Ⅲ级生物安全柜气流组织及控制策略研究
发布时间：2018-08-28 07:17
【摘要】：生物安全柜的主要功能是提供一个洁净的操作空间,它是微生物实验操作的重要洁净设备,对操作人员、试验环境和受试样本起隔离保护作用。三级生物安全柜提供一级,二级安全柜无法提供的绝对安全保障。所有三级生物安全柜都可在涉及一、二、三、四级生物安全水平的微生物因子实验中使用。尤其适用于产生致命因子的生物试验。但是目前三级生物安全柜在研发过程中还存在许多问题,笔者主要针对其中三个问题进行了研究。 1)三级生物安全柜是一个全密闭的负压空间,工作人员通过手套对实验样本进行操作。由于内部是负压,一旦手套脱落,外部空气瞬间就会进入内部。外面未经过滤的空气极易造成实验样本的污染。假设改变回风口格式能让流入空气在到达操作台之前全部流走,就能避免实验样品被污染。笔者首先对这一问题进行了fluent模拟,假设压力出口边界条件。模拟结果是这一假设不能实现,无论什么样的风口都会贯穿台面。由于fluent模拟该问题时存在边界条件设定的困难,假定的边界条件模拟得出的结果不能保证其正确性。笔者制造了一个三级生物安全柜的有机玻璃模型。手套脱落后在手套口处防烟雾并记录风速变化。得出结论：只通过改变回风口的方式在手套口脱落后避免样本被污染是行不通的。假设不能实现。 2)三级生物安全柜需要通过传递窗与外界传递物品,当传递窗打开时,操作区内部的压力会波动,如果内部压力长期处于波动状态,势必会对实验样本有影响。传递窗打开时,首先利用传统PID控制操作区内部压力,记录压力随时间变化情况。发现PID控制效果不佳。而后采用基于LABVIEW编程的虚拟仪器控制风机变频器的频率。在打开传递窗时改变风机频率,记录操作区内部压力随时间变化情况。实验发现采用采用LABVIEW勺虚拟控制器控制效果较好,反应速度较快。 3)孔板出流方式比格栅出流方式更适用于作为三级生物安全柜的垂直下降气流出口,但是小孔直径大小对气流组织的影响是未知的。本文利用CFD模拟对孔板回风时小孔孔径对气流组织的影响进行了研究。建立采用了不同孔径孔板回风口的三种模型。在气流速度分别为0.2m/s及0.5m/s的情况下,利用fluent模拟回风口孔径为5mm,7mm,10mm,13mmm,15mm时安全柜气流组织的情况。得到结论,在孔径为5mm时,操作区上下部分气流流速分割现象,气流流速不均匀,气流组织最差。综合比较而言,采用10mm或者13mm的回风口孔径气流组织较好。
[Abstract]:The main function of biosafety cabinet is to provide a clean operating space. It is an important cleaning equipment for microorganism experimental operation. Level 3 Biosafety cabinets provide one-level, two-level safety cabinets can not provide absolute security. All three-level biosafety cabinets can be used in microbiological factor tests involving level 1, 2, 3, and 4-4 biosafety. It is especially suitable for biological tests that produce lethal factors. However, there are still many problems in the research and development of three-stage biosafety cabinets. The author has mainly studied three of them. 1) the three-stage biosafety cabinet is a fully closed negative pressure space. The workers operated on the experimental samples with gloves. Because the inside is negative pressure, once the gloves fall off, the external air will enter the inside instantly. Outside unfiltered air is highly susceptible to contamination of experimental samples. It is assumed that a change in the orifice format would allow the incoming air to flow away before reaching the operating table, thus avoiding contamination of the experimental samples. At first, the author simulates this problem by fluent, and assumes the pressure outlet boundary condition. The simulation result is that this assumption cannot be realized, no matter what kind of tuyere will run through the Mesa. Due to the difficulty of setting boundary conditions when fluent simulates the problem, the results obtained by the assumed boundary conditions cannot guarantee its correctness. An organic glass model of a three-stage biosafety cabinet was made. After the glove falls off, prevent smoke at the glove mouth and record the change of wind speed. It is concluded that it is not feasible to avoid sample contamination by changing the tuyere only after the glove mouth falls off. Assuming that it cannot be realized. 2) the level III biosafety cabinet needs to deliver items to the outside world through the transfer window. When the transfer window is opened, the pressure inside the operating area will fluctuate, if the internal pressure is in a fluctuating state for a long time, It is bound to have an effect on the experimental sample. When the transfer window is opened, the traditional PID is first used to control the internal pressure of the operating area and record the pressure variation with time. It was found that the control effect of PID was not good. Then the frequency of fan frequency converter is controlled by virtual instrument based on LABVIEW programming. Change the fan frequency when opening the transfer window and record the internal pressure of the operating area with time. It is found that the virtual controller with LABVIEW scoop has better control effect and faster reaction speed. 3) the orifice outlet is more suitable than the grid outlet for the vertical downdraft outlet of the three-stage biosafety tank. However, the influence of pore diameter on airflow is unknown. In this paper, CFD simulation was used to study the effect of orifice aperture on airflow distribution. Three models with different orifice orifices were established. When the airflow velocity is 0.2m/s and 0.5m/s respectively, the airflow organization of the safety tank is simulated by fluent when the orifice aperture is 5 mm / 7 mm / 10 mm ~ 13 mm / m ~ (15 mm). It is concluded that when the aperture is 5mm, the upper and lower parts of the operating area are separated, the flow velocity is uneven and the airflow organization is the worst. In general, the air distribution of the orifice with 10mm or 13mm is better.
【学位授予单位】：东华大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU834
本文编号：2208682
[Abstract]:The main function of biosafety cabinet is to provide a clean operating space. It is an important cleaning equipment for microorganism experimental operation. Level 3 Biosafety cabinets provide one-level, two-level safety cabinets can not provide absolute security. All three-level biosafety cabinets can be used in microbiological factor tests involving level 1, 2, 3, and 4-4 biosafety. It is especially suitable for biological tests that produce lethal factors. However, there are still many problems in the research and development of three-stage biosafety cabinets. The author has mainly studied three of them. 1) the three-stage biosafety cabinet is a fully closed negative pressure space. The workers operated on the experimental samples with gloves. Because the inside is negative pressure, once the gloves fall off, the external air will enter the inside instantly. Outside unfiltered air is highly susceptible to contamination of experimental samples. It is assumed that a change in the orifice format would allow the incoming air to flow away before reaching the operating table, thus avoiding contamination of the experimental samples. At first, the author simulates this problem by fluent, and assumes the pressure outlet boundary condition. The simulation result is that this assumption cannot be realized, no matter what kind of tuyere will run through the Mesa. Due to the difficulty of setting boundary conditions when fluent simulates the problem, the results obtained by the assumed boundary conditions cannot guarantee its correctness. An organic glass model of a three-stage biosafety cabinet was made. After the glove falls off, prevent smoke at the glove mouth and record the change of wind speed. It is concluded that it is not feasible to avoid sample contamination by changing the tuyere only after the glove mouth falls off. Assuming that it cannot be realized. 2) the level III biosafety cabinet needs to deliver items to the outside world through the transfer window. When the transfer window is opened, the pressure inside the operating area will fluctuate, if the internal pressure is in a fluctuating state for a long time, It is bound to have an effect on the experimental sample. When the transfer window is opened, the traditional PID is first used to control the internal pressure of the operating area and record the pressure variation with time. It was found that the control effect of PID was not good. Then the frequency of fan frequency converter is controlled by virtual instrument based on LABVIEW programming. Change the fan frequency when opening the transfer window and record the internal pressure of the operating area with time. It is found that the virtual controller with LABVIEW scoop has better control effect and faster reaction speed. 3) the orifice outlet is more suitable than the grid outlet for the vertical downdraft outlet of the three-stage biosafety tank. However, the influence of pore diameter on airflow is unknown. In this paper, CFD simulation was used to study the effect of orifice aperture on airflow distribution. Three models with different orifice orifices were established. When the airflow velocity is 0.2m/s and 0.5m/s respectively, the airflow organization of the safety tank is simulated by fluent when the orifice aperture is 5 mm / 7 mm / 10 mm ~ 13 mm / m ~ (15 mm). It is concluded that when the aperture is 5mm, the upper and lower parts of the operating area are separated, the flow velocity is uneven and the airflow organization is the worst. In general, the air distribution of the orifice with 10mm or 13mm is better.
【学位授予单位】：东华大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU834
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