CN216779795U

CN216779795U - Circulating self-cleaning structure fume hood

Info

Publication number: CN216779795U
Application number: CN202122628614.2U
Authority: CN
Inventors: 王国东; 杜志波; 韩娜
Original assignee: Dezhizhao Technology Suzhou Co ltd
Current assignee: Dezhizhao Technology Suzhou Co ltd
Priority date: 2021-10-29
Filing date: 2021-10-29
Publication date: 2022-06-21
Anticipated expiration: 2031-10-29

Abstract

The utility model relates to a circulating self-cleaning structure fume hood which comprises an air inlet (1), a fan (2), an air purifying, filtering and regenerating device (3) and a circulating air supplementing opening (4) which are sequentially connected through a pipeline, wherein circulating air flow uniformly enters the air purifying, filtering and regenerating device (3) through the air inlet (1), and is supplemented into the fume hood through the air supplementing opening (4) after being purified. Compared with the prior art, the utility model reduces the total external air discharge amount of the fume hood on the premise of ensuring that harmful volatile matters can be effectively and quickly discharged in the operation process.

Description

Circulating self-cleaning structure ventilation cabinet

Technical Field

The utility model relates to the field of air purifiers, in particular to a circulating self-cleaning structure fume hood.

Background

The environmental requirement of laboratory is generally higher, because some volatility test reagent commonly used can be deposited in the laboratory, these volatility reagents can produce volatile gas usually, and some are poisonous and harmful, also can produce harmful gas during the experiment in addition, to experimental environment influence, not only can influence the accuracy of test data, harmful gas still can influence experimenter's physical and mental health, therefore the laboratory has corresponding exhaust system usually, in time updates the ambient air in the laboratory.

The experimental ventilation equipment is widely used in hospitals, schools, various research institutes and other series of research places, the fume hood is an indispensable component in laboratory ventilation design, in order to prevent laboratory workers from inhaling some toxic, pathogenic or non-toxic chemical substances and organisms, good ventilation should be realized in a laboratory, the most important function in the functions of the fume hood is an exhaust function, in a chemical laboratory, various harmful gases, odor, moisture and inflammable, explosive and corrosive substances are generated during experimental operation, in order to protect the safety of a user, the diffusion of the pollutants in the experiment to the laboratory is prevented, and the operation related to the pollution source is carried out in the fume hood.

At present, the structure of a laboratory fume hood is shown in fig. 1, the fume hood comprises a workbench 101, a cabinet door 102, an air duct 103 and a cabinet top air outlet 104, when the laboratory fume hood is used, the cabinet door 102 is opened, a fan sucks indoor air into the fume hood from the cabinet door 102, takes away polluted gas generated on the workbench 101, exhausts the polluted gas from the air duct 103, and exhausts the polluted gas into the atmosphere through the cabinet top air outlet 104. When a ventilation cabinet door is opened to carry out relevant operations, indoor air is pumped out of a room by an exhaust fan through a pipeline system, air flow distribution is uneven in the process and is easy to generate turbulence, partial harmful gas cannot be effectively discharged in time, in order to enable the harmful gas generated in an experiment to be discharged out of the room, the air volume and the air speed of exhausting air to the outside of the room are increased frequently, a large amount of fresh air needs to be supplemented into the room, meanwhile, a large amount of indoor air is discharged, the load of an air conditioning unit system is greatly increased, and a large amount of electric energy consumption is caused. If natural air supplement is adopted to reduce energy consumption, the working comfort of experiment operators is also influenced.

SUMMERY OF THE UTILITY MODEL

The utility model aims to overcome the defects in the prior art and provide the circulating self-cleaning structure fume hood which can ensure that harmful gas can be effectively and quickly discharged and reduce the external air discharge rate of the fume hood.

The purpose of the utility model can be realized by the following technical scheme: the utility model provides a circulation self-purification structure fume chamber, includes air intake, fan, air purification filtration and regenerating unit and the mend wind gap that connect gradually through the pipeline, the air intake make the air inlet evenly get into air purification filtration and regenerating unit and purify, in the fume chamber is mended back through the mend wind gap after the evolution.

Furthermore, the air inlet is a strip-shaped opening formed between the strip-shaped wing plate and the work table of the fume hood, the size of the air inlet can be controlled by adjusting the turnover angle of the wing plate, and therefore the air inlet speed is controlled, and air inlet is uniform.

Furthermore, the fan is installed between the air inlet and the air purifying, filtering and regenerating device, and air in the fume hood is sucked into the air purifying, filtering and regenerating device from the air inlet.

Furthermore, the fan is an ultra-silent pipeline fan, the variable frequency speed regulation control is adopted, the running speed is adjustable, the running speed of the fan is automatically adjusted according to the opening range of a cabinet door of the fume hood, or the running speed is manually set through an operation panel, the fan blades are designed in an ultra-silent mode, and the running noise is below 55 decibels.

Furthermore, the air purification, filtration and regeneration device comprises a cavity and a composite activated carbon filter element arranged in the cavity, wherein a conductive coil is arranged in the composite activated carbon filter element;

during purification, air containing harmful gas enters the cavity, harmful substances in the air are adsorbed by the composite activated carbon filter element, and filtered clean air is discharged;

during regeneration, the conductive coil generates a magnetic field with high-frequency change, eddy current can be generated inside the composite active carbon filter element under the action of the magnetic field, and the composite material is heated, so that adsorbed harmful substances are released from the composite active carbon filter element and are discharged to the outside.

Furthermore, a temperature sensor is pre-embedded in the composite activated carbon filter element, so that the temperature of the filter material during regeneration is accurately controlled, and the filter element is prevented from being damaged due to overheating.

Furthermore, the cavity be divided into two cavities by compound active carbon filter core, wherein be equipped with the air inlet on the first cavity, be equipped with the gas vent on the second cavity, the fan is connected to the air inlet, the gas vent passes through exhaust duct and connects the air supplement mouth.

Furthermore, the exhaust port side of the air purifying, filtering and regenerating device is also provided with a detection port, the detection port is connected to an air inlet pipeline in front of the air purifying, filtering and regenerating device through a detection pipeline, the detection pipeline is provided with a VOC detection sensor, a pressure difference sensor and an electromagnetic valve, wherein the VOC detection sensor detects the quality of the purified air, the pressure difference sensor detects the pressure difference between the front and the back of the air purifying, filtering and regenerating device, and the electromagnetic valve is closed in the regeneration working mode of the air purifying, filtering and regenerating device to protect each sensor on the detection pipeline.

Furthermore, the air supply opening is a long-strip-shaped pipeline arranged at the top of the ventilation cabinet, an even air outlet is formed in the long-strip-shaped pipeline, and purified air is discharged through the air supply opening to form an air curtain.

The pipeline for connecting the components is made of PVC, PP or PTEF, so that the acid and alkali corrosion resistance is good, the pipeline can be cut on site, and the pipe joint is made of standard parts, so that the construction and installation are convenient;

the fan shell is made of a non-metal material with good acid-base corrosion resistance or a metal material with an anti-corrosion coating.

The circulating self-cleaning structure (comprising an air inlet, a fan, an air purification, filtration and regeneration device and an air supply port which are sequentially connected by the pipelines) can be arranged inside the bottom cabinet at the lower part of the fume hood and also can be arranged at the top of the fume hood; the mode of supplementing air to the fume hood can adopt the mode of supplementing air to the front upper corner or the lower corner inside the fume hood; the ventilation cabinet can be supplemented with air by adopting a mode of supplementing air to the outer side of the ventilation cabinet.

Compared with the prior art, the utility model has the following beneficial effects:

firstly, the fume hood is internally provided with the air purification device, so that the fume hood has broad-spectrum purification capability on volatile pollutants, and the air exhaust volume of the fume hood is reduced by adopting the internal purification of the polluted air in the fume hood and a circulation mode, so that the remarkable energy-saving effect is realized. The fume chamber air exhaust part enters the purification device, and then enters the fume chamber internal circulation after purification, so that the internal air quantity of the fume chamber is increased, and the concentration of pollutants is reduced.

And secondly, the filter element for air purification adopts a reproducible working mode, so that the recycling of the filter element is realized, the service life of the filter element is greatly prolonged, and the use and maintenance cost of the ventilation cabinet is reduced.

And thirdly, the regeneration of the filter element for air purification can be set to be automatically carried out when no person works at night, so that the interference to the work of an operator in the daytime is avoided.

Fourthly, an air curtain device, namely an air supplement port, is arranged above the front of the operator to generate an air curtain to protect the head of the operator, and a protective air curtain is formed at an operation view window to prevent the operator from inhaling pollutants through the nose and the mouth to cause damage to the body;

and fifthly, an air supplementing wing, namely a wing plate type air inlet, is arranged at the edge of the table top below the window, and the air supplementing wing can maintain the air volume sucked into the room under the condition that the window of the ventilation cabinet is closed, so that the air volume is balanced, and the generation of turbulent flow is prevented.

Sixthly, convenient maintenance: the air purification and regeneration device is arranged in the bottom cabinet, the operation space is large, and the installation and the disassembly are easy.

Drawings

FIG. 1 is a schematic view of a prior art fume hood;

FIG. 2 is a schematic structural view of a circulating self-cleaning ventilation hood of the present invention;

FIG. 3 is a schematic view of the opening state of the circulating self-cleaning structure ventilation cabinet door of the present invention;

FIG. 4 is a schematic structural view of a circulating air purification system according to the present invention;

FIG. 5 is a schematic view of the air purifying, filtering and regenerating device and its piping connection system of the present invention;

FIG. 6 is a schematic view of the air purifying, filtering and regenerating device according to the present invention;

FIG. 7 is a schematic structural view of a circulating self-cleaning ventilation hood according to embodiment 2 of the present invention;

FIG. 8 is a schematic structural view of a circulating self-cleaning ventilation hood according to embodiment 3 of the present invention;

FIG. 9 is a schematic structural view of a circulating self-cleaning ventilation hood according to embodiment 4 of the present invention;

fig. 10 is a schematic structural view of a circulating self-cleaning ventilation hood according to embodiment 5 of the present invention.

Detailed Description

The following examples are given for the detailed implementation and specific operation of the present invention, but the scope of the present invention is not limited to the following examples.

The composite active carbon filter element 32 in the air purifying, filtering and regenerating device 3 of the utility model is a regenerated active carbon filter element developed by the limited company of the Showa science and technology (Shanghai), the filter element is formed by wrapping and assembling active carbon and a metal wire filter screen, wherein the particle size of the active carbon is 5mm, the pore diameter is 0.1mm, and the specific surface area is 0.1mm>300m²The activated carbon has the structure that the microcrystalline carbon is irregularly arranged, pores are arranged among cross connections, the capillary pores have an adsorption effect on organic gas molecules which are contacted with the activated carbon, the organic gas molecules are adsorbed and stored in the capillary pores of the activated carbon, the Brownian motion of the molecules is enhanced at high temperature, and the organic molecules in the activated carbon capillary are released from the activated carbon by breaking away from the adsorption of the capillary. The conductive coil is a high-frequency electromagnetic coil which is formed by insulating and packaging thin copper wires and a bracket, and the composite active carbon filter element can be heated to more than 100 ℃ under the condition of electrifying to desorb adsorbed organic matters.

Example 1

As shown in fig. 2, a circulating self-cleaning structure fume hood, the arrow indicates the air flow direction, including workstation 101, cabinet door 102, wind channel 103 and cabinet top air exit 104, still includes air intake 1, fan 2, air purification filtration and regenerating unit 3 and the air supply opening 4 that connect gradually through the pipeline, air intake 1 make the air inlet evenly get into air purification filtration and regenerating unit 3 and purify, mend back in the fume hood through air supply opening 4 after evolving. Fig. 2 shows a closed state of the cabinet door, and fig. 3 shows an open state of the cabinet door.

According to the utility model, the main source of air supplement of the fume hood is that substances which may harm human bodies, such as volatile organic matters and the like in polluted air in the fume hood, are adsorbed by purifying and filtering, and then the purified air is supplemented back into the fume hood through a pipeline fan. This prevents the air in the room from being drawn out to the outside as a large amount of return air. Meanwhile, due to the adoption of an air purification technology, the concentration of pollutants is greatly reduced, and the air quantity discharged to the outside is obviously reduced. The load of the air conditioning unit system is obviously reduced, thereby achieving the aim of saving energy.

Fig. 4 is a schematic view of the circulating air cleaning system of the present invention, with arrows indicating the direction of air flow.

The strip-shaped wing plate is arranged on the edge, close to the cabinet door 102, of the workbench 101, the strip-shaped opening formed between the strip-shaped wing plate and the workbench of the fume hood is an air inlet 1, the size of the air inlet is controlled by adjusting the turnover angle of the wing plate, and therefore the air inlet speed is controlled, and air inlet is even.

The pipe reaches and the pipe fitting all adopts PVC or PP material tubular product, and acid and alkali corrosion resistance is good, and can cut on the spot, and the coupling adopts the standard component, and the installation of conveniently constructing, the coupling adopts the standard component, is difficult to produce the corruption, and low in production cost, and it is convenient to install, is favorable to this to send out a meal and popularizes and applies.

The fan 2 is arranged between the air inlet 1 and the air purification, filtration and regeneration device 3, and is used for sucking air in the fume hood from the air inlet 1 into the air purification, filtration and regeneration device 3. The fan 2 is an ultra-silent pipeline fan, frequency conversion speed regulation control is adopted, the running speed is adjustable, the running speed of the fan is automatically adjusted according to the opening range of a cabinet door of the fume hood, or the running speed is manually set through an operation panel, fan blades are designed in an ultra-silent mode, and the running noise is below 35 decibels. Due to the ultra-silent design of the fan 2, the noise is very low during operation, and meanwhile, the rotating speed of the motor can be adjusted by adopting a variable frequency speed regulation technology, so that the air quantity of the fan can be adjusted according to requirements, and further energy-saving operation is achieved.

As shown in fig. 5-6, the air purifying, filtering and regenerating device 3 includes a cavity 31, and a composite activated carbon filter 32 disposed in the cavity 31, wherein a conductive coil 33 is disposed in the composite activated carbon filter 32; the composite active carbon filter core 32 is internally embedded with a temperature sensor 34, so that the temperature of the filter material during regeneration can be accurately controlled, and the damage of the filter core caused by overheating can be prevented. Air purification filter and regenerating unit 3's shell 37 can be rectangle, or square or circular, or other shapes, be the rectangle structure in this embodiment, the inside cavity 31 of casing 37 is divided into two cavitys by compound activated carbon filter core 32, wherein be equipped with air inlet 35 on the first cavity, be equipped with gas vent 37 on the second cavity, the gas vent can set up a plurality ofly, the gas vent is equipped with two in this embodiment, two gas vents, fan 2 is connected to air inlet 35, two gas vents 37 connect the mending wind mouth 4 both ends through two exhaust duct 62.

In the fume hood, a plurality of sensors are adopted for detecting the operation condition of the system, and specifically, as shown in fig. 2 and 5, a detection port 36 is further provided on the second cavity of the air purification filtration and regeneration device 3, the detection port 36 is connected to an air inlet pipe (in this embodiment, connected to an air inlet pipe 61 in front of the fan 2) in front of the air purification filtration and regeneration device 3 through a detection pipe 5, and a VOC detection sensor 51, a differential pressure sensor 52 and an electromagnetic valve 53 are provided on the detection pipe 5.

Wherein VOC detection sensor 51 detects the air quality after purifying, and differential pressure sensor 52 detects the pressure difference before and after air purification filters and regenerating unit 3, and when the filter core blockked up, differential pressure sensor 52 can detect the rise of front and back pressure, and when differential pressure exceeded a numerical value of settlement, it is possible that the filter core exists the jam of certain degree, need carry out the inspection maintenance or the change of filter core, and control system can send out the police dispatch newspaper, notifies the user to inspect the change filter core. Solenoid valve 53 is under air purification filters and regenerating unit 3's compound active carbon filter core 32 regeneration mode, solenoid valve 53 is the closed condition, cut off air detection pipeline 5, thereby the VOC detection sensor 51 of protection rear end, avoid it to expose under the VOC environment of high concentration for a long time, cause the ageing or the harm of VOC detection sensor, VOC detection sensor 51 is arranged in under air purification filters and regenerating unit 3 purification mode, detect the content of VOC in the air after the active carbon filters, when VOC's content in the air exceeds certain concentration, automatically regulated fan rotational speed, increase air volume is and send the suggestion, remind operating personnel to increase to exhaust or carry out equipment inspection.

Air supply opening 4 for setting up the rectangular form pipeline at the fume chamber top, be equipped with a plurality of align to grid's gas outlet on this rectangular form pipeline, the air after the purification is discharged through the air supply opening, forms the air curtain, protects operating personnel head, forms the protection air curtain at the operation sight window, prevents that operating personnel from having an empty mouth nose to inhale the pollutant, causes the harm on the health.

The air purifying, filtering and regenerating device 3 of the utility model has two working modes: air purification mode of operation and regeneration mode of operation:

in the air purification working mode, the polluted air is driven by the fan 2 to flow into the air purification filtering and regenerating device 3 along the air inlet pipeline 61 from the air inlet 1, the harmful substances such as VOC are adsorbed by the composite active carbon filter element 32, so that the concentration of volatile substances such as VOC in the air is gradually reduced, and when the harmful substances such as VOC adsorbed in the composite active carbon filter element 32 are continuously accumulated to reach a certain degree, the adsorption function regeneration of the active carbon filter is required in order to ensure that the composite active carbon filter element 32 can continuously adsorb the harmful substances such as VOC;

in a regeneration working mode, high-frequency alternating current is introduced into the conductive coil 33 embedded in the composite activated carbon filter element 32 to generate a magnetic field with high-frequency change, a ferromagnetic material in the composite activated carbon filter element 32 induces and generates eddy current under the magnetic field with high-frequency change, so that the composite activated carbon filter element 32 is heated, harmful substances such as VOC in the composite activated carbon filter element 32 are released and exhausted from the cabinet top air outlet 104 through the air duct 103, and after a certain period of regeneration, the composite activated carbon filter element 32 recovers an adsorption function again. Regeneration is generally set at night (the specific time can be set, such as 0: 00 to 2: 00), and the fume hood automatically operates when no staff operates the fume hood, when the fume hood operates, the door of the fume hood is ensured to be in a closed state, meanwhile, an outdoor exhaust device of the fume hood needs to be opened, air containing harmful substances such as VOC and the like in the fume hood is discharged to the outside, pollution is prevented from being released to the inside of a room, a temperature sensor 34 is embedded in a filter element, the temperature of the filtering material during regeneration can be accurately controlled, and damage of the filter element caused by overheating is prevented.

Comparative example

The conventional fume hood of a certain famous American brand is adopted as a comparative example as shown in figure 1.

The circulating self-cleaning ventilation cabinet in the embodiment 1 and the ventilation cabinet in the comparative example are compared, the sizes of the circulating self-cleaning ventilation cabinet and the ventilation cabinet are the same, and the workbench 101, the cabinet door 102, the air duct 103 and the cabinet top air outlet 104 are the same, so that the test is carried out.

The performance results are shown in the following table:

test items	Example 1	Comparative example
			Total air quantity discharged outside pipeline	441m³/h	1100m³/h
Ventilation cabinet surface wind speed	0.46m/s	0.5m/s
			Residual concentration of fume hood	0.01ppm	0.01ppm
Service life of filter element	24 months old	Is free of

As can be seen from the above table, the total air volume discharged outside the fume hood is reduced on the premise that the fume hood ensures that harmful gases can be effectively and quickly discharged. Thereby effectively reducing the energy consumption consumed by the laboratory.

In a typical laboratory equipped with an air conditioner, the energy consumption of the fresh air load due to the laboratory exhausting air to the outside is very high. Therefore, reducing the amount of exhaust air is the key to reducing energy consumption.

Example 2

As shown in fig. 7, the circulating self-cleaning structure (including the air inlet 1, the fan 2, the air purifying, filtering and regenerating device 3 and the air supply port 4 which are sequentially connected by the above-mentioned pipes) is arranged at the top of the fume hood; and air is supplemented to the fume hood by adopting a mode of supplementing air to the outer side of the fume hood. The rest is the same as example 1.

Example 3

As shown in fig. 8, the air supply opening 4 is arranged at the door of the fume hood, and supplies air from the back plate of the fume hood and from the upper part and the wing plate, which is the same as that in embodiment 1.

Example 4

As shown in fig. 9, the circulating self-cleaning structure (comprising the air inlet 1, the fan 2, the air purifying, filtering and regenerating device 3 and the air supply opening 4 which are sequentially connected by the above-mentioned pipelines) is arranged at the top of the fume hood, wherein (the inlet air of the circulating self-cleaning device is introduced from the wing plate of the fume hood, see the arrow of the air flow direction at the wing plate of the fume hood in the figure), the rest is the same as that of the embodiment 2.

Example 5

As shown in fig. 10, the circulating self-cleaning structure comprises an air inlet 1, a fan 2, an air purifying and filtering and regenerating device 3 and an air supplementing opening 4 which are sequentially connected by the pipelines, wherein the fan 2 is arranged in an air duct of the fume hood, the inlet of the fan 2 is provided with the filtering device, the outlet of the fan 2 is divided into two branches, one branch is directly communicated with the external atmosphere, the other branch is connected with the air purifying and filtering and regenerating device 3, the air supplementing opening is arranged at the outer side of a fume hood door (in the structure, the primary purifying and filtering device and the fan are arranged in the space behind a flow guide plate of the fume hood for convenient installation and maintenance, the upper part of the fan is provided with a three-way valve for controlling the air flow direction after primary purification, wherein the first flow direction is that a first valve 7 is opened to be discharged to the outside, the second flow direction is that a second valve 8 is opened to be used as return air supplement through secondary purification and filtration to be supplemented to the outer side of the fume hood door, because through second grade purification filtration, volatile harmful substance is dispelled in the anaplerosis wind effectively, avoids volatile harmful substance to escape indoor, causes personnel's injury. In the process of regenerating the filtering function of the primary purifying and filtering device, the first valve 7 is opened, and the second valve 8 is closed, so that the air with high content of harmful substances is directly discharged to the outside without being used as the air supply to supply air into the ventilation cabinet. ).

Claims

1. The utility model provides a circulation self-purification structure fume chamber, its characterized in that includes air intake (1), fan (2), air purification filtration and regenerating unit (3) and mend wind gap (4) that connect gradually through the pipeline, and circulating air passes through air intake (1) and evenly gets into air purification filtration and regenerating unit (3), mends back in the fume chamber through mend wind gap (4) after the purification treatment.

2. The circulating self-cleaning structure fume hood according to claim 1, characterized in that the air inlet (1) is a strip-shaped opening formed between the strip-shaped wing plate and the fume hood workbench, and the size of the air inlet is controlled by adjusting the turning angle of the wing plate, so that the air inlet speed is controlled, and the air inlet is uniform.

3. A self-cleaning ventilator according to claim 1 wherein said blower (2) is installed between the inlet (1) and the air cleaning, filtering and regenerating device (3) to suck the air in the ventilator from the inlet (1) into the air cleaning, filtering and regenerating device (3).

4. A circulating self-cleaning structure fume hood according to claim 1, characterized in that the fan (2) is an ultra-silent pipeline fan, and frequency-variable speed-regulating control is adopted.

5. A ventilated hood with a circulating self-cleaning structure according to claim 1, wherein the air purifying, filtering and regenerating device (3) comprises a cavity (31), and a composite activated carbon filter element (32) arranged in the cavity (31), wherein a conductive coil (33) is arranged in the composite activated carbon filter element (32);

during purification, air containing harmful gas enters the cavity (31), harmful substances in the air are adsorbed by the composite activated carbon filter element (32), and filtered clean air is discharged;

during regeneration, the conductive coil (33) generates a magnetic field with high-frequency change, eddy current is generated inside the composite active carbon filter element (32) under the action of the magnetic field, and the composite material is heated, so that adsorbed harmful substances are released from the composite active carbon filter element (32) and are discharged to the outside.

6. The circulating self-cleaning structure fume hood as recited in claim 5, wherein a temperature sensor (34) is embedded in the composite active carbon filter core (32) to precisely control the temperature of the filter material during regeneration, thereby preventing damage of the filter core caused by overheating.

7. The ventilated cabinet with the circulating self-cleaning structure according to claim 5, wherein the cavity (31) is divided into two cavities by the composite activated carbon filter core (32), wherein the first cavity is provided with an air inlet (35), the second cavity is provided with an air outlet, the air inlet (35) is connected with a fan, and the air outlet is connected with the air supplementing opening (4) through an air exhaust pipeline.

8. The circulating self-cleaning structure fume hood according to claim 1 or 7, characterized in that the exhaust side of the air purifying filtering and regenerating device (3) is further provided with a detection port (36), the detection port (36) is connected to the air inlet pipeline in front of the air purifying filtering and regenerating device (3) through a detection pipeline (5), the detection pipeline (5) is provided with a VOC detection sensor (51), a pressure difference sensor (52) and an electromagnetic valve (53), wherein the VOC detection sensor (51) detects the quality of the purified air, the pressure difference sensor (52) detects the pressure difference in front of and behind the air purifying filtering and regenerating device (3), and the electromagnetic valve (53) is closed in the regeneration working mode of the air purifying filtering and regenerating device (3) to protect the sensors on the detection pipeline (5).

9. A self-cleaning circulating ventilation hood as claimed in claim 1, wherein the air supply opening (4) is an elongated duct provided at the top of the ventilation hood, the elongated duct is provided with uniform air outlets, and the cleaned air is discharged through the air supply opening to form an air curtain;

the pipeline for connecting each component is made of PVC or PP material;

the shell of the fan (2) is made of non-metallic materials with good acid and alkali corrosion resistance.

10. A cyclic self-cleaning structure fumehood according to claim 1 wherein the cyclic self-cleaning structure is disposed within a lower bottom cabinet of the fumehood or on top of the fumehood; supplementing air to the fume hood by supplementing air to the front upper corner or the lower corner inside the fume hood; or the ventilation cabinet is supplemented with air by adopting a mode of supplementing air to the outer side of the ventilation cabinet.