CN103272696A - Particulate diffusion charge thickening method - Google Patents

Abstract

A particulate diffusion charge thickening method belongs to the technical field of environmental engineering and the like. The method provided by the invention is characterized in that primary particulates of PM0.1 and unipolar ions are injected together in a high-frequency high-voltage alternating electric field; the unipolar ions perform reciprocating motions up and down in the high-frequency high-voltage alternating electric field for 103-104 times; and each particulate of PM0.1 and the unipolar ions undergo collision charge thickening for tens of thousands even hundreds of thousands so as to further increase the particle size by 10-103 times and agglomerate to form primary particulates with the particle size being greater than 2 microns. Effects and advantages of the method provided by the invention are as follows: an effective method is provided to remove the atmospheric pollutant primary particulates of PM0.1; the method also can be used in ultramicro-sized coal dust dispersion charge electrocoagulation pretreatment by a dust remover; and one-time investment and operation costs and energy consumption are all reduced significantly.

Description

A kind of particle diffusional charging increases thick method

Technical field

The invention belongs to technical fields such as gas discharge physics, plasma technique and environmental project, relate to a kind of particle diameter and increase thick method less than 0.1 μ m primary particulate diffusional charging.

Background technology

China is the economic giant that is emerging, the energy has 2/3rds from coal, dependency degree is very high, only consumption of coal just increases by 44% in the period of 2005 to 2010, industrial enterprise, power plant fire coal, oil burning boiler combustion process produce ultra tiny flue dust, i.e. particle diameter≤0.1 μ m primary particulate PM0.1.Because its specific area is very big, active strong, adsorptivity is strong, causes PM0.1 surface very easily heavy metal (As, Se, Pb, Cr etc.) and organic pollutions such as PAHs, VOCs in the enriched air By; Also easily attach SO ₂, pollutant such as NOx and accessory substance sulfuric acid thereof, nitric acid, sulfate, nitrate, these pollutants mostly are carcinogen or genotoxicity mutagen matter.These trace contaminants can be in further migration and the enrichment of its surface, and its harmfulness is very big.Administer the PM0.1 atmosphere pollution and become the instant great people's livelihood problem of China.

Primary particulate is charged to be increased and knew a little about the unipolarity ion and its collision that produce behind the gas ionization and realize, increase thick mechanism and be divided into two kinds, a kind of is that electric-field charge increases slightly, gas unipolarity ion when extra electric field effect lower edge power line direction is done regular motion and particle collision charged increase thick; Another kind of diffusional charging increases slightly, collides charged increasing slightly with particle when gas is done irregular movement.Primary particulate is charged, and to increase thick mechanism different and different according to its particle diameter.When particle diameter＞1 μ m, increase slightly with electric-field charge and take as the leading factor; When particle diameter＜0.1 μ m, then increase slightly with diffusional charging and take as the leading factor.Electrostatic precipitation technology is to increase slightly based on electric-field charge at present, mainly captures the particle of particle diameter＞1 μ m.Then helpless to PM0.1.

Summary of the invention

The invention solves the existing particle diameter that captures less than the problem that 0.1 μ m primary particulate exists, provide a kind of particle diameter to increase thick new method less than 0.1 μ m primary particulate diffusional charging.Gas and high concentration unipolarity ion that this method will contain the PM0.1 primary particulate inject the high-frequency and high-voltage alternating electric field in the lump, and the unipolarity ion does 10 with flank speed in the high-frequency and high-voltage alternating electric field ³～10 ⁴Inferior pumping, PM0.1 primary particulate and unipolarity ion or charged PM0.1 primary particulate diffusional charging increase thick tens thousand of times, even hundreds thousand of times; After the PM0.1 primary particulate increased slightly by high-frequency and high-voltage alternating electric field diffusional charging, particle diameter increased 10～10 ³Doubly, the charged particle diameter＞2 μ m primary particulates that are condensed into.Provide a kind of effective method for eliminating PM0.1 primary particulate atmosphere pollution, and have all advantages such as reduction significantly such as once investment, operating cost, energy consumption.

PM0.1 primary particulate diffusional charging is to do the ion of random warm-up movement and its collision and make it charged.For the diffusional charging of particle diameter＜0.1 μ m grit and its size, carrying capacity and ion warm-up movement intensity, collision probability, movement velocity and in electric field multiple factor such as time of staying relevant.Grit charged process and carrying capacity calculating formula are derived and are all followed the relevant theory of gas molecule motion.

If apart from the suitable far ultraviolet of grit, the unipolarity ion numerical digit N in the electric field in the unit bodies; Be N1 near the number of ions around the grit, according to the gas molecule motion theory, can get the expression of both sides relation:

N ₁The formula 1 of=N * exp(-eV/kT)

In the formula: e is the quantity of electric charge of ion; V is the current potential of grit whereabouts; K is the Bo Ciman constant; T is gas temperature; Ion passes the number N of grit unit's external surface area in the unit interval ₂During expression, then

${\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="HDA00003312951600013.png"\; state="\{\{state\}\}">N</figure-callout>}}_2={\mathrm{<figure-callout\; id="1"\; label="N"\; filenames="HDA00003312951600013.png"\; state="\{\{state\}\}">N</figure-callout>}}_1\sqrt{\frac{\mathrm{<figure-callout\; id="2"\; label="kT"\; filenames="HDA00003312951600013.png"\; state="\{\{state\}\}">kT</figure-callout>}}{2\mathrm{\&pi;<figure-callout\; id="2"\; label="m\; Formula"\; filenames="HDA00003312951600013.png"\; state="\{\{state\}\}">m</figure-callout>}}}$ Formula 2

In the formula: m is the quality of ion.Know according to Gauss theorem, be positioned at grit outer peripheral areas electric-field intensity and be

${\mathrm{<figure-callout\; id="2"\; label="E"\; filenames="HDA00003312951600013.png"\; state="\{\{state\}\}">E</figure-callout>}}_2=\frac{{\mathrm{<figure-callout\; id="4"\; label="q\; p"\; filenames="HDA00003312951600013.png"\; state="\{\{state\}\}">q</figure-callout>}}_p}{4\mathrm{\&pi;}{\mathrm{\&epsiv;}}_0{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="HDA00003312951600013.png"\; state="\{\{state\}\}">r</figure-callout>}}^2}$ Formula 3

In the formula: q _pBe the primary particulate quantity of electric charge; E ₂For the peripheral carrying capacity of grit is q _pThe time electric field strength; ε ₀Be the vacuum dielectric constant; R is the peripheral charged radius of particle.With the differential form of formula 3 to the r integration, then the charged back of grit at the current potential at radius r place

$V=\frac{{\mathrm{<figure-callout\; id="4"\; label="q\; p"\; filenames="HDA00003312951600013.png"\; state="\{\{state\}\}">q</figure-callout>}}_p}{4\mathrm{\&pi;}{\mathrm{\&epsiv;}}_0\mathrm{<figure-callout\; id="4"\; label="r\; Formula"\; filenames="HDA00003312951600013.png"\; state="\{\{state\}\}">r</figure-callout>}}$ Formula 4

In formula 4 substitution formulas 1, then

${\mathrm{<figure-callout\; id="1"\; label="N"\; filenames="HDA00003312951600013.png"\; state="\{\{state\}\}">N</figure-callout>}}_1=N\&times;\exp (-\frac{{\mathrm{<figure-callout\; id="4"\; label="eq\; p"\; filenames="HDA00003312951600013.png"\; state="\{\{state\}\}">eq</figure-callout>}}_p}{4\mathrm{\&pi;}{\mathrm{\&epsiv;}}_0\mathrm{kTr}})$ Formula 5

At grit outer surface r=a place, the number of ions N in the unit volume _1aFor

$N_{1a}=N\&times;\exp (-\frac{{\mathrm{<figure-callout\; id="4"\; label="eq\; p"\; filenames="HDA00003312951600013.png"\; state="\{\{state\}\}">eq</figure-callout>}}_p}{4\mathrm{\&pi;}{\mathrm{\&epsiv;}}_0\mathrm{kTa}})$ Formula 6

Utilize formula 6 to calculate the charged speed on particle surface

$\frac{{\mathrm{dq}}_p}{\mathrm{dt}}=4\mathrm{\&pi;e}{N}_{2a}{a}^2={4\mathrm{\&pi;ea}}^2{N}_{1a}\sqrt{\frac{\mathrm{<figure-callout\; id="2"\; label="kT"\; filenames="HDA00003312951600013.png"\; state="\{\{state\}\}">kT</figure-callout>}}{2\mathrm{\&pi;m}}}$

$=e\sqrt{\frac{8\mathrm{\&pi;<figure-callout\; id="2"\; label="kT\; m\; a"\; filenames="HDA00003312951600013.png"\; state="\{\{state\}\}">kT</figure-callout>}}{m}}{a}^{}{}^2\mathrm{Nexp}(-\frac{{\mathrm{<figure-callout\; id="4"\; label="eq\; p"\; filenames="HDA00003312951600013.png"\; state="\{\{state\}\}">eq</figure-callout>}}_p}{4\mathrm{\&pi;}{\mathrm{\&epsiv;}}_0\mathrm{kTa}})$

Formula 7

M is the quality of ion in the formula.With t=0, q _p=0 boundary condition carries out integration to formula 7 and then gets the PM0.1 carrying capacity:

$q_p=\frac{2\mathrm{\&pi;}{\mathrm{\&epsiv;}}_0{d}_p\mathrm{kT}}{e}1n(1+\frac{d_p{\mathrm{Ne}}^2\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="HDA00003312951600013.png"\; state="\{\{state\}\}">t</figure-callout>}}{{2\mathrm{\&epsiv;}}_0\sqrt{2\mathrm{m\&pi;kT}}})$ Formula 8

As with ion average speed

The substitution following formula, following formula then is rewritten as

$q_p=\frac{2\mathrm{\&pi;}{\mathrm{\&epsiv;}}_0{d}_p\mathrm{kT}}{e}1n(1+\frac{d_p\stackrel{-}{u}{\mathrm{Ne}}^{2}t}{8{\mathrm{\&epsiv;}}_0\mathrm{kT}})$ Formula 9

In the formula: d _pDiameter for PM0.1; Be ion average speed.Following formula is applicable to particle diameter d _pThe diffusional charging amount of＜0.1 μ m primary particulate is calculated.From formula, as seen, has only the unipolarity of increasing number of ions N, gas temperature T, ion average speed

Charged time t can increase the PM0.1 carrying capacity with primary particulate.Because gas temperature T, the charged time t of primary particulate recruitment are very limited, and unipolarity population N and average speed thereof can become

Order of magnitude formula increases, and can adopt increases unipolarity population N and unipolarity ion average speed method

Increase the quantity of electric charge of PM0.1 primary particulate.

The diffusional charging that the PM0.1 primary particulate below is described in detail in detail increases thick method.

Improve unipolarity amount of ions and movement velocity thereof and be that the PM0.1 primary particulate is charged increases thick key.Be applied on the high-field electrode 11 by high-frequency and high-voltage alternating source 8 output voltages, form between high-field electrode 11 and the earthing pole 10 that high-frequency and high-voltage is charged to increase thick alternating electric field 3, electric-field intensity is 0.8kV～40kV.With concentration up to 10 ¹⁰/ cm ³～10 ¹⁴/ cm ³Unipolarity ion 1(anion or cation) and the gas that contains PM0.1 primary particulate 2 inject long charged thick alternating electric field 3, the i.e. every 1cm of increasing of high-frequency and high-voltage of 0.1m～4m in the lump ³The unipolarity ion reaches 10 in the gas ¹⁰～10 ¹⁴ Individual.Unipolarity ion 1 up to 2km/s, and does 10 with the gap of speed between high-field electrode 11 and earthing pole 10 of 2km/s at the charged average movement velocity that increases in the thick alternating electric field 3 of high-frequency and high-voltage ³～10 ⁴Inferior pumping, its movement locus is shown among Fig. 14.1 collision of each 2 each second of PM0.1 primary particulate and unipolarity ion is charged, and to increase thick opportunity be tens thousand of times, even hundreds thousand of times.The M0.1 primary particulate increases thick track shown among Fig. 15 charged in the alternating electric field.The PM0.1 primary particulate by high-frequency and high-voltage charged increase thick alternating electric field 3 diffusional chargings increase thick after, its particle diameter increases 10～10 ³Doubly, the saturated charged particle diameter＞2 μ m primary particulates 7 that are condensed into.

High-frequency and high-voltage is charged to be increased thick alternating electric field 3 and comprises Al ₂O ₃Thin slice 9, earthing pole 10, high-field electrode 11, its clearance distance are 10cm～60cm; The rectangle pole plate that earthing pole 10, high-field electrode 11 all adopt 304 stainless sheet metals to process.High-frequency and high-voltage alternating source 8 frequency ranges are 80Hz～12kHz, and the output voltage amplitude scope is 10kV～600kV.

The present invention finishes the saturated charged and cohesion of primary particulate with the PM0.1 primary particulate by the high-frequency and high-voltage alternating electric field and increases thick one-tenth particle diameter＞2 μ m primary particulates.This has solved the PM0.1 primary particulate and has captured a purification difficult problem, and slightly provides a kind of feasible, effective new method for the diffusional charging cohesion increases.The present invention also can be applied in the preliminary treatment of dedusters such as electric cleaner, cloth bag, sedimentation, through the charged primary particulate that is condensed into big particle diameter in advance, will increase substantially the purification efficiency of dedusters such as electric cleaner, cloth bag, sedimentation.Simultaneously can dwindle the deduster volume significantly again, reduce rolled steel dosage, and then reduce once investment and operating cost, reduce energy consumption again.

Description of drawings

The invention will be further described below in conjunction with drawings and Examples.

To be that the PM0.1 primary particulate is charged increase thick method principle schematic to Fig. 1.

Fig. 2 is that the alternating electric field frequency is to particle diameter 0.1 μ m primary particle amount occupation rate influence curve figure.

Fig. 3 is that the alternating electric field field intensity is to particle diameter 0.1 μ m primary particle amount occupation rate influence curve figure.

Among the figure: 1 unipolarity ion; 2PM0.1 primary particulate; 3 high-frequency and high-voltages are charged to increase thick alternating electric field; 4 unipolarity ion motion tracks; Increase thick track 5PM0.1 primary particulate is charged in alternating electric field; 6 chargedly increase thick primary particulate; The 7 saturated charged particle diameter＞2 μ m primary particulates that are condensed into; 8 high-frequency and high-voltage alternating sources; 9Al ₂O ₃Thin slice; 10 earthing poles; 11 high-field electrodes.

The specific embodiment

Be described in detail embodiments of the invention below in conjunction with technical scheme and accompanying drawing:

PM0.1 primary particulate of the present invention is charged to increase thick method principle signal as shown in Figure 1.Be applied on the high-field electrode 11 by high-frequency and high-voltage alternating source 8 output voltages, form between high-field electrode 11 and the earthing pole 10 that high-frequency and high-voltage is charged to increase thick alternating electric field 3, with concentration up to 10 ¹⁰/ cm ³～10 ¹⁴/ cm ³Unipolarity ion 1 and the gas that contains PM0.1 primary particulate 2 inject long charged thick alternating electric field 3, the i.e. every 1cm of increasing of high-frequency and high-voltage of 0.1m～4m in the lump ³The unipolarity ion reaches 10 in the gas ¹⁰～10 ¹⁴More than individual.Unipolarity ion 1 does 10 charged the increasing in the thick alternating electric field 3 with the gap of speed between high-field electrode 11 and earthing pole 10 of 2km/s of high-frequency and high-voltage ³～10 ⁴Inferior pumping, 1 collision of each 2 each second of PM0.1 primary particulate and unipolarity ion is charged, and to increase thick opportunity be tens thousand of times, to hundreds thousand of times.The PM0.1 primary particulate increases thick alternating electric field 3 after diffusional charging increases slightly by high-frequency and high-voltage is charged, and its particle diameter increases 10～10 ³Doubly, the saturated charged particle diameter＞2 μ m primary particulates 7 that are condensed into.

The invention process result is shown in Fig. 2,3.From Fig. 2 alternating electric field frequency to the influence curve of particle diameter 0.1 μ m primary particle amount occupation rate as can be known, be under the condition of 5kV/cm in high-frequency and high-voltage electric-field intensity, when the alternating electric field frequency is 10kHz, particle diameter is that 0.1 μ m primary particle amount occupation rate is about 28%, 72% charged having increased slightly of particle diameter 0.1 μ m primary particulate namely arranged, and it is obvious that visible cohesion increases thick effect.From Fig. 3 alternating electric field intensity to the influence curve of particle diameter 0.1 μ m primary particle amount occupation rate as seen, be under the 11kHz condition in high-frequency and high-voltage alternating electric field frequency, when high-frequency and high-voltage alternating electric field intensity is 5kV/cm, particle diameter 0.1 μ m primary particle amount occupation rate is about 28%, as seen under this parameter, have 72% particle diameter, 0.1 μ m primary particulate charged increase thick.

Claims (2)

1. a particle diffusional charging increases thick method, it is characterized in that concentration up to 10 ¹⁰/ cm ³～10 ¹⁴/ cm ³The unipolarity ion injects long 0.1m～4m together with the gas that contains the PM0.1 primary particulate, electric-field intensity is the high-frequency and high-voltage alternating electric field of 0.8kV～40kV; After the PM0.1 primary particulate increased slightly by high-frequency and high-voltage alternating electric field diffusional charging, its particle diameter increased 10～10 ³Doubly, the charged particle diameter＞2 μ m primary particulates that are condensed into.

2. method according to claim 1 is characterized in that, described high-frequency and high-voltage alternating electric field comprises Al ₂O ₃Thin slice (9), earthing pole (10), high-field electrode (11), its clearance distance is 10cm～60cm; The rectangle pole plate that earthing pole (10), high-field electrode (11) all adopt 304 stainless sheet metals to process; High-frequency and high-voltage alternating source (8) frequency range is 80Hz～12kHz, and the output voltage amplitude scope is 10kV～600kV.

Images