WO2001077574A1

WO2001077574A1 - Installation for filling gas tanks

Info

Publication number: WO2001077574A1
Application number: PCT/DE2001/001330
Authority: WO
Inventors: Hermann-Josef Winter
Original assignee: Winter Hermann Josef
Priority date: 2000-04-09
Filing date: 2001-03-29
Publication date: 2001-10-18
Also published as: DE10018612C1; AU2001256139A1; EP1278985A1

Abstract

The invention relates to an installation for filling gas tanks, such as those used for e.g., holding gaseous fuels for combustion engines, which can be used to fill gas tanks with a very wide range of suitable gases, especially natural gas. The inventive installation should preferably be configured for small capacities, in a versatile and economical manner, be able to satisfy very different requirements in terms of short filling times and optimum filling strategies and make good use of the available gas storage capacity, respectively. To this end, at least two pressure vessels or compressed gas vessels are used as gas storage devices (1;8) and are connected to a delivery point (15) or a distributor for several delivery points by pipes (23;24;25) of a pipe system. A compressor (7) is additionally located in a bypass pipe (2;2) of the valve-controlled pipe system.

Description

System for filling gas tanks

The invention relates to a system for filling gas tanks, such as those used for receiving gaseous fuels for internal combustion engines. It uses at least two pressurized or pressurized gas containers, as gas storage devices, which are connected to a tap or a distributor for several taps via lines of a line system. The gas tank to be filled can also be a conventional portable gas container.

The system according to the invention can be used to fill gas tanks on vehicles powered by natural gas, but also for other gaseous fuels, such as Biogas or hydrogen can be used.

So-called bank systems have been used to fill gas tanks, among other things. Two or three pressurized or pressurized gas containers are used, in which gas can be stored for different pressure ranges when filling gas tanks. For example, a gas tank (L-bank) for the lower pressure area in the gas tank, a gas tank (bank) for the medium pressure area and the third gas tank (H-bank) for the upper pressure area in the gas tank are used in a three-tank system. Since the flow rate and consequently the required filling time of gas tanks, without additional intermediate compression, depends on the respective pressure The difference between the gas storage and the gas tank depends on the bank system, so that at the beginning of the filling process the filling is done first from the L bank, then from the M bank and finally from the H bank. The corresponding gas store can be used until the pressure equalization between the gas stores and the gas tank is reached. An L-bench is not used in two-bank systems.

With this system, because of the dependency on the pressure drop, not all of the compressed gas in the individual banks can be used to fill the gas tank, and the degree of utilization is usually around 35%. Another disadvantage is that the gas tank cannot be filled to the maximum pressure when the gas storage is already partially empty.

This disadvantage of the low degree of utilization cannot be satisfactorily eliminated even with a so-called booster, as a post-compressor, with which an additional pressure increase of the gas flowing into the gas tank is to take place. Because the performance of the booster and thus the time required to reach the maximum pressure in the gas tank depends on the pressure - and that means the filling level of the gas storage.

A solution that both the required tank or filling times, as well as a maximum filling of the

Gas tanks and likewise an at least approximately 100% utilization of the compressed gas contained in gas stores is possible when using dynamic gas stores as described in DE 198 43 669 Cl. Here, in the event of an flow of gas into the gas tank the pressure in the gas storage is kept constant by reducing the volume in the gas storage accordingly.

This is the case with all known solutions

The problem is that users require the shortest possible tank times and a maximum filling of the gas tanks, but from the point of view of the system builder / operator, the gas quantity stored in the pressure or pressure gas tanks should be used to the maximum or at the same time.

The fulfillment of these requirements and the gas storage systems described above, with which these requirements are to be met, lead to high investment costs for the gas stores.

It is therefore an object of the invention to provide a system for filling gas tanks, in particular for small capacities, with which the various requirements regarding short tank times and optimal filling strategy can be flexibly and inexpensively met and the available gas storage capacity can be used as well as possible ,

According to the invention, this object is achieved with a system according to claim 1. Advantageous embodiments and further developments of the invention result from the features mentioned in the subordinate claims.

The system according to the invention for filling gas tanks uses at least two pressurized or pressurized gas containers of a conventional type which are connected to a tap or a line via a line system Distributors for several taps are connected. Of course, more than two such pressure or pressure gas containers can also be used, with the possibility of bundling them into two units.

It is important that a bypass line, in which a compressor is arranged, is connected in the valve-controlled line system.

By appropriate switching of the valves of the line system, it being possible to return to certain possibilities below, a wide variety of filling regimes can be implemented which take into account the respective operating conditions and requirements of the operator. The pressure or pressure gas containers used represent gas storage devices, in which compressed gas with the same or different maximum pressure can be contained. Based on the known two- and three-tank systems, the gas tank can be filled taking into account the current pressure drop from one or the other gas storage, the compressor arranged in the bypass line acting both as an intermediate amplifier and increasing the pressure when filling the gas tank effect how refilling of at least one of the two gas stores can also be carried out during filling pauses.

To implement the various filling regimes, the solenoid valves connected to the various lines in the line system can be opened or closed as required. For this purpose, sensors and their signals can be used on or in the line system on the various lines can also be switched directly via a programmable logic controller for actuating the solenoid valves. With the sensors, the respective pressure in the lines, but also the current volume flow of the gas flowing into the gas tank, can be measured.

In a simple embodiment, the various magnetic valves can also be controlled in a time-controlled manner, in which case the measurements may then be dispensed with.

Of course, there is also the possibility of measuring the pressure in the gas tank and / or the gas stores for the manipulation of a wide variety of valves and of using these measurement signals accordingly.

The compressor arranged in the bypass line is advantageously a hydraulically operated double-piston compressor.

Such a compressor can be controlled by means of a directional control valve, so that hydraulic fluid is pressed alternately into the two hydraulic cylinders of the double-piston compressor and, by corresponding movement of the double piston, gas is displaced in compressed form from one of two working cylinders and subsequently gas flows into the second working cylinder can.

To prevent undesired backflow of gas, check valves are connected in the connecting lines between the working cylinders of the compressor and the gas storage tanks or to the gas tank. With the solution according to the invention, the corresponding requirements can be worked in such a way that the shortest possible filling time for the gas tank, with correspondingly high flow velocities and volume flows, as well as the gentlest possible handling of the gas storage reserves, so that any subsequent filling requirements are also present other users to take into account by making optimal use of the pressure drop from the at least two gas stores. This fact can be achieved relatively simply and flexibly by arranging the additional compressor in the bypass line, since the at least two existing gas storage units are decoupled, but the compressor can be used flexibly for the various filling functions and filling paths if the solenoid valves in the line system are switched accordingly can.

At the interface to the user of a tank system, nothing changes compared to known systems, i.e. all known systems of automatic dispensers, petrol pumps and accounting systems can be used.

The invention will be explained in more detail below on the basis of exemplary embodiments.

Show:

Figure 1: an example of a system according to the invention, in a schematic representation and

FIG. 2: the schematic structure of a compressor which can be used in a system according to the invention. In the schematic construction of a system according to the invention shown in FIG. 1, two gas stores 1 and 8 are connected via lines 23, 24 and 25, which form a valve-controlled line system, to a distributor 15, to which a plurality of tapping points can be connected. The two gas accumulators 1 and 8 can have a different pressure level and consequently can be used in a similar way to a known M bank and H bank.

The gas storage device 1 can be supplied with compressed gas via a compressor (not shown) or a mobile system. The gas reservoir 8 can be filled via the compressor 7 from the gas reservoir 1 or also via the compressor, not shown.

By appropriate switching of the solenoid valves 10, 11 and 14, the filling of at least one gas tank, not shown, can be realized via the manifold 15 in various forms.

Filling can thus be carried out directly from the gas accumulator 1 forming the M bank via the lines 23 and 25 when the solenoid valves 10 and 11 are closed and the compressor 7 is switched off, this switching position should be maintained until a certain reduced pressure difference or pressure equalization between gas storage 1 and the gas tank to be filled has been achieved.

Then the solenoid valve 10 is opened and the filling takes place from the gas bank 8 forming the H bank via the lines 24 and 25, with the solenoid valve 14 open further. Since the output pressure in the gas storage device 8 is higher than the current pressure in the gas storage device 1, the usable pressure difference between the gas storage device 8 and the gas tank to be filled is of course larger again, so that the filling takes place in a correspondingly shorter time and leads to a higher filling level can.

If the pressure in the gas accumulator 8 drops further, the filling speed can be increased and consequently the time required for filling can be reduced by closing the solenoid valve 10 and opening the solenoid valve 11 present in the line 28. The gas can then be fed in a third cycle via the bypass line 2, 2 ′ and the compressor 7 through line 25 to the distributor 15. At the same time, the compressor 7 is switched on and gas can be conveyed to the gas tank at a higher pressure via the distributor 15.

During filling pauses, the gas store 8, as an H bank, can be refilled from the gas store 1 as an M bank. The solenoid valves 11 and 14 are closed. The gas passes from the gas storage device 1 via the line 23, the compressor 7 that is switched on through the opened solenoid valve 10 and the line 24 into the gas storage device 8.

Sensors, for example pressure sensors, volume flow sensors or flow rate meters, can be used to control the system.

The dashed line 28 with the solenoid valve 11 and the dashed check valve 21 can then be omitted if in a lower Expansion stage of the system on the above 3rd cycle can be dispensed with.

A check valve 21 and a second check valve 22 are provided in the line 23 between the bypass line 2 in order to prevent undesired gas flow.

The pressure switch 13 switches the system off when the maximum pressure in the gas tank has been reached.

With the possibilities already described with which the system can be operated, the various requirements of an operator can be taken into account almost optimally. With the primacy of filling gas tanks as short as possible, the highest possible flow rate can be ensured. In other modes of operation, there is the possibility of conserving the gas reserves contained in the gas stores 1 and 8 as far as possible, for example if filling requests from other users are to be satisfied briefly subsequently. Basically, it is a matter of making optimum use of the pressure drop between gas stores 1 and 8, which act as M and H banks.

To minimize the filling times, the control can be programmed or an appropriate control program can be selected so that the filling request is completely covered by the gas storage 8 as an H bank.

With the help of optimization calculations, it can also be determined whether a certain proportion of the required gas is first extracted from the gas storage 1 as Bank is removed.

In the calculations, it depends on the degree of filling of gas storage 1 (M bank) and gas storage 8 (H bank) up to which pressure in the gas tank a filling from the gas storage 1 should take place or can be sensibly carried out, this filling up to for pressure equalization between gas storage 1 and gas tank is possible.

In a further simulation, it can be calculated whether and to what extent it is more favorable to shorten the filling time to convey gas from the gas storage 8 (H bank) in compressed form via the compressor 7 for filling in the gas tank.

In some cases, it may prove to be advantageous in these simulations to recompress by adjusting the gas flow from the gas reservoir 8 via the compressor 7, with the solenoid valves 10, 11 and 14 open and closed accordingly, even before the pressure equalization between the gas reservoir 8 and the gas tank is set , as already described above, to be carried out, the higher inlet pressure of the gas led from the gas reservoir 8 into the compressor 7 having an advantageous effect.

FIG. 2 shows a compressor 7 that can be used in the system according to the invention, with the elements required for its operation. It is a hydraulically operated double-piston compressor, in which the double piston 3 is driven by hydraulic oil, which is pumped by a hydraulic pump 16 and controlled by means of a directional control valve 6, and can be moved back and forth in translation. In the illustration according to FIG. 2, the compressor 7 is shown in the rest position. The low leakage in the directional control valve 6 has reduced the hydraulic pressure in the hydraulic cylinders 28, 28 '.

To start up the compressor - controlled as described above - the valve 29, which is arranged, for example, in the line to the gas pressure accumulator (H bank), is opened and gas can be supplied directly via the check valves 19, 19 'and 20, 20 'flow into the gas tank, which could theoretically take place up to the pressure equalization between gas storage 8 and gas tank.

Then the hydraulic pump 16 is switched on and the directional control valve 6 switches to the switching position 30. As a result, hydraulic oil is conveyed via the line A to the hydraulic cylinder 28 and the double piston 3 moves accordingly to the right. As a result, gas located in the left-hand working cylinder 4 is compressed and, via the check valve 20 through the line 18, depending on the switching position of the solenoid valves, as described above, is either conveyed into the gas reservoir 8 or directly into the gas tank to be filled. At the same time, gas flows via the check valve 19 'into the right working cylinder 4', which is filled accordingly. The check valve 20 'connected via lines to this working cylinder 4' is closed. Hydraulic oil located in the right hydraulic cylinder 28 'is displaced via the line B and reaches the hydraulic oil tank via the directional control valve 6, to which the hydraulic pump 16 is connected.

It is advantageous that the movement of the double piston bens 3 is supported by the residual gas pressure in the right cylinder 4 ', and consequently the compression work required from the hydraulic side is reduced by the energy stored in the compressed gas. When the right-hand end position of the double piston 3 is reached, which in this example can be recognized with a corresponding displacement sensor WS, the directional control valve 6 switches to the switching position 31 and hydraulic oil is accordingly conveyed via line B into the right-hand hydraulic cylinder 28 ', so that the Double piston 3 is now moved to the left and the process is now repeated in the opposite direction, the gas contained in the right working cylinder 4 'being compressed and conveyed into the line 18 by the correspondingly arranged check valve 20'.

With the help of the position sensors WS in the end positions of the double piston 3, the oscillation process of the double piston is maintained until the pressure switch DS or a pressure sensor on the gas reservoir 8 or on the gas tank or its tap reaches the desired pressure in the gas tank or in the gas reservoir 8 reports. The hydraulic system is switched off by switching off the hydraulic pump 16 and de-energizing the directional control valve 6, the double piston 3 again moving into the middle position shown.

Since there is still a correspondingly high gas pressure in the working cylinder 4 or 4 'last used, the double piston 3 moves into an end position and the hydraulic oil still present in the direction of movement is displaced from the corresponding hydraulic cylinder 28 or 28' and re-enters via the directional control valve 6 the hydraulic oil tank. As a result of the throttled In the middle position of the directional control valve 6, this process takes place with a time delay and switching shocks can thereby be prevented. So that the opposite hydraulic cylinder 28 or 28 'remains filled, hydraulic oil is drawn into the hydraulic cylinder 28 or 28' from the hydraulic tank via the suction line NL and the corresponding suction valve NV.

By using a power-controlled hydraulic pump 16, a high volume flow can be achieved at low gas pressure in the gas store 8 or in the gas tank. The noise level can be kept low by choosing appropriate valves.

The directional control valve 6 can be used in a so-called "soft shift" version. As a result, the switching movements of the directional control valve 6 can be delayed and switching shocks and pressure peaks can be effectively avoided. The switching behavior can be optimized by means of corresponding switching amplifiers in the valve plugs, so that the compressor 7 can be operated with low noise.

In the example shown here, a power-controlled hydraulic pump 16 has been used, in which, based on the drive power of the drive motor of the hydraulic pump, the product of volume flow and operating pressure can automatically be kept constant.

The required volume flow of the hydraulic pump can thus be regulated to a maximum value as long as the pressure on the gas outlet side is still relatively low and the compressor 7 oscillates with ω H oo LΠ

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Claims

claims

1. System for filling gas tanks with at least two pressurized or pressurized gas containers, as a gas store, which are connected via lines of a line system to a tap or a distributor for several taps, characterized in that a compressor (7) is arranged in a bypass line of the valve-controlled line system is.

2. Plant according to claim 1, characterized in that in the two gas stores (1) and (8) compressed gas with different maximum pressure is contained.

3. Plant according to claim 1 or 2, characterized in that the compressor (7) is a hydraulically operated double-piston compressor.

4. Plant according to one of claims 1 to 3, characterized in that the compressor (7) is controlled by means of a directional valve (6).

5. Installation according to one of claims 1 to 4, characterized in that sensors for opening and closing in the lines (23, 24, 25, 28) connected solenoid valves (10, 11, 14) are connected to the line system.

6. Plant according to one of claims 1 to 5, characterized in that two working cylinders (4, 4 ') of the compressor (7) via the bypass line (2, 2') with the two gas stores (1) and (8) and with the tap or the distributor (15) and the two hydraulic cylinders (28, 28 ') separated from the working cylinders (4, 4') by the double piston (3) are connected to a hydraulic pump (16) and the directional control valve (6) is connected between the hydraulic pump (16) and the hydraulic cylinders (28, 28 ').

7. Installation according to one of claims 1 to 6, characterized in that in the connecting lines (17, 18) between the working cylinders (4, 4 ') and the gas stores (1) and (8) check valves (19, 19' , 20, 20 ') are switched.

System according to one of claims 1 to 7, characterized in that the solenoid valves (10, 11, 14) are controlled as a function of time, volume flow and / or pressure.