JP2004332610A - Exhaust particulate purifying device and its method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reliably purify a PM with no pressure loss by improving the trapping efficiency of the PM and efficiently stabilizing the incineration of the PM. <P>SOLUTION: This exhaust particulate purifying device comprises fuel additive supply means 17, 18, 19 provided in a fuel supply system for an engine 10 for supplying an additive of solution containing Ba or Sr and Ti dissolved in organic solvent into fuel to be supplied to the engine and an exhaust particulate static charge trapping reactor 20 provided in an exhaust system for the engine for trapping exhaust particulates in exhaust gas using static charges and incinerating them. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus and a method for purifying exhaust particulates, and more particularly, to a method of adding a fuel additive to fuel supplied to a diesel engine or a lean burn gasoline engine to collect and incinerate particulates in exhaust gas discharged from the engine. The present invention relates to a device and a method for purifying exhaust particulates purifying by means of a method.
[0002]
[Prior art]
It is known that the exhaust gas of a diesel engine or a lean-burn gasoline engine contains a large amount of exhaust fine particles (hereinafter sometimes referred to as PM) containing carbon as a main component, which causes air pollution. Various devices or methods for capturing and removing these fine particles from exhaust gas have been proposed, and an example thereof is disclosed in Patent Document 1 as an example.
[0003]
In the particulate incineration method described in Patent Document 1, an additive supply mechanism is provided in a fuel supply system of a diesel engine, and the fuel supplied to the engine contains at least one of cerium, copper, and iron. A fuel additive consisting of a liquid obtained by dissolving a catalyst in a petroleum-based solvent is added, and exhaust gas discharged from the engine is passed through a filter made of a gas-permeable porous material which is a honeycomb filter made of silicon carbide. Fine particles in the gas are captured by a filter and incinerated.
[0004]
[Patent Document 1]
JP-A-10-30429 [0005]
[Problems to be solved by the invention]
By the way, as described in Patent Document 1, a method of adding a fuel additive of an oxidation catalyst to fuel supplied to a diesel engine, capturing PM by a honeycomb filter made of silicon carbide, and incinerating the same is based on a method of using an oxidation catalyst. This has the advantage that PM can be incinerated at a relatively low temperature without adding heat from the outside.However, since the trapping of PM depends on a filter, the trapping rate or trapping rate of PM by so-called slip-through of PM is reduced. There is a limit, and PM purification efficiency cannot be said to be sufficient.
[0006]
Therefore, if the average diameter of the fine pores of the filter is reduced in order to increase the trapping rate, so-called clogging due to PM may occur, and the fuel efficiency may be deteriorated due to an increase in pressure loss of exhaust gas.
[0007]
An object of the present invention is to solve the problems of the related art, improve the PM collection efficiency, and efficiently and stably incinerate PM, and can surely purify PM without pressure loss. An object of the present invention is to provide an exhaust particulate cleaning device and method.
[0008]
[Means for Solving the Problems]
To achieve the above object, there is provided an exhaust particulate purification device according to the present invention, comprising: a fuel additive supply means provided in a fuel supply system of an engine for adding an additive to fuel supplied to the engine; An exhaust particulate purification device comprising exhaust particulate collecting and incineration means for collecting and incinerating particulates contained in the fuel, wherein the fuel additive is a solution in which Ba or Sr and Ti are dissolved in an organic solvent. The exhaust particulate collection / incineration means is an exhaust particulate electrostatic collection reactor that collects and incinerates exhaust particulates using static electricity.
[0009]
Further, an exhaust particulate purification method includes adding an additive to fuel supplied to an engine, collecting particulates contained in exhaust gas after combustion of the fuel and the additive in the engine, and incinerating the particulates. The fuel additive is a solution in which Ba or Sr and Ti are dissolved in an organic solvent, and the step of collecting and burning the exhaust fine particles includes removing the exhaust fine particles by an exhaust fine particle electrostatic collection reactor. It is collected and incinerated using static electricity.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a layout diagram schematically showing an embodiment of the present invention. In FIG. 1, reference numeral 10 denotes a diesel engine, 11 denotes an intake port connected to an intake system, 12 denotes an exhaust port connected to an exhaust system, and 13 denotes a piston defining a combustion chamber. In the present embodiment, the fuel supplied from the fuel tank 14 via the fuel pipe 15 to the combustion chamber of the engine 10 is injected by the fuel injection valve 16 and supplied.
[0011]
The fuel tank 14 is connected to an additive tank 19 via an additive supply pipe 18 having an additive pump 17. The additive pump 17 is controlled by a controller (not shown), and is configured to supply an appropriate amount of fuel additive to the fuel tank 14 according to the amount of fuel. Exhaust gas from the diesel engine 10 is introduced into an exhaust particulate electrostatic collection reactor 20 disposed in an exhaust system, purified as described later, and discharged to the atmosphere.
[0012]
The fuel additive supplied from the additive tank 19 to the fuel tank 14 via the additive pump 17 is a solution in which Ba or Sr and Ti are dissolved in an organic solvent.
[0013]
FIG. 2 is a cross-sectional view showing the structure of the exhaust particulate electrostatic collection reactor 20 used in the embodiment of the present invention. A substantially cylindrical metal outer cylinder portion 24 having a frusto-conical connecting portion 22 on both sides is provided, and a support member 26 having insulation, heat resistance, cushioning properties, and the like with respect to the outer cylinder portion 24, for example, It has a honeycomb structure 28 supported by an alumina mat. The honeycomb structure 28 is a so-called straight flow type porous honeycomb structure formed of ceramics such as cordierite, silica, and alumina.
[0014]
Here, the honeycomb structure 28 is preferably formed of a high porosity base material having a porosity of about 55 to 70% in a base portion (wall portion) excluding the through passage, and the length thereof is approximately It is around 200 mm. In the present embodiment, an insertion hole 28A is formed in the center, and a rod-shaped discharge electrode 31 is arranged in the insertion hole 28A. Further, an outer peripheral electrode 32 is arranged on an outer peripheral portion of the honeycomb structure 28.
[0015]
In the present embodiment, as shown in FIGS. 1 and 2, the discharge electrode 31 includes a plurality of stabs 31 a and 31 b at a portion located in the space inside the outer cylindrical portion 24, and the stabs 31 a 31 b is directed to the outer peripheral electrode 32. The discharge electrode 31 can be formed of chromium steel having excellent corrosion resistance (for example, 10Cr5Al), but is not limited thereto, and another metal having corrosion resistance can be used.
[0016]
Further, the outer peripheral electrode 32 disposed on the outer peripheral portion of the honeycomb structure 28 may be a mesh electrode, or may be formed by applying a conductive metal paste to the outer peripheral portion. Note that it is sufficient that the outer peripheral electrode 32 exists on at least a part of the outer peripheral portion of the honeycomb structure 28. However, when it is desired to maximize the PM collection rate, the honeycomb structure 28 is preferably formed so as to cover the entire outer peripheral portion.
[0017]
The discharge electrode 31 and the outer peripheral electrode 32 are connected to a DC power supply 33, respectively. In the present embodiment, the discharge electrode 31 is connected to the negative side of the DC power supply 33 through an insulator 29 provided through the metal outer cylinder portion 14, and the outer peripheral electrode 32 is also grounded through the insulator 29. Have been. The voltage of the DC power supply 33 is 5 kV or more. Further, the exhaust particulate electrostatic collection reactor 20 is not limited to the above-described arrangement of the central discharge electrode 31 and the outer peripheral electrode 32, and may have a form in which flat electrodes are arranged to face each other.
[0018]
According to the exhaust particulate cleaning apparatus and method according to the above-described embodiment, fuel such as light oil to which an appropriate amount of a solution obtained by dissolving Ba or Sr and Ti in an organic solvent is injected and supplied into the combustion chamber by the fuel injection valve 16. Being burned. As a result of such combustion, Ba or Sr and Ti react with oxygen to produce barium titanate (BaTiO ₃ ) or strontium titanate (SrTiO ₃ ), and a mixture with simultaneously generated PM is formed. Then, the exhaust gas containing the mixture of BaTiO ₃ or SrTiO ₃ and PM is led to the exhaust particulate electrostatic collection reactor 20 through the exhaust pipe.
[0019]
On the other hand, in the exhaust particulate electrostatic collection reactor 20, the power supply 33 is turned on at the same time when the engine is started, and a high voltage is applied between the discharge electrode 31 and the outer peripheral electrode 32. Therefore, the exhaust gas containing the mixture of BaTiO ₃ or SrTiO ₃ and PM passes through the high-voltage electric field by corona discharge in the high-voltage electric field formed between the discharge electrode 31 and the outer peripheral electrode 32. Then, the PM mixture is charged, and is sucked toward the outer peripheral electrode 32 by an electric suction force. In this case, due to the high dielectric constant of BaTiO ₃ or SrTiO ₃ , the charge amount of the PM mixture is significantly improved, and the PM mixture is high in the through-hole surface of the honeycomb structure 28 and the pores in the wall. Captured or collected with efficiency.
[0020]
Further, when an AC power supply is used, microdischarge occurs at the particle interface due to the ferroelectricity of BaTiO ₃ or SrTiO ₃ of the collected PM mixture. As a result, gas molecules in the exhaust gas are activated (radicalized), and ozone (O ₃ ), active oxygen (O ₂ ⁻ ), nitrogen dioxide (NO ₂ ), and the like having high oxidation activity are generated. The PM trapped in the honeycomb structure 28 is burned and incinerated by the activated gas and discharged as purified exhaust gas.
[0021]
As described above, according to the present embodiment, the trapping efficiency of PM is improved by the high dielectric constant of BaTiO ₃ or SrTiO ₃ , and O ₃ , O ₂ ⁻ , and NO ₂ having high oxidation activity are used. As a result, the PM is continuously burned, so that the PM can be incinerated efficiently and stably without a pressure loss, and the PM can be reliably purified.
[0022]
Further, if an oxidation catalyst such as Ce (cerium), Co (copper), and Fe (iron) is added to the above Ba or Sr and Ti as a fuel additive, the PM oxidizing power of these itself can be used. Since the particle size of the PM mixture can be further reduced, the charge density can be increased and the collection efficiency can be further improved.
[0023]
In the above-described embodiment, an example has been described in which the discharge electrode 31 is set to the negative electrode and the outer peripheral electrode 32 is grounded. However, these are sufficient if a predetermined high voltage is applied between them. It may be of a polarity and does not necessarily have to be grounded. The form of the power supply is not limited to DC, but may be pulse power or AC power. Further, the form of the voltage application is not limited to the above-described constant application, and the voltage application may be performed at a desired time according to the necessity of a PM collection request or a combustion processing request.
[0024]
【The invention's effect】
According to the present invention, an additive of Ba or Sr and Ti is added to the fuel supplied to the engine, and a mixture of BaTiO ₃ or SrTiO ₃ and PM contained in the exhaust gas after combustion is converted into an exhaust particulate electrostatic. Since collection and incineration are performed using static electricity by the collection reactor, the collection efficiency of PM is improved by the high dielectric constant of BaTiO ₃ or SrTiO ₃ , and at the same time, O ₃ and O having high oxidation activity are increased. ₂ ^-, it is possible to perform continuous combustion of the PM by utilizing the NO ₂ or the like, efficiently and stably carry out with the incineration of PM without pressure loss can be reliably purify PM .
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an outline of an embodiment of the present invention.
FIG. 2 is a sectional view showing an example of an exhaust particulate electrostatic collection reactor used in the present invention.
[Explanation of symbols]
10 Engine 14 Fuel Tank 19 Additive Tank 20 Exhaust Particulate Electrostatic Collection Reactor 28 Honeycomb Structure 31 Discharge Electrode 32 Outer Electrode 33 Power Supply

Claims (2)

A fuel additive supply means provided in a fuel supply system of the engine for adding an additive to fuel supplied to the engine; and an exhaust particulate collection device provided in an exhaust system of the engine for collecting and incinerating fine particles contained in exhaust gas. Exhaust particulate purification apparatus comprising a collection and incineration means,
The fuel additive is a solution in which Ba or Sr and Ti are dissolved in an organic solvent,
The exhaust particulate purifying apparatus, wherein the exhaust particulate collecting / incineration means is an exhaust particulate electrostatic collection reactor that collects and incinerates exhaust particulates using static electricity. An exhaust particulate purification method of adding an additive to fuel supplied to an engine, collecting and incinerating particulates contained in exhaust gas after combustion of the fuel and additive in the engine,
The fuel additive is a solution in which Ba or Sr and Ti are dissolved in an organic solvent,
The exhaust particulate cleaning method, wherein the exhaust particulates are collected and incinerated, wherein the exhaust particulates are collected and incinerated by using an exhaust particulate electrostatic collection reactor using static electricity.

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