JPH02241559A - Removing apparatus of fine particles from exhaust gas and flue gas - Google Patents

Abstract

PURPOSE: To remarkably decrease particulates in exhaust gas due to combustion of hydrocarbon by providing a high voltage generation device, an electrostatic separation means of sooth and a removal means of collected sooth. CONSTITUTION: The high voltage generation means, the means for electrostatically separating the particulates, and the means for removing the collected particulates are placed in a pipe 1 for allowing the exhaust gas or flue gas to pass. The means for electrostatically separating the particulates consists of at least one pair of conductors 1 and 2 allowing the exhaust gas or flue gas to pass through them, and respective these conductors are connected to terminals of the high voltage generator. Also, the means for removing the particulates consists of a means for raising the temperature of the particulates 7 with a spark discharge plug 10, a heater 5, etc., and for burning the exhaust gas rich in air itself or with assistance of air. Thus, the particulates in the exhaust due to the hydrocarbon are remarkably reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a system for removing particulates from flue gas. More particularly, the present invention applies to all cases involving the combustion of diesel engine exhaust or light oil, heavier oils, even heavy oils mixed with aromatic components (heat generating plants, possible The present invention relates to a system for eliminating or at least significantly reducing the emission of particulates from flue gases produced in portable generators, large-scale power plants, etc.) or in the combustion of coal.

In order to simplify the description in this specification, only a diesel engine will be exemplified below, but the points and conclusions described below can be equally applied to other cases.

Combustion of hydrocarbons starting from molecules with about 10 carbons or simple aromatic molecules is eg Co. C
O2 and H. It generates not only the usual combustion products such as carbon dioxide, but also products such as unburned organic compounds, nitrogen oxides, and nitrogen oxides.

The composition of the exhaust gas varies considerably depending on the amount of air used for combustion. However, in order to obtain good process yields (i.e., to obtain sufficient power), the air-to-fuel ratio is fixed at a roughly constant value; Difficult to avoid release.

This phenomenon is particularly obvious to observers in the case of automobile diesel engines, leading to accusations that they pollute the air and are extremely harmful to health.

Overall, such accusations are groundless. In fact, compared to gasoline engines, diesel engines produce four to one-sixth the amount of carbon monoxide (carbon monoxide is a powerful poison as it inhibits the oxygen exchange function of the blood), and the amount of unburned The amount of hydrocarbons (which are highly carcinogenic) is roughly half as much, and the amount of nitrogen oxides (which is associated with acid rain) is also about half.

However, diesel engines emit 40 times more carbon particles (which can cause bronchitis and other chest illnesses over time) and 40 times more sulfur dioxide (which also causes acid rain) than gasoline. Similarly, diesel fuel also releases carbon dioxide (which can be eliminated by desulfurization).

It should also be noted that su\ acts as a mediator for this carcinogen by adsorbing unburned hydrocarbons.

In summary, there is no doubt that the gases produced by the combustion of gas oils, fuel oils and the like are extremely unpleasant and their atmospheric emissions must be completely eliminated or at least greatly reduced.

A significant reduction in the amount of particulates produced by the combustion of hydrocarbons can be achieved by regulating the combustion with electronic devices. However, this adjustment is approximately 20%
Only reduces the smoke grade. This rate of reduction is often insufficient. Many efforts have been made to solve this problem.

Numerous patents (for example, Japanese Patent Application Laid-Open No. 63-232817, European Patent No. 283,240, European Patent No. 114,6)
No. 96, U.S. Patent No. 4,622,810, U.S. Patent No. 4.6
No. 04,868, No. 4571, 938, etc.)
Various types of ceramic filters are used that can mechanically capture particulates.

These ceramic filters can be periodically regenerated, for example, by combustion using hot gases produced in special burners or by means of a preheated air stream. Such filters often contain a catalyst, such as platinum, to facilitate combustion.

By doing this, the amount of particulates is greatly reduced, but the ceramic filter is expensive and fragile, and the catalyst is expensive and easily deteriorates. This made the use of such filters uneconomical, especially for use in automobiles.

U.S. Pat. No. 4,741,746 proposes the use of an electrostatic precipitator with a corona discharge to precipitate carbon particulates in diesel engine exhaust gas.

U.S. Pat. No. 4,587,808 is also related to diesel engines and proposes the use of a molecular dissociator. This molecular dissociator has a voltage of up to 150KV, and CC
The dissociation of O1Co and NOx molecules occurs, the unburned hydrocarbons are dissociated into their constituent elements, and the carbon particles thus produced are then removed together with the carbon particles already present in the exhaust gas.

However, 19
At the Paris Conference in 1987, it was concluded that when automobiles are equipped with systems derived from industry, their effectiveness becomes questionable (in the case of cyclones), their size is too large, and their mechanisms are prohibitively complex. It has been reported that (in the case of electrostatic separators)
(see page).

From the above, it can be seen that in cases of limited dimensions (e.g. in the case of automotive diesel engines or domestic heat plants), the technical aspects related to the reduction of the smoke content in the exhaust gases resulting from the combustion of hydrocarbons are It is clear that the problem and economic problems are far from being resolved.

An object of the present invention is to provide a simple, inexpensive, and compact device that can significantly reduce particulate matter in exhaust gas resulting from the combustion of hydrocarbons, and to The object is to overcome the above-mentioned drawbacks by providing a system that is simple.

According to the invention, a combination of three means is provided in the exhaust or flue gas pipe of a fossil fuel combustion system: a high-voltage generator, electrostatic separation means for the suction and means for removing the collected suction. A dust removal system is provided.

The electrostatic separation means described above comprises at least one pair of conductors disposed where the exhaust or flue gases flow, each of these conductors suitably connected to one of the terminals of the high voltage generator, and one conductor connected to one of the terminals of the high voltage generator. gives a charge of opposite polarity to that of the other conductor.

In contrast to the above, the conductor can consist of one conductor which is suitably insulated from the other conductor and has at least one point pointing in the direction of the other electrode.

In still other embodiments, one of the conductors may be formed on the inner surface of the conduit, and the other may be an elongated conductor disposed along the axis of the conduit and suitably insulated from the conduit.

The means for removing the soot may consist of means for raising the temperature of the particulates by the effect of the exhaust gas itself or air and causing them to burn. It was collected\
can also be removed by using switchable or replaceable means that can be removed and cleaned from the system. Further, for this purpose, known means may be employed depending on the case.

Means of increasing the temperature of the collected particles may be in the form of small auxiliary burners that supply the particles with hot gas rich in oxidizing components, or by heating the particles in a stream of exhaust gas or air or a mixture thereof. It can be in the form of an electric heater.

In cases where the exhaust or flue gas lines run vertically, such as in chimneys, smoke stacks, and other types of commercial vehicles, the dust removal means must be placed at the bottom of the particulate removal system so that the gas is It may consist of a collection trub located at the point of entry into the pipeline. The collection of particulates in this trap is facilitated by the use of appropriate systems, such as vibrators which are activated during the combustion process or during interruptions in the gas flow.

In another embodiment of the invention, a suitably sized particulate removal system that also functions as a container that can be separated from the exhaust/flue line is used to frequently remove, replace, and clean the container. so that it can be reused.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to preferred embodiments illustrated in the accompanying drawings.

In Figure 1, a steel (preferably stainless steel) exhaust or flue gas pipe 1, which also serves as one of the conductors of the particulate removal system, is connected to the positive terminal of a high voltage generator, not shown. be.

Exhaust gas enters through conduit 9. The other conductor connected to the other electrode of the high voltage generator passes through the insulator 8 to the pipe 1
It extends along the axis of the pipe 1 and is partially insulated over a certain distance with an insulator 3. The free end of the conductor 2 is supported by a suitable insulator 4. The insulator 4 is in the form of small spaced rods placed between the pipe 1 and the conductor 2. pipe 1
It also has an external heater 5, a conduit 6 and a spark or glow discharge plug lO.

In operation, exhaust gas is fed into the pipe 1 from the conduit 9 and flows from right to left in the drawing. In the space S between the conductor 2 and the pipe 1, both connected to the terminals of a high-voltage generator, the carbon particles are charged and attracted to the inner wall of the pipe 1, where they are discharged and deposited, forming a deposit 7. form.

When this deposition reaches such a thickness that conductors 1 and 2 cannot be sufficiently insulated from each other due to the formation of carbon throughout conductor 1, the voltage between the conductors drops;
In some cases this voltage drop can be quite significant.

At this point, the heater 5, which can be in the form of an electrical resistance, is activated, and/or the glow discharge or spark discharge plug lO is switched on, and/or very hot gas or air from the auxiliary burner is blown in. be. These operations, either individually or at least one in conjunction with the other, are designed to raise the temperature of the carbon deposit 7 to a temperature in the range of approximately 400° C. to 550° C. at which it burns.

In order to facilitate these operations, at least two of the aforementioned pipes 1 are installed in parallel, and while at least one of these pipes is being separated from the exhaust gas, at least one of the other pipes is being separated from the exhaust gas. In this step, the accumulated dust is removed. In this way, each of these pipes is alternately separated and removed.

The selection of the desired function and the operation of the valves that transfer exhaust gas from one pipe to another are preferably automatically controlled by a microprocessor or timer receiving information from special probes. You can do it like this.

In FIG. 2, in which the same parts as in FIG. The pipe 1 is thus connected to the exhaust vibrator 11 by a coupling 12, which can be in the form of a bayonet fitting, for example.

The apparatus shown in FIG. 2 is exactly the same as described for the embodiment of FIG. 1 with regard to separation. Here, too, at least two pipes can be arranged side by side, so that the exhaust gases are passed alternately through only one pipe. Alternatively, two or more of these pipes may be placed side by side, and only some sides of these pipes may be subjected to the separation process.

In the arrangement shown in FIG. 2, once the deposited layer of soot reaches a predetermined thickness, the pipe 1 is separated from the exhaust vibrator 11 for cleaning and connected to another already cleaned pipe 1. Replaced.

Tests have shown that the particulate content of exhaust/flue gases can easily be reduced by at least 50%.

According to another embodiment, air was fed into the pipe 1 without interrupting the flow of exhaust gas.

In this way it is possible to avoid the hassle of installing more than one conduit in parallel and to avoid the formation of lumps from the exhaust pipe due to vibrations, shocks or the like. becomes.

The present invention is based on a 3860cc diesel engine and a 15
The tests were carried out with an exhaust system in diesel mode consisting of a generator with a rated power of 40 KW at 0.00 rpm.

The length of one or two separation devices is 1000 mm.

It consisted of a steel cylinder with an inner diameter of 150 mm (two cylinders were arranged in parallel so that they could be operated simultaneously or alternately), and a steel rod with a diameter of 15 mm was installed at the axis.

A voltage of 30 KV and 0.5 mA was applied between the outer cylinder and the central steel rod. Each test was conducted by passing 500 liters of sample gas continuously for one hour. The sample gas that passed through the test device was passed through a porous filter, and the fine particles obtained there were weighed.

The results are shown in the table below.

The deposited soot was rapidly burned off by passing a 490°C air stream into the separate conduit.

If the exhaust gas is air-rich, the su\ will burn up during the separation process. Percentage strip count improved by 12 to 13 bonds.

Although the present invention has been described above in detail with reference to its preferred embodiments, it goes without saying that the present invention may be modified in many ways without departing from its spirit.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of one embodiment of the invention, and FIG. 2 is a cross-sectional view of a particulate removal section that can be removed from the rest of the exhaust/flue gas system. 1. Exhaust or flue gas pipe, 2. Conductor, 3.4
... Insulator, 5. External heater, 6. Conduit, 7. Deposition, 8. Insulator, 9. Conduit, lO.. Spark discharge or glow discharge plug, 11. Exhaust pipe, 12.
・Joints.

Claims (1)

[Scope of Claims] 1. A device for reducing particulates from exhaust or flue gas produced by combustion of fossil fuels, in which a high voltage generator and a particulate are electrostatically separated in a pipe through which the exhaust or flue gas passes. and means for removing collected particulates, the means for electrostatically separating said particulates comprising at least one pair of conductors between which exhaust and flue gases are passed; An apparatus characterized in that each is connected to a respective terminal of the high voltage generator. 2. The apparatus of claim 1, wherein the pair of conductors comprises two opposing walls in a conduit that are insulated from each other. 3. The device of claim 1, wherein one of the pair of conductors has at least one tip facing the other conductor,
Apparatus characterized in that the other conductor consists of a wall extending in front of one conductor from which it is electrically insulated. 4. The device according to claim 1, wherein one of the pair of conductors comprises the inner surface of a conduit, and the other conductor insulated therefrom is an elongated conductor extending along the axis of the conduit. Device. 5. Apparatus according to claim 1, characterized in that the means for removing particulates comprises means for increasing the temperature of the particulates and causing them to burn by the air-enriched exhaust gas itself or with the aid of air. 6. The apparatus of claim 1, wherein the means for removing particulates comprises a removable, interchangeable device that can be removed from the device to be cleaned and replaced with a similar cleaned device. Featured device. 7. Apparatus according to claim 5, characterized in that the means for increasing the temperature of the particulates comprises an auxiliary burner directing hot gas rich in oxidizing substances onto the particulates. 8. The device according to claim 5, wherein the means for increasing the temperature of the particulates comprises an electrical heating element that heats the particulates in the presence of a flow of a mixture of exhaust gas and air or air and exhaust gas. Featured device. 9. Device according to claim 8, characterized in that the electrical heating element comprises at least one spark discharge or glow discharge plug. 10. The apparatus of claim 1, wherein the exhaust gas is enriched with air during the particulate electrostatic precipitation process, thereby causing combustion of at least a portion of the particulates.