FR2679796A1 - Machine and method for spraying a mixture which includes products having variable particle size distributions - Google Patents

Abstract

The invention relates to a machine for projecting a mixture comprising products of variable grain sizes and a low water content such as aggregates of natural or industrial origin. The machine is provided with a projection device (16) activated by at least one pressure fluid injection (23, 28) such as compressed air. The injection device is supplied with mixture by means (8, 19) and for transport (11, 15) means. The invention also relates to a method for projecting the mixture.

Description

 The present invention relates to a machine and a method of spraying a mixture comprising products of variable particle size at a distance distant from said machine.

 Machines are already known which are suitable for spraying mortar compositions by the so-called wet route, for example on the principle of the sparrow pump. These spraying machines often include a hydraulic transmission system allowing an easy and rapid reversal of the direction of rotation of all the moving parts, in particular the hopper and the pump. This is the case, among others, of the PRECTJET H 3000 machine from MI JET FRANCE, the MF 80 HY machine from MOSSMER, and the P13 from PUZMEISTER but these machines only work properly with micro-concretes with a high content of binders and very fluids. These types of mortars only allow the realization of facade facings.

 These machines are not suitable for spraying mortars with a lower content of binders and water. Indeed, there is quickly the formation of an air tunnel at the level of the hopper causing frequent defusing of the pump. On the other hand, the low content of binder leads to rapid segregation of the mixture on standby in the preparation tank. The mixture accumulates in a non-elastic plug at the inlet of the pump, causing another cause of defusing the pump.

 There are also known dry spraying machines comprising a closed tank and sealed under pressure, supplied with bagged dry products. But these machines are batch fed.

 Document FR-2598349 discloses a machine modified to solve these problems mentioned, this machine being adapted to spray a mixture containing between 15 and 50% of earth and between 85 and 50% of sand, to which a contribution of binders representing at most 10% of the dry weight in aggregates as well as water representing at most 22% of the total dry weight.

 However, this new machine hardly admits mixtures with a water content of less than 15% by total dry weight and is limited in projection distance to a few meters. In addition, the sparrow pump cannot admit large aggregates without damage.

 The object of the present invention is to improve this machine for spraying at greater distances (several tens of meters) a mixture comprising solids of various and varied particle sizes and having a water content at most equal to 15% and possibly dry. The mixture advantageously consists of pickling products from the soil surrounding the site of the operation.

 The invention proposes to replace the sparrow pump or equivalent by a projection device, one of the elements of which uses the principle of the hydraulic jet pump.

 The principle of the hydraulic jet pump, well known in the prior art, consists in injecting a working fluid by an injector included and directed in the same longitudinal axis of a pipeline. The speed of the working fluid, provided by an auxiliary pumping, causes suction on one side of the pipe and on the other side a discharge by phenomenon of drive by the working fluid.

 In the present invention, compressed air is advantageously used as the working fluid and the injector is not included in the axis of the tube in communication with the mixture, but consists of an annular injection to said tube. The tube and the air injection open into a discharge or ejection conduit which itself communicates with the outlet orifice.

 It is not going beyond the scope of this invention to use a fluid other than air.

 Thus, the mixture does not encounter any obstacle in the conduits and the projection power is obtained and controlled by the flow of injected fluid which directly influences the speed of suction and delivery.

 To avoid jamming and the constitution of mixing caps upstream of the suction tube, the invention adds a system of blades at the outlet of the feed hopper in order to disaggregate the transported mixture and to promote its suction. Any other system of function equivalent to a cleaning of the materials could be used within the framework of this invention.

 The present invention therefore provides a machine for spraying a mixture comprising a feed tank, a feed hopper at the bottom of the tank, said hopper optionally feeding a forcing corridor disposed upstream of a projection device and a projection.

 The projection device comprises a means for cleaning said mixture, at least one means for injecting compressed gas such as air, a chamber and an ejection orifice cooperating with said projection pipe.

 The means for cleaning the mixture can comprise at least two propeller blades with reverse pitch and said chamber can be located at a level lower than said decompression means.

 The device may comprise a tube connecting said chamber and an ejection conduit, said conduit opening through said orifice, a means for injecting compressed gas opening into said conduit and adapted to both cause suction of said mixture and to repressing said mixture through said orifice.

 The means for injecting compressed gas may comprise at least one conduit disposed at the periphery of said tube.

 In the device, another means for injecting compressed gas may comprise an injection nozzle opening into said chamber, the diameter of said nozzle may be adjustable, the distance of penetration of the nozzle into the chamber may be adjustable and the longitudinal axis of said nozzle and the longitudinal axis of said tube can be combined.

 The device of the invention may include said two means for injecting compressed gas.

 The invention also relates to a machine for spraying a mixture containing solid products of various particle sizes such as natural aggregates or of industrial origin and a water content of less than 15% by total dry weight and comprising a device for ejecting said mixture, said device being activated by at least one injection of a pressurized fluid and said device being supplied with a mixture by kneading and transport means.

The invention also provides a method of projecting a mixture comprising the following steps:
a mixture is prepared comprising solid products of varied particle size and a water content at most equal to 15% of the total dry weight and possibly substantially dry,
- this mixture is continuously stirred and conveyed to the input of a projection device,
- Compressed gas such as air is injected into said device and said mixture is projected outside of said device.

 Said mixture may include aggregates such as sand, earth, gravel, any powdery products of natural origin or products of industrial origin, expanded or not, and the maximum particle size of which is of an order of centimeter.

 The method according to the invention can advantageously be applied to the manufacture by projection of embankments for access and / or protection against fires, to the extinction of fires of all origins, in particular of combustible liquids by projection of an extinguishing mixture. and the remote containment of polluting waste, in particular radioactive waste, by spraying a suitable mixture.

The present invention will be better understood and its advantages will appear more clearly on the following description of a nonlimiting example illustrated by the appended figures, among which:
FIG. 1 is a schematic view in cross section of a spraying machine according to the invention,
FIG. 2 is a schematic view thereof in vertical axial section along the line II-II,
FIG. 3 is a more detailed view of the ejection device,
- Figure 4 is a schematic top view of the spraying machine.

 The spraying machine shown by way of example in FIGS. 1 to 4 is of constitution substantially identical to the machine relating to patent FR-2598349, apart from the pumping part which has been replaced in the present invention by a projection system in particular pneumatic.

 The entire machine is carried by a support 1 produced at the road gauge and resting on a running gear 2 at the same gauge, a part of which is only shown in FIG. 1. The machine is provided with members 3 for fixing to the chassis 1 and structural reinforcements for securing 3A between the tank and the airlock.

 The spraying machine comprises a main body comprising the projection device, around which are arranged accessory elements.

 An external mixing complex is placed next to the main body of the machine and is used to prepare and dose the mixture.

This complex is broken down into a kneader casing 4 made of thick sheet steel of semi-tubular shape open upwards and in which a kneader 5 with a horizontal axis rotates driven by a hydraulic motor 13 supplied with energy by an assembly 14 containing a central hydraulic pump driven by a heat engine not shown. This power plant also supplies energy to the other hydraulic motors 13 of the other moving parts and includes a distribution and regulation system.

 Above the opening of the mixer is disposed a tilting screen 6 for screening and calibrating the various aggregates intended for compounding the mixture. This sieve, with meshes determined as a function of the maximum particle size of the granular products included in the mixture, can be mechanically vibrated if the required flow rates are high.

 A horizontal articulation 7 ensures a connection between the mixer and the main body of the machine and allows the tilting of the mixer (pushed by a hydraulic cylinder not shown) for the purpose of feeding the machine; in general the sieve is tilted beforehand on the side of the mixer casing (see arrows) in order to release the flow of the mixture towards the feed tank of the main body of the machine.

 After this feeding phase, the mixer then the sieve return to their initial positions in order to allow the preparation of a new batch during the projection of the batch which has just been poured into the main body.

 It is not going beyond the scope of this invention if an external and large capacity preparation system replaces the mixer 4 and feeds, in particular by conveyor belt, the feed tank or the hopper or even directly the projection device in a way keep on going.

 The main body comprises a supply tank 8, the envelope of which, for example made of steel, is shaped as close as possible to the scanning volumes of the various moving parts. To completely delimit these sweeping volumes, the sides 8B of the tank are adjusted as close as possible to the scanning area of the blades, as shown in FIG. 4. This tank preferably comprises a side hatch 8A for visiting and emptying the feed tank, intended in particular to facilitate cleaning of the tank after use. Inside the tank and sweeping the entire interior space is a battery of at least two counter-rotating mixers with horizontal and parallel axes 9 and blades 10 whose scanning areas are nested.

 Below this mixer battery is placed a feed hopper 1 1 with truncated, flat or spiraled blades (possibly the hopper may include an endless screw) housed substantially two-thirds in a semi-tubular steel sheet sheath 12 forming an integral part of the envelope of the supply tank, and constituting with it the main body of the machine. This sheath has at its lower part a drain flap 12A intended for cleaning the hopper.

The sweeping area of the hopper 11 will be placed in the vicinity closest to the scanning area of the blades 10 of the horizontal mixer battery, leaving just the free space necessary to avoid blockage by gravel.

 In the direct extension of this semi-tubular sheath 12 is placed, projecting from the main body of the machine, an airlock 15 in the form of a fully tubular sheath enveloping in its entirety the sweeping area of the hopper 1 1 which will be extended the length of the sheath.

This reinforced sheet sheath and the extension of the hopper jointly form a forced supply duct for the projection device 16.

 Without departing from the scope of this invention, it will not be possible to use a forcing corridor as described since this may present, for certain mixing, the disadvantage of compacting the mixture too strongly.

 On the other hand, it is necessary that the supply channel of the device is practically obstructed so that the injected gas does not preferentially escape towards this channel, which pushes the mixture from the wrong side. Other means of obstruction can be used.

 This airlock also includes mobile inspection doors of the hood type with high, low or lateral openings in order to ensure the possibility of unclogging and decompression of the duct by simple direct cleaning, this in the event of the formation of a plug. at the entrance of the projection device 16.

The projection device 16 is fixed to the forcing conduit by bolts 17. The shaft of the hopper 11 extends into the ejection device and is held there by a rolling bearing 18. On the part of the shaft included in the projection device 16, is fixed at least two propeller blades 19 in reverse pitch in order to provide an undercut or a cleaning on the mixture rod leaving the forcing corridor. Indeed, it is important to disaggregate the mixture so that it can be sucked efficiently and regularly by the ejection system. It will not depart from the scope of this invention if at the end of the forcing corridor or the main hopper, another system for cleaning the mixture before its ejection is used. It could for example be a rotary system independently driven by another hydraulic motor
The racked and disintegrated mixture falls by gravity into a chamber 20 located at a level below said racking means and preferably vertically. At the lower part of this chamber 20, a tube 21 constitutes the suction pipe for the mixture. This tube opens into an ejection conduit 22. In this conduit 22 also opens an injection conduit 23 of compressed air. The speed of the air in the conduit 22 provides a suction of the mixture contained in the chamber 20 through the channel of the tube 21. The air injection conduit is preferably produced by a tube 24 coaxial with the tube 21 together delimiting a conduit annular 23. In the context of this same invention, the air injection can be done by one or more tubular conduits arranged at the outer periphery of the tube 21 and opening into the conduit 22, also these conduits can lead into different sections from tube 21 ..

 The conduit 22 opens out through an orifice 25, which cooperates with a rigid tube of the cannon type, or a flexible pipe possibly connected to a spray lance.

 In Figure 3 is shown in more detail the lower part of the chamber comprising the tube and the air injection means at the level of this tube and a second air injection means 26. This second injection means can facilitate both the cleaning and disintegration of the mixture and the aspiration of the same mixture by the tube 21 by pushing the mixture towards the inlet of the tube.

 The shape of the bottom of the chamber is adapted so that the mixture which falls by gravity naturally occurs directly at the inlet of the tube 21 without providing dead spaces where the heavier granular products could statically accumulate.

 In FIG. 3, the second air injection means 26 comprises at the end of a tube 30 an interchangeable nozzle 28 allowing the modification of the shape and the power of the air jet and also the possible repair.

 The tube 30 is connected to a source of compressed air by a hose 31 and is held on the wall of the chamber 20 by means 29 providing a seal while allowing axial movement of the tube 30 to effect an adjustment of the distance between the nozzle 28 and the inlet of the tube 21.

Once the adjustment has been made, the means 29 fixes the position of the tube 30.

 The annular injection pipe 23 is delimited by the outside of the tube 21 and by a coaxial tube 24. The tube 24 has at least one orifice 32 connected to a source of compressed air.

 The end 27 of the tube 21 cooperates with an internal shape 27A of the tube 24 in order to delimit the passage section from the injection of air used to the ejection of the mixture. The tube 24 can move longitudinally relative to the tube 21 to modify the passage section between the two elements 27 and 27A. Means 33 and 34 respectively on the tube 21 and on the pipe 22 allow this longitudinal adjustment and provide the necessary seals.

 The conduit 22 in which the mixture moves and the compressed engine air emerges through the orifice 25 towards projection pipes.

 It will not depart from the scope of this invention if the spraying machine comprises only one or the other of the means for injecting compressed air, or the two assemblies as shown in FIG. 3.

 Concerning the mixing, the invention makes it possible to be able to spray mixes which are not very wet and even practically dry. Granular products can be very varied in their size, shape and nature. It can be conventional aggregates used in civil engineering such as gravel, sand, earth, crushed residues or even industrial products such as expanded clays or industrial residues. We can also spray active products such as detergents, flocculants, absorbents, etc ...

 The applications of this method of projection and of a spraying machine are multiple in particular when there is a need to be set back from the destination of the mixture, for example to treat an accidental spreading, to treat fires of all types in particular combustible liquids or confine polluting products such as radioactive waste.

 This machine and this method also make it possible to prepare an access to a dangerous site which cannot be approached, for example because of radioactive or thermal radiation.

 The gas flow rates injected will be variable depending in particular on the nature and the water content of the mixture and the projection distance to be reached.

 The flow rates can preferably be between 5 and 30 m3 / minute, without this range being limiting.

Claims (10)

 I - Machine for spraying a mixture comprising a feed tank (8), a feed hopper (11) at the bottom of the tank, said hopper possibly feeding a forcing corridor (15) disposed upstream of a projection (16), characterized in that the projection device (16) comprises a means for cleaning (19) of said mixture, at least one means for injecting (23, 26) of compressed gas such as air, a chamber (20) and an ejection orifice (25).  2 - Machine according to claim 1, characterized in that the cleaning means (19) of the mixture comprises at least two propeller blades with reverse pitch and in that said chamber (20) is located at a level below said means of cleaning.  3 - Machine according to one of the preceding claims, characterized in that said device comprises a tube (21) putting said chamber (20) into communication with an ejection duct (22), said duct (22) opening out through said orifice ( 25), an injection means (23) of compressed gas opening into said conduit (22) and adapted to both cause suction of said mixture and to discharge said mixture through said orifice (25).  4 - Machine according to claim 3, characterized in that said injection means (23) of compressed gas comprises at least one conduit disposed at the periphery of said tube (21).  5 - Machine according to one of claims 1 or 2, characterized in that another injection means (26) of compressed gas from said device comprises an injection nozzle (28) opening into said chamber, in that the diameter of said nozzle is adjustable, in that the penetration distance of the nozzle in the chamber (20) is adjustable and in that the longitudinal axis of said nozzle and the longitudinal axis of said tube (21) are combined.  6 - Machine according to one of the preceding claims, characterized in that the device comprises two injection systems (23, 28) of gas.  7 - Machine for spraying a mixture containing solid products of various particle sizes such as natural aggregates or of industrial origin and a water content of less than 15% by total dry weight, characterized in that it comprises an ejection device ( 16) of said mixture. said device being activated by at least one injection (23, 28) of a pressurized fluid and said device (16) being supplied with mixture by kneading (8, 19) and transport (11, 15) means.  8 - Method of projecting a mixture, characterized in that it comprises the following stages:  a mixture is prepared comprising solid products of various particle sizes, a water content at most equal to 15% of the total dry weight and possibly substantially dry,  - this mixture is continuously brewed and conveyed to the entry of a projection device,  - Compressed gas, such as air, is injected into said device and said mixture is projected outside of said device.  9 - Method according to claim 8, characterized in that said mixture comprises aggregates such as sand, earth, gravel, all pulverulent products of natural origin or products of industrial origin expanded or not, and whose maximum particle size is of order of centimetric size.  10 - Application of the method according to one of claims 8 to 9 to the manufacture by projection of embankments of access and / or protection against fires, to the extinction of fires of all origins in particular of combustible liquids by projection of an extinguisher mixture and the remote containment of polluting waste, in particular radioactive waste, by spraying a suitable mixture.