CN1927408A - Indoor air purification method by using medium for blocking off low-temperature plasma generated by discharge - Google Patents

Abstract

The invention discloses a method of room air purification with low temperature plasma generated by dielectric resistance discharging. The harmful gas of air can be wiped off by dielectric resistance discharging plasma which is in magnetic field: the needle plate electrode is the reaction electrode, the dielectric resistance discharging can be realized by inserting a dielectric-slab which is 1mm-5mm in thickness at the side of the plate electrode, the distance of the needle electrode is 6mm-30mm, the nanosecond frontal high-voltage narrow pulse power supply is applied to the two ends of the needle plate electrode, the voltage is 10kv-60kv, the permanent magnet is mounted on the two ends of the electrode; The harmful gas of air can be wiped off by pulse discharging plasma which is in magnetic field. At the base of parallel magnetic field, the harmful gas can be wiped off by the low temperature plasma generated by the nanosecond frontal pulse dielectric resistance discharging in the invention, so the purification efficiency is improved greatly.

Description

The low temperature plasma indoor air purification method that a kind of dielectric barrier discharge produces

Technical field

The invention belongs to field of environment protection, relate to a kind of air purification method, magnetic field is introduced in particularly a kind of employing, and the low temperature plasma indoor air purification method that utilizes nanosecond rise time pulsating medium barrier discharge to produce.

Background technology

Indoor environmental pollution is the global the third-largest air pollution problems inherent after smoke pollution and photochemical pollution, and it all can cause great loss to residents ' health and entire society's economy.In China, the major pollutants of room air comprise particle, oxynitride, oxygen sulfur compound, Hydrocarbon etc.

At present, Cleaning Technology of Indoor Air mainly contains absorption, static, anion, photocatalysis, membrance separation and low temperature plasma etc.Absorption method can be removed most organic pollution, ammonia, sulfide and radgas radon and various abnormal flavour effectively, reaches the effect of regulation and control air quality.As patent CN94119329.2 " a kind of air purifying preparation and air cleaner " proposed, purifier adheres to the porous material and the composite air purifying preparation of active carbon of at least a metal-oxide, trimethylamine to low concentration has extremely strong adsorptivity, and effect can continue long time, but, the VOCs that can react with active carbon and the high boiling Organic substance of macromole etc. should not be used this method; Simultaneously, product will cause secondary pollution, and be difficult to reuse once more.Cottrell process can be removed airborne particulate matter and dust etc., but can not effectively remove the harmful gas in the room air.Anion technology can reach sterilization and the purpose of sterilizing, as patent " a kind of anion generator that efficiently, easily spreads ", the patent No.: 03114683.X proposes to produce the high voltage electric field ionized air by the sheet type piezoelectric ceramic transformator, thereby produce a large amount of anion fine-purification air, but this method makes dust easily be adsorbed on wallpaper and glass etc. and locates, and can not clear out of indoor.Photocatalysis technology energy degradating chloro thing, aldehydes, ketone, alcohols, aromatic compound and other inorganic harmful gas CO, NOx etc., as patent " photolytic air cleaning ventilation device ", the patent No.: CN200410012678.8, the employing nano-photocatalyst material is a photocatalyst, and optical fiber is carrier, has the purification efficiency height, advantages such as it is wide to clear the pollution off, the catalyst micropore is caused catalysqt deactivation by obstruction such as dust and particulate matter easily simultaneously.Lower temperature plasma technology is applied to pollute control has become an emerging cross discipline; very active at the applied research in this field both at home and abroad at present; it can remove low concentration volatile organic matter and microorganism in the air; simultaneously can remove inorganic gas such as nitrogen oxide and sulfur dioxide; as patent " a kind of light fixture " with the plasma air purification device; the patent No.: CN200410016646.5; proposition purifies air by shelf depreciation generation non-equilibrium plasma takes place between needle plate electrode; light fixture and plasma air purifying device are combined; simple in structure; easy for installation; has illumination; multiple function such as air cleaning; but still exist discharge instability; shortcomings such as purification efficiency is low; " introduce the indoor air purification method in magnetic field " as patent; the patent No.: CN200410073573.3; disclose a kind of employing and introduced magnetic field; microsecond level high-voltage pulse corona discharge produces low temperature plasma and purifies air; it is low that this method has a cost; volume is little; purification efficiency is than advantages such as height; simultaneously owing to adopt microsecond level high-voltage pulse corona discharge; discharge is stable inadequately; capacity usage ratio is not high, draws nanosecond pulse forward position dielectric barrier discharge after further study and can obtain higher purification efficiency.

Summary of the invention

The weak point of the indoor air cleaner of above-mentioned prior art is that efficient awaits further raising, along with improving constantly of people's living standard, people are more and more higher to the requirement of surrounding air quality, along with being growing more intense of global energy competition, it is more and more important that energy savings becomes, improve purification efficiency, energy savings is a main starting point of the present invention.Therefore, the objective of the invention is to, provide a kind of employing to introduce magnetic field, and the low temperature plasma indoor air purification method that utilizes nanosecond rise time pulsating medium barrier discharge to produce.

In order to realize above-mentioned task, the present invention adopts following technical solution: the low temperature plasma indoor air purification method that a kind of dielectric barrier discharge produces, it is characterized in that, and comprise the steps:

1) the discharge of plasma in low temperature electrode is pin-plate electrode, be fixed with and have 5 discharging acusectors on the high-pressure stage of spray point, and 6 of every rows, needle gage is 20mm, and every pin 20mm is long, and the high-pressure stage of plasma discharge electrode and the distance between the earthing pole are 6mm～30mm;

2) discharge of plasma in low temperature electrode two ends apply the high voltage narrow pulse power supply, and pulse voltage is amplitude 10kV～60kV, and the rise time is 5ns～200ns, and pulse frequency is 50Hz～500Hz;

3) in the plate electrode side of discharge of plasma in low temperature electrode, realize dielectric barrier discharge thereby insert a dielectric-slab, dielectric-slab thickness is 1mm～5mm, and dielectric-slab is a glass, epoxy resin, politef or AL ₂O ₃

4) at discharge of plasma in low temperature electrode two ends permanent magnet is set, permanent magnet produces the magnetic induction about 10mT～50mT, and the direction in magnetic field is consistent with the direction of an electric field that is applied.

In the present invention, introduce magnetic field, adopt the dielectric barrier discharge of nanosecond rise time pulse to produce harmful gas in the low temperature plasma removal air simultaneously, its purification efficiency has improved 3～4 times than the microsecond level forward position corona discharge pulse of introducing magnetic field.

Description of drawings

Fig. 1 is a plasma discharge electrode sketch map;

Fig. 2 is the movement locus of electronics in constant electromagnetic field of different initial velocity;

Fig. 3 is that the dielectric impedance Board position is to removing the influence of sulfur dioxide;

Fig. 4 is the magnetic field size is removed efficient to sulfur dioxide influence;

Fig. 5 is the influence of pulse rise time sulfur dioxide being removed efficient of pulse voltage.

The embodiment that provides below in conjunction with accompanying drawing and inventor is described in further detail the present invention.

The specific embodiment

Accompanying drawing is specific embodiments of the invention;

(1) utilize the pulsed discharge plasma of introducing magnetic field to remove airborne harmful gas, this principle is mentioned in patent CN200410073573.3.

With reference to shown in Figure 1, label 3 among the figure is the earthing pole of plasma discharge electrode, 2 is the high-pressure stage of plasma discharge electrode, 4 is the plasma discharge pin, sparking electrode is pin-plate electrode, form reactor size by pin battle array and flat board: long 200mm, wide 150mm, high adjustable in the 30mm-100mm scope, spray point is positioned at middle position, the high 20mm of spray point, and pin spacing is from being 20mm, totally 5 arrange (the movable extraction of every pricking with needle), 6 pins of every row, two battery lead plates connect the two ends of power supply up and down, and two ends, the left and right sides are the air inlet and the gas outlet of air.Be coated with on the flat board the thick glass medium of one deck 3mm (can change the kind and the thickness of medium during test, as epoxy resin, politef or AL ₂O ₃All can), test in order to make power supply and electrode better matching, prevents from not have the energy of consumption to vibrate between power supply and sparking electrode when carrying out, in the parallel connection of the two ends of electrode the resistance of a 2M Ω.Apply the high voltage narrow pulse power supply at discharge of plasma in low temperature electrode two ends, pulse voltage is amplitude 10kV-60kV, and the rise time is 5ns～200ns, and pulse frequency is 50Hz～500Hz.At discharge of plasma in low temperature electrode two ends permanent magnet 1 is set, the magnetic induction that permanent magnet 1 produces about 10mT～50mT, and the direction in magnetic field is consistent with the direction of an electric field that is applied.

Will form the pulsating medium barrier discharge under the precipitous high voltage narrow pulse effect of rising edge, certain space produces low temperature plasma around sparking electrode.On the one hand, in producing the process of low temperature plasma, the instantaneous high-energy that high-frequency discharge produces is enough to open the chemical bond of some harmful gas molecule, makes it resolve into simple substance atom or harmless molecule.On the other hand, free groups such as N, the O of a large amount of strong oxidizing properties of meeting generation, OH in the low temperature plasma, the chemical reaction of its generation is as follows:

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

Thereby these free groups and harmful gas generation chemical reaction are eliminated harmful gas.

Magnetic field is incorporated in the low temperature plasma purifying harmful gas, and its influence mainly contains two aspects: at first, at the area of space near spray point, because electric field intensity is very big, electronics just can obtain bigger energy on very short distance.When electron energy reaches excitation threshold, begin to take place inelastic collision.

With reference to shown in Figure 2, among the figure, vertical coordinate is represented electronics motion distance in vertical direction, and abscissa is represented electronics motion distance in the horizontal direction, wherein $\mathrm{\Ω}=\frac{\mathrm{eB}}{m},$ $\mathrm{\η}=\frac{e}{m},$ Among the figure $r=\frac{\mathrm{\ηE}}{{\mathrm{\Ω}}^2},$ M is an electron mass, and e is an electron charge, and B is a magnetic induction, and E is an electric field intensity, v ₀Be the electronics initial velocity.The electronics motion of in electromagnetic field, spinning, distance in the axial direction increases, and the holdup time is elongated.Therefore, spatial metastable state collision this moment, excited state collision, ionizing collision frequency are all many soon than no magnetic field, thereby will produce the more free group of removal harmful gas in the unit interval, make that denitrification efficiency is very big must improve.

In addition, will be when harmful gas enters low temperature plasma by the charged charged particle that becomes, under the combined effect of electric field force and magnetic field force, the movement locus of charge particle also is complicated eddy flow track, its radius of gyration r is

$r=\frac{m{v}_{\⊥}}{\mathrm{qB}}---\left(11\right)$

In the formula: v _⊥For charged particle perpendicular to the speed on the magnetic direction;

M is the quality of charged particle;

Q is the charged particle electric weight;

B is the magnetic field size.

This swirling motion of harmful gas molecule makes them elongated in the time of plasma internal stops, thereby has prolonged the time that contacts with free group, makes harmful gas fully to be purified.Therefore as long as introduce suitable magnetic field, removal efficient is improved.

Fig. 4 has described the influence that the magnetic field size is removed efficient to sulfur dioxide, and abscissa is for removing time T (min), and vertical coordinate is that sulfur dioxide is removed efficiency eta (%).The loading pulse voltage peak is 24kV during test, and frequency is 100Hz, has added the stationary magnetic field between sparking electrode, and the direction in magnetic field is vertical with direction of an electric field, and magnetic field B 0＜B1＜B2＜B3, sulfur dioxide initial concentration are 20mg/m ³, pin-distance between plates 4 is 1cm, the number of spray point is 5 pricking with needle.By the result of the test of Fig. 4 as can be seen, under the identical situation of other conditions, sulfur dioxide is removed efficient and is improved along with the increase in magnetic field.(2) utilize dielectric barrier discharge to replace corona discharge generation low temperature plasma and remove airborne harmful gas:

The low temperature plasma that corona discharge produces mainly is distributed in the strong electric field region in the severe non-uniform electric field, and a little less than the discharge, the efficient that produces plasma and active particle is low, causes denitrification efficiency not high.

Dielectric barrier discharge is to have dielectric to insert a kind of gas discharge of discharge space, and this discharge belongs to the thermal nonequilibrium discharge under the hyperbar.Medium can cover on the electrode or hang in the discharge space, and like this, when applying sufficiently high alternating voltage on sparking electrode, interelectrode gas is even also can be breakdown under hyperbar very and form so-called dielectric barrier discharge.That this discharge shows as is very even, disperse and stablize, and seems to be low pressure glow discharge down, but in fact it is to be made of trickle fast pulse discharge channels in a large number.

With respect to corona discharge, dielectric barrier discharge is more stable, and discharge volume is big, the electron density height, and capacity usage ratio height, discharge process are easy to advantages such as control, help the raising of purification efficiency.

Fig. 3 has described the influence of the position of dielectric impedance plate to sulfur dioxide removal efficient, and abscissa is removal time t (min), and vertical coordinate is sulfur dioxide clearance η (%).As seen from Figure 3, under the identical situation of other conditions, the removal efficient of sulfur dioxide improves with the increase of dielectric impedance plate and pin battle array electrode distance; When the dielectric impedance plate covered on the minus plate, the removal of sulfur dioxide was most effective.(3) adopt the nanosecond rise time high-voltage pulse power source to replace the high-voltage pulse power source power supply of microsecond level forward position:

In order to realize the nanosecond rise time pulsating medium barrier discharge under the normal temperature and pressure, adopted the nanosecond rise time high-voltage pulse power source that can produce continuous high voltage narrow pulse, its important technological parameters is as follows:

Power supply: exchange single-phase 220V ± 10%, 50 ± 1Hz

Rated output power: 120VA

Peak impulse voltage: 10kV～60kV is adjustable continuously in output

Pulse polarity: plus or minus (realizing) by changing positive and negative high-voltage D.C. generator

Pulse width :≤500ns

Pulse rising front :≤100ns

Pulse recurrence frequency: 0～200Hz is adjustable continuously

Load: pin-plate dielectric impedance reaction electrode

Fig. 4 has described the influence of the pulse rise time of pulse voltage to sulfur dioxide removal efficient, and abscissa is for removing time T (min), and vertical coordinate is that sulfur dioxide is removed efficiency eta (%).To be respectively amplitude be 18kV to loading pulse voltage during test, the rising edge time is 10 μ s, and frequency is that the microsecond level forward position pulse power and the amplitude of 100Hz is 18kV, and the rising edge time is 50ns, frequency is the nanosecond rise time pulse power of 100Hz, and the sulfur dioxide initial concentration is 20mg/m ³, pin-distance between plates is 1cm, the number of spray point is 5 pricking with needle.By the result of the test of Fig. 4 as can be seen, the removal efficient of rising edge of a pulse time to sulfur dioxide has very big influence, the removal efficient of the nanosecond rise time pulse power is apparently higher than the microsecond level forward position pulse power, this is because short more when the pulse rise time of supply voltage, the energy of instantaneous injection reaction electrode is just high more, can in sparking electrode, set up highfield fast, the pulsed discharge instantaneous power density that forms is very big, can produce more high energy electron and free group, simultaneously because the power supply pulse is narrow, ion does not almost obtain to quicken, simultaneous temperature does not have obvious rising, and electronics obtains bigger energy in the relatively shorter time, forms the carrying out that low temperature plasma helps chemical reaction like this, therefore adopts the nanosecond rise time pulse power to remove sulfur dioxide.

Simultaneously, removing efficient more as can be seen with adopting the corona discharge plasma sulfur dioxide under the pulse power effect of microsecond level forward position before, adopt the dielectric barrier discharge form can greatly improve sulfur dioxide and remove efficient, is 3～4 times approximately.

Claims (1)

1. the low temperature plasma indoor air purification method that dielectric barrier discharge produces is characterized in that, comprises the steps:

1) adopts by pin battle array and the dull and stereotyped discharge of plasma in low temperature electrode of forming, be fixed with and have 5 discharging acusectors on the high-pressure stage of spray point, 6 of every rows, pin spacing is 20mm, every pin 20mm is long, and the high-pressure stage of plasma discharge electrode and the distance between the earthing pole are 6mm～30mm;

2) discharge of plasma in low temperature electrode two ends apply the high voltage narrow pulse power supply, and pulse voltage amplitude is 10kV～60kV, and the rise time is 5ns～200ns, and pulse frequency is 50Hz～500Hz;

3) in the plate electrode side of discharge of plasma in low temperature electrode, realize dielectric barrier discharge thereby insert a dielectric-slab, dielectric-slab thickness is 1mm～5mm, and dielectric-slab is a glass, epoxy resin, politef or AL ₂O ₃

4) at discharge of plasma in low temperature electrode two ends permanent magnet is set, permanent magnet produces the magnetic induction of 10mT～50mT, and the direction in magnetic field is consistent with the direction of an electric field that is applied.

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