KR20070103821A - Impinger controll system - Google Patents

Abstract

A dust-trap controlling system is provided to select the air filtering step according to condition of air within a working place, by installing a dust sensor and a gas sensor for determining the condition of inside air of the working place. A first filtering unit(21) and a second filtering unit(25) are installed on a main duct(31) for connecting an air suction port and an air supply port. A first damper(D1) and a second damper(D2) are installed at a front end and a rear end of the second filtering unit, respectively, so as to isolate the second filtering unit. The first damper and the second damper are connected by a bypass duct(32) having a third damper(D3) so that a flow path passes from downstream of the first filtering unit to upstream of the air supply port. When a pollution level measured by a pollution sensor is less than a pollution setting value, the first damper and the second damper are closed and the third damper is opened. When the pollution level measured by the pollution sensor is more than the pollution setting value, the first damper and the second damper are opened and the third damper is closed.

Description

Dust collection control system {Impinger controll system}

1 is a view showing a state in which a dust collecting system according to the prior art is installed,

2 is a cross-sectional view showing a dust collecting device according to the prior art,

3 is a view showing a state in which the dust collecting control system according to the present invention is installed,

4 is a state diagram showing a connection relationship between the dust collector according to the present invention;

5 is an operational connection diagram of a control unit according to the present invention;

6 is a flowchart illustrating a process of setting an operating state of a dust collecting control system according to the present invention.

* Explanation of symbols for main parts of the drawings

1: Dust collection control system 11: Dust sensor

12 gas sensor 13 room temperature sensor

14: outdoor temperature sensor 15: differential pressure gauge

20: dust collector 21: the first filter

22: three-phase inverter 25: the second filter

31: main duct 32: bypass duct

33: branch duct C: control unit

D1 to D5: first to fifth dampers

The present invention relates to a dust collecting control system that can remove various types of dust and harmful gas generated in the workplace, and more particularly, to a dust collecting control system that filters stepwise according to the degree of pollution of air through various sensors. will be.

In general, in automobile manufacturing plants or plastic molding plants that use a lot of equipment such as grinding machines and grinding machines, air pollutants harmful to the human body such as dust or harmful gases are generated in the factory. These air pollutants adversely affect not only the human body but also the environment. Therefore, it is mandatory to install a dust collector for a large amount of sources that can generate or generate such dusts and harmful gases such as carbon monoxide (CO), sulfur oxides (SO _X ), nitrogen oxides (NO _X ). Due to these problems, various technical developments have recently been attempted, ranging from small dust collectors such as air cleaners that can be used in homes to dust collectors installed in the same places as factories. Figure 1 shows such a conventional dust collecting system.

As shown in the figure, the conventional dust collection system 100 is connected to the dust sensor (s) for measuring the concentration of dust contained in the internal air of the workplace, the air intake port 120 and the air supply port 130 of the workplace. The duct (d) is installed to circulate the air in the workplace, the dust collector (110) for filtering the air introduced and installed in the duct (d), and receives the value detected from the dust sensor (s) Control unit (c) for controlling the operation of the dust collector (110).

The dust sensor s measures the concentration of dust contained in the air and transmits the detected value to the controller c. The control unit c determines whether the measured value received from the dust sensor s exceeds the dust concentration setting value. Here, the dust concentration setting value means the dust reference value of the air inside the workplace desired by the user. These dust concentration setting values may be different according to the cleanliness requirements of the workplace, so they can be set according to the use environment of the workplace.

At this time, when the value measured from the dust sensor (s) is less than the dust concentration setting value, the dust concentration of the air inside the workplace is repeatedly measured by the dust sensor (s) without any other operation.

On the other hand, if the value detected from the dust sensor s exceeds the dust concentration setting value, the control unit c operates a fan (not shown) installed inside the duct d. When the fan is operated, air in the workplace is delivered to the dust collector 110 through the hood h and the duct d. The air thus delivered is filtered by the dust collector 110, and the filtered clean air is circulated back into the workplace through the duct (d).

Here, the dust collecting apparatus 110 will be described in detail with reference to FIG. 2. As shown in the figure, if the value detected from the dust sensor (s) installed in the workplace exceeds the dust concentration setting value control unit (c) is installed in the fan (not shown) and the dust collector 110 in the duct (d) Operate the air nozzle power supply unit 119. At this time, when the fan is operated, the air in the workshop is introduced into the dust collector 110 through the duct (d). The air introduced in this way is first filtered by the bag filter 111.

The bag filter 111 is arranged side by side a plurality of filter cloth made of a non-woven material. The air sucked into the dust collector passes through a plurality of such filter cloths, and contaminants such as dust contained in the air passing through the filter cloth are filtered out by a fine mesh of filter cloth. In general, the bag filter 111 can be filtered to about 1㎛ particles. The primary filtered air in the bag filter 111 is moved to the HEPA filter 112 along the flow of compressed air discharged from the air nozzle 118.

The hepa filter 112 is made of artificial fibers and generally filters particles of about 0.3 μm to about 99.97%. Since the particles of this size include fine dust having an odor, the particles may be filtered to fine particles that are not filtered in the bag filter 111. At this time, the sampler valve 114 is positioned below the intermediate point between the bag filter 111 and the HEPA filter 112. A portion of the primary filtered air from the bag filter 111 is transmitted to the dust sensor s installed at the end of the tubule 116 through the sampler valve 114. The dust sensor s detects dust contained in the air and transmits the measured value to the control unit c. Thereafter, the control unit c may check the degree of air filtering by comparing the measured value detected by the dust sensor s installed in the workplace with the dust measured value of the primary filtered air. The secondary filtered air is moved to the carbon filter 113 along the flow of compressed air as described above.

On the other hand, the carbon filter 113 is composed of activated carbon having high adsorption property. Activated carbon has very fine pores than other materials. Therefore, very fine particles such as gas or smoke are adsorbed on the activated carbon and filtered. Therefore, even if noxious gas not measured by the dust sensor (s) is filtered through the carbon filter 113 even if the inside of the workplace can be filtered by the clean air required by the user.

The lower part of the intermediate point between the HEPA filter 112 and the carbon filter 113 is provided with a sampler valve 114 and a dust sensor s connected to the sampler valve 114 and the tubule 116. Therefore, the degree of filtering in the HEPA filter 112 can be seen as described above. In addition, a dust collecting box 117 is installed below the dust collecting device 110 to collect dust falling from the bag filter 111. The third filtered air is circulated back into the workplace along the duct (d) connected to the dust collector (110).

On the other hand, in the conventional dust collector, since the bag filter, the hepa filter and the carbon filter are connected to each other in one device, the air introduced into the dust collector must pass through all the filters. In other words, even if secondary and tertiary filtration are unnecessary, all filters installed by air passing through the dust collector should be used. Since these filters are mostly consumables, they have to be replaced after a certain period of time. Moreover, hepa filter and carbon filter which filter fine dust or gas are more expensive than bag filter or general filter, which increases the operating cost of dust collection system.

In addition, the conventional dust collecting system is a structure in which the air filtered through the dust collecting apparatus is circulated inwards, and is used in a workplace that requires high cleanliness. Such a dust collecting system needs to be installed so that the workplace can be completely enclosed, and thus, a high cost is required to install and operate the dust collecting system. Therefore, in places where high cleanliness is not required, such as general SMEs or automobile manufacturing plants, there is a problem that it is difficult to apply the dust collection system installation and operation costs are expensive.

In addition, the dust collection system as described above circulates all the filtered air back into the workplace, so that the temperature of the room is kept almost constant. Therefore, when the air temperature inside the workplace is high or low, such as summer or winter, there is a problem in that the temperature of the workplace air must be adjusted separately using an air conditioner or a heating device.

Accordingly, the present invention is to solve the problems as described above, to install a dust sensor and a gas sensor to determine the state of the air in the workplace dust collection system that can select the stage of filtration according to the state of the air in the workplace The purpose is to provide.

In addition, an object of the present invention is to provide a dust collection system that can be easily designed and applied in a workplace that does not require high cleanliness.

In addition, the purpose is to increase the work efficiency of the worker by controlling the temperature in the workplace by circulating the air indoors or discharged outside the workplace according to the temperature of the workplace air.

In order to achieve the above object, the present invention provides a dust collection control system having a first filter and a second filter separately for purifying air in a workplace equipped with a contamination sensor and equipped with an air suction port and an air supply port. The first filter part and the second filter part may be sequentially disposed on the main duct installed by connecting the air suction port and the air supply port, and may isolate the second filter part at the front and rear ends of the second filter part. The first damper and the second damper are installed so that the first damper and the second damper on the main duct are connected to a bypass duct having a third damper so that the flow path is connected to the first filtration part. Bypassing from the downstream upstream to the air supply port, and if the pollution value measured by the pollution sensor is less than the pollution value set value, the first damper and the second damper is closed and the third And opening the buffer, contamination value provides a dust control system comprising the control unit for controlling when to close the opening, and a third damper the first damper and the second damper exceeds the value contamination tongue.

In addition, it is preferable that the first filter part is made of a bag filter, and the second filter part is made of a hepa / carbon filter.

In addition, the contamination sensor is a dust sensor or a gas sensor, and the pollution value is preferably a dust concentration or a gas concentration.

In addition, the workplace is further provided with a temperature sensor, the branch duct having a fourth damper in front of the air supply port is connected to be exhausted to the outside, the fifth damper downstream of the branch point of the branch duct The control unit may include controlling the fourth damper to be opened and the fifth damper to be closed when the temperature measured by the temperature sensor exceeds a temperature set value.

In addition, the front and rear ends of the second filtration unit is connected to both inner sides of the first damper and the second damper to install a differential pressure gauge and a wheel-motor for driving a blower in the first filtration unit. If the pressure by the differential pressure gauge exceeds the set value, the wheel-motor is decelerated, and if it is less than the set value, it is preferable to control to accelerate the wheel-motor.

Hereinafter, with reference to the accompanying drawings will be described in detail with respect to the present invention.

3 shows a state in which a dust collecting control system according to the present invention is installed in a workplace. As shown in the drawing, the dust collecting control system 1 according to the present invention includes a sensor unit 10 for detecting dust, gas, and temperature, a hood H, and a duct forming a flow path through which internal air flows in the workplace. 30, a damper (D) installed in the duct (30) to open and close the passage, a dust collecting part (20) for filtering dust and gas contained in the workplace air, and an output signal from the sensor (10). It is comprised by the control part C which controls the dust-collecting part 20, the damper D, and the fan F. As shown in FIG.

The sensor unit 10 is a pollution sensor (11, 12) for detecting contaminants such as dust and gas (odor) contained in the air inside the workplace (wherein the pollution sensor is a dust sensor 11 or a gas sensor 12) And temperature sensors 13 and 14 for measuring the temperature inside and outside the workplace.

The dust sensor 11 generally uses the principle of an optical sensor. Here, the optical sensor uses the principle of measuring by comparing the amount of light irradiated from the light emitting unit and the amount of light reaching the light receiving unit. Therefore, the dust sensor 11 irradiates light in the air spread in the workplace to measure the change in the amount of light irradiated from the light emitting unit and the amount of light reaching the light receiving unit. If a large amount of particles such as dust is distributed in the air, the light irradiated from the light emitting unit receives the resistance of the particles, thereby reducing the amount of light reaching the light receiving unit. The dust sensor 11 derives a detection value by measuring a change amount of light received.

Gas sensor 12 is generally used a semiconductor gas sensor. The principle of the semiconductor gas sensor is to measure the concentration of gas by measuring the resistance change of the metal oxide generated by gas adsorption using a sensing electrode formed in the sensing unit.

The temperature sensors 13 and 14 have the highest accuracy among the existing temperature sensors of the platinum resistance temperature sensors 13 and 14, and are used as standard temperature sensors in the -260 to 630 ° C region. This uses the principle that the resistance of platinum changes with temperature. These temperature sensors 13 and 14 are installed inside and outside the workplace, respectively, to measure the change in temperature.

The sensors 11, 12, 13, and 14 are installed inside and outside the workplace to transmit respective detection values to the controller C through output signals. Sensors 11, 12, and 13 installed in the workplace may be installed in many places, it is preferable to be disposed close to the workbench generating dust or gas.

The hood (H) is installed on the workbench upper inside the workplace to suck in air inside the workplace. In general, a hood (H) suitable for the size of the workplace is installed, but when the workbench is distributed in several places in the work place, it may be arranged above each workbench to efficiently suck the air in the work place.

The duct 30 is installed to allow air sucked from the hood H to be discharged to the outside of the workplace through the dust collector 20 or circulated into the workplace. In the dust collecting control system 1, the main duct 31 connecting the air inlet port In and the air supply port Out formed on the ceiling of the workplace, and the bypass duct connecting the main duct 31 to bypass the main duct 31. And a branch duct 33 branched from the main duct 31 and installed out of the work place. The configuration of the duct 30 will be described with the damper D and the dust collecting part 20 in FIG. 4.

4 is a diagram illustrating a connection relationship between the dust collectors of the present invention.

As described above, the duct 30 includes a main duct 31, a bypass duct 32, and a branch duct 33.

The main duct 31 is connected to the hood (H) from the air inlet (In) formed in the ceiling of the workplace from the air supply port (Out) formed elsewhere in the ceiling of the workplace. In the main duct 31 at the point where the hood (H) is connected, the suction fan (F1) is installed to form a flow of air in the workplace. Therefore, when the suction fan F1 is operated, the air flow around the hood H is formed inside the main duct 31, and the air in the workplace is sucked into the hood H so that the air flows through the main duct 31. Will move.

Air moving along the main duct 31 flows into the dust collecting part 20 installed on the flow path of the main duct 31.

The dust collecting unit 20 is a device for filtering dust and gas contained in sucked air, and is composed of a first filtering unit 21 and a second filtering unit 25. The first filter unit 21 filters the dust contained in the air, the second filter unit 25 filters the fine particles of dust or gas that can not be filtered by the first filter unit 21. In the present embodiment, the bag filter 21 is used for the first filter part 21, and the hepa filter 25 and the carbon filter 25 (hereinafter, referred to as 'hepa / carbon filter') in the second filter part 25. It is explained by using).

The bag filter 21 is a filter dust collector in which a plurality of nonwoven fabric cloths are arranged side by side, and a blower (not shown) driven by a wheel-motor 23 is installed at an upper portion of the filter cloth. The air sucked into the bag filter 21 passes through a plurality of these filter cloths, and contaminants such as dust contained in the air are filtered out by the fine mesh of the filter cloth. In general, the bag filter 21 can filter to particles of about 1 μm. Therefore, in the workplace internal air delivered from the main duct 31, dust of relatively large particles is primarily filtered in the bag filter 21. Thereafter, the air filtered by the bag filter 21 flows through the main duct 31 connected to the bag filter 21 by a blower (not shown) installed on the top of the bag filter 21. The three-phase inverter 22 is installed inside the bag filter 21 to change the voltage and frequency and supply the wheel-motor 23 to accelerate or decelerate the speed of the wheel-motor 23. The control unit C controls the three-phase inverter 22 by the value detected from the differential pressure gauge 15 to be described below on the basis of the differential pressure set value.

The HEPA filter 25 is made of artificial fibers and generally filters particles of about 0.3 μm to about 99.97%. Since particles of this size include fine dust having an odor, the particles of the fine dust that are not filtered in the bag filter 21 may be filtered. Therefore, the air filtered in the bag filter 21 is filtered once more in the HEPA filter 25 to be filtered to finer dusts.

On the other hand, the carbon filter 25 is comprised from activated carbon with strong adsorption. Activated charcoal has very fine pores than other materials, so it adsorbs and filters fine particles such as gas or smoke, which are difficult to filter in the bag filter 21 and the HEPA filter 25. The carbon filter 25 is disposed in parallel with the HEPA filter 25 to filter dust and gas.

In the present invention, an embodiment in which the bag filter 21 and the hepa / carbon filters 25 and 25 are used in the first and second filtration units 21 and 25 as described above is not limited to the above-described method. Various dust collectors having the same effect can be used.

The first and second filtration units 21 and 25 are sequentially installed on the flow path of the main duct 31. At this time, the main duct 31 is provided with a first damper (D1) and a second damper (D2) which are located before and after the second filtration unit 25 to open and close the passage, respectively. In addition, a bypass duct 32 having a third damper D3 is connected between both outer points on the main duct 31 on which the first damper D1 and the second damper D2 are installed. The bypass duct 32 is connected to the main duct 31 located at the rear end of the second damper D2 from the downstream of the first filtration unit 21. Therefore, when the first and second dampers D1 and D2 are closed and the third damper D3 is open, the air filtered by the first filter part 21 is bypassed without passing through the second filter part 25. It can be discharged by -pass).

Here, the differential pressure gauge 15 is connected to both inner points of the first damper D1 and the second damper D2 of the main duct 31. The differential pressure gauge 15 measures the difference in pressure formed across the second filtration part 25.

Accordingly, the differential pressure gauge 15 measures the differential pressures of the two points and transmits the differential pressures to the control unit C so that the three-phase inverter 22 is controlled to maintain an appropriate rotational speed of the wheel-motor compared with the differential pressure set value.

The branch duct 33 is connected to the outside of the workplace upstream of the air supply port Out of the main duct 31 to which the bypass duct 32 is connected. The fourth damper D4 and the discharge fan F2 are provided in the branch duct 33 to block the passage. On the other hand, the fifth damper (D5) for opening and closing the passage of the main duct 31 is provided at the front end of the air supply port (Out). Therefore, the air filtered and discharged from the first filter part 21 or the second filter part 25 may be discharged to the outside or circulated into the workplace by controlling the opening and closing of the fourth and fifth dampers D4 and D5. .

5 shows an operational connection diagram of the controller C according to the present invention. The controller C receives the output signals from the sensors 11, 12, 13, and 14, as shown in the figure, and controls the dust collecting unit 20, the damper D, the fan F, and the inverter 22.

The dust sensor 11 and the gas sensor 12 and the temperature sensor 13 and 14 installed inside the workplace and the temperature sensors 13 and 14 installed outside the workplace transmit respective detected values to the control unit C. . At this time, the control unit C controls the dust collecting unit 20, the damper (D) and the fan (F) according to the preset values of each sensor. Here, the setting values of each sensor can be changed according to the user's environment. That is, it is possible to set based on the cleanliness in the workplace and the temperature in the workplace required for each workplace. Table 1 below shows a state in which the control unit C controls the damper when the values detected by the dust sensor 11, the gas sensor 12, and the temperature sensors 13 and 14 exceed the respective set values. .

Condition D1 D2 D3 D4 D5 Below temperature set point Dust Excess off off on off on Gas excess on on off off on Temperature set value exceeded Dust Excess off off on on off Gas excess on on off on off

TABLE 1

"On" shown in Table-1 represents the opening of the damper, and "off" represents the closing of the damper. As shown in Table 1 above, when the value detected from the temperature sensors 13 and 14 exceeds the temperature set value, the fourth damper D4 is opened and the fifth damper D5 is closed. On the contrary, when the value detected from the temperature sensors 13 and 14 is less than the temperature set value, the fifth damper D5 is opened and the fourth damper D4 is opened. This is to maintain the temperature by releasing the internal air to the outside when the temperature inside the workplace is higher than the set temperature and dropping the temperature inside the workplace or by circulating the internal air back into the workplace when the temperature is lower than the set temperature. . Accordingly, the controller C controls the fourth and fifth dampers D4 and D5 by comparing the values detected from the temperature sensors 13 and 14 with the temperature set values. At this time, when the air is discharged to the outside of the workplace, the control unit (C) operates the discharge fan (F2) located behind the fourth damper (D4). When the exhaust fan F2 is operated, the air flow in the branch duct 33 and the main duct 31 is formed to face the outside, and clean air filtered and discharged from the dust collector 20 is discharged to the outside along the flow of air. do. When the air discharged to the outside is circulated back to the inside, the fourth damper D4 is closed by the controller C, the fifth damper D5 is opened, and the discharge fan F2 is stopped. .

On the other hand, when the value detected from the dust sensor 11 and the gas sensor 12 exceeds each set value, the 1st, 2nd, 3rd dampers D1, D2, D3 are controlled from the control part C. As shown in FIG. As described above, when only the value detected from the dust sensor 11 exceeds the dust concentration setting value, the control unit C closes the first and second dampers D1 and D2 and opens the third damper D3. do. On the contrary, when the value detected from the gas sensor 12 exceeds the gas concentration setting value, the first and second dampers D1 and D2 are controlled by the control unit C regardless of whether the dust detection value is above or below the dust concentration setting value. ) Is opened and the third damper D3 is closed. This has the effect of protecting the filter of the second filtration unit 25 by closing the first and second dampers D1 and D2 when the value detected from the gas sensor 12 does not exceed the gas concentration setting value.

When the values detected by the dust sensor 11 and the gas sensor 12 exceed the respective set values, the controller C controls the damper D under the above conditions and then operates the suction fan F1. When the suction fan F1 is operated, air in the workplace is filtered out of the dust collecting part 20 through the flow path of the main duct 31 by the suction fan F1. At this time, when the values detected from the dust sensor 11 and the gas sensor 12 all fall below each set value, the suction fan F1 and the first and second filter parts 21 and 25 which are operated are supplied to the controller C. Can be stopped.

In addition, when the power of the dust collecting control system 1 is turned off, the damper D is generally maintained before the power is turned off, but before the power is turned off, the first and second dampers D1 and D2 are closed and the third damper ( D3) is preferably kept open. This is because the second filtration part 25 is closed by the dampers D1 and D2, and thus air is not introduced to protect the filter.

The controller C controls the inverter 22 installed in the first filtration unit 21.

The inverter 22 receives the detected value from the differential pressure gauge 15. At this time, the control value of the wheel-motor 23 according to the differential pressure set value is shown in Table-2 below. When the transmitted differential pressure detection value exceeds the differential pressure set value, the three-phase inverter 22 is controlled to reduce the speed of the wheel-motor 23 connected to the blower (not shown). On the other hand, when the transmitted differential pressure detection value is less than the differential pressure set value, the differential pressure set value in the main duct 31 is accelerated by controlling the three-phase inverter 22 to accelerate the speed of the wheel-motor 23 connected to the blower (not shown). To maintain it. When the differential pressure in the main duct 31 is maintained in this way, the air flows smoothly, thereby preventing the filtration from being properly performed or the main duct 31 being distorted.

Differential pressure measurement Wheel-motor control Differential pressure setting value exceeded deceleration Below differential pressure setting Acceleration

TABLE 2

6 is a flowchart illustrating a process of setting an operating state of the dust collecting control system according to the temperature setting of the present invention.

As in the figure, the temperature inside and outside the workplace is detected from the temperature sensors 13 and 14. At this time, when the value detected from the temperature sensor (13, 14) is less than the temperature set value, since the internal air is filtered through the main duct 31, the structure is circulated back into the workplace. The fourth damper D4 is opened and the fifth damper D5 is closed. Thereafter, the values detected from the dust sensor 11 and the gas sensor 12 are transmitted to the control unit C, and the control unit C compares the values with the respective set values. If the detection value of the dust and gas is less than each set value, the sensors 11 and 12 measure whether the dust and the gas are generated continuously without any other operation of the other devices. On the other hand, when the values detected from the dust sensor 11 and the gas sensor 12 exceed the respective set values, the suction fan F1 and the dust collector 20 are operated from the controller C.

When the value detected from the temperature sensors 13 and 14 exceeds the temperature set value, since the internal air is filtered and then discharged to the outside through the branch duct 33, the control unit C is the fourth damper. D4 is closed and the fifth damper D5 is opened. Then, the dust and gas contained in the air from the dust sensor 11 and the gas sensor 12 in the same manner as described above is detected. When the detected values of dust and gas are less than each set value, it is continued to measure whether or not dust and gas are generated in the same manner as described above. On the other hand, when the detected values from the dust sensor 11 and the gas sensor 12 exceed the respective set values, the suction fan F1 and the discharge fan F2 are operated from the control unit C, and the dust collecting unit 20 is operated. Is activated.

As described above, according to the present invention, the first filtration unit and the second filtration unit may be separately provided to selectively filter as necessary, thereby having the effect of maximizing the life of the filter. In addition, since it does not require high cleanliness, it is suitable to be installed in a place such as a factory, and has a simple structure, which makes it easy to install even in a state in which a building is already completed.

In addition, since the internal air in the workplace can be filtered and discharged to the outside or circulated back to the inside, there is an effect of improving the working environment and improving the work efficiency of the worker by adjusting the temperature in the workplace.

As described above, according to the present invention, it is possible to selectively filter the filter according to the situation of the air in the workplace, which has the effect of maximizing the life of the filter. In addition, since it does not require high cleanliness, it is easy to install in a factory or a building which has already been constructed.

In addition, there is an effect that can improve the working environment and improve the work efficiency of the operator by controlling the temperature in the workplace through the external discharge and internal circulation of air.

Claims (5)

In the dust collecting control system provided with a pollution sensor and having a first filter unit and a second filter unit for purifying the air in the workplace equipped with an air inlet and an air supply port, The first filter unit and the second filter unit are sequentially disposed on the main duct installed by connecting the air suction port and the air supply port, so as to isolate the second filter unit at the front and rear ends of the second filter unit. Each of the first damper and the second damper is installed, Connecting the outer both points of the first damper and the second damper on the main duct with a bypass duct having a third damper to enable a passage to be bypassed from the downstream of the first filtration part upstream of the air supply port; , If the pollution value measured by the pollution sensor is less than the pollution setting value, the first damper and the second damper are closed and the third damper is opened. If the pollution value exceeds the pollution setting value, the first damper and the second damper are opened and the third damper is opened. And a control unit for controlling the damper to close. The method of claim 1, And said first filter part comprises a bag filter and said second filter part consists of a hepa / carbon filter. The method of claim 1, And said pollution sensor is a dust sensor or a gas sensor, and said pollution value is a dust concentration or a gas concentration. The method according to any one of claims 1 to 3, The workplace is further provided with a temperature sensor, the branch duct having a fourth damper in front of the air supply port is connected to be exhausted to the outside, and the fifth damper downstream of the branch point of the branch duct , And the control unit controls the fourth damper to be opened and the fifth damper to be closed when the temperature measured by the temperature sensor exceeds a temperature set value. The method according to any one of claims 1 to 3, And a wheel-motor for installing a differential pressure gauge connected to the front and rear ends of the second filter portion at both inner sides of the first damper and the second damper, and driving a blower in the first filter portion, wherein the controller is provided with the differential pressure gauge. And if the pressure exceeds the set value, the wheel-motor is decelerated, and if the pressure is less than the set value, the dust collecting control system is controlled to accelerate the wheel-motor.

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