JPH07305606A - Exhaust heat recovery system - Google Patents

Abstract

PURPOSE:To improve an engine output by effectively recovering engine exhaust heat. CONSTITUTION:An exhaust gas supply pipe 13 from a mirror cycle gas engine 1 is connected to a steam generator 9. A steam turbine 10 is arranged on a circulation piping 6 of working substance fluid connected to the steam generator 9. A supercharger 12 is provided on an output shaft 10a of the steam turbine 10 for supplying compressed air to the mirror cycle gas engine 1. The supercharger 12 is driven with combustion exhaust gas from the mirror cycle gas engine as heat source, for improving an engine output.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a diesel engine,
The present invention relates to an exhaust heat recovery system configured to recover exhaust heat generated by an engine such as a Stirling engine and a Miller cycle gas engine to extract power.

[0002]

2. Description of the Related Art As an exhaust heat recovery system as described above, hot water discharged from a cooling jacket for cooling an engine is heated by combustion exhaust gas from an engine, and heat from the cooling jacket and heat of the combustion exhaust gas are combined with each other. There was a configuration in which the hot water obtained by the above was supplied to the regenerator of the absorption refrigerator to operate the absorption refrigerator.

[0003]

However, in the case of the conventional example, the temperature of the hot water supplied to the regenerator is about 90 ° C. by design, and the heat of the combustion exhaust gas, which usually reaches 400 to 700 ° C., is used. That said, the reality is that Excelgi is not being used effectively. That is, high-quality heat,
I wasted to use it as low-grade heat.

Further, since the absorption liquid heated by the hot water obtained by utilizing the heat of the combustion exhaust gas is returned to the absorber and cooled, a part of the heat of the hot water is wasted to the absorber cooling water. Was there.

The present invention has been made in view of such circumstances, and the exhaust heat recovery system of the invention according to claim 1 can effectively recover the engine exhaust heat and improve the engine output. The exhaust heat recovery system of the invention according to claim 2 aims to enable the engine exhaust heat to be recovered more effectively, and the exhaust heat recovery of the invention according to claim 3 The system aims to simplify the configuration and improve engine output,
Another object of the exhaust heat recovery system of the invention according to claim 4 is to enable effective recovery of exhaust heat of the fuel cell.

[0006]

In order to achieve the above-mentioned object, the exhaust heat recovery system of the invention according to claim 1 provides a working fluid connected to a steam generator using exhaust gas from an engine as a heat source. A steam turbine is provided in the circulation pipe, and a turbocharger of the engine is interlockingly connected to the steam turbine.

Further, the exhaust heat recovery system of the invention according to claim 2 has the following features to achieve the above object.
In the exhaust heat recovery system of the invention according to claim 1, an engine hot water supply pipe for supplying hot water discharged from the engine is connected to a regenerator of an absorption refrigerator, and the absorbent preheated by the regenerator is used as a working fluid to generate steam. It is configured to supply to the device.

Further, the exhaust heat recovery system of the invention according to claim 3 is the same as that of claim 1 in order to achieve the above object.
Alternatively, the engine of the exhaust heat recovery system of the invention according to 2 is composed of a Miller cycle engine.

The exhaust heat recovery system according to a fourth aspect of the present invention is intended to achieve the above object.
Alternatively, a fuel cell hot water supply pipe for supplying hot water discharged from the fuel cell is connected to the regenerator of the exhaust heat recovery system of the invention according to 3 and a heat exchanger is provided between the regenerator and the steam generator. In addition, a steam supply pipe for supplying low-pressure steam discharged from the fuel cell is connected to the heat exchanger.

[0010]

According to the constitution of the exhaust heat recovery system of the invention as set forth in claim 1, steam is generated in the steam generator by the combustion exhaust gas discharged from the engine, and the steam drives the steam turbine to take out power. The power can operate the supercharger of the engine to supply compressed air to the engine. As the working fluid, water, butane, etc. can be used. When using an absorption refrigerator, an aqueous ammonia solution (the main component supplied to the steam turbine is water), an aqueous alcohol solution such as methyl alcohol (supplied to the steam turbine) is used. The main component is water).

According to the structure of the exhaust heat recovery system of the invention as claimed in claim 2, the absorption refrigerating machine is operated by utilizing the hot water after engine cooling discharged from the engine, and the regenerator is used to preheat the same. The absorbed liquid can be supplied to the steam generator. On the other hand, the cold water taken out from the absorption refrigerator can be used as a heat source for cooling or freezing.

According to the structure of the exhaust heat recovery system of the third aspect of the present invention, since the compression ratio can be adjusted in the Miller cycle engine, the compression ratio can be adjusted to a high level by the operation of the supercharger due to engine exhaust heat. The output status can be obtained.

According to the configuration of the exhaust heat recovery system of the invention as claimed in claim 4, the absorption chiller is operated using the hot water discharged from the engine and the fuel cell, and is discharged from the fuel cell. With the low-pressure steam, the absorption liquid preheated in the regenerator can be further heated and then supplied to the steam generator.

According to the structure of the exhaust heat recovery system of the invention as claimed in claim 5, a steam turbine is provided in the working fluid circulation pipe connected to the steam generator which uses the exhaust gas from the engine as a heat source. The exhaust heat can be recovered as electric power by driving the generator with. This electric power also drives the electric motor, which can also drive the supercharger.

[0015]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a first embodiment of an exhaust heat recovery system according to the present invention. A Miller cycle gas engine 1 is interlocked with a generator 3 via a transmission clutch 2.

A main pipe 5 consisting of an engine hot water supply pipe 5a and a cooling water pipe 5b with a first pump 4 interposed is connected across the outlet and inlet of the engine cooling section of the gas engine 1. To the main pipe 5, a first heat exchanger 7 connected to a water circulation pipe 6 as a working fluid is connected.

A second pump 8, a steam generator 9, a steam turbine 10 and a condenser 11 are installed in the circulation pipe 6. The output shaft 10a of the steam turbine 10 is provided with a supercharger 12 for supplying compressed air to the Miller cycle gas engine 1, and the steam generator 9 is provided with the combustion exhaust gas from the Miller cycle gas engine 1. An exhaust gas supply pipe 13 to be supplied is connected.

With the above construction, hot water (for example, a temperature of 80 to 100 ° C.) generated by cooling the engine is used for preheating water, and combustion exhaust gas from the Miller cycle gas engine 1 (for example, a temperature of 400 to 750 ° C.) Is used as a heat source to vaporize and evaporate water, and the steam is used to generate the steam turbine 10
To drive the supercharger 12 to supply compressed air without reducing the power of the Miller cycle gas engine 1 to obtain a high output state.

FIG. 2 is a schematic configuration diagram showing a second embodiment of the exhaust heat recovery system according to the present invention. The difference from the first embodiment is as follows. That is, in place of the first heat exchanger 7 and the condenser 11 in the first embodiment, the circulation pipe 6 is provided with the regenerator 15, the absorption liquid pump 16, and the absorber 17 of the absorption refrigerator 14. Has been. In the figure, 18 is a condenser and 19 is an evaporator, respectively, that is, an aqueous ammonia solution, an aqueous methanol solution, etc.
The regenerator 1 uses an absorbing liquid that has a lower boiling point than water as the refrigerant.
5, the absorber 17, the condenser 18, and the evaporator 19 are circulated, cold water is taken out from the evaporator 19, and the cold water is used as a heat source for cooling or freezing.

A cooling tower 21 is connected to the cooling water pipe 5b via a three-way valve 20, and although not shown, a temperature sensor is provided in the engine hot water supply pipe 5a to discharge the cooled water from the Miller cycle gas engine 1 after cooling. Measure the temperature of hot water,
The opening degree of the three-way valve 20 is automatically adjusted so that the hot water temperature is maintained within the set range and overheat can be avoided. The other structure is the same as that of the first embodiment, and the description thereof is omitted by giving the same drawing numbers.

According to the structure of the second embodiment, the absorption refrigerating machine 14 is operated by utilizing the exhaust heat of the cooled hot water discharged from the Miller cycle gas engine 1, and the regenerator 15 preheats it. Absorbed liquid (eg, aqueous ammonia solution)
The working fluid (mainly water when the absorbing liquid is an aqueous ammonia solution) is supplied to the steam generator 9 so that the steam turbine 10 is driven by using the combustion exhaust gas as a heat source in the same manner as in the first embodiment. It has become.

FIG. 3 is a schematic configuration diagram showing a third embodiment of the exhaust heat recovery system according to the present invention. The difference from the second embodiment is as follows. That is, the condenser 22 and the second pump 23 are provided between the steam turbine 10 and the absorber 17 in the circulation pipe 6 in the second embodiment. Further, the three-way valve 20 and the cooling tower 21 are omitted. The other structure is the same as that of the second embodiment, and the description thereof will be omitted by giving the same drawing numbers.

According to the configuration of the third embodiment, by cooling the water passing through the steam turbine 10 with the condenser 22,
The output of the steam turbine 10 can be increased by increasing the pressure difference between the inlet and outlet of the steam turbine 10.

FIG. 4 is a schematic block diagram showing a fourth embodiment of the exhaust heat recovery system according to the present invention. The difference from the second embodiment is as follows. That is, the second heat exchanger 24 is interposed between the regenerator 15 and the steam generator 9 in the circulation pipe 6 in the second embodiment, and the fuel cell 25 is connected to the second heat exchanger 24. A steam supply pipe 26 is connected to supply low-pressure steam discharged from the. Further, a fuel cell hot water supply pipe 27 for supplying hot water discharged from the fuel cell 25 is connected to an intermediate part of the engine hot water supply pipe 5a. The other structure is the same as that of the second embodiment, and the description thereof will be omitted by giving the same drawing numbers.

According to the configuration of the fourth embodiment, when applied to a cogeneration system or the like in which the power generation by the Miller cycle gas engine 1 and the power generation by the fuel cell 25 are combined, the Miller cycle gas engine 1
In addition, there is an advantage that exhaust heat from the fuel cell 25 can be effectively recovered.

In FIG. 4, a first opening / closing valve 28 is provided between the second heat exchanger 24 and the steam generator 9, and the first opening / closing valve 28 and the second heat exchange valve 28 are exchanged with each other. And the regenerator 15 are connected to each other via a pipe 30 having a second opening / closing valve 29 interposed therebetween, and when driving the steam turbine 10, only the first opening / closing valve 28 is opened, while When the steam turbine 10 is not driven, only the second opening / closing valve 29 is opened so that the absorption liquid that has passed through the second heat exchanger 24 is regenerated by the regenerator 1.
It is configured to return to 5.

FIG. 5 is a schematic view of the essential parts of a fifth embodiment of the exhaust heat recovery system according to the present invention. The difference from the first embodiment is as follows. That is, the steam turbine 10 is configured to interlockly connect the generator 31 to take out electric power, while the supercharger 12 is interlockingly connected to the electric power output line 33 of the generator 31 and the electric motor 32. Are connected via a transformer 34 so as to supply set electric power to the electric motor 32 and take out surplus electric power separately. Another electric motor is driven by the surplus power extracted separately, and the electric motor and the crankshaft of the Miller cycle gas engine 1 are interlocked and coupled by a gear or the like, and the Miller cycle gas engine 1
May be further improved. of course,
The output power of the generator 31 is not limited to use as the power source of the electric motor 32 for driving the supercharger 12,
It may be used for other purposes.

According to the configuration of the fifth embodiment, the supercharger 1
2 is applied to an engine of a type in which the capacity of 2 is uniquely determined, that is, an engine other than the Miller cycle gas engine 1 described above, the supercharger 1
It is possible to supply the electric motor 32 with the electric power that matches the capacity of No. 2 and to use it suitably.

FIG. 6 is a schematic configuration diagram of a main part showing a modified example of the exhaust heat recovery system according to the present invention.
Before supplying the refrigerant vapor (for example, ammonia vapor) of the absorption refrigerator 14 evaporated in the regenerator 15 to the condenser 18, a third heat exchanger 35 is interposed between the regenerator 15 and the regenerator 15. And is supplied to the third heat exchanger 35 for cooling to improve the cooling efficiency.

FIG. 7 is a schematic configuration diagram of a main part showing another modified example of the exhaust heat recovery system according to the present invention.
Through the lower half side of the hot water supply tank 37 and then connected to a cooling tower (not shown), while the exhaust gas supply pipe 13 through the steam generator 9 is connected to the fourth heat exchanger 38.
The third pump 39 is connected to the fourth heat exchanger 38 and the upper half of the hot water supply tank 37.
A circulation pipe 40 is provided which is interposed.

At the bottom of the hot water supply tank 37, there is a water supply pipe 41,
The hot water supply pipes 42 are respectively connected to the upper part, and the return pipe 43 for the hot water which is connected to the hot water supply pipe 42 is connected to substantially the center of the hot water supply tank 37 in the vertical direction.
7 and the heat energy of the combustion exhaust gas after being supplied to the steam generator 9 as well as the heat energy recovered by cooling in the condenser 18 are used for hot water supply, and exhaust heat is more effectively recovered. ing.

The present invention is not limited to the Miller cycle gas engine 1 as in the above-described embodiment, but is applicable to an exhaust heat recovery system using various engines such as a diesel engine and a Stirling engine by adopting the configuration of the fifth embodiment. Can also be suitably applied.

Further, in the above-mentioned embodiment, the so-called cogeneration system in which the engine drives the generator 3 to take out the electric power is shown, but the present invention can be applied to the case where various mechanical devices are driven by the engine.

[0034]

As is clear from the above description, according to the exhaust heat recovery system of the first aspect of the invention, the combustion exhaust gas discharged from the engine is used to drive the steam turbine to generate power. Since the exhaust heat source itself operates the turbocharger of the engine to supply compressed air to the engine, it is not necessary to interlock the crankshaft of the engine and the turbocharger via gears, and Power loss can be eliminated and engine exhaust heat can be effectively recovered to improve engine output.

According to the exhaust heat recovery system of the second aspect of the present invention, the hot water discharged from the engine after engine cooling is used for the operation of the absorption chiller and the preheating of the absorption liquid supplied to the steam generator. Since it is used, the cold water taken out by the absorption refrigerator can be used for cooling and freezing, and the engine exhaust heat can be more effectively recovered.

In an engine such as a gas engine, the output is increased when the compression ratio is increased, but if the compression ratio is too high, the temperature in the combustion chamber rises and knocking occurs. Therefore, it is important to prevent knocking and obtain high output while maintaining a high compression ratio. On the other hand, the Miller cycle gas engine has a feature that the compression start timing can be adjusted. When the invention according to claim 3 is applied to this Miller cycle gas engine and combustion air compressed by a supercharger is supplied and the compression start timing is delayed, the temperature rise in the combustion chamber can be suppressed. Therefore, it is possible to operate at a high compression ratio while preventing knocking, and it is possible to increase the engine output. The mechanical loss increases in the conventional method of driving the supercharger with the power taken out from the crankshaft of the engine. Further, when the supercharger is driven by the electric power generated by the exhaust heat recovery, power generation loss and motor loss occur. On the other hand, in the exhaust heat recovery system of the invention according to claim 3 in which the steam turbine driven by exhaust heat is linked to the supercharger, the mechanical loss is small and the power obtained by the exhaust heat recovery is fully utilized. Adjusting the closing timing of the intake valve of the Miller cycle gas engine so that the thermal efficiency of the entire engine can be dramatically improved. Since it is possible to obtain a high output state by matching the compression ratio with the operation of the supercharger due to engine exhaust heat, for example, in order to match the operation of the supercharger with the engine, the interlocking connection configuration of the steam turbine and the supercharger is used. It is not necessary to add a special structure such as gear shifting or frequency adjustment to the power supply, and power loss for driving the supercharger can be eliminated. Therefore, the engine output can be further improved by simplifying the configuration.

According to the exhaust heat recovery system of the invention as defined in claim 4, the hot water, which is the low temperature exhaust heat discharged from the engine and the fuel cell, is utilized for the operation of the absorption refrigerator, and further, from the fuel cell. The low-pressure steam that is the high-temperature exhaust heat that is discharged and the combustion exhaust gas that is the high-temperature exhaust heat that is discharged from the engine are used to heat the absorption liquid that has been preheated in the regenerator.
Exhaust heat from both the engine and the fuel cell can be effectively recovered.

According to the exhaust heat recovery system of the fifth aspect of the invention, the exhaust heat can be recovered as electric power.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of an exhaust heat recovery system according to the present invention.

FIG. 2 is a schematic configuration diagram showing a second embodiment of the exhaust heat recovery system according to the present invention.

FIG. 3 is a schematic configuration diagram showing a third embodiment of the exhaust heat recovery system according to the present invention.

FIG. 4 is a schematic configuration diagram showing a fourth embodiment of the exhaust heat recovery system according to the present invention.

FIG. 5 is a schematic configuration diagram of essential parts showing a fifth embodiment of the exhaust heat recovery system according to the present invention.

FIG. 6 is a schematic configuration diagram of a main part showing a modified example of the exhaust heat recovery system according to the present invention.

FIG. 7 is a schematic configuration diagram of a main part showing another modified example of the exhaust heat recovery system according to the present invention.

[Explanation of symbols]

 1 ... Miller cycle gas engine 2 ... Transmission clutch 3 ... Generator 5a ... Engine hot water supply pipe 6 ... Circulation piping 7 ... First heat exchanger 9 ... Steam generator 10 ... Steam turbine 11 ... Condenser 12 ... Supercharge Machine 13 ... Exhaust gas supply pipe 14 ... Absorption refrigerator 15 ... Regenerator 17 ... Absorber 24 ... Second heat exchanger 25 ... Fuel cell 26 ... Steam supply pipe 27 ... Fuel cell hot water supply pipe 31 ... Generator

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location F02G 5/04 B F25B 27/02 K H01M 8/04 J

Claims (5)

[Claims] 1. An exhaust system characterized in that a steam turbine is provided in a circulation pipe for a working fluid connected to a steam generator using exhaust gas from an engine as a heat source, and a supercharger of the engine is linked to the steam turbine. Heat recovery system. 2. The exhaust heat recovery system according to claim 1, wherein an engine hot water supply pipe for supplying hot water discharged from the engine is connected to a regenerator of an absorption chiller and preheated by the regenerator. An exhaust heat recovery system that supplies liquid as a working fluid to a steam generator. 3. An exhaust heat recovery system, wherein the engine according to claim 1 or 2 is a Miller cycle gas engine. 4. A fuel cell hot water supply pipe for supplying hot water discharged from a fuel cell is connected to the regenerator according to claim 2 or 3, and a heat exchanger is provided between the regenerator and the steam generator. And a steam supply pipe for supplying low-pressure steam discharged from the fuel cell to the heat exchanger. 5. An exhaust heat recovery system characterized in that a steam turbine is provided in a working fluid circulation pipe connected to a steam generator using exhaust gas from an engine as a heat source, and a generator is driven by the steam turbine.