DE102011004792A1 - Nitrogen oxide elimination system for absorbing and eliminating nitrogen oxide in exhaust gas of internal combustion engine, comprises nitrogen oxide elimination unit, which holds nitrogen oxide absorption fluid for absorbing nitrogen oxide - Google Patents

Abstract

The nitrogen oxide elimination system comprises a nitrogen oxide elimination unit (30), which holds the nitrogen oxide absorption fluid for absorbing nitrogen oxide coming into contact with the nitrogen oxide absorption fluid. The nitrogen oxide is absorbed and eliminated into the exhaust gas of an internal combustion engine (10), in which the exhaust gas and the nitrogen oxide absorption fluid are brought in contact with one another. A carbon dioxide elimination unit (20) is provided at an exhaust tube (11) of the internal combustion engine.

Description

The present invention relates to a NOx removing system for an internal combustion engine, wherein the NOx removing system absorbs and eliminates NOx in the exhaust gas of the internal combustion engine by establishing contact between the exhaust gas and a NOx absorbing liquid.

Conventionally, as known devices for removing NOx in exhaust gas, there are, for example, a device using a NOx occlusion reduction catalyst and a device using a selective urea reduction catalyst. The NOx occlusion reduction catalyst reduces occluded NOx by using HC as a reducing agent, which is generated by periodically performing rich combustion in an internal combustion engine (see Patent Document 1: JP-A-2008-82315 ). The selective urea reduction catalyst selectively reduces NOx in the exhaust gas by using urea as a reducing agent (see Patent Document 2: JP-A-2009-281294 ).

However, these devices have a disadvantage in that the reduction function can not be applied until the temperature has risen to a temperature at which the catalyst is activated (for example, 200 ° C). In addition, there has been a tendency in recent years to incorporate low temperature combustion and exhaust heat recovery technologies. Therefore, the disadvantages described above are amplified, in particular during startup of the internal combustion engine.

The inventors of the present invention have studied a following apparatus using a system completely different from the systems of Patent Document 1 or 2 which reduces NOx by the catalyst. The device under investigation holds a liquid (NOx absorption liquid) capable of absorbing NOx which comes in contact with the liquid. The device absorbs and eliminates NOx in the exhaust gas in which contact between the liquid and the exhaust gas is caused. As the NOx absorbing liquid, for example, an ionic liquid, an aqueous alkali solution, water or the like can be used. Such NOx absorbing liquid can absorb NOx even at normal temperature. Therefore, the apparatus can eliminate the above-mentioned disadvantage of the conventional art which can not eliminate NOx until the catalyst activation temperature is reached.

However, the inventors have found that the following problem occurs in the system using the NOx absorbing liquid. That is, the NOx absorption liquid not only absorbs NOx but also CO2 in the exhaust gas. Whereas, the NOx concentration in the exhaust gas of the internal combustion engine is 0.1% or less, moreover, the CO2 concentration is in the range of several percent to several tens of percent. Therefore, there is a problem that the absorption of CO2 in the absorption of NOx in the absorbing liquid becomes dominant and NOx can not be satisfactorily absorbed.

It is an object of the present invention to provide a NOx removing system for an internal combustion engine which employs a system which absorbs and eliminates NOx in the exhaust gas by using a NOx absorbing liquid and which is capable of sufficiently absorbing NOx .

According to a first exemplary aspect of the present invention, a NOx removing system for an internal combustion engine has a NOx removing device and a CO2 removing device. The NOx removing device holds a NOx absorbing liquid which absorbs NOx, which comes into contact with the NOx absorbing liquid. The NOx removing device absorbs and eliminates NOx in the exhaust gas of the internal combustion engine by bringing the exhaust gas and the NOx absorbing liquid into contact with each other. The CO2 removing device is provided on an exhaust pipe of the internal combustion engine upstream of the NOx removing device and removes CO2 in the exhaust gas.

According to the above-described aspect of the present invention, the CO2 removing device is provided on the exhaust pipe upstream of the NOx removing device. Therefore, the exhaust gas whose CO2 concentration has been reduced by the CO2 removing device can be sent to the NOx removing device. Thus, an amount of CO2 absorbed by the NOx absorbing liquid held in the NOx removing device can be reduced. Further, a sufficient amount of NOx can be absorbed into the NOx absorbing liquid.

According to a second exemplary aspect of the present invention, the CO2 removing device holds a CO2 absorbing liquid that absorbs CO2 that is in contact with the CO2 absorbing liquid. The CO2 removing device absorbs and removes CO2 in the exhaust gas of the internal combustion engine by bringing the exhaust gas and the CO2 absorbing liquid into contact with each other.

The CO2 absorption liquid can absorb CO2 even at normal temperature. In contrast to the above-described aspect of the present invention, if as the CO2 removing device, a device that reduces and eliminates CO2 on a catalyst using a reducing agent is used, a problem arises that the CO2 can not be removed until the catalyst reached the activation temperature. In this regard, according to the above-described aspect of the present invention, the CO2 removing apparatus employing the system in which CO2 is absorbed with the CO2 absorbing liquid is used. Since such a CO2 absorbing liquid can absorb CO2 even at normal temperature, the above-mentioned problem that CO2 can not be eliminated until the catalyst activating temperature is reached can be solved. For example, as the CO2 absorption liquid, an ionic liquid, an aqueous alkali solution, water or the like can be used.

According to a third exemplary aspect of the present invention, the CO2 removing device has a circulation pump for circulating the CO2 absorption liquid through a circulation route, and an exhaust contact maker connected to the circulation route and provided on the exhaust pipe for absorbing the CO2 absorption liquid with the exhaust gas to bring into contact.

In the case of the engine mounted in the vehicle, the exhaust pipe is usually located under a vehicle floor. If it is attempted to install the entire CO2 removing device on such an exhaust pipe, the installation is difficult because the installation space is limited and a degree of freedom of a mounting layout under the vehicle floor is small.

In this regard, the CO2 removing apparatus according to the above-described aspect of the present invention is constructed so that the exhaust gas contact maker is connected to the circulation route through which the CO2 absorbing liquid is circulated by means of the circulation pump. Therefore, for example, by connecting a tank storing the CO2 absorption liquid to the circulation route, a body size of the exhaust gas contact maker provided on the exhaust pipe can be reduced. Therefore, the installation of the downsized exhaust gas contact maker as well as the connection of the exhaust gas contact maker to the exhaust pipe under the vehicle floor, where the installation space is limited, can be easily performed. The installation of the tank and the circulation pump is not limited to installation under the vehicle floor together with the exhaust contact manufacturer. The degree of freedom of the installation layout of the tank and the circulation pump can be improved.

According to a fourth exemplary aspect of the present invention, the CO2 removing device has a circulation control section for controlling a circulation state of the CO2 absorbing liquid. A range of an operating state of the internal combustion engine in which a NOx discharge amount in the exhaust gas is equal to or greater than a predetermined amount is defined as a high NOx operating range. A range of the operating state of the internal combustion engine in which the NOx discharge amount in the exhaust gas is smaller than the predetermined amount is defined as a low NOx operating range. When the operating state of the internal combustion engine is in the low NOx operating range, the circulation control section stops the circulation of the CO2 absorbing liquid to the exhaust gas contact manufacturer or decreases a circulation flow rate of the CO2 absorbing liquid to the exhaust gas contact manufacturer as compared with the case of the high NOx operating range.

An amount of NOx in the exhaust gas greatly changes as the operating state of the engine, such as an engine speed or an operating load, changes. It is important to absorb a sufficient amount of NOx with the NOx removing device during an operating state (high NOx operation) by discharging a large amount of NOx. For this purpose, it is desirable to increase CO2 removal capacity in the CO2 removal device during high NOx operation.

According to the above-described aspect of the present invention, considering this fact, the circulation of the CO2 absorbing liquid to the exhaust gas contact maker is stopped or the circulation flow rate is lowered during the low NOx operation. Therefore, the increase of a ratio of a CO 2 absorption amount (absorption ratio) with respect to an amount of CO 2 absorption liquid in the entire circulation route is prevented. That is, during the low NOx operation, the absorption ratio in the CO2 absorption liquid in the entire circulation route may be kept in the low state in preparation for the high NOx operation. Accordingly, the amount of absorption of CO2 during the high NOx operation can be increased and, moreover, a sufficient amount of NOx can be absorbed by the NOx removing device during the high NOx operation.

The above-mentioned circulation control section is, for example, a section for controlling an operation of an in 1 shown circulation pump 23 or a section to control operations of 1 shown valves 22c . 22d ,

According to a fifth exemplary aspect of the present invention, the CO2 removing device has an exhaust contact maker attached to the exhaust pipe to bring the CO2 absorbing liquid into contact with the exhaust gas, a bypass passage that branches off from the exhaust pipe so as to supply the exhaust gas cause the exhaust gas to bypass the exhaust contact manufacturer and a switching valve to switch exhaust flow to either the bypass passage or the exhaust contact manufacturer. A range of an operating state of the internal combustion engine in which a NOx discharge amount in the exhaust gas is equal to or greater than a predetermined amount is defined as a high NOx operating range. A range of the operating state of the internal combustion engine in which the NOx discharge amount in the exhaust gas is smaller than the predetermined amount is defined as a low NOx operating range. The CO2 removing device controls operation of the switching valve to guide the exhaust gas through the exhaust contact manufacturer when the operating state of the internal combustion engine is in the high NOx operating range. The CO2 removing device controls the operation of the switching valve to guide the exhaust gas through the bypass passage when the operating state of the internal combustion engine is in the low NOx operating range.

As mentioned above, during the high NOx operation, it is desirable to increase the CO2 removing capacity in the CO2 removing device so that a sufficient amount of NOx is absorbed by the NOx removing device. According to the above-described aspect of the present invention, taking into account this fact, the increase of the absorption ratio of the CO2 absorbing liquid in the entire circulation route is prevented by guiding the exhaust gas through the bypass passage during the low NOx operation. Thus, the absorption ratio in the entire circulation route can be maintained in the low state in preparation for the high NOx operation. Since the exhaust gas is passed through the exhaust contact manufacturer during the high NOx operation, the amount of CO2 absorption can be increased during the high NOx operation. Incidentally, a sufficient amount of NOx may be absorbed by the NOx removing device during the high NOx operation.

According to a sixth exemplary aspect of the present invention, the CO2 removing device has a tank for storing the CO2 absorbing liquid connected to the circulation route, and a circulation control section for controlling a circulation state of the CO2 absorbing liquid. The circulation control section discharges the CO2 absorbing liquid in the exhaust gas contact maker and replaces the CO2 absorbing liquid with the CO2 absorbing liquid in the tank when an absorption ratio of the CO2 absorbed in the CO2 absorbing liquid in the exhaust gas contact maker is equal to or higher than a predetermined value. The circulation control section holds the CO2 absorbing liquid in the exhaust gas contact maker without circulating the CO2 absorbing liquid in the exhaust gas contact maker to the circulation route when the absorption ratio is lower than the predetermined value.

In short, according to the above-described aspect of the present invention, the CO2 absorbing liquid is intermittently circulated. If the absorption ratio of the CO2 absorbing liquid in the exhaust gas contact maker becomes equal to or greater than the predetermined value, then the control for discharging the CO2 absorbing liquid in the exhaust gas contact maker and exchanging the CO2 absorbing liquid with the CO2 absorbing liquid in the tank is automatically performed. Therefore, the CO2 absorbing liquid in the exhaust gas contact maker can be automatically prevented from reaching an absorption saturation state in which the CO2 absorbing liquid can not absorb the CO2.

According to a seventh exemplary aspect of the present invention, the CO2 removing device has a circulation-speed control section for controlling a circulation rate of the CO2-absorbing liquid to the exhaust-gas contact manufacturer. The circulation speed control section continuously circulates the CO2 absorption liquid to the exhaust contact manufacturer. When an absorption ratio of the CO2 absorbed in the CO2 absorption liquid in the exhaust contact maker is equal to or greater than a predetermined value, the circulation-speed control section increases the circulation speed compared with the case where the absorption ratio is lower than the predetermined value.

In short, according to the above-described aspect of the present invention, the CO2 absorbing liquid is constantly circulated. When the absorption ratio of the CO2 absorption liquid in the exhaust gas contact manufacturer becomes equal to or greater than the predetermined value, then the control becomes Increasing the circulation speed automatically performed. Therefore, it can be automatically prevented that the CO2 absorption liquid in the exhaust gas contact manufacturer reaches the absorption saturation state in which the CO2 absorption liquid can not absorb CO2.

According to an eighth exemplary aspect of the present invention, the CO2 removing device has a circulation pump for circulating the CO2 absorption liquid through a circulation route, an exhaust contact manufacturer connected to the circulation route to bring the CO2 absorption liquid into contact with the exhaust gas, and one at the circulation route connected separating separator for separating the CO2, which has been absorbed in the CO2 absorption liquid, from the CO2 absorption liquid and for emitting CO2.

According to the above-described aspect of the present invention, the CO2 absorbed in the CO2 absorbing liquid can be separated and emitted from the CO2 absorbing liquid. Therefore, the absorption ratio of the CO2 absorption liquid in the entire circulation route can be reduced. Therefore, it can be avoided that the CO2 absorption liquid reaches the absorption saturation state in the entire circulation route. Accordingly, work for exchanging the CO2 absorbing liquid with a fresh CO2 absorbing liquid can be canceled and a replacement cycle can be prolonged.

According to a ninth exemplary aspect of the present invention, the CO2 removing device has a separation control section for controlling the separation speed of the separation performed by the separation separator. A range of an operating state of the internal combustion engine in which a NOx discharge amount in the exhaust gas is equal to or greater than a predetermined amount is defined as a high NOx operating range. A range of the operating state of the internal combustion engine in which the NOx discharge amount in the exhaust gas is smaller than the predetermined amount is defined as a low NOx operating range. When the operating state of the internal combustion engine is in the low NOx operating region as compared with the case of the high NOx operating region, the separation control section performs control for decreasing the separation speed or stopping the separation operation in the separation separator.

As mentioned above, it is desirable to increase the CO2 removing capacity in the CO2 removing device during the high NOx operation so that a sufficient amount of NOx can be absorbed by the NOx removing device during the high NOx operation. According to the above-described aspect of the present invention, in consideration of this fact, the separation speed in the separation separator is reduced or the separation operation is stopped during the low NOx operation. Thus, the increase of the absorption ratio of the CO2 absorption liquid in the entire circulation route can be prevented. That is, during the low NOx operation, the absorption ratio of the CO2 absorption liquid in the entire circulation route can be maintained in preparation for the high NOx operation at the low state. Therefore, the amount of CO2 absorption can be increased during the high NOx operation. Finally, a sufficient amount of NOx can be absorbed during the high NOx operation in the NOx removal device.

According to a tenth exemplary aspect of the present invention, the CO2 removing device has a separation control section for controlling the separation speed of the separation performed by the separation separator. If an absorption ratio of the CO2 absorbed in the CO2 absorption liquid is equal to or greater than a predetermined value, then the separation control section performs a control for increasing the separation speed as compared with the case where the absorption ratio is smaller than the predetermined value.

According to the above-described aspect of the present invention, if the absorption ratio of the CO2 absorbing liquid becomes equal to or higher than the predetermined value, the separation speed is increased. Therefore, the CO2 absorbing liquid can be automatically prevented from reaching the absorption saturation state in which the CO2 absorbing liquid can not absorb the CO2. The separation speed is reduced when the absorption ratio is smaller than the predetermined value. Therefore, an electric drive power consumed in the separator can be reduced. Therefore, in the case that the separation separator is driven by electric power generated by a driving force of the internal combustion engine, a power generation load on the internal combustion engine can be reduced. Further, in the case where CO2 is separated from the CO2 absorbing liquid by heating the CO2 absorbing liquid, the above-described aspect of the present invention is also effective in the following problem.

That is, depending on the type of CO2 absorption fluid, the absorbable decreases Amount of CO2 decreases with increasing temperature. If the temperature becomes too high, there is a problem that the CO2 absorbing liquid evaporates and becomes unable to fully utilize the CO2 absorbing capacity. Therefore, in the case where CO2 is separated by heating the CO2 absorbing liquid, the temperature of the CO2 absorbing liquid due to the heating for separating becomes high temperature, whereby the above-mentioned problem may occur.

Regarding this problem, according to the above-described aspect of the present invention, the separation speed is increased when the absorption ratio is equal to or higher than the predetermined value. The separation speed is reduced when the absorption ratio is smaller than the predetermined value. Therefore, the temperature increase of the CO2 absorption liquid can be prevented when the absorption ratio is low and the necessity for separation is low. Therefore, the above-mentioned problem caused by the temperature of the CO2 absorbing liquid becoming the high temperature can be prevented.

According to an eleventh exemplary aspect of the present invention, the separation separator separates CO2 from the CO2 absorption liquid by heating the CO2 absorption liquid. When a temperature of the CO2 absorption liquid in the separation separator is higher than the upper limit temperature, the separation separator reduces a heating degree of heating performed by the separation separator as compared with the case where the temperature is lower than the upper limit temperature.

Accordingly, the temperature can be prevented from rising to an extent that the CO2 absorption liquid evaporates. In addition, a significant lowering of the CO2 absorption capacity due to evaporation can be avoided.

According to a twelfth exemplary aspect of the present invention, the NOx removal system further has a heat recovery device attached to the exhaust pipe for recovering heat of the exhaust gas. The separator heats the CO2 absorption liquid using the heat recovered by the heat recovery device.

Thus, the CO2 absorption liquid is heated using the heat of the exhaust gas. Therefore, the electric power consumed by the NOx removing system can be reduced as compared with the case where a heat source such as an electric heater for performing the warm-up operation is provided.

According to a thirteenth exemplary aspect of the present invention, the internal combustion engine has a filter (DPF device) for collecting particulate matter (PM) in the exhaust gas, and a regeneration operation control section for performing a regeneration operation for increasing the exhaust gas temperature for removing the collected particulate matter from the filter. The NOx removal system is configured to control an operation of the circulation pump to flow the CO2 absorption liquid into the separation separator at a time when the regeneration processing is performed.

At the time when the regeneration processing is performed, the amount of heat that can be recovered by the heat recovery device is large, and the separability of the separation separator is high. Therefore, according to the above-described aspect of the present invention, which allows the CO2 absorption liquid to flow into the separation separator at this time, the heat of the exhaust gas can be effectively utilized, and CO2 can be separated from the CO2 absorption liquid sent into the separation separator and within a short time Period of time to be emitted.

According to a fourteenth exemplary aspect of the present invention, the NOx removal system further has an oxidation section for oxidizing NO in the exhaust gas in NO 2. The oxidation section is provided on the exhaust pipe upstream of the NOx removing device and downstream of the CO2 removing device.

A rate of the NOx absorption amount in the NOx absorption liquid with respect to an amount of NOx in the exhaust gas that is not absorbed but slips through the NOx removal device may be defined as an absorption rate. In this case, the absorption rate of NO 2 may be higher than the absorption rate of NO depending on the type of the NO x absorption liquid. Therefore, according to the above-described aspect of the present invention, according to which the oxidation section is located upstream of the NOx removing device, the absorption rate of NOx by the NOx removing device can be improved.

However, if NO is oxidized in NO2 upstream of the NO2 removal device, there is concern that an amount of CO2 released by the CO2 Absorption fluid absorbed NO2 may increase depending on the type of CO2 absorption fluid. According to the above-described aspect of the present invention, considering this fact, the oxidizing section is located upstream of the NOx removing device and downstream of the CO2 removing device. Therefore, the above concerns can be eliminated.

For example, an oxidation catalyst, an ozone generator or the like may be used as the oxidation section. According to the above-described aspect of the present invention, the oxidizing portion is disposed at a location remote from a combustion chamber in the exhaust pipe. Therefore, in the case where the oxidation catalyst is used, there is a concern that the oxidation catalyst can not be sufficiently heated when the oxidation catalyst is activated by heating the oxidation catalyst with the exhaust gas. In this case, it is desirable to provide a heating section such as a burner or an electric heater to the oxidation catalyst.

According to a fifteenth exemplary aspect of the present invention, the CO2 removing device has a cooling device for cooling the CO2 absorbing liquid.

With this construction, a problem can be solved according to which the CO2 absorption capacity is lowered or the CO2 absorption liquid evaporates, which may occur when the temperature of the CO2 absorption liquid becomes the high temperature. In particular, when the separation separator is provided which separates the CO2 from the CO2 absorption liquid by heating the CO2 absorption liquid, the above-described aspect of the present invention is effective, according to which the CO2 absorption liquid is cooled by the cooling means.

According to a sixteenth exemplary aspect of the present invention, the CO2 absorption liquid is a solution obtained by dissolving a solute which absorbs CO2 in contact with the solute in a solvent. The CO2 removing device has a concentration control section for controlling a concentration of the dissolved CO2 of the absorbing liquid.

There is a case where the solute concentration of the CO2 absorbing liquid increases because of evaporation of a solvent (for example, water). There is also a case where a water component in the exhaust gas mixes with the CO2 absorption liquid, so that the solute concentration decreases. Regarding these cases, according to the above-described aspect of the present invention, the control for matching the solute concentration with the optimum concentration can be automatically performed. Therefore, the lowering of the absorption capacity of the CO2 absorption liquid due to the concentration change can be prevented.

Features and advantages of embodiments as well as operating methods and functions of the related parts will become apparent from a study of the following detailed description, the appended claims and the drawings, all of which form a part of this application.

In the drawings:

1 Fig. 12 is a diagram showing a NOx removing system according to a first embodiment of the present invention;

2 a graph illustrating a CO2 absorption capacity of a CO2 absorption liquid according to the first embodiment;

3 FIG. 10 is a flowchart showing a flow of control for intermittently circulating the CO2 absorption liquid according to the first embodiment; FIG.

4 FIG. 12 is a diagram showing a NOx removing system for an internal combustion engine according to a second embodiment of the present invention; FIG.

5 a diagram showing a liquid recovery apparatus according to the second embodiment;

6 a diagram showing a liquid recovery device according to a modification of the second embodiment;

7 FIG. 10 is a flowchart showing a procedure for controlling a concentration of an absorbing liquid according to the second embodiment; FIG.

8th FIG. 10 is a flowchart showing a procedure for controlling the intermittent circulation of a CO 2 absorption liquid according to the second embodiment; FIG.

9 FIG. 10 is a flowchart showing a NOx removing system according to a third embodiment of the present invention; FIG.

10 FIG. 12 is a graph showing a relation between an operating state of an internal combustion engine, a NOx discharge amount, and a CO2 discharge amount; FIG.

11 FIG. 10 is a flowchart showing a procedure for controlling operations of a by-pass valve and the like according to the third embodiment; FIG.

12 FIG. 10 is a flowchart showing a NOx removing system according to a fourth embodiment of the present invention; FIG. and

13 FIG. 10 is a flowchart showing a procedure for controlling the constant circulation of a CO2 absorption liquid according to a fifth embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description of the respective embodiments, the same reference numerals are used in the drawings for identical or equivalent parts. An internal combustion engine to which the exhaust gas purification device according to each embodiment is applied is mounted in a vehicle and functions as a driving source for driving. As the internal combustion engine, a compression-ignition diesel engine is assumed.

(First embodiment)

1 is a diagram showing a NOX removal system and an internal combustion engine 10 according to a first embodiment of the present invention. From a combustion chamber 10a the internal combustion engine 10 discharged exhaust gas is discharged from a predetermined part of a rear portion of a vehicle through an exhaust pipe located below a vehicle floor 11 emitted. An oxidation catalyst 12 (DOC) for oxidizing NOx contained in the exhaust gas is at the exhaust pipe 11 appropriate. NO in the exhaust gas is through the DOC 12 oxidized in NO2.

A filter 13 (DPF) for collecting particulate matter (PM) in the exhaust gas is downstream of the DOC 12 on the exhaust pipe 11 appropriate. To those through the DPF 13 To burn collected particulate matter is a control of the injection quantity and the injection timing of an injector 14 for increasing the exhaust gas temperature, ie, a regeneration processing control periodically performed. A control unit (ECU 15 ), which is the operation of the injector 14 for performing the regeneration processing control corresponds to a regeneration processing control section. A CO2 removal device 20 for removing CO2 in the exhaust gas is downstream of the DPF 13 on the exhaust pipe 11 intended. A NOx removal device 30 for removing NOx in the exhaust gas is at the exhaust pipe 11 downstream of the CO2 removal device 20 intended. Any disposal device 20 . 30 corresponds to the exhaust gas purification device for the internal combustion engine. Next, the constructions of the devices 20 . 30 described in detail.

(CO2-removal device 20 )

The CO2 removal device 20 consists mainly of a tank 21 , an exhaust contact manufacturer 22 , a circulation pump 23 and a separation separator 24 passing each other through a circulation pipe 25 are connected. In the tank 21 is stored a CO2 absorption liquid (described in detail later). When the circulation pump 23 works, then the CO2 absorption liquid circulates through one through the circulation pipe 25 defined circulation passage. The exhaust contact manufacturer 22 is on the exhaust pipe 11 and works by bringing the circulating CO2 absorption liquid into contact with the exhaust gas.

The CO2 absorption liquid is a liquid that absorbs CO2 through contact with the CO2 in the exhaust gas. For example, as the CO2 absorption liquid, an in JP-A-2008-296211 and other references, ionic liquid, an alkali solution, water (e.g., engine coolant), or the like. It is preferable to use a liquid which hardly absorbs NOx but selectively absorbs CO2 in the exhaust gas (for example, NaOH, KOH, Na ₂ CO ₃ , K ₂ CO ₃ , Ca (OH) ₂ , ethanolamine or the like) CO2 absorption amount can be increased. A substance that absorbs CO2 by a chemical change, that is, a substance that causes chemical adsorption, can be used as the CO2 absorbing liquid. Alternatively, a substance that absorbs CO2 without chemical change, that is, a substance that causes physical adsorption, may be used. A gel substance or a slurry substance may be used as the CO2 absorption liquid.

2 shows a test result showing an effect of CO2 removal in the case where the aqueous NaOH solution is used as the CO2 absorption liquid. The exhaust gas, whose CO2 concentration is approx. 6%, becomes the exhaust gas contact manufacturer 22 guided. In this case it is confirmed that the CO2 concentration of the exhaust contact manufacturer 22 outgoing exhaust gas was reduced to about 1%, as in 2 is shown.

The exhaust contact manufacturer 22 consists mainly of a holder 22a which holds the CO2 absorbing liquid in itself by infiltrating the CO2 absorbing liquid and out of a casing 22b which the holder 22a in its interior. The housing 22b is on the exhaust pipe 11 connected and the exhaust gas flows through an interior of the housing 22b , The housing 22b is also on the circulation pipe 25 connected. The CO2 absorption liquid coming from an inflow hole of the housing 22b over the circulation pipe 25 in the case 22b is flowing in the container 22a held. The container 22a is arranged so that it passes through the interior of the housing 22b is exposed to flowing exhaust gas. This is what comes in the holder device 22a held CO2 absorption liquid with the exhaust gas in contact.

At the inflow hole and at the outflow hole of the housing 22b are each an inflow valve 22c or a discharge valve 22d intended. The valves 22c . 22d are electromagnetic drive valves. An ECU 15 controls the opening / closing operations of the valves 22c . 22d , If the ECU 15 the discharge valve 22d can perform the opening operation, therefore, the CO2 absorption liquid in the housing 22b be delivered. If the ECU 15 the inlet valve 22c can perform the opening operation, the CO2 absorption liquid in the housing 22b be flown.

The inflow hole is in an upper part of the housing 22b formed and the outflow hole is in a lower part of the housing 22b educated. Therefore, the system is constructed so that the CO2 absorption liquid can be discharged by its weight, if the opening operation of the discharge valve 22d is performed even if the circulation pump 23 not working. The system is designed so that the CO2 absorption liquid due to its weight in the housing 22b can flow when the opening operation of the inflow valve 22c is performed in a state in which the CO2 absorption liquid in the housing 22b was discharged, even if the circulation pump 23 not working.

The separation separator 24 consists mainly of a tank 24a that of the exhaust contact manufacturer 22 discharged CO2 absorption liquid, and from a heater 24b (Heating section), which is in the tank 24a is provided. If the CO2 absorption liquid supplied by the exhaust contact manufacturer 22 was discharged and in the tank 24a has flowed through the heater 24b is heated, CO2 absorbed in the CO2 absorption liquid is separated from the CO2 absorption liquid.

The ECU 15 controls an operation of the heater 24b , Therefore, the separation of CO2 is promoted when the ECU 15 the controller for operating the heater 24b performs. The separation rate of CO2 decreases when the ECU 15 a controller for stopping the operation of the heater 24b performs. That is, the ECU 15 functions as a separation control section for controlling the separation speed by controlling the operation of the heater 24b ie by controlling a heating degree.

There is a limit to the CO2 absorbable by a unit amount of the CO2 absorption liquid. Subsequently, a state of the CO2 absorption liquid in which the limit amount of CO2 has been absorbed is referred to as an absorption saturation state. A ratio of the CO2 absorption amount to a CO2 amount (maximum absorption amount) that can be absorbed by the CO2 absorption liquid in a state where the CO2 absorption amount is zero will be referred to as an absorption ratio hereinafter. The absorption ratio in the absorption saturation state is 100%. If the separator 24 the CO2 separates from the CO2 absorption liquid, the absorption ratio decreases, so that an absorption capacity of the CO2 absorption liquid increases and is restored. The separated CO2 is from a separator hole 24c emitted to the outside air. The CO2 absorption liquid from which the CO2 was separated and through the separation separator 24 was eliminated, circulated through the tank 21 , the CO2 removal device 20 and the separation separator 24 in this order.

The ECU 15 controls an operation of the circulation pump 23 , In the present embodiment, the circulation pump 23 not operated continuously but it is operated intermittently. That is, the CO2 absorption liquid is not constantly circulated but it is intermittently circulated. The control contents of the circulation pump 23 , the heater 24b and the like will be described later in detail.

(NOx removing device 30 )

Next, a construction of the NOx removing device will be described 30 explained. The NOx removal device 30 consists mainly of a tank 31 , an exhaust contact manufacturer 32 and a circulation pump 33 passing through a circulation pipe 35 connected to each other.

An inside of the tank 31 is in a feed tank area 31a and a recovery tank area 31b divided. The feed tank area 31a stores a NOx absorption liquid (which will be described in detail later) that is not yet used and that the exhaust contact manufacturer 32 is supplied. The recovery tank area 31b stores the used and recovered NOx absorption liquid. Thus, mixing of the used NOx absorbing liquid into the fresh NOx absorbing liquid is prevented. The NOx absorption liquid in the feed tank area 31a becomes the exhaust contact manufacturer 32 fed. The in the exhaust contact manufacturer 32 Used NOx absorption liquid is by operating the circulation pump 33 in the recovery tank area 31b recovered.

The exhaust contact manufacturer 32 is on the exhaust pipe 11 downstream of the exhaust contact manufacturer 22 the CO2 removal device 20 appropriate. The exhaust contact manufacturer 32 serves to bring the NOx absorption liquid into contact with the exhaust gas.

The NOx absorption liquid is a liquid that absorbs NOx by contact with the NOx in the exhaust gas. For example, as the NOx absorption liquid, the in JP-A-2008-296211 and other references, ionic liquid, the alkali solution, the water (for example, engine coolant), or the like. It is preferable to use the liquid (eg FeSO ₄ , Ca (OH) ₂ , H ₂ SO ₄ , K ₂ Cr ₂ O ₇ or the like) which hardly absorbs CO2 but selectively absorbs NOx in the exhaust gas since the NOx Absorption amount can be increased. A substance that absorbs NOx with a chemical change, that is, a substance that causes a chemical adsorption, may be used as the NOx absorbing liquid. Alternatively, a substance that adsorbs NOx without the chemical change, that is, a substance that causes the physical adsorption, may be used. A gel substance or a slurry substance may be used as the NOx absorption liquid.

The exhaust contact manufacturer 32 consists mainly of a holding device 32a holding the NOx absorbing liquid, and a housing 32b holding the holding device 32a inside absorbs. The housing 32b is to the exhaust pipe 11 connected and the exhaust gas flows through an interior of the housing 32b , The housing 32b is also to the circulation pipe 35 connected. The NOx absorption liquid coming from an inflow hole of the housing 32b over the circulation pipe 35 in the case 32b flows, is in the holding device 32a held. The holding device 32a is arranged so that it passes through the interior of the housing 32b is exposed to flowing exhaust gas. Therefore, the comes in the holding device 32a held NOx absorption liquid in contact with the exhaust gas.

An inlet valve 32c and a discharge valve 32d are respectively at the inflow hole and a discharge hole of the housing 32b intended. The valves 32c and 32d are electromagnetic drive valves. The ECU 15 controls opening / closing operations of the valves 32c . 32d , If the ECU 15 the discharge valve 32d can perform the opening operation, therefore, the NOx absorption liquid in the housing 32b be delivered. If the ECU 15 the inlet valve 32c can perform the opening operation, the NOx absorption liquid in the housing 32b be flown.

The inflow hole is in an upper part of the housing 32b formed and the outflow hole is in a lower part of the housing 32b educated. Therefore, the system is constructed so that the NOx absorption liquid can be discharged by its weight when the opening operation of the Ausströmventils 32d is performed even if the circulation pump 33 not driven. The system is designed so that the NOx absorption liquid due to their weight in the housing 32b can flow, if the opening operation of the inflow valve 32c is performed in the state where the NOx absorption liquid in the housing 32b was discharged, even if the circulation pump 33 not working.

There is a limit to the amount of NOx absorbable by a unit amount of the NOx absorption liquid. Hereafter, a state of the NOx absorption liquid that has absorbed the limit amount of NOx is referred to as an absorption saturation state. A ratio of the NOx absorption amount to a NOx amount (maximum absorption amount) that can be absorbed by the NOx absorption liquid in a state where the NOx absorption amount is zero is referred to as an absorption ratio. The absorption ratio in the absorption saturation state is 100%. The absorption ratio of in the feed tank area 31a stored, unused NOx absorption liquid is 0%.

The absorption ratio of the NOx absorption liquid in the feed tank section 31a is zero and the NOx absorption liquid becomes the exhaust gas contact maker 32 fed. The NOx absorption liquid, its absorption ratio in the exhaust gas contact manufacturer 32 has risen to a predetermined value or above, by the circulation pump 33 to the recovery tank section 31b recovered. The spent and in the recovery tank section 31b recovered NOx absorption liquid is removed from the tank 31 extracted. The dirty liquid treatment of the extracted NOx absorption liquid is carried out in a treatment plant outside the vehicle. Refilling fresh NOx absorption liquid to the feed tank section 31a is performed by a vehicle user or a service person, if necessary.

The ECU 15 controls the operation of the circulation pump 33 , In the present embodiment, the circulation pump is not operated constantly but intermittently. That is, the NOx absorption liquid is not constantly circulated but is intermittently circulated.

The NOx removal device 30 has a sensor for detecting a physical quantity that correlates with the absorption ratio of the NOx absorbing liquid. In the present embodiment, a pH sensor 32e used as the above-mentioned sensor. The pH sensor 32e is at the exhaust contact manufacturer 32 appropriate. If that by the pH sensor 32e If the detected pH value is equal to or less than a predetermined value (ie, if an acidity level is high), the ECU determines 15 in that the absorption ratio of the NOx absorption liquid in the exhaust contact manufacturer 32 has become equal to or higher than a predetermined value and performs the replacement control described below.

In the replacement control, first, the valve opening operation of the discharge valve 32d performed to the NOx absorption liquid in the exhaust contact manufacturer 32 leave. At this time, the discharged NOx absorption liquid becomes in the recovery tank section 31b recovered by the circulation pump 33 is operated. If the valve opening operation of the discharge valve 32d is performed for a predetermined period of time, it is determined that the discharge of the NOx absorption liquid is completed. Then, the valve closing operation of the Ausströmventils 32d performed and the valve opening operation of the inflow valve 32c is carried out. Thus, the NOx absorption liquid flows in the feed tank portion 31a into the exhaust contact manufacturer 32 , If the valve opening operation of the inflow valve 32c is performed for a predetermined period of time, it is determined that the supply and replacement of the NOx absorption liquid is completed. Then, the valve closing operation in the inflow valve 32c carried out.

(Circulation control of the CO2 absorption liquid)

Next, an operation of the separation-speed control in the separation separator will be described 24 described. The separation speed controller includes a circulation control of the CO2 absorption liquid by controlling the operation of the circulation pump 23 and controlling the operation of the heater 24b ,

3 Fig. 10 is a flowchart showing the procedure of the above-described control. A microcomputer of the ECU 15 executes the control 3 repeatedly in predetermined cycles (for example, in calculation cycles of the microcomputer or every predetermined crank angle).

First, in step S10 (S means "step") of 3 determines whether the absorption ratio of the CO2 absorption liquid in the exhaust contact manufacturer 22 is equal to or greater than a predetermined value. The CO2 removal device 20 has a sensor for detecting a physical quantity correlated with the absorption ratio of the CO2 absorption liquid. In the present embodiment, a pH sensor 22e used as the above-mentioned sensor. The pH sensor 22e is at the exhaust contact manufacturer 22 appropriate. If it is determined in step S10 that by the pH sensor 22e When the detected pH value is equal to or greater than a predetermined value α (ie, if the acidity is high), it is concluded that the absorption ratio of the CO2 absorption liquid in the exhaust gas contact manufacturer 22 is equal to or higher than the predetermined value. Then, the flow advances to the following step S11.

In step S11 (circulation control section), the operation of the circulation pump 23 started. At this time, the valve opening operations of both the inflow valve 22c as well as the discharge valve 22d be performed. Alternatively, only the valve opening operation of the Ausströmventils 22d be performed. Alternatively, a construction can be used that is not one of the valves 22c . 22d Has. Thus, the discharge of the CO2 absorption liquid from the exhaust contact manufacturer becomes 22 started. In the following step S12 (separation control section), the energization of the heater 24b started. Thus, the separation of CO2 by the separation separator 24 started.

In the following step S13, it is determined whether after the start of the operation of the circulation pump 23 in step S11 a predetermined period of time has elapsed. If it is determined in step S13, That the predetermined operation time has elapsed (S13: YES), it is assumed that an amount of the CO2 absorption liquid discharged by the exhaust contact manufacturer has been discharged 22 can be held. Then, in the following step S14 (circulation control section), the operation of the circulation pump 23 stopped. If both valves 22c . 22d since a start time of the operation of the circulation pump 23 are opened, the valve closing operations of both valves 22c . 22d at a stop time of the operation of the circulation pump 23 carried out.

If the valve opening operation only the discharge valve 22d at the start time of the operation of the circulation pump 23 is performed, the valve closing operation of the Ausströmventils 22d performed and the valve opening operation of the inflow valve 22c becomes the stop time of the operation of the circulation pump 23 carried out. Thus, mixing the used CO2 absorbing liquid whose absorption ratio has already increased to a predetermined value or more can be avoided with the unconsumed CO2 absorbing liquid discharged from the tank 21 is supplied.

In the following step S15, it is determined whether CO2 has been sufficiently separated and emitted to an extent that the absorption ratio of the CO2 absorption liquid in the separation separator 24 decreases to a value lower than the predetermined value. More specifically, an elapsed time of operation of the heater 24b at the predetermined temperature or above becomes equal to or longer than a predetermined time (S15: YES), it can be concluded that CO2 has been sufficiently separated and emitted. Then, in the following step S16 (separation control section), the operation of the heater 24b stopped.

• (1) Der Abgaskontakthersteller 22 der CO2-Beseitigungsvorrichtung 20 ist stromaufwärts des Abgaskontaktherstellers 32 der NOx-Beseitigungsvorrichtung 30 an dem Abgasrohr 11 vorgesehen. Daher kann das Abgas, dessen CO2-Konzentration durch die CO2-Beseitigungsvorrichtung 20 gesenkt wurde, zu der NOx-Beseitigungsvorrichtung 30 geschickt werden. Dementsprechend kann die Menge des durch die NOx-Absorptionsflüssigkeit absorbierten CO2 reduziert werden. Im Übrigen kann eine ausreichende Menge von NOx in die NOx-Absorptionsflüssigkeit absorbiert werden.
• (2) Das NOx-Beseitigungssystem gemäß dem vorliegenden Ausführungsbeispiel absorbiert NOx und CO2, indem die NOx-Absorptionsflüssigkeit und die CO2-Absorptionsflüssigkeit jeweils mit dem Abgas in Kontakt gebracht werden. Daher können die Beseitigungsfunktionen der CO2-Beseitigungsvorrichtung 20 und der NOx-Beseitigungsvorrichtung 30 sogar bei der normalen Temperatur ausgeübt werden. Daher kann das NOx in dem Abgas selbst beim Kaltstart der Brennkraftmaschine 10 unmittelbar nach dem Start der Brennkraftmaschine 10 beseitigt werden.
• (3) In der CO2-Beseitigungsvorrichtung 20 gemäß dem vorliegenden Ausführungsbeispiel sind der an dem Abgasrohr 11 angebrachte Abgaskontakthersteller 22 und der Tank 21 als getrennte Körper konstruiert und zwischen ihnen wird die Zirkulation durchgeführt. Falls das Volumen des Abgaskontaktherstellers 22 mit dem Tank 21 abgeglichen wird und die Heizeinrichtung 24b an dem Abgaskontakthersteller 22 vorgesehen ist, können der Trennabscheider 24 und der Tank 21 in den Abgaskontakthersteller 22 integriert werden und die Zirkulation kann hinfällig gemacht werden. Falls jedoch die Integration auf diese Weise durchgeführt wird, nimmt eine Körperabmessung des Abgaskontaktherstellers 22 zu und es wird ziemlich schwierig, den Abgaskontakthersteller 22 unter dem Fahrzeugboden zu installieren.

The present embodiment described above brings forth the following effects.

• (1) The exhaust contact manufacturer 22 the CO2 removal device 20 is upstream of the exhaust contact manufacturer 32 the NOx removal device 30 on the exhaust pipe 11 intended. Therefore, the exhaust gas, its CO2 concentration through the CO2 removal device 20 was lowered to the NOx removal device 30 sent. Accordingly, the amount of CO2 absorbed by the NOx absorbing liquid can be reduced. Incidentally, a sufficient amount of NOx can be absorbed into the NOx absorbing liquid.
• (2) The NOx removing system according to the present embodiment absorbs NOx and CO2 by contacting the NOx absorbing liquid and the CO2 absorbing liquid, respectively, with the exhaust gas. Therefore, the removal functions of the CO2 removal device 20 and the NOx removing device 30 even at the normal temperature. Therefore, the NOx in the exhaust gas even at the cold start of the internal combustion engine 10 immediately after the start of the internal combustion engine 10 be eliminated.
• (3) In the CO2 removal device 20 according to the present embodiment, the at the exhaust pipe 11 attached exhaust gas contact manufacturers 22 and the tank 21 constructed as separate bodies and between them the circulation is carried out. If the volume of the exhaust contact manufacturer 22 with the tank 21 is adjusted and the heater 24b at the exhaust contact manufacturer 22 is provided, the separating separator 24 and the tank 21 into the exhaust contact manufacturer 22 be integrated and the circulation can be made obsolete. However, if the integration is performed in this way, a body dimension of the exhaust contact manufacturer increases 22 too and it becomes quite difficult, the exhaust contact manufacturer 22 to install under the vehicle floor.

In contrast, according to the present embodiment, the exhaust contact manufacturer 22 , The Tank 21 and the separation separator 24 As the separate body is formed and the circulation is carried out. Therefore, the body dimension of the exhaust contact manufacturer 22 be reduced, which under the ground on the exhaust pipe 11 is to be connected. Therefore, according to the present embodiment, the installation of the exhaust contact manufacturer 22 simplified under the ground. In addition, one degree of freedom of a mounting layout may be involved in mounting the CO2 removing device 20 be improved on the vehicle.

• (4) Falls das Absorptionsverhältnis der CO2-Absortionsflüssigkeit in dem Abgaskontakthersteller 22 gleich oder größer als der vorbestimmte Wert wird, dann wird die Steuerung zum Abgeben der CO2-Absorptionsflüssigkeit in dem Abgaskontakthersteller 22 und zum Austauschen der CO2-Absorptionsflüssigkeit mit der CO2-Absorptionsflüssigkeit in dem Tank 21 automatisch durchgeführt. Daher kann automatisch verhindert werden, dass die CO2-Absorptionsflüssigkeit in dem Abgaskontakthersteller 22 den Absorptionssättigungszustand erreicht, in welchem die CO2-Absorptionsflüssigkeit das CO2 nicht absorbieren kann.

As mentioned above, according to the present embodiment, the exhaust contact manufacturer 22 , The Tank 21 and the separation separator 24 provided as the separate body and the circulation is carried out. When the internal combustion engine 10 has a large engine displacement, therefore, the present invention can be applied to such an engine 10 be applied by the volume of the tank 21 is increased and by the frequency of supplying the CO2 absorption liquid to the exhaust contact manufacturer 22 is increased. The same exhaust contact manufacturer 22 can work together for internal combustion engines 10 be used with different engine room.

• (4) If the absorption ratio of the CO2 absorption liquid in the exhaust contact manufacturer 22 becomes equal to or greater than the predetermined value, then the control for discharging the CO2 absorption liquid in the Exhaust Us Manufacturers 22 and for exchanging the CO2 absorption liquid with the CO2 absorption liquid in the tank 21 automatically performed. Therefore, it can be automatically prevented that the CO2 absorption liquid in the exhaust contact manufacturer 22 reached the absorption saturation state, in which the CO2 absorption liquid can not absorb the CO2.

• (5) Wenn NOx in dem Abgas durch den Abgaskontakthersteller 32 absorbiert wird, dann wird die Absorptionsrate von NO2 verglichen mit NO erhöht werden. Daher ist in dem vorliegenden Ausführungsbeispiel der DO12, der NO in NO2 oxidiert, stromaufwärts des Abgaskontaktherstellers 32 angeordnet, so dass die Absorptionsrate des NOx in dem Abgaskontakthersteller 32 verbessert werden kann. Der Dieselpartikelfilter 13 ist stromaufwärts des Abgaskontaktherstellers 22, 32 angeordnet. Daher kann verhindert werden, dass die Partikelstoffe in dem Abgas an den Innenseiten der Abgaskontakthersteller 22, 32 anhaften und ein Verstopfen hervorrufen.

When it is determined whether the control (exchange control) for replacing the CO2 absorption liquid in the exhaust contact manufacturer 22 is to be performed, the determination based on an operating time of the internal combustion engine 10 or a route of the vehicle. In this case, the pH sensor can 22e be omitted and the costs can be reduced. However, according to the present embodiment described above, the execution timing of the replacement control can be determined by detecting the pH of the CO2 absorption liquid using the pH sensor 22e determines an accurate management be performed so that the absorption ratio does not become equal to or higher than the predetermined value. In addition, a problem can be prevented, according to which the replacement is carried out early, although the absorption ratio is smaller than the predetermined value.

• (5) When NOx in the exhaust gas by the exhaust contact manufacturer 32 is absorbed, then the absorption rate of NO2 will be increased compared to NO. Therefore, in the present embodiment, the DO 12 that oxidizes NO into NO 2 is upstream of the exhaust port manufacturer 32 arranged so that the absorption rate of NOx in the exhaust contact manufacturer 32 can be improved. The diesel particulate filter 13 is upstream of the exhaust contact manufacturer 22 . 32 arranged. Therefore, it can be prevented that the particulate matter in the exhaust gas on the inner sides of the exhaust contact manufacturer 22 . 32 attach and cause clogging.

Second Embodiment

Next, a second embodiment of the present invention will be explained. In the in 4 The present embodiment shown are the functions of a heat recovery device 24d , a cooling device 26 a liquid recovery device 27 , a solution tank 28 to the CO2 removal device 20 of the first embodiment added. Further, functions of a liquid recovery device 37 and a solution tank to the NOx removing device 30 of the first embodiment added. Subsequently, a system configuration of 4 described, with the focus on the differences too 1 lies. The description of the first embodiment is herein with respect to the components in FIG 4 incorporated with the same reference numerals as those in 1 are shown components.

The heat recovery device 24d is on the exhaust pipe 11 attached to recover the heat of the exhaust gas. The heat recovery device 24d For example, it uses the engine coolant as the heat medium. The engine coolant is through a pipe 24e with the tank 24a of the separating separator 24 connected. The engine coolant carries heat exchange with the CO2 absorption liquid in the tank 24a through and warms up the CO2 absorption liquid. In short, the in 1 shown heater 24b eliminated. The CO2 absorption liquid is passed through the heat recovery device 24d warmed up, which separates CO2.

One by the ECU 15 controlled pump 24f is at the coolant circulating tube 24e appropriate. A heating degree (ie, a separation speed) is controlled by controlling an operation of the pump 24f controlled. For example, on the tank 24a of the separating separator 24 a temperature sensor 24g attached to the temperature of the CO2 absorption liquid in the tank 24a capture. The degree of heating is controlled by an on and off control of the pump 24f is performed according to the detected temperature.

The cooling device 26 is on the separator 24 and the tank 21 in the circulation pipe 25 provided and cools the CO2 absorption liquid immediately after the CO2 absorption liquid in the separator 24 was heated and separated. The cooling device 26 may be a cooling device of the air cooling type, which performs a heat exchange with an ambient air. Alternatively, the cooling device 26 be configured to receive a refrigerant or the like which circulates an evaporator of a vehicle chamber air conditioner, and to perform a heat exchange between the refrigerant and the CO2 absorption liquid.

The amount of CO2 absorbable by the CO2 absorption liquid decreases with increasing temperature. Specifically, as the temperature rises above a predetermined temperature, the absorbable amount of CO2 decreases rapidly. Therefore, the through the separator 24 heated CO2 absorption liquid in the present embodiment by the cooling device 26 cooled.

The liquid recovery device 27 is in the exhaust pipe 11 downstream of the exhaust contact manufacturer 22 and upstream of the NOx removing device 30 arranged. There are concerns that part of the exhaust gas in the exhaust contact manufacturer 22 in contact with the exhaust gas CO2 in the exhaust pipe together with the exhaust gas 11 is removed. The liquid recovery device 27 recovers the CO2 absorption liquid that has been removed in this way and to an outside of the housing 22b has flowed. In addition, the liquid recovery device works 27 such that it reduces the absorption ratio by removing CO2 from the recovered CO2 absorption liquid. Furthermore, the liquid recovery apparatus works 27 by passing the thus treated CO2 absorption liquid through a tube 27a to the circulation pipe 25 returns.

5 Fig. 12 is a diagram showing a structure of the liquid recovery apparatus 27 according to the present embodiment shows. The liquid recovery device 27 has one in the exhaust pipe 11 arranged electrode 27b and one on the inner wall surface of the exhaust pipe 11 attached electric cell 27c , If at the electrode 27b Applying a DC voltage with high voltage, then adhere to the electrons flowing out of the exhaust CO2 absorption liquid and ionize the CO2 absorption liquid. When the ionized CO2 absorption liquid on the electric cell 27c adheres, only absorbed in the CO2 absorption liquid CO2 ions pass the electric cell 27c which makes it a memory section 27d move and deposit there. Since the memory section 27d is electrically grounded, the electrons of the CO2 ions flow to the storage section 27d have moved into grounding. In other words, there is the CO2 absorption liquid, which is the electric cell 27c can not happen and remains in a state where CO2 has been removed and the absorption ratio has been lowered.

In short, the CO2 absorbing liquid in the exhaust gas becomes by charging the high-tension CO2 absorbing liquid and depositing the CO2 absorbing liquid on the electric cell 27c recovered. Then, CO2 is recovered from the recovered CO2 absorption liquid using the electric cell 27c eliminated. The CO2 absorptive liquid, which has the reduced absorption ratio, passes through the tube 27a to the circulation pipe 25 recycled. In the memory section 27d accumulated CO2 can be emitted to the ambient air.

6 is a diagram showing a modification of the in 5 shows the liquid recovery device shown. In the in 6 The device shown is the electric cell 27c omitted. The CO2 absorption liquid in the exhaust gas passing through the electrode 27b charged with high voltage is stored in a storage tank 27e recovered. In the storage tank 27e The CO2 absorption liquid, which has absorbed a large amount of CO2 and has the high absorption ratio, is deposited on a lower part of the storage tank 27e from. Therefore, be in the storage tank 27e the low absorption ratio CO2 liquid (thin CO2 liquid) and the high absorption ratio CO2 liquid (concentrated CO2 liquid) are separated from each other. The thin CO2 liquid in the upper layer of the in the storage tank 27e stored CO2 absorption liquid is through the pipe 27a to the circulation pipe 25 recycled. The in the lower layer of the storage tank 27e accumulated concentrated CO2 absorption liquid can be collected and disposed of, for example, in a vehicle workshop or the like.

The solution, such as the ionic solution or the alkali solution, which is prepared by dissolving a solute (for example, ion or alkali) in a solvent (for example, water) is used as the CO2 absorption liquid in the present embodiment. In this case, maintaining the solution concentration at a predetermined concentration is important to exercise a predetermined CO2 absorption function. However, if the solvent evaporates, the concentration increases or the concentration decreases if the water component in the exhaust gas becomes the CO2 absorption liquid in the exhaust contact manufacturer 22 mixed.

Therefore, in the present embodiment, the solute, such as the ion or the alkali, and the solvent, such as the water, in the solution tank 28 saved. The solute and the solvent are analyzed according to a concentration sensor 28a recorded concentration to the tank 21 fed. The concentration sensor 28a is on the circulation pipe 25 near and downstream of the tank 21 appropriate. For example, as the concentration sensor 28a uses a sensor that detects the viscosity, which strongly correlates with the concentration of the liquid.

In a connection between the solution tank 28 and the tank 21 is one through the ecu 15 controlled electromagnetic valve 28b intended. The ECU 15 performs the opening and closing control of the valve 28b according to a detection value of the concentration sensor 28a by. Thus, the ECU controls 15 the feed rates of Solvent and the solvent such that the concentration of CO2 absorption liquid in the tank 21 is in the optimum concentration range.

The NOx removal device 30 has the liquid recovery device 37 with the same structure as that of the liquid recovery device 27 the CO2 removal device 20 , The liquid recovery device 37 is on the exhaust pipe 11 downstream of the exhaust contact manufacturer 32 intended. There is concern that some of the NOx absorption liquid associated with the exhaust gas in the exhaust contact manufacturer 32 comes into contact, together with the exhaust gas in the exhaust pipe 11 escapes. The liquid recovery device 37 recovers the NOx absorption liquid that has escaped in this way and to an outside of the housing 32b has flowed. In addition, the liquid recovery device serves 37 decreasing the absorption ratio by removing NOx from the recovered NOx absorption liquid. Further, the liquid recovery device serves 37 returning the NOx absorption liquid thus treated through a pipe 37a to the circulation pipe 35 ,

The NOx removal device 30 has the solution tank 38 , a concentration sensor 38a and an electromagnetic valve 38b with the same structure as the solution tank 28 , the concentration sensor 28a and the electromagnetic valve 28b the CO2 removal device 20 , The ECU 15 performs the opening and closing control of the valve 38b according to a detection value of the concentration sensor 38a by. Thus, the ECU controls 15 the supply amounts of a solute and a solvent of the NOx absorption liquid such that the concentration of the NOx absorption liquid in the tank 31 is in the optimum concentration range.

A degree of reduction in concentration due to mixing of the water component in the exhaust gas is lower than a degree of increase in concentration due to evaporation of the solvent. Therefore, you can save and refill the solution using the solution tanks 28 . 38 be waived. 7 Fig. 10 is a flowchart showing a procedure for controlling the concentrations of the CO2 absorbing liquid and the NOx absorbing liquid for controlling the supply amounts of the solvent to prevent the increase of the concentration due to the evaporation of the solvent. The microcomputer of the ECU 15 leads the expiration of 7 in a predetermined cycle repeatedly (for example, in calculation cycles of the microcomputer or every predetermined crank angle).

First, in step S20 (concentration control section) of FIG 7 determines if the through the concentration sensor 28a (or 38a ) is equal to or greater than a predetermined value. If the liquid concentration is equal to or greater than the predetermined value, then in the following step S21 (concentration control portion), the valve opening operation of the electromagnetic valve becomes 28b (or 38b ) to transfer the solvent (eg water) to the tank 21 (or 31 ). If the detected viscosity (or concentration) is smaller than the predetermined value, then the valve closing operation of the electromagnetic valve becomes 28b (or 38b ) to stop the feed.

8th FIG. 11 is a flowchart illustrating a procedure for controlling the operations of the pump. FIG 24f the heat recovery device 24d and the circulation pump 23 of the circulation pipe 25 shows. The microcomputer of the ECU 15 Repeats the process of 8th in a predetermined cycle (for example, in a calculation cycle of the microcomputer or every predetermined crank angle).

First, in step S30 of FIG 8th determines if the regeneration processing of the DPF 13 is carried out. The regeneration processing serves to temporarily increase the exhaust gas temperature by retarding the injection timing to which the fuel from the injector 14 is injected or by increasing the fuel injection amount. Thus, those by the DPF 13 collected particulate matter burned and eliminated, causing the DPF 13 is regenerated.

If it is determined that the regeneration processing of the DPF 13 is performed, in the following step S31, the pump 24f the heat recovery device 24d driven. Thus, the heat medium of the heat recovery device becomes 24d to the separation separator 24 circulated. Accordingly, the CO2 absorption liquid becomes in the separation separator 24 heated by the heat of the exhaust gas whose temperature has increased with the exercise of the regeneration processing. Thus, the separation of CO2 is promoted. In the following step S32, the trap hole becomes 24c opened to CO2 from the separator 24 to emit.

In the following step S33, it is determined whether the separated CO2 has been completely emitted. More specifically, it is determined that the emission is completed when after opening the trap hole 24c a predetermined period of time has elapsed. Alternatively, it may be determined that the emission is completed when a predetermined Time lapse has elapsed after the temperature of the CO2 absorption liquid in the separator 24 has risen to the predetermined temperature. If it has been determined that the emission is completed, the operation of the pump becomes 24f stopped to stop the removal of CO2 caused by the heating. When the temperature of the CO2 absorption liquid in the separator 24 rises to the upper limit temperature, then the operation of the pump 24f stopped even if the CO2 emission is not completed. Thus, a lowering of the absorption capacity due to an excessive increase in the temperature of the exhaust contact to the manufacturer 22 Prevented supplied CO2 absorption liquid.

If it is determined that the emission is completed, the flow advances to the following step S34. In step S34, the operation of the circulation pump 23 of the circulation pipe to the CO2 absorption liquid in the tank 21 to the exhaust contact manufacturer 22 supply. In this case, the above-mentioned exchange control can be performed (control for discharging liquid from the exhaust gas contact manufacturer 22 by the valve opening operation of the discharge valve 22d is performed and then the liquid is supplied by after the completion of the liquid discharge, the valve opening operation of the inflow valve 22c is carried out). Alternatively, the operation of the circulation pump 23 be started while the opening operations of both valves 22c . 22d be performed.

In the following step S35, it is determined whether an amount of the liquid from the tank 21 to the holder 22a which is equal to a capacity in the holder 22a can be held. In addition, it is determined that the amount of liquid equal to the capacity has been supplied and the replacement is completed when the driving operation of the circulation pump 23 for a predetermined period of time (S35: YES). Then, in the following step S36, the operation of the circulation pump 23 stopped to stop the circulation of the liquid.

• (5) Die Wärmerückgewinnungsvorrichtung 24d ist vorgesehen, um die Wärme des Abgases zurückzugewinnen und die Flüssigkeit in dem Trennabscheider 24 zu erwärmen. Daher kann die in 1 gezeigte Heizeinrichtung 24b ausgelassen werden und der Energieverbrauch kann gesenkt werden.
• (6) Die Pumpe 24f wird angetrieben, um die Wärmerückgewinnung zu dem Zeitpunkt durchzuführen, zu dem die Regenerationsverarbeitung des Dieselpartikelfilters 13 durchgeführt wird. Daher kann eine ausreichende Wärmemenge zum Erwärmen und Trennen der Flüssigkeit sichergestellt werden.
• (7) Die Kühleinrichtung 26 ist vorgesehen, um die Flüssigkeit zu kühlen, deren Temperatur mit dem Erwärmen und dem Trennen zugenommen hat. Daher kann die CO2-Absorptionskapazität der CO2-Absorptionsflüssigkeit, deren CO2-Absorptionskapazität mit dem Ansteigen der Temperatur abgenommen hat, wiederhergestellt werden.
• (8) Da die Flüssigkeitsrückgewinnungsvorrichtungen 27, 37 vorgesehen sind, kann eine Emission eines Teils der Absorptionsflüssigkeiten, die aus den Abgaskontaktherstellern 22, 32 zum Inneren des Abgasrohrs 11 ausgeströmt sind, zusammen mit dem Abgas verhindert werden. Außerdem werden die Absorptionsflüssigkeiten zu den Zirkulationsrohren 25, 35 zurückgeführt, nachdem CO2 und NOx von den zurückgewonnenen Absorptionsflüssigkeiten abgetrennt wurden und die Absorptionsverhältnisse verringert wurden. Daher kann die Erhöhung der Absorptionsverhältnisse der Absorptionsflüssigkeiten in den Zirkulationsrohren 25, 35 verhindert werden.
• (9) Die Lösungstanks 28, 38 und die Konzentrationssensoren 28a, 38a sind vorgesehen, um die Konzentrationen der Absorptionsflüssigkeiten bei den vorbestimmten Konzentrationen beizubehalten. Daher kann ein Absenken der Absorptionskapazität infolge der Konzentrationsänderung vermieden werden.

The present embodiment explained above involves the following effects (5) to (9) in addition to the above-mentioned effects (1) to (4).

• (5) The heat recovery device 24d is provided to recover the heat of the exhaust gas and the liquid in the separator 24 to warm up. Therefore, the in 1 shown heater 24b be omitted and the energy consumption can be lowered.
• (6) The pump 24f is driven to perform the heat recovery at the time when the regeneration processing of the diesel particulate filter 13 is carried out. Therefore, a sufficient amount of heat for heating and separating the liquid can be ensured.
• (7) The cooling device 26 is intended to cool the liquid whose temperature has increased with heating and separating. Therefore, the CO2 absorption capacity of the CO2 absorption liquid whose CO2 absorption capacity has decreased with the increase of the temperature can be restored.
• (8) Since the liquid recovery devices 27 . 37 may be provided, an emission of a portion of the absorption liquids from the exhaust contact manufacturers 22 . 32 to the interior of the exhaust pipe 11 have flowed out, be prevented together with the exhaust. In addition, the absorption liquids become the circulation pipes 25 . 35 recycled after CO2 and NOx were separated from the recovered absorption liquids and the absorption ratios were reduced. Therefore, the increase of the absorption ratios of the absorbing liquids in the circulation pipes can be increased 25 . 35 be prevented.
• (9) The solution tanks 28 . 38 and the concentration sensors 28a . 38a are intended to maintain the concentrations of the absorption liquids at the predetermined concentrations. Therefore, a lowering of the absorption capacity due to the concentration change can be avoided.

(Third Embodiment)

Next, a third embodiment of the present invention will be described. In the in 9 shown third embodiment are a Beipassrohr 40 and a bypass valve 41 (Changeover valve) provided on the NOx removal system of the aforementioned first embodiment. Subsequently, a system configuration of 9 explains, focusing on the differences too 1 lies. The description of the first embodiment is herein with respect to the components in FIG 9 incorporated with the same reference numerals as those in 1 are shown components.

The bypass pipe 40 defines a bypass passage 40a that allows the exhaust gas to pass through so that the exhaust gas is the exhaust contact manufacturer 22 . 32 bypasses. The exhaust pipe 40 is upstream of the exhaust contact manufacturer 22 or downstream of the exhaust contact manufacturer 32 connected. The bypass valve 41 opens and closes an inlet of the bypass passage 40a , An electric motor drives the bypass valve 41 and the ECU 15 controls an operation of the engine.

If the bypass pipe 40 is applied to the system that the in 4 shown heat recovery device 24d it is desirable to have the inlet of the bypass tube 40 at a point downstream of the heat recovery device 24d and upstream of the exhaust contact manufacturer 22 to join. Thus, the waste heat may be used to heat the liquid in the separator 24 regardless of the operating state of the bypass valve 41 be restored. If the bypass pipe 40 is applied to the system containing the liquid recovery device 37 has, like this in 4 is shown, it is desirable to have an outlet of the bypass tube 40 at a point downstream of the exhaust contact manufacturer 32 and upstream of the liquid recovery device 37 to join. Thus, leaked NOx absorption liquid can be used regardless of the operating state of the bypass valve 41 be recovered.

As described in sections (a) and (b) of 10 11, the NOx discharge amount and the CO2 discharge amount in the exhaust gas largely change according to the operating state of the internal combustion engine 10 (about the engine output shaft speed NE and the engine load NE). For example, shows 10 in that the NOx release amount and the CO2 release amount increase with increasing engine load. 10 (a) also shows that the NOx discharge amount decreases when the engine speed NE is close to 2000 rpm, even if the engine load is a medium load.

The ECU 15 performs the valve opening operation of the bypass valve 41 when the engine operating condition is a condition in which the NOx discharge amount is smaller than a predetermined threshold value TH. The ECU 15 performs the valve closing operation of the by-pass valve 41 when the NOx discharge amount is equal to or greater than the threshold value TH. The ECU 15 the control leads to stopping the operations of the circulation pumps 23 . 33 through when the bypass valve 41 is open. The ECU 15 the controller carries out the operations of circulating pumps 23 . 33 through when the bypass valve 41 closed is.

11 FIG. 12 is a flowchart showing a procedure for controlling the operation of the by-pass valve. FIG 41 shows. The microcomputer of the ECU 15 leads the in 11 shown in a predetermined cycle repeatedly (for example, in a calculation cycle of the microcomputer or at each predetermined crank angle).

First, in step S40 of FIG 11 determines whether the engine load and the rotational speed NE are in a predetermined range (low NOx operating range) in a previously prepared map. The map is prepared in advance by examining a relationship between the engine load, the rotational speed NE, and the NOx discharge amount. The range defined by the engine load and the rotational speed NE and in which the NOx discharge amount is smaller than the threshold value TH is defined as the low NOx operating range.

When it is determined that the engine operating state is in the low NOx operating region (S40: YES), then the valve opening operation of the bypass valve becomes 41 in the following step S41. Thus, the exhaust gas flows through the bypass passage 40a and bypasses the exhaust contact manufacturers 22 . 32 , In the following step S42 (circulation control section), the circulation of the fluids of the circulation pipes becomes 25 . 35 stopped by the operations of the circulation pumps 23 . 33 turned off. In the following step S43 (separation control section), the operation of the heater becomes 24b stopped to stop the separation of CO2.

If it is determined that the engine load and the rotational speed NE are in a high NOx operating range that is different from the low NOx operating range in the map (S40: NO), the operation of the heater becomes 24b is turned on to start the separation of CO2 in the following step S44 (separation control section). In the following step S45 (circulation control section), the circulation of the liquids in the circulation pipes becomes 25 . 35 caused by the operations of the circulation pumps 23 . 33 be turned on. In the following step S46, a valve closing operation of the bypass valve 41 carried out. Thus, exhaust gas flows through the exhaust contact manufacturers 22 . 32 ,

• (10) Um eine ausreichende Menge von NOx mit der NOx-Beseitigungsvorrichtung 30 während des hohen NOx-Betriebs zu absorbieren, ist es wünschenswert, die CO2-Beseitigungskapazität in der CO2-Beseitigungsvorrichtung 20 im Vorfeld zu erhöhen. Daher wird in dem vorliegenden Ausführungsbeispiel das Abgas während des niedrigen NOx-Betriebs durch den Beipassdurchlass 40a geführt, um die Erhöhung des Absorptionsverhältnisses der gesamten CO2-Absorptionsflüssigkeit zu verhindern, welche durch das Zirkulationsrohr 25 zirkuliert wird. Somit kann das Absorptionsverhältnis in Vorbereitung des hohen NOx-Betriebs bei dem niedrigen Zustand beibehalten werden. Das Abgas wird während des hohen NOx-Betriebs durch die Abgaskontakthersteller 22, 32 geführt. Daher kann die CO2-Absorptionsmenge während des hohen NOx-Betriebs erhöht werden. Schließlich kann in der NOx-Beseitigungsvorrichtung 30 während des hohen NOx-Betriebs eine ausreichende Menge von NOx absorbiert werden.

The present embodiment explained above involves the following effects (10) and (11) in addition to the aforementioned effects (1) to (4).

• (10) To supply a sufficient amount of NOx with the NOx removing device 30 During high NOx operation, it is desirable to have the CO2 removal capacity in the CO2 removal device 20 to raise in advance. Therefore, in the present embodiment, the exhaust gas becomes through the bypass passage during the low NOx operation 40a to prevent the increase of the absorption ratio of the total CO2 absorption liquid passing through the circulation tube 25 is circulated. Thus, the absorption ratio can be maintained in preparation for the high NOx operation at the low state. The exhaust gas is produced by the exhaust contact manufacturers during the high NOx operation 22 . 32 guided. Therefore, the amount of CO2 absorption can be increased during the high NOx operation. Finally, in the NOx removal device 30 a sufficient amount of NOx is absorbed during high NOx operation.

Similarly, increasing the absorption ratio of the total NOx absorption liquid passing through the circulation tube 35 circulated during low NOx operation.

Thus, the absorption ratio can be maintained at a low state in preparation for the high NOx operation.

• (11) Der Betrieb der Heizeinrichtung 24b wird während des niedrigen NOx-Betriebs gestoppt, so dass der Energieverbrauch in der Heizeinrichtung 24b verhindert werden kann. Daher kann der Verbrauch der Batterie verhindert werden. Im Übrigen kann der Kraftstoffverbrauch verbessert werden, indem eine Stromerzeugung durch die Brennkraftmaschine 10 verringert wird.

The engine load and the rotational speed NE of the internal combustion engine 10 of the vehicle change rapidly within a short period of time. In this regard, according to the present embodiment, the absorption ratios of the CO2 absorbing liquid and the NOx absorbing liquid are maintained during the low NOx operation at low conditions. Therefore, even if a large amount of NOx is discharged within the short period of time, the NOx can be satisfactorily absorbed.

• (11) The operation of the heater 24b is stopped during the low NOx operation, so that the energy consumption in the heater 24b can be prevented. Therefore, the consumption of the battery can be prevented. Incidentally, the fuel consumption can be improved by generating power by the internal combustion engine 10 is reduced.

(Fourth Embodiment)

Next, a fourth embodiment of the present invention will be described. In the first embodiment described above, the DOC is 12 (Oxidation section) for oxidizing NO in the exhaust gas in NO2 upstream of the exhaust contact maker 22 arranged like this in 1 is shown. Thus, the DOC 12 at a point as close as possible to an exhaust port of the internal combustion engine 10 arranged to activate the oxidation catalyst. Such a construction is advantageous because the temperature increase of the DOC 12 can be realized in a short period of time by using the high-temperature exhaust gas. However, when NO in NO 2 is oxidized, while the NO x absorption rate in the exhaust contact manufacturer 32 can be improved, NOx by the CO2 absorption liquid in the exhaust contact manufacturer 22 Easier to absorb.

In this regard, according to the present embodiment, an oxidation section 12a in the exhaust pipe 11 downstream of the exhaust contact manufacturer 22 the CO2 removal device 20 and upstream of the exhaust contact manufacturer 32 the NOx removal device 30 arranged like this in 12 is shown. With such a construction, the absorption of NOx by the CO2 absorbing liquid can be prevented, and the absorption of NOx by the NOx absorbing liquid can be improved.

However, if the oxidation section 12a is arranged at such a location, is the oxidation section 12a far away from the exhaust port. As a result, it becomes difficult to activate the oxidation catalyst by the high-temperature exhaust gas within a short period of time. Therefore, if the oxidation section 12a is placed at this point, instead of the oxidation catalyst using the DOC preferably an ozone generator or a radical generator can be used. Alternatively, if the oxidation catalyst (DOC) is used, it is desirable to add an electric heater or burner to heat the DOC.

(Fifth Embodiment)

Next, a fifth embodiment of the present invention will be described. In the first embodiment described above, the circulation pump becomes 23 the CO2 removal device 20 operated intermittently to the CO2 absorption liquid in the circulation pipe 25 to circulate intermittently. In contrast, according to the present embodiment, the circulation pump 23 the CO2 removal device 20 Constantly operated to remove the CO2 absorption liquid in the circulation pipe 25 to circulate constantly. If the ECU 15 the operation of the circulation pump 23 controls, then controls the ECU 15 the circulation rate of the CO2 absorption liquid variable according to the absorption ratio of the CO2 absorption liquid. In the present embodiment, the inflow valve 22c and the discharge valve 22d , in the 1 shown are not used.

13 Fig. 10 is a flowchart showing a flow of the above-described control. The microcomputer of the ECU 15 executes the process 13 repeatedly in a predetermined cycle (for example, in a calculation cycle of the microcomputer or every predetermined crank angle).

First, in step S50 of FIG 13 determines whether the absorption ratio of the CO2 absorption liquid in the exhaust contact manufacturer 22 lies in a predetermined range. If it is determined that the absorption ratio is in the predetermined range (S50: YES), a Delivery of the heater 24b of the separating separator 24 and a discharge of the circulation pump 23 maintained at the current levies. Thus, the separation speed in the separation separator 24 and maintain the circulation rate of the CO2 absorption liquid. The absorption ratio may be the same as in the first embodiment using the pH sensor 22e be recorded.

If determined by the pH sensor 22e If the detected pH value is smaller than a predetermined range (S50: SMALLER), it is considered that the absorption ratio of the CO2 absorption liquid is larger than the predetermined range. Then the expenses of the heater 24b and the circulation pump 23 in the following step, S51 (circulation speed control section) and S52 (separation control section) are increased. Thus, the separation speed in the separation separator 24 and increases the circulation rate of the CO2 absorption liquid. Therefore, the amount of the exhaust contact manufacturer 22 per unit of time absorbable CO2 increased.

If determined by the pH sensor 22e If the detected pH value is higher than the predetermined range (S50: HIGHER), it is considered that the absorption ratio of the CO2 absorption liquid is smaller than the predetermined range. Then the expenses of the heater 24b and the circulation pump 23 in the following step, S53 (circulation speed control section) and S54 (disconnection control section) are reduced. Thus, the separation speed in the separation separator 24 and reduces the circulation rate of the CO2 absorption liquid. Therefore, the amount of consumed by the exhaust contact manufacturer is decreasing 22 absorbable CO2 per unit time.

In the following step S55, it is determined whether the temperature of the CO2 absorption liquid in the separation separator 24 is equal to or greater than a predetermined upper limit temperature. If it is determined that the temperature is equal to or higher than the upper limit temperature (S55: YES), the operation of the heater becomes 24b of the separating separator 24 regardless of the determination result of S50.

Thus, according to the present embodiment, by processing steps S50 to S54, the amount of NOx that is not absorbed but slips through the NOx removing device can be kept constant in the exhaust gas. In addition, by the processing of steps S55 and S56, the situation where the temperature of the CO2 absorbing liquid exceeds the upper limit temperature and the CO2 absorbing capacity decreases considerably can be avoided.

(Modifications)

The present invention is not limited to the above-described embodiments but may be modified and implemented as follows, for example. Furthermore, characteristic constructions of the respective embodiments can be arbitrarily combined.

The CO2 absorption liquid (or NOx absorption liquid) may be a liquid that absorbs CO2 (or NOx) without causing a change in a molecular structure, i. h., a liquid that absorbs CO2 (or NOx) through physical absorption. Alternatively, the CO2 absorption liquid (or the NOx absorption liquid) may be a liquid that absorbs CO2 (or NOx) by causing the change in molecular structure, i. h., a liquid that absorbs CO2 (or NOx) through chemical absorption.

In the above embodiments, the tank 21 (or 31 ) and the exhaust contact manufacturer 22 (or 32 ) are provided separately from each other and the absorption liquid is passed through the circulation pump 23 (or 33 ) circulates. Thus, the body size of the exhaust contact maker becomes 22 (or 32 ) decreased. Alternatively, the body dimension of the exhaust contact manufacturer 22 (or 32 ) and the tank 21 (or 31 ) can be omitted. In this case, the circulation pump 23 (or 33 ) are omitted to eliminate the circulation. Alternatively, the absorption liquid may be pumped inside the exhaust contact manufacturer using a pump 22 (or 32 ) are circulated.

In the embodiments described above, the exhaust gas and the absorbing liquid are brought into contact with each other by the holder 22a (or 32a ) is exposed to the exhaust gas, which keeps the absorption liquid in itself by infiltration of the absorption liquid. Alternatively, for example, the absorbing liquid may be brought into contact with the exhaust gas by injecting the absorbing liquid in the form of a spray into the exhaust gas. Alternatively, the absorbing liquid and the exhaust gas may be brought into contact with each other by blowing the exhaust gas into a tank storing the absorbing liquid.

The separation separator 24 According to the above-mentioned first embodiment, CO2 separates using the heater 24b (Heating section), which warms up the CO2 absorption liquid. Alternatively, instead of the heater 24b a negative pressure section may be provided to apply a negative pressure to the CO2 absorbing liquid, and CO2 may be separated by applying a negative pressure to the CO2 absorbing liquid.

In the first embodiment described above, the absorption ratios of the absorbing liquids are determined by using the pH sensors 22e . 32e detected. The absorption ratio is also highly correlated with the viscosity, transmittance, electrical conductivity and specific gravity of the liquid. Therefore, instead of any pH sensor 22e . 32e a sensor can be used to detect one of these physical quantities. In addition, when the absorbing liquid is the ionic liquid, the absorption ratio can be detected by using a sensor that detects a relationship between cations (positive ions) and anions (negative ions) in the absorbing liquid. In the first embodiment described above, the circulation pump becomes 33 the NOx removal device 30 operated intermittently to the NOx absorption liquid in the circulation pipe 35 to circulate intermittently. Alternatively, the circulation pump 33 the NOx removal device 30 be operated constantly to the NOx absorption liquid through the circulation pipe 35 to circulate constantly. If the ECU 15 the operation of the circulation pump 33 controls, the ECU can 15 the circulation rate of the NOx absorption liquid as in steps S50, S51 and S53 of FIG 13 variably according to the absorption ratio of the NOx absorption liquid. In this case it is desirable to use the inlet valve 32c and the discharge valve 32d , in the 1 are shown to eliminate. Moreover, in this case, it is necessary to eliminate a partition wall, which is the interior of the tank 31 in the feed tank section 31a and the recovery tank section 31b separates.

The present invention should not be limited to the disclosed embodiments, but may be implemented in many other ways without departing from the scope of the invention as defined in the appended claims.

An NOx removal system for an internal combustion engine ( 10 ) has a NOx removal device ( 30 ) which holds a NOx absorbing liquid for absorbing NOx in contact with the NOx absorbing liquid. The NOx removal device ( 30 ) absorbs and eliminates NOx in the exhaust gas of the internal combustion engine ( 10 ) by bringing the exhaust gas and the NO x absorption liquid into contact with each other. The NOx removal system has a CO2 removal device ( 20 ) located upstream of the NOx removal device ( 30 ) on the exhaust pipe ( 11 ) is provided to eliminate CO2 in the exhaust gas. Thus, there is provided the NOx removing system using the system which eliminates and absorbs NOx in the exhaust gas by using the NOx absorbing liquid and can sufficiently absorb NOx.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• JP 2008-82315 A [0002]
• JP 2009-281294 A [0002]
• JP 2008-296211A [0065, 0077]

Claims (16)

NOx removal system for an internal combustion engine ( 10 characterized by: a NOx removal device ( 30 ) which holds a NOx absorption liquid for absorbing NOx in contact with the NOx absorption liquid and the NOx in the exhaust gas of the internal combustion engine ( 10 ) is absorbed and removed by bringing the exhaust gas and the NO x absorption liquid into contact with each other; and a CO2 removal device ( 20 ) attached to an exhaust pipe ( 11 ) of the internal combustion engine ( 10 ) upstream of the NOx removal device ( 30 ) is provided for removing CO2 in the exhaust gas. The NOx removal system according to claim 1, wherein the CO2 removal device ( 20 ) holds a CO2 absorption liquid for absorbing CO2 in contact with the CO2 absorption liquid, and the CO2 removal device ( 20 ) Absorbs and eliminates CO2 in the exhaust gas of the internal combustion engine by bringing the exhaust gas and the CO2 absorption liquid into contact with each other. NOx removal system according to claim 2, wherein the CO2 removal device ( 20 ) comprises: a circulation pump ( 23 ) for circulating the CO2 absorption liquid through a circulation route ( 25 ); and an exhaust contact manufacturer ( 22 ) at the circulation route ( 25 ) is connected and at the exhaust pipe ( 11 ) is provided to bring the CO2 absorption liquid into contact with the exhaust gas. The NOx removal system according to claim 3, wherein the CO2 removal device ( 20 ) Circulation control means (S11, S14, S42, S45) for controlling a circulation state of the CO2 absorption liquid has a range of an operating state of the internal combustion engine (S11, S14, S42, S45) 10 ) in which a NOx discharge amount in the exhaust gas is equal to or larger than a predetermined amount is defined as a high NOx operating range, a range of the operating state of the internal combustion engine (FIG. 10 ), in which the NOx discharge amount in the exhaust gas is smaller than the predetermined amount, is defined as a low NOx operating range, and when the operating state of the internal combustion engine ( 10 ) is in the low NOx operating range, the circulation control means (S11, S14, S42, S45) controls the circulation of the CO2 absorption liquid to the exhaust gas contact manufacturer ( 22 ) or a circulation flow rate of the CO2 absorption liquid to the exhaust gas contact manufacturer ( 22 ) is reduced compared to a case of the high NOx operating range. NOx removal system according to claim 2 or 3, wherein the CO2 removal device ( 20 ) one on the exhaust pipe ( 11 ) installed exhaust contact manufacturers ( 22 ) has, to bring the CO2 absorption liquid into contact with the exhaust gas, a bypass passage ( 40a ), of the exhaust pipe ( 11 ) branches off to guide the exhaust gas so that the exhaust gas the exhaust contact manufacturer ( 22 ), and a switching valve ( 41 ) to supply a flow of exhaust gas either to the bypass passage (FIG. 40a ) or the exhaust contact manufacturer ( 22 ), a range of an operating state of the internal combustion engine ( 10 ) in which a NOx discharge amount in the exhaust gas is equal to or larger than a predetermined amount is defined as a high NOx operating range, a range of the operating state of the internal combustion engine (FIG. 10 ) in which the NOx discharge amount in the exhaust gas is smaller than the predetermined amount is defined as a low NOx operating range, the CO2 removing device (FIG. 20 ) an operation of the switching valve ( 41 ) to control the exhaust gas by the exhaust contact manufacturer ( 22 ), when the operating state of the internal combustion engine ( 10 ) is located in the high NOx operating range and the CO2 removal device ( 20 ) the operation of the switching valve ( 41 ) to the exhaust gas through the bypass passage ( 40a ), when the operating state of the internal combustion engine ( 10 ) is in the low NOx operating range. NOx removal system according to claim 3 or 4, wherein the CO2 removal device ( 20 ) one at the circulation route ( 25 ) connected tank ( 21 has for storing the CO2 absorption liquid, and the circulation control means (S11, S14, S42, S45) for controlling a circulation state of the CO2 absorption liquid, the circulation control means (S11, S14, S42, S45) the CO2 absorption liquid in the exhaust gas contact manufacturer (S11, S14, S42, S45) 22 ) and the CO2 absorption liquid with the CO2 absorption liquid in the tank ( 21 ) when an absorption ratio of in the CO2 absorption liquid in the exhaust gas contact manufacturer ( 22 ) absorbed CO2 is equal to or greater than a predetermined value, and the circulation control means (S11, S14, S42, S44) the CO2 absorption liquid in the exhaust gas contact manufacturer ( 22 ), without the CO2 absorption liquid in the exhaust gas contact 22 ) to the circulation route ( 25 ) when the absorption ratio is lower than the predetermined value. NOx removal system according to claim 3 or 4, wherein the CO2 removal device ( 20 ) a circulation-speed control means (S51, S53) for controlling the circulation rate of the CO2 absorption liquid to the exhaust-gas contact manufacturer (S51, S53) 22 ), the circulation-speed control means (S51, S53) has the CO2 absorption liquid constant to the exhaust-gas contact manufacturer (S51, S53) 22 ), and the circulation-speed control means (S51, S53) increases the circulation speed when an absorption ratio of the CO2 absorption liquid in the exhaust-gas contact maker ( 22 ) absorbed CO2 is equal to or higher than a predetermined value compared to the case where the absorption ratio is lower than the predetermined value. NOx removal system according to one of claims 2 to 7, wherein the CO2 removal device ( 20 ) comprises: a circulation pump ( 23 ) for circulating the CO2 absorption liquid through a circulation route ( 25 ); an exhaust contact manufacturer ( 22 ) at the circulation route ( 25 ) is connected to bring the CO2 absorption liquid into contact with the exhaust gas; and a separation separator ( 24 ) at the circulation route ( 25 ) to separate CO2 absorbed in the CO2 absorption liquid from the CO2 absorption liquid and to emit CO2. The NOx removal system according to claim 8, wherein the CO2 removal device ( 20 ) a separation control means (S12, S16, S43, S44, S52, S54) for controlling the separation velocity of the separation by the separator ( 24 ) carried out separation, a range of an operating condition of the internal combustion engine ( 10 ) in which a NOx discharge amount in the exhaust gas is equal to or greater than a predetermined value is defined as a high NOx operating range, a range of the operating state of the internal combustion engine ( 10 ) in which the NOx discharge amount in the exhaust gas is smaller than the predetermined value is defined as a low NOx operation range, and the separation control means (S12, S16, S43, S44, S52, S54) has a control for decreasing the separation speed or Stopping the separation operation in the separation separator ( 24 ) is performed when the operating condition of the internal combustion engine ( 10 ) is in the low NOx operating range as compared to the case of the high NOx operating range. The NOx removal system according to claim 8 or 9, wherein the CO2 removal device ( 20 ) a separation control means (S12, S16, S43, S44, S52, S54) for controlling the separation velocity of the separation by the separator ( 24 ), and the separation control means (S12, S16, S43, S44, S52, S54) performs control for increasing the separation speed when an absorption ratio of CO2 absorbed in the CO2 absorption liquid is equal to or greater than a predetermined value with the case where the absorption ratio is smaller than the predetermined value. NOx removal system according to one of claims 8 to 10, wherein the separation separator ( 24 ) Separates CO2 from the CO2 absorption liquid by heating the CO2 absorption liquid, and the separation separator ( 24 ) a degree of heating by the separation separator ( 24 ) is reduced when the temperature of the CO2 absorption liquid in the separation separator ( 24 ) is higher than an upper limit temperature as compared with the case where the temperature is lower than the upper limit temperature. The NOx removal system of claim 11, further comprising: a heat recovery device (10); 24d ) for recovering heat of the exhaust gas at the exhaust pipe ( 11 ), the separation separator ( 24 ) the CO2 absorption liquid using the heat recovery device ( 24d ) heat recovered. NOx removal system according to claim 12, wherein the internal combustion engine ( 10 ) a filter ( 13 ) for collecting particulate matters in the exhaust gas, and a regeneration processing control means ( 15 ) for performing a regeneration processing for increasing the exhaust gas temperature for removing the collected particulate matters from the filter ( 13 ), and the NOx removal system is configured to allow operation of the circulation pump ( 23 ) to transfer the CO2 absorption liquid into the separation separator at a time ( 24 ) at which the regeneration processing is performed. The NOx removal system of any one of claims 2 to 13, further comprising: an oxidizing agent ( 12a ) for oxidizing NO in the exhaust gas in NO 2, wherein the oxidizing agent ( 12a ) upstream of the NOx removal device ( 30 ) and downstream of the CO2 Disposal device ( 20 ) on the exhaust pipe ( 11 ) is provided. NOx removal system according to one of claims 2 to 14, wherein the CO2 removal device ( 20 ) a cooling device ( 26 ) for cooling the CO2 absorption liquid. The NOx removing system according to any one of claims 2 to 15, wherein the CO2 absorbing liquid is a solution prepared by dissolving a solute which absorbs CO2 in contact with the solute in a solvent, and the CO2 removing device ( 20 ) has a concentration control means (S20, S21) for controlling a solution concentration of the CO2 absorption liquid.

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