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Laboratory ventilation system engineering
Laboratory ventilation system engineering is to control the spread and harm of air pollution by means of ventilation dilution or ventilation exclusion, which is a kind of building environment control technology to realize the quality assurance of indoor and outdoor air environment. Ventilation system is to realize the function of ventilation, including air intake, exhaust, air supply pipe, fan, cooling and heating, filter, control system and other ancillary equipment including a set of devices. Mechanical ventilation is generally adopted in laboratory ventilation engineering, and ventilation power devices, comprehensive ventilation and local ventilation equipment, such as fume hood, atomic absorption hood, universal exhaust hood, etc., are mainly used to exhaust air. Hood: As an important safety equipment in the laboratory, fume hood can provide an effective way of local ventilation. Operating Environment: Carry OUT THE EXPERIMENTAL OPERATION OF inflammable, EXPLOSIVE and VOLATILE toxic and harmful substances, carry out the detection of unknown performance items, qualitative and quantitative experimental operations. Fume hood structure style: Three stage group table (on the cabinet, operating table, under the cabinet); Table type fume hood walk-in floor type fume hood. Type of fume hood: Steel fume hood, all steel fume hood, glass fiber reinforced plastic fume hood, PP fume hood. In order to make the exhaust air volume of each single equipment meet the design requirements, and ensure that each ventilation equipment does not affect the normal operation of other ventilation equipment when operating alone, ventilation frequency conversion system is used. Principle of frequency conversion system: When part of the fume hood is not used or fume hood electronic air valve Angle change, change of cylinder head wind ventilation rate, at the same time, the pressure difference of ventilation, head of change, the differential pressure sensor detects the duct pressure difference after the change, through the signal transmission to the frequency converter, through the inverter automatic adjustment, to control the speed of the fan motor, so as to achieve the goal of controlling exhaust air. Frequency conversion mode: Frequency conversion constant frequency conversion variable air volume air volume method of frequency conversion control mode control: by all air flow of ventilation system design, in each ventilation exhaust air for constants, use installed in electronic control air valve at the end of the tuyere Angle and (pipe hydrostatic or PLC programming) the frequency of the inverter control fan operation, meet the state ventilation exhaust air, Increase the air flow when the switch is closed, and decrease the air flow when the switch is open. Advantages: Energy saving. By switching the ventilation of the fume hood and room to a low air flow rate, significant energy savings can be achieved. High quality flow control is achieved by fast and stable regulation method. Compared with variable air volume control system, the equipment cost of control system is low. Disadvantages: A high - low (or maximum - minimum) switch between two predetermined values of airflow. The opening position of the adjustment door is unknown, and the surface wind speed may be high or low, which may reduce the safety. Surge frequency conversion control mode: In the process of adjusting the door movement, the surface wind speed of the fume hood is kept constant, and the opening of the control valve [] is controlled. At the same time, the frequency converter controls the running frequency of the fan, so as to meet the air volume required by the setting surface wind speed of the fume hood and achieve the control effect of constant wind speed on the fume hood surface. At the same time to ensure the dust collection capacity of the fume hood and significantly energy saving. Advantages: Adjust the door closing season can be significant; Adjust [] position change to maintain the correct surface wind speed, safety increase; Inherent alarm and monitoring functions are a typical component of VAV systems, while increasing safety. Laboratory flexibility is increased because VAV control systems can easily adapt to system changes. As the wind flow decreases, the sound level decreases. Disadvantages: If the regulating door is kept open, there will be high wind flow and high operating cost problems. The cost of control systems can lead to high investment costs. Because the general adjustment position determines the air volume, the incorrect adjustment door management will affect the investment recovery, sound effect, uneven situation. Different variable air volume system performance is different, different systems, control speed, regulation ratio, stability and maintenance needs are obviously different. In the daily operation of the laboratory, the corresponding waste gas will be generated. If it is directly discharged into the atmosphere without treatment, it is bound to pollute the surrounding environment and cause damage to the human body. For the inorganic and organic waste gas contained in waste flushing, different waste treatment schemes will be made according to the different types of waste gas. Inorganic waste gas: nitrogen oxide, sulfide, hydrogen chloride and hydrogen cyanide. Hydrogen chloride sulfur dioxide and other inorganic waste gas. Organic waste gas: mainly including aromatic: benzene toluene, xylene, styrene, etc.; Aldehydes and ketones: formaldehyde, acetaldehyde, glutaraldehyde, butyral, acetone, cyclohexanone, methyl ethyl ketone, acetophenone, etc. Esters: isobutyl acetate, ethyl acetate, butyl acetate, methyl acetate, banana water, etc. Alcohols: methanol ethanol, butanol propanol glycol, etc. Activated carbon adsorber working principle: Chemical smoke and harmful gases through the fan into the activated carbon adsorber, activated carbon and smoke molecules oxidation reaction and adsorption reaction, and is hydrolyzed into carbon dioxide and water, so as to reduce environmental pollution. Working principle of water spray purification tower: Fan drive chemical acid mist through water spray device, spray into a fine mist of neutralization liquid, waste gas is absorbed onto the surface of the tiny droplets and the slots to collect and clean air filter mist further back into the atmosphere, the liquid through the pump from collecting tank to draw the upper nozzle, neutralization reaction with exhaust gas back to the collecting groove, After the waste liquid is treated, it is put into the outside world or recycled.
