JPH0736885B2 - Exhaust gas cooling / purification method and device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an exhaust gas recirculation system for a diesel engine, in which at least the exhaust gas discharged from the diesel engine and returned to the diesel engine is directly cooled by sea water spray and is contained in the exhaust gas. The present invention relates to a method for simultaneously and easily cooling and purifying exhaust gas by capturing soot and dust in seawater.

[0002]

2. Description of the Related Art It is well known that exhaust gas recirculation (hereinafter referred to as EGR) is one of the NOx reduction techniques for diesel engines. Also, the actual Kaihei 2-
In Japanese Patent No. 46057 and Japanese Utility Model Laid-Open No. 2-43449,
A trap filter for capturing soot and dust is provided in the exhaust gas recirculation passage of the EGR of the diesel engine, and further,
An EGR device that prevents clogging of this filter is described.

[0003]

The EGR device described in the above publication has the following problems. (1) In the above filter, clogging due to soot and dust occurs, and means such as combustion regeneration and air purging are used to remove this, but the pressure loss due to the filter fluctuates greatly between the clogging and regeneration of the filter. However, this adversely affects engine performance. In particular, it has a great influence when it is equipped with a supercharger. (2) When the filter is burned and regenerated, the temperature of the filter itself rises excessively, the filter is damaged, and when it cannot be incinerated sufficiently, carbon is sintered and the filter is clogged. (3) The technology for recovering the clogging of the filter is complicated, and a surely recoverable method has not yet been established. On the other hand, when the EGR is performed, soot and dust in the exhaust gas increase. Further, the exhaust gas which is subjected to EGR and is recirculated into the cylinder needs to be cooled to a predetermined temperature. The present invention has been made in view of the above points, and at the same time as directly cooling the exhaust gas that recirculates at least in a diesel engine with seawater spray, at the same time by capturing the soot and dust contained in the exhaust gas in seawater, the EGR of It is an object of the present invention to provide a method and an apparatus capable of solving all the problems.

[0004]

In order to achieve the above object, the exhaust gas cooling / purifying method of the present invention is the exhaust gas recirculation method for a diesel engine, wherein all or part of the exhaust gas that has passed through the supercharger. To a dedusting / cooling device containing seawater
It enters, discharges facing the sea surface, and jets from the top.
By supplying mist-like seawater and directly contacting the exhaust gas with seawater,
The feature is that at least the exhaust gas flowing back to the diesel engine is cooled and at the same time, the dust in the exhaust gas is captured in seawater. Further, in the method of this, dust contained in seawater after treatment, configured to remove by filtration and / or centrifugation or the like oil.

The exhaust gas cooling / purifying device of the present invention is connected to the main exhaust gas conduit 13 from the supercharger 12 or the recirculation exhaust gas conduit 15 in the exhaust gas recirculation system of the diesel engine 10, as described with reference to the drawings. At least diese
The dedusting / cooling device 16 for directly contacting the exhaust gas flowing back to the engine with the seawater is provided .
Is configured so that the sea surface has a constant height at the inner bottom,
Above the sea level, down the exhaust gas conduit 22 which is open is connected to, sea water spray tube 24 is configured to be provided on the upper side of the exhaust gas conduit 22. Further, in the apparatus of this consists in the lower portion of the seawater discharge pipe 28 of the de-dust and cooling unit 16 so as to provide a filter 32, 34 and / or oil-water separator 36.

[0006]

When all the exhaust gas that has passed through the supercharger 12 attached to the diesel engine 10 or the exhaust gas that is recirculated is introduced into the dedusting / cooling device 16 and discharged facing the sea level.
Both of them are in direct contact with the sprayed seawater and are efficiently cooled, and at the same time, soot and dust are efficiently trapped in the seawater. The seawater containing soot and dust after treatment is passed through filters 32, 34, etc. to remove soot and dust,
Then, the oil is sent to a purifier such as the oil / water separator 36 to remove the oil, and after being cleaned, it is discharged into the sea. In addition, the diesel engine alone can generate 100p of NOx in the exhaust gas.
It is difficult to reduce to around pm and usually requires a post-treatment device. Even in such a case, since the EGR can be performed by using the dust removal / cooling device 16, the post-processing device can be downsized and simplified.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the drawings. However, the shape of the constituent devices described in this embodiment, the relative arrangement thereof, and the like, unless otherwise specified, are not intended to limit the scope of the present invention only to them, but merely illustrative examples. Nothing more. Example 1 This is a basic example of the present invention, and as shown in FIG.
This is a method of treating all the exhaust gas discharged from the supercharger 12 and the exhaust gas economizer 14 attached to the diesel engine 10 by the dedusting / cooling device 16 of the present invention. The exhaust gas economizer 14 may not be installed. A part of the exhaust gas after the treatment is introduced into the seawater mist separator 18 to remove the seawater mist, and then, together with the atmosphere, the diesel engine 1
It is recirculated to the supercharger 12 attached to 0, and the rest of the exhaust gas is discharged. Reference numeral 13 is a main exhaust gas conduit, and 15 is a recirculation exhaust gas conduit.

FIG. 2 shows an example of the dedusting / cooling device 16 and its surroundings. The sea surface 30 is configured to have a constant height on the inner bottom of the device body 20.
The exhaust gas conduit 22 opening downward is connected to the upper side of the, and a seawater spray pipe 24 is provided above the exhaust gas conduit 22. 26 is an exhaust gas outlet and 28 is a seawater discharge pipe.
Since the exhaust gas is discharged facing the seawater surface 30, a part of the large particle dust in the exhaust gas is captured in the seawater. Dust that rises with the exhaust gas is captured by the spray seawater. Dust is removed from the seawater from which the exhaust gas has been washed by the primary filter 32 and the secondary filter 34,
Then, after the oil is removed by an oil / water separator 36 such as a centrifuge, it is returned to the sea. 38 is a seawater filter, 40
Is a seawater pump. In addition, instead of providing the two filters of the primary filter 32 and the secondary filter 34, the number of filters may be one or three or more. Further, a plurality of filters may be switchably connected in parallel.
In addition, a filter, an oil / water separator, or both may be provided. The seawater surface 30 at the bottom of the device main body 20 has a fixed height so that the exhaust gas inflow hole 4
The distance between 2 and the sea surface 30 is measured, and the bypass amount of the sea water discharge pump 44 is adjusted by the bypass line 46, for example. Instead of adjusting by the bypass amount, liquid level control means (LC) or the like can be provided. As described above, the reason why the exhaust gas is discharged facing the seawater surface is that the exhaust gas outlet pressure of the diesel engine exhaust gas is low and the pressure loss cannot be so large. Instead of discharging the exhaust gas so as to face the seawater surface, a straight tubular exhaust gas conduit may be connected to the side surface of the apparatus main body 20 so that the exhaust gas inflow hole faces in the lateral direction. But in this case,
The dust collection efficiency is slightly lower. If a large pressure loss of exhaust gas from a diesel engine can be obtained, the sea level 3
It is also possible to connect the exhaust gas conduit below 0. Further, instead of providing the seawater spray pipe 24, it is also possible to provide a shelf or fill a filling material.

The seawater mist separator 18 for preventing the seawater mist from entering the engine has a structure for removing the seawater mist by utilizing centrifugal force, a structure for removing the seawater mist by a filter, or the like. be able to. Further, as shown in FIG. 3, the reflux exhaust gas discharged from the dedusting / cooling device may be washed by spraying with fresh water to remove seawater mist contained in the reflux exhaust gas. The seawater discharged from the lower part is sent to a purification device, treated, and then discharged to the sea. 48 is a fresh water spray pipe.

Example 2 In Example 1 (FIG. 1), the entire amount of exhaust gas is treated with a dedusting / cooling device, whereas in this example, only the recirculated exhaust gas is dedusting / cooling as shown in FIG. After passing through the device 16, the others are discharged as they are into the atmosphere. In this embodiment, the device can be downsized as compared with the first embodiment, but the effect of reducing the amount of dust in exhaust gas is small. Other configurations and operations are the same as those of the first embodiment (see FIG.
Up to the case of FIG. 3).

Embodiment 3 In this embodiment, as shown in FIG. 5, an indirect seawater cooler 50 is provided in the reflux exhaust gas conduit in Embodiment 1 (FIG. 1). In the EGR, it is necessary to cool the gas temperature of the recirculated exhaust gas to near room temperature, but in the first embodiment, a large amount of seawater is required because it is performed only by the dedusting / cooling device, and the device becomes large. On the other hand, in the case of the present embodiment, the separately installed cooler 50 is provided to cool to a predetermined temperature, so that the cooling seawater amount of the dedusting / cooling device can be reduced and the device can be downsized. Can be achieved. Other configurations and operations are similar to those of the first embodiment (FIGS. 1 to 3).

Embodiment 4 In this embodiment, an indirect seawater cooler 50 is provided in the reflux exhaust gas conduit 15 after the dedusting / cooling device in Embodiment 2 (FIG. 4), as shown in FIG. It is a thing. Similar to the third embodiment (FIG. 5), this embodiment also aims to reduce the amount of cooling seawater of the dust removal / cooling device and to downsize the device. Other configurations and operations are similar to those of the first embodiment (FIGS. 1 to 3).

Embodiment 5 In this embodiment, as shown in FIG. 7, a denitrification / denitration device 52 or a denitration / denitrification is separately provided at the outlet (or the inlet) of the supercharger in Embodiment 3 (FIG. 5).・ With a desulfurizer,
This is an example aiming at further reduction of dust and NOx (due to the EGR effect). In this case, dedusting / denitration device 5
In the case of No. 2, by providing the dust removal / cooling device 16, the size and simplification can be achieved as compared with the case where the device is installed alone. Other configurations and operations are similar to those of the first embodiment (FIGS. 1 to 3).

Embodiment 6 In this embodiment, as shown in FIG. 8, a denitrification / denitration device 52 or a denitration / denitrification is separately provided at the supercharger outlet (or the inlet) in the embodiment 4 (FIG. 6).・ With a desulfurizer,
This is aimed at the same effect as that of Example 5 (FIG. 7). Other configurations and operations are similar to those of the first embodiment (FIGS. 1 to 3).

[0015]

Since the present invention is configured as described above, it has the following effects. (1) All of the exhaust gas or recirculated exhaust gas to the sea surface
As it is discharged, it also supplies atomized seawater from the top.
Since the exhaust gas and the seawater are in direct contact, the exhaust gas is efficiently
Can be cooled efficiently and removed efficiently.
It ( 2 ) At least the exhaust gas recirculating to the diesel engine is cooled and washed with seawater to cool the exhaust gas recirculation.
At the same time , the soot and dust contained in the exhaust gas can be easily captured in seawater. As a result, soot and dust can be removed by a commonly used filter, cleaning material, etc. without requiring a complicated device for treating the seawater after cooling and washing. For this reason, re-especially of diesel engines in the ship
Suitable for use in circulating exhaust gas treatment. ( 3 ) When removing dust and soot from the exhaust gas using a filter or the like, a pressure loss is inevitably generated. However, by using the dedusting / cooling device of the present invention, clogging does not occur, so pressure loss is caused. Hardly occurs, and there is almost no pressure fluctuation . (4) Since the present invention enables exhaust gas recirculation , the amount of NOx emitted from the engine is reduced.
When the post-processing device is provided, the device can be downsized and simplified.

[Brief description of drawings]

FIG. 1 is a system explanatory view showing an embodiment of an exhaust gas cooling / purifying apparatus of the present invention.

FIG. 2 is a system explanatory view showing an example of the dedusting / cooling device in FIG. 1 and its surroundings.

FIG. 3 is an explanatory diagram showing an example of the seawater mist separator in FIG.

FIG. 4 is a system diagram showing another embodiment of the device of the present invention.

FIG. 5 is a yarn thread explanatory diagram showing another embodiment of the device of the present invention.

FIG. 6 is a system diagram showing another embodiment of the device of the present invention.

FIG. 7 is a system diagram showing another embodiment of the device of the present invention.

FIG. 8 is a system diagram showing still another embodiment of the device of the present invention.

[Explanation of symbols]

 10 Diesel Engine 12 Supercharger 13 Main Exhaust Gas Pipe 14 Exhaust Gas Economizer 15 Reflux Exhaust Gas Pipe 16 Dedusting / Cooling Device 18 Sea Water Mist Separator 20 Equipment Main Body 22 Exhaust Gas Pipe 24 Sea Water Spray Pipe 26 Sea Gas Discharge Pipe 30 Sea Water Surface 32 1 Secondary filter 34 Secondary filter 36 Oil-water separator 38 Seawater filter 40 Seawater pump 42 Exhaust gas inflow hole 44 Seawater discharge pump 46 Bypass line 48 Fresh water spray pipe 50 Cooler 52 Dedusting / denitrification equipment

Continuation of the front page (56) References JP-A-57-68121 (JP, A) JP-A-60-44018 (JP, A) Actually developed JP-A-58-171220 (JP, U)

Claims (4)

[Claims] 1. An exhaust gas recirculation method for a diesel engine, wherein all or part of the exhaust gas passing through the supercharger is introduced into the seawater.
Introduced into the dedusting and cooling device, and discharged facing the sea surface
At the same time, the atomized seawater is supplied from the top, and the exhaust gas
Direct contact with seawater to at least the diesel engine
Cooling the exhaust gas that recirculates, and at the same time, trapping soot and dust in the exhaust gas in seawater.
Purification method. 2. A dust contained in seawater after treatment, cooling and purifying method of an exhaust gas according to claim 1, wherein the removal by filtration and / or centrifugation or the like oil. 3. A main exhaust gas conduit (1) from a supercharger (12) in an exhaust gas recirculation system of a diesel engine (10).
3) or connected to the reflux exhaust gas conduit (15) and at least
Is equipped with a dedusting / cooling device (16) that makes direct contact between the exhaust gas flowing back to the diesel engine and seawater.
The cooling device (16) has a constant sea level at the inner bottom.
And a drainage opening downwards above the sea level.
A gas conduit (22) is connected to this exhaust gas conduit (22)
An exhaust gas cooling / purifying device, characterized in that a seawater spray pipe (24) is provided on the upper side of the . 4. A filter (32), (34) and / or an oil / water separator (36) is provided in the seawater discharge pipe (28) below the dedusting / cooling device (16).
Exhaust gas cooling / purification device described in 3 .