KR20170034691A - Apparatus for exhaust gas purification and exhaust gas purification method - Google Patents

Abstract

The present invention relates to a diesel engine, comprising: a first processing unit located at a front end of an exhaust gas discharge pipe connected to a diesel engine and injecting a mixed reducing agent into the exhaust gas; And a diesel particulate filter disposed at a rear end of the exhaust pipe and coated with a catalyst for selective catalytic reduction; And an exhaust gas purifying method using the same. Accordingly, it is an object of the present invention to provide an exhaust gas purifying apparatus and exhaust gas purifying apparatus which are excellent in the efficiency of removing nitrogen oxides and particulate matter in a wide temperature range, can remove soot while omitting the external heat source, A purification method can be provided.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an exhaust gas purifying apparatus and an exhaust gas purifying method,

The present invention relates to an exhaust gas purification apparatus and an exhaust gas purification method.

Diesel power generation is a method of generating electricity using energy generated by a diesel engine. A diesel engine is a type of internal combustion engine that compresses air in a cylinder to a state of high temperature and high pressure and then changes the thermal expansion energy generated by injecting the liquid fuel into mechanical motion. Since this process is carried out by combustion reaction at high temperature and high pressure, the diesel engine generates harmful substances such as nitrogen oxides (NOx) and particulate matter (PM).

Nitrogen oxides contain nitrogen monoxide, nitrogen dioxide, and other nitrogen oxides. When they react with moisture in the atmosphere, they become a major cause of acid rain. If they become cloud particles in the form of nitric acid, they can be a factor to destroy the ozone layer. In addition, nitrogen oxides themselves act on the human body and cause respiratory diseases such as emphysema and bronchitis.

In order to treat such nitrogen oxides, an exhaust gas using an SCCR system using a selective catalytic reduction (SCR) catalyst or an SNCR system using a reducing agent for selective non-catalytic reduction (SNCR) A gas purifier is used. The exhaust gas purifying apparatus of the SNCR system or the SCR system is installed in a discharge pipe connected to the diesel engine to reduce nitrogen oxides in the exhaust gas.

The SNCR system is characterized in that the treatment efficiency varies depending on the kind of the reducing agent. Ammonia and urea are mainly used as the reducing agent, and ammonia is generally higher in efficiency than the element, but elements that are easy to store and manage are used. However, the conventional SNCR system has a low denitrification efficiency, which causes excessive addition of a reducing agent. In this case, the amount of the reducing agent is high, which causes the operating cost to increase, and due to the excessive reducing agent, a large amount of ammonia damages the boiler tube and generates ammonium sulfate in the air preheater, which may cause thermal element corrosion and clogging frequently.

The SCR system is excellent in nitrogen oxide reduction efficiency by using a catalyst specific to nitrogen oxides, but it is difficult to maintain the exhaust gas temperature at an appropriate level. For example, when operating at a temperature lower than the catalytic activation temperature, ammonia and sulfur oxides (SOx) in the exhaust gas may form ammonium sulfate to poison the catalyst or cause clogging of the catalyst or air preheater, The nitrogen oxide removal activity during operation may be reduced and the hydrothermal stability may be lowered.

It is an object of the present invention to provide an exhaust gas purifying apparatus which is excellent in the removal efficiency of nitrogen oxides and particulate matter, has a wide active temperature range, can remove soot while omitting an external heat source, And a method for purifying exhaust gas.

In one embodiment of the present invention, there is provided a diesel engine comprising: a first processing unit located at a front end of an exhaust gas discharge pipe connected to a diesel engine, for reducing the amount of mixed reducing agent sprayed to the exhaust gas; And a diesel particulate filter disposed at a rear end of the discharge pipe and coated with a catalyst for selective catalytic reduction; And the exhaust gas purifying apparatus.

The mixed reducing agent may include 70 wt% to 85 wt% of urea solution, 10 wt% to 20 wt% of alcohol, 2.5 wt% to 5 wt% of polyethylene glycol, and 2.5 wt% to 5 wt% of alkylbenzenesulfonic acid.

The front end of the exhaust pipe may be a high temperature region where the temperature of the exhaust gas is 600 ° C. to 850 ° C. and a molar ratio of the nitrogen oxide: urea in the high temperature region may be 1: 1 to 1: 1.2.

The rear end of the exhaust pipe may be a middle / low temperature region where the temperature of the exhaust gas is 200 to 550 DEG C, and a molar ratio of the nitrogen oxide / urea in the middle / low temperature region may be 1: 0.7 to 1: 0.9.

The substrate of the diesel particulate filter may comprise at least one of cordierite, silicon carbide, acicular mullite, aluminum titanate and alloy foam. And has an average pore size of 10 탆 to 30 탆, and may have a honeycomb structure.

The catalyst for selective catalytic reduction may be one obtained by ion-exchanging copper (Cu) or iron (Fe) on the surface of a support, and the support may include at least one of mordenite, beta-zeolite and ZSM-5.

The selective catalytic reduction catalyst may include 15 to 35% by weight of copper (Cu) or iron (Fe).

The exhaust gas purifying apparatus may further include a regenerating device installed in the diesel engine for directly injecting fuel into the diesel engine to instantaneously combust the exhaust gas to instantaneously raise the temperature of the exhaust gas to regenerate the diesel particulate filter .

According to another embodiment of the present invention, there is provided a method for reducing nitrogen oxides in a diesel engine, the method comprising: a first processing step of reducing a nitrogen oxide by injecting a mixed reducing agent into the exhaust gas at a front end of an exhaust gas discharge pipe connected to a diesel engine; And a second treatment step of, at a rear end of the discharge pipe, reducing nitrogen oxides and particulate matter using a diesel particulate filter coated with a catalyst for selective catalytic reduction; To a method for purifying exhaust gas.

The exhaust gas purifying method is characterized in that the mixed reducing agent comprises 70 to 85% by weight of urea solution, 10 to 20% by weight of alcohol, 2.5 to 5% by weight of polyethylene glycol and 2.5 to 5% by weight of alkylbenzenesulfonic acid, As shown in FIG.

The first treatment step may comprise controlling the molar ratio of nitrogen oxide: urea from 1: 1 to 1: 1.2 in a high temperature region where the temperature of the exhaust gas is 600 캜 to 850 캜.

The second treatment step may comprise controlling the molar ratio of nitrogen oxide: urea to 1: 0.7 to 1: 0.9 in a medium to low temperature range where the temperature of the exhaust gas is 200 ° C to 550 ° C.

The base material of the diesel particulate filter in the exhaust gas purification method is cordierite, silicon carbide, acicular mullite, aluminum titanate, and alloy foam ), An average pore size of 10 to 30 mu m, and a honeycomb structure.

In the exhaust gas purifying method, the catalyst for selective catalytic reduction is one in which copper (Cu) or iron (Fe) is ion-exchanged on the surface of the support, and the support contains at least one of mordenite, beta-zeolite and ZSM- .

In the exhaust gas purifying method, the selective catalytic reduction catalyst may include 15 to 35% by weight of copper (Cu) or iron (Fe).

The exhaust gas purifying method may further include a third processing step of instantly combusting the liquid fuel directly injected into the diesel engine, thereby instantaneously raising the temperature of the exhaust gas to regenerate the diesel particulate filter.

The third process may be to instantaneously raise the temperature of the exhaust gas at the rear end of the exhaust pipe to 600 ° C to 650 ° C through instantaneous combustion to burn the soot of the diesel particulate filter.

The present invention provides an exhaust gas purifying apparatus which is excellent in the removal efficiency of nitrogen oxides and particulate matter in a wide temperature range, has a wide activation temperature range, can remove soot while omitting an external heat source, A device and an exhaust gas purifying method.

1 is a view showing an exhaust gas purifying apparatus of an embodiment of the present invention.

In an embodiment of the present invention, a first processing unit is disposed at a front end of an exhaust gas discharge pipe connected to a diesel engine, and injects a mixed reducing agent into the exhaust gas. And a second processing unit located at a rear end of the discharge pipe and using a diesel particulate filter coated with a catalyst for selective catalytic reduction; And the exhaust gas purifying apparatus.

The exhaust gas purifying apparatus of this embodiment is excellent in the removal efficiency of nitrogen oxides and particulate matter, has a wide temperature range excellent in the removal activity of nitrogen oxides and particulate matter, can remove soot while omitting the external heat source, It is simple, at the same time, has excellent purification efficiency and economical efficiency.

Hereinafter, the present invention will be described more specifically with reference to Fig. 1 showing an exhaust gas purifying apparatus of an embodiment of the present invention.

The exhaust gas purifying apparatus of one embodiment is connected to the diesel engine 100 and installed in a discharge pipe 200 for discharging exhaust gas generated from the diesel engine 100 to remove nitrogen oxides and particulate matter. In the diesel engine 100, external air is introduced and burned together with the fuel, and exhaust gas containing nitrogen oxide and particulate matter generated by the combustion is discharged through the discharge pipe 200. The exhaust gas passes through the exhaust pipe 200 and is passed through the exhaust gas purifying apparatus of the embodiment including the first processing unit 21 and the second processing unit 22 to exhaust the nitrogen oxide and particulate matter in a reduced state do.

Specifically, the exhaust pipe 200 is disposed at a front end of an exhaust pipe connected to the diesel engine, and includes a first processing unit 21 for reducing nitrogen oxides by injecting a mixed reducing agent into the exhaust gas; And a second processing unit (22) located at the rear end of the discharge pipe, for reducing nitrogen oxide and particulate matter using a diesel particulate filter coated with a catalyst for selective catalytic reduction.

The first processing unit 21 chemically reduces the nitrogen oxides by injecting the mixed reducing agent directly into the exhaust gas, and at the same time, catches some scattered particles.

The mixed reducing agent may include 70 wt% to 85 wt% of urea solution, 10 wt% to 20 wt% of alcohol, 2.5 wt% to 5 wt% of polyethylene glycol, and 2.5 wt% to 5 wt% of alkylbenzenesulfonic acid. In this case, the nitrogen oxide reduction effect can be more excellent at the exhaust gas temperature of the first treatment section. In addition, since the mixed reducing agent can easily be stored and handled, it is possible to reduce the consumption amount of the reducing agent due to the high efficiency of reducing nitrogen oxides, so that damage to the apparatus due to excessive reducing agent can be prevented.

In one embodiment, the mixed reducing agent comprises 80% to 85% by weight of urea solution, 10% to 15% by weight of alcohol, 2.5% to 5% by weight of polyethylene glycol and 2.5% to 5% by weight of alkylbenzenesulfonic acid . In this case, the nitrogen oxide in the initial exhaust gas can be reduced by 70 wt% or more, and the nitrogen oxide reduction efficiency is excellent.

The front end of the exhaust pipe 200 may be a high-temperature region where the temperature of the exhaust gas is 600 ° C to 850 ° C. In such a case, the mixed reducing agent may be more efficient in reducing the exhaust gas in the first treatment section. Further, when the mixed reducing agent of the above-described combination is used, nitrogen oxide can be removed with a high efficiency at a wider high temperature region (600 ° C to 850 ° C).

In one embodiment, the front end of the exhaust pipe 200 may have a temperature of exhaust gas of 700 ° C to 800 ° C. Within the above range, when the above-mentioned mixed reducing agent is used, the nitrogen oxide reduction effect in the first treatment section can be further improved.

The molar ratio of nitrogen oxide: urea in the high temperature region may be from 1: 1 to 1: 1.2. In this case, the nitrogen oxide in the initial exhaust gas can be reduced to an excellent efficiency of not less than 70 wt%, and the molar ratio of nitrogen oxide to urea at the rear end of the discharge pipe can be reduced to 1: 0.9 or less. This makes it possible to further improve the nitrogen oxide reduction effect in the second treatment unit described later and extend the service life of the entire exhaust gas purification apparatus and the diesel particulate filter of the second treatment unit.

The second processing unit 22 removes nitrogen oxides by selective catalytic reduction using a diesel particulate filter coated with a catalyst for selective catalytic reduction, and removes particulate matter by filtration. As a result, the nitrogen oxide reduction effect can be improved to 90% or more and the particulate fine particles can be removed.

The rear end 200 of the discharge pipe may be a middle or low temperature region where the temperature of the exhaust gas is 200 ° C to 550 ° C. Within the above range, the nitrogen oxide reduction effect by the second treatment section including the catalyst for selective catalytic reduction can be further improved.

The molar ratio of nitrogen oxide: urea in the middle low temperature region may be 1: 0.7 to 1: 0.9. In this case, the nitrogen oxide reduction effect in the second treatment section described later can be further improved, and the service life of the diesel particulate filter of the entire exhaust gas purification apparatus and the second treatment section can be prolonged.

The diesel particulate filter coated with the catalyst for selective catalytic reduction is characterized in that chemical removal of nitrogen oxides is carried out using a catalyst for selective catalytic reduction and at the same time physical removal of particulate matter and soot is performed using a particulate filter .

Base of the diesel particulate filter is cordierite (cordierite, Cd, 2MgO · 2Al 2 O 3 · 5SiO 2), silicon carbide (silicon carbide, SiC), aessi particulate reomeol light _{(acicular mullite, ACM, Al 2} SiO ₅ ), aluminum titanate (AT, Al ₂ TiO ₅ ), and alloy foam. In this case, the diesel particulate filter not only has an excellent effect of removing particulate matter, but also has excellent hydrothermal stability. In addition, excellent heat resistance at instantaneous high temperature is realized, and it is not damaged by the method of instantaneously increasing the temperature of the exhaust gas as described later, and it is possible to regenerate.

The substrate of the diesel particulate filter may have a honeycomb structure with an average pore size of 10 mu m to 30 mu m. In this case, not only is the effect of removing particulate matter better, but also the area of contact between the catalyst for selective catalytic reduction and the exhaust gas is increased to further improve the purification efficiency. Also, in the case where the average pore size is within the above-mentioned range, even when the catalyst for selective catalytic reduction is coated on the surface of the substrate, no pressure drop occurs in the exhaust gas purifying device, and the exhaust efficiency can be further improved.

The catalyst for selective catalytic reduction may be one obtained by ion-exchanging copper (Cu) or iron (Fe) on the surface of a support, and the support may include at least one of mordenite, beta-zeolite and ZSM-5. Within the above range, not only the hydrothermal stability of the catalyst is excellent, but also the removal efficiency against nitrogen oxides can be further improved. In particular, excellent catalytic activity can be maintained even when the diesel particulate filter is regenerated by a method of realizing excellent heat resistance at an instantaneous high temperature and instantaneously increasing the temperature of the exhaust gas as described later.

The selective catalytic reduction catalyst may include 15 to 35% by weight of copper (Cu) or iron (Fe). The removal efficiency for nitrogen oxides can be further improved within the above range. For example, the catalyst for selective catalytic reduction may include 15 wt% to 35 wt%, 20 wt% to 35 wt%, 20 wt% to 30 wt% eh of copper (Cu) or iron (Fe) 35% by weight. In the above range, the removal efficiency for nitrogen oxides can be further improved, and the rate of occurrence of the pressure drop can be lowered, so that the exhaust efficiency can be further improved.

In one embodiment, the catalyst for selective catalytic reduction can be obtained by, for example, introducing the carrier described above into an ion exchange solution containing copper (Cu) or iron (Fe) Lt; / RTI > may be prepared by stirring at a temperature. The catalyst for selective catalytic reduction having completed the ion exchange may be cleaned with deionized water using a vacuum filter and coated on the base material of the diesel particulate filter. The base material of the diesel particulate filter coated with the catalyst for selective catalytic reduction as described above is dried in a drier at a temperature of 110 ° C to 120 ° C for 20 to 24 hours and then calcined at about 400 ° C to about 600 ° C .

Although not shown in the drawing, the exhaust gas purifying apparatus is installed in a diesel engine and directly injects fuel to the diesel engine to instantaneously burn the gas, thereby instantaneously raising the temperature of the exhaust gas to regenerate the diesel particulate filter As shown in FIG. Such a regenerating apparatus can inject fuel directly to a cylinder after a power stroke by using a fuel injection device of a diesel engine. In this case, the temperature of the exhaust gas of the second processing section can be instantaneously increased to 600 to 650 占 폚. This allows the diesel particulate filter to be easily regenerated by burning the soot deposited in the diesel particulate filter. Such an exhaust gas purifying apparatus can omit an external heat source device such as a burner used for burning and regenerating a conventional diesel particulate filter, so that it is economical in view of facilities, And combustion particles can be prevented in advance, thereby being more excellent in efficiency.

The exhaust gas purifying apparatus includes a second processing unit using a diesel particulate filter coated with a catalyst for selective catalytic reduction, and a regenerating unit for regenerating the filter by directly injecting fuel into the diesel engine. There is an advantage that the DOC device installed at the front end of the diesel particulate filter can be omitted. In this case, the rate of occurrence of the pressure drop in the exhaust gas purifier can be further reduced to improve the exhaust efficiency, and the efficiency can be improved while simplifying the facility.

The exhaust gas purifying apparatus may further include: a first processing unit and a second processing unit; Alternatively, it is possible to remove at least 70% by weight of nitrogen oxide from the front end of the discharge pipe through the combined action of the first treatment section, the second treatment section and the third treatment section, and finally reduce the nitrogen oxide by 90% 90% by weight or more or 100% of the particulate matter can be removed.

According to another embodiment of the present invention, there is provided a method for reducing nitrogen oxides in a diesel engine, the method comprising: a first processing step of reducing a nitrogen oxide by injecting a mixed reducing agent into the exhaust gas at a front end of an exhaust gas discharge pipe connected to a diesel engine; And a second treatment step of, at a rear end of the discharge pipe, reducing nitrogen oxides and particulate matter using a diesel particulate filter coated with a catalyst for selective catalytic reduction; To a method for purifying exhaust gas.

Such an exhaust gas purifying method can be performed through the exhaust gas purifying apparatus of one embodiment described above.

The first processing step may be performed in the first processing unit 21 described above. In the first treatment step, the mixed reducing agent is directly injected into the exhaust gas passing through the first treatment section to chemically reduce the nitrogen oxides and capture some scattered particles.

The first treatment step of the exhaust gas purifying method is characterized in that the mixed reducing agent comprises 70 to 85% by weight of urea solution, 10 to 20% by weight of alcohol, 2.5 to 5% by weight of polyethylene glycol and 2.5 by weight of alkylbenzenesulfonic acid % To 5% by weight of the composition. In this case, the nitrogen oxide reduction effect can be more excellent at the exhaust gas temperature of the first treatment section. In addition, since the mixed reducing agent can easily be stored and handled, it is possible to reduce the consumption amount of the reducing agent due to the high efficiency of reducing nitrogen oxides, so that damage to the apparatus due to excessive reducing agent can be prevented.

In one embodiment, the first treatment step comprises the steps of: 80% to 85% by weight of the urea solution, 10% to 15% by weight of alcohol, 2.5% to 5% by weight of polyethylene glycol and 2.5% % Of a mixed reducing agent prepared by mixing. In this case, the nitrogen oxide in the initial exhaust gas can be reduced by 70 wt% or more, and the nitrogen oxide reduction efficiency is excellent.

The first treatment step may comprise controlling the molar ratio of nitrogen oxide: urea from 1: 1 to 1: 1.2 in a high temperature region where the temperature of the exhaust gas is 600 캜 to 850 캜. In this case, the nitrogen oxide in the initial exhaust gas can be reduced to an excellent efficiency of not less than 70 wt%, and the molar ratio of nitrogen oxide to urea at the rear end of the discharge pipe can be reduced to 1: 0.9 or less. This makes it possible to further improve the nitrogen oxide reduction effect in the second treatment unit described later and extend the service life of the entire exhaust gas purification apparatus and the diesel particulate filter of the second treatment unit.

The second processing step may be performed in the second processing unit 22 described above. In the second treatment step, the NOx is removed by selective catalytic reduction using a diesel particulate filter coated with a catalyst for selective catalytic reduction, and the particulate matter is removed by filtration. As a result, the nitrogen oxide reduction effect can be improved to 90% or more and the particulate fine particles can be removed.

The second treatment step may comprise controlling the molar ratio of nitrogen oxide: urea to 1: 0.7 to 1: 0.9 in a medium to low temperature range where the temperature of the exhaust gas is 200 ° C to 550 ° C. In this case, the nitrogen oxide reduction effect in the second treatment section described later can be further improved, and the service life of the diesel particulate filter of the entire exhaust gas purification apparatus and the second treatment section can be prolonged.

The base material of the diesel particulate filter in the exhaust gas purification method is cordierite, silicon carbide, acicular mullite, aluminum titanate, and alloy foam ), An average pore size of 10 to 30 mu m, and a honeycomb structure. In this case, the diesel particulate filter not only has an excellent effect of removing particulate matter, but also has excellent hydrothermal stability. In addition, excellent heat resistance at instantaneous high temperature is realized, and it is not damaged by the method of instantaneously increasing the temperature of the exhaust gas as described later, and it is possible to regenerate.

In the exhaust gas purifying method, the catalyst for selective catalytic reduction is one in which copper (Cu) or iron (Fe) is ion-exchanged on the surface of the support, and the support contains at least one of mordenite, beta-zeolite and ZSM- . In this case, not only the hydrothermal stability of the catalyst is excellent, but also the removal efficiency against nitrogen oxides can be further improved. In particular, excellent catalytic activity can be maintained even when the diesel particulate filter is regenerated by a method of realizing excellent heat resistance at an instantaneous high temperature and instantaneously increasing the temperature of the exhaust gas as described later.

In the exhaust gas purifying method, the selective catalytic reduction catalyst may include 15 to 35% by weight of copper (Cu) or iron (Fe). The removal efficiency for nitrogen oxides can be further improved within the above range. For example, the catalyst for selective catalytic reduction may comprise 15 wt% to 35 wt%, 20 wt% to 35 wt%, 20 wt% to 30 wt%, or 25 wt% to 35 wt% of copper (Cu) By weight. In the above range, the removal efficiency for nitrogen oxides can be further improved, and the rate of occurrence of the pressure drop can be lowered, so that the exhaust efficiency can be further improved.

The exhaust gas purifying method may further include a third processing step of instantly combusting the liquid fuel directly injected into the diesel engine, thereby instantaneously raising the temperature of the exhaust gas to regenerate the diesel particulate filter.

The third process may be to instantaneously raise the temperature of the exhaust gas at the rear end of the exhaust pipe to 600 ° C to 650 ° C through instantaneous combustion to burn the soot of the diesel particulate filter.

This third processing step can be performed through a regenerating device installed in the diesel engine, and the regenerating device can directly inject the fuel into the cylinder after the power stroke using the fuel injecting device. In this case, the temperature of the exhaust gas of the second processing section can be instantaneously increased to 600 to 650 占 폚. This allows the diesel particulate filter to be easily regenerated by burning the soot deposited in the diesel particulate filter. Such a method can omit an external heat source device such as a burner used for burning and regenerating a conventional diesel particulate filter, which is not only economical in terms of facility but also contributes to reduction of nitrogen oxides and combustion particles So that the efficiency can be further improved.

The exhaust gas purifying method includes a second process of using a diesel particulate filter coated with a catalyst for selective catalytic reduction and a third process of regenerating the filter by directly injecting fuel into the diesel engine , There is an advantage that the DOC device installed at the front end of the conventional diesel particulate filter can be omitted. In this case, the rate of occurrence of the pressure drop in the exhaust gas purifier can be further reduced to improve the exhaust efficiency, and the efficiency can be improved while simplifying the facility.

The exhaust gas purifying method may further include: a first processing step and a second processing step; Alternatively, it is possible to remove at least 70% by weight of nitrogen oxide from the front end of the discharge tube through the combined action of the first treatment step, the second treatment step and the third treatment step, and ultimately reduce the nitrogen oxide by 90% And at the same time, 90 wt% or more or 100% of the particulate matter can be removed.

Example

Hereinafter, the present invention will be described in detail with reference to examples and comparative examples. It should be understood, however, that these examples are provided for illustration only and are not intended to limit the scope of the present invention.

Manufacturing example  1 to 5: Preparation of mixed reducing agent

A mixed reducing agent was prepared by mixing urea, alcohol, polyethylene glycol and alkylbenzenesulfonic acid according to the composition ratios shown in Table 1 below. (At this time, the element was 30% concentrated)

Manufacturing example Element
(weight%) Alcohol
(weight%) Polyethylene glycol
(weight%) Alkylbenzenesulfonic acid
(weight%) Production Example 1 70 20 5 5 Production Example 2 75 20 2.5 2.5 Production Example 3 80 15 2.5 2.5 Production Example 4 85 10 2.5 2.5 Production Example 5 100 0 0 0

Example  1 to 4

In order to prepare a catalyst for selective catalytic reduction, ZSM-5 was added to Cu (NO ₃ ) ₂ and then ion-exchanged with stirring at a temperature of room temperature or higher. The ion-exchanged catalyst was washed with deionized water in a vacuum filtration apparatus equipped with a filter, and coated on Cordierite DPF. Then, the Cordierite DPF coated with the catalyst was placed in a drier and dried at a temperature of 110 to 120 DEG C for 24 hours. The dried sample was calcined at about 500 ° C. for several hours to prepare a diesel particulate filter coated with a catalyst for selective catalytic reduction. At this time, the amount of copper supported on the catalyst was controlled by the amount of support shown in Table 2 below.

A diesel particulate filter and a control unit coated with a catalyst for selective catalytic reduction prepared in the above-described manner, and an exhaust gas purifier were provided to the diesel generator operated in the island area.

(Nitrogen oxide: 1000 ppm, PM: 5 mg / m ³ , oxygen: 13.0%, moisture: 11%) at a reaction temperature of 600 ° C to 850 ° C and about 4,000 Nm ³ / %, Carbon monoxide 100 ppm or the like) was injected into the reaction tube and the mixed reducing agent of Production Examples 1 to 4 was sprayed at the front end portion of the discharge tube as shown in Table 2 to carry out the first step treatment. Thereafter, the exhaust gas (500 ° C) subjected to the first step is passed through the rear end of a discharge pipe equipped with a diesel particulate filter coated with a catalyst for selective catalytic reduction, and subjected to an operation test for about 1,000 hours Respectively.

Whether to use a diesel particulate filter coated with catalyst for selective catalytic reduction Mixed reducing agent Cu
(weight%) Example 1 ○ Production Example 1 15 Example 2 ○ Production Example 2 20 Example 3 ○ Production Example 3 25 Example 4 ○ Production Example 4 30

Comparative Example  One

The diesel generator in operation in the island area was equipped with a common diesel particulate filter and a control system that was not coated with a single reducing agent injection system and a catalyst for selective catalytic reduction, and equipped with an exhaust gas purifier.

(Nitrogen oxide: 1000 ppm, PM: 5 mg / m ³ , oxygen: 13.0%, moisture: 11%) at a reaction temperature of 600 ° C to 850 ° C and about 4,000 Nm ³ / %, Carbon monoxide 100ppm, etc.) was injected and the mixed reducing agent of Production Example 5 was sprayed as shown in Table 3 and treated in the first step. The exhaust gas treated at the first stage (500 ° C) was passed through a rear end of a discharge pipe equipped with a selective catalytic reduction apparatus and a diesel particulate filter, and the apparatus was operated for about 1,000 hours.

Whether to use a diesel particulate filter coated with catalyst for selective catalytic reduction Mixed reducing agent Cu
(weight%) Comparative Example 1 × Production Example 5 15

<Evaluation of initial nitrogen oxide removal rate>

The nitrogen oxide removal rates of the mixed reducing agents used in Examples 1 to 4 and Comparative Example 1 were evaluated and shown in Table 4.

In the exhaust gas purifying apparatus equipped with the reducing agent injecting apparatus, the mixed reducing agent used in Examples 1 to 4 and Comparative Example 1 was sprayed while adjusting the reaction temperatures to 500 ° C, 600 ° C, 700 ° C and 800 ° C. At this time, the exhaust gas had a nitrogen oxide: urea molar ratio of 1: 2.4 at a reaction temperature of about 4,000 Nm ³ / h at 600 캜 to 850 캜 (nitrogen oxide 1000 ppm, PM 5 mg / m ³ , oxygen 13.0%, moisture 11%, carbon monoxide 100 ppm Etc).

The concentration of the nitrogen oxide was measured using a non-dispersive infrared meter.

Nitrogen oxide removal rate (%) Mixed reducing agent 500 ℃ 600 ℃ 700 ℃ 800 ° C Example 1 Production Example 1 40 55 75 80 Example 2 Production Example 2 55 68 77 79 Example 3 Production Example 3 55 68 78 80 Example 4 Production Example 4 40 65 75 85 Comparative Example 1 Production Example 5 20 30 40 47

&Lt; Evaluation of final nitrogen oxide removal rate and particulate matter removal rate &

The nitrogen oxide concentration and the particulate matter concentration of the discharged exhaust gas were finally measured for the exhaust gas purifying method in Examples 1 to 4 and Comparative Example 1 to evaluate the nitrogen oxide removal rate and the particulate matter removal rate. The results are shown in Table 5.

Example reducing agent Whether to use a diesel particulate filter coated with catalyst for selective catalytic reduction Nitrogen oxide
Removal rate (%) Particulate fine particles
Removal rate (%) Example 1 Production Example 1 ○ 90 100 Example 2 Production Example 2 ○ 93 100 Example 3 Production Example 3 ○ 97 100 Example 4 Production Example 4 ○ 97 100 Comparative Example 1 Production Example 5 × 80 80

100: Diesel engine
200: discharge pipe
21: First processing section
22:

Claims (17)

A first processing unit located at a front end of an exhaust gas discharge pipe connected to the diesel engine and injecting a mixed reducing agent into the exhaust gas; And
A second processing unit located at a rear end of the discharge pipe and having a diesel particulate filter coated with a catalyst for selective catalytic reduction; And an exhaust gas purifying device for purifying exhaust gas.
The method according to claim 1,
Wherein the mixed reducing agent is an exhaust gas purifying agent comprising 70% by weight to 85% by weight of an urea solution, 10% by weight to 20% by weight of alcohol, 2.5% by weight to 5% by weight of polyethylene glycol and 2.5% Device.
The method according to claim 1,
Wherein the front end of the exhaust pipe is a high-temperature region where the temperature of the exhaust gas is 600 ° C to 850 ° C, and the molar ratio of nitrogen oxide: urea in the high-temperature region is 1: 1 to 1: 1.2.
The method according to claim 1,
And the rear end of the exhaust pipe is a middle / low temperature region where the temperature of the exhaust gas is 200 ° C to 550 ° C, and a molar ratio of the nitrogen oxide / urea in the middle / low temperature region is 1: 0.7 to 1: 0.9.
The method according to claim 1,
The substrate of the diesel particulate filter may comprise at least one of cordierite, silicon carbide, acicular mullite, aluminum titanate and alloy foam. Lt; / RTI &gt;
And an average pore size of 10 占 퐉 to 30 占 퐉, and has a honeycomb structure.
The method according to claim 1,
The selective catalytic reduction catalyst may be one wherein copper (Cu) or iron (Fe) is ion-exchanged on the surface of the support,
Wherein the carrier comprises at least one of mordenite, beta-zeolite and ZSM-5.
The method according to claim 6,
Wherein the catalyst for selective catalytic reduction comprises copper (Cu) or iron (Fe) in an amount of 15 wt% to 35 wt%.
The method according to claim 1,
The exhaust gas purifying apparatus further includes a regenerating device installed in the diesel engine for directly injecting fuel into the diesel engine for instantaneous combustion to thereby instantaneously raise the temperature of the exhaust gas to regenerate the diesel particulate filter Exhaust gas purifier.
A first treatment step of spraying a mixed reducing agent to the exhaust gas at a front end of an exhaust gas discharge pipe connected to the diesel engine to reduce nitrogen oxides; And
A second treatment step of, at a rear end of the discharge pipe, reducing nitrogen oxides and particulate matter using a diesel particulate filter coated with a catalyst for selective catalytic reduction; And exhausting the exhaust gas.
10. The method of claim 9,
Wherein the mixed reducing agent is a mixture of 70 wt% to 85 wt% urea solution, 10 wt% to 20 wt% alcohol, 2.5 wt% to 5 wt% polyethylene glycol, and 2.5 wt% to 5 wt% alkylbenzenesulfonic acid Way.
10. The method of claim 9,
Wherein the first treatment step comprises controlling the molar ratio of nitrogen oxide: urea to 1: 1 to 1: 1.2 in a high temperature region where the temperature of the exhaust gas is 600 占 폚 to 850 占 폚.
10. The method of claim 9,
Wherein the second treatment step comprises controlling the molar ratio of nitrogen oxide: urea to 1: 0.7 to 1: 0.9 in a medium to low temperature range where the temperature of the exhaust gas is 200 ° C to 550 ° C.
10. The method of claim 9,
The substrate of the diesel particulate filter may comprise at least one of cordierite, silicon carbide, acicular mullite, aluminum titanate and alloy foam. Lt; / RTI &gt;
And an average pore size of 10 mu m to 30 mu m, and has a honeycomb structure.
10. The method of claim 9,
The selective catalytic reduction catalyst may be one wherein copper (Cu) or iron (Fe) is ion-exchanged on the surface of the support,
Wherein the carrier comprises at least one of mordenite, beta-zeolite and ZSM-5.
15. The method of claim 14,
Wherein the catalyst for selective catalytic reduction comprises copper (Cu) or iron (Fe) in an amount of 15 wt% to 35 wt%.
10. The method of claim 9,
Wherein the exhaust gas purifying method further includes a third treatment step of instantly raising the temperature of the exhaust gas by regenerating the diesel particulate filter by directly injecting the liquid fuel into the diesel engine to instantaneously combust the exhaust gas, .
17. The method of claim 16,
Wherein the third treatment step instantaneously raises the temperature of the exhaust gas at the rear end of the exhaust pipe from 600 ° C to 650 ° C through instantaneous combustion to burn the soot of the diesel particulate filter.

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