JP2000204909A - Lng cryogenic power generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency of an LNG cryogenic power generation. SOLUTION: A steam injection regenerative gas turbine device 1 is combined into an LNG cryogenic power generation system. Exhaust gas of a gas turbine 4 heats combustion air in an air heater 11 of an heat recovery system 10, generates vapor which is mixed with the combustion air in a boiler 12, heats natural gas in a high pressure natural gas heater 15 and a low pressure natural gas heater 16, heats and vaporizes the LNG in an LNG vaporizer 14, moreover is cooled to a normal temperature in a Freon (R) vaporizer 13, and then moisture content more than the vapor input can be collected. The LNG cryogenic operation is moved to a mixed hydrofluorocarbon(HFC) refrigerant of a Rankine cycle 5 in an LNG main heat exchange 19, and power can be reduced by cooling intake air of an air compressor 2 by an air cooler 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquefied natural gas cold-heat power generation device that generates electric power by utilizing the cold energy of liquefied natural gas (hereinafter sometimes abbreviated as "LNG").

[0002]

2. Description of the Related Art In recent years, LNG has been imported in large quantities because it is used as a raw material for city gas or as a fuel for thermal power generation. The amount of LNG received in Japan in 1997 was about 4.8
It amounts to one million tons, of which about 31 million tons are used as fuel for power generation.

At the LNG liquefaction terminal on the side of the natural gas production area, about 380 kW is required to liquefy one ton of natural gas.
h power is required. Such power translates into the form of LNG cold, which has about 250 kWh / ton of cold exergy at atmospheric pressure. LN
When the pressure of G is increased to, for example, 4 MPa by a pump, about half of the cold exergy can be used before evaporating to room temperature. The remaining cold exergy can be recovered as pressure exergy by gas delivery pressure or natural gas direct expansion turbine. In 1979 after the oil crisis, from the viewpoint of energy saving, various LNG cryogenic power generation technologies were actively developed mainly by electric power companies and city gas companies.
The actual plant has begun operation.

FIG. 7 shows a conventional LNG cryogenic power generation system. The systems marked with an asterisk (*) in the figure have been put to practical use, and in these facilities, seawater is used as a heat source. Domestic LNG cryogenic power generation facilities are installed at city gas supply stations and thermal power stations of electric power companies. At a city gas supply station, there has been a case in which an expansion turbine is installed to recover energy from a pressure difference instead of a governor that adjusts the supply pressure of the city gas by lowering the pressure. The recovery output varies greatly depending on the vapor delivery pressure of LNG and the type of refrigerant used.

[0005] In a city gas company, the Rankine cycle of a single refrigerant or a mixed refrigerant is employed because of the high vaporization delivery pressure of LNG. The applicant of the present application has disclosed, for example,
For example, Japanese Patent Application No. 51707 (Japanese Patent Application No. 7-31654) proposes a liquefied natural gas vaporization power generation apparatus employing a combined cycle combining a gas turbine and a steam turbine and a Rankine cycle of a mixed refrigerant.

[0006]

The recovery power per ton of LNG in a plant using the conventional LNG thermal power generation system is 20 kWh to 40 kWh. On the other hand, since LNG was used for boiler fuel when LNG was introduced, LNG vaporization pressure can be made lower than that of city gas companies, and the natural gas direct expansion cycle is mainly used. In a combined plant with a Rankine cycle, the recovery power per ton of LNG exceeds 60 kWh.

[0007] However, LNG cryogenic power generation in 1990
In the age, construction has been stopped for economic reasons such as stable energy prices and rising construction costs. In particular, a highly efficient combined cycle (hereinafter, Advanced Combine
d Cycle, abbreviated as “ACC”).
An increase in the vaporization pressure of NG and a decrease in the output that can be recovered by LNG cryogenic power generation is also a major factor in which LNG cryogenic power generation is no longer expected.

Incidentally, the power generation output per ton of LNG used as fuel is 6,0 tons in a steam turbine system.
00 kWh. In recent ACC, the turbine inlet combustion temperature (hereinafter may be abbreviated as “TIT”) rises to 1500 ° C. with the improvement of the blade cooling technology and the turbine blade coating technology of the gas turbine, and the power generation output is It is about 7,900 kWh, and the power generation efficiency based on the high calorific value has reached 52%. Of this power output,
The contribution of the LNG due to the vaporization pressure is about 90 kWh, and it can be said that the utilization efficiency of the LNG cryogenic exergy is higher than the conventional net recovery output of about 20 kWh to 60 kWh by the LNG cryogenic power generation.

[0009] The applicant of the present invention has disclosed in Japanese Patent Application Laid-Open No. 9-15170.
In the combined cycle using cold energy proposed in 7,
Construction costs are an issue because relatively expensive steam turbines must be used.

Under these circumstances, at present, a large amount of LN
Cryogenic power generation facilities that utilize G cryogenic heat are no longer being constructed, and most of the LNG cryogenic exergy has been discarded in seawater used as a heat source for LNG vaporization.

[0011] It is an object of the present invention to provide a liquefied natural gas cold heat power generation device capable of generating electricity by effectively utilizing LNG cold heat.

[0012]

SUMMARY OF THE INVENTION The present invention provides a gas turbine which is driven to rotate by combustion gas of a gas fuel, an air compressor which is driven by a rotation output of the gas turbine and compresses combustion air of the gas fuel. Exhaust heat of the exhaust gas from the gas turbine is recovered, the combustion air of the gas fuel compressed by the air compressor is overheated, steam to be mixed with the combustion air is generated, and the temperature of the liquefied natural gas is raised. A waste heat recovery device that vaporizes and further heats, a Rankine cycle in which a mixed chlorofluorocarbon refrigerant that condenses by using the cold heat of liquefied natural gas is circulated, and is supplied to raise the temperature and vaporize in the waste heat recovery device A heat exchanger in which liquefied natural gas exchanges heat with the mixed CFC refrigerant circulating in the Rankine cycle; a CFC expansion turbine driven by the mixed CFC introduced into the heat exchanger; A natural gas expansion turbine driven by the natural gas superheated by the recovery device, a generator driven by the rotation output of the gas turbine and each expansion turbine, and a Rankine cycle mixed Freon refrigerant cooled by a heat exchanger And an air cooler that cools the air drawn into the air compressor.In the Rankine cycle, the mixed Freon refrigerant is led to an exhaust heat recovery device after the air cooler, and the exhaust gas is cooled before being passed to the Freon expansion turbine. It is a liquefied natural gas cold energy utilization power generation device characterized by being guided.

According to the present invention, the output is increased by mixing steam with the combustion gas for driving the gas turbine, and the heat of the exhaust gas from the gas turbine generates steam and superheats the combustion air, thereby reducing the temperature of the combustion gas. The heat exergy of the exhaust gas can be effectively recovered to increase the output of the gas turbine. Further, the cold heat of the liquefied natural gas can be effectively used by the air cooler that cools the intake air to the air compressor using the Rankine cycle, and the power of the air compressor can be reduced. If the amount of water vapor generated by the exhaust gas is reduced, the exergy loss due to the mixture of the water vapor and the air can be suppressed.

Further, in the heat exchanger of the present invention, heat exchange is possible in a state where the temperature difference between the liquefied natural gas and the mixed CFC refrigerant is small.

According to the present invention, heat is efficiently exchanged in the heat exchanger, and the cryogenic energy of the liquefied natural gas is transferred to the mixed CFC refrigerant of the Rankine cycle, and is effectively transmitted through the air cooler and the exhaust heat recovery device. Can be used for

Further, in the present invention, the steam generated in the exhaust heat recovery device is generated by heating water in exhaust gas cooled by the mixed Freon refrigerant.

According to the present invention, the water recovered from the exhaust gas generates steam to be mixed with the combustion gas of the gas turbine, so that a water source for generating steam can be eliminated.

Further, in the present invention, the natural gas expansion turbine is provided in a plurality of stages according to the pressure of the natural gas, and the exhaust gas from the high pressure side natural gas expansion turbine is further heated by the exhaust heat recovery device. The low-pressure side natural gas expansion turbine is rotationally driven.

According to the present invention, power can be recovered by the natural gas expansion turbine according to the pressure at which natural gas is supplied, so that the exergy of liquefied natural gas can be effectively used.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a schematic process flow of a system constituted by combining a gas turbine and high-efficiency LNG cold power generation as an embodiment of the present invention.
This system utilizes a waste heat of a steam injection regenerative gas turbine, and effectively combines a natural gas expansion turbine and a mixed CFC expansion turbine.

The process flow will be described below. The steam injection regeneration type gas turbine device 1 includes an air compressor 2, a combustor 3, and a gas turbine 4. The intake air to the combustor 3 is cooled by the HFC-based mixed chlorofluorocarbon in the air cooler 6 of the Rankine cycle 5 and compressed by the air compressor 2.
Rankine cycle 5 includes a Freon pump 7 and a Freon turbine 8 together with an air cooler 6. The intake air compressed by the air compressor 2 is mixed with the saturated steam in the mixing section 9, further preheated by the exhaust gas of the gas turbine 4 while passing through the air superheater 11 of the exhaust heat recovery device 10, and It is used as combustion air in a combustor 3 using gas as fuel. The combustion gas from the combustor 3 is introduced into the gas turbine 4 and power is recovered. Exhaust gas from the gas turbine 4 is guided to an exhaust heat recovery device 10 where exhaust heat is recovered.

The exhaust heat recovery device 10 includes an air superheater 11, a boiler 12, a freon vaporizer 13, an LNG vaporizer 14, a high-pressure natural gas superheater 15, and a low-pressure natural gas superheater 16, and a gas turbine 4 Heat exchange is performed with the exhaust gas from the exhaust gas, and heating using the thermal energy of the exhaust gas is performed. The hottest exhaust gas discharged from the gas turbine 4 heats the combustion air supplied to the combustor 3 by the air superheater 11. Next, the exhaust gas is boiler 1
2 is heated to generate steam to be mixed in the mixing section 9 with the air after being compressed by the air compressor 2 and before being heated by the air superheater 11. Next, the exhaust gas heats high-pressure and low-pressure natural gas with a high-pressure natural gas superheater 15 and a low-pressure natural gas superheater 16, respectively, and then uses an LNG vaporizer 14 to heat LNG.
Is evaporated. Finally, freon, which is an HFC-based mixed freon, is evaporated in the freon vaporizer 13.

When the exhaust gas is cooled in the course of such heat exchange and heat energy is effectively recovered, moisture can be obtained from the exhaust gas. Natural gas is a mixture of various hydrocarbons such as methane (CH ₃ ), and the exhaust gas from combustion is mainly composed of carbon dioxide gas and water vapor. Further, water vapor mixed with air in the mixing section 9 also comes out as exhaust gas. If the exhaust gas is cooled by the Freon vaporizer 13, the exhaust heat recovery device 10 can also function as a condenser, condensing more steam than the amount of steam mixed in the mixing unit 9, and collecting it as water. it can. The collected water is supplied to the water supply pump 17
The steam is sent to the boiler 12 to generate steam.

The composition of the HFC mixed freon is R1
34a (C ₂ F ₄ H ₂ ) and R23 (CHF ₃ ). This HFC-based mixed chlorofluorocarbon has a characteristic that it does not solidify even when heat is exchanged with LNG. The MOL composition of R134a is 40% or more.
45% is considered optimal.

On the other hand, the LNG main pump 1
The LNG pressurized at 8 is mixed with the liquefied natural gas before entering the LNG main heat exchanger 19. Mixed LN
G is vaporized and raised to room temperature by the LNG vaporizer 14 from the LNG main heat exchanger 19.

The natural gas vaporized and heated in the LNG vaporizer 14 passes through a natural gas preheater 20 and is superheated by exhaust gas from the gas turbine 4 in a high-pressure natural gas superheater 15.
Expanded by the high-pressure natural gas turbine 21, the natural gas preheater 2
0, and then to the medium pressure line 22, for example, 3.5
It is delivered at a pressure of MPa. Some natural gas exiting the high-pressure natural gas turbine 21 is supplied to the low-pressure natural gas superheater 16.
After being reheated in the low pressure natural gas turbine 23, the power is recovered, and after being cooled by the natural gas preheater 20, it is sent out from the low pressure line 24. In the natural gas preheater 20, the high-pressure natural gas and the medium-pressure or low-pressure natural gas exchange heat, the high-pressure natural gas is heated, and the medium-pressure or low-pressure natural gas is cooled.

The vaporized natural gas is supplied to a high-pressure line 25 shown in FIG.
Alternatively, it can be delivered to the low pressure line 24 at a pressure of, for example, 1.8 MPa. The natural gas in the low pressure line 24 is cooled by LNG in the LNG main heat exchanger 19 and condensed, and then pressurized by the LNG recovery pump 26,
It is mixed with LNG supplied from the LNG main pump 18. By controlling the flow rate of circulating low-pressure natural gas,
LNG which is a heat exchange partner of the LNG main heat exchanger 19
And the temperature difference between the LNG and the cooling energy of the LNG can be effectively recovered.

HFC-based mixed chlorofluorocarbon is used in Freon vaporizer 1
3, the power is recovered by the freon turbine 8, and the heat is exchanged in the LNG main heat exchanger 19 to raise the temperature of the LNG and to liquefy it by the LNG.
Further, the HFC-based mixed Freon pressurized by the Freon pump 7 is returned to the LNG main heat exchanger 19 and then introduced into the air cooler 6 in order to increase the circulation amount. The rotational output of the Freon turbine 8, which is an expansion turbine of mixed CFCs, is a high-pressure natural gas turbine 21 which is an expansion turbine of natural gas.
And the rotational output of the low-pressure natural gas expansion turbine 23,
The generator can be driven and converted to electric power. Assuming that each turbine separately drives the generator, the power output can be calculated by multiplying the rotary output by the rotary machine efficiency.

Next, the system of FIG. 1 will be compared with other power generation systems. First, a comparison is made with a cold power generation system using seawater as a heat source. In place of the exhaust gas from the boiler 12 shown in FIG. 1, seawater at a temperature of 20 ° C. is used as a heat source, and natural gas is sent to the medium pressure line 22.
In the case of a vaporization flow rate of 100 ton / h, it is calculated as about 5,500 kW.

The breakdown is that the freon turbine 8 is 1,610
kW, the high-pressure natural gas turbine 21 has 2,640 kW, and the low-pressure natural gas turbine 23 has 1,250 kW. In addition, about 460 kW is required as electric power of the seawater pump for vaporizing LNG.

Although such a system requires three turbines as compared with the power generation output of the hydrocarbon-based mixed refrigerant Rankine cycle of 4,000 kW, it is characterized in that a high power generation output can be obtained at a high delivery pressure. However, when the seawater temperature drops, it is necessary to raise the evaporation temperature of the mixed chlorofluorocarbon above the dew point to protect the turbine blades, and to reduce the chlorofluorocarbon evaporation pressure. As a result, the output of the freon turbine 8 is greatly reduced.
, The total shaft power of the system drops to 4,650 kW.

That is, a system using seawater as a heat source has the following problems. -Since the seawater temperature changes depending on the season, operation at the design point cannot be performed throughout the year, and the power generation output will decrease. -It is necessary to use an open rack type or a titanium tube heat exchanger as the seawater heat exchanger, which is expensive and requires a large installation space.

Next, the exergy evaluation and problems of the LNG thermal power generation cycle using the gas turbine will be described.
LNG thermal power accounts for approximately 25% of the power mix,
It is anticipated that power companies will continue to expand their capacity in the future, along with the improvement in efficiency. In recent years, a system that can obtain high power generation efficiency only with a gas turbine has been developed for reasons such as a reduction in construction cost and inability to use cooling water due to inland. Practical applications include chain and two-fluid cycles that inject high-pressure steam into gas turbines, and larger STIG (Steam Injection).
Gas Turbine) There is a method called a cycle. In addition, development of a high humidity gas turbine (HAT) is also underway.

The exergy evaluation of ACC and Cheng cycle is shown in Table 1 below. The calculation is performed under the following conditions. The evaluation temperature was set to 20 ° C., and the efficiencies of the turbine, air compressor, generator and low-temperature liquefied gas pump were each 88.
%, 88%, 98%, and 60%. -The molar composition of the fuel was methane 88%, ethane 6%, propane 4%, and butane 2%. The high calorific value, low calorific value, and chemical exergy of this fuel are 46.1 MJ, 4
1.3 MJ and 42.3 MJ. The power generation efficiency of the ACC and Cheng cycle based on the high calorific value is 49.6%, 3
3.7%.

A common problem with these gas turbine systems is the rise in intake air temperature in summer. The output of the gas turbine decreases by about 6% when the intake air temperature increases, for example, from 15 ° C. to 35 ° C. For this reason, electric power companies are studying intake cooling of gas turbines using LNG cold heat.

Further, in the chain cycle, higher power generation efficiency can be obtained than in the conventional gas turbine without using a steam turbine or a condenser in comparison with ACC. Exergy loss due to boiler heat transfer and heat release of exhaust gas is large.

[0037]

[Table 1]

The following table 2 shows the system of this embodiment.
Shows the main operating conditions for the LNG vaporization flow rate of 100 ton / h. The inlet temperature of the gas turbine 4 is set to 1,350 ° C. due to recent advances in blade cooling technology and heat resistance of the air preheater.
However, if the air preheating temperature can be further raised, it seems that 1,500 ° C. is possible. Under this condition, the total power generation output of each of the gas turbines 4, 8, 21, and 23 is about 38.4 MW in consideration of the reduction gear efficiency of the LNG cryogenic power generation. The power generation efficiency is 60.0%.

[0039]

[Table 2]

FIG. 2 shows the exergy loss occurring in each device of the system of this embodiment and the exergy that is charged or recovered under the conditions of the LNG vaporization flow rate of 100 ton / h. The value in parentheses in the figure is 1 for the chemical exergy of the fuel.
This is the value when 00% is set.

Based on this figure, the effect of the fusion of the gas turbine and the LNG cryogenic power generation system will be described. The intake air to the steam injection regenerative gas turbine device 1 is H
It is cooled down to -25 ° C by FC mixed freon. Although this cooling effect is as small as 0.3%, the required power of the air compressor 2 is reduced to about 3,000 kW by the effect of the intake air cooling.
Can be reduced.

13.2% of the chemical exergy of the fuel
Is used as a heating heat source for LNG cold energy generation. LN
Since 7.8% of exergy loss due to heat transfer from the G vaporizer 14 and the high-pressure natural gas superheater 15 is lost, L
The effective recovery contribution to NG cryogenic power generation is 5.4%.

In the LNG vaporizer 14, about 2,380 kW
Large exergy loss associated with heat transfer. Therefore, when considering the recovery of this loss by the Brayton cycle of air, depending on the characteristics of the rotating machine and the heat exchanger, about 350
kW of shaft power can be recovered. However, with respect to the recovery power, the cost of the heat exchanger is increased, and the system is complicated, so that it is not economical.

Based on these results, the power generation efficiency of this system is calculated as follows: 17.1 × 0.98 × 0.96 / (21.1−0.6 + 13.2) = 47.7% for LNG thermal power generation 50.2 × 0.98 / ( 100-13.2 + 0.6) = 56.3%. It should be noted that the power output of the gas turbine is higher than 54.0% of the power output of the ACC at the same turbine inlet combustion gas temperature.

The reason why a high output is obtained is shown in FIG.
Exhaust gas and intake air (Hot S
(Tream) and the enthalpy temperature characteristics of the fluid to be heated (Cold Stream). The upper continuous line shows the temperature of the exhaust gas. Each lower line segment indicates the temperature of the fluid to be heated.

The first reason for obtaining a high output is that the amount of steam generated in the boiler 12 is reduced, and exergy loss due to mixing of steam and air, which is a problem in a chain cycle or the like, is suppressed. For this reason, the range of enthalpy used in the boiler has been narrowed.

The second reason is that a large amount of hot exergy of high-temperature exhaust gas is effectively recovered by the air superheater 11, thereby increasing the output of the gas turbine 4.

The third reason is that the power of the air compressor 2 is reduced by cooling the intake air by the air cooler 6. Further, the exhaust gas is cooled to substantially the same temperature as the atmosphere by the HFC-based mixed chlorofluorocarbon in the Freon vaporizer 13, and condensed water at a boiler feedwater flow rate or more can be recovered.

Next, the reason why a high output can be obtained by the LNG cryogenic power generation will be described. In this embodiment, the natural gas and the HFC-based mixed chlorofluorocarbon fluid (H
FIG. 4 shows the temperature characteristics of the enthalpy in the condensation step of otStream) and the evaporation step of LNG and liquefied mixed chlorofluorocarbon (Cold Stream).

The first reason is that, by combining LNG and HFC-based mixed chlorofluorocarbon, the temperature difference between the fluids in the LNG main heat exchanger 19 is reduced, thereby greatly reducing the exergy loss due to heat transfer. It is that you are.

The second reason is that each natural gas turbine 21,
This means that the inlet gas temperature of the gas turbine 23 and the freon turbine 8 is heated by the exhaust heat of the gas turbine 4 to increase the turbine output.

The power generation output obtained by high-efficiency LNG cryogenic power generation using seawater as a heat source is about 50 kWh per ton of LNG. Usually, the LNG flow rate per LNG vaporizer is about 150 ton / h. Therefore, the power generation output in this case is 7,500 kW. On the other hand, LNG
Thermal power generation efficiency is 52% due to improved ACC efficiency and larger size
As described above, facilities having an output of about 330 MW per system have already been tested and operated. 150ton / h fuel LNG
When power is generated by this ACC, an output of about 1,200 MW can be obtained. From this, L of current system using seawater
NG refrigeration is no longer being built, mainly for economic reasons.

Therefore, as heat sources for vaporizing LNG, the exhaust heat of the steam injection regenerative gas turbine 1 as in the present embodiment is used to expand the natural gas turbines 21 and 23 and the Freon turbine 8 for expanding the mixed chlorofluorocarbon. We proposed an LNG cryogenic power generation that effectively combines the above, and conducted an exergy analysis.

FIG. 5 shows a state in which the system is defined by the software used for the exergy analysis, and FIG. 6 shows the results of the analysis at each part in FIG. The name shown in FIG.
e) corresponds to the reference numeral given to the arrow in FIG. As a result of the analysis, the power generation output per tonne of LNG was approximately doubled to 94 times.
kW, eliminating the need for seawater pumps and intake / drainage equipment. In addition to using expensive vaporization equipment, the waste heat recovery device 10
It was found that NG and HFC-based mixed CFC refrigerants could be vaporized. When the temperature of the combustion gas at the gas turbine inlet is 1,350 ° C., the power generation efficiency of the LNG cryogenic power generation and the gas turbine power generation is 47.7 on a cryogenic exergy basis.
%, And 51.6% on the basis of a high calorific value.

The power generation output of this system with respect to the LNG vaporization flow rate of 150 ton / h is about 58 MW, which is about eight times that of the system using seawater. Also, the power generation efficiency for natural gas fuel alone excluding cold exergy is
It is extremely high at 60%. If six LNG bases are adopted at an LNG terminal with a receiving capacity of 5 million tons annually, almost all of the LNG cold heat can be recovered, and the power generation output will be about 345 MW.

[0056]

As described above, according to the present invention, it is possible to increase the output of a gas turbine by mixing steam with the combustion gas for driving the gas turbine to effectively recover the heat of the exhaust gas from the gas turbine. Since the intake air to the air compressor is cooled by the air cooler constituting the Rankine cycle for extracting the cold heat of the liquefied natural gas, power consumption can be reduced. If the amount of water vapor generated by the exhaust gas is reduced, the exergy loss due to the mixture of the water vapor and the air can be suppressed.

Further, according to the present invention, heat exchange is efficiently performed in a state where the temperature difference between the liquefied natural gas and the mixed chlorofluorocarbon refrigerant and the circulated natural gas is small, and the cryogenic energy of the liquefied natural gas is mixed by the Rankine cycle It can be transferred to CFC refrigerant and circulating natural gas, and can be effectively used via an air cooler or an exhaust heat recovery device.

Further, according to the present invention, since the steam generated in the exhaust heat recovery device is generated from the water recovered from the exhaust gas, a water source for generating the steam is not required, and the cost required for the construction of a water supply facility or the like is eliminated. Can be reduced.

Further, according to the present invention, natural gas can be supplied at a plurality of pressures, and power can be recovered according to the pressure difference in the natural gas expansion turbine, so that the exergy of liquefied natural gas can be effectively used. be able to.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing an exergy evaluation result of the embodiment of FIG. 1;

FIG. 3 is a graph showing enthalpy temperature characteristics between exhaust gas and intake air of the gas turbine 4 and a fluid to be heated in the embodiment of FIG. 1;

FIG. 4 is a graph showing a temperature characteristic of enthalpy with respect to a space between fluids in the LNG main heat exchanger 19 in the embodiment of FIG.

FIG. 5 is a diagram showing a definition state of software for performing an exergy analysis in the embodiment of FIG. 1;

6 is a chart showing an example of an exergy analysis result for each part in FIG. 5;

FIG. 7 is a diagram showing the classification of the LNG thermal power generation system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steam injection regenerative gas turbine apparatus 2 Air compressor 3 Combustor 4 Gas turbine 5 Rankine cycle 6 Air cooler 8 Freon turbine 9 Mixing part 10 Exhaust heat recovery device 11 Air superheater 12 Boiler 13 Freon vaporizer 14 LNG vaporizer 15 High pressure natural gas superheater 16 Low pressure natural gas superheater 19 LNG main heat exchanger 21 High pressure natural gas turbine 23 Low pressure natural gas turbine

Claims (4)

[Claims] A gas turbine rotatably driven by a combustion gas of a gas fuel; an air compressor driven by a rotation output of the gas turbine to compress air for combustion of the gas fuel; and an exhaust gas having an exhaust gas from the gas turbine. By recovering heat, superheat the combustion air of gas fuel compressed by the air compressor,
Rankine circulating waste heat recovery equipment that generates steam to be mixed with combustion air, raises the temperature of the liquefied natural gas to vaporize it, and further heats it, and circulates a mixed CFC refrigerant that uses the cold heat of the liquefied natural gas to condense Cycle, a heat exchanger for exchanging heat between liquefied natural gas supplied for raising the temperature and vaporization in the exhaust heat recovery device, and a mixed chlorofluorocarbon refrigerant circulating in the Rankine cycle, and mixing introduced to the heat exchanger A CFC expansion turbine that is rotationally driven by CFCs; a natural gas expansion turbine that is rotationally driven by natural gas superheated by the exhaust heat recovery device; a generator that is driven by the rotational output of the gas turbine and each expansion turbine; An air cooler that cools the air taken into the air compressor by the mixed CFC refrigerant of the Rankine cycle cooled by the exchanger. Is a liquefied natural gas cold-heat power generation device characterized in that a mixed CFC refrigerant is guided to an exhaust heat recovery device after an air cooler, and the exhaust gas is cooled and then guided to a CFC expansion turbine. 2. The use of liquefied natural gas according to claim 1, wherein the heat exchanger is capable of performing heat exchange with a small temperature difference between the liquefied natural gas and the mixed CFC refrigerant. Power generator. 3. The steam generated in the exhaust heat recovery device,
The liquefied natural gas-based power generation device according to claim 1 or 2, wherein the water in the exhaust gas cooled by the mixed Freon refrigerant is heated to generate the water. 4. The natural gas expansion turbine is provided in a plurality of stages according to the pressure of the natural gas. Exhaust gas from the high-pressure side natural gas expansion turbine is further superheated by the exhaust heat recovery device, and then the low-pressure side 2. A natural gas expansion turbine according to claim 1, which is driven to rotate.
The liquefied natural gas cold energy utilizing power generator according to any one of claims 1 to 3.