DE10018612C1 - System for filling gas tanks - Google Patents

Abstract

The invention relates to a system for filling gas tanks, such as are used, for example, to hold gaseous fuels for internal combustion engines, it being possible to fill them with a wide variety of suitable gases and in particular natural gas. For small capacities, the system according to the invention should preferably be designed flexibly and inexpensively to meet the most varied requirements with regard to short tank times and an optimal filling strategy, and should utilize the gas storage capacity available in each case to a high degree. For this purpose, at least two pressurized or pressurized gas containers are used as gas stores, which are connected via lines of a line system to a tap or a distributor for several taps, and a compressor is additionally arranged in a bypass line of the valve-controlled line system.

Description

The invention relates to a system for filling Gas tanks according to the preamble of claim 1, as for example for the absorption of gaseous Fuels for internal combustion engines be set. It uses at least two pressure or pressurized gas container, as a gas storage device, which has Lei lines of a piping system with a tap or a distributor for several taps they are. The gas tank to be filled can also a conventional portable gas container his.

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

So far, among other things, for filling gas tanks rem also used so-called banking systems. there become two or three pressure or pressure gas containers used in which gas for different Druckbe rich can be saved when filling gas tanks can. This is the case, for example, with a three-bank system a gas storage (L-bank) for the lower pressure range in the gas tank, a gas storage (M-Bank) for the middle pressure area and the third gas storage (H-bank) used for the upper pressure range in the gas tank. There  the flow velocity and consequently also the required filling time of gas tanks, without additional che intermediate compression, from the respective pressure difference between gas storage and gas tank depends, In such banking systems, the procedure is such that Start of the filling process first from the L-Bank, subsequently from the M-Bank and finally from the H-Bank is filled. The corresponding gas feed can be used until pressure equalization between the gas storage tanks and the gas tank. At Two-bank systems are dispensed with an L-bench.

With this system, therefore, because of dependency not all of the pressure drop in the individual Compressed gas for filling held at banks of the gas tank and the degree of utilization is usually around 35%. Another after part is that the gas tank will not open the maximum pressure can be filled if the Gas storage is already partially empty.

This disadvantage of the low degree of utilization can also with a so-called booster, as a redensification ter, with which an additional pressure increase of the in the gas tank flowing gas should not take place be removed satisfactorily. Because the performance of Boosters and thus the time required until Reaching the maximum pressure in the gas tank depends gig of the pressure - and that means the degree of filling of the Gas storage.

A solution that meets both the required tank and Filling times, as well as a maximum filling of the Gas tanks and also at least approximately 100% use of the gas storage  Compressed gas allows, exists in the Ver use dynamic gas storage, as in DE 198 43 669 C1 are described. Here, with an over flow of gas into the gas tank the pressure in the gas tank cher kept constant in that the volume in the Gas storage is reduced accordingly.

Furthermore, DE 196 50 999 C1 describes a method for Filling a mobile gas tank and a dispensing system described in the case of gas from a gas supply line a first compressor system in a gas tank cher and from the gas storage via a gas pump in be given a mobile gas tank to be filled should. Subsequent to this first gas storage a second compressor system and an additional one second gas storage can be arranged to gas from the first gas storage taking into account the gas pressure in this gas storage faster in the mobi len gas tank to be able to promote.

This is the case with all known solutions Problem that users as short a tank as possible times and a maximum filling of the gas tanks different, but from the point of view of plant builders / operators at the same time or alternatively the in the printing or Compressed gas containers maximum amount of gas stored should be used.

The fulfillment of these requirements and the above ge described gas storage systems with which this For requirements to be met lead to high ones Investment costs for the gas storage.

It is therefore an object of the invention, in particular for small capacities a plant for filling gas to provide tanks with the most flexible and be the most diverse requirements at low cost with short refueling times and optimal filling rate gie fulfilled and the available gas storage capacity can be used as well as possible.

According to the invention, this object is achieved with a system solved according to claim 1. Advantageous design Shapes and developments of the invention result with those mentioned in the subordinate claims Characteristics.

The system according to the invention for filling gas tanks  uses at least two pressurized or pressurized gases containers of conventional design, which via lines a piping system with a tap or a Distributors for several taps are connected. Of course, more than two of these can also be used Pressurized or pressurized gas containers are used, whereby it is possible to combine these into two units bundle up.

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

By switching the valves of the Lei accordingly system, with certain options the following will still have to come back, ver various filling regimes can be realized the respective operating conditions and requirements of the operator. The used Pressurized or pressurized gas containers represent gas storage, in which compressed gas with the same or different chem maximum pressure may be included. On the basis to the known two and three-bank systems Filling the gas tank taking into account the momentary pressure drop from one or the other Ren gas storage can be made, the in the Bypass line arranged compressors both, as an intermediate acting as a booster when filling the guest anks cause an increase in pressure, as in Be filling breaks a refill of at least one the two gas storage can realize.

For the implementation of the various filling regimes can the in the different lines of the Switched solenoid valves depending on the pipe system  Open or close as needed. For this you can on or in the line system at the various Lines sensors are used, their signals directly but also via a programmable logic controller Control for actuating the solenoid valves correspond can be switched accordingly. With the sensors can the respective pressure in the lines, but also the current volume flow of the flowing into the gas tank Gases are measured.

In a simple version, a time can also clock-controlled control of the various magnetic circuits tile take place, where then, if necessary, on the Mes solutions can be dispensed with.

Of course there is also the possibility of Pressure in the gas tank and / or the gas storage for the Manipulation of different valves to mes sen and use these measurement signals accordingly.

The compressor arranged in the bypass line is advantageously a hydraulically operated dop pel piston compressor.

Such a compressor can by means of a directional valve can be controlled so that hydraulic fluid changes selectively in the two hydraulic cylinders of the double piston compressor and by appropriate movement of the double piston gas from one of two ares working cylinders displaced in compressed form and in to compress the second working cylinder afterwards gas can flow in.

To prevent unwanted backflow of Gas are in the connecting lines between the  Working cylinders of the compressor and the gas accumulators or to the gas tank check valves.

With the solution according to the invention, this can be done according to the requirements to be worked that the filling time for the gas tank is as short as possible, with correspondingly high flow velocities and Volume flows can be realized just like also the most careful handling of gas gas reserve reserves, if necessary, also below existing filling requirements of other users Rech wear by reducing the pressure drop from the minimum at least two gas storage tanks are optimally used. The This fact can be relatively simple and flexible by arranging the additional compressor in the bypass line can be reached because the minimum two existing gas storage units decoupled, the compression ter but flexible, with the appropriate switching of the Solenoid valves in the pipe system for the various filling functions and filling paths can be set.

At the interface to the user of a tank system nothing changes compared to known systems, i. H. all known systems of automatic dispensers, Petrol pumps and billing systems are used.

In the following, the invention is intended to be explained using tion examples are explained in more detail.

Show:

Fig. 1 shows an example of an Anla ge, in a schematic representation and

Fig. 2 shows the schematic structure of a usable in a system according to the invention Ver poet.

In the schematic structure 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 in various forms via the distributor 15 .

So the filling with closed Magnetventi len 10 and 11 and at the same time switched off compressor 7 , from the gas bank 1 forming the M bank via line 23 and 25 directly, this switching position should be maintained until a certain reduced pressure difference or pressure equalization between gas storage 1 and gas tank to be filled each time has been reached.

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 when switching the output pressure in the gas storage 8 is higher than the current pressure in the gas storage 1 , the exploitable pressure difference between the gas storage 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 to a higher degree of filling can lead.

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 27 . The gas can then be passed 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 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 ge. 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 .

To control the system, sensors can be used for example, pressure sensors, volume flow sensors or  flow meters are also used.

The dashed line 27 with the solenoid valve 11 and the dashed check valve 21 can be omitted if the above-mentioned 3rd cycle can be waived in a lower configuration of the system.

In the line 23 , a check valve 21 and a second check valve 22 are present between the bypass line 2 to prevent undesirable gas flows.

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 Primat, the shortest possible filling times for gas tanks can ensure the highest possible flow rate. In other modes of operation there is the possibility to conserve the gas reserves contained in the gas stores 1 and 8 as far as possible if, for example, filling requirements of other users are to be satisfied briefly subsequently. Basically, it is a matter of making optimal 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 a corresponding control program can be selected so that the filling request is completely covered by the gas storage 8 as an H bank.

With the aid of optimization calculations, however, it can also be determined whether a certain proportion of the required gas is first removed from the gas store 1 as an M bank.

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 cheaper to shorten the filling time to convey gas from the gas storage 8 (H bank) in post-compressed form via the compressor 7 for filling in the gas tank.

In some cases, it can prove to be advantageous in these simulations, prior to adjusting the pressure balance between gas storage 8 and gas tank, to recompress by guiding the gas flow from gas storage 8 through compressor 7 , with the solenoid valves 10 , 11 opened and closed accordingly and 14 , as already described in advance, whereby the higher inlet pressure of the gas led from the gas storage 8 into the compressor 7 has an advantageous effect.

In Fig. 2 is in a position to be used according to the invention compressor 7 , with the elements required for its operation. It is a hydraulically operated double piston compressor, in which the double piston 3 is driven by a hydraulic pump 16 and controlled by means of a directional control valve 6 hydraulic oil ben and is translationally reciprocable.

In the illustration according to FIG. 2, the compressor is shown in the rest position 7. 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 in the line to the gas pressure accumulator (H bank), for example, is opened and gas can be drawn directly via the check valves 19 , 19 'and 20 , 20th 'flow into the gas tank, which could theoretically take place up to the pressure equalization between gas storage 8 and gas tank.

The hydraulic pump 16 is then switched on and the directional control valve 6 switches to the switching position 30 . As a result, hydraulic oil is conveyed via line A to hydraulic cylinder 28 and 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. In the right hydraulic cylinder 28 'hydraulic oil is displaced ver via the line B and reaches via the directional control valve 6 to the hydraulic oil tank to which the hydraulic pump 16 is connected.

It is advantageous that the movement of the double piston 3 is supported by the residual gas pressure in the right cylinder 4 ′, and consequently the compression work required by 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 now moves to the left and the process is now repeated in the opposite direction, the gas contained in the right cylinder 4 'compressed and conveyed through the correspondingly arranged check valve 20 ' into line 18 .

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 storage device 8 or on the gas tank or its tap reaches the desired pressure in the gas tank or in the gas storage device 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 last-used cylinder 4 or 4 ', 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 returns via the directional valve 6 the hydraulic oil tank. As a result of the throttled 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 sucked 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 via appropriate switching amplifiers in the valve plugs, so that low-noise operation of the compressor 7 can be achieved.

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.

Thus, the required volume flow of the hydraulic pump, as long as the pressure on the gas outlet side is still relatively low, can be regulated to a maximum value and the compressor 7 oscillates with a correspondingly higher frequency. To the extent that the pressure on the gas outlet side increases, the delivery rate of the hydraulic pump is reduced to lower values, so that the frequency of the movement of the double piston 3 is continuously reduced.

Since the installed drive power corresponds to the Pressure level always optimally converted into compression work can be set are the acquisition and the Operating costs reduced accordingly.

The main advantages of such a compressor 7 are that the hydraulic drive is relieved by the energy used on the gas side. The drive power is always optimally converted into compression work by the purely hydraulic power control. The compression ter 7 can be built relatively small and therefore requires little space. The control elements used also guarantee low-noise and material-friendly operation and safety is guaranteed by appropriate elements (fine filter, safety valves, pressure switches, temperature and level monitoring).

Other components shown in Fig. 2 are a filter F, a safety valve SV, a manometer Ma, the drive M for the hydraulic pump 16 and an optional oil cooler K, a temperature switch TS, a level switch NS, the pressure line connected to the directional control valve P and a tank line T for the return.

Claims (8)

1. Plant for filling gas tanks with at least two pressure or pressure gas containers, as Gasspei cher, which are connected via lines of a valve-controlled line system with a tap or a distributor for several taps, characterized in that a compressor in a bypass line of the valve-controlled line system ( 7 ) is arranged. 2. Plant according to claim 1, characterized in that in the two gas stores ( 1 ) and ( 8 ) compressed gas with un different maximum pressure is included. 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. Plant according to one of claims 1 to 4, characterized in that on the line system sensors for opening and closing in the lines ( 23 , 24 , 25 , 27 ) connected Ma solenoid valves ( 10 , 11 , 14 ) are connected. 6. Plant according to one of claims 4 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 ) as well as with the tap or the distributor ( 15 ) and the two hydraulic cylinders ( 28 , 28 ') separated by a double piston ( 3 ) from working cylinders ( 4 , 4 ') are connected to a hydraulic pump ( 16 ) and the directional control valve ( 6 ) between hydraulic pump ( 16 ) and the hydraulic cylinders ( 28 , 28 ') is connected. 7. Plant according to claim 6, characterized in that in 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. 8. Plant according to one of claims 5 to 7, characterized in that the solenoid valves ( 10 , 11 , 14 ) are controlled as a function of time, volume flow and / or pressure.