KR200404748Y1 - Exhaust gas heating device for internal-combustion engine in air-suction type - Google Patents

Abstract

The present invention relates to an internal combustion engine exhaust gas heating apparatus required for heating the exhaust gas purifying apparatus of an internal combustion engine that drives DME which is LPG, LNG, gasoline, diesel, or oxygenated hydrocarbons as a raw material, the housing of the tube; The combustion reforming catalyst is filled in the housing so as to burn / reform exhaust gas, an electrothermal heater is installed at an introduction of the catalytic reactor, and a fuel preheating line is connected to the outside of the housing to supply fuel. A catalytic reactor having an expansion cone for inducing exhaust gas for supplying exhaust gas to the catalytic reactor; And a mixer installed at a rear end of the catalytic reactor to mix the combustion reformed gas discharged from the catalytic reactor and the exhaust gas flowing between the catalytic reactor and the housing, wherein the catalytic reactor has an internal combustion engine exhaust gas heating having heat radiating means. Device.

Description

Exhaust gas heating device for internal-combustion engine in air-suction type

The present invention relates to an internal combustion engine exhaust gas heating apparatus, and more particularly, to the internal combustion engine exhaust gas required for heating the exhaust gas purifier of an internal combustion engine driven by DME which is LPG, LNG, gasoline, diesel, or oxygenated hydrocarbons as a raw material. It relates to a heating device.

Hydrogen-powered internal combustion engines produce nitrogen oxides and particulate matter, and environmental pollution is increasing day by day as vehicles increase.

In particular, diesel vehicles are emphasized in importance because they have less CO ₂ emissions than gasoline vehicles.

However, in the case of diesel vehicles, the amount of nitrogen oxides is increased because the partial pressure of oxygen is maintained to improve combustion efficiency.

In addition, there are many disadvantages in the generation of particulate matter, which acts as a major pollutant in urban areas.

In order to solve the above problems, researches are being conducted in various angles, and in particular, researches on particulate matter removal filters and nitrogen oxide removal catalysts are being promoted.

At this time, as a key point, hydrocarbons are supplied as filter heating fuel and / or reducing agent for removing nitrogen oxides at the same time, but the exhaust gas temperature varies depending on the driving conditions of the vehicle, and it is difficult to maintain the conditions for burning the hydrocarbons themselves. Therefore, it is selectively applied to vehicles that satisfy the operating route or exhaust gas exhaust temperature conditions.

However, when the hydrocarbon, which is a fuel, is reformed into a reducing gas in the form of combustion and / or synthesis gas (hydrogen, carbon monoxide) and lower hydrocarbon, the purification apparatus is used regardless of the exhaust gas temperature conditions when used as a filter (DPF) heating or nitrogen oxide reducing agent. Can function.

Although many studies have been conducted on the synthesis of hydrocarbons through catalytic combustion / reformation, they are still in an incomplete stage for heating exhaust gas of internal combustion engines.

Currently, a method of utilizing combustion heat by burning electricity or hydrocarbons supplied from a battery as a heating energy in a burner is attempted.

However, these devices are an unfinished stage due to the limited power available or the space required for installing an external burner, which is an obstacle to the practical use of automotive aftertreatment systems.

Although a number of conceptual patents have been filed to form a reducing gas through heating and / or reforming the exhaust gas by supplying hydrocarbons in the exhaust gas, it does not present a specific system configuration necessary for its combustion / reformation.

In the case of injection of hydrocarbons into the exhaust gas, a separate exhaust gas heater is required to suppress condensation at low temperatures below the diesel oil BP.

As a method to compensate for this, a combustion method using DOC has also been published, which is converted into a vapor by using an evaporator using electricity and mixed in the exhaust gas. However, this also serves as a limitation for the applied vehicle because the DOC temperature is less than 235, it is impossible to combust the vaporized diesel and to prepare for the recondensation of the vaporized fuel.

1 is a general configuration diagram of a DPF heating by fuel injection, and supplies a fuel for assisting combustion to the exhaust gas from the engine 10 and mixes the exhaust gas with DOC (Diesel Oxidize Catalyst). Inputted to (11), the exhaust gas and the fuel are oxidized in the DOC 11 to generate heat, thereby supplying a heat source that the DPF (Diesel Particulate Matter Filter) 12 can reproduce.

The DOC 11 burns carbon monoxide, hydrocarbons, and soluble organic matter (SOF) in the exhaust gas and fuel supplied for heating the DPF.

The DPF 12 has a configuration arranged in series at the rear end of the diesel oxidation catalyst (DOC), and serves to reduce the particulate matter of the exhaust gas finally discharged by collecting particulate matter from the diesel engine in the filter, PM If this amount is collected over a certain amount, the PM is burned and regenerated by an external supply heat source. In FIG. 1, heat generated from the DOC 11 is used.

FIG. 2 further includes a fuel evaporator 21 compared to FIG. 1, and the evaporator 21 vaporizes and supplies fuel to the exhaust gas to improve mixing with the exhaust gas, thereby improving DOC 22. It serves to facilitate the oxidation process in.

The exhaust gas of the internal combustion engine, in particular in the case of diesel vehicles, collects particulate matter into a filter (metal or ceramic material) and continuously oxidizes or / or periodically burns at the same time to regenerate the filter. The regeneration period of the filter has fluidity according to the temperature distribution NO / soot ratio of the exhaust gas. The temperature of the exhaust gas has dependence on the vehicle model, aging condition, road conditions, and traffic congestion, and the ratio of NO / soot is also variable according to the EGR ratio.

In other words, in order to adjust the temperature of the exhaust gas in consideration of the performance of the after-treatment device, it is impossible to change the operating conditions of the engine, and there is a need for an independent heating system for heating the exhaust gas as needed.

In addition, a small reforming reactor is placed in the exhaust gas pipe to partially oxidize a part of the fuel, so that the DPF can be regenerated independently of the operating conditions of the vehicle. There is a disadvantage in that the provision of means for supplying air from the outside using.

An object of the present invention devised to solve the above problems is to burn a portion of hydrocarbons for driving an internal combustion engine in exhaust gas so that a DPF or / or a De-NOX aftertreatment device can function at the same time. It is to provide a gas heater.

Still another object of the present invention is to provide a catalytic combustion of a portion of the fuel in the exhaust pipe to heat the exhaust gas or at the same time to produce a synthesis gas (mixture of H ₂ and CO) which can be burned even at a low temperature of less than 100 ° C. An object of the present invention is to provide an internal combustion engine exhaust gas heating apparatus capable of securing thermal stability to reaction heat in application. In particular, it provides a system that eliminates the need for a separate accessory by utilizing the exhaust gas of the engine as a source of air required for the partial oxidation reaction.

The present invention for achieving the above object, the housing of the tube; The combustion reforming catalyst is filled in the housing so as to burn / reform exhaust gas, an electrothermal heater is installed at an introduction of the catalytic reactor, and a fuel preheating line is connected to the outside of the housing to supply fuel. A catalytic reactor equipped with an induction cone for supplying a part of the exhaust gas to the catalytic reactor; A combustion catalyst for burning the reducing gas and the fuel discharged from the reforming reactor is installed; An internal combustion engine exhaust gas heating apparatus including a mixer for mixing the combustion reformed gas discharged to the rear end of the combustion catalyst and the exhaust gas flowing between the catalytic reactor and the housing.

The heating apparatus is characterized in that a part of the exhaust gas is supplied to the catalytic reactor by using the expansion cone for induction of the exhaust gas in the inlet portion of the catalytic reactor is utilized as an oxidant.

The fuel preheating line is characterized in that it is installed to pass through the rear end of the catalytic reactor or the catalyst bed.

In addition, it is characterized in that the response time of the system is shortened by activating the secondary combustion catalyst layer by rapid heating using the high temperature reformed gas discharged from the catalytic reactor and burning the reformed gas by the catalyst thereof.

Still another object of the present invention is to provide a reduction gas producing apparatus for removing nitrogen oxides, including a reducing gas for removing nitrogen oxides from a predetermined gas, including the internal combustion engine exhaust gas heating apparatus.

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

In the present invention, the reforming reactor is located inside the exhaust gas, so that a part of the exhaust gas is used as an oxidant, and a heating system excluding a separate air supply device is constructed and the heating of the DPF by the generated heat thereof and the De-NO _X not shown in the drawing Heating of the catalyst or NO _X trap can be carried out.

3 is a configuration diagram of a DPF heating system according to an embodiment of the present invention, in place of a fuel supply method in FIG. 1 or 2, a combustion reformer 1100 is installed.

The fuel required for combustion may utilize fuel mounted in a vehicle or a separate hydrocarbon, and air, which is an oxidant, uses part of exhaust gas.

The combustion reformer 1100 of the present invention includes an exhaust gas suction cone 600, a catalytic reactor 500, a catalytic heater 170, a reformed gas combustion catalyst 800, a secondary fuel supply nozzle 320, and combustion gas. And a housing 100 including an exhaust gas mixer 200 and an exhaust gas moving space to form an independent component for performing exhaust gas heating.

The shape of the exhaust gas suction cone 600 is not particularly limited, but the cross-sectional area of the inlet is in the range of 30-90% of the housing 100. When the cross-sectional area of the suction cone is too small compared to the housing, the oxidation reaction cannot proceed sufficiently because the total amount of the exhaust gas flowing into the reactor 500 is small. On the contrary, when the cross-sectional area of the suction cone is increased to 90% or more, the suction amount of the exhaust gas is increased. Because of this too much, starting at low temperatures is impossible when the heater 170 capacity is insufficient at startup. In addition, the influence on the flow of the exhaust gas is increased, resulting in lower fuel consumption.

Although the shape of the catalytic reactor 500 is not limited, as shown in FIG. 4, the cross-sectional area of the inlet 700 into which the exhaust gas and the fuel are introduced may be configured to reform the exhaust gas and the fuel by the combustion reforming catalyst 510. It is preferable to install smaller than the cross-sectional area of the reaction section because it can reduce the power consumption of the electric heater for ignition.

The outer wall of the catalytic reactor 500 is formed of a heat transfer plate 540 having a good thermal conductivity.

When the cross-sectional ratio of the introduction portion 700 and the reaction portion is maintained in the range of 0.1 to 0.9, the ignition is quick and the slip of unburned hydrocarbon can be minimized.

Accordingly, the above-mentioned catalytic reactor has a shape in which two tubular bodies having different diameters have a tapered connection portion, which is roughly in the form of a funnel.

Since the catalytic reactor 500 used in the present invention can proceed with ignition through local heating, regardless of the operating conditions of the vehicle, the reforming system 1100 is started even in the engine idle state (exhaust gas temperature 100 ° C.) It supplies a reducing agent for heating and removing nitrogen oxides.

In particular, in the preferred reactor type 500, the advantage that can be obtained when the reforming proceeds at a high temperature (above 700 ℃) conditions in a small volume, a separate evaporator or injection nozzle when supplying gas to the reactor is unnecessary and liquid Even if it is supplied as a rapid reforming reaction with evaporation by high temperature, it is possible to completely exclude the accumulation of high-boiling hydrocarbons up to 350-480 ° C contained in diesel (less than 5% by weight).

In addition, since the reaction rate is very fast at a high temperature due to the nature of the reforming catalyst, the space velocity of the reactant can be kept very high (200,000 / hr or more), thereby minimizing the amount of precious metal as the reforming catalyst.

An electrothermal heater 170 is installed at the introduction portion 700 of the catalytic reactor 500, and the electrothermal heater 170 is inserted into an electrothermal heater connector 130 installed at a wall of the housing 100. It is connected to the 140, and is supplied with power by the power supply line 150 penetrates the electric heater connector 140.

Fuel supplied from the outside passes through the housing 100 and is naturally preheated by the exhaust gas in the fuel preheating line 300 and the heat generated from the catalytic reactor 500 before being supplied to the inlet 700.

Therefore, the fuel preheating line 300 is installed at the rear end of the catalytic reactor 500 and is bent several times inside the housing 100 to increase the heat exchange efficiency.

The combustion catalyst 800 is positioned in the range of 5-100 mm at the rear end of the reforming reactor so that the combustion catalyst 800 can be quickly heated and activated by the reforming gas discharged from the catalytic reactor 500. In addition, the form of the catalyst is preferably a form in which the oxidation catalyst is coated on a honeycomb having a density of 100-300 cells. When the distance between the reforming reactor and the catalyst is close to 5 mm or less, since the mixing degree of the reformed gas and the exhaust gas discharged from the reactor is low, there is a problem that the heating effect is low because the oxygen required for combustion is small. On the other hand, if the distance is maintained at 100mm or more, the mixing amount of the reformed gas and the exhaust gas may be increased so much that the temperature may be raised to the temperature at which the catalyst is lost. This phenomenon may also occur depending on the cell density of the monolith coated with the oxidation catalyst. When the cell density of the monolith is 100 or less, the reaction between the reactants mixed with the air and the catalyst is not smooth, and thus the combustion cannot proceed. In addition, when the cell density of the monolith is 300 or more, the movement of the reformed gas is suppressed by the monolith, so that the mixing with the exhaust gas becomes too large and the local heat generation proceeds. When following this configuration, in order to increase the capacity of the fuel reformer 500, the particle size of the suction cone 600 for receiving a large amount of exhaust gas can be reduced, thereby reducing fuel consumption.

The secondary fuel supply nozzle 320 is installed at the rear end of the combustion catalyst 800, and since the reducing gas generated in the reforming reactor 500 is formed by the combustion catalyst, the hot gas is used to generate additional hydrocarbons. Configured to proceed with the supply. Accordingly, even if the capacity of the reforming reactor 500 is small, a large amount of fuel can be supplied. However, the supply time of the secondary fuel includes an ECU operation logic to proceed when T3 reaches 250 ° C or more.

The mixer 200 is installed at the lower end of the housing 100 and serves to mix the reformed gas and the exhaust gas that does not pass through the catalytic reactor, so that a uniform fuel concentration and a gas temperature are provided in the DOC to combust the reformed gas. To maintain DOC loss.

As shown in FIG. 4, a suitable form of the mixer 200 for mixing the gas discharged from the post combustion catalyst 800 and the gas passing through the outside of the catalytic reactor 500 mixes each gas at a short distance by giving a rotational force to each gas. The helical form is preferred so that it can be.

Combustion reforming catalyst 510 is not particularly limited and can be used for both known combustion catalysts and reforming catalysts. Combustion catalyst 600 also has no particular limitations and is preferably in the form of a noble metal catalyst that exhibits a completely combustible performance without coke generation in the state of oxygen deficiency.

The composition and production method of the combustion catalyst and the reforming catalyst of the combustion reforming catalyst 510 used in the present invention are as follows.

First, the combustion catalyst was described, and platinum was used as an active ingredient, and alumina was used as the support. Prior to supporting the precious metal as an active metal, cerium nitrate (Ce (NO ₃ ) ₂ .xH ₂ O, Aldrich product) was dried and dried in 3-5 mm granular activated alumina (gamma-Al ₂ O ₃ , product manufactured by Canto). 105, 24 hours), and then calcined at 1300 ° C. for 12 hours. Platinum chloride (H ₂ PtCl ₆ .xH ₂ O, manufactured by HanGold Gold Co., Ltd.) was dissolved in distilled water on the completed composite support to carry an active metal. Each precursor was added to include 10% by weight of cerium and 0.2% by weight of platinum based on the total weight of the support. After supporting platinum, drying (105 ° C., 24 hours) and firing (1000 ° C., 24 hours) were completed (Pt / Ce / Al ₂ O ₃ ).

The reforming catalyst was also prepared in the same order as the combustion catalyst (Rh / Mg / Al ₂ O ₃ ). However, cerium was replaced with magnesium with a precursor (Mg (NO ₃ ) ₂ .xH ₂ O, manufactured by Aldrich), and platinum was replaced with a rhodium precursor (RhCl ₃ .xH ₂ O, manufactured by Kojima).

Combustion catalyst 600 was used to process the Pt / Ce / Al ₂ O ₃ catalyst prepared in the above into a powder and slurry and coated on 200 cell density cordierite honeycomb (Pt / Ce / Al ₂ O ₃ / monolith).

Partial oxidation according to Scheme 2 carried out by the present invention has the advantage that the temperature of the catalytic reactor is naturally heated according to the initiation of the reaction as an exothermic reaction.

Scheme 1

Therefore, when the cross-sectional area of the cone 600 for introducing a part of the exhaust gas into the catalytic reactor 500 is configured to be larger than 80% of the housing 100, the amount of heat generated can be increased while passing through the reactor. Since the air volume of the exhaust gas is increased, the cooling effect of the heater is increased to increase the heater capacity.

Since the air intake pipe is installed, it interferes with the movement of the exhaust gas, so a bypass pipe (not shown in the drawing) is installed to control the amount of exhaust gas flowing into the exhaust gas heater 1100, so that the initial startup and the exhaust gas are not heated. It is also possible to reduce the fuel consumption by minimizing the influence on the gas flow. However, there is a need to take the disadvantage of complicated system configuration.

There is no particular limitation on the form or material properties of the DPF, which is a heating element, by heating the exhaust gas using the catalytic combustion device according to the present invention. It can be applied to various types of filters, such as monolithic, foamy, and granular, composed of ceramic, metal, SiC, or SiN. However, at least 900 ℃ of heat resistance is required because the filter can be locally overheated by the combustion of the collected soot. In addition, a method of lowering the operating temperature through the coating of a noble metal oxide catalyst or a nitrogen occluding metal may also be used in the filter thereof.

The main measuring positions and items for operating the DPF heating system according to the present invention are as follows.

-Differential pressure before and after DPF (△ P)

-Exhaust gas temperature (T1) flowing into the catalytic combustor

-Catalytic combustion exhaust gas temperature (T2)

-Exhaust gas temperature at the DOC inlet (T3)

-Exhaust gas temperature at the DPF outlet (T4)

In the differential pressure monitoring of the DPF, when the pressure loss is detected above the reference value due to the increase in the amount of particulate matter collected, the igniter is supplied with power to heat the combustion catalyst.

At this time, if the temperature of T1 is more than 350 ℃ power supply process can be omitted. The power is supplied and fueled for a time for the temperature of the catalyst surface to reach 350 ° C. or more.

When the temperature of T2 is discharged above 300 ℃, the power supply to the heater is stopped.

The regeneration of the filter is performed by supplying fuel until the differential pressure DELTA P of the filter becomes lower than the reference value.

However, even when the differential pressure does not reach below the reference value, when the rear end temperature (T2) of the catalytic combustor 500 reaches 900 ° C. or more, the supply of fuel is reduced to satisfy the condition of 900 ° C. or less, thereby regenerating the filter 3000. Conduct.

The ECU also includes a safety mode in which the supply of fuel is adjusted so that the temperature T4 of the filter outlet does not reach 650 ° C. or more (variable according to the heat resistance of the DPF) to prevent loss of the filter.

In addition, immediately after the start of the heating apparatus 1100, the ECU also includes a function of limiting the upper limit of the supply amount of fuel when T3 is 250 ° C or less in order to suppress hydrocarbon slip of the DOC 2000 even when the temperature of the DPF is low.

The internal combustion engine exhaust gas heating apparatus according to the present invention can be used for reducing gas of nitrogen oxides depending on the fuel to be supplied.

The reactor maintains the ratio of oxygen to fuel required for the combustion reaction (Equation 4) at the start of the reactor to rapidly heat the catalyst, and when the temperature of the exhaust gas rises above 500 ° C, the center or high temperature of the catalytic reactor 500 It is also possible to configure and operate the system in the form of shortening the heating time of the DPF by supplying the secondary fuel to the combustion gas discharge part of the fuel cell to vaporize the liquid fuel.

Hereinafter, the experimental results of the internal combustion engine exhaust gas heating apparatus according to the present invention will be described in detail.

Example 1

The air suction pipe was made to have a circular funnel having a diameter of 60 mm and having 70% of the housing cross-sectional area. The reactor 500 was manufactured such that the portion in which the electric heater was embedded was 12 mm in diameter and the inner diameter of the extension was 23 mm in length and 35 mm in length.

15 ml of the reforming catalyst described above was charged to the catalytic reactor 500. Assembled catalytic reactor 500 was completed by mounting inside the housing 100 of diameter 75mm, length 200mm.

Air was heated to an arbitrary temperature (100 ° C., 175 ° C.) using an air heater to supply the catalyst heater 1100 at a flow rate of 75 Nm 3 / hr. The fuel combustion air of the reactor 500 is a type in which some air supplied to the housing is sucked in and used, and the diesel oil is supplied from the outside by using a pump in the same position as the heater.

After the temperature of each part of the reactor reached the steady state, DC 12V power was supplied for 1 minute, and diesel oil (ULSD) was supplied at 0.5 ml / min. The power supply was stopped when the temperature of T2 reached 250 ° C. One minute was maintained such that the afterburner temperature (T2) and the after temperature of DOC (2000) reached steady state, and the amount of diesel oil was gradually increased in the range of 1.0-17 ml / min.

Accordingly, the temperature of DOC 2000 inlet and outlet is as shown in FIG. According to the temperature of the air supplied to the reactor (1100), there is a difference in the rear end temperature of the DOC, but independent of the temperature of the supplied air it can be heated up to 550 ℃ required for PM combustion. In this regard, it was evaluated as a system capable of producing a heat source capable of heating the DPF regardless of the exhaust gas temperature.

By using the above-described internal combustion engine exhaust gas heating apparatus, it is possible to configure a reducing gas producing apparatus for removing nitrogen oxides, which produces a reducing gas for removing nitrogen oxides from a predetermined gas.

The present invention is not limited to the above-described specific preferred embodiment, and any person having ordinary skill in the art to which the present invention pertains may make various modifications without departing from the gist of the present invention claimed in the claims. Of course, such changes will fall within the scope of the claims.

By providing the combustion reformer for heating the exhaust gas of the present invention, it is possible to regenerate the DPF independently of the driving state of the vehicle.

Therefore, it is possible to apply the DPF to the DPF dissemination project, in particular, to a small-sized vehicle having a low exhaust gas temperature as well as a bus that runs in the city center.

In addition, the provision of a supply device for reducing gas that can be used as a reducing agent for nitrogen oxides is expected to be utilized as a system necessary for the completion of a post-treatment system that can comply with Euro V regulations in the future.

1 is a block diagram of a DPF heating system using a conventional fuel injection

2 is a block diagram of a DPF heating system using a fuel evaporator of the prior art

3 is a block diagram of a DPF heating system according to the present invention

4 is a configuration example of the present invention

5 is a DOC heating test results using the reformed gas

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

10,20,30: Engine 11,22,2000: DOC

12,23, 3000: DPF 21: Evaporator

40: differential pressure sensor 100: housing

130: heater connector 140: electric heater connector

150: power supply line 170: electric heater

200: mixer 300: fuel preheating line

320: secondary fuel supply nozzle 500: catalytic reactor

510: combustion reforming catalyst 540: heat transfer plate

550: catalyst support plate 700: introduction

800: combustion catalyst 1100: combustion reformer

2000: DOC

Claims (6)

Housing of tubular body; A combustion reforming catalyst is filled in the housing to combust / reform exhaust gas, a gas induction cone for introducing exhaust gas into the catalytic reactor is installed, and an electrothermal heater is installed in the introduction portion of the catalytic reactor. A catalytic reactor having a fuel preheating line connected to the outside of the housing to supply fuel; A heating apparatus installed at a rear end of the catalytic reactor and equipped with a combustion catalyst for combusting a mixed combustible material of combustion reformed gas discharged from the catalytic reactor and exhaust gas flowing between the catalytic reactor and the housing; And And a mixer installed at a rear end of the catalytic reactor and mixing a combustion gas passing through the combustion catalyst and exhaust gas flowing between the catalytic reactor and the housing. 2. The exhaust gas heating apparatus of claim 1, wherein the cross-sectional area of the exhaust gas inducing cone is 30-80% of the reactor housing (100). The exhaust gas heating apparatus according to claim 1, further comprising an exhaust gas bypass line and a gas direction switching valve. The exhaust gas heating apparatus of claim 1, wherein a combustion catalyst is mounted at a rear end of the reforming reactor. The internal combustion engine exhaust gas heating apparatus according to claim 1, wherein the fuel preheating line is installed to pass through the rear end of the catalytic reactor or the catalyst bed in order to preheat the fuel. The apparatus for producing a reducing gas for removing nitrogen oxides, comprising reducing gas for removing nitrogen oxides from a predetermined gas, including the internal combustion engine exhaust gas heating apparatus of claim 1.