WO2006108976A2

WO2006108976A2 - Method for controlling filling of gas cylinders

Info

Publication number: WO2006108976A2
Application number: PCT/FR2006/050258
Authority: WO
Inventors: Jean-Yves Faudou; Jean-Yves Lehman; Jaya-Sitra Pregassame; Katia Barral
Original assignee: L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude
Priority date: 2005-04-13
Filing date: 2006-03-24
Publication date: 2006-10-19
Also published as: WO2006108976A3; FR2884592A1; FR2884592B1

Abstract

The invention concerns a method for controlling filling of a gas cylinder characterized in that it consists in using the skin temperature of the cylinder as controlling parameter.

Description

Method of controlling the filling of gas cylinders

The invention relates to a method for controlling the filling of gas cylinders.

In the present invention will be used indifferently the terms "bottles" or "tanks", which designate hermetic containers for storing gas under pressure. As the protection of the environment is becoming more and more of a concern for both industry and individuals, the demand for "clean" fuels for motor vehicles is growing. One of the alternatives to conventional fuels is the use of gas.

However, if filling a tank of gasoline or fuel that are liquid fuels is an easy and fast operation, the operation of filling gas tanks is much more delicate. Because of the compressibility of the gas, the filling can lead to significant heating and also raises the problem of "counting" amount of material transferred.

Indeed, the gas must be injected from a gas storage zone into tanks or bottles of gas under pressure (200 bar or more depending on the gas and the application); the storage zone is itself at high pressure or at low pressure and in this case it is necessary to use a compressor. It is obvious that for safety reasons, the final pressure in the tank, as well as the temperature of the gas inside the tank or the stored mass must not exceed the limits of resistance. of the tank as determined by the manufacturers of these tanks. In addition, the faster the filling, the higher the temperature rise is important and therefore it is difficult to optimize the amount of gas inside the tank.

One of the parameters for defining the filling conditions of a bottle is the value of the temperature of the gas inside the bottle.

However, the measurement of this temperature is difficult to obtain. Indeed, to measure it should be placed a thermal probe in a suitable area inside the bottle with all the sealing problems that implies.

Conventionally, the filling is carried out at ambient temperature, using the principle of controlling measured parameters and / or estimating the maximum value of these parameters which are the pressure and / or the temperature, using the measurement of embedded temperature as in patent applications EP1205704 and EP1336795, or by using the measurement of the injected mass which is carried out by weighing (US 4,527,600, US 4,648,430, US 5,771,947, US 5,771,948, US 5,810,058, US 5,881,779) or by measurement flow rate (US 4,993,462, US 5,238,030, US 5,752,552). Other conventional methods include cooling the gas at the bottle inlet to a temperature below room temperature as described in EP1331289.

However all the processes described are difficult to implement because the parameters to be measured are difficult to access, especially the internal temperature of the gas, or are very complex in their implementation and in the calculation methods used. Moreover, the parallel filling of several tanks is not necessarily envisaged. However it is conventional to fill tanks in parallel, especially in the case of vehicle application. Depending on their destination, the bottles or tanks have a variable capacity. This capacity can range from 2L (bottle for scooters for example) to 200L (bottles used for example in buses). The vehicle may have a single large capacity tank or several smaller capacity tanks in parallel. When several bottles are filled in parallel, in general two separate valves are used on each bottle: one for filling and the other for emptying. Sometimes one or the other valves clog up, which can generate dangerous situations, the bottles then being constantly under pressure or the filling mass flow rate being much too high, for example.

There is therefore a real need for a process for controlling the filling of the bottle (s) or the gas tank (s), which must in particular be filled in parallel, which is at the same time reliable, easy to implement, easy to use and suitable for any type of bottle and any type of filling, especially for fast filling, that is to say that must be done in less than ten minutes.

The present inventors, after extensive and extensive research, have found that the control of the filling of a bottle or reservoir can be achieved by measuring and controlling the skin temperature of the bottle or reservoir. By "skin temperature" in the present invention is meant the temperature of the outer surface of the bottles or reservoirs.

This value can be measured by placing temperature sensors directly on the outer surface of the bottles. For example, these sensors are placed on the cylindrical part of the bottle.

According to a first embodiment of the invention, the control of the filling is done by using the skin temperature as a parameter replacing the internal temperature of the gas. The temperature measured on the external surface is representative of the evolution of the internal temperature at inertia due to the constituent material (s) of the bottle, this temperature being nevertheless more easily accessible than the temperature of the gas in the bottle. It can therefore be used instead of the internal temperature to control the evolution of the filling of the bottle. This system can help to control the filling if another control system already exists and can also be an active control system based on the torque (pressure measured at the bottle inlet / skin temperature).

Advantageously, in this embodiment, the shape of the bottle must be such that at the end of filling, it makes it possible to obtain a homogeneous gas temperature. Such a characteristic depends on the geometry of the bottle, which advantageously has a generally cylindrical shape with a length L ratio on diameter D, L / D, less than 6, preferably from 1 to 5, and even more preferably from 1 to 4.

In addition, advantageously, the tanks to be filled are arranged horizontally or in a manner vertical and then the filling is done from top to bottom. This arrangement ensures homogeneity of the internal temperature of the gas.

The invention is also particularly useful for controlling bottles to be filled in parallel.

Thus, according to a second embodiment of the invention, the method relates to the parallel filling of identical bottles, the filling being controlled by the measurement and monitoring of the evolution over time of the skin temperature of each of the bottles, any difference in the evolution of this temperature from one bottle to another being reported. In practice, the temperature difference between all the bottles in parallel at any time t of the filling must be less than a certain Δθi _d defined beforehand between 20 ^° C. and 100 ^° C.

Thus, according to this embodiment, temperature sensors are placed on the outer surface of each bottle. During filling, the temperature of the gas in the bottle increases and the heat propagates in the constituent material (s) of the bottle. There is therefore a variation in the external temperature of the bottles after a certain period of time. This variation in temperature must be approximately identical in each bottle, since identical bottles are filled in the same conditions (in parallel). Thus, a different evolution in one of the bottles compared to others is the witness of an abnormality of the filling of this bottle, for example if the filling valve is clogged. The method of the invention allows the detection of this anomaly and the operator can intervene. The signal of the temperature sensors can be analyzed by an automaton. If a fault is measured, an error message may appear indicating the fault and identifying the faulty cylinder or the controller may also operate an automatic valve which cuts the gas supply circuit so as to interrupt the filling immediately and automatically. .

According to a third embodiment, particularly in the case where the bottles to be filled in parallel are not necessarily all identical or if it is desired to fill only one bottle or if there is no information on the bottles, the method of the invention then consists in measuring for each bottle the initial skin temperature θ _o , setting a minimum temperature difference to be reached (Δθ), and measuring the skin temperature θ _t of the bottles to one time t, if the difference θ _t -θ _o is less than Δθ, an anomaly signal is then given.

The time t must be sufficient so that the skin temperature has time to increase due to the inertia of the heat exchange between the gas and the outside, and must not be too important for the skin temperature of the bottle is not changed by a possible increase in the ambient temperature during the day. This time t can be set according to the type of bottle. Advantageously, t is at least equal to the filling time, preferably t is greater than this duration, more preferably still t is equal to 2 times the filling time of the bottle, it being understood that the filling is a rapid filling. that is to say, whose duration is between about 1 to 10 minutes.

Δθ is fixed either by the operator or automatically depending on the gas, the speed of filling (expressed in units of pressure per unit of time) and initial pressure. In general, Δθ may be between 10 and 70 ^° C., preferably between 10 and 40 ^° C. and even more preferably between 15 and 30 ^° C. The lower the Δθ value, the more likely the process will detect the only anomaly is that the valve is completely clogged. The higher the Δθ value, the more the system will be able to detect partially blocked valves. Thus, according to this embodiment, temperature sensors are placed on the outer surface of each bottle. During filling, the temperature of the gas in the bottle increases and the heat propagates in the constituent material (s) of the bottle. There is therefore a variation in the external temperature of the bottles after a certain period of time. The bottles being different (depending on the materials or the volume for example), the rise in temperature can also be different from one bottle to another. During the filling, if no change in skin temperature is measured during the time t defined (which may be greater than the duration of the filling) or if the skin temperature variation is lower than the defined Δθ, the bottle in question may have a defect: fill valve completely or partially blocked. Note that if the draw valve is partially or completely blocked, the bottle will only partially empty or not at all. The initial pressure in this bottle will be higher than the other bottles. The increase in temperature during filling will therefore also be affected.

The signal from the temperature sensors can be analyzed by a PLC and if a fault is measured, a error message may appear signaling the possibility of a fault and identifying the faulty bottle.

Of course, the control methods of the second and third embodiments described above can be combined, that is to say that a filling defect will be reported as soon as at least one of the following events occurs:

1 / the variation of temperature at time t fixed is less than Δθ 2 / the temperature of a bottle and the temperature of an identical bottle evolve differently, the difference being> Δθid

This combination is possible if the information concerning the identity of the bottles is given to the management automaton.

Thus, according to this particular embodiment, the management automaton has the information relating to the number of bottles to be filled in parallel, to the capacity of the bottles, to the identity or not of the bottles, and receives in dynamic mode the measurement. skin temperature sensors. The system therefore measures for each bottle the value Δθ at time t fixed and for identical bottles the value Δθi _d . If Δθ calculated is lower than the setpoint value, the PLC sends a fault signal. If Δθi _d is greater than the setpoint value, the automaton also emits an anomaly signal, which preferably and differs from the previous one.

In the second and third embodiments previously described, the temperature sensor must be correctly placed, that is to say, it must be placed at the place where there is the greatest rise in temperature, which rather corresponds to the bottom of the bottle. We can possibly place several sensors along the bottle.

The present invention is usable whatever the nature of the gas. It can be for example methane, hydrogen, oxygen, nitrogen, helium, etc. The vehicle application targets in particular natural gas or methane and

Hydrogen.

The anomaly signal can be visual and / or audible and can trigger the automatic closing of the tank inlet valves.

The invention will be described in more detail in the following examples which are given by way of illustration of the invention and which are not limiting. EXAMPLES

EXAMPLE 1: Parallel filling

A vehicle equipped with 2 Dynetek bottles with a capacity of 150 liters each and each equipped with a thermal sensor placed on the outer wall of the bottle will be filled with hydrogen. The thermal sensors are connected to the vehicle's dashboard. They display a temperature of 15 ^° C.

The filling conditions are calculated so that the simultaneous filling in parallel of the 2 bottles must be done in 3 minutes.

The table below summarizes the different values measured for each bottle at several times:

The temperature difference between the bottle 1 and the bottle 2 is 8 ⁰ C at time t = 2 min and 14 ⁰ C at time t = 3 min.

The difference Δθi _d between the two bottles must always be less than 1O ⁰ C. There is therefore filling anomaly.

The difference between T 3 min and initial T is 22 ⁰ C for bottle 1 and 8 ⁰ C for bottle 2.

A red light then lights on the dashboard and an abnormality of filling the bottle 2 is signaled.

EXAMPLE 2: Parallel filling of different bottles. 4 bottles DYNETEK (service pressure

350bar) will be filled with hydrogen. 2 of them have a capacity of 150L (Bl and B2) and the other 2 with a capacity of 205L (B3 and B4). Each bottle has a thermal sensor placed on the outer wall of the bottle. The thermal sensors are connected to the vehicle's dashboard. They display an initial temperature of between 15 ^° C. and 17 ^° C.

The filling conditions are calculated so that simultaneous filling in parallel of the 4 bottles must be done in 5 minutes. The time t is set at 10 minutes and Δθ is set at 20 ^° C. The table below summarizes the different skin temperature values measured for each bottle at different times t:

T, Δθ ( ⁰ C) B1 (150L) B2 (150L) B3 (205L) B4 (205L) measured at time t to 15 16 15 17 t = 2min30 28 29 22 19 (Δθ = 13 ^° C.) (Δθ = 13 ^° C.) (Δθ = 7 ° C.) (Δθ = 2 ° C.) t = 5 min 45 47 35 24 (ΔΘ = 30 ^° C.) (Δθ = 31 ^° C.) ( ΔΘ = 20 ^° C.) (Δθ = 7 ° C.) t = 10 min 51 52 49 31 (Δθ = 36 ^° C.) (Δθ = 36 ^° C.) (Δθ = 36 ^° C.) (Δθ = 14 ^° C.)

The temperature variations measured on the first 3 bottles (Bl to B3) are greater than 20 ^° C: their filling is "normal". On the other hand, the bottle B4 displays a temperature variation of less than 20 ^° C. Moreover, the temperature evolution between B3 and B4 is different. Bottle B4 thus has a defect which may be a partially clogged filling valve. A malfunction message is sent to the user.

Claims

1. A method of controlling the filling of a gas cylinder in which the skin temperature of the bottle is used as a control parameter, characterized in that the initial skin temperature θo is measured for each bottle, a temperature difference Δθ, to be reached at the end of filling is fixed, the skin temperature θ _t at a time t is measured, t being at least equal to the total duration of filling, preferably greater than the total duration of filling and more preferably still equal to 2 times the filling time, if θ _t -θo is less than Δθ, an anomaly signal is given.

2. Method according to claim 1 for filling at least two bottles, characterized in that the bottles are filled in parallel.

3. Method according to claim 1 or claim 2, the evolution of the skin temperature for each bottle is monitored over time and any difference in temperature evolution from one bottle to the other is reported, the bottles to be filled being identical.

4. Method according to claim 2 or claim 3, characterized in that the skin temperature difference between 2 identical bottles at any time of the filling must be less than Δθid, Δθid ranging from 20 ^° C to 100 ^° C.

5. A method according to any one of claims 1 to 4, characterized in that Δθ is between 10 and 7O ⁰ C, preferably between 10 and40 ° C and more preferably between 15 and 3O ⁰ C.

6. Method according to any one of claims 1 to 5, characterized in that the gas is selected from the group including in particular natural gas or methane, hydrogen, oxygen, nitrogen, helium.

7. Method according to one of claims 1 to 6, characterized in that it is intended for filling bottles on board motor vehicles such as cars, buses, motorcycles, mopeds, scooters, trucks, tractors.