AUTONOMOUS VISCORED FOAM GENERATION DEVICE

Abstract

This foam-generating device is easily transportable, requires no fluid or electricity supply, and is capable of producing a viscous foam with a high, constant expansion (low liquid fraction). Compressed gas is drawn from a cylinder (2), and a fixed fraction of its flow rate drives a pneumatic pump (5) that draws in the foaming liquid. The foam is formed in a mixer (6) containing freely moving solids just before the device's discharge end (7). Applications include the decontamination and remediation of large areas of buildings or structures, both indoors and outdoors. See Figure 1 for abbreviations.

Description

Title of the invention: AUTONOMOUS DEVICE FOR GENERING VISCORED FOAM

[0001] The present invention relates to an autonomous device for generating viscosified foam.

[0002] It will be useful in particular in decontamination or pollution control work, in which foams must be applied to large surfaces which may be highly inclined or vertical, belonging for example to buildings, or in almost enclosed volumes, possibly difficult to access, and remain on these surfaces for a long enough time to act on the polluting products, without running or degrading in any other way.

[0003] Viscose foams are valued for this purpose; that is, foams enriched with a gelling agent that increases their physical stability and makes them less prone to flowing over even highly inclined or vertical surfaces. These two characteristics allow the foam to act for a sufficient time on the surface being treated. Examples are given in FR 2 841 802 A1. One of their drawbacks is that they are difficult to manufacture from a liquid foaming solution, precisely because of the high viscosity of this solution. Foam-generating devices are generally designed for conventional foams and are not suitable for viscose foams.In particular, they do not allow for a sustained high overrun of the foam produced, i.e. a low liquid fraction in the foam (for example less than 10% by volume); a lower overrun has the disadvantage of using an excess of liquid products for the same volume of foam, and of producing fewer, more durable small bubbles.

[0004] An example of a foam-generating device is described in WO 2013 / 067401 A2; this device is partially portable, but it is designed for ordinary foams used against fires.

[0005] An object of the invention is to manufacture foams, in particular special high expansion foams, reliably, at a high flow rate, by means of a suitable generator whose operation is stable.

[0006] Other objects of the invention are:

[0007] - to be able to transport the device without difficulty to hard-to-reach places and deprived of any source of supply, for example water or electricity;

[0008] -to offer certain security advantages to the operator.

[0009] According to a general definition, the invention relates to a generation device of foam, comprising a reservoir of a foaming liquid, a compressed gas cylinder, a first conduit exiting the reservoir and passing through a pneumatic pump by being connected to suction and discharge ports of said pneumatic pump, a second conduit exiting the cylinder and passing through a regulator, the first conduit and the second conduit joining at a junction; a conduit for transporting a mixture of the foaming liquid and the compressed gas extending between the junction and a foam ejection end (7); a mixer of the foaming liquid and the compressed gas, into an inlet of which the first conduit and the second conduit terminate and in which the foam is formed, and situated on the conduit for transporting the mixture between the junction and the ejection end; the second conduit comprising a bifurcation leading to a pneumatic pump start-up port.

[0010] This device, in which compressed gas is used both to produce the foam and to draw the foaming liquid from its reservoir, eliminates the need for a power supply, thus avoiding the need for either an external power source via cables or a heavy battery. The flow rate of the drawn liquid, determined by the energy supplied to the pump, is proportional to the pressure of the compressed gas, and the flow rate of the compressed gas used to produce the foam is also proportional to this pressure. The stability of the foam's expansion ratio, i.e., the value of its liquid fraction, is therefore guaranteed without any adjustment. The mixer integrated into the device is well-suited to producing foam with the required qualities.

[0011] According to various optional improvements to this design:

[0012] - the device includes a pressure gauge for measuring the pressure of the compressed gas in the bottle;

[0013] - the mixture transport conduit includes a flexible lance;

[0014] - the device comprises a single control lever, located on the lance, opening of the lance and ejection of the foam;

[0015] - the mixer comprises a cylindrical wall open at both axial ends and traversed by the mixture between the said axial extremities, a cage formed in the cylindrical wall, and at least one solid body free to move in the cage;

[0016] - at least one solid body consists of 1 to 40 balls, constructed of materials rigid;

[0017] - the cage is 10 to 400 mm long, 10 to 100 mm in diameter, and the balls are 2 20 mm in diameter;

[0018] - the cage is delimited by two grids following one another in the cylindrical wall; - the The device is mounted on a portable chassis or rolling cart, and is completely independent, in operation, of external supplies, including electricity or fluids.

[0019] The invention is well suited to the generation of foams containing a gelling agent.

[0020] The invention will now be described in its various aspects, characteristics and advantages, by means of the following figures, which illustrate a particular embodiment thereof, given purely for illustrative purposes:

[0021] - [Fig.1] is a diagram of an embodiment of the invention;

[0022] - [Fig.2] represents the mixer;

[0023] - [Fig.3] represents the end of the projection lance;

[0024] - [Fig.4] illustrates a concrete arrangement of the realization.

[0025] Referring to [Fig.1], the apparatus comprises a reservoir 1 of foaming solution in liquid state, a compressed air cylinder 2, a pressure gauge 3, a main regulator 4, a pneumatic pump 5, a mixer 6, a foam ejection end 7, and a chassis 8. A first conduit 11 connects an outlet port of the reservoir 1 to a suction port 12 of the pneumatic pump 5; It exits the pneumatic pump 5 through its discharge port 13, passes through the mixer 6 and reaches the end 7. A second conduit 14 connects an outlet port of the cylinder 2 to the main regulator 4, then joins the first conduit 11 at a junction 15 made between the discharge port of the pneumatic pump 5 and the mixer 6. A bifurcation 16 of the second conduit 14 leads to an orifice 17 for starting the rotor of the pneumatic pump 5 (possibly via a second regulator 43 to independently adjust the pressure at this point).The branch 16 leaves the second conduit 14 just downstream of the main regulator 4 and therefore carries slightly compressed air at constant pressure (7 bar for example). The pressure gauge 3 is connected by a pressure tapping conduit 20 to the second conduit 14, upstream of the main regulator 4, and it therefore allows the gas pressure at the outlet of cylinder 2 to be measured and its fill level to be assessed.

[0026] The frame 8 carries the reservoir 1, the bottle 2, the main regulator 4, the pneumatic pump 5, the first conduit 11, and the second conduit 14. As shown in [Fig. 4], the frame 8 can be vertical and belong to a backpack worn by the device operator; the frame 8 can also be a rolling cart, for example. The foam ejection nozzle 7 is not attached to the frame 8, but is located at the end of a flexible nozzle 21, which is held by the operator. The nozzle 21 extends between the nozzle 7 on one side and the junction 15 on the other.

[0027] The mixer 6 is located in the path of the liquid and compressed air mixture between the junction 15 and the end 7, and is shown in [Fig. 2]. It comprises two flat grids 28 arranged successively in the bore 24 of a cylindrical wall and occupying its entire cross-section, two sealing gaskets 29 to which the grids 28 are respectively fixed and which serve as supports for them against the wall of the bore 24, and spherical balls 30 and The rigid elements are free to move between the grids 28. The seals 29 serve to hold the grids 28 in place and to form a cage 31 between them, further delimited by the wall of the bore 24, and in which the balls 30 are retained. They also force all fluids circulating in the bore 24 to pass through the interior of the cage 31.

[0028] This type of mixer, comprising balls, or more generally solid bodies, free in a cage through which the pre-mixed fluids pass, has proven very effective in producing foams with a well-defined and potentially high expansion ratio, i.e., with a low liquid fraction. It is particularly suitable for the manufacture of viscosified foams, but other types of mixers are also compatible with a good embodiment of the invention.

[0029] Fig. 3 shows that the end 7 is fixed to the front end of a gun barrel 32 held by the operator, the rear end of which is joined to the nozzle 21. The operator opens the nozzle 21 and triggers the foam projection by pressing a trigger 35 of the gun 32.

[0030] Fig. 4 illustrates a possible arrangement of equipment on chassis 8, where a spare tank 1' is also shown, used when the first one (tank 1) has been emptied.

[0031] The operation of the device and its advantages can be described as follows. As the device is independent of any external power source, the operator can easily put it on or transport it to remote or hard-to-reach locations. The operator grasps the nozzle 21 by the gun 32 and presses the trigger 35 when in front of the surface to be covered with foam. The opening of the nozzle 21 allows compressed air to flow through the second conduit 14. Part of the flow passes through the pneumatic pump 5, activating it and serving to draw a constant flow rate, proportional to the air flow rate through the pump 5, of the foaming solution from the reservoir 1. The pumped foaming solution and the main flow of compressed air, which is directed towards the nozzle 21, converge at the junction 15, upstream of the mixer 6.Here too, the flow rate of the foaming solution and that of the compressed air mixing with it are proportional and therefore have an invariable ratio, determined by the physical characteristics of the fluids and the device. The foam is formed by the mixing of air and the foaming solution, passing through the mixer 6, which is very effective in obtaining a high-expansion foam, desirable among other things for viscous foams.

[0032] Some additional details, of a concrete nature, are given below to describe more fully a particular example of this realization of the device and its performance.

[0033] Bottle 2: capacity of 31, starting pressure of 300 bars;

[0034] Tanks 1 or 1': capacity of 81 each;

[0035] Main regulator 4: reduces the pressure to 7 bars;

[0036] Second regulator 43: reduces the pressure to 4 bars;

[0037] Mixer 6: diameter and length of cage 31: from 10 to 100 mm and from 10 to 400 mm;

[0038] Rigid balls 30: from 1 to 40, from 2 to 20 mm in diameter;

[0039] Foaming solution: water, with Glucopon 215UP [BASF] at 10g / l, and Xanthan Gum (G1253) [Sigma Aldrich] at 3g / l;

[0040] Layer projected onto a vertical surface: 10 m², 1 cm thick, in 120 s; sliding speed less than 1 m / min. If the foam is used to fill a volume, the foam retention time is at least 120 min.

[0041] Foaming of the foam obtained: approximately 16.7 (approximately 100 liters of foam produced for 6 liters consumed of the foaming solution).

[0042] The balls 30 could be replaced by another solid body freely mobile in the cage 31, and their number could also be different, only one solid body being possible.

Claims

Demands

1. Foam generation device, comprising a reservoir (1) of a foaming liquid, a cylinder (2) of compressed gas, a first conduit (11) exiting the reservoir and passing through a pneumatic pump (5) by being connected to suction (12) and discharge (13) ports of said pneumatic pump, a second conduit (14) exiting the cylinder (2) and passing through a regulator (4), the first conduit and the second conduit joining at a junction (15); a conduit (21) for transporting a mixture of the foaming liquid and the compressed gas extending between the junction (15) and a foam ejection end (7); a mixer (6) of the foaming liquid and the compressed gas, in which the foam is formed, and located on the conduit (21) for transporting the mixture between the junction (15) and the ejection end (7);the second conduit comprising a bifurcation (16) leading to an orifice (17) for starting the pneumatic pump, characterized in that the mixer (6) comprises a cylindrical wall open at both axial ends and through which the mixture passes between said axial ends, a cage (31) formed in the cylindrical wall, and at least one solid body (30) free to move in the cage, the at least one solid body consisting of 1 to 40 balls, constructed of rigid materials, and in that the cage is 10 to 400 mm long, 10 to 100 mm in diameter, and the balls are 2 to 20 mm in diameter.;

2. Foam generation device according to claim 1, characterized in that it comprises a pressure gauge (3) for measuring the pressure of the compressed gas in the bottle (2).

3. Foam generation device according to any one of claims 1 or 2, characterized in that the mixture transport conduit (21) comprises a flexible lance.

4. Foam generation device according to claim 3, characterized in that it comprises a single control lever (35), disposed on the lance (21), for opening the lance and ejecting the foam.

5. Foam generation device according to any one of generations 1 to 4, characterized in that the cage is delimited by two grids (28) following one another in the cylindrical wall.

6. Foam generation device according to any one of claims 1 to 5, characterized in that it is mounted on a portable chassis (8), and completely independent, in operation,

7. of external supplies, in particular electricity or fluids. Application of a device according to any one of the preceding claims to the manufacture and projection onto a surface of a foam containing a gelling agent.

Images