JP2002213695A - City gas supplying method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device, capable of using hydrogen fuel facilities such as a fuel cell by a city gas pipe line without reforming device. SOLUTION: Hydrogenated city gas, passing through a conduit 3b, is sucked by the action of a vacuum pump 18a, and supplied to a hydrogen separating device 15a through piping 13a, and a flow rate control valve 18a. A hydrogen- separating film, not shown in Figure, is provided in the hydrogen separating device 15a, and hydrogen gas in the city gas is supplied to a fuel cell 16a via the separating film and the piping 17a, while methane, and propane and the like, except for the hydrogen gas, is returned to the conduit 3b through gas piping 14a without passing via the separating film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for supplying city gas, and more particularly to a method and apparatus for supplying city gas containing hydrogen gas.

[0002]

2. Description of the Related Art In recent years, fuel cells have been put to practical use for consumer use, and fuel cell systems using city gas as fuel are expected to be widely used in the future. Conventionally, the city gas supply has mainly been 13A gas which vaporizes LNG containing methane as a main component and further increases the heat by LPG. In order to operate a fuel cell using conventional city gas, a reformer must be installed upstream of the fuel cell to reform hydrocarbons in city gas to hydrogen and supply it to the fuel cell. is necessary. However, the installation of the reformer increases the cost and the size of the equipment, and may be a factor that hinders the spread of fuel cells.

On the other hand, as a technology for supplying hydrogen using an existing city gas pipeline, a technology for supplying so-called "Hydrogen Methane" in which hydrogen is mixed with natural gas has been disclosed (for example, JP-A-11-
228101) still requires equipment for reforming methane when a fuel cell is used in the Hytan supply system.

[0004] Further, an idea of supplying 100% hydrogen gas using an existing city gas pipeline is also known. In this case, an apparatus using hydrogen as a direct fuel such as a fuel cell can be used directly. There is a problem that the city gas equipment cannot be used.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and an apparatus which make it possible to use a hydrogen fuel facility such as a fuel cell by using a city gas pipeline without requiring a reformer. .

Another object of the present invention is to provide an energy supply mode which ensures a smooth transition from the natural gas supply era to the hydrogen supply era.

It is another object of the present invention to provide a city gas supply mode which is friendly to the global environment.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a method for supplying a gas containing hydrogen gas through a conduit network, the method comprising supplying hydrogen gas in the city gas at one or more points branched from the conduit network. , And at least a part of the separated gas is returned to the conduit network again (Claim 1).

In this manner, the hydrogen gas in the city gas can be separated and supplied directly to a facility using the hydrogen gas as a fuel, such as a fuel cell. This eliminates the need to provide a reformer in the fuel cell. Further, by returning the separated gas to the conduit network, it is possible to respond to a customer who uses the conventional city gas combustion equipment without changing the conventional system.

The present invention is characterized in that the separation of hydrogen gas is controlled so that the Wobbe index (WI) and the burning rate index (CP) of the separated gas each fall within predetermined ranges. A gas supply method is provided (claim 2).

[0011] By such control, it is possible to ensure stable combustion of the city gas combustion equipment. Currently, based on the Gas Business Act, city gas nationwide is classified into 14 gas groups with the Wobbe index and the burning rate index within their respective specified ranges, and city gas companies supply city gas of the specified gas type. It is obliged to supply to customers in the region. Here, the Wobbe index (WI) is a numerical value obtained by dividing the calorific value H (MJ / m3) of the gas by the square root of the specific gravity s of the gas with respect to air, and is expressed by the following equation. The Wobbe index indicates the relationship between the input of gas equipment and the amount of primary air suctioned by the nozzle, and is an index as to whether or not the gas equipment can completely burn.

WI = H / √s The burning velocity index (MCP) is expressed by the following equation.

[0013]

(Equation 1)

Here, S1 and f1 are the burning rate and coefficient of each combustible gas in the city gas, A1 is the content (volume percentage) of each combustible gas in the city gas, and K is the damping coefficient. , Calculated by the following equation.

[0015]

(Equation 2)

In the equation, α1 is a correction coefficient for each combustible gas;
CO2, N2 and O2 are carbon dioxide in the gas,
It is the content (percentage by volume) of nitrogen and oxygen. Note that S
Since specific numerical values of 1, f1, and α1 are shown in the Gas Business Act, they are omitted here.

The combustion characteristics of gas appliances can be expressed by WI and MCP. FIG. 5 conceptually shows this, and shows a compatible range of gas appliances. The device interchangeable region refers to a portion surrounded by these limit lines in which a good combustion region is obtained for all gas appliances with respect to incomplete combustion, back, lift, and the like. In the figure, the incomplete combustion limit, the lift limit, the back limit, the infrared burner glow limit, and the infrared burner back limit are shown. All gas appliances can be satisfactorily burned even if the composition of the supplied gas fluctuates within the compatible range. The Gas Business Law defines a gas group based on such a theory. On the other hand, the law does not regulate the composition of city gas as long as WI and MCP are within certain ranges.
Therefore, even in the case where hydrogen gas is added to city gas and supplied, if the hydrogen concentration in the city gas is controlled within the range of WI and MCP specified for each gas type, both supply and combustion are particularly troublesome. There is no. From this, when a customer who uses equipment using hydrogen gas as a fuel, such as a fuel cell, is in the pipeline network, the customer separates the hydrogen gas and uses it for the fuel cell, etc. WI
And MCP are controlled so as to be within the above range, and again,
By returning to the conduit network, the operation of the fuel cell and the WI and M of city gas flowing through the conduit network
Compatibility with CP maintenance becomes possible.

In the above invention, WI is 52.7 ≦ WI
The hydrogen gas concentration in the city gas can be controlled so that ≦ 57.8 and the CP satisfies 35 ≦ MCP ≦ 47 (claim 3).

The WI and MCP in this range are values determined by the Business Law for 13A gas. The 13A gas is a hydrocarbon-based gas, particularly a city gas mainly composed of methane made from LNG. In addition to 13A gas, L
In some cases, a gas in which PG and air are mixed is supplied. By controlling the hydrogen separation at the customer so that the WI and MCP fall within this range at all points in the supply area, the 13A gas equipment can be satisfactorily burned in the supply area without any problem.

FIG. 3 shows WI and MC for 13A gas.
Hydrogen gas, methane gas, C for keeping P within the above range
It is a figure which shows the permissible density | concentration range of the hydrocarbon gas (CmHn) other than O gas and methane (it shows with the partial pressure ratio of each gas when 1 is set as the whole). That is, if the composition of the city gas is controlled so as to fall within the portion surrounded by the thick frame in FIG. For example, when methane gas is 0.7, hydrogen gas can be added in the range of 0.13 to 0.24 (CO and CmH
n varies from 0.17 to 0.06).

In addition, WI is 49.2 ≦ WI ≦ 53.8, and CP is 34 ≦ MCP ≦ 47.
The ratio of hydrogen gas in city gas can also be determined (claim 4).

The values of WI and MCP are values determined for the 12A gas. By controlling the 12A gas within this range, the same operation as the 13A gas can be performed.

Further, in each of the above-mentioned inventions, the hydrogen addition amount of the supply gas can be controlled based on the hydrogen gas concentration at a plurality of points in the conduit network (claim 7). By doing so, it is possible to prevent the concentration of hydrogen gas in the city gas from becoming too low in some areas in the network, resulting in a gas out of supply conditions.

The amount of hydrogen added is controlled by measuring the amount of hydrogen gas separated at one or more locations branched from the conduit network and determining the concentration of hydrogen gas in city gas at a predetermined location in the conduit network. Can be. Based on the result, WI and MCP can be controlled within a predetermined range throughout the conduit network.

The control of the hydrogenation rate can be performed by supplementing and supplying hydrogen gas at one or more points in the conduit network. As a supplementary supply method, in addition to a method of increasing the hydrogen concentration of city gas supplied from a factory, hydrogen can be added from a hydrogen gas storage facility provided in a conduit network.

According to the present invention, there are provided a gas introducing means for branching and introducing city gas containing hydrogen gas from a conduit network, a hydrogen gas separating means for separating hydrogen gas in city gas, and a conduit for separating at least a part of the separated gas. Provided is a hydrogen gas separation / return device provided with a separation gas return means for returning to a network (claim 9).

The present invention is a gas separation and return device used for supplying city gas according to claims 1 to 8. By installing such a gas separation and return device in a customer equipped with a hydrogen gas utilization device such as a fuel cell, hydrogen gas can be directly used.

[0028] A hydrogen separation membrane can be used as the hydrogen gas separation means. As a material of the hydrogen separation membrane, a known palladium, palladium alloy membrane, polymer membrane, or the like can be used. Further, a hydrogen electrode of a fuel cell can be used as the hydrogen gas separating means.
1).

Further, a double-pipe type pipe constituted by an inner pipe portion and an outer pipe portion can be used as the city gas introducing means and the separated gas returning means (claim 12). By configuring the city gas pipe in this way, the equipment can be made compact.

[0030]

Embodiments of the present invention will be specifically described below with reference to the drawings. Here, in the drawings, the same components are denoted by the same reference numerals, and redundant description will be omitted.
Further, the following embodiments are exemplifications, and the scope of the present invention is not limited to each embodiment.

A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows an overall view of a 13A city gas production and supply system according to the present invention. In FIG. 1, a city gas production and supply system 1 is connected to a city gas production plant 2, a conduit network 3 composed of conduits 3a to 3c, a pipeline 12 connecting the city gas production plant 3 and the conduit network 3, and a conduit network 3. Customers 4 and 5 that perform the operations. In an actual city gas production and supply system, other necessary production and supply facilities such as a booster, an odor device, a gas holder, and a governor exist, but are omitted in the figure.

The city gas production plant 2 has an LNG tank 7,
An LPG tank 6, a vaporizer 9, and a hydrogen gas storage device 10 are provided.

Customers 4 and 5 are connected to the conduit 3b so that city gas equipment can be used.
Actually, a large number of customers are connected to the conduit network 3, but only two customers are displayed to avoid complication.

FIG. 2 shows a detailed configuration of the customer 4.
The customer 4 includes a fuel cell 16a, and further includes a hydrogen separator 15a, a controller 19a, a flow control valve 18a, and a separated gas return pipe 14 for controlling combustion of the fuel cell 16a.
a. The city gas flowing through the conduit 3b is
a and is led to the hydrogen separation device 15a. Further, a hydrogen concentration sensor 22a is provided in the path of the post-separation gas return pipe 14a downstream of the hydrogen separation device 15a. As the hydrogen concentration sensor, for example, a semiconductor sensor can be used.

The control unit 19a is a computer having a storage unit, a calculation unit, a control unit, and the like, and is configured to control the operation of the hydrogen separation unit 15a according to the hydrogen concentration in the separated gas. The control device 19a has a data table having the contents shown in FIG.

In FIG. 1, the customer 5 has a fuel cell 16
b, a hydrogen separator 15b, a controller 19b, a flow control valve 18b, and a hydrogen concentration sensor 22b. These structures are the same as those of the customer 4. The difference from the configuration of the customer 4 is that the customer 5 further includes a gas appliance 1 for 13A.
7 and 18 are provided.

Next, a method of adding hydrogen to the 13A city gas in the city gas manufacturing plant 2 and supplying the hydrogen gas to the city gas production plant 2 using a conduit network will be described with reference to FIG.

First, a method of adding hydrogen to the 13A gas will be described. The LNG supplied from the LNG tank 7 via the pipe 7a and the LPG supplied from the LPG tank 6 via the pipe 6a are mixed at a predetermined mixing ratio in the mixing section 8, and further mixed with the gas in the vaporizer 9. Become. Further, in the mixer 11, hydrogen supplied from the hydrogen gas storage device 10 is added. Here, the mixing ratio of LNG, LPG, and hydrogen gas is adjusted so as to be within the range of 13 A gas specified by WI and MCP. Conditioned hydrogenated city gas is supplied to conduit network 3 via conduit 12. The supply pressure can be set to any value, but the high pressure (1 MPa or more) and the medium pressure (0.1 M
Pa or more and less than 1 MPa), low pressure (less than 0.1 MPa)
It can also be three stages.

Next, hydrogen separation in the customer 4 and return to the conduit network will be described with reference to FIG.
13A city gas of hydrogen addition flowing in the conduit 3b
3a, hydrogen separation device 15a via flow control valve 18a
Supplied to A hydrogen separation membrane (not shown) is provided inside the hydrogen separation device 15a, and hydrogen contained in city gas is sucked by a vacuum pump 18a (not shown), passes through the separation membrane, and further passes through a pipe 17a. The fuel is supplied to the fuel cell 16a via the fuel cell 16a. On the other hand, components such as methane and propane other than hydrogen gas stay without passing through the separation membrane, and are returned to the conduit 3b via the gas pipe 14a. Although a vacuum pump was used on the downstream side of the separation membrane during hydrogen separation, it is important to generate a differential pressure through the separation membrane, and a booster may be used on the upstream side. In addition, conduit 3b
It can be returned via a booster or the like as necessary.

Next, a method for controlling the hydrogen concentration of the separated gas returning to the conduit 3b via the gas pipe 14a will be described. The hydrogen concentration in the gas after separation is determined by the gas return pipe 1 after separation.
It is measured at predetermined time intervals by a hydrogen concentration sensor 22a provided in the path of 4a, and the data is taken into the control device 19a. The computer of the control device 19a calculates WI and MCP based on the hydrogen concentration of the separated gas and the city gas composition supplied from the factory, and determines whether the composition of the separated gas is within the range of FIG. to decide. When this value is within the range of FIG. 3, the supply of hydrogen to the fuel cell 16a is continued. When the hydrogen concentration is out of the range shown in FIG. 3, the operation of the hydrogen separator is stopped. When the city gas composition supplied from the factory is almost constant, it can be stored in a computer as an initial value. Further, when the fluctuation of the composition of the city gas supplied from the factory cannot be ignored, it is possible to use the communication means described later. It goes without saying that the concentration of components other than hydrogen may be measured. By performing such control, the composition of the return gas can be set within the range shown in FIG. For example, in FIG. 3, the methane concentration of the city gas supplied to the customer 4 is 0.
7. When the hydrogen concentration is 0.24, the hydrogen separator 15
The limit that can be separated by a is that the hydrogen concentration of the separated gas is 0.13
Is the city gas composition

In the above description, the control of the hydrogen concentration of the separated gas is performed by starting and stopping the hydrogen separation device 15a. However, a method of adjusting the opening of the flow control valve 18a may be employed.

Next, the manner in which the customer 5 uses city gas will be described. The hydrogen separation and the return to the conduit network are the same as those of the customer 4 and will not be described. In the customer 5, the gas pipe 14b further connects the conduit 3
A part of the separated gas returned to b is guided to the gas appliances 17 and 18 via the gas pipe 14c. Since the hydrogen concentration of the separated gas is controlled in the same manner as in the customer 4, normal combustion of the gas appliances 17, 18 is ensured.

In the above embodiment, the separated hydrogen gas is supplied to the fuel cell 16a, but the supplied gas is a component that poisons the platinum catalyst of the hydrogen electrode (not shown) of the fuel cell 16a. For example, when carbon monoxide (CO) is not included, the city gas can be directly supplied to the fuel cell without installing a hydrogen separator. In this case, only the hydrogen molecules are selectively ionized at the hydrogen electrode and pass through the electrolyte, and the other molecular components cannot pass through the electrode and remain.
By returning the residual gas component to the conduit 3b, the same function as described above can be performed. In this case, the hydrogen electrode (not shown) of the fuel cell 16a functions as a hydrogen separator.

In the above embodiment, a hydrogen separation membrane is used as a hydrogen separation method for city gas. However, the present invention is not limited to this.
It is also possible to use a method capable of selectively separating hydrogen in another mixed gas, for example, PSA or the like.

Further, although a hydrogen concentration sensor is used as a method for measuring the hydrogen concentration of the gas after separation, a method of calculating the hydrogen concentration of the gas after separation from the amount of power generated by the fuel cell may be used.

FIG. 4 is a diagram showing another embodiment according to the present invention. In the present embodiment, the hydrogen concentration at each point of the conduit network is centrally controlled to achieve a stable supply. In FIG. 1, a city gas production and supply system 50 is shown.
Are city gas production plants A and B, center 52, conduit 5
Conduit network 51 consisting of 1a to 51c,
Hydrogen gas storage device 55 disposed in the path of conduit 51b
It has. Further, a group of consumers who receive the supply of city gas through the conduit network 51 include customers 53-1 to 53-n equipped with a hydrogen separation / return device and customers 54-1 to 53-n without the hydrogen separation and use conventional equipment. 1 to 54-m. Note that the numbers of city gas production plants, hydrogen gas storage devices, and the like are not limited to those shown in the figure, and any number can be selected as needed.

The center 52 and the factories A and B are configured to be able to exchange information via communication lines CL1 and CL2, respectively. The center 52 and the hydrogen gas storage device 55
Are connected by a communication line CL3. Further, the center 52 and the customers 53-1 to 53-n are also connected by a communication line. As the communication means, for example, an Internet line including a public telephone line, a packet communication network, and a digital public line such as ISDN, a dedicated line, a CATV line network, a satellite communication, a wireless communication, and the like can be used. Thereby, it is configured such that the hydrogen concentration data of the separated gas in each customer transmitted from the control device (not shown) provided in each customer can be monitored.

Next, control of the hydrogen concentration in the conduit network according to the present embodiment will be described. Center 52
Commands the consumers 53-1 to 55-n to transmit hydrogen concentration data at predetermined time intervals. Then, by storing the transmitted hydrogen concentration data in a computer (not shown) provided in the center 52, it is possible to grasp the hydrogen concentration distribution in the city gas in the conduit network. The center 52 instructs to select an optimum supply factory from the factories A and B based on the distribution data and to adjust the hydrogen concentration of the city gas to be sent to the factory. The commanded factory adjusts and supplies the hydrogen concentration of the city gas to be produced based on the command value.

The addition of the hydrogen gas is not limited to the factory, but can be performed from the hydrogen gas storage device 55 provided in the conduit network as needed. In this case, the center 52 is provided with a control valve 56 connected to the hydrogen gas storage device 55.
And hydrogenates the conduit 51b so as to be within the range of FIG. As described above, by continuously monitoring the hydrogen concentration distribution in the city gas in the conduit network, the WI and the MCP of the supply gas can be calculated and constantly controlled within the range shown in FIG.

[0050]

According to the present invention, on the premise of a conventional city gas supply system, a certain amount of hydrogen is mixed with a hydrocarbon-based gas (natural gas) to selectively use only conventional city gas equipment and hydrogen. A hydrogen-using gas device (such as a fuel cell) to be used can be used together. This enables a smooth transition to the hydrogen gas supply expected in the future.

In addition, since hydrogen can be directly supplied without passing through a natural gas reformer which burdens the operation of the fuel cell, quick start of the fuel cell becomes possible.

Further, by utilizing high-purity hydrogen separation by hydrogen separation, adsorption separation, or the like, the gas odorant causing poisoning of the fuel cell catalyst can be removed, so that the life of the fuel cell is prolonged. is there.

Further, hydrogen can be supplied to each home, office, and the like, and a hydrogen source for a fuel cell vehicle using hydrogen fuel can be supplied without a dedicated stand, thereby contributing to the popularization of the vehicle.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall view of a city gas production and supply system according to the present invention.

FIG. 2 is a diagram showing an equipment configuration of a city gas user according to the present invention.

FIG. 3 is a diagram showing an allowable concentration range of hydrogen, methane, CO, and CmHn of 13A gas.

FIG. 4 is a diagram showing another embodiment of the present invention.

FIG. 5 is a conceptual diagram showing a gas interchange area.

[Explanation of symbols]

1 · 50 ··· City gas production and supply system, 2 ··· City gas production plant, 3 · 51 ···· Conduit network, 3a · 3
b, 3c, 51a, 51b, 51c ... conduit, 4.5
53-1 to 53-n and 54-1 to 54-m... Customers, 6... LPG tanks 6, 7... LNG tanks, 9.
... Vaporizer, 10 ・ 55 ... Hydrogen gas storage device, 12 ...
... Pipeline, 15a / 15b ... Hydrogen separation device, 1
6a, 16b: fuel cell, 18a, 18b: flow control valve, 19a, 19b: hydrogen separation control device, 22.2
3 ... hydrogen partial pressure sensor, 25 ... vacuum pump, 52 ...
... Center, CL1-CL3 ... Communication line, 56 ... Control valve

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference)

Claims (14)

[Claims] 1. A city gas supply method for supplying a gas containing hydrogen gas through a conduit network, comprising: separating hydrogen gas in the city gas at one or more points in the conduit network; A city gas supply method comprising returning at least a part of a gas (hereinafter, referred to as a separated gas) to the conduit network. 2. The hydrogen gas separation is controlled so that the Wobbe index (WI) and the burning velocity index (CP) of the separated gas are within predetermined ranges. The city gas supply method described in 1. 3. WI is 52.7 ≦ WI ≦ 57.8,
The method according to claim 1, wherein the hydrogen gas separation amount is controlled so that CP satisfies 35 ≦ MCP ≦ 47. 4. WI is 49.2 ≦ WI ≦ 53.8,
The method according to claim 1, wherein the hydrogen gas separation amount is controlled so that CP satisfies 34 ≦ MCP ≦ 47. 4. 5. The city gas supply method according to claim 1, wherein the city gas is mainly composed of a hydrocarbon-based gas. 6. The city gas supply method according to claim 1, wherein the city gas contains methane as a main component. 7. The method for supplying city gas according to claim 1, further comprising the step of: determining whether a concentration of hydrogen gas at one or more points in said conduit network is less than a predetermined concentration. A hydrogen gas is added thereto. 8. The measurement of the hydrogen gas consumption is obtained by measuring the power generation of a fuel cell.
The city gas supply method described in 1. 9. A gas introducing means for introducing a city gas containing hydrogen gas by branching from a conduit network, a hydrogen gas separating means for separating hydrogen gas in the city gas, and a conduit for supplying at least a part of the separated gas. A hydrogen gas separation and return device comprising: a separation gas return means for returning to a network. 10. The gas separation and return device according to claim 9, wherein said hydrogen gas separation means includes a hydrogen separation membrane. 11. The gas separation and return device according to claim 9, wherein said hydrogen gas separation means is a hydrogen electrode of a fuel cell. 12. The gas separation and return device according to claim 9, wherein the gas introduction means and the separation gas return means include a double pipe having an inner pipe part and an outer pipe part. 13. The gas separation and return device according to claim 9, further comprising a hydrogen gas concentration measuring means. 14. A gas meter provided with the gas separation and return device according to claim 9.