KR20080003956A - Exhaust gas treatment system for low exhaust temperature vehicle using catalytic combustion type diesel injector - Google Patents

Abstract

An exhaust gas treatment system is provided to remove particulate soot effectively even in a low exhaust temperature vehicle through a catalytic combustion. An exhaust gas treatment system includes a diesel oxidation catalyst unit for oxidation of organic matter and nitrogen oxide in exhaust gas, and a diesel particulate filter unit for combustion of particulate soot by a catalyst. The diesel oxidation catalyst unit and the diesel particulate filter unit are sequentially arranged from an upper-stream relatively to the flow of exhaust gas. The diesel oxidation catalyst unit has a front end with an electric heating catalyst unit.

Description

Exhaust Gas Treatment System For Low Exhaust Temperature Vehicle using Catalytic Combustion Type Diesel Injector}

1 is a graph showing the soot oxidation reaction rate by NO ₂ and O ₂ ,

2 shows a catalyst filter regeneration mechanism by NO and NO ₂ ,

Figure 3 is a side view of the smoke reduction system to which the catalytic combustion diesel injector used in the present invention,

Figure 4 shows that the exhaust gas is heated by the catalytic combustion diesel injector used in the present invention,

5 is a result of measuring the temperature change in the exhaust pipe when driving the catalytic combustion diesel injector in the smoke reduction system according to the present invention.

<Explanation of symbols for the main parts of the drawings>

1: Diesel Oxidation Catalyst (DOC)

2: Diesel Particulate Filter (DPF)

3: pressure sensor 4, 7: temperature sensor

5: Data storage, alarm and injector control unit

6: Distributor to help vaporize injected diesel and mix with exhaust

8: diesel injector 9: diesel pump

10: diesel fuel pipe 11: exhaust gas inlet

20: Soot Reduction Device

The present invention relates to a smoke reduction system for a low temperature exhaust vehicle installed in an exhaust passage of a diesel engine, and more particularly to burning particulate smoke by an oxidation catalyst unit and a catalyst for oxidizing organic matter and nitrogen oxides (NO) in exhaust gas. A catalyst filter part is provided sequentially from the upstream with respect to the flow of exhaust gas, and relates to a smoke reduction system for a low temperature exhaust vehicle having a catalytic combustion diesel injector having an electric heating catalyst part at the front end of the oxidation catalyst part.

In diesel engines, fuel injected into the engine burns due to self-ignition due to a rise in temperature due to compression of the piston. In this process, incomplete combustion occurs due to inhomogeneity of fuel and air, and at this time, harmful particulates (soot) such as unburned carbon are generated. This soot can cause serious illness in human body through breathing, and especially with the increase of diesel vehicles, it is becoming a social problem.

When a catalytic filter is used as a smoke reduction device, the smoke accumulated in the filter is removed by the coated catalyst for exhaust gas above a certain temperature, so that the filter can be naturally regenerated to some extent. If the driver experiences frequent idle conditions or does not take much load of the vehicle, the temperature of the exhaust gas is low, so that the natural regeneration of the filter is difficult even by the catalyst.

In the conventional smoke reduction apparatus of an exhaust gas vehicle, a method of collecting soot by a catalyst filter and oxidizing the collected soot by a catalyst at a temperature of exhaust gas above a certain temperature is applied. However, when the temperature of the exhaust gas is lower than the temperature at which the catalyst can act, it is difficult to oxidize the soot in the conventional soot reduction apparatus, and there is a forced regeneration method in which the exhaust gas and the catalyst filter are raised to a temperature at which the direct oxidation can be performed. As a method of raising the direct oxidation temperature to the soot oxidation temperature, there is a method of directly heating by means of electric heater heating and burner combustion.

The method of forcibly raising the exhaust gas temperature by installing an electric heater in front of the filter is known from Korean Patent Laid-Open Publication No. 2004-68792. Such a method is to obtain electrical energy for raising the temperature of the exhaust gas. In order to raise the temperature of the exhaust gas, a battery having a large capacity is required, but it is difficult to apply the battery practically.In the case of the burner continuous type, a burner is installed inside or outside the apparatus. Since the external air is supplied separately, the device is enlarged and complicated, so it is inferior in economic efficiency.

In another method, Korean Patent Laid-Open Publication No. 2003-3599 includes an injector for injecting fuel at a predetermined position on an exhaust flow path in which a smoke reduction device is installed, and an ignition means for igniting the fuel at an adjacent position of the injector. Although a device for igniting a furnace and forcibly raising the temperature is disclosed, the device is frequently clogged by a carbon component when repeatedly used, and it is difficult to achieve complete combustion because it is directly burned using a flame. Can increase the unburned soot, hydrocarbons and carbon monoxide, the burden of the filter at the same time increases, still requires a separate complicated device according to the installation of the ignition device, and also depending on the use of the hole of the ignition device This can lead to blockage and make the device unusable. Falls in the economy also has practical drawbacks are not likely to be difficult for long-term use.

Another method is to mix materials containing metals and metal oxides that can show catalytic performance in diesel fuel and post-inject the diesel fuel in the combustion chamber of the engine, which shows catalytic performance in diesel fuel. When a mixed fuel in which a substance is mixed is injected into an engine and the fuel and the fuel additive are burned together in the engine, metals and metal oxides that exhibit catalytic performance after combustion accumulate in the filter along with soot. The diesel fuel injected afterwards from the combustion chamber of the engine is transferred to the oxidation catalyst together with the exhaust gas to cause catalytic combustion. At this time, the temperature of the exhaust gas is increased by the heat of combustion. When the exhaust gas temperature rises, the fuel additive already accumulated in the filter acts as a catalyst and can be removed by catalytic combustion of soot. However, this method has a disadvantage in that the additives are continuously added to the fuel, and the additives are continuously accumulated in the filter, so that the filter needs to be cleaned.

Japanese Laid-Open Patent Publication No. 2005-69017 discloses a method for regenerating a filter by directly supplying combustible liquid fuel to the soot and organic matter captured by the catalyst filter as unburned human bodies. However, according to this method, when a large amount of liquid fuel is introduced to sufficiently raise the temperature of the catalyst filter, unburned hydrocarbons or carbon monoxide may be emitted into the atmosphere without being completely oxidized from the catalyst filter. In this case, the catalyst surface is covered by soot, which makes it difficult to effectively burn liquid fuel at low temperatures.

The system, also known as Continously Regenerating Trap (CRT), uses a ceramic wall-flow filter and installs an oxidation catalyst upstream of the wall-flow filter (NO _2). ), The particulate matter collected in the filter is continuously oxidized. Carbon, which is present in the form of soot, oxidizes with oxygen at a very high reaction rate at temperatures above 550 ℃. However, NO ₂ oxidizes above 250 ° C, much lower than this. This regeneration mechanism also occurs in catalyzed soot filtration systems with active noble metal catalysts, producing some NO ₂ to help filter regeneration, but all soot because NO ₂ generated in CRT systems is generated upstream of the filter. There is an advantage that can be used for the oxidation of). However, such a continuous regeneration method also has a problem that it is difficult to continuously maintain effective smoke reduction efficiency because it is greatly affected by the temperature of the exhaust gas, the sulfur content of the fuel, the NOx / PM ratio in the exhaust gas.

Meanwhile, Korean Patent Publication No. 1997-0001934 discloses an exhaust gas purifying apparatus including an electric heating catalyst (EHC) forcibly increasing the temperature of the exhaust gas at the front end of the catalytic converter, and in Korea Patent No. 300179 A nitrogen oxide reduction catalyst system including an electric heating catalyst (EHC) at a front end portion of an oxide occluding type catalyst or a three-way catalyst is disclosed. In addition, Korean Patent No. 309839 uses an electroheating catalyst (EHC) to remove HC desorbed at a high temperature at the rear end of the HC-Adsorber catalyst device. In addition, Korean Laid-Open Patent Publication No. 2004-68792 discloses a smoke reduction device that includes an electric heating unit at a front end of a particle removal filter to operate an electric heater to directly raise the exhaust gas. However, although the conventional EHC and electric heater are designed to directly raise the exhaust gas or to burn HC (hydrocarbon) in the exhaust gas by being installed in the exhaust gas passage, it is not possible to raise the entire exhaust gas by electric energy alone. There is not enough battery capacity.

Accordingly, the present inventors have invented a catalytic combustion diesel injector for utilizing the combustion heat of diesel as an energy source of exhaust gas temperature raising to solve the problems of the prior art and to effectively heat the exhaust gas. Catalytic combustion diesel injector according to the present invention is to have an electric heating catalyst inside the electric heating catalyst to heat the diesel injected into the exhaust gas by applying an electric heating catalyst (EHC) or an electric heating and combustion catalyst. There is no case in which the electric heating catalyst is applied to a diesel injector for injecting diesel into the exhaust gas, and the present invention has completed the smoke reduction device for effectively raising the temperature of the exhaust gas.

Accordingly, the present invention provides a smoke reduction device having a catalytic combustion diesel injector, so that the smoke reduction for low-temperature exhaust vehicles that can effectively reduce particulate matter even in low-temperature exhaust gas vehicles that can not be applied to conventional techniques known as continuous regeneration traps. The purpose is to provide a system.

In addition, the present invention can be freely injected and combusted even at low exhaust gas temperature is difficult to vaporize diesel, including the idle (Idle) state that diesel injection is difficult during vehicle operation, so that the injected diesel is converted into heat without waste to change the temperature of the exhaust gas It can raise a temperature effectively.

Accordingly, another object of the present invention is to provide a smoke reduction system for a low temperature exhaust vehicle using a catalytic combustion diesel injector having a high degree of freedom of diesel injection control and an electric heating catalyst capable of regenerating the catalyst filter with a small amount of diesel injection. have.

The present invention relates to a catalytic combustion diesel injector and a smoke reduction system comprising the same.

The catalytic combustion diesel injector according to the present invention is characterized by having an electric heating catalyst unlike the conventional diesel injector, and unlike the conventional diesel injector spraying and injecting diesel into the exhaust pipe, the catalytic combustion type according to the present invention. The diesel injector is characterized in that the sprayed diesel is catalytically burned through the electric heating catalyst part in the injector.

Existing electric heating catalyst (EHC) and electric heater type have to increase the temperature of the entire exhaust gas using only electric energy, so it is difficult to commercialize due to the limitation of battery capacity and high cost and complexity of power control device. The characteristics of the catalytic combustion diesel injector of the present invention are mainly to increase the temperature of the exhaust gas by using diesel combustion heat, and the electric heating catalyst heats its own electric heating catalyst and / or combustion catalyst with a small amount of electric energy so It acts as a catalytic combustion igniter to allow combustion.

The electric heating catalyst portion provided in the catalytic combustion diesel injector according to the present invention is an integral electric heating catalyst (EHC) portion in which both electric heating and catalytic combustion are performed at the same time, or an adjacent electric heating catalyst in which the electric heating portion and the combustion catalyst portion are arranged adjacent to each other. It may be a part, or may be a combined electric heating catalyst unit combined with the integrated electric heating catalyst and the combustion catalyst.

In addition, the present invention is provided with an oxidation catalyst unit for oxidizing organic matter and nitrogen oxides (NO) in the exhaust gas and a catalyst filter unit for burning particulate matter by a catalyst sequentially from upstream with respect to the flow of the exhaust gas. Provided is a smoke reduction system for a low temperature exhaust vehicle having a catalytic combustion diesel injector having an electric heating catalyst portion at its front end.

The catalyst combustion type diesel injector injects a high temperature diesel combustion gas generated by combustion of diesel fuel into the exhaust pipe to increase the exhaust gas, and the heated exhaust gas is transferred to the catalyst filter through an oxidation catalyst to catalyze the catalytic filter. By lowering the combustion temperature, particulate particulates can be effectively reduced at low temperatures.

The catalytic combustion diesel injector according to the present invention includes a diesel injection unit, an air injection unit, an injection nozzle, and an electric heating catalyst unit, and the diesel sprayed through the nozzle is heated and burned in the electric heating catalyst unit to produce high temperature diesel. It is characterized by generating a combustion gas.

The electric heating catalyst part is an integral electric heating catalyst (EHC) part in which both electric heating and catalytic combustion are performed simultaneously, or an electric heating catalyst part in which the electric heating part and the combustion catalyst part are arranged adjacent to each other, or the integral electric heating catalyst (EHC). ) And the combustion catalyst unit may be a combined electric heating catalyst unit. The integrated electric heating catalyst is commonly known as an EHC (Electrically Heated Catalyst), and a metal catalyst carrier is used as electric energy to reduce emissions of hydrocarbons (HC) and carbon monoxide (CO), which are contained in a large amount of exhaust gas in a gasoline vehicle. It has been applied to reduce HC and CO emissions by heating, and the conventional EHC has been used in the exhaust passage to reduce the CH, CO generated in a large amount of air-fuel ratio in gasoline vehicles. The EHC is a catalyst component coated on the metal support. When the metal support is electrically supplied, the EHC is heated by its resistance and the diesel is oxidized at a low temperature by the coated catalyst. However, the electric heating catalyst unit of the present invention is not limited thereto, and includes both an apparatus for allowing electric heating and catalytic combustion to be performed inside a diesel injector. Therefore, as described above, the electric heating unit and the combustion catalyst unit may be adjacent electric heating catalyst units arranged adjacent to each other, and the integrated electric heating catalyst unit and the combustion catalyst unit may be used to more efficiently burn the catalyst of the integrated electric heating catalyst unit. It may be a combined electric heating catalyst unit combined.

Therefore, in the present invention, the disadvantages of the conventional diesel injection injector using the catalytic combustion diesel injector having an electric heating catalyst selected from the integral electric heating catalyst (EHC), the adjacent electric heating catalyst or the composite electric heating catalyst. Was to solve. In the case of directly injecting diesel fuel in a smoke reduction apparatus having a conventional diesel injection injector, the exhaust gas may be oxidized by the temperature of the exhaust gas or the diesel may be oxidized by the oxidation catalyst, but the temperature of the exhaust gas may be increased. In order to raise the temperature sufficiently, a large amount of diesel must be injected, so that the injected diesel is not effectively oxidized to increase the amount of organic matter in the exhaust gas, thereby increasing the combustion capacity of the oxidation catalyst or the catalyst filter, thereby removing particulate matter. The exhaust gas that has passed through the catalytic filter can be reduced, and hydrocarbons and carbon monoxide produced by the incomplete combustion of diesel are mixed to release pollutants into the atmosphere, and the efficiency of regeneration is lowered due to insufficient combustion of the incompletely burned soot. This can happen.

In addition, in a vehicle having a low exhaust gas temperature applied in the present invention, when diesel is directly injected to the front end portion of the oxidation catalyst, diesel is hardly vaporized because it is injected at low temperature. Since the vaporization temperature of diesel is a mixture of various components, the temperature ranges from about 200 to 320 ° C. The temperature of the exhaust gas of a low-temperature exhaust gas vehicle is 250 ° C or lower. In this case, when diesel fuel is injected, only a part of the injected diesel is vaporized. And some are mixed with the exhaust gas in the liquid phase to enter the oxidation catalyst. At this time, the vaporized diesel can be uniformly mixed with the exhaust gas to enter the oxidation catalyst unit in a properly dispersed state, but the non-vaporized liquid diesel fuel is driven into the lower end of the oxidation catalyst unit due to the weight deviation. It is difficult to completely oxidize diesel by the oxidation catalyst, and unburned diesel or liquid diesel enters the catalytic filter part, so that regeneration of the catalyst filter is difficult to occur uniformly and smoothly.

The catalytic combustion diesel injector of the present invention invented to compensate for the disadvantages of the conventional diesel injection injector and to effectively heat up the exhaust gas has an electric heating catalyst so that the sprayed diesel is not sprayed directly on the exhaust passage. There is a big difference between allowing the diesel fuel of high temperature to be injected into the exhaust passage while being heated and burned while passing through the heating catalyst.

Among the electric heating catalyst parts, the integrated electric heating catalyst part uses a metal support coated with a catalyst on a high-temperature alloy, and when a current is applied by installing a (+) electrode and a (-) electrode therein, a sudden temperature is caused by its own resistance. The rise is made. The high temperature alloy may be an iron-chromium-aluminum alloy, a nickel-chromium alloy, or a nickel-chromium-aluminum alloy, but is not limited thereto. The metal support may be used in the form of honeycomb, mesh, foam or fiber. In addition, the catalyst coated on the metal support is preferably at least one catalyst component selected from platinum, palladium, rhodium, ruthenium, cobalt, manganese, nickel, copper, iron, and platinum (Pt), palladium (Pd) or ruthenium. In the case of using the precious metal component selected from (Ru), even when the temperature of the EHC is about 200 degrees, the injected diesel easily burns and can easily raise the temperature to 700 to 800 degrees, effectively increasing the temperature of the exhaust gas. It is more preferable because it is. If a catalyst-free metal support is used, the atomized diesel can be combusted at relatively high temperatures, causing problems with the electrical equipment including the electrodes, and the response time is also slowed down. . A carrier selected from alumina, silica, titania, zirconia, and the like may be used to effectively coat the catalyst component on a support, but is not limited thereto.

The adjoining type electric heating catalyst part is an electric heating part and a combustion catalyst part are arranged adjacent to each other, and the electric heating part is arranged at the upper end and the combustion catalyst part is arranged at the lower end with respect to the diesel injection direction. And catalytic combustion is performed by an adjacent combustion catalyst. The electric heating unit is made of a material of a high-temperature metal alloy such as an iron-chromium-aluminum alloy, a nickel-chromium alloy, or a nickel-chromium-aluminum alloy, and has a three-dimensional structure with a large surface area so that heat is effectively distributed and sprayed. It is preferable to allow the diesel to be effectively heated, and may be selected from the support of an open flow method selected from honeycomb, mesh, foam or fiber. However, the present invention is not limited thereto, and any means can be used as long as it can heat up the diesel diesel sprayed by electric ignition or heating, and a spark plug, a heating rod, or the like may be used.

In addition, the combustion catalyst is at least one metal catalyst component selected from platinum, palladium, rhodium, ruthenium, cobalt, manganese, nickel, copper, iron, or platinum, palladium, rhodium, ruthenium, cobalt, manganese, nickel on a ceramic support. The metal oxide catalyst component containing one or more metals selected from copper and iron may be coated or the metal catalyst component and the metal oxide catalyst component may be coated. The coated metal oxide may be perovskite or It may have a hexaaluminate crystal structure. In addition, the ceramic support may be selected from cordierite, SiC, alumina or lite.

The hybrid electric heating catalyst unit provided in the catalytic combustion diesel injector according to the present invention combines the adjacent electric heating catalyst unit and the combustion catalyst unit, and the electric heating catalyst unit adjacent to the upper end with respect to the diesel injection direction, and the combustion catalyst at the lower end. Allow the unit to be deployed. This has the advantage that the catalytic combustion is more activated by the combustion catalyst disposed at the lower end has the effect of more effectively burning the diesel to increase the temperature.

Catalytic combustion diesel injector according to the present invention can adjust the degree of combustion of the diesel by the flow rate of air with respect to the flow rate of the diesel flowing into the catalytic combustion diesel injector, that is, to adjust the degree of oxidation, EHC or combustion catalyst portion Depending on the type of catalyst supported, the degree of oxidation of diesel can be controlled. In order to completely inject the combustion gas oxidized diesel, it is more preferable to use a catalyst loaded with platinum (Pt) component, the flow rate ratio of the air to the injected diesel is preferably 8000 or more, partially oxidized diesel combustion gas In order to inject it, it is more preferable to use a palladium or ruthenium catalyst by reducing the flow rate of air, and the flow rate ratio of air to diesel is preferably about 2000 to 5000, but the temperature of the exhaust gas itself, the performance of the oxidation catalyst part, and the catalyst filter part The conditions can be changed according to the amount of particulate matter trapped in the.

 The catalytic combustion diesel injector used in the smoke reduction system of the present invention effectively injects high-temperature diesel combustion gas generated during the process in which the sprayed diesel is heated and combusted through the electric heating catalyst, so that the exhaust gas is effectively heated up and the heated exhaust gas is heated. Since the gas is transferred to the catalyst filter unit through the oxidation catalyst unit, the oxidation reaction efficiency of organic matter or NO of the oxidation catalyst is increased, and the regeneration process of removing particulate matter by combustion by the catalyst and oxygen of the catalyst filter is more effectively performed. The catalyst filter can be effectively regenerated even when the temperature of the exhaust gas is low.

The oxidation catalyst unit according to the present invention oxidizes organic matter in the exhaust gas to raise the exhaust gas, and oxidizes nitric oxide (NO) in the exhaust gas to generate nitrogen dioxide (NO ₂ ), which is collected in the catalyst filter by NO ₂ . It is possible to remove the particulate soot at a lower temperature. In the present invention, a high temperature diesel combustion gas is injected into the exhaust gas passage by a catalytic combustion diesel injector to heat up the exhaust gas and oxidize organic matter and nitrogen oxide in the exhaust gas at the oxidation catalyst unit. There is an advantage that the temperature of the gas is raised more effectively. In addition, even if some diesel is injected in the unburned state without being oxidized in the catalytic combustion diesel injector, it is possible to oxidize by the oxidation catalyst so that the exhaust gas can be heated up stably, thereby preventing the emission of unburned diesel as well as a small amount. The catalyst can also be regenerated using diesel. In the oxidation catalyst according to the present invention, it is preferable to use a platinum group component selected from platinum (Pt), palladium (Pd), rhodium (Rh) or iridium (Ir), and in cordierite, SiC, alumina or mullite It is preferable to use selected ceramic supports.

In the case of the exhaust gas reducing system, the catalyst combustion type diesel injector, the oxidation catalyst unit, and the catalyst filter unit are provided. In the state where the back pressure is not increased, the injection is stopped to convert NO to NO ₂ in the existing oxidation catalyst. The mechanism of oxidizing soot by NO ₂ can be applied, and when the constant back pressure rises, the exhaust gas is heated up by the hot diesel combustion gas injected from the catalytic combustion diesel injector, and the combustion catalyst is unburned. Since the organic matter in the exhaust gas or the exhaust gas can be oxidized to increase the exhaust gas temperature, the natural regeneration by NO ₂ occurs as compared with the soot regeneration device without the oxidation catalyst, and thus the frequency of injecting diesel is reduced. Relatively lower diesel consumption can increase the combustion efficiency of the soot. It is possible to maximize efficiency.

In addition, the present invention has the advantage of increasing the temperature of the exhaust gas in a fast response time, unlike the direct injection of diesel by regenerating the catalyst filter, that is, by burning the diesel inside the catalytic combustion diesel injector, the diesel is completely Even if it is injected without being burned, it is oxidized by an oxidation catalyst so that the injected diesel can be almost completely burned, so that unburned diesel is less likely to be transferred to the catalyst filter unit, and the catalyst filter unit can be effectively regenerated by the heated exhaust gas. Can be. In addition, a method of burning and injecting diesel is adopted, and since the temperature of the exhaust gas is raised even by the oxidation catalyst, the consumption of post-injected diesel is small, and fuel economy can be saved.

In addition, the catalyst filter unit according to the present invention includes a cordierite having excellent heat resistance, ceramics containing SiC, Ni alloys or FeCr alloys so that the material of the filter can be used safely even when the temperature is excessively increased during the regeneration of the filter. It is preferable to use an alloy. When such a high heat resistant material is used as a filter, even when particulate particulates (or soot) are accumulated in excess in the filter, it can operate stably against the high heat generated during regeneration, and excessive soot is generated. Since the amount of heat generated during oxidation can be used, the amount of diesel fuel injected can be saved.

1 illustrates an example of a catalyst filter in which Pt is supported on a heat resistant SiC filter, and illustrates oxidation rate (filter regeneration rate) of soot accumulated in the filter. When NO and O ₂ or NO, O ₂ , H ₂ O are introduced into the catalyst filter, as shown in FIG. 2, NO ₂ is generated on the catalyst, and soot is oxidized to CO ₂ by NO ₂ . At this time, the reaction temperature range shows the maximum conversion rate at 250 ~ 350 ° C. When the exhaust gas is often outside the temperature range because the temperature range is narrow, soot cannot be regenerated smoothly. On the other hand, when O ₂ is introduced into the reactant, as shown in FIG. 1, the maximum conversion rate is relatively higher than 500 ° C., but the reaction rate is very fast, and the higher the temperature, the higher the conversion rate. Therefore, as in the present invention, when diesel fuel is injected and catalytic combustion in the oxidation catalyst portion intentionally increases the temperature of the exhaust gas to about 500 degrees, even in a vehicle where it is difficult to regenerate the smoke, soot is rapidly generated by the oxidation reaction to O ₂ . Can play.

The present invention further comprises a distributor between the catalytic combustion diesel injector and the oxidation catalyst which can help the mixing of the hot diesel combustion gas and the exhaust gas injected from the catalytic combustion diesel injector to effectively remove particulate matter at low temperature. Can be.

The present invention includes a pressure sensor and a temperature sensor at the front end of the distributor or the oxidation catalyst unit, and a temperature sensor at the rear end of the catalyst filter unit.

In the present invention, the pressure sensor, the temperature sensor and the catalytic combustion diesel injector are electrically connected to a control unit, and the control unit has various engine operation information such as engine speed (RPM) input thereto. Therefore, the control unit controls the diesel injection timing, the diesel injection amount, and the operation of the electric supply device connected to the electric heating catalyst based on the temperature and pressure measured by the temperature sensor and the pressure sensor and the operation information of the engine. Done.

Hereinafter, the operation relationship of the reproducing apparatus that can effectively reproduce the smoke reduction system of the present invention will be described with reference to FIG.

Figure 3 shows an embodiment of the present invention, showing a low-temperature smoke reduction system connected to the exhaust pipe to which the exhaust gas flows.

The smoke reduction system is inserted into the exhaust gas passage of the diesel engine, and the exhaust gas inlet 11 of the front end portion of the smoke reduction device 20 connected to the exhaust pipe of the engine burns the diesel fuel and oxidizes the smoke reduction device. An oxidation catalyst unit which is formed adjacent to the catalytic combustion diesel injector 8 and the catalytic combustion diesel injector 8 that injects a high temperature diesel combustion gas into the front end of the catalyst part and catalytically burns organic matter and nitrogen oxides of the exhaust gas. 1), the catalytic filter unit (2) for burning the soot particles collected by the catalytic combustion process of the high-temperature diesel combustion gas and the oxidation catalyst unit (1) injected from the catalytic combustion diesel detector, catalytic combustion diesel It is composed of a diesel pump (9) for supplying fuel injected into the injector, a diesel pump (9) and a diesel fuel pipe (10) connected to an external diesel fuel storage tank (not shown).

The present invention also provides a pressure sensor (3) and a temperature sensor (4) inserted into one side of the front end of the oxidation catalyst of the smoke reduction device and the temperature sensor (7) installed at the rear end of the smoke reduction device and the pressure sensor and the temperature sensor It comprises a control unit (5) for storing information and storing information on the state of the engine to control the diesel fuel injection of the diesel pump.

In addition, the present invention is located at the front end of the oxidation catalyst, it may be further provided with a distributor (6) that can help the mixing of the hot diesel combustion gas and the exhaust gas injected from the catalytic combustion diesel injector.

The following describes the operation of the low temperature smoke reduction system of the present invention.

The pressure applied to the pressure sensor 3 installed at the front end of the smoke reduction device, which is connected to the exhaust pipe of the engine and located at a certain position of the smoke exhaust pipe, increases as the engine operation time passes by a filter for filtering particulate matter. When the value measured by the pressure sensor 3 exceeds the set value, the regeneration process is performed for combustion of the collected soot. Diesel and air are injected into the catalytic combustion diesel injector 8 and the nozzles inside the catalytic combustion diesel injector to combust the soot collected by the control unit 5 from the value and the set value of the pressure sensor. Diesel is sprayed with air at At this time, a current flows in the electric heating catalyst part and the temperature is raised to 200 degrees or more by its own resistance. The sprayed diesel is combusted by the catalytic action of the electric heating catalyst at a temperature of 200 degrees or more, and high combustion heat is generated during the combustion process, so that a high temperature diesel combustion gas is generated, and the high temperature combustion gas is injected into the exhaust passage to exhaust the exhaust gas. The temperature is raised. 4 shows a schematic cross-sectional view of the catalytic combustion diesel injector and the exhaust gas being heated by the catalytic combustion diesel injector. Referring to FIG. 4, the electroheating catalyst unit of the catalytic combustion diesel injector is a complex electroheating catalyst unit including an integral electroheating catalyst unit and a combustion catalyst unit, and the sprayed diesel is heated in the integral electroheating catalyst unit and partially catalytically burned. The combustion of diesel is performed by catalytic combustion in the subsequent combustion catalyst section, and the exhaust gas is heated up by injecting the same into the exhaust gas passage, and the heated exhaust gas is transferred to the oxidation catalyst section and the catalyst filter. The temperature raising effect and the NO ₂ formation effect work in combination, and the particulate particulates collected by the catalytic action of the catalyst filter are burned to effectively regenerate the catalyst filter.

The diesel injected into the catalytic combustion diesel injector 8 is supplied only when the catalyst filter is regenerated by the diesel pump 9, and the electric heating catalyst unit is supplied through an electric supply device connected to the electric heating catalyst at the same time as the diesel injection. Supply current to Once the temperature rises above 200 degrees and the combustion of diesel begins, the electricity supply is no longer supplied to the electric heating catalyst, so the electricity supply is stopped. In addition, although the regeneration degree of the catalyst filter can be grasped by measuring the pressure of the pressure sensor 3, the regeneration degree of the filter can be estimated according to the temperature rising degree of the temperature by measuring the temperature of the temperature sensor 7 at the rear end of the filter. . Therefore, the regeneration degree is controlled by adjusting the injection cycle and injection amount of diesel fuel required for the regeneration process according to the pressure, temperature and RPM measured during regeneration.

According to the present invention, when a large amount of particulate smoke does not accumulate in the catalyst filter, the catalyst filter is continuously regenerated by NO ₂ generated from an oxidation catalyst, and when the particulate smoke accumulates and the back pressure increases, the catalytic combustion diesel injector is applied. By rapidly oxidizing the diesel fuel is injected into the front end of the oxidation catalyst portion it is possible to quickly increase the exhaust gas has the advantage of removing the particulate matter accumulated in the catalyst filter in a short cycle.

The oxidation catalyst of the present invention serves to oxidize organic matter and nitrogen oxides in the exhaust gas and to continuously remove particulate matter from the catalyst filter, and to remove particulate matter accumulated in a large amount from the catalytic combustion diesel injector. In the case of injecting a high temperature diesel combustion gas generated while the diesel is combusted, the oxidation catalyst portion plays a role of effectively raising the exhaust gas by burning organic materials in the diesel and exhaust gas which can be unburned and injected.

The following describes the technology of the present invention in more detail from the examples of the present invention, and is not limited only to the following examples of the present invention.

[Production example]

As shown in FIG. 4, a catalytic combustion diesel injector having a composite electric heating catalyst part including an integral electric heating catalyst (EHC) part and a combustion catalyst part was manufactured.

Manufacture of integrated electrothermal catalyst (EHC) unit

A corrugated FeCrAl alloy plate (FeCrAlloy) and a flat FeCrAl alloy plate are rolled together to form a metal honeycomb support having a diameter of about 4 cm, and a FeCrAl alloy rod having a diameter of about 2 mm is welded to the center and the outside of the support. It was designed to supply current. This was heat-treated at 900 degrees for about 5 hours to precipitate alumina on the metal surface. The support thus prepared was impregnated in 5% palladium nitrate solution, followed by air-blowing, which was dried at 120 degrees for 2 hours and calcined at 850 degrees for 4 hours to produce the final EHC. .

Manufacture of combustion catalyst

Gamma alumina powder [SASOL, Germany, surface area: 210m ² / gr, pore volume: 0.5cc / gr, specific gravity: 0.8g / cc], acetic acid and secondary distilled water were mixed, and then pulverized using a wet ball mill for 24 hours. A homogeneous alumina slurry was prepared. The average particle size of the alumina ground through a wet ball mill was adjusted to 2 to 8 micrometers.

A cordierite honeycomb having a diameter of 4 cm, a height of 1.5 cm, and a cell density of 400 cpsi was prepared, impregnated in the alumina slurry prepared above, and then air-blowed, which was dried at 120 degrees for 2 hours and dried at 850 degrees. The mixture was calcined for 4 hours to 2.0 g / in ³ . After impregnating 5% palladium nitrate (Palladium Nitrate) solution, the air is blown (Air-Blowing), it is dried for 2 hours at 120 degrees and 4 hours at 800 degrees and finally 4wt% Pd / Al ₂ O ₃ A honeycomb combustion catalyst coated with a catalyst was prepared.

EXAMPLE

Smoke reduction device equipped with catalytic combustion injector

The exhaust gas temperature rise by the catalytic combustion injector was evaluated using the system mounted as shown in FIG. 3.

Catalytic combustion injector is a catalytic combustion type having a composite electric heating catalyst portion arranged sequentially adjacent to the injection direction of diesel as the integral electrothermal catalyst (EHC) and the combustion catalyst prepared as shown in Figure 4 Injectors were used. The injected diesel and air are mixed and the diesel injected through the injection nozzle is first heated up and combusted in the EHC, and the combustion reaction by the catalyst in the adjacent combustion catalyst is more activated to effectively raise and burn the diesel.

<Evaluation conditions>

Engine dynamometer experiment (Santa Fe engine)

EHC Power injection method: 2 series 12V battery for vehicle connection

Voltage and current 24.9 V, 25 A

Air injection rate: 30L / min

<Evaluation details>

Initially, the engine was driven at 1200 RPM with a torque of 0. Before the diesel injection, power and air were supplied to the integrated electrothermal catalyst (EHC) unit of the catalytic combustion injector about 30 seconds in advance. The exhaust gas temperature was measured about 20 cm away from the diesel inlet. Subsequently, when diesel was supplied at 7cc / min per minute, the exhaust gas temperature rose rapidly above 500 degrees, and the injection was stopped to protect the EHC and the combustion catalyst. Afterwards, when the injection amount of diesel injection at 4cc / min as shown in Figure 5 it was confirmed that the exhaust gas temperature is raised to about 400 degrees to maintain a stable. Afterwards, the exhaust gas flow rate was increased by increasing the RPM to 1700. When diesel injection was performed at the same time as 4cc / min, the exhaust gas temperature was stably increased at about 300 degrees. Also, even when the EHC was turned off under the same conditions, the temperature of the exhaust gas following diesel injection showed an elevated temperature of about 300 degrees. This is because the temperature of the combustion catalyst was increased by the calorific value generated in the previous experiment even after the power supply was turned off, and it was maintained at a temperature where the catalytic combustion reaction could not easily be cooled after a certain time.

From the results of this embodiment, the EHC confirmed that the combustion reaction in the lower combustion catalyst portion through the electric heating to increase the temperature of the exhaust gas by combusting diesel, the EHC and the lower combustion catalyst portion DPF temperature of the low temperature exhaust gas It was confirmed that the temperature can be raised sufficiently to allow the regeneration of.

The smoke reduction system of the present invention provides an apparatus capable of effectively removing accumulated particulate smoke even in a vehicle having a low exhaust gas temperature through catalytic combustion. That is, the present invention relates to a smoke reduction system for effectively regenerating a catalyst filter using a catalytic combustion diesel injector having an electric heating catalyst. The catalytic combustion diesel injection injector of the present invention includes an electric heating catalyst therein. By injecting the hot diesel combustion gas generated by burning the sprayed diesel gas through the EHC to the front end of the oxidation catalyst part, there is no problem of unburned diesel emission, and the exhaust gas is sufficiently heated even with a small amount of diesel. There is an advantage that can improve the fuel economy.

In addition, when the particulate smoke is not accumulated in the catalyst filter part, the catalyst filter is continuously regenerated by NO ₂ generated from the oxidation catalyst part, and when the particulate smoke is accumulated and the back pressure increases. By oxidizing the diesel fuel rapidly by the catalytic combustion diesel injector and injecting it into the front end of the oxidation catalyst unit, the exhaust gas can be quickly heated up, thereby eliminating the soot particles accumulated in the catalyst filter in a short cycle.

Claims (9)

In the smoke reduction system for low temperature exhaust vehicle installed in the exhaust passage of the diesel engine, An oxidation catalyst unit for oxidizing organic matter and nitrogen oxides (NO) in the exhaust gas and a catalyst filter unit for burning particulate matter by the catalyst are sequentially provided from the upstream with respect to the flow of the exhaust gas, and electrically heated at the front end of the oxidation catalyst unit. A smoke reduction system for a low temperature exhaust vehicle having a catalytic combustion diesel injector having a catalyst unit. The method of claim 1, The catalytic combustion diesel injector includes a diesel injection unit, an air injection unit, an injection nozzle, an electric heating catalyst unit, and the diesel sprayed through the nozzle is heated and burned in the electric heating catalyst unit to generate a high temperature diesel combustion gas. A smoke reduction system for low temperature exhaust vehicles. The method of claim 2, The electric heating catalyst part is an integral electric heating catalyst (EHC) part in which both electric heating and catalytic combustion are performed simultaneously, or an electric heating catalyst part in which an electric heating part and a combustion catalyst part are arranged adjacent to each other, or the integral electric heating catalyst part and A smoke reduction system for a low-temperature exhaust vehicle, characterized in that a combined type electric heating catalyst unit combined with a combustion catalyst unit. The method of claim 3, wherein The integrated electric heating catalyst part is a low-temperature exhaust vehicle smoke reduction system, characterized in that the coating of at least one catalyst component selected from platinum, palladium, rhodium, ruthenium, cobalt, manganese, nickel, copper, iron on a high-temperature metal alloy support . The method of claim 4, wherein The support is a soot for low-temperature exhaust vehicles, characterized in that the metal alloy support selected from iron-chromium-aluminum alloy, nickel-chromium alloy or nickel-chromium-aluminum alloy in the form selected from honeycomb, mesh, foam or fiber. Abatement system. The method of claim 3, wherein The electric heating unit is a smoke reduction system for a low-temperature exhaust vehicle, characterized in that made of a high-temperature metal alloy support of the open flow method. The method of claim 3, wherein The combustion catalyst unit is at least one metal catalyst component selected from platinum, palladium, rhodium, ruthenium, cobalt, manganese, nickel, copper, iron on a ceramic support selected from cordierite, SiC, alumina or murite, the metal catalyst A smoke reduction system for a low-temperature exhaust vehicle, characterized in that the metal oxide catalyst component or a mixture thereof containing one or more of the components is coated. The method of claim 1, The catalyst filter is a smoke reduction system for a low-temperature exhaust vehicle, characterized in that it uses cordierite, ceramics containing SiC, alloys containing Ni alloy or FeCr alloy. The compound according to any one of claims 1 to 8, wherein The smoke reduction system includes a temperature sensor provided at the front end and the rear end of the catalyst filter, a pressure sensor provided at the front end of the catalyst filter, and the diesel of the catalytic combustion diesel injector by monitoring the pressure, temperature and engine speed (RPM). A smoke reduction system for a low temperature exhaust vehicle having a control unit that controls an injection timing, a diesel injection amount, an air injection amount, and an electric supply device connected to an electric heating catalyst unit.

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