KR100836367B1 - purification device for diminishing PM and NOx of diesel engine - Google Patents

Abstract

The present invention is to generate a reducing agent from the fuel injected after the regeneration of the nitrogen oxide storage catalyst and to regenerate the nitrogen oxide storage catalyst through this, to achieve a more stable purification function of NOx (NOx) Its purpose is to.

In order to achieve the above object, the present invention, the diesel particulate catalytic filtration filter (CPF) is installed in the exhaust pipe of the diesel engine to collect particulate matter (PM); A differential pressure sensor for detecting an amount of particulate matter (PM) collected in the diesel particulate catalyst filtering filter (CPF); A post injection injector installed in the exhaust pipe passage; A diesel fuel decomposition catalyst (DFC) for decomposing fuel injected from the after injection injector; A nitrogen oxide storage catalyst (de-NOx catalyst) for reducing and removing nitrogen oxides (NOx) accumulated therein through a reducing agent generated in the diesel fuel decomposition catalyst (DFC); A detection sensor installed in the exhaust pipe path and detecting an amount of nitrogen oxide (NOx); The regeneration time of the fuel is determined by determining the regeneration time of the diesel particulate catalyst filtration filter through the differential pressure sensor, and the regeneration time of the de-NOx catalyst is determined by the detection sensor. It is characterized in that it comprises a control unit for determining and adjusting the post injection amount of fuel.

Description

Purification device for diminishing PM and NOx of diesel engine

1 is a view showing the configuration of a purification apparatus for reducing particulate matter and nitrogen oxides of a diesel engine according to the present invention.

2 illustrates another embodiment of the present invention.

The present invention relates to a purification apparatus capable of reducing particulate matter and nitrogen oxide contained in exhaust gas of a diesel engine.

A purifier that simultaneously reduces particulate matter and nitrogen oxides contained in the exhaust gas of a conventional diesel engine includes a diesel particulate catalyst filtration filter (CPF), a nitrogen oxide de-NOx catalyst, and a diesel oxidation catalyst (DOC). Sequentially install, and install an auxiliary exhaust pipe branched from the exhaust pipe on the front exhaust pipe of the diesel particulate catalyst filtration filter (CPF), and open / close valve and secondary injection system and diesel fuel decomposition in the auxiliary exhaust pipe. While installing a catalyst (DFC), the outlet to the auxiliary exhaust pipe has a structure located in front of the nitrogen oxide de-NOx catalyst.

In this case, a differential pressure sensor for detecting the amount of particulate matter (PM) stored therein is installed at the front and rear of the diesel particulate catalyst filtration filter (CPF), and the exhaust gas at the rear of the diesel oxidation catalyst (DOC). A nitrogen oxide detection sensor for detecting the concentration of heavy nitrogen oxides (NOx) is provided.

However, in the conventional purification device as described above, a fuel is decomposed using a diesel fuel decomposition catalyst (DFC) to generate a reducing agent, and the generated reducing agent is supplied to a nitrogen oxide storage catalyst (de-NOx catalyst). Decomposition catalyst (DFC) is rapidly oxidized according to the conditions of the exhaust gas, there is a problem that does not produce a reducing agent by decomposing the fuel injected in the secondary injection system, but rather oxidize the fuel to purify.

In addition, the fuel injected from the secondary injection system in the desulfurization mode of the nitrogen oxide de-NOx catalyst carried out rearward by using regeneration heat during the forced regeneration of the diesel particulate catalyst filtration filter (CPF) is a diesel fuel decomposition catalyst. (DFC) may cause a sudden oxidation reaction, which rapidly raises the inlet exhaust gas temperature of the de-NOx catalyst to cause abnormal deterioration of the nitrogen oxide storage catalyst (LNT).

In addition, the conventional purifier has a separate bypass pipe branched from the exhaust pipe in front of the diesel particulate catalyst filtration filter (CPF) and having an outlet in front of the de-NOx catalyst. There has been a problem of having a complicated structure in which a diesel fuel decomposition catalyst (DFC) is embedded in a phase.

Accordingly, the present invention has been made to solve the above-mentioned issues, by generating a reducing agent from the fuel injected after the regeneration of the nitrogen oxide storage catalyst, and through this regeneration of the nitrogen oxide storage catalyst, the NOx (NOx Its purpose is to enable more stable purification of).

In order to achieve the above object, the present invention provides a diesel particulate catalytic filter (CPF) for collecting particulate matter (PM) in a single exhaust path through which exhaust gas is discharged through an exhaust pipe of a diesel engine, and after injection. Diesel fuel decomposition catalyst (DFC) for decomposing the generated fuel to generate a reducing agent, and nitrogen oxide storage catalyst for reducing and removing nitrogen oxide (NOx) accumulated through the reducing agent generated in the diesel fuel decomposition catalyst (DFC). (de-NOx catalyst) each installed sequentially;
Installing a differential pressure sensor for detecting an amount of particulate matter (PM) collected in the diesel particulate catalyst filtering filter (CPF) by detecting a pressure difference between the front and rear ends of the diesel particulate catalyst filtering filter (CPF);
A post injection injector for performing post injection of fuel behind the diesel particulate catalyst filtration filter (CPF);
A sensor for detecting an amount of nitrogen oxide (NOx) contained in exhaust gas in front of the diesel fuel decomposition catalyst (DFC);
Determine the regeneration time of the diesel particulate catalyst filtration filter (CPF) from the signal detected by the differential pressure sensor to adjust the post injection amount of the fuel made through the injector of the diesel engine, and the nitrogen oxide from the signal detected by the sensor It is provided with a control unit for determining the regeneration time of the de-NOx catalyst to adjust the post injection amount of the fuel made through the post injection injector.
In addition, the present invention captures a diesel fuel decomposition catalyst (DFC) and particulate matter (PM) to decompose the fuel injected after the injection for the single exhaust path through which the exhaust gas is discharged through the exhaust pipe of the diesel engine to generate a reducing agent A diesel particulate catalyst filtration filter (CPF) and a nitrogen oxide storage catalyst (de-NOx catalyst) for reducing and removing nitrogen oxides (NOx) accumulated through a reducing agent generated in the diesel fuel decomposition catalyst (DFC). Each installed sequentially;
A post injection injector for performing post injection of fuel in front of the diesel fuel decomposition catalyst (DFC);
Installing a differential pressure sensor for detecting the amount of particulate matter (PM) collected in the diesel particulate catalyst filtering filter (CPF) by detecting a pressure difference between the front and rear ends of the diesel particulate catalyst filtering filter (CPF);
A sensor for detecting an amount of nitrogen oxide (NOx) contained in exhaust gas in front of the nitrogen oxide de-NOx catalyst;
Determine the regeneration time of the diesel particulate catalyst filtration filter (CPF) from the signal detected by the differential pressure sensor to adjust the post injection amount of the fuel made through the injector of the diesel engine, and the nitrogen oxide from the signal detected by the sensor It is provided with a control unit for determining the regeneration time of the de-NOx catalyst to adjust the post injection amount of the fuel made through the post injection injector.

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Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in the figure, the present invention provides a diesel particulate catalytic filter (CPF) 14 for a single exhaust path through which exhaust gas is discharged through an exhaust pipe 12 of a diesel engine 10. And a diesel fuel cracking catalyst (DFC) 16 and a de-NOx catalyst 18, respectively, and are installed inside the diesel particulate catalyst filtration filter 14. In order to detect the amount of particulate matter (PM; Particulate Matter) collected in the diesel particulate catalyst filter (CPF) 14 is installed between the front and rear of the differential pressure sensor 20 for detecting the pressure difference And a post injection injector 22 and the nitrogen for post injection of fuel to the front end of the diesel fuel decomposition catalyst (DFC) 16 based on the exhaust path which is the flow direction of the exhaust gas in the exhaust pipe 12. Detecting the amount of NOx accumulated in the oxide de-NOx catalyst 18 Install the sensor 24 respectively.

Here, the diesel particulate catalyst filtering filter (CPF) 14 collects particulate matter (PM) contained in the exhaust gas discharged through the exhaust pipe passage 12, and the diesel engine 10 of the diesel engine 10 when the filter is regenerated. The particulate matter PM collected by the fuel post-injection made by the injector 10a is burned and removed.

In addition, the diesel particulate catalyst filtration filter (CPF) 14 has an exhaust manifold of the diesel engine 10 in a state in which a diesel oxidation catalyst (DOC) 14a is locally coated on the front end of the diesel particulate catalyst (CPF) 14. It is formed in a region adjacent to 11), and is made of a so-called Closed Catalyst Converter (CCC) type catalyst device that is capable of directly transferring heat from exhaust gas from the exhaust manifold 11.

In addition, the diesel fuel decomposition catalyst (DFC) 16 decomposes fuel injected from the after-injector injector 22 to generate a reducing agent, and the nitrogen oxide de-NOx catalyst 18 is the diesel. Nitrogen oxides (NOx) accumulated therein are reduced by means of a reducing agent produced in the fuel decomposition catalyst (DFC) 16 to be removed.

In this case, the diesel fuel decomposition catalyst (DFC) 16 breaks the chain of carbon elements through the catalytic reaction of diesel fuel, which is the fuel of the diesel engine 10, to decompose a highly reactive carbon monoxide (CO) and hydro of short chains. It acts to convert to reducing agents such as carbon (CH) and hydrogen (H ₂ ).

That is, the diesel fuel cracking catalyst (DFC) 16 breaks through a link ring of carbon constituting a hydrocarbon compound, which is a main component of the fuel, as described in the following chemical formula through a thermal cracking function for decomposing a fuel. .

Thermal cracking;

C ₁₆ H ₃₄ → 2n-C ₈ H ₁₇ * → nC ₆ H ₁₃ * → nC ₄ H ₉ * → C ₂ H ₅ * → C ₂ H ₄

C ₁₆ H ₃₄ → 8C ₂ H ₄ + H ₂

In this case, * means radical.

In addition, the diesel fuel decomposition catalyst (DFC) 16 has a steam reforming function and a partial oxidation function for generating a reducing agent from the decomposed fuel, respectively, as described in the following chemical formula.

Forming a reducing agent carbon monoxide (CO) and hydrogen (H ₂ ) from the decomposed fuel (Steam Reforming);

C ₁₆ H ₃₄ + 16H ₂ O ↔ 16CO + 33H ₂

Making carbon monoxide (CO), hydrocarbon (CH) and hydrogen (H ₂ ), which are reducing agents, from the decomposed fuel (Partial Oxidation);

C ₁₆ H ₃₄ + 1 / 2O ₂ → 8C ₂ H ₄ + H ₂ O

C ₁₆ H ₃₄ +8 O ₂ ↔ 16CO + 17H ₂

Accordingly, the reducing agent produced by the diesel fuel decomposition catalyst (DFC) 16 reacts with nitrogen by directly injecting the fuel injected from the after injection injector 22 with the de-NOx catalyst 18. It is possible to prevent the rapid oxidation reaction occurring in the oxide de-NOx catalyst 18, thereby preventing deterioration of the nitrogen oxide de-NOx catalyst 18 due to the oxidation reaction.

As a result, the diesel fuel decomposition catalyst (DFC) 16 can reduce the adsorbed nitrogen oxides (NOx) to nitrogen (N ₂ ).

On the other hand, the nitrogen oxide de-NOx catalyst 18, like the diesel fuel decomposition catalyst (DFC) 16 at the front end portion based on the exhaust path, the fuel injected from the after injection injector 22 It consists of a catalytic device partially equipped with a catalyst (18a) for generating a reducing agent to decompose to generate a reducing agent.

In other words, the nitrogen oxide de-NOx catalyst 18 basically includes a catalyst coating for purifying nitrogen oxides (NOx), and the diesel fuel decomposition catalyst (DFC) 16 at its front end. Complementing the function of, that is to further include a catalyst coating for reducing agent generation for generating a reducing agent by decomposing the fuel.

As a result, the nitrogen oxide de-NOx catalyst 18 is partially equipped with the catalyst 18a for generating the reducing agent, thereby reducing the capacity of the relatively expensive diesel fuel decomposition catalyst (DFC) 16. Will be.

On the other hand, the control unit 26 determines the regeneration time of the diesel particulate catalyst filtration filter (CPF) 14 from the signal detected by the differential pressure sensor 20, and the nitrogen from the signal detected by the detection sensor 24 The regeneration time of the oxide de-NOx catalyst 18 is determined.

In this case, when the control unit 26 determines the regeneration time of the diesel particulate catalyst filtration filter (CPF) 14 through the differential pressure sensor 20, the injector 10a of the diesel engine 10 is driven. After controlling the after injection amount of the fuel injected from the injector (10a), and determines the regeneration time of the de-NOx catalyst (18) through the sensor 24, the after-minute The driving of the use injector 22 is controlled to adjust the post injection amount of the fuel injected from the post injection injector 22.

In addition, in the present invention, the diesel fuel decomposition catalyst (DFC) 16 is located at a front end portion than the de-NOx catalyst 18 based on the exhaust path, the diesel particulate catalyst filtration filter (CPF) 14 is located in front of the nitrogen oxide de-NOx catalyst 18, according to the first embodiment of the present invention, the diesel particulate catalyst filtration filter (CPF) 14 ) Is positioned at a front end portion of the diesel fuel decomposition catalyst (DFC) 16 with respect to the exhaust path.

In this case, the diesel fuel cracking catalyst (DFC) 16 is sequentially installed on the basis of the exhaust path in the same housing as the nitrogen oxide de-NOx catalyst 18.

In addition, according to the second embodiment of the present invention, the diesel fuel decomposition catalyst (DFC) 16 is configured to be located at the front end portion than the diesel particulate catalyst filtration filter (CPF) 14 with respect to the exhaust path.

In this case, the diesel fuel decomposition catalyst (DFC) 16 is sequentially installed on the basis of the exhaust path in a housing separated from each other in a state spaced apart from the de-NOx catalyst 18.

On the other hand, in the first and second embodiments of the present invention, the after injection injector 22 is located at a front end portion of the diesel fuel decomposition catalyst (DFC) 16 on the exhaust pipe passage 12, and the detection sensor 24 is disposed on the exhaust pipe 12 so as to be located at a front end portion than the de-NOx catalyst 18.

In this case, the detection sensor 24 detects in real time the amount of nitrogen oxides (NOx) contained in the exhaust gas flowing through the exhaust pipe passage 12 and outputs it to the control unit 26, the control unit 26 ) Estimates the amount of nitrogen oxides (NOx) accumulated in the nitrogen oxide storage catalyst (de-NOx catalyst) 18 via the signal input from the sensor 24, and denitrates the nitrogen oxide storage catalyst (de). Regeneration time for the nitrogen oxide de-NOx catalyst 18 is calculated by comparing the amount of nitrogen oxides (NOx) accumulated with respect to the capacity of the -NOx catalyst 18.

As a result, the control unit 26 can more accurately calculate the regeneration time for the nitrogen oxide de-NOx catalyst 18, thereby more actively evacuating NOx emissions. Can be prevented.

Hereinafter, the operation of the purification device for reducing particulate matter and nitrogen oxides of the diesel engine according to the present invention.

First, when the exhaust gas is discharged through the exhaust pipe passage 12 after combustion of the diesel engine 10, particulate matter (PM) contained in the exhaust gas is collected in the diesel particulate catalyst filtration filter (CPF) 14 Nitrogen oxides (NOx) are accumulated in the nitrogen oxide de-NOx catalyst 18.

In the course of this process, the control unit 26 determines the regeneration time for the diesel particulate catalytic filtration filter (CPF) 14 through the differential pressure sensor 20, the diesel engine ( A post injection signal is output to the injector 10a of 10) to oxidize and remove the particulate matter collected through the post injection fuel.

In addition, the control unit 26 determines the regeneration time for the de-NOx catalyst 18 through the detection sensor 24, and when the regeneration time arrives, the post injection injector ( 22, and outputs a post injection signal, the fuel post injection from the post injection injector 22 is highly reactive through the diesel fuel decomposition catalyst (DFC) 16 and the reducing agent generation catalyst (18a). It is converted into a reducing agent such as carbon monoxide (CO) and short chain hydrocarbon (CH) and hydrogen (H ₂ ) to provide the de-NOx catalyst 18.

At this time, the nitrogen oxide storage catalyst (de-NOx catalyst) 18 is discharged by reducing the nitrogen oxides (NOx) accumulated through the provided reducing agent with nitrogen (N ₂ ).

As a result, the post-injected fuel can directly react with the nitrogen oxide de-NOx catalyst 18, thereby preventing the abrupt oxidation reaction accompanying, and thus the nitrogen oxide de-NOx catalyst. It is possible to prevent damage due to deterioration of (18).

In addition, the present invention separately separates the process of desulfurization regeneration at high temperature conditions of the exhaust gas which is carried out to solve the sulfur poisoning of the nitrogen oxide de-NOx catalyst 18 by the sulfur component contained in the diesel fuel. The nitrogen oxide storage catalyst (de) is carried out through the heat discharged during the regeneration of the diesel particulate catalyst filtration filter (CPF) 14 using the exhaust heat transferred from the exhaust manifold 11 of the diesel engine 10 without performing it. It is possible to implement desulfurization regeneration for -NOx catalyst (18).

That is, the nitrogen oxide storage catalyst (CN) is formed by using the exhaust heat generated during the regeneration of the diesel particulate catalyst filtration filter (CPF) 14 formed by post injection of the fuel in the injector 10a of the diesel engine 10 ( Since the heat source required for the desulfurization process of the de-NOx catalyst 18 can be obtained, it is possible to reduce the amount of post-injected fuel and to improve fuel economy.

As described above, according to the purifying apparatus for reducing particulate matter and nitrogen oxides of the diesel engine according to the present invention, after the regeneration of the nitrogen oxide storage catalyst, the fuel injected after decomposition is generated through a diesel fuel decomposition catalyst to generate a reducing agent, By using the generated reducing agent, it is possible to prevent damage due to deterioration of the nitrogen oxide storage catalyst accompanying the overheating caused by the oxidation reaction with the catalyst when the nitrogen oxide accumulated in the nitrogen oxide storage catalyst is regenerated, and to remove the normal nitrogen oxide removal. It can be implemented.

Claims (8)

The diesel particulate catalyst filtration filter (CPF) 14 which collects particulate matter (PM) in a single exhaust path through which the exhaust gas is discharged through the exhaust pipe passage 12 of the diesel engine 10, and the post-injected fuel A nitrogen fuel decomposition catalyst (DFC) 16 that decomposes to produce a reducing agent, and nitrogen that reduces and removes nitrogen oxides (NOx) accumulated through a reducing agent generated in the diesel fuel decomposition catalyst (DFC) 16 through a reduction treatment. The oxide de-NOx catalysts 18 were each sequentially installed; Differential pressure for detecting the amount of particulate matter (PM) trapped in the diesel particulate catalyst filtering filter (CPF) 14 by detecting the pressure difference between the front and rear ends of the diesel particulate catalyst filtering filter (CPF) 14 Install sensor 20; A post injection injector 22 for post-injection of fuel is provided behind the diesel particulate catalyst filtration filter (CPF) 14; A detection sensor 24 for detecting an amount of nitrogen oxide (NOx) contained in exhaust gas in front of the diesel fuel decomposition catalyst (DFC) 16; Determine the regeneration time of the diesel particulate catalyst filtration filter (CPF) 14 from the signal detected by the differential pressure sensor 20 to adjust the post injection amount of the fuel made through the injector of the diesel engine 10, the detection The control unit 26 for determining the regeneration time of the de-NOx catalyst 18 from the signal detected by the sensor 24 to adjust the post injection amount of fuel made through the post injection injector 22. Purification apparatus for reducing particulate matter and nitrogen oxides of the diesel engine having a. A diesel fuel decomposition catalyst (DFC) 16 which decomposes the post-injected fuel for a single exhaust path through which the exhaust gas is discharged through the exhaust pipe passage 12 of the diesel engine 10 to generate a reducing agent, and particulate matter ( Nitrogen to reduce and remove nitrogen oxides (NOx) accumulated through a diesel particulate catalyst filtration filter (CPF) 14 for collecting PM) and a reducing agent generated in the diesel fuel decomposition catalyst (DFC) 16. The oxide de-NOx catalysts 18 were each sequentially installed; A post injection injector 22 for post-injection of fuel is installed in front of the diesel fuel decomposition catalyst (DFC) 16; Differential pressure for detecting the amount of particulate matter (PM) trapped in the diesel particulate catalyst filtering filter (CPF) 14 by detecting the pressure difference between the front and rear ends of the diesel particulate catalyst filtering filter (CPF) 14 Install sensor 20; A sensor (24) for detecting the amount of nitrogen oxide (NOx) contained in the exhaust gas in front of the nitrogen oxide de-NOx catalyst (18); Determine the regeneration time of the diesel particulate catalyst filtration filter (CPF) 14 from the signal detected by the differential pressure sensor 20 to adjust the post injection amount of the fuel made through the injector of the diesel engine 10, the detection The control unit 26 for determining the regeneration time of the de-NOx catalyst 18 from the signal detected by the sensor 24 to adjust the post injection amount of fuel made through the post injection injector 22. Purification apparatus for reducing particulate matter and nitrogen oxides of the diesel engine having a. The method according to claim 1 or 2, The diesel particulate catalyst filtration filter (CPF) 14 is a CCC type catalyst device having a diesel oxidation catalyst (DOC) (14a), characterized in that the purification device for reducing particulate matter and nitrogen oxides of the diesel engine. The method according to claim 1 or 2, The nitrogen oxide de-NOx catalyst 18 is a catalyst device having a catalyst 18a for generating a reducing agent for decomposing fuel injected through the after injection injector 22 to generate a reducing agent. Purifier for reducing particulate matter and nitrogen oxides in diesel engines. delete delete delete delete

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