JP6161969B2 - Exhaust purification system - Google Patents

Description

The techniques of the present disclosure relates to exhaust gas purification system that purifies exhaust of the engine.

An exhaust gas purification device that purifies nitrogen oxides (hereinafter referred to as NO _x ) in the exhaust gas is mounted in the exhaust passage connected to the engine. The exhaust emission control device includes, for example, a supply valve that supplies hydrocarbons into exhaust gas and an HC-SCR catalyst that is a catalyst that reduces NO _x, and reduces NO _x to nitrogen by using hydrocarbons as a reducing agent. (For example, refer to Patent Document 1).

JP 2008-75610 A

By the way, in the exhaust emission control device, fuel supplied to the engine is usually used as hydrocarbons supplied into the exhaust, and the fuel contains hydrocarbons such as alkanes. Since alkane is a stable substance, the reduction reaction with the HC-SCR catalyst is difficult to proceed. Therefore, there is a need for an exhaust purification device that can reduce NO _x with higher efficiency.

The techniques of the present disclosure is intended to provide an exhaust purification system that can be enhanced efficiencies reduction of NO _x.

One aspect of the exhaust purification system according to the technology of the present disclosure includes a reduction catalyst that reduces nitrogen oxides contained in exhaust from an engine and a reforming catalyst that reforms hydrocarbons. A reducing agent supply unit that supplies the generated reducing agent to the reduction catalyst; an ozone supply unit that supplies ozone to the reforming catalyst; and a control unit that controls driving of the ozone supply unit. The control unit obtains the amount of the hydrocarbon and the generation efficiency of the reducing agent in the reforming catalyst at different timings, and when the generation efficiency of the reducing agent in the reforming catalyst is equal to each other, A calculation unit is provided that increases the required supply amount of ozone as the amount of hydrocarbons increases. The ozone supply unit supplies the ozone at a level equal to or greater than the required supply amount calculated by the calculation unit.

  According to one aspect of the exhaust purification system of the technology of the present disclosure, when the efficiency of the reforming catalyst acquired at different timings is equal to each other, the calculation unit calculates the higher the amount of hydrocarbon supply. Increase the required supply of ozone. Therefore, compared to a configuration in which the amount of ozone supplied is not increased even when the amount of hydrocarbons is increased, the amount of ozone supplied is insufficient, so that a reducing agent generation reaction, and thus a nitrogen oxide reduction reaction is unlikely to occur. It is suppressed.

In another aspect of the exhaust purification system according to the technology of the present disclosure, the calculation unit is a first calculation unit, and the control unit is configured to control the nitrogen oxide emission amount and the nitrogen oxidation in the reduction catalyst at different timings. A second calculation unit that obtains the reduction efficiency of the product and increases the required supply amount of ozone as the emission amount of the nitrogen oxide is higher when the reduction efficiency of the nitrogen oxide in the reduction catalyst is equal to each other In addition. The ozone supply unit supplies the ozone at a supply amount obtained by adding the required supply amount calculated by the first calculation unit and the required supply amount calculated by the second calculation unit.

In order to facilitate the reduction reaction with the reduction catalyst, it is preferable that the nitrogen oxide is oxidized before the reaction between the nitrogen oxide and the reducing agent.
According to another aspect of the exhaust purification system of the technology of the present disclosure, when the reduction efficiency of nitrogen oxides in the reduction catalysts obtained at different timings is equal to each other, the higher the emission amount of nitrogen oxides, the more ozone Increase the required supply. In addition, the ozone supply unit supplies ozone with a supply amount obtained by adding the calculation results of both the first calculation unit and the second calculation unit. Therefore, compared to the configuration not including the second calculation unit and the configuration in which the ozone supply amount is not increased even when the nitrogen oxide emission amount is increased, the amount of ozone supply is insufficient. It is suppressed that the oxidation reaction, and hence the reduction reaction of nitrogen oxides, hardly occurs.

It is a lineblock diagram showing a schematic structure of an exhaust emission control device in a 1st embodiment of this indication with an engine. It is a functional block diagram showing the composition of the exhaust purification system in a 1st embodiment of this indication. It is a calculation block diagram which shows the form of calculation of the required supply amount in the calculation part with which a control part is provided. It is a block diagram which shows schematically a part of structure of the exhaust gas purification apparatus in 2nd Embodiment of this indication. It is a calculation block diagram which shows a part of calculation form in the calculation part in 2nd Embodiment of this indication. It is a block diagram which shows schematically a part of structure of the exhaust gas purification apparatus in 3rd Embodiment of this indication. It is a calculation block diagram which shows the form of calculation in a 1st ozone amount calculation part. It is a calculation block diagram which shows the form of calculation in a 2nd ozone amount calculation part.

[First Embodiment]
A first embodiment of an exhaust emission control device and an exhaust emission purification system will be described with reference to FIGS. 1 to 3. Below, it demonstrates in order of the structure of an exhaust gas purification apparatus, the structure of the control part with which an exhaust gas purification system is provided, and the form of calculation in a calculation part.

[Configuration of exhaust purification system]
The configuration of the exhaust emission control device will be described with reference to FIG. 1 together with the engine on which the exhaust emission purification device is mounted.

As shown in FIG. 1, an exhaust purification device 20 is mounted in the middle of an exhaust passage 11 connected to an engine 10 that is an example of a hydrocarbon supply unit, and the exhaust purification device 20 has exhaust gas flowing through the exhaust passage 11. oxides and nitrogen oxides hydrocarbons in (hereinafter, NO _x) performs the reduction of. That is, the exhaust gas purification device 20 purifies the exhaust gas flowing through the exhaust passage 11.

For example, natural gas is used as the fuel of the engine 10, and the natural gas may be compressed gaseous natural gas (CNG) or liquid natural gas (LNG). The main component of natural gas is methane, which is an example of a hydrocarbon. Examples of natural gas include alkanes other than methane, such as ethane, propane, butane, and pentane, which are also examples of hydrocarbons, nitrogen, water, etc. Is included. Natural gas contains, for example, 80 mol or more of methane per 100 mol. Therefore, the exhaust gas flowing through the exhaust passage 11 mainly includes, for example, unburned methane, carbon oxide, NO _x , and water.

  The exhaust purification device 20 includes a cylindrical casing 21, and the reforming catalyst 22 and the reduction catalyst 23 are arranged in the casing 21 along the direction in which the exhaust passage 11 extends from the side close to the exhaust inlet 21 a. Are in order. Silver and alumina, or silver and zeolite are used as a material that functions as a catalyst in the reduction catalyst 23. The casing 21 and the reforming catalyst 22 are an example of a reducing agent supply unit that supplies a reducing agent to the reduction catalyst 23.

  An ozone supply valve 24 is attached to the casing 21, and the supply port of the ozone supply valve 24 is upstream of the reforming catalyst 22 in the exhaust flow, for example, the inlet 21 a and the reforming catalyst in the direction in which the exhaust passage 11 extends. 22 between the two. For example, an ozone generation unit 25 that generates ozone from oxygen by discharge is connected to the ozone supply valve 24. The ozone supply valve 24 supplies the ozone generated by the ozone generator 25 into the housing 21. In the first embodiment, the ozone supply valve 24 is an example of an ozone supply unit that supplies ozone to the reforming catalyst 22.

  A fuel addition valve 26 is attached to the housing 21, and the supply port of the fuel addition valve 26 is upstream of the reforming catalyst 22 in the exhaust flow, for example, the exhaust passage 11, as is the supply port of the ozone supply valve 24. It is arranged between the inlet 21 a and the reforming catalyst 22 in the extending direction. The fuel addition valve 26 is connected to, for example, a fuel tank that supplies natural gas to the engine 10, and the fuel addition valve 26 supplies natural gas to the exhaust in the casing 21. Thereby, the fuel addition valve 26 further supplies methane to the exhaust gas containing methane discharged from the engine 10. The fuel addition valve 26 is an example of a hydrocarbon addition unit.

In the exhaust emission control device 20, the reforming catalyst 22 promotes the formation reaction of formaldehyde, which is a reducing agent that reduces NO _x in the exhaust gas. Formaldehyde is generated when ozone supplied from the ozone supply valve 24 to the reforming catalyst 22 oxidizes at least one of methane in the exhaust and methane supplied from the fuel addition valve 26.

  The reforming catalyst 22 promotes the reactions represented by the following reaction formulas (1) to (4). In particular, on the surface of the reforming catalyst 22, the reactions shown in the reaction formulas (1) and (2) proceed. In the exhaust gas purification device 20, formaldehyde is generated, and carbon monoxide in the exhaust gas is oxidized to generate carbon dioxide.

O ₃ + e ⁻ → O ⁻ + O ₂ (1)
CH ₄ + O ⁻ → OH ⁻ + CH ₃ (2)
_{CH 3 · + O 2 → CH} 2 O + HO · (3)
CO + 2HO · → CO ₂ + H ₂ O (4)
In the reduction catalyst 23, NO _x is reduced to nitrogen by the formaldehyde generated by the reforming catalyst 22. Incidentally, in terms of NO _x is reduced in at reducing catalyst 23, NO _x, particularly preferably is one nitric oxide of the NO _x is oxidized to nitrogen dioxide by ozone.

In the exhaust purification device 20, by ozone from the ozone supply valve 24 is supplied to the reforming catalyst 22 oxidizes methane, formaldehyde is generated reactivity with NO _x is an example of a high reduction agent than methane . Then, in the reduction catalyst 23, since the NO _x using formaldehyde is reduced, a stable alkanes compared to formaldehyde as compared to the structure used as the reducing agent, per unit flow rate of the methane supplied to the reforming catalyst 22 The reduction amount of NO _x is increased, that is, the efficiency of reducing NO _x is increased. In addition, since the reduction catalyst 23 promotes an oxidation reaction of carbon monoxide in accordance with the formation reaction of formaldehyde, according to the exhaust purification device 20, the amount of carbon monoxide in the exhaust gas that has left the exhaust purification device 20 is exhausted. It can also be made smaller than the amount of carbon monoxide in the exhaust gas entering the purification device 20.

In addition, in the exhaust purification device 20, when only methane in the exhaust is used for the production of formaldehyde, the methane in the exhaust is used for the production of formaldehyde, so that the oxidation of methane is performed before NOx is reduced. Advances. Therefore, the exhaust gas emitted from the exhaust purification device 20 has less methane in addition to NO _x than the exhaust gas entering the exhaust purification device 20.

[Configuration of control unit]
With reference to FIG. 2, the structure of the control part with which an exhaust gas purification system is provided is demonstrated. The exhaust purification system includes the exhaust purification device 20 described above and a control unit that controls driving of the ozone supply valve 24. Each functional unit constituting the control unit is embodied by an exhaust purification program, hardware such as a logic circuit or an arithmetic circuit, or a composite configuration thereof.

  As illustrated in FIG. 2, the control unit 10C includes an acquisition unit 30 that acquires various types of information, a calculation unit 40 that calculates a required supply amount that is a supply amount of ozone required for the ozone supply valve 24, and a calculation. An output unit 50 that outputs a control signal generated based on the calculated value of the unit 40 is provided. The control unit 10C acquires, through the acquisition unit 30, a measurement value or an estimated value necessary for calculating the required supply amount as an input value.

For example, the acquisition unit 30 measures the intake air amount of the engine 10, the NO _x concentration in the exhaust, the temperature of the reduction catalyst 23, the rotational speed of the engine 10, the torque of the engine 10, and the temperature of the reforming catalyst 22. Get value or estimate. These values may be values output from sensors that measure the respective values, or may be values processed by processing units other than the control unit 10C. Each value may be acquired at every predetermined control cycle, or may be acquired from a processing unit other than the control unit 10C in response to a request from the control unit 10C.

The calculation unit 40 includes a first ozone amount calculation unit 40A that is an example of a first calculation unit, and a second ozone amount calculation unit 40B that is an example of a second calculation unit. The first ozone amount calculation unit 40A calculates the amount of reformed ozone, which is the amount of ozone necessary for reforming methane, using the amount of methane supplied to the reforming catalyst 22. Second ozone amount calculation unit 40B uses the emission of the NO _x from the engine 10, to calculate the amount in which the oxidation of ozone of ozone required for the oxidation of the NO _x. The required supply amount described above is, for example, an added value of the reformed ozone amount and the oxidized ozone amount.

  A drive unit 24D is connected to the control unit 10C, and an ozone supply valve 24 is connected to the drive unit 24D. The drive unit 24D generates a drive signal for driving the ozone supply valve 24. When the drive unit 24D generates the drive signal, the drive unit 24D generates ozone with a drive amount corresponding to the requested supply amount output from the control unit 10C. A drive signal for driving the supply valve 24 is generated. The ozone supply valve 24 supplies the reforming catalyst 22 with an amount of ozone substantially equal to the required supply amount by being driven with a drive amount corresponding to the drive signal output from the drive unit 24D.

[Form of calculation]
With reference to FIG. 3, an example of a calculation form in the first ozone amount calculation unit 40A and an example of a calculation form in the second ozone amount calculation unit 40B will be described. In addition, when the ozone amount is calculated by the first ozone amount calculation unit 40A and the second ozone amount calculation unit 40B, the acquisition unit 30 of the control unit 10C determines the rotation number, torque, concentration of NO _x, the temperature of the reforming catalyst, the intake air amount, and obtains the reduction catalyst temperature.

As shown in FIG. 3, the first ozone amount calculator 40A includes a methane emission amount calculator 41, a fuel calculator 42, a reforming catalyst efficiency calculator 43, and a reformed ozone amount calculator 44. .
In the first ozone amount calculation unit 40A, the methane emission amount calculation unit 41 calculates the emission amount of methane in the exhaust gas using the rotation speed and the torque. For example, the methane emission amount calculation unit 41 calculates the emission amount of methane in the exhaust gas by applying the rotation speed and torque to the methane emission amount calculation map. The methane emission amount calculation map is created in advance based on experiments and stored in the storage unit of the control unit 10C.

The fuel calculation unit 42 calculates the injection amount of fuel supplied from the fuel addition valve 26 to the exhaust gas using the NO _x concentration and the methane emission amount calculated by the methane emission amount calculation unit 41. More specifically, the fuel calculation unit 42 is configured such that the amount of formaldehyde generated from methane in the exhaust gas is reduced to the amount capable of reducing all of the NO _{x in} the exhaust gas with respect to the amount of NO _x contained in the exhaust gas. If not, calculate the fuel injection amount to compensate for the shortage of methane. For example, the fuel calculation unit 42 calculates a higher fuel injection amount as the amount of formaldehyde generated with respect to the NO _x emission amount is smaller. The reforming catalyst efficiency calculation unit 43 calculates the reducing agent generation efficiency in the reforming catalyst 22, which is the reaction efficiency of the reforming catalyst 22, using the temperature of the reforming catalyst 22.

  Similarly, in the first ozone amount calculating unit 40A, the reformed ozone amount calculating unit 44 uses the methane emission amount, the fuel injection amount, and the reaction efficiency of the reforming catalyst 22 to supply ozone to the reforming catalyst 22. The amount of modified ozone, which is the amount, is calculated. When the temperatures of the reforming catalysts 22 acquired by the acquisition unit 30 at different timings are equal to each other, in other words, when the reaction efficiencies of the reforming catalysts 22 calculated at different timings are equal to each other, the reformed ozone The amount calculation unit 44 calculates the reformed ozone amount as follows. That is, the reformed ozone amount calculation unit 44 calculates a higher reformed ozone amount as the supply amount of methane, which is the sum of the methane emission amount and the fuel injection amount, is higher.

The second ozone amount calculation unit 40B includes a NO _x emission amount calculation unit 45, a reduction catalyst efficiency calculation unit 46, and an oxidized ozone amount calculation unit 47. In the second ozone amount calculating section 40B, NO _x emission calculating unit 45 calculates the emission of the NO _x by using the intake air amount and the concentration of NO _x reducing catalyst efficiency calculation section 46, of the reduction catalyst 23 The reduction efficiency of NO _x in the reduction catalyst 23, which is the reaction efficiency of the reduction catalyst 23, is calculated using the temperature. The oxidized ozone amount calculation unit 47 calculates an oxidized ozone amount that is the amount of ozone supplied to the reduction catalyst 23 using the NO _x emission amount and the reaction efficiency of the reduction catalyst 23. When the temperatures of the reduction catalysts 23 acquired at different timings by the acquisition unit 30 are equal to each other, in other words, when the reaction efficiencies of the reduction catalysts 23 calculated at different timings are equal to each other, an ozone oxidation amount calculation unit 47 calculates the amount of oxidized ozone as follows. That is, oxidation ozone amount calculation unit 47, the higher the emissions NO _x, calculates a high oxidation amount of ozone.

  The control unit 10C calculates the reformed ozone amount, which is the calculation result of the first ozone amount calculation unit 40A, and the oxidized ozone amount, which is the calculation result of the second ozone amount calculation unit 40B, for each control cycle, and calculates the ozone amount. The unit 48 calculates and outputs the added value of the reformed ozone amount and the oxidized ozone amount as the required supply amount.

Next, the operation of the exhaust purification device and the exhaust purification system will be described.
When the reaction efficiency of the reforming catalyst 22 calculated at different timings is equal to each other, the first ozone amount calculation unit 40A increases the calculated supply amount of ozone as the supply amount of methane increases. Therefore, compared with the configuration in which the temperatures of the plurality of reforming catalysts 22 are equal to each other and the supply amount of ozone is not increased even when the supply amount of methane is high, the supply amount of ozone is insufficient. It is possible to suppress the generation reaction of NO and thus the reduction reaction of NO _{x from} becoming difficult to occur.

The second ozone amount calculating section 40B, the temperature of the reduction catalyst 23 calculated at different timings from each other is at mutually equal, the higher the emissions NO _x, to increase the supply amount of the ozone to be calculated. In addition, the ozone supply valve 24 supplies ozone with a supply amount obtained by adding the calculation results of both the first ozone amount calculation unit 40A and the second ozone amount calculation unit 40B. Compared Therefore, a configuration which does not include the second ozone amount calculating section 40B, equal temperatures of the plurality of the reduction catalyst 23 to each other, and configured so as not to increase the supply amount of ozone is high in emission of the NO _x Thus, the following state can be suppressed. That is, in order to supply the amount of ozone is not sufficient, the oxidation reaction of the NO _x, therefore, it is prevented that the reduction reaction of the NO _x is less likely to occur.

As described above, according to the first embodiment of the exhaust purification device and the exhaust purification system, the effects listed below can be obtained.
(1) Since a reducing agent having a higher reactivity than methane is used for the reduction reaction in the reduction catalyst 23, the amount of NO _x reduced per unit flow rate of methane as compared with the configuration using methane for the reduction reaction. Becomes larger. That is, the efficiency with which NO _x is reduced is increased.

(2) Since a reducing agent is generated from methane in the exhaust gas, hydrocarbons are oxidized in the exhaust gas before NO _x is reduced. Therefore, when only methane in the exhaust gas is used to generate the reducing agent, the exhaust gas that exits the exhaust gas purification device 20 has less methane in addition to NO _x than the exhaust gas that enters the exhaust gas purification device 20.

(3) Compared with a configuration in which only methane in the exhaust is used for generating the reducing agent, the amount of methane contained in the exhaust can be increased by the fuel addition valve 26, and therefore, NO _x is insufficient due to the lack of methane. Is not reduced.

(4) Compared with a configuration in which the reducing agent generation efficiencies in the reforming catalysts 22 calculated at different timings are equal to each other and the required supply amount of ozone is not increased even when the amount of methane is increased. Therefore, it is possible to prevent the generation reaction of the reducing agent, and hence the reduction reaction of NO _{x from} becoming difficult to occur.

(5) The configuration in which the second ozone amount calculation unit 40B is not provided, and the reduction efficiency of nitrogen oxides in the reduction catalyst 23 calculated at different timings are equal to each other, and the NO _x emission amount is high. However, compared with a configuration in which the calculated supply amount of ozone is not increased, the following state can be suppressed. That is, in order to supply the amount of ozone is not sufficient, the oxidation reaction of the NO _x, therefore, it is prevented that the reduction reaction of the NO _x is less likely to occur.

[Second Embodiment]
With reference to FIG. 4 and FIG. 5, 2nd Embodiment of an exhaust gas purification apparatus and an exhaust gas purification system is described. The second embodiment differs from the first embodiment in the configuration related to the generation of the reducing agent. Therefore, in the following, such differences will be described in detail.

[Configuration of exhaust purification system]
The configuration of the exhaust emission control device will be described with reference to FIG. In FIG. 4, the illustration of the engine to which the exhaust passage is connected is omitted, and the same components as those in FIG. 1 are denoted by the same reference numerals.

  As shown in FIG. 4, the exhaust purification device 60 includes a cylindrical casing 21 disposed in the middle of the exhaust passage 11 as in the first embodiment, and the reduction catalyst 23 is disposed in the exhaust passage 11. Has been placed.

  A reducing agent supply valve 61 is attached to the housing 21, and a supply port of the reducing agent supply valve 61 is disposed between the inlet 21 a and the reduction catalyst 23 in the direction in which the exhaust passage 11 extends. A reducing agent generation chamber 62 different from the casing 21 is connected to the reducing agent supply valve 61. In the reducing agent generation chamber 62, a reforming catalyst 63 and a temperature control unit that adjusts the temperature of the reforming catalyst 63. 64 are arranged. The reducing agent generation chamber 62 is disposed outside the exhaust passage 11 and is connected through the reducing agent supply valve 61 in the middle of the exhaust passage 11. The temperature adjustment unit 64 may be, for example, a heater that heats the reforming catalyst 63, or a heat exchange mechanism that maintains the temperature of the reforming catalyst 63 at a predetermined temperature.

  The reducing agent generation chamber 62 is connected to an ozone generation unit 65 that is an example of an ozone supply unit, and a fuel supply unit 66 that is an example of a hydrocarbon supply unit, and each of the ozone generation unit 65 and the fuel supply unit 66 includes For example, before being connected to the reducing agent generation chamber 62, it is connected to a common pipe. Note that the ozone generation unit 65 and the fuel supply unit 66 may be connected to the reducing agent generation chamber 62 by individual piping.

In the second embodiment, the reducing agent supply valve 61, the reducing agent generation chamber 62, and the reforming catalyst 63 constitute an example of a reducing agent supply unit.
In the exhaust purification device 60, the ozone generated by the ozone generation unit 65 and the fuel from the fuel supply unit 66 are supplied to the reducing agent generation chamber 62. Then, the reforming catalyst 63 disposed in the reducing agent generation chamber 62 promotes a reaction for generating formaldehyde as a reducing agent by oxidation of methane by ozone, and the reducing agent supply valve 61 supplies a reducing agent to the reducing catalyst 23. Supply.

In the exhaust purification device 60, the reducing agent generation chamber 62 in which the reforming catalyst 63 is disposed is provided separately from the casing 21, so that exhaust from the engine 10 is not supplied to the reducing agent generation chamber 62. Therefore, the reaction represented by the above-described reaction formulas (1) to (4) is not affected by the exhaust gas temperature or flow. Therefore, compared with the configuration in which the reforming catalyst is disposed in the casing 21, the amount of reducing agent produced is not affected by the state of exhaust. As a result, compared with the configuration in which the reduction catalyst 23 is disposed in the exhaust passage, the exhaust state is not affected by the temperature of the reduction catalyst 23 or the supply of methane and ozone to the reforming catalyst 22 depending on the exhaust state. This makes it possible to prevent the NO _x reduction reaction from occurring.

  Further, when the reducing agent is generated in the reducing agent generation chamber 62, the temperature adjustment unit 64 controls the temperature of the reforming catalyst 63. For example, the temperature adjustment unit 64 preferably controls the temperature of the reforming catalyst 63 to be lower than the temperature at which ozone is decomposed. Thereby, compared with the case where the temperature of the reforming catalyst 63 is higher than the temperature at which ozone is decomposed, the amount of ozone in the reaction formula (1) described above increases, so the amount of formaldehyde generated also increases. . That is, according to the temperature control unit 64, the amount of formaldehyde generated per unit flow rate of ozone supplied into the reducing agent generation chamber 62 increases by adjusting the temperature of the reforming catalyst 63.

In the housing 21, the reduction catalyst 23 promotes the reduction reaction of NO _{x in} the exhaust gas by the reducing agent.
[Form of calculation]
With reference to FIG. 5, the structure of the control part with which an exhaust gas purification system is provided is demonstrated. Note that the calculation mode of the second embodiment differs from the calculation mode of the first embodiment in the calculation mode related to the calculation of the amount of reformed ozone supplied to the reforming catalyst 63. Therefore, in FIG. 5, only the first ozone amount calculation unit 40A that calculates the reformed ozone amount is shown in the calculation unit 40, and other configurations that are the same as those in the first embodiment are illustrated. It is omitted. Moreover, in FIG. 5, the same code | symbol is attached | subjected with respect to the structure equivalent to 1st Embodiment.

As shown in FIG. 5, the first ozone amount calculator 40A includes a fuel calculator 71, a reforming catalyst efficiency calculator 43, and a reformed ozone amount calculator 72. The fuel calculation unit 71 calculates the amount of fuel supplied from the fuel supply unit 66 to the reducing agent generation chamber 62 using the NO _x concentration. That is, the control unit 10C of the second embodiment calculates the amount of fuel for reducing NO _x in the exhaust gas without taking into account the amount of methane in the exhaust gas. Fuel calculating unit 71, as the concentration of NO _x is high and calculates the supply amount of the high fuel. The reforming catalyst efficiency calculation unit 43 calculates the reaction efficiency of the reforming catalyst 22 using the temperature of the reforming catalyst 22 as in the first embodiment.

  The reformed ozone amount calculation unit 72 calculates a reformed ozone amount that is the amount of ozone supplied to the reforming catalyst 22 using the fuel supply amount and the reaction efficiency of the reforming catalyst 22. When the temperatures of the reforming catalysts 22 acquired by the acquisition unit 30 at different timings are equal to each other, in other words, when the reaction efficiencies of the reforming catalysts 22 calculated at different timings are equal to each other, the reformed ozone The amount calculation unit 72 calculates the reformed ozone amount as follows. That is, the reformed ozone amount calculating unit 72 calculates a higher reformed ozone amount as the fuel supply amount, that is, the methane supply amount is higher.

Note that the amount of ozone calculated by the modified ozone amount calculation unit 72 is used for calculation of the required supply amount by the ozone amount calculation unit 48 as in the first embodiment.
As described above, according to the second embodiment of the exhaust gas purification apparatus and the exhaust gas purification system, the following effects can be obtained in addition to the effects (1) and (4) described above.

(6) Since the reaction for generating the reducing agent is performed in the reducing agent generation chamber 62 different from the exhaust passage 11, the generation reaction of the reducing agent is not affected by the temperature or flow of the exhaust. Therefore, as compared with the configuration in which the reducing agent generation reaction is performed in the exhaust passage 11, the reducing agent is stably generated. As a result, the NO _x reduction reaction at the reduction catalyst is less affected by the exhaust state.

(7) first ozone amount calculating section 40A, as the concentration of NO _x is high, in order to calculate the supply amount of the high fuel configuration and the same amount of fuel in the reducing agent generation chamber regardless concentration of NO _x fed Compared with the exhausted NO _x , the amount of reducing agent is suppressed from being insufficient.

[Third Embodiment]
With reference to FIGS. 6 to 8, a third embodiment of the exhaust purification device and the exhaust purification system will be described. Note that the third embodiment differs from the first embodiment in that the exhaust purification device includes a three-way catalyst. Therefore, in the following, such differences will be described in detail.

[Configuration of exhaust purification system]
The configuration of the exhaust emission control device will be described with reference to FIG. In FIG. 6, as in FIG. 4, the illustration of the engine to which the exhaust passage is connected is omitted, and the same components as those in FIG. 1 are denoted by the same reference numerals.

  As shown in FIG. 6, a three-way catalyst 81 is disposed in the casing 21 of the exhaust purification device 80 between the inlet 21 a and the fuel addition valve 26 in the direction in which the exhaust passage 11 extends. In the exhaust purification device 80, the fuel addition valve 26 adds fuel to the exhaust gas that has passed through the three-way catalyst 81.

That is, in the exhaust purification device 80, in addition to the reforming catalyst 22 and the reduction catalyst 23, the three-way catalyst 81 also oxidizes hydrocarbons discharged from the engine 10, and reduces NO _x . Therefore, as compared with the configuration in which the three-way catalyst 81 is not provided, the amount of NO _x is smaller in the exhaust gas that has exited the exhaust purification device 80 than in the exhaust gas that enters the exhaust purification device 80. When only the methane in the exhaust gas is used for the generation of the reducing agent, the exhaust gas that has exited the exhaust gas purification device 80 is more than the exhaust gas that enters the exhaust gas purification device 80 as compared with a configuration that does not include a three-way catalyst. The amount of methane is reduced.

[Form of calculation]
With reference to FIG. 7 and FIG. 8, the form of calculation of the ozone amount in the calculation unit will be described. Note that the calculation mode of the third embodiment is different from the calculation mode of the first embodiment in that each of the calculation of the methane emission amount, the calculation of the fuel amount, and the calculation of the NO _x emission amount is different. Different. Further, when these values are calculated in the third embodiment, unlike the first embodiment, the obtaining unit 30, the rotational speed as a value required for the calculation of the amount of ozone, torque, NO _x concentration, modification In addition to the temperature of the catalyst, the intake air amount, and the reduction catalyst temperature, the air-fuel ratio is acquired. Note that the air-fuel ratio may be acquired from a sensor that measures the air-fuel ratio, as with other values, or may be acquired through a processing unit other than the control unit 10C. The air-fuel ratio may be input every predetermined control cycle, or may be acquired from a processing unit other than the control unit 10C in response to a request from the control unit 10C.

As shown in FIG. 7, the first ozone amount calculation unit 40A includes a methane oxidation amount calculation unit 91, a methane emission amount calculation unit 92, a fuel calculation unit 93, a reformed ozone amount calculation unit 94, and reforming catalyst efficiency. A calculation unit 43 is provided. The methane oxidation amount calculation unit 91 calculates the methane oxidation amount using the air-fuel ratio, and the methane emission amount calculation unit 92 calculates a higher methane oxidation amount as the air-fuel ratio is closer to the theoretical air-fuel ratio. The methane emission amount calculation unit 92 calculates the emission amount of methane supplied to the reforming catalyst 22 using the rotation speed, torque, and oxidation amount of methane. When the rotational speeds acquired at different timings are equal to each other and the torques acquired at different timings are equal to each other, the methane emission amount calculation unit 92 decreases the methane emission amount as the methane oxidation amount increases. calculate. That is, unlike the methane emission amount calculation unit 41 of the first embodiment, the methane emission amount calculation unit 92 of the third embodiment takes into consideration the amount of methane oxidized by the three-way catalyst 81 and discharges methane. Is calculated. Fuel calculating unit 93, using the emissions and the concentration of NO _x methane, calculates the injection quantity of fuel to be injected into the exhaust having passed through the three-way catalyst 81.

  The reformed ozone amount calculation unit 94 calculates the reformed ozone amount using the methane emission amount, the injection amount, and the reaction efficiency of the reforming catalyst 22. Since the reformed ozone amount calculation unit 94 uses the methane emission amount in which the methane oxidation amount is added, the methane oxidation amount is also added to the reformed ozone amount.

As shown in FIG. 8, the second ozone amount calculation unit 40B includes a NO _x reduction amount calculation unit 95, a NO _x emission amount calculation unit 96, an oxidized ozone amount calculation unit 47, and a reduction catalyst efficiency calculation unit 46. ing. _The NO _x reduction amount calculating section 95 calculates the amount of reduced NO _x at the three-way catalyst 81 with the air-fuel ratio, _the NO _x reduction amount calculating section 95, the air-fuel ratio is closer to the stoichiometric air-fuel ratio, The amount of reduction of high NO _x is calculated. NO _x emission calculating unit 96, intake air amount, NO _x concentration, and calculates the emissions of the NO _x with a reducing amount of the NO _x. More specifically, the NO _x emission amount calculation unit 96 differs from the NO _x emission amount calculation unit 45 of the first embodiment in that the amount of NO _x reduced by the three-way catalyst 81 with respect to the amount of NO _{x in} the exhaust gas. Is calculated as the NO _x emission amount. NO _x emission calculating unit 96 is equal intake air amount mutually acquired at different timings, and, when concentration of NO _x is equal to each other, the higher the amount of reduction of NO _x, emissions of low NO _x calculate.

The oxidized ozone amount calculation unit 97 calculates an oxidized ozone amount that is the amount of ozone supplied to the reduction catalyst 23 using the NO _x emission amount and the reaction efficiency of the reduction catalyst 23. Oxidizing ozone amount calculation unit 97, for using the emissions of NOx reduction amount is consideration of the NO _x, the reducing amount of the NO _x is also considered to oxidation amount of ozone.

  Note that the reformed ozone amount calculated by the first ozone amount calculating unit 40A and the oxidized ozone amount calculated by the second ozone amount calculating unit 40B are requested by the ozone amount calculating unit 48 as in the first embodiment. Used for quantity calculation.

The exhaust gas purification system, the control unit 10C calculates the amount of reduced NO _x, the required supply amount while taking into account the amount of oxidizing methane in a three-way catalyst 81. Therefore, an excess or deficiency of the amount of ozone supplied into the exhaust gas can be suppressed as compared with a configuration in which the amount of reduced NO _{x and} the amount of oxidized methane are not taken into account.

  As described above, according to the third embodiment of the exhaust gas purification device and the exhaust gas purification system, the effects listed below can be obtained in addition to the effects obtained by the first embodiment described above.

(8) Compared with the configuration not including the three-way catalyst 81, the amount of NO _x is smaller in the exhaust gas that has exited the exhaust gas purification device 80 than in the exhaust gas that enters the exhaust gas purification device 80.
(9) The control unit 10C is, for calculating the required supply quantity while taking into account the reduction of the oxidized amount and NO _x methane in the three-way catalyst 81, not taking into account the reduction of the oxidized amount and NO _x methane Compared with the configuration, an excess or deficiency of the amount of ozone supplied into the exhaust gas is suppressed.

Each of the first to third embodiments described above can be implemented with appropriate modifications as follows.
-In each embodiment, the calculation part 40 does not need to be provided with the 2nd ozone amount calculation part 40B. Even with such a configuration, the reducing agent can be generated by supplying the amount of ozone calculated by the first ozone amount calculation unit 40A to the reforming catalyst 22. Therefore, it is possible to increase the oxidation amount of NO _x with respect to the amount of methane supplied to the reforming catalyst 22 as compared with the configuration using methane as the reducing agent.

  In each embodiment, the first ozone amount calculation unit 40A may not include the reforming catalyst efficiency calculation unit 43. Even in such a configuration, the reformed ozone amount calculation unit 44 calculates a higher ozone supply amount as the methane supply amount to the reforming catalyst 22 is higher. Compared with the configuration in which the amount is set, the shortage of ozone supply relative to the amount of methane supply can be suppressed.

In each embodiment, the second ozone amount calculation unit 40B may not include the reduction catalyst efficiency calculation unit 46. Even in such a configuration, the higher the amount of NO _x emitted, the higher the amount of ozone _x is calculated, and the higher the amount of ozone, the higher the amount of ozone, so that a constant amount of ozone is set regardless of the amount of NO _x emitted. compared with, the supply amount of ozone is suppressed no small that insufficient can against emissions NO _x.

  In each embodiment, the control unit 10C may not be configured to calculate the methane emission amount and the reducing agent generation efficiency in the reforming catalyst in the first ozone amount calculation unit 40A. The configuration may be such that the emission amount of methane and the generation efficiency of the reducing agent in the reforming catalyst are acquired as detected values or estimated values.

In each embodiment, the control unit 10C includes a emissions of the NO _x in the second ozone amount calculating section 40B, may not be configured to calculate the reduction efficiency of the NO _x in the reduction catalyst, the controller 10C is and emissions of the NO _x, the reducing efficiency and the detection value of the NO _x in the reduction catalyst, or may be configured to obtain as an estimate.

In each embodiment, the first ozone amount calculation unit 40A may not include the reformed ozone amount calculation unit and the oxidized ozone amount calculation unit, and may include only the reformed ozone amount setting unit. That is, a configuration in which the amount of ozone supplied into the exhaust gas is set to a constant amount without being calculated in consideration of the NO _x emission amount, the methane emission amount, and the temperature of the reforming catalyst 22. But you can. Even if it is such a structure, since ozone is supplied with respect to exhaust_gas | exhaustion, the effect according to (1) mentioned above can be acquired.

In the first and third embodiments, the fuel calculating unit 42,93 may be configured to calculate the injection quantity of fuel using only concentration of NO _x, i.e., without emission of methane is taken into account A configuration in which the amount of fuel is calculated may be employed.

In each embodiment, the first ozone amount calculation unit 40A may not include the fuel calculation units 42 and 71. That is, the first ozone amount calculation unit 40A is provided with a fuel setting unit, regardless of the emission of the NO _x concentration and methane, may be configured to set a fixed amount as the injection quantity. Even if it is such a structure, as long as a reducing agent is produced | generated from methane and ozone, the effect according to said (1) can be acquired.

  In the second embodiment, the reducing agent supply valve 61 may be omitted, and the reducing agent generation chamber 62 and the housing 21 may be connected by a passage. Even in such a configuration, the reducing agent generated in the reducing agent generation chamber 62 is supplied to the exhaust gas flowing through the housing 21 and the generation of the reducing agent is performed in a region where the exhaust gas does not flow. Therefore, the effect according to (1), (6), and (7) described above can be obtained.

  In the first embodiment and the third embodiment, the exhaust purification devices 20 and 80 may be configured not to include the fuel addition valve 26. Even if it is such a structure, since the methane in exhaust_gas | exhaustion is used for the production | generation of a reducing agent, the effect according to (1) mentioned above can be acquired not a little.

  In the first and third embodiments, when the fuel addition valve 26 supplies fuel to the exhaust, the supply of ozone from the ozone supply valve 24 and the supply of fuel from the fuel addition valve 26 are performed simultaneously. May be. Alternatively, the fuel supply from the fuel addition valve 26 may be performed prior to the ozone supply from the ozone supply valve 24, or the ozone supply from the ozone supply valve 24 may be performed from the fuel addition valve 26. It may be performed prior to the fuel supply. In order to increase the efficiency of the reducing agent generation reaction and the reduction reaction with respect to the supplied fuel amount or ozone amount, it is preferable that the fuel supply and the ozone supply be performed simultaneously.

  -Also in 2nd Embodiment, the ozone from the ozone production | generation part 65 and the fuel from the fuel supply part 66 may be simultaneously supplied with respect to the reducing agent production | generation chamber 62, and may be supplied separately. In order to increase the efficiency of the reducing agent generation reaction and the reduction reaction with respect to the supplied fuel amount or ozone amount, it is preferable that the fuel supply and the ozone supply be performed simultaneously.

  In the second embodiment, the exhaust passage through which the exhaust from the engine flows branches from the upstream of the inlet 21a toward the reducing agent generation chamber 62, and the exhaust flowing through the exhaust passage is also supplied to the reducing agent generation chamber 62. May be.

  The exhaust purification device 20 of the first embodiment is disposed outside the exhaust passage 11 and is connected to the reductant generation chamber connected in the middle of the exhaust passage 11, the reforming catalyst and the reductant disposed in the reductant generation chamber. The configuration may further include an ozone supply unit that supplies ozone to the generation chamber and a fuel supply unit that supplies methane to the reducing agent generation chamber. At this time, the exhaust passage branches from the upstream of the reforming catalyst 22 accommodated in the casing 21 toward the reducing agent generation chamber, and the exhaust gas flowing through the exhaust passage may be supplied to the reducing agent generation chamber. . According to such a configuration, the reducing agent is generated in the exhaust passage and the reducing agent generation chamber.

  The exhaust purification device 80 of the third embodiment supplies ozone to the reducing agent generation chamber, the reforming catalyst disposed in the reducing agent generation chamber, and the reducing agent generation chamber, as in the exhaust purification device 20 of the first embodiment. The configuration may further include an ozone supply unit and a fuel supply unit that supplies methane to the reducing agent generation chamber. At this time, the exhaust passage branches from the upstream of the reforming catalyst 22 accommodated in the casing 21 toward the reducing agent generation chamber, and the exhaust gas flowing through the exhaust passage may be supplied to the reducing agent generation chamber. . According to such a configuration, the reducing agent is generated in the exhaust passage and the reducing agent generation chamber.

  In the first embodiment, the supply port of the ozone supply valve 24 may not be disposed between the inlet 21 a and the reforming catalyst 22 in the direction in which the exhaust passage 11 extends, and the exhaust passage 11 rather than the reforming catalyst 22. What is necessary is just to be arrange | positioned at the engine 10 side in the extending direction. Even with such a configuration, ozone from the ozone supply valve 24 is supplied to the reforming catalyst 22 not a little.

  In the first embodiment, the supply port of the fuel addition valve 26 may not be disposed between the inlet 21 a and the reforming catalyst 22 in the direction in which the exhaust passage 11 extends, and the exhaust passage 11 rather than the reforming catalyst 22. What is necessary is just to be arrange | positioned at the engine 10 side in the extending direction. Even with such a configuration, the fuel from the fuel addition valve 26 is supplied to the reforming catalyst 22 not a little.

  -In 2nd Embodiment, the supply port of the reducing agent supply valve 61 does not need to be arrange | positioned between the inflow port 21a and the reduction catalyst 23 in the direction where the exhaust passage 11 is extended, and the exhaust passage 11 is rather than the reduction catalyst 23. What is necessary is just to arrange | position at the engine 10 side in the extending direction. Even with such a configuration, the reducing agent from the reducing agent supply valve 61 is supplied to the reduction catalyst 23 in no small amount.

-As a material which functions as a catalyst in the reduction catalyst 23, materials other than silver and alumina, or silver and zeolite may be used. In short, any material that functions as a catalyst in the NO _x reduction reaction may be used.

-The ozone production | generation part 25 may be the structure which produces | generates ozone by electrolysis of water etc., and the ultraviolet lamp which produces | generates the ultraviolet-ray containing ozone may be sufficient as it.
The fuel supply unit may not be a fuel tank, but may be a fuel supply unit that is provided separately from the fuel tank and stores fuel that is supplied only to the exhaust.

In the first embodiment and the third embodiment, the shortage of the methane emission amount relative to the NO _x emission amount may not be supplied as fuel from the fuel addition valve 26. Even in such a configuration, the amount of reduction of NO _x is not less than that in a configuration in which fuel is not supplied.

-In 2nd Embodiment, the exhaust gas purification apparatus 60 does not need to be provided with the temperature control part 64. FIG.
-In 2nd Embodiment, even if a three way catalyst is arrange | positioned between the inflow port 21a and the reducing agent supply valve 61 in the direction where the exhaust passage 11 is extended in the housing | casing 21, like 3rd Embodiment. Good. In such a case, the second ozone amount calculation unit 40B of the calculation unit 40 may have a configuration equivalent to the second ozone amount calculation unit 40B of the third embodiment.

In the third embodiment, the fuel calculation unit 93 of the first ozone amount calculation unit 40A performs the NO _x reduction amount calculation unit 95 of the second ozone amount calculation unit 40B in addition to the NO _x concentration and the methane emission amount. There may be calculated injection quantity of the fuel with a reducing amount of the calculated NO _x.

- In the third embodiment, the control unit 10C is the amount of methane oxidized by the three-way catalyst 81, and, modified ozone amount without considering the amount of reduced NO _x, and the amount of oxidizing ozone It may be calculated.

-Light oil or gasoline may be used for the fuel of the engine 10. Even this structure, by using the reforming catalyst and ozone, generating not a little high reactivity reducing agent and NO _x than hydrocarbons from a hydrocarbon alkane or the like contained in gas oil, gasoline Is possible. Therefore, the light oil or gasoline as compared with the structure used as the reducing agent of the NO _x, the amount of the NO _x is reduced to per unit flow rate of the hydrocarbon increases. That is, the efficiency with which NO _x is reduced is increased.

DESCRIPTION OF SYMBOLS 10 ... Engine, 10C ... Control part, 11 ... Exhaust passage, 20, 60, 80 ... Exhaust gas purification device, 21 ... Case, 21a ... Inlet, 22, 63 ... Reforming catalyst, 23 ... Reduction catalyst, 24 ... Ozone Supply valve, 24D ... drive unit, 25, 65 ... ozone generation unit, 26 ... fuel addition valve, 30 ... acquisition unit, 40 ... calculation unit, 40A ... first ozone amount calculation unit, 40B ... second ozone amount calculation unit, 41,92 ... methane emission calculating unit, 42,71,93 ... fuel calculating section, 43,72 ... reforming catalyst efficiency calculation unit, 44,94 ... reformed ozone amount calculating unit, 45,96 ... NO _x emissions Calculation part 46 ... Reduction catalyst efficiency calculation part 47, 97 ... Oxidized ozone amount calculation part, 48 ... Ozone amount calculation part, 50 ... Output part, 61 ... Reducing agent supply valve, 62 ... Reducing agent production chamber, 64 ... Temperature Control unit, 66 ... Fuel supply unit, 81 ... Three-way catalyst, 91 ... Methane oxidation Amount calculation unit, 95 ... NO _x reduction amount calculating unit.

Claims (2)

A reduction catalyst for reducing nitrogen oxides contained in the exhaust from the engine;
A reducing agent supply unit having a reforming catalyst for reforming hydrocarbons, and supplying a reducing agent generated by reforming the hydrocarbons to the reduction catalyst;
An ozone supply unit for supplying ozone to the reforming catalyst;
A control unit for controlling the driving of the ozone supply unit,
The controller is
Obtaining the amount of the hydrocarbon and the production efficiency of the reducing agent in the reforming catalyst at different timings,
When the production efficiency of the reducing agent in the reforming catalyst is equal to each other, a calculation unit that increases the required supply amount of ozone as the amount of the hydrocarbon is higher,
The ozone supply unit
An exhaust gas purification system that supplies the ozone at a level equal to or greater than the required supply amount calculated by the calculation unit. The calculation unit is a first calculation unit;
The controller is
Obtaining the emission amount of the nitrogen oxides and the reduction efficiency of the nitrogen oxides in the reduction catalyst at mutually different timings,
When the reduction efficiency of the nitrogen oxides in the reduction catalyst is equal to each other, further comprising a second calculation unit that increases the required supply amount of ozone as the emission amount of the nitrogen oxides increases.
The ozone supply unit
An exhaust purifying system according to claim 1 for supplying the ozone supply amount obtained by adding the required supply amount of the second calculating unit and the required supply amount of the first calculation unit is calculated is calculated.

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