JP5867675B2 - Dust removal apparatus and method for exhaust gas - Google Patents

Description

  The present invention relates to an apparatus and method for removing dust from exhaust gas in a diesel engine.

Nitrogen oxides (NOx) are contained in exhaust gas from diesel engines, and application of a denitration device is being studied as regulations are tightened. As a denitration apparatus, an apparatus using a denitration reaction by a catalytic reduction method using a catalyst is promising.
However, the exhaust gas of diesel engines contains solids such as soot and dust such as SOF (soluble organic substances), and if this dust adheres to the catalyst surface of a denitration device, it causes a problem of catalyst performance degradation. There is. Therefore, in order to remove dust in the exhaust gas, removal using a DPF (diesel particulate filter) is performed in a vehicle diesel engine.

In order to avoid the increase in pressure loss due to the collected soot using a ceramic filter having a catalytic function, a method for regenerating the ceramic filter by combustion treatment at a high temperature of 500 ° C. or less has been proposed. (See Patent Document 1).
In addition, an electric machine dust collection method for collecting dust electrically by charging the dust has been proposed (see Patent Document 2).

JP-A-8-309151 JP 2000-130273 A

  However, when dust contained in diesel engine exhaust gas is removed by, for example, a DPF including a ceramic filter, it is necessary to remove dust accumulated on the DPF by high temperature combustion removal or so-called backwashing as shown in Patent Document 1. There is a problem that continuous regeneration of DPF, that is, continuous dust removal cannot be performed. For example, it is conceivable to divide the exhaust gas passage into two systems and install DPFs in the two exhaust gas passages respectively. However, regeneration and use of the DPF must be operated alternately. For example, in a marine diesel engine, There is not enough space to provide two exhaust gas passages in the ship, which is not preferable.

In addition, in the electric dust collection method and the cleaning dust collection method as shown in Patent Document 2, it is desirable to reduce the exhaust gas temperature to a low temperature of about 200 ° C. or less once. In that case, up to the operating temperature of the denitration catalyst installed downstream There is a problem that the gas temperature needs to be reheated and the system becomes complicated.
The present invention has been made to solve such problems, and the object of the present invention is to provide an exhaust gas that can be removed continuously and efficiently with a simple structure regardless of the temperature of the exhaust gas. An object of the present invention is to provide a dust removing apparatus and method.

In order to achieve the above object, an exhaust gas dust removing device of the present invention is interposed between a denitration catalyst device interposed in an exhaust passage extending from a diesel engine, and an exhaust upstream side of the denitration catalyst device in the exhaust passage. and a cyclone with the cyclone, the dust contained in the exhaust gas be one which centrifugation, have a dust discharging means for discharging the dust, the exhaust passage, a first exhaust passage and said And a turbocharger and a heat exchanger, and the turbocharger and the heat exchanger are configured so that the turbocharger is on the exhaust upstream side. The cyclone and the denitration catalyst device are interposed in the second exhaust passage, and the second exhaust passage is disposed in the first exhaust passage. The air passage branches from the exhaust upstream side of the turbocharger and merges at the exhaust upstream side or downstream side of the turbocharger, and switching adjustment is performed at a branch portion between the second exhaust passage and the first exhaust passage. A valve is interposed .

The exhaust gas dust removing device according to another aspect of the present invention includes a denitration catalyst device interposed in an exhaust passage extending from a diesel engine, and a cyclone interposed in the exhaust passage upstream of the denitration catalyst device. An exhaust gas dust removing device comprising: a cyclone for centrifuging dust contained in the exhaust gas, having a dust discharge means for discharging the dust; An exhaust passage and a second exhaust passage branching and joining to the first exhaust passage, and further comprising a turbocharger and a heat exchanger, wherein the turbocharger and the heat exchanger are exhausted upstream of the turbocharger. while interposed the first exhaust passage so that the side, the cyclone and the denitration catalyst device comprises is interposed the second exhaust passage, the rhino Ron consists of a plurality, and includes a plurality of switching valves for opening and closing the exhaust gas corresponding to the plurality of cyclones by opening and closing, and a control means for controlling the opening and closing of each of the plurality of switching valves, the exhaust passage is The exhaust gas upstream of the denitration catalyst device is branched in parallel into a plurality of branch passages corresponding to the plurality of cyclones, and each of the branch passages includes the cyclone and the switching valve, and the control means includes the diesel engine It includes load detecting means for detecting a load, and controlling the number of switching valves to be opened out of the plurality of the switching valve in accordance with the detected load by the load detecting means.

Further, the dust removing method of the exhaust gas of the present invention extends from a diesel engine, to have a denitration catalyst unit in an exhaust passage of a second exhaust passage that branches converging to a first exhaust passage and the first exhaust passage And a turbocharger and a heat exchanger, wherein the turbocharger and the heat exchanger are interposed in the first exhaust passage so that the turbocharger is on the exhaust upstream side, while the cyclone and the denitration The catalyst device is interposed in the second exhaust passage, and has dust discharge means for centrifuging dust contained in the exhaust gas and discharging the dust on the exhaust upstream side of the denitration catalyst device in the exhaust passage. A plurality of cyclones and a plurality of switching valves for opening and closing the exhaust gas in response to the plurality of cyclones by opening and closing, and the exhaust passage includes the denitration The exhaust gas upstream using the exhaust gas dust removal device that branches in parallel to the plurality of branch passages corresponding to the plurality of cyclones on the upstream side of the medium device, and has the cyclone and the switching valve in the branch passages, respectively. A method for removing dust, wherein the load of the diesel engine is detected, and the number of switching valves to be opened among the plurality of switching valves is controlled according to the detected load of the diesel engine, The number of cyclones through which exhaust gas circulates is changed among the cyclones.

  According to the exhaust gas dust removing device of the present invention, the cyclone for centrifuging dust contained in the exhaust gas is provided in the exhaust passage extending from the diesel engine and located upstream of the denitration catalyst device, and the dust collected by the cyclone is collected. Therefore, it is possible to continuously remove dust with a simple configuration regardless of the temperature of the exhaust gas, and to prevent the catalyst performance of the denitration catalyst device from being deteriorated.

  According to a preferred exhaust gas dust removal apparatus and method of the present invention, a plurality of cyclones and a plurality of switching valves are provided, and each of the plurality of cyclones and the plurality of switching valves is connected to a plurality of exhaust upstream sides of the denitration catalyst device. Provided in each of the branch passages, according to the load of the diesel engine, the number of switching valves that are opened among the plurality of switching valves is controlled to change the number of cyclones through which the exhaust gas of the plurality of cyclones circulates. Therefore, it is possible to remove dust continuously and efficiently with a simple configuration regardless of the exhaust gas temperature in the full load range regardless of the load of the diesel engine, and the catalyst performance of the denitration catalyst device is reduced. Can be prevented.

It is the schematic which shows the dust removal apparatus of the waste gas which concerns on 1st Example of this invention. It is the schematic which shows the front view (a) and upper view (b) of a cyclone. It is the schematic which shows the dust removal apparatus of the waste gas which concerns on 2nd Example of this invention. It is the schematic which shows the dust removal apparatus of the waste gas which concerns on 3rd Example of this invention. It is the schematic which shows the dust removal apparatus of the waste gas which concerns on 4th Example of this invention. It is the schematic which shows the 2nd exhaust passage of the dust removal apparatus of the waste gas which concerns on 5th Example of this invention. It is a figure which shows the relationship between the pressure loss ratio dP / dP0 of exhaust gas with respect to the process gas flow ratio of the exhaust gas in a cyclone, and the minimum separation particle diameter ratio d / d0 of the dust which can be removed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First embodiment]
FIG. 1 is a schematic view showing an exhaust gas dust removing apparatus according to a first embodiment of the present invention.
In the exhaust gas dust removing apparatus according to the first embodiment of the present invention, a turbocharger 4 is disposed in the first exhaust passage 2 of the diesel engine 1 as shown in FIG. A miser (heat exchanger) 6 is interposed. The turbocharger 4 is a supercharger that synchronously rotates a compressor by rotating a turbine with the pressure of exhaust gas and increases the intake air amount by supercharging the intake air to increase the intake efficiency. The economizer 6 is a device for recovering the heat of the exhaust gas by heat exchange and using it effectively.

The diesel engine 1 may be for vehicles or for ships, and is not limited to these applications.
Then, as shown in the figure, the exhaust gas downstream of the turbocharger 4 of the first exhaust passage 2 branches off from the economizer 6, that is, the exhaust of the economizer 6 with respect to the first exhaust passage 2. The second exhaust passage 3 extends so as to branch from the upstream side and merge on the exhaust downstream side of the economizer 6, and a denitration catalyst device 8 is interposed in the second exhaust passage 3, and further the denitration catalyst device. A cyclone 10 is interposed upstream of the exhaust 8. The denitration catalyst device 8 is a device that reduces and removes nitrogen oxides (NOx) in exhaust gas by denitration reaction by adding urea as a reducing agent, and the operating temperature is about 350 ° C.

  The cyclone 10 is an apparatus configured to swirl exhaust gas within a cylinder, as schematically shown in FIG. FIG. 2A is a front view of the cyclone 10, and FIG. 2B is a top view of the cyclone 10. As shown in the figure, the cyclone 10 is provided with an introduction port 14 for introducing exhaust gas into the cyclone main body 12 and an exhaust port 16 for exhausting exhaust gas from the cyclone main body 12, which are located in the upper part of the cyclone main body 12. A dust collecting bottle (dust discharging means) 18 is provided at a lower portion of 12.

Note that a switching adjustment valve that adjusts the flow of exhaust gas to the first exhaust passage 2 and the flow to the second exhaust passage 3 at a branch portion on the exhaust upstream side of the first exhaust passage 2 and the second exhaust passage 3. 20 is interposed. The switching adjustment valve 20 is, for example, an electromagnetic valve, and the switching adjustment valve 20 is electrically connected to an electronic control unit (not shown) for controlling switching.
With such a configuration, in the exhaust gas dust removing device according to the first embodiment of the present invention, the switching control valve 20 is controlled to be switched by the control device in accordance with, for example, the operating state of the diesel engine 1, and the exhaust gas is the first exhaust gas. When the switching control valve 20 is switched so as to flow to the passage 2, the economizer 6 recovers the heat of the exhaust gas. On the other hand, when the switching control valve 20 is switched so that the exhaust gas flows into the second exhaust passage 3, the exhaust gas flows through the cyclone 10 to the denitration catalyst device 8, and NOx is reduced and removed.

  In the cyclone 10, the exhaust gas introduced from the inlet 14 swirls along the inner wall surface of the cyclone body 12 according to the flow rate of the exhaust gas, and solids such as soot in the exhaust gas or dust such as SOF (soluble organic substance). Is centrifuged. The centrifugally separated dust descends on the funnel-shaped inner wall surface of the cyclone body 12 and is collected in the dust collection bottle 18. The dust collected in the collection bottle 18 is appropriately collected, for example, periodically and discarded. On the other hand, the exhaust gas after the dust is centrifuged is discharged from the discharge port 16 and returned to the second exhaust passage 3.

When the dust in the exhaust gas is removed in the cyclone 10 in this way, the dust in the exhaust gas is suppressed from flowing into the denitration catalyst device 8, and the dust is prevented from adhering and accumulating on the catalyst surface of the denitration catalyst device 8. Is done. That is, by providing the cyclone 10 on the exhaust upstream side of the denitration catalyst device 8 and providing the cyclone 10, the dust in the exhaust gas can be continuously removed with a simple configuration regardless of the temperature of the exhaust gas.
Thus, in the exhaust gas dust removing apparatus according to the first embodiment, when the exhaust gas flows through the second exhaust passage 3, the exhaust gas does not pass through the turbocharger 4, the cyclone 10 and the denitration catalyst device 8 and does not pass through the economizer 6. By reducing the pressure loss and reducing the burden on the diesel engine 1 while supercharging the intake air, the dust in the exhaust gas can be removed well and the catalyst performance of the denitration catalyst device 8 can be reduced. Can be prevented.

Urea added as a reducing agent to the denitration catalyst device 8 needs to be decomposed into ammonia in the denitration reaction, but it takes a certain amount of time until urea is decomposed into ammonia. Urea should be added upstream. As a result, urea can be sufficiently decomposed into ammonia in the cyclone 10.
The first exhaust passage 2, the second exhaust passage 3, and the cyclone 10 are preferably covered with a heat insulating material so that the temperature of exhaust gas flowing into the denitration catalyst device 8 can be prevented from being lowered.

[Second Embodiment]
FIG. 3 is a schematic view showing an exhaust gas dust removing apparatus according to a second embodiment of the present invention.
In the exhaust gas dust removing apparatus according to the second embodiment of the present invention, as shown in the figure, the second exhaust passage 103 is provided from the exhaust downstream portion of the turbocharger 4 of the first exhaust passage 2 via the switching adjustment valve 20. The second embodiment is different from the first embodiment in that the second exhaust passage 103 is joined to the first exhaust passage 2 on the exhaust upstream side of the economizer 6.
With this configuration, in the second embodiment, when the switching control valve 20 is switched so that the exhaust gas flows into the second exhaust passage 103, the exhaust gas flows to the denitration catalyst device 8 via the cyclone 10, and NOx is reduced and removed. Thereafter, the heat of the exhaust gas is recovered by the economizer 6.

  Thus, in the first embodiment, when the exhaust gas flows through the second exhaust passage 3, the exhaust gas only passes through the turbocharger 4, the cyclone 10, and the denitration catalyst device 8, whereas the exhaust gas according to the second embodiment. In this dust removing device, when the exhaust gas flows through the second exhaust passage 103, the exhaust gas passes through the turbocharger 4, the cyclone 10, the denitration catalyst device 8, and the economizer 6. Although the burden tends to increase, it is possible to continuously remove dust in the exhaust gas with a simple structure regardless of the temperature of the exhaust gas while supercharging the intake air and recovering the heat of the exhaust gas well. Thus, it is possible to prevent the catalyst performance of the denitration catalyst device 8 from being lowered.

[Third embodiment]
FIG. 4 is a schematic view showing an exhaust gas dust removing apparatus according to a third embodiment of the present invention.
In the exhaust gas dust removing apparatus according to the third embodiment of the present invention, as shown in the figure, the second exhaust passage 203 is provided from the exhaust downstream portion of the diesel engine 1 of the first exhaust passage 2 via the switching adjustment valve 20. The second and second exhaust passages 203 are different from the first and second embodiments in that the second exhaust passage 203 joins the first exhaust passage 2 on the exhaust upstream side of the economizer 6.
With this configuration, in the third embodiment, when the switching control valve 20 is switched so that the exhaust gas flows into the second exhaust passage 203, the exhaust gas does not flow to the turbocharger 4 and passes through the cyclone 10, and the denitration catalyst device 8. After the NOx is reduced and removed, the economizer 6 recovers the heat of the exhaust gas.

Thus, in the second embodiment, when the exhaust gas flows through the second exhaust passage 103, the exhaust gas passes through the turbocharger 4, the cyclone 10, the denitration catalyst device 8, and the economizer 6, so that the pressure loss is large. However, in the exhaust gas dust removing device according to the third embodiment, when the exhaust gas flows through the second exhaust passage 203, the exhaust gas passes only through the cyclone 10, the denitration catalyst device 8, and the economizer 6, and excess intake air is discharged. Although not supplied, the pressure loss is reduced and the burden on the diesel engine 1 is kept small, the exhaust gas heat is recovered well, and the dust in the exhaust gas is made simple regardless of the temperature of the exhaust gas. Can be removed continuously, and a reduction in the catalyst performance of the denitration catalyst device 8 can be prevented.
In addition, by adjusting the switching degree of the switching control valve 20, the exhaust gas may flow to the second exhaust passage 203 and to the turbocharger 4, thereby supercharging the intake air to some extent.

[Fourth embodiment]
FIG. 5 is a schematic view showing an exhaust gas dust removing apparatus according to a fourth embodiment of the present invention.
In the exhaust gas dust removing apparatus according to the fourth embodiment of the present invention, as shown in the figure, the second exhaust passage 303 is provided from the exhaust downstream portion of the diesel engine 1 of the first exhaust passage 2 via the switching adjustment valve 20. The second embodiment is different from the first to third embodiments in that the second exhaust passage 303 joins the first exhaust passage 2 on the exhaust upstream side of the turbocharger 4.

With this configuration, in the fourth embodiment, when the switching control valve 20 is switched so that the exhaust gas flows into the second exhaust passage 303, the exhaust gas flows to the denitration catalyst device 8 via the cyclone 10, and NOx is reduced and removed. After that, the turbocharger 4 supercharges the intake air, and the economizer 6 recovers the heat of the exhaust gas.
Thus, in the third embodiment, when the exhaust gas flows through the second exhaust passage 203, the exhaust gas only passes through the cyclone 10, the denitration catalyst device 8, and the economizer 6, while the exhaust gas according to the fourth embodiment In the dust removing device, when the exhaust gas flows through the second exhaust passage 303, the exhaust gas passes through the cyclone 10, the denitration catalyst device 8, the turbocharger 4, and the economizer 6. However, it is possible to continuously remove dust in the exhaust gas with a simple configuration regardless of the temperature of the exhaust gas, while supercharging the intake air and recovering the heat of the exhaust gas well, A decrease in the catalyst performance of the denitration catalyst device 8 can be prevented.

[Fifth embodiment]
In the exhaust gas dust removing apparatus according to the fifth embodiment of the present invention, as shown in FIG. 6, the second exhaust passage 3 of the first embodiment, the second exhaust passage 103 of the second embodiment, and the third Instead of the second exhaust passage 203 of the embodiment and the second exhaust passage 303 of the fourth embodiment, a second exhaust passage 403 is employed.
As shown in the figure, the second exhaust passage 403 has a plurality of branch passages branching and joining in parallel, and the cyclones 10 having the same processing capacity are configured in multiple stages in parallel. A switching valve 30 for shutting off is interposed. Thus, in the exhaust gas dust removing apparatus according to the fifth embodiment, the number of the cyclones 10 to be used is changed by changing the number of switching valves 30 to be opened according to the load of the diesel engine 1, that is, the exhaust gas flow rate correlated with the load. To change.

The dust processing capacity per cyclone 10 and the number of cyclones 10 are set according to, for example, the exhaust gas flow rate at the full load of the diesel engine 1 or the particle size of dust to be removed. A method for setting the processing capacity and number of dust will be briefly described.
Referring to FIG. 7, when the cyclone 10 is designed with a desired exhaust gas flow rate as a set value, the exhaust gas pressure loss ratio dP / dP 0 to the exhaust gas processing gas flow rate ratio and the minimum dust separation ratio d / d 0 of dust that can be removed. The relationship is shown.
Here, the pressure loss ratio dP / dP0 is the ratio of the pressure loss dP0 at the processing gas flow rate ratio 1.0 to the pressure loss dP at each processing gas flow rate ratio, and the minimum separation particle size ratio d / d0 is the processing gas This is the ratio between the minimum separated particle diameter d0 at a flow rate ratio of 1.0 and the minimum separated particle diameter d at each process gas flow rate ratio.

Generally, in a cyclone, dust with a larger particle size is easier to separate and remove. Therefore, the smaller the minimum separated particle size d, which is the smallest particle size, is, the higher dust removal performance is evaluated. In such a case, the minimum separation particle diameter d decreases as the processing gas flow rate increases. However, when the processing gas flow rate is increased, the pressure loss dP of the cyclone increases, and there is a drawback that, for example, the power consumption of the exhaust fan (not shown) increases.
That is, in FIG. 7, there is a trade-off relationship between the minimum separation particle diameter d and the pressure loss dP as described above, and in order to achieve both the target minimum separation particle diameter d and the pressure loss dP. , Indicating that there is an optimum range of process gas flow rates.

  As a result, the pressure loss dP is not increased as much as possible, so that the minimum separable particle diameter d of the dust that can be removed becomes as small as possible. That is, the pressure loss dP of the exhaust gas is in a predetermined pressure loss range and It is better to suppress the fluctuation range of the processing gas flow rate of the exhaust gas for each cyclone 10 so that it has the above-mentioned optimal range so that the separation performance of the cyclone 10 can be achieved. The allowable fluctuation range of the processing gas flow rate of the exhaust gas is determined so as to be within the above optimal range, and is appropriately set according to the allowable fluctuation range of the processing gas flow rate of the exhaust gas.

  Here, as shown in FIG. 6, eight cyclones 10 are set, and the second exhaust passage 403 includes, for example, eight branch passages 403a, 403b, 403c, 403d, 403e, 403f, 403g, and 403h. The cyclones 10a, 10b, 10c, 10d, 10e, 10f, 10g, and 10h are interposed in the branch passages 403a to 403h, respectively. Further, switching valves 30a, 30b, 30c, 30d, 30e, 30f, 30g, and 30h are interposed in the branch passages 403a to 403h, respectively. The switching valves 30a to 30h are electrically connected to an electronic control unit (ECU: control means) 50, respectively.

The ECU 50 is composed of a CPU and a memory, and is configured such that load information (engine load: accelerator opening, engine output, etc.) of the diesel engine 1 is input at least on the input side of the ECU 50 (load detection means), As described above, the switching valves 30a to 30h are connected to the output side.
Thereby, in the exhaust gas dust removing apparatus according to the fifth embodiment, the switching valves 30a to 30h opened by the ECU 50 are switched and controlled in accordance with the load of the diesel engine 1, that is, the exhaust gas flow rate, and the cyclones 10a to which the exhaust gas flows. 10h is appropriately selected. That is, in the fifth embodiment, the number of cyclones 10 through which exhaust gas flows is variably controlled between 1 and 8 according to the load of the diesel engine 1.

As described above, since eight cyclones 10a to 10h are provided here, when the total load of the diesel engine 1, that is, the maximum exhaust gas flow rate is set to 100%, and the total load is divided into eight equal parts, one cyclone 10 is used. The load of 12.5%, that is, the exhaust gas flow rate is shared. Accordingly, when the load of the diesel engine 1 is X%, the number obtained by dividing this X% by 12.5% and rounding up the fractional part is the number of cyclones 10 through which exhaust gas flows, and according to this number The switching valves 30a to 30h opened by the ECU 50 are controlled to be switched.
Specifically, when the load X% of the diesel engine 1 is 80%, for example, 80% / 12.5% = 6.4, and the number obtained by rounding up the fractional part is 7. Seven of the switching valves 30a to 30h, the switching valves 30a to 30g, are opened, the switching valve 30h is closed, and the exhaust gas flows to seven of the cyclones 10a to 10h up to the cyclones 10a to 10g. Like that. Actually, when the load of the diesel engine 1 fluctuates in the vicinity of 80%, for example, the pressure loss dP is within ± 15% and the minimum separation particle diameter d is 80% to 80% in each of the seven cyclones 10a to 10g. It is possible to control within a range of 115%.

Thus, according to the exhaust gas dust removing apparatus according to the fifth embodiment, the load on the diesel engine 1 is controlled by controlling the number of cyclones 10 through which exhaust gas flows according to the load of the diesel engine 1, that is, the exhaust gas flow rate. Regardless, over the entire load range, the cyclone 10 can continuously and efficiently remove dust having a small particle diameter while preventing the pressure loss of the exhaust gas from increasing.
Although the description of the embodiment of the dust removal device for exhaust gas according to the present invention is finished above, the present invention is not limited to the above embodiment.

For example, in the fifth example of the above embodiment, the number of cyclones 10 is eight, but the number of cyclones 10 is not limited to eight, and may be set appropriately as described above.
Further, in the fifth example of the above embodiment, the switching valves 30a to 30h are respectively installed on the exhaust upstream side of the cyclones 10a to 10h in the branch passages 403a to 403h. The control valve 50 may be controlled so that a switching valve is provided on each exhaust downstream side of the exhaust gas, or separately from the switching valves 30a to 30h, a switching valve is provided on each downstream side of the cyclones 10a to 10h. You may make it control by ECU50.

DESCRIPTION OF SYMBOLS 1 Diesel engine 2 1st exhaust passage 3, 103, 203, 303, 403 2nd exhaust passage 4 Turbocharger 6 Economizer 8 Denitration catalyst apparatus 10, 10a-10h Cyclone 18 Dust collection bottle (dust discharge means)
20 switching control valve 30a-30h switching valve 50 electronic control unit (ECU)
403a-403h Branch passage

Claims (3)

A denitration catalyst device interposed in an exhaust passage extending from the diesel engine;
A the denitration catalyst dedusting apparatus of an exhaust gas Ru and an interposed cyclone the exhaust upstream side of the apparatus of the exhaust passage,
The cyclone is
Centrifuge the dust contained in the exhaust gas,
Have a dust discharge means for discharging the dust,
The exhaust passage includes a first exhaust passage and a second exhaust passage that branches and merges with the first exhaust passage, and further includes a turbocharger and a heat exchanger.
The turbocharger and the heat exchanger are interposed in the first exhaust passage so that the turbocharger is on the exhaust upstream side, while the cyclone and the denitration catalyst device are interposed in the second exhaust passage. And
The second exhaust passage branches from the exhaust upstream side of the turbocharger with respect to the first exhaust passage and merges on the exhaust upstream side or downstream side of the turbocharger , and the second exhaust passage and the first exhaust passage The exhaust gas dust removing device is characterized in that a switching control valve is interposed at a branch portion with the exhaust passage. A denitration catalyst device interposed in an exhaust passage extending from the diesel engine;
A the denitration catalyst dedusting apparatus of an exhaust gas Ru and an interposed cyclone the exhaust upstream side of the apparatus of the exhaust passage,
The cyclone is
Centrifuge the dust contained in the exhaust gas,
Have a dust discharge means for discharging the dust,
The exhaust passage includes a first exhaust passage and a second exhaust passage that branches and merges with the first exhaust passage, and further includes a turbocharger and a heat exchanger.
The turbocharger and the heat exchanger are interposed in the first exhaust passage so that the turbocharger is on the exhaust upstream side, while the cyclone and the denitration catalyst device are interposed in the second exhaust passage. becomes Te,
Before Symbol cyclone is composed of a plurality,
A plurality of switching valves for opening and closing the exhaust gas in response to the plurality of cyclones by opening and closing, and a control means for controlling the opening and closing of each of the plurality of switching valves,
The exhaust passage branches in parallel to a plurality of branch passages corresponding to the plurality of cyclones on the exhaust upstream side of the denitration catalyst device, and each of the branch passages includes the cyclone and the switching valve,
The control means includes load detection means for detecting a load of the diesel engine, and controls the number of switching valves to be opened among the plurality of switching valves according to the load detected by the load detection means. A dust removal device for exhaust gas. Extending from a diesel engine, as well as have a denitration catalyst unit in the exhaust passage ing from the second exhaust passage for branching to the first exhaust passage and the first exhaust passage, and a further turbocharger and the heat exchanger The turbocharger and the heat exchanger are interposed in the first exhaust passage so that the turbocharger is on the exhaust upstream side, while the cyclone and the denitration catalyst device are interposed in the second exhaust passage. it is so, the dust contained in the exhaust gas corresponding to a plurality of cyclones and the plurality of cyclones with dust discharge means for discharging the dust with centrifuging the exhaust upstream side of the denitration catalyst unit of the exhaust passage A plurality of switching valves for opening and closing the exhaust gas through and shutting off, and the exhaust passage is arranged on the upstream side of the exhaust gas of the denitration catalyst device. The branches in parallel to a plurality of branch passages corresponding to a respective said cyclone and said exhaust gas using the exhaust gas of the dust removing apparatus comprising a switching valve dedusting method to the branch passage,
Detecting the load of the diesel engine;
According to the detected load of the diesel engine, the number of switching valves that are opened among the plurality of switching valves is controlled, and the number of cyclones through which exhaust gas flows is changed among the plurality of cyclones. A method for removing dust from exhaust gas.

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