JPH0515739A - Denitration reducing agent supply device and denitration reducing agent decomposition catalyst - Google Patents

Abstract

(57) [Summary] [Object] To provide a denitration reducing agent supply device which uses a solid reducing agent that is easier to handle than ammonia and has sufficient denitration performance in a limited space. By contacting a reducing agent B, such as urea, which is a solid nitrogen-containing compound at room temperature and atmospheric pressure, and a heating gas (air, etc.) A containing steam, with a reducing agent dispersion catalyst 8 such as alumina or silica, The reducing agent B is decomposed into ammonia. This is injected from the injection nozzle 7 into the exhaust gas duct of the combustion device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flue gas denitration technology by a catalytic reduction method, and more particularly to a denitration apparatus suitable for performing a denitration reaction by using a solid reducing agent which is safe and easy to handle as a reducing agent.

[0002]

2. Description of the Related Art NOx in smoke emitted from power plants, various factories, automobiles, etc. is a causative substance of photochemical smog, and ammonia (NH
Flue gas denitration method by selective catalytic reduction using ₃ ) as a reducing agent is widely used mainly in thermal power plants.

Recently, cogeneration systems using diesel engines, gas turbines, etc. are increasing mainly in urban areas, and NOx emission regulations are applied to these systems as well, and strengthened in some regions. Therefore, it is an urgent task to install a flue gas denitration device as in large plants. Since such denitration equipment for small-scale facilities is used in densely populated areas such as buildings, liquefied NH ₃
Is difficult to apply. Therefore, a method of using a solid reducing agent such as urea, cyanuric acid, melamine, and ammonium hydrogen carbonate, which is easy to handle and safe, has been attracting attention in place of liquefied NH ₃ .

FIG. 8 shows an example in which the denitration apparatus process using the solid reducing agent for denitration is applied to a cogeneration plant using a diesel engine. The cogeneration system usually includes a diesel engine 1 that serves as power for power generation, an exhaust heat recovery boiler 3 that recovers exhaust heat from the diesel engine 1, and a chimney 4. Due to recent environmental problems, in order to remove nitrogen oxides in the exhaust gas, the denitration device 2 is installed in the diesel engine 1 in which the exhaust gas temperature is in the optimum temperature range of the catalyst.
An injection nozzle, which is installed at the outlet and injects the reducing agent, is installed in the duct 5 between the diesel engine 1 and the denitration device 2. The reducing agent injected here is mixed with nitrogen oxides in the exhaust gas and introduced into the denitration device 2.

Here, in order to react the nitrogen oxides uniformly dispersed in the exhaust gas with the solid reducing agent, it is necessary to sufficiently vaporize the solid reducing agent and sufficiently mix both. Therefore, for example, the following two methods are used as a method of using a solid reducing agent. One is a method in which a reducing agent aqueous solution is directly sprayed into exhaust gas and evaporated, and as a patent related to this, for example, Japanese Patent Laid-Open No. 53-62772.
JP-A-53-64102, JP-A-53-1122
No. 73 and JP-A No. 53-115658.

The method of spraying the reducing agent aqueous solution directly into the exhaust gas to evaporate has the following problems. For example, when an aqueous urea solution is used, this aqueous solution is introduced into the exhaust gas flue, so the exhaust gas temperature drops, and when sulfur oxides are present in the exhaust gas, NH generated by decomposition of urea is generated.
_The reaction between ₃ and sulfur oxides causes precipitation of acidic ammonium sulfate, which adversely affects downstream equipment. Furthermore, in this method, the drain may be accumulated in the flue or the moisture may be scattered to the denitration catalyst layer installed on the downstream side, which may adversely affect the catalyst performance.

Another method is a method in which a solid reducing agent is directly sprayed into the exhaust gas duct to be vaporized. Since this method supplies urea in a solid state, the contact mixing property with the exhaust gas is poor, and safe vaporization of the solid reducing agent is not easy,
There was a problem that urea did not vaporize and remained in the flue.

Therefore, a method is known in which the solid reducing agent is not directly sprayed into the exhaust gas but the solid reducing agent is once decomposed by a decomposition catalyst and used for exhaust gas denitration. In this method, as shown in FIG. 9, a layer composed of the decomposition catalyst 8 is installed in the duct 5 on the upstream side of the denitration device 2, and injection is performed from an injection nozzle 7 installed in the upstream of the layer composed of the decomposition catalyst 8. When the solid reducing agent is brought into contact with the layer composed of the decomposition catalyst 8, decomposition is promoted and is guided to the downstream NOx removal device 2 to be subjected to NOx removal treatment. This system is effective in the case of clean exhaust gas containing no dust, but in the case of exhaust gas containing dust, the dust in the exhaust gas and the molten solid reducing agent are mixed, and the decomposition catalyst 8 does not decompose. May adhere to and solidify. Therefore, when treating an exhaust gas containing dust in the exhaust gas, as described in JP-A-2-268811, a decomposer for decomposing the solid reducing agent outside the exhaust gas duct into a system different from the exhaust gas system. Is most suitable, and the solid reducing agent is once decomposed and then injected into the exhaust gas in a gas state.

[0009]

However, the above-mentioned Japanese Unexamined Patent Application Publication No.
According to the denitration method described in Japanese Patent No. 268811, in a solid reducing agent decomposition reaction tower, urea is allowed to flow down in a zigzag manner while being melted on a baffle plate and gradually decomposed. Since the heat for the decomposition of urea is supplied by steam from outside the decomposition reaction tower, the central part of the decomposition reaction tower is
It is difficult to transfer sufficient heat. Moreover, since the decomposition reaction of urea is an endothermic reaction, it is difficult to raise the temperature of the baffle plate. Therefore, urea is likely to change into another polymer while flowing down the baffle plate, and there is a possibility that it will adhere to and solidify on the baffle plate.

Therefore, an object of the present invention is to provide a denitration reducing agent supply device and a denitration reducing agent decomposition catalyst for surely decomposing an easy solid reducing agent into ammonia and supplying it to exhaust gas. It is in.

[0011]

The above object of the present invention is achieved mainly by the following constitutions. That is, of the heating gas and steam, at least one of the gas supply port, a reducing agent supply port made of a solid nitrogen-containing compound at room temperature and normal pressure, and a reducing agent decomposition catalyst layer are provided inside, and the reducing agent is In a denitrification device equipped with a reducing agent decomposer for decomposing to produce ammonia and a pipe for supplying the ammonia to combustion exhaust gas,
The reducing agent decomposer is a denitration reducing agent supply apparatus provided with a mixing means including a mechanism for swirling the reducing agent, heated gas, and steam.

Air, nitrogen, oxygen or exhaust gas may be used as the heating gas, and steam in the exhaust gas may be used as the steam.

The reducing agent decomposer may be provided with a heating means for heating the reducing agent and the heated gas. Preferably, the reducing agent decomposition temperature is adjusted to 250 ° C to 500 ° C.

Here, urea, cyanuric acid, melamine, biuret, ammonium carbonate or ammonium hydrogencarbonate can be used as the reducing agent, and alumina, silica, silica-alumina, calcia, magnesia or titania can be used as the reducing agent decomposition catalyst. One or more selected from the group consisting of single or mixed metal oxides and zeolites are used.

Further, the decomposition temperature of the reducing agent is 250 ° C. to 50 ° C.
By setting the temperature to 0 ° C., the result that the decomposition rate into ammonia is high can be obtained.

For example, the mixing means is provided with a reducing agent charging port and a heating gas / steam charging port separately installed in the reducing agent decomposing unit so that the reducing agent decomposing unit can be filled with the reducing agent, the heating gas and the steam. Turn.

Exhaust gas from the combustion apparatus is used as a source of heated gas and steam, a reducing agent inlet is provided in the exhaust gas flue, and the exhaust gas flue near the reducing agent inlet is formed into a cyclone to mix the reducing agent and the heated gas. You may.

[0018]

When urea is used as an example of the solid reducing agent, it is generally known that urea decomposes as follows when heated to 350 ° C. or higher. (NH ₂ ) ₂ CO → NH ₃ + HNCO (1) Furthermore, isocyanic acid (H
NCO) is hydrolyzed according to the formula (2) when water vapor coexists. HNCO + H ₂ O → NH ₃ + CO ₂ (2) On the other hand, isocyanic acid becomes cyanuric acid according to the formula (3) at 350 ° C. or lower. 3HNCO → (HNCO) ₃ (3) Further, urea is 4 when the water vapor coexists in the atmosphere.
It is known to hydrolyze according to formula (4) at a temperature of 00 ° C or higher. (NH ₂ ) ₂ CO + H ₂ O → 2NH ₃ + CO ₂ (4) The reactions of the formulas (1), (2) and (4) are remarkable on the solid surface of metal oxides such as alumina and silica-alumina or zeolites. Be promoted. FIG. 7 shows the conversion rate of urea to NH ₃ by the hydrolysis reaction, but the hydrolysis temperature in the presence of the metal oxide and the like is about 100 ° C. lower than that in the absence thereof. It is considered that the metal oxide or the like has a hydrolysis catalytic action. Therefore, by using the metal oxide or the like as a catalyst for hydrolysis, NH ₃ can be effectively produced from the reducing agent.

In the present invention, as the metal oxide or the like, alumina, silica, silica-alumina, calcia, magnesia, titania, zeolite, etc. may be used, but in order to accelerate thermal decomposition and / or hydrolysis reaction, solid Those having strong acidity or basicity are effective, and two or more kinds of metal oxides and the like may be combined and used. In order to increase the solid acidity of the above metal oxides, nickel (Ni), tungsten (W), vanadium (V), iron (Fe), molybdenum (Mo), cobalt (Co), manganese (Mn), It is also effective to add a transition metal component such as copper (Cu) to the carrier.

When treating an exhaust gas containing dust in the exhaust gas, it is advantageous to provide a decomposer for decomposing the solid reducing agent in a system different from the exhaust gas system outside or inside the duct.
As shown in FIG. 1, for example, as shown in FIG. 1, the structure of this reducing agent decomposing unit is such that the decomposing unit 6 has a cylindrical tube filled with a decomposing catalyst 8, and the upper part of the cylindrical decomposing unit 6 has a conical shape. An inlet 9 for introducing the solid reducing agent B is provided, and an inlet 10 for the heated air A containing steam serving as a heat source for decomposing the solid reducing agent is provided in the tangential direction of the circle of the plane cross section in the lateral direction of the conical portion. Has been. The solid reducing agent B charged from the upper charging port 9 is conveyed while being heated by the heated air A charged from the charging port 10, decomposed by the action of the decomposition catalyst 8, and injected into the exhaust gas by the injection nozzle 7. .

When the solid reducing agent B is charged, the solid reducing agent feeder cannot be installed on the decomposer 6 due to the arrangement and the compressed air is present in the duct. It is common to carry by.

However, of the solid reducing agents B, if urea is taken as an example, since urea melts at 132 ° C., it cannot be conveyed by heated air. Therefore, for example, as shown in FIG. 3, a urea charging port 9 and a heated air charging port 10 containing water vapor.
And must be provided separately. In this case, urea can be more evenly dispersed on the upper surface of the layer composed of the decomposition catalyst 8 when charged from above. On the other hand, when the heating air A is fed from the same direction as the urea, the urea carrier air close to room temperature and the heating air at a high temperature cannot be uniformly mixed, and a temperature distribution is generated in the upper part of the layer composed of the decomposition catalyst 8 and In the lower part, there is a possibility that the polymer cannot be sufficiently decomposed to cause a polymerization reaction and adhere to the upper surface of the layer composed of the decomposition catalyst 8 to cause clogging. Therefore, heated air A
Will be input in the horizontal direction. As a result, a swirl flow can be generated inside the decomposer 6. The carrier air is entrained in this swirling flow, mixed, and flows into the layer formed of the decomposition catalyst 8. On the other hand, urea falls vertically due to the weight of urea and the acceleration during transportation. At this time, when the upper part of the decomposer 6 is a flat surface and the diameter of the decomposer 6 increases, the heated air inlet 10 containing water vapor becomes far from the swirling flow, and the effect of entraining the carrier air is lost. For this reason, by making the upper part of the decomposer 6 into a conical shape, the swirl flow can effectively entrain the carrier air.

In the experiments conducted by the inventors, the final velocity of the carrier air was calculated from the particle size, weight, etc. of urea, and it was confirmed that it was optimal to carry the carrier air through the pipe at 8 to 20 m / s. In addition, the urea injection angle in this state is as wide as the natural gas injection angle of 24 degrees. Therefore, when the divergence angle of the conical portion is set to be equal to or less than the divergence angle of urea, urea also rides on the swirling flow of the heated air, receives heat inside the decomposer 6, melts, and adheres without being decomposed. Therefore, it is necessary to set the spread angle of the conical portion to be equal to or larger than the injection angle of urea.

Although not limited to the decomposer 6 shown in FIG.
By installing the reducing agent decomposition catalyst packed bed in the downstream portion of the cylindrical portion of the decomposer, the decomposition reaction of the reducing agent can be completed before the adhered solidified material of the reducing agent and the dust in the exhaust gas is formed. Furthermore, by covering the inner wall surface of the decomposer with a reducing agent decomposition catalyst, the reducing agent is decomposed and flows down toward the lower part of the cylindrical portion, increasing the decomposition rate. Further, by providing a means for heating the inner wall surface of the decomposer 6, the decomposition reaction of the reducing agent can be promoted.

[0025]

EXAMPLES Next, the present invention will be described in more detail by way of examples. Although urea is used as an example of the solid reducing agent in this example, similar results can be obtained with cyanuric acid, melamine, biuret, ammonium carbonate and ammonium hydrogen carbonate.

In the urea decomposition test, 100 ml of a urea decomposition catalyst, which was molded by granules or tablet molding and then divided into 4-6 mm φ, was charged into a reaction vessel, and air and water were passed at a speed of 20,000 h ^-1. , Under the condition that the urea decomposition catalyst is set to a predetermined temperature, urea is N / NO molar ratio in urea to NOx in diesel engine exhaust gas = 1.2 (urea / NO molar ratio = 0.6) It was dropped together with a considerable amount of urea and air, and the ratio (conversion rate (%)) of NH ₃ in the generated urea decomposition gas to each theoretical production amount was calculated. The analysis of NH ₃ in the urea decomposition gas was performed by an ion chromatography method.

The denitration test was carried out by adding the urea decomposition gas to the exhaust gas discharged from the 25 kw power generation diesel engine. The composition of exhaust gas varies slightly depending on the load condition of the engine, but is almost 3% by volume of oxygen and 12% of carbon dioxide.
Volume%, water 5 volume%, NOx 500ppm, sulfur dioxide 500ppm, carbon monoxide 1,000ppm, gas amount 8
0 Nm ³ / h, temperature 350 ° C., AV 21 m / s,
A titanium oxide-based plate catalyst was used as the denitration catalyst.

The NOx content is measured by a chemiluminescence type NOx meter, and the NOx decomposition rate (denitration rate) is calculated by the formula (5) by measuring the NOx concentration before and after the urea decomposition gas addition. ) Was calculated. Denitration rate = [{NOx (inlet) -NOx (outlet)} / NOx (inlet)] x 100 (%) (5)

Example 1 As a catalyst for urea decomposition, γ-alumina particles manufactured by Kishida Chemical Co., Ltd. were used, and the temperature on the alumina was set to 380 ° C. to decompose urea, and the conversion rate to NH ₃ was measured. . Further, the generated urea decomposition gas was added to the exhaust gas of the diesel engine, and the denitration rate was measured. The results are shown in Table 1 below.

Examples 2 to 7 As catalysts for urea decomposition, silica particles manufactured by Kishida Chemical Co., Ltd., silica-alumina particles, zeolite (NaY) manufactured by Nishio Industry Co., Ltd., and reagents manufactured by Kishida Chemical Co., Ltd. were used. Using calcia, magnesium and titania obtained by tablet molding, the temperature on each urea decomposition catalyst was set to 380 ° C,
In the same manner as in Example 1, the conversion rate to NH ₃ and the denitration rate were measured. The results are shown in Table 1 below.

[0031] Using Kishida Chemical Co., Ltd. γ- alumina granules as Example 8 Urea cracking catalyst, the temperature on the urea decomposition catalyst as 400 ° C., to decompose the urea, in the same manner as in Example 1 NH ₃ And the denitrification rate were measured. The results are shown in Table 1 below.

Example 9 Using γ-alumina granular material manufactured by Kishida Chemical Co., Ltd. as a urea decomposition catalyst, the temperature on the urea decomposition catalyst was set to 350 ° C. to decompose urea, and NH ₃ was converted in the same manner as in Example 1. The conversion rate and denitrification rate were measured. The results are shown in Table 1 below.

Example 10 Silica-alumina particles manufactured by Kishida Chemical Co., Ltd. were used as a urea decomposition catalyst, and the temperature on the urea decomposition catalyst was set to 400.
At a temperature of ℃, urea was decomposed, and the conversion rate to NH ₃ and the denitration rate were measured in the same manner as in Example 1. The results are shown in Table 1 below.

Example 11 Silica-alumina particles manufactured by Kishida Chemical Co., Ltd. were used as a urea decomposition catalyst, and the temperature on the urea decomposition catalyst was set to 350.
At a temperature of ℃, urea was decomposed, and the conversion rate to NH ₃ and the denitration rate were measured in the same manner as in Example 1. The results are shown in Table 1 below.

[0035] Using Kishida Chemical Co., Ltd. γ- alumina granules as Example 12 Urea cracking catalyst, the temperature on the urea decomposition catalyst as 200 ° C., to decompose the urea, in the same manner as in Example 1 NH ₃ And the denitrification rate were measured. The results are shown in Table 1 below.

[0036] Using Kishida Chemical Co., Ltd. γ- alumina granules as Example 13 Urea cracking catalyst, the temperature on the urea decomposition catalyst as 600 ° C., to decompose the urea, Example 1 in the same manner as NH ₃ And the denitrification rate were measured. The results are shown in Table 1 below.

[0037] The glass beads granules used as a comparative example 1 Urea cracking catalyst, the temperature on the urea decomposition catalyst and 380 ° C., to decompose the urea, conversion and denitrification rate to Example 1 in the same manner as NH ₃ Was measured. The results are shown in Table 1 below.

[0038] The glass beads granules used as a comparative example 2 Urea cracking catalyst, the temperature on the urea decomposition catalyst and 600 ° C., to decompose the urea, conversion and denitrification rate to Example 1 in the same manner as NH ₃ Was measured. The results are shown in Table 1 below.

Comparative Examples 3 and 4 Stannous oxide and stannic oxide obtained by tablet-molding reagents manufactured by Kishida Chemical Co., Ltd. were used as urea decomposition catalysts.
The temperature on the urea decomposition catalyst was set to 380 ° C., urea was decomposed, and the conversion rate to NH ₃ and the denitration rate were measured as in Example 1. The results are shown in Table 1 below. In the case of tin oxide, since it has a high oxidizing ability, it does not generate NOx and does not generate urea or N
It is thought to oxidize H ₃ .

[0040]

[Table 1] An example of a decomposing agent for a denitration reducing agent will be described below based on Examples 1 to 13 above.

Example 14 The deoxidizer reducing agent decomposer 6 shown in FIG. 1 has a diameter of 200.
φ, urea amount of about 800 g / h, reaction temperature of 390 ° C., and urea was decomposed by using γ-alumina granules manufactured by Kishida Chemical Co., Ltd. as a decomposition catalyst.
Of NH ₃ to NH ₃ was measured. In addition, as a result of performing a verification test with a 200 kw diesel engine exhaust gas for power generation using this decomposer 6, an exhaust gas amount of 1200 Nm ₃ / h,
A denitration rate of 90% or more was confirmed under conditions of an inlet NOx of 530 ppm and an exhaust gas temperature of 350 ° C.

Example 15 This example is shown in FIG. In this embodiment, a cracking catalyst 8 is coated on the inner wall of a cracker 6 having a cylindrical shape and a lower portion having a funnel shape, and an injection nozzle 7 is provided below the cracker 6. Then, the inlet 10 for the heated air A containing water vapor is provided laterally above the decomposer 6 so that the heated air A is swirled in the decomposer 6. The urea inlet 9 to the decomposer 6 is installed in the vicinity of or at the same position as the heated air inlet 10, and urea is placed on the swirling flow of the heated air A containing steam, and the urea is decomposed to cover the inner wall of the decomposer 6. It contacts the layer of the catalyst 8, flows into the lower part while decomposing, and is injected into the exhaust gas from the injection nozzle 7.

Embodiment 16 FIG. 3 shows the present embodiment. FIG. 3 is a modification of the fifteenth embodiment shown in FIG. In the apparatus shown in FIG. 2, of the urea charged from the upper part of the decomposer 6, the urea that did not ride the swirling flow of the heated air containing steam and flowed into the lower part, or the decomposition catalyst surface could not be completely decomposed. Objects may flow into the bottom. On the other hand, as shown in FIG. 3, the cracking catalyst 8a is filled in the lower portion of the cracking catalyst 6 whose inner wall is covered with the cracking catalyst 8 to decompose the urea which cannot be decomposed by the swirling flow of the cracking catalyst 6 with this cracking catalyst 8a. Then, it is injected into the exhaust gas from the injection nozzle 7.

Embodiment 17 This embodiment is shown in FIG. FIG. 4 corresponds to a modification of the fifteenth embodiment shown in FIG. Since the decomposition reaction of the solid reducing agent such as urea is an endothermic reaction, the temperature of the portion where urea is coated on the inner wall of the decomposer 6 is lowered by the endothermic reaction.
In order to prevent this, a heater 11 for warming the inner wall of the decomposer 6 is installed as shown in FIG. As a result, the temperature of the layer of the decomposition catalyst 8 can always be kept stable.

Embodiment 18 This embodiment is shown in FIG. FIG. 5 is a modification of the fifteenth embodiment shown in FIG. 2, and FIG. 5 shows the decomposer 6 of FIG. 2 connected to an exhaust gas system. The inner wall of the cyclone-type decomposer 6 is coated with the decomposition catalyst 8 and installed in the upstream of the denitration device 2.
The inlet / outlet of the decomposer 6 is connected to the exhaust gas duct 5. Urea is charged from the urea charging port 9 of the cracker 6, and the charged urea rides on the exhaust gas and the swirling flow in the cracker 6 and is decomposed by coming into contact with the layer of the cracking catalyst 8 and is discharged to the denitration device 2 together with the exhaust gas. Be guided.

By carrying out the above Examples 14 to 18, it is effective to make the contact time between the decomposition catalyst and urea longer, and it is not necessary to simultaneously use other equipment for decomposing urea.

Embodiment 19 This embodiment is shown in FIG. This embodiment is the first embodiment shown in FIG.
The decomposer 6 of No. 4 is installed in the exhaust gas duct and applied to a large-scale boiler or the like.

In the upstream duct of the denitration device 2, the decomposition catalyst 8
A decomposer 6 filled with is installed. Further, the heated air required for urea decomposition is produced by exchanging heat with the exhaust gas by inserting the air pipe 14 into the duct, and is introduced into the upper conical portion of the decomposer 6. Urea is dropped vertically from a feeder 16 installed outside the duct above the decomposer 6. And
When decomposing urea by hydrolysis, it is necessary to introduce water vapor into the decomposing unit 6, and this water vapor is generated by using the water vapor produced by the evaporator 12 installed before or after the denitration device. , And put it in the conical portion above the decomposer 6. The urea decomposed by the decomposer 6 is injected into the exhaust gas from the urea injection nozzle 7 connected to the decomposer 6.

[0049]

The following effects can be obtained by adopting the present invention. (1) By using a metal oxide decomposition catalyst, the solid reducing agent can be decomposed at a relatively low temperature. (2) Since the solid reducing agent can be thoroughly decomposed by the heated reducing agent decomposition catalyst layer by thoroughly mixing the carrier air and the water vapor before injecting the solid reducing agent into the exhaust gas, conventional liquefaction A denitration technology equivalent to the NH ₃ method can be used. (3) When a cyclone system or the like is used as the solid reducing agent supply device, the solid reducing agent can be directly injected into the exhaust gas duct, so that no other device for decomposing the solid reducing agent is required all at once, which is simple. A denitration system can be provided.

[Brief description of drawings]

FIG. 1 is a structural diagram of a solid reducing agent decomposer of the present invention.

FIG. 2 is a structural diagram of a solid reducing agent decomposer of the present invention.

FIG. 3 is a structural diagram of a solid reducing agent decomposer of the present invention.

FIG. 4 is a structural diagram of a solid reducing agent decomposer of the present invention.

FIG. 5 is an exploded structural view of a cyclone as a solid reducing agent supply device of the present invention installed in an exhaust gas system.

FIG. 6 is a structural diagram in which the decomposer 6 of Embodiment 14 shown in FIG. 3 of the present invention is installed in an exhaust gas duct and applied to a large boiler or the like.

FIG. 7 is a diagram showing an example of the relationship between the temperature and the NH ₃ generation rate when urea is used.

FIG. 8 is a system diagram when a denitration device is installed in a cogeneration system that uses a diesel engine.

FIG. 9 is a denitration system diagram in which a decomposition catalyst is installed when a solid reducing agent is injected as a solid.

[Explanation of symbols]

2 Denitration equipment 6 decomposer 7 injection nozzle 8 Decomposition catalyst 9 Urea input port 10 Heated air inlet

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B01J 21/06 A 8017-4G 21/08 A 8017-4G 21/10 A 8017-4G 21/12 A 8017-4G 23/02 A 8017-4G 29/08 (72) Inventor Hiroshi Takeda No. 1280 Kamiizumi, Sodegaura-cho, Kimitsu-gun, Chiba Idemitsu Kosan Co., Ltd. (72) Naomi Imada 3 Takara-cho, Kure-shi, Hiroshima No. 36 Bab Kotuku Hitachi Co., Ltd. Kure Research Institute (72) Inventor Meiji Ito No. 36 Takara-cho, Kure City, Hiroshima Prefecture Bab Kotuku Hitachi Co. Hitachi Co., Ltd. Kure Research Institute (72) Inventor Hayato Morita 6-9 Takara-cho, Kure City, Hiroshima Prefecture Babkotsu Hitachi Co., Ltd. Kure Factory (72) Inventor Kiichi Mori 6-9 Takara-cho, Kure City, Hiroshima Prefecture Babkotsu Ku Hitachi Co., Ltd. Kure Factory (72) Inventor Yoshinori Nagai 6-9 Takaracho, Kure City, Hiroshima Prefecture Bab Kotsk Hitachi Co., Ltd. Kure Factory

Claims (12)

[Claims] 1. A supply port for at least one of heating gas and steam, a supply port for a reducing agent made of a solid nitrogen-containing compound at room temperature and normal pressure, and a reducing agent decomposition catalyst layer, In a denitration device equipped with a reducing agent decomposer for decomposing a reducing agent to generate ammonia and a pipe for supplying the ammonia to combustion exhaust gas, the reducing agent decomposer swirls the reducing agent, heated gas, and steam. A reducing agent supply device for denitration, comprising a mixing means including a mechanism. 2. A reducing agent supply device for denitration, wherein the reducing agent decomposer is provided with heating means for a reducing agent decomposition catalyst. 3. The denitration reducing agent supply apparatus according to claim 1, wherein urea, cyanuric acid, melamine, biuret, ammonium carbonate or ammonium hydrogen carbonate is used as the reducing agent. 4. The heating means of the reducing agent decomposition catalyst is 250 ° C. or higher.
The reducing agent supply device for denitration according to claim 2, wherein the temperature is adjusted to 500 ° C. 5. The reducing agent supply apparatus for denitration according to claim 1, wherein an inner wall surface of the reducing agent decomposer is coated with a reducing agent decomposition catalyst. 6. The denitration reducing agent supply apparatus according to claim 5, further comprising means for heating the inner wall surface of the reducing agent decomposer. 7. The apparatus for supplying a reducing agent for denitration according to claim 1, wherein a reducing agent decomposition catalyst packed bed is installed in a downstream portion of the reducing agent decomposer. 8. Exhaust gas from a combustion apparatus is used as the heating gas and steam, a reducing agent inlet is provided in the exhaust gas flue, and the exhaust gas flue near the reducing agent inlet is made into a cyclone shape to mix the reducing agent and the exhaust gas. The reducing agent supply device for denitration according to claim 1, wherein the reducing agent decomposer is capable of decomposing. 9. The reducing agent decomposer has a cylindrical main portion and a conical portion provided on the upper portion thereof, a reducing agent inlet is provided at the apex of the conical portion, and a heating gas inlet having a horizontal outlet is provided. 2. The denitration reducing agent supply apparatus according to claim 1, wherein an inlet for water vapor is provided in the conical portion, and an inlet for introducing the decomposed product of the reducing agent into the exhaust gas is provided below the cylindrical portion. 10. The reducing agent supply device for denitration according to claim 9, wherein the divergence angle of the conical portion at the upper part of the reducing agent decomposer is equal to or larger than the injection angle of the reducing agent from the reducing agent inlet. 11. The apparatus for supplying a reducing agent for denitration according to claim 9, wherein a reducing agent decomposition catalyst packed bed is installed below a cylindrical main portion of the reducing agent decomposer. 12. A single or complex metal oxide selected from alumina, silica, silica-alumina, calcia, magnesia, and titania as a reducing agent decomposition catalyst applied to the reducing agent supply device for denitration according to claim 1. And a reducing agent decomposition catalyst for denitration, characterized by using one or more selected from the group consisting of zeolite.