includes: the monitoring module acquires the actual pressure value of each clean area, determines whether the actual pressure value is lower than the lower limit of the preset pressure range, when the actual pressure value is lower than the lower limit of the preset pressure range, the monitoring module calculates the gas volume required for the clean room to reach the lower limit of the preset pressure range from the actual pressure value based on the pressure relationship function, and simultaneously determines whether the gas in the corresponding pressure stabilizing chamber is greater than the required gas volume, when the gas in the pressure stabilizing chamber is greater than the required gas volume, the blower inflates the inflation chamber, when the gas in the pressure stabilizing chamber is not greater than the required gas volume, the opening of the air volume control valve is reduced according to the required gas volume, the difference between the pressure stabilizing chamber and the required volume, and the preset adjustment time, and when the actual pressure value is not lower than the lower limit of the preset pressure range, step S3 is executed.

[0022] Furthermore, in step S1, the pressure relationship function is determined based on the size of the clean area, the gas temperature, and the amount of gaseous substance.

[0023] Furthermore, in step S2, the air volume control valve is preset with a minimum opening degree, which is 15% of the total opening degree of the air volume control valve.

[0024] Further, in step S3, after the monitoring module obtains the gas volume required for the cleanroom to reach the upper limit of the preset pressure range from the actual pressure value, the monitoring module determines whether the required gas volume satisfies the second formula. If yes, the monitoring module adjusts the opening of the air volume control valve to the upper limit and increases the speed of the exhaust fan according to the required gas volume. If no, the monitoring module only increases the opening of the air volume control valve. The second formula is: |V0|>V2+V3-V1, where V1, V2, and V3 are the current air supply fan speed, the exhaust fan speed, and the air volume control valve at its maximum opening, respectively, within the preset adjustment time, the air supply volume of the air supply fan, the exhaust volume of the exhaust fan, and the return air volume of the cleanroom itself.

[0025] Further, in step S2, the monitoring module reduces the opening of the air volume control valve according to the required gas volume and the preset adjustment time, including the following steps:

[0026] Step S21: The monitoring module calculates the required first gas flow rate Q1 of the exhaust duct per unit time within the preset adjustment time using a third formula. The third formula is: Where Q0 is the first gas flow velocity in the exhaust duct, s is the cross-sectional area of ​​the exhaust duct, and t is the preset adjustment time;

[0027] Step S22: The monitoring module adjusts the opening of the air volume control valve based on the relationship between the first gas flow rate and the opening of the air volume control valve.

[0028] Furthermore, step S2 also includes: when the gas in the pressure stabilizing chamber is not greater than the required gas volume, the opening of the air volume control valve is reduced according to the required gas volume, the difference between the pressure stabilizing chamber and the required volume, and the preset adjustment time; at the same time, when the pressure of the clean room is close to the preset value, the speed of the exhaust fan is reduced again, so as to achieve pressure regulation of the clean room through the pressure stabilizing chamber.

[0029] Compared with the prior art, the beneficial effects of the present invention are at least as follows:

[0030] 1. This invention sets a preset pressure range within the monitoring module. When the actual pressure of the cleanroom is lower than the lower limit of the preset pressure range, the airflow from the exhaust duct is reduced by decreasing the opening of the airflow control valve, thereby increasing the cleanroom pressure. When the actual pressure of the cleanroom is higher than the upper limit of the preset pressure range, the airflow from the exhaust duct is increased by increasing the opening of the airflow control valve, thereby increasing the cleanroom pressure. Furthermore, when the actual pressure in the cleanroom is significantly higher than the preset pressure range, the exhaust fan speed is further increased by increasing the opening of the airflow control valve, thereby increasing the first gas velocity in the exhaust duct and thus increasing the exhaust volume of the cleanroom within a preset time. This invention uses a differential pressure gauge to detect the absolute pressure in the cleanroom and controls the airflow from the cleanroom through the monitoring module to achieve intelligent adjustment of the cleanroom pressure. In addition, the monitoring module can also intelligently adjust the exhaust fan speed according to the actual pressure, thereby achieving rapid adjustment of the negative pressure cleanroom pressure.

[0031] 2. Before a cleanroom is put into use, the air supply and exhaust ducts are configured according to the design operating pressure and the size of the gaps in the cleanroom doors and windows. This means that the cleanroom maintains pressure while continuously exchanging air. In the second formula, firstly through... The required reduction in the first gas velocity within the exhaust duct is calculated. Then, the required reduction in the first gas velocity is subtracted from the current first gas velocity to obtain the desired first gas velocity. It should be noted that the required gas volume derived from the pressure relationship has a positive and negative sign; that is, V0 is positive when the gas volume needs to be increased and negative when the gas volume needs to be decreased. Therefore, the second formula does not need to restrict the sign of V0. After calculating the required reduction in the first gas velocity using the second formula, since the monitoring module has recorded the correspondence between the first gas velocity within the exhaust duct and the opening of the air volume control valve, the monitoring module can directly adjust the air volume control valve, thereby achieving intelligent adjustment of the air volume control valve.

[0032] 3. Therefore, when the door is opened, the air volume control valve is adjusted synchronously to maintain a dynamic balance between the supply and exhaust air volume of the clean room. This reduces the pressure fluctuation of the clean room and improves the precision of the clean room pressure regulation.

[0033] 4. This invention can accurately determine the pressure difference in a cleanroom by working with a constant pressure chamber. In conjunction with the upper and lower differential pressure valves, pressure stabilizing chamber, air filling chamber, first and second valves, and control module, it can regulate the cleanroom pressure in real time, preventing the pressure difference from continuously expanding. Simultaneously, it replenishes the cleanroom with stabilizing gas from the pressure stabilizing chamber to maintain the cleanroom pressure. Furthermore, through the above steps, the exhaust fan can maintain a relatively constant speed, reducing significant fluctuations in fan speed and improving adjustment accuracy. Even when the pressure in the pressure stabilizing chamber is insufficient to compensate for the pressure in the cleanroom, the pressure can be maintained simultaneously through the cooperation of the pressure stabilizing chamber and the exhaust fan, improving the compensation speed. Moreover, when approaching the preset pressure of the cleanroom, the fan speed can be reduced, and pressure compensation can be performed again through the pressure stabilizing chamber, thereby improving the accuracy of the cleanroom pressure difference. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the overall structure of the differential pressure precision control system for the clean area of ​​a pharmaceutical production workshop according to the present invention;

[0035] Figure 2 This is a flowchart of the method for precise control of differential pressure in the clean area of ​​a pharmaceutical production workshop according to the present invention;

[0036] Figure 3 This is a schematic diagram of the cleanroom door of the present invention being opened;

[0037] Figure 4 This is a schematic diagram of the pressure stabilizing chamber and the air filling chamber of the present invention, as well as related structures in their vicinity.

[0038] In the diagram: 1. Supply fan; 2. Exhaust fan; 3. Air volume control valve; 4. Differential pressure gauge; 5. Gas flow meter; 6. Monitoring module; 7. Control module; 8. Angle sensor; 9. Door; 10. Constant pressure chamber; 11. First valve; 12. Second valve; 14. First pressure gauge; 15. Second pressure gauge; 16. Upper differential pressure valve; 17. Lower differential pressure valve. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0040] It is understood that the terms "first," "second," etc., used in this application may be used herein to describe various elements, but unless otherwise specified, these elements are not limited by these terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of this application, a first script may be referred to as a second script, and similarly, a second script may be referred to as a first script.

[0041] Example 1

[0042] like Figure 1 As shown, a precise differential pressure control system for a clean area in a pharmaceutical production workshop includes: a supply fan 1, connected to each clean area via supply ducts, for supplying gas into each clean area; an exhaust fan 2, connected to each clean area via exhaust ducts, for exhausting gas from the clean area; a return air volume detection device (not shown), for detecting the return air volume of the clean room; an air volume control valve 3, installed in each exhaust duct, for increasing the air volume through the exhaust duct by increasing the opening of the air volume control valve 3; specifically, the air volume control valve 3 is a butterfly valve or a venturi valve; a differential pressure gauge 4, installed in each clean area, for detecting the absolute pressure difference between the clean area and the external environment; and gas flow meters 5, installed in the exhaust ducts and door 9, for detecting the gas flow rate of each clean area. The system acquires and records the first gas velocity passing through the exhaust duct per unit time when the air volume control valve 3 is at different opening degrees, and the second gas velocity passing through the door 9 when the door 9 is open; an angle sensor 8 is installed on the door 9 to detect the opening angle of the door 9; a monitoring module 6 is connected to the exhaust fan 2, differential pressure gauge 4, gas flow meter 5 and angle sensor 8, and stores the preset pressure value range and preset adjustment time for each clean area. When the monitoring module 6 detects that the actual pressure value of the clean area is outside the preset pressure value range, the monitoring module 6 generates a corresponding control command based on the magnitude of the deviation and the preset adjustment time; a control module 7 receives the control command and adjusts the speed of the exhaust fan 2 and the opening degree of the air volume control valve 3 according to the control command to regulate the pressure in the clean area.

[0043] like Figure 3 As shown, in this embodiment, when door 9 is opened, monitoring module 6 adjusts the first gas flow rate based on the first gas flow rate to reduce pressure fluctuations within the clean area. Specifically, monitoring module 6 determines the required first gas flow rate for the exhaust duct when door 9 is open using a third formula, which is: Where Q2 is the second gas velocity, h is the height of door 9, w is the width of door 9, θ is the opening angle of door 9, and s is the cross-sectional area of ​​exhaust duct.

[0044] When cleanroom door 9 is opened, gas flows between adjacent cleanrooms due to the pressure difference between them. Adjusting the cleanroom pressure after door 9 is closed will result in a certain lag. Therefore, when door 9 is opened, the opening of the airflow control valve 3 is adjusted synchronously to maintain a dynamic balance between the cleanroom's supply and exhaust airflow. This reduces pressure fluctuations and improves the precision of cleanroom pressure regulation. Specifically, when door 9 is opened, the cosine theorem is applied... The distance between the upper side of the door 9 and the wall is calculated. This distance is multiplied by the height of the door 9 to obtain the gas passage area at the opening angle θ. Then, the air volume passing through the door 9 per unit time is calculated based on the second gas flow velocity through the door 9. Finally, the first gas flow velocity required by the exhaust duct is calculated based on the cross-sectional area of ​​the exhaust duct, thereby adjusting the opening of the air volume control valve 3.

[0045] In existing technologies, to ensure the pressure difference between cleanrooms, the pressure of adjacent rooms is usually used as a reference for adjustment. While this can guarantee the pressure difference between cleanrooms, it may cause the cleanroom pressure to be much higher than the reference pressure. When subsequent pressure difference imbalances occur and the cleanroom pressure needs to be increased, the actual pressure of the cleanroom may have exceeded the adjustment range of the control system. Therefore, by setting up a differential pressure gauge 4 to detect the absolute pressure difference between the cleanroom and the external environment, it is ensured that the cleanroom pressure will not exceed the adjustment range of the control system.

[0046] On the other hand, such as Figure 2 As shown, the present invention also provides a method for precise control of differential pressure in the clean area of ​​a pharmaceutical production workshop. This method utilizes the precise differential pressure control system for the clean area of ​​a pharmaceutical production workshop described above, and includes the following steps:

[0047] Step S1: Obtain the pressure relationship function V0 = f(P1 - P2), where V0 is the gas volume required for the cleanroom to reach the second pressure value P2 from the first pressure value P1.

[0048] Step S2: The monitoring module 6 obtains the actual pressure value of the clean area and determines whether the actual pressure value is lower than the lower limit of the preset pressure value range. If yes, the monitoring module 6 calculates the gas volume required for the clean room to reach the lower limit of the preset pressure value range from the actual pressure value based on the pressure relationship function, and reduces the opening of the air volume control valve 3 according to the required gas volume and the preset adjustment time. If no, step S3 is executed.

[0049] Step S3: The monitoring module 6 determines whether the actual pressure value is higher than the upper limit of the preset pressure value range. If so, the monitoring module 6 calculates the gas volume required for the clean room to reach the upper limit of the preset pressure value range from the actual pressure value based on the pressure relationship function, and increases the opening degree of the air volume control valve 3 and the speed of the exhaust fan 2 according to the required gas volume and the preset adjustment time.

[0050] This invention sets a preset pressure range within the monitoring module 6. When the actual pressure in the cleanroom is lower than the lower limit of the preset pressure range, the airflow from the exhaust duct is reduced by decreasing the opening of the airflow control valve 3, thereby increasing the cleanroom pressure. When the actual pressure in the cleanroom is higher than the upper limit of the preset pressure range, the airflow from the exhaust duct is increased by increasing the opening of the airflow control valve 3, thereby increasing the cleanroom pressure. Furthermore, when the actual pressure in the cleanroom is significantly higher than the preset pressure range, the speed of the exhaust fan 2 is further increased by increasing the opening of the airflow control valve 3, thereby increasing the first gas velocity in the exhaust duct and thus increasing the exhaust volume of the cleanroom within a preset time. This invention uses a differential pressure gauge 4 to detect the absolute pressure in the cleanroom and controls the airflow from the cleanroom through the monitoring module 6 to achieve intelligent adjustment of the cleanroom pressure. In addition, the monitoring module 6 can also intelligently adjust the speed of the exhaust fan 2 according to the actual pressure, thereby achieving rapid adjustment of the negative pressure cleanroom pressure.

[0051] In step S1, the pressure relationship function is determined based on the size of the clean area, the gas temperature, and the amount of gas. Since the relationship between gas mass and pressure within a fixed space can be derived from the Clapeyron equation, after knowing the size of the clean area, the temperature, and the difference between the first and second pressure values, the required gas mass to reach the second pressure value can be calculated based on the Clapeyron equation. Then, based on the required gas mass, the required gas flow rate can be calculated. The conversion between pressure and gas volume based on the Clapeyron equation is a common technique in this field and will not be elaborated here.

[0052] In this embodiment, in step S2, the air volume control valve 3 is preset with a minimum opening degree, which is 15% of the total opening degree of the air volume control valve 3. This setting ensures that the monitoring module 6 cannot completely close the exhaust duct, thus ensuring that the clean room has a certain degree of gas flow while increasing the pressure. On the other hand, when the opening of the air volume control valve 3 is too small, the risk of air volume control valve 3 being eroded will greatly increase. Therefore, by setting a minimum opening degree, the erosion of the air volume control valve 3 by the gas can be reduced.

[0053] In step S3, after the monitoring module 6 obtains the gas volume required for the cleanroom to reach the upper limit of the preset pressure range from the actual pressure value, the monitoring module 6 determines whether the required gas volume meets the second formula. If yes, the monitoring module 6 adjusts the opening of the air volume control valve 3 to the upper limit and increases the speed of the exhaust fan 2 according to the required gas volume. If no, the monitoring module 6 only increases the opening of the air volume control valve 3. The second formula is: |V0|>V2+V3-V1, where V1, V2, and V3 are the current speed of the supply fan 1, the speed of the exhaust fan 2, and the air volume control valve 3 at its maximum opening, within a preset adjustment time, respectively, the supply air volume of the supply fan 1, the exhaust air volume of the exhaust fan 2, and the return air volume of the cleanroom itself.

[0054] This formula determines whether the cleanroom pressure can be reduced to the preset pressure range using only the airflow control valve 3 within the preset adjustment time. When |V0| < V2 + V3 - V1, it indicates that at the current exhaust fan 2 speed, when the airflow control valve 3 is adjusted to its maximum opening, the exhaust volume of the exhaust duct within the preset time can reach the exhaust volume required to reduce the cleanroom pressure to the upper limit of the preset range. In this case, only the opening of the airflow control valve 3 needs to be adjusted to achieve rapid adjustment of the cleanroom pressure. When |V0| > V2 + V3 - V1, it indicates that at the current exhaust fan 2 speed, when the airflow control valve 3 is adjusted to its maximum opening, the exhaust volume of the exhaust duct within the preset time still cannot reach the exhaust volume required to reduce the cleanroom pressure to the upper limit of the preset range. In this case, even with the airflow control valve 3 adjusted to its maximum opening, the speed of the exhaust fan 2 needs to be increased to achieve rapid adjustment of the cleanroom pressure.

[0055] In step S2, the monitoring module 6 reduces the opening of the air volume control valve 3 according to the required gas volume and preset adjustment time, including the following steps:

[0056] Step S21: Monitoring module 6 calculates the required first gas flow rate Q1 in the exhaust duct per unit time within the preset adjustment time using the third formula. The third formula is: Where Q0 is the first gas flow rate in the current exhaust duct, and t is the preset adjustment time;

[0057] Step S22: Based on the relationship between the first gas flow rate and the opening degree of the air volume control valve 3, the monitoring module 6 adjusts the opening degree of the air volume control valve 3.

[0058] Before a cleanroom is put into use, the air supply and exhaust ducts are configured according to the design operating pressure and the size of the gaps in the cleanroom doors and windows. This means that the cleanroom maintains pressure while continuously exchanging air. In the second formula, firstly through... The required reduction in the first gas velocity within the exhaust duct is calculated. Then, the required reduction in the first gas velocity is subtracted from the current first gas velocity to obtain the required first gas velocity. It should be noted that the required gas volume derived from the pressure relationship has a positive and a negative sign. That is, V0 is positive when the gas volume needs to be increased and negative when the gas volume needs to be decreased. Therefore, the second formula does not need to restrict the sign of V0. After calculating the required reduction in the first gas velocity using the second formula, since the monitoring module 6 has recorded the correspondence between the first gas velocity within the exhaust duct and the opening of the air volume control valve 3, the monitoring module can directly adjust the air volume control valve 3, thereby achieving intelligent adjustment of the air volume control valve 3.

[0059] Example 2

[0060] While the aforementioned technical solution can quickly adjust the differential pressure—that is, a single exhaust fan 2 can achieve rapid adjustment—in actual adjustment, the external environmental pressure is not constant. In situations requiring high precision, even slight pressure changes can lead to differential pressure variations, reducing the accuracy of the adjustment. More seriously, for example, a significant change in differential pressure occurs the instant a door opens, and this change continues rapidly with the duration the door remains open. To maintain a stable differential pressure, the speed of the exhaust fan 2 typically needs to be changed relatively quickly. The instantaneous change in the exhaust fan 2's speed causes rapid pressure changes in both the supply and exhaust ducts, thus affecting the entire system. The stability of the system is impacted, and the sudden change in gas flow also reduces the measurement accuracy of gas flow meter 5. During the control process, since the opening and closing of air volume control valve 3 is not synchronized with the speed of exhaust fan 2, the adjustment accuracy of the entire system is reduced in situations such as when the door is open or other situations that cause large pressure difference changes. Especially when the door is open for a certain period of time, the pressure difference between the two clean rooms changes relatively large. When it is necessary to adjust the pressure difference of two or more clean rooms simultaneously and quickly, the control of exhaust fan 2, gas flow meter 5, and air volume control valve 3 becomes relatively complex, making it difficult to achieve high-precision adjustment of multiple clean rooms at the same time.

[0061] Therefore, as Figure 4As shown, the preferred technical solution includes, for example, at least clean areas A, B, C, and D; a constant pressure chamber 10 located above each clean area and corresponding to the differential pressure gauge 4; the constant pressure chamber 10 is a closed chamber, which can maximize the pressure stability of the constant pressure chamber 10, thereby enabling accurate measurement of the pressure difference in conjunction with the differential pressure gauge 4; and pressure stabilizing chambers W1-W4 located above clean areas A and D respectively. The setting of the pressure stabilizing chambers enables the pressure inside the pressure stabilizing chamber to be equal to or substantially equal to the pressure of the corresponding clean area. For example, pressure stabilizing chamber W1-W4... The pressure in pressure chambers W1 and W2 is P1, the pressure in pressure stabilizing chamber W2 and W2 is P2, the pressure in pressure stabilizing chamber W3 and W2 is P3, the pressure in pressure stabilizing chamber W4 and W4 is P4, there is an inflation chamber C1 located above pressure stabilizing chambers W1 and W2, and an inflation chamber C2 located above pressure stabilizing chambers W3 and W4. The pressure in inflation chamber C1 is greater than the pressure in pressure stabilizing chambers W1 and W2, and the pressure in inflation chamber C2 is greater than the pressure in pressure stabilizing chambers W3 and W4. A first pressure gauge 14 is installed in inflation chamber C1, and a second pressure gauge 15 is installed in inflation chamber C2.

[0062] By setting the first and second pressure gauges, the pressure in inflation chambers C1 and C2 can be kept basically constant. Since the pressure inside cleanrooms usually requires continuous air supply due to factors such as door opening or air leakage, this invention supplies air to inflation chambers C1 and C2 to maintain stable internal air pressure. Pressure stabilizing chambers C1 and C2 are connected to the blower 1 via the first valve 11 and the second valve 12, respectively. A differential pressure valve 17 is provided between each clean area and the pressure stabilizing chamber P, and a valve 17 is provided between each pressure stabilizing chamber P and the inflation chamber. There is an upper differential pressure valve 16, and a pressure gauge 14 is installed in the inflation chamber. The control module opens the first valve 11 and the second valve 12 in a pulse manner based on the pressure values ​​of the first pressure gauge 14 and the second pressure gauge 15 to maintain the pressure of the inflation chamber C1 and the inflation chamber. The pressures of the pressure stabilizing chambers W1-W4 are the preset pressures P1-P4 of the clean area AD, respectively. The lower differential pressure valve 17 is configured to open when the pressure of the clean area and the pressure of the corresponding pressure stabilizing chamber exceed a threshold. The upper differential pressure valve 16 is configured to open when the pressure of the pressure stabilizing chamber and the pressure of the corresponding inflation chamber exceed a threshold.

[0063] With the above settings, when the internal pressure decreases slightly, such as when a door is opened quickly or there is a slight air leak, if the pressure in a certain clean area AD decreases (e.g., clean area A), as the pressure in clean area A (or BD) decreases, the pressure difference between the pressure stabilizing chamber W1 and clean area A exceeds the opening pressure difference of the lower differential pressure valve 17. Furthermore, the lower differential pressure valve 17 is configured to sense when the pressure difference exceeds a predetermined value, which can be less than a preset pressure value. That is, it opens before the cleanroom pressure drops to the lower limit of the preset pressure range, thereby adjusting the clean area's precision as much as possible, thus avoiding the need to operate below the lower limit. When the preset pressure value range is at its lower limit, the speed of exhaust fan 2 is adjusted to maintain a more stable speed, improving the detection accuracy of various components and the adjustment accuracy. When there are large pressure changes, such as when a door is left open for an extended period, the pressure in the pressure stabilizing chamber alone is insufficient to meet the adjustment requirements, or to meet the requirements for rapid adjustment. In this case, as in the previous embodiment, the speed of exhaust fan 2 can be increased by changing its speed. However, the sudden change in speed reduces the adjustment accuracy. Therefore, when the pressure in the clean area approaches or reaches the lower limit of the preset pressure value range, the speed of exhaust fan 2 is reduced to its original speed, in conjunction with... Figure 1 The air supply duct simultaneously regulates the pressure in the air filling chambers C1 and C2 through the first and second valves. Specifically, the valves are opened only when the pressure stabilizing chamber cannot meet the differential pressure regulation requirements. Figure 1 The air supply duct shown supplies air to the clean area.

[0064] In this invention, considering that the pressure in clean areas A, B, C, and D gradually increases, and that the rate of change of pressure difference between clean areas A and D decreases sequentially under the same sealing and opening conditions, the pressure difference is compensated for more quickly by setting the pressure of inflation chamber C1 to be greater than that of inflation chamber C2. This allows for faster adjustment of the pressure difference between clean areas A and B through greater pressure. Furthermore, when inflating the inflation chambers, inflation chambers C1 and C2 are inflated using a pulse method. Within one pulse cycle, the pulse inflation time for inflation chamber C1 is longer, while the pulse inflation time for inflation chamber C2 is shorter. This further achieves pressure balance between inflation chambers C1 and C2, improves pressure regulation accuracy, and further reduces the possibility of excessive pressure difference leading to increased rotational speeds of the supply fan 1 and exhaust fan 2, thus improving regulation precision.

[0065] In step S2, the following steps are included: the monitoring module acquires the actual pressure value of each clean area, determines whether the actual pressure value is lower than the lower limit of the preset pressure range, and when the actual pressure value is lower than the lower limit of the preset pressure range, the monitoring module calculates the gas volume required for the clean room to reach the lower limit of the preset pressure range based on the pressure relationship function. Simultaneously, it determines whether the gas volume in the corresponding pressure stabilizing chamber is greater than the required gas volume. When the gas volume in the pressure stabilizing chamber is greater than the required gas volume, the exhaust fan does not adjust its speed, and the supply fan inflates the inflation chamber. When the gas volume in the pressure stabilizing chamber is not greater than the required gas volume, the exhaust fan does not adjust its speed, and the supply fan inflates the inflation chamber. When the required gas volume is reached, the opening of the air volume control valve is reduced based on the required gas volume, the difference between the pressure stabilizing chamber and the required volume, and the preset adjustment time. When the actual pressure value is not lower than the lower limit of the preset pressure value range, step S3 is executed. Further, when the gas in the pressure stabilizing chamber is not greater than the required gas volume, the opening of the air volume control valve is reduced based on the required gas volume, the difference between the pressure stabilizing chamber and the required volume, and the preset adjustment time. At the same time, when the pressure in the clean room is close to the preset value, the speed of the exhaust fan is reduced again, and the pressure in the clean room is regulated through the pressure stabilizing chamber.

[0066] The preferred embodiment of the present invention can accurately determine the pressure difference in the cleanroom by working with the constant pressure chamber. In conjunction with the upper and lower pressure differential valves, the pressure stabilizing chamber, the air filling chamber, the first and second valves, and the control module, the pressure in the cleanroom can be regulated in real time to prevent the pressure difference from continuously expanding. Simultaneously, the pressure in the cleanroom is replenished with stabilizing gas in the pressure stabilizing chamber to maintain the cleanroom pressure. Furthermore, through the above steps, the supply fan can maintain a relatively constant speed, reducing large fluctuations in the exhaust fan speed and improving regulation accuracy. Even when the pressure in the pressure stabilizing chamber is insufficient to compensate for the pressure in the cleanroom, the pressure can be maintained simultaneously through the cooperation of the pressure stabilizing chamber and the supply fan, improving the compensation speed. Moreover, when approaching the preset pressure of the clean area, the exhaust fan speed can be reduced, and pressure compensation is performed again through the pressure stabilizing chamber, thereby improving the accuracy of the pressure difference in the clean area.

[0067] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and RAMbus dynamic RAM (RDRAM), etc.

[0068] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0069] The above-described embodiments are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A precise differential pressure control system for the clean area of ​​a pharmaceutical production workshop, characterized in that, include: A blower is provided, which is connected to each clean area via air supply ducts, and is used to deliver gas into each clean area. An exhaust fan is connected to each clean area via exhaust ducts, and the exhaust fan is used to exhaust the gas in the clean area. Return air volume detection device, used to detect the return air volume of cleanroom; An air volume control valve is installed in each of the exhaust ducts, and the air volume passing through the exhaust duct is increased by increasing the opening of the air volume control valve; Differential pressure gauges are installed in each clean area to detect the absolute pressure difference between the clean area and the external environment. A gas flow meter is installed on the door between the exhaust duct and the adjacent clean area. The gas flow meter acquires and records the first gas flow velocity passing through the exhaust duct per unit time when the air volume control valve is at different opening degrees, and the second gas flow velocity passing through the door when the door is open. An angle sensor is installed on the door, and the angle sensor is used to detect the opening angle of the door; A monitoring module is connected to the exhaust fan, the differential pressure gauge, the gas flow meter, and the angle sensor. The monitoring module stores a preset pressure range and a preset adjustment time for each clean area. When the monitoring module detects that the actual pressure value of the clean area is outside the preset pressure range, it generates a corresponding control command based on the magnitude of the deviation and the preset adjustment time. When the door is opened, the monitoring module adjusts the first gas flow rate based on the second gas flow rate to reduce pressure fluctuations within the clean area. The monitoring module determines the required adjustment value of the first gas flow rate when the door is opened using a first formula: Where Q1 is the first gas flow rate, Q2 is the second gas flow rate, h is the height of the door, w is the width of the door, θ is the opening angle of the door, and s is the cross-sectional area of ​​the exhaust duct. The control module receives the control command and adjusts the speed of the exhaust fan and the opening of the air volume control valve according to the control command to regulate the pressure in the clean area. The cleanroom of the pharmaceutical production workshop includes at least cleanroom A, cleanroom B, cleanroom C, and cleanroom D, as well as pressure stabilizing chambers W1-W4 located above cleanrooms A and D, an inflation chamber C1 located above pressure stabilizing chambers W1 and W2, and an inflation chamber C2 located above pressure stabilizing chambers W3 and W4. A first pressure gauge is installed in inflation chamber C1, and a second pressure gauge is installed in inflation chamber C2. Inflation chambers C1 and C2 are connected to the blower through a first valve and a second valve, respectively. A lower differential pressure valve is installed between each cleanroom and a pressure stabilizing chamber, and an upper differential pressure valve is installed between each pressure stabilizing chamber and an inflation chamber. The control module opens the first and second valves in a pulse manner based on the pressure values ​​of the first and second pressure gauges to maintain the pressure of inflation chambers C1 and C2. The lower differential pressure valve is configured to open when the pressure difference between the cleanroom and the corresponding pressure stabilizing chamber exceeds a threshold, and the upper differential pressure valve is configured to open when the pressure difference between the pressure stabilizing chamber and the corresponding inflation chamber exceeds a threshold.

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