JP2003148696A - Natural gas feeding method and natural gas feeding equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To feed natural gas by situating an LNG storage tank at a demander site. SOLUTION: Liquefied natural gas is stored in a storage tank situated at a demander site, and vaporized by a vaporizer coupled with the storage tank through a first transfer pipe. Vaporized natural gas is fed to a gas appliance through a second transfer pipe. In a hot water tank coupled with the storage tank through a third transfer pipe, boil off gas generated in the storage tank is utilized as a heating source.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a facility for supplying natural gas, which comprises a liquefied natural gas (LNG) storage tank, a carburetor facility and a gas heater type hot water storage tank at each home or business site.

[0002]

2. Description of the Related Art As a conventional fuel gas supply method for households and businesses in urban areas, it is a general method to receive the supply of natural gas from a city gas pipe. This is because the gas pipe can always supply the fuel gas, the storage tank for the fuel is not required, and the labor for refueling can be saved, which is convenient. FIG. 1 shows a conventional gas supply system. LPG and kerosene are used as fuel in areas where gas supply from the city gas pipeline is not available.

Further, when a distributed power source such as a fuel cell power generation system using natural gas as a fuel or a micro gas turbine is installed, the conventional fuel supply method is generally to receive supply from a city gas pipe. is there. This is because the city gas pipe can constantly supply fuel gas, does not require a fuel storage tank, and has the convenience of refueling. LPG and kerosene are used as fuel in areas where the supply from the city gas piping network cannot be obtained, and they are delivered by home delivery and supplied to storage tanks installed at each site for use.

FIG. 2 is a conceptual diagram when the small fuel cell power generation system is used as a household cogeneration. The fuel for the small fuel cell power generation system is supplied from the city gas pipe. Electricity generated by a small fuel cell is supplied to home air conditioners, lighting, refrigerators, etc. Electricity that is not sufficient for power generation by small fuel cells is supplied with commercial power. Hot water generated from the exhaust heat of the fuel cell is stored in a small hot water storage tank and supplied to the kitchen or bath as needed.

[0005]

The domestic city gas uses imported LNG (liquefied natural gas) as a raw material, which is vaporized and supplied to the city gas pipe. LNG itself is purchased in large quantities in a long-term plan, so the gas cost is 20-30 yen / Nm
It is about ³ . However, the unit price of city gas purchased by consumers is extremely high due to the supply of natural gas through city gas pipes. The reason for this is that city gas is LNG, which is a raw material.
Is vaporized and pressurized at the LNG base, and is supplied to each consumer by using city gas pipes that are expensive to install. Particularly in urban areas, it is said that land is expensive, piping installation costs are high, and there are many laws and regulations, and city gas piping work is expensive.

When LPG is used as a fuel outside the area where city gas is supplied, the unit price of LPG is higher than that of city gas, so there is little merit in terms of economic efficiency. The cost of using kerosene as fuel is lower than that of city gas, but there are environmental problems such as sulfur oxides and NOx. Therefore, in order to improve the environment, it is necessary to supply natural gas at low cost to urban areas and suburbs. It is expected that the city gas will be gradually replaced in the future, but the land price is relatively low in such areas, but the gas pipes are long due to the lack of artificial construction, and the construction cost is high. Therefore, it is expected that it will be difficult to reduce the gas unit price.

[0007] At present, from the viewpoint of energy saving and environmental aspects, introduction of cogeneration equipment using city gas as fuel is expected, but at present, the introduction of the city gas is hindered by the high unit cost of city gas. In particular, the gas unit price when used for a distributed power source such as a household fuel cell is 123 yen / Nm ^3, and it is more economical to purchase electricity from a distribution system if only electricity is used. It is estimated that the gas unit price, which is economically advantageous even if both heat and electricity are used, is 70 to 90 yen / Nm ³ or less, and lowering the price of gas is an issue.

When LPG is used as fuel, the unit price of LPG is higher than that of city gas, and therefore there is little merit in terms of economic efficiency. In addition, when kerosene is used as fuel, it is cheaper than city gas, but it needs to be reformed as a fuel for distributed power sources such as fuel cells, and kerosene with a high sulfur content and carbon content cannot be reformed. It is difficult and not suitable as a fuel for fuel cells. Furthermore, the amount of SO _X and NO _X generated is large, and there are restrictions from the environmental aspect.

Under the above circumstances, in order to promote the introduction of cogeneration equipment such as fuel cells, it is necessary to provide a method of supplying fuel gas to urban areas and suburban areas at low cost.

Under these circumstances, an attempt has been made to install an LNG storage tank at a customer site and eliminate the need for city gas piping. However, since LNG is a low-temperature liquid, there is a boil-off gas phenomenon in which heat is absorbed from the ambient atmospheric temperature and a part is vaporized. It is difficult to use this boil-off gas, and therefore it is difficult to use for household and business purposes. LNG storage did not penetrate into consumer demand. Since boil-off gas is generated during the time when gas is not consumed or at night, effective use of boil-off gas has been a problem.

[0011]

The present inventor has conducted extensive studies in view of the above-mentioned problems of the prior art, and as a result, the supply of city gas to consumers is controlled by liquefied natural gas (LNG) which is a liquid. It has been found that by constructing a system for supplying natural gas to a gas appliance from an LNG storage tank installed at a customer site, the cost of fuel gas can be reduced and boil-off gas can be effectively used.

That is, the present invention provides the following natural gas supply method and natural gas supply equipment. Item 1. The liquefied natural gas is stored in a storage tank installed at the customer site, the liquefied natural gas is vaporized by a vaporizer connected to the storage tank by the first transfer pipe, and the vaporized natural gas is stored by the second transfer pipe. A method for supplying natural gas, comprising supplying to a gas appliance and using boil-off gas generated in the storage tank in a hot water storage tank connected to the storage tank by a third transfer pipe as a heating source.

Item 2. The second transfer pipe and / or the third
Item 2. The natural gas supply method according to Item 1, wherein the natural gas transferred by the transfer pipe is supplied to the distributed power source, and the natural gas is used as a fuel for the distributed power source.

Item 3. Item 3. The natural gas supply method according to Item 2, wherein the exhaust heat generated by the distributed power source is used as a heat source of the vaporizer.

Item 4. Item 4. The natural gas supply method according to Item 2 or 3, wherein hot water generated by the distributed power source is used as a heat source of the hot water storage tank.

Item 5. 5. The water is cooled by air cooled by vaporization cold heat of liquefied natural gas provided in the vaporizer, and the cooled water is stored in a cold water tank. Natural gas supply method.

Item 6. By transmitting the liquid level information of the storage tank to a liquefied natural gas supply station via a telephone line or an internet line, the liquid level level is grasped at the liquefied natural gas supply site, and the liquid level is below a predetermined value. The natural gas supply method according to any one of Items 1 to 5, wherein the storage tank is replenished with liquefied natural gas.

Item 7. A storage tank for storing liquefied natural gas, a vaporizer connected to the storage tank by a first transfer pipe, for vaporizing the liquefied natural gas, and a second for supplying the gas appliance with the natural gas vaporized by the vaporizer. A hot water storage tank, which is connected to a transfer pipe, the storage tank, and a third transfer pipe, and uses boil-off gas generated in the storage tank as a heating source;
A natural gas supply device comprising a fourth transfer pipe connecting the second transfer pipe and the third transfer pipe.

Item 8. A first control valve provided on the first transfer pipe for adjusting the flow rate according to the gas usage of the gas appliance and the gas usage of the hot water storage tank; and the gas usage of the supply destination provided on the fourth transfer pipe and Item 8. The natural gas supply device according to Item 7, further comprising a second control valve that adjusts a flow rate according to the amount of gas used in the hot water storage tank.

Item 9. Item 8. The natural gas supply apparatus of item 7, further comprising a distributed power source connected to the fourth transfer pipe by a fifth transfer pipe.

Item 10. A distributed power source connected to the fourth transfer pipe by a fifth transfer pipe, and a gas usage amount of a gas appliance, a gas usage amount of the hot water storage tank, and a gas usage amount of the distributed power source, which are provided in the first transfer pipe. Is provided between the first control valve that adjusts the flow rate according to the above, the connection portion of the fourth transfer pipe and the fifth transfer pipe, and the connection portion of the second transfer pipe and the fourth transfer pipe. A second control valve for adjusting the flow rate according to the usage amount, the gas usage amount of the hot water storage tank and the gas usage amount of the distributed power source, a connecting portion of the fourth transfer pipe and the fifth transfer pipe, and a third transfer pipe And the amount of gas used in the gas appliance, which is provided between the connecting portion of the fourth transfer pipe and
A third control valve that adjusts the flow rate according to the amount of gas used in the hot water storage tank and the amount of gas used in the distributed power source, and is provided on the hot water storage tank side from the connecting portion of the third transfer pipe and the fourth transfer pipe,
Fourth, adjusting the flow rate according to the gas usage of the gas appliance, the gas usage of the hot water storage tank, and the gas usage of the distributed power source
The natural gas supply apparatus according to item 7, further comprising a control valve.

Item 11. Item 11. The natural gas supply device according to Item 9 or 10, further comprising a pipe that supplies exhaust heat generated from the distributed power source to the vaporizer.

Item 12. Item 12. The natural gas supply device according to any one of Items 9 to 11, further comprising a pipe for supplying hot water generated from the distributed power source to the hot water storage tank.

Item 13. A heat exchanger for exchanging heat between vaporized cold heat of liquefied natural gas generated in the vaporizer and water, and a cold water tank for storing cold water produced by the heat exchanger. The natural gas supply device according to any one of 7 to 12.

Item 14. Item 14. The natural gas supply device according to any one of items 7 to 13, further comprising means for transmitting the liquid level information of the storage tank to a liquefied natural gas supply site via a network.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, city gas is supplied to a consumer in the form of liquefied natural gas (LNG) which is a liquid, and a gas appliance is supplied from an LNG storage tank installed at a consumer site. It relates to a system for supplying natural gas to. Consumers include ordinary households, factories, housing complexes, small and medium-sized housing development areas, and the like. The LNG delivery from the LNG base to the LNG delivery center is mainly by the LNG storage tank truck, but the delivery from the LNG delivery center to each user is, for example, the delivery by a small LNG storage tank truck or a portable cylinder. By this, LNG can be supplied to the LNG storage of the consumer. As a result, since there is no depreciation of piping equipment costs, it is possible to supply fuel gas only with transportation costs and labor costs and LNG storage tank equipment depreciation costs, which is comparable to city gas that requires the installation of city gas piping. Thus, a low-cost fuel gas supply method can be obtained. FIG. 3 shows an example of the LNG supply system. In addition,
Throughout the drawings, the same components are denoted by the same reference numerals.

Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 4 is a system diagram showing an embodiment of a natural gas supply facility according to the present invention. In this embodiment, an LNG storage tank 1, an LNG vaporizer 2, and a gas type hot water storage tank 3 are provided. The gas type hot water storage tank 3
Is equipped with a gas heater. The LNG storage tank 1 is provided with a supply pipe (not shown) for supplying LNG from the tank truck as needed.

First control valve 2 provided on the first transfer pipe
L opened from LNG storage tank 1 by opening 1
NG is supplied to the LNG vaporizer 2 via the first transfer pipe 11, and is vaporized in the vaporizer 2 to generate natural gas (N
G). The vaporized natural gas is supplied to the gas appliance 4 such as a gas stove and floor heating via the second transfer pipe 12 and, if necessary, to the gas heater of the gas hot water storage tank 3 via the fourth transfer pipe 14.

The boil-off gas generated in the LNG storage tank 1 is passed through the third transfer pipe 13 to the gas type hot water storage tank 3
The gas heater is used to raise and maintain the temperature of the hot water in the hot water storage tank 3. As a result, the boil-off gas generated regardless of day and night can be effectively used, and economical operation can be achieved even if the LNG storage tank is installed at the customer site. When the amount of heat is insufficient with only the boil-off gas, the second control valve 22 provided in the fourth transfer pipe 14 is opened, and NG vaporized by the vaporizer 2 is supplied to the gas heater of the gas hot water storage tank 3. , Water temperature rise and hot water temperature maintenance are performed.

The LNG storage tank 1 is not particularly limited as long as it stores LNG in a liquid state, and for example, a double shell vacuum adiabatic low temperature tank (fixed type or portable type) or the like can be used. The LNG vaporizer 2 is not particularly limited as long as it vaporizes LNG, and for example, a fin tube type open rack type or a plate fin type open rack type can be used. As the gas type hot water storage tank 3, a stainless steel container having a built-in heating gas burner can be used. As the gas appliance 4, a gas stove, a gas floor heating, a gas fan heater, a gas cooling system, or the like can be used.

The first transfer pipe 11 is not particularly limited as long as it can transfer LNG, and a vacuum heat insulating pipe, a high heat insulating pipe or the like can be used. Second transfer pipe 12, third
The transfer pipe 13 and the fourth transfer pipe 14 are not particularly limited as long as they can transfer NG, and general gas pipes currently used can be used.

Regarding the control of the system, when the gas appliance 4 is used, the first control valve 21 is opened and LNG is changed to LNG.
It is supplied to the vaporizer 2 and vaporized. The control of the first control valve is to control the start / stop of the gas appliance 5 and the amount of hot water in the gas hot water storage tank 3.
The control may be based on the information on the hot water temperature state, or may be constant pressure control that keeps the pressure of the gas pipe constant. Further, the control of the second control valve 22 is preferably controlled by information on the hot water amount / hot temperature state of the gas type hot water storage tank 3. The amount of hot water stored in the gas hot water storage tank 3 can be set by using a microcomputer-type program by which time. For example, during the day,
The hot water tank holds 50% warm water and is full after 5 pm. After using it in the bath, it is possible to use hot water of 50% capacity again.

The capacity of the LNG storage tank depends on the LNG supply frequency and the amount of gas used. When considering household LNG storage tanks, the amount of city gas used per month is 50 to 10
It is 0 Nm ³ , which is approximately 120 to 240 when converted to LNG.
It becomes L.

Household fuel consumption per month 50 to 100 Nm ³ 50 Nm ³ /22.4 Nm ³ × 16kg = 35.7kg LNG specific gravity is about 0.3 to 35.7 kg / 0.3 = 119 L Therefore, LNG is supplied once a month. Then, the LNG storage tank capacity is sufficient if it is about 120 to 240 L, but it is appropriately selected according to the gas usage amount of the consumer and the LNG supply frequency. The installation space of the LNG storage tank with a capacity of 200 L is about half that of the electric water heater for home use, and it is easy to secure the installation space for the LNG storage tank at home.

When the LNG storage tank is installed at the customer site, care must be taken to manage the remaining amount of LNG and replenish LNG. The information of the liquid level gauge (not shown) of the LNG storage tank 1 is transmitted to the LNG supplier such as the LNG delivery center 5 via the network, and the LNG supplier manages the information of the liquid surface level, so that the consumer It is possible to save the trouble of checking the liquid level.

The network may be wired or wireless, and may be, for example, a telephone line, an internet line, or LA.
It is possible to use N, optical communication line, satellite communication line, wireless line, PHS and the like.

In the case of household use, the capacity of the gas type hot water storage tank is such that the maximum amount of hot water used in a short time is a bath, so it is usually sufficient to have the same capacity as the bath, and in that case, about 200 L. is there. When using an electric water heater, it is for 4-5 people
Needs 350-450L. Therefore, the capacity of the hot water storage tank of the present invention is about half that of the electric water heater.

In the above description, the capacity of the LNG storage tank has been described using the case of use in a general household as a model case.
The capacity of the LNG storage tank may be appropriately selected according to the amount of gas used by the consumer, the frequency of replenishment, etc., and is not limited to the above. This also applies to the following description.

The amount of boil-off gas is usually 1 to 3% of the stored amount.
/ It is said to be a day. In the case of a 36 kg (about 120 L) storage LNG storage tank, if the boil-off gas amount is 3%, the boil-off gas amount is 36 kg × 0.03 = 1.08 kg / day.
Converting this to heat, 1.08 kg / day ÷ 16 × 22.4 × 950
It becomes 0kcal / Nm ³ = 14364 kcal.

When water of 15 ° C. is heated to 90 ° C. with this heat quantity, about 153 L of hot water is produced when the burner efficiency is calculated as 80% (14364 kcal ÷ (90−15) × 0.8≈153 L) .

When the storage amount is 72 kg (about 240 L), which is double,
The amount of boil-off gas doubles, producing 306L of hot water. This amount is similar to the hot water storage tank of a domestic electric water heater. As described above, in the present invention, the boil-off gas generated from the LNG storage tank does not become a surplus and is effectively used for producing hot water in the hot water storage tank. The amount of boil-off gas generated is reduced by improving the heat insulation.

Next, FIG. 5 shows an embodiment of the natural gas supply equipment of the present invention using a fuel cell as an example of a distributed power source. The distributed power source is not particularly limited as long as it uses gas as a fuel, for example, a fuel cell,
A small gas engine, micro turbine, etc. can be used. As the fuel cell, for example, a phosphoric acid fuel cell, a polymer electrolyte fuel cell, a molten carbon dioxide fuel cell, a solid electrolyte cell, or the like can be used.

In this embodiment, an LNG storage tank 1, an LNG vaporizer 2, a gas type hot water storage tank 3, and a fuel cell 6 are provided. The boil-off gas generated in the LNG storage tank 1 is used for the fuel cell 6, and when the boil-off gas is insufficient, the boil-off gas generated in the carburetor 2 is supplemented to make the boil-off gas generated day and night effective. Therefore, even if an LNG storage tank is installed at the customer site, it can be economically operated. In addition, when the fuel cell 6 is operated at night, or when the fuel cell 6 fails and stops, the boil-off gas can be used in the gas heater of the gas hot water storage tank 3 to consume the entire boil-off gas. In addition, the fuel cell 6
It is also possible to effectively use the exhaust heat by using the exhaust heat generated in step 2 as the heat source of the vaporizer 2. Also, FIG.
As shown in FIG. 2, the water used for cooling the fuel cell 6 rises in temperature due to the heat of the fuel cell 6, and the hot water obtained by the hot water is stored
It is also possible to add to the heat source of.

The system control is as follows. When the fuel cell 6 is generating power, the second control valve 22 is always open and the naturally occurring boil-off gas is supplied to the fuel cell 6. When the power generation of the fuel cell 6 is insufficient only by the fuel supply by the boil-off gas, the first control valve 1 and the second control valve 22 are opened and the NG vaporized by the LNG vaporizer is supplied to the fuel cell. When the gas appliance 4 is used, the first control valve 21 is adjusted to increase the amount of NG, and other controls do not change. First control valve 21
The control may be controlled by the information on the output of the fuel cell 6 or the information on the start / stop of the gas appliance 4, or may be the constant pressure control for keeping the pressure of the gas pipe constant. Gas type hot water storage tank 3
Is supplied with the cell cooling water of the fuel cell 6 to produce hot water of about 60 ° C. However, when the amount of additional heating or the amount of hot water for raising the hot water to 60 ° C. or more decreases, the fourth control valve 24 is used as the first step. Is opened, and when the amount of heat is still insufficient, the first control valve 21, the second control valve 22, and the third control valve 23 are opened, and NG vaporized by the vaporizer is supplied to the gas heater of the gas hot water storage tank 3. In addition, when the fuel cell 6 is operated to stop at night, or when the fuel cell 6 breaks down, the fourth control valve 24 is opened and
It is also possible to close the control valve 22 and supply the entire amount of boil-off gas to the gas heater of the gas hot water storage tank 3.

In the present embodiment, assuming that the LNG supply frequency is once a month, it is sufficient for household use that the LNG storage tank capacity is about 400 L.

Fuel consumption at rated load of 1kW PEFC
0.3Nm ^{3 /} h (0.21kg / h), fuel consumption at ³⁰ % minimum load 0.1
Nm ³ / h (0.07kg / h) Monthly LNG fuel consumption 0.21kg / h × 16h × 30 days + 0.07kg / h × 8h × 30 days = 117.6kg /
The specific gravity of the monthly LNG is about 0.3 to 117.6 kg / 0.3 = 392 L 400 L The installation space is about the same as a household electric water heater, and it is considered that there is an installation space unless the home is extremely small. Also, if the replenishment period is every two weeks, the installed capacity will be reduced by half.

The amount of boil-off gas in this case is generally said to be 1 to 3% / day of the stored amount. Storage amount 117 kg (about 400
If the boil-off gas amount is 3% in the storage tank (L), the night-time boil-off gas amount is 117 kg × 0.03 ÷ 24h = 0.146 kg / h 1 kW PEFC rated load LNG usage (0.21 kg /
h), 0.146 kg / h corresponds to about 60-70% load. Therefore, by using the boil-off gas for a distributed power source such as a fuel cell, the boil-off gas can be effectively used, and excess boil-off gas is not generated.

Next, LNG of the natural gas supply equipment of the present invention
Cold water production using vaporized cold heat generated in the vaporizer will be described. FIG. 6 shows an embodiment of the natural gas supply equipment of the present invention for producing cold water by utilizing the vaporized cold heat generated in the LNG vaporizer 2. In this embodiment, the heat exchanger 7 and the cold water tank 8 are provided, and the LNG storage tank 1, the LNG vaporizer 2, and the gas type hot water storage tank 3 (not shown) are provided similarly to the natural gas supply equipment shown in FIG. Is equipped with. Further, similarly to the natural gas supply facility shown in FIG. 5, it is possible to further provide a distributed power source such as a fuel cell. Figure 6
In Fig. 1, among the facilities of the present invention, only those involved in cold water production are shown.

LNG from the LNG storage tank 1 is L
Air is supplied by an air blower installed in the NG vaporizer 2 and is vaporized by the heat of the air. However, in the case of a small capacity device, it is possible to vaporize by natural convection without the air blower. The air cooled by the LNG is the carburetor 2
The water in the cold water heat exchanger 7 installed at the upper part of is cooled. The cooled water is stored in the cold water tank 9. When the water level in the cold water tank 8 becomes low, the cold water supply valve 25 opens under the condition that the vaporizer 2 is operating, and tap water is supplied to the cold water heat exchanger 7. In the present embodiment, the heat exchanger 7 is installed inside the vaporizer 2, but it may be installed outside the vaporizer 2. As the heat exchanger, for example, a fin tube type can be used.

The amount of city gas used in a household gas appliance is 50 to 100 Nm ³ / month in the case of a general household of 4 people.
In addition, the flow rate of natural gas used when installing a household fuel cell is 0.3 Nm ³ / h for a 1 kW machine. When a gas amount corresponding to this is obtained by vaporizing LNG, the cold heat generated can be used to produce cold water. 1) An example of cold water production when a cold water production system is added to the embodiment shown in FIG. 4 is shown below.

LNG evaporation heat 122kcal / kg NG constant pressure specific heat 0.5kcal / kg LNG vaporization temperature -82 ° C cold water temperature 4 ° C (tap water temperature summer 15 ° C intermediate period
13 ℃ Winter 10 ℃ Cold energy generated is [122kcal / kg + (4 ℃ + 82 ℃) x 0.5kcal /
[kg] = 165kcal / kg Cold water generated in summer is 165kcal / kg × 1.2 kg / day × 0.7 (efficiency) / (15 ℃ -4 ℃), assuming that LNG vaporization amount per day is 1.2kg.
＝ 12 kg ＝ 12L Cold water generated in the middle period is 165 kcal / kg × 1.2 kg × 0.7 (efficiency) / (13 ℃ -4 ℃) = 1
5.4 kg ＝ 15L Cold water generated in winter is also 165kcal / kg × 1.2 kg × 0.7 (efficiency) / (10 ℃ -4 ℃) = 2
3 kg = 23L In this way, cold water for drinking can be obtained by using LNG cold heat, and if it is stored in a cold water pot, a sufficient amount for household use can be supplied. 2) An example of cold water production when the cold water production system is added to the embodiment shown in FIG. 5 is shown below.

LNG evaporation heat 122kcal / kg NG constant pressure specific heat 0.5kcal / kg LNG vaporization temperature -82 ° C cold water temperature 4 ° C (tap water temperature summer 15 ° C intermediate period
13 ℃ winter 10 ℃) The generated cold heat is [122kcal / kg ＋ (4 ℃ ＋ 82 ℃) × 0.5kcal / kg]
kg] = 165kcal / kg Cold water generated in the summer has an LNG vaporization rate of 3.
Assuming 92 kg, 165 kcal / kg × 3.92 kg × 0.7 (efficiency) / (15 ℃ -4 ℃) =
41 kg = 41L Cold water generated in the middle period is also 165 kcal / kg × 3.92 kg × 0.7 (efficiency) / (13 ℃ -4 ℃) =
50 kg = 50 L Cold water generated in the winter season is also 165 kcal / kg × 3.92 kg × 0.7 (efficiency) / (10 ℃ -4 ℃) =
75 kg = 75 L As described above, cold water for drinking can be obtained by utilizing LNG cold heat, and if it is stored in a cold water pot, a sufficient amount can be supplied for home and business use.

In order to increase the capacity of the NG vaporizer or reduce its size, the low temperature exhaust heat of the distributed power source such as a fuel cell is used as the heat source of the vaporizer. This can be achieved by flowing exhaust gas exhaust heat of the fuel cell of 60 to 80 ° C. to the position. Especially in winter, a large amount of air is required because the air temperature drops. By adopting a variable nozzle structure for the exhaust gas duct, it becomes possible to guide the exhaust gas to the vaporizer in the cold season and improve the vaporizer efficiency.

FIG. 7 shows an embodiment in which the present invention is used in an apartment house or a small residential area development area. An LNG storage tank and an LNG vaporizer are installed in a part of an apartment house and the vaporized NG is supplied to each household in the apartment house. The boil-off gas generated from the LNG storage tank is used as fuel for a distributed power source such as a fuel cell or a micro gas turbine, and is used as private power consumption in collective housing or the like or power for shared facilities. Further, the warm heat generated from the fuel cell or the like and the cold heat generated from the vaporizer can be used in the community center or the like.

[0055]

EFFECT OF THE INVENTION Conventionally, when gas is supplied from an LNG storage tank, boil-off gas that is vaporized from LNG at a time when gas is not used or at night (because it is a low-temperature liquid, heat is absorbed from the ambient atmospheric temperature). The treatment of the gas generated by partial vaporization was a major problem. However, in the present invention, since the boil-off gas is always used by being basically used as a burner fuel for hot water storage or a fuel of a distributed power source such as a fuel cell, the problem of boil-off gas is solved,
An LNG storage tank and a vaporizer can be installed to supply gas directly to homes and businesses. Therefore, it is not necessary to install city gas pipes, natural gas can be supplied to users at low cost, and economic efficiency is improved.

For example, for household use, the gas unit price is 123 yen / Nm ³
However, if it is possible to purchase LNG directly and use it as fuel by the method according to the present invention, it is not necessary to lay city gas pipes and there is no amortization of pipe equipment costs, so transportation costs And labor costs and LNG storage tank depreciation costs alone, it will be possible to supply at a lower cost than piping.
It will be possible to purchase for about JPY / Nm ³ , which will improve the economic efficiency. Since the unit price of city gas is high especially for small-lot users, the merit of purchasing LNG becomes remarkable for small-lot users. For this reason, in the past, since the unit price of city gas was high, it was difficult to popularize cogenes using a distributed power source such as a fuel cell, but the present invention reduces the unit price of gas and makes it possible to popularize it.

For example, in the case of a solid polymer electrolyte fuel cell for home use, even if the cost of the fuel cell system is 500,000 yen / unit, it is not economical unless the gas unit price is 70 to 90 yen / Nm ³ or less. There is a calculation result of. If it is possible to directly purchase LNG and use it as fuel in the system according to the present invention, it is possible to purchase LNG for about 40 to 90 yen / Nm ^3, which is economically feasible.

Further, by delivering and replenishing LNG even in an area where LPG or kerosene was used as fuel outside the city gas supply area, natural gas, which is lower in cost than LPG and environmentally superior to kerosene, is used as a fuel. It becomes possible.

[Brief description of drawings]

FIG. 1 is a diagram showing a conventional domestic city gas supply system.

FIG. 2 is a conceptual diagram showing a home cogeneration system.

FIG. 3 is a diagram showing an LNG supply route.

FIG. 4 is a system diagram showing an embodiment of a natural gas supply facility according to the present invention.

FIG. 5 is a system diagram showing an embodiment of a natural gas supply facility using a fuel cell according to the present invention.

FIG. 6 is a system diagram showing an embodiment of a natural gas supply facility using the heat exchanger according to the present invention.

FIG. 7 is a diagram showing an example in which the natural gas supply facility of the present invention is applied to an apartment house or a small-scale residential land development area.

[Explanation of symbols]

1 LNG storage tank 2 LNG vaporizer 3 gas type hot water storage tank 4 gas appliances 5 LNG delivery center 6 Fuel cell 7 heat exchanger 8 cold water tank 11 First transfer pipe 12 Second transfer pipe 13 Third transfer pipe 14 Fourth transfer pipe 15 Fifth transfer pipe 21 First control valve 22 Second control valve 23 Third control valve 24 Fourth control valve 25 Water supply valve 31 Hot water piping for battery cooling

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F23K 5/00 307 F23K 5/00 307Z

Claims (14)

[Claims] 1. A liquefied natural gas is stored in a storage tank installed at a customer site, the liquefied natural gas is vaporized by a vaporizer connected to the storage tank by a first transfer pipe, and the vaporized natural gas is removed. A method of supplying natural gas, characterized in that the gas is supplied to a gas appliance through a second transfer pipe, and boil-off gas generated in the storage tank in a hot water storage tank connected to the storage tank is used as a heating source. . 2. The natural gas transferred by the second transfer pipe and / or the third transfer pipe is supplied to a distributed power source, and the natural gas is used as fuel for the distributed power source. Item 1. The natural gas supply method according to Item 1. 3. The natural gas supply method according to claim 2, wherein the exhaust heat generated by the distributed power source is used as a heat source of the vaporizer. 4. The natural gas supply method according to claim 2, wherein the hot water generated by the distributed power source is used as a heat source of the hot water storage tank. 5. The water is cooled by air cooled by vaporization cold heat of liquefied natural gas provided in the vaporizer, and the cooled water is stored in a cold water tank.
4. The method for supplying natural gas according to any one of 4 to 4. 6. A liquid level is grasped at the liquefied natural gas supply site by transmitting the liquid level information of the storage tank to a liquefied natural gas supply site via a telephone line or an internet line, and the liquid level The method for supplying natural gas according to any one of claims 1 to 5, wherein liquefied natural gas in the storage tank is replenished when the level becomes a predetermined value or less. 7. A storage tank for storing liquefied natural gas, a vaporizer connected to the storage tank by a first transfer pipe to vaporize the liquefied natural gas, and a natural gas vaporized by the vaporizer is supplied to a gas appliance. A second transfer pipe, a storage tank, and a third transfer pipe, which connect the second transfer pipe and the third transfer pipe to a hot water storage tank that uses boil-off gas generated in the storage tank as a heating source. A natural gas supply device comprising a fourth transfer pipe. 8. A first control valve provided on the first transfer pipe for adjusting a flow rate according to a gas usage amount of a gas appliance and a gas usage amount of the hot water storage tank, and a supply destination provided on a fourth transfer pipe. 8. The natural gas supply apparatus according to claim 7, further comprising a second control valve that adjusts a flow rate according to the gas usage amount of the above and the gas usage amount of the hot water storage tank. 9. The natural gas supply apparatus according to claim 7, further comprising a distributed power source connected to the fourth transfer pipe by a fifth transfer pipe. 10. A distributed power source connected to the fourth transfer pipe by a fifth transfer pipe, and a gas usage amount of a gas appliance, a gas usage amount of the hot water storage tank, and the dispersion type power supply provided on the first transfer pipe. It is provided between the first control valve that adjusts the flow rate according to the amount of gas used by the power source, the connecting portion between the fourth transfer pipe and the fifth transfer pipe, and the connecting portion between the second transfer pipe and the fourth transfer pipe. A second control valve for adjusting a flow rate according to a gas usage amount of a gas appliance, a gas usage amount of the hot water storage tank and a gas usage amount of the distributed power source; and a connecting portion between a fourth transfer pipe and a fifth transfer pipe. Adjusting the flow rate according to the gas usage of the gas appliance, the gas usage of the hot water storage tank, and the gas usage of the decentralized power supply, which are provided between the third transfer pipe and the connecting portion of the fourth transfer pipe. The third control valve and the connection of the third transfer pipe and the fourth transfer pipe. And a fourth control valve which is provided closer to the hot water storage tank than the unit and adjusts the flow rate according to the gas usage of the gas appliance, the gas usage of the hot water storage tank, and the gas usage of the distributed power source. The natural gas supply device according to claim 7, which is characterized in that. 11. The natural gas supply apparatus according to claim 9, further comprising a pipe for supplying exhaust heat generated from the distributed power source to the vaporizer. 12. The natural gas supply apparatus according to claim 9, further comprising a pipe for supplying hot water generated from the distributed power source to the hot water storage tank. 13. A heat exchanger for exchanging heat between vaporized cold heat of liquefied natural gas generated in the vaporizer and water, and a cold water tank for storing cold water produced by the heat exchanger. The natural gas supply device according to any one of claims 7 to 12, characterized in that. 14. The natural gas supply apparatus according to claim 7, further comprising means for transmitting liquid level information of the storage tank to a liquefied natural gas supply site via a network. .