KR100318888B1 - Diesel engine exhaust gas purifier - Google Patents

Abstract

The present invention captures soot using alternating filter medium by electric heater in the primary filter regeneration unit for post-treatment of exhaust gas of diesel engine and heats filter medium composed of combustion network to regenerate and regenerate soot and unburned hydrocarbon. A NOx is removed by applying a reduction catalyst for removing nitrogen oxide at the inlet and an oxide catalyst at the outlet, and removing NOx, and oxidizing unburned hydrocarbons, particulate matter and carbon monoxide. It relates to a diesel engine exhaust gas purification apparatus, characterized in that it can be used as.

Description

Diesel engine exhaust gas purification device

The present invention relates to a diesel engine exhaust gas purifying apparatus, and in particular, unburned hydrocarbons and particulate matter are alternately collected in a filter medium combustion network to be burned by the heating wire of the electric heater and the filter medium combustion network heated by the heating wire, In the honeycomb coated with metal oxide on the back of the filter media, a catalyst for removing NOx at the inlet is removed to remove nitrogen oxide, and an oxidation catalyst is applied at the outlet to secondary oxidation and carbon monoxide is oxidized to carbon dioxide. In addition, the present invention relates to a diesel engine exhaust gas purifying apparatus which oxidizes a part of particulate matter and a hydrocarbon, or evenly distributes an NOx removal catalyst and an oxidation catalyst throughout the honeycomb.

Conventional diesel engine exhaust gas purification apparatus used a method of reburning the filtered particulate matter with a heating wire or burner using only the filter medium. In this method, pressure sensor is applied before and after the filter medium to heat it with a burner or the like and supply air to the blower to burn off the particulate matter deposited on the filter medium. However, this method has to burn the unburned hydrocarbons or particulate matter at a time, so that the temperature rises sharply, thereby shortening the life of the filter medium.

In addition, while regenerating the filter medium by burning particulate matter with a burner or the like, there is also an inefficient problem such that the exhaust gas from the diesel engine must be filtered or bypassed with the second filter medium.

In addition, conventionally, the catalyst was coated on a ceramic filter medium to oxidize hydrocarbons and carbon monoxide and reduce NOx. However, particulate matter or hydrocarbons were precipitated on the surface of the catalyst and precipitated to exhibit sufficient catalyst performance. Did not sufficiently oxidize the fine particulate matter.

The technical problem to be achieved by the present invention is to filter particulate matter and hydrocarbons in diesel exhaust gas that are difficult to oxidize, and then to increase the temperature of the filter medium combustion network composed of a combustion network by electric heater to burn particulate matter and hydrocarbons. Honeycomb coated with metal oxide, which is a secondary catalytic reduction and oxidation treatment, can be used continuously at low temperature of 200 ~ 450 ℃ without sedimentation and periodic cleaning.It has high conversion rate of carbon monoxide and nitrogen oxide at low temperature. It is to provide a diesel engine exhaust gas purification device.

The technical problem to be achieved by the present invention is to collect the unburned hydrocarbons and particulate matter alternately in the filter medium combustion network to burn by the heating wire of the electric heater and the filter medium combustion network heated by this heating wire, the metal oxide In the coated honeycomb, a catalyst for removing NOx is applied to the inlet to remove nitrogen oxides, and an oxidation catalyst is applied to the outlet to oxidize secondary to oxidize carbon monoxide to carbon dioxide, or to remove some of the particulate matter and hydrocarbons. Or by a diesel engine exhaust gas purifier that evenly distributes the NOx removal catalyst and the oxidation catalyst throughout the honeycomb.

1 is a schematic view showing a diesel engine exhaust gas purification apparatus of the present invention.

Figure 2 is a view showing a filter medium combustion network in the diesel engine exhaust gas purification apparatus of the present invention.

3 is a view showing an electric heater in the diesel engine exhaust gas purifying apparatus of the present invention.

<Explanation of symbols for main parts of drawing>

10a, 10b: primary filtration regeneration unit 11a, 11b: electric heater

12a, 12b: filter medium combustion network 20: valve

20a, 20b: exhaust gas inlet path 30: time control unit

40: secondary catalyst reduction oxidation treatment 41: honeycomb

As shown in FIGS. 1 to 3, two primary filtration regeneration units 10a and 10b installed in the front of the electric heaters 11a and 11b are connected to the engine side, and the primary filtration regeneration unit. A valve 20 which opens and closes the exhaust gas inflow passages 20a and 20b so that only one of the 10a and 10b is in communication with the engine side, and the valve 20 is operated at a predetermined time while being cut off from the engine side. In the exhaust gas purification device comprising a time control unit 30 for supplying electric power to the electric heaters 11a and 11b of the primary filtration regeneration units 10a and 10b, the primary filtration regeneration units 10a and 10b, respectively. ) Is provided with a filter medium combustion network 12a, 12b folded in a zigzag spaced apart by a predetermined distance, and finely to remove NOx at the inlet to the rear of each of the primary filtration regeneration unit (10a) (10b). Divided aluminum oxides, zeolites, yttria and platinum group metals and additives Ni and L attached to the mixture A reduction catalyst comprising a catalyst composition for removing NOx containing at least one element selected from i, Na, K, Cs, Rb, and Fr is applied, and at the outlet, carbon monoxide is oxidized to carbon dioxide and some of the particulate matter and hydrocarbons are oxidized. Secondary catalytic reduction oxidation in which honeycomb 41 coated with an oxidation catalyst comprising Ni in CeO 2 and LaO 3 and comprising an oxidation catalyst composition impregnated with at least one element selected from Fe, Cu, V, Cr, and Co. The processor 40 is connected to the installation.

At this time, the power of the electric heater (11a) (11b) is used as a storage battery used at the start of the diesel engine and as the heat wire as shown in Figure 3 by using a nichrome wire, canal wire, metal composite heating wire as it is or ceramic coating Likewise, it is wound on a support made of ceramic or mica board.

In addition, as the filter medium combustion network (12a) (12b), a stainless steel mesh or a composite metal mesh of 30 to 800 mesh is folded in a zigzag to be spaced apart by a predetermined distance as shown in FIG.

As the active ingredient used for the metal oxide coating applied to the honeycomb 41 in the secondary catalytic reduction oxidation treatment unit 40, finely divided aluminum oxide, zeolite, yttria and platinum attached to the mixture A catalyst composition for NOx removal containing at least one element selected from the group metals and the additives Ni and Li, Na, K, Cs, Rb, and Fr is applied to the exit of the honeycomb 41 and used for CeO ₂ and LaO ₃ . An oxidation catalyst composition containing Ni and impregnated with at least one element selected from Fe, Cu, V, Cr, and Co is applied to the honeycomb 41 for use.

In the present invention as described above, the exhaust gas flows into the primary filtration regeneration unit 10a communicated to the engine side by the valve 20, and unburned hydrocarbons and particulate matter are collected in the filter medium combustion network 12a.

When the unburned hydrocarbons and particulate matter are collected in the filter medium combustion network 12a for a predetermined time, the time control unit 30 operates the valve 20 so that the primary filtration and regeneration unit 10b communicates with the engine side. At the same time, power is applied to the electric heater 11a to regenerate by burning unburned hydrocarbons and particulate matter collected in the filter medium combustion network 12a.

At this time, unburned hydrocarbons and particulate matter of the exhaust gas are collected in the filter medium combustion network 12b of the primary filtration regeneration unit 10b communicated with the engine side.

That is, as the valve 20 controlled by the time control unit 30 is switched, unburned hydrocarbons and particulate matter are collected in one filter medium combustion network, and unburned hydrocarbons and particulate matter collected in the other filter medium combustion network. The material is burned by the electric heaters 11a and 11b.

On the other hand, the filter medium combustion network (12a) (12b) of the present invention is folded in a zigzag spaced apart by a certain distance as shown in Figure 2 as a result the surface area is increased to obtain an optimum filtration effect.

The switching time of the valve 20 is preferably about 1 hour, and the time for which power is applied to the electric heaters 11a and 11b is preferably about 15 minutes.

The exhaust gas passing through the primary filtration regeneration unit (10a) (10b) is passed through the honeycomb 41 of the secondary catalytic reduction oxidation processing unit 40 and is discharged to the atmosphere through the muffler.

The exhaust gas is removed by NOx removal reduction catalyst applied to the inlet of the honeycomb 41, and carbon monoxide is oxidized to carbon dioxide in the oxidation catalyst at the outlet, or some of the particulate matter and hydrocarbons are secondaryly oxidized.

The exhaust gas purification apparatus for a diesel engine of the present invention can be used in diesel vehicles, ships, locomotives, industrial internal combustion engines, aircrafts, and the like.

The present invention will be described in more detail with reference to the following Examples, which are not to be limited to these Examples.

From Example 1 to Comparative Example 1, the diesel engine exhaust gas purifying catalyst and the apparatus were examined for the purifying ability after engine endurance.

The endurance engine used commercially available four-cylinder diesel engine, 2476cc, compression ratio 21: 1, maximum torque / engine speed = 20.0㎏m / 2000rpm, maximum output / engine speed = 85ps / 4200rpm, and diesel engine exhaust gas purification catalyst and device The catalytic purifier was aged for 100 hours under the condition that the temperature was 450 ° C in normal operation.

The total particulate matter (TPM), hydrocarbon (HC), volatility (VOF: Volatile Organic Fraction), CO and NOx were investigated at SV = about 150,000 hr ^-1 . The purification and conversion persistence of

Table 1 shows the performance of the diesel engine exhaust gas purification apparatus by the method as described above.

Example 1

A specific surface area of 550m ² / g of zeolite NaY- 10g and a specific surface area 210m ² / g of γ-Al ₂ O ₃ 160g of palladium chloride, a palladium aqueous solution containing 1.5g and 1.5g platinum containing platinum chloride aqueous solution and 0.2g of the Ni It was impregnated with an aqueous sodium hydroxide solution containing nickel chloride and 0.1 g of Na, and dried at 120 ° C. for 12 hours, and then calcined at 600 ° C. for 2 hours to obtain an oxide catalyst powder. 3 g of cerium oxide powder and 3 g of lanthanum oxide powder were loaded with 0.4 g of Ni and 0.4 g of Fe, dried at 120 ° C. for 12 hours, and calcined at 600 ° C. for 2 hours to obtain a powder for removing NOx. Each aqueous slurry was prepared by wet grinding. An outer diameter of 144 mm long 150 mm corderite monolith carrier having about 400 gas flow cells per square inch of cross-sectional area is immersed in the slurry for NOx removal, and the outlet is immersed in the slurry for oxidation catalyst and taken out to compress excess sludge in the cell. Blown by air, then dried at 120 ° C. for 12 hours and calcined again at 600 ° C. for 2 hours to obtain a catalyzed honeycomb 41 and purifying the exhaust gas for a diesel engine configured as shown in FIGS. 1 and 3. Device.

Comparative Example 1)

Instead of filter material combustion network 12a or 12b, a corderite ceramic filter having 100 cells per square inch is used by supporting an NOx reduction catalyst and an oxidation catalyst on the outlet and honeycomb on the rear of the ceramic filter. A diesel engine exhaust gas purifier is the same as that of Example 1 except that it is not installed.

Table 1. Performance of Diesel Engine Emissions Purification Catalysts and Devices

The present invention is to filter the particulate matter and hydrocarbons in the diesel engine exhaust gas that is difficult to oxidize, and then to increase the temperature of the filter medium combustion network composed of the combustion network by the electric heater to burn particulate matter and hydrocarbons, A diesel engine that can be used continuously in the honeycomb coated with metal oxide, which is a secondary catalytic reduction and oxidation treatment at temperature, without precipitation of particulate matter and periodic cleaning, and has a high conversion rate of carbon monoxide and nitrogen oxide at low temperature. It relates to an exhaust gas purification device.

Claims (1)

Only one of the two primary filtration regenerative units 10a, 10b and the primary filtration regenerative unit 10a, 10b, which are installed at the front and connected to the engine side, are internally installed with electric heaters 11a, 11b. Valve 20 for opening and closing the exhaust gas inlet (20a, 20b) and the electric heater of the primary filtration regeneration unit (10a) (10b) that is operated at the same time and the valve 20 is cut off from the engine side at a certain time In the exhaust gas purification device consisting of a time control unit 30 for applying power to (11a) (11b), Inside each of the primary filtration regeneration unit (10a) (10b) is provided with a filter medium combustion network (12a, 12b) folded in a zigzag spaced by a predetermined distance, Behind each of the primary filtration regeneration units 10a and 10b, aluminum oxide, zeolite, yttria finely divided to remove NOx at the inlet, and platinum group metals and additives Ni, and Li attached to the mixture, A reduction catalyst composed of a catalyst composition for removing NOx containing at least one element selected from Na, K, Cs, Rb, and Fr is applied, and CeO2 and CeO2 are oxidized at the outlet to oxidize carbon monoxide to carbon dioxide and to oxidize some of the particulate matter and hydrocarbons. Secondary catalytic reduction oxidation unit 40 having a honeycomb 41 coated with an oxidation catalyst comprising Ni in LaO 3 and an oxidation catalyst composition impregnated with at least one element selected from Fe, Cu, V, Cr, and Co. Exhaust gas purification device of a diesel engine, characterized in that the connection is installed.

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