KR101005742B1 - Nox Purification Device And Method Using Reformed Gas - Google Patents

Abstract

The present invention relates to an apparatus and method for reducing nitrogen oxide using reformed gas. More particularly, after the exhaust gas generated from a vehicle is introduced into a reformer to generate reformed gas using exhaust gas in the reformer, It is injected to the occlusion type catalyst front end exhaust pipe side installed in the exhaust pipe, and the occlusion type catalyst uses hydrogen and carbon monoxide of the reformed gas as a reducing agent in the denitrification process to reduce the NOx in the exhaust gas, thereby increasing the NOx reduction rate and The present invention relates to a nitrogen oxide reduction apparatus and method using reformed gas provided with first and second Nox sensors at the front and rear ends of the catalyst to check the reduction rate of Nox at the front and rear of the occlusion catalyst.

Reformer, Reformer Gas, Nitrogen Oxide, Storage Catalyst, Reduction Device

Description

Nox Purification Device And Method Using Reformed Gas

The present invention relates to an apparatus and a method for reducing nitrogen oxide using reformed gas, which is applied to an engine and a vehicle of a transport machine equipped with a reformed gas supply and use system to increase the NOx reduction efficiency.

Gasoline engines mix high-flammable fuels with air and then burn them in the engine using electric flames, which are currently widely used as a power source for automobiles. Market demand. However, the increase in oil cost demands new alternative energy engine technology, and it is expected that it will affect the share of gasoline engine in the future. In particular, as the pressure of diesel engines encroaching on the market with low CO ₂ emission and high efficiency characteristics increases, low exhaust and high fuel efficiency technologies are recognized as the most important countermeasures. In response to these demands, various fields such as Direct Injuction Spark Ignition (DISI) technology have been in the spotlight, and researches on elements representing each technology are underway.

In the case of gasoline direct injection technology, it is considered that the Lean Burn operation, which discharges gas containing 5% O ₂ or more in a low load region and operates with an air-fuel ratio of about 22, is highly applicable. However, oxidation of CO and HC in Lean Burn is not a problem, but it is difficult to remove Nox under severe oxidizing atmosphere gas conditions, and a system capable of removing Nox under such conditions is urgently needed.

In the Nox reduction reaction that occurs in general three-way catalyst, Nox decomposition is difficult due to self-poisoning caused by 0 ₂ . The chemisorption of nitrogen oxides on noble metals is easy and readily decomposes to N ₂ on catalysts. However, the oxygen desorption on the catalyst under lean burn ratio conditions is difficult in the absence of a separate reducing agent, and thus the nitrogen oxide is not continuously purified. Therefore, in order to remove 0 ₂ from the surface, reducing agents (HC, CO, H 2) and the like are required.

Precious metals are almost impossible to remove by the self-poisoning of oxygen on the surface of the catalyst under lean burn conditions in the use of automotive three-way catalysts. Therefore, the removal of Nox under lean burn conditions is another mechanism. The development of catalysts is absolutely required, and a method of supplying CO at the theoretical fuel consumption level for O ₂ desorption under lean combustion conditions, or a method of using the required reducing agent as urea is being sought. Among them, the applicability of the LNT (Lean Nox Trap) is most likely, but there is a disadvantage that the supply of additional reducing agent must be made.

The present invention has been made to solve the above problems, the object of the present invention is to apply the reformed gas supply and storage system to the actual engine, by using a simple reforming gas supply device and system addition and control method of Nox It is an object of the present invention to provide an apparatus and method for reducing nitrogen oxide using reformed gas to enable reduction.

Other objects and advantages of the invention will be described below and will be appreciated by the embodiments of the invention. Furthermore, the objects and advantages of the present invention can be realized by means and combinations indicated in the claims.

The present invention provides a means for solving the above problems, the reformer unit for injecting the exhaust gas of the vehicle by injecting the reformed gas generated through the steam reforming reaction to the exhaust pipe; An occlusion type catalyst installed in an exhaust pipe into which the reformed gas is injected and adsorbing and storing Nox in exhaust gas; First and second Nox sensors which are respectively installed at the front and rear ends of the sorbent catalyst and measure the amount of Nox in the exhaust gas flowing through the exhaust pipe; And a control unit.

In addition, the reforming unit includes a reforming apparatus for introducing the exhaust gas into the interior to generate a reformed gas of a high temperature, low pressure state using a built-in catalyst; A heat exchanger connected to a rear end of the reformer for reprocessing the flow of reformed gas; A cylinder connected to the heat exchanger to store a predetermined capacity of reformed gas; A relief valve connected to the cylinder to enable the user to discharge the reformed gas stored in the cylinder at a desired pressure and flow rate; An injector for injecting the reformed gas of the cylinder into the exhaust pipe; And a control unit.

In addition, the reforming unit is characterized in that the reformed gas is generated under high load conditions through theoretical fuel consumption combustion.

In addition, the nitrogen oxide reduction device using the reformed gas is by using a reforming gas containing hydrogen and carbon monoxide produced under high load conditions through theoretical fuel consumption combustion as a denitrification process reducing agent of the storage catalyst at low load conditions through lean combustion, It is characterized by reducing the Nox of the exhaust gas which flows through an exhaust pipe.

In addition, the first and second Nox sensors are respectively installed at the front of the occlusion type catalyst in which the reformed gas is injected into the exhaust pipe and mixed with the exhaust gas, and at the rear end of the occlusion type catalyst which is mixed and then passed through the occlusion type catalyst. It is characterized by measuring the amount of Nox, so that the reduced state of Nox can be known.

In addition, the first and second Nox sensors transmit respective measurement signals to an electrically connected engine control apparatus, and the engine control apparatus compares the measurement signals of the first and second Nox sensors to determine the amount of NOx reduction in the exhaust gas. It is characterized by.

As described above, the present invention can be applied not only to gasoline engines, but also to diesel engines, and can be applied to all operating regions, and thus, combustion control that can affect main factors such as engine combustion stability and exhaust emissions. This has the effect of providing very useful data.

Before describing the various embodiments of the present invention in detail, it will be appreciated that the application is not limited to the details of construction and arrangement of components described in the following detailed description or illustrated in the drawings. The invention may be embodied and carried out in other embodiments and carried out in various ways. It should also be noted that the device or element orientation (e.g., "front," "back," "up," "down," "top," "bottom, Expressions and predicates used herein for terms such as "left," " right, "" lateral, " and the like are used merely to simplify the description of the present invention, Or that the element has to have a particular orientation.

The present invention has the following features to achieve the above object.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the present specification and claims should not be construed as being limited to the common or dictionary meanings, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention.

Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations. Also, terms such as " first "and" second "are used herein for the purpose of the description and the appended claims, and are not intended to indicate or imply their relative importance or purpose.

Hereinafter, a nitrogen oxide reduction apparatus and method using a reforming gas according to a preferred embodiment of the present invention will be described in detail with reference to FIGS. 1 to 4.

As shown, the nitrogen oxide reduction apparatus and method using the reformed gas according to the present invention for reducing the nitrogen oxides of the exhaust gas generated in the vehicle through the reformed gas generated by introducing the exhaust gas into the reformer (10). Apparatus and method, reformer unit 100, occluded catalyst 110, first and second Nox sensors 120 and 121, reformer 10, heat exchanger 30, cylinder 50, relief valve 60, an injector 70, and an engine control device 130.

FIG. 1 is a schematic diagram of a system in which a reformer is mounted on an engine. As shown in the drawing, a reformer 10 is added to an existing fuel supply system, and the reformer 10 has a high temperature. Since the operating conditions are required, when the engine exhaust gas is recovered, the thermal efficiency of the reformer 10 itself may be expected to increase.

Figure 2 is a basic conceptual view showing an embodiment of the reforming unit according to the present invention, Figure 3 is a schematic diagram according to an embodiment of the nitrogen oxide reduction apparatus using the reforming gas according to the present invention, Figure 2 is applied, Figure 4 As a flow chart of an embodiment showing a method for reducing nitrogen oxide using reformed gas according to the present invention, as shown in the drawing, as a basic conceptual diagram for applying a reformer for generating reformed gas to a real engine, the reformer 10 The high-temperature, high-pressure reformed gas generated in the) to be made available to the engine, it is to enable the injection control using the injector 70 which will be described later.

Looking at the configuration, while generating a reformed gas of a high temperature / low pressure of 500 to 700 ℃ and below atmospheric pressure, while supplying air and fuel through the supply line 21, the exhaust gas inlet line 20 of the vehicle A reformer 10 having a built-in catalyst 11 and a rear end of the reformer 10, generating a reformed gas by introducing the exhaust gas into the steam and causing the water in the fuel and the exhaust gas to undergo a steam reforming reaction. Coupled to the heat exchanger 30 for reprocessing the reformed gas generated in the reformer 10 to be sprayed by the injector 70 to be described later, and connected to the heat exchanger 30 to remove moisture in the reformed gas. A humidifier 40, a cylinder 50 connected to the humidifier 40 to store the reformed gas to a predetermined capacity desired by the user, and the reformed gas installed at the cylinder 50 to the pressure and flow rate desired by the user. Can supply Relief valve 60 for controlling the pressure in the cylinder 50 to store the reformed gas so that (reformation of the reformer 10, of course, in the state of continuous flow reforming of the high temperature, low pressure is made smoothly Naturally, it consists of a high flow rate, low leakage injector 70 that injects a certain amount of reformed gas stored in the cylinder 50 into the exhaust pipe P1 of the vehicle.

The direct injection gasoline engine technology can satisfy the two conflicting factors of fuel economy and high power by injecting fuel directly into the combustion chamber and enabling high-efficiency combustion even in very thin mixers by precise combustion control. As described above, there is a problem in that it is not possible to reduce the Nox magnification under lean combustion conditions, and the present invention includes the reformer 100 to solve the problem, and is generated from the reformer 10 of the reformer 100. The reformed gas is injected into the exhaust pipe P1. This will be divided into the generation and use of reformed gas, which will be explained as follows.

1. Generation of reformed gas (high load (theoretical fuel consumption) conditions (FIG. 2)): When theoretical fuel consumption is combusted to obtain a high output, the temperature of the exhaust gas discharged from the engine increases and the ratio of oxygen contained in the exhaust gas As shown in FIG. 2, as shown in FIG. 2, the exhaust gas generated from the vehicle is directly passed to the reformer 10 through the exhaust gas inlet line 20 so that the water and the fuel supplied in the exhaust gas undergo steam reforming reaction (SR). Steam reforming occurs to generate reformed gas (H2 + CO), and the generated reformed gas is stored in the cylinder 50 to a predetermined capacity desired by the user to allow the user to discharge the cylinder at a desired pressure. Pressurize the inside to a certain level. (At this time, if an additional air supply system is configured, a partial oxidation reforming reaction (POx, Partial Oxidation) using partial oxidation of the fuel or an autothermal reforming reaction (ATR) using water in the exhaust gas at the same time may also be carried out. It can be used as a generated mechanism.)

2. Use of reformed gas (low load (lean burn conditions) (FIG. 3)): O _{2 in a} lean burn zone with excess air CO and HC are remarkably reduced because of the rich oxidation and active oxidation reaction, but the reduction reaction is difficult and almost no reduction of NOx is observed. In the present invention, LNT (Lean Nox Trap) was used as the occlusion catalyst 110. The LNT is converted into nitrogen and carbon dioxide by a catalyst by capturing Nox in a lean region and then discharging it in a rich region. It has a three-way catalytic function, and it absorbs and stores Nox as a Nox trap in the lean area, purifies the collected Nox when fuel is injected or the air-fuel ratio is high, and at the same time restores the Nox trap function. Reducing agent performance of the LNT catalyst is H ₂ 2 and 3, the reformed gas containing hydrogen and CO (carbon monoxide) generated under high load conditions (theoretical fuel consumption combustion) is used as a reducing agent in the denitrification process. It is used to reduce Nox.

In other words, by using the above-described method, high efficiency engine combustion of low fuel consumption and low exhaust, which is incompatible with a gasoline engine, becomes possible.

In addition, as shown in FIG. 3, first and second Nox sensors 120 and 121 are respectively installed at the front and rear ends of the storage catalyst 110, and the first Nox sensor 120 is the storage type. It is installed at the front end of the catalyst 110, the reformed gas generated from the reformer 10 of the reformer unit 100 and injected into the exhaust pipe (P1) through the injector 70 and the exhaust gas flowing in one direction; In addition, it is installed at the portion introduced through the front end of the occlusion type catalyst 110, to measure the amount of Nox in the exhaust pipe (P1) before the exhaust gas passes through the occlusion type catalyst (110). In addition, the second Nox sensor 121 is installed at the rear end of the storage catalyst 110 to measure the amount of Nox in the exhaust gas flowing through the storage catalyst 110 with the reformed gas.

Each of the first and second Nox sensors 120 and 121 is electrically connected to an engine control unit (ECU) 130 in the vehicle, and the engine control unit 130 is connected to the first and second Nox sensors. After receiving the measurement signals from the sensors 120 and 121, the two signals are compared with each other, so that the amount of NOx reduction before and after the occlusion type catalyst 110 generated by injecting the reformed gas into the exhaust pipe P1 is known. It will be possible.

Hereinafter, a method of reducing a preferred embodiment of the present invention having the configuration and structure as described above will be described with reference to FIG. 4.

1. Measuring the pressure in the cylinder 50 in which the reformed gas generated through the reformer 10 of the reformer 100 is stored in a predetermined capacity, in the present invention, the pressure in the cylinder 50 is 3 to 3; 5 bar (step S100).

2. After step S100, when the pressure in the cylinder 50 is about 3 to 5 bar, the first and second Nox sensors 120 and 121 at the front and rear ends of the storage type catalyst 110 installed in the exhaust pipe P1. The amount of Nox is measured from each, but it is determined whether the amount of each measured Nox is similar to each other (step S200).

3. After the step (S200), if the amount of each Nox measured by the first and second Nox sensors (120, 121) are similar, it is determined whether the theoretical air-fuel ratio operating conditions (step S300), not the theoretical air-fuel ratio operating conditions In the case of controlling the fuel to be rich in instantaneous air-fuel ratio to form a theoretical air-fuel operating conditions (S400), in the case of the theoretical air-fuel ratio operating conditions reforming gas using the injector 70 in front of the occlusion type catalyst 50 installed in the exhaust pipe (P1) (S500 step), and if the amount of each Nox measured by the first and second Nox sensors (120, 121) is not similar to the injection of reformed gas to the intake pipe (P2) (step S310).

4. After setting the theoretical air-fuel ratio operating condition as in the step S310 or step S500, the NOx is reduced through the storage catalyst 110. (S600 step)

However, in step S100 of measuring the pressure of the cylinder 50, if the pressure is not high enough, in order to move to step S200, the pressure in the cylinder 50 must be increased, for this purpose, the pressure measuring step (S100) After the pressure in the cylinder 50 is low,

1-1. Determining whether the theoretical air fuel ratio is a driving condition (step S110);

1-2. After the step (S110), if the theoretical air-fuel ratio operating conditions, the exhaust gas is introduced into the reforming apparatus 10, so that the reformed gas is generated by the steam reforming reaction (SR) of the water and the introduced fuel of the exhaust gas ( Step S120), if the theoretical air-fuel ratio is not operating conditions, after the exhaust gas is introduced into the reformer 10, partial oxidation reforming reaction (POx) or steam reforming reaction and partial oxidation reforming reaction using partial oxidation reaction of the introduced fuel. Using both autothermal reforming reaction (ATR) to generate a reformed gas (step S130).

1-3. When the reformed gas is generated through the step S120 or the step S130, the generated reformed gas is pressurized and stored in the cylinder 50 to increase the pressure (step S140). Subsequently, by performing the step S100 again to check whether the pressure in the cylinder 50 is high, if it is satisfied, the method for reducing Nox is continued, and if it is not satisfied, the steps S110 to S140 are sequentially performed again.

In addition, the symbols of the drawings that are not described in the above detailed description

A stands for MFM (Mass Flow Meter), B stands for Check Valve, C stands for Gas Chromatography (GC), and D stands for Mass Flow Controller (MFC).

As mentioned above, although this invention was demonstrated by the limited embodiment and drawing, this invention is not limited by this, The person of ordinary skill in the art to which this invention belongs, Various modifications and changes may be made without departing from the scope of the appended claims.

1 is a schematic diagram of a system equipped with a reformer in an engine;

2 is a basic conceptual view showing an embodiment of a reforming unit according to the present invention.

Figure 3 is a schematic diagram according to an embodiment of the nitrogen oxide reduction device using the reformed gas according to the present invention Figure 2 is applied.

Figure 4 is a flow chart of one embodiment showing a method for reducing nitrogen oxides using the reformed gas according to the present invention.

<Indication of symbols for main parts of drawing>

10: reformer 11: catalyst

20: exhaust gas inlet line 21: supply line

30: heat exchanger 40: humidifier

50: cylinder 60: relief valve

70: injector 100: reforming unit

110: stored catalyst 120: first Nox sensor

121: second Nox sensor 130: engine control device

Claims (8)

A reforming unit unit 100 which injects the exhaust gas of the vehicle and injects the reformed gas generated through the reforming reaction into the exhaust pipe P1; An occlusion type catalyst (110) installed in the exhaust pipe (P1) to which the reformed gas is injected to adsorb and store Nox in the exhaust gas; First and second Nox sensors (120, 121) installed at the front and rear ends of the storage catalyst (110), respectively, for measuring the amount of Nox in the exhaust gas flowing through the exhaust pipe (P1); Nitrogen oxide reduction device using a reforming gas, characterized in that configured to include a. The method of claim 1, The reformer 100 is A reforming apparatus (10) for introducing fuel, air, and exhaust gas into the interior to cause reforming reaction of the exhaust gas and fuel to generate reformed gas; A heat exchanger (30) connected to the rear end of the reformer (10) for reprocessing the flow of reformed gas so as to be sprayable; A cylinder (50) connected to the heat exchanger (30) to store a predetermined capacity of reformed gas; A relief valve 60 connected to the cylinder 50 to enable the user to discharge the reformed gas stored in the cylinder 50 at a desired pressure and flow rate; An injector 70 for injecting the reformed gas of the cylinder 50 into the exhaust pipe P1; Nitrogen oxide reduction device using a reforming gas, characterized in that configured to include a. The method of claim 1, The reformer unit 100 is a nitrogen oxide reduction device using the reformed gas, characterized in that for the reformed gas is generated under high load conditions through the theoretical fuel consumption combustion. The method of claim 1, Nitrogen oxide reduction device using the reformed gas A reformed gas containing hydrogen and carbon monoxide produced under high load conditions through theoretical fuel consumption combustion is used as a reducing agent for the denitrification process of the occlusion type catalyst 110 under low load conditions through lean combustion, thereby exhaust gas flowing through the exhaust pipe P1. Nitrogen oxide reduction device using a reforming gas, characterized in that to reduce the Nox of. The method of claim 1, The first and second Nox sensors 120 and 121 may have a front end of an occlusion type catalyst 110 into which the reformed gas injected into the exhaust pipe P1 and the exhaust gas flowing through the exhaust pipe P1 are mixed and introduced. Nitrogen oxide reduction using reformed gas, which is installed at the rear end of the storage type catalyst 110 in the state of passing through the storage type catalyst 110 to measure the amount of Nox in the exhaust gas so that the amount of reduction of Nox can be known. Device. The method of claim 5, The first and second Nox sensors 120 and 121 transmit the respective measurement signals to the electrically connected engine controller 130, and the engine controller 130 first and second Nox sensors 120 and 121. The nitrogen oxide reduction apparatus using the reformed gas, characterized in that for determining the amount of NOx reduction in the exhaust gas by comparing the measured signal of the. Measuring the pressure in the cylinder 50 in which the reformed gas generated through the reformer 10 is stored in a predetermined capacity (S100); After the step S100, when the pressure in the cylinder 50 is high, each Nox measured by the first and second Nox sensors 120 and 121 at the front and rear ends of the storage type catalyst 110 installed in the exhaust pipe P1. Determining whether the quantities are similar (S200); After the step S200, when the amount of each Nox measured by the first and second Nox sensors 120 and 121 is similar, determining whether the theoretical air-fuel ratio driving condition is performed (S300); After the step (S200), injecting reformed gas into the intake pipe (P2) when the amount of each Nox measured by the first and second Nox sensors (120, 121) is not similar (S310); After the step (S300), if not the theoretical air-fuel ratio operating condition to control the instantaneous rich air-fuel ratio to form a theoretical air-fuel driving conditions (S400); After the step (S300), in the case of the theoretical air-fuel ratio operating conditions, the step of injecting the reformed gas to the front end exhaust pipe (P1) of the storage type catalyst (110) (S500); After the step (S310) or step (S500), the step of reducing the Nox through the occluded catalyst (110) (S600); Nitrogen oxide reduction method using a reforming gas, characterized in that comprises a. The method of claim 7, wherein Nitrogen oxide reduction method using the reformed gas After the step (S100), if the pressure in the cylinder 50 is low, Determining whether the theoretical air-fuel ratio driving condition (S110); After the step (S110), when the theoretical air-fuel ratio operating conditions, by introducing the exhaust gas to the reformer 10, the water and the fuel of the exhaust gas to cause the steam reforming reaction (SR) to generate a reformed gas (S120); After the step (S110), if the theoretical air-fuel ratio operating conditions, the exhaust gas is introduced into the reforming unit 10, the partial oxidation reforming reaction (POx) or steam reforming reaction and partial using the partial oxidation reaction of the introduced fuel Generating a reformed gas using an autothermal reforming reaction (ATR) using all of the oxidation reforming reactions (S130); After the step (S120) or step (S130), the step of increasing the pressure by storing the reformed gas in the cylinder (50) (S140); Nitrogen oxide reduction method using a reforming gas, characterized in that it is made by repeating sequentially.

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