System For Producing And Dispensing Pressurized Hydrogen

Abstract

A system for producing and dispensing pressurized hydrogen includes: a hydrogen generator, in particular an electrolyser, a hydraulic drive, two or more hydrogen storage tanks, and a hydrogen dispensing unit, wherein each of the hydrogen storage tanks is capable of discharging hydrogen at a constant pressure by movement of an internal piston, wherein at least one of the hydrogen storage tanks is arranged to act as compressor by actuation of the internal piston by the hydraulic drive, and wherein at least one of the hydrogen storage tanks is arranged to act as a constant pressure tank for storing and discharging hydrogen at a constant pressure.

Claims

1. A System for producing and dispensing pressurized hydrogen comprising: a hydrogen generator; a hydraulic drive; two or more hydrogen storage tanks; and a hydrogen dispensing unit, wherein each of the two or more hydrogen storage tanks is configured for discharging hydrogen at a constant pressure by movement of an internal piston, wherein at least one of the two or more hydrogen storage tanks is arranged to act as compressor by actuation of the internal piston by the hydraulic drive, and wherein at least one of the two or more hydrogen storage tanks is arranged to act as a constant pressure tank for storing and discharging hydrogen at a constant pressure.

2. The system according to claim 1, wherein the hydrogen generator produces hydrogen at a pressure between 1 and 45 bar.

3. The system according to claim 1, wherein the two or more hydrogen storage tanks are configured for pressures up to 900 bar.

4. The system according to claim 1, further comprising a catalyst for removing oxygen residues from the hydrogen.

5. The system according to claim 1, wherein the hydrogen generator is configured to produce hydrogen and oxygen, wherein the system further comprises: an oxygen expander for reducing the pressure of the produced oxygen and thereby cooling of the produced oxygen; and a heat exchanger for transferring heat between the cooled oxygen and the hydrogen downstream of the electrolyser and upstream of the compressor.

6. The system according to claim 1, wherein a condenser for separating water from the compressed hydrogen is arranged upstream of the compressor.

7. The system according to claim 6, further comprising a water reservoir connected to the electrolyser; and a return pipeline connecting the condenser with the water reservoir.

8. The system according to claim 1, wherein the two or more hydrogen storage tanks are identical.

9. The system according to claim 1, further comprising a hydrogen buffer tank upstream of the compressor.

10. The system according to claim 1, wherein the compressor is a one-stage compressor.

11. The system according to claim 1, wherein a wireless communication device is connected to the system and configured to allow customers to check the current filling level of the hydrogen storage tanks and to book a time slot for refueling.

12. The system according to claim 1, wherein the system is configured as a mobile unit.

Description

[0047] The invention as well as preferred embodiments of the invention will be described with reference to the enclosed drawing.

[0048] FIG. 1 shows an inventive system for producing and dispensing hydrogen.

[0049] The inventive system as shown in FIG. 1 makes use of an electrolyser 1 as hydrogen generator. A cooling loop with integrated cooler 26 rejects generated process heat. A water reservoir 2 is connected to the electrolyser 1 via a water supply line 3 and supplies the electrolyser 1 by means of a pump 25 with deionized water at a pressure of for example 40 bar.

[0050] The electrolyser 1 produces hydrogen and oxygen at a pressure of around 40 bar. Depending on the type and size of the electrolyser the hydrogen production rate varies between 1.5 kg hydrogen per day and 20 kg hydrogen per day, preferably between 2.5 kg per day and 15 kg per day.

[0051] The produced hydrogen gas is then passed through a back pressure regulator 6 which automatically opens when the electrolyser reaches its operation pressure. The back pressure regulator 6 prevents the hydrogen to flow back to the electrolyser 1. The hydrogen is then passed through a catalyst 8 in order to remove any oxygen residues. The hydrogen gas can be cooled by an air cooler 9. Downstream of the air cooler 9 a condenser 20 is provided to remove water vapor from the hydrogen stream. As will be explained below in greater detail the oxygen generated by the electrolyser 1 at elevated pressure can be used as a coolant for such purpose.

[0052] The system comprises three identical hydrogen storage tanks 10a, 10b, 10c. The hydrogen storage tanks 10a, 10b, 10c are each provided with an internal piston 11a, 11b, 11c. The internal pistons 11a, 11b, 11c each divide the hydrogen storage tanks 10a, 10b, 10c into a hydrogen section 12a, 12b, 12c and a hydraulic section 13a, 13b, 13c.

[0053] One of the hydrogen storage tanks acts as a compressor 10a. The hydrogen gas leaving condenser 20 is passed into the hydrogen section 12a of the compressor 10a. In the compressor 10a the internal piston 11a moves in a slow motion and compresses the hydrogen to a pressure level of 850 bar. The piston 11a is driven by a hydraulic drive 16 which uses the hydraulic fluid provided by tank 27. Upstream of the compressor a hydrogen buffer tank 40 is provided which temporarily stores hydrogen during the compression phase of the compressor 10a. Once a compression phase of the compressor 10a is completed the hydrogen stored in the buffer tank 40 is led to the compressor 10a.

[0054] The hydrogen storage tanks 10b, 10c are used as constant pressure tanks. The compressed hydrogen is directed through check valves 14, 15 into the hydrogen sections 12b, 12c of the constant pressure tanks 10b, 10c for storage.

[0055] The pistons 11b, 11c of the constant storage tanks 10b, 10c are also actuated by the hydraulic drive 16. When hydrogen gas is added to the constant storage tanks 10b, 10c or withdrawn from the constant storage tanks 10b, 10c the piston 11b, 11c is moved accordingly such that the pressure in the hydrogen section 12b, 12c remains the same. Thus, the pressure in the hydrogen section 12b, 12c can be kept constant during filling of the constant pressure tanks 10b, 10c as well as during the refuelling process when hydrogen is withdrawn from the constant pressure tanks 10b, 10c.

[0056] The oxygen produced in the electrolyzer 1 is passed through a back pressure regulator 17, a catalyst 18 and an air cooler 19 into an expander 30. The expanded oxygen is finally vented in the atmosphere. During expansion of the oxygen in the expander 30 cold is produced. This cold is used to cool the hydrogen by indirect heat exchange before the hydrogen is compressed in the compressor 10a. For cooling the hydrogen, the cold oxygen is passed through a heat exchanger 21 arranged in the condenser 20. Any water which condenses out of the hydrogen is collected and directed via a condensate line 22 back to the water reservoir 2.

[0057] For refuelling the tank of a hydrogen-consuming vehicle or device, such as a vehicle tank, a valve 23 is opened and the piston 11b, 11c in the constant pressure tanks 10b, 10c is propelled by the hydraulic drive 16. Thereby, hydrogen gas is pushed out of the hydrogen section 12b, 12c of the constant pressure tank 10b, 10c and directed to a hydrogen dispensing unit formed by a dispensing nozzle 50 to refuel the vehicle.