JPS5813215B2 - catalytic reactor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a catalytic reactor, and more particularly to a catalytic reactor that has excellent durability against wear caused by dust in gas.

BACKGROUND ART Conventionally, a parallel flow type catalyst such as a plate-shaped or honeycomb-shaped catalyst has been used as a catalyst for exhaust gas denitrification for gas containing a lot of dust in order to prevent clogging of the catalyst layer by dust.

These catalysts generally consist mainly of metal oxides, are often formed into a porous structure to improve their activity, are weak in strength, and often have insufficient abrasion resistance.

Therefore, for gases containing dust that easily wears out the catalyst, such as coal combustion exhaust gas, the gas flow velocity in the catalyst layer cannot be increased very much, and is usually about 4 to 6 m/s.

However, when the gas flow rate is restricted as described above as a condition for using the catalyst, restrictions are placed on the arrangement of the reactor, etc., resulting in a complicated arrangement, which often increases the overall product cost.

For example, when the required denitrification rate is low and the amount of catalyst is small, it is advantageous to incorporate the catalytic reactor 4 between the economizer 2 and air heater 3 of the boiler 1 as shown in Fig. 1 because the arrangement is simple. However, since the gas flow velocity in the duct before and after the reactor 4 is usually 10 to 15 m/s, the gas flow velocity in the reactor is also close to 10 m/s, and the above gas flow rate limiting condition is satisfied. exceed.

Therefore, in such a case, as shown in FIG. 2, the duct must be lengthened and the reactor 4 must be placed in a separate arrangement, which has the disadvantage of increasing manufacturing costs.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art described above, and to provide a catalytic reactor in which the catalyst is less likely to be worn out even by gas containing dust and can withstand high gas flow rates.

In the present invention, a plate-shaped catalyst is slightly inclined with respect to the gas flow direction, and the surface of the catalyst plate facing upstream of the gas is made of a wear-resistant material such as metal, and the surface facing downstream is made of a catalytic material. It is.

Hereinafter, the present invention will be explained in more detail with reference to embodiments shown in the drawings.

FIG. 3 and FIG. 4 are a cross-sectional view and a perspective view showing the positional relationship between plate-shaped catalysts arranged in a catalytic reactor.

In the figure, the catalyst plate 5 is inclined at an angle θ to the gas flow direction 6 and is fixed in the reactor by suitable support means (not shown).

The surface 7 of the catalyst plate facing the gas upstream side is made of a wear-resistant material such as metal, and the surface 8 facing the downstream side is made of a catalytic material.

Such a plate-shaped catalyst can be easily manufactured by, for example, roughening the surface of a wear-resistant material such as a metal plate and attaching and holding a catalyst material to the surface.

The inclination angle θ of the catalyst plate is preferably in the range of 5 to 15 degrees, although it depends on conditions such as the dust concentration in the exhaust gas and the gas flow rate.

If the inclination angle is too large, pressure loss will increase, while if it is too small, the prevention of wear on the catalyst surface, which is the object of the present invention, will be insufficient.

The above-mentioned plate-shaped catalyst is arranged in multiple stages so as to have slopes in opposite directions alternately in the gas flow direction. However, if the length 9 of the catalyst in the gas flow direction is too long, the gas flow between the catalyst plates will be rectified. Since the direction of the catalyst plate and the direction of dust flow are the same, the catalyst material 8 is also worn away.

Therefore, the length 9 of the catalyst plate is adjusted to a length (for example, 100 to 200 mm) that does not cause rectification.

By arranging the catalyst as described above, the dust entrained in the gas collides only with the wear-resistant material surface 7 of the catalyst 5.
Since the surface 8 of the catalytic material is in the shade, there is less dust collision and therefore the abrasion of the catalyst can be prevented.

For this reason, for example, in the case of exhaust gas denitration, the catalyst can be used even at a high gas flow rate of about 10 m/s.

As described above, according to the present invention, wear of the catalyst due to dust in the gas can be reduced by arranging the plate-shaped catalyst obliquely with respect to the gas flow direction.

Therefore, the gas flow rate within the reactor can be increased, and since there is no restriction on the gas flow rate, the apparatus can be simplified, and other excellent effects can be obtained.

[Brief explanation of drawings]

Figures 1 and 2 are schematic layout diagrams of a catalytic reactor connected to a boiler, and Figures 3 and 4 are examples of the arrangement of plate catalysts in the catalytic reactor of the present invention, respectively. FIG. 2 is a cross-sectional view and a perspective view. 1... Boiler, 4-catalytic reactor, 5... Itabuse catalyst,
7... Wear-resistant material (surface), 8... Catalyst material (surface).

Claims (1)

[Claims] 1. In a catalytic reactor in which a plurality of plate-shaped catalysts are arranged parallel to the gas flow direction, the plate-shaped catalysts are slightly inclined with respect to the gas flow direction, and the gas upstream side of the catalyst plate surface is A catalytic reactor characterized in that the surface facing the downstream side is made of a wear-resistant material and the surface facing downstream is made of a catalytic material. 2. The catalytic reactor according to claim 1, wherein the plate-shaped catalysts are arranged in a plurality of stages so that the plate-shaped catalysts have dome slopes that alternate in opposite directions along the gas flow direction. 3. The catalytic reactor according to claim 1 or 2, wherein the plate-shaped catalyst has an oblique angle of 5 to 15 degrees.