JPH05141219A - Device for removing particulate in exhaust - Google Patents

Abstract

PURPOSE:To provide a particulate removing device wherein an organic cut in exhaust can be reduced to be discharged to the atmosphere without decreasing a heat transfer coefficient in a heat collecting part at the time of both low and high loads. CONSTITUTION:A filter element 12 is arranged in a flow path of exhaust 11 where exhaust of containing particulate and an organic cut flows, to provide a means for adjusting a temperature of the filter element 12. This means is inserted through or brought into contact with the filter element 12 to arrange a heat transfer pipe 18 in the inside of which a heating medium flows. In addition to the heat transfer pipe 18, a heat transfer element of heat pipe or the like is used. The filter element 12 is cooled at the time of a high load, and the organic cut is changed into a mist and captured in a particulate filtering part to reduce a discharge of the cut to the atmosphere.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for removing particulate matter from exhaust gas, and more particularly to an exhaust gas suitable for removing particulates and organic fractions contained in high temperature combustion exhaust gas discharged from boilers, internal combustion engines and the like. Of the fine particle removing device

[0002]

2. Description of the Related Art In the exhaust gas of an internal combustion engine such as a diesel engine or a combustion apparatus such as a boiler, carbon, which causes environmental pollution, and fine particles containing ash in fuel, that is, soot and dust, are cooled. It contains mist, that is, vapor of an organic fraction that becomes liquid fine particles. Among the organic fractions, soluble organic fractions, namely SOF (Soluble Org)
There are particularly many substances called anic Fraction). The soluble organic fraction is a combustion emission substance mainly composed of hydrocarbons having about 10 to 20 carbon atoms, which is composed of unburned lubricating oil, unidentified combustion products and the like. The vaporization temperature of the soluble organic fraction is generally in the range of 150 ° C to 45 ° C.

In order to reduce the release of such fine particles and organic fractions into the atmosphere, the Air Pollution Control Law Enforcement Ordinance and its enforcement regulations were amended and enforced from 1988, and the regulations of the law were strengthened. ing.

As a device for removing fine particles, an exhaust inlet 10 and a purified gas outlet 1 as shown in FIG. 14 are attached to a relatively small engine mounted on an automobile or the like.
It is proposed that a columnar or plate-shaped filter element 43 is arranged in a casing 15 provided with 3, and a buffer material 16 is provided on the outer periphery thereof to filter fine particles contained in exhaust gas with the filter element 43. ing. Filtration element 43
As a material used in the above, a ceramic foam, a metal foam, a fired body of ceramic or metal, a woven cloth, a fiber molded body, or the like, which has a three-dimensional network minute path, is known.
The fine particles captured on the filter element 43 are incinerated by the action of the oxidation catalyst carried therein or by an incinerator such as a burner installed separately. However,
The exhaust particles emitted from diesel engines and the like are often particles of a few microns or less. Therefore, although it is necessary to form the element with a fine mesh material, it is important to minimize the flow resistance in order to maintain the engine efficiency.

For that purpose, it is necessary to reduce the flow velocity of the exhaust gas and to widen the ventilation area of the filtering portion. However, in the conventional device as shown in FIG. 14, the device size per engine output becomes relatively large. Not preferable. In view of these points, a filter element 44 having a honeycomb structure as shown in FIGS. 15 and 16 has been proposed. Multiple small channels or cells 47
In the honeycomb structure constituted by, the adjacent cells 47 on the inlet side end surface 45 and the outlet side end surface 46 are alternately sealed with the sealing material 49. At this time, the cell 47 sealed on the inlet side is open on the outlet side, and the cell 47 sealed on the outlet side is open on the inlet side. The exhaust gas 11 penetrates through the cell wall 48 from the cell whose inlet side is open, and reaches the adjacent outlet side open cell.

In this device, the fine particles are trapped mainly on the surface of the cell wall 48. With such a structure, the filtration area increases proportionally as the length of the honeycomb in the flow direction increases. Therefore, it is advantageous in securing the necessary filtration area without making the exhaust pipe cross section too large. However, since such a honeycomb-type filtration element is integrally manufactured by a method such as extrusion molding, it is difficult to increase the size, the size of the cell is limited, and the amount of fine particles deposited in the cell is reduced. If the amount is uneven or the amount is too large, the element may be burnt or damaged due to temperature distribution during the incineration process, and even if the cell is partially damaged, it is necessary to replace the entire element. It also has drawbacks.

On the other hand, as a fine particle removing device for a large-scale fixed equipment, the structure shown in FIG. 17 is usually adopted regardless of which of the above-mentioned elements is used as the fine particle filtering section. Exhaust gas 11 emitted from the diesel engine 1 connected to the generator 2 is reduced in particulate matter in the exhaust gas by the particulate filter section 50, and is normally discharged from the chimney 7 through the heat recovery section 6. A differential pressure detector 9 that measures the differential pressure between the upstream side and the downstream side of the particulate filter 50 is used to detect clogging in the particulate filter 50. When clogging of the filtration unit is detected, the damper 29 is opened, and, for example, high temperature gas is supplied from the burner 28 to incinerate the fine particles deposited on the fine particle filtration unit 50.

On the other hand, the diesel engine 1 is equipped with a water cooling jacket 3 and is supplied with water 22 via a pump 8.
Is cooled by. Further, the water supply 22 is discharged as hot water 26 from the water cooling jacket 3, and a part or all of the water is supplied to the heat transfer pipe 51 of the heat recovery section via the heat recovery inlet valve 20 and acts as a heat medium for heat recovery. , Hot water or steam 21 of higher temperature.

[0009]

As described above, the exhaust contains the organic fraction in addition to the fine particles of carbonaceous matter and ash. This organic fraction is steam when the temperature of the exhaust gas is high,
When it is low, it exists as mist. Since the exhaust gas temperature is low when the diesel engine is started or when the load is low, most of the fine particles and the organic fraction are captured in the particulate filter 50, but the exhaust gas temperature becomes high during the high load operation, and the organic fraction of the previous period becomes high. Most of the permeation passes through the particulate filter 50 as vapor and is released to the atmosphere.

On the other hand, although a heat recovery section is installed downstream of the fine particle filtration section 50, the surface temperature of the heat transfer tube is often lower than the temperature at which the organic fraction is condensed. Therefore, a part of the organic fraction adheres to the surface of the heat transfer tube and further promotes the adhesion of fine particles not captured in the filtration section, increasing the contamination of the heat transfer tube and significantly reducing the heat transfer coefficient.

The object of the present invention is not to reduce the heat transfer coefficient of the heat recovery part, but to reduce the organic fraction not only during low exhaust temperature startup or low load but also during high load operation with high exhaust temperature. It is an object of the present invention to provide a device for removing particulate matter in exhaust gas that can reduce discharge to the atmosphere.

[0012]

The above object can be achieved by arranging a filter element in an exhaust passage through which exhaust gas containing fine particles and an organic fraction flows, and adjusting the temperature of the filter element, mainly cooling. As the temperature adjusting means of the filtration element, the filtration element is penetrated, or in contact with the filtration element, a heat transfer tube through which a heat medium flows is arranged inside, or one end thereof penetrates the filtration element or is in contact with the filtration element. A means for arranging a heat transfer element such as a heat pipe whose other end is located outside the casing is adopted.

[0013]

[Function] During high-load operation at a high exhaust temperature, most of the organic fraction supplied as vapor to the particulate filter becomes a mist when it is cooled, is captured by the particulate filter, and is discharged to the atmosphere. The quantity is reduced.

Further, since the mist adhered to the filtration element facilitates the capture of fine particles composed of carbonaceous matter and ash, the discharge amount of the fine particles themselves is also reduced. In addition, the heat recovery tube heat transfer tube disposed downstream of the particle filtering section is less contaminated and the heat transfer coefficient is less deteriorated, so that the thermal efficiency of the entire system can be improved.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. In the first embodiment shown in FIG. 1, the same components as in the prior art shown in FIG. 17 are designated by the same reference numerals. The fine particle removing device 5 is installed in the exhaust passage 4 of the diesel engine 1. A heat recovery unit 6 is arranged downstream of the particle removal device 5. The particulate removing device 5 mainly includes an exhaust inlet 10
And a filter element 12 and a heat transfer tube 18. The filter element 12 is held in the casing 15 by a cushioning material 16. From the viewpoint of heat transfer, it is preferable that the filter element 12 is made of a material having a high thermal conductivity.
The filtration element 12 carries an oxidation catalyst typified by metal oxides, noble metals and the like.

.. In the present embodiment, the heat transfer tubes 18 are arranged so as to penetrate through the filtration element 12, but in order to increase the heat transfer area and enhance the cooling capacity, it is preferable to form a tube group as shown in FIG.

On the other hand, as described above, the diesel engine 1
It is equipped with a water cooling jacket 3 and is cooled by water supply 22 supplied via a pump 8. Further, the water supply is discharged from the water cooling jacket 3 as hot water 26, a part of which is supplied to the heat transfer tube 51 of the heat recovery section 6 and acts as a heat medium for heat recovery to become hot water or steam 21 of higher temperature. ..
Further, the hot water 26 is used as the heat transfer tube 18 in the particle removing device 5.
Will also be supplied. The heat transfer tubes 18 and 51 are provided with a filter element inlet valve 17 and a heat recovery unit inlet valve 20, respectively. A temperature detector 52 is installed to monitor the temperature of the differential pressure detector 9 and the temperature of the filtration element 12 in order to detect the differential pressure of the exhaust gas inlet / outlet in the particulate removal device 5. Incidentally, 24 and 25 are bypass valves.

Next, the operation of the first embodiment constructed as above will be described. Exhaust gas containing fine particles and organic fraction vapor 1
1 is supplied to the exhaust inlet of the particle removing device 5. On the other hand, the hot water 26 is supplied to the heat transfer tube 18 as a heat medium for cooling, and the filtration element 12 around the heat transfer tube 18 is cooled. Therefore, the organic fraction vapor in the exhaust gas that has touched the filter element 12 is liquefied and becomes mist, and is captured by the filter element 12 together with the fine particles composed of carbonaceous matter and ash. Purified gas with reduced fine particles and organic fraction 14
Is discharged from the purified gas outlet 13, passes through the heat recovery section 6, and is discharged from the chimney 7 to the atmosphere.

Since the fine particles and the organic fraction have already been reduced in the heat recovery section 6, the heat transfer tube 51 is not polluted and the heat transfer coefficient is not reduced. When the differential pressure detector 9 detects that the differential pressure of the particulate removing device 5 exceeds the allowable value, the filtration element inlet valve 17 is adjusted by observing the time when the exhaust gas temperature is high and the load is high. The flow rate of hot water in 18 is reduced, or the supply of hot water is stopped to raise the surface temperature of the filtration element 12 and the heat transfer tube 18. As a result, the oxidation catalyst carried by the filtration element 12 is made to function, the fine particles and the organic fraction captured by the filtration element 12 are burned, and the filtration element 12 can be regenerated.

In the present embodiment, since the oxidation catalyst is carried on the filter element 12, the filter element 12 can be regenerated without requiring a special heat source for regenerating the filter element, and an economically excellent apparatus can be provided. Can be provided.

During regeneration of the filter element, the temperature of the filter element 12 is detected by the temperature detector 52, and the flow rate of hot water in the heat transfer tube 18 is adjusted by the filter element inlet valve 17 to prevent the filter element 12 from burning. It can be prevented. Further, in this embodiment, the preheated water to be supplied to the heat recovery unit 6 is partially branched and supplied to the heat transfer tube 18, but air or another fluid may be used as the heat medium in the heat transfer tube 18.

A second embodiment of the present invention is shown in FIG. Second
In the embodiment of the present invention, in regenerating the filter element 12, the electric heater 27 for igniting the particulate matter and the organic fraction accumulated in the filter element 12 is provided.
Since it is provided on the upstream side of 2, the ignition operation for incineration regeneration can be surely performed. The parts other than the above-mentioned structure are the same as those in the first embodiment.

A third embodiment of the present invention is shown in FIG. In the present embodiment, when regenerating the filtration element 12,
A burner 28 is attached upstream of the particle removing device, and the damper 2
Filter element 1 for hot gas through
The temperature distribution of the filter element 12 at the time of regeneration is relatively uniform, so that partial burnout or damage of the filter element 12 can be prevented.

A fourth embodiment of the present invention is shown in FIG. In this embodiment, the electric resistor 31 is arranged around the heat transfer tube 18 penetrating the filtration element 12. Filtration element 1
Not only is it possible to rapidly heat and raise the temperature at the time of incineration and regeneration of No. 2, but it is particularly effective for incineration of fine particles and organic fractions accumulated in large amounts in the vicinity of the heat transfer tube 18.

FIG. 6 shows a fifth embodiment of the present invention. In the present embodiment, the filtration element 12 is provided with γ-alumina, zeolite, etc. on the upstream side of the oxidation catalyst supporting portion 33 formed around the heat transfer tube 18 through which the heat mediums 19a and 19b flow, as viewed from the exhaust flow direction. The organic fraction adsorbent supporting portion 32 typified by the above is arranged. Since the adsorbent adsorbs or releases the organic fraction under a predetermined temperature condition, it is possible to average the reaction load of the oxidation catalyst arranged in the downstream portion of the oxidation catalyst supporting portion 32, and further, the filtration element. It is possible to prevent partial burnout or damage of 12. Further, it is possible to suppress the release of the organic fraction to the atmosphere regardless of the exhaust gas temperature.

FIGS. 7 and 8 show an embodiment of the essential part of the sixth embodiment of the present invention, in which the filter element is divided into a plurality of blocks 34, and the heat transfer tube 18 is provided in a part or all of the blocks 34.
Are arranged. In the present embodiment, even if a temperature distribution is generated in the filtration element, it is possible to prevent the element from being destroyed by thermal stress with minimum difficulty. Also, FIG.
If the filter element blocks 34 are stacked and arranged in a zigzag arrangement as shown in FIG. 5, blow-through of the exhaust gas 11 in the filter element can be prevented, and the purified gas 14
Is discharged as.

FIG. 9 shows a seventh embodiment of the present invention, in which the filter element and the heat transfer tube do not necessarily have to be integrated, and a plurality of filter element blocks 35 are spaced in the exhaust flow direction. The heat transfer tubes 18 may be arranged in the gap between the filter element blocks 35. At this time, if the filtration element block 35 and the heat transfer tube 18 are placed in contact with each other, the cooling effect of the filtration element block 35 by the heat transfer tube 18 can be maintained.

The filter element block can have not only the structure shown in FIG. 7 but also various structures shown in FIGS. 10 to 12. 10 and 11 show one filter element block 36, 37 in which a plurality of heat transfer tubes 18 to which the heat medium 19 is supplied are arranged, and FIG. 12 uses a corrugated plate 38 as a filter element. In the example of FIG. 12 using the corrugated plate 38, the unit blocks are stacked to form a honeycomb block.

The filter element having such a structure is mainly suitable for reducing the organic fraction, has a low pressure loss, and is hardly clogged. Depending on the material of the filter element, the filter element and heat transfer tube can be integrated.
Various methods such as pipe expansion, pressure bonding, brazing, welding, bonding with an adhesive and casting molding are adopted. A seventh embodiment of the present invention is shown in FIG. In this embodiment, the heat pipe 39 is used as the cooling element of the filtration element. The heat pipe 39 is a heat transfer element that seals the working fluid in the tube excluding the non-condensable gas and transfers the working fluid by evaporation and condensation. The heat pipe 39 has a heat absorbing portion 40 at one end and a heat radiating portion 41 at the other end. In this embodiment, the heat pipe 39 is arranged such that one end of the heat pipe 39 penetrates the filter element 12 or is in contact with the filter element 12 and the other end is located outside the casing 15. The cooling means 42 is added to the portion located on the outer side of. In the present embodiment, the piping of the heat medium is not necessary, and the system is simplified by utilizing a phenomenon such as natural convection as the cooling means.

[0030]

EFFECTS OF THE INVENTION According to the present invention, the organic fraction supplied as vapor is also cooled to form a mist and captured by the fine particle filtration unit, so that the exhaust temperature is not limited to when the engine is started or when the load is low. Emissions of organic fractions to the atmosphere can be reduced even during high-load operation at high temperatures.

Further, since the mist adhered to the filter element promotes the capture of fine particles composed of carbonaceous matter and ash, the emission of fine particles is further reduced. In addition, the heat recovery unit disposed downstream of the particulate filtration unit is less contaminated, the heat transfer coefficient is less reduced, and the thermal efficiency of the entire system can be improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of a fine particle removing apparatus according to the present invention.

FIG. 2 is a cross-sectional view taken along the line A-A ′ of FIG.

FIG. 3 is a schematic configuration diagram showing a second embodiment of the present invention.

FIG. 4 is a schematic configuration diagram showing a third embodiment of the present invention.

FIG. 5 is a schematic configuration diagram showing a fourth embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of a main part showing a fifth embodiment of the present invention.

FIG. 7 is a perspective view of an essential part showing a sixth embodiment of the present invention.

8 is a cross-sectional view showing an example of use of the filtration element block of FIG.

FIG. 9 is a cross-sectional view showing one mode of a filtration element block.

FIG. 10 is a cross-sectional view showing another aspect of the filtration element block.

FIG. 11 is a cross-sectional view showing still another aspect of the filtration element block.

FIG. 12 is a cross-sectional view showing still another aspect of the filtration element block.

FIG. 13 is a schematic configuration diagram showing a seventh embodiment of the present invention.

FIG. 14 is a cross-sectional view of essential parts showing a conventional particulate matter removing device.

FIG. 15 is a main part perspective view showing another example of a conventional particulate matter removing device.

16 is a cross-sectional view taken along the line B-B ′ of FIG.

FIG. 17 is a schematic configuration diagram showing an example of a conventional particulate matter removing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Diesel engine 2 Generator 3 Water cooling jacket 5 Fine particle removal device 6 Heat recovery part 9 Differential pressure detector 12 Filtration element 15 Casing 16 Buffer material 18 Heat transfer tube 19a Heat medium 19b Heat medium 27 Electric heater 28 Burner 31 Electric resistor 32 Adsorption Material support part 33 Oxidation catalyst support part 34, 35, 36, 37 Filtration element block 39 Heat pipe 40 Endothermic part 41 Heat dissipation part 42 Cooling means

Claims (8)

[Claims] 1. A device for removing particles in exhaust gas, wherein a filter element is arranged in an exhaust flow path through which exhaust gas containing particles and organic fraction flows, and the filter element captures and removes the particles and organic fraction in exhaust gas. A device for removing particulates in exhaust gas, comprising temperature adjusting means for adjusting the temperature of the filtration element. 2. The particulate matter removing device for exhaust gas according to claim 1, wherein the filtration element carries an oxidation catalyst of metal oxides, precious metals and the like. 3. The particulate matter in the exhaust gas according to claim 2, wherein an organic fraction adsorbing material such as γ-alumina or zeolite is arranged upstream of the oxidation catalyst supporting portion in the filtration element in the exhaust gas flow direction. Removal device. 4. A heat transfer pipe is arranged in the casing having an exhaust gas inlet and a purified gas outlet, and penetrates the filter element or is in contact with the filter element and has a heat medium flowing therein. The device for removing particulate matter in exhaust gas according to claim 1, wherein 5. The fine particle removing apparatus according to claim 1, wherein the temperature adjusting means is provided with a device for cooling the filtration element and a device for heating the filtration element, respectively. 6. The device for removing particulate matter in exhaust gas according to claim 4, wherein the filter element is divided into a plurality of blocks, and a heat transfer tube is arranged in a part or all of the block. 7. A heat having a filter element disposed in a hex having an exhaust gas inlet and a purified gas outlet, one end of which penetrates the filter element or is in contact with the filter element and the other end of which is located outside the casing. The device for removing particulates in exhaust gas according to claim 1, wherein a pipe is installed, and a cooling means is attached to a portion of the heat pipe located outside the casing. 8. The particulate matter removing apparatus according to claim 4, wherein a means for introducing a high-temperature gas for incinerating or reducing the particulate matter and the organic fraction captured by the filtration element is provided in the casing.