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    Home > Active Ingredient News > Drugs Articles > Laboratory exhaust gas treatment

    Laboratory exhaust gas treatment

    • Last Update: 2020-11-17
    • Source: Internet
    • Author: User
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    First, the harm of laboratory exhaust gas to all kinds of chemical laboratories in the country is quite a lot, mainly distributed in various schools, scientific research institutions and enterprises, distribution is very wide, some chemical laboratories due to historical reasons, or in the city center, or in densely populated areas, acid treatment samples in the irregular discharge of a large number of harmful gases, not only to the atmosphere, but also to the surrounding population, vegetation caused serious harm, and the harm to the population has potential.
    rainy, low pressure climate, exhaust gas is difficult to spread in time, but also exacerbated the pollution level of the local environment, resulting in the formation of local severe acid rain, constitute a serious social hazard.
    The current situation of emissions from domestic laboratories: the vast majority of chemical laboratory emissions using direct emissions, the general laboratory using pipes concentrated on the roof, fan direct emissions, and some laboratories using decentralized exhaust fan direct emissions, basically no exhaust gas treatment, there are many laboratories for exhaust gas treatment after emissions.
    direct emissions to some extent partially improve the working environment of operators, but still directly caused pollution to the atmosphere, seriously affecting the ecological environment of the surrounding areas, its losses can not be measured by money.
    2. Because of the different working properties of various chemical laboratories, the relevant institutions compare and discuss the treatment methods of harmful gases emitted by chemical laboratories, and summarize the following four methods of laboratory exhaust gas treatment.
    1. The combustion method includes high temperature combustion and catalytic combustion, the former requires additional fuel combustion, therefore, when using the method to consider the recovery of heat energy;
    considering that the heat recovered by the high temperature combustion method exceeds the heat required for production, it is not appropriate.
    direct catalytic combustion investment is too large.
    2. Condensation method mainly uses cold medium to treat high temperature organic exhaust vapor, which can effectively recover solvents.
    treatment effect is related to the temperature of refrigerant, the treatment efficiency is relatively low compared with other methods, and the treatment of high concentration exhaust gas is applicable.
    3. Absorption method is the process of separating harmful components from the air stream by using different components in the gas mixture to dissolve different degrees in the absorbent, or by selective chemical reaction with the absorbent.
    This method has the characteristics of high capture efficiency, simple equipment structure, low one-time investment, small footprint and convenient installation and commissioning, so it is widely used in the treatment of gaseous pollutants, especially inorient gaseous pollutants control.
    , such as exhaust gases containing HC1, HF, S02, HC10 and other pollutants, can be absorbed and purified by wet method.
    specifically, the use of thin lye or water as an absorbent, the use of spray system to fully atomize the absorbent and exhaust gas in the container evenly mixed reaction, so as to achieve a good absorption effect.
    commonly used in wetting are filler towers, plate towers, spray towers, Venturi scrubbers and rotating spray towers.
    there are two common absorption methods used in laboratory exhaust gas treatment.
    (1) There is pump water mist absorption method has pump water mist absorption method application time is earlier, more application in the chemical industry, the principle is the use of acid-resistant pumps to circulating pool liquid through pipes and end atomized nozzles into the absorption cavity, so that the absorption cavity is filled with a large number of water mist particles.
    chemical laboratory harmful gases by the wind pipe introduced into the absorption device, after the absorption cavity, a large number of water mist particles use its surface area and harmful gas full contact, collision with each other, in the process, water mist particles not only dissolve the various chemicals in the harmful body, but also gradually increase the water by collision with each other The particle volume of the fog, blocked by the wind shield function, the water mist further accumulated into a larger water droplet, playing the role of gas separation, water droplets rely on their own gravity to overcome the absorption of the wind speed in the cavity force and fall into the collection disk, and into the circulating water tank, absorption device principle.
    the method is that the water mist absorption device is simpler, the processing size accuracy of each part is lower, and the installation and commissioning is convenient.
    But in the course of operation, acid-resistant pump continuous work, and spray head in the work due to various factors easily change the spray condition, affect the atomization effect, reduce the purification effect of the entire device on the exhaust gas, at the same time due to the continuous operation of the pump, its rotating parts wear, prone to liquid leakage, resulting in secondary pollution.
    Therefore, in order to keep the absorption device in good working condition, in addition to regular maintenance also need to be checked from time to time, at any time to replace poor atomization nozzles and acid-resistant pump wear seals.
    requires a certain maintenance cost and energy consumption of acid-resistant pumps in operation.
    (2) no pump water curtain absorption method no pump water curtain absorption method put into practical application much later than there is pump water mist absorption method, is only gradually applied to the actual in recent years.
    although the application of this method is relatively late, but the very significant advantages of the application of this method has been rapid development, the principle is in the absorption device vertically divided into gas-liquid mixture and gas-liquid separation of the two areas, exhaust gas through the pipeline to send people to the device, first through the circulation of water curtain flushing and water curtain filtration, and then along the lower edge of the water pan-water plate across the water tank surface, into the water channel, water in the water tank in the air flow. Under the atomization and become water mist, through the gas and water channel is raised to the water collection plate, the water mist in the water collection board is collected by the water retaining plate and then flowed into the spillway, the overflowing water flow along the water pan plate back to the water tank, exhaust gas in the gas channel and water mist violent impact mixing, so that the harmful substances in the exhaust gas are absorbed into the water, through the water stopper separate water mist after exit.
    method is characterized by the relatively complex internal structure of the absorption device, which has certain requirements for processing accuracy.
    the method does not require any maintenance work and energy consumption expenditure in operation, and covers a small area, meta-secondary pollution phenomenon, no noise.
    the mutual contact between water and gas in operation is relatively full, so the absorption efficiency of harmful substances in exhaust gas is high, which is a method worthy of further exploration and popularization.
    4. Adsorption purification by adsorption means the process by which a certain component or component of a mixture is absorbed on a solid surface by using unbalanced molecular gravity or chemical bonds present on the solid surface when the gas mixture comes into contact with an appropriate multi-child L-like solid.
    a solid with adsorption is called an adsorbent, and the absorbent substance is called an adsorption substance.
    advantage of this method is that it can recover useful parts, the equipment is simple, the operation is convenient, and the automatic control is easy to realize.
    But because the materialization performance of adsorbents is different, with strong targeting, so the treatment of exhaust gases containing different harmful substances must be equipped with different physical and chemical properties of adsorbents, in order to play a good role in gas purification; Absorption capacity, and the content of harmful substances in the exhaust gas has certain requirements, the content of harmful substances in the exhaust gas is too high, the effect of exhaust gas purification will not be ideal, in the exhaust gas through the adsorption medium, because the air flow is blocked by the solid medium, it is necessary to increase the power of the fan to ensure the normal wind speed of the ventilation system.
    the adsorption capacity is generally not high (about 40%), adsorbents need to be replaced regularly or regenerated to ensure the normal operation of the absorption device.
    so the method in the practical application needs to invest a certain amount of cost and manpower, replaced adsorbents or adsorbents for regeneration treatment are prone to secondary pollution.
    this method is generally used for the relatively stable and low content of the types of hazardous substances in the exhaust gas treatment, which facilitates the use of a targeted adsorbent. the principle of dry adsorption commonly used in
    laboratory exhaust gas treatment is to let harmful gases pass through the dry adsorption medium, so that the harmful substances are adsorbed into the media when the gas passes through the adsorption medium, so that the purified gas and harmful substances are separated, to achieve the purpose of gas purification.
    The absorption device structure of this method is simple, but the adsorption medium because of its different materialization performance, has a strong target, so the exhaust gas treatment containing different harmful substances must be configured with different physical and chemical properties of the adsorption medium, in order to play a good role in gas purification, so the selection of adsorption media is very critical.
    because the exhaust gas passes through the adsorption medium for a short time, this requires the adsorption medium has a very strong adsorption capacity.
    and the content of harmful substances in the exhaust gas has certain requirements, the content of harmful substances in the exhaust gas is too high, the effect of exhaust gas purification is not ideal.
    when the exhaust gas passes through the adsorption medium, because the air flow is blocked by the solid medium, the power of the fan must be increased in order to ensure the normal wind speed of the ventilation system.
    important thing to stress is that the adsorption capacity of any adsorption medium is limited.
    the adsorption medium needs to be replaced regularly or regenerated to ensure the normal operation of the absorption unit.
    so the method in practical application needs to invest a certain amount of cost and manpower, replaced adsorption media or adsorption media for regeneration treatment are prone to secondary pollution.
    this method is generally used for the relatively stable and low content of harmful substances in the exhaust gas treatment, easy to use a targeted adsorption medium.
    5. Laboratory emission hazards so the country's various types of chemical laboratories are quite a lot, mainly distributed in various schools, scientific research institutions and enterprises, distribution is very wide, some chemical laboratories due to historical reasons, or in the city center, or in densely populated areas, acid treatment samples in the irregular discharge of a large number of harmful gases, not only to the atmosphere, but also to the surrounding population, vegetation caused serious harm, and the harm to the population has potential.
    rainy, low pressure climate, exhaust gas is difficult to spread in time, but also exacerbated the pollution level of the local environment, resulting in the formation of local severe acid rain, constitute a serious social hazard.
    6. Laboratory treatment methods Laboratory instruments and equipment are changing with the next day, more and more experimental operation projects, the use of reagents is increasing.
    the laboratory chemical odor is very large, the laboratory environment has been seriously polluted.
    the health of laboratory staff is endangered and the risk of occupational diseases increases.
    Due to the need for new work, but also in order to improve the laboratory environment, reduce man-made environmental pollution, the use of pipeless catheter clean air ventilation cabinet and clean gas medicine cabinet effective adsorption experimental operation volatile toxic and harmful chemical gases, to provide safety protection for the experimenters.
    air-type ventilation cabinet clean air-type ventilation cabinet and clean gas-type medicine cabinet, there is online monitoring indoor environmental conditions and filter use, according to the laboratory environment level, users set their own safety alert concentration.
    provides an effective guarantee for our personal safety.
    the function of the clean air ventilation cabinet is mainly exhaust function, in the chemical laboratory, the experimental operation produces a variety of harmful gases, odors, moisture and flammable, explosive, corrosive substances, in order to protect the safety of users, prevent the spread of pollution substances in the experiment to the laboratory, in the vicinity of the source of pollution to use ventilation cabinets, in the past, the number of clean air ventilation cabinets used less, only in particularly harmful and dangerous gases and produce a large amount of heat in the experiment.
    air-type ventilation cabinet is only responsible for the auxiliary functions of the test bench.
    in recent years, taking into account the improvement of the experimental environment, the experiments carried out on the test bench gradually transferred to the clean air ventilation cabinet, which requires that the air purification ventilation cabinet should be suitable for the use of equipment functions.
    , especially in most newly built laboratories, require air conditioning, so the initial design phase of the building will be the use of clean air ventilation cabinets into the air conditioning system plan.
    Because the air-type ventilation cabinet occupies a very important position in the bio-chemical laboratory, from the aspects of improving the laboratory environment, improving the working hygiene conditions, improving the work efficiency and so on, the number of use of the clean air-type ventilation cabinet has increased dramatically.
    is followed by ventilation pipes, piping, wiring, exhaust, etc. have become an important topic in laboratory construction.
    editor: Sever Safety
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