JPH053213Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention relates to a laser photoreactor.
Specifically, the present invention relates to improvements in photochemical reactors that cause chemical reactions using laser light.

BACKGROUND ART A conventional laser photoreactor has a configuration as shown in FIG. 3, for example. In Fig. 3, 11 is the reactor main body, 12 is the raw material that undergoes a chemical reaction with laser light, 13 is the stirrer, 14 is the circulation pump, 15 is the entrance window, 16 is the shielding material such as graphite, and 17 is the laser beam. It is light. That is, the laser beam 17 is irradiated from an entrance window 15 provided on one side wall of the reactor main body 11 and transmitted through the raw material 12, and the transmitted laser beam 17 is received by a shielding material 16 provided on the other side wall. It's summery.

Problems to be Solved by the Invention In the conventional laser photoreactor shown in FIG. The problem is that the irradiation volume becomes extremely small and the reaction rate is low. Second, if the beam intensity of the laser beam 17 is increased in order to increase the irradiation volume, not only will the entrance window 15 be damaged, but the raw material 12 near the entrance will be irradiated with extremely strong laser beam 17. This is undesirable because side reactions other than the desired reaction, such as evaporation and ionization, occur, and even if such extreme phenomena do not occur, the problem is that the irradiation intensity is higher than that required for the reaction, making it inefficient. There is a point. Thirdly, in order to solve the first and second problems above, there is a method of expanding the beam diameter of the laser beam 17 in advance, but the entrance window 15 becomes large, which is disadvantageous in terms of cost. , when pressurizing or depressurizing, there is a problem that a large entrance window 15 cannot be created. Fourth, since irradiation is limited to the vicinity of the entrance, careful stirring and circulation are required, which requires relatively large equipment, increasing equipment and operating costs. . Fifth, for the reasons mentioned above, there is a problem in that the laser beam 17 cannot be effectively irradiated to raw materials that have a high absorption rate or to raw materials that react with low intensity relative to the beam intensity. The present invention aims to solve these problems.

Means for solving the problem: A lens that magnifies the laser beam is installed on the top wall of the reactor body, and the expanded laser beam is irradiated from above onto the free surface of the raw material inside the reactor body. I made it. Further, a lens purge gas introduction pipe was provided on the top wall to blow purge gas onto the lower surface (inner surface) of the lens.

Function: By installing a lens that magnifies the laser beam on the top wall of the reactor body, the entrance window can be minimized, the incidence loss of the laser beam is reduced, and the optimum intensity of irradiation is achieved. It becomes possible.
In addition, purge gas is blown onto the lower surface (inner surface) of the lens from the lens purge gas introduction tube to maintain the sharpness of the lens.

Embodiment FIG. 1 shows a first embodiment of the present invention. In Fig. 1, 1 is the reactor main body, which is cylindrical with a bottom and a top wall 1a, and its horizontal cross section is basically circular or rectangular, similar to the cross-sectional shape of the expanded laser beam. The closer to the shape the better. 2
is a lens purge gas introduction pipe attached to the top wall 1a. 3 is a lens installed in the center of the top wall 1a, which in this embodiment is a concave lens;
It magnifies a laser beam, which will be described later, and the shorter the focal length is within a comfortable range, the lower the height of the reactor body 1 can be. Reference numeral 4 denotes a laser beam direction converter, which will be described later, and in this embodiment, it consists of a mirror, and since the laser beam is normally emitted horizontally, it converts it into a vertical direction. 5
is a stirrer to stir the raw materials described below. Reference numeral 6 denotes a gas introduction pipe through which raw material gas is introduced during gas-liquid reaction. 7 is a raw material, which is in the form of liquid or slurry. 8 is a laser beam, which may be either continuous or pulsed. Reference numeral 9 denotes a gas venting pipe attached to the top wall 1a, which is used for lens purge gas, gas introduction,
Venting the gas or gases of gaseous reactants, if any. 10 is a gas, which is an inert gas for the reaction or a raw material gas when performing a gas-liquid reaction.

In the laser light reactor configured as shown in FIG. 1, laser light 8 is magnified by a lens 3 and irradiated (radiated) onto the liquid surface, which is the free surface of the raw material 7, from above. This causes the raw material 7 to undergo a predetermined chemical reaction. Note that the light intensity required for the reaction or the margin should be considered, and the light intensity should be expanded to be slightly higher than that. In addition, if any deposits occur on the inner surface of the lens 3, such deposits are prevented by blowing an inert gas such as nitrogen gas onto the lens 3 through the lens purge gas introduction pipe 2.

Next, a design example will be described. A certain chemical solution has a wavelength
With 308nm laser light, the incident intensity is 10mW/cm ²
The reaction occurs effectively, but at that time, most of the light is absorbed (0.01mW/cm ² ) at a depth of 1cm. Now, let us consider the case where a 20W (beam diameter 1 x 2 cm) Xecl excimer laser (wavelength 308 nm) is used to efficiently cause a reaction in the laser photoreactor shown in Figure 1. Lens 3, transmittance 90%, focal length 60mm
A concave lens made of synthetic quartz is used.

Irradiation area = 20 x 0.9 ÷ 0.01 = 30 x 60 (cm ² ), from which the height of the lens 3 from the liquid surface is 60 mm x 60 cm/2 cm - 60 mm = 1740 mm. Irradiation volume = 30 x 60 x 1 = 18000 (cm ³ ).

Therefore, in the conventional method, the incident intensity is 10000 mW/cm ² , which is not only too strong but also reduces the transmission length to 1 cm x (loge10000/0.01)/(loge10/0.01) = 2c
m, the irradiation volume is 2 x 2 = 4 (cm ³ ), so the irradiation volume is 18000cm ^{3 when using the laser photoreactor shown in Figure 1, whereas it is 4cm 3} using the conventional method. ³ , so there is an incomparable difference, 4/18000 = 1/4500.

FIG. 2 shows a second embodiment of the invention. This second embodiment differs from the first embodiment only in that a convex lens is used for the lens 3, and an isosceles right triangular prism is used for the direction changer 4 of the laser beam 8. are the same, so detailed illustrations are omitted.

Effects of the invention The present invention installs a lens that magnifies the laser beam on the top wall of the reactor body, and irradiates the expanded laser beam onto the free surface of the raw material inside the reactor body from above. As a result, the irradiation volume can be extremely large for materials with high light absorption, increasing the reaction rate, and the laser light intensity required for reaction is small compared to the beam intensity. , it is possible to efficiently irradiate a large irradiation volume with light without irradiating with a stronger intensity than necessary. Moreover, even though the lens system at the light incidence part of the reactor body is small, it is possible to obtain a large irradiation area. Therefore, since the lens system is small, it is possible to meet the conditions for pressurization and depressurization. Can be set in a wider range. In addition, when the raw material is in liquid or slurry form, the lens does not come into direct contact with the raw material, so it is possible to minimize the adhesion of products that often occur in photochemical reactors. For this purpose, purge with an inert gas such as nitrogen gas using a lens purge gas inlet tube. Furthermore, when performing a gas-liquid reaction, the reaction can be easily carried out by using the gas phase as a raw material gas, and gas can also be introduced by providing a gas introduction pipe. Furthermore, since the structure is simple and a large power unit is not required, equipment costs and operating costs can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a sectional front view showing a first embodiment of the present invention, Fig. 2 is a partially cutaway sectional front view showing a second embodiment of the invention, and Fig. 3 is an example of a conventional technique. FIG. DESCRIPTION OF SYMBOLS 1... Reactor main body, 1a... Top wall, 2... Lens purge gas introduction pipe, 3... Lens, 7... Raw material, 8... Laser light.

Claims (1)

[Scope of utility model registration request] A reactor body containing raw materials to undergo a chemical reaction by laser light, and a reactor body installed on the top wall of the reactor body to expand the laser light downward to reach the free surface of the raw materials inside the reactor body. A laser photoreactor comprising: a lens for irradiating light from above; and a lens purge gas introduction tube installed on the top wall for blowing an inert gas onto the lower surface of the lens.