JP4931614B2 - Cogeneration system using cold heat of liquefied gas and its operation method - Google Patents

Description

The present invention relates to a cogeneration system including a Stirling engine, and more particularly, to a cogeneration system using cold heat of liquefied gas that can be generated by a Stirling engine using cold energy of liquefied gas such as natural gas, and an operation method thereof. related to.

The Stirling engine has a configuration similar to that of an internal combustion engine including a reciprocating piston and a cylinder. The engine has a structure in which a piston is moved by heating and cooling the working gas sealed in the cylinder from the outside. The Stirling engine, since the explosion pronunciation does not occur, it is very quiet. The Stirling engine changes the gas smoothly without exploding, so it is in principle a very heat efficient engine. Stirling engines do not produce harmful components caused by explosions even when fuel is used. Clean exhaust gas can be obtained by quiet combustion. The Stirling engine moves when it creates a temperature difference, so it is possible to use various heat sources such as biomass, all combustible materials, geothermal heat, solar heat, and so on.

A cogeneration system that generates electric power by rotating a generator with this Stirling engine has been proposed. As shown in the explanatory diagram of FIG. 5, as a high-temperature heat source for heating the working gas of the Stirling engine 2 from the outside, the fuel is burned by the heater unit 7 with a burner or the like to generate “hot”, while the outside air is “cold”. There is a cogeneration system that drives the Stirling engine 2 used as a generator to generate electric power with the generator 1.

  On the other hand, as shown in the explanatory diagram of FIG. 6, in the system in which the gas engine 5 is driven by city gas or the like and the generator 1 is rotated to generate power, the boiler 8 is heated by the exhaust heat of the gas engine 5, There is a cogeneration system that makes effective use of.

Various techniques for improving the power generation efficiency of such a cogeneration system including a Stirling engine have been proposed. For example, as shown in Japanese Patent Laid-Open No. 2000-213418, “Heat source system using low-temperature steam and cogeneration system using the same” in Patent Document 1, in the Stirling engine, the entire working gas space including the low temperature chamber and the high temperature chamber is Blowing low-temperature steam as working gas into the low-temperature chamber near the minimum, and a portion of the internal vapor as working gas from the low-temperature chamber in the vicinity where the total working gas space is maximum and the subsequent space reduction process By providing a valve means for converting the steam engine to be discharged, and compressing the low-temperature steam delivered from the low-temperature steam generator by a separate compressor using this Stirling engine as the drive source, the low-temperature steam is heated and heated. In addition to generating high-temperature steam to be supplied to the customer, a part of the low-temperature steam sent from the low-temperature steam generator is Stirling air by the valve means. Heat source system of the low-temperature steam usage that is a configuration to be used as blowing steam into the gin has been proposed.
JP 2000-213418 A

Similarly, as shown in Japanese Patent Application Laid-Open No. 2000-213419, “Heat Source System Utilizing Low Temperature Heat, and Cogeneration System Using the Same”, a high temperature endothermic chamber including a high temperature heater and a low temperature heater are provided. Regenerative heat exchange of working gas in a state where a low-temperature heat absorption chamber, a high-temperature heat dissipation chamber with a high-temperature radiator, and a low-temperature heat dissipation chamber with a low-temperature radiator are in communication with each other with a regenerative heat exchanger interposed between them. Endothermic side working gas moving process to move from high temperature heat radiating chamber and low temperature heat radiating chamber to high temperature endothermic chamber and low temperature endothermic chamber through working chamber, working gas expansion process with heat collection from high temperature heater and low temperature heater, working gas The process of moving the working gas on the heat release side that moves from the high-temperature endothermic chamber and the low-temperature endothermic chamber through the regenerative heat exchanger to the high-temperature heat-dissipating chamber and the low-temperature heat-dissipating chamber, and the working gas pressure with heat dissipation A cycle execution unit that repeats the process in that order and performs a Stirling cycle and a reverse Stirling cycle in parallel is provided, and heat exchange is performed between the high-temperature heating medium and the working gas for heat input in the high-temperature heater, and used in the low-temperature heater. Heat exchange between the working gas and the low-temperature heat medium that holds the target low-temperature heat, heat exchange between the working medium and the heat medium for heating output supplied to the heat demand in the high-temperature radiator, and cooling for heat radiation in the low-temperature radiator A heat source system using low-temperature heat, which is configured to exchange heat between the heat medium and the working gas, has been proposed.
JP2000-213419

  However, in the above-described system in which the gas engine 5 is driven by the city gas or the like and the generator 1 is rotated to generate electricity, the exhaust heat of the gas engine 5 is mainly used for heating the boiler 8 and is efficient. It was not a good power generation system.

  In addition, “Heat source system using low-temperature steam and cogeneration system using the same” in Patent Document 1 or “Heat source system using low temperature heat and a cogeneration system using the same” in Patent Document 2 are used for using low-temperature heat. It has characteristics, and the liquefied gas was not effectively used. Furthermore, the required amount of electric power and the amount of steam generated by the boiler were not adjusted.

  The inventor of the present invention paid attention to utilizing the cold energy of the liquefied gas as the cold energy of the Stirling engine, and also utilizing the exhaust heat from the equipment as the warm temperature of the Stirling engine.

  The present invention has been developed to solve such problems. That is, an object of the present invention is to utilize the cold energy of liquefied gas such as natural gas, and to effectively use the cold energy of liquefied gas by combining the gas engine with a Stirling engine and to exhaust gas from the gas engine. It is intended to provide a cogeneration system using cold heat of liquefied gas that can be used to generate power with high efficiency by using the heat of Stirling engine and an operation method thereof.

Cogeneration systems utilizing cold heat of the liquefied gas of the present invention, the generator (1) and the Stirling engine (2) for rotating the, vaporizing liquefied gas (3), a vaporizer for generating the fuel gas (4) And a gas engine (5) driven by the fuel gas to rotate a separately installed generator (1), a boiler (8) heated using the exhaust gas of the gas engine (5), and A boiler flow path (E1) in which the boiler (8) is connected via a damper (10) to the gas engine (5) and the exhaust gas delivery side; and the gas engine (5) and the exhaust gas delivery side. the Stirling engine (2) a Stirling engine flow path by connecting interposed the damper (10) and (E2), comprising a cold heat for driving the Stirling engine (2), said liquefied gas (3 Using the cold energy of the, heat for driving the Stirling engine (2) is to use the heat of exhaust gas of the gas engine (5), when not using the vapor of the boiler (8), each damper (10 , 10) by changing the open / close angle of the gas engine (5) to supply the total amount of exhaust gas from the Stirling engine flow path (E2) to the Stirling engine (2) while using the steam of the boiler (8) By changing the open / close angle of each damper (10, 10) and distributing and supplying the exhaust gas of the gas engine (5) from the boiler flow path (E1) to the boiler (8), power generation by the Stirling engine (2) The amount (BkW) is configured to be adjustable .

  As the liquefied gas (3), natural gas such as LNG (Liquid Natural Gas) or NGH (Natural Gas Hydrate) can be used.

Operation method in cogeneration system of the present invention, the generator (1) the cold of the Stirling engine (2) for rotating utilizes cold energy of the liquefied gas (3), the heat is separately installed electric generator ( together to generate power using the exhaust gas of the gas engine rotating (5) 1), a driving method in cogeneration systems for heating the boiler (8), when driving the Stirling engine (2), wherein When the steam of the boiler (8) is not used, the entire amount of exhaust gas of the gas engine (5) is supplied to the Stirling engine (2) as warm heat, and when the steam of the boiler (8) is used, the boiler (8 ) To distribute and supply the exhaust gas of the gas engine (5) .

Further, the refrigerant cooled by vaporizing the liquefied gas (3), wherein to monitor the temperature difference between the heat medium heated by the boiler (8) for heating in the exhaust gas of the gas engine (5), the temperature and supply amount It is preferably used as “cold heat” and “hot heat” for controlling and driving the Stirling engine (2) .

In the system configured as described above, “cold heat” that drives the Stirling engine (2) that rotates the generator (1) is generated when the liquefied gas (3) is vaporized by the vaporizer (4) to generate fuel gas. Using cold energy, “warmth” uses the thermal energy of the exhaust gas of the gas engine (5) that rotates the generator (1). Since a system that utilizes the "thermal" both waste heat as a "cold" it is possible to power generation with high efficiency. In particular, the cold energy of the liquefied gas (3) can be used effectively, and contributes to the reduction of environmental load on a global scale.
Further, by distributing and supplying the exhaust gas of the gas engine (5) to the Stirling engine (2) and the boiler (8), the power generation amount (BkW) by the Stirling engine (2) can be adjusted.

  In the operation method having the above configuration, the exhaust function of the gas engine (5) is supplied to the boiler (8) when the steam load (boiler use steam amount) is high, and the other is supplied to the Stirling engine (2). It is possible to generate electricity with high efficiency. That is, when the required electrical output is small, the entire amount of exhaust gas from the gas engine (5) is supplied to the boiler (8). Conversely, when the required electrical output is large, the entire amount of exhaust gas from the gas engine (5) is supplied to the Stirling engine (2) to generate electricity. Thereby, it can be fluctuated according to the amount of steam used in the boiler (8).

Further, when the apparatus scale of the Stirling engine (2) is large, employ temperature heat of the exhaust gas cooling energy and gas engines of liquefied gas (3) (5), a high temperature difference between the heat such as a boiler (8) Therefore, the necessary temperature difference can be set easily. For example, when the material metal of the Stirling engine (2) cannot withstand the heat difference between cold and hot, the temperature difference can be easily set.
Even when the consumption amount of the liquefied gas (3) fluctuates greatly, the necessary amount of power can be constantly supplied by adjusting the power generation amount of the Stirling engine (2) and the gas engine (5).

  The cogeneration system using the cold heat of the liquefied gas of the present invention includes a Stirling engine that rotates a generator, a vaporizer that vaporizes the liquefied gas to generate fuel gas, and a fuel gas for rotating the generator. And a gas engine driven by the system. The cold energy that drives the Stirling engine uses the cold energy of the liquefied gas, and the hot energy uses the exhaust gas of the gas engine.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a circuit diagram showing a cogeneration system using cold heat of liquefied gas according to Embodiment 1 of the present invention.
The cogeneration system using the cold heat of the liquefied gas according to the present invention includes a Stirling engine 2 that rotates the generator 1, a vaporizer 4 that vaporizes the liquefied gas 3 to generate fuel gas, and another generator 1. It is a device provided with a gas engine 5 driven by fuel gas for rotation.

  The Stirling engine 2 uses a working gas such as helium and has the same configuration as an internal combustion engine including a reciprocating piston and cylinder. The working gas sealed in the cylinder is heated by external heat and cooled by cold to cause the piston to move. A generator 1 that rotates by the Stirling engine 2 to generate electric power is provided.

  The vaporizer 4 is a device that heats and regasifies the liquefied gas 3 such as LNG or NGH. There are various methods for regasification. For example, a liquefied gas 3 such as LNG that flows from the bottom to the top in a combination of a shell and tube method that vaporizes using an intermediate heat medium or water as a heat source, or a combination of a number of panels in which vertical tubes are arranged in a row. It is possible to use a vaporizer 4 of an open rack type or the like in which a heating medium is flowed down from the outside with a burner 6 or the like to heat and vaporize.

  The liquefied gas 3 includes LNG (Liquid Natural Gas), NGH (Natural Gas Hydrate), and the like. These liquefied gases 3 are cooled to a temperature of −162 ° C. in LNG in order to increase the transport efficiency. NGH is cooled to a temperature of −20 ° C. In the present invention, cold energy generated by heat exchange when vaporizing the cooled liquefied gas 3 is used. In addition, if it is the liquefied gas 3 made into the cooling state, it is also possible to use gas other than these LNG or NGH.

The gas engine 5 is an engine driven by fuel gas, and includes a generator 1 that is rotated by the gas engine 5 to generate electric power. As the fuel gas, a gas obtained by vaporizing the liquefied gas 3 with the vaporizer 4 is used. The generator 1 is generated by each is distinct from the generator 1 is driven by a Stirling engine 2.

In the system configured as described above, the cooling energy for driving the Stirling engine 2 uses the cooling energy of the liquefied gas 3. On the other hand, the heat that drives the Stirling engine 2 uses the exhaust gas of the gas engine 5. As shown in FIG. 1, the cold energy from the liquefied gas 3 uses the vaporized −10 ° C. fuel gas as it is as “cold heat” of the Stirling engine 2. The fuel gas which has been subjected to heat exchange in the Stirling engine 2 and brought to room temperature is burned in the heater unit 7 by the burner 6 and is used as “warm heat” for driving the Stirling engine 2.

  The power generation amount can be adjusted by the two generators of the Stirling engine 2 of the present invention and the generator 1 of the gas engine 5. In general, since the Stirling engine 2 has only an output of several tens to several hundred kW, it can be supplemented by the generator 1 of the gas engine 5. When the exhaust gas of the gas engine 5 increases, the exhaust heat can be used to increase the output of the Stirling engine 2 and the power generation amount can be increased.

FIG. 2 is a circuit diagram illustrating a modification of the cogeneration system using the cold heat of the liquefied gas according to the first embodiment.
The cold energy from the liquefied gas 3 can be utilized as “cold heat” of the Stirling engine 2 through a refrigerant as shown in FIG. Examples of the refrigerant include air and helium gas. By using the refrigerant in this way, it becomes possible to accurately adjust the temperature of “cold heat”. The temperature and supply amount of this refrigerant are controlled by an adjusting device 9 provided between the vaporizer 4 and the Stirling engine 2.

FIG. 3 is a circuit diagram showing a cogeneration system using cold heat of liquefied gas equipped with the boiler of the second embodiment. FIG. 4 is an explanatory flow diagram that takes into consideration the balance between the required amount and the required power generation amount of the boiler according to the second embodiment.
The cogeneration system of Example 2 further includes a boiler 8 that is heated with the exhaust gas of the gas engine 5. A boiler 8 was disposed on the exhaust gas delivery side (downstream) of the gas engine 5 with a damper 10 interposed. Steam is generated from this boiler 8 and used as energy.

  Therefore, in the cogeneration system of the second embodiment, when the Stirling engine 2 is driven, the exhaust gas of the gas engine 5 is supplied to the boiler 8 or the Stirling of the exhaust gas of the gas engine 5 according to the amount of steam used by the boiler 8. Distribute and supply to the engine 2.

For example, when the steam of the boiler 8 heated by the exhaust gas of the gas engine 5 is used , the entire amount of the exhaust gas is supplied to the boiler 8 through the flow path indicated by the dotted arrow E1 in FIG. In this case, the "warm thermal" Stirling engine 2 is normal temperature (20 ° C.), "cold heat" is -100 ° C.. In other words, since the temperature difference between 20 ° C. and −100 ° C. is only 120 ° C., the electrical output of the generator 1 is small.

On the other hand, when the steam of the boiler 8 heated by the exhaust gas of the gas engine 5 is not used , the entire amount of the exhaust gas is supplied to the Stirling engine 2 through the flow path indicated by the dotted arrow E2 in FIG. At this time, the “warmth” of the Stirling engine 2 is 400 ° C., and the “cold heat” is −100 ° C. That is, since the temperature difference is 500 ° C. between 400 ° C. and −100 ° C., the electrical output of the generator 1 is increased.
The numbers of “cold heat” at −100 ° C. and “warm heat” at 400 ° C. are examples, and it is needless to say that the numbers are not limited to these numbers.

Thus, when the required electrical output is large, the entire amount of exhaust gas from the gas engine 5 is supplied to the Stirling engine 2 to generate power. Thereby, it can be fluctuated according to the amount of steam used by the boiler 8. The power generation amount (AkW) by the gas engine 5 and the power generation amount (BkW) by the Stirling engine 2 in FIG. 3 are adjusted. At this time, the power generation amount (BkW) by the Stirling engine 2 is mainly controlled with respect to the required power amount, and the power generation amount (AkW) by the gas engine 5 is controlled.
Furthermore, it is also possible to supply the steam (heat medium) of the boiler 8 to the Stirling engine 2 as “heat”. This heating medium is provided with an adjusting device 9 for controlling the temperature and supply amount. An adjusting device 9 for controlling the temperature and the supply amount is also provided in the refrigerant delivery pipe of the vaporizer 4. The supply amount is adjusted simply by changing the opening / closing angle of the damper 10.

  In the operation method of the present invention, even when the consumption amount of the liquefied gas 3 such as LNG fluctuates greatly, the necessary amount of power is always supplied by adjusting the power generation amount of the Stirling engine 2 and the gas engine 5. Can do.

  Note that the present invention uses the cold energy of the liquefied gas 3 such as natural gas, and combines the Stirling engine 2 with the gas engine 5 to effectively use the cold energy of the liquefied gas 3, and the gas engine. As long as it is a system or an operation method that can generate power with high efficiency using the exhaust gas of No. 5 for the heat of the Stirling engine 2, it is not limited to the embodiment of the invention described above, and does not depart from the gist of the invention. Of course, various changes can be made.

  The cogeneration system using the cold heat of the liquefied gas and the operation method thereof according to the present invention can be used as power generation equipment for general households. In addition, a large amount of power can be supplied by arranging a plurality of the systems, and the system can also be used as power generation equipment such as a factory.

It is a circuit diagram which shows the cogeneration system using the cold heat of the liquefied gas of Example 1 of this invention. It is a circuit diagram which shows the modification of the cogeneration system using the cold heat | fever of the liquefied gas of Example 1. FIG. It is a circuit diagram which shows the cogeneration system using the cold heat | fever of the liquefied gas provided with the boiler of Example 2. FIG. It is an explanatory flow figure in consideration of the balance of the required amount and required power generation amount of the boiler of Example 2. It is explanatory drawing of the cogeneration system which consists of a conventional Stirling engine. It is explanatory drawing of the cogeneration system which consists of the conventional gas engine.

1 Generator 2 Stirling Engine 3 Liquefied Gas 4 Vaporizer 5 Gas Engine 8 Boiler

Claims (4)

A Stirling engine (2) for rotating the generator (1);
A vaporizer (4) for vaporizing the liquefied gas (3) to produce fuel gas;
A gas engine (5) driven by the fuel gas to rotate a separately installed generator (1);
A boiler (8) for heating using the exhaust gas of the gas engine (5);
A boiler flow path (E1) in which the boiler (8) is connected via a damper (10) to the gas engine (5) and the exhaust gas delivery side;
A Stirling engine flow path (E2) in which the Stirling engine (2) is connected via a damper (10) on the gas engine (5) and the exhaust gas delivery side ;
The cold energy that drives the Stirling engine (2) uses the cold energy that the liquefied gas (3) has,
The heat that drives the Stirling engine (2) uses the heat of the exhaust gas of the gas engine (5) ,
When the steam of the boiler (8) is not used, the opening and closing angles of the dampers (10, 10) are changed to transfer the total amount of exhaust gas of the gas engine (5) from the Stirling engine flow path (E2) to the Stirling engine (2 When the steam of the boiler (8) is used, the open / close angle of each damper (10, 10) is changed, and the exhaust gas of the gas engine (5) is sent from the boiler flow path (E1) to the boiler. (8) A cogeneration system using the cold of liquefied gas, characterized in that the power generation amount (BkW) by the Stirling engine (2) can be adjusted by distributing and supplying to (8) .   The cogeneration system using the cold energy of liquefied gas according to claim 1, wherein natural gas such as LNG (Liquid Natural Gas) or NGH (Natural Gas Hydrate) is used as the liquefied gas (3). The cold energy of the Stirling engine (2) that rotates the generator (1) uses the cold energy of the liquefied gas (3), and the thermal energy of the gas engine (5) that rotates the separately installed generator (1). An operation method in a cogeneration system that generates power using exhaust gas and heats a boiler (8),
When driving the Stirling engine (2), when the steam of the boiler (8) is not used, the entire amount of exhaust gas of the gas engine (5) is supplied to the Stirling engine (2) as hot heat, and the boiler ( When using the steam of 8), the exhaust gas of the gas engine (5) is distributed and supplied to the boiler (8) . The temperature difference between the refrigerant vaporized and cooled by the liquefied gas (3) and the heating medium heated by the boiler (8) heated by the exhaust gas of the gas engine (5) is monitored, and the temperature and supply amount are controlled. The operation method in the cogeneration system according to claim 3, wherein the operation method is used as “cold heat” and “hot heat” for driving the Stirling engine (2) .

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