CN1168521C - Apparatus and process for cleaning gas - Google Patents

Abstract

The present invention discloses a gas cleaning treatment device. The present invention comprises a blower which is used for sucking gaseous pollutants, a low-temperature plasma generator, a filter layer and a negative ion generator, wherein the low-temperature plasma generator generates plasma bodies which are used for the low-temperature plasma body evolution processing of the gaseous pollutants sucked by the blower; the filter layer is used for filtering the gas which is purified by the plasma bodies, and is also used for filtering residual harmful gas; the negative ion generator is used for the negative ion processing of the filtered gas to improve the air quality. The present invention has extremely ideal effect of removing harmful gas, and the purifying rate of formaldehyde and H2S reaches 100%. In addition, the bacterial purification rate of the present invention reaches 98.9%, and the sterilization function of the present invention is extremely notable.

Description

Gas purification treatment facility and method

Technical field

The present invention relates to a kind of gas purification treatment facility and method, particularly a kind of gas purification treatment facility and method that adopts the plasma purified treatment.

Background technology

Domestic and international existing purification techniques also rests on the level of Electrostatic Absorption, charcoal absorption and negative aeroionization at present, these The Application of Technology have certain facilitation to improving air quality, but exist short, drawback such as sterilization is not thorough of sorbing material replacement cycle.And the plasma technology that is called one of the key technology of environmental science " 21 century " in the world is the brand new technical that integrates physics, chemistry, biology and environmental science; be characterized in having concurrently to environmental pollutants physical action, chemical action and biological agent; have advantages such as expense is low, treatment effect good, non-secondary pollution, and with sterilization thoroughly, administer the favor that characteristics such as gaseous state and little pollution effects are remarkable are subjected to the various countries environmentalist.

Have a large amount of active particles in the plasma, these active particles can destroy the hard-degraded substance in the environment fully, and how utilizing the poisonous and hard-degraded substance in the plasma treatment environment is hot research in recent years.Poisonous and the hard-degraded substance that might be used for processing environment from present result of study plasma as a kind of high efficiency, low energy consumption, means applied widely and that treating capacity is big.Existing in this respect people does a lot, and for example has the people to study the SO that removes the power plant discharging with the method for electron beam irradiation in the seventies ₂And NO ₂But low, the operating cost master of this method cost, and capacity usage ratio is not high.Therefore people expect utilizing the method for plasma to remove SO ₂And NO ₂, and done a series of work.Early stage research produces atmospheric plasma to degraded NO based on corona discharge as human corona discharge pulses such as ClementsJ.S _xAnd SO ₂Carried out research, they are having 2.6%H ₂Under the condition that O exists, the SO of initial concentration 1000ppm ₂After being 5.2s discharge time, have 90% to be removed.China has also drawn analog result according to human similar approach such as Chengwus, SO ₂Gas concentration is at 114.5-3259.8mg/m ³In the time of in the scope, SO ₂Remove efficient in the 98.1%-81.4% scope; People such as Ning Cheng are also with Positive Pulse Corona Discharge with add under the condition of ammoniacal liquor taking off NO _xAnd SO ₂Study, they draw adding under ammoniacal liquor and the temperature conditions of higher, and higher desulfuration efficiency is arranged, and can reach 98.9%.And their experimental result shows, ammoniacal liquor is to handling NO _xNot influence, corona is to NO _xDegradation rate have only 31%, the gas volume that is activated during the Corona discharge Treatment pernicious gas is little, has limited the disposal ability of gas like this.Therefore, research in recent years is based on dielectric barrier discharge (DBD), and human DBD discharge generation non-equilibrium plasmas such as LiJing are handled and simulated stack gases, and they draw and remove per kilogram SO ₂Need power consumption 75KWh.People such as Sun Wanming also use DBD discharge removal SO ₂And NO ₂, at SO ₂Initial concentration be 400ppm, NO ₂Initial concentration be 100ppm, obtained 99% degradation rate.With Low Temperature Plasma Treating volatile organic matter (VOC _S) research of aspect also has the method for the traditional processing volatile organic matter in tabloid road not such as absorption, absorption, condensation and burning etc. to be difficult to realize for the pollutant of low concentration in recent years, low concentration volatilization organic pollution as the ppb level is very high with above-mentioned method operating cost, and for the volatile organic matter of common concentration in the ppb-ppm level, when the super beginning concentration that they draw HCHO is 100ppm under the voltage of 19KV and obtain 97% dissociation yield.Bubnov A.G also uses with quadrat method degraded HCHO and phenol, and under preferable condition, phenol etc. are degraded to CO, CO ₂And H ₂O, dissociation yield are 90-99%, also have in recent years with the report of plasma treatment CFC, decompose CFC-11 as human radio frequency discharges such as Eakabayashi, and Ar and H are being arranged ₂Under the condition that O exists, resolution ratio can be up to 100%.In addition, Japanese NEDO also develops and can be heated to 10 ⁴℃, disposal ability is the CFC decomposer of 50kg/h.China's research in this respect also has, and except that the research of desulfurization and denitration is mentioned in the front, has reported the research of corona discharge pulse to decolorizing printing and dyeing waste water in addition.All these is for providing new approaches with the pollutant in the low-temperature plasma degradation environment.

But the above-mentioned Low Temperature Plasma Treating method of utilizing, be in the experimental study stage mostly, the device that productivity allows does not have substantially, the example that is used for actual engineering is still few, and it is single to handle composition mostly, main research object is the processing of industrial waste gas, and service condition is all multicomponent air cleanings in being not suitable for the position closed environment basically.

Summary of the invention

Above-described various aspects mainly are the processing that is used for industrial waste gas, and their characteristics are that concentration is higher, discharge capacity is big, composition is single.And in the closed environment, the purified treatment of the gaseous contaminant in tunnel, the position for example, poor effect then, because its gaseous contaminant is based on organic matter, the component complexity, concentration is very little.Show according to examining report: to be divided into be 9 big classes to pernicious gas in the position, 45 kinds, wherein the most common, to human body harm maximum be: NH ₃, H ₂S, CO, CO ₂, toluene, formaldehyde, methyl alcohol, acetone, bacterium etc.

The present invention be directed to that above-mentioned situation proposes, a kind of equipment and the method that can carry out effective purified treatment to gaseous contaminant in the closed environment that provide is provided.

According to an aspect of the present invention, the gas purification treatment facility that is provided comprises: a blower fan is used to suck gaseous contaminant; A low-temperature plasma generator produces plasma, and the air-breathing attitude pollutant of blower fan is carried out the low temperature plasma purified treatment, and wherein, the needle electrode of this low-temperature plasma generator and the distance between the plate electrode are 2-20mm; A filter course that adsorbs carbon monoxide and carbon dioxide filters the gas of handling through plasma for purification, filters gaseous contaminant in the remaining closed environment; An anion generator carries out anion to the gas after filtering and handles, and increases air quality.

Described low-temperature plasma generator is a dielectric barrier discharge plasma generator.

Described low-temperature plasma generator is the corona discharge plasma generator, comprises drawing together the pulse power, needle electrode, plate electrode and ceramic insulation sheet, and wherein, the distance between needle electrode and the plate electrode is 2-20mm.

Described filter course is the adsorption layer of absorption carbon monoxide and carbon dioxide, comprises the pulse power, needle electrode, plate electrode, and wherein, the distance between needle electrode and the plate electrode is 2-20mm.

Described adsorption layer is compounded to form by hopcalite and NaOH material.

Distance between described needle electrode and the plate electrode is 3-10mm.

Distance between described needle electrode and the plate electrode is 8mm.

According to another aspect of the present invention, the gas purification processing method that is provided may further comprise the steps: suck gaseous contaminant by blower fan; Utilize low-temperature plasma generator to produce plasma, so that the air-breathing attitude pollutant of blower fan is carried out the low temperature plasma purified treatment, wherein, the needle electrode of described low-temperature plasma generator and the distance between the plate electrode are 2-20mm; Utilize the filter course of absorption carbon monoxide and carbon dioxide, the gas of handling through plasma for purification is filtered, filter gaseous contaminant in the remaining closed environment; Utilize anion generator, the gas after filtering is carried out anion handle, to increase air quality.

The present invention is very desirable to the removal effect of pernicious gas, especially PARA FORMALDEHYDE PRILLS(91,95), H ₂The purifying rate of S has reached 100%.In addition, the purifying rate of bacterium is reached 98.9%, that is to say the sterilization functions highly significant.

The present invention is described in detail with way of example below in conjunction with accompanying drawing.

Description of drawings

Fig. 1 is the allocation plan of air cleaning treatment facility of the present invention;

Fig. 2 is the schematic diagram of a kind of low-temperature plasma generator shown in Fig. 1 (dielectric barrier discharge);

Fig. 3 is the schematic diagram of the another kind of low-temperature plasma generator (corona) shown in Fig. 1;

Fig. 4 is the theory diagram of the pulse power among Fig. 2 and Fig. 3;

Fig. 5 to Figure 10 is the analysis chart of explanation plasma discharge electrode design of the present invention.

The specific embodiment

Referring to Fig. 1, gas purification treatment facility of the present invention comprises: a blower fan is used to suck gaseous contaminant; A blower fan is used to suck gaseous contaminant; A low-temperature plasma generator produces plasma, blower fan is sucked gaseous contaminant carry out the low temperature plasma purified treatment; A filter course filters the gas of handling through plasma for purification, filters the remaining celebrating gas that has; An anion generator carries out anion to the gas after filtering and handles, and increases air quality.

Referring to Fig. 2, low-temperature plasma generator of the present invention is a dielectric barrier discharge plasma generator, comprises the pulse power, needle electrode, plate electrode and ceramic insulation sheet, and wherein, the distance between needle electrode and the plate electrode is 2-20mm.

Referring to Fig. 3, low-temperature plasma generator of the present invention is the corona discharge plasma generator, comprises the pulse power, needle electrode, plate electrode and ceramic insulation sheet, and wherein, the distance between needle electrode and the plate electrode is 2-20mm.

In addition, described filter course is the adsorption layer of absorption carbon monoxide and carbon dioxide.

Described adsorption layer is compounded to form by materials such as hopcalite and NaOH.

Referring to Fig. 1, gas purification processing method of the present invention may further comprise the steps: suck gaseous contaminant; Blower fan is sucked gaseous contaminant carry out the low temperature plasma purified treatment; The gas of handling through plasma for purification is filtered, filter remaining pernicious gas; Gas after filtering is carried out anion handle, increase air quality.

Dielectric barrier discharge produces lower temperature plasma technology principle and characteristics.

As shown in Figure 2, be filled with the gas that is studied between the electrode, total electronics in a small amount that exists in the gas, the free path of electronics is longer in the gas, and when the electrode two ends add high voltage, the electronics in the gas is quickened by electric field, when electronics accelerates to a certain degree, the bombardment neutral molecule makes neutral molecule continue ionization, produces cation and new electronics.Cation that is produced and new electronics obtain kinetic energy again from electric field, the bombardment neutral molecule makes recall continuation ionization neutral the branch, and such process chain type ground development is gone down, and forms shower, makes gaseous conduction.If add alternating electric field between the electrode, then electronics and cation can vibrate with adding alternating electric field between two electrodes, and discharge is continued.

Dielectric barrier discharge (Dielecyric barrier discharge (DBD)) is a kind of approach that obtains low temperature plasma under the hyperbar.This discharge generation is between two electrodes, and wherein at least one will cover one deck dielectric above the electrode, and its structure as shown in Figure 2.Dielectric barrier discharge can be in (0.1-10) * 10 ⁵Carrying out under the air pressure of Pa, is the evenly characteristics moved of the hyperbar of discharge and corona discharge of a kind of large space that has glow discharge concurrently.Principal character is: whole discharge by many on room and time the micro discharge of random distribution constitute, the duration of these micro discharges is very short, generally in the 10ns level.Dielectric layer has two significant feature to this type of discharge: the one, and the motion of charged particle makes micro discharge become very brief one by one pulse in the restriction micro discharge; The 2nd, allow micro discharge be distributed in uniformly and stably between the whole planar electrode and prevent spark discharge.Can not send the huge puncture sound because dielectric barrier discharge does not resemble the airborne spark discharge, be also referred to as voltolising (Silent dischasrge) in history.

A thread little current cycle in the dielectric barrier discharge can be divided into three parts: the one, and electron avalanche breakdown just takes place in the formation of micro discharge; The 2nd, electric charge mainly forms quasi-molecule and free radical in the transportation of discharging gap in this process; The 3rd, the luminescence process of chemical reaction between the active particle and excited state particle de excitation.Wherein Ju Bu breakdown process is in nanosecond order, and the transport process of electric current approximately continues 1-100ns, and then sustainable nanosecond of the chemical process of plasma is to a second order of magnitude.

Dielectric barrier discharge has the advantages that electron density is high and can move under normal pressure, also can be applicable to the removal of hard-degraded substance in the generation of quasi-molecule ultraviolet source and the environment.

Corona discharge pulse produces lower temperature plasma technology principle and characteristics:

Referring to Fig. 3, under normal pressure, corona discharge pulse can produce low temperature plasma, near when electric-field intensity inhomogeneous or electrode electric field than electrode between other position electric-field strength for a long time, the voltage sound pitch arrives to a certain degree, near the electrode gas medium can be produced electric discharge phenomena by partial breakdown, and at this moment, corona discharge has just taken place.In corona discharge, the shape of electrode plays main effect in general.The inhomogeneities of electric field is in main ionization or the little thin layer, and this zone is exactly the corona layer.In general, if corona discharge electrode is a negative pole, then because of the strong electric field of electrode surface quickens electronics electron avalanche takes place.If corona discharge electrode is anodal, then can not make the electron ionization gas molecule form electron avalanche because of electric field is more weak near the negative electrode, and electronics just might obtain higher energy ionization and excite some gas molecules near anode.

According to the analysis that aligns the negative pole corona as can be known, the regeneration electronics of keeping discharge in the positive corona process is less than the regeneration electronics in the negative corona process.Therefore, consider, should select the higher negative corona discharge of corona current from the efficient that purifies air.In crossing of corona discharge planted, transmit energy.

In corona discharge low temp plasma, harmful substance is removed in the following manner:

1) more low-energy electronics and airborne particle and microorganism collision makes it charged, thereby by the electrostatic field adsorption removal;

2) the higher direct and chemical substance collision of electronics of energy makes it ionization and decomposes;

3) multiple interaction between component in higher electronics of energy and the air produces free radical, and harmful substance and free radical carry out two bodies even a prose style free from parallelism and collide and become harmless species.

Because low temperature plasma is a new and high technology, the air cleaning research of using it for both at home and abroad at present in the closed environment is at the early-stage, can be seldom for the technical data of using for reference, so the tactical and technical norms of low-temperature plasma generator tentatively is decided to be:

CO ₂Purifying rate (60min) 〉=70%

CO ₂Purifying rate (60min) 〉=40%

H ₂S purifying rate (60min) 〉=85%

NH ₃Purifying rate (60min) 〉=80%

Low temperature plasma is to the degradation rule of organic pollution:

Plasma chemical reaction is power with the electronic kinetic energy, and therefore, plasma chemical reaction has traditional chemical and reacts unexistent characteristics.But, be abundant neutral free radical and the excitation state group of accumulating the system from the available group that plasma space obtained.The gas organic-matter chemical reaction that is caused by the low-temperature ion body is in the ionization that gas phase is carried out, dissociate, excite, mutually combining and addition reaction between atom and molecule.

Reaction mechanism to the hydrocarbons pollutant low-temperature plasma degradation:

The alkyl dehydrogenation reaction is mainly taken place in the hydro carbons organic matter.The atom state hydrogen that the alkyl disassociation of organic compound can obtain enriching.The rare reduction reaction of organic matter mainly is the free responding of dehydrogenation and pi-electron.

When atomic oxygen and organic alkyl are done the time spent, the generation of alkyl dehydrogenation before this carbonylation, along with the carrying out of oxidation, last organic matter is decomposed into CO ₂And H ₂O.If contain two keys in the organic matter, then decompose through epoxidation process.End product still is CO ₂And H ₂O.

Low temperature plasma is to the degradation rule of arene:

Modal in the aromatic hydrocarbon gaseous contaminant is toluene (C ₇H ₈), dimethylbenzene (C ₈H ₁₀), in their molecule, mainly containing phenyl ring (big π key), its bond energy is as follows: the carbon-to-carbon bond energy in the phenyl ring is approximately 801.5kJ/mol (8.4eV); Carbon-hydrogen link can be approximately 424.6kJ/mol (3.6eV) on the phenyl ring.From medium discharge being produced during electron energy the low temperature plasma measures, draw mean electron energy in its reaction system between 2.42-9.88.4eV.According to formula:

$f\left(\mathrm{\ϵ}\right)=2.07{\left(\mathrm{\ϵ}\right)}^{-3/2}\·{\mathrm{\ϵ}}^{-1/2}\·e^{-15\mathrm{\ϵ}/\mathrm{\ϵ}}$

Wherein f (ε) is the distribution of electron energy in the lowest temperature plasma system of ε for average energy.Can determine that above chemical bond all might scission of link take place in the low temperature plasma generating process and dissociate.

Low temperature plasma is to the degradation rule of alcohols, aldehydes:

Alcohol contains hydroxyl in the molecule, and (OH) functional group can regard the product after hydrogen atom in the hydrocarbon molecule is replaced by hydroxyl as.In pure molecule, the O-H key is that an oxygen atom is with a sp ³Hybridized orbit hands over lid to form mutually; The C-O key is a sp of carbon atom ³A sp of hybridized orbit and oxygen atom ³Hybridized orbit hands over lid to form mutually.With methyl alcohol is example, and the c h bond bond distance is 0.110nm, 109 ° of bond angles; O-H key bond distance is 0.096nm, 110 ° of bond angles; C-O key bond distance is 0.143nm, 108.9 ° of bond angles, and the bond energy of hydrogen bond is 25.9kJ/mol in the methyl alcohol.When methyl alcohol reacted, it was dissimilar to mainly contain two kinds of hydrogen-oxygen key and carbon-oxygen bonds.Because the bond distance of C-O key is big than hydrogen-oxygen key bond distance, therefore, its fracture institute energy requirement is less than hydrogen bond energy, promptly less than 25.9kJ/mol.According to formula:

$f\left(\mathrm{\ϵ}\right)=2.07{\left(\mathrm{\ϵ}\right)}^{-3/2}\·{\mathrm{\ϵ}}^{-1/2}\·e^{-15\mathrm{\ϵ}/\mathrm{\ϵ}}$

Wherein f (ε) is the distribution of electron energy in the lowest temperature plasma system of ε for average energy.Can determine that above chemical bond all might scission of link take place in the low temperature plasma generating process and dissociate.

The main functional group of aldehydes is that aldehyde radical (CHO), promptly is connected with a hydrogen atom on the carbonyl.In the carbonyl, carbon is connected with two keys with oxygen, and two keys of carbon oxygen and carbon-carbon double bond are similar, are made up of a σ key and a π key.In the carbonyl, carbon is connected with two keys with oxygen, and two keys of carbon oxygen and carbon-carbon double bond are similar, are made up of a σ key and a π key.Carbonylic carbon atom is with three sp ²A hybridized orbit and an oxygen atom and two other atoms form three σ keys, and these three keys distribute at grade, and bond angle is similar to 120 °.Also have a p rail side hand-deliver lid to form the π key on the carbon atom, so carbonyl has the triangle projective planum structure.As formaldehyde, C=O bond distance 0.120nm, 121.3 ° of H-C-O bond angles, the long 0.110nm of c h bond, 116.5 ° of H-C-H bond angles.Though the two keys of carbon oxygen are made up of a σ key and a π key, owing to the electronegativity of oxygen is bigger, it holds the very capable of electric charge, so carbon oxygen pair keys polarize π key wherein particularly.Because the pi-electron cloud flows easily, to be partial to easily around the strong oxygen atom of electronegativity, thereby near the cloud density the oxygen atom is increased, near the cloud density the carbon atom reduces.Therefore, carbonyl is a polar group, and its oxygen atom has the part negative electrical charge, and carbon atom has the part positive charge.For aldehyde material, owing to be connected with a hydrogen atom on its carbonyl, therefore, aldehyde radical is oxidized easily.Use weak oxidant such as Fehling or tollens reagent just can make its oxidation.

In plasma based, there is a large amount of free groups, produce part of O simultaneously ₃, have strong oxidisability, can make the aldehyde radical oxidation fully.Therefore, analyze theoretically, plasma also is no problem to the degraded of aldehyde material.

The power supply design

The dielectric impedance Development on inverter:

Improve the ability that generator purifies harmful substance, particularly improve the ability of removing chemical substance, must increase the generation rate of electronics and active material.As dc corona discharge, the power of discharge is subjected to the restriction of electrical breakdown condition, can't do the raising of big spoke degree.Dielectric barrier discharge can produce quite highdensity plasma, as shown in Figure 2, be applied to air cleaning and have tangible advantage, but it requires tens of kHz, amplitude to reach the power supply of 10kV.

Industrial frequency AC change direct current uprises frequently again, and communication process is referred to as inversion.Use the power supply of this technology to be referred to as inverter.Owing to use electronic switching element, claim the inverse switch power supply again.

The basic principle of inverse switch power supply is: elder generation is with the 220V alternating current of power frequency 50Hz, through being rectified into 308V direct current supply power square wave translation circuit.The electro coupled oscillator of being made up of integrated circuit removes to promote the IGBT high power module after isolating amplification.The continuous square wave of this oscillator output, the frequency of square wave is determined by integrated oscillator.The frequency of integrated oscillator output from several kilocycles to 100 kilocycles.With the high frequency waves of electronic switch output through the high-frequency power transformer isolation boosting to the 8000V alternating-current pulse, if through rectification output unidirectional pulse.Pulse signal is provided on the dielectric barrier discharge electrode, just can produces dielectric barrier discharge plasma.

Honest variable power source technical parameter is as follows:

Input voltage: 220V;

Output floating voltage peak value: 8000V-12000V;

Output current peak value: 50mA-300mA.

Connect load during use, connect 220 volts of electricity and get final product work.All bright as red green indicator lamp, be normal operating conditions; Do not work if green light sends out a warning, be the small voltage state, can regulate blue variable resistor clockwise voltage is strengthened; Outage after all glimmering as traffic lights illustrates overcurrent, and power supply is protected automatically, will reclose 220 volts of electricity this moment, and power supply just can be reworked.

The impulse electric corona power supply

The operation principle of impulse electric corona power supply is: input 220V power supply obtains 308V after rectification, supplier's wave producer produces the power square wave, boosts through variable-frequency transformer, produces high-voltage pulse power source, referring to Fig. 4.

Parameter is as follows:

Input voltage: 220V;

Output floating voltage peak value: 12000V;

Output current peak value: 300mA.

Operating voltage: 0-8000V is adjustable.

Connect load during use, connect 220 volts of electricity and get final product work.All bright as red green indicator lamp, be normal operating conditions; Sending out a warning as green light does not work, and is the small voltage state, can regulate blue variable resistor clockwise voltage is strengthened; Outage after all glimmering as traffic lights illustrates overcurrent, and power supply is protected automatically, will reclose 220 volts of electricity this moment, and power supply just can be reworked.

The design of plasma discharge electrode:

The electrode structure that the present invention adopts is line board-like (needle electrode and plate electrode) electrode structure.Therefore, can obtain its approximation according to the electrode structure form.On cross section, set up x, y coordinate, on the axis direction of corona discharge electrode, set up the z coordinate shown in Fig. 5 (electric field find the solution coordinate) perpendicular to corona discharge electrode.

According to uniqueness theorem as can be known, in the space arbitrarily certain P (x, y z) have well-determined electric field $\stackrel{\→}{E}=\stackrel{\→}{E}(x,y,z),$ Because electric charge is that the z direction of principal axis evenly distributes along the corona discharge electrode direction on the corona discharge electrode, so (x when y) determining, has identical electric field for any Z, and promptly space electric field distributes irrelevant with Z as space P.The boundary condition of this electrode system:

E (oa)=E ₀, E (ao)=E ₀, E (by)=constant formula 1

We adopt method of images to come solution space electric field (shown in Fig. 6 (line charge Q and its are as charge Q ' constitute electric field)), because the dust collecting electrode electromotive force is zero, suppose to exist one to look like distribution of charges Q '=Q at dust collecting electrode the right b place, then any 1 P in space (x, the electric field of y) locating:

${\stackrel{\→}{E}}_p=\stackrel{\→}{E}+{\stackrel{\→}{E}}^{\′}$

$E_x=E\cos \mathrm{\&theta;}+E^{\&prime;}\cos {\mathrm{\&theta;}}^{\&prime;}=\frac{\mathrm{<figure-callout\; id="2"\; label="Q"\; filenames="C0211660600223.png"\; state="\{\{state\}\}">Q</figure-callout>}}{2{\mathrm{\&pi;\&epsiv;}}_0}[\frac{x}{x^2+{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="C0211660600223.png"\; state="\{\{state\}\}">y</figure-callout>}}^2}+\frac{2b-x}{{(\mathrm{xb}-x)}^2+y^2}]$

Formula 2

$E_y=E\sin \mathrm{\&theta;}+E^{\&prime;}\sin {\mathrm{\&theta;}}^{\&prime;}=\frac{\mathrm{<figure-callout\; id="2"\; label="Q"\; filenames="C0211660600223.png"\; state="\{\{state\}\}">Q</figure-callout>}}{2{\mathrm{\&pi;\&epsiv;}}_0}[\frac{y}{x^2+{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="C0211660600223.png"\; state="\{\{state\}\}">y</figure-callout>}}^2}+\frac{y}{{(2b-x)}^2+y^2}]$

Formula 3

Fig. 6:

CONSIDERING BOUNDARY CONDITIONS (formula 1), the field intensity that can obtain a bit locating arbitrarily in the space is:

$\stackrel{\&RightArrow;}{E}(x,y)=E_{0}a[(\frac{x}{x^2+{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="C0211660600223.png"\; state="\{\{state\}\}">y</figure-callout>}}^2}+\frac{2b-x}{{(2b-x)}^2+y^2})\stackrel{\&RightArrow;}{i}+(\frac{y}{x^2+y^2}-\frac{y}{{(2b-x)}^2})\stackrel{\&RightArrow;}{j}]$

Formula 4

In the formula: E ₀Be corona discharge electrode surface breakdown field intensity.According to: $\stackrel{\mathrm{\&rho;}}{E}=-\&dtri;\mathrm{\&Phi;}$ We can obtain any point electromotive force in the space:

$\mathrm{\&phi;}(x,y)=\&Integral;\frac{\&PartialD;\mathrm{\&phi;}}{\&PartialD;x}\mathrm{dx}+\&Integral;\frac{\&PartialD;\mathrm{\&phi;}}{\&PartialD;y}\mathrm{dy}=-E_{0}a\ln \frac{x^2+y^2}{{(2b-x)}^2+{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="C0211660600223.png"\; state="\{\{state\}\}">y</figure-callout>}}^2}$

Formula 5

CONSIDERING BOUNDARY CONDITIONS: φ (o, a)=φ (a, o)=-U, have:

$\mathrm{\&phi;}(x,y)=-\frac{\mathrm{<figure-callout\; id="2"\; label="U"\; filenames="C0211660600223.png"\; state="\{\{state\}\}">U</figure-callout>}}{2\ln (a/2b)}\ln \frac{x^2+y^2}{{(2b-x)}^2+{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="C0211660600223.png"\; state="\{\{state\}\}">y</figure-callout>}}^2}$

In formula 6 formulas: U: institute's making alive on the corona discharge electrode, a, b, d are the electrode system structural parameters.Because electrode structure gets final product about the Potential Distributing in y space on the xoy plane.(a, b), (a, b), z is any for x ∈ for y ∈ in this space.Can draw the electrode space Potential Distributing shown in Fig. 7 (the board-like electrode structure potential profile of line) according to formula 6.If there is the line-plate electrode system of many discharge electrodes, its corona discharge electrode setting as shown in Figure 8, when ion began to flow, Potential distribution was shown in Fig. 9 (multi-electrode system spatial distribution).Although voltage changes, the equipotential line shape also not too changes.Formed electric field between the corona discharge electrode a little less than, and corona discharge electrode at interval 2c is big more, this situation is obvious more.At this moment adopt the method for resolving to ask electric field impossible, can adopt progressively approximate method to try to achieve is bit function.

$\mathrm{\&phi;}(x,y)=-\frac{{\mathrm{<figure-callout\; id="0"\; label="U"\; filenames="C0211660600223.png"\; state="\{\{state\}\}">U</figure-callout>}}_0}{\ln \frac{d}{a}}\ln \left[\sqrt{k}\right|s_n(\frac{k_z}{c},k)\left|\right]-\frac{\ln \frac{d}{a}}{4{\mathrm{\&pi;\&epsiv;}}_0{\mathrm{\&mu;}}_{i}U}I(b^2-x^2)$ Formula 7

In the formula: $d=c/K\sqrt{k};K=c{\&Integral;}_0^{\mathrm{\&pi;}/2}\frac{1}{\sqrt{1-{\mathrm{\&mu;}}^2{\mathrm{<figure-callout\; id="2"\; label="sin"\; filenames="C0211660600223.png"\; state="\{\{state\}\}">sin</figure-callout>}}^2\mathrm{\&phi;}}}\mathrm{d\&phi;};$

$k={[{2\mathrm{<figure-callout\; id="1"\; label="q"\; filenames="C0211660600223.png"\; state="\{\{state\}\}">q</figure-callout>}}^{1/4}\underset{n=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}{q}^{n(n-1)}/1+2\underset{n=1}{\overset{\&infin;}{\mathrm{\&Sigma;}}}{q}^{n^2}]}^{1/2};$ $q=\exp (-\frac{2\mathrm{\&pi;b}}{c});$ ${\mathrm{<figure-callout\; id="0"\; label="U"\; filenames="C0211660600223.png"\; state="\{\{state\}\}">U</figure-callout>}}_0=a{\mathrm{<figure-callout\; id="0"\; label="E"\; filenames="C0211660600223.png"\; state="\{\{state\}\}">E</figure-callout>}}_0\ln \frac{d}{a};$ Corona inception voltage; $S_n(\frac{K_z}{c},k):$ Jacobian elliptic function.When b/c≤0.6, d ≈ 4b/ π; When b/c 〉=2, d ≈ c/[π exp (π b/c)]; When 0.6≤b/c≤2, the value of d is pressed shown in Figure 10 (b/c and c/d graph of a relation).We can know thus, and when electrode gap d and corona wire when the ratio of 2c is very little at interval, d is relevant with the corona wire interval.

According to formula 7, we can directly obtain the electric current that flows on the corona discharge electrode unit length.When the corona space did not have ion to flow, the voltage on the corona discharge electrode was voltage V of super beginning of corona ₀, I=0 is at this moment obtained by formula 7:

$\mathrm{\&phi;}(x,y)=-\frac{{\mathrm{<figure-callout\; id="0"\; label="U"\; filenames="C0211660600223.png"\; state="\{\{state\}\}">U</figure-callout>}}_0}{\ln d/a}\ln \left[\sqrt{k}\right|S_n(\frac{K_z}{c},k)\left|\right]=-{\mathrm{<figure-callout\; id="0"\; label="U"\; filenames="C0211660600223.png"\; state="\{\{state\}\}">U</figure-callout>}}_0$ Formula 8

With the rising gradually of corona discharge electrode voltage, the corona space begins to have ion to flow, and when reaching balance, flows to the electric current (x=0 this moment) of corona discharge electrode:

$I=\frac{4{\mathrm{\&pi;\&epsiv;}}_0{\mathrm{\&mu;}}_i}{b^2\ln (d/a)}U(U-U_0)$ Formula 9

If b/c≤0.6 o'clock, then: $I=\frac{4{\mathrm{\&pi;\&epsiv;}}_0{\mathrm{\&mu;}}_i}{b^2\ln 4b/\mathrm{\&pi;a})}U(U-U_0)$ Formula 10

If b/c 〉=2 o'clock, then $I=\frac{8{\mathrm{c\&epsiv;}}_0{\mathrm{\&mu;}}_i}{b^3}U(U-U_0)$ Formula 11

Current density on the collector is so: $i=\frac{4{\mathrm{\&epsiv;}}_0{\mathrm{\&mu;}}_i}{b^3}U(U-U_0)$ Formula 12

This shows when corona wire is enough big at interval, flows to the unit long electrical wave and the corona number of poles and irrelevant at interval of corona discharge electrode, and the current density on the collector is not with the corona discharge electrode interval variation simultaneously.Therefore, when the design electrode structure, corona discharge electrode spacing parameter c size is unessential, importantly the size of positive and negative electrode spacing parameter b.But as can be known: i ∝ 1/b from formula 11 and 12 ⁿ, when b/c≤2, n=2; When b/c＞2, n=3.Therefore, two electrode gap b and corona discharge electrode at interval the ratio of 2c to the influence of corona current also outbalance.In the time of generally speaking between b/c=0.6～2.0, the I maximum.Formula 8 is asked the derivative of position, then can obtain the electric-field intensity of the board-like electrode system of line by utmost point space.Near collector, promptly during x → b, can obtain approximate formula:

$E\&ap;\sqrt{\mathrm{Ib}/{\mathrm{\&pi;c\&epsiv;}}_0{\mathrm{\&mu;}}_i}$

Formula 13

When b=c: $E\&ap;\sqrt{I/{\mathrm{\&pi;\&epsiv;}}_0{\mathrm{\&mu;}}_i}$

Formula 14

Near the electric field that this is with cylinder type electrode system collector $E\&ap;\sqrt{I/2{\mathrm{\&pi;\&epsiv;}}_0{\mathrm{\&mu;}}_i}$ Compare, reach near the electric field collector under the condition of same level, the corona current of the board-like electrode system of line only needs half of cylinder type electrode system corona current.

By above derivation as can be seen: it is easy than the cylinder type electrode system that the board-like electrode system of line produces plasma.Therefore, the board-like electrode of this problem employing line is effectively.

When the design generator, we select for use the very little pin electrode of diameter as discharge electrode, and this moment, a can ignore; Get between the two poles of the earth distance and be 10mm, be i.e. 2c=10mm, distance c=8mm between this moment two battery lead plates.

The removal of ozone

In corona discharge process, the electronics with dissociative ionization oxygen molecule ability all concentrates in the corona zone.If the electron density in the corona zone is higher, energy then will produce ozone more or less greater than the oxygen molecule bond energy.Ozone has positive influences because of having strong oxidizing property to clean-up effect.Therefore, in the discharge purification process, should suitably produce ozone, but the concentration of the ozone after purifying must be controlled (GJB3143-97) within the specific limits, otherwise can produce harm human body with the raising purifying rate.

For plasma generator, the generation of ozone is inevitably, therefore, to avoid it human body is produced harmful effect with regard to how eliminating excessive ozone, and seminar has carried out a large amount of work.

The bond angle of ozone molecule is 116.8 °, bond energy 1.05 ± 0.02eV, but decompose slowly at normal temperatures.Then decompose rapidly and methods such as catalytic decomposition as heat, light radiation or catalysis.

Data shows: ozone is high more through uviol lamp power, and gas flow rate is slow more, and ozone degradation efficient is high more.Because the air quantity of device is had relatively high expectations, so gas flow rate is easy to control, and, consider that from economical and other combined factors it is inappropriate adopting ultraviolet light to decompose in this problem.

Except that ultraviolet photolysis, can also adopt corona wire to heat and remove unnecessary ozone.When reaching 163 ℃, the residing environment temperature of ozone can decompose, though heated by electrodes can make the ozone generating capacity decrease within a certain period of time, but because the corona discharge electrode heating can make corona current increase sharply, so ozone still can increase along with corona current is linear.

For effectively avoiding the too much ozone of plasma generation that human body is worked the mischief, seminar adsorbs ozone at the terminal activated carbon fiber of development voluntarily that adopts of generator, experimental results show that this sorbing material can effectively absorb the ozone that plasma generator produces, make ozone concentration meet the regulation of national standard.

Hygiene environmental medicine research detection shows through Military Medical Science Institute, and purifying the back ozone concentration is 0.03-0.07mg/m ³See survey report), meet the regulation of GJB314-97.

Test and interpretation of result

Be the purifying property of check low temperature plasma, we to the dielectric impedance of development voluntarily put, the corona discharge low temperature plasma and at present the low temperature plasma of domestic other type carried out comprehensive comparison.

To the inorganic pollution clean-up effect relatively

Ammonia and hydrogen sulfide is present more common gaseous state inorganic pollution, and we have checked the removal effect of four kinds of low temperature plasmas to ammonia and hydrogen sulfide.

Laboratory apparatus, equipment

QGS-08 carbon monoxide infrared ray gas analyzer (Beijing);

Z-300 formaldehyde determination instrument (U.S.);

Z-800 ammonia analyzer (U.S.);

Electronics time control air sampler;

FWL-IIB type air microbe monitor;

Ultrasonic atomizer;

Experiment polypropylene plastics pocket (1.7m ³);

Air compressor;

1/100 weighing scale to test twisting force;

Laboratory Module (4.0m ³);

The pernicious gas detector tube;

Portable electric heating pressure steam sterilizer;

Oese, inoculated tube, culture dish, syringe (100ml).

Reagent

AR: formaldehyde, toluene, dimethylbenzene, methyl alcohol, acetone, ammonia, ferrous sulfide, hydrochloric acid.

Standard gas: carbon monoxide

Other: physiological saline, nutrient agar

Test method

Dielectric impedance, corona discharge low temp plasma are put 1.7m respectively ³In the polybag of volume, power line and sampling pipe are in communication with the outside, and airtight sack is blown into air in the bag with sampler, add institute simultaneously and are furnished with harmful gas, treat that airbag is full of, and measure harmful gas concentration in the airbag with instrument or gas detecting tube behind the mixing.Do not start shooting, left standstill 1 hour, observe natural decay rate when leaving standstill; Start shooting and shut down after 1 hour, measure harmful gas concentration.

Result of the test and analysis

To the result of the test of ammonia, hydrogen sulfide shown in table 1, table 2.

Table 1: the ammonia decontamination effect is compared (hl)

	Dielectric barrier discharge	Corona discharge	Certain is No. 1	Certain is No. 2
					Before the purification	10.0	15.0	8.0	8.0
After the purification	3.0	7.0	6.0	5.0
					Purifying rate %	70.0	53.3	25.0	37.5

Table 2: to H ₂The S clean-up effect is (hl) relatively

	Dielectric barrier discharge	Corona discharge	Certain is No. 1	Certain is No. 2
					Before the purification	130.0	380.0	20.0	186.0
After the purification	30.0	1.0	10.0	168.0
					Purifying rate %	76.9	99.7	50.0	8.4

As can be seen from the above results: low temperature plasma is for removing NH ₃, H ₂Two kinds of gases of S are effectively, and this may be because NH ₃, H ₂S has reproducibility, and the free radical that can be had oxidisability in the plasma is (as O ₃) due to the oxidation.In above-mentioned four kinds of plasmas, to NH ₃, H ₂What the S clean-up effect was best is corona discharge low temp plasma.

To the organic pollution clean-up effect relatively

Because at present common gaseous contaminant is in the majority with organic matter, therefore, we check four kinds of plasmas to the purification of toluene, dimethylbenzene, methyl alcohol, acetone.

Clean-up effect to toluene, dimethylbenzene, methyl alcohol, acetone sees Table shown in the 3-table 6.

Table 3: the clean-up effect to toluene compares (hl, mg/m ³)

	Dielectric barrier discharge	Corona discharge	Certain is No. 1	Certain is No. 2
					Before the purification	700.0	700.0	120.0	1000.0
After the purification	250.0	250.0	50.0	850.0
					Purifying rate %	64.3	64.3	58.3	15.0

Table 4: the clean-up effect of paraxylene is (hl, mg/m relatively ³)

	Dielectric barrier discharge	Corona discharge	Certain is No. 1	Certain is No. 2
					Before the purification	8000	7500	6000	6000
After the purification	5000	2000	3000	4500
					Purifying rate %	37.5	73.3	50.0	25.0

Table 5: the clean-up effect to methyl alcohol compares (hl, mg/m ³)

	Dielectric barrier discharge	Corona discharge	Certain is No. 1	Certain is No. 2
					Before the purification	420.0	350.0	800.0	200.0
After the purification	370.0	10.0	750.0	200.0
					Purifying rate %	11.9	97.1	6.2	0.0

Table 6: the clean-up effect to acetone compares (hl, mg/m ³)

	Dielectric barrier discharge	Corona discharge	Certain is No. 1	Certain is No. 2
					Before the purification	200.0	250.0	700.0	100.0
After the purification	150.0	100.0	400.0	100.0
					Purifying rate %	25.0	60.0	42.9	0.0

By above result as can be seen: low temperature plasma is better to the removal effect of toluene, dimethylbenzene, and this may be because for C ₆-C ₇Aromatic hydrocarbon, forming in the process of plasma through overdischarge, there is following process: under the effect of taking the energy electronics after quickening through electric field, hydrocarbon molecule is excited after absorbing energy, and the hydrocarbon molecule generation scission of link that a part is in excitation state dissociates and forms due to the free radical fragment of many short carbon chains.Purifying rate to methyl alcohol, acetone is relatively low, this may owing to-OH in conjunction with closely causing.

In above-mentioned four kinds of plasmas, to toluene, dimethylbenzene, methyl alcohol, four kinds of organic pollution clean-up effects of acetone best be corona discharge low temp plasma.

The index performance

By as can be seen above: corona discharge low temp plasma is more satisfactory to the treatment effect of gaseous contaminant, and therefore, the applicant adopts this discharge type to make the corona discharge low temp plasma generator, and has completely examined its performance.

Test

Laboratory apparatus, equipment, method are the same.

The clean-up effect check

Clean-up effect check to pernicious gas

The applicant is imitated the purification of corona discharge low temp plasma generator and has been carried out comprehensive check and evaluation, and concrete outcome sees Table 7.

Table 7: corona discharge low temp plasma generator clean-up effect

The pernicious gas kind	Harmful gas concentration (mg/m 3)		Purifying rate (%)
				Before the purification	After the purification
	H 2S	33.0				0.0	100.0
NH 3			110.0	7.0	93.6
	CO	140.0				63.0	55.0
CO 2			11.5 ten thousand	2.0 ten thousand	82.6
	Toluene	750.0				250.0	66.7
Dimethylbenzene			650.0	60.0	90.8
	Methyl alcohol	300.0				20.0	93.3
Acetone			550.0	150.0	72.7
	Formaldehyde	2.3				0.0	100.0
O 3				0.03-0.07	-
	Anion					1.5×10 6Individual/cm 3	-

From table 7 data as can be seen, the corona discharge low temp plasma generator is very desirable to the removal effect of pernicious gas, especially PARA FORMALDEHYDE PRILLS(91,95), H ₂The purifying rate of S has reached 100%, and this conforms to theory analysis, has also satisfied the requirement of tactical and technical norms.

Clean-up effect to microorganism

Use ultrasonic atomizatio behind Laboratory Module the bacterium liquid after the dilution, sample immediately as background, recording its bacterial population is 2300CFU/m ³, open low-temperature plasma generator, in purifying sampling in back 30 minutes, record the bacterial action highly significant.

Experiment showed, that corona discharge low temp plasma generator of the present invention is 93.6% to the purifying rate of ammonia; Hydrogen sulfide purifying rate: 100.0%; Carbon monoxide: 55.0%; Carbon dioxide: 82.6%; Toluene: 66.7%; Dimethylbenzene: 90.8%; Methyl alcohol: 93.3%; Acetone: 72.7%; Formaldehyde: 100.0%; Sterilization rate: 98.9% (30min); Ozone concentration: 0.03-0.07mg/m ³Negative ion concentration: 1.5 * 10 ⁶Individual/cm ³Satisfy the requirement of tactical and technical norms fully.

Claims (8)

1, a kind of equipment to gaseous contaminant purified treatment in the closed environment comprises:

A blower fan is used to suck gaseous contaminant;

A low-temperature plasma generator produces plasma, and the air-breathing attitude pollutant of blower fan is carried out the low temperature plasma purified treatment, and wherein, the needle electrode of this low-temperature plasma generator and the distance between the plate electrode are 2-20mm;

A filter course that adsorbs carbon monoxide and carbon dioxide filters the gas of handling through plasma for purification, filters gaseous contaminant in the remaining closed environment;

An anion generator carries out anion to the gas after filtering and handles, and increases air quality.

2, equipment according to claim 1, wherein said low-temperature plasma generator are dielectric barrier discharge plasma generators, comprise the pulse power, needle electrode, plate electrode and ceramic insulation sheet.

3, equipment according to claim 1, wherein low-temperature plasma generator is the corona discharge plasma generator, comprises the pulse power, needle electrode, plate electrode.

4, equipment according to claim 1, wherein said filter course are the adsorption layers of absorption carbon monoxide and carbon dioxide.

5, equipment according to claim 4, wherein said adsorption layer is compounded to form by hopcalite and NaOH material.

6, according to claim 2 or 3 described equipment, the distance between wherein said needle electrode and the plate electrode is 3-10mm.

7, according to claim 2 or 3 described equipment, the distance between wherein said needle electrode and the plate electrode is 8mm.

8, a kind of method to gaseous contaminant purified treatment in the closed environment may further comprise the steps:

Suck gaseous contaminant by blower fan;

Utilize low-temperature plasma generator to produce plasma, so that the air-breathing attitude pollutant of blower fan is carried out the low temperature plasma purified treatment, wherein, the needle electrode of described low-temperature plasma generator and the distance between the plate electrode are 2-20mm;

Utilize the filter course of absorption carbon monoxide and carbon dioxide, the gas of handling through plasma for purification is filtered, filter gaseous contaminant in the remaining closed environment;

Utilize anion generator, the gas after filtering is carried out anion handle, to increase air quality.

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