GB2469084A

GB2469084A - Gas cylinder filling system

Info

Publication number: GB2469084A
Application number: GB0905610A
Authority: GB
Inventors: Robert Lee; Graham Smith; George Kynoch Yule; Stewart Sim; Eric Watson
Original assignee: Dominion Technology Gases Ltd
Current assignee: Dominion Technology Gases Ltd
Priority date: 2009-04-01
Filing date: 2009-04-01
Publication date: 2010-10-06
Anticipated expiration: 2029-04-01
Also published as: WO2010112899A1; GB2469084B; GB0905610D0

Abstract

A gas cylinder filling system 1 comprises oxygen, nitrogen and argon gas supply modules 2,3 and 4. The system further includes a helium compressor module 6. Each of the modules are based on a standard size transportation container 7 comprising a frame 8 having at least one detachable side and within which is housed a gas conversion system. The detachable side provides a means for converting the gas supply module between a transportation mode and an operational mode. Each module 2,3,4 includes a tank 9, a module control unit 10 and a power generator 11. The gas conversion system is configured to convert a liquid gas contained within a tank to a pressurised gas supply.

Description

1 Gas Cylinder Filling System 3 The present invention relates to the field of gas cylinders and in particular to filling systems 4 for gas cylinders.

6 Pure gases and gas mixtures are employed within a range of technical fields and for a 7 wide variety of purposes. For example, gas mixtures are frequently employed for welding 8 and cutting; helium/nitrogen and helium/oxygen gas mixtures are employed as breathing 9 gases for underwater divers; while pure argon, helium, hydrogen, nitrogen, oxygen gases and mixtures thereof are employed for a wide variety of scientific and analytical purposes, 11 to name but a few. In practice, the number of permutations and combinations of the 12 various gases are restricted only by the physical and chemical properties of the 13 components and by health and safety issues relevant to their production, as well as the 14 stability and quality of the final mixture.

16 Cylinders are presently employed to facilitate the transportation of these gases. Typically 17 these cylinders are employed individually or within cylinder bundles e.g. as 16, 48 or 64 18 cylinder quads. Their construction materials include aluminium, steel, light alloys, and 19 composite materials, as well as special porous interior materials for acetylene.

2 When a gas is required at a particular location an order is typically placed by a customer 3 with a gas supplier. The required pure gas or gas mixture is then prepared and bottled 4 under high pressure within gas cylinders by the gas supplier, typically at their nearest plant to the required location for the gas. Thereafter, the gas supplier is required to transport 6 the gas cylinders from their plant to the desired location.

8 As will be appreciated by those skilled in the art, the transportation process often involves 9 the movement of large quantities of high pressure gas cylinders over great distances. The transportation process is therefore a significant, time consuming inconvenience to the gas 11 supplier that not only increases the costs involved but is also potentially hazardous, 12 depending on the chemical content of the pure gases and/or the gas mixtures being 13 transported.

If a customer requires a large quantity of gas over a significant period of time for a 16 particular project it is known for a gas supplier to build a bespoke gas plant at the desired 17 location. However, this is an expensive solution requiring a significant level of man power 18 to carry out the in situ welding and testing of the required plant and associated pipe work.

19 As a result, such a solution is not always available and if carried out can result in an abandoned gas plant being left when the particular project has been completed.

22 It is therefore an object of an aspect of the present invention to provide a gas cylinder 23 filling system that obviates or at least mitigates the disadvantages of gas filling systems

24 described in the prior art.

26 Summary of Invention

28 According to a first aspect of the present invention there is provided a gas supply module, 29 the gas supply module comprising a container having at least one detachable side and within which is housed a gas conversion system, wherein the detachable side provides a 31 means for converting the gas supply module between a transportation mode and an 32 operational mode whereby the gas conversion system is configured to convert a liquid gas 33 contained within a tank to a pressurised gas supply.

1 Housing the gas conversion system within the container allows it to be physically protected 2 during periods of transportation. However, when the at least one detachable side is 3 removed the gas conversion system is provided with a suitable environment to allow it to 4 operate.

6 Optionally the gas conversion system comprises a vaporiser at least one section of which 7 is located along the detachable side of the container. Most preferably the vaporiser 8 comprises an ambient air vaporiser. Removal of the at least one detachable side therefore 9 provides the ambient air vaporiser with a sufficient air supply in order to allow it to operate.

11 Optionally the container comprises three detachable sides and the ambient air vaporiser 12 system comprises a section located along each of the three detachable sides. Increasing 13 the number of detachable sides and associated sections of the vaporiser system increases 14 the efficiency of the conversion process.

16 Preferably the sides are detachable from a container frame.

18 It is also preferable for a fourth side of the container to be pivotally mounted to the 19 container frame so as to provide an access point to the container. Alternatively, the container comprises a fourth side that is detachable from the container frame.

22 It is preferable for the tank to be located on top of the container. Such an arrangement 23 provides the contained liquid with a sufficient pressure head for the conversion process.

Optionally the gas conversion system further comprises a pump located between the tank 26 and the vaporiser. The inclusion of the pump provides a means for controlling the 27 pressure of the gas supply. Such embodiments are suitable for the provision of oxygen, 28 nitrogen, carbon dioxide and argon gases.

The gas supply module may further comprise a cut out valve in a suction line and a return 31 line between the pump and the tank. Preferably a driving gas is employed to remotely 32 open and close the cut out valves. This is a safety feature intended to be deployed in the 33 event of a fire where it is important that a liquid oxygen supply can be quickly isolated from 34 theseatofthefire.

1 Alternatively the gas supply system comprises a heat exchanger. Preferably the gas 2 supply system further comprises a compressor the compressor package being located so 3 as to position the heat exchanger between the compressor and the tank. The inclusion of 4 the compressor package provides a means for controlling the pressure of the gas supply.

Such embodiments are suitable for the provision of helium gas.

7 Optionally the container comprises five removable sides.

9 The container may comprise a module control unit. Optionally the module control unit is located on an external surface of the container. The module control unit preferably 11 comprises a pump start button, a pump stop button and a module emergency stop button.

12 The combination of these features provides a means for manual operation of the pump.

14 It is preferable for the gas supply module to further comprise a gas monitor that provides a means of detecting a gas leak. Preferably the gas monitor is an oxygen gas monitor.

17 Optionally, the module control unit may also comprise a gas monitor alarm that is activated 18 when a gas leak is detected by the gas monitor.

The module control unit may also comprise a time indicator that provides a means of 21 indicating the time the pump has been in operation.

23 Optionally the container is fitted with an alarm which is activated when a body enters the 24 container.

26 Preferably the gas supply module further comprises a power generator housed with the 27 container, the power generator providing a dedicated power source for the module.

28 Alternatively, or in addition, the gas supply module further comprises an electrical control 29 panel suitable for receiving an external power source for the module.

31 According to a second aspect of the present invention there is provided a system control 32 module for a gas cylinder filling system wherein the system control module comprises a 33 container within which is housed a fill and analysis unit.

1 Preferably the system control module further comprises a tank. It is preferable for the tank 2 to be located on top of the container. Such an arrangement provides the contained liquid 3 with a sufficient pressure head for the bottling process.

Optionally the system control module further comprises an office space housed within the 6 container. The office space provides an operator with an area to safely operate the gas 7 cylinder filling system.

9 The fill and analysis unit preferably comprises one or more mixture filling modules. The fill and analysis unit may further comprise an analysis module. Preferably the fill and analysis 11 unit also comprises a vacuum system.

13 Preferably the one or more mixture filling modules comprise one or more filling valves 14 suitable for providing fluid communication with a gas supply module.

16 The one or more mixture filling modules may also comprise a supply gas swing hose 17 adapted to selectively connect the one or more filling valves to a cylinder filling system.

19 Optionally the cylinder filling system comprises a quad filling hose. Alternatively the cylinder filling system comprises a multiple point cylinder filling manifold.

22 Optionally the one or more mixture filling modules comprise a temperature gauge that 23 provides a means for measuring the temperature of any cylinder deployed with the filling 24 modules.

26 The analysis module preferably comprises a test cylinder connection point that provides a 27 means for connecting a cylinder to one or more cylinder diagnostics selected from a set of 28 cylinder diagnostics comprising a pressure gauge, a moisture analyser, an oxygen gas 29 analyser, a carbon dioxide gas analyser, and a gas chromatograph.

31 The analysis module may comprise and an instrument calibration apparatus. It is 32 preferable for the analysis module to further comprise a nitrogen purge facility.

34 Preferably the system control module further comprises a power generator housed with the container, the power generator providing a dedicated power source for the module.

1 Alternatively, or in addition, the system control module further comprises an electrical 2 control panel suitable for receiving an external power source for the module. The electrical 3 control panel may provide a means for distributing power to a gas supply module.

According to a third aspect of the present invention there is provided a gas cylinder filling 6 system comprising one or more gas supply modules in accordance with the first aspect of 7 the present invention.

9 A gas cylinder filling system made up of individual modules based on a container provides a system that is both highly mobile and flexible in its deployment. By employing different 11 modules within different systems provides a customer with a bespoke gas cylinder filling 12 system. The container based system also allows the gas cylinder filling system to be 13 easily disassembled and thus removed at the end of a project.

Preferably the one or more gas supply modules supply one or more gases selected from a 16 group of gases comprising oxygen, nitrogen, carbon dioxide, argon and helium.

18 Most preferably the gas cylinder filling system further comprises a system control module 19 in accordance with the second aspect of the present invention. In this way the mixture filling modules provide a means for mixing the gases provided by the one or more gas 21 supply modules to a customer required specification.

23 Optionally the gas cylinder filling system further comprises a power source connected to 24 the electrical control panel of the system control module. The electrical control panel may be configured to distribute power to the one or more gas supply modules.

27 According to a fourth aspect of the present invention there is provided a method of 28 deploying a gas cylinder filling system the method comprising the steps of: 29 -selecting one or more one or more gas supply modules in accordance with the first aspect of the present invention; 31 -transporting the one or more gas supply modules to a required location for the 32 gas cylinder filling system 33 -connecting the one or more gas supply modules together at the required 34 location.

1 Preferably the method of deploying a gas cylinder filling system further comprises the 2 steps of 3 -selecting a system control module in accordance with the second aspect of the 4 present invention; -transporting the system control module to the required location; and 6 -connecting the system control module to the one or more gas supply modules.

8 According to a fifth aspect of the present invention there is provided a gas supply module, 9 the gas supply module comprising a container having at least one detachable side and within which is housed a vaporiser system, at least one section of which is located along 11 the detachable side of the container, wherein the detachable side provides a means for 12 converting the gas supply module between a transportation mode and an operational 13 mode within which the vaporiser system is configured to convert a liquid gas contained 14 within a tank to a pressurised gas supply.

16 Embodiments of the fifth aspect of the invention may comprise the preferred or optional 17 features of the first aspect of the invention or vice versa.

19 According to a sixth aspect of the present invention there is provided a gas supply module, the gas supply module comprising a container having at least one detachable side and 21 within which is housed a heat exchanger wherein the detachable side provides a means 22 for converting the gas supply module between a transportation mode and an operational 23 mode within which the heat exchanger system is configured to convert a liquid gas 24 contained within a tank to a pressurised gas supply.

26 Embodiments of the sixth aspect of the invention may comprise the preferred or optional 27 features of the first aspect of the invention or vice versa.

29 Brief Description of Drawings

31 Aspects and advantages of the present invention will become apparent upon reading the 32 following detailed description of example embodiments and upon reference to the following 33 drawings in which: 1 Figure 1 presents a schematic representation of a mobile gas filling system in accordance 2 with an embodiment of the present invention; 4 Figure 2 presents further detail of an oxygen gas supply module and a nitrogen gas supply module of the mobile gas filling system of Figure 1; 7 Figure 3 presents a process and instrumentation diagram of the oxygen gas supply 8 module incorporated within the mobile gas filling system of Figure 1; Figure 4 presents a process and instrumentation diagram of a supply line between the 11 oxygen gas supply module and the system control module; 13 Figure 5 presents a process and instrumentation diagram of the nitrogen gas supply 14 module incorporated within the mobile gas filling system of Figure 1; 16 Figure 6 presents a process and instrumentation diagram of a supply line between the 17 nitrogen gas supply module and a system control module; 19 Figure 7 presents further detail of a helium compressor module and the system control module of the mobile gas filling system of Figure 1; 22 Figure 8 presents a process and instrumentation diagram of the helium compressor 23 module incorporated within the mobile gas filling system of Figure 1; Figure 9 presents a process and instrumentation diagram of a mixture filling module of the 26 system control module; 28 Figure 10 presents a process and instrumentation diagram of an analysis module of the 29 system control module; and 31 Figure 11 presents a process and instrumentation diagram of a vacuum system housed 32 within the system control module.

34 In the description which follows, like parts are marked throughout the specification and drawings with the same reference numerals. The drawings are not necessarily to scale 1 and the proportions of certain parts have been exaggerated to better illustrate details and 2 features of embodiments of the invention.

4 Detailed Description

6 In order to provide understanding of the various aspects of the present invention an 7 exemplary gas cylinder filling system 1 designed to fill various gas mixtures will now be 8 described with reference to Figure 1.

From Figure 1, the gas cylinder filling system 1 can be seen to comprise three gas supply 11 modules, namely an oxygen gas supply module 2, a nitrogen gas supply module 3, and an 12 argon gas supply module 4. The gas cylinder filling system 1 further comprises a helium 13 compressor module 5 for use with a cryogenic helium tanker (not shown) and a system 14 control module 6.

16 Each of the modules 2, 3, 4, 5 and 6 of the mobile gas filling system 1 are based on a 17 standard twenty foot container 7 that is suitable and certified for international transport and 18 stacking and so provide a relatively simple and secure means for transporting each of 19 these modules 2, 3, 4, 5 and 6. Significantly, however, is the fact that the sides of the containers 7 have been adapted so as to allow them to be removed, or retracted, from a 21 structural frame 8 of the container 7, as described in further detail below.

23 Oxygen Gas Supply Module Further detail of the oxygen gas supply module 2 is now provided with reference to the 26 schematic representation of Figure 2 and the process and instrumentation diagrams of 27 Figure 3 and Figure 4. In particular, Figure 3 presents a process and instrumentation 28 diagram of the oxygen gas supply module 2 while Figure 4 presents a process and 29 instrumentation diagram of a supply line between the oxygen gas supply module 2 and the system control module 6.

32 The oxygen gas supply module 2 comprises a twenty foot, ISO tank 9 containing liquid 33 oxygen and a module control unit 10 both of which are mounted on top of the container 7.

34 A Wessington ISO-Vac 5500 horizontal cryogenic vacuumed ISO tank is a suitable vessel to be employed as the oxygen gas ISO tank 9. These ISO tanks have a capacity of 1 20,566 litres, an empty weight of 9000kg and a maximum gross weight of 36,000kg. They 2 are specifically designed to transport liquid gas by road, rail and sea, and satisfy the ADR, 3 RID, IMDG, CSC and DOT regulations relating to the carriage of dangerous goods. They 4 are self-pressuring tanks, which employ the pressure of the contained liquid to allow this liquid to be decanted at high flow rates without the need for the employment of an external 6 pump.

8 Housed within the container 7 is a power generator 11 (a 100 KVA unit being one such 9 suitable power generator) is employed to provide a 400V AC 3ph 50Hz power supply to drive a single speed pump 12 (a Krytem TLC36.6/420 22kW being one such suitable 11 pump). A bespoke ambient air vaporiser 13 is also housed within the container 7, further 12 details of which are provided below. Cryogenically insulated hoses provide the required 13 suction 14 and return 15 lines between the pump 12 and the liquid oxygen ISO tank 9.

14 Both the suction 14 and return 15 lines are equipped with automatic cut out valves 16a and 16b, thermal relief valves 17a and 17b and a purge valve 18.

17 A nitrogen supply 19 is provided as a driving gas to remotely open and close the two 18 emergency shut-off valves 16a and 16b. This is a safety feature intended to be deployed 19 in the event of a fire where it is important that the liquid oxygen supply can be quickly isolated from the seat of the fire i.e. the pump 12 or the power generator 11.

22 The pump 12 also incorporates a number of components to protect it from various 23 situations, namely: 24 1) a high discharge pressure switch 20 is employed to stop the pump 12 in the event of a high discharge pressure. This trip is designed to prevent over pressurisation 26 of all of the pipe work system (including the pump) without lifting the primary safety 27 device, namely pressure relief valve 21 whose activation results in the venting of 28 high pressure gas; 29 2) a low temperature switch 22 is employed to stop the pump 12 when the temperature exit of the vaporiser drops below -20°C. This trip is designed to 31 prevent low temperatures damaging pipes, valves, fittings and cylinders not 32 designed to withstand such low temperatures. The trip is also an indication that the 33 vaporiser 13 has become overloaded and needs de-frosting; 34 3) a high temperature switch 23 is employed to stop the pump 12 and a trim heater (if fitted) when the temperature exit of the vaporiser rises above 60°C. This trip is 1 designed to prevent high temperatures damaging pipes, valves, fittings and 2 cylinders not designed to withstand such high temperatures. The trip is also an 3 indication that the trim heater (if fitted) is not working correctly; 4 4) high temperature switches 24 and 25 are employed to stop the pump 12 when the temperature on the pump return 15 and suction lines 14, respectively, is high.

6 These trips are designed to prevent the pump 12 running dry (no liquid) and 7 causing wear to parts designed to run at low temperatures; 8 5) a low temperature switch 26 is employed to stop the pump 12 when the 9 temperature at a stuffing box is low. This trip is designed to prevent cold damage to the pump warm end parts; and 11 6) A motor overload switch 27 activates when the pump 12 is overloaded.

13 The module control unit 10 comprises a pump start button 28, a pump stop button 29 and 14 a module emergency stop button 30 the combination of which provide a means for manual operation of the pump 12. In this mode the pump 12 is started via the pump start button 16 28 and will continue to run until either the pump stop button 29 is pressed or until the high 17 pressure switch 20 trip switch point is achieved.

19 The module control unit 10 may also provide an indication of the time the pump 12 has been in operation, an indication of the functionality of an oxygen monitor (high/Low) and a 21 visual or audible entry alarm warning activated by a monitor located within the container 7.

22 As each of the above described trip situations requires a manual reset by an operator 23 before the pump 12 can restart the module control unit 10 may be also employed to 24 provide an indication to this effect.

26 Further optional features (not shown) that may be incorporated into the module control unit 27 10 include a mains power switch, a tank valves open button, a tank valves closed button, a 28 control supply on lamp, an interlocks OK lamp, a tank valves open lamp, a pump running 29 lamp, a pump heater on lamp, a motor fault lamp, a pump suction high temperature lamp, a pump discharge high temperature lamp, a vaporiser outlet low temperature lamp, a seal 31 packing low temperature lamp, a vaporiser outlet high pressure lamp, a pump suction 32 temperature indicator, a pump discharge temperature indicator, a vaporiser exit 33 temperature indicator and a pump seal temperature indicator.

1 As well as the above described manual operation of the module control unit 10, this unit 2 may also be remotely controlled from the system control module 6, as described in further 3 detail below.

In the supply line between the vaporiser 13 and the system control module 6 are located 6 the following safety features for the oxygen gas supply module 2, namely a pressure 7 contact gauge 31 employed as a line pressure indicator and a controlled pump stop, over 8 pressure protection valves (to external) 32, line vent valves 33, and a supply line isolation 9 valve 34.

11 The above arrangement allows the oxygen pump system to be fully isolated and 12 depressurised at any time.

14 An important operational design feature of the oxygen gas supply module 2 is the fact that the oxygen ISO tank 9 is located on top of the container 7. This arrangement provides the 16 pump 12 with a sufficient head of pressure to operate such that the oxygen gas supply 17 module 2 is capable of providing and maintain an oxygen gas supply at a suitable line 18 pressure to the system control module 6, as presented schematically within the process 19 and instrumentation diagram of Figure 4. The design pressure of the presently described oxygen supply system is 420 BarG.

22 Important to the efficiency of the oxygen gas supply to the system control module 6 is the 23 arrangement of the ambient air vaporiser 13 within the container 7. As can be seen from 24 Figures 1 and 2, the ambient air vaporiser 13 is built into three sides of the container 7 and is the primary means of vaporising the oxygen liquid gas as it exits the pump 12. The 26 vaporiser 13 comprises multiple arrays of finned tubes arranged to provide conversion 27 rates of up to 8 litres per minute at air operating temperatures between -10°C and 50°C, 28 with the greatest efficiently being provided at an ambient air temperature of 15°C. When 29 deployed for use the three corresponding sides of the container 7 are removed from the frame thus exposing a large surface area of the ambient air vaporiser 13 to the 31 surrounding air. This allows the ambient air vaporiser 13 to operate in an efficient manner 32 and so avoids the normal requirement to provide a separate, stand alone vaporiser unit. A 33 stand alone vaporiser would need to be piped up and separately mounted from the oxygen 34 gas supply module 2 and so the removal of this requirement greatly increases the mobility ofthemodule2.

2 The side 35 of the container not comprising a section of the ambient air vaporiser 13 is 3 arranged to be retractable. As a result, the retractable side 35 provides an easy access 4 point for an operator to the inside of the container 7. Thus, by isolating and depressurising the pump system the operator can then access the inside of the container 7 via the 6 retractable side 35 so as to carry out any required maintenance.

8 Nitrogen Gas Supply Module Details of the nitrogen gas supply module 3 are provided within the schematic 11 representation of Figure 2 and the process and instrumentation diagrams of Figure 5 and 12 6. In particular, Figure 5 presents a process and instrumentation diagram of the nitrogen 13 gas supply module 3 while Figure 6 presents a process and instrumentation diagram of the 14 supply line between the nitrogen gas supply module 3 and the system control module 6.

16 As can be seen the nitrogen gas supply module 3 comprises many components in 17 common with the previously described oxygen gas supply module 2, namely a twenty foot, 18 liquid ISO tank 9, now containing liquid nitrogen, and a module control unit 10 both of 19 which are again mounted on top of the container 7. A Wessington ISO-Vac 5500 horizontal cryogenic vacuumed ISO tank is again a suitable vessel to be employed as the 21 nitrogen gas ISO tanks 9.

23 Housed within the container 7 is again a power generator 11 (a 100 KVA unit being one 24 such suitable power generator) employed to provide a 400V AC 3ph 50Hz power supply to drive a pump 12. An ambient air vaporiser 13 is also housed within the container 7.

26 Cryogenically insulated hoses again provide the required suction 14 and return 15 lines 27 between the pump 12 and the liquid nitrogen ISO tank 9. Both the suction 14 and return 28 15 lines are equipped with thermal relief valves 17a and 17b and a purge valve 18.

The pump 12 also incorporates the above described safety components, namely: 31 1) a high discharge pressure switch 20 employed to stop the pump 12 in the event of 32 a high discharge pressure; 33 2) a low temperature switch 22 employed to stop the pump 12 when the temperature 34 exit of the vaporiser drops below -20°C; 1 3) a high temperature switch 23 employed to stop the pump 12 and a trim heater (if 2 fitted) when the temperature exit of the vaporiser rises above 60°C; 3 4) high temperature switches 24 and 25 employed to stop the pump 12 when the 4 temperature on the pump discharge and suction, respectively, is high; 5) a low temperature switch 26 employed to stop the pump 12 when the temperature 6 at a stuffing box is low, typically set to activate at-i 200; and 7 6) a motor overload switch 27 that activates when the pump 12 is overloaded.

9 The module control unit comprises a pump start button 28, a pump stop button 29 and a module emergency stop button 30 that again provide a means for manual operation of the 11 pump 12. In this mode the pump 12 is started via the pump start button 28 and will 12 continue to run until either the pump stop button 29 is pressed or until the high pressure 13 switch 20 trip switch point is achieved.

The module control unit 10 may also provide an indication of the time the pump 12 has 16 been in operation, an indication of the functionality of an oxygen and a nitrogen monitor 17 (high/Low) and a visual or audible entry alarm warning activated by a monitor located 18 within the container 7. As each of the above described trip situations requires a manual 19 reset by an operator before the pump 12 can restart the module control unit 10 may also be employed to provide an indication to this effect.

22 Further optional features (not shown) that may be incorporated into the module control unit 23 10 include a mains power switch, a tank valves open button, a tank valves closed button, a 24 control supply on lamp, an interlocks OK lamp, a tank valves open lamp, a pump running lamp, a pump heater on lamp, a motor fault lamp, a pump suction high temperature lamp, 26 a pump discharge high temperature lamp, a vaporiser outlet low temperature lamp, a seal 27 packing low temperature lamp, a vaporiser outlet high pressure lamp, a pump suction 28 temperature indicator, a pump discharge temperature indicator, a vaporiser exit 29 temperature indicator and a pump seal temperature indicator.

31 As well as the above described manual operation of the module control unit 10, this unit 32 may also be remotely controlled from the system control module 6, as described in further 33 detail below.

1 In the supply line between the vaporiser 13 and the system control module 6 are located 2 the following safety features for the nitrogen gas supply module 3, namely a pressure 3 contact gauge 31 employed as a line pressure indicator and a controlled pump stop, over 4 pressure protection valves (to external) 32, line vent valves 33, and a supply line isolation valve 34.

7 The above arrangement allows the nitrogen pump system to be fully isolated and 8 depressurised at any time.

The operation of the nitrogen gas supply module 3 is similar to that previously described 11 with respect to the oxygen gas supply module 2. The nitrogen ISO tank 9 on top of the 12 container 7 provides the pump 12 with a sufficient head of pressure to operate such that a 13 nitrogen gas supply can be provided to the system control module 6, as presented 14 schematically within the process and instrumentation diagram of Figure 6. The design pressure of the presently described nitrogen supply system is again 420 BarG.

17 Important to the efficiency of the nitrogen gas supply to the system control module 6 is the 18 arrangement of the ambient air vaporiser 13 within the container 7 which is again built into 19 three sides of the container 7. The remaining side 35 of the container 7 is retractable so as to provide access to the components of the module 3 housed within the container 7.

22 A point to note about the process and instrumentation diagram of Figure 6 is the presence 23 of a dedicated nitrogen filling point 36. The dedicated nitrogen filling point 36 is provided 24 because nitrogen in an unmixed state is a gas frequently required by customers.

Therefore, it is useful to have a source for bottling nitrogen gas that is independent of the 26 system control module 6.

28 A further point to note is that, unlike the oxygen gas supply module 2, emergency valves 29 with a dedicated nitrogen supply are riot required within this module 3 since there is no need to isolate nitrogen from any fire within the module 3.

32 Argon Gas Supply Module 34 The third gas supply module 4 is employed to provide a source of argon gas to the system control module 6. To all intensive purposes this module 4 is identical to that of the 1 previously described nitrogen gas supply module 3 except for the fact that the liquid 2 contained within the ISO tank 9 is argon, and there is no requirement for a dedicated gas 3 filling point 36.

In an alternative embodiment, the third gas supply module 4 is employed to provide a 6 source of carbon dioxide gas to the system control module 6.

8 Helium Compressor Module Details of the helium compressor module 5 will now be described with reference to Figures 11 7 and 8. In particular, Figure 7 presents a schematic representation of the helium 12 compressor module 5 while Figure 8 presents a process and instrumentation diagram of 13 the helium compressor module 5.

As can be seen the structure of the helium compressor module 5 differs significantly from 16 the previously describe gas modules. The main reason for this is the chemical 17 composition of helium which results in it being significantly colder (at the same volume and 18 pressure) than any of oxygen, nitrogen, argon or carbon dioxide when provided as a 19 cryogenically cooled liquid.

21 The module 5 is however again based on a container 7 this time comprising five 22 removable sides. However, unlike the previously described modules the helium 23 compressor module 5 does not comprise an ISO tank 9 located on top of the container 7.

24 Instead a helium tanker (not shown) is required to be connected to a compressor package 37 that is located within the helium compressor module 5. The compressor package 37 is 26 designed to convert the helium liquid within the tanker to a maximum of 320 bar gauge of 27 helium gas at 176 m3/hr to the system control module 6.

29 In order to achieve this result, and with reference to Figure 8, the compressor package 37 comprises an internal coil heat exchanger 38, that employs a heating element 39 to heat 31 the helium liquid so as to convert it to a gaseous state, and a compressor 40 which 32 provides a means for controlling the pressure output of the helium gas. The required 33 power for these components is provided by a power supply 41. To assist in this 34 conversion process the compressor package 37 further comprises a helium gas receiver 42 located between the heat exchanger 38 and the compressor 40.

2 In the presently described embodiment the heat exchanger 38 is a Krytem water bath heat 3 exchanger with a recirculation pump and is capable of converting 200 liquid Nm3 per hour, 4 the compressor 40 is a CompAi437.1.He helium compressor while the power supply 41 is a 75 kw rating (absorbed 55 kw) Star delta with fixed soft start, 400v 3 phase supply 6 that is capable of operating at either 50 or 60 hertz and is water cooled (closed system) a 7 with trim cooler 43 based on a maximum ambient temperature of 55°C.

9 The compressor 40 may comprise the following features (not explicitly shown), namely: a let-down package, a low pressure trip, a high pressure trip, a low temperature inlet trip, a 11 filtration package, a high pressure relief valve set at 10% above maximum working 12 pressure of the module 6, and a 0-400 BarG pressure contact gauge adapted to trip the 13 compressor package 37 during a period of rising pressure.

A compressor control unit (not shown) is also provided on the compressor package 37.

16 This control unit comprises a compressor start button, a compressor stop button and a 17 module emergency stop button that provide a means for manual operation of the 18 compressor package 37. In this mode the compressor package 37 is started via the 19 compressor start button and will continue to run until either the compressor stop button is pressed or until the high pressure switch trip switch point is achieved.

22 The compressor control unit may also provide an indication of the time compressor 23 package 37 has been in operation. Further optional features that may be incorporated into 24 the compressor control unit include a mains power switch, a control supply on lamp, an interlocks OK lamp, a compressor running lamp, a compressor cooler on lamp, a motor 26 fault lamp, a compressor suction high pressure lamp, a compressor suction low pressure 27 lamp, a compressor discharge high pressure lamp and a compressor discharge high 28 temperature lamp.

As well as the above described manual operation of the compressor package 37, this unit 31 may also be remotely controlled from the system control module 6, as described in further 32 detail below.

34 From Figure 8, the supply line of the helium compressor module 5 can be seen to comprise a check and fill valve line 44,a clw vent 45 (to external), a pressure gauge 46, a 1 quad fill hose with parking position (to external) 47 that allows for the filling of a manifold 2 cylinder package with helium gas, a pressure relief valve 48 for lower pressure helium gas 3 fills, an on line cylinder buffer 49 to allow for minor component decanting, and supply line 4 isolation valves 50.

6 When the module 5 is to be deployed in an operational mode it is advantageous for all of 7 the removable sides of the container 7 to be removed. In the first instance this is required 8 to assist in the process of connecting the helium tanker (not shown) to the heat exchanger 9 38. If the remaining sides of the container 7 are not also removed then the compressor package 37 would effectively be housed within an open sided cavity which would act to 11 amplify the noise produced during the operation of the compressor package 37. Removal 12 of the remaining sides of the container 7 thus reduces this amplifying effect and so 13 improves the operating safety of the helium compressor moduleS. This effect can be 14 further reduced by mounting the compressor package 37 on anti-vibration mounts 51.

16 System Control Module 17 The final module that makes up the mobile gas filling system 1 is the system control 18 module 6 details of which can be seen in Figure 7. The system control module 6 19 comprises three distinct components, namely an office space 52 and a fill and analysis unit 53, both located within the container 7, and a ten foot, ISO tank 54 located on top of the 21 container 7. Also housed within the container 7 is a power generator 11 (a 100 KVA unit 22 being one such suitable power generator) that is employed to provide a 400V AC 3ph 23 50Hz power supply for the system control module 6.

The office space 52 takes up approximately one half of the volume of the container 7 and 26 provides an operator with a safe working space within the mobile gas filling system 1. This 27 office space 52 may be equipped with an air conditioning unit.

29 The second half of the container 7 is employed to house the fill and analysis unit 53 which comprises a mixture filling module 55, an analysis module 56 and a vacuum system 57 for 31 the mobile gas filling system 1 Further details of each of these components are provided 32 below.

1 The ISO tank 54 on top of the container 7 contains carbon dioxide in a liquid state. It 2 therefore provides a pressurised source of carbon dioxide gas for the mixture filling 3 module 55 as described in further detail below.

With reference to the process and instrumentation diagram of Figure 9 the mixture filling 6 module 55 provides a means for filling one, or multiple gas cylinders with various gases or 7 gas mixtures. It can be seen in fact to comprise two separate filling modules, 55a and 8 55b, both of which are shown connected to oxygen 58, nitrogen 59 and helium supply lines 9 60. Each filling module, 55a and 55b, comprises five check and fill valves, one for each of the oxygen gas supply 61a and 61b, the nitrogen gas supply 62a and 62b the helium gas 11 supply 63a and 63b the argon gas supply 64a and 64b and the carbon dioxide gas supply 12 65a and 65b. Each check and fill valve 61a, 62a, 63a, 64a, 65a and 61b, 62b, 63b, 64b, 13 65b has an associated pressure gauge 46 that provides a means for monitoring the gas 14 pressure at the check and fill valves 61a, 62a, 63a, 64a, 65a and 61b, 62b, 63b, 64b, 65b.

16 The filling modules 55a and 55b also comprise a supply gas swing hose 66 adapted to 17 selectively connect the check and fill valves 61a, 62a, 63a, 64a, 65a and 61b, 62b, 63b, 18 64b, 65b, respectively, to a pair of associated off valved quad filling hoses 67a and 67b.

19 Each pair of off valved quad filling hoses 67a and 67b has an associated pressure gauge 46 and a temperature gauge 68. Filling module 55b can also be seen to comprise a 21 valved fifteen point cylinder filling manifold 69.

23 Each of the filling modules 55a and 55b further comprises a low pressure relief valve 70a 24 and 70b that provide a means for filling a single cylinder with a 200 BarG gas. Line venting valves 33 are located within a VSL external line 71 while vacuum valves 72a and 26 72b provide a means of isolating the filling modules 55a and 55b from the vacuum system 27 57.

29 The final component of the filling modules 55a and 55b is a cylinder wall temperature gauge 73a and 73b that takes the form of a portable hand gun. This provides a means for 31 measuring the temperature of any cylinder deployed with the filling modules 55a and 55b.

33 Figure 10 presents a process and instrumentation diagram of the analysis module 56 of 34 the system control module 6 that provides a means for analysing the gas content of a cylinder. This module 56 comprises a cylinder connection point 74, a pressure gauge 46, 1 a vent & isolation facility 75 and regulation 76 and relief valves 77. Other components of 2 the analysis module 56 include a moisture analyser 78 with a regulated feed and flow 3 metered vents, an oxygen and carbon dioxide gas analyser 79 (a Systech ZR894 with a 4 valved feed being one such suitable analyser), two calibration feeds 80, and a by-pass flow meters 81.

7 In addition to the above components the analysis module 56 further comprises a regulated 8 carrier gas feed 82 to a bench mount unit 83 via a sample hose 84 along with appropriate 9 calibration feeds 85. A carrier gas is used to ensure a constant supply of gas through the instruments thus ensuring they remain dry. As a result the carrier gas is run at all times.

11 The calibration feeds 80 allow a calibration gas to be employed to calibrate the 12 instruments. Typically this process would be carried out on a daily basis. The analysis 13 module 56 may further comprise a gas chromatograph.

A nitrogen purge facility 86 is also provided as a means for purging the analysis module 16 56.

18 A process and instrumentation diagram of the vacuum system 57 is presented in Figure 19 11. As previously discussed, the vacuum system 57 is housed within the container 7 of the system control module 6 and is designed to evacuate residual gas as part of a cylinder 21 fill cycle. The vacuum system 57 comprises a vacuum pump 87 that is connected to the 22 filling modules 55a and 55b. Manual control of the vacuum pump 87 is provided via a 23 vacuum control panel (not shown) located within the office space 52. The vacuum pump 24 87 is preferably air cooled, fully oxygen compatible, and rated for continuous running. A (RIM) (RIM) Leybola uGEVAu sV65 is a vacuum pump suitable for providing this functionality.

27 A vacuum protection valve 88 (V71-10) is located between the vacuum pump 87 and the 28 filling modules 55a and 55b. The vacuum protection valve 88 is arranged to close and 29 isolate the vacuum pump 87 in the event of high suction pressure being detected by the pressure gauge 46.

32 From the office space 52 an operator may remotely operate the oxygen gas supply module 33 2, the nitrogen gas supply module 3, the argon gas supply module 4, the helium 34 compressor module 5 and the other components of the system control module 6 via a computer interface which communicates with the associated control units.

2 The computer interface also provides for an overall emergency stop system that can be 3 employed to shut down the complete mobile gas filling system 1. This complete shut down 4 can be activated by an operator located within office space 52 or via module emergency stop button 30 located on the outside of each of the gas supply modules 2, 3 and 4, and 6 the helium compressor module 5. Upon activation of the emergency stop system the 7 pumps 12 are stopped, the compressor package 37 is stopped, the oxygen pump suction 8 16a and return valves 16b are closed, and notification of the emergency stop is indicated 9 on the module control units 10 and the compressor control unit. The described emergency shutdown situation needs to be manually reset by an operator before the mobile gas filling 11 system 1 can be restarted.

13 Deploying the Gas Filling System Deployment of the gas cylinder filling 1 system is as follows. Once the location for the gas 16 cylinder filling system 1 has been determined then the various modules 2,3,4,5 and 6 are 17 transported to the required destination. The fact that each of the modules 2, 3, 4, 5 and 6 18 is based on a container significantly simplifies this transportation process.

The modules 2, 3, 4, 5 and 6 are then appropriately arranged, configured into their 21 operational mode and then connected up, as appropriate. The gas cylinder filling system 1 22 employs a flexible piping system to connect the various modules and so removes the need 23 for a team of welders to be on site to install and test fixed pipe work, as is required in prior 24 art systems.

26 Once deployed the mixture filling modules and the analysis module allow for the controlled 27 filling and analysis of cylinders with pure gases or gas mixtures, as and when required by 28 a customer.

In order to replenish a oxygen, nitrogen, carbon dioxide or argon gas source all that is 31 required is for the system 1 to be isolated, the appropriate module 2, 3, 4 or 6 to be 32 removed and replaced with a new module comprising a full ISO tank 9. The original 33 module 2, 3, 4, or 6 can then be transported away for refilling. To replenish the helium gas 34 source the helium tanker connected to the helium compressor module 5 has simply to be replaced.

2 In the above described embodiments each of the modules 2, 3, 4, 5 and 6 comprises an 3 independent power source. In an alternative embodiment each module 2, 3, 4, 5 and 6 4 may comprises an electrical control panel (not sown) that is fed from a single 400v 3 phase 50 hertz external power supply. In a further alternative embodiment the system 6 control module 6 may provide a single main power entry and then handle the onward 7 distribution of power to each of the remaining modules 2, 3, 4 and 5.

9 It will be appreciated that the gas sources are not restricted to the provision of oxygen, nitrogen, carbon dioxide, argon or helium gases. Any alternative pure gas or gas mixture 11 could readily be provided within a corresponding gas supply module, as and when 12 required by a customer.

14 In a further alternative embodiment the system control module 6 may comprise a twenty foot, ISO tank 9 containing liquid carbon dioxide or any other suitable liquid gas.

17 The described gas cylinder filling system therefore provides a system that is significantly 18 more flexible than the prior art systems which require the transportation of large numbers 19 of gas cylinders over large distances. Being able to mix the gases in situ means that bespoke gas mixtures are more readily available and there is a reduction in the distances 21 over which potentially hazardous gas mixtures are required to be transported.

23 When compared with the fixed gas plant solutions to the above problems the presently 24 described gas cylinder filling system can again be seen to be more flexible and significantly more mobile. The present solution therefore reduces the expense involved as 26 significantly less man power is required to deploy the system. The mobile nature of 27 described gas cylinder filling system also avoids an abandoned gas plant being left on the 28 completion of a particular project. The gas cylinder filling system can simply be 29 disconnected and transported away.

31 The foregoing description of the invention has been presented for purposes of illustration 32 and description and is not intended to be exhaustive or to limit the invention to the precise 33 form disclosed. The described embodiments were chosen and described in order to best 34 explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilise the invention in various embodiments and with various I modifications as are sufted to the particular use contemplated. Therefore, further 2 modificatIons or Improvements may be Incorporated without departing from the scope of 3 the Invention as defined by the appended claims.