DE102012023329A1 - Method for performing a pressure and leak test - Google Patents

Abstract

The invention relates to a method for performing a pressure and tightness test before refueling a storage container (5) with a pressurized gaseous medium, in particular hydrogen, in which a gas buffer store (1) in which the medium to be used for refueling is stored , is connected via a first valve (28) to a pipe section (29) delimiting a pipe volume, which is connected to the storage tank (5) via a second valve (31) and a subsequent tank feed pipe (34) first (28) and closed second valve (31) the pipeline volume is pressurized to a predefined initial pressure with medium or hydrogen from the gas buffer store (1), then the first valve (28) is closed and the second valve (31) is opened, so that only medium or hydrogen located in the pipeline volume presses a tank valve (53) of the storage container (5) and into the Storage tank (5) flows.

Description

The invention relates to a method for carrying out a pressure and leak test before refueling a storage container.

Vehicles that use a gaseous medium such as fuel. B. refueling, require specially trained gas stations that conduct the under relatively high pressure hydrogen (eg., 700 bar) in the vehicle tank or storage tank. Typically, such a gas station has a storage of liquid hydrogen or is connected directly to a hydrogen pipeline or other equipment that may be a hydrogen storage. Since the hydrogen is to be present for refueling in the gaseous phase, such a gas station usually has gas storage tanks, which feed from the aforementioned (liquid hydrogen) storage. Preferably, gas storage tanks are provided which hold gaseous hydrogen in so-called banks at different pressures; For example, a gas buffer may have a high, medium, and low pressure bank.

In order to ensure the safety (risk of explosion) for the environment when refueling storage tanks (eg vehicle tanks) with hydrogen and to set a standard for the refueling process, a consortium consisting of, inter alia, several vehicle manufacturers agreed on the Standard SAE J2601 , Among other things, the standard specifies safety-relevant limits and performance requirements for the refueling process. SAE J2601 sees z. Example, that hydrogen-powered vehicles should be refueled within 3 minutes to 700 bar, without causing the temperature of the storage tank (tanks) of the vehicle above a temperature of 85 ° C increases.

Furthermore, he sees Standard SAE J2601 that before filling the storage tank, a pressure and tightness test is performed; among other things, to ensure that the fuel station tank inlet has been correctly connected to the vehicle's storage tank.

In the said pressure test, the pressure in the storage tank of the vehicle is determined. This is done via a short surge from the gas station to open the storage tank of the vehicle, which is secured by a tank valve (usually a check valve). Then a settling time of 5 s to 20 s can be inserted to compensate for thermal changes due to the pressure surge. This phase can also be omitted (tolerable pressure drop is increased - accuracy of the leak test decreases). Subsequently, for the tightness test, the pressure which now settles in the tank supply line, which is equal to the pressure in the storage container of the vehicle, is measured at the filling station for a certain time (waiting period about 5 s to 20 s) to ensure that there is no appreciable pressure drop takes place, which would indicate a problem, such as a leak in the tank supply line or in connection with the storage container of the vehicle.

The pressure surge for the pressure and tightness test is usually carried out directly from the high pressure bank of the gas storage tank, so that downstream elements in the pipes or the tank inlet, such. Pressure transmitters, thermometers, flowmeters, valves and ramp regulators are exposed to the full pressure surge (eg 800 bar to 850 bar).

Furthermore, in this type of pressure surge, carried out directly by the high-pressure bank of the gas buffer accumulator, at the start (after said waiting period) of the actual refueling operation, there is often a further pressure peak in the downstream elements, which is due to a residual volume under pressure in parts of the pipeline. Such load changes in the pipeline and tank feed contribute to the faster wear of the downstream elements and thus to a shortening of the life of these components.

Proceeding from this, the present invention is based on the problem to provide a method of the type mentioned, in which the said loads are reduced.

This problem is solved by a method having the features of claim 1.

Thereafter, in a method according to the invention for carrying out a pressure and leak test prior to refueling a storage container with pressurized gaseous hydrogen, in which a gas storage tank, in which the hydrogen to be used for refueling is stored, via a first valve with a limiting a pipe volume Pipe section is connected, which is connected via a second valve and a subsequent tank supply line to the storage container, before the Refueling with the first opened and closed second valve, the pipe volume to a predefined initial pressure with hydrogen from the gas storage tank depressed, then closed the first valve and the second valve, so that only in the pipe volume hydrogen applied to a tank valve of the storage tank, if necessary, opens and flows into the storage tank. The said pipe section is at least partially surrounded by a heat exchanger or a heat sink of a heat exchanger. The heat sink is preferably made of a metal, in particular of aluminum. The heat exchanger is therefore also known as "aluminum cold fill".

Instead of hydrogen, the inventive method can also be used for refueling a storage container with another gaseous, pressurized medium. In the following, the method will be described by way of example with reference to hydrogen.

Said pipe volume is preferably dimensioned so that in the section to be tested downstream of said pipe section, a predefined pressure value is required, which is required for the pressure and / or leak test, ie, in particular allows opening of the tank valve, unless the storage tank is fully fueled. This pressure value is at refueling to 700 bar at z. B. 700 bar and z. B. in a set of rules such. B. SAE 2601 be set. If, in particular, a pressure of 700 bar is measured in a filling station of the gas station, the refueling is not started in particular. The pipe volume is especially dimensioned so that this pressure is reached. Otherwise, the surplus hydrogen is directed into the vehicle during the test surge, so that a pressure equalization takes place. If refueling to another pressure value is carried out, the pressure required to carry out the pressure test is adjusted accordingly.

The solution according to the invention advantageously avoids the otherwise occurring initial pressure peak.

The said storage container is in particular a (fuel) tank of a vehicle operated with hydrogen. Furthermore, the first and the second valve is preferably designed as a pneumatic valve.

Preferably, the second valve is closed again after that opening of the tank valve. This is preferably done as directly as possible, since closing the second valve contributes to avoiding a pressure peak in the tank supply line. This can be detected electronically by a mass flow in the dispenser of the hydrogen filling station or by a pressure rise in the dispenser.

Subsequently, a settling time of 5 s to 25 s can be inserted. This serves to compensate for thermal shocks created during the pressure surge. This step can also be skipped - the tolerable pressure fluctuation is then higher.

According to a variant of the method according to the invention is then closed to a dense tank supply line when the measured pressure over a predefined period of time in the range of 5 s to 25 s is constant within certain fluctuations, said constant pressure value is assumed as prevailing in the storage tank pressure. The tolerable fluctuation range depends on the installed dispenser equipment (volume) as well as the implementation of a calming phase (soothing time). Guide values for this are approx. 1 bar to 15 bar. In the event that the tank supply line (including a connection to the storage tank) should be leaking, the measured pressure in the said time period would drop noticeably and the refueling process would be interrupted accordingly.

In a further variant of the invention, it is provided that the first valve for refueling the storage container is controlled by means of a ramp regulator when the second valve is open in such a way that the pressure measured downstream of the second valve in the tank supply line starts from that constant pressure value which is used as starting value for the tank Ramp controller is assumed, ramp-shaped (preferably linearly rising) - up to a possible pressure peak by still in the pipeline volume hydrogen increases. The slope of the ramp is specified in the relevant standard (see above) and is chosen in particular as a function of the ambient temperature and the pressure prevailing in the storage container and the pre-cooling temperature of the hydrogen to be refueled. This temperature can z. B. at -20 ° C or -40 °. Temperatures in between, z. B. -30 ° C are also conceivable.

The pressing of the said pipe section to the initial pressure is preferably carried out again after the end of the respective refueling operation, so that a corresponding (limited) pressure surge is available for the next test.

Further details and advantages of the invention will be explained by the following description of an exemplary embodiment with reference to the figures.

Show it:

1 a schematic representation of a hydrogen filling station; and

2 a temporal pressure curve in the tank supply line in a pressure and leak test carried out according to the prior art; and

3 a temporal pressure curve in the tank supply line in a pressure and leak test carried out according to the invention.

1 shows a schematic representation of a hydrogen filling station, with a gas storage tank 1 , the hydrogen at different pressures in three banks (high, medium and low pressure bank) 2 . 3 . 4 for refueling a storage tank 5 of a vehicle 6 holds. In particular, the three banks 2 . 3 . 4 over pipelines 7 from each other via a combination of pneumatic valves 10 . 12 and check valves 8th ; 9 . 11 . 13 . 14 . 15 pressure-decoupled, as well as individually via a compressor or cryopump 16 fillable. Furthermore, the three banks 2 . 3 . 4 one pressure transmitter each 17 . 18 . 19 associated with the pressure in the respective bank 2 . 3 . 4 senses.

Downstream of the banks 2 . 3 . 4 are in particular pneumatic valves 20 . 21 . 22 followed by check valves 23 . 24 . 25 arranged so that each of the three banks 2 . 3 . 4 can be used individually for hydrogen extraction. This can from the gas storage tank 1 Hydrogen are withdrawn at different pressures.

The gas storage tank 1 is also about a valve 26 and a particle filter 27 with a first, in particular pneumatically controllable valve 28 connected. The first valve 28 subsequent pipeline section 29 , in particular has a heat exchanger (eg "aluminum cold fill") 30 on and ends at a second, downstream valve 31 , The heat exchanger 30 in particular, the temperature of the hydrogen is controlled to a predefined temperature, preferably -40 ° C. Furthermore, the pipe section 29 a mass flowmeter 32 and a pressure transmitter 33 on. Downstream of the second, preferably pneumatic valve 31 is located in a second valve 31 with the storage tank 5 connecting tank supply line 34 a check valve 35 , another, downstream of said check valve 35 arranged pressure transmitter 36 besides printing 36a as well as a temperature transmitter 37 , The tank supply line 34 points at one end into the storage tank 5 opens, a particular hand-controlled valve 38 and a tap 39 on. The storage tank to be refueled 5 is with a tank valve 53 (eg check valve) secured.

A chimney pipe 40 , which transfers excess hydrogen into the environment, has valve-secured connections to the pipelines in several places 7 the gas station. A first connection is via two valves 41 . 42 downstream of the compressor 16 intended. Between these valves 41 . 42 is an inlet 43 for another gas such. For example, nitrogen is provided. Furthermore, the gas buffer memory 1 two connections to the chimney pipe 40 wherein the first connection comprises an emergency ventilation device consisting of a safety valve 44 which opens at 850 bar, and wherein the second connection two consecutive valves 45 . 46 with intermediate inlet 47 for another gas, such as nitrogen. The pipe section 29 also has a connection via a safety valve 48 with the chimney pipe 7 downstream of the heat exchanger 30 on. Furthermore, one connects downstream of the check valve 35 provided combination of three valves 49 . 50 . 51 the tank supply line 34 with the chimney pipe 40 , Downstream of this connection is another connection to the chimney pipe 40 and the tank supply line 34 via a valve 52 intended.

2 shows the temporal pressure curve when performing the pressure and tightness test and the beginning of the actual refueling operation according to the prior art according to the Standard SAE J2601 at a gas station on the type of 1 , It is initially between the valves 20 and 31 z. B. an initial pressure of z. B. about 850 bar from the HD-Bank 2 at.

By opening valve 20 and 31 the pressure on the pressure transmitter rises 36 to 800 bar (pressure peak P1 at about 1.5 s). Subsequently, said valves 20 . 31 closed and the pressure is similar to the pressure in the storage tank 5 off when the tank valve 53 is pressed. A waiting period of approx. 5 s after closing the two valves 20 . 31 follows the pressure in the storage tank 5 and the tightness of the connection with the storage container 5 to determine. Subsequently, both valves 20 . 31 opened again and still between the valves 20 and 31 existing hydrogen flows into the storage tank 5 of the vehicle 6 , which leads to a second pressure peak P2 (approximately after 7 s). Although over the valve 28 already at the second opening of the valves 20 and 31 an increasing pressure ramp is driven, this is visible only after the second pressure peak P2 faded away. The following table 1 contains the allocation table of pressure and time values, as in 2 to see: Table 1 time in seconds Pressure in bar 0 1 0.5 1 1 200 1.5 800 2 200 2.5 40 3 40 3.5 39 4 38 4.5 37 5 36 5.5 36 6 36 6.5 36 7 200 7.5 750 8th 600 8.5 200 9 100 9.5 80 10 90 10.5 100 11 110 11.5 120 12 130 12.5 140 13 150 13.5 160 14 170 14.5 180 15 190 15.5 200 16 210 16.5 220 17 230 17.5 240 18 250 18.5 260

3 shows the temporal pressure curve in the implementation of a pressure and leakage test according to the invention and the beginning of the actual refueling operation at a gas station according to 1 , The pipe section 29 between the first and the second valve 28 . 31 is initially at the initial pressure (about 850 bar) with hydrogen from the HD bank 2 depressed. The pipe volume of the pipe section 29 , which is also the heat exchanger 30 Surrounding volume is sized so that downstream of the pipe section 29 , in particular in the section of the tank supply line 34 between the valve 35 and the vehicle or storage container 5 a pressure value of the hydrogen required for the pressure and / or leak test can be achieved.

Then the second valve 31 opened and the pressure rises in a peak shape to about 140 bar (P3 after about 2 s), before a hydrogen flow through the mass flowmeter 32 is detected. Upon detection of the hydrogen flow or an increase in the pressure in a pump of the hydrogen station, the second valve 31 closed and z. B. a waiting period of about 5 seconds after closing the second valve 31 Waited for the pressure in the storage tank 5 and the tightness of the connection with the storage container 5 to determine. Became the tank valve 53 of the storage container 5 namely pressed on the test shock, there is a pressure equalization and the pressure in the storage tank 5 corresponds to that by means of the pressure transmitter 36 measured pressure plateau during the waiting period. If this pressure does not drop significantly within the waiting period, a tight connection to the storage tank may occur 5 getting closed.

Subsequently, according to the invention, the first and the second valve 28 . 31 open, with a ramp regulator the first valve 28 on the measured pressure (plateau value) in the storage tank 5 the still in the pipe section 29 located, pressurized hydrogen in the storage container 5 flows, resulting in a somewhat steeper increase in pressure (cf. 3 at P4) at the pressure transmitter 36 leads (about 7 s to 9 s). Thereafter, the pressure increases as over the first valve 28 and the ramp controller specified approximately linearly. The following Table 2 contains the corresponding time and associated pressure values of 3 that z. B. by means of the pressure transmitter 36 can be measured. Table 2 time in seconds Pressure in bar 0 1 0.5 1 1 140 1.5 50 2 40 2.5 40 3 40 3.5 39 4 38 4.5 37 5 36 5.5 36 6 36 6.5 36 7 36 7.5 36 8th 36 8.5 60 9 80 9.5 80 10 90 10.5 100 11 110 11.5 120 12 130 12.5 140 13 150 13.5 160 14 170 14.5 180 15 190 15.5 200 16 210 16.5 220 17 230 17.5 240 18 250 18.5 260 LIST OF REFERENCE NUMBERS 1 Gas buffer 2 High pressure Bank 3 Medium pressure Bank 4 Low pressure Bank 5 storage container 6 vehicle 7 piping 8th . 9 . 10 . 11 . 13 . 14 . 15 . 23 . 24 . 25 . 35 check valve 12 . 20 . 21 . 22 . 49 Pneumatic valve 16 pump 17 Pressure transmitter high pressure bank 18 Pressure transmitter Medium pressure bank 19 Pressure transmitter low pressure bank 26 . 41 . 42 . 45 . 46 . 50 . 51 . 52 Valve 27 particulate Filter 28 First (pneumatic) valve 29 Pipeline section 30 Heat exchanger 31 Second (pneumatic) valve 32 Mass Flow Meter 33 . 36 pressure transmitters 36a pressure indicator 34 tank supply line 37 temperature transmitter 38 Hand-controlled valve 39 tap 40 fire line 43 . 47 inlet 44 safety valve 48 safety valve 53 Tank valve (eg check valve) P1, P2, P3, P4 peak pressure

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• Standard SAE J2601 [0003]
• Standard SAE J2601 [0004]
• SAE 2601 [0012]
• Standard SAE J2601 [0029]

Claims (8)

Method for carrying out a pressure and leak test before refueling a storage container ( 5 ) with a pressurized, gaseous medium, in particular hydrogen, in which a gas buffer memory ( 1 ) by storing the medium to be refueled via a first valve ( 28 ) with a pipe section delimiting a pipe volume ( 29 ) connected via a second valve ( 31 ) and a subsequent tank supply line ( 34 ) with the storage container ( 5 ), wherein before refueling when the first ( 28 ) and closed second valve ( 31 ) the pipe volume to a predefined initial pressure with the medium from the gas storage tank ( 1 ), then the first valve ( 28 ) and the second valve ( 31 ) is opened, so that only in the pipeline volume medium located a tank valve ( 53 ) of the storage container ( 5 ) and into the storage container ( 5 ) flows. Method according to claim 1, characterized in that the pipeline section ( 29 ) with a heat exchanger ( 30 ), which in particular has a heat sink, in particular made of aluminum, which has that pipe section ( 29 ) at least partially surrounds. A method according to claim 1 or 2, characterized in that the pipe volume is dimensioned such that downstream of the pipe section ( 29 ) reaches a predefined pressure of the medium, which is sufficient in particular for carrying out the pressure and / or leak test, said pressure is preferably 700 bar. Method according to one of the preceding claims, characterized in that downstream of the second valve ( 31 ) in the tank supply line ( 34 ) pressure is measured over a predefined period of time to the pressure in the storage container ( 5 ) prevailing pressure and the tightness of the tank supply line ( 34 ) to investigate. Method according to one of the preceding claims, characterized in that after pressing the tank valve ( 53 ) the second valve ( 31 ) is closed. Method according to one of the preceding claims, characterized in that on a dense tank supply line ( 34 ) is closed when the measured pressure is constant over a predefined period of time, with that constant pressure value as in the storage container ( 5 ) prevailing pressure is assumed. Method according to one of the preceding claims, characterized in that said initial pressure above a nominal refueling pressure of the storage container ( 5 ), wherein the initial pressure is in particular greater than or equal to 800 bar. Method according to claim 6, characterized in that the first valve ( 28 ) for refueling the storage container ( 5 ) with the second valve open ( 31 ) is controlled by means of a ramp regulator so that the downstream of the second valve ( 31 ) measured pressure ramps up from that constant pressure value.

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