Method and Apparatus for Cleaning Exhaust Gas and Reducing Noise by Using High Voltage Electric Field

Technical Field

The present invention relates to a method and an apparatus to clean exhaust gas conveying through the chamber, by burning up granular particles under plasma atmosphere, by removing gaseous materials with negative ions, and by eliminating NOx with ultraviolet rays, which are induced by high voltage electric field. Specifically, the present invention relates to a method and an apparatus which can clean exhaust gas and reduce noise, wherein it comprises the step of burning up the granular particles with corona discharge after changing particles into plasma atmosphere, the step of removing gaseous materials with negative ions, the step of eliminating NOx with ultraviolet rays, and the step of reducing noise.

The main causes of circumstance pollution are smoke and noise produced by industrial equipments and

automobiles .

Especially, diesel engines are used in popular, since it has high power and cost of diesel is low. By the way, in the event of using diesel engines, there occur some problems that diesel engines push out smoke including granular particles, hydrocarbons, NOx, noise and so on, which must be solved to prevent the circumstance pollution.

In order to solve these problems, intensive studies have been carried about cleaning exhaust gas and reducing noise.

Background of Art

Heretofore known methods make use of catalytic filters, electric field and recombustion of exhaust gas.

In DE 3834920, the system has been described, wherein it burns up the deposited carbon particles in ceramic filter with ozone produced by electric field of 20KHz and 20MV.

In WO 9200442, method and device have been described, wherein exhaust gases are taken into a channel of ceramic body where an electric field is generated

across the direction flow, and the soot particles deposited on the walls of the channel are first negatively charged by a discharge electrode and then oxidized by ions adhering to oxygen.

In DE 3314168, the system has been described, wherein neutral particles are divided into two side streams which are directed over electrodes of large surface area, held at opposite potentials.

In DE 3711312, the method and apparatus have been described, wherein particles are removed by being ionized with UV rays and by being collected to the plate.

In US 5074112, an apparatus has been described, wherein a filter disposed within the cavity removes particulate products of combustion from exhaust gases passing the cavity and electromagnetic waves produce heat for incinerating particulate products of combustion.

As shown in the above, one method can be applied to eliminate only a kind of ingredient, and so the other ingredients including NOx and noise are pushed out without eliminating.

Accordingly, the inventors of the present invention invented a method and apparatus for cleaning exhaust gas as well as reducing engine noise.

SUMMARY OF THE INVENTION

An object of this invention is to provide a method and an apparatus for cleaning exhaust gas pushed out from engines or industrial equipments and reduce engine noises.

Specifically, the object of the present invention is to provide method and apparatus which can clean exhaust gas and reduce engine noise, by partitioning the granular particles and noxious materials in exhaust gas, and then by burning up directly the granular particles under plasma atmosphere, by burning up again the minute particles by means of DC voltage and AC voltage, by removing noxious materials with negative ions, by removing NOx by oxidizing it into N0 ₃ with ultraviolet rays and ozone, which can be easily solved in water which is produced by Sellen's effect of PN diode in this apparatus, and by cutting off engine noises and electromagnetic interference.

The apparatus in the present invention is divided into

seven units in order to enhance productivity and efficiency of after-service, which can be used in combination or in separation.

In this invention, partition unit (100) renders exhaust gas to pass through at high speed and burns up particles which has been collected in partition unit (100) In partition unit (100) , to pass exhaust gas at high speed, EHD (electro-hydro dynamics) method and electrostatic method are applied at bottle necked nozzle to accelerate the flow of exhaust gas. The negatively charged particles accelerate much more by voltage difference between ionpin(llθ) and attractor electrode (120) , and therefore staying or slowing down of exhaust gas in a chamber is prevented. The negatively charged particles are attracted by electrostatic force on the collector electrode (130) which is made of a metal mesh(211) and particles which can not pass through the collector electrode (130) of a metal mesh(211) drop down into the manhole where one set of discharge pole (140, 140) are disposed to burn up large particles. In plasma unit (200) , particles passed through collector electrode (130) are burned by using corona process,

wherein small particles are burned by streamer corona generated between plasma unit pole (210) and mesh(211) . In order to clean exhaust gas more efficiently, exhaust gas is conveyed to electron unit (300) after passing through plasma unit (200) . Electron unit (300) burns up minute particles by means of DC voltage and AC voltage. AC high voltage is applied across pole plate (350) and hole plate (310) in order to generate streamer corona to burn up minute particles. DC high voltage is applied across hole plate (310) and ionpin plate (320) to generate electric wind by ionpin(llθ) which pushes particles to hole plate (350) in order to enhance the efficiency of corona discharge between hole plate (310) and pole plate (350) . By the above-mentioned process, granular ingredients of exhaust gas are nearly cleared.

Also, there are noxious chemical materials including NOx in exhaust gas, which are removed with negative ions generated by ionization unit (400) which generates UV rays between plasma jet and opposite electrode (430) , and this UV rays generate lots of negative ions. Noxious materials combine with negative ions and ozones to be changed into other materials. In order to remove NOx which is not removed in the above-mentioned ionization unit (400) , screen unit (600)

is used.

The screen unit (600) comprises ceramic plate A(630) , ceramic plate C(650) and ceramic plate B(640) having hexagonal holes (610) in which PN diode (620) are disposed.

By action of 10K voltage applied across plates, UV rays are generated around hexagonal hole (610) in a large amount, and this UV rays let 0 ₂ to be changed into ozone. In addition, PN diodes (620) cause temperature dropping by Sellen's effect to condensate H ₂ 0 into water.

During above process, the efficiency of removing NOx will be enhanced by taking air into plates. This invention can contain a union unit (700) , which absorbs engine noises and shields electromagnetic wave to be radiated by high frequency. Union unit is used to meet the regulations of EMI, EMC specification of this inventive apparatus. According to the above, this invention can clear exhaust gas and can be substituted for a noise absorber.

Brief Description of the Drawings

This object, and other objects and advantages of the

present invention, will appear more clearly from the following specification in conjunction with accompanying schematic drawing, in which:

FIG.l is an exploded view of the inventive apparatus ,-and FIG.2 (a) is a schematic view showing the working principle of an partition unit ;and FIG.2(b) illustrates a brush corona discharge ;and FIG.3 is an embodiment of a partition unit ,-and

FIG.4 (a) is a schematic view showing the disposition of plasma unit cell and opposite electrode ,-and FIG.4(b) is illustrates a streamer corona discharge through hemispheric plasma unit pole ;and FIG.5 (a) is a detailed view of one set in an electron unit ;and FIG.5(b) is a schematic view to calculate the distance between a dust collector at soot clean-up space ,-and FIG.5(c) is a circuit to supply DC voltage ,-and FIG.5(d) is a circuit to supply DC voltage ;and FIG.6 is an embodiment of the plasma jet to generate a negative ion FIG.7 is an ionization cell mounted on a cell-plate ;and

FIG.8 is a detailed view to show a screen unit ;and FIG.9 (a) is a circuit of high-frequency voltage generator ;and FIG.9(b) is voltage multiplier circuit to multiply voltage applied across a thirdly order coil ;and FIG.10 shows an external view of this invention apparatus

Detailed Description of the Preferred Embodiment

In the following, the present invention will be explained in detail referring to the drawings.

Referring to Fig.l, which shows the entire prospect of the present invention, the present invention comprises a partition unit (100) which renders exhaust gas to pass through at high speed and burns up large particles which have been collected in a partition unit (100) , a plasma unit (200) which burns up directly granular particles by making them into plasma state with streamer corona, electron unit (300) which burns up minute particles by means of DC voltage and AC voltage, a ionic polarization unit (400) which eliminates the noxious materials by generating lots of negative ions, a screen unit (600) which removes NOx by generating

ozone with ultraviolet rays in order to oxidize NOx into N0 ₃ , which can be easily solved in water which is produced by Sellen's effect of PN diode (620) in screen unit (400) , a union unit (700) which reduces engine noises and shields electromagnetic waves irradiated from the above-mentioned unions (100, 200,300, 400, 600) , and high voltage generator (not drawn) to supply high voltage to each unit .

Each unit will be explained in detail in the followings .

A partition unit (100) is shown in detail in Fig.2 and Fig.3. Referring to Fig.2 (a), a partition unit (100) comprises ionpin(llθ) which induces negative high voltage to ionize air and granular particles in exhaust gas, an attractor electrode (120) in a bottle-necked nozzle which induces negative voltage to accelerate exhaust gas, a meshed collector electrode (130) which partitions granular particles, that is, larger particles drop down into the manhole below the meshed collector electrode (130) and small particles are passed through the collector electrode (130) , and discharge poles (140, 140) which burns up the dropped materials in manhole.

Fig.2(b) shows a brush corona which is discharged from ionpin(llθ) to charge the granular particles in exhaust gas.

Fig.3 shows one of the embodiments where above elements (110, 120, 130, 140) are mounted in a partition unit (100) , wherein a partition unit (100) comprises a partition unit plate(180), a ionpin(llθ) which ionizes granular particles, an air inlet hole (150) which takes exhaust gas into channel, a partition unit guider(160) where bottle-necked nozzle is mounted, and a partition unit pole (170) which burns up larger particles which is mounted at discharge poles (140, 140) below a collector electrode (130) in front of a ionpin(llθ) .

Fig.4 (a) shows a unit cell (250) of the plasma unit (200) which is composed of several unit cells, wherein a plasma unit cell (250) comprises several plasma unit pole (210) in hemispheric shape which generate streamer corona to burn up the particles passed through the collector electrode (130) of the partition unit (100) , several pole hole (220) in which the above plasma unit pole (210) are inserted, meshes [211 ; not shown in Fig.4 (a)] which act as a discharge electrode of the plasma unit pole (210) and a ground hole (260) which is

connected to the meshes (211) .

Fig.4(b) shows the streamer corona which is generated between the plasma unit pole (210) in the plasma unit cell(250) and meshes(211) .

Fig.5 (a) shows one set of a electron unit (300) which is composed of several units. One set of the electron unit (300) has a ionpin plate (320) , a hole-plate (310) and pole-plate (350) , wherein the ionpin plate (320) applied negative high voltage comprises many ionpin(110) which ionize the minute particles and generate electron wind, and many air inlet hole (150) which gas pass through, a hole-plate (310) with many air inlet hole (150) mounted on meshes (211) which act as discharge electrode for streamer corona, and a pole- plate (350) with many air inlet hole (150) and many plasma unit poles (210) which generate streamer corona to burn up the particles.

Fig.5(b) shows the embodiment that the above plates (310, 320, 350) are disposed in a electron unit (300) . Practically, the efficiency of cleaning exhaust gas depends on size, shape, disposition of the plates (310,

320, 350) and applied voltage and current.

The appropriate area of cleaning exhaust gas in a electron unit (300) is characterized by : S = WNH wherein distance between plates (310, 320, 350) is W, the height of plates (310, 320, 350) is H, the amount of exhaust gas is , and the cross-sectional area for cleaning exhaust gas is S, if space is composed of n plates.

The space between plates (310, 320, 350) is lane, and the an area of one lane is 2LH so that the total area of cleaning exhaust gas in a electron unit (300) is as the followings. A = 2NLH

DC-7KV is applied to each ionpin plate (320) and hole- plate (310) to ionize the minute particles by a ion pin(110) on the ionpin plate (320) and then to deposit the ionized particles on the meshes (211) of the a hole- plate (310) and to cause electron wind between a ionpin plate (320) and a hole-plate (310) .

AC 10KV is applied to pole plate (350) to generate streamer corona to burn up the particles collected on meshes (211) .

Fig.5(c) is a circuit which supplies DC voltage to an ionpin (110) mounted on an ionpin unit plate(320) , comprises a transformer (T) to multiply voltage, a rectifying diode (Dl, D2) , a filtering resistor (Rl, R2) to attenuate ripple signal, resistor (R3) the time constant of this circuit and capacitor (Cl) which determine the time constant of this circuit .

FIG.5(d) is another circuit which supplies DC voltage to an ionpin (110) mounted on a ionpin unit plate (320) . A circuit comprises a transformer (T) to multiply voltage, a rectifying diode(D3) , resistor(R6) and capacitor (C2) which determine the time constant of this circuit when positive voltage is applied, and resistor (R6) and capacitor (C2) which determine the time constant of this circuit when negative voltage is applied.

Here, Electric field(E) generated at a ionpin (110) V

E =

R(RC/RD) V : voltage applied at a ionpin(110)] R : the radius of corona discharge generated at a ionpin (110)

RD : the radius of discharging current generated at

an ionpin (110) RC : the radius of meshes (211) set up on an air inlet hole (150) .

Referring to Fig.6, the ionization unit (400) comprises many ionization cells (405) composed of an inner pipe (410) and an outer pipe (420) where gas passes through at high speed, and an opposite electrode (430) applied with high voltage. And the point end(406) of each ionization cell (405) is disposed between opposite electrodes (430) .

Referring to Fig.7, the ionization unit (400) comprises a cell plate (409) on which several ionization cell (405) mounted, and hole-plate (310, shown in Fig.l) which acts as an opposite electrode (430) .

Fig.8 shows one set of screen uni (600) which is composed of several sets. One set of screen unit has plate A(630), plate B(640), and plate C(650), wherein it comprises plate A(630) and plate C(640) having several hexagonal holes (610) which generate UV rays to render 0 ₂ into ozone and then NOx into N0 ₃ , and plate B(640) having several PN diodes (620) to generate H ₂ 0 by dropping down the temperature of exhaust gas resulted

from Sellen's effect.

Fig.9 (a) shows a high-frequency voltage generator, wherein it comprises a firstly order coil applied with AC voltage, a transistor (T) to amplify signal, bias resistor (R7) to stabilize operation, a thirdly order coil applied with high voltage according to the turns ratio, a secondly order coil to modulate carrier having 50KHz-100KHz, a voltage multiplier circuit (D5) , and capacitor (C5) to charge a thirdly order voltage.

Fig. 9(b) shows a voltage multiplier circuit (D5) in detail shown in Fig.9(a) , which comprises a thirdly order coil to induce high voltage according to turns ratio, diode (D10, ... ,D80) to rectify AC voltage, high voltage is charged across capacitor (C5, ... ,C70) . And the equivalent circuit of a voltage multiplier circuit (D5) is shown.

Fig.10 shows the entire external form the present invention, which is housed with metal in order to cut off the outer impact and to prevent irradiating engine noise and electromagnetic waves caused by each unit. The outlet of the case is forwarded to the ground.

Finally, a union unit (700) in Fig.l absorbs noise and shields electromagnetic waves, wherein it comprises a secondly order ferrite core to meet the regulations for noise absorber, EMI and EMC.

The operation of the apparatus in the present invention will be explained in the followings.

Partition unit (100) takes exhaust gas pushed out from an engine and sends it to a plasma unit (200) fluently. In a partition unit (100) , EHD (electro-hydro dynamics) method is applied between inhaling site(a-a) and exhaling site (b-b) to accelerate the flow of exhaust gas and electrostatic method of Coulomb's force is used.

Exhaust gas mixed with air is inhaled into a partition unit (100) , and the granular particles in exhaust gas are decomposed and ionized into negatively. The negatively charged particles pass through a bottle- necked nozzle, where the speed of the gas accelerates by means of EHD method.

In addition, negatively charged particles accelerates much more by voltage difference between a ionpin(110) and an attractor electrode (120) induced negatively, and

this phenomena prevent exhaust gas from staying or slowing down in the partition unit (100) . We call the above process as EHD (electro-hydro dynamics) method. Exhaust gas after passing through a nozzle is diffused to a collector electrode (130) , where the diffusion theory of waveguide is applied. That is, exhaust gas diffused after passing through the narrow space can spread widely without slowing down the speed. The negatively charged particles are attracted by electrostatic force on the collector electrode (130) which is made of metal mesh and larger particles which can not pass through the collector electrode (130) of metal mesh(211) drop down into the manhole where one set of discharge poles (140, 140) are disposed to burn up large particles.

While large particles in exhaust gas are eliminated by burning up in a manhole where small particles may pass through the collector electrode (130) . It is preferred that a partition unit pole (170) has a round head in shape to increase ignition energy.

The high speed of exhaust gas is helpful in preventing the collector electrode (130) filled up with small particles.

In a plasma unit (200) , particles are burned by applying

plasma process, where plasma means that particles are divided into positive and negative particles, of which the amounts are the same, and therefore they show neutral state in total. Small particles which can pass through the collector electrode (130) burn up in a plasma unit cell (250) by streamer corona generated between a plasma unit pole (210) applied with + voltage and mesh(211) applied with - voltage. In the present invention, the streamer corona is generated by using a hemispheric plasma unit pole (210) . By using a hemispheric plasma unit pole, a large amount of streamer corona can be generated.

When the high voltage is applied for a short time, particles in exhaust gas are charged and burned up by flame discharge which occurs between a plasma unit pole (210) and mesh(211) . In addition, particles oscillate due to property of attracting each other by electrostatic force and this prevents the meshed net (211) filled up with particles. Further, electrons oscillate in plasma state, and electron's oscillation frequency enhance the particles oscillation. Oscillation frequency(f _k ) is characterized by;

f _k = 8.9 x IOVN , where N is electron density and oscillation frequency depends on air pressure.

In order to clean exhaust gas more efficiently, exhaust gas is conveyed to electron unit (300) after passing through plasma unit (200) .

The air inlet hole (150) of hole plate (310) in plate set is composed of metal meshed net [211, not drawn in Fig.5 (a)] through which exhaust gas can flow freely, and metal meshed net (211) acts as discharge electrode. AC high voltage is impressed to pole plate (350) and hole plate (310) in order to generate streamer corona to burn up minute particles. And oscillating AC voltage prevents the metal meshed net [ 211, not drawn in Fig.5 (a)] filled up with particles.

DC high voltage is impressed across hole-plate (310) and ionpin plate (320) to generate electric wind by ionpins(llθ) on the ionpin plate (320) which pushes particles to hole plate (350) in order to enhance the efficiency of corona discharge between hole plate (310) and pole plate (350) .

The above-mentioned process will be explained systematically in the following.

The noxious materials in exhaust gas are nearly cleared by several steps, wherein large particles are first removed in partition unit (100) , and then small particles passed through the partition unit (100) are removed in plasma unit (200) by streamer corona, and then minute particles are eliminated in electron unit (300) .

There are noxious chemical materials in exhaust gas, and two different methods are used to remove noxious chemical materials in the present invention. First, noxious materials are removed with negative ions generated by ionization unit (400) . Ionization unit (400) which generates ultraviolet rays between outer pipe (420) and opposite electrode (430) , and this ultra-violet rays generate lots of negative ions. While the general negative-ion generator has a pointed- end in order to produce negative ions, negative ion generator of the present invention has an ionization cell (405) structure which has inner cylindrical wall dividing the space into two routes, that is, inner pipe (410) and outer pipe (420) in addition to the known form. By the above-mentioned ionization cell (405) structure, the negative ion generator of the present invention emits more negative ions several thousand

times than the usual negative ion generator, while the noxious gases passing through at very high speed. We call this method as plasma jet, where the appropriate distance between outer pipe (420) and opposite electrode (430) should be maintained in order to generate negative ions in a large amount. Corona is also generated at the pointed end of plasma jet, and its temperature is 800°C-1500°C. The noxious material molecules are excited by ultra- violet rays and the excited noxious materials combine negative ions and ozones to be changed into other materials. And in this process noxious positive ions are also removed.

In order to remove NOx which is not removed in the above-mentioned ionization unit (400) , screen unit (600) is used in the present invention.

The screen unit (600) comprises ceramic plate A(630) , ceramic plate C(650) and ceramic plate B(640) having hexagonal holes (610) in which PN diodes (620) are disposed.

When 10K voltage is impressed to plates, ultra-violet rays are generated around hexagonal hole (610) in a large amount, and ultra-violet rays let 0 ₂ be changed into ozone.

Ozone is generated in a large amount when thickness of metal is 20μm-30μm

The impedance matching is important, since the printed metal may be separated from ceramic plate, if higher voltage than 1KV is impressed for a long time.

Also the separation of the printed metal from ceramic plate can be prevented by scratching the ceramic plate.

Such an apparatus has been used for sterilization of food or for generator of ozone, but it has been never used for eliminating of smoke.

In addition, PN diodes (620) mounted in hexagonal holes (610) of plate B(640) cause temperature dropping by Sellen's effect to condense H ₂ 0 into water.

Ultra-violet rays are generated in a large amount when high voltage is impressed to the plate A(630) and plate C(650) , and this ultra-violet rays make oxygen into ozone which renders NOx into N0 ₃ which can be easily solved in water.

During this process, the efficiency of removing NOx will be enhanced by taking air into plates. The method of dropping temperature by using PN diodes (620) is called as Sellen's effect and this method has been used for refrigerator, but has never

been used for eliminating smoke.

In the present invention, PN diodes (620) are connected in serial and parallel to induce Sellen's effect. The operating voltage is 0.7V.

Accordingly, the number of diode which is needed, N, is specified as;

DC voltage (V)

N = 0.7V

Most of noxious chemical gas in exhaust gases is removed in an ionization unit (400) and a NOx, which is not filtered in an ionization unit, is removed through a screen unit (600) .

Therefore, the granular ingredients and noxious chemical gas of exhaust gases are completely purified.

A high voltage generator with a high frequency comprises by a high frequency oscillator and a high voltage rectifier with transformer.

The high voltage generator with a high frequency of this invention supplies positively and negatively polarized high voltage. A high voltage generator in the present invention is different from the usual one in the point that it has

a special circuit which needs an isolation strength and a feedback circuit to shutdown a firstly order coil voltage, if a secondly order coil is abnormal.

This high voltage generator shown in FIG 9(a) comprises a transistor to amplify a modulated signal, a thirdly order coil to induce a high voltage, a secondly order coil to shutdown a firstly order coil voltage, when second orderly coil does not work well, a capacitor (C5) to charge voltage, and a voltage multiplier circuit (D5) to multiply a voltage.

A voltage multiplier circuit (D5) is used to multiply voltage needed for the above-mentioned units (100, 200, 300, 400, 600), wherein E is a charged voltage across a capacitor (C5) , 2E is a charged voltage across a capacitor (CIO) , 3E is a charged voltage across a capacitor(C20) , 4E is a charged voltage across a capacitor(C30) , 5E is a charged voltage across a capacitor (C40) , 6E is a charged voltage across a capacitor (C50) , 7E is a charged voltage across a capacitor (C60) , 8E is a charged voltage across a capacitor (C70)

A ceramic resistor filter (R100) is used to prevent circuit breakdown, and to avoid dangerous situation which are caused by the remained high voltage across

capacitor (CIO, - ^• -, C70) in case of a thirdly order coil voltage "OFF".

As modulating a carrier (400KHz) and a signal (50KHz-

100Hz) at a secondly order coil, a transistor outputs specially high voltage without excessive current .

To reverse an output voltage polarity, the connection of diode (D10, •• • ,D80) is reversed.

As E is a charged voltage across a capacitor (C5) , discharge voltage (Vo)

This invention can contain a union unit (700) , which comprises a mechanical-electric filter, to absorb engine noises and to shield electromagnetic waves to be radiated from corona discharge process. Namely, this unit is used to meet the regulations of EMI, EMC specification of this inventive apparatus. By inserting ferrite cores into metal house and by winding wire around ferite cores, this unit (700) shields EMI and EMC. To shield EMI, EMC effectively, a wide range L and C with resonant frequency is recommended.

As above-mentioned, this invention relates to a method

and an apparatus to clean exhaust gas of an internal combustion engine, an external combustion engine and anti-pollution equipments an so on. As this invention can clean exhaust gas and reduce noises, it can be substituted for a noise absorber, for example, the muffler of automobiles.