JP6122300B2 - Engine system and ship - Google Patents

Description

  The present invention relates to an engine system that performs exhaust heat recovery in an EGR unit.

  Some engine systems such as ships have a composite boiler to improve energy efficiency. The composite boiler is an integrated exhaust gas economizer and boiler, and is mainly composed of an exhaust gas economizer, a burner section, and an air / water separation section. In the exhaust gas economizer, the water to be heated (boiler water) is heated using the heat of the exhaust gas, and if the amount of heat is insufficient, additional heating is performed in the burner section. Further, the steam / water separation unit separates the steam generated by heating the water to be heated and the water to be heated, and supplies only the steam to the outside. If it is a marine engine system, the steam generated by the composite boiler is used as a heat source for heating to reduce the viscosity of fuel (C heavy oil), a heat source for generating distilled water by a water generator, and the like. .

  Some engine systems include an EGR (Exhaust Gas Recirculation) unit that returns part of exhaust gas to the engine body for the purpose of reducing NOx generation. Even an engine system equipped with a composite boiler can be equipped with an EGR unit. However, in this case, since the EGR unit returns a part of the exhaust gas to the engine body as EGR gas, the amount of exhaust gas flowing into the composite boiler is reduced, and the recoverable heat amount is reduced. As a result, a large amount of fuel is consumed in the burner section, and the energy efficiency of the entire engine system is reduced.

  Based on this, Patent Document 1 proposes an exhaust heat recovery system in which an exhaust gas economizer is arranged in an EGR unit. Patent Document 1 describes that according to the present invention, a waste heat recovery system that is compact and has high exhaust heat recovery efficiency can be provided.

JP 2012-172647 A

  In each drawing of Patent Document 1, devices associated with the exhaust gas economizer are not shown, but various devices are required to actually use the heated water and steam heated by the exhaust gas economizer. Specifically, an auxiliary boiler for additional cooking for generating stable steam and an air / water separator for separating generated steam from heated water are required. Alternatively, there is a method of replacing the exhaust gas economizer with the above-described composite boiler.

  Providing various devices associated with the exhaust gas economizer or replacing the exhaust gas economizer with a composite boiler leads to an increase in the size of the EGR unit. However, the EGR unit is often attached to the engine body for easy onboard installation and is required to be compact.

  The present invention has been made in view of such circumstances, and an object thereof is to provide an engine system in which an EGR unit is relatively compact while an exhaust gas economizer is provided in the EGR unit.

  An engine system according to an aspect of the present invention includes an engine body, a supercharger unit driven by exhaust gas, an EGR unit that recirculates a part of the exhaust gas as EGR gas to the engine body, and the supercharger. A composite boiler that is disposed downstream of the machine unit, has an exhaust gas economizer inside, and is capable of separating air and water, and the EGR unit has an EGR economizer that heats heated water with EGR gas, The heated water heated by the EGR economizer and the steam generated by heating the heated water are supplied to the composite boiler, and the heated water and the steam are separated by the composite boiler. Has been.

  According to this configuration, the heated water heated by the EGR economizer and the steam generated by heating the heated water are supplied to the separately provided composite boiler and processed into a usable state. Therefore, there is no need to provide an auxiliary boiler and a steam / water separator or a composite boiler in the EGR unit. Therefore, the EGR unit can be configured compactly.

  In the engine system, the EGR unit may include an EGR gas cooler that cools EGR gas, and the EGR economizer may be disposed upstream of the EGR gas cooler. According to such a configuration, since the EGR gas whose temperature has been reduced by the heat exchange by the EGR economizer is supplied to the EGR gas cooler, the burden on the EGR gas cooler can be reduced. As a result, the EGR gas cooler can be kept small.

  In the engine system, the EGR unit may further include a scrubber that removes dust of EGR gas with a cleaning liquid, and the EGR gas cooler may be disposed on the downstream side of the scrubber. According to this configuration, the EGR gas saturated with the cleaning liquid of the cleaning dust collector is cooled by the EGR gas cooler. Therefore, water can be removed from the EGR gas as condensed water. Thereby, it is possible to prevent the condensed water from being generated in the equipment downstream of the scrubber and adversely affecting the equipment.

  In the above engine system, the supercharger unit includes a first supercharger and a second supercharger arranged in parallel with the first supercharger, and the EGR unit is an EGR gas. When the engine is recirculated to the engine body, the second supercharger may be stopped. According to this configuration, even if the flow rate of the exhaust gas flowing into the supercharger unit is reduced by EGR (exhaust gas recirculation), the second supercharger is stopped to flow into the first supercharger. It can suppress that the flow volume of exhaust gas falls. Therefore, since scavenging gas (supply gas) having a sufficiently high pressure can be supplied to the engine body and the maximum combustion pressure can be increased, deterioration of the fuel consumption of the engine body can be suppressed. At the same time, the temperature of the exhaust gas discharged from the engine body also decreases, so that the burden on the EGR gas cooler can be reduced.

  In the engine system described above, the first supercharger may be provided with a variable nozzle at the turbine inlet. According to such a configuration, in addition to stopping the second supercharger at a low load or the like, the opening area of the variable nozzle is changed in accordance with the flow rate of the exhaust gas flowing into the first supercharger. Can be further suppressed. Moreover, the temperature of the exhaust gas discharged from the engine body is further lowered, and the burden on the EGR gas cooler can be further reduced.

  In the engine system, the supercharger unit has a first supercharger provided with a variable nozzle at an inlet of a turbine portion, and when the EGR gas is recirculated to the engine body, You may be comprised so that opening area may be made small. According to such a configuration, even if the flow rate of the exhaust gas flowing into the supercharger unit is reduced by EGR, it is possible to further suppress the deterioration of the supercharging performance in the first supercharger. Therefore, since the scavenging gas (supply gas) having a sufficiently high pressure can be supplied to the engine body, it is possible to prevent the fuel consumption of the engine body from deteriorating. Moreover, the temperature of the exhaust gas discharged from the engine body is further lowered, and the burden on the EGR gas cooler can be further reduced.

  The engine system may further include a SOx removing device that removes SOx from the exhaust gas using the wash water, and the SOx removing device may be disposed downstream of the supercharger unit. As described above, by suppressing the deterioration of the fuel consumption of the engine body, the temperature of the exhaust gas discharged from the engine body decreases. In the SOx removal device, the lower the exhaust gas temperature, the higher the SOx removal efficiency. Therefore, according to this configuration, SOx can be efficiently removed from the exhaust gas.

The engine system may be configured such that EGR gas that has passed through the EGR economizer can be supplied to the composite boiler. According to such a configuration, even if the amount of steam generated in the composite boiler is reduced due to a decrease in the temperature of the exhaust gas discharged from the engine body as a result of the efficient operation of the engine body, the EGR economizer Since steam can be generated in this manner, it is possible to make up for insufficient steam while suppressing fuel consumption by the burner section.

  The ship which concerns on a certain form of this invention is equipped with said engine system.

  As described above, according to the engine system described above, the EGR unit can be configured to be relatively compact while the exhaust gas economizer is provided in the EGR unit.

FIG. 1 is a block diagram of an engine system according to the first embodiment of the present invention. FIG. 2 is a block diagram of an engine system according to the second embodiment of the present invention. FIG. 3 is a block diagram of an engine system according to the third embodiment of the present invention. FIG. 4 is a block diagram of an engine system according to the fourth embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Below, the same code | symbol is attached | subjected to the element which is the same or it corresponds through all the drawings, and the overlapping description is abbreviate | omitted.

(First embodiment)
First, a first embodiment of the present invention will be described. FIG. 1 is a block diagram of an engine system 100 according to the first embodiment. As shown in FIG. 1, an engine system 100 according to the present embodiment is mounted on a large ship 101, and includes an engine body 10, a supercharger unit 20, an EGR unit 40, and a composite boiler 60. And a control device 70. Hereinafter, each of these components will be described in order. Of the arrows shown in FIG. 1, the broken arrow indicates the flow of scavenging gas (fresh air) supplied to the engine body 10, and the solid arrow indicates the flow of exhaust gas discharged from the engine body 10. The arrows of the alternate long and short dash line indicate the flow of heated water.

<Engine body>
The engine body 10 of this embodiment is a marine two-stroke diesel engine. However, the engine body 10 may be another type of engine such as a 4-stroke engine. In the case of a four-stroke engine, the gas supplied to the engine body is called “supply gas” instead of “scavenging gas”. Here, “supply gas” is also included in “scavenging gas”. As shown in FIG. 1, the engine body 10 of the present embodiment includes a plurality of cylinders 11, a single scavenging pipe 12 positioned upstream of each cylinder 11, and a single positioned downstream of each cylinder 11. The exhaust pipe 13 is provided. The scavenging pipe 12 and the exhaust pipe 13 are both formed in a cylindrical shape, and have functions of suppressing pulsation caused by the combustion cycle of each cylinder 11 and mixing scavenging gas and exhaust gas.

<Supercharger unit>
The supercharger unit 20 is a unit that boosts fresh air taken from the outside and supplies it to the engine body 10. As shown in FIG. 1, the supercharger unit 20 according to this embodiment includes a first supercharger 21 and a second supercharger 22. The first supercharger 21 and the second supercharger 22 are arranged in parallel. That is, fresh air and exhaust gas that have passed through the first supercharger 21 flow without passing through the second supercharger 22, and fresh air and exhaust gas that has passed through the second supercharger 22 1 It flows without passing through the supercharger 21.

  The first supercharger 21 has a first turbine part 23, a first compressor part 24, and a first connecting shaft 25. The exhaust gas generated in each cylinder 11 is collected in the exhaust pipe 13 and then supplied to the first turbine unit 23 through the first exhaust passage 26. The first turbine unit 23 is rotationally driven using the energy of the exhaust gas supplied from the exhaust pipe 13. The exhaust gas that has passed through the first turbine section 23 passes through the first discharge passage 27 and is discharged to the composite boiler 60. On the other hand, the first compressor unit 24 is connected to the first turbine unit 23 via the first connecting shaft 25. Therefore, as the first turbine unit 23 is driven to rotate, the first compressor unit 24 is also driven to rotate. The first compressor unit 24 takes in fresh air from the outside and boosts the pressure. The pressurized fresh air passes through the first scavenging passage 28, is cooled by the air cooler 29, and is then supplied to the scavenging pipe 12.

  The second supercharger 22 has a second turbine part 30, a second compressor part 31, and a second connecting shaft 32. The second turbine unit 30 is supplied with exhaust gas from the exhaust pipe 13 via the second exhaust passage 33. The second turbine unit 30 is driven to rotate using the energy of the exhaust gas supplied from the exhaust pipe 13. The exhaust gas that has passed through the second turbine section 30 is discharged from the second discharge passage 34. The exhaust gas discharged from the second discharge passage 34 merges with the exhaust gas passing through the first discharge passage 27 and is then discharged to the composite boiler 60. On the other hand, the second compressor unit 31 is coupled to the second turbine unit 30 via the second coupling shaft 32 and is rotationally driven as the second turbine unit 30 is rotationally driven. The second compressor unit 31 boosts the fresh air taken from outside. The pressurized fresh air passes through the second scavenging passage 35, merges with fresh air passing through the first scavenging passage 28, is cooled by the air cooler 29, and then supplied to the scavenging pipe 12. The fresh air that has passed through the second scavenging passage 35 may not be merged with the fresh air that has passed through the first scavenging passage 28, and may be supplied to the scavenging pipe 12 through the air cooler 29 alone.

  Further, supercharger control valves 36 to 38 are provided in the second exhaust passage 33, the second discharge passage 34, and the second scavenging passage 35. Opening and closing of the supercharger control valves 36 to 38 is controlled by the control device 70. The timing for opening and closing the supercharger control valves 36 to 38 will be described later. Furthermore, in the supercharger unit 20 of the present embodiment, the capacity of the second supercharger 22 is configured to be about half of the capacity of the first supercharger 21. That is, when the supercharger control valves 36 to 38 are fully opened, about two thirds of the exhaust gas flowing through the entire supercharger unit 20 flows to the first supercharger 21 and about one third is the first. 2 is configured to flow to the supercharger 22.

<EGR unit>
The EGR unit 40 is a unit that recirculates a part of the exhaust gas discharged from the engine body 10 to the engine body 10. By returning the already burned exhaust gas to the engine body 10, the oxygen concentration of the scavenging gas is lowered, and the combustion temperature in the cylinder 11 is lowered. As a result, the amount of NOx discharged from the engine body 10 can be reduced. Hereinafter, the exhaust gas flowing into the EGR unit 40 is referred to as “EGR gas”. As shown in FIG. 1, the EGR unit 40 includes an EGR economizer 41, a scrubber (cleaning device) 42, an EGR gas cooler 43, and an EGR blower 44.

  The EGR economizer 41 is a device that recovers thermal energy of EGR gas. EGR gas is supplied to the EGR economizer 41 from the exhaust pipe 13 via the EGR gas exhaust passage 45. The EGR economizer 41 has an EGR gas pipe 46 inside. The EGR gas pipe 46 is made of a material having a high heat transfer coefficient. The EGR gas supplied to the EGR economizer 41 passes through the EGR gas pipe 46. On the other hand, heated water is supplied into the EGR economizer 41 from a water supply tank (not shown). Thereby, inside the EGR economizer 41, the EGR gas and the water to be heated exchange heat through the EGR gas pipe 46. The water to be heated is heated by the heat of the EGR gas, and part of it is vaporized to become steam. The heated water heated in the EGR economizer 41 and the steam generated by heating the heated water are supplied to the composite boiler 60 via the heated water piping 47.

  The scrubber 42 is a device that cleans EGR gas. The EGR gas contains a large amount of suspended particulate matter such as carbon. If the EGR gas is returned to the engine body 10 without cleaning, suspended particulate matter contained in the EGR gas has an adverse effect on the engine body 10. Therefore, the EGR gas is supplied to the engine body 10 after removing the suspended particulate matter and the like from the EGR gas by the scrubber 42. The scrubber 42 uses wash water to remove suspended particulate matter and the like from the exhaust. Cleaning methods that use cleaning water include a method that allows exhaust to pass through the cleaning water, a method that jets cleaning water into the exhaust, and a method that allows exhaust to pass between members soaked with cleaning water. May be adopted. In the scrubber 42, the cleaning water contains caustic soda for desulfurization so that SOx (sulfur oxide) can also be removed from the EGR gas.

  The EGR gas cooler 43 is a device that cools the EGR gas. One purpose of cooling the EGR gas is to reduce the volume of the EGR gas (increase the density). By reducing the volume of the EGR gas, the power for driving the EGR blower 44 located on the downstream side can be reduced and the EGR blower 44 can be made compact. The EGR gas cooler 43 is located on the downstream side of the EGR economizer 41. Since the EGR gas is cooled by heat exchange with the water to be heated in the EGR economizer 41, the cooling burden on the EGR gas cooler 43 can be reduced by arranging the EGR gas cooler 43 downstream of the EGR economizer 41. it can. In the present embodiment, the EGR gas cooler 43 is disposed downstream of the scrubber 42, but may be disposed upstream of the scrubber 42 or may be disposed on both sides. If the EGR gas cooler 43 is arranged on the downstream side of the scrubber 42, moisture can be taken as condensed water from the EGR gas saturated in the scrubber 42, thereby preventing the condensed water from adhering to the subsequent equipment. Can do. Further, if the EGR gas cooler 43 is arranged on the upstream side of the scrubber 42, the temperature of the EGR gas is lowered, so that the desulfurization reaction in the scrubber 42 is improved.

  The EGR blower 44 is a device that boosts the EGR gas and supplies it to the scavenging pipe 12. Further, the EGR blower 44 can operate together with the EGR control valves 49 and 50 to adjust the flow rate of the EGR gas. The EGR control valves 49 and 50 are provided in the EGR gas exhaust passage 45 on the inlet side and the EGR scavenging passage 48 on the outlet side of the EGR unit 40, respectively. EGR (exhaust gas recirculation) by the EGR unit 40 is not always performed, and also when performing EGR, the EGR rate (exhaust gas exhausted from the engine body 10) according to the operating state of the engine body 10 The ratio of the amount of EGR gas to the amount of gas) is changed. In this embodiment, while changing the rotation speed (output) of the EGR blower 44 and changing the opening degree of the EGR control valves 49 and 50, the EGR is started and stopped, and the EGR rate is adjusted. The EGR blower 44 and the EGR control valves 49 and 50 are controlled by the control device 70.

<Composite boiler>
The composite boiler 60 is a device that generates an arbitrary amount of steam at an arbitrary pressure according to the purpose of use. As shown in FIG. 1, the composite boiler 60 includes an exhaust gas economizer 61, a burner unit 62, and a steam / water separation unit 63.

  The exhaust gas economizer 61 is a device that recovers thermal energy of exhaust gas. The exhaust gas economizer 61 is supplied with the exhaust gas that has passed through the supercharger unit 20. Like the EGR economizer 41, the exhaust gas economizer 61 has an exhaust gas pipe 64 formed of a material having a high heat transfer coefficient. The exhaust gas supplied to the exhaust gas economizer 61 passes through the exhaust gas pipe 64. Further, as described above, heated water and steam are supplied from the EGR economizer 41 to the inside of the exhaust gas economizer 61 in addition to the heated water (boiler water) for the composite boiler 60. Therefore, more steam is supplied from the composite boiler 60 than the steam generated solely by the composite boiler 60. The exhaust gas that has passed through the exhaust gas economizer 61 is guided to the SOx removal device 66 through the exhaust gas discharge passage 65. The SOx removing device 66 is a so-called wet scrubber, and removes SOx from the exhaust gas by injecting a cleaning liquid containing seawater or caustic soda.

  The burner unit 62 is a device that burns fuel and heats the water to be heated with the heat. In FIG. 1, the burner unit 62 is positioned below the water to be heated, but may be positioned near the center of the exhaust gas economizer 61, and the position of the burner unit 62 is not particularly limited. The amount of fuel supplied to the burner unit 62 is adjusted according to the amount of heat recovered by the exhaust gas economizer 61. Specifically, when the pressure or generation amount of the vapor gas is less than a preset value, the fuel supply amount is increased to increase the heat amount, and if it exceeds the preset value, the fuel supply amount is increased. Reduce the amount of heat by reducing or stopping the supply. Thus, the composite boiler 60 can supply the steam according to the intended use stably by having the burner portion 62.

  The steam / water separator 63 is a part that separates liquid (that is, heated water) and gas (that is, steam). The steam separation unit 63 is a space provided above the exhaust gas economizer 61 and in the vicinity of the steam outlet. In the composite boiler 60, the water to be heated and steam exist in a mixed state, but by providing this space, the water to be heated falls by its own weight, and only the steam that does not fall by its own weight is discharged from above this space. The Thus, by providing the space that is the steam separator 63 above the exhaust gas economizer 61, the liquid and the gas can be separated. As described above, the exhaust gas economizer 61 includes steam generated by the EGR economizer 41. Therefore, the steam / water separator 63 separates not only the steam generated in the composite boiler 60 but also the steam generated by the EGR economizer 41 from the heated water.

<Control device>
The control device 70 is a device that controls the entire engine system 100 and includes a CPU, a ROM, a RAM, and the like. The control device 70 controls the EGR blower 44 and the EGR control valves 49 and 50 to adjust the EGR rate and start and stop the EGR as described above, but at the time of starting and stopping the EGR, The supercharger control valve 36 is also controlled. Specifically, when the EGR is started, all the supercharger control valves 36 to 38 are closed, and when the EGR is stopped, all the supercharger control valves 36 to 38 are opened. That is, the control device 70 stops the second supercharger 22 when performing EGR, and drives the second supercharger 22 when not performing EGR. The control device 70 controls in this way for the following reason.

  If the EGR rate when performing EGR is about 30 to 40%, the flow rate of exhaust gas flowing through the entire turbocharger unit 20 when performing EGR is about two-thirds when EGR is not performed. . On the other hand, as described above, in the present embodiment, about two-thirds of the exhaust gas flowing through the entire turbocharger unit 20 flows to the first supercharger 21 and about one-third is the second supercharger. It is configured to flow to the machine 22. Then, if only the second supercharger 22 is stopped when performing EGR, all the exhaust gas flowing to the supercharger unit 20 flows to the first supercharger 21, so that the exhaust gas flowing to the first supercharger 21. The flow rate will not change significantly. Thereby, even if the flow rate of the exhaust gas supplied to the supercharger unit 20 is reduced by performing EGR, the deterioration of the supercharging performance of the first supercharger 21 can be prevented, and fresh air is sufficiently obtained. The pressure can be increased to Therefore, since the maximum combustion pressure can be set high, the deterioration of the fuel consumption of the engine main body 10 is minimized, the temperature of the exhaust gas (EGR gas) discharged from the engine main body 10 can also be suppressed, and the EGR gas cooler 43 is eventually extended. This also contributes to the downsizing of the EGR unit 40 due to the decrease in.

  As described above, according to the present embodiment, the temperature of the exhaust gas discharged from the engine body 10 is lowered. In addition, in the turbocharger unit 20 (first supercharger 21), the exhaust gas is exhausted. Since energy is efficiently used for rotational driving, the temperature of the exhaust gas further decreases. Thereby, the temperature of the exhaust gas discharged from the supercharger unit 20 is lowered, and the temperature of the exhaust gas entering the SOx removing device is also lowered. Since the cleaning liquid for removing SOx has higher desulfurization efficiency as the temperature is lower, according to this embodiment, SOx can be efficiently removed from the exhaust gas.

  The above is the configuration of the engine system 100 according to the present embodiment. In the engine system 100 according to the present embodiment, heated water heated by the EGR economizer 41 and steam generated by heating the heated water are supplied to the composite boiler 60. The steam generated by the EGR economizer 41 is separated from the water to be heated by the composite boiler 60. That is, the heated water heated by the EGR economizer 41 and the steam generated by heating the heated water are supplied to a separately provided composite boiler 60 and processed into a usable state. Therefore, it is not necessary to provide an auxiliary boiler and a steam / water separator in the EGR unit 40 or newly provide a composite boiler. Therefore, according to the engine system 100 according to the present embodiment, the EGR unit 40 can be configured in a compact manner.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. FIG. 2 is a block diagram of an engine system 200 according to the second embodiment. As shown in FIG. 2, in the engine system 200 according to this embodiment, the supercharger unit 20 does not include the second supercharger 22, while the first supercharger 21 is at the inlet of the first turbine unit 23. The configuration is different from the engine system 100 according to the first embodiment in that the variable nozzle 39 is provided. The opening area of the variable nozzle 39 of the present embodiment is controlled by the control device 70. Specifically, the control device 70 reduces the opening area of the variable nozzle 39 when performing EGR, and increases the opening area of the variable nozzle 39 when not performing EGR. Thereby, also when performing EGR, the deterioration of the supercharging performance in the 1st supercharger 21 can be reduced. The variable nozzle 39 may be a continuously variable nozzle that smoothly changes the opening area, or may be a two-stage variable nozzle that selectively switches the opening area. According to the engine system 200 according to this embodiment, compared with the case of the first embodiment, the cost can be reduced and the space can be saved because the second supercharger 22 is not provided.

(Third embodiment)
Next, a third embodiment of the present invention will be described. FIG. 3 is a block diagram of an engine system 300 according to the third embodiment. As shown in FIG. 3, the engine system 300 according to the present embodiment is an engine system according to the first embodiment in that the first supercharger 21 has a variable nozzle 39 at the inlet of the first turbine unit 23. 100 and the configuration is different. The opening area of the variable nozzle 39 is controlled by the control device 70. In the case of this embodiment, as in the case of the first embodiment, when performing EGR, the second supercharger 22 is stopped, and further, according to the flow rate of the exhaust gas flowing into the supercharger unit 20, The opening area of the variable nozzle 39 is adjusted so that the efficiency of the first supercharger 21 is improved. According to such a configuration, the scavenging pressure can be further increased and the combustion pressure can be further increased as compared with the first embodiment, and the fuel consumption of the engine body 10 can be further improved.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described. FIG. 4 is a block diagram of an engine system 400 according to the fourth embodiment. As shown in FIG. 4, the engine system 400 according to the present embodiment has the same configuration as the engine system 100 according to the first embodiment in that it includes a bypass pipe 52 that guides the EGR gas that has passed through the EGR economizer 41 to the composite boiler 60. Different.

  One end side of the bypass pipe 52 is connected to an EGR economizer outlet pipe 51 located on the outlet side of the EGR economizer 41. The EGR economizer outlet pipe 51 is provided with an on-off valve 53 that is controlled to open and close by the control device 70. The on-off valve 53 is located downstream of the portion of the EGR economizer outlet pipe 51 to which the bypass pipe 52 is connected. Further, the other end side of the bypass pipe 52 is connected to the first discharge passage 27. The connection portion between the bypass pipe 52 and the first discharge passage 27 is located downstream of the connection portion between the second discharge passage 34 and the first discharge passage 27. Further, the bypass pipe 52 is provided with an open / close valve 54 that is controlled to open and close by the control device 70.

  The on-off valve 53 provided in the EGR economizer outlet pipe 51 is opened while EGR is being performed, and is closed while EGR is not being performed. Further, the on-off valve 54 provided in the bypass pipe 52 is closed while EGR is being performed, and is opened while EGR is not being performed. In the case of the present embodiment, the exhaust gas flowing into the EGR unit 40 is adjusted by adjusting the opening of the EGR control valve 49 located on the inlet side of the EGR unit 40 regardless of whether or not EGR is performed. The amount of (EGR gas) is controlled. By controlling each valve in this way, all the exhaust gas that has passed through the EGR economizer 41 is supplied to the scrubber 42 while EGR is being performed, and the EGR economizer 41 is being operated while EGR is not being performed. All exhaust gas that has passed through is supplied to the composite boiler 60.

  Here, for example, when the ship 101 navigates in a sea area where there is no emission restriction such as NOx, EGR is not performed, and both the first supercharger 21 and the second supercharger 22 operate. At this time, since the engine body 10 can be operated efficiently under optimum conditions in the high load region, the temperature of the exhaust gas discharged from the engine body 10 tends to be low, and as a result, the amount of steam generated by the composite boiler 60 is small. There is a risk. On the other hand, the engine system 400 according to the present embodiment allows a small amount of scavenging gas to flow to the EGR unit 40 so that the scavenging air pressure is equal to or higher than the lower limit even when EGR is not performed. Steam can be generated by the EGR economizer 41 using energy. Therefore, it is possible to make up for insufficient steam while suppressing fuel consumption by the burner unit 62. Furthermore, in this embodiment, since the EGR gas that has passed through the EGR economizer 41 is supplied to the composite boiler 60, it is efficient because the thermal energy of the EGR gas can be recovered again.

  In the present embodiment, the case where the efficiency of the engine body 10 is improved by using the two superchargers 21 and 22 is described. However, the engine system 200 according to the second embodiment and the third embodiment are related. Similarly, when the turbocharger has a variable nozzle as in the engine system 300, the temperature of the exhaust gas discharged can be lowered as the efficiency of the engine body 10 is improved. Therefore, also in the engine system 200 according to the second embodiment and the engine system 300 according to the third embodiment, the EGR gas that has passed through the EGR economizer 41 can be guided to the composite boiler 60 as in the present embodiment. It is beneficial.

  As described above, the embodiments of the present invention have been described with reference to the drawings. However, the specific configuration is not limited to these embodiments, and even if there is a design change or the like without departing from the gist of the present invention. It is included in the present invention. For example, in the above description, exhaust gas that has not passed through the supercharger unit 20 is taken into the EGR unit 40. However, even if the exhaust gas that has passed through the supercharger unit 20 is taken into the EGR unit 40, Included in the invention.

  Moreover, although the installation place of the composite boiler 60 and the SOx removal apparatus 66 is not specifically limited above, it may be arrange | positioned in the vicinity of the engine main body 10, and may be arrange | positioned at the hull side. That is, even if the composite boiler and the SOx removing device are arranged away from other components, the engine system is configured as a whole, and thus such an engine system is also included in the present invention.

  Furthermore, although the case where the engine systems 100, 200, 300, and 400 are mounted on the ship 101 has been described above, the present invention is not limited to this. For example, the engine system is for power generation installed on land. Even if it exists, it is included in this invention.

  The engine system according to the present invention can provide an engine system in which the EGR unit is relatively compact while the exhaust gas economizer is provided in the EGR unit. Therefore, it is useful in the technical field of engine systems.

DESCRIPTION OF SYMBOLS 10 Engine main body 20 Supercharger unit 21 1st supercharger 22 2nd supercharger 37 Variable nozzle 40 EGR unit 41 EGR economizer 42 Cleaning dust collector 43 EGR gas cooler 60 Composite boiler 61 Exhaust gas economizer 62 Burner part 63 Air Water separation unit 66 SOx removal device 100, 200, 300, 400 Engine system 101 Ship

Claims (9)

The engine body,
A turbocharger unit driven by exhaust gas;
An EGR unit for recirculating a part of the exhaust gas as EGR gas to the engine body;
A composite boiler that is disposed downstream of the supercharger unit, has an exhaust gas economizer inside, and is capable of separating air and water;
The EGR unit has an EGR economizer that heats water to be heated with EGR gas,
The heated water heated by the EGR economizer and the steam generated by heating the heated water are supplied to the composite boiler, and the heated water and steam are separated by the composite boiler. The engine system that is configured. The EGR unit has an EGR gas cooler that cools EGR gas,
The engine system according to claim 1, wherein the EGR economizer is disposed upstream of the EGR gas cooler. The EGR unit further includes a scrubber that removes dust of EGR gas with a cleaning liquid,
The engine system according to claim 2, wherein the EGR gas cooler is disposed downstream of the scrubber. The supercharger unit has a first supercharger and a second supercharger arranged in parallel with the first supercharger,
The engine according to any one of claims 1 to 3, wherein the second supercharger is configured to be stopped when the EGR unit recirculates the EGR gas to the engine body. system.   The engine system according to claim 4, wherein the first supercharger is provided with a variable nozzle at an inlet of a turbine section. The supercharger unit has a first supercharger provided with a variable nozzle at the turbine section inlet,
The engine system according to any one of claims 1 to 3, wherein when the EGR gas is recirculated to the engine body, an opening area of the variable nozzle is reduced. A SOx removal device that removes SOx from the exhaust gas using cleaning water;
The engine system according to any one of claims 4 to 6, wherein the SOx removing device is disposed downstream of the supercharger unit. The engine system according to any one of claims 1 to 7, wherein the engine system is configured to supply EGR gas that has passed through the EGR economizer to the composite boiler.   A ship provided with the engine system according to any one of claims 1 to 8.

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