Oxidation catalyst system

Abstract

To suppress heat loss of equipment provided on the down stream side from the oxidation catalyst.SOLUTION: An oxidation catalyst system includes an oxidation catalyst which is provided on an exhaust gas line from an internal combustion engine and oxidizes exhaust gas, a heat exchanger which is constituted so as to perform heat exchange between purified gas as the exhaust gas having temperature elevated by oxidation reaction by means of the oxidation catalyst and the exhaust gas flowing on the upstream side from the oxidation catalyst of the exhaust gas line, a purified gas introduction line for extracting the purified gas from the downstream side of the oxidation catalyst of the exhaust gas line and guiding the gas to the heat exchanger, a purified gas returning line for returning the purified gas to the downstream side of a first connection part as a connection part with the purified gas introduction line of the exhaust gas line from the heat exchanger, a purified gas temperature acquiring device constituted so as to acquire a temperature of the purified gas flowing through the downstream side of the oxidation catalyst of the exhaust gas line, and a purified gas flow rate adjusting device which is constituted so as to adjust a flow rate of the purified gas guided to the hat exchanger in accordance with the temperature of the purified gas obtained by the purified gas temperature acquiring device.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to oxidation catalyst systems. [Background technology]

[0002] An oxidation catalyst system is provided with an oxidation catalyst device that includes an oxidation catalyst for oxidizing exhaust gas discharged from an internal combustion engine. For example, when an internal combustion engine is operated using fuel such as liquefied natural gas that contains unburned methane in its exhaust gas, a methane oxidation catalyst may be provided downstream of the internal combustion engine to remove methane from the exhaust gas. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-227329 A Summary of the Invention [Problem to be solved by the invention]

[0004] In order to improve the efficiency of the methane oxidation catalyst, the methane oxidation catalyst may be preheated. When the methane oxidation catalyst is preheated, there is a risk that the temperature of the exhaust gas that has passed through the methane oxidation catalyst may become too high. If the temperature of the exhaust gas that has passed through the methane oxidation catalyst is too high, there is a risk that thermal damage may occur to equipment provided downstream of the methane oxidation catalyst in the exhaust gas flow direction. In particular, when a methane oxidation catalyst is additionally provided downstream of an existing internal combustion engine, there is a high possibility that the equipment provided downstream of the methane oxidation catalyst in the exhaust gas flow direction may be thermally damaged, since the temperature rise of the exhaust gas caused by the oxidation reaction in the methane oxidation catalyst is not taken into consideration. In order to suppress thermal damage to the equipment, it is necessary to control the temperature of the exhaust gas.

[0005] Patent Document 1 discloses a structure for preheating exhaust gas to be introduced into an oxidation catalyst using heat generated by an oxidation reaction in the oxidation catalyst. However, Patent Document 1 does not disclose any description regarding temperature control of exhaust gas downstream of the oxidation catalyst, so it is unclear whether thermal damage to equipment installed downstream of the oxidation catalyst can be prevented.

[0006] In view of the above circumstances, at least one embodiment of the present disclosure aims to provide an oxidation catalyst system that can suppress thermal damage to equipment provided downstream of the oxidation catalyst in the exhaust gas flow direction. [Means for solving the problem]

[0007] The oxidation catalyst system according to at least one embodiment of the present disclosure comprises: An oxidation catalyst provided in an exhaust gas line through which exhaust gas discharged from an internal combustion engine flows, the oxidation catalyst being configured to oxidize the exhaust gas; a heat exchanger configured to perform heat exchange between a purified gas, which is the exhaust gas heated by an oxidation reaction by the oxidation catalyst, and the exhaust gas flowing upstream of the oxidation catalyst in the exhaust gas line; a purified gas introduction line for extracting the purified gas from a downstream side of the oxidation catalyst of the exhaust gas line and introducing the purified gas into the heat exchanger; a purified gas return line for returning the purified gas from the heat exchanger to a downstream side of a first connection portion which is a connection portion between the exhaust gas line and the purified gas introduction line; a purified gas temperature acquisition device configured to acquire a temperature of the purified gas flowing downstream of the oxidation catalyst in the exhaust gas line; and a purified gas flow rate adjustment device configured to adjust the flow rate of the purified gas guided to the heat exchanger in accordance with the temperature of the purified gas acquired by the purified gas temperature acquisition device. Effect of the Invention

[0008] According to at least one embodiment of the present disclosure, an oxidation catalyst system is provided that can suppress thermal damage to equipment provided downstream of the oxidation catalyst in the exhaust gas flow direction. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of an internal combustion engine system including an oxidation catalyst system according to an embodiment of the present disclosure. [Diagram 2] 1 is a schematic diagram of an internal combustion engine system including an oxidation catalyst system according to an embodiment of the present disclosure. [Diagram 3] 2 is a block diagram showing an example of opening control of a first open / close damper in the oxidation catalyst system shown in FIG. 1. FIG. [Figure 4] 3 is a block diagram showing an example of opening control of a second open / close damper in the oxidation catalyst system shown in FIG. 2. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, some embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as the embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure.

[0011] (Internal Combustion Engine System) 1 and 2 are schematic diagrams of an internal combustion engine system 1 including an oxidation catalyst system 2 according to an embodiment of the present disclosure. As shown in FIGS. 1 and 2, the internal combustion engine system 1 includes the oxidation catalyst system 2, an internal combustion engine 11, and an exhaust gas line 12 through which exhaust gas discharged from the internal combustion engine 11 flows. The internal combustion engine system 1 may further include a generator 15 that is connected to an output shaft of the internal combustion engine 11 and generates electricity using the power generated by the internal combustion engine 11. In other words, the internal combustion engine 11 may be an engine for generating electricity. The exhaust gas line 12 forms a flow path for circulating the exhaust gas, and is formed by, for example, piping.

[0012] In the following description, when simply referring to the upstream side, it refers to the upstream side along the main flow direction of the fluid in the part or region to which the direction is described. Similarly, in the following description, when simply referring to the downstream side, it refers to the downstream side along the main flow direction of the fluid in the part or region to which the direction is described.

[0013] (Oxidation Catalyst System) An oxidation catalyst system 2 according to some embodiments is mounted on an internal combustion engine system 1. As shown in Fig. 1 and Fig. 2, the oxidation catalyst system 2 includes an oxidation catalyst device 3, a catalyst casing 4, a heat exchanger 5, a purified gas inlet line 13, and a purified gas return line 14.

[0014] (Oxidation catalyst device) 1 and 2, the oxidation catalyst device 3 includes an oxidation catalyst 31 that promotes the oxidation of at least one of the components (exhaust gas components) contained in the exhaust gas. In the illustrated embodiment, the internal combustion engine 11 is operated using a fuel such as liquefied natural gas, whose exhaust gas components may include unburned methane. The oxidation catalyst 31 includes a methane oxidation catalyst that promotes the oxidation of methane contained in the exhaust gas. The oxidation catalyst device 3 may include not only the oxidation catalyst 31 but also a catalyst carrier that supports the oxidation catalyst 31.

[0015] (Catalyst casing) 1 and 2, the catalyst casing 4 is provided in the exhaust gas line 12 and accommodates an oxidation catalyst device 3 including an oxidation catalyst 31. In the illustrated embodiment, the catalyst casing 4 includes a casing main body 41 formed in a rectangular tube extending along the vertical direction and having an internal space 40 through which the exhaust gas flows. The exhaust gas flowing inside the catalyst casing 4 (internal space 40) flows from the bottom to the top in the vertical direction.

[0016] The oxidation catalyst device 3 is disposed in the internal space 40 and extends along a direction intersecting the flow direction of the exhaust gas flowing inside the catalyst casing 4 (in the illustrated example, a horizontal direction perpendicular to the flow direction of the exhaust gas flowing inside the catalyst casing 4). The internal space 40 includes two spaces 40A, 40B partitioned by the oxidation catalyst device 3. That is, the internal space 40 includes a first internal space 40A located upstream of the oxidation catalyst device 3 in the exhaust gas flow direction, and a second internal space 40B located downstream of the oxidation catalyst device 3 in the exhaust gas flow direction.

[0017] The casing body 41 has an exhaust gas inlet 42 formed at a lower end in the vertical direction for introducing exhaust gas from the outside of the casing body 41 into the first internal space 40A. The casing body 41 has an exhaust gas outlet 43 formed at an upper end in the vertical direction for discharging exhaust gas from the second internal space 40B to the outside of the casing body 41.

[0018] 1 and 2, the exhaust gas line 12 includes an upstream exhaust gas line 12A for guiding exhaust gas from the internal combustion engine 11 to the catalyst casing 4, and a downstream exhaust gas line 12B for guiding exhaust gas from the catalyst casing 4 to the downstream side in the exhaust gas flow direction. The upstream exhaust gas line 12A has an upstream end connected to the internal combustion engine 11, and a downstream end connected to an exhaust gas inlet 42 of the catalyst casing 4. The downstream exhaust gas line 12B has an upstream end connected to an exhaust gas outlet 43 of the catalyst casing 4.

[0019] The exhaust gas discharged from the internal combustion engine 11 flows through the exhaust gas line 12 and is introduced into the first internal space 40A from the exhaust gas inlet 42. When the exhaust gas introduced into the first internal space 40A passes through the oxidation catalyst device 3, the oxidation of at least one of the exhaust gas components (e.g., methane) is promoted by the oxidation catalyst 31 contained in the oxidation catalyst device 3. The exhaust gas that has passed through the oxidation catalyst device 3 is discharged from the exhaust gas outlet 43 to the outside of the casing main body 41 (the downstream exhaust gas line 12B).

[0020] When the exhaust gas passes through the oxidation catalyst device 3, the temperature of the exhaust gas increases due to an oxidation reaction caused by the oxidation catalyst 31. For example, in an oxidation catalyst system 2 not including a heat exchanger 5, when the exhaust gas flowing through the first internal space 40A has a temperature of about 400°C, the exhaust gas that has been heated by an oxidation reaction caused by the oxidation catalyst 31 and flows through the second internal space 40B has a temperature of about 440°C.

[0021] (heat exchanger) The heat exchanger 5 is configured to exchange heat between the purified gas, which is exhaust gas that has passed through the oxidation catalyst device 3 and has been heated by an oxidation reaction by the oxidation catalyst 31, and the exhaust gas flowing upstream of the oxidation catalyst device 3 in the exhaust gas line 12. The heat exchanger 5 is a heat exchanger for recovering thermal energy of the purified gas. The heat exchange in the heat exchanger 5 cools the purified gas, and heats the exhaust gas flowing upstream of the oxidation catalyst device 3 in the exhaust gas line 12.

[0022] For example, when the exhaust gas introduced into the heat exchanger 5 is at about 400°C, the exhaust gas is heated to about 410°C by heat exchange between the exhaust gas and the purified gas in the heat exchanger 5. The exhaust gas that has passed through the heat exchanger 5 is further heated by an oxidation reaction caused by the oxidation catalyst 31, so that the exhaust gas flowing through the second internal space 40B becomes at about 450°C. The purified gas is cooled from about 450°C to about 425°C by heat exchange with the exhaust gas in the heat exchanger 5.

[0023] In the illustrated embodiment, the heat exchanger 5 is provided upstream of the oxidation catalyst device 3 in the exhaust gas line 12, and includes at least one heat transfer tube 51 through which the purified gas flows in an internal flow path. The exhaust gas flows around the heat transfer tube 51 before being introduced into the oxidation catalyst device 3. In the embodiment illustrated in FIGS. 1 and 2, the at least one heat transfer tube 51 is disposed in the first internal space 40A, and the thermal energy of the purified gas flowing through the heat transfer tube 51 is transferred to the exhaust gas flowing through the first internal space 40A.

[0024] At one end of the at least one heat transfer tube 51 described above, a purified gas inlet is formed for introducing purified gas from the outside into the heat transfer tube 51. At the other end of the at least one heat transfer tube 51 described above, a purified gas outlet is formed for discharging purified gas from the heat transfer tube 51 to the outside.

[0025] (Inlet gas duct, outlet gas duct) In the illustrated embodiment, the oxidation catalyst system 2 further includes an inlet gas duct 21 attached to the outside of the catalyst casing 4, and an outlet gas duct 22 attached to the outside of the catalyst casing 4. In the case where the at least one heat transfer tube 51 described above includes a plurality of heat transfer tubes 51, each of the plurality of heat transfer tubes 51 has a purified gas inlet connected to the common inlet gas duct 21 and a purified gas outlet connected to the common outlet gas duct 22.

[0026] (Purified gas inlet line, purified gas return line) The purified gas introduction line 13 forms a flow path for extracting the purified gas from the exhaust gas line 12 downstream of the oxidation catalyst device 3 and guiding it to the heat exchanger 5. The purified gas return line 14 forms a flow path for returning the purified gas from the heat exchanger 5 to the exhaust gas line 12 downstream of a first connection part P1, which is a connection part between the exhaust gas line 12 and the purified gas introduction line 13. Each of the purified gas introduction line 13 and the purified gas return line 14 is formed by, for example, piping.

[0027] In the illustrated embodiment, the purified gas introduction line 13 has an upstream end connected to a first connection part P1 of the downstream exhaust gas line 12B, and a downstream end connected to an inlet gas duct 21. The purified gas return line 14 has an upstream end connected to an outlet gas duct 22, and a downstream end connected to a second connection part P2, which is a connection part downstream of the first connection part P1 of the downstream exhaust gas line 12B. The purified gas introduced to the at least one heat transfer tube 51 via the purified gas introduction line 13 is introduced to the exhaust gas line 12 downstream of the catalyst casing 4 via the purified gas return line 14.

[0028] (Purified gas temperature acquisition device, purified gas flow rate adjustment device) 1 and 2, the oxidation catalyst system 2 according to some embodiments further includes a purified gas temperature acquisition device 6 and a purified gas flow rate adjustment device 7. The purified gas temperature acquisition device 6 is configured to acquire the temperature of the purified gas flowing downstream of the oxidation catalyst 31 in the exhaust gas line 12.

[0029] The purified gas flow rate adjusting device 7 is configured to adjust the flow rate of the purified gas guided to the heat exchanger 5 according to the measured temperature MT, which is the temperature of the purified gas acquired by the purified gas temperature acquiring device 6. The purified gas flow rate adjusting device 7 increases the flow rate of the purified gas guided to the heat exchanger 5 in order to activate the oxidation catalyst 31. As the flow rate of the purified gas guided to the heat exchanger 5 increases, the temperature of the purified gas flowing downstream of the oxidation catalyst 31 increases. When the temperature of the purified gas flowing downstream of the oxidation catalyst 31 exceeds a target value, the purified gas flow rate adjusting device 7 reduces the flow rate of the purified gas guided to the heat exchanger 5 to protect equipment such as piping that constitutes the downstream side of the second connecting part P2 of the exhaust gas line 12, thereby lowering the temperature of the purified gas flowing downstream of the oxidation catalyst 31. Specifically, the purified gas flow rate adjusting device 7 adjusts the flow rate of the purified gas guided to the heat exchanger 5, thereby making it possible to lower the temperature of the purified gas flowing through the second internal space 40B. This makes it possible to lower the temperature of the purified gas flowing downstream of the second connection part P2 of the exhaust gas line 12, and suppress thermal damage to equipment such as piping that configures the downstream side of the second connection part P2 of the exhaust gas line 12. Examples of equipment such as piping that configures the downstream side of the second connection part P2 of the exhaust gas line 12 include a flue, a silencer, and a spark arrester that prevents sparks and fireworks from scattering.

[0030] According to the above configuration, the purified gas flow rate adjusting device 7 adjusts the flow rate of the purified gas guided to the heat exchanger 5 in accordance with the purified gas temperature MT acquired by the purified gas temperature acquiring device 6, thereby making it possible to suppress an excessive increase in the temperature of the purified gas flowing downstream of the oxidation catalyst 31. This makes it possible to suppress damage to equipment, such as piping, that constitutes the exhaust gas line 12 downstream of the second connecting part P2 due to the heat of the purified gas without increasing the heat resistance temperature of the equipment.

[0031] 1 and 2, in some embodiments, the purified gas temperature acquisition device 6 is configured to acquire the temperature of the purified gas flowing downstream of the oxidation catalyst 31 and upstream of the first connection part P1 of the exhaust gas line 12. The purified gas temperature acquisition device 6 may be provided in the second internal space 40B of the catalyst casing 4 to measure the temperature of the purified gas flowing through the second internal space 40B, or may be provided at a position upstream of the first connection part P1 of the downstream exhaust gas line 12B to measure the temperature of the purified gas flowing through the position. The purified gas temperature acquisition device 6 may include a temperature sensor configured to measure the temperature of the purified gas.

[0032] According to the above configuration, the position where the purified gas temperature acquisition device 6 acquires the purified gas temperature is downstream of the oxidation catalyst 31 of the exhaust gas line 12 and upstream of the first connection part P1. That is, the purified gas temperature acquisition device 6 can directly acquire the purified gas temperature near the second internal space 40B. In regulating the flow rate of the purified gas by the purified gas flow rate control device 7, the temperature of the purified gas flowing downstream of the oxidation catalyst 31 and upstream of the first connection part P1 of the exhaust gas line 12 can be more reliably kept below the above-mentioned heat-resistant temperature by using the purified gas temperature near the second internal space 40B acquired by the purified gas temperature acquisition device 6. As a result, the temperature of the purified gas flowing downstream of the second connection part P2 of the exhaust gas line 12 can be kept below the above-mentioned heat-resistant temperature, and damage caused by the heat of the purified gas to the equipment constituting the downstream side of the second connection part P2 of the exhaust gas line 12 can be suppressed.

[0033] (First opening / closing damper, induced draft fan) In some embodiments, the above-mentioned purified gas flow rate control device 7, as shown in FIG. 1, includes a first opening / closing damper 81 that is provided in the purified gas inlet line 13 and opens and closes the purified gas inlet line 13, and an induced draft fan 82 that is provided downstream of the first opening / closing damper 81 in the purified gas inlet line 13 and sucks the purified gas from the exhaust gas line 12 into the purified gas inlet line 13.

[0034] The induced draft fan 82 is driven by power supplied from a generator (not shown) or the like, and sends the purified gas to the downstream side of the purified gas introduction line 13.

[0035] According to the above configuration, even when there is no margin for exhaust pressure in the oxidation catalyst system 2, that is, when the pressure difference between the purified gas flowing through the purified gas inlet line 13 and the purified gas flowing downstream of the second connection part P2 which is the connection part of the exhaust gas line 12 with the purified gas return line 14 is small, the induced draft fan 82 can reliably guide the purified gas to the heat exchanger 5. In addition, the flow rate of the purified gas guided to the heat exchanger 5 can be adjusted by opening and closing the first open / close damper 81.

[0036] In some embodiments, the above-mentioned purified gas flow control device 7 is provided downstream of the first connection part P1 of the exhaust gas line 12 and upstream of the second connection part P2, which is the connection part with the purified gas return line 14, as shown in FIG. 2, and includes a second opening / closing damper 83 that opens and closes the exhaust gas line 12.

[0037] According to the above configuration, when there is a margin in the exhaust pressure of the oxidation catalyst system 2, that is, when there is a large pressure difference between the purified gas flowing through the purified gas introduction line 13 and the purified gas flowing downstream of the second connection part P2 of the exhaust gas line 12, there is no need for a device for sending the purified gas to the heat exchanger 5, such as the above-mentioned induced draft fan 82. That is, by opening and closing the second open-close damper 83, it is possible to send the purified gas to the heat exchanger 5 and adjust the flow rate of the purified gas introduced to the heat exchanger 5. In this case, since there is no need for a device for sending the purified gas, the structure of the oxidation catalyst system 2 can be simplified.

[0038] Each of the above-mentioned first opening / closing damper 81 and second opening / closing damper 83 may be an opening / closing valve whose opening degree can be adjusted to fully closed or fully open, or may be an opening degree adjustment valve whose opening degree can be adjusted to fully closed, fully open, and at least one intermediate opening degree between them.

[0039] (Adjustment of flow rate of purified gas) Fig. 3 is a block diagram showing an example of opening control of the first on-off damper 81 in the oxidation catalyst system 2 shown in Fig. 1. Fig. 4 is a block diagram showing an example of opening control of the second on-off damper 83 in the oxidation catalyst system 2 shown in Fig. 2. In some embodiments, the above-mentioned purified gas flow rate adjustment device 7 is configured to adjust the flow rate of the purified gas guided to the heat exchanger 5 so that the purified gas temperature MT acquired by the purified gas temperature acquisition device 6 approaches the target temperature TT of the purified gas.

[0040] In the illustrated embodiment, as shown in Figs. 1 to 4, the purified gas flow rate control device 7 further includes a control device (controller) 70 configured to control the operation of the first open / close damper 81 or the second open / close damper 83. The control device 70 is an electronic control unit for controlling the first open / close damper 81 or the second open / close damper 83. The control device 70 is configured as a microcomputer including a CPU (processor) (not shown), memories such as ROM and RAM, a storage device such as an external storage device, an I / O interface, a communication interface, and the like. The control device 70 may realize control of each functional unit provided in the control device 70 by the CPU operating (e.g., calculating data, etc.) according to instructions of a program loaded into the main storage device of the memory, for example.

[0041] As shown in Fig. 3 and Fig. 4, the control device 70 includes a purified gas temperature acquisition unit 71A, a damper opening degree output unit 72, a PID control unit 73, and a control value conversion unit 74. The purified gas temperature acquisition unit 71A is connected so as to be able to receive a signal (a signal related to the measured temperature MT) from the purified gas temperature acquisition device 6, and is configured to receive information such as a signal related to the measured temperature MT of the purified gas from the purified gas temperature acquisition device 6. The PID control unit 73 performs a PID control (feedback control) operation so that the measured temperature MT of the purified gas acquired by the purified gas temperature acquisition unit 71A approaches a target temperature TT of the purified gas. The control value conversion unit 74 converts the control value output by the PID control unit 73 into an opening degree instruction value for the first opening / closing damper 81 or the second opening / closing damper 83. The damper opening output unit 72 is connected to the first opening / closing damper 81 or the second opening / closing damper 83 so as to be able to transmit a signal (a signal related to an opening instruction value) to the first opening / closing damper 81 or the second opening / closing damper 83, and is configured to transmit the above-mentioned opening instruction value to the first opening / closing damper 81 or the second opening / closing damper 83. The first opening / closing damper 81 or the second opening / closing damper 83 is configured to change the opening to an opening corresponding to the opening instruction value transmitted from the damper opening output unit 72.

[0042] According to the above configuration, by bringing the purified gas temperature MT acquired by the purified gas temperature acquisition device 6 closer to the target purified gas temperature TT, an excessive increase in the temperature of the purified gas flowing downstream of the second connection part P2 can be suppressed, and the exhaust gas that has passed through the heat exchanger 5 can raise the temperature of the oxidation catalyst 31 to a temperature at which it can perform its functions.

[0043] In some embodiments, the above-mentioned purified gas flow rate control device 7 is configured to reduce the flow rate of the purified gas guided to the heat exchanger 5 when the purified gas temperature MT acquired by the purified gas temperature acquisition device 6 is higher than the target temperature TT.

[0044] In the illustrated embodiment, the PID control unit 73 is configured to output an output value for decreasing the opening degree of the first open / close damper 81 or increasing the opening degree of the second open / close damper 83 when the purified gas temperature MT acquired by the purified gas temperature acquisition device 6 is higher than the target temperature TT. The PID control unit 73 is configured to output an output value for increasing the opening degree of the first open / close damper 81 or decreasing the opening degree of the second open / close damper 83 when the purified gas temperature MT acquired by the purified gas temperature acquisition device 6 is lower than the target temperature TT.

[0045] According to the above configuration, when the acquired temperature MT of the purified gas is higher than the target temperature TT, the flow rate of the purified gas guided to the heat exchanger 5 can be reduced. By reducing the flow rate of the purified gas guided to the heat exchanger 5 and reducing the thermal energy of the purified gas recovered in the exhaust gas in the heat exchanger 5, the temperature of the purified gas flowing downstream of the oxidation catalyst 31 can be lowered. This makes it possible to suppress an excessive increase in the temperature of the purified gas flowing downstream of the oxidation catalyst 31.

[0046] Depending on the type and specifications of the internal combustion engine 11, the load EL of the internal combustion engine 11 and the exhaust gas temperature may have the following tendency. That is, the exhaust gas discharged from the internal combustion engine 11 may have a tendency that the exhaust gas temperature increases as the load EL increases in a region where the load EL of the internal combustion engine 11 is equal to or lower than a predetermined load (e.g., 75%), and may have a tendency that the exhaust gas temperature decreases as the load EL increases in a region where the load EL of the internal combustion engine 11 exceeds the predetermined load.

[0047] (Target temperature adjustment) In some embodiments, the purified gas flow control device 7 described above is configured to increase the target temperature TT of the purified gas when the load EL of the internal combustion engine 11 is higher than a predetermined load (for example, 75%) and the load EL increases. The purified gas flow control device 7 may gradually increase the target temperature TT of the purified gas as the load EL increases in a region where the load EL is higher than the predetermined load, or may divide the region where the load EL is higher than the predetermined load into a plurality of regions and increase the target temperature TT of the purified gas stepwise for each divided region. As shown in FIG. 3 and FIG. 4, the purified gas flow control device 7 may further include a load acquisition unit 71B that acquires the load EL of the internal combustion engine 11, and a target temperature adjustment unit 75 configured to adjust the target temperature TT according to the load EL acquired by the load acquisition unit 71B. The target temperature adjustment unit 75 may be configured to perform the increase control of the target temperature TT associated with the increase in the load EL of the purified gas flow control device 7 described above and the decrease control of the target temperature TT associated with the decrease in the load EL described later. The load acquisition unit 71B is configured to receive information such as signals relating to the load EL from the internal combustion engine 11, the generator 15, and the like.

[0048] According to the above configuration, when the load EL of the internal combustion engine 11 is higher than a predetermined load, if the load EL increases, the temperature of the exhaust gas from the internal combustion engine 11 drops, and the efficiency of the oxidation reaction by the oxidation catalyst 31 drops by the amount of the drop in the exhaust gas temperature. In this case, by raising the target temperature TT of the purified gas with the purified gas flow rate control device 7 and increasing the flow rate of the purified gas led to the heat exchanger 5, the temperature of the exhaust gas led to the oxidation catalyst 31 can be raised, and the efficiency of the oxidation reaction by the oxidation catalyst 31 can be improved.

[0049] In some embodiments, the above-mentioned purified gas flow rate control device 7 is configured to lower the target temperature TT of the purified gas when the load EL of the internal combustion engine 11 is higher than a predetermined load (e.g., 75%) and the load EL decreases. Note that the purified gas flow rate control device 7 may gradually lower the target temperature TT of the purified gas as the load EL decreases in a region where the load EL is higher than the predetermined load, or may divide the region where the load EL is higher than the predetermined load into a plurality of regions and gradually lower the target temperature TT of the purified gas for each divided region.

[0050] According to the above configuration, when the load EL of the internal combustion engine 11 is higher than a predetermined load, if the load EL decreases, the temperature of the exhaust gas from the internal combustion engine 11 rises, and the efficiency of the oxidation reaction by the oxidation catalyst 31 increases by the amount of the increase in the exhaust gas temperature. In this case, by lowering the target temperature TT of the purified gas by the purified gas flow rate control device 7 and reducing the flow rate of the purified gas led to the heat exchanger 5, the temperature of the exhaust gas led to the oxidation catalyst 31 can be lowered, and thermal damage to devices provided downstream of the oxidation catalyst 31 in the flow direction of the purified gas can be reliably prevented.

[0051] In some embodiments, the purified gas flow rate control device 7 may have a constant target temperature TT regardless of changes in the load EL.

[0052] In this specification, expressions expressing relative or absolute configuration, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," do not only strictly represent such a configuration, but also represent a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions indicating that things are in an equal state, such as "identical," "equal," and "homogeneous," not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. Furthermore, in this specification, expressions describing shapes such as a rectangular shape or a cylindrical shape do not only refer to shapes such as a rectangular shape or a cylindrical shape in the strict geometric sense, but also refer to shapes that include uneven portions, chamfered portions, etc., to the extent that the same effect is obtained. In addition, in this specification, the expressions "comprise," "include," or "have" a certain element are not exclusive expressions that exclude the presence of other elements.

[0053] The present disclosure is not limited to the above-described embodiments, and includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0054] The contents described in the above-mentioned embodiments can be understood, for example, as follows.

[0055] 1) At least one embodiment of the oxidation catalyst system (2) according to the present disclosure comprises: an oxidation catalyst (31) provided in an exhaust gas line (12) through which exhaust gas discharged from an internal combustion engine (11) flows and configured to oxidize the exhaust gas; a heat exchanger (5) configured to exchange heat between a purified gas, which is the exhaust gas heated by an oxidation reaction in the oxidation catalyst (31), and the exhaust gas flowing upstream of the oxidation catalyst (31) in the exhaust gas line (12); a purified gas introduction line (13) for extracting the purified gas from a downstream side of the oxidation catalyst (31) of the exhaust gas line (12) and introducing the purified gas into the heat exchanger (5); a purified gas return line (14) for returning the purified gas from the heat exchanger (5) to a downstream side of a first connection part (P1) which is a connection part between the heat exchanger (5) and the purified gas introduction line (13) of the exhaust gas line (12); a purified gas temperature acquisition device (6) configured to acquire a temperature of the purified gas flowing downstream of the oxidation catalyst (31) in the exhaust gas line (12); and a purified gas flow rate adjustment device (7) configured to adjust the flow rate of the purified gas introduced to the heat exchanger (5) in accordance with the temperature (MT) of the purified gas acquired by the purified gas temperature acquisition device (6).

[0056] According to the above configuration 1), the purified gas flow rate control device (7) adjusts the flow rate of the purified gas guided to the heat exchanger (5) in accordance with the purified gas temperature (MT) acquired by the purified gas temperature acquisition device (6), thereby making it possible to suppress an excessive increase in the temperature of the purified gas flowing downstream of the oxidation catalyst (31). This makes it possible to suppress damage to the equipment downstream of the second connection part (P2) of the exhaust gas line (12) due to the heat of the purified gas, without increasing the heat-resistant temperature of the equipment.

[0057] 2) In some embodiments, the oxidation catalyst system (2) described in 1) above, The purified gas flow rate control device (7) is The flow rate of the purified gas guided to the heat exchanger (5) is adjusted so that the temperature (MT) of the purified gas acquired by the purified gas temperature acquisition device (6) approaches a target temperature (TT) of the purified gas.

[0058] According to the above configuration 2), by bringing the purified gas temperature (MT) acquired by the purified gas temperature acquisition device (6) closer to the target temperature (TT) of the purified gas, an excessive increase in the temperature of the purified gas flowing downstream of the second connection part (P2) can be suppressed, and the exhaust gas that has passed through the heat exchanger (5) can raise the temperature of the oxidation catalyst (31) to a temperature at which the oxidation catalyst (31) can exhibit its performance.

[0059] 3) In some embodiments, the oxidation catalyst system (2) described in 2) above, The purified gas flow rate control device (7) is When the temperature (MT) of the purified gas acquired by the purified gas temperature acquisition device (6) is higher than the target temperature (TT), the flow rate of the purified gas introduced to the heat exchanger (5) is reduced.

[0060] According to the above configuration 3), when the acquired temperature (MT) of the purified gas is higher than the target temperature (TT), the flow rate of the purified gas guided to the heat exchanger (5) can be reduced. By reducing the flow rate of the purified gas guided to the heat exchanger (5) and reducing the thermal energy of the purified gas recovered in the exhaust gas by the heat exchanger (5), the temperature of the purified gas flowing downstream of the oxidation catalyst (31) can be lowered. This makes it possible to suppress an excessive increase in the temperature of the purified gas flowing downstream of the oxidation catalyst (31).

[0061] 4) In some embodiments, the oxidation catalyst system (2) according to 2) or 3) above, The purified gas flow rate control device (7) is When a load (EL) of the internal combustion engine (11) is higher than a predetermined load, the target temperature (TT) of the purified gas is increased when the load (EL) increases.

[0062] According to the above configuration 4), when the load (EL) of the internal combustion engine (11) is higher than a predetermined load, if the load (EL) increases, the temperature of the exhaust gas from the internal combustion engine (11) decreases, and the efficiency of the oxidation reaction by the oxidation catalyst (31) decreases by the amount of the decrease in the exhaust gas temperature. In this case, the target temperature (TT) of the purified gas is increased by the purified gas flow rate control device (7) and the flow rate of the purified gas introduced to the heat exchanger (5) is increased, whereby the temperature of the exhaust gas introduced to the oxidation catalyst (31) can be increased and the efficiency of the oxidation reaction by the oxidation catalyst (31) can be improved.

[0063] 5) In some embodiments, the oxidation catalyst system (2) according to 2) or 3) above, The purified gas flow rate control device (7) is When a load (EL) of the internal combustion engine (11) is higher than a predetermined load, the target temperature (TT) of the purified gas is lowered when the load (EL) decreases.

[0064] According to the above configuration 5), when the load (EL) of the internal combustion engine (11) is higher than a predetermined load, if the load (EL) decreases, the temperature of the exhaust gas from the internal combustion engine (11) increases, and the efficiency of the oxidation reaction by the oxidation catalyst (31) increases by the amount of the increase in the exhaust gas temperature. In this case, the target temperature (TT) of the purified gas is lowered by the purified gas flow rate control device (7) to reduce the flow rate of the purified gas introduced to the heat exchanger (5), thereby making it possible to lower the temperature of the exhaust gas introduced to the oxidation catalyst (31), and it is possible to reliably prevent thermal damage to devices provided downstream of the oxidation catalyst (31) in the flow direction of the purified gas.

[0065] 6) In some embodiments, the oxidation catalyst system (2) according to any one of 1) to 5) above, The purified gas flow rate control device (7) is a first opening / closing damper (81) provided in the purified gas introduction line (13) for opening and closing the purified gas introduction line (13); an induction fan (82) provided on the purified gas introduction line (13) downstream of the first open / close damper (81) for sucking the purified gas from the exhaust gas line (12) into the purified gas introduction line (13).

[0066] According to the above configuration 6), even if the exhaust pressure of the oxidation catalyst system (2) is not sufficient, the purified gas can be reliably guided to the heat exchanger (5) by the induction fan (82). In addition, the flow rate of the purified gas guided to the heat exchanger (5) can be adjusted by opening and closing the first open-close damper (81).

[0067] 7) In some embodiments, the oxidation catalyst system (2) according to any one of 1) to 5) above, The purified gas flow rate control device (7) is The exhaust gas line (12) includes a second opening / closing damper (83) that is provided downstream of the first connecting portion (P1) and upstream of a second connecting portion (P2) that is a connecting portion with the purified gas return line (14) and opens and closes the exhaust gas line (12).

[0068] According to the above configuration 7), when there is sufficient exhaust pressure in the oxidation catalyst system (2), a device for sending purified gas to the heat exchanger (5), such as the above-mentioned induction fan (82), is not required. That is, by opening and closing the second open / close damper (83), it is possible to send purified gas to the heat exchanger (5) and adjust the flow rate of the purified gas guided to the heat exchanger (5). In this case, since no device for sending purified gas is required, the structure of the oxidation catalyst system (2) can be simplified.

[0069] 8) In some embodiments, the oxidation catalyst system (2) according to any one of 1) to 7) above, The purified gas temperature acquisition device (6) The temperature of the purified gas flowing upstream of the first connection part (P1) of the exhaust gas line (12) is acquired.

[0070] According to the above configuration 8), the position where the purified gas temperature is acquired by the purified gas temperature acquisition device (6) is downstream of the oxidation catalyst (31) of the exhaust gas line (12) and upstream of the first connection part (P1). That is, the purified gas temperature in the vicinity of the second internal space (40B) can be directly acquired by the purified gas temperature acquisition device (6). In the adjustment of the flow rate of the purified gas by the purified gas flow control device (7), the temperature of the purified gas flowing downstream of the oxidation catalyst (31) and upstream of the first connection part (P1) of the exhaust gas line (12) can be more reliably kept below the above-mentioned heat-resistant temperature by using the purified gas temperature in the vicinity of the second internal space (40B) acquired by the purified gas temperature acquisition device (6). As a result, the temperature of the purified gas flowing downstream of the second connection part (P2) of the exhaust gas line (12) can be kept below the above-mentioned heat-resistant temperature, and damage to devices downstream of the second connection part (P2) of the exhaust gas line (12) due to heat of the purified gas can be suppressed. [Explanation of symbols]

[0071] 1 Internal Combustion Engine System 2. Oxidation Catalyst System 3. Oxidation catalyst device 4 Catalyst casing 5 Heat exchanger 6. Purified gas temperature acquisition device 7 Purified gas flow regulator 11 Internal combustion engine 12 Exhaust gas line 12A Upstream exhaust gas line 12B Downstream exhaust gas line 13 Purified gas introduction line 14 Purified gas return line 15. Generator 21 Inlet gas duct 22 Exit gas duct 31 Oxidation Catalyst 40 Interior Space 40A First Internal Space 40B 2nd internal space 41 Casing body 42 Exhaust gas inlet 43 Exhaust gas outlet 51 Heat transfer tube 70 Control device 71A Purified gas temperature acquisition unit 71B Load acquisition part 72 Damper opening output section 73 PID control unit 74 Control value conversion unit 75 Target temperature adjustment section 81 First opening / closing damper 82 Attracting Fans 83 Second opening / closing damper EL Internal combustion engine load MT Measured temperature of purified gas P1 First connection part P2 Second connection part TT target temperature

Claims

1. An oxidation catalyst provided in an exhaust gas line through which exhaust gas discharged from an internal combustion engine flows, the oxidation catalyst being configured to oxidize the exhaust gas; a heat exchanger configured to perform heat exchange between a purified gas, which is the exhaust gas heated by an oxidation reaction by the oxidation catalyst, and the exhaust gas flowing upstream of the oxidation catalyst in the exhaust gas line; a purified gas introduction line for extracting the purified gas from a downstream side of the oxidation catalyst of the exhaust gas line and introducing the purified gas into the heat exchanger; a purified gas return line for returning the purified gas from the heat exchanger to a downstream side of a first connection portion which is a connection portion between the exhaust gas line and the purified gas introduction line; a purified gas temperature acquisition device configured to acquire a temperature of the purified gas flowing downstream of the oxidation catalyst in the exhaust gas line; a purified gas flow rate adjustment device configured to adjust a flow rate of the purified gas guided to the heat exchanger in accordance with the temperature of the purified gas acquired by the purified gas temperature acquisition device, The purified gas flow rate control device is When the temperature of the purified gas acquired by the purified gas temperature acquisition device is higher than a target temperature, the flow rate of the purified gas guided to the heat exchanger is reduced within a range not to zero. Oxidation catalyst system.

2. The purified gas flow rate control device is The flow rate of the purified gas guided to the heat exchanger is adjusted so that the temperature of the purified gas acquired by the purified gas temperature acquisition device approaches the target temperature of the purified gas. The oxidation catalyst system of claim 1 .

3. The purified gas flow rate control device is When a load of the internal combustion engine is higher than a predetermined load, the target temperature of the purified gas is increased when the load increases.

3. The oxidation catalyst system according to claim 1 or 2.

4. The purified gas flow rate control device is When a load of the internal combustion engine is higher than a predetermined load, the target temperature of the purified gas is reduced when the load is reduced.

3. The oxidation catalyst system according to claim 1 or 2.

5. The purified gas flow rate control device is a first opening / closing damper provided in the purified gas introduction line for opening and closing the purified gas introduction line; an induction fan provided downstream of the first open / close damper in the purified gas introduction line for sucking the purified gas from the exhaust gas line to the purified gas introduction line; 3. The oxidation catalyst system according to claim 1 or 2.

6. The purified gas flow rate control device is a second opening / closing damper that is provided downstream of the first connecting portion of the exhaust gas line and upstream of a second connecting portion that is a connecting portion with the purified gas return line, and that opens and closes the exhaust gas line; 3. The oxidation catalyst system according to claim 1 or 2.

7. The purified gas temperature acquisition device is The temperature of the purified gas flowing upstream of the first connection portion of the exhaust gas line is acquired.

3. The oxidation catalyst system according to claim 1 or 2.

Images