JP6525262B2 - Hydrogen precool system - Google Patents

Description

  The present invention, in a hydrogen station, fills hydrogen fuel from a hydrogen gas supply source into a fuel tank of a hydrogen automobile as a fuel for a hydrogen automobile such as a fuel cell automobile (hereinafter simply referred to as "hydrogen automobile"). In particular, it relates to a hydrogen precool system used to lower the temperature of hydrogen gas at the final filling of a hydrogen station.

Hydrogen gas, which is used as fuel for hydrogen vehicles, is characterized by its reverse temperature (-58 ° C) due to its properties when subjected to adiabatic expansion (isenthalpy expansion) from high pressure at parts such as an expansion valve provided in the hydrogen gas charging path. The Joule-Thomson effect has the property that the temperature after expansion rises due to the expansion in the high region.
Therefore, at the hydrogen station, when hydrogen gas to be fueled by the hydrogen car is filled from the hydrogen gas supply source into the fuel tank of the hydrogen car, a portion such as an expansion valve provided in the path filled with hydrogen gas The temperature of hydrogen gas rises.

Since the rise in the temperature of this hydrogen gas becomes more remarkable as the expansion ratio of hydrogen gas becomes larger, the pressure increase of the feed gas from the hydrogen gas supply source at the hydrogen station (for example, 45 → 70 MPa (G), further With the increase of 82 MPa (G)), the self temperature rise amount becomes larger.
As an example, FIG. 1 shows an example of self-temperature change at each secondary pressure when hydrogen gas is expanded in one step from 70 MPa (G) and 30 ° C.

  On the other hand, in a fuel cell vehicle that has started to be widely spread under the present circumstances, the maximum temperature upper limit at the time of hydrogen charging is about 85 ° C., due to the temperature limitation by the material of the fuel tank and the limitation of the operation temperature of the fuel cell main cell.

  And, because of the nature of hydrogen, if hydrogen gas is filled as it is without any measures, the temperature at hydrogen filling exceeds the maximum temperature limit of 85 ° C., and the temperature limit by the material of the fuel tank or the fuel cell In order to cause problems such as limitation of the operating temperature of the main cell and pressure drop due to cooling after filling, a cooling means such as a heat exchanger is disposed in the path filled with hydrogen gas, and this cooling means A method for filling hydrogen vehicles while cooling gas has been proposed and put into practical use (see, for example, Patent Document 1).

JP 2004-116619 A

Here, FIG. 2 shows a block diagram of the current general 70 MPa (G) hydrogen station.
The hydrogen station comprises a compressor installation 1 comprising a compressor unit for receiving hydrogen gas, a hydrogen storage installation 2 comprising an accumulator unit for accumulating hydrogen gas sent from the compressor installation 1 and a hydrogen storage installation 2 An expansion valve 3 and a hydrogen gas precooler 4 provided in a path for charging the hydrogen gas into the fuel tank 6 of the hydrogen car, and a hydrogen precool system 5 for cooling the hydrogen gas through the precooler 4; The hydrogen precool system 5 is provided with a refrigerator installation 7 consisting of a compressor, a condenser, an expansion valve, an evaporator, an accumulator etc., and a brine circuit 8 consisting of a brine tank, a primary brine pump, a secondary pump etc. ing.
And, in this hydrogen station, hydrogen received by both the on-site type and off-site type hydrogen stations is intermediate pressure (40 MPa (G) in the illustrated example) or high pressure (82 ) And held in the form of compressed gas in the accumulator unit of the hydrogen accumulator 2 at each pressure.
In order to fill these hydrogen gas into the on-demand fuel tank 6 on the demand side, expansion is performed via the expansion valve 3, but at that time, the temperature rise of the hydrogen gas itself is accompanied, so It is cooled to -40 ° C by a hydrogen pre-cool system 5.
In the present technology, this hydrogen precool system 5 is configured by combining a normal refrigerator installation 7 such as fluorocarbon refrigerant and a brine circuit 8 operating around -40 ° C, so the configuration is complicated, In addition, many rotating devices such as a refrigerant compressor for a refrigerator, a primary brine pump, and a secondary brine pump are also required.

For this reason, the following problems were encountered in the hydrogen pre-cool system used to lower the temperature of hydrogen gas in the final filling section of the conventional hydrogen station.
1) The external independent hydrogen precool system is a system that itself operates with external power. It is about 40 kW at a typical hydrogen station (300 Nm ³ / h), and the operation of the hydrogen precool system itself increases the operation cost.
2) Due to the use of chlorofluorocarbons (refrigerant fluorocarbons) as refrigerants in refrigerators, the precooler equipment itself is subject to the refrigeration safety regulations of the High Pressure Gas Safety Act, and is restricted in equipment and operation.
3) Having fluorocarbons and brines in the station requires measures to prevent environmental accidents from external leaks of fluorocarbons and brines.
4) Many maintenance and management services occur because the hydrogen precool system is complicated by the two-stage configuration of the refrigeration circuit and the brine circuit, and there are multiple rotating machines such as a refrigerant compressor and a brine pump.
5) Because of the system via brine, it takes time from startup to steady state. For this reason, it is necessary to start the hydrogen precool system and keep the inside of the system in a steady state long before the filling operation.
6) When miniaturizing the installation space of the hydrogen station itself, the exclusive space of the hydrogen precool system is the limitation.
7) At the current temperature of -40 ° C, there is a limit to the rapid filling of additional hydrogen. In the future, in order to further shorten the filling time, precooling may be required to a temperature lower than the current temperature of -40 ° C.

  In view of the problems of the hydrogen precool system used to lower the temperature of hydrogen gas in the final filling section of the conventional hydrogen station, the present applicant has first made the configuration in Japanese Patent Application No. 2015-059233. We have proposed a hydrogen pre-cool system that is used to lower the temperature of hydrogen gas in the final filling section of the hydrogen station, which is simple, has a low burden of maintenance and management costs, and can reduce operating costs including power consumption costs. .

The hydrogen precool system used to lower the temperature of hydrogen gas in the final filling section of the hydrogen station has the hydrogen precool system used to lower the temperature of hydrogen gas in the final filling section of the conventional hydrogen station. Although the problem can be solved, there are the following problems.
8) In a hydrogen pre-cool system using an expander, for example, in a facility for filling one fuel cell vehicle, the flow rate often falls at a relatively small flow rate. In that case, when the expander is configured by a hydrogen turbine, It may be a very small microturbine class. In this micro turbine, it becomes difficult from the viewpoint of cost reduction effect and reliability ensuring to a general-purpose hydrogen turbine.

  In view of the problems of the hydrogen precool system used to lower the temperature of hydrogen gas in the final filling section of the conventional hydrogen station described above, the present invention has a simple configuration, less burden on maintenance and management services, and power consumption. Provide a hydrogen pre-cool system used to lower the temperature of hydrogen gas at the final filling of a hydrogen station, which is inexpensive to operate including the cost of The purpose is to

To achieve the above object, the hydrogen pre-cool the system of the present invention, hydrogen in the hydrogen filling stations for filling the hydrogen gas from the hydrogen gas source that is accumulated in the high pressure, the pressure difference expansion through the valve to the other side of the tank Purekuru In the system
The circuit is branched from the hydrogen gas source, one is connected to the primary buffer tank, and the other is connected to the primary bypass line via the primary bypass expansion valve,
The circuit is branched from the primary buffer tank, and one is joined to the secondary buffer tank via the expander and the other via the secondary bypass expansion valve and the secondary bypass line, respectively.
The primary bypass line is merged with the circuit from the secondary buffer tank via a heat exchanger installed inside the secondary buffer tank, and the tank on the other side is filled via a hydrogen dispenser. by doing,
In the process of expanding and depressurizing hydrogen gas, the temperature of the hydrogen gas is lowered by the expander and the primary and secondary buffer tanks provided before and after it, and the cold energy is used to pre-cool the hydrogen gas It is characterized by

In this case, the hydrogen gas inflated directly by the primary expansion valve from said source of hydrogen gas may be Rukoto to supply to the primary buffer tank.

Further, the hydrogen gas inflated directly by the secondary expansion valve from said primary buffer tank can be Rukoto to supply to the expander.

  In addition, any one or a combination of a hydrogen turbine, a reciprocating mechanical expander, a rotary expander, and a scroll expander can be used as the expander.

According to the hydrogen precool system of the present invention, in the hydrogen precool system in the hydrogen filling facility for filling the tank with hydrogen gas accumulated at high pressure by pressure differential expansion through the opposite valve, the expander and Specifically, for example, a hydrogen turbine, a reciprocating mechanical expander, a rotary expander, and a scroll expander, or a combination thereof, by a primary buffer tank and a secondary buffer tank provided before and after it. By using it to lower the temperature of hydrogen gas and precooling hydrogen gas using its cold energy, the configuration is simple, the burden on maintenance and management services is small, and the cost of power consumption is reduced. Hydrogen used to lower the temperature of hydrogen gas in the final filling section of the hydrogen station, which can reduce the operating costs involved It is possible to provide a record cool system.
Then, a primary buffer tank and a secondary buffer tank may be provided before and after the expander, and a secondary bypass line may be provided to connect the primary buffer tank and the secondary buffer tank without the expander. The heat exchanger of the primary bypass line is provided inside the secondary buffer tank to supply the hydrogen gas directly expanded from the hydrogen gas source line by the primary bypass expansion valve to the demand side. It is possible to utilize a small flow expander designed for one fuel cell vehicle, for example, an expander such as a relatively large general-purpose hydrogen turbine instead of a micro turbine. Then, the remaining cold in the secondary buffer tank can be provided to the valve-expanding hydrogen gas from the high-pressure hydrogen gas and effectively used, thereby providing an efficient hydrogen pre-cool system.

It is a graph which shows an example of temperature rise by expansion (valve expansion) using the expansion valve of hydrogen gas, and expansion (turbine expansion) using a hydrogen turbine. It is explanatory drawing of the hydrogen station using the conventional hydrogen precool system. It is an explanatory view showing one example of a hydrogen precool system of the present invention. It is an explanatory view showing the important section.

  Hereinafter, an embodiment of a hydrogen precool system of the present invention will be described based on the drawings.

  This hydrogen pre-cool system is a hydrogen pre-cool system used to lower the temperature of hydrogen gas in the final filling section of the hydrogen station, and by pressure-differential expansion of the hydrogen gas accumulated at high pressure through the opposite valve. In the hydrogen precooling system in the hydrogen filling facility for filling the tank, the temperature of hydrogen gas is lowered by the expander and the primary buffer tank and the secondary buffer tank provided in the process of expanding and reducing the hydrogen gas, and The cold energy is used to pre-cool hydrogen gas.

Specifically, like the final expansion mechanism of hydrogen gas at a hydrogen station shown in FIG. 3, this hydrogen precool system 10 branches a part of the gas of the hydrogen gas source line 9 and expands the expander, for example, A circuit of a hydrogen turbine 11 generally used as an expander is provided.
The hydrogen is expanded by the hydrogen turbine 11 and the temperature-reduced hydrogen gas is rejoined. If necessary, the pressure may be expanded to an intermediate pressure and mixed, and finally the tank may be finally expanded and filled with a small expansion ratio.
In FIG. 3, the high pressure hydrogen gas branched under high pressure is supplied to the hydrogen turbine 11 through the turbine inlet valve, and the expansion by the hydrogen turbine 11 always causes a temperature drop (see FIG. 1. Here, FIG. 1) Is an example of calculation, and the outlet temperature can be controlled in a wide range by the inlet condition of the hydrogen turbine 11 and the setting of the expansion ratio etc.), so the turbine outlet temperature drops from the inlet.
The expanded gas is combined and mixed with the expanded gas, and as the optimum temperature, the tank is continuously filled at a final low expansion ratio.
Then, the pressure and temperature conditions of the other side of the filling are detected by a sensor, and feedback control is performed to obtain an optimal mixing temperature. By controlling the hydrogen turbine inlet valve according to this temperature command, the temperature drop width and the temperature after mixing are maintained in an appropriate range by changing the flow rate of the turbine circuit.

  More specifically, as shown in FIG. 4, the hydrogen precool system 10 is filled with hydrogen gas from the high pressure hydrogen gas source line 9 to the demand side through the hydrogen dispenser 21.

When the demand destination is a low pressure, the intermediate pressure gas is expanded to the primary buffer tank 14 through the primary expansion valve 12. From the primary buffer tank 14 through the secondary expansion valve 13, the hydrogen turbine 11 is expanded as far as the expansion ratio can be obtained and expanded to the pressure of the secondary buffer tank 15.
The secondary buffer tank 15 supplies hydrogen gas to the demand side (after the hydrogen dispenser 21) via the final expansion valve 20, but at the beginning of filling, a predetermined amount of hydrogen gas expanded and lowered in temperature by the hydrogen turbine 11 Is extracted from the final expansion valve 20, so the difference between the processing flow rate of the hydrogen turbine 11 and the final expansion amount is gradually stored in the secondary buffer tank 15, and at the same time, the secondary buffer tank 15 is externally insulated. The temperature of the secondary buffer tank 15 itself is also lowered due to the cold of the hydrogen gas whose temperature has dropped. Therefore, even if the temperature rise in the final expansion valve 20 occurs, a sufficiently low hydrogen gas temperature can be maintained.

Then, after the internal pressure of the secondary buffer tank 15 rises, the differential pressure with the primary buffer tank 14 narrows, and the drive of the hydrogen turbine 11 is stopped, the secondary bypass expansion valve 18 is started from the primary buffer tank 14. The supply of hydrogen gas to the demand side is continued by directly expanding the hydrogen gas and supplying the hydrogen gas to the secondary buffer tank 15 through the secondary bypass line 19.
At this time, since the secondary buffer tank 15 which has been excessively cooled is passed, temperature rise on the demand side can be prevented.

  Furthermore, as the pressure on the demand side rises, if the pressure in the secondary buffer tank 15 does not catch up with the pressure, hydrogen gas is directly expanded from the hydrogen gas source line 9 by the primary bypass expansion valve 16, 1 The supply of hydrogen gas to the demand side is continued via the next bypass line 17. Since the primary bypass line 17 passes through the heat exchanger 17 a installed inside the secondary buffer tank 15, the temperature inside the secondary buffer tank 15 is effectively utilized to raise the temperature of the hydrogen gas. There is no filling up to the final pressure.

The supply of each of these hydrogen gases is designed to be able to switch and control the optimum expansion filling line route and flow rate at all times while automatically monitoring the pressure of each.
As an example, the pressure of the hydrogen gas source line 9 is 820 atm, the pressure of the primary buffer tank 14 is 400 to 600 atm, and the pressure of the secondary buffer tank 15 is 20 to 600 atm. Expansion), cold surplus generation and expansion route switching are performed, and the demand side is pressurized and filled within a predetermined time until the final filling pressure.

  If there is residual pressure in the secondary buffer tank 15 at the collection stage of one filling, in the next filling cycle, the filling is started first by gas expansion from the secondary buffer tank 15, and the secondary buffer tank is started. When the pressure 15 becomes an outlet pressure corresponding to the drive of the hydrogen turbine 11, the hydrogen turbine 11 is driven to generate refrigeration.

  As a result, it is possible to utilize a relatively large general-purpose hydrogen turbine 11 rather than a small flow rate micro turbine designed for one fuel cell vehicle on the filling side. Then, the remaining refrigeration in the secondary buffer tank 15 can be provided to the valve-expanding hydrogen gas from the high-pressure hydrogen gas and effectively used, thereby providing an efficient hydrogen pre-cool system.

  In this case, in addition to the above-mentioned hydrogen turbine 11 (see, for example, Japanese Patent Application Laid-Open Nos. 2003-106108 and 2012-206909), a reciprocating machine is widely used as an expander for the expander. Expanders (see, for example, JP-A-61-262558), rotary expanders (see, for example, JP-A-2007-9755) and scroll-type expanders (see, for example, International Publication WO 2012/164609) Or any combination thereof.

Moreover, the following systems can be mentioned as a means to take out the energy by the said expander.
1) Braking by brake fan (conversion to heat by water cooling cooler)
2) Generational braking by incorporating a generator 3) Boosting of process hydrogen by a booster blower

  In this hydrogen precool system 10, high pressure hydrogen gas branched under high pressure is supplied to the hydrogen turbine 11 via a turbine inlet valve, and expansion by the hydrogen turbine 11 always causes a temperature drop (FIG. 1), The turbine outlet temperature drops from the inlet. The expanded gas is merged and mixed with the expanded gas, and the secondary buffer tank 15 is continuously filled at a low expansion ratio as an optimum temperature.

According to the above principle, this hydrogen precool system can solve the problems of the hydrogen precool system used to lower the temperature of hydrogen gas in the final filling section of the conventional hydrogen station as follows.
As for Problem 1), since the operation of an expander such as a hydrogen turbine does not require external power, almost no power is required for the operating cost (the electricity cost) of the conventional hydrogen precool system.
As for problem 2), since there is no refrigerant, the system is not separately affected by the freezing law. It can be dealt with in the High Pressure Gas Safety Act of the entire hydrogen station.
As for Problem 3), there is no risk of environmental accidents because fluorocarbon refrigerant and brine itself do not exist.
As for the problem 4), since the system configuration is simple, not only the operation cost but also the maintenance cost can be significantly reduced.
With regard to problem 5), since the temperature drop can be made simultaneously with the start of the expander such as a hydrogen turbine, the time constant in the system is very small. Pre-start time will be small.
As for Problem 6), since only the cold box of an expander such as a hydrogen turbine is required, significant space saving can be achieved.
As for the problem 7), the temperature can be precooled to near -100 ° C. by an expander such as a hydrogen turbine and can cope with more rapid filling.
As for Problem 8), it becomes possible to use the system configuration and surplus cooling by using a general-purpose hydrogen turbine, and it is high cost, low reliability, low when using a small flow rate micro turbine designed only with the required filling flow rate It can solve the problem of efficiency. In addition, it is possible to use the previous surplus cold first in the next filling of batch filling.

  As mentioned above, although the hydrogen precool system of this invention was demonstrated based on the Example, this invention is not limited to the structure described in the said Example, The structure is suitably changed in the range which does not deviate from the meaning. It is something that can be done.

  The hydrogen pre-cool system of the present invention is simple in construction, less burdened on maintenance and management services, can reduce the operating cost including the cost of power consumption, and is also applicable to filling equipment that can be accommodated with a relatively small flow rate. Because of this property, it can be suitably used for the application of the hydrogen precool system used to lower the temperature of hydrogen gas in the final filling section of the hydrogen station.

DESCRIPTION OF SYMBOLS 1 compressor installation 2 hydrogen storage installation 3 expansion valve 4 precooler 5 hydrogen precool system 6 fuel tank 7 refrigerator installation 8 brine circuit 9 hydrogen gas source line 10 hydrogen precool system 11 hydrogen turbine (expansion machine)
12 primary expansion valve 13 secondary expansion valve 14 primary buffer tank 15 secondary buffer tank 16 primary bypass expansion valve 17 primary bypass line 18 secondary bypass expansion valve 19 secondary bypass line 20 final expansion valve 21 hydrogen dispenser

Claims (4)

The hydrogen gas from the hydrogen gas source that is accumulated in the high pressure, the hydrogen pre-cool the system in a hydrogen filling stations for filling the other side of the tank by a pressure difference expansion through the valve,
The circuit is branched from the hydrogen gas source, one is connected to the primary buffer tank, and the other is connected to the primary bypass line via the primary bypass expansion valve,
The circuit is branched from the primary buffer tank, and one is joined to the secondary buffer tank via the expander and the other via the secondary bypass expansion valve and the secondary bypass line, respectively.
The primary bypass line is merged with the circuit from the secondary buffer tank via a heat exchanger installed inside the secondary buffer tank, and the tank on the other side is filled via a hydrogen dispenser. by doing,
In the process of expanding and depressurizing hydrogen gas, the temperature of the hydrogen gas is lowered by the expander and the primary and secondary buffer tanks provided before and after it, and the cold energy is used to pre-cool the hydrogen gas Hydrogen precool system characterized by. The hydrogen precool system according to claim 1, wherein the hydrogen gas expanded directly from the hydrogen gas source by the primary expansion valve is supplied to the primary buffer tank. The hydrogen precool system according to claim 1 or 2, wherein hydrogen gas directly expanded from the primary buffer tank by a secondary expansion valve is supplied to an expander .   4. The hydrogen precool system according to claim 1, 2 or 3, wherein the expander is a hydrogen turbine, a reciprocating mechanical expander, a rotary expander, a scroll expander or any combination thereof. .

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