Transmitting and discharging control method and system for laboratory fume hood

Abstract

The invention discloses a laboratory fume hood transmitting and discharging control method and system, and the method comprises the steps: controlling a door plate of a single fume hood to drive a displacement sensor to act, obtaining the face velocity of the fume hood during the operation in a laboratory, and calculating the ventilation area generated by pulling the displacement sensor; the air volume is calculated on the basis of the face air speed in combination with the ventilation area, and the air outlet volume is automatically adjusted through an exhaust valve with a rapid actuator on the ventilation cabinet; when the ventilation cabinets in the laboratory are used, the air supply amount of the air supply VAV valve of the laboratory is increased according to the additional exhaust air amount generated by the operation of a plurality of ventilation cabinets, and the variable transmission and variable exhaust control is carried out. The opening degree of the rapid exhaust valve is calculated and controlled through the displacement sensor of the ventilation cabinet, the face velocity stability is ensured, and the safety of experimenters is ensured; the opening degree of the air supply VAV valve is calculated through feedback of multiple ventilation cabinet exhaust valves, and it is guaranteed that the negative pressure of the laboratory environment is rapidly responded and stable.

Description

Technical Field

[0001] The present invention relates to the technical field of laboratory fume hoods, and in particular to a transmission and exhaust control method and system for laboratory fume hoods. Background Art

[0002] VAV is the abbreviation of Variable Air Volume (variable air volume control technology). The VAV control system can support multiple fume hoods to share one fan. The central control system adjusts the fan speed to achieve the purpose of adjusting the total exhaust volume. It is suitable for multiple fume hoods in the laboratory. The biggest function of the laboratory fume hood is to exhaust the harmful gases generated during the experiment and protect the health of the experimenters. To achieve this goal, it is necessary to ensure a certain suction speed at the opening of the fume hood, which is what we usually call the surface wind speed. The main factors that determine the surface wind speed of the fume hood are: the content of the experiment and the nature of the harmful substances.

[0003] When multiple fume hoods frequently change their working conditions, it is also necessary to ensure the negative pressure environment of the room to ensure the safety of laboratory personnel. Currently, the room pressure difference is controlled.

[0004] A variable air volume valve is installed on the air supply of the air conditioning system to control the air supply volume. The exhaust volume required to ensure the surface wind speed is calculated through the displacement distance of the displacement sensor on the fume hood. The required air supply volume is quickly calculated through the feedback opening of the fast air valve actuator installed in the air outlet duct of the fume hood and transmitted to the air supply variable air volume valve to achieve a rapid response to the negative pressure environment of the laboratory room, thereby ensuring the environmental safety during the use of multiple fume hoods.

[0005] Traditional control schemes use direct pressure difference control and residual air volume control to control the room and the atmosphere under negative pressure. This method often has a long response time when more than a dozen or even twenty or thirty fume hoods are working at the same time, and is prone to large fluctuations in room pressure difference, which cannot guarantee the health of experimenters. Summary of the invention

[0006] The purpose of the present invention is to provide a laboratory fume hood transmission and exhaust control method and system to solve one or more technical problems existing in the prior art and at least provide a beneficial choice or create conditions.

[0007] The present invention adopts the following technical solutions to achieve the above-mentioned invention object:

[0008] The present invention provides a laboratory fume hood transmission and exhaust control method, comprising:

[0009] Control the door panel of a single fume hood to drive the displacement sensor to move, obtain the surface wind speed of the fume hood when it is operated in the laboratory, and calculate the ventilation area generated by pulling the displacement sensor;

[0010] The air volume is calculated based on the surface wind speed combined with the ventilation area, and the air volume is automatically adjusted by the exhaust valve with a fast actuator on the fume hood through pid;

[0011] According to the additional exhaust volume generated by the operation of multiple fume hoods in the laboratory, the air supply volume of the laboratory air supply VAV valve is increased to control the air supply and exhaust.

[0012] Furthermore, the formula for calculating the ventilation area S1 generated by pulling the displacement sensor is as follows, including:

[0013] S1=L1*H1

[0014] Where: H1 is the displacement length of the displacement sensor; L1 is the door panel width; S1 is the ventilation area.

[0015] Furthermore, the face velocity of the fume hood when it is operated in the laboratory is obtained, and the air volume is calculated in combination with the ventilation area as follows:

[0016] Q1=S1*U1*3600

[0017] Where: U1 is the face wind speed of the fume hood when it is operated in the laboratory; S1 is the ventilation area; Q1 is the air volume.

[0018] Furthermore, the face velocity of the fume hood during laboratory operation reaches 0.5 m / s.

[0019] Furthermore, the additional exhaust volume generated by the operation of multiple fume hoods is used to increase the air supply volume of the laboratory air supply VAV valve, and control the air supply and exhaust, including:

[0020] Multiple fume hoods have glass doors and windows on the door panels to generate additional exhaust volume, which increases the exhaust valve opening and increases the total exhaust volume in the laboratory.

[0021] By feedback on the opening of exhaust valves in multiple fume hoods, the required exhaust volume is calculated to change the frequency of the exhaust fan. At the same time, the opening of the air supply VAV valve and the frequency of the air supply fan are increased according to the total exhaust volume.

[0022] The room pressure difference in the laboratory is controlled to be within the set -5PA environment to achieve transmission and exhaust control.

[0023] Furthermore, by feedbacking the opening of the exhaust valves in multiple fume hoods, the required exhaust volume is calculated to change the frequency of the exhaust fan. At the same time, the total exhaust volume is used to increase the opening of the air supply VAV valve and the frequency of the air supply fan. The formula is as follows:

[0024] Fs=Fh+Fx+Ff

[0025] Q1+Q2+···+Qn=ΔFf

[0026] Where: ΔFf is the total exhaust volume that changes when multiple fume hoods are used, the supply air volume required by the air conditioner is Fs, the exhaust air volume is Ff, the return air volume is Fh, and the fresh air volume is Fx;

[0027] When the total exhaust volume of the fume hood changes during use is ΔFf, the pressure in the room is kept constant by correspondingly increasing the total air supply volume, and the increase in air supply volume is ΔFs, at which time ΔFs = ΔFf;

[0028] The exhaust fan frequency conversion uses PID calculation to take the set value corresponding to ΔFf+Ff as the new target value for frequency conversion adjustment;

[0029] When the air supply volume increases to ΔFs during the use of the fume hood, the demand valve opening of the air supply VAV valve is calculated by the obtained Fs to give valve control at 0-100%;

[0030] The fan frequency conversion is PID-calculated, and the set value of ΔFs+Fs is used as the new target value to adjust the fan frequency conversion;

[0031] The air supply VAV valve and the air supply fan frequency converter operate simultaneously.

[0032] The present invention provides a laboratory fume hood transmission and exhaust control system, comprising:

[0033] The first calculation unit is used to control the door panel of a single fume hood to drive the displacement sensor to move, obtain the surface wind speed of the fume hood when it is operated in the laboratory, and calculate the ventilation area generated by pulling the displacement sensor;

[0034] The second calculation unit is used to calculate the air volume based on the surface wind speed combined with the ventilation area. The air volume is automatically adjusted by the exhaust valve with a fast actuator on the fume hood through pid;

[0035] The control unit is used to increase the air supply volume of the laboratory air supply VAV valve and perform variable air supply and exhaust control according to the additional exhaust volume generated by the operation of multiple fume hoods when the fume hoods in the laboratory are in use.

[0036] The beneficial effects of the present invention are as follows:

[0037] The invention calculates and controls the opening of the rapid exhaust valve through the displacement sensor of the fume hood, thereby ensuring the stability of the surface wind speed and ensuring the safety of the experimenters; and calculates the opening of the air supply VAV valve through the feedback of the exhaust valves of multiple fume hoods, thereby ensuring that the negative pressure of the laboratory environment responds quickly and is stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1A flowchart of a laboratory fume hood transmission and exhaust control method provided according to an embodiment of the present invention;

[0039] Figure 2 A diagram showing the architecture of a laboratory VAV ventilation system according to an embodiment of the present invention;

[0040] Figure 3 A plan view of multiple fume hoods in a laboratory provided according to an embodiment of the present invention;

[0041] Figure 4 A logic control diagram of a fume hood displacement sensor, an exhaust valve, and an air supply VAV valve provided according to an embodiment of the present invention;

[0042] Figure 5 A schematic diagram of a laboratory negative pressure environment provided according to an embodiment of the present invention;

[0043] Figure 6 Schematic diagram of the plane air volume trend of the laboratory provided according to an embodiment of the present invention Figure 1 ;

[0044] Figure 7 Schematic diagram of the plane air volume trend of the laboratory provided according to an embodiment of the present invention Figure 2 . DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with specific examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention.

[0046] Example 1

[0047] With the continuous development of science and technology, scientific experiments as technical theories are becoming more and more popular and improved, and the concept of scientific and safe experiments has also begun to gain popularity. People's awareness of experimental safety is constantly increasing, and the requirements for fume hoods are also constantly increasing. Whether it is a professional scientific researcher or a student entering a science school, the laboratory is not a strange place. However, some harmful gases may appear during the experiment. How to protect the experimenters in our laboratory from being harmed by these harmful gases has always been the primary issue for our fume hood researchers. The fundamental principle is to control the wind speed, thereby controlling the pollution collection and emission of the air. And put forward some design optimization suggestions.

[0048] The cost of our laboratory's air conditioning system is generally 3-6 times that of an ordinary building air conditioning system. Its operating costs are also relatively high. At present, in order to ensure that the harmful gases in the experiment can be completely collected and reasonably discharged, we generally use a fresh air system, but its cost and use are very high in the past. The variable air volume exhaust system is an effective way for us to reduce the cost and use costs of the air conditioning system. In the past, the exhaust volume of the exhaust cabinet in the fixed air volume air conditioning system was quantitative, and its operating consumption was also quantitative. Generally, its air volume was uniformly set as the exhaust volume. The change in the size of its sliding door does not change the size of its exhaust volume. The variable air volume exhaust system can change the hood wind speed according to the change of its sliding door. For example, if its minimum wind speed is 0.5m / s, then when the sliding door is opened a quarter, its hood wind speed increases to 2m / s, and when the entire sliding door is fully opened, its hood wind speed can immediately increase to 10m / s. However, too high a hood wind speed may cause a drastic change in the airflow above our test bench, and then it may still cause polluted gases to gather in a certain place in the cabinet, and may also blow out our experimental flame, destroying the effect of the experiment. However, if the hood wind speed is not enough, the polluted gas cannot be eliminated even if it is removed, and it will cause our experimenters to inhale harmful gases. Therefore, our exhaust system must be adjusted according to the specific experiment on the test bench, considering the actual experimental conditions of the test bench, indoor pressure and other conditions. Changing the hood wind speed with the size of the wind cabinet sliding door and keeping it within a certain range can greatly reduce the energy consumption of our laboratory exhaust system. The variable air volume exhaust system can save about 20% energy compared to the quantitative exhaust system. For example, a laboratory that needs to change air at 6 to 60 ACH can save a lot of energy if a variable air volume ventilation system is used. Therefore, our modern laboratories should generally adopt variable air volume exhaust systems.

[0049] The pulling distance of the displacement sensor on the fume hood is transmitted to the opening of the exhaust fast air valve actuator. After the opening of multiple air valve actuators is fed back through the algorithm, the corresponding air supply volume is calculated to achieve the stability of the absolute pressure difference in the room.

[0050] Reference Figure 1-Figure 7 The present invention provides a laboratory fume hood transmission and exhaust control method, comprising:

[0051] Step S1: When the air conditioning system in the experimental area operates normally and automatically, the exhaust valve feedback opening value VF1 of the minimum exhaust volume of the fume hood is recorded.

[0052] Step S2: Push the door panel of a single fume hood to drive the displacement sensor to move. The displacement length of the displacement sensor is H1, and the width of the door panel is L1. Calculate the ventilation area S1 generated by pulling the displacement sensor.

[0053] Step S3: Since the fume hood needs to meet the surface wind speed U1 of 0.5m / s when operating in the laboratory, the air volume Q1 can be calculated by the formula Q1=S1*U1*3600, and the formula is as follows:

[0054] Q1=S1*U1*3600

[0055] Where: U1 is the surface wind speed of the fume hood when it is operated in the laboratory; S1 is the ventilation area; Q1 is the air volume. The Q1 air volume is automatically adjusted by the exhaust valve with a fast actuator on the fume hood. The exhaust valve body is a CAV valve body with a fast actuator installed to achieve fast response. The exhaust valve has a comparison table of air volume linear corresponding to the opening. This linearity has been split into a formula for 0-100% valve opening corresponding to the minimum air volume to the maximum air volume based on the data provided by the manufacturer. When the fume hood is used, the displacement sensor is driven to act, and the exhaust volume of a single fume hood is calculated to be Q1. The air volume of Q1 corresponds to the valve opening of 0-100% for adjustment.

[0056] Step S4: According to the additional exhaust volume Q1-Qn generated by the operation of multiple fume hoods in the laboratory under normal use, the air supply volume of the laboratory air supply VAV valve is increased to achieve the effect of variable transmission and variable exhaust.

[0057] Step S5: Under normal use of fume hoods in the laboratory, multiple fume hoods generate additional exhaust volume by pulling glass doors and windows on the door panels, causing the exhaust valve opening to increase, thereby increasing the total exhaust volume in the laboratory, and the frequency control of the exhaust fan needs to be adjusted.

[0058] Step S6: By using the feedback values ​​of the openings of the exhaust valves in the multiple fume hoods, the required exhaust volume is calculated and the frequency of the exhaust fan is changed.

[0059] The formula is as follows:

[0060] The air supply volume required by the air conditioner is Fs, the exhaust volume is Ff, the return air volume is Fh, and the fresh air volume is Fx

[0061] Fs=Fh+Fx+Ff(without considering the leakage air volume)

[0062] Combining the above, the exhaust volume changes when multiple fume hoods are used

[0063] Q1+Q2+···+Qn=ΔFf

[0064] When the fume hood is in use, the total exhaust volume changes to ΔFf, and the corresponding increase in the total supply volume to maintain a constant pressure in the room is ΔFs

[0065] ΔFs=ΔFf

[0066] The frequency conversion of the exhaust fan is carried out through PID calculation. The original frequency conversion of the exhaust fan uses the exhaust volume as the set value to adjust the frequency. The set value of ΔFf+Ff is used as the new target value for frequency conversion adjustment.

[0067] At the same time, through the total exhaust volume, increase the opening of the air supply VAV valve, and the frequency of the air supply fan, ensure that the room pressure difference in the laboratory is controlled within the set -5PA environment, and start the effect of variable transmission and variable exhaust, including:

[0068] The air supply VAV valve has a comparison table of air volume linear corresponding to the opening. This linear has been split into a formula of 0-100% valve opening corresponding to the minimum air volume to the maximum air volume based on the data provided by the manufacturer.

[0069] When ΔFs is increased during the use of the cabinet, the final Fs is used to calculate the demand valve opening of the air supply VAV valve 0-100% to give valve control.

[0070] The fan frequency conversion is through PID calculation. The fan frequency conversion uses the air volume as the set value to adjust the frequency. The ΔFs+Fs set value is used as the new target value for frequency conversion adjustment.

[0071] The air supply VAV valve and the air supply fan frequency converter operate simultaneously.

[0072] Step S7: The laboratory air conditioning automatic control system must always meet the experimental tu The process requirement of the indoor and outdoor atmospheric pressure difference is -5PA. When multiple experimenters operate the fume hood at the same time, a large total exhaust volume fluctuation will occur. The exhaust valve needs to have a fast response function, and the air supply VAV valve and the supply fan and exhaust fan frequency need to change in real time to achieve the stability of the room pressure difference in the laboratory.

[0073] Example 2

[0074] The present invention provides a laboratory fume hood transmission and exhaust control system, comprising:

[0075] The first calculation unit is used to control the door panel of a single fume hood to drive the displacement sensor to move, obtain the surface wind speed of the fume hood when it is operated in the laboratory, and calculate the ventilation area generated by pulling the displacement sensor;

[0076] The second calculation unit is used to calculate the air volume based on the surface wind speed combined with the ventilation area. The air volume is automatically adjusted by the exhaust valve with a fast actuator on the fume hood through pid;

[0077] The control unit is used to increase the air supply volume of the laboratory air supply VAV valve and perform variable air supply and exhaust control according to the additional exhaust volume generated by the operation of multiple fume hoods when the fume hoods in the laboratory are in use.

[0078] In summary, the technical effects of the present invention are:

[0079] 1. The air volume can be automatically adjusted according to the height of the fume hood door to ensure constant surface wind speed;

[0080] 2. Energy saving and emission reduction: Through intelligent air volume adjustment, the variable air volume control system of the fume hood can adjust the air volume according to the actual needs of the laboratory, reduce energy waste and reduce operating costs;

[0081] 3. Safety assurance: The system uses high-precision sensors and intelligent controllers to monitor the internal environment of the fume hood in real time, ensuring rapid response when harmful gases are released to ensure personnel safety;

[0082] 4. Improved flexibility: The variable air volume control system makes the air volume adjustment of the fume hood more flexible, adapting to the needs of different experiments and improving the efficiency and reliability of experimental operations;

[0083] 5. Intelligent management: The system can automatically record and analyze the usage data of the fume hood, realize intelligent management, and facilitate decision-making for laboratory managers.

[0084] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0085] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0086] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0087] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0088] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A laboratory fume hood transmission and exhaust control method, characterized in that: include: Control the door panel of a single fume hood to drive the displacement sensor to move, obtain the surface wind speed of the fume hood when it is operated in the laboratory, and calculate the ventilation area generated by pulling the displacement sensor; The air volume is calculated based on the surface wind speed combined with the ventilation area, and the air volume is automatically adjusted by the exhaust valve with a fast actuator on the fume hood through pid; According to the additional exhaust volume generated by the operation of multiple fume hoods in the laboratory, the air supply volume of the laboratory air supply VAV valve is increased to control the air supply and exhaust.

2. A laboratory fume hood transmission and exhaust control method according to claim 1, characterized in that: The formula for calculating the ventilation area generated by pulling the displacement sensor is as follows, including: S1=L1*H1 Where: H1 is the displacement length of the displacement sensor; L1 is the door panel width; S1 is the ventilation area.

3. A laboratory fume hood transmission and exhaust control method according to claim 2, characterized in that: The face wind speed of the fume hood when operating in the laboratory reaches 0.5m / s.

4. A laboratory fume hood transmission and exhaust control method according to claim 3, characterized in that: The formula for obtaining the face velocity of the fume hood when it is operating in the laboratory and calculating the air volume in combination with the ventilation area is as follows: Q1=S1*U1*3600 Where: U1 is the face wind speed of the fume hood when it is operated in the laboratory; S1 is the ventilation area; Q1 is the air volume.

5. A laboratory fume hood transmission and exhaust control method according to claim 4, characterized in that: The additional exhaust volume generated by the operation of multiple fume hoods is used to increase the air supply volume of the laboratory air supply VAV valve and perform variable air supply and exhaust control, including: Multiple fume hoods have glass doors and windows on the door panels to generate additional exhaust volume, which increases the exhaust valve opening and increases the total exhaust volume in the laboratory. By feedback on the opening of exhaust valves in multiple fume hoods, the required exhaust volume is calculated to change the frequency of the exhaust fan. At the same time, the opening of the air supply VAV valve and the frequency of the air supply fan are increased according to the total exhaust volume. The room pressure difference in the laboratory is controlled to be within the set -5PA environment to achieve transmission and exhaust control.

6. A laboratory fume hood transmission and exhaust control method according to claim 5, characterized in that: By feedbacking the opening of the exhaust valves in multiple fume hoods, the required exhaust volume is calculated to change the frequency of the exhaust fan. At the same time, the total exhaust volume is used to increase the opening of the air supply VAV valve and the frequency of the air supply fan. The formula is as follows: Fs=Fh+Fx+Ff Q1+Q2+···+Qn=ΔFf Where: ΔFf is the total exhaust volume that changes when multiple fume hoods are used, the supply air volume required by the air conditioner is Fs, the exhaust air volume is Ff, the return air volume is Fh, and the fresh air volume is Fx; When the total exhaust volume of the fume hood changes during use is ΔFf, the pressure in the room is kept constant by correspondingly increasing the total air supply volume, and the increase in air supply volume is ΔFs, at which time ΔFs = ΔFf; The exhaust fan frequency conversion uses PID calculation to take the set value corresponding to ΔFf+Ff as the new target value for frequency conversion adjustment; When the air supply volume increases to ΔFs during the use of the fume hood, the demand valve opening of the air supply VAV valve is calculated by the obtained Fs to give valve control at 0-100%; The fan frequency conversion is PID-calculated, and the set value of ΔFs+Fs is used as the new target value to adjust the fan frequency conversion; The air supply VAV valve and the air supply fan frequency converter operate simultaneously.

7. A laboratory fume hood transmission and exhaust control system, characterized in that: include: The first calculation unit is used to control the door panel of a single fume hood to drive the displacement sensor to move, obtain the surface wind speed of the fume hood when it is operated in the laboratory, and calculate the ventilation area generated by pulling the displacement sensor; The second calculation unit is used to calculate the air volume based on the surface wind speed combined with the ventilation area. The air volume is automatically adjusted by the exhaust valve with a fast actuator on the fume hood through pid; The control unit is used to increase the air supply volume of the laboratory air supply VAV valve and perform variable air supply and exhaust control according to the additional exhaust volume generated by the operation of multiple fume hoods when the fume hoods in the laboratory are in use.

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