AU2014217851A1

AU2014217851A1 - Pressure vessel with display

Info

Publication number: AU2014217851A1
Application number: AU2014217851A
Authority: AU
Inventors: Derek Ernest HILTON
Original assignee: Linde GmbH
Current assignee: Linde GmbH
Priority date: 2013-02-14
Filing date: 2014-02-13
Publication date: 2015-08-13
Anticipated expiration: 2034-02-13
Also published as: AU2014217851B2; GB201302554D0; WO2014125010A1; EP2956707A1; CA2900148A1

Abstract

A pressure vessel for compressed gas comprising a shut-off valve, a pressure sensor, a temperature sensor, a programmable computing device with an associated display screen, a collar and a guard or retaining ring. The Guard or retaining ring is attached to the pressure vessel to hold the collar in place between the pressure vessel and the guard or retaining ring and the display screen is in the collar. The pressure and temperature sensors are in communication with the interior of the pressure vessel and generate first and second signals which are functions of the pressure and temperature in the vessel. The computing device calculates information concerning the amount of contents in the pressure vessel from first and second signals, and the display screen displays this information. The collar is a separate component from the pressure vessel and is placed on the top of the pressure vessel surrounding the valve.

Description

WO 2014/125010 PCT/EP2014/052795 PRESSURE VESSEL WITH DISPLAY The present invention relates to a pressure vessel for storing a compressed gas. 5 The term "gas" as used herein includes within its scope a gas mixture. The gas may be a permanent gas, in which case it can be stored in a pressure vessel entirely in gaseous state, or a non-permanent gas, in which case it may exist under pressure in the storage vessel as a liquid phase in 10 equilibrium with a gaseous phase according to the storage pressure. Pressure vessels for storing compressed gases are of course very well known and are commonly referred to as "gas cylinders" because they conventionally, but not necessarily, have a cylindrical shape. A gas cylinder is 15 typically able to store gas at a pressure of up to 200 bar or 300 bar. A gas cylinder is conventionally formed as a one-piece vessel, symmetrical about a longitudinal axis, from a suitable steel. The walls of the vessel have a suitable thickness to be able to withstand cycling of pressure from atmospheric pressure to a maximum storage pressure, which as stated above may be as 20 high as 300 bar. The cylinder has an axial opening in which is fitted a valve, typically having a brass body with external screw threads that engage complementary screw threads in the mouth of the cylinder. There are various different kinds of cylinder valve, but all kinds are able to be opened to permit the controlled discharge of gas from the cylinder and also, when the cylinder 25 is empty, to enable it to be refilled. Some cylinder valves have an integral pressure regulator to enable the user to set the pressure at which gas is delivered. Alternatively the cylinder valve may have a port in which a separate pressure regulator may be docked. The pressure regulator may include a pressure gauge to indicate the delivery pressure to a user. Such a pressure 30 gauge is not in continuous communication with the interior of the cylinder.

WO 2014/125010 PCT/EP2014/052795 -2 EP 2 339 222 discloses an arrangement in which a pressure sensor has a continuous communication with the interior of the pressure vessel and a temperature sensor is in thermal communication with the interior of the vessel. The signals from these sensors are fed to a controller which displays certain 5 information on the content on a display screen. The application is primarily directed to a modern lightweight cylinder which has a plastic shell with handles under one of which the screen is positioned. The application also mentions the possibility of applying the principle to a traditional steel cylinder, in which case it suggests incorporating the display screen into the valve 10 assembly or guard. Incorporating the display into the guard is directly analogous to include these in the shell of the lightweight cylinder, although no specific example is given of how this is done. According to the present invention, there is provided a pressure vessel 15 apparatus for the storage of compressed gas, comprising: (a) a pressure vessel for containing the compressed gas; (b) a shut-off valve in engagement with the mouth of the pressure vessel; (c) a pressure sensor device for sensing the pressure in the vessel, 20 the pressure sensor device being in continuous communication with the interior of the pressure vessel and being adapted to generate a first signal which is a function of the sensed pressure in the pressure vessel; (d) a temperature sensor device for sensing the temperature of the gas in the vessel, the temperature sensor device being in thermal 25 communication with the interior of the pressure vessel and being adapted to generate a second signal which is a function of the sensed temperature of the gas; (e) a programmable computing device for calculating information concerning the amount of contents in the pressure vessel from the said first 30 and second signals; WO 2014/125010 PCT/EP2014/052795 -3 (f) a display screen operatively associated with the computing device for displaying said information; (g) a collar which is a separate component from the pressure vessel which is placed on the top of the pressure vessel surrounding the valve; and 5 (h) a guard or retaining ring attached to the pressure vessel to hold the collar in place between the pressure vessel and the guard or retaining ring, wherein the display screen is in the collar. Positioning the display on the collar, rather than on the guard provides 10 a number of advantages. Specifically, a problem with the arrangement disclosed in EP 2 339 222 is that the shell can only be fitted to the liner in a single orientation. This orientation is unlikely to be aligned with the sensors. As a result of this, any cabling connecting to the sensors to the computing device and/or screen needs to be long enough to cope with the worst case 15 scenario, namely that the sensor is on the opposite side of the vessel to the computing device/display screen. Not only is this wasteful in requiring extra cabling, but also it can become awkward to attach, particularly when the sensors and computing device/display screen are in alignment as there is then an excess length of cable to be accommodated. 20 Placing the screen on the collar avoids this problem as the collar is free to rotate until such time as it is secured in place by the guard or retaining ring. As a result of this, the collar can be aligned with the sensors such that a very short length of cable is always sufficient to make the connection. 25 Also, the circumferential nature of the collar provides plenty of room to accommodate a larger screen then can be accommodated in the guard. The collar is generally a thin-walled plastic structure as to opposed to the guard which is a relatively thick metal structure. It is therefore easier and cheaper to 30 produce a collar which can accommodate a screen and also to attach the screen to the collar. It can be simply and cheaply replaced in the event of a WO 2014/125010 PCT/EP2014/052795 -4 screen malfunction. The position of the collar ensures that the screen is protected in both the body of the pressure vessel and the guard itself and it is therefore well placed for protection against accidental damage. 5 The apparatus according to the invention is thus on simple inspection of the display screen able to impart to the viewer information about the amount of contents present in the vessel. In the example of a permanent gas, the computing device may be programmed to calculate the mass of gas in the cylinder from the real gas equation. This calculated mass may be compared 10 with the mass of gas in the pressure vessel when full, and a pictorial, graphical or digital display of the information may be made, for example as a position on a full to empty scale. If the gas is not permanent, and a liquid phase is present in the 15 pressure vessel, the apparatus according to the invention may additionally comprise a level detector for detecting the level of liquid in the pressure vessel, the level detector being adapted to generate a signal which is a function of the sensed level of the liquid in the pressure vessel and to transmit the signal to the programmable computing device. 20 The pressure and temperature sensors may be in the shoulder of the vessel as shown in EP 2 339 222. However, preferably, the pressure and temperature sensors are located within a sensing port or ports in the shut off valve on its pressure side. 25 Pressure vessel apparatus according to the invention will now be described by way of example with reference to the accompanying drawings, in which: 30 Figure 1 is a schematic, cross-section of a pressure vessel according to the invention; WO 2014/125010 PCT/EP2014/052795 -5 Figure 2 is a cross-section through the valve illustrating the pressure and temperature sensors; Fig. 3 is a schematic cross-section showing a second example of a 5 pressure vessel; and Figure 4 is a schematic diagram illustrating the electrical components included in the vessel. As shown in Fig. 1, the pressure vessel 2 is a conventional steel or 10 aluminium gas cylinder, or may be made of a seamless composite material. A cylinder valve 4 has a body with external screw-threads 5 complementary to threads 6 in the mouth of the cylinder 2 so as to enable fluid-tight engagement to be made between the mouth of the cylinder and the valve. In this example, the pressure transducer and temperature sensor 7 are located in a ports in 15 the valve 4. This is similar to the arrangement disclosed in US 5,975,121. As shown in Fig. 2, the pressure transducer and temperature sensor 7 is provided in a lateral port 8 which leads to the main valve bore 9, the flow through which is controlled by valve element 10 and is well known in the art. 20 Extending around the neck of the cylinder 2 is a collar 11. Such collars are well known in the art and are attached to the cylinder to provide safety information and information on the content of the cylinder. This is held in place by the guard 12. 25 The collar 11 accommodates a display screen device 13 and also houses the computing device described below . A cable 14 connects the screen device 13 and computing device with the pressure transducer and temperature sensor. 30 WO 2014/125010 PCT/EP2014/052795 -6 As shown in Figs. 1 and 2, the temperature sensor may be integrated into the same housing as the pressure transducer. Alternatively, a temperature sensor may be provided in a separate bore, attached to the external face of the cylinder, or even integrated into the screen device 13. In 5 these latter cases, the temperature sensor will not sense the internal temperature of the cylinder directly. However, by sensing the temperature of the wall of the cylinder, or of the immediately surrounding vicinity, the sensor is able to provide information from which an approximation of the temperature inside the cylinder can be determined. In this sense it can be said to be in 10 thermal communication with the interior of the pressure vessel. In order to assemble the device, the valve is fixed in place. The collar 11 with the screen device 13 in place is placed over the shoulder of the cylinder and the collar is rotated to bring the display into alignment with the 15 pressure transducer and temperature sensor 7. The collar 11 is then fixed in place by screwing the guard 12 onto the cylinder to hold the collar against the top of the cylinder. The cable is then connected to the pressure transducer. Alternatively, the cable may be connected before the collar is fixed place. 20 The collar may be held in place by a retaining ring 15, which is screwed in place instead of the guard as shown in Fig. 3. The electrical arrangements are illustrated schematically in Fig. 4. Here, the previously defined pressure transducer and temperature sensor are 25 designated separately by pressure sensor device 24 and a temperature sensor device 26. The pressure sensor device 24 is preferably of a kind based on the flexure of a ceramic membrane, for example, of aluminium oxide. This 30 material has good elasticity and is almost free of hysteresis. The upper side of the membrane has a bridge arrangement (not shown) of electric resistors WO 2014/125010 PCT/EP2014/052795 -7 attached thereto. Flexure of the membrane in response to the pressure in the pressure vessel causes the resistors to be deformed with the result that their electrical resistivity varies. An input voltage is applied to the bridge and an output voltage dependent on the degree of flexure of the membrane and 5 hence the pressure in the pressure vessel is tapped off from the bridge in a known manner. The output voltage is conducted to associated electrical circuits which amplify the voltage and provide a signal representative of the pressure to the display screen device 12. The pressure sensor device 24 is generally similar to that disclosed in US-B-6 978 678 to which document the 10 reader is referred for further information. If the gas is a permanent gas, the mass of the gas can be calculated from a knowledge of the sensed pressure, sensed temperature, the volume of the pressure vessel, and the composition of the gas with which the cylinder or 15 pressure vessel is filled. If the gas is not a permanent gas, however, and if the part of the gas is present in the pressure vessel in the liquid phase, then performance of such a calculation requires a knowledge of the volume of liquid present. In such an example, the temperature sensor device 26 may also incorporate a level sensor or level sensors (not shown). Alternative level 20 sensing devices can be used, for example, one emphasising sonic sensing of the liquid level. The display screen device 13 includes a programmable computing device 40 for calculating the mass of gas in the pressure vessel from the 25 sensed pressure and temperature signals (and, as appropriate, the liquid level) and for feeding signals representing the results of the calculations to the screen 42 of the screen device 22. The screen 42 typically utilises light emitting diodes (LEDs) and/or a Liquid Crystal Display (not shown). It may alternatively be an e-ink. The display screen device 13 may also house a 30 battery (not shown) for activating the display screen 42. The battery may be WO 2014/125010 PCT/EP2014/052795 -8 disposable or rechargeable and may also be used to provide electrical power to the sensors. The computing device 40 may also calculate parameters relating to the 5 mass of gas in the cylinder or pressure vessel. For example, the device 40 may be programmed with the mass of gas present when the cylinder was full, and calculate how full the cylinder is at any time, for example, on a scale of 0 100, 0 being empty and 100 being full. This information can be displayed numerically as a percentage or pictorially . Other calculations may be made. 10 For example, if the gas is intended for use as a shielding gas in electric arc welding, then there may be calculated and displayed the length of time for which gas can be drawn from the cylinder before it runs out. In another example, if the gas is intended for use in filling balloons, the mass of gas present in the cylinder at any one time may be expressed in terms of the 15 number of balloons that can be filled before the cylinder runs out of gas. The display screen 42 may be permanently illuminated or may be provided with control buttons such that a particular parameter or parameters will be displayed only when the buttons are depressed. 20 The electrical arrangements are illustrated schematically in Figure 4. All requirements for electrical power are met from a rechargeable or disposable electrical DC battery 60. The battery supplies the electrical power necessary to operate the pressure sensor device 24 and the temperature 25 sensor device 26. The battery 60 also provides the necessary electrical power to operate the display screen device 12. The display screen device 13 includes an analogue to digital converter circuit 62 which converts signals from the sensors 24 to 26 into digital form. The converter circuit 62 is operatively associated with a programmable microprocessor 64 including a 30 RAM (Random Access Memory) device (not shown) and interposes with an input keyboard 66 and output devices including a liquid crystal display screen WO 2014/125010 PCT/EP2014/052795 -9 42, a Light Emitting Diode display 68 for providing a visual alarm signal and a buzzer 70 for making an audible alarm signal. The voltage provided by the battery 60 may be transformed into a first larger DC voltage by transformer 72 so as to provide electrical power to the sensors 24 and 26 and the analogue 5 to-digital converter 62, and to a second larger DC voltage by transformer 74 so as to provide electrical power to the microprocessor 64 and the output devices. The pressure vessel apparatus is thus able to give the user of a 10 cylinder a visual indication of its contents, that is how full it is, on demand at any time.

Claims

1. A pressure vessel apparatus for the storage of compressed gas, comprising: 5 (a) a pressure vessel for containing the compressed gas; (b) a shut-off valve in engagement with the mouth of the pressure vessel; (c) a pressure sensor device for sensing the pressure in the vessel, the pressure sensor device being in continuous communication with the 10 interior of the pressure vessel and being adapted to generate a first signal which is a function of the sensed pressure in the pressure vessel; (d) a temperature sensor device for sensing the temperature of the gas in the vessel, the temperature sensor device being in thermal communication with the interior of the pressure vessel and being adapted to 15 generate a second signal which is a function of the sensed temperature of the gas; (e) a programmable computing device for calculating information concerning the amount of contents in the pressure vessel from the said first and second signals; 20 (f) a display screen operatively associated with the computing device for displaying said information; (g) a collar which is a separate component from the pressure vessel which is placed on the top of the pressure vessel surrounding the valve; and (h) a guard or retaining ring attached to the pressure vessel to hold 25 the collar in place between the pressure vessel and the guard or retaining ring, wherein the display screen is in the collar.

2. A pressure vessel apparatus according to claim 1, in which the computing device is programmed to calculate the mass of gas in the pressure 30 vessel. WO 2014/125010 PCT/EP2014/052795 - 11

3. A pressure vessel apparatus according to claim 2, wherein the programmable computing device is able to compare the calculated volume of gas with that in the pressure vessel when full. 5

4. A pressure vessel apparatus according to claim 3, wherein the comparison with the calculated volume of gas with that in the pressure vessel when full is able to be displayed pictorially, graphically or digitally by the display screen device. 10

5. A pressure vessel apparatus according to any one of the preceding claims, wherein the gas is a permanent gas.

6. A pressure vessel apparatus according to any one of claims 1 to 4, wherein the gas is not permanent and a liquid phase is present in the 15 pressure vessel, the apparatus additionally comprising a level detector for detecting the level of liquid in the pressure valve, the level detector being adapted to generate a signal which is a function of the sensed level of the liquid in the pressure vessel and to transmit the signal to the programmable computing device. 20

7. A pressure vessel apparatus according to any one of the preceding claims, wherein the pressure and temperature sensors are located within a sensing port or ports in the shut off valve on its pressure side.