JP2003288907A - Lng hybrid vaporizing power generation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate power by effectively utilizing exhaust heat of a normal pressure solid electrolyte fuel cell and LNG cold. <P>SOLUTION: Normal pressure high temperature exhaust gas is introduced from the normal pressure solid electrolyte fuel cell 2 into a gas turbine 3. Back pressure of the gas turbine 3 is kept in negative pressure with compressors 6, 7. Suction air of the compressors 6, 7 is cooled by utilizing cold of LNG in coolers 8, 9 to enhance efficiency. Since the exhaust gas becomes normal temperature and atmospheric pressure, the exhaust gas is cooled to -100°C and lower by utilizing the cold of the LNG in an air direct cooling device 10, and effectively utilized as cold. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an atmospheric pressure solid oxide fuel cell (SOFC) which uses liquefied natural gas (hereinafter abbreviated as “LNG”) as a fuel to generate electric power, and produces exhaust gas and LNG cold heat. The present invention relates to an LNG hybrid vaporization power generation device that uses a gas turbine to generate power.

[0002]

2. Description of the Related Art Conventionally, LNG has been widely used as a fuel for thermal power generation and a raw material for city gas. LNG is
It is a low-temperature liquid at atmospheric pressure of -159 ° C, and when it is used as a fuel or a raw material in a gaseous state at room temperature, cold heat is obtained. Although LNG cold heat power generation equipment that uses this cold heat effectively to generate electricity is also being constructed, in Japan, a highly efficient gas turbine combined cycle (GT) is used for thermal power generation.
CC) has been adopted and is no longer being constructed. In the gas turbine combined cycle, steam is generated by the exhaust heat of the gas turbine, and the steam turbine also generates electricity to improve efficiency.

As a power generation method utilizing the cold heat of LNG,
International Publication No. WO 00/37785 discloses a method of generating power using a gas turbine having a negative back pressure instead of the existing high efficiency gas turbine combined cycle steam turbine. Exhaust gas from a gas turbine having a negative back pressure is cooled and compressed by a compressor over a plurality of stages to reach room temperature and atmospheric pressure. By cooling, the temperature of the exhaust gas sucked into the compressor is lowered, and the compression power is reduced. It has been proposed to use LNG together with seawater as a cooling heat source. This system can be considered as a reverse Brayton cycle because the compressor is used on the exhaust gas side of the gas turbine, as opposed to the Brayton cycle that uses the exhaust heat of the gas turbine.

[0004]

[Problems to be Solved by the Invention] Large-scale and economically effective use of cold energy is an important factor for energy companies that use LNG, such as power generation and city gas supply, to implement COP3 (3rd Conference of the Framework Convention on Climate Change: 1997). It is also an urgent task to achieve the consensus goal of the Kyoto Conference on Global Warming Prevention (December 2014). In particular, for the unification of city gas types,
Small and medium-sized gas companies are introducing LNG. However, at a base handling LNG, the transported LNG is used as a fuel to generate hot water in a boiler, which is used for defrosting an air-cooled LNG vaporizer and as a heat source in winter, and the cold heat of LNG is hardly used. At the LNG base of electric power companies, with the introduction of the combined cycle, LNG
Almost no cold heat is used.

In view of the current situation, it is necessary to urgently develop a practical use of LNG cold heat by a method using a gas turbine having a negative back pressure. However, there are the following problems.

In the back pressure negative pressure turbine, the energy density of the high temperature gas to be introduced is 1 / th that of the gas turbine of the same size.
Since it is 3 or less, the output of the gas turbine is also 1/3 or less, and it is necessary to modify the compressor on the downstream side to an intermediate cooling type, which requires development cost. Especially the latest 150
In the 0 ℃ class high efficiency combined cycle, the gas turbine pressure ratio is large and the turbine outlet exhaust gas temperature is 600 ℃.
It is the following. Therefore, even if the atmospheric pressure exhaust gas at 600 ° C. or lower is subjected to energy recovery in the reverse Brayton cycle, it is considered that the economy is poor.

When the temperature of the exhaust gas for intercooling is lowered, the water vapor in the exhaust gas condenses, so that a system for extracting it midway is required. If you raise the exhaust gas temperature to save this,
The compression power increases and the power generation efficiency decreases. Further, in the system of FIG. 18 on the rear side of the international publication where the intermediate cooling is performed by LNG, frost and icing are attached to the heat transfer tube that first exchanges heat with LNG, and heat transfer inhibition and pressure loss on the exhaust gas side increase with time. However, stable operation may not be possible.

In order to prevent global warming, fuel cells, which can generate electricity by reducing carbon dioxide emissions, are also drawing attention. In particular, an atmospheric pressure solid oxide fuel cell (SOF
C: Solid Oxide Fuel Cell) can obtain exhaust gas at a normal temperature and high temperature of 820 ° C., so that there is a possibility of effective utilization of LNG cold heat in combination with the reverse Brayton cycle.

An object of the present invention is to provide an LNG hybrid gasification power generation device capable of generating power by effectively utilizing the exhaust heat of the atmospheric pressure type solid oxide fuel cell and the LNG cold heat.

[0010]

SUMMARY OF THE INVENTION The present invention is directed to an atmospheric pressure solid electrolyte fuel cell, a gas turbine for driving a generator using exhaust gas from the atmospheric pressure solid electrolyte fuel cell as a power source, and an exhaust gas from the gas turbine. A first cooler for cooling, a first compressor for compressing the exhaust gas cooled by the first cooler, a second cooler for cooling the exhaust gas compressed by the first compressor, A second compressor for compressing the exhaust gas cooled by the second cooler, and the cold heat obtained when the LNG is vaporized is used for the multi-stage intercooling including the first and second coolers. The LNG hybrid gasification power generation device is characterized in that the exhaust gas is discharged at room temperature and atmospheric pressure while maintaining a negative pressure on the downstream side of the gas turbine by a plurality of stages of compression including the first and second compressors.

According to the present invention, an atmospheric pressure high temperature exhaust gas of, for example, about 600 ° C. can be obtained from the atmospheric pressure type solid electrolyte fuel cell. In a plurality of stages of cooling including the first cooler and the second cooler, the cold heat obtained when vaporizing LNG is used to cool the exhaust gas from the gas turbine. The exhaust gas cooled by each cooler is sequentially compressed by a plurality of stages of compression including the first compressor and the second compressor, and the exhaust gas is kept at a normal pressure and atmospheric pressure while maintaining a negative pressure on the downstream side of the gas turbine. Discharge with.
Since the back pressure of the gas turbine is maintained at a negative pressure, it is possible to operate by using the atmospheric pressure and high temperature exhaust gas from the atmospheric pressure type solid electrolyte fuel cell as a power source and drive the generator to generate electricity. The heat of exhaust gas can be effectively used for vaporizing LNG. The cold heat of LNG can be effectively used to lower the temperature of the exhaust gas sucked into the compressor, reduce the power required to drive the compressor, and improve the power generation efficiency. By combining the back pressure negative pressure gas turbine with the normal pressure type solid electrolyte fuel cell through hybridization, by incorporating it into the LNG vaporization process, it is possible to expect higher power generation efficiency than the pressure type solid electrolyte fuel cell as a whole system, and a cooler. The heat exchanger such as can also be made compact.

Further, according to the present invention, the temperature detecting means for detecting the temperature of the exhaust gas from the gas turbine and the temperature of the exhaust gas detected by the temperature detecting means are cooled to a predetermined temperature capable of preventing drainage of water vapor. As described above, the method further includes LNG introduction amount control means for controlling the introduction amount of LNG using cold heat for the intermediate cooling.

According to the present invention, the temperature of the exhaust gas from the gas turbine is detected by the temperature detecting means, and the LNG introduction amount controlling means controls the introduction amount of LNG using cold heat for the intercooling so that the temperature of the exhaust gas is controlled. It is controlled so as to be cooled to a predetermined temperature that can prevent drainage of water vapor. If the drain adheres to the heat transfer tube of the cooler, etc., it freezes at a low temperature of the LNG and forms frost or icing, which hinders heat transfer and increases pressure loss on the exhaust gas side. Since the drainage is prevented by adjusting the amount of LNG introduced, it is possible to efficiently prevent the heat transfer from being hindered by frost or icing and increase the pressure loss of exhaust gas, and to efficiently use the LNG cold heat.

Further, according to the present invention, the exhaust gas which has reached the normal temperature and atmospheric pressure is used as a heat source to evaporate and raise LNG to a normal temperature.
It is characterized in that it further comprises NG vaporization means.

According to the present invention, the exhaust gas that has reached room temperature and atmospheric pressure can be used as a stable heat source.
Even when direct heat exchange is performed when cooling to a low temperature in order to evaporate and raise the temperature to room temperature, it is possible to stably maintain the conditions for reducing frost and icing.

Further, in the present invention, the LNG vaporization means has an area where the exhaust gas is introduced to perform dehumidification and an area where the air heated by the exhaust gas from the gas turbine is introduced to regenerate the dehumidifying capacity. It is characterized by including a dehumidifying rotor that includes the dehumidified exhaust gas to vaporize LNG, and to cool the exhaust gas to −100 ° C. or lower so that it can be used as low-temperature air.

According to the present invention, the LNG vaporizing means for vaporizing and raising the temperature of LNG to room temperature by using the exhaust gas at room temperature and atmospheric pressure as a heat source has a region for performing dehumidification by introducing the exhaust gas,
A dehumidification rotor including a region in which air heated by exhaust gas from the gas turbine is guided to regenerate the dehumidification capacity. With the dehumidification rotor, the dehumidification capacity in the dehumidification area
Since it can be regenerated by the heat of the exhaust gas from the gas turbine, it is possible to maintain the dehumidifying ability, lower the dew point of the exhaust gas that vaporizes LNG, and prevent growth even if frost or icing occurs.

[0018]

FIG. 1 shows a schematic configuration of an LNG hybrid vaporization power generation apparatus 1 which is an embodiment of the present invention. In the LNG hybrid vaporization power generation device 1, a normal pressure type solid electrolyte fuel cell 2, a gas turbine 3 which uses exhaust gas from the normal pressure type solid electrolyte fuel cell 2 as a power source, a regenerator 4, a generator 5, and a compressor 6 , 7, and coolers 8, 9
And direct air cooler (DAC)
Including 10 and. The gas turbine 3 drives the generator 5 and the compressors 6 and 7. The first cooler 8 cools the exhaust gas from the gas turbine 3 with LNG and vaporizes the LNG. The exhaust gas cooled by the first cooler 8 is the first
It is compressed by the compressor 6. The second cooler 9 cools the exhaust gas compressed by the first compressor 6. The second compressor 7 compresses the exhaust gas cooled by the second cooler 9.

Each of the compressors 6 and 7 and the coolers 8 and 9 is provided in two stages, but the number of stages can be further increased. For the interstage cooling of the multiple stages including the first and second coolers 8 and 9, the cold heat obtained when vaporizing LNG is used to perform the multiple stages of compression including the first and second compressors 6 and 7. The exhaust gas is discharged at room temperature and atmospheric pressure while maintaining a negative pressure on the downstream side of the gas turbine.

In this embodiment, from the atmospheric pressure type solid electrolyte fuel cell 2, exhaust gas at atmospheric pressure and high temperature of, for example, about 820 ° C. can be obtained. The heat of the exhaust gas is used to preheat the normal temperature air supplied to the atmospheric pressure solid electrolyte fuel cell 2 in the regenerator 4 to about 550 ° C. In a plurality of stages of cooling including the first cooler 8 and the second cooler 9, the cold heat obtained when vaporizing LNG is used to cool the exhaust gas from the gas turbine 3. The exhaust gas cooled by each cooler 8 and 9 is
The first compressor 6 and the second compressor 7 are sequentially compressed by a plurality of stages of compression, and the exhaust gas is discharged at room temperature and atmospheric pressure while maintaining a negative pressure on the downstream side of the gas turbine 3.

Since the back pressure of the gas turbine 3 is maintained at a negative pressure, the exhaust gas of normal temperature and high temperature discharged from the normal pressure type solid electrolyte fuel cell 2 through the regenerator 4 is used as a power source to drive the generator 5 Can be driven to generate electricity. The heat of the exhaust gas can be effectively used for the vaporization of LNG, and the cold heat of the LNG lowers the temperature of the exhaust gas sucked into the compressors 6 and 7, and the power required to drive the compressors 6 and 7. Can be effectively used to reduce power consumption and improve power generation efficiency. The back pressure negative pressure gas turbine 3 can be incorporated into the LNG vaporization process by hybridizing it with the normal pressure type solid electrolyte fuel cell 2, and as a whole system, higher power generation efficiency than the pressure type solid electrolyte fuel cell can be expected. Further, a heat exchanger such as a cooler can be made compact.

In the LNG hybrid vaporization power generator 1,
Utilizing the exhaust heat of normal pressure high temperature 820 ° C. discharged from the normal pressure type solid electrolyte fuel cell 2, multi-stage intermediate cooling (25
℃) Compressors 6 and 7 on the wake side negative pressure 0.03MP
Power is generated by driving the gas turbine 3 set to about a (0.3ata). High temperature exhaust gas (600
(° C) can be effectively used for preheating (550 ° C) of room temperature air supplied to the atmospheric pressure solid electrolyte fuel cell 2 and for vaporizing LNG without icing or frosting. When applied to a 300 kW class atmospheric pressure solid electrolyte fuel cell 2 that is expected to be put to practical use,
Power generation efficiency of 60% or more and total thermal efficiency of 100% or more can be expected.

FIG. 2 shows a schematic structure of the air direct cooling device 10 of FIG. The exhaust gas in FIG. 1, which has reached room temperature and atmospheric pressure, is cooled to about 5 ° C. by the precooler 11. The water vapor contained in the exhaust gas is condensed and separated as drain. 5 ° C
The exhaust gas cooled to a certain degree dries while passing through the processing zone 21 of the moisture absorption rotor 12. As the moisture absorption rotor 12, for example, an activated silica honeycomb rotor is used, and the dew point of the machine body to be treated can be lowered to around -30 ° C. The exhaust gas sucked by the processing blower 13 exchanges heat with LNG in the chiller 14 to vaporize LNG, and the exhaust gas is -1.
It is cooled to below 00 ° C. The natural gas vaporized by LNG (hereinafter abbreviated as “NG”) is heated in the precooler 11 to near room temperature.

The moisture absorption rotor 12 rotates about the central axis 12a and is divided into a processing zone 21, a regeneration zone 22 and a cooling zone 23. The processing zone 21 absorbs moisture. In the regeneration zone 22, it is overheated to about 140 ° C. to regenerate its hygroscopic capacity. In the cooling zone 23, the temperature of the moisture absorption rotor 12 which is high for regeneration is lowered. As the heat source for regeneration, the heat of the exhaust gas of the gas turbine of FIG. 1 is used. A part of the high-temperature air preheated by the regenerator 4 is branched, guided to the regeneration zone 22 of the moisture absorption rotor 12, and sucked by the regeneration blower 24 to regenerate the regeneration zone 22.

The reason why the air cooling temperature is set to -100 ° C. is to cope with various cold heat applications including low temperature pulverization. Further, since no intermediate refrigerant is used, the cost and size of the entire apparatus can be reduced. The applicant of the present application discloses an air direct cooling device using the moisture absorption rotor 12 in Japanese Patent Application No. 2000-325909.

FIG. 3 shows an equivalent piping system for analyzing the operation of the LNG hybrid vaporization power generator 1 of FIG. The atmospheric pressure solid electrolyte fuel cell 2 is evaluated as a burner. From the atmospheric pressure type solid electrolyte fuel cell 2, 8.782
An AC power output of × 10 ⁶ kJ can be obtained. A shaft output of 7.030 × 10 ⁶ kJ is obtained from the gas turbine 3.
The efficiency is 85%. The first compressor 6 is 2.111 ×
It requires a power of 10 ⁶ kJ and an efficiency of 80%. The second compressor 7 requires a power of 1.344 × 10 ⁶ kJ and an efficiency of 80%. With the output obtained by subtracting the power of the compressors 6 and 7 from the output of the gas turbine 3, it is possible to drive the generator 5 of FIG. 1 to generate power.

Depending on the temperature of the exhaust gas, LNG is obtained in the intermediate cooling.
The amount of gas introduced is controlled by the LNG control means 30 or the like, and the temperature is cooled to a temperature at which water vapor in the exhaust gas can be prevented from being drained. LNG is vaporized to room temperature using the exhaust gas that has reached room temperature and atmospheric pressure as a heat source. Further, the high temperature air branched from the regenerator 4 is used as a regeneration heat source for the dehumidifying rotor 12.

[0028]

As described above, according to the present invention, power can be generated by driving a gas turbine having a negative back pressure with exhaust gas of normal pressure and high temperature from a normal pressure type solid electrolyte fuel cell. Exhaust gas from the gas turbine can be discharged at normal temperature and atmospheric pressure while reducing the compression power by cooling using LNG cold heat by a plurality of stages of coolers and compressors. The back pressure negative pressure gas turbine can be incorporated into the LNG vaporization process by hybridizing it with a normal pressure type solid electrolyte fuel cell, and high overall power generation efficiency can be expected, and heat exchangers such as coolers can be made compact. You can

Further, according to the present invention, since the exhaust gas is prevented from being drained in the cooler by adjusting the LNG introduction amount, it is possible to prevent heat transfer inhibition due to frost or icing and increase in pressure loss of the exhaust gas, thereby improving efficiency. Well, LNG cold heat can be used.

Further, according to the present invention, the exhaust gas which has reached the normal temperature and atmospheric pressure can be effectively used as a heat source for vaporizing LNG.

Further, according to the present invention, the LNG vaporization means is provided with a dehumidifying rotor for dehumidifying, and the dehumidifying capacity of the region for dehumidifying by introducing the exhaust gas is utilized by utilizing the heat of the high temperature exhaust gas from the gas turbine. So you can play
It is possible to lower the dew point of the exhaust gas that vaporizes LNG so that it does not grow even if frost or frost forms.

[Brief description of drawings]

FIG. 1 is a piping system diagram showing a schematic configuration of an LNG hybrid vaporization power generation device 1 according to an embodiment of the present invention.

FIG. 2 is a piping system diagram showing a schematic configuration of an air direct cooling device 10 of FIG.

FIG. 3 is an equivalent piping system diagram for analyzing the operation of the LNG hybrid vaporization power generation device 1 of FIG.

[Explanation of symbols]

1 LNG hybrid vaporization power generator 2 Atmospheric pressure solid electrolyte fuel cell 3 gas turbine 4 regenerator 5 generator 6,7 compressor 8,9 Cooler 10 Air direct cooling device 11 precooler 12 Dehumidifying rotor 13 Treatment blower 14 Chiller 21 processing zone 22 Playback zone 23 Cooling zone 24 Play Blower

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshinori Hisazumi             4-1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka Prefecture               Within Osaka Gas Co., Ltd. F-term (reference) 5H026 AA06

Claims (4)

[Claims] 1. An atmospheric pressure solid electrolyte fuel cell, and exhaust gas from the atmospheric pressure solid electrolyte fuel cell as a power source,
A gas turbine that drives a generator, a first cooler that cools exhaust gas from the gas turbine, and a first compressor that compresses exhaust gas cooled by the first cooler
Compressor and a second compressor for cooling the exhaust gas compressed by the first compressor
And a second compressor for compressing exhaust gas cooled by the second cooler
And a plurality of stages of intercooling including the first and second coolers,
By utilizing the cold heat obtained when vaporizing NG, exhaust gas is discharged at room temperature and atmospheric pressure while maintaining a negative pressure on the downstream side of the gas turbine by a plurality of stages of compression including the first and second compressors. Characteristic LNG hybrid gasification power generation device. 2. A temperature detecting means for detecting a temperature of exhaust gas from the gas turbine, and a temperature of the exhaust gas detected by the temperature detecting means are cooled to a predetermined temperature capable of preventing drainage of water vapor, The LNG hybrid vaporization power generation device according to claim 1, further comprising LNG introduction amount control means for controlling the introduction amount of LNG that uses cold heat for the intermediate cooling. 3. The LNG hybrid vaporization power generation apparatus according to claim 1, further comprising an LNG vaporization unit that vaporizes and raises LNG to room temperature by using the exhaust gas that has reached the room temperature and atmospheric pressure as a heat source. 4. The LNG vaporization means includes a dehumidification rotor including a region where the exhaust gas is guided to perform dehumidification, and a region where the air heated by the exhaust gas from the gas turbine is guided to regenerate the dehumidification capacity. Is equipped with the dehumidified exhaust gas to vaporize LNG,
The LNG hybrid vaporization power generator according to claim 3, wherein the exhaust gas is cooled to -100 ° C or lower and can be used as low temperature air.