KR100463713B1 - Reactor with lean phase for circulating fluized bed photo-catalyst and method for photolysis of trichloroethlyene gas using the same - Google Patents

Abstract

The present invention relates to a circulating fluized bed photocatalytic reactor, and more particularly, to a circulating fluidized bed photocatalyst reactor having a lean phase and a photolysis method of a volatile organic compound gas using the same. The circulating fluidized bed photocatalytic reactor of the present invention converts the riser into a quartz tube and arranges an ultraviolet lamp outside the riser, thereby maximizing the irradiation efficiency of the ultraviolet light emitted from the reactor and the photocatalyst and maintaining the irradiation intensity of the ultraviolet ray. Adjust it. In addition, through the lean phase obtained through a suitable gas flow rate in the riser, the contact between the ultraviolet ray, the reactor body, and the photocatalyst is maximized. As a result, it is possible to considerably increase the photolysis capacity and reaction efficiency and to reduce the manufacturing cost of the reactor.

Description

Reactor with lean phase for circulating fluized bed photo-catalyst and method for photolysis of trichloroethlyene gas using the same}

The present invention relates to a circulating fluidized bed photocatalyst reactor, and more particularly, to a circulating fluidized bed photocatalyst reactor having a lean phase and a photolysis method of a volatile organic compound gas using the same.

Photocatalytic reactor is a reactor used for photocatalytic reaction that completely oxidizes and decomposes hardly decomposable substances, toxic substances, volatile organic and inorganic compounds with high efficiency in various environmental fields such as water quality, air, ocean, groundwater, etc. There is a form. Among the photocatalyst reactors, the fluidized bed reactor does not require the separation process between the catalyst and the reactant, and in recent years, decolorization of dyeing wastewater, COD removal of heavy metal wastewater generated in printed circuit board manufacturing processes, and high concentration antibiotics generated in pharmaceutical manufacturing processes It has been studied in various fields, such as wastewater treatment (Catalysis, vol. 14, No. 2, 1998: Principles and Properties of Semiconductor Photocatalysts).

In particular, US Pat. No. 5,374,405 to Finberg et al. Discloses a photochemical reactor using a porous bed vessel drum equipped with a rotating plenum vessel. The reactor is configured to react with fluidized solid particles as it passes through a porous bed vessel drum equipped with a rotating plenum vessel through which the reactor injected through the wall of the drum passes, and then passes through the discharge section. A spinning device is installed to promote the photocatalytic reaction. However, in the reactor, since solid particles such as catalysts are affected by gravity in addition to centrifugal force, there is a disadvantage in that a complicated apparatus is required to fluidize the solid particles.

In addition, U.S. Patent No. 5,045,288 to Raub et al. Is composed of a narrow gap consisting of two flat glass plates, a porous dispersion plate, a reactor inlet and an outlet, and a photocatalyst is filled inside the glass wall. A reactor is disclosed in which a two-dimensional photocatalytic reactor is irradiated with ultraviolet rays from outside of a glass wall surface. The photocatalytic reactor is used to purify the air and water contaminated with volatile organic compounds such as trichloroethylene (TCE) and nonvolatile organic compounds such as polychlorinated biphenyl. However, in the photocatalytic reactor, since borosilicate glass is used as the glass wall of the reactor, ultraviolet light having a short wavelength is absorbed into the glass, thereby inefficient supply of ultraviolet light. In addition, since the reactor is planar, there is a problem in that the intensity of ultraviolet rays reached according to the position of the reactor is different. In addition, there is a drawback that the processing capacity is quite insufficient to remove a large amount of volatile organic chemicals.

In addition, the Korean Patent No. 358950 of the applicant has a narrow gap in the form of an annulus including an ultraviolet lamp provided inside a small diameter quartz tube and an electric one of the two quartz tubes having different diameters. A two-dimensional fluidized-bed photocatalyst reactor having is disclosed, which can be used to photolyse nitric oxide (see FIG. 1). However, the photocatalytic reactor is limited to two-dimensional contact with ultraviolet rays, photocatalysts, and reactants using bubbles formed by an appropriate flow rate, thereby reducing three types of contact efficiency, and because the appropriate flow rate is relatively low, a large amount of volatile organic compounds. There is a problem of not bonding to decompose the material.

Therefore, by eliminating the disadvantages of the photocatalytic reactors described above, the photocatalytic reactor not only makes the dispersion of the photocatalysts uniform, but also maximizes the contact between the ultraviolet light, the reactor body, and the photocatalyst, thereby improving the photolysis efficiency and increasing the processing capacity. There is a constant need for development.

In order to further improve the performance of the conventional fluidized bed photocatalytic reactor, the present inventors have replaced the wall of the fluidized bed photocatalyst reactor made of a conventional borosilicate glass tube with quartz which minimizes the loss of ultraviolet light energy, UV lamps are installed outside the riser, and the lean phase obtained by moderate gas flow increases to maximize the contact between UV light, the reactant and the photocatalyst to maximize the photolysis efficiency of trichloroethylene. The present invention has been completed by revealing that the photolysis treatment capacity can be maximized.

It is an object of the present invention to provide an improved circulating fluidized bed photocatalyst reactor having a lean phase.

It is still another object of the present invention to provide a photolysis method of a volatile organic compound using the improved circulating fluidized bed photocatalytic reactor.

1 is a schematic view showing a main body of a conventional annular fluidized bed photocatalyst reactor,

2 is a schematic diagram schematically showing a main body of a circulating fluidized bed photocatalytic reactor having a lean phase of the present invention;

3 is a graph showing the conversion rate of trichloroethylene in the circulating fluidized bed photocatalytic reactor having a lean phase of the present invention and a conventional Annulus fluidized bed photocatalytic reactor.

<Description of the symbols for the main parts of the drawings>

11: borosilicate glass wall surface, 15, 28: reactor body injection portion,

12, 22: ultraviolet lamp, 16, 27: reactor outlet,

13: photocatalyst, 17: generated bubble,

14, 23: porous dispersion plate, 21: riser,

25: downcomer, 24: photocatalyst recycle facility,

26: cyclone

In order to achieve the above object, the present invention comprises a riser tube made of a quartz tube and filled with a photocatalyst; A porous dispersion plate provided at a lower end of the riser; A reactive gas injection unit provided at the end of the porous dispersion plate; A cyclone connected to an upper portion of the riser; A downcomer provided on the cyclone lower end; A photocatalyst recycle facility connected to the porous dispersion plate and provided in the form of a loop-seal provided at the end of the downcomer; A reactor gas discharge part provided at an upper end of the cyclone and the rising pipe; And it provides a circulating fluidized bed photocatalyst reactor having a lean phase, including an ultraviolet lamp provided outside the riser.

In addition, the present invention comprises the steps of filling the photocatalyst in the riser of the circulating fluidized bed photocatalyst reactor; Injecting a volatile organic compound gas into the reactor injection unit; And it provides a method for photodegradation of volatile organic compounds, comprising the step of irradiating the ultraviolet light to the riser.

Hereinafter, the improved circulating fluidized bed photocatalytic reactor of the present invention will be described in detail with reference to the accompanying drawings.

The present invention comprises a riser tube 21 made of a quartz tube and filled with a photocatalyst; A porous dispersion plate 23 provided at the lower end of the riser 21; A reactive gas injection unit 28 provided at the end of the porous dispersion plate 23; A cyclone 26 connected to an upper portion of the riser 21; A downcomer 25 provided at the lower end of the cyclone 26; A photocatalyst recycling facility (24) connected to the porous dispersion plate (23) and in the form of a loop-room provided at the end of the downcomer (25); A reactor gas discharge part 27 provided at the uppermost ends of the cyclone 26 and the riser 21; And it provides a circulating fluidized bed photocatalyst reactor having a lean phase comprising an ultraviolet lamp 22 provided outside the riser (21).

At this time, the riser 21 is made of a quartz tube to efficiently transmit light energy such as ultraviolet rays to the photocatalyst to be efficiently transmitted therein, as well as by the gas flow rate introduced through the reactor injector 28. And the photocatalyst is diluted appropriately so as to become lean phase. In addition, the porous dispersion plate 23 supports the photocatalyst, the cyclone 26 collects the photocatalysts smoothly, the downcomer 25 is a function to deliver the collected photocatalysts to the recycling facility (28). Do it. In addition, the recirculation facility 28 functions to smoothly recycle the photocatalysts from the downcomer 25 to the upcomer 21 in the form of a loop-seal.

A cyclone 26 for collecting scattered photocatalyst is installed at an upper portion of the riser 21, and a lower portion of the cyclone 26 moves the collected photocatalysts in a vertical direction to a recycling facility 24. The downcomer 25 is installed, and a recycling facility 24 for smoothly recycling the photocatalyst to the upcomer 21 is installed at the end of the downcomer 25. At the end of the porous dispersion plate 23 and the top end of the cyclone 26 are provided with a reactive gas injection portion 28 and a reactive gas discharge portion 27, respectively, so that the reactive gas is a reactive gas injection portion 28 ), A porous dispersion plate 23, a riser 21 filled with a photocatalyst such as titanium dioxide, a cyclone 26 for collecting the photocatalyst, and a reactor for discharging the reactant from the upper end of the cyclone 26. Passed in the order of the discharge part 27. On the other hand, the ultraviolet lamp 22 is provided outside the rising tube 21 made of the quartz tube.

As such, the reactor of the present invention has the advantage of suppressing the generation of dead zones compared to the conventional fluidized bed reactor by forming a circulating fluidized bed to circulate the reactor body and the photocatalyst throughout the reactor. In the conventional two-dimensional fluidized bed reactor, the photocatalytic layer (so-called "dead zone") that does not participate in the reaction due to the poor circulation of the catalyst does not occur well, so that effective photolysis efficiency is hardly obtained. However, in the case of the circulating fluidized bed photoreactor of the present invention, the entire photocatalyst is circulated so that contact between the photocatalyst, the reactor body, and the ultraviolet light occurs uniformly. As a result, the generation of a photocatalyst layer (dead zone) that does not participate in the photoreaction is significantly suppressed, whereby an efficient photolysis efficiency can be obtained.

In addition, by attaching an ultraviolet lamp to the outside of the riser to make the amount of ultraviolet light emitted from the ultraviolet lamp uniform, the characteristics of the circulating fluidized bed obtained through the appropriate flow rates of the reactor body and the photocatalyst, together with the lean phase of the ultraviolet light and reaction Maximization of the contact between the gas and the photocatalyst can be achieved.

In the circulating fluidized bed photocatalytic reactor, the photocatalyst is coated on silica gel and its particle size is preferably 190 to 250 μm in diameter, and titanium dioxide (TiO ₂ ), tin dioxide (SnO ₂ ), and zinc oxide (ZnO). , Tungsten trioxide (WO ₃ ), ferric trioxide (Fe ₂ O ₃ ), cadmium sulfide (CdS), molybdenum disulfide (MoS ₂ ), cadmium selenide (CdSe) and molybdenum selenide (MoSe ₂ ) It is more preferable that it is at least one selected, and most preferably titanium dioxide (TiO ₂ ).

The riser 21 is filled with a photocatalyst, in order to improve the fluidization characteristics of the photocatalyst, it is preferable to use a photocatalyst coated on silica gel in place of the photocatalyst in a general powder state. Therefore, the size of the photocatalyst is suitably 190-250 μm, which is a fluidization property when the photocatalyst coated with silica gel having a relatively high UV transmittance and suitable physical properties is used in place of the small photocatalyst. This is because the contact between the ultraviolet light, the reactive gas and the photocatalyst is maximized as the result of the enhancement is to produce a suitable lean phase. In particular, silica gel is relatively porous as well as permeable to ultraviolet light, so it is easy to coat various catalysts including titanium dioxide in its pores.

In addition, as a photocatalyst, a compound of a general transition element may be widely used, but it is particularly preferable that the transition element is a compound combined with oxygen, sulfur, selenium, or the like. Titanium dioxide photocatalyst is an n-type semiconductor that converts light energy into chemical energy by causing electron transition (oxidation-reduction reaction) at the interface by using chemical energy of covalent holes and conduction band electrons generated by absorbing light. . Therefore, the titanium dioxide photocatalyst is relatively inexpensive, and it is possible to obtain renewable energy sources and chemically useful materials as well as to be applied to the oxidation decomposition reaction of hardly decomposable organic materials.

In the circulation fluidized bed photocatalytic reactor, the diameter of the riser 21 is preferably 13 to 20 mm.

As shown in FIG. 2, the riser 21 of the circulating fluidized bed photocatalytic reactor of the present invention is manufactured using a quartz tube having a suitable diameter. At this time, the inner diameter of the riser 21 should be maintained at 13 to 20 mm so that the reactor inside can be uniformly irradiated by ultraviolet rays. The reason for this is that when the inner diameter of the riser 21 does not reach 13 mm, the passage amount of the reactor body becomes small, and when it exceeds 20 mm, the intensity of ultraviolet rays irradiated to the gas passing through becomes nonuniform, resulting in photocatalytic decomposition reaction. This is because there is a problem that does not occur evenly.

In addition, in the circulating fluidized bed photocatalytic reactor, the pore size of the porous dispersion plate 23 is preferably an average diameter of 100 to 220 ㎛.

The lower end of the riser 21 is provided with a porous dispersion plate 23 having a plurality of small pores. The porous jet plate 23 supports a photocatalyst made of titanium dioxide and the like, and the reactor body is dispersed in the riser 21 to generate a uniform lean phase. To this end, the pore size of the porous dispersion plate 23 is such that the average diameter is 100 to 200 ㎛. When the average diameter of the pores of the porous dispersion plate 23 does not reach 100 μm, the pressure of the reactor is increased so that lean phases are not uniformly produced. When the thickness exceeds 200 μm, the photocatalyst blocks the pores. Therefore, the photocatalytic reaction does not occur evenly.

In addition, the present invention comprises the steps of filling the photocatalyst in the riser 21 of the circulating fluidized bed photocatalyst reactor; Injecting a volatile organic compound gas into the reactive gas injection unit (28); And it provides a photolysis method of a volatile organic compound, comprising the step of irradiating ultraviolet light to the riser (21).

The ultraviolet lamp 22 is provided outside the riser 21 made of a quartz tube to provide a contact and photolysis capacity between the ultraviolet ray, the reactive body, and the photocatalyst through a lean phase obtained by a suitable gas flow rate to initiate the photocatalytic reaction. It maximizes the photodegradation efficiency and throughput of volatile organic gas.

At this time, the photocatalyst is coated with silica gel titanium dioxide (TiO ₂ ), tin dioxide (SnO ₂ ), zinc oxide (ZnO), tungsten trioxide (WO ₃ ), ferric trioxide (Fe ₂ O ₃ ), cadmium sulfide ( CdS), molybdenum disulfide (MoS ₂ ), cadmium selenide (CdSe) and molybdenum selenide (MoSe ₂ ) is preferably at least one selected from the group consisting of volatile organic compounds in the reactor injection portion 28 The flow rate of gas injection is preferably 1.1 to 1.9 m / s. In addition, the volatile organic compound gas is preferably selected from the group consisting of trichloroethylene (TCE), ethanol, methanol, acetone, toluene, acetaldehyde, propanol, formic acid and benzene, most preferably trichloroethylene desirable.

Hereinafter, the operation and effects of the improved circulating fluidized bed photocatalytic reactor of the present invention will be described.

In the circulating fluidized bed photocatalytic reactor of the present invention, when the reaction gas is injected from the reactor injection portion 28 and the reactor fluidized through the porous dispersion plate 23 maintains a proper gas flow rate, the riser 21 filled with the photocatalyst is provided. A lean image is formed within). At this time, ultraviolet rays are irradiated from the ultraviolet lamp 22 to maximize the contact between the ultraviolet rays, the reactor body, and the photocatalyst to increase the photolysis efficiency, and then the reactor body passes through the reactor body discharge part 27 and is discharged out of the reactor. The photocatalyst is collected in the cyclone 26 and passes through the downcomer 25, and then is injected into the upcomer 21 from the downcomer 25 through a recycling facility having a loop-chamber shape.

The circulating fluidized bed photocatalytic reactor having the lean phase of the present invention converts a conventional borosilicate glass tube used as a wall of a conventional photocatalytic reactor into a quartz tube, and has an ultraviolet lamp 22 outside the quartz tube and is suitable in the riser 21. The thin phase generated by maintaining the gas flow rate maximizes the contact between the ultraviolet light, the reactant and the photocatalyst. This maximizes the photolysis efficiency of volatile organic compound gases such as trichloroethylene and minimizes the loss of ultraviolet light energy. In addition, it is possible to obtain an additional effect of making the intensity of ultraviolet rays irradiated on the reactor body and the titanium dioxide photocatalyst uniform throughout the entire surface of the photocatalytic reactor and reducing the production cost.

Hereinafter, the present invention will be described in more detail with reference to Examples.

However, the following examples are merely to illustrate the invention, it will be apparent to those skilled in the art that the contents of the present invention is not limited to the following examples.

Example 1 Fabrication of Improved Circulating Fluidized Bed Photocatalytic Reactor

The present inventors have a riser tube 21 made of a quartz tube having a diameter of 13 mm; A porous dispersion plate 23 including pores having an average diameter of 160 μm at the lower end of the riser 21; A reactive gas injection unit 28 provided at the bottom of the porous dispersion plate 23; A cyclone (26) for smoothly collecting photocatalysts at the upper portion of the riser (21); A downcomer 25 having a diameter of 22 mm to transfer the photocatalysts collected from the cyclone 26 to a recycling facility; A loop-chamber recycling facility for smoothly recycling the photocatalysts from the downcomer 25 to the upcomer 21; A reactor gas discharge part 27 provided at an upper end of the cyclone 26; And the main body of the circulating fluidized bed photolysis reactor composed of an ultraviolet lamp 22 provided on the outside of the riser (21) (Fig. 2).

Finally, 80 g of the titanium dioxide photocatalyst coated with 0.3 g of titanium dioxide was coated on 1 g of silica gel (average diameter of 270 μm) by the sol gel method in the riser 21 of the purified fluidized bed photocatalytic reactor. To complete the circulating fluidized bed photolysis reactor.

Example 2 Photodegradation Effect of Trichloroethylene Using the Circulating Fluidized Bed Photocatalytic Reactor

<2-1> Photolysis Measurement of Trichloroethylene by Circulating Fluidized Bed Photocatalytic Reactor

Trichloroethylene gas was injected through the reactor body injection part 28 at the bottom of the porous dispersion plate 23 of the circulating fluidized bed photolysis reactor prepared in Example 1. Specifically, the experiment was carried out while varying the initial concentration at the inflow to 99 to 500 ppm while maintaining the injection flow rate of trichloroethylene gas at 1.3 m / s. Trichloroethylene concentration was measured by measuring the change in the trichloroethylene concentration discharged to the reactor outlet 27 by irradiating ultraviolet light (I max = 254 nm, intensity = 32 mW / cm 2) at each trichloroethylene injection concentration. The conversion rate was calculated. At this time, the concentration of trichloroethylene discharged was measured using an HP 6890 II (HP, USA) instrument, trichloroethylene conversion was calculated using the following equation:

Trichloroethylene conversion = (initial concentration-post reaction concentration) / initial concentration

<2-2> Photolysis Measurement of Trichloroethylene Using a Conventional Annulus Fluidized Bed Photocatalytic Reactor

Two borosilicate glass plates 100 mm in width and 250 mm in height were attached at intervals of 4 mm, and a porous dispersion plate 14 including pores having an average diameter of 140 μm was provided at the bottom thereof. The main body of the conventional annular fluidized bed photocatalytic reactor (FIG. 1) equipped with a reactor injection portion 15 and an outlet portion, respectively, was prepared and the same photocatalyst as in Example 1 (titanium dioxide photocatalyst coated with titanium dioxide on silica gel) 1) 80 g was charged. As shown in FIG. 1, a conventional annular fluidized bed photocatalyst reactor was manufactured in a form in which ultraviolet rays (I max = 254 nm, intensity = 32 μs / cm 2) were irradiated inside the reactor. The initial reactant flow rate of trichloroethylene as in Example <2-1> was maintained at 1.2 m / s, and the initial concentration of the gas injected into the photocatalytic reactor was changed from 100 ppm to 498 ppm. After irradiating ultraviolet rays and measuring the concentration of trichloroethylene gas discharged from the outlet of the reactor, trichloroethylene conversion was measured by applying the same formula as in Example <2-1>.

<2-3> Comparison of Photolysis Measurement of Trichloroethylene by Circulating Fluidized Bed Photocatalytic Reactor and Annular Fluidized Bed Photocatalytic Reactor

The result of Example <2-1> and Example <2-2> was compared (FIG. 3). In FIG. 3, (-● --- ●-) is the conversion rate of trichloroethylene according to the initial concentration by the circulating fluidized bed photocatalytic reactor having the lean phase of the present invention, and (-▲ --- ▲- ) Represents the conversion of trichloroethylene with the initial concentration by the conventional Annulus fluid bed photoreactor. In the case of using the circulating fluidized bed photocatalytic reactor having the lean phase of the present invention, the trichloroethylene conversion was changed depending on the initial concentration of the injected reactor, but the trichloroethylene was significantly higher than the conventional annular photocatalytic reactor at the initial initial concentration. It was confirmed that the conversion rate (Fig. 3).

As described above, the circulating fluidized bed photocatalytic reactor of the present invention converts a conventional borosilicate glass plate used as a wall surface into a quartz tube and arranges an ultraviolet lamp outside the riser tube, thereby radiating light of ultraviolet rays irradiated onto the reactant and photocatalyst. The irradiation efficiency of the energy was maximized and the irradiation intensity of ultraviolet rays was constantly controlled. In addition, through the lean phase obtained through a suitable gas flow rate in the riser, the contact between the ultraviolet ray, the reactor body, and the photocatalyst was maximized. As a result, it was possible to considerably increase the photolysis capacity and reaction efficiency and to reduce the manufacturing cost of the reactor.

Claims (11)

A rising tube 21 made of a quartz tube and filled with a photocatalyst; A porous dispersion plate 23 provided at the lower end of the riser 21; A reactive gas injection unit 28 provided at the end of the porous dispersion plate 23; A cyclone 26 connected to an upper portion of the riser 21; A downcomer 25 provided at the lower end of the cyclone 26; A recirculation facility connected to the porous dispersion plate 23 and having a loop-chamber shape provided at an end of the downcomer 25; A reactor gas discharge part 27 provided at the uppermost ends of the cyclone 26 and the riser 21; And an ultraviolet lamp (22) provided outside the riser (21), wherein the circulating fluidized bed photocatalyst reactor has a lean phase. The reactor of claim 1, wherein the photocatalyst is coated on silica gel and has a particle size of 190 to 250 μm. The method of claim 2, wherein the photocatalyst is titanium dioxide (TiO ₂ ), tin dioxide (SnO ₂ ), zinc oxide (ZnO), tungsten trioxide (WO ₃ ), ferric trioxide (Fe ₂ O ₃ ), cadmium sulfide (CdS And molybdenum disulfide (MoS ₂ ), cadmium selenide (CdSe), and molybdenum selenide (MoSe ₂ ). The reactor of claim 3, wherein the photocatalyst is titanium dioxide (TiO ₂ ). The reactor according to claim 1, wherein the diameter of the riser is 13 to 20 mm. The reactor according to claim 1, wherein the pore size of the porous dispersion plate has an average diameter of 100 to 220 µm. Charging a photocatalyst into the riser (21) of the circulating fluidized bed photocatalytic reactor having the lean phase of claim 1; Injecting a volatile organic compound gas into the reactive gas injection unit (28); And irradiating ultraviolet rays to the riser (21). The method of claim 7, wherein the photocatalyst is coated with silica gel titanium dioxide (TiO ₂ ), tin dioxide (SnO ₂ ), zinc oxide (ZnO), tungsten trioxide (WO ₃ ), ferric trioxide (Fe ₂ O ₃ ) And at least one selected from the group consisting of cadmium sulfide (CdS), molybdenum disulfide (MoS ₂ ), cadmium selenide (CdSe), and molybdenum selenide (MoSe ₂ ). 8. The method of claim 7, wherein the flow rate for injecting the volatile organic compound gas into the reactive gas injection unit (28) is 1.1 to 1.9 m / s. The method of claim 7, wherein the volatile organic compound gas is selected from the group consisting of trichloroethylene (TCE), ethanol, methanol, acetone, toluene, acetaldehyde, propanol, formic acid and benzene. 11. The method of claim 10, wherein the volatile organic compound gas is trichloroethylene.