JP2008175151A - Cogeneration system using cold of liquefied gas and method for operating same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently generate power by effectively using cold energy which liquefied gas has, and using exhaust gas of a gas engine in heating a Stirling engine by using cold energy which liquefied gas such as natural gas has and combining a gas engine to a Stirling engine. <P>SOLUTION: This system is provided with the Stirling engine 2 rotating a generator 1, a carburetor 4 carbureting liquefied gas 3 and forming a fuel gas, and the gas engine 5 driving with the fuel gas for rotating the generator 1. Cold energy which the liquefied gas 3 has is used for cold for driving the Stirling engine 2 and exhaust gas of the gas engine 5 is used for heating. <P>COPYRIGHT: (C)2008,JPO&INPIT

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. It is about.

  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. This Stirling engine is extremely quiet because the Stirling engine does not generate explosion sounds. 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 a burner or the like to generate “hot” in the heater unit 7, 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 method of driving the gas engine 5 with city gas or the like and rotating the generator 1 to generate electric power, the boiler 8 is heated by the exhaust heat of the gas engine 5 to generate 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 carries out a Stirling cycle and a reverse Stirling cycle in parallel is provided. 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.

According to the system of the present invention, a Stirling engine (2) for rotating a generator (1),
A vaporizer (4) for vaporizing the liquefied gas (3) to generate fuel gas, and a gas engine (5) driven by the fuel gas to rotate the generator (1), The cooling energy for driving the Stirling engine (2) uses the cooling energy of the liquefied gas (3), and the heating energy for driving the Stirling engine (2) uses the exhaust gas of the gas engine (5). There is provided a cogeneration system that uses the cold heat of a liquefied gas that is configured.

It is preferable to further include a boiler (8) for heating using the exhaust gas of the gas engine (5).
As the liquefied gas (3), natural gas such as LNG (Liquid Natural Gas) or NGH (Natural Gas Hydrate) can be used.

According to the operation method of the present invention, the cold energy of the Stirling engine (2) that rotates the generator (1) uses the cold energy of the liquefied gas (3), and the heat is generated separately from the generator (1). In the cogeneration system that heats the boiler (8) while generating power using the exhaust gas of the gas engine (5) that rotates the boiler (8) when the Stirling engine (2) is driven. According to the amount of steam used in 8), the exhaust gas of the gas engine (5) is supplied to the boiler (8), or the exhaust gas of the gas engine (5) is distributed and supplied to the Stirling engine (2). An operating method in a characteristic cogeneration system is provided.
For example, when the amount of steam used by the boiler (8) heated by the exhaust gas of the gas engine (5) is larger than a predetermined value, the entire amount of the exhaust gas is supplied to the boiler (8), and the exhaust gas of the gas engine (5) When the amount of steam used in the boiler (8) heated at is less than a predetermined value, the entire amount of the exhaust gas can be used as cold heat for the Stirling engine (2).

  The cooling energy of the Stirling engine (2) that rotates the generator (1) uses the cooling energy of the liquefied gas (3), and the temperature of the gas engine (5) rotates the generator (1) that is installed separately. ) In the cogeneration system that generates power using the exhaust gas and heats the boiler (8), wherein the liquefied gas (3) is vaporized and cooled, and the gas engine (5) Monitor the temperature difference with the heating medium heated by the boiler (8) heated with exhaust gas, and if there is a temperature difference greater than a predetermined value, use these as "cool" and "heat" after exchanging heat in advance It is preferable to do.

  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 both “cold heat” and “warmth” systems use exhaust heat, highly efficient power generation is possible. 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.

  In the operation method having the above configuration, the exhaust gas 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).

Moreover, when the scale of the Stirling engine (2) is large, a high temperature difference such as the cold energy of the liquefied gas (3), the exhaust heat of the gas engine (5), the temperature of the boiler (8), etc. can be employed. 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 of the present invention rotates the Stirling engine 2 that rotates the generator 1, the vaporizer 4 that vaporizes the liquefied gas 3 to generate fuel gas, and the generator 1. Therefore, it is a device provided with a gas engine 5 driven by fuel gas.

  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 separate from the generator 1 driven by the Stirling engine 2 and generates power by each.

  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 that has been subjected to heat exchange in the Stirling engine 2 and brought to room temperature is combusted in the burner 6 and is used as “warm heat” in the heater unit 7 to drive 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. The heating medium is supplied from the boiler 8 to the Stirling engine 2 as “warm heat”. This heating medium is provided with an adjusting device 9 for controlling 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 simply adjusted by changing the opening / closing angle of the damper 10.

  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 amount of steam used by the boiler 8 heated by the exhaust gas of the gas engine 5 is greater than a predetermined value, the entire amount of exhaust gas is supplied to the boiler 8 through the flow path indicated by the dotted arrow E1 in FIG. At this time, the “cold heat” of the Stirling engine 2 is room temperature, and the “warm 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 amount of steam used by the boiler 8 heated by the exhaust gas of the gas engine 5 is less than a predetermined value, the entire amount of 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.

  In the operation method of the present invention, even when the consumption 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.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Generator 2 Stirling engine 3 Liquefied gas 4 Vaporizer 5 Gas engine 8 Boiler

Claims (6)

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 the generator (1),
The cooling energy for driving the Stirling engine (2) uses the cooling energy of the liquefied gas (3), and the heating energy for driving the Stirling engine (2) uses the exhaust gas of the gas engine (5). A cogeneration system using the cold heat of liquefied gas, characterized in that The cogeneration system using cold of liquefied gas according to claim 1, further comprising a boiler (8) for heating using the exhaust gas of the gas engine (5). 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), depending on the amount of steam used by the boiler (8),
An operation method in a cogeneration system, characterized in that exhaust gas from the gas engine (5) is supplied to a boiler (8), or exhaust gas from the gas engine (5) is distributed and supplied to the Stirling engine (2). When the amount of steam used in the boiler (8) heated by the exhaust gas of the gas engine (5) is greater than a predetermined value, the entire amount of the exhaust gas is supplied to the boiler (8),
When the amount of steam used by the boiler (8) heated by the exhaust gas of the gas engine (5) is less than a predetermined value, the total amount of the exhaust gas is used as cold heat of the Stirling engine (2). The operation method in the cogeneration system according to Item 4. 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),
The temperature difference between the refrigerant that has evaporated and cooled 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. In some cases, the operation method in the cogeneration system is characterized in that these are used as “cold heat” and “warm heat” after exchanging heat in advance.

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