EP0990487B1 - Apparatus for decontaminating surfaces with a jet composed of air, fine grained blasting material and a liquid - Google Patents

Abstract

The decontamination device is composed of an outer body (1) with a cylindrical bore (2) protecting the mixing chamber (5). A socket (7) assembled to the outer body protects a second bore (8). The outer body has a first inlet (13) for supplying liquid to the mixing chamber and a second sloping inlet (11) for a mixture of fine grain material and air. The second inlet is located so that the air and fine grain material mixture reaches the inner wall of the mixing chamber near its upstream end.

Description

The present invention relates to a device for surface decontamination, using a compound jet pressurized air, spray material to fine grains and a liquid, including a mixture in the form of a body of revolution fed axially by said liquid and obliquely and eccentrically to the axis of said chamber with the mixture of air and fine-grained material, said chamber communicating with a nozzle of spray said device consisting of an outer body provided with a cylindrical bore housing the mixing chamber, a socket provided with means for being assembled to said body exterior constituting said spray nozzle, said exterior body being provided with a first intake for feed in the axial direction of the mixing chamber in liquid, and a second inlet whose axis is oblique and offset from that of the mixing chamber for the entry of the air and fine grain material mixture, said second inlet being located so that the air and fine grain material mixture reaches the inner wall of the mixing chamber offset from the axis of the mixing chamber (as known from document DE 40 02 787 A).

It has been known for several years the use facilities for cleaning surfaces, including facades of buildings or monuments contaminated by atmospheric pollution or the passage of time, even on a voluntary basis (Graffiti). Such facilities include basically the use of an air jet under pressure comprising a grain spray material purposes commonly called aggregate and the use of a liquid which is, most of the time, clear water. One of the important elements of this installation, put share of course the different machines of supply of air, water and grain material purposes is the nozzle itself mounted on a handle of ordered. Such a control handle is described in FR-B 2 753 643 by the same inventor. The nozzle on this installation has a very important role because its construction and its geometry allow to give the throw a rotational movement around an axis, which allows to reproduce in a way a movement of friction on the surface to be decontaminated. The nozzle is an element which undergoes wear, if only by the presence of fine-grained material and pressure to which this material is subject. We use in principle of materials with high resistance abrasion by said material. However, after a number of uses, it is necessary to replace said nozzle so that the efficiency of the jet does not is not diminished. Currently, when work is not is done more satisfactorily, we proceed to replacing the nozzle instead of replacing only the part which has been subject to wear. This part is often the part upstream of the mixing chamber which receives first the air jet and the fine-grained material.

In document EP-A-0 110 529 a method is proposed of production based essentially on the presence of a high pressure liquid which sucks (Venturi effect) the aggregate and the air to form a jet, a device and a nozzle for implementing the method.

In document DE-A-40 02 787 a nozzle is proposed. the aggregate training is also provided by a liquid.

The present invention is directed to a nozzle in which the displacement of the aggregate is ensured by air under pressure, the liquid having more of a function comfort, i.e. preventing the dust produced during inconvenient decontamination, on the one hand, the user and, on the other hand, pollutes the ambient air. In certain situations, we can without diminishing the desired effect, interrupt the water supply.

The object of the present invention is to provide a new nozzle to overcome drawbacks above.

The decontamination device according to this invention is characterized in that said device consists of an external body provided with a cylindrical bore housing the mixing chamber, a socket having an approximately cylindrical shape provided with means for being assembled to said body exterior and housing a second body in a bore of revolution constituting said spray nozzle, that said outer body is provided with a first feed inlet in the axial direction of the liquid mixing chamber, and a second inlet whose axis is oblique and offset from to that of the mixing chamber for the entry of the mixture of air and fine-grained material, that said second intake is located so that the mixture air and fine-grained material reaches the wall interior of the mixing chamber near its end located upstream and it is offset by relative to the axis of the mixing chamber to the left when we are on the northern hemisphere and to the right when we are on the southern hemisphere so that the jet air and projection material benefits from the effect of Coriolis.

The advantages of the nozzle according to the invention are the fact that it is made up of four main elements, know the outer body receiving the chamber of mixture, the sleeve that protects the nozzle itself which is also a body of revolution which are individually interchangeable, allowing to replace only the worn or damaged part damage instead of replacing the entire device as is the case nowadays. Else apart, the fact that the air and projection material jet fine grain falls on the end of the chamber allows to use the entire length of the room for him give the desired movement in order to obtain a maximum efficiency at the outlet of the nozzle, contrary to what is done in the devices using liquid as a means of transporting grains. In addition, the fact that the second admission is offset from the axis of the mixing chamber of so the jet of air and projection material benefits from acceleration, the Coriolis allows to obtain a maximum kinetic energy at the exit of the nozzle therefore a great efficiency. It's obvious that this movement must be done either to the left or to right, depending on the Earth's hemisphere on which one is.

Another advantage is that the bedroom can be reused if it is turned by example of 180 °, thus doubling the life of the mixing chamber which is an economy substantial. It would also be possible to adjust the life of the room if we turn the room 120 °, which allows an even more substantial saving. Thus, for the element which undergoes the strongest wear, you can either extend your life by turning it 180 ° or 120 ° inside the external body, i.e. replace well before replacing the nozzle which undergoes less wear and in any case wear symmetrical since in this part, the jet moves helically, but always in the direction tangential to the wall of the nozzle, which the jet is not the case when it strikes the first times the upstream portion of the chamber wall mixed.

According to an alternative embodiment, the mixing chamber consists of an upstream cylindrical part and a tapered part downstream going in narrowing, this which allows the jet to pass inside the chamber mixing to a section whose diameter weakens to reach the next element which is the nozzle itself.

According to another variant, the admission allowing the supply of air and grain material includes a rod made of a material that resists abrasion which is screwed into a body tapping outside and it is surrounded by a sleeve made of preferably in plastic and on this sleeve is fixed by thread or other means the pipe for the supply of air and fine grain material.

This construction also allows to have a admission which resists abrasion due to fine-grained material. We can thus replace this rod when worn without having to replace the entire intake system and this allows also to have an item whose cost is not very high, which would be the case if this admission was made from a single piece of durable material abrasion.

According to another alternative embodiment, the mixture also ends on its outer part in tapering cone collaborating with the second body of revolution which has its upstream end a surface complementary allowing by interlocking of form a continuous channel between the mixing chamber and the outlet nozzle.

According to another alternative embodiment, the wall of the mixing chamber includes a conical part upstream going in narrowing inward of the chamber, followed by a cylindrical part, followed by a conical part going in narrowing, that the downstream end of said mixing chamber has an annular surface through which it comes lean on an annular surface corresponding to the second body of revolution.

The invention will be described in more detail using the drawing.

Figure 1 is an axial sectional view of the device according to the present invention.

Figure 2 is an axial sectional view only of the mixing chamber and the second body of revolution according to a second variant.

The device according to the present invention shown in the figure comprises an outer body 1 provided with a bore 2 inside which is disposed a body of revolution 5 constituting the mixing chamber. The body 1 is provided with an axial threaded passage 13 for the connection of a liquid supply pipe which preferably water, from a second tapping 3 arranged so as to form an angle of about 25 ° to 30 ° with the axis of chamber 5 and the axis of this bore tapped 3 is also slightly offset from the axis of chamber 5 from about 1 to 4 mm to the left of the axis of the mixing chamber with respect to the direction of movement of the jet in order to benefit from the Coriolis effect. If we are in the hemisphere South, this movement will have to be to the right. In this way we obtain kinetic energy maximum using in addition the entire length of the chamber 5. Inside this tapping is arranged a threaded rod 11 which is screwed there. Rod 11 is made of abrasion resistant material. Around from this rod 11 is fixed a sleeve 12 made of a plastic material provided on its upper part with a device for joining to a conduit. The device can be a bayonet or a thread or any other usual assembly device. The conduit thus formed allows the supply of air and material fine grain from chamber 5. Chamber 5 is arranged inside the body 1, so that the mixture including air and fine grain material comes to touch the wall upstream of the chamber before keep moving inside the room with a helical movement mainly thanks to the eccentric and oblique position of intake 3 and well heard the push of the liquid.

A socket 7 is provided with a bore 8 is fixed to the end of the body 1 by any conventional means 4, the simplest being screwed, a seal 14 ensuring sealing. Inside the bore 8 is arranged a body of revolution 9 having a passage having a diameter of the order of 10 mm. This body 9 presents in its upstream end a conical surface 10 coming marry the conical end 6 of chamber 5. So, we obtain an assembly allowing to have a passage between the mixing chamber 5 and the body 8 which is continuous ensuring that the jet will be free of protrusions that could affect the quality and jet efficiency.

As mentioned earlier, the value of this device is the fact that it is made up of multiple separate elements that can be replaced individually either for wear or to modify the dimensions, for example of the body 9 if the fine grain product should be used with nozzle of different dimensions.

It should also be noted that when the jet with air and the fine-grained material falls to the end of the chamber 5 causes wear which is localized at the place of impact and that after a certain number of uses can affect the quality of the spray.

In this case, it is necessary to replace the chamber 5, which can be done without replacing the entire device or as mentioned previously turn this 180 ° chamber or a third of a turn so to use the other part of the room which is not hit by the jet and which in reality does not disturb the dynamic qualities of the nozzle since this part of the surface of the chamber does not come into contact with the air and fine-grained material mixture only on the impact part, then the jet advances helically.

As an example, it can be mentioned that the mixture 5 can be made of carbide, body 9 of sintered alumina, the outer body 1 of aluminum or made of elastomer, Nylon, vinyl etc. Socket 7 could also be made of elastomer, vinyl, nylon etc.

According to an alternative embodiment shown in Figure 2, the chamber 50 has downstream a conical part 51 facilitating the access of air jet and grain material ends followed by a cylindrical part 52 and ending by a new conical part 54. The downstream end of the chamber has an annular surface 55 by which the chamber 50 rests on a surface correspondent 91 of the second body of revolution 90. The internal diameter of this body 90 being smaller that the smallest diameter of the chamber 50, part conical 92 upstream of the body 90 makes it possible to form a continuous passage without abrupt change of section, which would result in turbulence and a wear of the elements present. This configuration of parts 50 and 90 avoids sharp ends which may break due to shock from the arrival of the jet.

Claims (5)

1. A device for the decontamination of surfaces, by means of a composite jet of compressed air, a fine sprayable particulate and a liquid, comprising a mixing chamber (5, 50) in the shape of a body of revolution supplied axially (13) with said liquid and obliquely (3, 11) and eccentrically with respect to the axis of said chamber (5, 50) with the mixture of air and fine particulate, said chamber communicating with a spray nozzle (7, 9; 90), said device being constituted by an outer body (1) with a cylindrical bore (2) housing the mixing chamber (5, 50), a sleeve (7) of approximately cylindrical shape with means (4, 14) for fitting it to said outer body (1) and housing in a bore (8) a second body of revolution forming said spray nozzle; said outer body (1) being provided with a first inlet (13) for the supply of liquid in the axial direction to the mixing chamber (5, 50), and with a second inlet (3, 11) whose axis is oblique and offset from that of the mixing chamber for the entry of the mixture of air and fine particulate, said second inlet (3, 11) being situated in such a way that the mixture of air and fine particulate reaches the inner wall of the mixing chamber (5, 50) near its upstream end and is offset from the axis of the mixing chamber toward the left when on the northern hemisphere and toward the right when on the southern hemisphere so that the jet of air and sprayable material benefits from the Coriolis effect.
2. A device as claimed in claim 1, characterized by the fact that the mixing chamber (5, 50) comprises a cylindrical part (22) and ends downstream in a narrowing conical part (6; 23, 24).
3. A device according to one of claims 1 or 2, characterized by the fact that the inlet for the supply of the mixture of air and fine particulate comprises a hollow rod (11) made of an abrasion-resistant material screwed into a tapped hole (3) in the outer body (1), and that a plastic bushing (12) surrounds this rod (11) and is provided with means for connection thereto of a supply line carrying said mixture.
4. A device according to one of claims 1 to 3, characterized by the fact that the outer part of the downstream end of the mixing chamber (5) is conical (6), while the upstream end of the nozzle (9) has a complementary opening (10) enabling an intimate connection between the downstream end of the mixing chamber (5) and the upstream end of the nozzle (9).
5. A device according to claim 1, characterized by the fact that the wall of the mixing chamber (50) comprises upstream a conical part (51) that narrows toward the center of the chamber, followed by a cylindrical part (52), followed by a new narrowing conical part (53, 54), and the downstream end of said mixing chamber has an annular surface (55) by which it bears against a corresponding annular surface (91) of the second body of revolution (90).

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