WO2003092868A1 - Hybrid apparatus and method for removing volatile organic compounds and odorous substances by electron beam and catalyst - Google Patents

Hybrid apparatus and method for removing volatile organic compounds and odorous substances by electron beam and catalyst Download PDF

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Publication number
WO2003092868A1
WO2003092868A1 PCT/KR2003/000876 KR0300876W WO03092868A1 WO 2003092868 A1 WO2003092868 A1 WO 2003092868A1 KR 0300876 W KR0300876 W KR 0300876W WO 03092868 A1 WO03092868 A1 WO 03092868A1
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Prior art keywords
electron beam
catalyst
case
volatile organic
organic compounds
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PCT/KR2003/000876
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French (fr)
Inventor
Jo-Chun Kim
Young Sunwoo
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Jo-Chun Kim
Young Sunwoo
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Priority to AU2003224483A priority Critical patent/AU2003224483A1/en
Publication of WO2003092868A1 publication Critical patent/WO2003092868A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/007—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by irradiation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/86—Catalytic processes
    • B01D53/88—Handling or mounting catalysts
    • B01D53/885—Devices in general for catalytic purification of waste gases
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/70—Organic compounds not provided for in groups B01D2257/00 - B01D2257/602
    • B01D2257/708—Volatile organic compounds V.O.C.'s
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/90—Odorous compounds not provided for in groups B01D2257/00 - B01D2257/708
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2259/00—Type of treatment
    • B01D2259/80—Employing electric, magnetic, electromagnetic or wave energy, or particle radiation
    • B01D2259/812—Electrons
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
    • Y02C20/00—Capture or disposal of greenhouse gases
    • Y02C20/20—Capture or disposal of greenhouse gases of methane

Definitions

  • the present invention relates to a hybrid apparatus and method for removing volatile organic compounds and odorous substances by an electron beam and a catalyst, and more particularly, to a hybrid apparatus and method which effectively remove these contaminants even in an environment with a small amount of electron beam energy by utilizing a hybrid action of the electron beam and the catalyst.
  • the adsorbent in the catalyst by forming the adsorbent, such as a granular activated carbons or ceramics capable of adsorbing volatile organic compounds and various hazardous gases, also serves as a carrier of the catalyst in a reactor which the electron beam is irradiated onto.
  • volatile organic compounds have been treated as air pollution sources for a long time which have a harmful effect on human health and the environment.
  • the volatile organic compounds (VOCs) are various and wide in kinds, so thousands of chemical substances belong thereto. Besides, they are strongly flammable, which is the cause of safety accidents caused by fire and explosion.
  • the volatile organic compounds mainly includes BTEX(benzene, toluene, ethylbenzene and xylene), PCE, TCE, CHC, halogen group and non-halogen group chlorine and the like. These compounds are highly chemically reactive and are highly carcinogenic, so their regulation is absolutely needed and there is an urgent need for an economic control method. Additionally, the volatile organic compounds (VOCs) are known as contaminants which are fairly anesthetic as well as strongly movable and odor-inducing. Moreover, they have potential toxicity and carcinogen, and photochemically react with nitric oxide and other compounds to form ozone. As such, a special interest is being concentrated on the environmental contamination caused by these compounds. To overcome the above problems, every work place is working hard with a great deal of labor with respect to the selection and application of proper preventive techniques. Above all things, economic efficiency and safety in work places are required.
  • the volatile organic compounds are, for the most part, volatile organic compounds exhausted from painting and petrochemical facilities, even if gases exhausted from traveling automobiles are excluded. Thus, at present, there is an absolute need for control of volatile organic compounds for these industrial facilities and processes.
  • thermal NOx may be produced and much carbon dioxide (CO 2 ), a greenhouse gas, may be generated.
  • adsorbability is gradually reduced according to the number of times of regeneration of an adsorbent, thus the adsorbent has to be frequently replaced, thereby increasing the cost. Further, because the filtration of particulate matters using a preprocessing apparatus is needed, the operating and maintenance costs increase.
  • Figs, la and lb are views showing a VOC removal apparatus according to one example of the conventional art.
  • a volatile organic compound removal apparatus 100 according to the conventional art is provided with a rectangular, enclosed case 120, the case 120 having at the top surface a reactor irradiation film (not shown) composed of alloys of thin films for irradiating an electron beam, the inner peripheral surface of the case 120 being coated with a reflecting member 120a for making the reflection of the electron beam easily done.
  • an electron beam accelerator 110 for irradiating an electron beam is provided at a position spaced apart from the top surface of the reactor irradiation film at a predetermined distance. While, an inlet pipe 122 for introducing volatile organic compounds is formed at a predetermined portion of the outer peripheral side of the case 120 and an outlet pipe 124 for discharging volatile organic compounds is formed at a predetermined portion of the lower surface thereof.
  • the case 120 is formed with an inclined plane at a predetermined angle at both lengthwise side faces.
  • an adsorbent supporting net 128 is installed for mounting an adsorbent 130.
  • an rectangular supporting protuberance 126 which projects from the case 120 toward the center of the inside thereof, is formed for fixing the supporting net 128 to a predetermined height.
  • the activated carbon In the activated carbon, if a solid surface is contacted onto a fluid for a long time, a specific component on the fluid gathers on the solid surface and the concentration in the fluid and the concentration of the solid surface becomes different. This phenomenon is called adsorption. At this time, the concentration in the fluid and the concentration of the solid surface forms equilibrium if the chemical potential of both phases is proper and reach the adsorption equilibrium relation. Also, such a relation is much influenced by a temperature.
  • the adsorption in the activated carbon is achieved by the following principle.
  • the activated carbon particle has a binary structure of micro pores (less than 2nm) dominating the adsorption and macro pores (a few ⁇ m) formed with the voids of micro particles.
  • the diameter of the granular activated carbon is a few mm and adsorbate molecules are diffused from the outside of the particle to reach the adsorption point in this particle, and thus the adsorption is achieved through various routes.
  • One of the routes is a serial diffusion in which the adsorbate molecules are transferred to the middle of the fluid filling the macro pores by diffusion and are adsorbed in the micro pores by diffusion.
  • Another diffusion type is a surface diffusion in which the molecules in the adsorption state on the surface in the adsorbent are transferred to an adjacent adsorption point.
  • the volatile organic compounds introduced through the inlet pipe 24 are firstly composed by an electron beam irradiated from the upper part of the case 120. Then, as they are repetitively desorbed by the adsorbent 130 mounted on the supporting net 128, they are concentrated and secondarily decomposed by an electron beam. The residual gas from which the volatile organic compounds are removed is discharged through the outlet pipe 124.
  • the above-described volatile organic compound removal apparatus using the electron beam and the adsorbent is problematic in that, when the volatile organic compounds are adsorbed, desorbed and removed, they are easily removed if the energy of an irradiated electron beam is large, while they are more focused on adsorption and desorption than removal if the energy of the electron beam is small.
  • the volatile organic compound removal apparatus using an electron beam alone is problematic in that it is very difficult to decompose materials having a stable structure but a small bonding energy, such as methane.
  • a third decomposition is occurred by mounting a plurality of adsorbents having self-catalytic characteristics on the top surface of the catalyst plate and making the volatile organic compounds repeat adsorption and desorption.
  • a metal plate with good heat transfer and heat resistance is located on the top surface of the catalyst plate so that the corresponding metal plate can hold the latent heat of the electron beam by electron beam irradiation and then transfer the corresponding latent heat to the catalyst plate, thereby stimulating the action of the catalyst plate.
  • the apparatus further comprises: a heater line embeded on an inner side wall of the case for increasing the temperature of internal air and thus increasing the efficiency of the catalyst plate; and a temperature sensor for detecting the temperature of the internal air of the case.
  • FIGS. 1 a and lb are views showing a VOC removal apparatus in accordance with one example of the conventional art
  • Figs. 2a and 2b are perspective views illustrating the profile of a hybrid apparatus for removing volatile organic compounds and odorous substances by an electron beam and a catalyst in accordance with an embodiment of the present invention
  • Figs. 3a and 3b are side sectional views illustrating the hybrid apparatus for removing volatile organic compounds and odorous substances by an electron beam and a catalyst in accordance with the embodiment of the present invention
  • Figs. 4 and 5 are graphs showing the comparison of the removal efficiencies obtained when an electron beam alone acts for styrene and toluene, when a ceramic catalyst alone acts therefor and when the ceramic catalyst and the electron beam act therefor as a hybrid;
  • Fig. 6 is a graph showing a change in temperature of a ceramic catalyst layer in a reactor according to an irradiation dose
  • Fig. 7 is a graph showing the CO 2 conversion rate of volatile organic compounds by the electron beam and the catalyst in the reactor according to an irradiation dose
  • Fig. 8 is a graph showing the comparison of removal efficiencies of volatile organic compounds between a ceramic catalyst carried with platinum and a general ceramic catalyst in accordance with the embodiment of the present invention
  • Fig. 9 is a graph showing the comparison of removal efficiencies between a ceramic catalyst and a ternary ceramic catalyst with respect to a current change in accordance with the embodiment of the present invention
  • Figs. 10 and 11 are graphs showing the removal efficiencies of odorous substances, methyl disulfide (DMDS) and methyl sulfide (DMS), by the application of the hybrid system in accordance with the embodiment of the present invention.
  • Figs. 12a and 12b are views illustrating the profile and side section of the hybrid apparatus for removing volatile organic compounds and odorous substances by an electron beam and a catalyst in accordance with another embodiment of the present invention.
  • Figs. 2a and 2b are perspective views illustrating the profile of a hybrid apparatus for removing volatile organic compounds and odorous substances by an electron beam and a catalyst in accordance with one embodiment of the present invention.
  • Figs. 3 a and 3b are side sectional views illustrating the hybrid apparatus for removing volatile organic compounds and odorous substances by an electron beam and a catalyst in accordance with one embodiment of the present invention.
  • the hybrid apparatus 200 for removing volatile organic compounds and odorous substances by an electron beam and a catalyst in accordance with an embodiment of the present invention has a case 220 whose sides are formed in the same inclined plane as the case 120 of a conventional volatile organic compound removal apparatus 100 or are formed perpendicular. A detailed explanation thereof will be stated later.
  • the case 220 is constructed in a manner that an electron beam can be diffused and irradiated from the inside of the case 220 when the electron beam is irradiated from the upper end.
  • a reactor irradiation film 212 formed of titanium alloys is provided at the top surface of the case 220, and a reflecting member (not shown) is coated on the inner peripheral surface of the case 220 for making the reflection of the electron beam easily done.
  • an electron beam accelerator 210 for irradiating an electron beam is located at a position spaced apart from the top surface of the reactor irradiation film 212 at a predetermined distance. While, at a predetermined portion of the outer peripheral side of the case 220, an inlet pipe 222 is formed which introduces volatile organic compounds from exhaust ports of plants or others through various kinds of pipelines, and at a predetermined portion of the lower surface thereof, an outlet pipe 224 is formed for discharging the residual gas of removed volatile organic compounds.
  • the outlet pipe 224 may be installed at a predetermined portion of a side face of a lower part of the case 220 instead of being installed on the bottom face of the lower part thereof.
  • a supporting net 228 for mounting a catalyst plate 232 is installed at a position spaced apart from the inner bottom face of the case 220 at a predetermined distance.
  • an adsorbent 230 is additionally arranged on the top surface of the catalyst plate 232 for thereby performing the function of removing complex volatile organic compounds.
  • a fixed jaw 226 is formed below the supporting net 228 at an inner wall of the case 220 for supporting the catalyst plate 232 to a predetermined height.
  • the thus-constructed hybrid apparatus 200 for removing volatile organic compounds and odorous substances by an electron beam and a catalyst carry out hybrid decomposition and removal, such as decomposition and activation of contaminants by an electron beam, pyrolysis by the catalyst plate 232 and repetitive adsorption and desorption by the adsorbent 230.
  • an additional metal plate (not shown) with good heat transfer and heat resistance and of a small sphere shape is located at the top surface of the catalyst plate 232 so that the corresponding metal plate holds the latent heat of an electron beam and thereafter transfer the corresponding latent heat to the catalyst plate 232 by electron beam irradiation, thereby stimulating the action of the catalyst plate 232.
  • the substance such as styrene is removed relatively well by the electron beam, it is made to be maximally removed by the electron beam by increasing a reactor space and then is completely oxidized by passing the catalyst plate 232. Namely, by forming the case 220 in a pyramid shape, the electron beam irradiation space is maximized down to the lowermost surface of the case 220 and the atmospheric layer of introduced volatile organic compounds becomes wider. Therefore, it is more expected that the electron beam can completely oxidize the unsaturated systems, such as toluene, xylene and styrene, which have a large bonding energy, at least one functional group and a double bond.
  • unsaturated systems such as toluene, xylene and styrene
  • the side faces of the case 220 are formed perpendicular and a heat storage member (not shown) is attached to an inner side face thereof. Therefore, the air in the reactor, i.e., the hybrid apparatus 200 for removing volatile organic compounds and odorous substances by an electron beam and a catalyst, is preheated to thus increase the efficiency of removing the volatile organic compounds.
  • the catalyst plate 232 is not activated by itself, but brings about a strong pyrolysis when activated by an external energy source. Therefore, the electron beam irradiated from the upper part of the hybrid apparatus 200 for removing volatile organic compounds and odorous substances by an electron beam and a catalyst of the present invention brings about a first decomposition at the upper part of the reactor, and the residual energy of the electron beam acts as an activation energy of the catalyst plate 232 and brings about a second decomposition of the contaminants adsorbed to the adsorbent 230.
  • the adsorbent 230 exemplified in the hybrid apparatus for removing volatile organic compounds and odorous substances by an electron beam and a catalyst according to one embodiment of the invention can be carried in the catalyst plate 232 for use or can be coated on the surface of the catalyst plate 232 for use. Also, in the present invention, the adsorbents having self-catalytic characteristics, such as activated carbon, can be used.
  • adsorbent material of the activated carbon or ceramic system as a carrier. More preferably, on the inner side face of the vertical case 220, a reflecting member (not shown), upon which the electron beam is irradiated, is attached or a catalyst (not shown) is coated, thereby increasing the efficiency of oxidization by the catalyst.
  • Figs. 4 and 5 are graphs showing the comparison of the removal efficiencies obtained when an electron beam alone acts for styrene and toluene, when a catalyst (Pt Ceramic) alone using ceramic as a carrier acts therefor and when the ceramic catalyst and the electron beam act therefor as a hybrid.
  • Such a removal reaction is shown because the catalyst becomes active at a predetermined temperature and thus serves to reduce the activation energy (energy required for removal reaction) much more for main removal sections of the removal reaction.
  • the electron beam, activated carbons and catalyst, which are means for removing volatile organic compounds, suggested by the present invention make it easier to remove the volatile organic compounds while performing a complementary action.
  • the apparatus for removing volatile organic compounds by the catalyst can very easily remove the materials having a small bonding energy but a stable structure, such as methane.
  • the use of a hybrid process of the electron beam and the catalyst can remove the volatile organic compounds more effectively.
  • the materials such as methane, ethane and propane has a much smaller bonding energy and a more stable chemical structure than the materials such as benzene, toluene, xylene and styrene.
  • the catalyst can perform removal and decomposition more effectively.
  • the materials such as toluene, xylene and styrene are expected to serve as the electron beam more effectively since they are unsaturated systems having at least one functional group and a double bond though they have a larger bonding energy than the above-described three materials.
  • this can be confirmed by experiments.
  • aromatic compounds such as benzene, toluene, xylene and styrene
  • the bonding energy becomes higher in order of styrene, xyelne, toluene and benzene, and thus the degree of decomposition by the electron beam becomes higher in the above order.
  • the degree of decomposition by the catalyst becomes higher as the bonding energy is smaller, that is, in order of benzene, toluene, xylene and styrene. Therefore, the present invention is suggested so as to acquire the optimum decomposition rate by employing the hybrid removal apparatus using the catalyst and the electron beam.
  • the electron beam reaction, the adsorption and decomposition and the heat decomposition by the catalyst have a complementary action.
  • Fig. 9 is a graph showing the comparison of removal efficiencies between a pt ceramic catalyst and a ternary ceramic catalyst with respect to a current change in accordance with the embodiment of the present invention.
  • the application of the platinum catalyst shows a higher removal efficiency than that of the ternary catalyst.
  • the application of both electron beam and catalyst shows a 20% increase in removal efficiency compared to the application of only the electron beam.
  • the catalyst of the invention includes not only the platinum or ternary catalyst but also all metal catalysts.
  • the materials such as a ceramic serving as a carrier of the catalyst are inclined to store heat, and they are more suitable for increasing the temperature in the reactor.
  • volatile organic compounds to be processed are inputted into the removal apparatus 200 through the inlet pipe 222.
  • the adsorbent 230 mounted at a predetermined height and carried with a catalyst is formed in the removal apparatus 200, and volatile organic compounds are adhered to the surface thereof.
  • the electron beam accelerator 210 is driven so that an electron beam of a predetermined irradiation dose can be irradiated on the surface of the adsorbent 230 carried with the catalyst. That is, in this case, the adsorbent can perform both adsorption function and catalyst function by incorporating the catalyst into the adsorbent 230.
  • the electron beam it has an advantage that it can easily decompose unstable odors and VOCs such as styrene having the same functional group (for example, methyl group) as a double bond even though its bonding energy is much larger than methane.
  • VOCs such as styrene having the same functional group (for example, methyl group)
  • the electron beam can process odors and VOCs more easily through a radical reaction such as OH- radicals.
  • Table 1 shows a change in reaction constant of OH-radicals according to a change in bonding energy of each individual volatile organic compound. Even in case of a volatile organic compound with a large bonding energy, it can be seen that decomposition and removal are easily performed through the apparatus for removing volatile organic compounds by a catalyst using an adsorbent as a carrier according to the present invention.
  • methane (CH 4 ) is a simple ring type with no double bond and benzene (C 6 H 6 ) has two double bonds and is of ring type.
  • toluene (C 7 H 8 ) has a (C 6 H 5 )-CH 3 bond
  • o-xylene (C 8 H n ) has a (CH 3 )-(C 6 H 5 )-(CH 3 ) bond
  • m-xylene (C ⁇ ⁇ ) has a (CH 3 )-(C 6 H 5 )-(CH 3 ) bond
  • p-xylene (C 8 H n ) has a (CH 3 )-(C 6 H 5 )-(CH 3 ) bond.
  • the volatile organic compounds having such a bonding structure are decomposed through a radical reaction such as OH-radicals as illustrated in Fig. 1.
  • a radical reaction such as OH-radicals as illustrated in Fig. 1.
  • Table 1 it can be seen that the volatile organic compounds having a large reaction constant of OH-radicals are easily decomposed even though their bonding energy is large. Besides, it can be seen that, as the number of functional group is larger, the compounds are well decomposed.
  • Figs. 10 and 11 are graphs showing the removal efficiencies of odorous substances, methyl disulfide (DMDS) and methyl sulfide (DMS), by the application of the hybrid system.
  • odorous substances including methyl disulfide (DMDS) and methyl sulfide (DMS) also show very high removal efficiency in an electron beam area to which a low energy is applied.
  • Figs. 12a and 12b are views illustrating the profile and side section of the hybrid apparatus 200' for removing volatile organic compounds and odorous substances by an electron beam and a catalyst in accordance with another embodiment of the present invention.
  • a vacuum case 240 is preferably provided between a case 220 and an electron beam accelerator 210 for making the electron beam to be directly irradiated from the electron beam accelerator 210 into the case 220 without reacting with external air.
  • the vacuum case 240 gives a synergy effect on the permeability of the irradiated electron beam and makes the electron beam not to react with external air, and this does not cause ozone generation. Therefore, the hybrid apparatus 200' for removing volatile organic compounds and odorous substances by an electron beam and a catalyst in accordance with another embodiment of the present invention has a higher removal efficiency of volatile organic compounds.
  • a temperature sensor 250 is attached to a predetermined portion of an inner side wall of the reactor case 220 and a heater line 252 is embedded along the inner side wall (or along the inner circumferential face of the inlet pipe 222).
  • the heater line 252 is embedded along the inner circumference of the inlet pipe 222, the volatile organic compounds input into the case 220 via the inlet pipe 222 are firstly preheated as they pass through the inlet pipe 222.
  • the electron beam is provided with an adsorbent such as activated carbon or ceramic serving as a carrier of the catalyst, and thus the decomposition by the electron beam, the decomposition by the adsorbent and the pyrolytic reaction by the catalyst perform a complementary action on various contaminant gases, odors and volatile organic compounds.
  • an adsorbent such as activated carbon or ceramic serving as a carrier of the catalyst
  • the hazardous gaseous materials can be removed very effectively in small-sized facilities using a small energy, as well as large-sized facilities such as petrochemical processes, coating processes, paint plants, refining plants, sewage disposal plants, refuse combustion and disposal facilities from which a variety of hazardous gaseous materials including volatile organic compounds, odors, dioxin or nitrogen oxides. Besides, a relatively small energy is consumed for removing contaminants, and thus the apparatus and method are very economic.

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  • Environmental & Geological Engineering (AREA)
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Abstract

The present invention discloses a hybrid apparatus for removing volatile organic compounds and odorous substances by an electron beam and a catalyst. The apparatus comprises: an electron beam accelerator for irradiating an electron beam downward; a case having an inlet pipe and an outlet pipe connected respectively on a side face and a bottom face or the opposite side face of a bottom part; a supporting net for mounting a catalytic plate therein; a reactor irradiation film composed of a thin film such as titanium adhered to the upper part of the case for irradiating the electron beam; and a catalyst plate formed of a rectangular plate of a predetermined thickness and arranged to reduce an activation energy required for removal of volatile organic compounds, wherein the irradiated electron beam brings about a first decomposition on the upper layer in the case and the residual electrons of the electron beam brings about a second decomposition of various hazardous gas molecules by activating the catalyst plate.

Description

HYBRID APPARATUS AND METHOD FOR REMOVING VOLATILE ORGANIC COMPOUNDS AND ODOROUS SUBSTANCES BY ELECTRON
BEAM AND CATALYST
TECHNICAL FIELD
The present invention relates to a hybrid apparatus and method for removing volatile organic compounds and odorous substances by an electron beam and a catalyst, and more particularly, to a hybrid apparatus and method which effectively remove these contaminants even in an environment with a small amount of electron beam energy by utilizing a hybrid action of the electron beam and the catalyst. The adsorbent in the catalyst by forming the adsorbent, such as a granular activated carbons or ceramics capable of adsorbing volatile organic compounds and various hazardous gases, also serves as a carrier of the catalyst in a reactor which the electron beam is irradiated onto.
BACKGROUND ART
As generally known, with the rapid development of the industry and with an increase of the use of various kinds of coating materials, the structure of pollution sources are changing, whereby the kinds of air pollutants are becoming varied.
Especially, volatile organic compounds (VOCs) have been treated as air pollution sources for a long time which have a harmful effect on human health and the environment. The volatile organic compounds (VOCs) are various and wide in kinds, so thousands of chemical substances belong thereto. Besides, they are strongly flammable, which is the cause of safety accidents caused by fire and explosion.
The volatile organic compounds (VOCs) mainly includes BTEX(benzene, toluene, ethylbenzene and xylene), PCE, TCE, CHC, halogen group and non-halogen group chlorine and the like. These compounds are highly chemically reactive and are highly carcinogenic, so their regulation is absolutely needed and there is an urgent need for an economic control method. Additionally, the volatile organic compounds (VOCs) are known as contaminants which are fairly anesthetic as well as strongly movable and odor-inducing. Moreover, they have potential toxicity and carcinogen, and photochemically react with nitric oxide and other compounds to form ozone. As such, a special interest is being concentrated on the environmental contamination caused by these compounds. To overcome the above problems, every work place is working hard with a great deal of labor with respect to the selection and application of proper preventive techniques. Above all things, economic efficiency and safety in work places are required.
First of all, the volatile organic compounds are, for the most part, volatile organic compounds exhausted from painting and petrochemical facilities, even if gases exhausted from traveling automobiles are excluded. Thus, at present, there is an absolute need for control of volatile organic compounds for these industrial facilities and processes.
However, there is a wide variety of volatile organic compounds exhausted from these facilities, so it is difficult to control the facilities in the same way from technical point of view. Therefore, it is necessary to sort the volatile organic compounds into groups of similar physicochemical properties and control them according to their characteristics.
Since the combustion method of the conventional techniques is run at a high temperature, thermal NOx may be produced and much carbon dioxide (CO2), a greenhouse gas, may be generated.
Additionally, in case of processing halogen compounds, an additional washing facility has to be installed and it takes a lot of fuel cost. Moreover, the catalytic oxidation method has a limited range of application according to the form of a gas to be processed.
Meanwhile, in the adsorption technique, adsorbability is gradually reduced according to the number of times of regeneration of an adsorbent, thus the adsorbent has to be frequently replaced, thereby increasing the cost. Further, because the filtration of particulate matters using a preprocessing apparatus is needed, the operating and maintenance costs increase.
Recently, the method of removing contaminants using an electron beam has been introduced. An anticipated advantage of this method is that no secondary wastewater treatment facility is required since the method is carried out at dryness and at an ambient temperature. Presently, however, the method is being applied solely to some facilities of large capacity due to an efficiency problem. In case that a contaminant removal apparatus using an electron beam is used in structures of small and medium size, the study on various methods for increasing the efficiency must be carried out in advance.
Accordingly, to solve the above problems, the present inventor applied for a patent application (Korean Patent Application No. 10-2001-0023288) on Apr. 30, 2001, entitled an apparatus and method for removing volatile organic compounds by an electron beam and an adsorbent. The above prior art VOC removal apparatus will be described in detail with reference to the accompanying drawings.
Figs, la and lb are views showing a VOC removal apparatus according to one example of the conventional art. Referring to these drawings, a volatile organic compound removal apparatus 100 according to the conventional art is provided with a rectangular, enclosed case 120, the case 120 having at the top surface a reactor irradiation film (not shown) composed of alloys of thin films for irradiating an electron beam, the inner peripheral surface of the case 120 being coated with a reflecting member 120a for making the reflection of the electron beam easily done.
Additionally, an electron beam accelerator 110 for irradiating an electron beam is provided at a position spaced apart from the top surface of the reactor irradiation film at a predetermined distance. While, an inlet pipe 122 for introducing volatile organic compounds is formed at a predetermined portion of the outer peripheral side of the case 120 and an outlet pipe 124 for discharging volatile organic compounds is formed at a predetermined portion of the lower surface thereof. The case 120 is formed with an inclined plane at a predetermined angle at both lengthwise side faces.
At a position spaced apart from the inner bottom face of the case 120, an adsorbent supporting net 128 is installed for mounting an adsorbent 130. At the boundary of the supporting net 128, an rectangular supporting protuberance 126, which projects from the case 120 toward the center of the inside thereof, is formed for fixing the supporting net 128 to a predetermined height.
For the description of the adsorbent 130, a gaseous activated carbon, one example of the adsorbent, has a large specific surface area and a pore structure of small diameter and is highly adsorptive to low concentration gases. Further, because of its hydrophobic surface, it is low in adsorptivy for steams and can efficiently remove hazardous gaseous materials such as volatile organic compounds and odors mixed in the air. The activated carbon has both the portion having crystallites of a graphite structure non-uniformly dispersed and the methylene ring portion. Besides, because of its improved inner pore structure, it has a definitely large specific surface area reaching 3,000m7g.
In the activated carbon, if a solid surface is contacted onto a fluid for a long time, a specific component on the fluid gathers on the solid surface and the concentration in the fluid and the concentration of the solid surface becomes different. This phenomenon is called adsorption. At this time, the concentration in the fluid and the concentration of the solid surface forms equilibrium if the chemical potential of both phases is proper and reach the adsorption equilibrium relation. Also, such a relation is much influenced by a temperature. The adsorption in the activated carbon is achieved by the following principle. The activated carbon particle has a binary structure of micro pores (less than 2nm) dominating the adsorption and macro pores (a few μm) formed with the voids of micro particles. The diameter of the granular activated carbon is a few mm and adsorbate molecules are diffused from the outside of the particle to reach the adsorption point in this particle, and thus the adsorption is achieved through various routes. One of the routes is a serial diffusion in which the adsorbate molecules are transferred to the middle of the fluid filling the macro pores by diffusion and are adsorbed in the micro pores by diffusion. Another diffusion type is a surface diffusion in which the molecules in the adsorption state on the surface in the adsorbent are transferred to an adjacent adsorption point.
The hazardous gases adsorbed by this principle, such as volatile organic compounds, are decomposed by irradiation of an electron beam. Also, because the electron beam irradiation increases the kinetic energy of the molecules, as the adsorbed molecules are repetitively desorbed from the surface of the adsorbent, they are secondarily decomposed by being re-irradiated by an electron beam.
That is, the volatile organic compounds introduced through the inlet pipe 24 are firstly composed by an electron beam irradiated from the upper part of the case 120. Then, as they are repetitively desorbed by the adsorbent 130 mounted on the supporting net 128, they are concentrated and secondarily decomposed by an electron beam. The residual gas from which the volatile organic compounds are removed is discharged through the outlet pipe 124.
At this time, when the volatile organic compounds are intermittently adsorbed and concentrated by the adsorbent 130, if an electron beam is irradiated from the upper part of the case 120, this exhibits a higher decomposition efficiency of the volatile organic compounds.
However, the above-described volatile organic compound removal apparatus using the electron beam and the adsorbent is problematic in that, when the volatile organic compounds are adsorbed, desorbed and removed, they are easily removed if the energy of an irradiated electron beam is large, while they are more focused on adsorption and desorption than removal if the energy of the electron beam is small.
Especially, the volatile organic compound removal apparatus using an electron beam alone is problematic in that it is very difficult to decompose materials having a stable structure but a small bonding energy, such as methane.
DISCLOSURE OF INVENTION
Accordingly, it is an object of the present invention to provide a hybrid apparatus and method for removing volatile organic compounds and odorous substances by an electron beam and a catalyst, which effectively remove contaminants even in an environment with a small electron beam energy by a hybrid action of an electron beam, a catalyst or an adsorbent in the catalyst by forming the adsorbent serving as a carrier of the catalyst, such as granular activated carbons or ceramics capable of adsorbing volatile organic compounds and various hazardous gases, in a reactor to which the electron beam is irradiated.
To achieve the above object, there is provided a hybrid apparatus for removing volatile organic compounds and odorous substances by an electron beam and a catalyst in accordance with an aspect of the present invention, comprising: an electron beam accelerator for irradiating an electron beam downward; a case having an inlet pipe and an outlet pipe formed respectively at a side face and a bottom face; a supporting net for mounting a catalytic plate therein; a reactor irradiation film composed of a thin film such as titanium adhered to the upper part of the case for irradiating the electron beam; and a catalyst plate formed of a rectangular plate of a predetermined thickness and arranged to reduce an activation energy required for removal of volatile organic compounds, wherein the irradiated electron beam brings about a first decomposition on the upper layer in the case and the residual electrons of the electron beam brings about a second decomposition of various hazardous gas molecules by activating the catalyst plate.
Preferably, a third decomposition is occurred by mounting a plurality of adsorbents having self-catalytic characteristics on the top surface of the catalyst plate and making the volatile organic compounds repeat adsorption and desorption.
More preferably, a metal plate with good heat transfer and heat resistance is located on the top surface of the catalyst plate so that the corresponding metal plate can hold the latent heat of the electron beam by electron beam irradiation and then transfer the corresponding latent heat to the catalyst plate, thereby stimulating the action of the catalyst plate.
In accordance with another aspect of the present invention, the apparatus further includes a vacuum case of a thin film arranged between the lowermost end of the accelerator and the top surface of the reactor case for suppressing the reaction caused by a contact with external air upon the irradiation of the electron beam.
Preferably, the apparatus further comprises: a heater line embeded on an inner side wall of the case for increasing the temperature of internal air and thus increasing the efficiency of the catalyst plate; and a temperature sensor for detecting the temperature of the internal air of the case.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features, aspects, and advantages of preferred embodiments of the present invention will be more fully described in the following detailed description along with the accompanying relevant drawings. In the drawings: Figs. 1 a and lb are views showing a VOC removal apparatus in accordance with one example of the conventional art;
Figs. 2a and 2b are perspective views illustrating the profile of a hybrid apparatus for removing volatile organic compounds and odorous substances by an electron beam and a catalyst in accordance with an embodiment of the present invention; Figs. 3a and 3b are side sectional views illustrating the hybrid apparatus for removing volatile organic compounds and odorous substances by an electron beam and a catalyst in accordance with the embodiment of the present invention;
Figs. 4 and 5 are graphs showing the comparison of the removal efficiencies obtained when an electron beam alone acts for styrene and toluene, when a ceramic catalyst alone acts therefor and when the ceramic catalyst and the electron beam act therefor as a hybrid;
Fig. 6 is a graph showing a change in temperature of a ceramic catalyst layer in a reactor according to an irradiation dose; Fig. 7 is a graph showing the CO2 conversion rate of volatile organic compounds by the electron beam and the catalyst in the reactor according to an irradiation dose;
Fig. 8 is a graph showing the comparison of removal efficiencies of volatile organic compounds between a ceramic catalyst carried with platinum and a general ceramic catalyst in accordance with the embodiment of the present invention; Fig. 9 is a graph showing the comparison of removal efficiencies between a ceramic catalyst and a ternary ceramic catalyst with respect to a current change in accordance with the embodiment of the present invention;
Figs. 10 and 11 are graphs showing the removal efficiencies of odorous substances, methyl disulfide (DMDS) and methyl sulfide (DMS), by the application of the hybrid system in accordance with the embodiment of the present invention; and
Figs. 12a and 12b are views illustrating the profile and side section of the hybrid apparatus for removing volatile organic compounds and odorous substances by an electron beam and a catalyst in accordance with another embodiment of the present invention.
BEST MODES FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
Figs. 2a and 2b are perspective views illustrating the profile of a hybrid apparatus for removing volatile organic compounds and odorous substances by an electron beam and a catalyst in accordance with one embodiment of the present invention. Figs. 3 a and 3b are side sectional views illustrating the hybrid apparatus for removing volatile organic compounds and odorous substances by an electron beam and a catalyst in accordance with one embodiment of the present invention.
Referring to these drawings, the hybrid apparatus 200 for removing volatile organic compounds and odorous substances by an electron beam and a catalyst in accordance with an embodiment of the present invention has a case 220 whose sides are formed in the same inclined plane as the case 120 of a conventional volatile organic compound removal apparatus 100 or are formed perpendicular. A detailed explanation thereof will be stated later.
First, in Figs. 2a and 2b illustrating the case 220 whose sides are formed in an inclined plane, the case 220 is constructed in a manner that an electron beam can be diffused and irradiated from the inside of the case 220 when the electron beam is irradiated from the upper end. And, a reactor irradiation film 212 formed of titanium alloys is provided at the top surface of the case 220, and a reflecting member (not shown) is coated on the inner peripheral surface of the case 220 for making the reflection of the electron beam easily done.
Additionally, an electron beam accelerator 210 for irradiating an electron beam is located at a position spaced apart from the top surface of the reactor irradiation film 212 at a predetermined distance. While, at a predetermined portion of the outer peripheral side of the case 220, an inlet pipe 222 is formed which introduces volatile organic compounds from exhaust ports of plants or others through various kinds of pipelines, and at a predetermined portion of the lower surface thereof, an outlet pipe 224 is formed for discharging the residual gas of removed volatile organic compounds.
At this time, if the volatile organic compounds are completely removed from the inside of the case 220, the gas discharged to the outside through the outlet pipe 224 becomes cleaner than the urban atmosphere. On the other hand, the outlet pipe 224 may be installed at a predetermined portion of a side face of a lower part of the case 220 instead of being installed on the bottom face of the lower part thereof.
And, a supporting net 228 for mounting a catalyst plate 232 is installed at a position spaced apart from the inner bottom face of the case 220 at a predetermined distance. At this time, an adsorbent 230 is additionally arranged on the top surface of the catalyst plate 232 for thereby performing the function of removing complex volatile organic compounds.
Moreover, a fixed jaw 226 is formed below the supporting net 228 at an inner wall of the case 220 for supporting the catalyst plate 232 to a predetermined height.
The thus-constructed hybrid apparatus 200 for removing volatile organic compounds and odorous substances by an electron beam and a catalyst carry out hybrid decomposition and removal, such as decomposition and activation of contaminants by an electron beam, pyrolysis by the catalyst plate 232 and repetitive adsorption and desorption by the adsorbent 230.
Preferably, an additional metal plate (not shown) with good heat transfer and heat resistance and of a small sphere shape is located at the top surface of the catalyst plate 232 so that the corresponding metal plate holds the latent heat of an electron beam and thereafter transfer the corresponding latent heat to the catalyst plate 232 by electron beam irradiation, thereby stimulating the action of the catalyst plate 232.
In the hybrid apparatus 200 for removing volatile organic compounds and odorous substances by an electron beam and a catalyst as shown in Figs. 2a and 3a, the side faces of the case 220 are formed in an inclined plane and a reflecting member is attached to an inner side face thereof. Thus, it is expected that the electron beam can act well for unsaturated systems, such as toluene, xylene and styrene, which have a large bonding energy, at least one functional group and a double bond. That is, by making the width of the lower layer portion of the case 220 larger than that of the upper layer portion thereof, the space at which volatile organic compounds are removed by direct irradiation of an electron beam is maximized. Because the substance such as styrene is removed relatively well by the electron beam, it is made to be maximally removed by the electron beam by increasing a reactor space and then is completely oxidized by passing the catalyst plate 232. Namely, by forming the case 220 in a pyramid shape, the electron beam irradiation space is maximized down to the lowermost surface of the case 220 and the atmospheric layer of introduced volatile organic compounds becomes wider. Therefore, it is more expected that the electron beam can completely oxidize the unsaturated systems, such as toluene, xylene and styrene, which have a large bonding energy, at least one functional group and a double bond.
Meanwhile, in the hybrid apparatus 200 for removing volatile organic compounds and odorous substances by an electron beam and a catalyst as shown in Figs. 2b and 3b, the side faces of the case 220 are formed perpendicular and a heat storage member (not shown) is attached to an inner side face thereof. Therefore, the air in the reactor, i.e., the hybrid apparatus 200 for removing volatile organic compounds and odorous substances by an electron beam and a catalyst, is preheated to thus increase the efficiency of removing the volatile organic compounds.
The volatile organic compounds especially well removed by this structure include methane, ethane, propane and the like. The methane, ethane and propane have a small bonding energy and a relatively stable chemical structure. These compounds are better removed by a catalyst than by an electron beam. In order to use such characteristics effectively, the side faces of the removing apparatus 200 are manufactured perpendicularly. In the vertical removing apparatus 200 as shown in Figs. 2b and 3b, when a focused electron beam is irradiated by the electron accelerator 210 located at an upper part, parts of the electron beam is irradiated to the heat storage member attached on the inner side wall and thus a preheating operation starts from the upper layer portion of the removing apparatus 200. In the next step, a preheated air passes through the catalyst plate 232 located at the lower end. This increases the efficiency of transferring the temperature of the catalyst plate 232 to thus maximize the removal rate of stabilized substances such as methane.
At this time, the catalyst plate 232 is not activated by itself, but brings about a strong pyrolysis when activated by an external energy source. Therefore, the electron beam irradiated from the upper part of the hybrid apparatus 200 for removing volatile organic compounds and odorous substances by an electron beam and a catalyst of the present invention brings about a first decomposition at the upper part of the reactor, and the residual energy of the electron beam acts as an activation energy of the catalyst plate 232 and brings about a second decomposition of the contaminants adsorbed to the adsorbent 230.
The adsorbent 230 exemplified in the hybrid apparatus for removing volatile organic compounds and odorous substances by an electron beam and a catalyst according to one embodiment of the invention can be carried in the catalyst plate 232 for use or can be coated on the surface of the catalyst plate 232 for use. Also, in the present invention, the adsorbents having self-catalytic characteristics, such as activated carbon, can be used.
That is, it is sufficiently possible to include the catalyst in the adsorbent using the adsorbent material of the activated carbon or ceramic system as a carrier. More preferably, on the inner side face of the vertical case 220, a reflecting member (not shown), upon which the electron beam is irradiated, is attached or a catalyst (not shown) is coated, thereby increasing the efficiency of oxidization by the catalyst.
Figs. 4 and 5 are graphs showing the comparison of the removal efficiencies obtained when an electron beam alone acts for styrene and toluene, when a catalyst (Pt Ceramic) alone using ceramic as a carrier acts therefor and when the ceramic catalyst and the electron beam act therefor as a hybrid.
Referring to Fig. 4, in a case that only an electron beam is reacted for 0.46 seconds while inputting a 200ppm toluene at a speed of 25L/min into the hybrid apparatus 200 of removing volatile organic compounds and odorous substances in accordance with the embodiment of the present invention, 60% of the 200ppm toluene is removed. In a case that only a ceramic (Pt ceramic) carried with a platinum catalyst acts as the catalyst, a removal efficiency of about 88% is shown. In a case that the ceramic (Pt ceramic) carried with the catalyst and the electron beam acts as a hybrid, a high removal efficiency of about 98% is shown.
Referring to Fig. 5, in a case that only an electron beam is reacted for 0.46 seconds while inputting a 200ppm styrene at a speed of 25L/min into the hybrid apparatus 200 of removing volatile organic compounds and odorous substances in accordance with the embodiment of the present invention, 80% of the 200ppm styrene is removed. In a case that only a ceramic (Pt ceramic) carried with a catalyst acts as the catalyst, a similar removal efficiency of about 80% is shown. In a case that the ceramic (Pt ceramic) carried with the catalyst and the electron beam acts as a hybrid, a high removal efficiency of almost 100% is shown. Fig. 6 is a graph showing a change in temperature of a ceramic catalyst layer in a reactor according to an irradiation dose.
Referring to this, the catalyst plate 232 composed of a ceramic catalyst is arranged on the lowermost layer of the case 220 of the reactor of the hybrid apparatus 200 of removing volatile organic compounds and odorous substances in accordance with the embodiment of the present invention. In a case that volatile organic compounds are inputted at a speed of 15L/min, the reactor retention time is 0.54 seconds and the catalyst plate 232 composed of a ceramic carried with a catalyst has a 20mm thickness and is carried with platinum, as shown in Fig. 9, the temperature of the catalyst plate 232 increases in direct proportion to the irradiation dose of an electron beam. That is, the more the irradiation dose of the electron beam is, the higher the temperature of the catalyst plate 232 is.
Fig. 7 is a graph showing the CO2 conversion rate of volatile organic compounds by the electron beam and the catalyst in the reactor according to an irradiation dose. Referring to this, as shown in Fig. 5, the hybrid apparatus 200 of removing volatile organic compounds and odorous substances in accordance with the embodiment of the present invention increases the irradiation dose of the electron beam under the condition that a lOOppm toluene is used as an object gas, the speed is 15L/min and the reactor retention time is 0.54 seconds. As the result, the CO2 conversion amount of the toluene is not more than 200ppm. That is, it can be known that the decomposition rate of the volatile organic compounds is low.
However, if toluene is inputted under the same condition as above plus the condition that a ceramic carried with a platinum catalyst has a 20mm thickness and the catalyst retention time is 0.17 seconds, and the irradiation dose of the electron beam is increased in the same way as above, it can be known that the CO2 conversion amount of the toluene is rapidly increased when the irradiation dose is around 3kGy. That is, it can be known that the decomposition rate of the volatile organic compounds becomes very higher.
In case that only the electron beam or only the electron beam and the adsorbent simply act in the reactor, although some by-products such as ozone, benzaldehyde, etc. are produced after processing hazardous gases, this problem can be solved by including the electron beam and the catalyst simultaneously as in the present invention.
Such a removal reaction is shown because the catalyst becomes active at a predetermined temperature and thus serves to reduce the activation energy (energy required for removal reaction) much more for main removal sections of the removal reaction. Thus, the electron beam, activated carbons and catalyst, which are means for removing volatile organic compounds, suggested by the present invention make it easier to remove the volatile organic compounds while performing a complementary action.
Especially, the apparatus for removing volatile organic compounds by the catalyst can very easily remove the materials having a small bonding energy but a stable structure, such as methane.
For example, if it is desired to simultaneously remove the materials including methane, ethane, propane, benzene, toluene, xylene, styrene and the like, the use of a hybrid process of the electron beam and the catalyst can remove the volatile organic compounds more effectively. Here, it can be known that the materials such as methane, ethane and propane has a much smaller bonding energy and a more stable chemical structure than the materials such as benzene, toluene, xylene and styrene. In this case, it is expected that the catalyst can perform removal and decomposition more effectively. Meanwhile, the materials such as toluene, xylene and styrene are expected to serve as the electron beam more effectively since they are unsaturated systems having at least one functional group and a double bond though they have a larger bonding energy than the above-described three materials. In practice, this can be confirmed by experiments. For example, in case of aromatic compounds such as benzene, toluene, xylene and styrene, the bonding energy becomes higher in order of styrene, xyelne, toluene and benzene, and thus the degree of decomposition by the electron beam becomes higher in the above order. On the other hand, it can be known that the degree of decomposition by the catalyst becomes higher as the bonding energy is smaller, that is, in order of benzene, toluene, xylene and styrene. Therefore, the present invention is suggested so as to acquire the optimum decomposition rate by employing the hybrid removal apparatus using the catalyst and the electron beam.
However, the number of functional groups is increased as the horizontal axis goes toward the right, and thus it is certain that the decomposition by the electron beam performs better for styrene followed by xylene, toluene and benzene. Fig. 8 is a graph showing the comparison of removal efficiencies of volatile organic compounds between a ceramic catalyst carried with platinum and a general ceramic catalyst in accordance with one embodiment of the present invention.
Referring to this, the catalyst plate 232, which is provided at the lower end of the inside of the apparatus 200 for removing volatile organic compounds as shown in Figs. 2a, 2b, 3 a and 3b, acts for removing the volatile organic compounds along with the activated carbon located at the upper part and the electron beam irradiated from the electron beam accelerator 210. If the electron beam irradiated from the electron beam accelerator 210 is irradiated for a predetermined time onto the volatile organic compounds adsorbed on the adsorbent 230, heat is generated on the surface of the adsorbent 230 to thus increase the temperature.
At this time, when the temperature of the surface of the adsorbent 230 increases
to 200 to 250°C, the catalyst constituting the catalyst plate 232 is activated and thus the activation energy required for activating the overall reaction is reduced, thereby stimulating the reaction. The reduction of the activation energy upon removal reaction is achieved by the heat generating reaction of the catalyst plate 232. Thus, the catalyst plate 232 is activated by an external energy and this brings about a strong heat decomposing reaction.
Therefore, in the hybrid apparatus 200 for removing volatile organic compounds and odorous substances by an electron beam and a catalyst according to the present invention, the electron beam reaction, the adsorption and decomposition and the heat decomposition by the catalyst have a complementary action.
Fig. 9 is a graph showing the comparison of removal efficiencies between a pt ceramic catalyst and a ternary ceramic catalyst with respect to a current change in accordance with the embodiment of the present invention.
Referring to this, as illustrated in Fig. 8, in the removal reaction of volatile organic compounds using the electron beam, adsorbent and catalyst, the current inputted into the electron beam accelerator is closely connected with the irradiation dose of the electron beam. Thus, this graph shows the comparison of removal efficiencies between a pt ceramic catalyst and a ternary ceramic catalyst with respect to a current.
As a result of performing electron beam treatment using the ceramic carried with a platinum catalyst and the ceramic carried with a ternary catalyst, as illustrated in Fig. 6, it can be known that the application of the platinum catalyst shows a higher removal efficiency than that of the ternary catalyst. Especially, it can be known that the application of both electron beam and catalyst shows a 20% increase in removal efficiency compared to the application of only the electron beam. At this time, the catalyst of the invention includes not only the platinum or ternary catalyst but also all metal catalysts. In addition, as in the structure suggested in the present invention, in case that the electron beam is irradiated by tightly contacting the composition of the adsorbent 230 to the top surface of the catalyst plate 232, a higher removal efficiency of volatile organic compounds is shown. At this time, the materials such as a ceramic serving as a carrier of the catalyst are inclined to store heat, and they are more suitable for increasing the temperature in the reactor.
In a process to remove volatile organic compounds using the apparatus for removing volatile organic compounds by a catalyst, firstly, volatile organic compounds to be processed are inputted into the removal apparatus 200 through the inlet pipe 222. Then, the adsorbent 230 mounted at a predetermined height and carried with a catalyst is formed in the removal apparatus 200, and volatile organic compounds are adhered to the surface thereof. At the same time, the electron beam accelerator 210 is driven so that an electron beam of a predetermined irradiation dose can be irradiated on the surface of the adsorbent 230 carried with the catalyst. That is, in this case, the adsorbent can perform both adsorption function and catalyst function by incorporating the catalyst into the adsorbent 230.
In case of the electron beam, it has an advantage that it can easily decompose unstable odors and VOCs such as styrene having the same functional group (for example, methyl group) as a double bond even though its bonding energy is much larger than methane. In practice, as the number of the function group becomes larger, the electron beam can process odors and VOCs more easily through a radical reaction such as OH- radicals. [Table 1]
Figure imgf000021_0001
This table is derived under the condition that the unit of the reaction constant is
cm3/mol/sec and the temperature is 298°K.
Table 1 shows a change in reaction constant of OH-radicals according to a change in bonding energy of each individual volatile organic compound. Even in case of a volatile organic compound with a large bonding energy, it can be seen that decomposition and removal are easily performed through the apparatus for removing volatile organic compounds by a catalyst using an adsorbent as a carrier according to the present invention.
More specifically, methane (CH4) is a simple ring type with no double bond and benzene (C6H6) has two double bonds and is of ring type. In addition, toluene (C7H8) has a (C6H5)-CH3 bond, o-xylene (C8Hn) has a (CH3)-(C6H5)-(CH3) bond, m-xylene (C^ {) has a (CH3)-(C6H5)-(CH3) bond and p-xylene (C8Hn) has a (CH3)-(C6H5)-(CH3) bond.
In the present invention, the volatile organic compounds having such a bonding structure are decomposed through a radical reaction such as OH-radicals as illustrated in Fig. 1. As shown in Table 1, it can be seen that the volatile organic compounds having a large reaction constant of OH-radicals are easily decomposed even though their bonding energy is large. Besides, it can be seen that, as the number of functional group is larger, the compounds are well decomposed.
Figs. 10 and 11 are graphs showing the removal efficiencies of odorous substances, methyl disulfide (DMDS) and methyl sulfide (DMS), by the application of the hybrid system. By this, it can be seen that odorous substances including methyl disulfide (DMDS) and methyl sulfide (DMS) also show very high removal efficiency in an electron beam area to which a low energy is applied.
Hereinafter, a hybrid apparatus 200' for removing volatile organic compounds and odorous substances by an electron beam and a catalyst in accordance with another embodiment of the present invention will be described in detail with reference to the accompanying drawings.
Figs. 12a and 12b are views illustrating the profile and side section of the hybrid apparatus 200' for removing volatile organic compounds and odorous substances by an electron beam and a catalyst in accordance with another embodiment of the present invention.
Referring to these, in the hybrid apparatus 200' for removing volatile organic compounds and odorous substances by an electron beam and a catalyst in accordance with another embodiment of the present invention, a vacuum case 240 is preferably provided between a case 220 and an electron beam accelerator 210 for making the electron beam to be directly irradiated from the electron beam accelerator 210 into the case 220 without reacting with external air. At this time, the vacuum case 240 gives a synergy effect on the permeability of the irradiated electron beam and makes the electron beam not to react with external air, and this does not cause ozone generation. Therefore, the hybrid apparatus 200' for removing volatile organic compounds and odorous substances by an electron beam and a catalyst in accordance with another embodiment of the present invention has a higher removal efficiency of volatile organic compounds.
More preferably, in the same drawings, a temperature sensor 250 is attached to a predetermined portion of an inner side wall of the reactor case 220 and a heater line 252 is embedded along the inner side wall (or along the inner circumferential face of the inlet pipe 222). In a case that the heater line 252 is embedded along the inner circumference of the inlet pipe 222, the volatile organic compounds input into the case 220 via the inlet pipe 222 are firstly preheated as they pass through the inlet pipe 222. By this, in case that the inlet temperature detected by the temperature sensor 250, at which the upper layer portion of a catalyst layer is introduced to the catalyst layer, is
low (e.g., less than 50°C), a power is inputted into the heater line 252 to allow the reactor case 220 introduced to the catalyst layer to keep at least ambient temperature. Likewise, the hybrid apparatus 200' for removing volatile organic compounds and odorous substances by an electron beam and a catalyst in accordance with another embodiment of the present invention have a higher removal efficiency of volatile organic compounds.
Since the above embodiments are described only for examples, the present invention is not limited to the above embodiments and various modifications or alterations can be easily made therefrom by those skilled in the art without departing from the scope of the present invention.
As seen from above, the hybrid apparatus and method for removing volatile organic compounds and odorous substances by an electron beam and a catalyst in accordance with the present invention, the electron beam is provided with an adsorbent such as activated carbon or ceramic serving as a carrier of the catalyst, and thus the decomposition by the electron beam, the decomposition by the adsorbent and the pyrolytic reaction by the catalyst perform a complementary action on various contaminant gases, odors and volatile organic compounds. Therefore, the hazardous gaseous materials can be removed very effectively in small-sized facilities using a small energy, as well as large-sized facilities such as petrochemical processes, coating processes, paint plants, refining plants, sewage disposal plants, refuse combustion and disposal facilities from which a variety of hazardous gaseous materials including volatile organic compounds, odors, dioxin or nitrogen oxides. Besides, a relatively small energy is consumed for removing contaminants, and thus the apparatus and method are very economic.

Claims

1. A hybrid apparatus for removing volatile organic compounds and odorous substances by an electron beam and a catalyst, comprising: an electron beam accelerator for irradiating an electron beam downward; a case having an inlet pipe formed on a side face of an upper part for receiving various hazardous gases and an outlet pipe formed on a bottom face or the opposite side face of a bottom part; a supporting net for mounting a catalytic plate therein; a reactor irradiation film composed of a thin film such as titanium adhered to the upper part of the case for irradiating the electron beam; and a catalyst plate formed of a rectangular plate of a predetermined thickness and arranged to reduce an activation energy required for removal of volatile organic compounds, wherein the irradiated elecfron beam brings about a first decomposition on the upper layer in the case and the residual elecfrons of the electron beam brings about a second decomposition of various hazardous gas molecules by activating the catalyst plate.
2. The apparatus of claim 1 , wherein a third decomposition is occurred by mounting a plurality of adsorbents having self-catalytic characteristics on the top surface of the catalyst plate and making the volatile organic compounds repeat adsorption and desorption.
3. The apparatus of claim 1 , wherein a metal plate with good heat transfer and heat resistance is located on the top surface of the catalyst plate so that the corresponding metal plate can hold the latent heat of the electron beam by electron beam irradiation and then transfer the corresponding latent heat to the catalyst plate, thereby stimulating the action of the catalyst plate.
4. The apparatus of claim 1, wherein, if the volatile organic compounds to be decomposed are compounds such as methane, ethane, propane and the like which have a small bonding energy and a relatively stable chemical structure, they are decomposed utilizing the case having a perpendicular side face.
5. The apparatus of claim 1, wherein, if the volatile organic compounds to be decomposed are unsaturated systems, such as toluene, xylene and styrene, which have a large bonding energy, at least one functional group and a double bond, the side faces of the case are formed in an inclined plane of a predetermined angle and the reactor is up narrow and down wide.
6. The apparatus of claim 4, wherein the oxidization efficiency by the catalyst can be increased by attaching a reflecting member for reflecting the electron beam on an inner side face of the perpendicular case or coating the catalyst thereon.
7. A hybrid apparatus for removing volatile organic compounds and odorous substances by an electron beam and a catalyst, comprising: an electron beam accelerator for irradiating an electron beam downward; a case having an inlet pipe and an outlet pipe connected respectively on a side face and a bottom face or the opposite side face of a bottom part; a supporting net for mounting a catalytic plate therein; a reactor irradiation film composed of a thin film such as titanium adhered to the upper part of the case for irradiating the electron beam; a vacuum case of a thin film arranged between the lowermost end of the accelerator and the top surface of the reactor case for suppressing the reaction caused by a contact with external air upon the irradiation of the electron beam; and a catalyst plate formed of a rectangular plate of a predetermined thickness located on the inner bottom face of the case and arranged to reduce an activation energy required for removal of volatile organic compounds, wherein the irradiated electron beam brings about a first decomposition on the upper layer in the case and the residual elecfrons of the electron beam brings about a second decomposition of various hazardous gas molecules by activating the catalyst plate.
8. The apparatus of claim 7, wherein further comprising: a heater line embeded on an inner side wall of the case or on the inner circumferential face of the inlet pipe for increasing the temperature of internal air and thus increasing the efficiency of the catalyst plate; and a temperature sensor for detecting the temperature of the internal air of the case.
9. A hybrid method for removing volatile organic compounds and odorous substances by an electron beam and a catalyst, comprising the steps of: firstly decomposing a hazardous gas by increasing the molecular activity of the hazardous gas by the electron beam irradiated from the upper part of a removal apparatus; and removing the hazardous gas by storing the heat of a catalyst plate and oxidizing the same by the catalyst action of the catalyst plate as the residual energy of the electron beam is irradiated on the ceramic catalyst plate carried with platinum.
10. The method of claim 9, further comprising the step of repetitively adsorbing and desorbing contaminants under an electron beam atmosphere by including an adsorbent on the top surface of the catalyst plate.
11. The method of claim 9, further comprising the steps of: detecting a temperature of the case; and increasing the temperature in the case to more than an ambient temperature by driving the heater line if the temperature of the upper layer portion of the catalyst plate is lower than the ambient temperature.
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CN116914171A (en) * 2023-09-05 2023-10-20 南阳汉鼎高新材料有限公司 Recycling method of failure vanadium battery electrolyte

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KR101494781B1 (en) * 2012-12-06 2015-02-23 한국원자력연구원 Perfluorinated compounds treatment system
CN112892145B (en) * 2021-01-22 2022-06-28 机械工业第九设计研究院股份有限公司 Degradation device in VOC exhaust-gas treatment system of automotive interior processing

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