JP2008055020A - Deodorizing apparatus for odor containing oil droplets and fine particles, and deodorizing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To establish an apparatus for deodorizing odor (offensive odor) containing oil droplets and fine particles in broad ranges such as service business including restaurants, individual residence, livestock business, automobile components manufacturing business, and printing business, and to establish a decomposing method using the apparatus. <P>SOLUTION: The apparatus deodorizes the odor (offensive odor) containing the oil droplets and the fine particles by including: a plasma discharge unit, which is arranged at the downstream side of a dust collection unit composed of a charging part and a dust collection part; and a catalytic unit for decomposing ozone, which is arranged in a rear stage. The odor is decomposed with the use of the method using the apparatus. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to an apparatus for efficiently decomposing malodors and a method for decomposing odors using the apparatus.

In recent years, there has been a growing interest in environmental issues such as bad odor pollution in the living environment, including the adverse effects of volatile compounds on the air environment. For example, the number of complaints about bad odors is said to have reached about 23,000 in FY2001. In particular, there are obvious cases where automobile repair shops, canteens, food processing, apartment houses such as condominiums, and livestock industries are the source of bad odors, and how to reduce these bad odors in the vicinity of residential areas Has become an issue. Malodorous substances are mainly composed of volatile organic compounds and inorganic compounds. Combustion methods (Patent Document 1), adsorption methods (Patent Document 2), and the like are known as techniques for treating these volatile substances.
JP 2003-294222 A JP-A-11-71584

However, these malodor decomposition apparatuses are large-sized apparatuses intended for installation in production factories and the like, and it has been extremely difficult to adapt as they are to small and medium-sized service providers, private houses, apartment houses, and the like. As a relatively small-scale deodorization technique, there is known an application of the technology of an electrostatic precipitator (Patent Document 3). However, the known electrostatic precipitator has an insufficient deodorizing efficiency and is practically deodorized. There was a problem of lack of ability.
JP 2000-5631 A

Most of the deodorization techniques disclosed so far are provided with a plurality of adsorption towers, for example, while continuously changing the pressure of the adsorption tower and performing the adsorption process in one of the adsorption towers, Adsorption towers are known to adsorb and remove odorous substances such as volatile organic compounds while performing a desorption process (regeneration of adsorbent), and to be brominated in a furnace and operate in large chemical plants. is doing.

However, it is difficult to apply known technologies used in chemical plants, etc., to combat odors generated outside from businesses such as small and medium-sized service businesses in the vicinity of residential areas, private livestock industry, apartment houses, etc. In order to solve this problem, technical development of a deodorizing device for environmental purification that is small and easy to operate is awaited. The development of this technology has led to the spread of environmental deodorization equipment to small and medium-sized businesses, which reduces the generation of odors from businesses such as small and medium-sized service businesses in the vicinity of residential areas, privately-run livestock industry, and housing complexes. Therefore, it can be expected that the living environment will be improved.

That is, an object of the present invention is to provide a deodorizing apparatus for substantially reducing odorous substances such as volatile compounds in a small and simple manner and a method for decomposing odorous substances using the same.

Therefore, the present inventors have intensively researched and developed a small, light and low running cost odor decomposing apparatus and an odor decomposing method using the odor decomposing apparatus. After removing particulate matter such as ozone, the plasma discharge unit consisting of needle-like electrode and plate electrode efficiently decomposes ozone, easily decomposable substance decomposed by discharge, and odorous substance in the presence of photocatalyst. An inorganic oxide catalyst containing manganese can be arranged on the downstream side, and the excess ozone generated in the plasma discharge unit and the odorous substances that are insufficiently decomposed or denatured in the plasma discharge unit are almost completely removed and trapped. In addition, a deodorizing apparatus with high efficiency and extremely high safety can be obtained.

Efficiently venting the target gas containing odorous substances from 0.05 vol.ppm to 2000 vol.ppm through the device at a rate of 6 L / min to 1000 L / min in a standard state per pair of electrodes in the plasma discharge unit Odorous substances can be removed. It has been found that according to this deodorizing apparatus and a deodorizing method using the apparatus, it is possible to deodorize a wide range of odors (treatment gas) at room temperature, and the present invention has been completed.

That is, the technical solution means of the present invention is: (1) a plasma discharge unit comprising a needle electrode for generating ozone and a plate electrode is disposed at a subsequent stage of a dust collecting unit comprising a charging part and a current collecting part; (2) The odor decomposition apparatus according to (1), wherein the shape of the plate electrode is a honeycomb shape. (3) The odor decomposition apparatus according to (1), wherein the manganese content of the catalyst used in the manganese-containing catalyst unit is 10 mass% to 95 mass% on a catalyst basis, and (4) the plasma discharge unit (1) The odor decomposition apparatus according to (1), wherein a honeycomb electrode in which titania is applied to the plate electrode is used. (5) In the plasma discharge unit The odor decomposition apparatus according to (1), wherein odor is introduced from a tip side of the electrode, and (6) a DC negative potential is applied to the needle electrode and a DC positive potential is applied to the plate electrode in the plasma discharge unit. (7) An odor decomposition apparatus according to (1), wherein (7) a plasma discharge unit comprising a needle electrode and a plate electrode for generating ozone is disposed downstream of a dust collection unit comprising a charging unit and a current collection unit. Furthermore, the concentration of the odorous substances contained in the gas to be treated is 0.05 vol.ppm or more to 2000 vol.ppm in the odor decomposing apparatus characterized in that a manganese-containing catalyst unit mainly for the subsequent stage ozonolysis is arranged. The following is a method for decomposing odorous substances, characterized in that the flow rate of processing gas per pair of needle electrodes and plate electrodes is 6 L / min to 1000 L / min in terms of standard state, (8 ) Ma The method for decomposing odorous substances according to (7), wherein the manganese content of the catalyst used in the gun-containing catalyst unit is 10 mass% to 95 mass% on a catalyst basis, and (9) the plasma discharge unit (7) The method for decomposing odorous substances according to (7), wherein a honeycomb electrode in which titania is applied to the plate electrode is used. (10) In the plasma discharge unit, the odor is introduced from the tip side of the needle-like electrode. (7) The odorous substance decomposition method according to (7), wherein (11) the plasma discharge unit applies a negative DC potential to the needle electrode and a positive DC potential to the plate electrode. This is a method for decomposing odorous substances.

As described above, according to the present invention, it is possible to reduce odors from businesses such as small and medium-sized service businesses, privately-run livestock industry, and apartment houses, and a significant improvement in the environment can be expected.

The details of the present invention will be described below by way of examples, but they are intended to specifically describe the technical contents of the present invention and are not intended to limit the scope of the present invention.

(Deodorizer)
(Device configuration)
As shown in FIG. 1, the deodorizing device is roughly divided into the order of (a) dust collection unit, (b) plasma discharge unit, (c) post-treatment process, and (d) an exhaust fan. Be placed.

(Role of each component)
(A) The dust collection unit odor (gas to be treated) is first guided to the dust collection unit. Particulate matter such as dust, smoke, oily smoke, and metal powder contained in the odor is charged by the charged part and then captured and removed by the dust collecting part.

(B) Plasma discharge unit After the particulate matter is removed by the dust collection unit, in this unit, the odorous substance collides with charged particles in the presence of cold plasma and decomposes into easily decomposable substance or by plasma discharge. Decomposes by reacting with generated ozone (O ₃ ). In addition, the easily decomposable substance further decomposes by reacting with ozone. When the photocatalyst is present, these reactions proceed more efficiently by the ultraviolet rays generated by the discharge.

(C) The odorous substance is almost completely decomposed and non-bromated in the plasma discharge unit described above in the post-treatment process, but contains excess ozone that was not involved in the decomposition reaction and partially undegraded or modified odorous substances containing manganese. It is decomposed or trapped almost completely in the post-treatment step provided with the impregnated inorganic oxide catalyst.

(D) Exhaust fan As the exhaust fan, a known exhaust fan can be preferably used. A sirocco fan, a turbo fan or the like can be preferably used as the exhaust fan. Moreover, it does not prevent having a suction machine.

(Details of each component)
(B) Dust collection unit The dust collection unit consists of a charging part and a dust collection part. In the charging part, a DC voltage of 2kV to 22kV is applied so that the needle electrode has a positive potential and the plate electrode has a negative potential. It has the role of charging droplets and fine particles and efficiently collecting the dust in the dust collection section downstream of the charging section. The DC voltage (applied voltage) in the charged portion is preferably 2 kV to 22 kV, more preferably 3 kV to 18 kV, and most preferably 4 kV to 12 kV. The dust collecting part located at the subsequent stage of the charging part has a role of removing charged particles such as oil droplets and fine particles. The dust collection unit can collect dust without installing a power supply and applying an applied voltage. However, the acicular electrode and plate electrode are arranged so that the acicular electrode has a positive potential and the plate electrode has a negative potential. When voltage is applied, the dust collection effect increases.

(I)
Plasma discharge unit (suitable number of electrodes)
In the plasma discharge unit, one or two or more electrode assemblies each including a needle electrode and a plate electrode are used. The number of electrodes constituting one aggregate is 80 to 2000 pairs, preferably 85 to 1500 pairs, more preferably 90 to 750 pairs, most preferably 95 to 150 pairs. preferable. If it is less than this range, the volume of odor (process gas) to be handled becomes small, which is uneconomical. In addition, if this range is exceeded, the plasma discharge tends to be non-uniform, and this is not preferable.

(Applied voltage value and polarity)
A DC voltage is applied to the electrode, a negative potential is applied to the needle electrode, and a positive potential is applied to the plate electrode. This is because when a negative potential is applied to the needle electrode and a positive potential is applied to the plate electrode, ultraviolet rays having a wavelength corresponding to the band gap of titania are selectively generated between the electrodes. As described above, the present invention has a feature that an ultraviolet ray including a wavelength corresponding to a band gap is generated by discharge from titania (showing a photocatalytic function) directly applied to an electrode, and an ultraviolet ray generating device such as a black light can be omitted. is doing. Therefore, when a direct current having the opposite polarity to that described above is applied, the decomposition rate tends to decrease. When AC is applied, it is somewhat improved compared to DC of the opposite polarity (DC positive potential applied to the needle electrode and DC negative potential applied to the plate electrode), but the DC negative potential is applied to the needle electrode. Compared with the case where a positive DC potential is applied to the plate electrode, the decomposition rate of the odorous substance is not reached.

The applied DC voltage is preferably 8 kV to 50 kV, more preferably 10 kV to 30 kV, still more preferably 12 kV to 20 kV, and most preferably 12 kV to 17 kV. The upper limit value is not particularly limited, but about 50 kV is considered as the upper limit value from a practical viewpoint such as an increase in the size of the power source.

(Material and shape of electrode)
As for the material of the electrode, a stainless steel plate can be preferably used for the plate electrode, but a stainless steel plate is most preferable in view of easy cleaning of the electrode. Regarding the material of the needle electrode, tungsten and stainless steel are preferable, and tungsten is most preferable. The shape of the needle electrode can be preferably various shapes such as a columnar shape, a screw shape, a spiral shape, a prismatic shape, a triangular prism shape, and a blade shape, but a cylindrical shape and a prismatic shape are more preferable, and a cylindrical shape is most preferable. Various shapes such as a flat plate shape, a honeycomb shape, and a corrugated plate shape can be adopted as the shape of the plate electrode, but a flat plate shape and a honeycomb shape are preferable. When aiming to increase the amount of ozone in the plasma discharge unit, a honeycomb shape is preferable.

In the case of a cylindrical shape, in the shape of a prism, the length of the long side of the diagonal line is preferably 0.6 mm to 3.3 mm, more preferably 0.7 mm to 2.5 mm, more preferably 0.7 mm to 1.2 mm. Most preferably, it is from mm to 1.0 mm. If it is less than this, there is a tendency that the wear of the needle electrode tends to proceed. If this is exceeded, the cost of the material will increase and the technical meaning will tend to be dilute.

(Titania coating conditions and coating amount on plate electrode)
The purpose of applying titania to the plate electrode is to effectively utilize the ultraviolet rays generated by the discharge to promote the decomposition of odorous substances and to prevent the electrodes from being soiled. In the apparatus of the present invention, a desired deodorizing effect can be obtained even when titania is not applied to the plate electrode, but by applying titania depending on the odor concentration, the amount of oil droplets or fine particles in the odor, etc., the deodorizing efficiency can be improved. I can expect. The necessity of applying titania is preferably determined in consideration of the target odor, removal rate, economy, and the like.

  In applying titania, after applying a solution containing titanium alkoxide, which is a titania precursor, to the plate electrode, it is preferable to bake at a temperature of 140 ° C. to 340 ° C. for 1 hour or more, more preferably 150 ° C. to 330 ° C. Preferably, it is 160 ° C or higher and 300 ° C or lower, and more preferably 170 ° C or higher and 280 ° C or lower. As a coating method, a known method can be preferably used, and a preferred format may be selected according to the production scale.

Note that vapor deposition, sputtering, and the like are also known as methods for carrying titania. Even if these methods are used, there is no problem in terms of performance, but the cost increases, so that they are not suitable for small and medium-sized business applications.

The coating amount of titania to the plate electrode is preferably 1 g / m ² or more 150 g / m ² or less in terms of TiO _2, 10 g / m ² or more 130 g / m ² or less, more preferably, 25 g / m ² or more ～110G / m ² or less is preferable, 40 g / m ² or more to 100 g / m ² or less is most preferred. If it is less than this range, the catalyst activity may be insufficient. Conversely, if the range is exceeded, the activity is saturated, and as a result, the technical advantage is reduced, for example, the effect is saturated while the cost increases. Absent.

The inorganic chemical shape of titania carried on the honeycomb electrode is not particularly limited. For example, when titania is crystalline, anatase type and rutile type can be preferably used. From the viewpoint of deodorization efficiency, anatase type is preferable because it is excellent, but various inorganic chemical shapes may be selected in consideration of cost and the like.

(B) Post-treatment step In the post-treatment step, a catalyst containing an inorganic oxide and a manganese compound is used. In this process, of the ozone generated in the preceding step (a), the odorous substances are almost completely decomposed, and then the remaining ozone and odorous substances are decomposed and captured when they are undegraded and denatured. Indicates a role.

As the shape of the catalyst used in the post-treatment step, a hollow prismatic shape, a cylindrical shape, a triangular prism shape, a spindle shape, or the like can be preferably used, and a prismatic shape is most preferable. As the hollow shape, various shapes such as a circle, a triangle, a quadrangle, and a hexagon can be preferably used, but a quadrangle and a hexagon are preferable. Materials that can be used for the inorganic oxide include alumina, zirconia, titania, silica, silica alumina, high silica zeolite, ceria, yttria, magnesia, barrier, inorganic substances such as clinoptilolite, sepiolite, faujasite, Synthetic zeolites such as ZSM-5 and MCM-41 can be preferably used. Zeolite is not prevented from being dealuminated or ion-exchanged with various metal ions as appropriate.

Among the inorganic oxides, alumina, silica alumina, sepiolite, and clinoptilolite are preferable, alumina, silica alumina, and sepiolite are more preferable, and sepiolite is most preferable. One or more of these can be appropriately selected and used. In addition to these materials, addition of various inorganic and organic compounds as a molding agent and a release agent is not hindered.

The manganese compound content is preferably from 10 mass% to 95 mass% as Mn on a catalyst basis, more preferably from 30 mass% to 90 mass%, further preferably from 45 mass% to 85 mass%, and more preferably from 55 mass% to 80 mass%. Most preferred. If the amount is less than this range, the ozone removal performance tends to be insufficient. If this range is exceeded, the content of the inorganic oxide described above may be reduced, leading to a decrease in specific surface area or mechanical strength. As a result, ozone removal performance tends to be lowered, which is not preferable.

(C) Exhaust fan As the exhaust fan, a known exhaust fan can be preferably used. Moreover, it does not prevent using an aspirator, a decompression pump, etc. as an exhaust fan. Although there is no particular limitation on the intake capacity, it can be considered that a realistic range is 0.03 m ³ (standard value conversion value, hereinafter abbreviated as stp) / min to 1000 m ³ (stp) / min.

(Deodorization method)
(Odor ventilation)
When a honeycomb-shaped electrode is used in the plasma discharge unit, it is preferable to vent from the opposite side of the needle-shaped electrode toward the needle-shaped electrode (for convenience of explanation, this direction is referred to as a forward direction, and the opposite of this direction). The direction is called the reverse direction)). Even when it is ventilated from the needle electrode side, a sufficient deodorizing effect can be obtained, but the amount of decomposition and decomposition rate of odorous substances are further improved by making it in the forward direction, so it has more space and power saving features. This is preferable because it makes it possible to design a device that makes full use of it.

The reason why the degradation rate of malodorous substances improves when ventilated in the forward direction is not clear at this time, but the inventors are not sure between needle-to-plate electrodes such as needle-shaped and hexagonal hollow-shaped electrodes. The odorous molecules collide with high-speed electrons more efficiently, or contact with active oxygen species such as ozone. It is presumed that the efficiency will increase.

(Odor flow per pair of electrodes in plasma discharge unit)
Aeration rate per electrode pair is preferably 6L (stp) / min to 1000L (stp) / min, more preferably 10L (stp) / min to 1000L (stp) / min, 300L (stp) / min It is more preferably from ˜800 L (stp) / min, and most preferably from 400 L (stp) / min to ˜700 L (stp) / min.

Below this range, there is no problem with the decomposition rate, but the amount of processing air per hour decreases, making it uneconomical and diluting technical meaning. Conversely, if this range is exceeded, the size of the rotating machine such as the exhaust fan system becomes too large, making it unsuitable as a device for small and medium-sized businesses and individual businesses of the present invention. In some cases, the superiority may be sparse.

(Target odor substance)
The target odor substances are ammonia, methyl mercaptan, hydrogen sulfide, methyl sulfide, methyl disulfide, trimethylamine, acetaldehyde, propionaldehyde, normal butyraldehyde, isobutyraldehyde, normal valeraldehyde, isovaleraldehyde, isobutanol, ethyl acetate, methyl isobutyl. In addition to ketones, toluene, styrene, xylene, propionic acid, normal butyric acid, normal valeric acid, isovaleric acid, etc., fatty acids such as acetic acid, aldehydes such as acetaldehyde, formaldehyde, propionaldehyde, butyraldehyde, valeraldehyde, butanol, Alcohols such as propanol, ethanol and methanol, esters such as ethyl acetate, and aromatics such as benzene, toluene, styrene and xylene Alkanes such as butane, pentane, hexane and heptane, alicyclic hydrocarbons such as cyclopentane and cyclohexane, hydrocarbons such as alkenes such as propene, butene, pentene, allene, butadiene and pentadiene, hydrocarbons such as diene and allene, and mercaptans It is possible to preferably treat odorous substances such as odors.

(Concentration of odorous substances contained in odor)
The odor (processing target gas) that can be handled may contain these odorous substances alone, or may contain two or more odorous substances. The concentration of odorous substances alone in the odor (gas to be treated) or when two or more odorous substances are included, the total concentration of odorous components is preferably 0.05 vol.ppm or more and 2000 vol.ppm or less, 0.1 vol. More preferably, it is .1 to 1250 vol.ppm, more preferably 0.1 to 800 vol.ppm, and most preferably 0.3 to 300 vol.ppm. When the upper limit value of this range is exceeded, there is a high possibility that a part of the odorous material overflows downstream, depending on the processing amount. Technically, there is no limit to the lower limit, but the actual lower limit is considered to be about 0.05 vol.ppm. The temperature of the odor (the gas to be treated) is not particularly limited, but it can be preferably used at the normal outdoor temperature or the environmental temperature of a building (such as a factory). As a rough guide, -10 ° C or higher and 450 ° C or lower is preferable.

The present invention can eliminate bad odor pollution by using it in various sources of bad odor such as service industry including canteen industry, personal housing, livestock industry, automobile parts manufacturing industry, printing industry and the like.

It is a figure which shows schematic structure of a deodorizing apparatus.

Claims (11)

A plasma discharge unit consisting of a needle electrode and a plate electrode for generating ozone is placed after the dust collecting unit consisting of a charging part and a current collecting part, and a manganese-containing catalyst unit mainly intended for the subsequent ozone decomposition is placed. Odor decomposition device characterized by 2. The odor decomposition apparatus according to claim 1, wherein the plate electrode has a honeycomb shape. The odor decomposition apparatus according to claim 1, wherein the manganese content of the catalyst used in the manganese-containing catalyst unit is 10 mass% or more and 95 mass% or less based on the catalyst. 2. The odor decomposition apparatus according to claim 1, wherein a honeycomb electrode in which titania is applied to a plate electrode of a plasma discharge unit is used. The odor decomposition apparatus according to claim 1, wherein the odor is introduced from the tip side of the needle electrode in the plasma discharge unit. 2. The odor decomposition apparatus according to claim 1, wherein a DC negative potential is applied to the needle electrode and a DC positive potential is applied to the plate electrode in the plasma discharge unit. A plasma discharge unit consisting of a needle electrode and a plate electrode for generating ozone is placed after the dust collecting unit consisting of a charging part and a current collecting part, and a manganese-containing catalyst unit mainly intended for the subsequent ozone decomposition is placed. The total concentration of odorous substances contained in the gas to be treated in the odor decomposing device characterized by the above is 0.05 vol.ppm or more and 2000 vol.ppm or less, and the flow rate of processing gas per pair of needle electrodes and plate electrodes is standard Degradation method of odorous substances characterized by a state conversion value of 6L / min to 1000L / min The method for decomposing an odor substance according to claim 7, wherein the manganese content of the catalyst used in the manganese-containing catalyst unit is 10 mass% or more and 95 mass% or less based on the catalyst. 8. The method for decomposing an odor substance according to claim 7, wherein a honeycomb electrode in which titania is applied to a plate electrode of a plasma discharge unit is used. The method for decomposing odorous substances according to claim 7, wherein odorous substances are introduced from the tip side of the needle-like electrode in the plasma discharge unit. 8. The method for decomposing odorous substances according to claim 7, wherein a DC negative potential is applied to the needle electrode and a DC positive potential is applied to the plate electrode in the plasma discharge unit.