JPH06334A - Filter for dust removal and denitration - Google Patents

Abstract

PURPOSE:To carry out a dust removal and a denitration collectively without need of a wide installing area by attaching a bag filter to a honeycomb style supportor supporting a denitration catalyst and treating a waste gas to be treated which is formed by mixing ammonia into a waste gas contg. soot and dust and nitrogen oxides. CONSTITUTION:A bag filter 2 consisting of a wavon fabric or non-wavon fabric of fiber is attached to an inside or an outside honeycomb style supporter 1 made of titanium oxide, zeolite, etc., supporting a denitration catalist made of gold, platinum, etc. By using the filter for the dust removal and the denitration, waste gas contg. the soot and dust and the nitrogen oxides is further injected with ammonia for a denitration and is treated. Thus, the dust removal and the denitration are collectively carried out and lowering of a denitration efficiency caused by attachment and sedimentation of the soot and the dust is prevented, and a soot and a dust attached to the filter are cleaned and removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter for treating exhaust gas which has both dust removing ability and denitrifying ability.

Exhaust gas discharged from incinerators such as large amounts of dust and industrial waste discharged from general households and various factories contains harmful substances such as nitrogen oxides in addition to dust particles. Processing has become an important issue. As shown in FIG. 6, an exhaust gas treatment apparatus which has been used generally in the past and has a relatively high treatment efficiency includes a denitration device (12) and a bag filter (2) attached to a metal net-like holder (11). Since it is composed of the dust remover (13) provided, there is a problem that not only a large installation area is required, but also the denitration device and the dust remover must be individually controlled, which makes the operation complicated. is there.

As one of the solutions to such a problem, a technology for collectively treating dust particles and nitrogen oxides by using a catalyst filter for treating combustion exhaust gas, which is formed by coating a denitration catalyst (titanium oxide) on an inorganic fiber Has been proposed (see Japanese Patent Laid-Open No. 3-221146). However, when using this type of filter, not only the dust removal efficiency but also the denitrification efficiency decreases due to the adhesion and accumulation of dust particles on the fiber surface, and in addition, when cleaning the filter to remove the accumulated dust particles. However, from the viewpoint of preventing peeling and separation of the catalyst layer, there is a drawback that sufficient cleaning cannot be performed because sufficient wind pressure or mechanical vibration cannot be applied to the filter. Further, since the filter itself does not have a sufficient shape-retaining property, it is necessary to additionally use a holder during use.

[0004]

SUMMARY OF THE INVENTION In view of the above situation in the field, the present invention is not only capable of performing dust removal and denitration collectively without requiring a large installation area, but also denitration by deposition of dust particles. The purpose of the present invention is to provide a filter for treating exhaust gas that does not have a decrease in efficiency, can be sufficiently cleaned, and does not require a holder.

[0005]

That is, the present invention relates to a dust-removing denitration filter comprising a bag-like filter mounted on a honeycomb-shaped holding body carrying a denitration catalyst.

The present invention will be described below with reference to the accompanying drawings showing preferred embodiments of the present invention. FIG. 1 is a plan view showing an embodiment of the dust removal denitration filter according to the present invention. FIG. 2 is a schematic elevation view seen from the line AA of FIG.
FIG. 3 is a partially enlarged exploded elevational view of FIG. Figure 4
FIG. 1 is a schematic configuration diagram of a pulse jet type exhaust gas treatment apparatus equipped with a dust removal denitration filter according to the present invention. Figure 5
FIG. 1 is a schematic configuration diagram of a reverse pressure blow-off type exhaust gas treatment apparatus equipped with a dust removal denitration filter according to the present invention.

The dedusting denitration filter according to the present invention is constructed by mounting a bag filter (2) on a honeycomb-shaped holder (1) carrying a denitration catalyst. When the exhaust gas is processed by the pulse jet method, the bag filter (2) is attached to the outside of the honeycomb-shaped holder (1) (see FIG. 4), but when the exhaust gas is processed by the reverse pressure blow-off method. The bag filter (2) is attached to the inside of the honeycomb-shaped holder (1) (see FIG. 5).

The denitration catalyst supported on the honeycomb-shaped holder (1) is a catalyst that has been conventionally used for denitration treatment of exhaust gas, for example, gold, platinum, palladium, silicon oxide, aluminum oxide, titanium oxide, iron oxide. , Copper oxide, vanadium oxide, manganese oxide, chromium oxide, molybdenum oxide, tungsten oxide and the like 1
One kind or two or more kinds of catalysts may be appropriately used. The amount of the denitration catalyst supported may be appropriately determined depending on the type of catalyst, catalytic activity, type of carrier, concentration of nitrogen oxides in the exhaust gas, etc., but is usually 0.1 to 50% by weight.

Honeycomb-shaped holder on which the above catalyst is supported
Examples of the material of (1) include zeolite, silica, alumina, titanium oxide and the like, but titanium oxide and zeolite are preferable from the viewpoint of holding strength and specific surface area.

Honeycomb support (1) carrying a denitration catalyst
The general production method of the carrier powder is a carrier powder such as titanium oxide or zeolite (the particle size is not particularly limited, but usually 0.1 μm to
1 mm) and a catalyst such as the above metal oxide are mixed,
This is a method of press-molding into a predetermined honeycomb shape and then firing.

The honeycomb of the holder (1) is usually in a rectangular or rhombic shape, and the honeycomb has a structure in which the gas passage area decreases toward the center of the holder (1). When the exhaust gas is treated by the pulse jet method as shown, the flow rate of the gas to be treated increases as it progresses, and therefore the molecular diffusion increases, so that the denitration efficiency is improved.

Dimensions of the holding body (1), for example, inner diameter (K in FIG. 1), outer diameter (L in FIG. 1), depth of catalyst layer, thickness of catalyst layer, total circumferential division number, outer peripheral portion of through hole Pitch (a in FIG. 3), inner peripheral pitch of the through hole (b in FIG. 3), outer periphery of the through hole (in FIG. 3)
c), the inner periphery of the through hole (d in the figure), the height of the catalyst layer unit,
Number of catalyst layers and equivalent diameter of through holes (= hole cross-sectional area x 4 /
(Hole inner peripheral length) and the like may be appropriately selected according to the amount of exhaust gas to be treated, the concentration of nitrogen oxides in the exhaust gas, the catalytic activity, the specific surface area and the retention strength, etc., but are not particularly limited, but are commonly used. The dimensions are as follows.

Inner diameter: 10 to 500 mm Outer diameter: 20 to 500 mm Depth of catalyst layer: 5 to 100 mm Thickness of catalyst layer: 0.1 to 5 mm Total number of divisions: 4 to 100 divisions / one rotation Outer periphery of through hole Pitch: 3 to 75 mm Inner circumference of through hole Pitch: 2 to 70 mm Outer periphery of through hole: 2 to 75 mm Inner periphery of through hole: 1 to 70 mm Height of catalyst layer unit: 50 to 1000 mm Number of steps of catalyst layer: 1 -10 Equivalent diameter of through hole (exhaust gas inlet side): 1 to 75 mm Equivalent diameter of through hole (exhaust gas outlet side): 1 to 75 mm

The bag filter (2) mounted on the outer side or the inner side of the holding body (1) is a bag filter conventionally used for dust removal of exhaust gas from incinerators, for example, inorganic fiber or Teflon. , Heat-resistant nylon, polyimide, carbon fiber, stainless steel and a mixture of the above, and a woven or non-woven bag filter may be appropriately used.

The usage of the above-mentioned dust removal denitration filter according to the present invention is roughly classified into the usage of the pulse jet type as shown in FIG. 4 and the usage of the reverse pressure blow-off type as shown in FIG. .

In the case of the pulse jet type shown in FIG. 4,
The exhaust gas discharged from the incinerator (not shown) (the temperature is usually adjusted to about 500 to 100 ° C and the catalytic activity is lowered when the temperature is lower than 100 ° C), the ammonia inlet is provided.
Ammonia for denitration is injected from (4), and the mixed gas (the concentration of ammonia is injected corresponding to the concentration of nitrogen oxides, usually 0 to 1000 ppm) is the exhaust gas inlet.
After passing through the dust removal denitration filter which is introduced from (7) into the main body of the exhaust gas treatment device and is equipped with the bag filter (2) on the outside of the honeycomb-shaped holding body (1) disposed in the main body of the device, It is discharged from the exhaust gas discharge port (8) to the outside of the system. Since dust removal and denitration of exhaust gas can be performed by a single filter, it is not necessary to separately provide a denitration device as in the case of the conventional device (see FIG. 6). The dedusting denitration filter is supported by the supporter (3). Bag filter (2)
When the clogging of the occurs, the air compressor (6)
By sending the compressed air from the inside to the dust removing denitration filter, the dust adhering to the bag filter (2) is wiped off, and the dust is discharged from the dust discharge port (10) to the outside of the system. In addition, from the viewpoint of energy saving, resource saving and environmental pollution prevention, a part of the exhaust gas after being treated with a filter is used together with the air introduced from the air inlet (9) and the fan.
By using (5), it is possible to recirculate it to the treatment line and use it for cooling the exhaust gas to be treated, and at the same time, reuse part of the remaining ammonia.

The flow velocity of the exhaust gas in the system depends on the form and size of the holder (1), the type of bag filter, the amount of exhaust gas to be treated,
It depends on the amount of dust and nitrogen oxides in the exhaust gas and the catalytic activity, and is not particularly limited, but the flow rate that is usually adopted when using a holder or bag filter having the above-described form and dimensions is as follows. Is as follows: Flow rate at exhaust gas inlet: 0.1-5 m / min Flow rate at exhaust gas outlet: 0.1-5 m / min SV in catalyst bed: 50-30,000 hr ^-1 Average filtration rate: 0 1 to 5 m / min

The reverse pressure blow-off type exhaust gas treating apparatus shown in FIG. 5 has a bag filter inside the honeycomb-shaped holder (1).
A filtration chamber (16) in which a dust removal denitration filter formed by mounting (2) is supported and arranged by a bottom plate (14),
The main body of the exhaust gas treatment device including the filtration tension chamber (17) and the hopper (15) is connected in parallel through the damper (18) in three units. The process for filtering the exhaust gas and the bag filter (2) The reverse pressure step of removing the dust adhering to) is performed alternately, and the exhaust gas is continuously treated (in Fig. 5, the right and middle units indicate the state of filtering, the left unit the reverse pressure). State). In the case of this embodiment, the treated exhaust gas containing ammonia injected from the ammonia inlet (4) passes from the exhaust gas inlet (7) into the hopper (15), and then from the inside of the bag filter (2) to the holder ( After being sent to 1) and subjected to dust removal and denitration treatment, it is discharged from the exhaust gas discharge port (8) to the outside of the system through the filtration tension chamber (17). Also in this case, a part of the treated exhaust gas is recirculated together with the air introduced from the air introduction port (9), and this is used for cooling the exhaust gas to be treated and a part of the remaining ammonia is reused. can do. The dust from the clogged bag filter (2) is removed by the back pressure from the fan (5).

In the case of the embodiment shown in FIG. 5 as well, the flow rate of exhaust gas in the system is not particularly limited, but the flow rate normally adopted when using the holder or bag filter having the above-described form and dimensions is as follows. As follows: Flow rate at exhaust gas inlet: 0.1-5 m / min Flow rate at exhaust gas outlet: 0.1-5 m / min SV in catalyst bed: 50-30,000 hr ^-1 Average filtration rate: 0.1-5m / min

[0020]

EXAMPLES Examples 1 to 6 for explaining the present invention by way of examples In accordance with the following preparation methods, the denitration catalysts having the configurations shown in FIGS. A honeycomb-shaped holding body made of titanium oxide supporting vanadium oxide, copper oxide, aluminum oxide, and tungsten oxide was obtained. Preparation method of support: As denitration catalyst, V ₂ O ₅ 34 wt
%, CuO 15 wt%, WO ₃ 1 wt% and γ-Al ₂ O
The ₃ 50 wt% of the mixture is mixed with titanium oxide carrier was baked for 30 minutes at 400 ° C. after drying. The supported amount of the catalyst after firing was 10 wt%.

A pulse jet type exhaust gas treating apparatus (Examples 1 to 3) shown in FIG. 4 is a dust removing denitration filter in which a bag filter (material: glass cloth) is attached to the outside or inside of the obtained honeycomb-shaped holder. The apparatus was incorporated into the reverse pressure blow-off type exhaust gas treatment apparatus (Examples 4 to 6) shown in FIG. 5, and the treated exhaust gas containing 100 to 500 ppm of ammonia in the exhaust gas from the incinerator was treated using these apparatuses. The exhaust gas treatment conditions and the denitration rate and dust removal rate are shown in Tables 1 and 2 below.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

EFFECTS OF THE INVENTION According to the present invention, it is possible to perform dust removal and denitration collectively without requiring a large installation area, and there is no reduction in denitration efficiency due to deposition of dust particles.
Moreover, it becomes possible to sufficiently remove and clean the dust particles adhering to the filter, and it is not necessary to separately provide a holder.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a dust removal denitration filter according to the present invention.

FIG. 2 is a schematic elevation view seen from the line AA of FIG.

3 is a partially enlarged exploded elevational view of FIG.

FIG. 4 is a schematic configuration diagram of a pulse jet type exhaust gas treatment apparatus equipped with a dust removal denitration filter according to the present invention.

FIG. 5 is a schematic configuration diagram of a reverse pressure blow-off type exhaust gas treatment apparatus equipped with a dust removal and denitration filter according to the present invention.

FIG. 6 is a schematic configuration diagram of a conventional exhaust gas treatment apparatus equipped with a bag filter.

[Explanation of symbols]

 1 Honeycomb-shaped holder 2 Bag filter 3 Supporter 4 Ammonia inlet 5 Fan 6 Air compressor 7 Exhaust gas inlet 8 Exhaust gas outlet 9 Air inlet 10 Dust outlet 11 Metal mesh holder 12 Denitration device 13 Dust remover 14 Bottom plate 15 Hopper 16 Filtration chamber 17 Filtration tension chamber 18 Damper

Claims (3)

[Claims] 1. A honeycomb-shaped holding body carrying a denitration catalyst.
A dust-removing denitration filter comprising a bag filter (2) attached to (1). 2. A method for treating exhaust gas, which comprises treating an exhaust gas to be treated in which ammonia is mixed with an exhaust gas containing dust and nitrogen oxides, by using the dust-removal denitration filter according to claim 1. 3. The exhaust gas treatment method according to claim 2, wherein a part of the treated exhaust gas is recirculated to the treatment line.