Expansion turbine and compressor-type high-pressure hydrogen filling system and control method for same

Abstract

An expansion turbine/compressor type high-pressure hydrogen gas filling system is simple in configuration, low in site work cost, small in the burden of maintenance work, and capable of reducing the operating cost including cost of power consumption, and it is not necessary to separately provide a way to take out the energy produced in the expansion equipment and effectively use outside such as generator, and that can be applied for temperature lowering system technology such as pre-cooler function in the final filling portion of the hydrogen station, the expansion turbine portion has with a process to incorporate the expansion turbine/compressor in the expansion turbine portion in the filling system to do the enthalpy lowering of the hydrogen gas using the expansion turbine, when the hydrogen gas accumulated at high pressure is pressurized and filled into the tank.

Claims

1. A hydrogen filling system comprising: a tank; an expansion turbine/compressor that is provided with a-an expansion turbine and a compressor; a cooler that is provided at an entrance on an expansion turbine side of the expansion turbine/compressor; and a controller that is configured to: control an exit temperature of hydrogen gas of the cooler, and lower a temperature of the hydrogen gas using the expansion turbine when the hydrogen gas accumulated at a predetermined pressure is pressurized and filled into the tank.

2. The hydrogen filling system of claim 1, wherein the expansion turbine includes a first impeller for expansion on a first side of a rotating shaft and the compressor includes a second impeller for compression using rotating energy obtained by the expansion on a second side of the rotating shaft opposite the first side.

3. The hydrogen filling system of claim 1, wherein the expansion turbine/compressor is equipped with bearings of a dynamic gas bearing system using hydrogen gas that is supplied.

4. The hydrogen filling system of claim 1, wherein only one of the expansion turbine/compressor is provided in the hydrogen filling system.

5. The hydrogen filling system of claim 1, wherein the expansion turbine/compressor is one of a plurality of expansion turbine/compressors provided in the hydrogen filling system.

6. A control method of a hydrogen filling system that includes a tank, an expansion turbine/compressor that is provided with an expansion turbine and a compressor, and a cooler that is provided at an entrance on an expansion turbine side of the expansion turbine/compressor, the control method comprising: controlling an exit temperature of hydrogen gas of the cooler, and lowering a temperature of the hydrogen gas using the expansion turbine when the hydrogen gas accumulated at a predetermined temperature is pressurized and filled into the tank.

7. The control method of claim 6, wherein the exit temperature of the hydrogen gas of the cooler is detected and a cold energy amount of the cooler is adjusted so that the exit temperature will be a predetermined temperature.

8. The control method of claim 6, wherein when the hydrogen gas is pressurized and filled into the tank, a cold energy amount of the cooler is adjusted so that a predetermined gas temperature is obtained at each filling stage.

9. The control method of claim 6, wherein a pressure and temperature rise of the tank are detected and a cold energy amount of the cooler is adjusted so that a predetermined gas temperature is obtained at each filling stage.

10. The control method of claim 7, wherein the predetermined temperature of the exit temperature is set lower than in a stage where an initial filling is advanced.

Description

BRIEF EXPLANATION OF DRAWINGS

(1) FIG. 1 Graph to show filling rate, pressure and temperature changes of hydrogen gas by means of expansion (valve expansion) using the expansion valve

(2) FIG. 2 Explanatory drawing of hydrogen station using the conventional hydrogen pre-cool system

(3) FIG. 3 Explanatory drawing to show an embodiment of expansion turbine/compressor type high-pressure hydrogen gas filling system of this invention

(4) FIG. 4 Explanatory drawing to show modified embodiment of expansion turbine/compressor type high-pressure hydrogen gas filling system of this invention

(5) FIG. 5 Graph to show filling rate and pressure changes of hydrogen gas by means of expansion (valve expansion) using expansion valve (conventional system) and expansion turbine/compressor type high-pressure hydrogen filling system (embodiment) of this invention

(6) FIG. 6 Graph to show temperature changes of hydrogen gas by means of expansion (valve expansion) using expansion valve (conventional system) and expansion turbine/compressor type high-pressure hydrogen gas filling system (embodiment)

(7) FIG. 7 Explanatory drawing to show an embodiment of system configuration of expansion turbine/compressor type high-pressure hydrogen filling system to implement the control method of the expansion turbine/compressor type high-pressure hydrogen filling system of this invention

(8) FIG. 8 Graph to show the relationship between filling completion temperature and turbine efficiency when the temperature of hydrogen gas is changed by providing a cooler at the entrance portion of the expansion turbine side

(9) FIG. 9 Explanatory drawing to show an embodiment of the system configuration of the expansion turbine/compressor type high-pressure hydrogen filling system to implement the control method of the expansion turbine/compressor type high-pressure hydrogen filling system of this invention

EMBODIMENTS TO IMPLEMENT THE INVENTION

(10) Below the embodiments of the expansion turbine/compressor type high-pressure hydrogen filling system and the control method of this invention are explained in accordance with the drawings.

(11) This expansion turbine/compressor type high-pressure hydrogen filling system has the expansion turbine/compressor type high-pressure hydrogen filling system of this invention applied for the hydrogen pre-cool system used to lower the temperature of the hydrogen gas at the final filling portion of the hydrogen station, and it is provided with a process to incorporate the expansion turbine/compressor in the expansion turbine portion in the filling system to do enthalpy lowering of the hydrogen gas using the expansion turbine when the hydrogen gas accumulated at high pressure is pressurized and filled in the tank.

(12) Here the process to incorporate the expansion turbine/compressor is provided in the expansion turbine portion, and so in this embodiment, it is possible to use the turbine/compressor generally used for compression and expansion of refrigerant (called “expansion turbine/compressor” in this specification) having an impeller for expansion on one side of the rotating shaft and impeller for compression on the other side.

(13) This expansion turbine/compressor can be provided with bearings (bearings to support both radial and thrust directions) of dynamic gas bearing system using the hydrogen gas supplied.

(14) Specifically, like the final expansion mechanism of the hydrogen gas of the hydrogen station shown in FIG. 3, this hydrogen pre-cool system 10 has the hydrogen gas source line 9 connected to the circuit of the expansion turbine/compressor and the hydrogen gas subjected to enthalpy lowering (temperature lowering) is finally expanded by the expansion turbine/compressor 11 and filled in the fuel tank of a hydrogen automobile via the hydrogen gas supply unit 13.

(15) Here, the expansion turbine/compressor 11 is provided with the expansion turbine 11a having the impeller for expansion on one side of the rotating shaft and compressor 11b having the impeller for compression on the other side, and by utilizing the rotating energy obtained on the expansion turbine 11a side, the pressure of the hydrogen gas is raised and the hydrogen gas is introduced to the entrance of the expansion turbine 11a (the hydrogen gas is supplied to the compressor 11b and then supplied to the expansion turbine 11a)) thus the expansion ratio of the expansion turbine 11a is increased for the pressure raised by the compressor 11b making it possible to obtain more heat drop (cold generation).

(16) It is possible to provide a cooler 12 in the entrance portion on the expansion turbine 11a side of the expansion turbine turbine/compressor 11.

(17) For the low temperature heat source 12a of the cooler 12, a water cooling system or chiller unit system can be used as preferably.

(18) Though the illustration is omitted, a similar cooler can be installed in the entrance portion on the compressor 11b side. In this case, the cooler 12 provided in the entrance portion on the expansion turbine 11a side can be omitted.

(19) This can assist the temperature lowering of the hydrogen gas, and by lowring the temperature of the hydrogen gas to a proper value, it becomes possible to secure room for the temperature at the completion of tank filling and establish the process with an expansion turbine of lower efficiency.

(20) FIG. 5 and FIG. 6 show the filling flow rate and pressure and temperature changes by the expansion (valve expansion) using the expansion valve of hydrogen gas (conventional system) and the expansion turbine/compressor type high-pressure hydrogen filling system of this invention (embodiment).

(21) By applying the expansion turbine/compressor type high-pressure hydrogen filling system of this invention for the hydrogen pre-cool system used for lowering the temperature of hydrogen gas in the final filling portion of a hydrogen station, it is possible to fill the hydrogen gas expanded by driving the expansion turbine/compressor 11 by utilizing the pressure difference from the high pressure (82 MPa) (main pressure) of the hydrogen gas source line 9 directly into the fuel tank of a hydrogen automobile.

(22) In this case, since the difference between the main pressure and the pressure in the fuel tank 6 is large in the initial filling, the expansion ratio with the expansion turbine 11a and the expansion ratio by the compressor 11b can be secured rather large, and so more cold can be generated.

(23) As the filling proceeds, the pressure in the fuel tank increases and the cold generated by the expansion turbine/compressor 11 decreases, but the filling can be finally completed at 85 C or lower.

(24) By the way, one unit of expansion turbine/compressor 11 is used in the embodiment shown in FIG. 3 but multiple units can be arranged in series as shown in the modified embodiment shown in FIG. 4, and the multiple units arranged in series can be arranged in parallel.

(25) This makes it possible to operate the expansion turbine/compressor 11 with the expansion rate in the maximum area at each expansion ratio, secure room for the cost generation, easily increase the equipment flow rate, and make the filling equipment for large fuel cell bus and truck without a large pre-cool cooler. By the way, in the embodiment shown in FIG. 3 (same with the embodiment shown in FIG. 4), as shown in FIG. 7, the cooler 12 and controller 14 are provided in the entrance portion on the expansion turbine 11a side of the expansion turbine/compressor 11 so as to control the exit temperature of the hydrogen gas of the cooler 12.

(26) Such configuration can properly lower the exit temperature of hydrogen gas of the cooler 12, thus making it possible to secure some room for the temperature in the fuel tank at completion of filling.

(27) In FIG. 7, by lowering the exit temperature of hydrogen gas of the cooler 12 from ordinary temperature of about 33 C to 25 C or 20 C by means of the controller 14, it is possible to secure room for the temperature rise in the fuel tank 6 after filling, making it possible to design the process with an expansion turbine of lower efficiency, as shown in FIG. 8. That is, the target temperature can be achieved by adjusting the cold of the cooler 12 instead of lowering the temperature with a new cooler.

(28) In this case, it is desirable to detect the exit temperature of hydrogen gas of the cooler 12, set it relatively low during the first filling time (20 to 30 seconds), program proper cold generation as the filling proceeds (as cold load decreases), and have the exit temperature of hydrogen gas follow the target temperature.

(29) Specifically, the control of the protocol to fill hydrogen gas into the fuel tank 6 is to be made by the controller provided in the hydrogen gas supply unit 13. In this case, the filling can be done with minimum external energy without doing wasteful cooling by internally calculating the optimum cold to meet the filling time allocation specified in advance and through optimum control of the entrance temperature of the expansion turbine 11a (exit temperature of cooler 12).

(30) It is also possible to have the exit temperature of hydrogen gas follow the target temperature by detecting the pressure and temperature rise in the fuel tank 6.

(31) Specifically, it is possible to do the filling with minimum external energy without doing wasteful cooling by detecting the present pressure and temperature of the fuel tank 6 on the hydrogen gas supply unit 13, calculating the optimum cold quantity to the filling completion and controlling optimum the entrance temperature of the expansion turbine 11a (exit temperature of cooler 12) through automatic control, as shown in FIG. 9.

(32) By applying the expansion turbine/compressor type high-pressure hydrogen filling system for the hydrogen pre-cool system used to lower the temperature of hydrogen gas in the final filling portion of the hydrogen station, it is possible to solve as follows the problems of the hydrogen pre-cool system used to lower the temperature of hydrogen gas in the final filling portion of the conventional hydrogen station. Problem 1): Since the external power is not required for operating the expansion turbine/compressor itself, almost no power is required in comparison with the operating cost (electricity charge) of the conventional hydrogen pre-cool system. Problem 2): Since the refrigerant does not exist, the system is not subjected to the refrigeration rule. It can be coped with within the High Pressure Gas Safety Act of the entire hydrogen station. Problem 3): Since the CFC refrigerant and brine itself does not exist, there is no more risk of environmental accidents. Problem 4): Since system configuration is very simple, not only operating cost but also maintenance cost can be greatly reduced. Problem 5): Since the temperature lowered state can be created simultaneously with the starting of the expansion turbine/compressor, the time constant within the system is very small. The time of prior starting is small. Problem 6): Since only the cold box of the expansion turbine/compressor is required, large space-saving is achieved. It is about 10 % in volume ratio in comparison with the conventional system Problem 7): By combining multiple units of expansion turbine/compressor or using expansion turbine/compressor of optimum flow rate, it is possible to easily increase the equipment flow rate and make filling equipment for large fuel cell bus and truck without a large pre-cool cooler. Problem 8): By using the expansion turbine/compressor, it is not necessary to separately provide a means to take out the energy produced in the expansion equipment and effectively use it, and furthermore, by raising the pressure of hydrogen gas on the compressor side by utilizing the rotating energy obtained on the expansion turbine side and introducing it to the expansion turbine entrance, the expansion ratio of the expansion turbine increases for the pressure raised by the compressor, thus making it possible to obtain the heat drop (cold generation), and by lowering the temperature of hydrogen gas to a proper value by providing a cooler at the entrance portion of the expansion turbine side, it becomes possible to secure some room for temperature at the completion of tank filling and establish a process with an expansion turbine of lower efficiency.

(33) So far the expansion turbine/compressor type high-pressure hydrogen filling system and the control method have been explained in accordance with the embodiments, but the invention is not limited to the configuration described in the above embodiments, and the configuration can be changed as required within the range deviated from the purpose.

Possibility of industrial application

(34) The expansion turbine/compressor type high-pressure hydrogen filling system and the control method of this invention is characterized in that the configuration is simple, site work cost is low, the load of maintenance work is small, the operating cost including the cost of power consumption is small, and it is not necessary to separately provide a means to take out the energy produced in the expansion equipment and effectively utilize outside such as generator, and so it can be preferably used for the application of the hydrogen pre-cool system in the final filling portion of the hydrogen station.

EXPLANATION OF SIGNS

(35) 1 Compressor equipment 2 Hydrogen accumulating equipment 3 Expansion valve 4 Pre-cooler 5 Hydrogen pre-cool system 6 Fuel tank (tank) 7 Refrigerator equipment 8 Brine circuit 9 Hydrogen gas source line 10 Hydrogen pre-cool system 11 Expansion turbine/compressor 11a Expansion turbine 11b Compressor 12 Cooler 12a Low temperature heat source 13 Hydrogen gas supply unit