JP7801944B2 - Selective reduction catalyst system and reducing agent spraying method - Google Patents

Description

The present invention relates to a selective reduction catalyst system and a reducing agent spray method.

Marine diesel engines, which use ammonia as part of their fuel, use liquefied ammonia (hereinafter referred to as "LNH3"). Ammonia is attracting attention as a fuel in order to realize a carbon-free society, and the number of ships carrying LNH3 as cargo is increasing.
On the other hand, marine diesel engines use selective catalytic reduction units to remove nitrogen oxides generated by the combustion of fuel oil and other raw materials. Urea water, which is generally considered to be highly safe, is widely used as a reducing agent.

Patent Document 1 discloses a method of using urea water as a reducing agent in a selective catalytic reduction catalyst connected to a marine diesel engine, and a selective catalytic reduction system that emphasizes safety and maintainability using this method.

JP 2011-144765 A

However, the technology disclosed in Patent Document 1 is a method that uses urea water as a reducing agent for a selective reduction catalyst from the perspective of corrosion resistance, etc., and does not allow for the effective use of LNH3 used in marine diesel engines that use ammonia as part of their fuel, or LNH3 carried as cargo, while also allowing for the reuse of existing urea water supply system equipment for such engines, etc.

The present invention aims to provide a selective catalytic reduction system and a reducing agent spray method that can effectively utilize LNH3 used in marine diesel engines that use ammonia as part of their fuel, or LNH3 carried as cargo, while also utilizing the existing urea water supply system equipment of such engines.

A first aspect of the present invention is
1. A selective catalytic reduction system connected to a diesel engine of a ship carrying liquefied ammonia as fuel or cargo, comprising:
A mixing unit and a spray unit are provided,
The mixing unit mixes the liquefied ammonia or the purge gas containing ammonia emitted from the diesel engine with the urea water stored in an existing tank of the ship,
The spraying section sprays a predetermined amount of the synthetic reducing agent produced by the mixing section.

A second aspect of the present invention is
1. A selective catalytic reduction system connected to a diesel engine of a ship carrying liquefied ammonia as fuel or cargo, comprising:
The apparatus includes a water generating unit, an agitating unit, a mixing unit, and a spraying unit,
The water generator generates fresh water from seawater,
The stirring unit stirs the fresh water and powdered urea,
the mixing unit mixes the liquefied ammonia or a purge gas containing ammonia emitted from the diesel engine with the urea water produced by the stirring,
The spraying section sprays a predetermined amount of the synthetic reducing agent produced by the mixing section.

A third aspect of the present invention is
An ammonia abatement device connected to a ship carrying liquefied ammonia as fuel or cargo,
a selective catalytic reduction system connected to a diesel engine of the ship, the selective catalytic reduction system including a urea solution storage tank;
Ammonia is absorbed by bubbling inert gas from the bottom of the urea water storage tank and diluted to a concentration that is not harmful to the human body.

A fourth aspect of the present invention is
1. A method of reducing agent spraying carried out by a selective reduction catalyst system connected to a diesel engine of a ship carrying liquefied ammonia as fuel or cargo, comprising:
It includes the following steps:
In the mixing step, the liquefied ammonia or the purge gas containing ammonia emitted from the diesel engine is mixed with the urea water stored in the existing tank of the ship,
In the spraying step, a predetermined amount of the synthetic reducing agent produced in the mixing step is sprayed.

A fifth aspect of the present invention is
1. A method of reducing agent spraying carried out by a selective reduction catalyst system connected to a diesel engine of a ship carrying liquefied ammonia as fuel or cargo, comprising:
It includes the following steps:
In the water production step, fresh water is produced from seawater,
In the stirring step, the fresh water and powdered urea or urea water are stirred,
In the mixing step, the urea water produced by the stirring is mixed with ammonia water produced by absorbing excess ammonia from a ship carrying the liquefied ammonia,
In the spraying step, a predetermined amount of the synthetic reducing agent produced in the mixing step is sprayed.

A sixth aspect of the present invention is
A method for detoxifying excess ammonia in a ship carrying liquefied ammonia as fuel or cargo, comprising:
a selective catalytic reduction system connected to a diesel engine of the ship, the selective catalytic reduction system including a urea solution storage tank;
This method involves absorbing ammonia from the bottom of the urea water storage tank by bubbling inert gas, and diluting it to a concentration that is not harmful to the human body.

The selective catalytic reduction system and reducing agent spray method of the present invention effectively utilize LNH3 used in marine diesel engines that use ammonia as part of their fuel, as well as LNH3 carried as cargo, while utilizing the existing urea water supply system equipment of such engines, thereby reducing the cost increase that would otherwise be incurred by installing a separate reducing agent supply system.

Overall view of the selective catalytic reduction system according to this embodiment Overall diagram of the selective catalytic reduction system when urea water is also produced Comparison of denitrification rates between urea water and synthetic reducing agents

Embodiments of the present invention will be described below using the drawings. The various features shown in the following embodiments can be combined with each other.

1. Configuration of the selective catalytic reduction system 1 In Section 1, the configuration of the selective catalytic reduction system of this embodiment will be described.

1.1 Selective catalytic reduction system 1
1 is an overall view of a selective reduction catalyst system 1, one aspect of the present embodiment, connected to a diesel engine of a ship carrying liquefied ammonia as fuel or cargo. The selective reduction catalyst system 1 includes a urea-water storage tank 2, a mixer 3, and a sprayer 6, and a flow rate adjuster 5 may be attached to the urea-water storage tank 2. The urea-water storage tank 2 is an existing tank that stores urea-water at a concentration used in the selective reduction catalyst unit 8, and is configured to spray a required amount of the synthetic reducing agent created by the mixer 3 into the selective reduction catalyst unit 8.

1.2 Urea water storage tank 2
The urea water storage tank 2 stores the reducing agent used in the selective catalytic reduction unit 8. While a diesel engine automobile uses 32.5% by weight of urea water, a ship uses 40.0% by weight of urea water. This is because the amount consumed as a reducing agent is overwhelmingly greater in ships, and so it is necessary to keep the concentration as high as possible in order to secure as much space as possible on board the ship.
As shown in FIGS. 1 and 2 , the urea water storage tank 2 has a mixing section 3 and an agitation section 4 , and is configured to supply the prepared synthetic reducing agent to a selective reduction catalyst unit 8 via a spray section 6 .

1.3 Mixing section 3
As shown in FIG. 1, the mixer 3 mixes the urea water stored in the urea water storage tank 2 with ammonia gas, ammonia water, and LNH 3 .
As shown in FIG. 2, the mixer 3 mixes the urea water obtained by stirring powdered urea into the fresh water stored in the urea water storage tank 2 with ammonia gas, ammonia water, and LNH 3 .

The ammonia gas is boil-off gas from a fuel tank or cargo tank, etc., and is mixed with the gas by bubbling with an inert gas. The ammonia water is ammonia water absorbed in fresh water separate from the fresh water stored in the urea water storage tank 2 in order to detoxify the excess ammonia. The LNH3 is extracted in liquid form directly from a fuel tank, cargo tank, etc.

Urea water is a solution of powdered urea, which is a solid, while ammonia water is a solution of ammonia gas, which is a gas. Therefore, although both urea water and ammonia water are hydrogen-bonded with water molecules, they can coexist. In other words, ammonia molecules can be mixed with urea water regardless of its concentration.
Furthermore, the solubility parameters of urea water and ammonia water are close to each other, so they are very easy to mix even though they are both liquids.

For this reason, the mixing unit 3 can be any device that has the function of rotating a rod, plate, or propeller-shaped stirrer in one direction at a constant speed within the tank, and does not require any special movement such as automatically inverting the container.

1.4 Stirring section 4
The agitation unit 4 is configured to prepare urea water by agitating the powdered urea introduced from above into the fresh water stored in the urea water storage tank 2. As described above, the powdered urea introduced is adjusted so that the concentration of the urea water becomes approximately 40 wt %.
Since powdered urea is easily dissolved in water, similar to the mixing unit described above, the stirring unit 4 can be any device that has the function of rotating a rod, plate, or propeller-shaped stirrer in one direction at a constant speed within the tank, and does not require any special movement such as automatically turning over the container.

Furthermore, the amount of powdered urea that dissolves increases as the solvent temperature rises. Therefore, as shown in Figure 2, when ammonia gas is bubbled from the bottom of the urea water storage tank 2, the temperature of the water that serves as the solvent rises due to the heat of reaction, making it easier for the urea to dissolve. In other words, in this case, the operating time of the agitator 4 is also shortened.

1.5 Flow rate adjustment section 5
As shown in Figures 1 and 2, the flow rate adjustment unit 5 is a flow rate adjustment valve for liquids such as LNH3 from a fuel tank or a cargo tank, and ammonia water absorbed in fresh water separate from the fresh water stored in the urea water storage tank 2 in order to remove excess ammonia.
In order to adjust the concentration of the synthetic reducing agent, it may be necessary to maintain a constant pressure in the urea water storage tank 2. In this case, a pressure regulating valve may be used instead of a flow rate regulating valve, which can be changed as needed depending on the usage situation.

1.6 Spray part 6
The spray unit 6 is configured to supply the synthetic reducing agent produced in the urea water storage tank 2 to the selective reduction catalyst unit 8. The spray unit 6 has a so-called shower head structure, and is often attached immediately before the selective reduction catalyst unit 8. As long as a predetermined concentration is maintained, the spray unit 6 may be one that sprays something that includes the synthetic reducing agent sampled by the analysis unit 9, which will be described in detail below. In this way, the synthetic reducing agent can be used without waste.

1.7 Water production department 7
As shown in Figure 2, the fresh water production unit 7 is a distillation unit or a membrane desalination unit (not shown) that pumps up seawater located particularly around the ship, distills it, and obtains fresh water. The fresh water is mainly used as cooling water for the main engine, power generation engine, and air compressor of the marine diesel engine, and is also used as boiler feed water, drinking water, and general service water. A portion of this fresh water is introduced into the urea water storage tank 2 and serves as a solvent for urea water and ammonia water.

As mentioned above, if an exothermic reaction occurs in the mixing section 3 and assistance in dissolving the powdered urea in the agitation section 4 is not required, the heat of reaction can of course be used to assist in the water production section 7.

1.8 Selective catalytic reduction unit 8
The selective reduction catalyst unit 8 is assumed to have a structure with a plurality of through-holes extending in one direction to form a gas flow path, a catalyst supported along the inner walls of the structure that define the through-holes, and vanadium, tungsten, or platinum as contained elements on the catalyst surface. Similarly, a selective reduction catalyst unit manufactured by extrusion molding with titanium oxide as its main component is also assumed. Exhaust gas containing nitrogen oxides from a marine diesel engine flows along the flow path, and ammonia water as a reducing agent is supplied from the spray unit 6 at a predetermined flow rate and concentration, thereby removing the nitrogen oxides.

1.9 Analysis Department 9
The analysis unit 9 is configured to measure the concentrations of the urea water and ammonia water, which are the synthetic reducing agents produced in the urea water storage tank 2. For this reason, the analysis unit 9 is assumed to be a concentration meter, but a density meter, which is easier to measure than a concentration meter, may also be used. In this case, it is necessary to obtain in advance the relationship between the density meter measurement value and the concentration. For example, in the case of ammonia water only, if the density meter optically measures 0.912, the ammonia water concentration is considered to be approximately 15% at room temperature and normal pressure.

When urea or ammonia is dissolved to the maximum extent as a synthetic reducing agent, the concentration of urea water is approximately 40% by weight, and the concentration of ammonia water is approximately 20% by weight. Therefore, when an analysis result exceeding a predetermined threshold is obtained, the analysis unit 9 is configured to send a signal to stop the operation of the mixer 3 and the agitator 4.
Similarly, the device may be configured to send a signal to activate the spray unit 6 when an analysis result exceeding a predetermined threshold is obtained.

2 First Embodiment Section 2 describes aspects of the first embodiment of the present invention.

Figure 1 is an overall view of a selective catalytic reduction system 1, showing one aspect of this embodiment. The LNH3 shown in Figure 1 is extracted in liquid form directly from a fuel tank, cargo tank, or the like, and the ammonia gas shown in Figure 1 is boil-off gas from a fuel tank or cargo tank, for example. Furthermore, the ammonia water shown in Figure 1 is ammonia water that has been absorbed into fresh water so that excess ammonia gas remaining in the marine engine piping can be detoxified.

In order to improve environmental friendliness, part of the LNH3 may of course be LNH3 obtained by recovering and separating wastewater from marine diesel engines that use ammonia as part of their fuel.

The urea water storage tank 2 stores urea water with a maximum concentration of approximately 40% by weight so that it can be supplied to the selective catalytic reduction unit 8 via the spray unit 6. The LNH3, ammonia gas, and ammonia water are introduced into the urea water storage tank 2 at a predetermined flow rate by the flow rate adjustment unit 5.

The mixing section 3 installed in the urea water storage tank 2 then mixes the ammonia component with the urea component to produce a synthetic reducing agent. The bubbling gas used to introduce the ammonia gas into the urea water storage tank 2 can of course be an inert gas such as nitrogen, but it can also be purge gas mixed with ammonia emitted from the engine. In this case, the rotation speed of the agitator in the mixing section 3 is even slower than that of ammonia water or LNH3.

As described above, the synthetic reducing agent is produced in the urea water storage tank 2, and the analysis unit 9 determines whether the urea water and ammonia water exceed a predetermined concentration. The analysis unit 9 may be a simple measurement device such as a light transmission density meter, or it may sample the synthetic reducing agent from the urea water storage tank 2 and measure the concentration through a chemical reaction.

Furthermore, since ammonia becomes weakly alkaline when dissolved in water, its concentration can also be determined using its hydrogen ion exponent. In this case, however, it is necessary to obtain in advance the relationship between the hydrogen ion exponent and the concentration.

We will now examine the effects of the synthetic reducing agents mentioned above, urea water and ammonia water. Urea is an amide of carbonic acid with two ammonia groups (NH2 groups). The mass of urea is 60 g/mol, while that of ammonia is 17 g/mol. Therefore, although ammonia is significantly lighter than air, many molecules are dissolved in water, and detailed calculations suggest that 40% urea water and 23% ammonia water have equivalent reducing capabilities.

Figure 3 shows the experimental results when 32.5% by weight urea water and a synthetic reducing agent (urea: ammonia: water = 32.5:10:57.5) made by dissolving ammonia in the urea water were sprayed into the simulated selective reduction catalyst unit 8 by the spray unit 6. It can be seen that the amount of spray required for denitration can be significantly reduced with the synthetic reducing agent.

By dissolving ammonia in the urea water until it reaches saturation, it is possible to reduce the amount sprayed by up to roughly half, leading to reduced running costs. It also enables the urea water storage tank 2 to be made smaller and lighter. Furthermore, the ammonia water produced by absorbing ammonia into the fresh water produced in the fresh water production unit 7 can be effectively used to neutralize any excess ammonia gas remaining in the piping, reducing the load on the ammonia detoxification device. Furthermore, by directly dissolving ammonia in the urea water, the load on the fresh water production unit 7 itself can also be reduced.

Whether or not ammonia is dissolved in the urea water to a saturated state at ambient temperature depends on the environment on board the ship outside the vicinity of the urea water storage tank 2. This is because ammonia diffusion can be prevented by dissolving only the amount of ammonia that will be saturated at the highest expected temperature on board the ship.

As shown in Figure 3, synthetic reducing agents have a lower freezing point than aqueous urea. In cold regions in particular, the aqueous urea may freeze and become unable to be pumped, posing a risk of damaging valves and piping, so temperature control of the aqueous urea storage tank 2 is necessary. However, this method is preferable because it allows the selective catalytic reduction system 1 to start up without such temperature control.

The synthetic reducing agent produced in this way is highly environmentally friendly, as it reduces carbon dioxide emissions while utilizing existing equipment such as pump modules in the urea water supply system. As described above, the urea water storage tank 2 can be set up in a smaller size, making better use of the space in the entire selective catalytic reduction system 1. The reducing agent is then sprayed into the selective catalytic reduction unit 8 via the spray section 6, where denitrification takes place.

Furthermore, by preparing a synthetic reducing agent made by mixing urea water and ammonia in advance and loading it into the urea water storage tank 2, the urea water storage tank 2 can be set up more compactly, allowing for more efficient use of space on the ship. It can also reduce the number of storage tanks for fresh water for the scrubber. In this case, however, temperature control within the urea water storage tank 2 is required. This is because, depending on the engine operating conditions, the ammonia and other substances in the synthetic reducing agent may exceed saturation and precipitate.

3 Second Embodiment A second embodiment of the present invention will be described in Section 3. Note that the description of functions and configurations that are substantially the same as those of the first embodiment will be omitted.

Figure 2 is an overall view of a selective catalytic reduction system 1 according to one embodiment of the present invention. A major difference from the first embodiment of the present invention is that what is stored in advance in the urea water storage tank 2 is not urea water, but fresh water produced by the water generator 7. Powdered urea is introduced from above into the fresh water stored in the urea water storage tank 2, and the water is stirred by the stirrer 4 to produce urea water. The concentration of the urea water is adjusted to approximately 40% by weight, and the stirrer 4 stops operating when the predetermined concentration is reached.

Note that the timing at which ammonia gas, ammonia water, or LNH3 is introduced into the urea water storage tank 2 via the flow rate adjustment unit 5 does not have to be after the stirring unit 4 has stopped moving. In particular, when ammonia gas is introduced, the heat of reaction causes the water temperature to rise. In this case, the amount of powdered urea dissolved in the clean water increases, which can shorten the stirring time in the stirring unit 4 and, ultimately, the mixing unit 3.

4. Third Embodiment A third embodiment of the present invention will be described in Section 4. Note that the description of functions and configurations that are substantially the same as those of the first and second embodiments will be omitted.

The generation of excess ammonia is unavoidable on ships carrying liquefied ammonia as fuel or cargo. However, because this ammonia has an effect on the human body, it cannot be released directly into the atmosphere and must be removed using abatement equipment.

As mentioned above, a typical example of a method for removing ammonia is a scrubber, and one known method is to absorb the ammonia by bubbling it into a solvent with an inert gas. Scrubbers are often used for marine diesel engines due to their low cost and ease of operation, but the installation space required for the solvent that absorbs the ammonia is an issue.

As shown in Figures 1 and 2, the urea water storage tank 2 installed in the selective catalytic reduction system 1 is used as a scrubber tank. In other words, by using urea water as a solvent to absorb ammonia, the urea water storage tank 2 functions as both part of the selective catalytic reduction system 1 and part of the abatement device. Not only can this make effective use of onboard space, but it can also be used effectively as a synthetic reducing agent, as in the first and second embodiments of the present invention described above.

In the second embodiment of the present invention, the mixing section 3 and the stirring section 4 may be operated substantially simultaneously. This is because, since the reaction heat between ammonia gas and water is particularly large, the operation time of the stirring section 4 can be shortened by increasing the solubility of powdered urea due to the reaction heat.

When ammonia gas, ammonia water, or LNH 3 is introduced into the urea water storage tank 2, it is preferable that the amount of ammonia is adjusted by the flow rate adjusting unit 5 so that the ammonia concentration does not exceed the saturation concentration of the ammonia in the composite reducing agent.
The amount of ammonia water generated varies greatly depending on whether it is used as fuel or cargo, and therefore, by adjusting the flow rate in accordance with the operating conditions of the ship, the selective reduction catalyst system 1 can be made efficient and highly environmentally friendly.

It is more preferable that the ammonia introduced into the urea water storage tank 2 is ammonia gas via the flow rate adjusting unit 5 and is bubbled with an inert gas.
As described above, not only can the solubility be increased by utilizing the heat of reaction, but if a heat exchanger or the like is attached to the lower part of the urea solution storage tank 2, the heat can also be used to assist in the production of fresh water in the fresh water production section 7, resulting in a more environmentally friendly system.

It is more preferable that an analysis section 9 be provided to determine whether a predetermined concentration has been reached before the synthetic reducing agent is sprayed into the selective reduction catalyst unit 8.
When reaction heat is generated by bubbling or the like, a temperature gradient may occur between the upper and lower parts of the urea water storage tank 2. In this case, the ammonia and urea are not completely dissolved in the fresh water, resulting in uneven concentrations, which is not suitable for effective use of the synthetic reducing agent.

While various embodiments have been described above, these are presented as examples and are not intended to limit the scope of the invention. These novel embodiments may be embodied in a variety of other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. These embodiments and their variations are within the scope and spirit of the invention, and are also within the scope of the invention and its equivalents as set forth in the claims.

1 Selective catalytic reduction system 2 Urea water storage tank 3 Mixing section 4 Stirring section 5 Flow rate adjusting section 6 Spray section 7 Water generating section 8 Selective catalytic reduction unit 9 Analysis section

Claims (16)

1. A selective catalytic reduction system connected to a diesel engine of a ship carrying liquefied ammonia as fuel or cargo, comprising:
A mixing unit and a spray unit are provided,
The mixing unit mixes the liquefied ammonia or the purge gas containing ammonia emitted from the diesel engine with the urea water stored in an existing tank of the ship,
The spraying unit sprays a predetermined amount of the synthetic reducing agent produced by the mixing unit. 1. A selective catalytic reduction system connected to a diesel engine of a ship carrying liquefied ammonia as fuel or cargo, comprising:
The apparatus includes a water generating unit, an agitating unit, a mixing unit, and a spraying unit,
The water generator generates fresh water from seawater,
The stirring unit stirs the fresh water and powdered urea,
the mixing unit mixes the liquefied ammonia or a purge gas containing ammonia emitted from the diesel engine with the urea water produced by the stirring,
The spraying unit sprays a predetermined amount of the synthetic reducing agent produced by the mixing unit. 3. The selective reduction catalyst system of claim 2,
The stirring in the stirring section and the mixing in the mixing section are carried out substantially simultaneously. The selective reduction catalyst system according to claims 1 to 3,
The system further includes a flow rate adjusting section, and the ammonia loaded on the ship is transported to the mixing section at a predetermined rate. 5. The selective reduction catalyst system of claim 4,
The ammonia on board the ship is supplied from the lower part of the mixing section by bubbling inert gas. The selective reduction catalyst system according to claims 1 to 3,
It also has an analysis section,
the analysis unit performs component analysis of the synthetic reducing agent generated by the mixing unit,
The spray unit sprays a predetermined amount determined by the value of the component analysis result. 5. The selective reduction catalyst system of claim 4,
It also has an analysis section,
the analysis unit performs component analysis of the synthetic reducing agent generated by the mixing unit,
The spray unit sprays a predetermined amount determined by the value of the component analysis result. 6. The selective reduction catalyst system of claim 5,
It also has an analysis section,
the analysis unit performs component analysis of the synthetic reducing agent generated by the mixing unit,
The spray unit sprays a predetermined amount determined by the value of the component analysis result. 1. A method of reducing agent spraying carried out by a selective reduction catalyst system connected to a diesel engine of a ship carrying liquefied ammonia as fuel or cargo, comprising:
It includes the following steps:
In the mixing step, the liquefied ammonia or the purge gas containing ammonia emitted from the diesel engine is mixed with the urea water stored in the existing tank of the ship,
In the spraying step, a predetermined amount of the synthetic reducing agent produced in the mixing step is sprayed. 1. A method of reducing agent spraying carried out by a selective reduction catalyst system connected to a diesel engine of a ship carrying liquefied ammonia as fuel or cargo, comprising:
It includes the following steps:
In the water production step, fresh water is produced from seawater,
In the stirring step, the fresh water and powdered urea or urea water are stirred,
In the mixing step, the urea water produced by the stirring is mixed with ammonia water produced by absorbing excess ammonia from a ship carrying the liquefied ammonia,
In the spraying step, a predetermined amount of the synthetic reducing agent produced in the mixing step is sprayed. 11. A method of spraying a reducing agent performed by the selective reduction catalyst system of claim 10, comprising:
The method, wherein the stirring step and the mixing step occur substantially simultaneously. A reducing agent spraying method performed by the selective reduction catalyst system according to any one of claims 9 to 11, further comprising a flow rate adjusting step, wherein the amount of ammonia loaded on the ship that is transported to the mixing step is a predetermined amount. 13. A method of spraying a reducing agent performed by the selective reduction catalyst system of claim 12, comprising:
A method wherein the mixing step is performed by bubbling an inert gas from below the ammonia on board the vessel. A reducing agent spraying method performed by the selective reduction catalyst system according to any one of claims 9 to 11, comprising:
It also has an analysis step,
the analyzing step performs a component analysis of the synthetic reducing agent produced by the mixing step,
A method in which the spraying step sprays a predetermined amount determined by the value of the component analysis result. 13. A method of spraying a reducing agent performed by the selective reduction catalyst system of claim 12, comprising:
It also has an analysis step,
the analyzing step performs a component analysis of the synthetic reducing agent produced by the mixing step,
A method in which the spraying step sprays a predetermined amount determined by the value of the component analysis result. 14. A method of spraying a reducing agent performed by the selective reduction catalyst system of claim 13, comprising:
It also has an analysis step,
the analyzing step performs a component analysis of the synthetic reducing agent produced by the mixing step,
A method in which the spraying step sprays a predetermined amount determined by the value of the component analysis result.