JP2014001675A - Prime mover system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently recover waste heat from pressurized intake air.SOLUTION: A prime mover system 1 comprises: a prime mover 3; a supercharger 4; a first heat exchanger 5; and a waste heat recovery device 6. The supercharger 4 comprises a turbine 41, and a compressor 42. The prime mover 3 and the supercharger 4 are connected to each other by a scavenging passage 31 and an exhaust passage 32. The exhaust passage 32 comprises: a main exhaust passage 321 for introducing exhaust air from the prime mover 3 to the turbine 41; and a branch exhaust passage 322 branched from the main exhaust passage 321. Branch exhaust air that is one part of the exhaust from the prime mover 3 flow through the branch exhaust passage 322. The first heat exchanger 5 is provided on the branch exhaust passage 322 and the scavenging passage 31. The first heat exchanger 5 is a plate-type heat exchanger for gas-gas, and heats scavenging air flowing through the scavenging passage 31 with the branch exhaust air as a heat source. Thereby, a scavenging temperature becomes high, so that waste heat can be efficiently recovered from the scavenging air by the waste heat recovery device 6 and recovery power can be made large.

Description

  The present invention relates to a prime mover system.

  Conventionally, a technique for recovering energy from waste heat of a prime mover using a Rankine cycle is known. For example, in Patent Document 1, exhaust heat of an internal combustion engine is recovered by a heat medium having a boiling point higher than that of water, the heat medium and the organic fluid are heat-exchanged to evaporate the organic fluid, and the evaporated organic fluid is used as a turbine. An exhaust heat recovery power generation device that generates electricity by driving a power source is disclosed.

JP 2011-149332 A

  By the way, in a prime mover system equipped with a prime mover with a supercharger, it is conceivable to recover waste heat from the intake air pressurized by the supercharger (pressurized intake air), but if the output of the prime mover is low, Since the temperature of the pressurized intake air supplied to the prime mover is also low, the energy recovered from the waste heat of the pressurized intake air is reduced.

  The present invention has been made in view of the above problems, and an object of the present invention is to efficiently recover waste heat from pressurized intake air.

  The invention according to claim 1 is a prime mover system, comprising a prime mover, a supercharger that pressurizes intake air and supplies the prime mover to the prime mover, and a pressurized intake air that is pressurized by the supercharger. A pressurized intake passage that is a flow path that leads to the prime mover, an exhaust passage that guides exhaust from the prime mover to the supercharger, and the pressurized intake passage that is provided on the pressurized intake flow path and uses the exhaust as a heat source. The first heat exchanger that heats the pressurized intake air flowing through the intake passage, and the pressurization that is disposed between the first heat exchanger and the prime mover on the pressurized intake passage and flows through the pressurized intake passage. A second heat exchanger that heats and vaporizes the working fluid using the intake air as a heat source; an expander that expands the working fluid vaporized in the second heat exchanger to recover mechanical energy; and the expander A condenser for condensing and liquefying the working fluid expanded in The liquefied the working fluid at the vessel and a pump for sending to the second heat exchanger.

  Invention of Claim 2 is a motor | power_engine system of Claim 1, Comprising: The said exhaust path branches from the main exhaust path which connects the said prime mover and the said supercharger, and the said main exhaust path, A branch exhaust passage through which a part of the exhaust from the prime mover flows, wherein the heat source of the first heat exchanger is exhaust flowing through the branch exhaust passage, and the prime mover system flows through the branch exhaust passage The exhaust flow rate adjustment unit that adjusts the flow rate of the exhaust gas, the thermal load acquisition unit that acquires the thermal load in the second heat exchanger, and the exhaust flow rate adjustment unit that is controlled based on the output from the thermal load acquisition unit And an exhaust flow rate controller.

  Invention of Claim 3 is a motor | power_engine system of Claim 2, Comprising: The said thermal load acquisition part acquires the said thermal load based on the rotation speed of the said motor | power_engine.

  Invention of Claim 4 is a motor | power_engine system in any one of Claim 1 thru | or 3, Comprising: The said expander is a turbine rotated with the said working fluid vaporized in the said 2nd heat exchanger. is there.

  The invention according to claim 5 is the prime mover system according to any one of claims 1 to 4, which is a main engine system of a ship.

  In the present invention, waste heat can be efficiently recovered from pressurized intake air.

It is a figure which shows the structure of the motor | power_engine system which concerns on one embodiment. It is a figure which shows the relationship between the recovery motive power and scavenging temperature in a waste heat recovery apparatus. It is a figure which shows the relationship between the motor | power_engine load and scavenging temperature in the motor | power_engine system of a comparative example. It is a figure which shows the relationship between a motor | power_engine load and collection | recovery motive power.

  FIG. 1 is a diagram showing a configuration of a prime mover system 1 according to a first embodiment of the present invention. The prime mover system 1 is used as a main engine system of a ship. The motor system 1 includes a motor 2 with a supercharger, a first heat exchanger 5, and a waste heat recovery device 6 that recovers waste heat of the motor 2 with a supercharger.

  The supercharger-equipped prime mover 2 includes a marine prime mover 3 that is a two-stroke engine (hereinafter simply referred to as “prime mover 3”) and a turbocharger 4 that is a turbocharger. The supercharger 4 includes a turbine 41 and a compressor 42 that is mechanically connected to the turbine 41. The prime mover 3 and the supercharger 4 are connected by a scavenging path 31 and an exhaust path 32.

  The exhaust path 32 guides the exhaust from the prime mover 3 to the turbine 41 of the supercharger 4. The turbine 41 is rotated by the exhaust gas supplied through the exhaust passage 32. Exhaust gas used for the rotation of the turbine 41 is discharged outside the prime mover system 1. The compressor 42 uses the rotational force generated in the turbine 41 (that is, using the rotation of the turbine 41 as power), and intake air (air) guided to the supercharger 4 from the outside of the prime mover system 1 through the intake passage 43. And press to compress. Pressurized intake air (hereinafter referred to as “scavenging”) that is the intake air pressurized by the compressor 42 is supplied to the prime mover 3 via the scavenging passage 31. Thus, in the supercharger 4, the intake air is pressurized using the exhaust gas, and scavenging is generated. The scavenging passage 31 is a pressurized intake passage that is a passage that guides the pressurized intake air from the supercharger 4 to the prime mover 3.

  The exhaust path 32 includes a main exhaust path 321 and a branch exhaust path 322. The main exhaust path 321 connects the prime mover 3 and the turbine 41 of the supercharger 4. The branch exhaust passage 322 branches from the main exhaust passage 321 at the branch portion 324 in the vicinity of the prime mover 3, and rejoins the main exhaust passage 321 at the merge portion 325 in the vicinity of the turbine 41. At least a part of the exhaust from the prime mover 3 (hereinafter referred to as “branch exhaust”) flows through the branch exhaust path 322. The branch exhaust passes through the branch exhaust passage 322 and is then guided to the turbine 41 through the main exhaust passage 321.

  A control valve 323 is provided on the branch exhaust path 322. The control valve 323 is an exhaust flow rate adjusting unit that adjusts the flow rate of the branch exhaust flowing through the branch exhaust path 322. The flow rate of the branch exhaust gas is controlled by controlling the opening degree of the control valve 323 by the exhaust gas flow rate control unit 72. When the control valve 323 is closed, no exhaust flows through the branch exhaust passage 322, and the entire amount of exhaust from the prime mover 3 is guided to the turbine 41 via the main exhaust passage 321.

  The first heat exchanger 5 is provided on the branch exhaust path 322 and the scavenging path 31. On the branch exhaust path 322, the first heat exchanger 5 is disposed between the control valve 323 and the junction 325. The first heat exchanger 5 is a gas-gas plate heat exchanger, and heats the scavenging gas flowing through the scavenging passage 31 using the branch exhaust as a heat source.

  The waste heat recovery apparatus 6 includes a pipe 61 through which a working fluid flows, a second heat exchanger 62, an expander 63, a condenser 64, and a pump 65. The second heat exchanger 62, the expander 63, the condenser 64 and the pump 65 are connected by a pipe 61. Various fluids may be used as the working fluid. In this embodiment, an organic medium such as an alternative chlorofluorocarbon such as R245fa is used as the working fluid, and the waste heat recovery apparatus 6 uses a so-called organic Rankine cycle (ORC). : Organic Rankine Cycle).

  The second heat exchanger 62 is disposed between the first heat exchanger 5 and the prime mover 3 on the scavenging path 31 that is a flow path that guides the scavenging air to the prime mover 3, and uses the scavenged gas flowing through the scavenging path 31 as a heat source. The working fluid is heated and vaporized. On the other hand, the scavenging gas in the scavenging passage 31 is guided to the prime mover 3 after being cooled by the working fluid in the second heat exchanger 62. In other words, the second heat exchanger 62 is a so-called intercooler that cools the scavenged air.

  The expander 63 expands the working fluid vaporized by the second heat exchanger 62 and recovers mechanical energy. In the present embodiment, a turbine that is rotated by the working fluid vaporized in the second heat exchanger 62 is used as the expander 63. The shaft of the turbine is connected to the generator 8, and the turbine is driven by the saturated steam of the working fluid sent from the second heat exchanger 62 through the pipe 61, thereby generating power in the generator 8. . The condenser 64 condenses and liquefies the working fluid expanded by the expander 63. The pump 65 is a booster pump that sends the working fluid liquefied by the condenser 64 to the second heat exchanger 62 while pressurizing the working fluid.

  The heat load acquisition unit 71 acquires the heat load in the second heat exchanger 62. The acquisition of the thermal load by the thermal load acquisition unit 71 is performed based on the rotation speed of the prime mover 3. Specifically, the temperature and flow rate of the scavenging gas supplied from the compressor 42 to the scavenging passage 31 is obtained based on the number of revolutions of the prime mover 3, and considering the heating of the scavenging gas by the first heat exchanger 5, 2 The temperature and flow rate of the scavenging gas supplied to the heat exchanger 62 are obtained. Then, the heat load in the second heat exchanger 62 is acquired based on the temperature and flow rate of the scavenging gas supplied to the second heat exchanger 62.

  FIG. 2 is a diagram showing the relationship between the amount of power generated by the generator 8 (hereinafter referred to as “recovered power”) in the waste heat recovery apparatus 6 and the scavenging temperature. The horizontal axis of FIG. 2 indicates the scavenging temperature (° C.), and the vertical axis indicates the ratio of the recovery power at each scavenging temperature to the recovery power when the scavenging temperature is 213 ° C. As shown in FIG. 2, the recovery power by the waste heat recovery device 6 increases when the scavenging temperature increases, and the recovery power decreases when the scavenging temperature decreases.

  FIG. 3 is a diagram showing the relationship between the prime mover load and the scavenging temperature in a prime mover system (hereinafter referred to as “comparative example prime mover system”) in which the first heat exchanger and the branch exhaust passage are not provided. The horizontal axis of FIG. 3 shows the prime mover load (%), and the vertical axis shows the ratio of the scavenging temperature at each prime mover load to the scavenging temperature when the prime mover load is 80%. As shown in FIG. 3, in the prime mover system of the comparative example, the scavenging temperature greatly decreases as the prime mover load decreases. In other words, as the prime mover load decreases, the heat load in the second heat exchanger of the waste heat recovery apparatus greatly decreases.

  FIG. 4 is a diagram showing the relationship between the prime mover load and the recovered power. The horizontal axis of FIG. 4 indicates the prime mover load (%), and the vertical axis indicates the ratio of the recovered power at each prime mover load to the recovered power when the prime mover load is 80%. In the prime mover system of the comparative example, the heat load in the second heat exchanger is greatly reduced as described above as the prime mover load is reduced. Therefore, as shown by the broken line 91 in FIG. Is also greatly reduced.

  On the other hand, in the prime mover system 1 according to the present embodiment, the scavenging air is heated using the branch exhaust as a heat source by the first heat exchanger 5 provided on the branch exhaust passage 322 and the scavenging passage 31. The scavenging temperature is higher than the prime mover system. Thereby, compared with the motor | power_engine system of a comparative example, waste heat can be efficiently collect | recovered from scavenging by the waste heat recovery apparatus 6, and recovery power can be enlarged.

  In the prime mover system 1, based on the thermal load in the second heat exchanger 62 acquired by the thermal load acquisition unit 71 (that is, based on the output from the thermal load acquisition unit 71), the exhaust flow rate control unit 72 adjusts the control valve. 323 is controlled, and heating of the scavenging gas in the first heat exchanger 5 is controlled. Thereby, the heat load in the 2nd heat exchanger 62 and the recovery power by the waste heat recovery apparatus 6 can be controlled easily.

  In the prime mover system 1, for example, only when the output of the prime mover 3 is less than the normal output (in this embodiment, when the prime mover load is less than 80%), the first heat exchanger 5 is branched via the branch exhaust passage 322. Exhaust is supplied. Then, by controlling the flow rate of the branch exhaust gas by the exhaust flow rate control unit 72, the scavenging temperature between the first heat exchanger 5 and the second heat exchanger 62 is made approximately equal to the scavenging temperature at the normal output. The As a result, as shown by the solid line 92 in FIG. 4, when the output of the prime mover 3 is less than the normal output, the waste heat is efficiently recovered from the scavenging and the recovery power is increased compared to the prime mover system of the comparative example. can do. When the output of the prime mover 3 is equal to or higher than the normal output, the exhaust from the prime mover 3 is cooled in the first heat exchanger 5 by stopping the supply of branch exhaust to the first heat exchanger 5. Without being supplied to the turbine 41. As a result, the intake air can be efficiently compressed in the compressor 42.

  It should be noted that the output of the prime mover 3 which is a reference for the presence or absence of the supply of branch exhaust to the first heat exchanger 5 is not necessarily limited to the normal output, and branch exhaust is generated when the output of the prime mover 3 is less than a predetermined threshold output. The scavenging gas is heated by being supplied to the first heat exchanger 5, and the supply of branch exhaust to the first heat exchanger 5 may be stopped when the output is equal to or higher than the threshold output. Further, branch exhaust may be supplied to the first heat exchanger 5 in the entire range of the output of the prime mover 3.

  In the prime mover system 1, the branch exhaust flowing through the branch exhaust path 322 is guided to the turbine 41 after passing through the first heat exchanger 5. Thus, the efficiency of the prime mover system 1 can be further improved by using the exhaust after being used for heating the scavenging gas for driving the supercharger 4.

  In the prime mover system 1, as described above, branch exhaust is supplied to the first heat exchanger 5 and the scavenging gas is heated, thereby efficiently recovering the waste heat of the scavenging gas over a wide range of the prime load. Can do. Therefore, the prime mover system 1 is particularly suitable for a marine main engine system in which the prime mover 3 is operated at a low load at a relatively high frequency.

  The thermal load acquisition unit 71 can easily acquire the thermal load in the second heat exchanger 62 based on the rotational speed of the prime mover 3. Further, since the expander 63 is a turbine rotated by the working fluid vaporized by the second heat exchanger 62, the structure of the waste heat recovery device 6 is particularly suitable for a prime mover system that recovers relatively large waste heat. ing.

  As mentioned above, although embodiment of this invention has been described, this invention is not limited to the said embodiment, A various change is possible.

  For example, the branch exhaust path 322 may be directly connected to the turbine 41 after passing through the first heat exchanger 5. In this case, the branch exhaust is directly supplied to the turbine 41 without passing through the main exhaust path 321. Further, the branch exhaust passage 322 may not be connected to the main exhaust passage 321 and the turbine 41 after passing through the first heat exchanger 5. In this case, the branch exhaust is discharged outside the prime mover system 1 without passing through the turbine 41.

  In the waste heat recovery apparatus 6, the expander 63 is not limited to the turbine, and for example, an expansion valve may be used as the expander 63. The expander 63 does not necessarily need to be connected to the generator 8, and the output from the expander 63 may be used for various purposes in a ship in which the prime mover system 1 is disposed. Moreover, the working fluid of the waste heat recovery apparatus 6 is not limited to an organic medium.

  In the prime mover system 1, a sensor for measuring the temperature and flow rate of the scavenging gas is provided between the first heat exchanger 5 and the second heat exchanger 62 in the scavenging passage 31, and the second is based on the output from the sensor. The heat load of the heat exchanger 62 may be acquired. In addition, the heat load of the second heat exchanger 62 is not necessarily acquired, and the control valve 323 is controlled based on the number of revolutions of the prime mover 3 by the exhaust flow rate control unit 72, whereby the first heat exchanger 5 is controlled. The flow rate of the branch exhaust supplied to the engine may be controlled. In the prime mover system 1, the flow rate of the branch exhaust flowing through the branch exhaust path 322 may be constant regardless of the rotational speed of the prime mover 3.

  In the prime mover system 1, if the scavenging temperature becomes higher than that of the prime mover system of the comparative example by supplying the branch exhaust to the first heat exchanger 5, the scavenging temperature is not necessarily equal to the scavenging temperature at the normal output. There is no need to be done.

  In the prime mover system 1, when the output of the prime mover 3 is relatively low, the entire amount of exhaust from the prime mover 3 may be supplied to the branch exhaust path 322 as branch exhaust. In this case, the adjustment valve 323 is provided in the branch portion 324. Further, the branch exhaust path 322 is not necessarily provided, and the first heat exchanger 5 is provided on the main exhaust path 321 and the scavenging path 31, and the total amount of exhaust from the prime mover 3 is always in the first heat exchanger 5. It may be supplied and used for heating scavenging.

  Between the 2nd heat exchanger 62 and the motor | power_engine 3 of the scavenging path 31, the cooling device which cools scavenging with seawater etc. may be provided. Thereby, scavenging is further cooled and the efficiency of the prime mover 3 can be improved. Further, even when the waste heat recovery apparatus 6 is stopped due to maintenance or the like, the scavenging can be cooled.

  The prime mover 3 is not necessarily a two-stroke engine, and a four-stroke engine may be used as the prime mover 3. In this case as well, the waste heat can be efficiently recovered by the waste heat recovery device 6 from the supply air that is pressurized by the supercharger 4 and the recovery power can be increased, as in the above embodiment. . The prime mover system 1 may be used for applications other than the main engine system of a ship, and the prime mover with a supercharger 2 is not limited to a marine prime mover.

  The configurations in the above embodiment and each modification may be combined as appropriate as long as they do not contradict each other.

1 prime mover system 3 prime mover 4 supercharger 5 first heat exchanger 31 scavenging path 32 exhaust path 62 second heat exchanger 63 expander 64 condenser 65 pump 71 heat load acquisition unit 72 exhaust flow rate control unit 321 main exhaust path 322 Branch exhaust passage 323 Control valve

Claims (5)

A prime mover system,
Prime mover,
A supercharger that pressurizes intake air and supplies it to the prime mover;
A pressurized intake passage that is a flow path that guides the pressurized intake air that has been pressurized by the supercharger to the prime mover;
An exhaust path for guiding exhaust from the prime mover to the supercharger;
A first heat exchanger that is provided on the pressurized intake passage and heats the pressurized intake air flowing through the pressurized intake passage using the exhaust as a heat source;
A second heat exchanger disposed between the first heat exchanger and the prime mover on the pressurized intake passage and configured to heat and vaporize a working fluid using the pressurized intake air flowing through the pressurized intake passage as a heat source; ,
An expander for recovering mechanical energy by expanding the working fluid vaporized in the second heat exchanger;
A condenser that condenses and liquefies the working fluid expanded by the expander;
A pump for delivering the working fluid liquefied in the condenser to the second heat exchanger;
A prime mover system comprising: The prime mover system according to claim 1,
The exhaust path is
A main exhaust passage connecting the prime mover and the supercharger;
A branched exhaust passage that branches off from the main exhaust passage and through which a part of the exhaust from the prime mover flows;
With
The heat source of the first heat exchanger is exhaust flowing through the branch exhaust path;
The prime mover system is
An exhaust flow rate adjusting unit for adjusting the flow rate of the exhaust gas flowing through the branch exhaust path;
A heat load acquisition unit for acquiring a heat load in the second heat exchanger;
An exhaust flow rate control unit that controls the exhaust flow rate adjustment unit based on an output from the thermal load acquisition unit;
A prime mover system characterized by further comprising: The prime mover system according to claim 2,
The prime mover system, wherein the thermal load acquisition unit acquires the thermal load based on a rotational speed of the prime mover. The prime mover system according to any one of claims 1 to 3,
The prime mover system, wherein the expander is a turbine rotated by the working fluid vaporized in the second heat exchanger. The prime mover system according to any one of claims 1 to 4,
A prime mover system characterized by being a main engine system of a ship.

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