KR100675957B1 - Internal combustion engine exhaust gas heater - Google Patents

Abstract

The present invention relates to an internal combustion engine exhaust gas heating apparatus required for heating a 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 a tubular body; The combustion reforming catalyst is filled in the housing so as to burn / reform exhaust gas, and an electrothermal heater is installed at an introduction portion of the catalytic reactor, and a fuel preheating line and fuel air connected from the outside of the housing to supply fuel are provided. Catalytic reactor is installed air preheating line for introducing; 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

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 to 7 are cross-sectional views of the catalytic reactor of FIG.

8 shows DOC heating test results using reformed gas

<Description of Symbols for Main Parts of Drawings>

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

12,23, 3000: DPF 21: Evaporator

40: differential pressure sensor 100: housing

120: baffle 130: heater connector

140: electric heater connector 150: power supply line

170: electric heater 200: mixer

300: fuel preheating line 500: catalytic reactor

510: combustion reforming catalyst 530: expansion cone

540: cooling fin 542: flow path heat sink

543: Euro 550: catalyst support plate

600: air preheating line 700: inlet

1100: combustion reformer 2000: DOC

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 step due to the limited power available or the space required for installing an external burner, which is an obstacle to the practical use of automatic after-treatment 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 follows a configuration arranged in series at the rear end of the diesel oxidation catalyst (DOC), and serves to reduce particulate matter in the final exhaust gas by collecting particulate matter from a diesel engine in a filter. When a certain amount of PM is accumulated, 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.

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.

It is still another object of the present invention to apply a reactor for producing a synthesis gas (mixture of H2 and CO) capable of heating a discharge gas by carrying out catalytic combustion of a part of the fuel in an exhaust pipe or simultaneously burning at low temperature below 100 ° C. An object of the present invention is to provide an internal combustion engine exhaust gas heating apparatus capable of securing thermal stability against heat of 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, and an electrothermal heater is installed at an introduction portion of the catalytic reactor, and a fuel preheating line and fuel air connected from the outside of the housing to supply fuel are provided. Catalytic reactor is installed air preheating line for introducing; 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.

The heat dissipation means is characterized in that the plurality of heat radiation fins formed on the outer surface of the catalytic reactor.

In addition, the heat radiating means is characterized in that the flow path through the catalytic reactor formed so that the exhaust gas flows.

In addition, a plurality of baffles are provided on the inner wall of the housing to allow exhaust gas to flow toward the catalytic reactor.

The fuel preheating line and the air preheating line may be installed to pass through the rear end of the catalytic reactor in order to preheat the fuel and combustion air.

In addition, a buffer for increasing the residence time inside the housing is provided in a portion located in the rear end of the catalytic reactor of the air preheating line.

Another invention is a nitrogen oxide removal reducing gas production apparatus for producing a reduction gas for nitrogen oxide removal from a predetermined gas, including the internal combustion engine exhaust gas heating apparatus.

Another invention is a fuel supply device for resupplying a combustion reformed gas generated by an internal combustion engine exhaust gas heating device to the internal combustion engine.

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

In the present invention, by placing the reforming reactor inside the exhaust gas to secure the cooling action by this, the heating of the catalyst for De-NO _X or NO _X trap not shown in the drawing (DOC, DPF) is performed by using the generated heat. Can be.

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

The fuel required for combustion may utilize fuel mounted on a vehicle or a separate hydrocarbon, and air, which is an oxidant, is supplied through an external compressor.

Combustion reformer 1100 of the present invention comprises a catalytic reactor 500, a catalytic heater 170, a mixture of the combustion gas and exhaust gas 200 and the housing 100 including the exhaust gas moving space to provide exhaust gas heating Form independent parts to perform.

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.

When the ratio of the cross-sectional area of the introduction part 700 and the reaction part is maintained in the range of 0.1 to 0.9, ignition proceeds quickly 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 to 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 As a result, the rapid reforming reaction proceeds with evaporation at a high temperature, so that the accumulation of high-boiling hydrocarbons up to 350-480 ° C contained in diesel (less than 5% by weight) can be completely excluded.

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.

The cross section of the reaction part filled with the combustion reforming catalyst 510 of the catalytic reactor 500 in FIG. 4 may be circular as shown in FIG. 5 or rectangular as shown in FIGS. 6 to 7, and the shape thereof is not limited.

In addition, the reactor diameter / diagonal of the expanded portion is preferably 50 mm or less. Preferably 30 mm or less is recommended. Even if the cooling fin is installed, if the diameter of the catalytic reactor is too large, there is a problem that the heat transfer rate of the catalyst itself is slow, and thus the desired purpose cannot be achieved.

5 and 6, a plurality of cooling fins 540 are provided on the outer surface of the catalytic reactor 500 to increase the heat dissipation of the reaction heat to increase the combustion / modification capacity of the hydrocarbon in a small volume. Provide a catalytic combustor 1100.

As shown in FIG. 7, a flow path 542 through which the exhaust gas flows may be installed in the reaction part to increase the external surface area required for heat transfer between the exhaust gas and the catalytic reactor 500, thereby omitting the mounting of the cooling fins. You may.

At this time, the ratio (S / A) of the outer surface area (S) of the reactor that can be in contact with the exhaust gas and the cross-sectional area (A) on which the catalyst is mounted is preferably 2.0 or more, so that smooth heat exchange is achieved.

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.

In order to further improve the cooling efficiency, the baffle 120 is installed on the inner wall of the housing 100 so that the engine exhaust gas can be concentrated on the outer surface of the catalytic reactor 500.

The baffle 120 is installed to have a predetermined angle with respect to the wall surface of the housing 100 so that the traveling direction of the engine exhaust gas flowing near the inner wall of the housing 100 faces the catalytic reactor 500.

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.

Combustion air is also preheated in the air preheating line 600 to suppress the temperature drop of the reactant introduction part 700.

Similarly, the air preheating line 600 is installed at the rear end of the catalytic reactor 500 and is bent several times inside the housing 100 to increase heat exchange efficiency.

In addition, it is also possible to increase the residence time of the combustion air by placing a buffer (not shown) in the portion located in the rear end of the catalytic reactor 500 of the air preheating line 600.

The buffer (not shown) is a tube having a larger cross-sectional area than the air preheating line 600, and serves to increase the residence time through diffusion of combustion air.

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 uniform fuel is supplied to the DOC to burn the reformed gas. Suppress the loss of.

As shown in FIG. 4, a suitable form of the mixer 200 for mixing the gas discharged from the expansion cone 530 and the gas passing while cooling the catalytic combustion layer at the rear end of the catalytic burner 500 provides a rotational force to each gas. The helical form is preferred so that it can be mixed at short distances.

The expansion cone 530 serves to diffuse the combustion reformed gas discharged from the catalytic combustor 500. In addition, a catalyst support plate 550 is installed inside the expansion cone 530 to prevent separation of the combustion reforming catalyst 510 in the catalytic burner 500.

Combustion reforming catalyst 510 is not particularly limited and can be used for both known combustion catalysts and reforming catalysts.

The composition and preparation 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 3-5mm granular activated alumina (gamma-Al ₂ O ₃ , canto product). 105, 24 hours), and then calcined at 1300 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 platinum support, drying (105, 24 hours) and firing (1000, 24 hours) were completed.

The reforming catalyst was also prepared in the same order as the combustion catalyst. 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).

In the reforming reaction of hydrocarbons carried out by the present invention, steam reforming according to Scheme 1, partial oxidation according to Scheme 2, and auto thermal reforming according to Scheme 3 (ATR) are shown. Are distinguished.

Scheme 1

Scheme 2

Scheme 3

However, the partial oxidation reaction is exothermic, as shown in Scheme 2, especially when the heat of reaction is not effectively removed, especially when the reactor is operated at a high ratio of O ₂ / CH at the beginning of the operation (Scheme 4). ) Can't be removed quickly, resulting in loss of reactor and catalyst.

Scheme 4

Accordingly, as shown in FIGS. 5 to 7, a flow path 543 is formed to increase the contact area of the catalytic reactor 500 with the exhaust gas, or a cooling fin 540 is installed on the outer surface of the catalytic reactor 500 and the surroundings thereof. When the reforming system 1100 is configured to allow the exhaust gas to flow, it is possible to provide durability of the catalytic reactor 500 and the catalyst.

There is no particular limitation on the form or material properties of the DPF in which the exhaust gas is heated by means of the catalytic combustion device according to the present invention and the blood is a heating body. 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.

Main measurement 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 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 the ECU that prevents the loss of the filter by adjusting the amount of fuel supplied so that the temperature T4 of the filter outlet does not reach 650 or more (variable according to the heat resistance of the DPF).

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 supplying an engine for reducing oxygen concentration in a reducing gas of nitrogen oxide or an engine in accordance with a ratio of air and fuel to be supplied.

The reactor maintains the oxygen-to-fuel ratio required for the combustion reaction (Equation 4) at the start of the reactor to quickly heat up the catalyst and, if necessary, reduce the air supply or increase the fuel supply to partially oxidize the reaction. Can drive to switch.

That is, the combustion / reforming reaction is variable according to the supply ratio of oxygen and fuel, and the reactor has a corresponding response. The O ₂ / CH ratio in this reactor is operable in the range of 0.05-15. In the initial stage of the reactor, the ratio of O ₂ / CH is preferably in the range of 1.5-15 so that the reactor can be rapidly heated, and increases the amount of fuel supplied after the reactor temperature is heated to 700 ° C or higher, or By reducing the feed rate, the ratio of O ₂ / CH is maintained in the range of 0.15-1.5 to increase the amount of syngas produced.

In addition, when the temperature of the reactor reaches a high temperature of 800 or more and the temperature of T3 reaches the diesel combustion temperature (250) or more, the O ₂ / CH ratio is further lowered (0.02-0.15) so that the partial oxidation reaction is low at the reactor temperature maintenance level by the heat of reaction. It is possible to increase the combustion amount in the DOC 2000 through increasing the supply amount of fuel so as to proceed to operate the heating of the DPF quickly.

That is, in this case, the operation of obtaining the heat of evaporation of light oil through some hydrocarbon combustion proceeds.

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 reactor uses a 3/8 "connection tee made of stainless 316 as the air and fuel introduction tube 600, and the reactor extension tube 700 uses a 3/4" tube made of stainless 316 to igniter the part. The diameter of was reduced and it produced so that the diameter of the main reactor might be expanded.

29 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.

The air was heated to 150 ° C. using an air heater and supplied to the catalyst heater 1100 at a flow rate of 42 Nm ³ / hr. Air supplied to the reactor 500 was supplied using a compressor from the outside, and diesel oil was supplied using a high pressure pump.

12V DC power was supplied for 2 minutes, supplying 12L / min of air for diesel combustion, and ULSD was supplied at 0.5 mL / min. The catalyst was combusted at a constant time so that the rear end temperature (T2) and the rear end temperature of the DOC (2000) reached a steady state, and the gas oil supply was increased in steps of 1.0, 1.2, 1.5, 1.8, 2.5, 3.0, and 4.5 ml / min. .

Accordingly, the temperature of DOC 2000 inlet and outlet is as shown in FIG. After the reaction, the surface state of the reactor 500 was clean. Therefore, it is estimated that the discharge of generated calories is easy in view of the fact that no particular appearance change occurs.

Comparative Example 2

The diesel combustion reaction was carried out as in Example 1. However, a combustion reaction was performed using the reactor 500 and the outer surface thereof was insulated with ceramic insulation. The reactor was constructed of a 1/4 "tube and a 1/2" union made of stainless 316. When supplying the air supply amount 3 L / min and the diesel oil supply amount at 0.5 mL / min, the temperature of the reactor outlet reached 1050, which made it impossible to increase the fuel supply amount.

The diesel combustion reaction lasted for 2 hours, and the appearance after the reaction showed loss of external surface. This shows the importance of removing the heat generated in the reactor.

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.

In addition, it is possible to configure a regenerated fuel supply device for re-supplying the combustion reformed gas generated by the above-described internal combustion engine exhaust gas heating device to the internal combustion engine by using a circulation mechanism such as a pump.

The present invention is not limited to the above-described specific preferred embodiments, and various modifications can be made by any person having ordinary skill in the art 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.

With the provision of the combustion reformer for heating the exhaust gas of the present invention, the DPF can be regenerated 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.

Claims (8)

Housing of tubular body; A combustion reforming catalyst is filled in the housing so as to burn / reform exhaust gas, and an electrothermal heater is installed at an introduction portion of the catalytic reactor, and a fuel preheating line and fuel air connected from an outside of the housing to supply fuel are provided. Catalytic reactor is installed air preheating line for introducing; And A mixer installed at a rear end of the catalytic reactor and mixing a combustion reformed gas discharged from the catalytic reactor and the exhaust gas flowing between the catalytic reactor and the housing, The catalyst reactor is an internal combustion engine exhaust gas heating device is formed with a heat radiating means. The exhaust gas heating apparatus of claim 1, wherein the heat radiating means is a plurality of heat radiating fins formed on an outer surface of the catalytic reactor. The internal combustion engine exhaust gas heating apparatus according to claim 1, wherein the heat dissipation means is a passage passing through the catalytic reactor formed to allow the exhaust gas to flow. The internal combustion engine exhaust gas heating apparatus according to claim 1, wherein a plurality of baffles are provided on the inner wall of the housing to allow the exhaust gas to flow toward the catalytic reactor. The exhaust gas heating apparatus of claim 1, wherein the fuel preheating line and the air preheating line are installed to pass through a rear end of the catalytic reactor in order to preheat fuel and combustion air. The internal combustion engine exhaust gas heating apparatus according to claim 5, wherein a buffer for increasing the residence time in the housing is provided at a portion of the air preheating line located at a rear end of the catalytic reactor. Reducing gas producing apparatus for removing nitrogen oxides, including reducing gas for removing nitrogen oxides from a predetermined gas, including the internal combustion engine exhaust gas heating apparatus of claim 1. A fuel supply device for supplying a combustion reformed gas generated by the internal combustion engine exhaust gas heating device of claim 1 to the internal combustion engine.

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