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Clean room technology teaching notes (3) - air purification equipment and its application
Filtration mechanism of the filter on the particles: mechanical separation, electric power separation, washing separation, filtration separation; air cleaning technology, mainly using filtration separation, followed by electric power separation.
Filter basic filtration process: stable phase: does not change with time, meaningful in clean technology;
Unstable phase: changes over time, decisive for general industrial filters
Filter filters five effects: (1) interception effect (2) inertial effect (3) diffusion effect (4) gravity effect (5) electrostatic effect (class notes)
Air purification equipment air purification equipment
Factors affecting filter efficiency: (PPT)
a. particle size, type, shape b, fiber thickness, filling rate, cross-sectional shape c, filtration wind speed d, air flow temperature, humidity, pressure e, dust holding capacity
Air filter performance indicators: P48-52
Filtration efficiency: It is the most important indicator of the air filter. It is a parameter to measure the ability of the air filter to collect dust particles. It refers to the difference between the dust concentration of the air before and after the filter and the dust concentration of the air before the filter under the rated air volume. Percentage of ratio = 100% = (1 - 1) 100%; total efficiency of two filters in series: =1-(1-)(1-), n filters used in series = 1 - (1- ) (1 - )…(1- ). The permeability can also be used to evaluate the quality of the filter. The penetration rate is the percentage of the ratio of the dust concentration of the filtered air to the dust concentration of the air before filtration, P = / 100% = 1 -, which can visually represent the filter. Before and after the air dust content, use him to evaluate and compare the performance of the high-efficiency filter, which is more intuitive.
Filter face speed and speed: The filter face speed refers to the air flow velocity (m/s) passed through the cross section of the filter, u=Q/(F 3600), Q——the air volume passing through the filter ( /h F; the windward cross-sectional area of ​​the filter ( ); the surface wind speed is a performance index reflecting the passing capacity and installation area of ​​the filter; the filtration speed refers to the air flow rate passing through the filtering area, reflecting the passing ability of the material (filtering performance)
Filter resistance: one is the resistance of the filter material, and the other is the resistance of the filter structure.
Dust holding capacity of the filter: The dust holding capacity of the filter refers to the maximum allowable dust accumulation of the filter, which is the quality of the filter containing the specific test dust under the test conditions of the specific conditions; the domestic test dust has specified the floating soil of the Loess Plateau; The International Organization for Standardization has designated "AC Fine Ash" as the test dust
When two filters of the same filter material are connected in series, is the filter series efficiency calculation formula applicable? Why?
Applicable, because the particle size of the dust treated before and after the two filters are connected in series is different, the filtration efficiency is different.
Air filter classification: P52-54
(1) Classified by filtration efficiency:
1) Coarse air filter: mainly used for fresh air filtration, sedimentation particles and various foreign bodies; the filter object is generally 5μm or more; the efficiency of the coarse filter is 5μm; the oil immersed filter is strictly prohibited. .
2) Medium efficiency filter: As the final filter of the general air conditioning system and the pre-filter for purifying the high efficiency filter in the air conditioning system; the filtering object is generally 1~10μm particles; the efficiency is based on filtering 1μm.
3) High-efficiency filter: It can be used as the end filter of the system with general purification degree. It can also be used as the intermediate filter to protect the high-efficiency filter; it is mainly used to trap suspended particles of 1~5μm; the efficiency is also filtered by 1μm. Prevail.
4) Sub-high efficiency filter: It can be used as a clean room end filter; it can also be used as a pre-filter for high-efficiency filter; it can also be used as a final filter for purifying the fresh air of air-conditioning system to improve the quality of fresh air; it is mainly used for intercepting 1μm or less. Particles; efficiency is based on the filtration of 0.5μm particles; must be used under the protection of the primary and intermediate filters.
5) High-efficiency filter: often used as the end filter for three-stage filtration; mainly used to intercept particles below 1μm; efficiency is based on filtering 0.3μm particles; efficiency is based on filtering 0.12μm particles, called ultra-efficient Filter (mainly used to trap particles from 0.1 to 0.3 μm); must be used under the protection of primary and intermediate filters.
(2) Classified according to the purpose of use
a. Filter for fresh air treatment: usually adopts coarse, medium, high and medium efficiency, sub-efficient, etc.
b. Indoor air supply filter: usually sub-efficient, efficient, ultra-efficient or efficient + chemical filter, etc.
c. Exhaust filter: generally used sub-efficient, high efficiency or HEPA+ chemical filter.
d. Filters for clean indoor equipment: generally use high efficiency, ultra high efficiency, HEPA+ chemical filter or ULPA+ chemical filter, etc.
e. Filters for manufacturing equipment (non-standard type): HEPA, ULPA or HEPA+ chemical filters or ULPA+ chemical filters are usually used.
f. Air filter for high pressure piping: usually used for gas transportation with a pressure greater than 0.1 mpa
(3) Classification by filter material
Filter paper filter: one of the most widely used filters; fiber layer filter: usually used as a medium efficiency filter; less foam filter application
Chemical (gas) filter: P55 filter material: activated carbon, ion exchange resin; mainly used in chip factories, nuclear industry, airports and so on. The factors reflecting the adsorption performance of activated carbon are mainly adsorption capacity, residence time, service life and selectivity. It can monitor the change of pollutant concentration before and after the filter, determine the replacement cycle of activated carbon and the service life of the filter, and estimate the filter according to the change of the quality of activated carbon. Service life. Note: When using, the upper and lower ends of the activated carbon filter should be equipped with a high-efficiency air filter. The upper filter prevents dust particles from clogging the activated carbon micropores, and the lower filter can remove the dust from the activated carbon itself.
Test method for air filter efficiency: P55-58
China: oil mist method and sodium flame method; Germany: paraffin oil mist method; Britain: sodium flame method; United States: DOP method.
The test methods for air filters commonly used at home and abroad are:
Quality method: efficiency test of coarse and medium efficiency air filter; principle: the filter is installed in the standard test wind tunnel, and the wind is continuously dusted at the windward end, and the dust quality passing through the filter is measured at intervals, thereby obtaining a filter. The filtration efficiency of the dust quality calculation at this stage.
Colorimetric method: efficiency test of medium efficiency air filter. Principle: sample before and after the filter, dusty air is passed through the filter paper, the contaminated filter paper is placed under the light source, and the transmittance of the filter paper before and after the filter is measured by a photocell colorimeter (photoelectric density meter); Under the conditions of the same composition, size and distribution, the filtration efficiency is calculated by using the relationship between the density and the amount of dust accumulation.
Particle Counter Method: The test of high-efficiency air filter in clean room is widely used in clean air conditioning projects. Principle: When the dusty airflow passes through the strong light illumination area at a small flow rate, when the dust particles in the air to be tested pass sequentially, each dust particle will generate a light scattering to form an optical pulse signal according to the amplitude of the optical pulse signal. The size is proportional to the particle surface size, and the number of particles and brightness are measured by a photomultiplier tube to determine the filtration efficiency. Judging the advantages and disadvantages according to the filtration efficiency of the particle size file: coarse 5 m, medium efficiency 2 m, high medium efficiency 1 m, sub-efficient, high efficiency 0.5 m
DOP method: used for high efficiency; most commonly used in the world; principle: the test dust source is 0.3 m monodisperse phase DOP droplets heated into steam, condensed into tiny droplets under certain conditions, and the excess and too small droplets are removed. Under the 0.3 m particle, the misty DOP enters the air duct, and then the turbidity of the gas sample before and after the filter is measured, thereby judging the dust filtration efficiency of 0.3 m.
Counting scanning method: for high efficiency; principle: measuring instrument is a large flow laser particle counter or condensation tube counter, using the counter to scan the entire outlet surface of the filter, the counter gives the number and particle size of each point of dust.
Oil mist method: Principle: The dust source is oil mist, and the turbidity meter is used to determine the filtration efficiency of the oil mist particles by the turbidity meter.
Sodium Flame Method: Principle: The test dust source is a monodisperse phase sodium chloride salt spray, and the flame brightness is used to determine the salt spray concentration of the air before and after the filter.
Introduction to several commonly used air filters
ZJK-I type automatic winding type herringbone air filter: coarse effect; accumulated dust to a certain extent, the automatic control system is automatically updated.
YB type glass fiber filter: divided into D type and X type
YZG medium efficiency air filter: V-shaped unit, the ratio of the filter material area to the windward surface area of ​​the filter is large.
Tubular high-efficiency air filter: tubular structure, large air volume, low resistance, high dust holding capacity and light weight
GZ type air filter: bag filter, filter bag can be replaced and cleaned.
JKG-2A electrostatic filter: The efficiency of the electrostatic filter is inversely related to the air volume.
Air filter selection:
a. According to the rated air volume; b. Reasonably determine the efficiency of each level of filter c. The final filter is reliable d. The primary filter is easy to maintain. Generally, the rated dust holding capacity is used as the service life of the filter: ; T-filter service life (d); P-filter dust holding capacity (g); N1 - dust concentration of air before filter (mg / ); Q-filter air volume ( / h); t - filter one day working time (h); η - calculated filter weight efficiency (%).
What is the difference between the filter air supply and the fan filter unit?
Filter air supply port: a filter unit composed of a high-efficiency filter and a blower port, without a fan;
Fan filter unit: The filter unit formed by the filter air supply port and the fan are connected together.
(Fan filter unit) What are the similarities and differences between the ducted tuyere unit and the circulating tuyere unit?
The pipeline type is connected with the pipeline, and the fan is used to supplement the system pressure head, and only the high efficiency is arranged, and the coarse and medium are arranged in the system;
The circulating type uses a fan to directly circulate indoor air, and a pre-filter is required.
What is a self-cleaning device and what does it do?
Definition: An air purification device consisting of a fan, a coarse, medium and efficient (sub-efficient) filter and a feed and return air vent.
Function: Local temporary purification of the operating point; set in the vortex area where the clean room is prone to reduce the probability of dust and bacteria retention; can be used as a simple circulation unit for clean environment.
What is the structure of the clean laminar flow hood? Is it the same as the FFU?
There are fans: consisting of pre-filters, fans, high-efficiency air filters and tanks; no fans: consisting of high-efficiency air filters and tanks.
What is the purification unit made up of? What is the difference? What is the difference compared to the self-cleaning unit?
Structure: It consists of pre-filter, fan, high efficiency air filter and upper and lower tank. Role: purify fresh air and return air.
What is the role of the air shower room for single, multi-person cab and channel?
Role: It is a device for personal purification and prevention of polluted air entering the clean area. Single <30 people; multi-person>30 people; channel>80 people.
The role and classification of the transfer window.
Role: Temporarily block the clean air flow to prevent the spread of pollutants. Classification: mechanical, airlock, sterilized, closed and desirable.
The function, performance and position of the residual pressure valve.
Role: maintain a certain indoor static pressure. Performance: adjustable pressure range: 5Pa-40Pa, exhaust air volume: 300-1200m3/h.
Position: usually installed in the lower part of the lower side wall of the clean room, and the height of the return air inlet is flush; the multiple residual pressure valves of the large clean room should face the passageway, the return air wall, etc.;
When the small clean room is only equipped with a residual pressure valve, the valve opening degree is about 15-20° under normal conditions, and the valve opening degree is increased when the positive pressure of the room is increased, and vice versa.
What is the difference between ordinary air conditioning and clean air conditioning?
Ordinary: Use less ventilation to increase the uniformity of indoor temperature and humidity fields as much as possible, and more use airflow organization with large turbulence.
Clean: Supply a sufficient amount of clean air, dilute and replace the pollutants generated indoors, so that the indoor cleanliness is kept within the allowable range.
Clean room technology teaching notes (3) - air purification equipment and its application
Filtration mechanism of the filter on the particles: mechanical separation, electric power separation, washing separation, filtration separation; air cleaning technology, mainly using filtration separation, followed by electric power separation.
Filter basic filtration process: stable phase: does not change with time, meaningful in clean technology;
Unstable phase: changes over time, decisive for general industrial filters
Filter filters five effects: (1) interception effect (2) inertial effect (3) diffusion effect (4) gravity effect (5) electrostatic effect (class notes)
Air purification equipment air purification equipment
Factors affecting filter efficiency: (PPT)
a. particle size, type, shape b, fiber thickness, filling rate, cross-sectional shape c, filtration wind speed d, air flow temperature, humidity, pressure e, dust holding capacity
Air filter performance indicators: P48-52
Filtration efficiency: It is the most important indicator of the air filter. It is a parameter to measure the ability of the air filter to collect dust particles. It refers to the difference between the dust concentration of the air before and after the filter and the dust concentration of the air before the filter under the rated air volume. Percentage of ratio = 100% = (1 - 1) 100%; total efficiency of two filters in series: =1-(1-)(1-), n filters used in series = 1 - (1- ) (1 - )…(1- ). The permeability can also be used to evaluate the quality of the filter. The penetration rate is the percentage of the ratio of the dust concentration of the filtered air to the dust concentration of the air before filtration, P = / 100% = 1 -, which can visually represent the filter. Before and after the air dust content, use him to evaluate and compare the performance of the high-efficiency filter, which is more intuitive.
Filter face speed and speed: The filter face speed refers to the air flow velocity (m/s) passed through the cross section of the filter, u=Q/(F 3600), Q——the air volume passing through the filter ( /h F; the windward cross-sectional area of ​​the filter ( ); the surface wind speed is a performance index reflecting the passing capacity and installation area of ​​the filter; the filtration speed refers to the air flow rate passing through the filtering area, reflecting the passing ability of the material (filtering performance)
Filter resistance: one is the resistance of the filter material, and the other is the resistance of the filter structure.
Dust holding capacity of the filter: The dust holding capacity of the filter refers to the maximum allowable dust accumulation of the filter, which is the quality of the filter containing the specific test dust under the test conditions of the specific conditions; the domestic test dust has specified the floating soil of the Loess Plateau; The International Organization for Standardization has designated "AC Fine Ash" as the test dust
When two filters of the same filter material are connected in series, is the filter series efficiency calculation formula applicable? Why?
Applicable, because the particle size of the dust treated before and after the two filters are connected in series is different, the filtration efficiency is different.
Air filter classification: P52-54
(1) Classified by filtration efficiency:
1) Coarse air filter: mainly used for fresh air filtration, sedimentation particles and various foreign bodies; the filter object is generally 5μm or more; the efficiency of the coarse filter is 5μm; the oil immersed filter is strictly prohibited. .
2) Medium efficiency filter: As the final filter of the general air conditioning system and the pre-filter for purifying the high efficiency filter in the air conditioning system; the filtering object is generally 1~10μm particles; the efficiency is based on filtering 1μm.
3) High-efficiency filter: It can be used as the end filter of the system with general purification degree. It can also be used as the intermediate filter to protect the high-efficiency filter; it is mainly used to trap suspended particles of 1~5μm; the efficiency is also filtered by 1μm. Prevail.
4) Sub-high efficiency filter: It can be used as a clean room end filter; it can also be used as a pre-filter for high-efficiency filter; it can also be used as a final filter for purifying the fresh air of air-conditioning system to improve the quality of fresh air; it is mainly used for intercepting 1μm or less. Particles; efficiency is based on the filtration of 0.5μm particles; must be used under the protection of the primary and intermediate filters.
5) High-efficiency filter: often used as the end filter for three-stage filtration; mainly used to intercept particles below 1μm; efficiency is based on filtering 0.3μm particles; efficiency is based on filtering 0.12μm particles, called ultra-efficient Filter (mainly used to trap particles from 0.1 to 0.3 μm); must be used under the protection of primary and intermediate filters.
(2) Classified according to the purpose of use
a. Filter for fresh air treatment: usually adopts coarse, medium, high and medium efficiency, sub-efficient, etc.
b. Indoor air supply filter: usually sub-efficient, efficient, ultra-efficient or efficient + chemical filter, etc.
c. Exhaust filter: generally used sub-efficient, high efficiency or HEPA+ chemical filter.
d. Filters for clean indoor equipment: generally use high efficiency, ultra high efficiency, HEPA+ chemical filter or ULPA+ chemical filter, etc.
e. Filters for manufacturing equipment (non-standard type): HEPA, ULPA or HEPA+ chemical filters or ULPA+ chemical filters are usually used.
f. Air filter for high pressure piping: usually used for gas transportation with a pressure greater than 0.1 mpa
(3) Classification by filter material
Filter paper filter: one of the most widely used filters; fiber layer filter: usually used as a medium efficiency filter; less foam filter application
Chemical (gas) filter: P55 filter material: activated carbon, ion exchange resin; mainly used in chip factories, nuclear industry, airports and so on. The factors reflecting the adsorption performance of activated carbon are mainly adsorption capacity, residence time, service life and selectivity. It can monitor the change of pollutant concentration before and after the filter, determine the replacement cycle of activated carbon and the service life of the filter, and estimate the filter according to the change of the quality of activated carbon. Service life. Note: When using, the upper and lower ends of the activated carbon filter should be equipped with a high-efficiency air filter. The upper filter prevents dust particles from clogging the activated carbon micropores, and the lower filter can remove the dust from the activated carbon itself.
Test method for air filter efficiency: P55-58
China: oil mist method and sodium flame method; Germany: paraffin oil mist method; Britain: sodium flame method; United States: DOP method.
The test methods for air filters commonly used at home and abroad are:
Quality method: efficiency test of coarse and medium efficiency air filter; principle: the filter is installed in the standard test wind tunnel, and the wind is continuously dusted at the windward end, and the dust quality passing through the filter is measured at intervals, thereby obtaining a filter. The filtration efficiency of the dust quality calculation at this stage.
Colorimetric method: efficiency test of medium efficiency air filter. Principle: sample before and after the filter, dusty air is passed through the filter paper, the contaminated filter paper is placed under the light source, and the transmittance of the filter paper before and after the filter is measured by a photocell colorimeter (photoelectric density meter); Under the conditions of the same composition, size and distribution, the filtration efficiency is calculated by using the relationship between the density and the amount of dust accumulation.
Particle Counter Method: The test of high-efficiency air filter in clean room is widely used in clean air conditioning projects. Principle: When the dusty airflow passes through the strong light illumination area at a small flow rate, when the dust particles in the air to be tested pass sequentially, each dust particle will generate a light scattering to form an optical pulse signal according to the amplitude of the optical pulse signal. The size is proportional to the particle surface size, and the number of particles and brightness are measured by a photomultiplier tube to determine the filtration efficiency. Judging the advantages and disadvantages according to the filtration efficiency of the particle size file: coarse 5 m, medium efficiency 2 m, high medium efficiency 1 m, sub-efficient, high efficiency 0.5 m
DOP method: used for high efficiency; most commonly used in the world; principle: the test dust source is 0.3 m monodisperse phase DOP droplets heated into steam, condensed into tiny droplets under certain conditions, and the excess and too small droplets are removed. Under the 0.3 m particle, the misty DOP enters the air duct, and then the turbidity of the gas sample before and after the filter is measured, thereby judging the dust filtration efficiency of 0.3 m.
Counting scanning method: for high efficiency; principle: measuring instrument is a large flow laser particle counter or condensation tube counter, using the counter to scan the entire outlet surface of the filter, the counter gives the number and particle size of each point of dust.
Oil mist method: Principle: The dust source is oil mist, and the turbidity meter is used to determine the filtration efficiency of the oil mist particles by the turbidity meter.
Sodium Flame Method: Principle: The test dust source is a monodisperse phase sodium chloride salt spray, and the flame brightness is used to determine the salt spray concentration of the air before and after the filter.
Introduction to several commonly used air filters
ZJK-I type automatic winding type herringbone air filter: coarse effect; accumulated dust to a certain extent, the automatic control system is automatically updated.
YB type glass fiber filter: divided into D type and X type
YZG medium efficiency air filter: V-shaped unit, the ratio of the filter material area to the windward surface area of ​​the filter is large.
Tubular high-efficiency air filter: tubular structure, large air volume, low resistance, high dust holding capacity and light weight
GZ type air filter: bag filter, filter bag can be replaced and cleaned.
JKG-2A electrostatic filter: The efficiency of the electrostatic filter is inversely related to the air volume.
Air filter selection:
a. According to the rated air volume; b. Reasonably determine the efficiency of each level of filter c. The final filter is reliable d. The primary filter is easy to maintain. Generally, the rated dust holding capacity is used as the service life of the filter: ; T-filter service life (d); P-filter dust holding capacity (g); N1 - dust concentration of air before filter (mg / ); Q-filter air volume ( / h); t - filter one day working time (h); η - calculated filter weight efficiency (%).
What is the difference between the filter air supply and the fan filter unit?
Filter air supply port: a filter unit composed of a high-efficiency filter and a blower port, without a fan;
Fan filter unit: The filter unit formed by the filter air supply port and the fan are connected together.
(Fan filter unit) What are the similarities and differences between the ducted tuyere unit and the circulating tuyere unit?
The pipeline type is connected with the pipeline, and the fan is used to supplement the system pressure head, and only the high efficiency is arranged, and the coarse and medium are arranged in the system;
The circulating type uses a fan to directly circulate indoor air, and a pre-filter is required.
What is a self-cleaning device and what does it do?
Definition: An air purification device consisting of a fan, a coarse, medium and efficient (sub-efficient) filter and a feed and return air vent.
Function: Local temporary purification of the operating point; set in the vortex area where the clean room is prone to reduce the probability of dust and bacteria retention; can be used as a simple circulation unit for clean environment.
What is the structure of the clean laminar flow hood? Is it the same as the FFU?
There are fans: consisting of pre-filters, fans, high-efficiency air filters and tanks; no fans: consisting of high-efficiency air filters and tanks.
What is the purification unit made up of? What is the difference? What is the difference compared to the self-cleaning unit?
Structure: It consists of pre-filter, fan, high efficiency air filter and upper and lower tank. Role: purify fresh air and return air.
What is the role of the air shower room for single, multi-person cab and channel?
Role: It is a device for personal purification and prevention of polluted air entering the clean area. Single <30 people; multi-person>30 people; channel>80 people.
The role and classification of the transfer window.
Role: Temporarily block the clean air flow to prevent the spread of pollutants. Classification: mechanical, airlock, sterilized, closed and desirable.
The function, performance and position of the residual pressure valve.
Role: maintain a certain indoor static pressure. Performance: adjustable pressure range: 5Pa-40Pa, exhaust air volume: 300-1200m3/h.
Position: usually installed in the lower part of the lower side wall of the clean room, and the height of the return air inlet is flush; the multiple residual pressure valves of the large clean room should face the passageway, the return air wall, etc.;
When the small clean room is only equipped with a residual pressure valve, the valve opening degree is about 15-20° under normal conditions, and the valve opening degree is increased when the positive pressure of the room is increased, and vice versa.
What is the difference between ordinary air conditioning and clean air conditioning?
Ordinary: Use less ventilation to increase the uniformity of indoor temperature and humidity fields as much as possible, and more use airflow organization with large turbulence.
Clean: Supply a sufficient amount of clean air, dilute and replace the pollutants generated indoors, so that the indoor cleanliness is kept within the allowable range.
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