JP2016142223A - Exhaust heat recovery device, exhaust heat recovery type ship propulsion device and exhaust heat recovery method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recover heat quantity of cooling water whose temperature has increased, as effective energy.SOLUTION: A exhaust heat recovery type ship propulsion device 1 includes: a cooling water circulation flow passage 6 configured to circulate first cooling water for cooling a Diesel engine 3; an ORC (Organic Rankine Cycle) system 2 configured to recover exhaust heat from the first cooling water circulating in the cooling water circulation flow passage 6, and perform power generation with the exhaust heat; and a control device 9 configured to control the ORC system 2 so that heat quantity recovered by the ORC system 2 is increased as the rotational frequency of the Diesel engine 3 increases.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an exhaust heat recovery device that recovers exhaust heat from an internal combustion engine, an exhaust heat recovery type ship propulsion device, and an exhaust heat recovery method.

2. Description of the Related Art Conventionally, an exhaust heat recovery device that recovers exhaust heat of a diesel engine of a ship and generates electric power is known (for example, see Patent Document 1).
The exhaust heat recovery device disclosed in Patent Document 1 guides jacket cooling water discharged from a diesel engine to an evaporator, and guides a working fluid evaporated in the evaporator by heat exchange with the jacket cooling water to a power turbine. . Then, the power turbine is rotated by the evaporated working fluid, and the rotational power of the power turbine is transmitted to the generator accordingly. The jacket cooling water exchanged with the working fluid is supplied to the diesel engine and is used again to cool the diesel engine.

  In the exhaust heat recovery device disclosed in Patent Document 1, when the temperature of the jacket cooling water discharged from the diesel engine is higher than a set value, a relatively low temperature fresh water is often supplied to the circulation passage for circulating the jacket cooling water. Operate the three-way valve for temperature adjustment to flow. Thereby, it adjusts so that the temperature of the jacket cooling water discharged | emitted from a diesel engine may not exceed a setting value. The temperature of the jacket cooling water is adjusted in this way in order to maintain the temperature of the jacket cooling water discharged from the diesel engine at a temperature suitable for a fresh water generator that creates fresh water using the heat. It is.

JP 2012-215124 A

However, since the exhaust heat recovery device disclosed in Patent Document 1 reduces the temperature of the jacket cooling water by heat exchange with relatively cool water, the amount of heat that the jacket cooling water discharged from the diesel engine has is effective. It could not be recovered as energy.
In particular, when the load on the diesel engine increases, the temperature of the jacket cooling water discharged from the diesel engine rises, but the amount of heat that increases due to this temperature rise is discarded and can be recovered as effective energy. There wasn't.

For example, in the exhaust heat recovery apparatus disclosed in Patent Document 1, the temperature of the jacket cooling water supplied to the diesel engine decreases by increasing the amount of exhaust heat recovery from the jacket cooling water discharged from the diesel engine. . Thereby, the temperature of the jacket cooling water discharged from the diesel engine decreases, and the amount of heat discarded from the jacket cooling water decreases.
However, if the amount of exhaust heat recovery is increased too much, the temperature of the jacket cooling water discharged from the diesel engine becomes lower than the set value, and the temperature of the jacket cooling water discharged from the diesel engine cannot be maintained at the set value. .

  The present invention has been made to solve the above-described problem, and when the temperature of the cooling water for cooling the internal combustion engine rises as the load of the internal combustion engine increases, the cooling water whose temperature has risen. It is an object of the present invention to provide an exhaust heat recovery device, an exhaust heat recovery type ship propulsion device, and an exhaust heat recovery method capable of recovering heat as effective energy.

The present invention employs the following means in order to solve the above problems.
An exhaust heat recovery apparatus according to an aspect of the present invention circulates a cooling water circulation passage for circulating first cooling water for cooling an internal combustion engine from a cooling water outlet to a cooling water inlet of the internal combustion engine, and the cooling water circulation passage. The exhaust heat recovery unit that recovers exhaust heat from the first cooling water and generates power using the exhaust heat, and the amount of heat recovered by the exhaust heat recovery unit as the load of the internal combustion engine increases. And a control unit that controls the exhaust heat recovery unit so as to increase.

  In the exhaust heat recovery apparatus according to an aspect of the present invention, the amount of heat recovered by the exhaust heat recovery unit is increased as the load of the internal combustion engine increases. In this way, when the temperature of the cooling water for cooling the internal combustion engine rises as the load on the internal combustion engine increases, the amount of heat of the cooling water whose temperature has risen can be recovered as effective energy. it can.

  In the exhaust heat recovery apparatus according to an aspect of the present invention, the exhaust heat recovery unit includes an evaporator that exchanges heat between the cooling water circulating in the cooling water circulation passage and the working fluid to evaporate the working fluid; A turbine rotated by the working fluid evaporated by the evaporator, a generator for generating electric power by the rotational power of the turbine, a condenser for condensing the working fluid discharged from the turbine, and the working fluid. A circulating pump that circulates, and the controller controls the circulating pump to increase a discharge amount per unit time of the working fluid discharged by the circulating pump in accordance with an increase in a load of the internal combustion engine. The structure to control may be sufficient.

According to the exhaust heat recovery apparatus of this configuration, the working fluid is evaporated by heat exchange with the first cooling water, the turbine is rotated by the evaporated working fluid, and the working fluid discharged from the turbine is condensed, The condensed working fluid is circulated by a circulation pump. The circulation pump is controlled so that the discharge amount of the working fluid discharged per unit time increases as the load of the internal combustion engine increases.
By doing in this way, when the load of an internal combustion engine increases, the amount of heat which an evaporator collects from the 1st cooling water by heat exchange can be increased.

  In the exhaust heat recovery apparatus according to an aspect of the present invention, the cooling water circulation channel on the downstream side of the cooling water outlet and on the upstream side of the exhaust heat recovery unit from the cooling water circulation channel on the upstream side of the cooling water inlet. A cooling water bypass flow path for bypassing the first cooling water, a supercharger that is driven by exhaust gas discharged from the internal combustion engine, compresses the air, and supplies the compressed air to the internal combustion engine, An air cooler that cools the combustion air supplied from the supercharger to the internal combustion engine with the cooling water that flows through the cooling water bypass passage may be provided.

According to the exhaust heat recovery apparatus of this configuration, the supercharger is driven by the exhaust gas discharged from the internal combustion engine. A supercharger driven by exhaust gas compresses air and supplies it to the internal combustion engine as combustion air. Although the temperature of combustion air increases due to compression, it is cooled by the first cooling water flowing through the cooling water bypass passage. Therefore, the heat quantity of the combustion air is recovered by the first cooling water. The amount of heat of the first cooling water is further recovered by the exhaust heat recovery unit.
As described above, according to this configuration, the load on the internal combustion engine can be increased by the supercharger, and the amount of heat of the combustion air heated by the compression can be appropriately recovered by the exhaust heat recovery unit.

In the exhaust heat recovery apparatus according to one aspect of the present invention, the control unit controls the exhaust heat recovery unit to reduce the amount of heat recovered by the exhaust heat recovery unit in response to a decrease in the load of the internal combustion engine. It may be configured to.
According to this configuration, as the load of the internal combustion engine decreases, the amount of heat of the first cooling water recovered by the exhaust heat recovery unit decreases, and accordingly, the first cooling water guided to the cooling water inlet. The temperature rises. Moreover, the temperature of the 1st cooling water guide | induced to a cooling water inlet increases, and the temperature of the 1st cooling water discharged | emitted from a cooling water outlet rises in connection with it. Therefore, the temperature of the 1st cooling water discharged | emitted from a cooling water exit can be prevented from falling.

When the temperature of the first cooling water discharged from the cooling water outlet is higher than a target temperature, the exhaust heat recovery apparatus according to one aspect of the present invention supplies the second cooling water having a temperature lower than that of the first cooling water. The structure provided with the temperature adjustment part which guides to the said cooling water circulation flow path upstream from a cooling water inlet and reduces the temperature of a said 1st cooling water may be sufficient.
According to the exhaust heat recovery apparatus of this configuration, when the first cooling water discharged from the cooling water outlet is higher than the target temperature, the second cooling water having a temperature lower than that of the first cooling water is led upstream of the cooling water inlet. Then, the temperature adjustment unit adjusts the temperature of the first cooling water to be lowered. In this case, the amount of heat discarded increases as the flow rate of the second cooling water guided by the temperature adjusting unit to the cooling water circulation passage increases.

  Therefore, the exhaust heat recovery apparatus of this configuration increases the amount of heat recovered by the exhaust heat recovery unit as the load on the internal combustion engine increases. By doing in this way, the calorie | heat amount of the 1st cooling water collect | recovered by an exhaust heat recovery part increases, and the temperature of the 1st cooling water guide | induced to a cooling water inlet falls in connection with it. Moreover, when the temperature of the 1st cooling water guide | induced to a cooling water inlet falls, the temperature of the 1st cooling water discharged | emitted from a cooling water outlet will fall in connection with it. Therefore, the flow rate of the 2nd cooling water which a temperature adjustment part leads to a cooling water circulation flow path reduces, and the amount of heat | fever discarded by a temperature adjustment part reduces in connection with it.

An exhaust heat recovery type ship propulsion device according to one aspect of the present invention includes the exhaust heat recovery device according to any one of the above and the internal combustion engine, and the internal combustion engine is a main engine that generates a propulsion force of the ship. is there.
In this way, when the temperature of the cooling water that cools the internal combustion engine increases as the load on the internal combustion engine increases, the increased amount of heat of the cooling water can be recovered as effective energy. The exhaust heat recovery type ship propulsion device that has been made can be provided.

  An exhaust heat recovery method according to an aspect of the present invention includes a cooling water circulation step of circulating first cooling water for cooling an internal combustion engine from a cooling water outlet to a cooling water inlet of the internal combustion engine, and exhaust heat from the first cooling water. And an exhaust heat recovery step of generating power using the exhaust heat, wherein the exhaust heat recovery step generates a heat amount recovered from the first coolant as the load of the internal combustion engine increases. increase.

  In the exhaust heat recovery method according to an aspect of the present invention, the amount of heat recovered by the exhaust heat recovery unit is increased as the load of the internal combustion engine increases. In this way, when the temperature of the cooling water for cooling the internal combustion engine rises as the load on the internal combustion engine increases, the amount of heat of the cooling water whose temperature has risen can be recovered as effective energy. it can.

  ADVANTAGE OF THE INVENTION According to this invention, when the temperature of the cooling water which cools an internal combustion engine rises with the load of an internal combustion engine increasing, it became possible to collect | recover the calorie | heat amount of the raised cooling water as effective energy. An exhaust heat recovery device, an exhaust heat recovery type ship propulsion device, and an exhaust heat recovery method can be provided.

1 is a schematic configuration diagram of an exhaust heat recovery type ship propulsion device according to an embodiment of the present invention. It is a flowchart which shows the process which the waste heat recovery type | formula ship propulsion apparatus which concerns on one Embodiment of this invention performs. It is a figure which shows the change of the rotation speed of a diesel engine. It is a figure which shows the change of the discharge amount of the organic fluid which a circulation pump discharges. It is a figure which shows the temperature change of the cooling water which passed the evaporator of the ORC system. It is a figure which shows the change of the opening degree of a three-way valve. It is a figure which shows the temperature change of the cooling water in the cooling water inlet and cooling water outlet of a diesel engine. It is a figure which shows the change of the electric power generation output of an ORC system.

Hereinafter, an exhaust heat recovery type ship propulsion device 1 according to an embodiment of the present invention will be described with reference to the drawings.
The exhaust heat recovery type ship propulsion device 1 of the present embodiment is configured to remove the exhaust heat of the jacket cooling water of the diesel engine 3 (internal combustion engine), which is the main engine (main engine) that generates the propulsion force of the ship, by heat exchange. This is a device that generates power by rotating a power turbine connected to the generator by the organic fluid.

  As shown in FIG. 1, an exhaust heat recovery type ship propulsion device 1 (exhaust heat recovery device) according to this embodiment includes an ORC system 2 (exhaust heat recovery unit), a diesel engine 3 (internal combustion engine), and a turbocharger. 4 (supercharger), air cooler 5, cooling water circulation channel 6, cooling water bypass channel 7, fresh water generator 8, control device 9 (control unit), exhaust heat recovery system 10, Is provided.

An ORC system (Organic Rankine Cycle System) 2 is a system that generates power by using jacket cooling water to which heat generated by combustion of diesel fuel in the diesel engine 3 is transmitted as a heat source.
As shown in FIG. 1, the ORC system 2 includes an organic fluid circulation channel 2a, an evaporator 2b, a power turbine 2c, a generator 2d, a condenser 2e, and a circulation pump 2f.

The organic fluid circulation channel 2 a is a channel that circulates an organic fluid (working fluid) that exchanges heat with the cooling water circulating in the cooling water circulation channel 6. As the organic fluid, a fluid having a boiling point lower than that of water is used. Therefore, the organic fluid circulating through the organic fluid circulation channel 2a is evaporated by exchanging heat with high-temperature cooling water (for example, about 85 ° C.).
As an organic fluid having a lower boiling point than water, low molecular hydrocarbons such as isopentane, butane, and propane, and refrigerants such as R134a and R245fa can be used.

  The evaporator 2b is an apparatus that evaporates the organic fluid by exchanging heat between the cooling water flowing through the cooling water circulation passage 6 and the organic fluid. The evaporator 2b evaporates the organic fluid flowing from the circulation pump 2f via the organic fluid circulation channel 2a and supplies the evaporated organic fluid to the power turbine 2c.

  The power turbine 2c is a device that is rotated by a gas-phase organic fluid evaporated by the evaporator 2b. The power turbine 2c has a rotor shaft (not shown) connected to the generator 2d, and transmits the rotational power of the rotor shaft to the generator 2d. The organic fluid that has worked to provide rotational power to the power turbine 2c is discharged from the power turbine 2c and then supplied to the condenser 2e.

  The generator 2d is a device that generates power using the rotational power of the rotor shaft transmitted from the power turbine 2c. The electric power generated by the generator 2d is supplied to each part of the ship on which the exhaust heat recovery type ship propulsion apparatus 1 of the present embodiment is mounted.

  The condenser 2e is a device that cools the organic fluid discharged from the power turbine 2c with seawater, and condenses the gaseous organic fluid into a liquid organic fluid. The liquid organic fluid condensed by the condenser 2e is supplied to the circulation pump 2f via the organic fluid circulation passage 2a.

  The circulation pump 2f is a device that pumps the liquid organic fluid supplied from the condenser 2e through the organic fluid circulation passage 2a to the evaporator 2b. By circulating the organic fluid by the circulation pump 2f, the organic fluid circulates in the order of the evaporator 2b, the power turbine 2c, and the condenser 2e on the organic fluid circulation channel 2a. The discharge amount that the circulation pump 2 f discharges the organic fluid is controlled by the control device 9.

The diesel engine 3 is a main engine (main engine) that generates a propulsion force of a ship, and is an internal combustion engine that burns with scavenging air using at least one of fuel oil and fuel gas as main fuel.
The diesel engine 3 has a water jacket (not shown) that is a passage through which cooling water flows outside the engine cylinder. The diesel engine 3 guides the cooling water flowing from the cooling water inlet 3a to the water jacket to cool the periphery of the water jacket, and discharges the cooling water from the cooling water outlet 3b to the cooling water circulation passage 6.

  The turbocharger 4 includes a turbine 4a that is driven by exhaust gas that is discharged when the diesel engine 3 burns main fuel, and a compressor 4b that compresses outside air by the rotational power of the turbine. The outside air compressed by the turbocharger 4 is supplied to the diesel engine 3 as scavenging air for combustion.

  The air cooler 5 is a device that cools the scavenging air supplied from the compressor 4 b of the turbocharger 4 to the diesel engine 3. The temperature of the scavenging air at the inlet of the air cooler 5 ranges from about 50 ° C. to about 200 ° C. depending on the main engine load (the load of the diesel engine 3 as the main engine). By cooling the scavenging air with the air cooler 5, the temperature of the scavenging air at the outlet of the air cooler 5 is maintained at about 40 ° C. regardless of the main engine load. Thus, by reducing the temperature of the scavenging air, the weight per unit volume of the scavenging air supplied to the diesel engine 3 can be increased.

The air cooler 5 includes a first air cooling unit 5a disposed on the upstream side in the flow direction of the combustion air, and a second air cooling unit 5b disposed on the downstream side thereof.
The 1st air cooling part 5a cools scavenging air by performing heat exchange with the jacket cooling water of the diesel engine 3 supplied from the cooling water bypass flow path 7, and the scavenging air supplied from the compressor 4b.
The second air cooling unit 5b further cools the scavenged air by performing heat exchange between the fresh water cooled with seawater by a central cooler (not shown) and the scavenged air cooled by the first air cooling unit 5a. To do.

  As shown in FIG. 1, the cooling water circulation channel 6 is a channel that circulates cooling water in the order of a channel 6a, a channel 6b, a channel 6c, a channel 6d, a channel 6e, and a channel 6f. The cooling water circulation channel 6 is a channel for circulating cooling water (first cooling water) for cooling the diesel engine 3 from the cooling water outlet 3b of the diesel engine 3 to the cooling water inlet 3a.

  The cooling water that has cooled the diesel engine 3 is discharged from the cooling water outlet 3b to the flow path 6a. The cooling water discharged to the flow path 6a flows into the flow path 6b and is supplied to the flow path 6c by the circulation pump 6g. The cooling water supplied to the flow path 6c is subjected to heat exchange with the organic fluid that passes through the evaporator 2b and circulates through the organic fluid circulation flow path 2a, and is supplied to the flow path 6d. The cooling water supplied to the flow path 6d is guided to the relay tank 11.

  A three-way valve 6h (temperature adjustment unit) is provided in the flow path 6d. The three-way valve 6h is a device for bypassing part of the cooling water pumped from the circulation pump 6g to the flow path 6d without introducing it to the evaporator 2b. The control device 9 adjusts the opening degree of the three-way valve 6h, and among the cooling water pumped from the circulation pump 6g, the flow rate of the cooling water led to the evaporator 2b and the flow to the flow path 6d without being led to the evaporator 2b. The flow rate to be bypassed can be adjusted.

The reason why the flow rate of the cooling water guided to the evaporator 2b and the flow rate of bypassing the flow path 6d without being guided to the evaporator 2b are adjusted is to adjust the flow rate of the cooling water flowing into the evaporator 2b to adjust the ORC system 2. This is to adjust the power generation output (waste heat recovery amount).
When the ORC system 2 is stopped, the opening degree of the three-way valve 6h is adjusted so that the cooling water is not guided to the evaporator 2b.

  A three-way valve 6i (temperature adjustment unit) is provided in the flow path 6e. The three-way valve 6i is a device that supplies part of the cooling water supplied from the relay tank 11 to a central cooler (not shown) and guides other cooling water to the flow path 6f. The cooling water guided to the flow path 6f is supplied to the cooling water inlet 3a by the circulation pump 6j. The control device 9 adjusts the flow rate of the cooling water led to the central cooler and the flow rate of the cooling water led to the flow path 6f among the cooling water supplied from the relay tank 11 by adjusting the opening of the three-way valve 6i. Can be adjusted.

  The three-way valve 6i is used to lower the temperature of the cooling water discharged from the cooling water outlet 3b when the temperature of the cooling water discharged from the cooling water outlet 3b is higher than a target temperature (for example, 85 ° C.). . The three-way valve 6i is controlled by the control device 9 so that the same amount of fresh water (second cooling water) as the flow rate of the cooling water supplied from the flow path 6e to the central cooler is supplied from the central cooler.

The temperature of fresh water supplied from the central cooler to the three-way valve 6i is lower than the temperature of the cooling water flowing through the flow path 6e. For example, while the cooling water flowing through the flow path 6e is about 70 ° C., the temperature of the fresh water supplied to the three-way valve 6i is about 35 ° C.
Therefore, the three-way valve 6i lowers the temperature of the cooling water at about 70 ° C. flowing through the flow path 6e by guiding fresh water having a temperature lower than that of the cooling water flowing through the flow path 6e from the central cooler to the flow path 6f. Thereby, the temperature of the cooling water discharged from the cooling water outlet 3b is adjusted so as not to exceed the target temperature.
The control device 9 adjusts the opening degree of the three-way valve 6i according to the temperature detected by the temperature sensor 6k provided in the flow path 6a, so that the temperature of the cooling water discharged from the cooling water outlet 3b becomes the target temperature (for example, , 85 ° C).

The cooling water bypass channel 7 is a cooling water circulation channel 6 on the downstream side of the cooling water outlet 3 b and on the upstream side of the ORC system 2 from the relay tank 11 on the cooling water circulation channel 6 on the upstream side of the cooling water inlet 3 a. This is a flow path for bypassing the cooling water to the flow path 6b.
The cooling water bypass flow path 7 is a flow path 7 a that guides cooling water from the relay tank 11 to the air cooler 5 and a flow path that joins the cooling water that has passed through the air cooler 5 to the flow path 6 b of the cooling water circulation flow path 6. 7b.
A water pump 7c is provided in the flow path 7a. The water pump 7c is a device that pumps the cooling water supplied from the relay tank 11 to the flow path 7b.

A three-way valve 7d is provided at a connection position connecting the flow path 7a and the flow path 7b. The three-way valve 7d is a device for bypassing a part of the cooling water pumped from the water pump 7c to the flow path 7b without guiding it to the first air cooling unit 5a. The control device 9 adjusts the opening degree of the three-way valve 7d, and among the cooling water pumped from the circulation pump 7c, the flow rate of the cooling water led to the first air cooling unit 5a and the first air cooling unit 5a. It is possible to adjust the flow rate of detouring to the flow path 7b.
The flow rate of the cooling water guided to the first air cooling unit 5a and the flow rate of detouring to the flow channel 7b without being guided to the first air cooling unit 5a are adjusted for the cooling that merges from the flow channel 7b to the flow channel 6b. This is to maintain the water temperature at the target temperature.

The control device 9 detects the temperature of the cooling water flowing through the flow path 7b at the position immediately before joining the flow path 6b with the temperature sensor 7e, and adjusts the opening of the three-way valve 7d. When the temperature detected by the temperature sensor 7e is higher than the target temperature (for example, 85 ° C.), the control device 9 increases the flow rate of detouring to the flow path 7b without being led to the first air cooling unit 5a. The flow rate of the cooling water led to the cooling unit 5a is decreased.
On the other hand, when the temperature detected by the temperature sensor 7e is lower than the target temperature (for example, 85 ° C.), the control device 9 reduces the flow rate that is bypassed to the flow path 7b without being led to the first air cooling unit 5a. 1 The flow rate of the cooling water led to the air cooling unit 5a is increased.

  The fresh water generator 8 is a device that evaporates seawater taken from the outside of the ship with a decompressed evaporator and condenses the generated steam to produce fresh water. Since the sea water generator 8 evaporates seawater with the decompressed evaporator, the cooling water which cooled the diesel engine 3 can be used as a heat source. In order to be able to always produce a certain amount of fresh water, the fresh water generator 8 has a certain amount (for example, a flow rate of about 60 t / h out of a flow rate of about 90 t / h flowing through the flow path 6a). Cooling water is guided.

As shown in FIG. 1, the fresh water generator 8 includes a flow path 8a, a flow path 8b, an evaporator 8c, a water pump 8d, and a three-way valve 8e.
The water pump 8d is a device that pumps the cooling water supplied from the flow path 8a and guides it to the flow path 8b. A part of the cooling water flowing through the flow path 6a of the cooling water circulation path 6 is guided to the flow path 8a by pumping the cooling water with the water pump 8d.

  A three-way valve 8e is provided at a position where the flow path 8a and the flow path 8b are connected. The three-way valve 8e is a device for bypassing the cooling water pumped from the water pump 8d to the flow path 8b without guiding it to the evaporator 8c. The control device 9 switches between switching the opening of the three-way valve 8e to guide the entire amount of cooling water pumped from the water pump 8d to the fresh water generator 8 or to bypass the entire amount of cooling water to the flow path 8b. be able to.

  The control device 9 is a device that controls each part of the exhaust heat recovery type ship propulsion device 1. The control device 9 performs various processes by reading and executing a control program stored in a storage unit (not shown).

The exhaust heat recovery system 10 is an apparatus that recovers and uses exhaust heat of exhaust gas discharged from the diesel engine 3 and used as power for the turbocharger 4.
The exhaust heat recovery system 10 includes a composite boiler 10a, an exhaust gas passage 10b, a cooling water passage 10c, a heater 10d, an atmospheric pressure drain tank 10e, and a feed water pump 10f.

The composite boiler 10a is a device that generates steam by exchanging heat between high-temperature exhaust gas and cooling water. High-temperature exhaust gas is guided from the turbocharger 4 to the composite boiler 10a through the exhaust gas passage 10b. Further, the cooling water is guided from the atmospheric pressure drain tank 10e to the composite boiler 10a through the cooling water flow path 10c by the water supply pump 10f.
The cooling water sent to the composite boiler 10a evaporates by heat exchange with the exhaust gas, and the generated steam is sent to the heater 10d. The heater 10d is used as a heat source for various devices (oil heater, tank heater, etc.). The steam used as a heat source in the heater 10d is collected in the atmospheric pressure drain tank 10e.

The level of the cooling water collected in the atmospheric pressure drain tank 10e is adjusted by a float switch (not shown) so as to maintain a constant water level.
As described above, the exhaust heat recovery system 10 recovers exhaust heat of exhaust gas used as power for the turbocharger 4 to generate steam, and uses it as a heat source for various devices (oil heater, tank heater, etc.). be able to.

  Next, processing executed by the exhaust heat recovery ship propulsion device 1 according to the present embodiment will be described with reference to the flowchart of FIG. 2 and the diagrams shown in FIGS. The processing shown in the flowchart of FIG. 2 is performed by the control device 9 reading and executing a control program stored in a storage unit (not shown). The process shown in FIG. 2 is performed by changing the discharge amount of the organic fluid discharged from the circulation pump 2f of the ORC system 2 when an instruction to change the rotation speed of the diesel engine 3 which is the main engine of the ship is received. This is a process for changing the amount of heat collected by the system 2 from the cooling water.

  In step S201, the control device 9 determines whether or not the rotational speed of the diesel engine 3 that is the main engine is lower than a rated rotational speed (for example, 90 rpm). When it is determined that the current rotation speed is lower than the rated rotation speed, the control device 9 proceeds to step S202, and otherwise proceeds to step S205.

  In step S <b> 202, the control device 9 determines whether a rotation speed increase instruction for increasing the rotation speed is received from an operation unit (not shown) that indicates the rotation speed of the diesel engine 3. When it is determined that the rotation speed increase instruction has been received, the control device 9 proceeds to step S203, and otherwise proceeds to step S205.

  In step S <b> 203, since the control device 9 determines that the rotation speed increase instruction has been received, the control apparatus 9 controls the diesel engine 3 to increase the rotation speed of the diesel engine 3. When the rotational speed of the current diesel engine 3 is R1 [rpm] and the rotational speed instructed by the rotational speed increase instruction is R2 [rpm], the control device 9 controls the diesel engine 3 so that R1 increases to R2. Control.

  As shown in FIG. 3, the control device 9 increases the rotational speed of the diesel engine 3 at time T <b> 1 so that the rotational speed increase amount of the diesel engine 3 per unit time becomes constant. For example, when the amount of increase in the rotational speed of the diesel engine 3 per unit time is Rn, the control device 9 takes the time of (R2-R1) / Rn (time from time T1 to time T3 shown in FIG. 3). The rotational speed of the diesel engine 3 is increased at a constant gradient.

In step S204, the control device 9 controls the circulation pump 2f so as to increase the discharge amount per unit time of the organic fluid discharged from the circulation pump 2f of the ORC system 2 as the rotational speed of the diesel engine 3 increases. .
As shown by a solid line in FIG. 4, the control device 9 increases the discharge amount so that the discharge amount from Q1 [l / min] until time T1 becomes Q2 [l / min] at time T2. In addition, the comparative example shown with a broken line in FIG. 4 is an example in which the discharge amount per unit time of the organic fluid discharged from the circulation pump 2f does not change even if the rotational speed of the diesel engine 3 increases.

The controller 9 increases the discharge amount of the circulation pump 2f because the amount of heat recovered by the ORC system 2 from the cooling water circulating through the cooling water circulation passage 6 as the rotational speed of the diesel engine 3 increases. This is to increase it. By ORC system 2 is the amount of heat recovered is increased from the cooling water, the evaporator 2b lowers the temperature _{T ORC_OUT} of the coolant after passing through the reduction temperature _{T JCT_IN} of the cooling water in the cooling water inlet 3a with it To do.

By appropriately setting the amount of heat collected by the ORC system 2 from the cooling water, the temperature T _{JCT_OUT} of the cooling water at the cooling water outlet 3b can be maintained at the target temperature (for example, 85 ° C.).
As shown in FIG. 5, the temperature T _{ORC_OUT} of the cooling water after passing through the evaporator 2b of the ORC system 2 has been Temp1 until time T1 but has decreased to Temp2 at time T2. In other words, the amount of heat recovered from the cooling water passing through the evaporator 2b is greater after time T1 than before time T1.

Thus, the temperature T _{ORC_OUT} of the cooling water after passing through the evaporator 2b is decreased by increasing the discharge amount of the circulation pump 2f in accordance with the increase in the rotational speed of the diesel engine 3. Therefore, the flow rate of the relatively low temperature fresh water led from the central cooler to the flow path 6f by the three-way valve 6i decreases. Thereby, the amount of heat discarded from the cooling water due to the inflow of fresh water at the three-way valve 6i is reduced.

Further, as shown in FIG. 4, the control device 9 of the present embodiment starts increasing the discharge amount of the circulation pump 2 f at time T <b> 1 when the increase in the rotational speed of the diesel engine 3 is started. By doing in this way, the response of the timing which starts the increase in the discharge amount of the circulation pump 2f compared with the case where the increase in the discharge amount of the circulation pump 2f is started after _{TJCT_OUT} detected by the temperature sensor 6k starts to increase. There is no delay.

As described above, in the present embodiment, the temperature of the cooling water at the cooling water outlet 3b is started by starting the increase in the discharge amount of the circulation pump 2f simultaneously with the time T1 when the increase in the rotational speed of the diesel engine 3 is started. While _maintaining T _{JCT_OUT} at a target temperature (for example, 85 ° C.), it is possible to suppress a response delay in timing at which the amount of heat recovered from the cooling water by the ORC system 2 is increased.

FIG. 6 is a diagram comparing the opening degree of the three-way valve 6i in the present embodiment and the opening degree of the three-way valve 6i in the comparative example.
The opening degree of the three-way valve 6i shown in FIG. 6 refers to the opening degree of the portion that guides fresh water from the central cooler to the flow path 6f. Therefore, the larger the opening degree of the three-way valve 6i, the larger the flow rate of fresh water flowing into the flow path 6f.
Moreover, the comparative example shown by the broken line in FIG. 6 corresponds to the comparative example shown in FIG. 4, and the discharge amount per unit time of the organic fluid discharged by the circulation pump 2 f even if the rotational speed of the diesel engine 3 increases. The case where it does not change is shown.

In the present embodiment, the discharge amount of the circulation pump 2f is increased in accordance with the increase in the rotational speed of the diesel engine 3. As indicated by a solid line in FIG. 6, the opening degree of the three-way valve 6i of the present embodiment increases from Ap1 at time T1 to Ap2 at time T3.
On the other hand, as shown by a broken line in FIG. 6, the opening degree of the three-way valve 6i of the comparative example increases from Ap1 at time T1 to Ap3 at time T3. As shown in FIG. 6, Ap2 has a smaller opening than Ap3. Therefore, in this embodiment, the flow rate of relatively low-temperature fresh water guided from the central cooler to the flow path 6f by the three-way valve 6i is smaller than that of the comparative example.
As described above, FIG. 6 shows that the exhaust heat recovery type ship propulsion device of the comparative example has a larger amount of heat discarded from the cooling water than the exhaust heat recovery type ship propulsion device 1 of the present embodiment. .

Figure 7 shows the temperature _{T JCT_OUT} coolant temperature _{T JCT_IN} of the cooling water in the cooling water inlet 3a of the diesel engine 3 in the cooling water outlet 3b. As shown in FIG. 7, as the rotational speed of the diesel engine 3 increases, T _{JCT_OUT} increases from _Temp 3 at time T2 when a certain time has elapsed from time T1. This is because T _{JCT_IN} has decreased from Temp4 to Temp6 by increasing the discharge amount of the circulation pump 2f.

Further, T _{JCT_OUT that} has risen from _{Temp 3} at time T 2 _{falls to Temp} 3 again at time T 4, and is maintained at the same temperature as before the number of revolutions of diesel engine 3 increases. This is because T _{JCT_IN} after time T4 is maintained at Temp5 lower than _Temp4 by increasing the discharge amount of the circulation pump 2f.

FIG. 8 shows changes in the power generation output of the ORC system 2. As shown in FIG. 8, in this embodiment, since the discharge amount of the circulation pump 2f is increased from time T1, the power generation output increases early, and the power generation output P1 [KW] at time T1 is earlier than time T3. The power generation output P2 [KW] has been reached at time '.
On the other hand, in the comparative example, since the discharge amount of the circulation pump 2f is constant from time T1, the power generation output does not increase early, and the power generation output P1 [KW] at time T1 is earlier than time T4 at time T4 ′. The power generation output P2 [KW] has been reached.

  In step S <b> 205, the control device 9 determines whether a rotation speed reduction instruction for reducing the rotation speed is received from an operation unit (not shown) that instructs the rotation speed of the diesel engine 3. If it is determined that the rotation speed reduction instruction has been received, the control device 9 proceeds to step S206. If not, the control device 9 ends the process shown in FIG. 2 and executes step S201 again.

In step S206, the control device 9 determines that the rotation speed reduction instruction has been received, and thus controls the diesel engine 3 so as to decrease the rotation speed of the diesel engine 3. When the current rotational speed of the diesel engine 3 is R2 [rpm] and the rotational speed instructed by the rotational speed reduction instruction is R1 [rpm], the control device 9 controls the diesel engine 3 so that R2 decreases to R1. Control.
For example, when the amount of increase in the rotational speed of the diesel engine 3 per unit time is Rn, the control device 9 reduces the rotational speed of the diesel engine 3 with a constant gradient over a period of (R2-R1) / Rn. .

In step S207, the control device 9 controls the circulation pump 2f so as to reduce the discharge amount per unit time of the organic fluid discharged from the circulation pump 2f of the ORC system 2 as the rotational speed of the diesel engine 3 decreases. .
The controller 9 reduces the discharge amount of the circulation pump 2f because the amount of heat recovered from the cooling water that the ORC system 2 circulates through the cooling water circulation passage 6 as the rotational speed of the diesel engine 3 decreases. It is for lowering.

Here, it is desirable that the control device 9 reduce the discharge amount of the circulation pump 2f after a certain waiting time has elapsed since the start of the reduction in the rotational speed of the diesel engine 3. The fixed waiting time here is, for example, the time from when the decrease in the rotational speed of the diesel engine 3 is started until T _{JCT_OUT} detected by the temperature sensor 6k starts to decrease.
By doing in this way, the ORC system 2 can _remove as much exhaust heat as possible from the cooling water within a range in which the temperature T _{JCT_OUT} of the cooling water at the cooling water outlet 3b is maintained at the target temperature (for example, 85 ° C.). It can be recovered.

Thus, the temperature T _{ORC_OUT} of the cooling water after passing through the evaporator 2b rises by reducing the discharge amount of the circulation pump 2f in accordance with the reduction in the rotational speed of the diesel engine 3. Therefore, it is possible to prevent T _{ORC_OUT from} being unnecessarily decreased in accordance with the decrease in the rotational speed of the diesel engine 3.

Next, the operation and effect of the exhaust heat recovery type ship propulsion device 1 of the present embodiment described above will be described.
According to the exhaust heat recovery type ship propulsion device 1 of the present embodiment, the amount of heat recovered by the ORC system 2 is increased by increasing the discharge amount of the circulation pump 2f of the ORC system 2 as the rotational speed of the diesel engine 3 increases. Was increased. By doing in this way, when the temperature T _{JCT_OUT at} the cooling water outlet 3b for cooling the cooling water for cooling the diesel engine 3 increases as the rotational speed of the diesel engine 3 increases, the increased amount of heat becomes effective. It can be recovered as energy.

  Further, in the exhaust heat recovery type marine vessel propulsion apparatus 1 of the present embodiment, when the cooling water (first cooling water) discharged from the cooling water outlet 3b is higher than the target temperature, fresh water (second cooling) lower than the cooling water. The three-way valve 6i (temperature adjusting unit) adjusts the water) to the flow path 6f on the upstream side of the cooling water inlet 3a to lower the temperature of the cooling water. However, the amount of heat that is discarded increases as the flow rate of fresh water that the three-way valve 6i leads to the cooling water circulation passage 6 increases.

  Therefore, the exhaust heat recovery type ship propulsion device 1 of the present embodiment increases the amount of heat recovered by the ORC system 2 (exhaust heat recovery unit) as the rotational speed of the diesel engine 3 increases. By doing in this way, the calorie | heat amount of the cooling water collect | recovered by ORC system 2 increases, and the temperature of the cooling water guide | induced to the cooling water inlet 3a falls in connection with it.

  Further, when the temperature of the cooling water led to the cooling water inlet 3a is lowered, the temperature of the cooling water discharged from the cooling water outlet 3b is lowered accordingly. Therefore, the flow rate of fresh water that the three-way valve 6i leads to the cooling water circulation passage 6 decreases, and accordingly, the amount of heat discarded by the three-way valve 6i decreases.

Further, according to the exhaust heat recovery type ship propulsion device 1 of the present embodiment, the organic fluid is evaporated by heat exchange with the cooling water, and the power turbine 2c is rotated by the evaporated organic fluid, and the power turbine 2c The discharged organic fluid is condensed, and the condensed organic fluid is circulated by the circulation pump 2f. The circulation pump 2f is controlled so that the discharge amount per unit time of the organic fluid discharged as the rotational speed of the diesel engine 3 increases.
By doing in this way, when the rotation speed of diesel engine 3 increases, the amount of heat which evaporator 2b collects from cooling water by heat exchange can be increased. Therefore, the flow rate of fresh water led by the three-way valve 6i decreases and the amount of heat discarded by the three-way valve 6i decreases.

Further, according to the exhaust heat recovery type ship propulsion device 1 of the present embodiment, the turbocharger 4 is driven by the exhaust gas discharged from the diesel engine 3. The turbocharger 4 driven by the exhaust gas compresses the air and supplies it to the diesel engine 3 as combustion air. Although the temperature of combustion air increases due to compression, it is cooled by the cooling water flowing through the cooling water bypass passage 7. Therefore, the heat quantity of the combustion air is recovered by the cooling water. The amount of heat of the cooling water is further recovered by the ORC system 2.
Thus, according to this embodiment, the rotational speed of the diesel engine 3 can be increased by the turbocharger 4 and the amount of heat of the combustion air heated by the compression can be appropriately recovered by the ORC system 2. .

1 Waste heat recovery type ship propulsion device (exhaust heat recovery device)
2 ORC system (exhaust heat recovery unit)
2a Organic fluid circulation channel 2b Evaporator 2c Power turbine 2d Generator 2e Condenser 2f Circulation pump 3 Diesel engine (internal combustion engine)
3a Cooling water inlet 3b Cooling water outlet 4 Turbocharger (supercharger)
4a Turbine 4b Compressor 5 Air cooler 5a First air cooling section 5b Second air cooling section 6 Cooling water circulation flow path 6i Three-way valve (temperature adjusting section)
6k Temperature sensor 7 Cooling water bypass flow path 7c Water supply pump 7d Three-way valve 7e Temperature sensor 9 Control device (control unit)
10 Waste heat recovery system

Claims (7)

A cooling water circulation passage for circulating first cooling water for cooling the internal combustion engine from the cooling water outlet to the cooling water inlet of the internal combustion engine;
An exhaust heat recovery unit that recovers exhaust heat from the first coolant circulating in the cooling water circulation passage and generates power using the exhaust heat;
An exhaust heat recovery apparatus comprising: a control unit that controls the exhaust heat recovery unit so as to increase an amount of heat recovered by the exhaust heat recovery unit in response to an increase in a load of the internal combustion engine. The exhaust heat recovery unit
An evaporator that evaporates the working fluid by exchanging heat between the first cooling water circulating through the cooling water circulation passage and the working fluid;
A turbine rotated by the working fluid evaporated by the evaporator;
A generator for generating power by the rotational power of the turbine;
A condenser for condensing the working fluid discharged from the turbine;
A circulation pump for circulating the working fluid condensed by the condenser,
2. The exhaust according to claim 1, wherein the control unit controls the circulation pump to increase a discharge amount per unit time of the working fluid discharged from the circulation pump in accordance with an increase in a load of the internal combustion engine. Heat recovery device. A cooling water bypass channel that bypasses the first cooling water from the cooling water circulation channel upstream of the cooling water inlet to the cooling water circulation channel downstream of the cooling water outlet and upstream of the exhaust heat recovery unit. When,
A supercharger that is driven by exhaust gas discharged from the internal combustion engine, compresses the air and supplies the air as combustion air to the internal combustion engine;
The air cooler which cools the combustion air supplied from the supercharger to the internal combustion engine with the first cooling water flowing in the cooling water bypass flow path. Waste heat recovery device.   The said control part controls the said exhaust heat recovery part so that the amount of heat which the said exhaust heat recovery part collect | recovers according to the load of the said internal combustion engine falling may be reduced. The exhaust heat recovery device described in 1.   When the temperature of the first cooling water discharged from the cooling water outlet is higher than a target temperature, the second cooling water having a temperature lower than that of the first cooling water is supplied to the cooling water circulation channel upstream of the cooling water inlet. The exhaust heat recovery apparatus according to any one of claims 1 to 4, further comprising a temperature adjusting unit that guides the temperature to the temperature of the first cooling water. The exhaust heat recovery apparatus according to any one of claims 1 to 5,
The internal combustion engine,
An exhaust heat recovery type ship propulsion apparatus, wherein the internal combustion engine is a main engine that generates a propulsion force of the ship. A cooling water circulation step for circulating first cooling water for cooling the internal combustion engine from the cooling water outlet to the cooling water inlet of the internal combustion engine;
A waste heat recovery step of recovering waste heat from the first cooling water and generating power using the waste heat;
The exhaust heat recovery step is an exhaust heat recovery method in which the amount of heat recovered from the first cooling water is increased as the load on the internal combustion engine increases.

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