JP2005207316A - Apparatus and method of processing exhaust gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide exhaust gas processing apparatus capable of removing unburned hydrocarbon contained in exhaust gas with high efficiency and reliability in a simple configuration. <P>SOLUTION: This exhaust gas processing apparatus includes a hydrocarbon conversion device 3 for converting at least one part of hydrocarbon in exhaust gas into carbon monoxide mainly, a catalyst purification device 4 for purifying the exhaust gas processed by the hydrocarbon conversion device 3 using a catalyst, and a conversion control device 8 for controlling the hydrocarbon conversion device 3 so as to convert at least one part of hydrocarbon in the exhaust gas into carbon monoxide mainly. A discharge plasma conversion device for converting the hydrocarbon into the carbon monoxide, or an ozone reaction device for converting the hydrocarbon into the carbon monoxide by deriving a reaction of the exhaust gas and the ozone. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an exhaust gas processing apparatus and an exhaust gas processing method for purifying harmful components in exhaust gas exhausted from an internal combustion engine or the like.

  Unburned hydrocarbons are contained in the exhaust gas emitted from automobile engines. In order to purify the hydrocarbons contained in the exhaust gas, a catalyst is usually used. However, the catalyst does not show activity until a certain temperature is exceeded. Therefore, in a state where the catalyst temperature is low, such as immediately after starting the engine, purification of unburned hydrocarbons in the exhaust gas cannot be sufficiently realized by using the catalyst.

Therefore, the unburned hydrocarbon is adsorbed on the adsorbent until the temperature of the catalyst rises to the activation temperature, and the unburned hydrocarbon adsorbed on the adsorbent is removed when the catalyst reaches the operating temperature or higher. An exhaust gas purification device that is separated and purified by a catalyst has been proposed (see, for example, Patent Document 1).
Alternatively, an exhaust gas processing apparatus for automobiles in which a plasma processing apparatus is inserted into an exhaust line of an engine and a catalytic purification apparatus is connected downstream of the plasma processing apparatus has been proposed (for example, see Patent Documents 2 and 3). ).

Japanese Examined Patent Publication No. 6-15016 (Pages 2-4, Fig. 2) Japanese Unexamined Patent Publication No. Hei 5-99856 (pages 3 to 5, FIGS. 1, 3, and 4) JP-A-6-335621 (pages 2-5, FIG. 1)

  However, in the case of a conventional exhaust gas purification device using an adsorbent, if the hydrocarbon is desorbed from the adsorbent before the temperature of the catalyst rises to the operating temperature, or if it is exposed to a high temperature, the performance of the adsorbent deteriorates. Therefore, there is a problem of lack of reliability. Further, in order to avoid such a problem, the conventional exhaust gas purification apparatus using an adsorbent requires a complicated configuration including a bypass flow path and a switching valve as shown in Patent Document 1. End up.

Further, the conventional exhaust gas processing apparatus including the plasma processing apparatus described above is made harmless by converting nitrogen oxide (NO _x ) in the exhaust gas to nitrogen (N ₂ ), or unburned by the plasma processing apparatus. A hydrocarbon is converted into carbon dioxide (CO ₂ ) by oxidation. However, since the amount of electric power required becomes large, it becomes necessary to increase the number of storage batteries of an automobile, and the fuel consumption deteriorates, so that the problem of high efficiency remains.

  The present invention has been made to solve the above-described problems, and provides an exhaust gas treatment apparatus and an exhaust gas treatment method capable of efficiently purifying unburned hydrocarbons contained in exhaust gas. It is intended to provide.

  The exhaust gas treatment device according to the present invention is a hydrocarbon conversion device that converts at least a part of hydrocarbons in the exhaust gas into carbon monoxide, and the exhaust gas treated by the hydrocarbon conversion device is purified using a catalyst. And a conversion control device for controlling the hydrocarbon conversion device so as to mainly convert at least a part of hydrocarbons in the exhaust gas into carbon monoxide.

  According to the exhaust gas treatment device of the present invention, the hydrocarbon conversion device controlled by the conversion control device adds hydrocarbons to carbon dioxide as in the past by converting hydrocarbons mainly into carbon monoxide. Exhaust gas because hydrocarbons can be converted with less power compared to hydrocarbon converters, and the subsequent catalytic cleaner can clean the converted carbon monoxide without energy consumption. There is an effect that hydrocarbons can be efficiently purified and purified as a whole treatment apparatus.

Embodiment 1 FIG.
FIG. 1 is a schematic diagram showing a basic configuration of an engine apparatus including an exhaust gas treatment apparatus according to Embodiment 1. As shown in FIG. 1, the engine device includes an exhaust manifold 2, a hydrocarbon conversion device 3, a catalytic purification device 4, and an exhaust gas passage disposed in order in an exhaust gas path from the engine body 1 to the exhaust gas outlet 6. The silencer 5 is included. These parts from the exhaust manifold 2 to the exhaust gas outlet 6 are connected by an exhaust pipe 7. The conversion control device 8 controls the hydrocarbon conversion device 3 to convert at least part of the hydrocarbons in the exhaust gas mainly into carbon monoxide.

  Several cylinders (not shown) are provided inside the engine body 1, and exhaust gas combusted inside the cylinder is released to the outside of the engine body 1. The exhaust manifold 2 forms a part of the exhaust pipe 7 and collects exhaust gases exhausted from the plurality of cylinders into one. The exhaust gas collected by the exhaust manifold 2 is introduced into the hydrocarbon conversion device 3 and subjected to conversion treatment. The conversion treatment referred to here is to convert at least part of hydrocarbons contained in the exhaust gas mainly into carbon monoxide. Thereafter, the exhaust gas containing carbon monoxide obtained by the conversion reaches the catalytic purification device 4 through the exhaust pipe 7 and is cleaned in the catalytic purification device 4. The purification treatment referred to here is conversion of carbon monoxide, hydrocarbons, and the like contained in the exhaust gas into carbon dioxide. As the catalytic purification device 4, for example, a device formed by filling an exhaust pipe with a honeycomb-shaped ceramic base material that has been conventionally used and having a noble metal catalyst such as platinum supported thereon is used. Can do.

  The exhaust gas purified by the catalytic purification device 4 passes through the silencer 5 and is exhausted to the outside from the exhaust gas outlet 6. The silencer 5 is a device that reduces noise caused by exhaust, and a conventionally used device can be used.

  FIG. 2 is a schematic diagram showing a specific configuration of an engine apparatus including the exhaust gas processing apparatus of the first embodiment. As shown in FIG. 2, the exhaust gas treatment apparatus of the present embodiment includes a discharge plasma conversion device 31 as a hydrocarbon conversion device. A high voltage power source (not shown) is connected to the discharge plasma conversion device 31 via a plasma generation control device 32 as a conversion control device. The plasma generation control device 32 controls the operation of the discharge plasma conversion device 31 by controlling the high voltage power source based on the monitored information on the generation status of the discharge plasma and the information such as the rotational speed of the engine body 1 and the exhaust gas temperature. The amount of plasma generation is controlled by controlling.

  FIG. 3 is a partially broken perspective view showing the discharge plasma conversion device 31 more specifically. The discharge plasma conversion device 31 includes an exhaust pipe 21 and has a structure in which exhaust gas passes through the exhaust pipe 21. For example, the exhaust gas can be passed from left to right in FIG. At both ends of the exhaust pipe 21, flanges 28 are provided so that the exhaust manifold 2 and the exhaust pipe 7 can be connected. The material of the exhaust pipe 21 may be an insulating material and is not limited to one. For example, ceramic such as aluminum oxide can be used.

  Inside the exhaust pipe 21, a high voltage electrode 22 fixed by a mesh 23 is installed so as to be coaxial with the exhaust pipe 21. In order to supply a voltage to the high voltage electrode 22, the high voltage electrode terminal 22 a and the power supply terminal 22 b are connected by a high voltage cable 26. The power supply terminal 22b is connected to the plasma generation control device 32 by a cable (not shown). A ground electrode 24 is attached to the periphery (outer peripheral surface) of the exhaust pipe 21 so as to contact the exhaust pipe 21. The ground electrode 24 is fastened with a fixing screw 27. Further, a cable (not shown) for connecting to the plasma generation control device 32 is also attached by the fixing screw 27. In addition, the material of the mesh 23 should just be an insulator, and although it is not limited to one, For example, ceramics, such as aluminum oxide, can be used. Further, the material of the high voltage electrode 22 and the ground electrode 24 may be a conductor and is not limited to one. For example, stainless steel can be used.

  In the discharge plasma conversion device 31 configured as described above, an AC high voltage or a pulsed high voltage is applied between the high voltage electrode 22 and the ground electrode 24, whereby the high voltage electrode 22 and the ceramic exhaust pipe 21 are connected. Silent discharge can be generated in the space. The length in the gas flow direction of the space where silent discharge occurs is the same as the length of the ground electrode 24 in the gas flow direction. That is, silent discharge occurs in the space surrounded by the ground electrode 24. The exhaust gas introduced into this discharge plasma conversion device passes through the mesh 23 and the silent discharge space. In this passage process, the exhaust gas undergoes a chemical reaction by the discharge plasma.

Next, the experimental results of treating exhaust gas using the above-described discharge plasma conversion device 31 shown in FIG. 3 will be described.
The exhaust gas of the engine body 1 was simulated as follows.
Propane concentration: 7000 ppm,
O ₂ concentration: 10%,
When this simulated gas was passed through the discharge plasma conversion device 31 while changing the electric power, the result shown in FIG. 4 was obtained. In this experiment, when the electric power consumed by the discharge is W [J / s] and the processing flow rate of the simulated gas is Q [L / s], the energy W consumed for the processing per 1 L of the exhaust gas. / Q was evaluated as a value. As the amount of energy consumed per unit volume increases, the concentration of hydrocarbons decreases and the concentration of carbon monoxide and carbon dioxide increases, that is, the rate at which hydrocarbons are converted to carbon monoxide and carbon dioxide increases. I understand that. In addition, the ratio of carbon monoxide and carbon dioxide at that time is much higher in carbon monoxide. When the energy consumption per unit volume is 40 [J / L], about half of the hydrocarbons are converted, and most of them are converted to carbon monoxide.

  When the energy consumption per unit volume is 40 [J / L], if the exhaust gas flow rate from the engine body 1 is 10 [L / sec], the required power is 400 [W], which is 1 [kW], which is conventionally known. It becomes a discharge plasma conversion device with low power consumption as compared with the required power of more than about. This is because the purpose is to convert hydrocarbons to carbon monoxide, and when oxidizing to carbon dioxide, several times more power is required.

  The discharge plasma conversion device 31 is controlled by a plasma generation control device 32 as a conversion control device so that at least a part of the hydrocarbons in the exhaust gas is mainly converted into carbon monoxide as described above. Yes. More specifically, this control by the plasma generation control device 32 is performed, for example, by controlling the energy consumption per unit volume of the exhaust gas in the discharge plasma conversion device 31. As described above, since the plasma generation control device 32 is controlled by the plasma generation control device 32 so as to mainly convert hydrocarbons to carbon monoxide, the case where the plasma generation control device 32 operates so as to convert the hydrocarbons to carbon dioxide. Requires much less energy.

  Further, the temperature of the exhaust gas when the exhaust gas from the engine body 1 passes through the discharge plasma conversion device 31 through the exhaust manifold 2 is low when the engine body 1 is started, but becomes higher as the vehicle runs at a higher speed. . When the temperature of the exhaust gas increases, the hydrocarbon conversion rate in the discharge plasma conversion device 31 is improved. Note that the performance of the discharge plasma conversion device 31 does not deteriorate even when exposed to high temperatures.

  Next, the catalytic purification device 4 of the present embodiment will be described. The temperature of the purification rate of the catalytic purification device 4 when the catalyst purification device 4 uses a catalyst having a honeycomb-like ceramic base material that is generally used and supporting a noble metal, particularly platinum (Pt). The characteristics are shown in FIG. As shown in this figure, propane, which is a representative hydrocarbon, cannot be completely purified unless it reaches about 300 ° C., whereas carbon monoxide reaches a purification rate of 50% at about 80 ° C., and almost 100% at 100 ° C. 100% purified. In addition, since the catalyst type cleaning apparatus 4 of this Embodiment operate | moves using the heat | fever of exhaust gas, it can clean carbon monoxide without energy consumption for the operation | movement.

  The treatment temperature in the catalytic purification device 4 must be raised to 300 ° C. at which the hydrocarbon can be directly purified in the absence of the discharge plasma conversion device 31. However, the catalytic purification device 4 has only to perform a treatment for detoxifying carbon monoxide to carbon dioxide when the discharge plasma conversion device 31 is used upstream thereof. As long as it has been converted to carbon monoxide to an appropriate ratio in order to satisfy the environmental standards, as described above, even if the catalytic purification device 4 is operated at a processing temperature of 100 ° C. or less, the exhaust gas passed through the discharge plasma conversion device 31 is exhausted. The gas can be cleaned. Therefore, according to the exhaust gas treatment device or the exhaust gas treatment method of the present embodiment using the discharge plasma conversion device 31 and the catalytic purification device 4, the carbonization is performed even at a low temperature immediately after the start of the engine body 1. Exhaust gas containing hydrogen can be cleaned. As a result, the exhaust gas treatment device of the present embodiment is a highly reliable exhaust gas treatment device that can reliably clean the exhaust gas even when the engine body 1 or the exhaust gas treatment device is at a low temperature.

  In addition, since the reaction in which carbon monoxide is rendered harmless (oxidized) in the catalytic purification device 4 is accompanied by heat generation, the temperature rise of the catalyst of the catalytic purification device 4 is faster than when carbon dioxide is fed, and the hydrocarbon is directly removed. It quickly reaches 300 ° C., which can be converted to carbon dioxide. Therefore, the time until it becomes possible to purify the hydrocarbons that have not been converted by the discharge plasma conversion device 31 is faster than when relying solely on the temperature rise due to heating or the heat of the exhaust gas. As a result, it is possible to convert hydrocarbons at an early stage by using only the catalytic purifier 4 and to obtain an energy saving effect associated with the power supply to the discharge plasma converter 31 being cut off at an early stage. You can also.

  The exhaust gas temperature when the exhaust gas from the engine body 1 passes through the discharge manifold 2 and the discharge plasma conversion device 31 and the catalytic purification device 4 is low when the engine body 1 is started, but is high speed. The higher the temperature, the higher the temperature. When the temperature of the exhaust gas is increased, the purification rate in the catalytic purification device 4 is improved, and when it reaches a predetermined temperature, for example, 300 ° C. or more, the hydrocarbon can be rendered harmless only by the catalytic purification device 4. Therefore, a temperature sensor for detecting the temperature of the exhaust gas at or near the catalytic purification device is provided, and when the detected temperature reaches a predetermined temperature, the plasma generation control device 32 as a conversion control device from the viewpoint of energy saving. The power supply to the discharge plasma conversion device 31 may be stopped by the control according to. Alternatively, it is estimated that the temperature of the exhaust gas in the catalytic purification device has reached a predetermined temperature when a predetermined time has elapsed from the start of the engine, and power is supplied to the discharge plasma conversion device 31 by the control of the plasma generation control device 32 May be stopped. In this way, the efficiency in the exhaust gas treatment device of the present embodiment can be further increased.

  As described above, in the exhaust gas treatment device or the exhaust gas treatment method of the present embodiment using the discharge plasma conversion device 31 and the catalytic purification device 4, the exhaust gas is exhausted to the discharge plasma conversion device 31 controlled by the plasma generation control device 32. By flowing the gas, hydrocarbons are converted into carbon monoxide, and the carbon monoxide is rendered harmless to carbon dioxide by passing through the catalytic purification device 4 located downstream of the discharge plasma conversion device 31. That is, in the exhaust gas treatment device or the exhaust gas treatment method of the present embodiment, at least a part of hydrocarbons in the exhaust gas is mainly converted to carbon monoxide by the discharge plasma conversion device 31 controlled by the plasma generation control device 32. The exhaust gas that has been converted and processed by the discharge plasma conversion device 31 is cleaned by the catalytic purification device 4. The energy required when the discharge plasma conversion device 31 converts the exhaust gas containing hydrocarbons or the like into carbon monoxide is the discharge plasma conversion device when the exhaust gas containing hydrocarbons or the like is directly cleaned into carbon dioxide or the like. Much less than the energy required by 31. Moreover, since the subsequent catalytic cleaning device 4 operates using the heat of the exhaust gas, carbon monoxide can be cleaned without energy consumption.

  Note that the type of the engine body 1 in which the exhaust gas processing apparatus or the exhaust gas processing method of the present embodiment is used is not limited to a conventional gasoline engine, and the present embodiment is applied to a diesel engine or a lean burn engine for gasoline. It is also possible to use the exhaust gas processing apparatus or the exhaust gas processing method. In the case of conventional gasoline engines, the concentration of oxygen contained in the exhaust gas is extremely low, whereas in the case of diesel engines and gasoline lean burn engines, in addition to hydrocarbons and carbon monoxide, several percent to 10% Some degree of oxygen is contained in the exhaust gas. When the oxygen concentration in the exhaust gas is high in this way, the conversion (oxidation reaction) in the discharge plasma conversion device 31 tends to proceed, so that the efficiency of the discharge plasma conversion device 31 increases. When exhaust gas from a conventional gasoline engine is to be treated, air is mixed on the upstream side (previous stage) of the discharge plasma conversion device 31, and conversion (oxidation reaction) in the discharge plasma conversion device 31 is performed. It may be promoted. As a result, the efficiency in the exhaust gas treatment apparatus of the present embodiment can be further increased.

  As described above, according to the exhaust gas treatment device or the exhaust gas treatment method of the present embodiment, the discharge plasma conversion device 31 as the hydrocarbon conversion device converts the hydrocarbons mainly into carbon monoxide. Since it is controlled by the plasma generation control device 32 as a control device, it can be operated with much less energy than when hydrocarbons are converted to carbon dioxide. Since the subsequent catalytic cleaning device 4 operates using the heat of the exhaust gas, carbon monoxide can be cleaned without energy consumption for the operation. Therefore, the exhaust gas treatment device of the present embodiment contains hydrocarbons with much less energy consumption than when exhaust gas containing hydrocarbons or the like is directly purified to carbon dioxide or the like by a hydrocarbon conversion device. The exhaust gas can be purified, and an effect of high efficiency can be obtained.

  Further, according to the exhaust gas treatment device or the exhaust gas treatment method of the present embodiment, since the discharge plasma conversion device 31 as the hydrocarbon conversion device is used as the preceding stage of the catalytic purification device 4, the catalytic purification device 4. As in the case of using an apparatus equipped with an adsorbent as the preceding stage, the hydrocarbons adsorbed on the adsorbent may be detached before the discharge plasma conversion device 31 reaches a temperature at which the hydrocarbon can be directly detoxified. Therefore, the exhaust gas can be treated with high reliability. Furthermore, since the exhaust gas treatment device or the exhaust gas treatment method of the present embodiment uses the discharge plasma conversion device 31 as the previous stage of the catalytic purification device 4, an adsorbent is provided as the previous stage of the catalytic purification device 4. As in the case of using the apparatus, the adsorbent is not deteriorated by heat and cannot perform a sufficient operation, and also in this respect, it is possible to treat high exhaust gas with high reliability.

  Furthermore, according to the exhaust gas treatment device of the present embodiment, the discharge plasma conversion device 31 is used as a front stage of the catalytic purification device 4, and the performance of the discharge plasma conversion device 31 deteriorates even when exposed to high temperatures. When the exhaust gas becomes hot, as in the case of an exhaust gas treatment device using an apparatus equipped with an adsorbent that may be deteriorated by high temperature as the previous stage of the catalytic purification device 4 No configuration is required to bypass. Therefore, the exhaust gas treatment device of the present embodiment is advantageous in that it becomes an exhaust gas treatment device having a simple configuration as compared with the case where a device equipped with an adsorbent is used as a preceding stage of the catalytic purification device.

Embodiment 2. FIG.
FIG. 6 is a partial cross-sectional view schematically showing a configuration of a main part of an engine apparatus provided with the exhaust gas processing apparatus of the second embodiment, and shows a cylinder part inside the engine body 1 and its vicinity. In the first embodiment described above, the discharge plasma conversion device 31 is connected to the downstream (rear stage) side of the exhaust manifold 2, but in this embodiment, the discharge plasma conversion device 31 is directly connected to the upstream (front stage) side of the exhaust manifold 2, that is, directly to the engine body 1. A discharge plasma conversion device 31 is connected to the above. Note that the exhaust gas treatment device in the present embodiment includes a discharge plasma conversion device 31 as a hydrocarbon conversion device. Since other configurations are the same as those of the first embodiment, differences from the first embodiment will be mainly described below.

  As shown in FIG. 6, the engine body 1 includes a piston 130, an intake valve 131, an exhaust valve 132, an intake pipe 133, and an exhaust pipe 134. Here, the description of the operation of the engine body 1 is omitted, and the arrangement of the exhaust gas exhaust path (exhaust gas flow path) and the discharge plasma conversion device 31 will be described. When the engine body 1 operates, the high-temperature exhaust gas is exhausted to the outside of the engine body 1 through the exhaust pipe 134. A discharge plasma conversion device 31 is connected to the outlet of the engine body 1, and an exhaust manifold 200 is connected to the subsequent stage. Although not all of the exhaust manifold 200 is shown in the figure, the exhaust manifold 200 supplies exhaust gas from a plurality of exhaust gas conversion devices 31 provided so as to correspond to a plurality of cylinders to one exhaust pipe. It is the composition put together. An exhaust pipe 7 is connected to the rear stage of the exhaust manifold 200, and the downstream side of the exhaust pipe 7 has the same configuration as that shown in FIG. Although not shown, the discharge plasma conversion device 31 is connected to the plasma generation control device 32 as in the first embodiment.

  Next, the operation will be described. Exhaust gas that has passed through the exhaust pipe 134 in the engine body 1 is introduced into the discharge plasma conversion device 31. At this time, since the exhaust gas in a high temperature state just exhausted from the engine body 1 is introduced into the discharge plasma conversion device 31, the discharge plasma treatment can be performed in a state where the exhaust gas is at a high temperature. By this conversion treatment, at least some of the hydrocarbons in the exhaust gas are mainly converted into carbon monoxide. In this conversion process, as in the first embodiment, the plasma generation control device 32 controls the hydrocarbons mainly by controlling the energy consumption per unit volume of the exhaust gas in the discharge plasma conversion device 31, for example. To carbon monoxide. The exhaust gas that has passed through the discharge plasma conversion device 31 is collected from a plurality of cylinders by the exhaust manifold 200 and introduced into the catalytic purification device 4 via the exhaust pipe 7.

  FIG. 7 is a graph showing experimental results of component concentrations in the exhaust gas after passing the exhaust gas through the discharge plasma conversion device 31 while keeping the power consumption constant at various temperatures of the discharge plasma conversion device 31. As shown in this graph, the conversion from hydrocarbon to carbon monoxide increases as the temperature of the discharge plasma conversion device 31 increases.

  When the engine body 1 is started or when the automobile is running at a low speed, the combustion temperature inside the engine body 1 may be low. Even in such a case, the exhaust gas treatment device or the exhaust gas treatment method of the present embodiment is provided with the exhaust gas conversion device 31 between the engine body 1 and the exhaust manifold 200 so that the hydrocarbon conversion device 31 The exhaust gas can be introduced into the discharge plasma conversion device 31 before being cooled outside the engine body 1 by being arranged at a position that will be close to the engine body 1. As a result, the exhaust gas treatment device or the exhaust gas treatment method of the present embodiment can treat high-temperature exhaust gas in the discharge plasma conversion device 31, and a hydrocarbon conversion device such as a discharge can be provided at a position away from the engine body 1. Compared to the case where the plasma conversion device 31 is provided, the exhaust gas conversion in the exhaust gas conversion device 31 is promoted as shown in FIG.

  As described above, according to the exhaust gas processing device or the exhaust gas processing method of the present embodiment, even if the combustion temperature inside the engine body 1 is low, the exhaust gas is converted into the exhaust gas conversion device 31 before being cooled. It becomes possible to treat the exhaust gas at a high temperature in the discharge plasma conversion device 31. As a result, the exhaust gas conversion in the exhaust gas conversion device 31 is promoted and energy efficiency can be further improved as compared with the case where a hydrocarbon conversion device such as a discharge plasma conversion device 31 is provided at a position away from the engine body 1. The effect that it is possible can be obtained.

Embodiment 3 FIG.
FIG. 8 is a schematic diagram showing a basic configuration of an engine apparatus including the exhaust gas processing apparatus according to the third embodiment. The exhaust gas treatment device of the present embodiment includes a packed bed type discharge plasma conversion device 37 as a hydrocarbon conversion device that converts at least a part of hydrocarbons in the exhaust gas mainly into carbon monoxide. Since other configurations are the same as those of the first embodiment, differences from the first embodiment will be mainly described below.

  The packed bed type discharge plasma conversion device 37 is a device for generating silent discharge, and FIG. 9 shows a specific configuration example thereof. The packed bed type discharge plasma conversion device 37 has a configuration in which the discharge space of the discharge plasma conversion device shown in FIG. 3 is filled with barium titanate beads 70. The barium titanate beads 70 are in the form of a ceramic in which barium titanate is hardened in a spherical shape. The packed bed type discharge plasma conversion device 37 is not limited to the configuration shown in FIG. 9, and is a known various packed bed type discharge plasma conversion device using barium titanate. May be.

  The packed bed type discharge plasma conversion device 37 also includes a temperature sensor 71 for measuring the temperature inside the discharge space, that is, the temperature of the exhaust gas inside. As shown in FIG. 8, the temperature sensor 71 is connected to the temperature controller 72, and the temperature controller 72 is connected to the plasma generation control device 32. The temperature controller 72 increases the output voltage of a high voltage power source (not shown) via the plasma generation control device 32 when the temperature of the exhaust gas inside the packed bed type discharge plasma conversion device 37 is lower than the set temperature. In addition, it has a function of increasing the temperature of the exhaust gas by increasing the power consumed in the packed bed type discharge plasma conversion device 37. The temperature controller 72 also has a function of decreasing the temperature of the exhaust gas by decreasing the output voltage of the high-voltage power supply via the plasma generation control device 32 when the temperature of the exhaust gas becomes higher than the set upper limit temperature. . The voltage applied to the packed bed type discharge plasma conversion device 37 may be either an alternating high voltage or a pulsed high voltage.

  Further, the control by the plasma generation control device 32 includes control for mainly converting hydrocarbons in the exhaust gas into carbon monoxide. This control is performed, for example, by controlling the energy consumption per unit volume of the exhaust gas in the packed bed type discharge plasma conversion device 37.

  The exhaust gas in which at least a part of the hydrocarbons is mainly converted into carbon monoxide in the packed bed type discharge plasma conversion device 37 passes through the exhaust pipe 7 and is introduced into the catalytic purification device 4. The catalytic purification device 4 and the downstream configuration are the same as those in the first embodiment.

  Next, the temperature adjustment of the exhaust gas inside the packed bed type discharge plasma conversion device 37 will be described in more detail. When the exhaust gas temperature in the packed bed type discharge plasma conversion device 37 detected by the temperature sensor 71 is low, the temperature regulator 72 outputs the output voltage of a high voltage power source (not shown) via the plasma generation control device 32. Increase.

  When a high voltage is applied to the high voltage electrode 22 and the ground electrode 24 inside the packed bed type discharge plasma apparatus 37, a silent discharge occurs at a place where the barium titanate beads 70 are in contact with each other. At this time, since the barium titanate bead 70 itself is a material having a large dielectric loss, the barium titanate bead 70 itself becomes a heating element with the occurrence of discharge. The heat generated by this dielectric loss heats the exhaust gas. Therefore, the exhaust gas treatment apparatus of the present embodiment heats the exhaust gas to a higher temperature by increasing the voltage applied to the packed bed type discharge plasma conversion device 37 to increase the heat generation due to dielectric loss. Can do.

  Depending on the operation of the engine body 1, the temperature of the exhaust gas exhausted from the engine body 1 may be low and may be immediately cooled by the exhaust manifold 2 to become a low temperature. For example, exhaust gas tends to be immediately cooled when the engine body is started or when a vehicle is running at a low speed. In this way, when the temperature of the exhaust gas is low, the exhaust gas treatment device of the present embodiment increases the voltage applied to the packed bed type discharge plasma conversion device 37 to increase the heat generation due to dielectric loss. Exhaust gas can be heated. In this way, by increasing the exhaust gas temperature, it is possible to sufficiently convert hydrocarbons into carbon monoxide in the packed bed type discharge plasma apparatus 37. As described above, the exhaust gas treatment apparatus of the present embodiment can perform discharge treatment and heat treatment at the same time by the packed bed type discharge plasma conversion device 37, so that it is simple without using components such as an electric heater (heater). The exhaust gas in the packed bed type discharge plasma conversion device 37 can be heated by such a device.

  As described above, the exhaust gas processing apparatus or the exhaust gas processing method of the present embodiment can reliably adjust the temperature of the exhaust gas by using the temperature sensor 71 and the temperature controller 72. However, even if the temperature sensor 71 and the temperature controller 72 are not used, an appropriate high voltage is applied to the high voltage electrode 22 and the ground electrode 24, and silent discharge occurs at a place where the barium titanate beads 70 are in contact with each other. If the exhaust gas can be heated to an appropriate temperature by generating heat, the temperature sensor 71 and the temperature controller 72 are not necessarily required.

  As described above, according to the exhaust gas treatment device or the exhaust gas treatment method of the present embodiment, the voltage applied to the packed bed type discharge plasma conversion device 37 is increased to increase the heat generated due to the dielectric loss. By heating the gas, the hydrocarbon can be sufficiently converted into carbon monoxide in the packed bed type discharge plasma apparatus 37. As described above, according to the exhaust gas treatment apparatus or the exhaust gas treatment method of the present embodiment, the discharge treatment and the heat treatment can be performed simultaneously by the packed bed type discharge plasma conversion device 37 provided as the hydrocarbon conversion device. The exhaust gas in the packed bed type discharge plasma conversion device 37 can be heated with a simple device without using the above components. This also increases the temperature of the exhaust gas in the packed bed type discharge plasma conversion device 37 and promotes the conversion of the exhaust gas, so that the energy efficiency can be further improved.

Embodiment 4 FIG.
FIG. 10 is a schematic diagram showing a specific configuration of an engine apparatus including the exhaust gas processing apparatus according to the fourth embodiment. In the first embodiment, the configuration including the discharge plasma conversion device 31 is used as the hydrocarbon conversion device 3 that mainly converts at least a part of harmful components in the exhaust gas into carbon monoxide. In the exhaust gas treatment apparatus in the apparatus, instead of the discharge plasma conversion apparatus 31, an ozone supply line as an ozone reaction apparatus having a configuration in which an air inlet 80, an air pump 81, an ozone generator 82, and an ozone injection nozzle 84 are connected in order. (Corresponding to a device having means for injecting ozone into exhaust gas). In addition, the ozone supply line as an ozone reaction apparatus in this Embodiment is corresponded to the hydrocarbon conversion apparatus mentioned above. Since other configurations are the same as those of the first embodiment, differences from the first embodiment will be mainly described below.

  As shown in FIG. 10, the engine device including the exhaust gas processing device of the present embodiment includes an exhaust manifold 2 and catalytic purification that are sequentially arranged in the exhaust gas exhaust path from the engine body 1 to the exhaust gas outlet 6. A device 4 and a silencer 5 are provided. Note that these portions from the exhaust manifold 2 to the exhaust gas outlet 6 are connected by an exhaust pipe 7. Exhaust gases exhausted from the engine body 1 are combined into one by the exhaust manifold 2. The exhaust gas collected by the exhaust manifold 2 passes through the exhaust pipe 7 and is introduced into the catalytic purification device 4.

  Moreover, the exhaust gas treatment apparatus of the present embodiment includes an ozone supply line including a configuration in which an air inlet 80, an air pump 81, an ozone generator 82, and an ozone injection nozzle 84 are connected in order. The ozone injection nozzle 84 is installed so as to open inside the exhaust pipe 7 located on the upstream side of the catalytic purification device 4. The ozone generator 82 is connected to an ozone generation power source 83. As the ozone generator 82 and the ozone generating power supply 83, various known devices and methods can be used. For example, a silent discharge type ozonizer may be used as the ozone generator 82, and a high voltage power source may be used as the ozone generation power source 83. An electrolytic ozone generator may be used as the ozone generator 82, and the ozone generation power source 83 may be used. A combination using a DC power source may be used.

  Furthermore, as shown in FIG. 10, the exhaust gas treatment device of the present embodiment includes an ozone generation control device 85 as a conversion control device. The ozone generation control device 85 controls at least one of the ozone generator 82 and the ozone generation power supply 83 to control the amount of ozone generated, thereby controlling the exhaust pipe 7 located upstream of the catalytic purification device 4. Inside, at least some of the hydrocarbons in the exhaust gas are mainly converted to carbon monoxide.

Next, the operation of the exhaust gas processing apparatus configured as described above will be described. Exhaust gas exhausted from the engine body 1 passes through the exhaust manifold 2 and flows through the exhaust pipe 7. On the other hand, in the ozone supply line, air taken from the air inlet 80 is introduced into the ozone generator 82 by the air pump 81. The ozone generator 82 generates ozonized air containing ozone (O ₃ ) generated therein. This ozonized air is injected into the exhaust pipe 7 located upstream of the catalytic purification device 4 via an ozone injection nozzle 84. When ozonized air is mixed with exhaust gas inside the exhaust pipe 7, a part of ozone is dissociated and (O *) is generated. (O * represents an O radical. The same shall apply hereinafter.)
O ₃ → O * + O ₂
This O * reacts with hydrocarbons in the exhaust gas to convert at least a part of the hydrocarbons mainly into carbon monoxide.

  In the above description, the case where the ozone supply line is used in place of the discharge plasma conversion device 31 in the exhaust gas treatment device shown in FIG. 2 of the first embodiment has been described. However, the exhaust gas processing apparatus or the exhaust gas processing method of the present embodiment is not limited to this. For example, in the exhaust gas processing apparatus described in the second embodiment, the present embodiment is replaced with the discharge plasma conversion apparatus 31. It is good also as what uses the ozone supply line of a form. Also in an engine apparatus using such an exhaust gas processing apparatus or an exhaust gas processing method, the same operational effects as in the case of the second embodiment can be obtained.

  As described above, according to the exhaust gas processing device or the exhaust gas processing method of the present embodiment, the ozone injection installed so as to open inside the exhaust pipe 7 located on the upstream side of the catalytic purification device 4. By injecting and mixing ozonized air into exhaust gas containing hydrocarbons through an ozone supply line equipped with a nozzle 84, the hydrocarbons contained in the exhaust gas may have a conversion effect equivalent to that of the above-described discharge plasma treatment. it can. The exhaust gas in which at least a part of the hydrocarbons is converted into carbon monoxide in this way can be efficiently cleaned by the subsequent catalytic purification device 4. Therefore, the exhaust gas processing apparatus or the exhaust gas processing method of the present embodiment can achieve the same effect as the exhaust gas processing apparatus or the exhaust gas processing method of the first embodiment without using a discharge plasma conversion apparatus.

Embodiment 5 FIG.
FIG. 11 is a schematic diagram illustrating a specific configuration of an engine apparatus including the exhaust gas processing apparatus according to the fifth embodiment. In the first embodiment, the discharge plasma conversion device 31 is used as the hydrocarbon conversion device 3 that converts at least a part of the hydrocarbons in the exhaust gas mainly into carbon monoxide. However, in the engine device of the present embodiment, In the exhaust gas treatment device, a configuration in which an ultraviolet lamp 90 (ultraviolet irradiation means for irradiating the exhaust gas with ultraviolet rays) is installed inside the exhaust pipe 7 is used as the hydrocarbon conversion device 3. The ultraviolet lamp 90 installed in the exhaust pipe 7, that is, the ozone reactor, converts at least a part of hydrocarbons in the exhaust gas mainly into carbon monoxide. Since other configurations are the same as those of the first embodiment, differences from the first embodiment will be mainly described below.

  As shown in FIG. 11, the engine device provided with the exhaust gas processing device of the present embodiment has an exhaust manifold 2 and an ultraviolet lamp 90 arranged in order in the exhaust gas exhaust path from the engine body 1 to the exhaust gas outlet 6. The catalytic purification device 4 and the silencer 5 are provided. These parts from the exhaust manifold 2 to the exhaust gas outlet 6 are connected by an exhaust pipe 7. Exhaust gases exhausted from the engine body 1 are combined into one by the exhaust manifold 2. The exhaust gas collected by the exhaust manifold 2 flows through the portion of the exhaust pipe 7 where the ultraviolet lamp 90 is installed, thereby irradiating the ultraviolet lamp 90 with ultraviolet rays in the exhaust pipe 7 upstream of the catalytic purification device 4. receive. The exhaust gas that has passed through the portion of the exhaust pipe 7 where the ultraviolet lamp 90 is installed is introduced into the catalytic purification device 4.

  As the ultraviolet irradiation means for irradiating the exhaust gas with ultraviolet rays, any known ultraviolet lamp may be used. For example, an ultraviolet lamp for generating ozone, which generates ultraviolet light having a low wavelength of, for example, around 185 nm, can be preferably used as an ultraviolet irradiation means for exhaust gas.

  Furthermore, the engine apparatus of the present embodiment includes an ozone generation control device 92 as a conversion control device, as shown in FIG. The ozone generation control device 92 controls the amount of ozone generated by controlling the light quantity of the ultraviolet lamp 90, thereby removing at least a part of the hydrocarbons in the exhaust gas in the exhaust pipe 7 on the upstream side of the catalytic purification device 4. Is converted mainly to carbon monoxide.

Next, the operation of the exhaust gas processing apparatus configured as described above will be described. Exhaust gas exhausted from the engine body 1 passes through the exhaust manifold 2 and flows through the exhaust pipe 7. When the exhaust gas passes in the vicinity of the ultraviolet lamp 90, the light having a low wavelength from the ultraviolet lamp 90 dissociates a part of oxygen contained in the exhaust gas and generates O *.
O ₂ + UV → 2O *
Since this O * has a short lifetime, a part of it reacts with hydrocarbons in the vicinity of the ultraviolet lamp to convert at least a part thereof to carbon monoxide. A part of O * is combined with oxygen molecules to become ozone (O ₃ ).
O * + O ₂ → O ₃
Since ozone (O ₃ ) has a longer life than O *, it diffuses into the exhaust pipe 7 and mixes with exhaust gas. Part of the ozone mixed with the exhaust gas is dissociated again by the heat of the exhaust gas to generate O *.
O ₃ → O * + O ₂
This O * reacts with the hydrocarbons in the exhaust gas and at least partially converts it mainly into carbon monoxide.

  In the above description, a case where an ultraviolet irradiation means for irradiating the exhaust gas with ultraviolet rays is used instead of the discharge plasma conversion device 31 in the exhaust gas treatment apparatus or the exhaust gas treatment method shown in FIG. did. However, the exhaust gas treatment device or the exhaust gas treatment method of the present embodiment is not limited to this, and the discharge plasma conversion device 31 is replaced with the exhaust gas treatment device or the exhaust gas treatment method described in the second embodiment. Further, it is possible to use an ultraviolet irradiation means for irradiating the exhaust gas of the present embodiment with ultraviolet rays. Also in such an exhaust gas processing apparatus or an exhaust gas processing method, the same effect as the case of Embodiment 2 can be obtained.

  As described above, according to the exhaust gas processing apparatus or the exhaust gas processing method of the present embodiment, O * is generated by irradiating the exhaust gas with ultraviolet rays by the ultraviolet lamp 90 in the exhaust pipe 7 to generate exhaust gas. The conversion action equivalent to the above-mentioned discharge plasma treatment can be exerted on the contained hydrocarbon. The exhaust gas in which at least a part of the hydrocarbons is converted into carbon monoxide in this way can be efficiently cleaned by the subsequent catalytic purification device 4. Therefore, according to the exhaust gas processing apparatus or the exhaust gas processing method of the present embodiment, the same effects as the exhaust gas processing apparatus or the exhaust gas processing method of the first embodiment can be obtained without using the discharge plasma conversion device 31. Can play. Furthermore, according to the exhaust gas processing apparatus or the exhaust gas processing method of the present embodiment, the ozone reaction apparatus can be configured simply by installing the ultraviolet lamp 90 inside the exhaust pipe 7, so that the number of components is small and the exhaust gas The effect that the processing apparatus can be simplified is also obtained.

Embodiment 6 FIG.
FIG. 12 is a schematic diagram showing a basic configuration of an engine apparatus including an exhaust gas treatment apparatus in the sixth embodiment. In the first embodiment, a configuration including the discharge plasma conversion device 31 is used as the hydrocarbon conversion device 3 that mainly converts at least a part of hydrocarbons in the exhaust gas into carbon monoxide. In the exhaust gas treatment apparatus in the apparatus, an ultraviolet lamp 90 (ultraviolet irradiation means for irradiating the exhaust gas with ultraviolet rays) installed inside the exhaust pipe 7 and a photocatalyst 91 installed on the inner wall of the exhaust pipe 7 are converted into a hydrocarbon converter. It is used as. Note that the ozone reaction device in the present embodiment is configured to include an ultraviolet lamp 90 and a photocatalyst 91 installed in the exhaust pipe 7. Further, the exhaust gas treatment device of the present embodiment also includes an ozone generation control device 92 as shown in FIG. Since other configurations are the same as those of the first embodiment, differences from the first embodiment will be mainly described below.

  As shown in FIG. 12, the engine apparatus of the present embodiment includes an exhaust manifold 2, an ultraviolet lamp 90 and a photocatalyst 91, a catalytic type, which are sequentially arranged in the exhaust gas exhaust path from the engine body 1 to the exhaust gas outlet 6. A purifier 4 and a silencer 5 are provided. These parts from the exhaust manifold 2 to the exhaust gas outlet 6 are connected by an exhaust pipe 7. Exhaust gases exhausted from the engine body 1 are combined into one by the exhaust manifold 2. The exhaust gas collected by the exhaust manifold 2 flows through the exhaust pipe 7 where the ultraviolet lamp 90 and the photocatalyst 91 are installed, so that it receives ultraviolet rays from the ultraviolet lamp 90 and at the same time a part of the exhaust gas Contact the photocatalyst 91. Then, the exhaust gas that has passed through the exhaust pipe 7 where the ultraviolet lamp 90 and the photocatalyst 91 are installed is introduced into the catalytic purification device 4.

As an ultraviolet irradiation means for irradiating the exhaust gas with ultraviolet rays, any known ultraviolet lamp may be used as in the case of the fifth embodiment. For example, an ultraviolet lamp for generating ozone, which generates ultraviolet light having a wavelength of 400 nm or less effective for activating the reaction via the photocatalyst, is preferably used as an ultraviolet irradiation means for irradiating the exhaust gas with ultraviolet light. it can. As the photocatalyst 91, for example, a known TiO ₂ catalyst can be used.

  Furthermore, as shown in FIG. 12, the engine apparatus of the present embodiment includes an ozone generation control device 92 as a conversion control device. The ozone generation control device 92 controls the light quantity of the ultraviolet lamp 90 to control at least a portion of hydrocarbons in the exhaust gas by controlling the amount of ozone generated in the vicinity of where the ultraviolet lamp 90 and the photocatalyst 91 are installed. In the exhaust pipe 7, it is mainly converted into carbon monoxide.

  Next, the operation of the exhaust gas processing apparatus configured as described above will be described. Exhaust gas exhausted from the engine body 1 passes through the exhaust manifold 2 and flows through the exhaust pipe 7. And when this exhaust gas passes the vicinity of the ultraviolet lamp 90, exhaust gas treatment by irradiating the light of the ultraviolet lamp 90 to the exhaust gas, and the exhaust gas to the photocatalyst 91 irradiated with the light of the ultraviolet lamp 90 The two processes of the exhaust gas process due to contact with each other are performed. The exhaust gas treatment by the irradiation of the ultraviolet lamp 90 is the same as that of the fifth embodiment, and thus the description thereof will be omitted. In the following, the exhaust gas caused by contact of the exhaust gas with the photocatalyst 91 irradiated with the light of the ultraviolet lamp 90 The gas treatment will be described.

  When the light of the ultraviolet lamp 90 is irradiated onto the photocatalyst 91, water in the exhaust gas is dissociated on the surface of the photocatalyst 91 to generate OH * (OH * represents OH radical; the same applies hereinafter). This OH * reacts with the hydrocarbons in the exhaust gas to at least partially convert it mainly into carbon monoxide.

  The exhaust gas in which at least a part of the hydrocarbons is mainly converted into carbon monoxide in this way is efficiently cleaned by the subsequent catalytic purification device 4.

  In the above, in the exhaust gas processing apparatus or the exhaust gas processing method shown in FIG. 2 of the first embodiment, the ultraviolet lamp 90 and the photocatalyst 91 installed in the exhaust pipe 7 instead of the discharge plasma conversion apparatus 31 The case where is used has been described. However, the exhaust gas processing apparatus or the exhaust gas processing method of the present embodiment is not limited to this, and instead of the discharge plasma conversion apparatus 31 in the exhaust gas processing apparatus or the exhaust gas processing method described in the second embodiment. The exhaust gas processing apparatus or the exhaust gas processing method using the ultraviolet lamp 90 and the photocatalyst 91 installed inside the exhaust pipe 7 in the present embodiment may be used. Also in such an exhaust gas processing apparatus or an exhaust gas processing method, the same effect as the case of Embodiment 2 can be obtained.

  As described above, according to the exhaust gas treatment apparatus or the exhaust gas treatment method of the present embodiment, by performing the treatment by the ultraviolet irradiation from the ultraviolet lamp 90 and the treatment by the photocatalyst 90 on the exhaust gas, The effect is obtained that the hydrocarbon in the exhaust gas can be converted to carbon monoxide more efficiently than in the case of Embodiment 5 in which the hydrocarbon in the exhaust gas is converted into carbon monoxide only by ultraviolet irradiation.

  The exhaust gas treatment apparatus or the exhaust gas treatment method according to the present invention can be used for the purification treatment of exhaust gas from an automobile engine as described in the above embodiments. For example, the present invention can also be used for cleaning exhaust gas exhausted from an internal combustion engine such as a ship or a diesel generator, or exhaust gas exhausted from thermal power generation. Furthermore, it can also be used for the purification treatment of exhaust gas exhausted from a combustion apparatus such as an incinerator.

1 is a schematic diagram showing a basic configuration of an engine device that includes an exhaust gas treatment device according to Embodiment 1. FIG. It is a schematic diagram which shows the specific structure of an engine apparatus provided with the exhaust-gas processing apparatus shown in FIG. FIG. 3 is a perspective view showing a specific configuration of the discharge plasma conversion apparatus shown in FIG. It is a graph which shows the process result by the discharge plasma converter shown in FIG. 3 as a density | concentration of each component of the exhaust gas with respect to energy consumption. It is a graph which shows the temperature characteristic of the purification rate of propane and carbon monoxide in the catalytic purification apparatus shown in FIG. 1 and FIG. FIG. 6 is a partial cross-sectional view schematically showing a configuration of a main part of an engine device provided with an exhaust gas treatment device of a second embodiment. It is a graph which shows the experimental result regarding the temperature characteristic of a discharge plasma conversion apparatus. FIG. 6 is a schematic diagram showing a specific configuration of an engine device including an exhaust gas treatment device in a third embodiment. FIG. 9 is a perspective view showing a specific configuration of the packed bed type discharge plasma conversion apparatus shown in FIG. FIG. 10 is a schematic diagram showing a basic configuration of an engine device provided with an exhaust gas treatment device in a fourth embodiment. FIG. 10 is a schematic diagram showing a basic configuration of an engine device including an exhaust gas treatment device in a fifth embodiment. FIG. 10 is a schematic diagram showing a basic configuration of an engine apparatus provided with an exhaust gas treatment apparatus in a sixth embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Engine body, 2 Exhaust manifold, 3 Hydrocarbon conversion device, 4 Catalytic purification device, 5 Silencer, 6 Exhaust gas outlet, 7 Exhaust pipe, 22 High voltage electrode, 22a High voltage electrode terminal, 22b Feeding terminal, 23 mesh , 24 ground electrode, 28 flange, 31 discharge plasma conversion device, 32 plasma generation control device, 37 packed bed type discharge plasma conversion device, 70 barium titanate beads, 71 temperature sensor, 72 temperature regulator, 80 air inlet, 81 air Pump, 82 Ozone generator, 83 Ozone generation power supply, 84 Ozone injection nozzle, 85 Ozone generation control device, 90 UV lamp, 91 Photocatalyst, 92 Ozone generation control device, 130 Piston, 131 Intake valve, 132 Exhaust valve, 133 Intake Pipe, 134 exhaust pipe, 200 exhaust manifold De.

Claims (10)

A hydrocarbon converter that converts at least a portion of the hydrocarbons in the exhaust gas to carbon monoxide;
A catalytic purification device for purifying the exhaust gas treated by the hydrocarbon conversion device using a catalyst;
An exhaust gas processing apparatus comprising: a conversion control device that controls the hydrocarbon conversion device so as to convert at least part of hydrocarbons in the exhaust gas mainly into carbon monoxide.   The conversion control device supplies power to the hydrocarbon conversion device when the temperature of the exhaust gas at or near the catalytic purification device becomes a predetermined temperature or when it is estimated to be the predetermined temperature. The exhaust gas processing device according to claim 1, wherein control for further stopping is further performed.   The exhaust gas treatment device according to claim 1 or 2, wherein the hydrocarbon conversion device is a discharge plasma conversion device that converts a hydrocarbon into carbon monoxide using discharge plasma.   The exhaust gas treatment apparatus according to claim 3, wherein the discharge plasma conversion apparatus is a packed bed type discharge plasma conversion apparatus formed by filling a discharge space with a large number of beads having a predetermined shape.   The exhaust gas treatment device according to claim 1 or 2, wherein the hydrocarbon conversion device is an ozone reaction device that reacts exhaust gas with ozone to convert hydrocarbons to carbon monoxide.   The exhaust gas treatment device according to claim 5, wherein the ozone reaction device has means for injecting ozone into the exhaust gas.   6. The exhaust gas treatment apparatus according to claim 5, wherein the ozone reaction device has ultraviolet irradiation means for generating ozone by irradiating the exhaust gas with ultraviolet rays.   6. The exhaust gas treatment apparatus according to claim 5, wherein the ozone reaction device has ultraviolet irradiation means for generating ozone by irradiating the exhaust gas with ultraviolet rays and a photocatalyst.   The exhaust gas treatment device according to any one of claims 1 to 8, wherein the hydrocarbon conversion device is disposed at a position close to the engine body. A hydrocarbon conversion stage that converts at least a portion of the hydrocarbons in the exhaust gas primarily to carbon monoxide;
An exhaust gas treatment method comprising: a catalytic reaction stage in which the exhaust gas treated in the hydrocarbon conversion stage is cleaned using a catalyst.

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