JPH10165768A - Method for deodorizing exhaust gas from internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove malodor attributed to aldehydes in an exhaust gas and make the malodor hardly diffused in the ambient air by oxidizing and decomposing aldehydes in an exhaust gas by a catalyst which works at a specified low temperature value in an internal combustion engine such as a gas engine in which an exhaust gas purifying catalyst is not installed in the exhaust line. SOLUTION: In an exterior apparatus of a gas heat pump, an odorantremoving apparatus 10 containing a catalyst for adsorbing and removing the odorant added to a fuel gas is installed in the gas suction side of a gas engine 1 and at the same time a HC deodorizing apparatus 21 containing a catalyst for decomposing and removing malodorous components of HC such as aldehydes contained in the exhaust gas is installed in the exhaust gas side of the gas engine 1. MnO2 type catalysts, Cu-Cr type catalysts, ZnO/Cu-SiO2 type catalysts, Pd-Ag type catalysts, Cu-Zn-Cr type catalysts are examples of the catalyst to be used for the HC deodorizing apparatus 21 and each of them works at temperature as low as 60-200 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas deodorizing method for removing an off-flavor component in exhaust gas from an internal combustion engine used in an environment where people are present around the city or the like.

[0002]

2. Description of the Related Art For example, in a gas engine used as a driving source of a gas heat pump for cooling and heating, a gas such as city gas or propane gas used as a fuel contains S (sulfur) or N (amine) as a measure against gas leakage. Since the odor component of the system is added as an odorant, if the combustion is incomplete, the odor due to the odorant in the unburned gas becomes a problem, and if the combustion is complete, the odor due to the odorant disappears However, S and N in the odorant burn, so SO _X and N
The occurrence of O _X there is a problem of increasing.

[0003] Therefore, for such a gas engine, by installing a deodorizing device in the middle of the fuel gas supply passage, the odorant in the fuel gas is removed before the fuel gas is fed into the combustion chamber of the engine. Removal has already been proposed by the applicant. (For example, see Japanese Patent Application Nos. 6-202615 and 7-348333).

[0004]

By the way, in a gasoline engine of an automobile or the like, the use of a liquid fuel of C8 or more makes it possible to reduce the HC component in the exhaust gas to C1 to C20 (C
6 or more), the HC component in the exhaust gas is usually purified by a three-way catalyst.
In a gas heat pump gas engine, SO _X in the exhaust gas due to the combustion of the odorant acts as a negative catalyst,
Conventionally, a catalyst for purifying exhaust gas has not been used.

[0005] In such a gas engine, even if the odorant added to the fuel gas is removed by the deodorizing device as described above, the phenomenon that the exhaust gas generates a peculiar odor due to the combustion of the fuel gas itself. Because there is no catalyst for exhaust gas, it is released directly to the atmosphere, and in fixed equipment such as a gas heat pump that is fixedly installed as an air conditioning system, it is difficult to diffuse odors. It is becoming a major problem, but no measures have been taken at this point.

[0006] Then, as a result of investigating the off-flavor component of such off-gas of the gas engine exhaust gas, it was found that HC in the exhaust gas of the gasoline engine had a large amount of C6 or more, whereas HC was mainly C3 or less, and it was found that the off-flavor components in the exhaust gas were HC components, especially aldehydes of C1 to C3, and organic acids.

[0007] The present invention has been made based on such knowledge, and has been developed for an internal combustion engine, such as the above gas engine, in which an exhaust gas purifying catalyst is not provided in an exhaust passage. The purpose is to remove the unpleasant odor caused by it and make it difficult to diffuse to the surroundings. Furthermore, an engine that uses a liquid fuel such as gasoline by providing a catalyst for purifying exhaust gas in the exhaust passage, For internal combustion engines such as engines using propane gas into which no agent is mixed, and gas engines in which a deodorizing device is arranged in the middle of a fuel gas supply passage for introducing city gas and a catalyst for purifying exhaust gas is provided in an exhaust passage. It is another object of the present invention to remove the off-flavor due to the aldehyde slightly present in the exhaust gas, thereby making it more difficult for the off-flavor to diffuse to the surroundings.

[0008]

According to the present invention, there is provided a catalyst for operating an aldehyde in exhaust gas at a low temperature of 60 to 200 ° C., as described in claim 1 above. And decompose it by oxidation.

Further, in the method for deodorizing an exhaust gas of an internal combustion engine according to the first aspect, as described in the second aspect, the catalyst comprises manganese dioxide (MnO ₂ ) as a basic component. It is characterized by the following.

Further, in the exhaust gas deodorizing method for an internal combustion engine according to the first aspect, as described in the third aspect, the catalyst comprises copper-chromium (Cu-Cr) as a basic component. It is characterized by being.

Further, in the method for deodorizing exhaust gas of an internal combustion engine according to the first aspect, as described in the fourth aspect, the catalyst comprises zinc oxide (ZnO) / copper-silicon dioxide (Cu-SiO2). ₂ ) as a basic component.

[0012] In the exhaust gas deodorizing method for an internal combustion engine according to the first aspect of the present invention, as described in the fifth aspect, the catalyst comprises palladium-silver (Pd-Ag) as a basic component. It is characterized by being.

Further, in the method for deodorizing exhaust gas of an internal combustion engine according to the first aspect of the present invention, as described in the sixth aspect, the catalyst comprises copper-zinc-chromium (Cu-Zn-C).
r) as a basic component.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for deodorizing exhaust gas of an internal combustion engine according to the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows a gas heat pump for cooling and heating in which a gas engine for carrying out the exhaust gas deodorizing method of the present invention is used. The gas engine 1 is a cycle-cooled gas engine. The gas engine 1 is provided with a refrigerant circuit 3 for circulating a refrigerant and a cooling water circuit 4 for cooling the engine and recovering waste heat. .

The gas engine 1 has a crankshaft 11
The starting motor 2 is connected via a starting clutch 5, and the compressor 31 of the refrigerant circuit 3 is connected via an clutch 6 to the output shaft 12.

An intake passage 14 is connected to an intake port 13 of the gas engine 1. An upstream end of the intake passage 14 is opened to the outside as an air intake 14a. Air cleaner 15 is arranged,
A venturi section 16 is formed in the intake passage 14 downstream of the air cleaner 15, and a throttle valve 17 is installed downstream of the venturi section 17.

A fuel gas supply passage 9 extending from a fuel gas supply source 8 merges with a venturi section 16 of the intake passage 14. The fuel gas supply passage 9 extends along the fuel gas supply passage 9. An odorant removing device 10 for removing the odorant is installed, and a fuel gas supply passage 9 upstream of the odorant removing device 10 serves as a gas source cock.
Two on-off valves 23 and 24 and a zero governor (decompressor) 25 are provided, and a flow rate control valve 26 is provided in the fuel gas supply passage 9 downstream of the odorant removing device 10.

In this embodiment, the odorant removing device 10 is arranged downstream of the zero governor (decompressor) 25 and between the flow control valve 26.
5 and between the on-off valve 24 and the on-off valve 24.

The throttle valve 17 is connected to the crankshaft 11
The opening degree of the gas engine 1 is adjusted by the governor device 7 connected to the engine so that the set engine speed can be maintained. As the heat load of the heat pump increases, the engine speed of the gas engine 1 decreases. Set high to increase.

An exhaust passage 19 is connected to an exhaust port 18 of the gas engine 1, and a downstream end of the exhaust passage 19 is opened to the outside as an exhaust port 19 a.
9, an exhaust heat exchanger 20 is installed. Downstream of the exhaust heat exchanger 20, an exhaust passage 19 between exhaust ports 19a is provided.
Further, an HC deodorizing device 21 for removing off-flavor components of the exhaust gas and a muffler 22 are provided respectively.

In the illustrated embodiment, the HC deodorizing device 2 is used.
Although the muffler 22 is disposed downstream of the muffler 1, the HC deodorizing device 21 may be disposed downstream of the muffler 22 in some cases.

The refrigerant circuit 3 of the gas heat pump is a circuit for circulating refrigerant such as chlorofluorocarbon by a compressor 31 driven by the gas engine 1 from the engine output shaft 12 via the clutch 6. Valve 32,
The indoor heat exchanger 33, the receiver tank 34, the sight glass 35, the expansion valve 36, the outdoor heat exchanger 37, the accumulator 38, and the like are connected in a closed manner by a pipeline.

In the refrigerant circuit 3, during the heating operation, the high-pressure refrigerant discharged from the compressor 31 is supplied to the four-way switching valve 32.
From the indoor heat exchanger 33, the condensed heat is released in the indoor heat exchanger 33 to liquefy, and the room is heated, and then guided to the expansion valve 36 through the receiver tank 34 and the sight glass 35, After the pressure is reduced by the expansion valve 36, the heat is guided to the outdoor heat exchanger 37, the evaporation heat is removed from the outside air by the outdoor heat exchanger 37, and the vaporized gas is returned to the compressor 31 through the four-way switching valve 32 through the accumulator 38. It is.

During the cooling operation, the four-way switching valve 32
Is switched, and the high-pressure refrigerant discharged from the compressor 31 is guided from the four-way switching valve 32 to the outdoor heat exchanger 37,
After being cooled by the outside air in the outdoor heat exchanger 37 to release condensed heat and liquefied, the liquid is guided to the expansion valve 36 through the receiver tank 34 and the sight glass 35, and the pressure is reduced by the expansion valve 36, and then the indoor heat exchanger The room is cooled by evaporating the air in the room by evaporating heat from the air in the room by the indoor heat exchanger 33, and then returned to the compressor 31 from the four-way switching valve 32 through the accumulator 38.

The cooling water circuit 4 of the gas heat pump is a circuit for circulating cooling water by two cooling water pumps 41 and 42, and includes a cooling water pump 41, an exhaust heat exchanger 20, a linear three-way valve 43, a radiator 44, Accumulator 38
A circuit having a heat exchange section 45 therein;
Cooling water jacket 28 for engine 1, thermostat 4
6 is connected to the circuit having the reference numeral 6.

In the cooling water circuit 4, when the engine temperature is low and the cooling water temperature is equal to or lower than a predetermined value, the cooling water pump 41
From the exhaust heat exchanger 20 passes through the linear three-way valve 43, one passes through the radiator 44 and returns to the cooling water pump 41, and the other passes through the heat exchanger 45 in the accumulator 38 and passes through the cooling water pump The cooling water sent out from the cooling water pump 42 is circulated back to the cooling water pump 42 through the cooling water jacket 28 and the thermostat 46 of the engine 1.

When the engine temperature is high and the cooling water temperature is equal to or higher than a predetermined value, the cooling water sent from the cooling water pump 41 is branched, one of which passes through the exhaust heat exchanger 20 and the other of which is the cooling water pump 42. Cooling water jacket 2
8. After passing through the thermostat 46 and joining, after passing through the linear three-way valve 43, one passes through the radiator 44 and returns to the cooling water pump 41, and the other passes through the heat exchange section 45 in the accumulator 38 and passes through the cooling water pump. Circulated back to 41.

The linear three-way valve 43 is connected to the radiator 4
The ratio of the cooling water flowing to the side of the heat exchanger 4 and the side of the heat exchange section 45 is determined by an output signal from a control device (not shown) based on the input of the temperature of the cooling water and the operating state of the engine.
3 is controlled.

By the way, in the outdoor unit of the gas heat pump as described above, as shown in FIG. 2, a catalyst for adhering and removing the odorant added to the fuel gas on the intake side of the gas engine 1 is provided. The stored odorant removing device 10 is disposed, and an HC deodorizing device 21 that stores a catalyst for decomposing and removing the off-flavor component of HC contained in the exhaust gas is disposed on the exhaust side of the gas engine 1. Have been.

The catalyst used in the odorant removal device 10 disposed on the intake side of the gas engine 1 is, for example, one of three types of odor components (mercaptan,
Sulfides and thiophenes) are as follows.

That is, as a catalyst for a mercaptan-based odor component, a Cu-H ion-exchanged zeolite-based catalyst, a Mn oxide-ceramic-based catalyst, a Cu-Mn catalyst,
A hopcalite catalyst, a Mn-Fe catalyst, or the like is used. As a catalyst for a sulfide-based odor component, a Mn oxide-ceramic catalyst, a Cu-Mn catalyst, a hopcalite catalyst, a Mn-Fe catalyst, or the like is used. Catalysts for the odor components of the system include Mn oxide-ceramic catalyst, Cu-Mn catalyst, hopcalite catalyst, Mn
-An Fe-based catalyst or the like is used.

In order to remove both the sulfide-based odor component and the thiophene-based odor component, it is preferable to use a Mn oxide-ceramic catalyst, a hopcalite catalyst, or a Mn-Fe catalyst.

On the other hand, in order to carry out the exhaust gas deodorizing method of the present invention, the catalyst used in the HC deodorizing device 21 disposed on the exhaust side of the gas engine 1 includes a MnO ₂ type catalyst, a Cu—Cr type catalyst. there ZnO / Cu-SiO ₂ catalyst, Pd-Ag-based catalyst, Cu-Zn-Cr-based catalyst and the like.

Regarding the shape and structure of the catalyst used in the HC deodorizing apparatus 21, in this embodiment, after the catalyst material is prepared, the catalyst itself is formed into a honeycomb structure and fired. Alternatively, it is a honeycomb structure manufactured by applying a catalyst material inside an activated alumina honeycomb carrier, drying and firing the catalyst material, and the HC deodorizing device 21 is configured as shown in FIG. The catalyst 21a having such a honeycomb structure is accommodated in a catalyst container 21b serving as an exhaust passage via a catalyst holding mat 21c.

Examples of the respective catalyst materials used in the HC deodorizing apparatus 21 are as follows.

Manganese dioxide (MnO ₂ ) catalyst Specific gravity: 0.8 kg / L Composition: MnO ₂ 90% Other metals 10
%

Copper-chromium (Cu-Cr) catalyst Specific gravity: 0.5 kg / L Composition: CuO 40% Cr ₂ O ₃ 40% Other metals 10%

Copper-zinc-chromium (Cu-Zn-Cr) catalyst Specific gravity: 1.5 kg / L Composition: CuO 40% ZnO 40% Cr ₂ O ₃ 40% Other metals 10%

Copper-silicon dioxide (Cu-SiO ₂ ) catalyst Specific gravity: 0.7 kg / L Composition: CuO 50% SiO ₂ 40% Other metals 10%

Zinc oxide (ZnO) catalyst Specific gravity: 1.0 kg / L Composition: ZnO 90%

Palladium-silver (Pd-Ag) catalyst A catalyst in which silver is supported on a carrier. Specific gravity: 0.7 kg / L

HC containing any of the above catalysts
In the exhaust gas deodorizing method of the present embodiment performed by the deodorizing device 21, the fuel gas from which the odorant has been removed by the odorant removing device 10 disposed on the intake side is burned in the combustion chamber of the gas engine 1. With respect to the exhaust gas discharged after the exhaust gas, the aldehyde, which is an odor component in the HC of the exhaust gas, is converted to aldehyde (HC) at a low temperature of 60 to 200 ° C. by a catalyst contained in an HC deodorizing device 21 disposed on the exhaust side. 2R-CHO + O ₂ ) → It is decomposed by oxidation like acid anhydride (2R-COOH).

According to such an exhaust gas deodorizing method for a gas engine according to the present embodiment, the odorant removing device 10 on the intake side is provided.
As a result, the odorant serving as the source of SO _X is removed before the combustion of the fuel gas, so that the HC deodorizing device 21 disposed on the exhaust side does not contain SO _X acting as a negative catalyst. Thus, aldehyde, which is an odor component of HC (H _n C _m ) in the exhaust gas, can be oxidized by the catalyst to be decomposed, and thereby, the problem of an odor caused by the exhaust gas can be solved.

Further, the catalyst contained in the HC deodorizer 21 is an inexpensive oxidation catalyst as compared with a normal three-way catalyst, and is therefore advantageous in terms of cost.
Since it acts only on the aldehyde which is the odor component of C, its effect duration can be kept long.

Further, since the catalyst accommodated in the HC deodorizing device 21 operates at a low temperature of 60 to 200 ° C., the catalyst is disposed at a position in the exhaust passage close to the gas engine 1 where the exhaust gas temperature is high. This is not necessary, and the catalyst can be arranged at an appropriate position in the exhaust passage away from the gas engine 1, so that the degree of freedom of the mounting position of the HC deodorizing device 21 is increased.

It should be noted that in the present embodiment, the H
An exhaust heat exchanger 20 is disposed upstream of the C deodorizing device 21, and the high temperature exhaust gas from the gas engine 1 is exchanged with the cooling water by the exhaust heat exchanger 20. The cooling water heated by exchanging heat with the heat is carried to the accumulator 38, and the low-temperature low-pressure refrigerant is heated through the heat exchanger 45, whereby the heating efficiency can be improved, and the exhaust gas is deodorized by HC. The temperature in the range of 60 to 200 ° C. at which the catalyst in the apparatus 21 efficiently oxidizes the aldehyde can be reduced.

The exhaust gas deodorizing method for an internal combustion engine according to the present invention has been described above with reference to one embodiment using a gas engine used in a gas heat pump. However, the present invention is limited only to the above embodiment. For example, the present invention can be applied to a gas engine for vehicles using propane gas as a fuel, a gasoline or diesel engine, and the like.

In such a case, as shown in FIG. 3 (A), CO, HC (H _n
C _m), to remove the NO _X, etc., removed from the cooled exhaust gas into a low temperature of 60 to 200 ° C., can not be removed HC and H _n C _m (the odor component) by HC deodorizing device 21 by the cooling fins Good to do.

[0050] Also, even in the case of a gas heat pump, with SO _X component is prevented from contamination in the exhaust gas by placing the odorant removal device in the middle of the fuel gas supply passage, an exhaust gas using a three-way catalyst CO in, HC, to remove NO _X and the like, further, water after removing the dehydrating device, HC
It can be carried out by removing off-flavor components with a deodorizing device. In addition, instead of using a three-way catalyst, an oxidation catalyst or a reduction catalyst for purifying exhaust gas can be used. It is also possible to carry out in combination with another appropriate exhaust gas purification method, such as using a plurality of reduction catalysts in combination.

When a three-way catalyst is used as described above,
In any case, such as when using an oxidation catalyst or reduction catalyst for purifying exhaust gas, or when using a combination of a plurality of three-way catalysts, oxidation catalysts, and reduction catalysts, deodorization that oxidizes aldehydes downstream of them. H containing the catalyst for use
By installing the C deodorizing device, it is possible to remove the off-flavor component slightly remaining in the exhaust gas, and it is possible to prevent discomfort to surrounding people.

In these cases, an exhaust gas radiating portion may be provided in the exhaust passage on the upstream side to reduce the temperature of the exhaust gas flowing into the HC deodorizing device to a temperature of 60 to 200 ° C. It is preferable to provide a cooling water passage for cooling the deodorizing catalyst in the HC deodorizing device so that the deodorizing catalyst does not become hot even if the exhaust gas flows in.
In order to lower the temperature of the exhaust gas flowing into the HC deodorizing device, for example, as shown in FIG. 3B, the exhaust gas is cooled by separating the muffler from the three-way catalyst, and then the muffler is further cooled. A structure is also conceivable in which the exhaust gas is further cooled by expanding the exhaust gas in an internal expansion chamber, and then guided to an HC deodorizing device provided at a rear portion in the muffler.

[0053]

According to the exhaust gas deodorizing method for an internal combustion engine of the present invention as described above, it is possible to remove the off-flavor component of the exhaust gas generated by the combustion of the liquid fuel or the fuel gas itself.

[Brief description of the drawings]

FIG. 1 is a circuit diagram schematically showing a gas heat pump using a gas engine for performing an exhaust gas deodorizing method of the present invention.

FIG. 2 is an explanatory view schematically showing an outdoor unit of the gas heat pump shown in FIG.

FIG. 3 is a flow chart for carrying out the exhaust gas deodorizing method of the present invention;
(A) An explanatory diagram showing an example of an exhaust passage of a gas engine for an automobile, and (B) an explanatory diagram showing another example of an exhaust passage of a gas engine for a gas heat pump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas engine 10 Odorant removal device 21 HC deodorization device 21a Catalyst

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B01J 23/72 B01J 23/86 A 23/86 B01D 53/36 G

Claims (6)

[Claims] An aldehyde in the exhaust gas is reduced from 60 to 20.
An exhaust gas deodorizing method for an internal combustion engine, comprising oxidizing and decomposing with a catalyst that operates at a low temperature of 0 ° C. 2. The method for deodorizing exhaust gas of an internal combustion engine according to claim 1, wherein the catalyst comprises manganese dioxide (MnO ₂ ) as a basic component. 3. The exhaust gas deodorizing method for an internal combustion engine according to claim 1, wherein the catalyst comprises copper-chromium (Cu-Cr) as a basic component. 4. The exhaust gas deodorizing method for an internal combustion engine according to claim 1, wherein the catalyst comprises zinc oxide (ZnO) / copper-silicon dioxide (Cu-SiO ₂ ) as a basic component. . 5. The catalyst according to claim 1, wherein the catalyst is palladium-silver (Pd-Ag).
2. The method according to claim 1, wherein
The exhaust gas deodorizing method for an internal combustion engine according to the above. 6. The catalyst is copper-zinc-chromium (Cu-Zn).
2. The method for deodorizing exhaust gas of an internal combustion engine according to claim 1, wherein the method comprises -Cr) as a basic component.