GB2576361A

GB2576361A - A system

Info

Publication number: GB2576361A
Application number: GB1813406.4A
Authority: GB
Inventors: Bayerl WILHELM; Blondeau Jean; Bohn Matthias
Original assignee: Linde GmbH
Current assignee: Linde GmbH
Priority date: 2018-08-16
Filing date: 2018-08-16
Publication date: 2020-02-19
Also published as: GB201813406D0; WO2020035256A1

Abstract

A system 100 for measuring the fill level of gas inside a cylinder 200 comprises an impactor 12 configured to apply an acoustic impact to a cylinder; a sensor 14 configured to detect a response from the cylinder and generate a signal indicative thereof; and a computer readable storage medium 18 including data representative of a first response from the cylinder to an acoustic impact when the cylinder is at a first fill level. A processor 16 compares the signal to the data representative of the first response; and determines a fill level of the cylinder based upon this comparison. A method of detecting defects in a cylinder comprises applying an acoustic impact to the cylinder; detecting a response from the cylinder; comparing the response to a stored response at a first fill level and determining defects in the cylinder based on the comparison.

Description

- 1 A SYSTEM

The present invention is directed to a system for measuring the fill level of gas inside a cylinder and corresponding method of use and method calibration.

Conventionally, the only method suitable for measuring the content of a mobile gas vessel (such as a gas cylinder) filled with under-pressure liquefied gas has been to weigh the full cylinder and subtract the pre-measured weight of the cylinder when it was empty (tare weight). This is not an optimal solution as the gas cylinder should be disconnected from its associated piping in order to ensure a correct weight reading. In particular, the weight could be miscalculated as any cylinder fixation would impact upon the measured weight. Each connection and disconnection of the cylinder is an additional task involved in the measuring process and will allow an amount of gas to be lost to the atmosphere. Some systems do allow a cylinder with connected piping to be weighed. However, this means that the tare weight of the cylinder must also be determined in an identical configuration. This can be altered by any remaining pressure or tension in the connection pipes which still leads to erroneous results.

The content of permanent gasses in gas vessels has typically been measured by using a pressure sensor. For higher accuracy a temperature sensor can also be included to account for the effect of temperature of the gas on the exerted pressure. Each of these sensors requires a direct media contact to the pressurised gas. Accordingly, they will need to be inserted into the cylinder which introduces an additional step and allows for potential losses. The materials used in the sensor must also be carefully selected to ensure that they are compatible with the gas within the cylinder. Furthermore, it is not possible to measure the remaining content in a gas vessel filled with under pressure liquefied gasses simply by measuring the pressure in this manner. The head-pressure in such a cylinder is substantially constant until the very last of the liquid phase has been vaporised. The pressure then experiences a rapid drop. Accordingly, the pressure sensing method suitable for permanent gasses is not applicable in this situation.

There is therefore a need for an easy method to measure the remaining gas content in a gas cylinder.

-2A system for measuring the fill level of gas inside a cylinder according to the present invention is provided according to claim 1.

This system allows the fill level to be reliably measured without having to insert any probes into physical contact with the vessel’s contents. The system can also be used in-situ with a gas cylinder. In particular embodiments, the system can operate remotely without the need for an operator to physically access the system.

The computer readable storage medium may further include data representative of a second response from the cylinder to an acoustic impact when the cylinder is at a second fill level, different to the first fill level; and the processor may be further configured to: compare the signal to the data representative of the second response; and determine the fill level also based upon this comparison.

Having responses at two fill levels allows extrapolation to form a response profile for the cylinder across the entire range of fill levels. The fill level can therefore be accurately measured for any amount of gas in the cylinder.

The first fill level may be between 0% and 10%.

This represents a lower bound, representing when a cylinder is generally empty. This lower bound can be used to inform a user that the cylinder needs replacing.

The first fill level may be between 0% and 10%; and the second fill level may be between 90% and 100%.

These two readings generally span the entire range of fill levels and an accurate extrapolated response profile can be formed therefrom.

A method for measuring the fill level of gas inside a cylinder according to the present invention is provided according to claim 5.

This method allows the fill level to be reliably measured without having to insert any probes into physical contact with the vessel’s contents. The system can also be used in-situ with a

-3gas cylinder. In particular embodiments, the system can operate remotely without the need for an operator to physically access the system.

The method may further comprise the steps of: comparing the response to a second stored response at a second fill level; and determining the fill level of the cylinder based upon the comparison.

The first fill level may be between 0% and 10%.

A method of calibrating a system for measuring the fill level of gas inside a cylinder according to the present invention is provided according to claim 9.

A method of detecting defects in a cylinder according to the present invention is provided according to claim 11.

-4This method allows defects in the cylinder to be remotely detected without requiring inspection of the cylinder. The defects are also detected without requiring any physical contact between a sensor and the contents of the cylinder.

The present invention will now be described with respect to the following Figures in which: Figure 1 shows a schematic cross-section of a system according to the present invention.

Figure 1 shows a system 100 for measuring the fill level of gas inside a cylinder 200. While the present invention is described with respect to a cylinder 200, this is merely exemplary and the gas container could be any shape. In particular, the gas is preferably an underpressure liquefied gas or a permanent gas. The system 100 comprises an impactor 12 which is in physical contact with an outer surface of the cylinder 200. The impactor 12 may be arranged to physically strike the cylinder 200. Alternatively, the impactor 12 may use some other method to generate vibrations in the cylinder 200. The impactor 12 may be an actuator, in particular a piezoelectric actuator, a solenoid actuator, a spring powered actuator or a simple mechanical (hammer) actuator. The impactor 12 is configured to apply an acoustic impact to the cylinder 200. This acoustic impact will travel through the cylinder 200 and the characteristics thereof will be determined by the fill level of the cylinder 200.

A sensor 14 is further provided in communication with an outer surface of the cylinder 200. The sensor 14 may be any suitable sensor which is capable of determining the response of the cylinder 200 to the acoustic impact. In particular, the sensor 14 may be a vibrometer or microphone. As the acoustic impact travels through the cylinder 200 a response thereto will be generated by the cylinder 200. This sensor 14 is configured to detect this response and generate a signal indicative thereof.

The signal generated by the sensor 14 is transmitted to a processor 16. The processor 16 is further in communication with a computer readable storage medium 18. The computer readable storage medium 18 may be provided locally in proximity to the cylinder 200. Alternatively, or in addition, the computer readable storage medium may be a remote system which can be accessed by the system 100, such as via the internet (the “Cloud”). The computer readable storage medium 18 includes data representative of at least a first response from the cylinder 200 to an acoustic impact when a cylinder 200 is at a first fill

-5level Fi. The processor 16 compares the received signal from the sensor 14 to the first response and based upon this comparison determines the fill level of the cylinder 200.

The number of responses stored in the computer readable storage medium 18 that the processor 16 is configured to determine the fill level depends upon the accuracy required. For simple operations, it may be sufficient to have a single stored response and the processor 16 simply configured to determine whether the contact fill level Fc is higher or lower than the fill level F, for this stored response. In particular, this fill level F, could be between 40% and 60%. In preferred embodiments this fill level F, may be approximately 50%. Accordingly, the processor 16 would be able to determine whether the cylinder 200 is above or below half-full. In further embodiments, this first fill level F, could be set at a lower bound, such as between 0 to 20%, in order to warn the user that the cylinder 200 is substantially empty and near replacement.

In a preferred solution, the computer readable storage medium 18 includes first and second responses from the cylinder to an acoustic impact when the cylinder is at first and second fill levels Fi, F2 being different to one another. The first and second fill levels F1, F2 may be selected to generally correspond to a full state of the cylinder 200 and an empty state of the cylinder 200 respectively. While it may not be possible to completely empty or completely fill the cylinder it is appreciated that within 10% thereof may be suitable for the present invention. With these empty and full responses stored, the processor 12 may extrapolate a reference for the entire range of fill-levels that the detected signal can be compared to. This allows the current fill level Fc of the cylinder 200 to be generally known at any level.

In order to obtain these empty and full fill levels a calibration method may need to be carried out on the cylinder 200. In particular, the cylinder 200 when empty can have the acoustic impact applied by the impactor 12 and the response detected by the sensor 14. This response is then stored in the computer readable storage medium 18 (whether locally or remotely, as discussed above). The cylinder 200 is then filled with the relevant gas and the impactor 12 applies a second acoustic impact to the now full cylinder 200. Again, the response thereto is detected by the sensor 14 and stored in the computer readable storage medium 18. The system 100 is then configured to determine the current fill-level Fc of the cylinder 200. This configuration needs to be done only once for each combination of cylinder 200 and fill-gas.

-6While this calibration can be done locally at each time, it is also anticipated that the calibration may be done globally for known cylinder and gas combinations and stored on the computer readable storage medium 18. The system 100 may then further comprise an input for the user to select which pre-stored calibration they desire without the need to locally re-calibrate.

The system 100 may further include a transmitter which is configured to send a signal when the cylinder 200 reaches a pre-determined low level. This signal may be for example a warning signal which could be sent to a user’s device such as a smart phone. Alternatively, the signal could automatically trigger an order for a replacement cylinder to be delivered. The signal can be sent via any known transmission method with an appropriate transmitter selected. This includes, but is not limited to, via Bluetooth (RTM) and/or the internet.

A further use of the system 100 may be to detect damage in the cylinder 200 (cracks, corrosion, etc.). The response of the cylinder 200 to the acoustic impact can be compared to a response at a known pressure stored on the computer readable storage medium 18 (whether locally or remotely, as discussed above). The differences between the response of the cylinder 200 and the stored response can then be analysed in order to determine any defects in the cylinder 200. For example, cracks or corrosion may cause a reflection of the response to be generated, which can be detected. The comparison may, in particular embodiments, take the form of a comparison of the acoustic spectrum of the responses.

While the system 100 depicted in the Figures is shown generally in the valve region of the cylinder 200 this is not necessarily the case. In particular, the system 100 could be provided at any point on the cylinder 200. This may be in the form of a further attachable component which attaches to the cylinder. However, it is convenient if the system can be incorporated into the valve as there may already be further use for components therein.

Claims

CLAIMS:

1. A system for measuring the fill level of gas inside a cylinder, the system comprising: an impactor configured to apply an acoustic impact to a cylinder;

a sensor configured to detect a response from the cylinder to the acoustic impact and generate a signal indicative thereof; and a computer readable storage medium including data representative of a first response from the cylinder to an acoustic impact when the cylinder is at a first fill level;

a processor in communication with the sensor and computer readable storage medium, wherein the processor is configured to:

receive the signal from the sensor;

compare the signal to the data representative of the first response; and determine a fill level ofthe cylinder based upon this comparison.

2. The system of claim 1, wherein:

the computer readable storage medium further includes data representative of a second response from the cylinder to an acoustic impact when the cylinder is at a second fill level, different to the first fill level; and the processor is further configured to:

compare the signal to the data representative of the second response; and determine the fill level also based upon this comparison.

3. The system of claim 1 or 2, wherein the first fill level is between 0% and 10%.

4. The system of claim 2, wherein:

the first fill level is between 0% and 10%; and the second fill level is between 90% and 100%.

5. A method for measuring the fill level of gas inside a cylinder, the method comprising the steps of:

providing a cylinder;

applying an acoustic impact to the cylinder;

detecting a response from the cylinder to the acoustic impact;

comparing the response to a first stored response at a first fill level; and determining a fill level ofthe cylinder based upon the comparison.

6. The method of claim 5, further comprising the steps of:

comparing the response to a second stored response at a second fill level; and determining the fill level of the cylinder based upon the comparison

7. The method of claim 5 or 6, wherein the first fill level is between 0% and 10%.

8. The method of claim 6, wherein:

9. A method of calibrating a system for measuring the fill level of gas inside a cylinder, the method comprising the steps of:

providing a generally empty cylinder at a first fill level;

applying an acoustic impact to the cylinder;

detecting an empty response from the cylinder to the acoustic impact; storing the empty response in a computer readable storage medium; filling the cylinder with a gas to a generally full second fill level; applying a further acoustic impact to the cylinder;

detecting a full response from the cylinder to the acoustic impact; and storing the full response in the computer readable storage medium.

10. The method of claim 9, wherein:

11. A method of detecting defects in a cylinder, the method comprising the steps of: providing a cylinder;

applying an acoustic impact to the cylinder;

detecting a response from the cylinder to the acoustic impact;

comparing the response to a first stored response at a first fill level; and determining whether there are any defects in the cylinder based upon the comparison.