FR2780484A1 - Safety device for avoiding the overfilling of liquified gas bottles, particularly LPG bottles - Google Patents

Abstract

The device comprises a support (7) holding the bottle (6) horizontal, a pressure connection for the liquid phase and one for the gas phase, a gas/liquid differential pressure detector, a feeler-gauge (9) to determine the diameter of the bottle, a detector measuring liquid inlet temperature and two controlled valves, one modulating and the other stopping liquid flow A sleeve for a pressure connection for the liquid phase is along the axis of and outside the bottle and a pressure connection for the gas phase is inside the liquified gas storage vessel. The device has two inclined half-planes (7) with a horizontal intersection, which hold the bottle still in a horizontal position. The feeler-gauge is held against the bottom periphery of the bottle by a spring (10) and the displacement is transformed by a transducer (11) into an analogue or numerical signal allowing the bottle diameter to be determined. A calculator is programmed to control the valves using information from the installed transducers. The calculator can simultaneously control several filling posts.

Description

The present invention relates to a device for controlling

  filling of liquefied gas cylinders, particularly liquefied petroleum gas (LPG) in

  low capacity installations presenting risks of overfilling.

  The filling of a bottle beyond a critical rate (overfilling situation) characteristic of the mixture of hydrocarbons present results, in the event of an increase in temperature, by swelling of the liquid phase (L) which can lead to the bursting of the enclosure or to an invasion of liquid in the gaseous starting pipe of the installation of use, causing fires or explosions. Large capacity industrial filling centers are generally provided with control devices allowing 1 O not to introduce into the commercial circuit bottles which have been abnormally overfilled. This is not the case for low capacity units, which are very widespread, the technicality of which is limited to filling functions with manual or automatic stop without a posteriori control, which equip establishments which are often multi-product and which are likely to receive packages of different sizes. These factors combine to significantly increase overfilling situations and the risks associated with them. The invented device makes it possible to remedy this state of affairs by controlling the filling operation and by stopping it when the maximum admissible rate fixed beforehand is reached, this operating from the outside of the bottle, without introduction of probe or of Z 0 gauge inside the bottle. Unlike conventional systems which consist in filling a bottle arranged vertically on a rocker, the invented device consists in filling the bottle previously arranged in a horizontal position: - when the bottle is horizontal and its diameter known, it suffices to determine the height (H) of the liquid column above the axis of the cylindrical body of the bottle to then determine the filling rate. The filling rate tolerated corresponds to a height

  of liquid called the set value (VC).

  - when the bottle is horizontal, the static pressure at the axis can be measured outside the bottle by means of a special sleeve located in this same axis and in communication with the bottle, since the pressures on a same plane are equal, - the pressure of the gas headspace of the bottle can be determined by measurement on an external container containing a product of identical composition and temperature, in particular the storage of liquefied gas supplying the filling station; in the event of a temperature variation, it suffices to make the appropriate corrections, - knowledge of these two pressures makes it possible to calculate the height of liquid above the axis. Two other additional parameters must be taken into account: the diameter of the cylindrical body of the bottle as well as the temperature of the liquid. These four parameters are entered by sensors integrated into the device and then processed by a calculation unit. It is thus possible to access the knowledge of the level in the bottle "from the outside", as soon as the bottle is at least half filled. The calculation unit delivers a signal allowing automatic actuation of a valve for modulating the liquefied gas flow

  then a closing valve completes the filling circuit.

  \ O CA realization of the device comprises: - a V-shaped support (7) made up of two inclined half-planes, intended to receive the bottle (6) and to keep it in a horizontal position, - a probe (9) installed in the lower part of this support, held against the lower generator of the bottle by means of a spring (10), the displacement of which generates, by i 5 fl'intermediate of a transducer (I l), a signal depending on the diameter of the bottle, - a pressure tapping sleeve (5) in the axis of the bottle, adapted to the orifice of the bottle (tap, valve ...), interchangeable according to the types of bottles and provided with a drain, - a device for pressure test point (12) of the gas phase (O) in the storage tank tO of liquefied gases (1), - a differential pressure sensor (14), - a probe (13) for the temperature of the filling liquid ( L), - a calculation unit (15), - a modulating valve (3) controlled by the calculation unit, intended to reduce see the flow rate of 2. ' liquid when the level (H) in the bottle approaches the set value (VC), - a shut-off valve (4), also controlled by the calculation unit and intended to shut off the supply circuit when the level reaches the value (VC), The device does not replace the measurement of the quantity delivered, either by weight, in which case the V-shaped support is placed on a conventional tilting platform (8), mechanical or electronic, or by volume, in which case a metering device is installed on the line

  filling (2). The device constitutes an intrinsic safety device.

  The attached drawings illustrate the installation of the elements constituting the device: - Figure 1: overall drawing of the device, - Figure 2: bottle support

3 2780484

  The invention is capable of industrial application in the following cases: - reconfiguration of existing filling stations, so as to add an anti-overfill safety module, - development of new filling stations integrating this module, built around

  the calculation unit which can then present other functionalities.

Claims (3)

  1 / Safety device to avoid overfilling of liquefied gas bottles, particularly liquefied petroleum gas (LPG), characterized in that it comprises a support (7) making it possible to immobilize the bottle (6) in a horizontal position, a sleeve (5) for taking the pressure of the liquid phase in the axis of the bottle, outside the bottle, a pressure tap (12) for the gas phase inside the storage of liquefied gases ( 1), a sensor (14) of the liquid / gaseous differential pressure, a probe (9) for determining the diameter of the bottle, a probe (13) for measuring the temperature of the liquid phase on entering the bottle, a calculation unit (15) and two valves   allowing one (3) to modulate the flow of liquid, the other (4) to stop it.   À O 2 / Device according to claim 1 characterized in that it comprises two inclined half-planes (7) whose intersection is horizontal, making it possible to immobilize the bottle (6) in horizontal position.   3 / Device according to claim 1 characterized in that it comprises a feeler (9) held against the lower generator of the bottle under the effect of a spring (10), and whose displacement is transformed by means of a transducer (11) into an analog signal or   digital, to determine the diameter of the bottle.   4 / Device according to claim 1, characterized in that it comprises a calculation unit (15) equipped and programmed to capture the information from the transducers   installed, and control the valves for modulating and stopping the flow of liquefied gas.   O 5 / Device according to the preceding claims, characterized in that the calculation unit   allows multiple filling stations to be controlled simultaneously.