JP2003340440A - Method and apparatus for cleaning ammonia-containing waste water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for cleaning ammonia- containing waste water for preventing a decrease in catalytic performance as much as possibly and for decreasing the amount of toxic substances produced when ammonia removed from ammonia-containing waste water by stripping is detoxified by catalytic decomposition. <P>SOLUTION: The apparatus is composed of a stripping tower 7 as a means to bring the NH<SB>3</SB>-containing waste water into contact with a carrier gas to transfer NH<SB>3</SB>from the NH<SB>3</SB>-containing waste water to the gas phase, a gas cooler 17 as a means to remove a part of the water content in the gas containing NH<SB>3</SB>produced in the stripping tower 7, a preheater 11 as a means to heat the NH<SB>3</SB>-containing gas from which a part of the water content is removed in the cooler 17, and a catalytic tower 12 to bring the NH<SB>3</SB>-containing gas heated in the preheater 11 into contact with a catalyst to decompose the NH<SB>3</SB>into nitrogen and water. By removing the water content in the exhaust gas, the catalytic performance is maintained and the catalyst can be used for a long period of time. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying waste water, and in particular, effectively detoxifies ammonia (NH ₃ ) in waste water discharged from a thermal power plant into nitrogen (N ₂ ) and water (H ₂ O). The present invention relates to a method and an apparatus for purifying ammonia-containing wastewater that can be used.

[0002]

2. Description of the Related Art In recent years, interest in global environment conservation has increased and regulations have been enforced in 1993 as a countermeasure for eutrophication of sea areas. It has been demanded. On the other hand, conventionally, nitrogen removal (denitrification) from wastewater has been performed mainly by the following method.

(1) Biological treatment method: A method of mineralizing and detoxifying organic nitrogen in water using bacteria. (2) Discontinuous chlorination method: a method of oxidatively decomposing NH ₃ using sodium hypochlorite. (3) Ion exchange method: A method of adsorbing NH ₃ using zeolite. (4) Ammonia stripping method: A method of dissipating NH ₃ -containing wastewater into the air by using air or steam (Environment Creation, 8, (9), 67 (1987), etc.).

When the BOD in the wastewater is high, the biological denitrification method (1) is used, but most of the nitrogen in the wastewater from the process of the chemical factory or the wastewater after the wastewater treatment is ammonia or ammonium ion. The methods (2), (3), and (4) are applied to the treatment of wastewater containing ammoniacal nitrogen.

The above-mentioned prior art has the following problems. That is, in the method (1), since the reaction rate of the biological reaction is slow, the reaction tank required for the treatment becomes large, a large installation space is required, and excess sludge is generated. In the method (2), it is necessary to add sodium hypochlorite in an amount more than stoichiometrically necessary for complete removal of ammonia, which causes problems of treatment of residual chlorine and generation of organic chlorine compounds. The method of addition (3), the process for waste water containing a high concentration of ammonium ions during the zeolite regeneration occurs is required, (4) after the migration, NH ₃ containing gas is air dissipate NH ₃ in the gas phase Therefore, there is a problem of secondary pollution.

Among these methods, the stripping method (4) is relatively easy to process and has low equipment cost and operating cost, so that it is advantageous as compared with other methods. Therefore, the separated NH ₃ gas of high concentration is used as a catalyst. The method of making harmless comprehensively by combining with the method of oxidative decomposition is also adopted in the existing human waste treatment facility.

However, in the stripping catalytic oxidation system, a large amount of NOx is generated at the time of oxidizing NH _3, so that it is necessary to install a NOx reducing catalytic tower in addition to the NH ₃ oxidizing catalytic tower. Furthermore, according to the study of the inventors, NH ₃
It was found that a large amount of N ₂ O was generated during the oxidation. N ₂
O, like CO ₂ , is a substance that contributes to global warming,
The large amount of this released to the atmosphere is as harmful as the release of NH ₃ and is harmful in the global environment, which is not desirable. As described above, the NH ₃ -containing wastewater treatment in the prior art has many problems, and depending on the method, there is a problem that it may become a new source of generating various secondary pollutants.

Regarding this problem, Japanese Patent Laid-Open No. 2000-31
7272 (Applicant: Babcock Hitachi Ltd.)
Is proposed. FIG. 4 shows the above-mentioned Japanese Patent Laid-Open No. 2000-31.
7272 invention from coal-fired and heavy oil-fired thermal power plants
Wastewater containing ammonia nitrogen such as discharged wastewater
FIG. 6 is an explanatory view showing a flow of exhaust gas treatment when applied to
It In the figure, drainage A and alkali B are
It is supplied to the tank 3 from the pipes 1 and 2 and mixed in the tank 3.
After being combined, it is sent to the preheater 5 by the pump 4. Preheat
Wastewater A, which has been preheated to about 100 ° C in the vessel 5, passes through the pipe 6.
It is then supplied to the upper part of the stripping tower 7. Strip
The packing 8 is contained inside the ping tower 7,
Steam supplied from pipes 9 and 16 at the bottom of the tower as gas
The air C and the air D do not contact the wastewater A efficiently in the tower.
Rises inside the tower, and gas containing high-concentration ammonia gas
can get. NH in the obtained gas₃Concentration thousands to tens of thousands ppm
Is. The obtained gas is supplied from the pipe 10 as needed.
Preheater, possibly diluted by air D
After being preheated to a predetermined temperature at 11, it is led to the catalyst tower 12.
Be done. The stripped ammonia gas is the catalyst 13
Oxidatively decomposed above, N ₂And H₂Decomposed into O from pipe 14
Released into the atmosphere. This catalyst is nitrogen oxide NH₃To
The first component having reducing activity and NH₃From nitrogen oxides
A second component having the activity of producing (NOx)
It The reaction temperature in the catalyst layer 13 at this time is 250
-450 degreeC, Preferably it is 350-400 degreeC. Strike
Ammonia is fed from the pipe 15 at the bottom of the ripping tower 7.
The removed wastewater E is discharged.

[0009]

The above-mentioned NH ₃ -containing wastewater treatment method is characterized in that the generation of secondary pollutants is extremely small and the operation is easy. It was found that there is a problem that the NH ₃ concentration at the outlet of the catalyst tower becomes high depending on the properties, and this problem becomes remarkable when the catalyst is used for a long period of time.

The object of the present invention is to solve these problems,
An object of the present invention is to provide a method and an apparatus for purifying ammonia-containing wastewater, which can prevent deterioration of catalyst performance during long-term use and reduce the amount of harmful substances generated.

[0011]

Means for Solving the Problems In the course of conducting a long-term performance test of a catalyst for purifying ammonia-containing exhaust gas, the present inventors have found that when the catalyst deteriorates, the water concentration in the exhaust gas becomes the NH ₃ decomposition rate of the catalyst. As a result of extensive research, they have arrived at the present invention. That is, the invention claimed in the present application is as follows.

[0012] (1) in ammonia (NH ₃₎ method for purifying NH ₃ containing waste water to detoxify the NH ₃ in containing waste water is brought into contact with the NH ₃ containing waste water and the carrier gas N
A step of transferring NH ₃ from the H ₃ -containing wastewater into the gas phase,
A step of removing a part of the water content in the gas containing NH ₃ generated in the step, and an NH ₃ part of the water content removed in the step
The step of heating the contained gas, and the N heated in the heating step.
A method for purifying NH ₃ -containing wastewater, which comprises a step of bringing an H ₃ -containing gas into contact with a catalyst to decompose the NH ₃ into nitrogen and water.

[0013] (2) a step of removing a portion of the moisture in the gas containing NH _3, to lower the temperature of the gas, characterized in that condense remove moisture (1) NH ₃ according
Purification method of contained wastewater.

(3) The NH ₃ -containing wastewater according to (1) or (2), characterized in that the water concentration after removing a part of the water in the generated gas containing NH ₃ is 25% or less. Purification method.

[0015] (4) wherein said catalyst is a characterized by comprising a second component having a first component and nitrogen oxides from NH ₃ (NOx) activity to generate having a reducing activity due NH ₃ nitrogen oxides The NH _{3 according} to (1) or (2)
Purification method of contained wastewater.

(5) The first component of the catalyst is titanium (T
i) and an oxide of one or more elements selected from tungsten (W), vanadium (V) and molybdenum (Mo), and the second component of the catalyst is platinum (Pt), iridium (Ir) , A catalyst containing one or more oxides selected from silica, zeolite and alumina supporting one or more noble metals selected from rhodium (Rh) and palladium (Pd) (4 The method for purifying NH ₃ -containing wastewater according to 1).

(6) The method for purifying NH ₃ -containing wastewater according to (1) or (2), wherein the catalyst is zeolite.

(7) Ammonia (NH₃) Contained in wastewater
The NH₃Detoxifying NH₃For purification equipment of contained wastewater
And the NH₃Contact the contained wastewater and carrier gas
NH ₃From contained wastewater NH₃To transfer the gas into the gas phase
And NH generated by the means₃Part of the water content in the gas containing
For removing the water and N with a part of the water removed by the means
H₃Means for heating the contained gas, and heating by the heating means
NH₃When the contained gas is brought into contact with the catalyst, the NH₃The nitrogen
And a means for decomposing into water, NH₃Including
Wastewater purification device.

(8) The means for removing a part of the water in the gas containing NH ₃ is a device for lowering the temperature of the gas and condensing and removing a part of it (7) The NH ₃ -containing wastewater purification device described.

[0020] (9) wherein said catalyst is a characterized by comprising a second component having a first component and nitrogen oxides from NH ₃ (NOx) activity to generate having a reducing activity by NH ₃ nitrogen oxides The NH _{3 according} to (7) or (8)
Purification device for contained wastewater.

(10) The first component of the catalyst is an oxide of titanium (Ti) and one or more elements selected from tungsten (W), vanadium (V) and molybdenum (Mo), The second component of the catalyst is platinum (Pt),
A catalyst containing one or more kinds of oxides selected from silica, zeolite and alumina supporting one or more kinds of noble metals selected from iridium (Ir), rhodium (Rh) and palladium (Pd). (9)
The apparatus for purifying NH ₃ -containing wastewater according to 1.

(11) The apparatus for purifying NH ₃ -containing wastewater according to (7) or (8), wherein the catalyst is zeolite.

In the present invention, the NH ₃ -containing wastewater is treated with NH _3
As a means for transferring ₃ into the gas phase, for example, a method of blowing carrier gas into the waste water or spraying the waste water into the carrier gas to strip ammonia in the gas into the gas phase is used. The pH of stripping is 10
If it is above, as it is, if it is low, alkali such as sodium hydroxide or slaked lime is added to make it 10 or more, and air is brought into contact with this, and the air is used as a carrier gas to diffuse the ammonia gas. The carrier gas may be water vapor as well as air, but may be used without using the carrier gas.

As a means for heating the NH ₃ -containing gas,
A normal preheating method such as heat exchange with a high temperature gas such as a burner, steam or a catalyst device outlet gas may be used, but when circulating the gas, a method that does not change the gas composition, particularly the oxygen concentration (for example, heat exchange) is preferable . In the case of an NH ₃ decomposition catalyst having a denitration function, the temperature of the catalyst layer is 250-45.
It is important to set the temperature in the range of 0 ° C, preferably 350 to 400 ° C, and 450 to 600 in the case of a zeolite-based catalyst.
Although it is preferable to set the temperature to ℃, in any case, an appropriate temperature may be selected based on the characteristics of the catalyst.

The NH ₃ -containing wastewater mentioned here means wastewater discharged from sewage and night soil treatment facilities, etc., and combustion ash and SO ₂ gas in exhaust gas discharged from coal-fired and heavy oil-fired thermal power plants. Installed to remove the
It means wastewater containing ammonia nitrogen, such as wastewater discharged from dry electrostatic precipitator and wet desulfurizer.
In addition, wastewater after decomposing organic nitrogen in wastewater containing organic nitrogen into NH ₃ state nitrogen that can be stripped by general biological treatment, and high concentration discharged during zeolite regeneration by the conventional ion exchange method. such as NH ₃ containing waste water, waste water is also included which is converted to NH ₃ nitrogen by pretreatment.

[0026]

FUNCTION FIG. 5 shows a pore model of an NH ₃ decomposition catalyst having a denitration function used in the present invention. In FIG. 5, the pores of this catalyst have a structure in which micropores formed by silica pores are present in the macropores (first component) formed by the component that reduces NO by NH ₃ , From NH ₃ to NO in the micropore
A component (second component) having an activity of generating x is supported. NH ₃ diffuses into the macropores inside the catalyst, is oxidized according to the formula (1) on the second component to become NO, and collides with NH ₃ adsorbed inside the macropores in the process of diffusing out of the catalyst, It is reduced to N ₂ by the reaction of the formula (2), and becomes as shown in the formula (3) as a whole.

[0027]

[Equation 1] NH ₃ + 5 / 4O ₂ → NO + 3 / 2H ₂ O (1) NH ₃ + NO + 1 / 4O ₂ → N ₂ + 3 / 2H ₂ O (2) NH ₃ + 3 / 4O ₂ → 1 / 2N ₂ + 3 / 2H ₂ O (3) Thus, in the NH ₃ decomposition catalyst with the denitration function,
Since the oxidation reaction of H _{3 and} the reduction reaction by generated NO and NH ₃ proceed inside the catalyst, NH ₃ is reduced to N ₂ without generating NO or N ₂ O which is considered to be generated in the NO generation process. can do. Also, when zeolite is used as a catalyst, the production of NO and N ₂ O is extremely small.

However, even when such a catalyst is used, if the water concentration in the gas becomes high, NH 3 at the catalyst tower outlet will be generated.
_A phenomenon was observed in which the concentration of ₃ increased (the decomposition rate of NH ₃ decreased). The reason for the decrease in NH ₃ decomposition rate due to the increase in water concentration is not clear, but in order to prevent this, for example, by cooling the gas discharged from the stripping tower, some of the water in the gas is condensed, It was found that the decomposition rate of ammonia was significantly improved. As a means for cooling the gas, it is preferable to exchange heat with the waste water supplied to the stripping tower, which is effective from the viewpoint of thermal efficiency.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention shown in the drawings are as follows.
Will be described in more detail. FIG. 1 shows the NH of the present invention.₃Inclusion and elimination
Ammonia state discharged from thermal power plants depending on how water is treated
A theory showing the equipment system when applied to wastewater containing nitrogen
It is a clear view. This device is₃Contained wastewater and carrier gas
Contact the NH₃From contained wastewater NH ₃To the gas phase
The stripping tower 7 as a means for making the
NH generated in the topping tower 7₃Of water in gas containing
Gas cooler 17 as means for removing parts, and the cooler
NH with some water removed in 17₃Heating the gas contained
And a preheater 11 as a means for
NH₃When the contained gas is brought into contact with the catalyst, the NH₃Picking up
Mainly from the catalyst tower 12 as a means for decomposing into elementary water
Consists of

In the figure, wastewater A and alkali B are supplied to the tank 3 from the pipes 1 and 2, respectively, mixed in the tank 3 and then sent to the preheater 5 by the pump 4. The wastewater A preheated to about 100 ° C. by the preheater 5 is supplied to the upper part of the stripping tower 7 through the pipe 6.
Inside the stripping tower 7, there is a packing 8,
The vapor C and the air D supplied from the pipes 9 and 16 at the lower part of the tower as carrier gas rise in the tower while efficiently contacting the wastewater A in the tower, and a gas containing a high concentration of ammonia gas is obtained. The NH ₃ concentration in the obtained gas is several thousand to several tens of thousands ppm. The obtained gas is sent to the gas cooler 17, and the cooling water F supplied from the pipe 18 condenses and removes part of the water content in the gas. The condensed / removed water is returned to the tank 3 from the conduit 19. The water returned from the pipe 19 to the tank 3 contains a small amount of ammonia, so it may be reprocessed. However, depending on the concentration of the contained ammonia, it may be discharged as it is together with the treated wastewater E. Good. The gas from which a part of the water has been removed is diluted with the air D supplied from the pipe 10 if necessary, and in some cases preheated to a predetermined temperature by the preheater 11 and then introduced into the catalyst column 12. The stripped ammonia gas undergoes oxidative decomposition on the catalyst 13 to produce N ₂
Is decomposed into H ₂ O and released from the pipe 14 to the atmosphere. The water concentration at the catalyst tower outlet is measured by the water concentration measuring device 20 installed at the catalyst tower outlet, and the flow rate of the cooling water F supplied from the pipe 18 is controlled according to the measured value. The wastewater E from which ammonia has been removed is discharged from the pipe 15 at the bottom of the stripping tower 7. Here, the catalyst used was composed of a second component having a first nitrogen oxide from the ingredients and NH ₃ activity to generate (NOx) having a reducing activity by NH ₃ nitrogen oxides. The reaction temperature in the catalyst layer 13 at this time is 250 to 450 ° C, preferably 350 to 400 ° C.

Next, specific examples of the present invention will be described. Example 1 Slurry of metatitanate (TiO ₂ content: 30 wt%, S
O ₄ content: 8 wt%) 67 kg of ammonium paratungstate _{((NH 4) 10 H 10} · W 12 O 46 · 6H 2 O)
2.5 kg and 2.33 kg of ammonium metavanadate were added and kneaded using a kneader, and the obtained paste was granulated, dried and then calcined at 550 ° C. for 2 hours, and the obtained granules were crushed to The catalyst powder was one component. The composition of this powder is Ti / W / V = 91/5/4 (atomic ratio).
On the other hand, 1.33 × 10 ^-2 wt% chloroplatinic acid (H ₂ [P
tCl ₆ ] · 6H ₂ O) 1L, 500g of fine silica powder (trade name, Microcomputer F, manufactured by Tomita Pharmaceutical Co., Ltd.) was added, evaporated to dryness in a sand bath, and calcined in air at 500 ° C. for 2 hours. 0.01 wt% Pt.SiO ₂ was prepared and used as the catalyst powder of the second component.

Next, the first component 20 kg and the second component 40.1
g of silica / alumina inorganic fiber 5.3 kg, water 17 kg
In addition, kneading with a kneader gave a catalyst paste, which was not
The reticulate material made of E-glass fiber is used for titania and silica
Impregnated with slurry of polyvinyl alcohol and polyvinyl alcohol, 150
The catalyst base material is dried at ℃, and the catalyst is placed between the catalyst base materials.
The paste is sandwiched and rolled through rolling rollers to form a plate
The plate-shaped body was air-dried for 12 hours in the air, and then 5
NH with denitration function by firing at 00 ° C for 2 hours ₃Disassembly
Used as a medium. The first component and the second component of the second component in the catalyst are
The component / first component ratio is 0.2 / 99.8.

Using this catalyst, a wastewater treatment test was conducted under the apparatus shown in FIG. 1 and the conditions shown in Table 1. The effect of the water concentration in the gas at the catalyst tower on the ammonia concentration in the gas at the catalyst tower outlet is shown in FIG.

[0034]

[Table 1] As is clear from the results shown in FIG. 2, by maintaining the water concentration at the catalyst layer inlet at 25% or less, the ammonia concentration in the gas at the catalyst tower outlet can be reduced.
The lower the water concentration, the lower the ammonia concentration in the gas at the catalyst tower outlet, but if the water concentration is lower than necessary, the supply amount of the cooling water F and the heating energy in the preheater 11 will increase. become. Although it varies depending on the catalyst and the composition of waste water, the appropriate water concentration for maintaining the ammonia decomposition rate is about 15 to 25%, preferably 20 to 25%.
%Met.

According to the above-mentioned embodiment, by reducing the water concentration in the gas, in addition to the effect of reducing the ammonia concentration, the heating energy required for preheating to a predetermined temperature in the preheater 11 is reduced. be able to.

In the above embodiment, the gas temperature is lowered by using the gas cooler to condense and remove the water content in the gas. For example, water having a low temperature is sprayed into the gas or the water content is absorbed. Using substances to remove water in gas,
Any method that can reduce the water concentration in the gas can be used.

FIG. 3 is an explanatory view showing an apparatus system of a wastewater treatment method showing another embodiment of the present invention. In this embodiment, the waste water supplied to the stripping tower 7 is supplied to the gas cooler 1
7 to cool the gas at the outlet of the stripping tower to reduce the water concentration in the gas, raise the temperature of the waste water, and reduce the energy required for heating. That is, FIG.
In, the wastewater A and the alkali B are supplied to the tank 3 from the pipes 1 and 2, respectively, and after being mixed in the tank 3, a part of them is sent to the gas cooler 17 through the distributor 21 by the pump 4. The wastewater A is heated by the gas exiting the stripping tower 7 in the gas cooler 17, preheated to about 100 ° C. in the preheater 5 if necessary, and supplied to the upper portion of the stripping tower 7 through the pipe 22. In addition, the wastewater A that was not sent to the gas cooler 17 is about 1 in the preheater 5.
It is preheated to 00 ° C. and supplied to the upper part of the stripping tower 7 through the pipe 6. The stripping tower 7 contains a packing 8 therein, and the steam C and the air D supplied from the lower pipes 9 and 16 as carrier gas are efficiently contacted with the wastewater A in the tower and the inside of the tower. And a gas containing a high concentration of ammonia gas is obtained. The NH ₃ concentration in the obtained gas is several thousand to several tens of thousands ppm. The obtained gas is sent to the gas cooler 17 and cooled by the drainage A supplied from the pipe 22, and part of the water content in the gas is condensed and removed. The condensed / removed water is returned to the tank 3 from the conduit 19. The gas from which a part of the water has been removed is diluted with the air D supplied from the pipe 10 if necessary, and in some cases, preheated to a predetermined temperature by the preheater 11 and then introduced into the catalyst column 12. The stripped ammonia gas undergoes oxidative decomposition on the catalyst 13 to produce N ₂ and H ₂
It is decomposed into O and released from the pipe 14 to the atmosphere. The water concentration at the outlet of the catalyst tower is measured by the water concentration measuring device 20 installed at the outlet of the catalyst tower, and the distributor 2 is measured according to the measured value.
The flow rate of the wastewater A supplied from the pipe 22 through 1 is controlled. From the pipe 15 at the bottom of the stripping tower 7,
The wastewater E from which ammonia has been removed is discharged.

The catalyst used in Example 1 is the catalyst of claim 9.
The same effects as those of the components described in (1) can be expected and used.

[0039]

According to the invention described in claims 1 to 11, even if the catalyst is deteriorated, the NH ₃ concentration at the catalyst tower outlet can be reduced, and the catalyst performance can be maintained high. Can also be reduced.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an apparatus system of a method for purifying ammonia-containing wastewater according to the present invention.

FIG. 2 is a diagram showing experimental data of the present invention conducted using the apparatus of FIG.

FIG. 3 is an explanatory view showing an apparatus system of a method for purifying ammonia-containing wastewater showing another embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a conventional method for purifying ammonia-containing wastewater.

FIG. 5 is a schematic diagram illustrating the effect of the catalyst used in the present invention.

[Explanation of symbols]

1 ... Piping, 2 ... Piping, 3 ... Tank, 4 ... Pump, 5 ... Preheater, 6 ... Piping, 7 ... Stripping tower, 8 ... Packing,
9 ... Piping, 10 ... Piping, 11 ... Preheater, 12 ... Catalyst tower,
13 ... Catalyst, 14 ... Piping, 15 ... Piping, 16 ... Piping, 1
7 ... Gas cooler, 18 ... Piping, 19 ... Pipeline, 20 ... Moisture concentration measuring device, 21 ... Distributor, 22 ... Piping, A ... Drainage,
B ... alkali, C ... steam, D ... air, E ... drainage, F ... cooling water, G ... gas.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hidetomo Noda             20 Kitakanzan, Otakamachi, Midori-ku, Nagoya-shi, Aichi             No.1 Energy Development Division, Chubu Electric Power Co., Inc.             Rugie Applied Research Center (72) Inventor Yoshito Mori             20 Kitakanzan, Otakamachi, Midori-ku, Nagoya-shi, Aichi             No.1 Energy Development Division, Chubu Electric Power Co., Inc.             Rugie Applied Research Center (72) Inventor Masao Aoki             20 Kitakanzan, Otakamachi, Midori-ku, Nagoya-shi, Aichi             No.1 Energy Development Division, Chubu Electric Power Co., Inc.             Rugie Applied Research Center (72) Inventor Hirofumi Yoshikawa             Babcock Hitachi 3-36 Takaracho, Kure City, Hiroshima Prefecture             Kure Institute Co., Ltd. (72) Inventor Hiroshi Ishizaka             Babcock Hitachi 3-36 Takaracho, Kure City, Hiroshima Prefecture             Kure Institute Co., Ltd. (72) Inventor ▲ High ▼ Narihi Motomoto             Babcock Hitachi 3-36 Takaracho, Kure City, Hiroshima Prefecture             Kure Institute Co., Ltd. (72) Inventor Takanori Nakamoto             Babcock Hitachi 6-9 Takaracho, Kure City, Hiroshima Prefecture             Kure Office Co., Ltd. F-term (reference) 4D011 AA15 AB01 AB03 AC04                 4D037 AA11 AB12 BA23 BB05                 4D048 AA08 AB02 AB03 AB06 BA03X                       BA06X BA07X BA11Y BA23X                       BA26Y BA27X BA30X BA31Y                       BA33Y BA41X BB03 BB08                       CC32 CD10 DA01 DA03 DA20                 4D052 AA02 BA00 BA05

Claims (11)

[Claims] 1. Ammonia (NH₃) NH in contained wastewater
₃Detoxifying NH ₃Before purifying the contained wastewater,
Note NH₃NH by contacting the contained wastewater with carrier gas₃Including
From wastewater to NH₃And a step of moving the
NH generated in₃To remove some of the water in the gas containing
Step and NH from which a part of water is removed₃Containing moth
And the NH heated in the heating step.₃Including
When the gas is brought into contact with the catalyst, the NH₃Decomposes into nitrogen and water
NH including a step of₃Purification of contained wastewater
Method. 2. The NH ₃ -containing wastewater according to claim 1, wherein in the step of removing a part of the water content in the gas containing NH ₃ , the temperature of the gas is lowered to condense and remove the water content. Purification method. 3. The method for purifying NH ₃ -containing wastewater according to claim 1, wherein the water concentration after removing a part of the water in the generated gas containing NH ₃ is 25% or less. . Wherein said catalyst is the nitrogen oxide from the first component and NH ₃ having a reducing activity by NH ₃ nitrogen oxides (N
The method for purifying NH ₃ -containing wastewater according to claim 1 or 2, comprising a second component having an activity of generating Ox). 5. The first component of the catalyst is titanium (Ti).
And an oxide of one or more elements selected from tungsten (W), vanadium (V) and molybdenum (Mo), wherein the second component of the catalyst is platinum (Pt), iridium (Ir), rhodium. (Rh) and palladium (P
silica carrying one or more noble metals selected from d),
The method for purifying NH ₃ -containing wastewater according to claim 4, which is a catalyst containing one or more oxides selected from zeolite and alumina. 6. The method for purifying NH ₃ -containing wastewater according to claim 1, wherein the catalyst is zeolite. 7. An apparatus for purifying NH ₃ -containing wastewater, which detoxifies NH ₃ in ammonia (NH ₃ ) -containing wastewater, by contacting the NH ₃ -containing wastewater with a carrier gas.
Means for transferring NH ₃ from the H ₃ -containing wastewater into the gas phase,
Means for removing a portion of the moisture in the gas containing NH ₃ generated by said means, NH ₃ removed a portion of the water in said means
Means for heating the contained gas and N heated by the heating means
An apparatus for purifying NH ₃ -containing wastewater, comprising means for contacting a H ₃ -containing gas with a catalyst to decompose the NH ₃ into nitrogen and water. 8. The device for removing a part of water in a gas containing NH ₃ is a device for lowering the temperature of the gas and condensing and removing a part of it. NH ₃ -containing wastewater purification device. Wherein said catalyst is the nitrogen oxide from the first component and NH ₃ having a reducing activity by NH ₃ nitrogen oxides (N
The purification device for NH ₃ -containing wastewater according to claim 7 or 8, comprising a second component having an activity of generating Ox). 10. The first component of the catalyst is titanium (T
i) and an oxide of one or more elements selected from tungsten (W), vanadium (V) and molybdenum (Mo), and the second component of the catalyst is platinum (Pt), iridium (Ir) A catalyst containing one or more oxides selected from silica, zeolite and alumina supporting one or more noble metals selected from rhodium (Rh) and palladium (Pd). 9
The apparatus for purifying NH ₃ -containing wastewater according to 1. 11. The apparatus for purifying NH ₃ -containing wastewater according to claim 7, wherein the catalyst is zeolite.