EP2181888A1

EP2181888A1 - Suction apparatus for suctioning combustible material

Info

Publication number: EP2181888A1
Application number: EP08425692A
Authority: EP
Inventors: Luigi Cappellotto; Nicola Da Riol; Michele Cescon
Original assignee: Cappellotto SpA
Current assignee: Cappellotto SpA
Priority date: 2008-10-28
Filing date: 2008-10-28
Publication date: 2010-05-05

Abstract

A suction apparatus (10) for suctioning a combustible material, potentially at risk of fire and/or explosion. The apparatus comprises a suction path (23) extending between an inlet mouth (26) of a mixture of air and of said combustible material, and an outlet mouth (28), said mixture forming, at least in one given section (15, 17, 22, 45) of said suction path (23), an atmosphere comprising a concentration of oxygen and a concentration of said combustible material.

The apparatus (10) further comprises, in communication with said at least one section of said suction path (23), at least one first oxygen detection device (47, 52) apt to detect oxygen concentration in said atmosphere, at least one first combustible material detection device (40, 44) apt to detect the concentration of said combustible material in said atmosphere, at least one pressure detection device (48) and at least one modifier device (41, 60, 61, 62, 63, 64, 72) of said atmosphere. The modifier device is operatively connected to said first oxygen detection device (47, 52), to said first combustible material detection device (40, 44) and to said pressure detection device (48) for modifying said atmosphere when said oxygen concentration and said concentration of combustible material are in a determined relationship with respective reference concentrations.

Description

The present disclosure relates, in its most general aspect, to the field of apparatuses operating with dangerous materials, or substances, potentially at risk of explosion and/or fire, and more specifically to a suction apparatus for suctioning combustible material (for example, in the form of gas, vapours, mists, sprays, dusts), wherein said material is suctioned from a zone, or environment, to be decontaminated.
Within the scope of the present disclosure, by the expression "combustible material" it is meant any one substance in a gaseous, nebulised, liquid or solid form, like for example a dust, which in the presence of oxygen (O₂) and/or of other comburent, as well as of a heat source or an initiator (for example, a spark), is susceptible of giving rise to flame or explosion.
In fact, conditions required in order to have combustion, are the presence of a combustible material, a comburent and an initiator source. Initiator sources can be high-temperature surfaces, sparks of mechanical origin, sparks of electrical origin, electric arcs, electromagnetic fields.
In the field of apparatuses processing, and in particular suctioning, combustible material potentially at risk of explosion and/or fire, very strict standards are in force which define a given degree of dangerousness of the zone to be decontaminated on the basis of the combustible material suctioned from said apparatuses and, depending on said degree of dangerousness, set up for each apparatus certain compliance measures such as to make the apparatuses compatible with the established degree of dangerousness.
In general, standards require the setting up of measures such that said apparatuses do not generate dangerous situations in the work and/or decontamination zone, i.e., that there be no risk of generating a flame initiation.
Evidently, the need has arisen to set up suction apparatuses for suctioning combustible material potentially at risk of explosion and/or fire, which can operate under such dangerous conditions.
A way to proceed to meet said need is to provide a series of expedients of the suction apparatus, minimizing the risk of flame initiation.
Such expedients comprise, for example, a suitable selection of materials of the apparatus, such as to reduce generation of initiations and also having a certain resistance to fire, the use of adequate electric systems, the provision of a system of flame outlets, a maintenance program for the apparatus, and optionally a certain list of behaviour rules apt to prevent the onset of a fire.
Further expedients are, for example, the provision of a system for the automatic detection of fires, an emergency plan, an automatic extinguishing system, a smoke and heat evacuation system, the presence of fire extinguishers, and optionally a fire-fighting water system.
This way to proceed, though advantageous under a plurality of standpoints, entails some drawbacks.
A drawback lies in the fact that the above-mentioned expedients proved insufficient to effectively prevent a fire and/or an explosion under all dangerous situations. In other words, the above-mentioned way to proceed does not always prevent an initiation of fire and/or explosion.
Therefore, in line with said standards, a known suction apparatus has limited usefulness if dangerous zones are characterised by a high degree of risk of fire and/or explosion.
A technical problem underlying the present disclosure lies in providing a suction apparatus for suctioning combustible material potentially at risk of fire and/or explosion, overcoming said drawback, or at least providing further advantages.
Said technical problem is solved by a suction apparatus for suctioning a combustible material, potentially at risk of fire and/or explosion, said apparatus comprising a suction path, extending between an inlet mouth for a mixture of air and of said combustible material, and an outlet mouth, said mixture forming, at least in one given section of said suction path, an atmosphere comprising a concentration of oxygen and a concentration of said combustible material, said apparatus further comprising, in communication with at least one section of the suction path, at least one oxygen detection device, apt to detect oxygen concentration in said atmosphere, a combustible material detection device, apt to detect the concentration of said combustible material in said atmosphere, at least one device for detecting the pressure of said atmosphere, and at least one modifier device of said atmosphere, said at least one modifier device being operatively connected to said oxygen detection device, to said combustible material detection device and to said pressure detection device, and being apt to modify said atmosphere when said oxygen concentration and said combustible material concentration are in a determined relationship with respective reference concentrations.
Said reference concentrations for the combustible material and for oxygen are also referred to as flammability limits, defining a so-called flammability range; i.e., they are the maximum and minimum concentrations of a combustible material and of oxygen at a certain pressure (and at a certain temperature), at which a flame or a fire occur.
In particular, oxygen concentration and the concentration of a combustible material, for example, measure in mass per volume unit, below which an atmosphere is not explosive and/or flammable, are referred to as LEL concentrations, whereas the oxygen concentration and the concentration of a combustible material above which the atmosphere is not explosive and/or flammable are referred to as UEL concentrations.
The above-mentioned three detection devices can be three distinct members, or even be incorporated in a single member capable of detecting both concentrations, and pressure.
Secondary features of the apparatus according to the present disclosure are defined in the corresponding dependent claims thereof.
The above-mentioned technical problem is also solved by a motor vehicle including a suction apparatus according to claim 18, and by a process for suctioning a combustible material, according to claim 19, and following dependent claims.
The present suction apparatus provides several relevant advantages.
A first advantage of the present disclosure lies in making available a suction apparatus, in which at least one section of the suction path can be continuously and actively controlled in order to avoid the danger of fires or explosions during the suctioning steps. Thus, it is guaranteed that no hazardous situation is generated in the apparatus.
In fact, it has been noticed that a dangerous situation is generated not so much outside of the suction apparatus, but above all in an environment internal to the suction apparatus, where combustible material and oxygen are more concentrated and therefore there is a greater risk that relative concentrations fall within said certain flammability limits, and that there be initiations.
In other words, an advantage of the above-mentioned apparatus lies in that the atmosphere in all internal sections of the suction path, which come into contact with the mixture of air and combustible material, can be actively controlled, so as to always guarantee a condition of non-flammability of the mixture inside the apparatus.
Such an apparatus can operate in a zone at high risk of fire.
A further advantage lies in that the constant and active control allows to safeguard from fires any personnel working in close contact with the suction apparatus.
Moreover, the presence of a pressure detection device, an oxygen concentration detection device and a combustible material concentration detection device, set in communication with the suction path, entails the advantage that active control does not necessarily occur at suction, but also subsequently thereto, for example, during a possible carriage of the apparatus or during a post-suction unloading of the combustible material from the apparatus.
A further advantage of the suction apparatus in accordance to this embodiment lies in that the presence of a pressure detection device allows to detect also any suction anomaly of the suction apparatus, for example any obstruction, or pressure rise in the suction path. In fact, in case of overpressure, it has been noticed that a variation of the flammability range may occur, in particular a widening of the flammability range, and therefore a greater risk of fire and/or explosion.
In an embodiment, the suction apparatus comprises a collecting tank set along the suction path, intended to at least partially contain said suctioned combustible material. The oxygen concentration detection device, the combustible material concentration detection device and the pressure detection device are set at least in communication with said collecting tank, in order to detect the concentrations of oxygen and of combustible material in the collecting tank, therefore to check whether any danger situations, generated in the collecting tank, are occurring in the apparatus.
In another embodiment, the suction apparatus comprises a filtration device, set along the suction path between said collecting tank and a suction unit, for retaining any combustible material leaking from the collecting tank. The oxygen (concentration) detection device, the combustible material (concentration) detection device and the pressure detection device are further set in communication with at least said filtration device, therefore for checking whether any danger situations, generated in the filtration device, are occurring in the apparatus.
An advantage of these latter embodiments lies in that, if present, said collecting tank, and/or said filtration device are actively and continuously controlled.
Preferably, the suction apparatus is set aboard a motor vehicle, so as to allow easy displacement before and after the suctioning steps.
An advantage of this embodiment lies in that, as mentioned above, also in carriage, the atmosphere inside the suction path can be controlled at all times, so as to ensure a safety of the suction apparatus at any instant and in any one zone where the suction apparatus is transported. There follows that a carriage of the suction apparatus through a high-density dwelling zone entails no danger whatsoever to people.
In other words, carriage of suctioned combustible material takes place safely and in compliance with ADR (Accord Dangereuses par Route - European agreement on the international carriage of dangerous goods on road) standards regulating the carriage of dangerous goods on road.
In addition, also the unloading of such suctioned combustible material can take place in full safety, the atmosphere internal to the apparatus being constantly monitored.
In an embodiment, the suction apparatus comprises a plurality of modifier devices of said atmosphere, each apt to be operated depending on detected concentration values, and on the above-mentioned relationship with the respective reference values. The advantage of having a plurality of modifiers lies just in the option of setting up a schedule of targeted modification depending on the extent of the fire danger.
In fact, if concentration values lie in a boundary zone between flammability range and non-flammability range, it suffices to slightly modify the atmosphere in the suction path by operating one of said modifiers, so as to bring such concentration values into the non-flammability range.
If, instead, concentration values are amply contained within the flammability range, it is necessary to substantially modify the atmosphere in the suction path in order to exit said field, optionally by using plural atmosphere modifiers.
In an embodiment, a first one of said modifiers comprises an actuator member operatively connected, on the one side, to the oxygen detection device, to the combustible material detection device and to the pressure detection device, and on the other side to a suction unit, in order to operate the suction unit depending on the detected concentrations of oxygen and combustible material.
In particular, if detected concentration values are close to or fall within the flammability range, i.e., detected concentration values are next to match, for example, LEL values or be greater than the latter, the suction unit is operated so as to increase vacuum, i.e. suction power, thereby causing a decrease of the pressure of said atmosphere in the suction path.
In fact, it has been noticed that a vacuum increase in the suction path causes a reduction of the amount of oxygen in the mixture, such as to cause in some cases a departure of the oxygen concentration from the reference or LEL concentration.
In addition, by decreasing the pressure inside of the suction path a more rarefied atmosphere is obtained, such as to decrease a risk of collision and reaction between molecules of oxygen and of combustible material, and therefore a variation of the flammability range.
For this reason, preferably the oxygen detection device and the combustible material detection device are recalibrated depending on the actual pressure in the suction path, in order to modify reference concentration values, i.e., the minimum and maximum flammability limits of combustible material and oxygen depending on the actual pressure in the suction path.
An advantage of this embodiment of the above-defined apparatus lies in that by increasing the vacuum, and therefore the extent of suction of the dangerous material, it is checked in real time whether oxygen and combustible material concentration values fall within the flammability range.
Moreover, a modification of the atmosphere in the suction path does not affect the suction operation of the apparatus; in other words, the monitoring of flame and/or explosion risk does not affect the suction yield of the apparatus. In fact, the suction apparatus continues suctioning, in fact with a suction increase, and concomitantly it is made safe.
Preferably, the suction apparatus is configured so as to provide at least one sequence of two adjustments of the degree of vacuum. In other words, the above-mentioned actuator is prearranged for progressively or gradually adjusting the operation of the suction unit, depending on the detected oxygen and combustible material concentration values.
In an embodiment, to further modify the atmosphere in the suction path, the suction apparatus comprises at least one second atmosphere modifier comprising a device for introducing inert gas.
Said device for introducing inert gas preferably comprises an inert gas storage container, set in communication with the suction path. The inert gas is intended to be inlet from the storage container into the suction path to cause a dilution of the concentrations of oxygen and combustible material. This second modifier is particularly useful if the increase in the extent of the vacuum is not sufficient for atmosphere modification and making the suction apparatus safe.
In an embodiment, the inert gas storage container is fed by an inert gas generator set aboard the suction apparatus, and/or the above-mentioned motor vehicle.
In an alternative embodiment, the inert gas storage container is fed by an inert gas generator, which is set in an area external with respect to the suction apparatus, and/or to the above-mentioned motor vehicle, and that, in case of need, is connected to the inert gas storage container. Therefore, it is an independent generator.
Furthermore, in an embodiment, the suction apparatus lacks the inert gas storage container and the inert gas generator is set directly in fluid connection (for example, by a piping) with said suction path.
Furthermore, in another embodiment, the suction apparatus comprises at least one third atmosphere modifier, comprising at least one inlet port or opening for external air, usually kept closed by a closure or intercept member, said opening being such as to set in communication the suction path with an environment external to the suction apparatus. The inlet port is sized and connected to the suction path in a manner such that, by opening said intercept member, only environment-air be suctioned from said inlet port, making substantially nil the suction of combustible material at the inlet mouth.
In other words, into the suction path environment-air is inlet which replaces the above-mentioned combustible mixture, diluting the combustible substance already present in the apparatus, thereby making the apparatus totally safe from the risk of fire and/or explosion.
This third modifier is apt to be operated if the above-mentioned dilution by inert gas is not sufficient to exit the flammability range, and guarantees dilution of explosive atmosphere concentration.
Preferably, the external air inlet port comprises an inlet piping. Even more preferably, in order to reduce piping and connections with the suction path, if said inert gas container is present, the latter is set in fluid communication with the suction path by a secondary piping, which fits into said inlet piping, provided it also with a suitable on-off valve.
Further advantages and features of the suction apparatus according to the present disclosure will be evident to those skilled in the art from the following detailed and non-limiting description of an embodiment thereof.
However, it is evident how each embodiment of the present disclosure may entail one or more of the advantages listed above; in any case, it is not however required for each embodiment to concomitantly entail all of the advantages listed.
Reference will be made to the figures of the annexed drawings, wherein:

Figure 1 shows a view of a motor vehicle associated to a suction apparatus according to the present disclosure;
Figure 2 schematically shows a side view of a suction apparatus such as that of Figure 1, in a first operative condition thereof;
Figure 3 schematically shows another view of the suction apparatus of Figure 2;
Figures 4a, 4b, 4c show a detail of a suction unit of the suction apparatus of Figure 2 in subsequent operation steps thereof;
Figure 5 schematically shows a side view of the suction apparatus of Figure 2, in a second operative condition thereof;
Figure 6 schematically shows a side view of the suction apparatus of Figure2, in a third operative condition thereof;
Figure 7 schematically shows a side view of the suction apparatus of Figure 2, in a fourth operative condition thereof.

Referring to the attached figures, by reference number 10 it is denoted a suction apparatus according to the present disclosure. The suction apparatus 10 is intended for suctioning combustible material, for example hydrocarbons, for example petrol-based, potentially at risk of fire and/or explosion.
In the example, the suction apparatus 10 is mounted aboard a motor vehicle denoted by reference number 11, said motor vehicle 11 comprising, conventionally as main parts, a tractor 12, an engine, not illustrated in the drawings, and a supporting platform 13 onto which the suction apparatus 10 is set.
More specifically, in the example, the suction apparatus 10 comprises a suction pipe 15, a collecting tank 17 or reservoir, a filtration device 22, and a suction unit 19, in the example a pump. All these members form in the suction apparatus 10 a suction path 23, denoted in an exemplary and non-limiting manner by a broken line in Figures 2, 6 and 7, having a travelling direction that goes from the suction pipe 15 to the suction unit 19. With respect to the above-mentioned suction path 23, which is directed left-to-right in the figure as denoted by arrows, an upstream position and a downstream position are singled out in the apparatus. Any reference to "upstream" and "downstream" positions in the present disclosure is to be understood as specified above with reference to the travelling direction in the above-mentioned suction path 23.
In the example, the suction unit 19 is operated by the same engine of the motor vehicle 11, and therefore the suction power depends on the number of revolutions (rpm) of the engine of the motor vehicle 11.
In particular, the suction path 23 extends between an inlet mouth 26, obtained in correspondence of a free end 27 at the mouth of the suction pipe 15, and an outlet mouth 28 downstream of the suction unit 19. Practically, at the inlet mouth 26 a certain mixture of air and combustible material is introduced. Then, from the inlet mouth 26 for each section of the suction path 23, it is obtained an atmosphere of certain pressure comprising said mixture of combustible material and oxygen (besides, obviously, other air-contained inert gases, such as Nitrogen and other gases in lesser concentrations).
The collecting tank 17 is connected downstream with the filtration device 22 by a first connection pipe 30, and a second connection pipe 31.
In particular, the first connection pipe 30 connects the collecting tank 17 respectively with a bottom region (portion) 35 of the filtration device 22, whereas the second connection pipe 31 connects the collecting tank 17 with a median region 37 of the filtration device 22.
The suction apparatus 10 further comprises a first intercepting or on/off valve 32 set along the suction path 23 on the suction pipe 15, a second on/off valve 38 which is set on the first connection pipe 30, and a third on/off valve 39, which is set on the second connection pipe 31.
In the present instance, the suction path 23 extends into the connection pipe 31.
The first connection pipe 30 is intended for a recovery of combustible material from the filtration device 22, as it will be better described hereinafter, with reference to Figure 7.
The suction apparatus 10 comprises, in communication with the suction path 23, at least a first oxygen detection device 47 for detecting oxygen concentration in the atmosphere, a first combustible material detection device 40 for detecting the concentration of combustible material in the atmosphere, and a pressure detection device or meter, denoted by reference number 48, for monitoring the pressure into the suction path 23.
In the example, the first combustible material detection device 40 is a so-called LEL detector, i.e., a detector apt to concomitantly detect a plurality of preset combustible/flammable substances, which can display in-air concentration of such gases already on a LEL scale or as percent by volume.
For instance, as mentioned hereto, such gases include petroliferous products, solvents, alcohols, etc. In other words, in this embodiment, the first combustible material detection device 40 is manufactured in a single body, including, in one piece, four sensors. Such a first combustible material detection device 40 is of infrared (IR) type, i.e., it is apt to detect the concentration of such gases by evaluation of absorption at certain IR wavelengths.
As to the first oxygen detection device 47 and first combustible material detection device 40, it has to be pointed out that both are selected so as to operate even at very low pressures and be calibrated even for high vacuum values.
More specifically, the first combustible material detection device 40, the first oxygen detection device 47, and the pressure detection device 48 are set in communication with the collecting tank 17 by means of a first connecting duct 42, equipped with a related self-calibration valve 42a, and with the filtration device 22 by means of a second connecting duct 43. Practically, first combustible material detection device 40, first oxygen detection device 47, and pressure detection device 48 are set in communication with a plurality of sections of the suction path 23.
In particular, the self-calibration valve 42a is intended to be closed, if need be, for a calibration of the detection devices 40, 47, 48 as it will be described hereinafter, whereas the second connecting duct 43 has also the function of guaranteeing a fluid circuit inside the suction apparatus 10, and of preventing any erroneous measuring therein due to load losses.
The first combustible material detection device 40, the first oxygen detection device 47, and the pressure detection device 48 are connected with an electronic control circuit 50 for controlling electric signals coming from the detection devices 40, 47, 48, which in turn is connected with a control unit 41, in the example a computer or alike processor set on the tractor 12 of the motor vehicle 11.
To ensure certain detection with minimal errors, the suction apparatus 10 comprises a second combustible material detection device 44, it also comprised of a so-called LEL multigas detector, like the first combustible material detection device 40. The second detection device 44 is of thermal type, i.e., is capable of detecting the concentration of oxygen and of combustible material from thermal conductivity measuring.
The use of said second combustible material detection device 44 is for safety purposes, and allows to control the concentration values detected by the first combustible material detection device 40, and have a certainty of the detected concentration values.
Also this additional combustible material detection device 44 is connected to the control unit 41 by means of the electronic circuit 50, and, like the first combustible material detection device 40, is set in communication with the collecting tank 17, by means of said first connecting duct 42 equipped with a related cyclic self-calibration valve 42a, and with the filtration device 22, by means of said second connecting duct 43. Practically, also the second combustible material detection device 44 is set in communication with a plurality of sections of the suction path 23.
The suction apparatus 10 comprises a plurality of atmosphere modifiers, described hereinafter, which are intended to be activated on the basis of the detected concentration measuring of oxygen and combustible material.
A first modifier comprises the control unit 41, serving as actuator, and operatively connects the first combustible material detection device 40, the first oxygen detection device 47, and the pressure detection device 48 to the suction unit 19. The connection with the control unit 41 is indicated in a wholly schematic manner in Figures 2, 5, 6 and 7 by a continuous line provided with a double arrowhead, said connection being of electric/electronic type, or optionally wireless by respective radio wave receivers/transmitters.
In particular, the control unit 41 is configured for adjusting the actuation of the suction unit 19.
Essentially, on the basis of the detected oxygen concentration and combustible material concentration, therefore on the basis of LEL values, the central control unit 41 acts on the operating power of the suction pump, increasing the suction power and causing a greater degree of vacuum in the suction path 23.
As it will be observed in greater detail below, as the first combustible material detection device 40 and the first oxygen detection device 47 detect that the atmosphere in the suction path 23 falls within LEL limits or is close thereto, the suction power of the suction unit 19 is increased in order to decrease atmosphere pressure in the suction path 23, and make the atmosphere more rarefied.
Therefore, it is attained a modification of the atmosphere in the suction path 23, which, as it has been noticed, causes a decrease in oxygen concentration.
Under such conditions, the first combustible material detection device 40 and the first oxygen detection device 47 are suitably recalibrated to re-establish new LEL limits consistent with the new pressure detected in the suction path 23. In fact, generally, the flammability range restricts with a pressure decrease, thereby reducing the risk of flame.
Moreover, to the above-mentioned electronic circuit 50 it is operatively connected a second oxygen detection device 52, which is set on a connecting duct 46 connecting a pipe piece 45 that lies interposed between the filtration device 22 and the suction unit 19. In practice, on the pipe piece 45 there takes place only a monitoring of the concentration of oxygen, and not of combustible material; in the example, such a monitoring suffices in said zone of the suction path 23 lying downstream of the filtration device 22.
More specifically, it has been noticed that if the combustible material is of solid and/or liquid type, no combustible material is found in the pipe piece 45 and therefore its detection is unnecessary, whereas if the combustible material is of gaseous type and the latter is suctioned along with air into the pipe piece 45, in the apparatus of the example the detection of concentration of gaseous combustible material is irrelevant, sufficing it to guarantee that oxygen concentration be sufficiently low.
On the connecting duct 46 a cyclic self-calibration valve 56 is positioned which, like the above-mentioned cyclic self-calibration valve 42a and as it will be explained below, is suitably closed when it is necessary to calibrate the detection devices 40, 44, 47 and 48.
The suction apparatus 10 comprises a second atmosphere modifier, which comprises an inert gas introduction device, generally denoted by reference number 62, for example of Nitrogen or of carbon dioxide, or of other inert gas, i.e., a gas that is inert with respect to a possible combustion between oxygen and suctioned combustible material.
The inert gas introduction device 62 comprises an inlet duct 63, equipped with a first on-off valve 67, connected to a piping 64 having an upturned U-shape and equipped with a second on-off valve 68, fitting from the top into the collecting tank 17, for introducing inert gas into the suction path 23.
To have available a reserve of inert gas, the inert gas introduction device 62 also comprises a pair of inert gas containers 60, 61, set on the sides of the collecting tank 17 and set in communication with the collecting tank 17 by means of two shunts 65, 66, each set on a side of the inlet duct 63, which fit into the pipe 64.
Each inert gas container 60, 61 is loaded beforehand with carbon dioxide or Nitrogen, or other inert gas, collected from an inert gas generator not depicted in the drawings, and let in through the inlet duct 63, and the shunts 65, 66. During said preventive loading, the second on-off valve 68 is kept suitably closed.
On the contrary, in order to introduce inert gas into the collecting tank 17, the first on-off valve 67 is closed and the second on-off valve 68 is opened so as to convey inert gas from the containers 60, 61 into the collecting tank 17, as it will be more clearly described with reference to Figure 6 hereinafter.
Said first and second on-off valves 67, 68 are operatively connected with the control unit 41, to be operated thereby if need be.
Preferably, the inert gas storage containers 60, 61 are fed by an inert gas generator set aboard the above-mentioned motor vehicle 11.
In an alternative embodiment, the inert gas storage container 60, 61 is fed by an independent inert gas generator which is set on an area external to the suction apparatus 10, and/or to the above-mentioned motor vehicle 11, and which is connected to the inert gas storage containers 60, 61 if need be.
Moreover, in the illustrated example it may be seen that one of the two inert gas containers, in the example the container 60, is connected by a duct 70, provided with an on-off valve 71, to the first connection pipe 30, which as mentioned above connects the collecting tank 17 with the bottom region 35 of the filtration device 22, and in particular with an elbow section 30a of the connection pipe 30.
The suction apparatus 10 further comprises a third atmosphere modifier, which comprises at least one inlet port 72 set in communication with the suction path 23 and that sets in communication the suction path 23 with the environment external to the suction apparatus 10. More specifically, in the example, the port comprises an inlet piping 72, which fits vertically into the above-mentioned piping 64 and is closed by an on-off valve 73.
This latter on-off valve 73 is operatively connected with the control unit 41 to be operated thereby.
In particular, the control unit 41 is apt to open the on-off valve 73, so as to set into communication the suction path 23 with the environment external to the suction apparatus 10, and the inlet port 72 is sized so as to predominantly let environment-air into the suction path 23, and substantially cause a stop of the suctioning from the suction pipe 15.
The connection between the control unit 41 and the on-off valves 67, 68, 73 is not indicated in the figures so as not to burden the drawings, said connection being of electric/electronic type, or optionally wireless by means of respective radio wave receivers/transmitters.
The suction apparatus 10 also comprises a throttling device 59 set on the suction pipe 15, and provided with gauge 58, or alike pressure meter. Such a throttling device 59 is comprised of a section reducer of the suction pipe, of known type and having the function of locally varying the section of the suction pipe 15, and therefore the pressure inside the suction pipe 15, on the basis of the pressure measuring metered by the gauge.
Operation of the throttling device 59 is entrusted to the ability and experience of an operator, who checks the pressure in the suction pipe 15, and, if the pressure is too high or too low, modifies the section of the suction pipe at the throttling device 59. Therefore, by reducing the pressure into the suction pipe 15 it is obtained a modification of the atmosphere in said suction pipe, and in particular a modification of the flammability range.
Pressure adjustment in the suction pipe 15 depends also on the fact that the suction power of the suction unit 19 depends also on the actual rpm of the engine of the motor vehicle 11. If the engine runs with a low rpm, suction is consistently low, pressure in the suction pipe consistently high, and therefore a modification of the section of the suction pipe 15 may be required .
If the engine runs with a high rpm, suction is consistently high, pressure in the suction pipe consistently low, and therefore a modification of the section of the suction pipe 15 may be required.
Preferably, in the exemplary embodiment illustrated, also the suction unit 19 is subjected to a modification of the atmosphere, in particular it is used a suction pump, such as that manufactured by IngerSoll Rand Company.
In particular, referring to Figure 4a, Figure 4b and Figure 4c, the suction unit 19 comprises a case 80, in which there are housed two three- lobed rotors 81, 82, apt to run in counter rotation.
The case 80 includes an inlet port 83 in which suctioned air enters, and an outlet port 84 from which air exits. Essentially, between inlet port 83 and outlet port 84 there extends a section of the suction path 23. The case 80 also comprises two further ports 86, 88 for injection of additional air. Additional air is introduced in the case 80 and admixes with suctioned air, to cause a dilution in the concentration of combustible material in the case 80. Therefore, also the suction pump is made safe by a constant dilution of the mixture passing thereby.
Preferably, additional air is introduced through a silencer 25b, and also air exiting the outlet port 84 transits through a silencer 25a.
The silencers 25a, and 25b are of known type and substantially consist of containers filled with sound-absorbing material, like for example rock wool.
It may be noticed that said outlet mouth 28 of the suction path 23 is obtained at an end 29 of the silencer 25a set downstream of the suction unit 19.
Operation of the suction apparatus 10 described hereto is as follows.
In a first step, the oxygen detection device 47, the second oxygen detection device 52, the first combustible material detection device 40, and the second combustible material detection device 44 are calibrated by environment air and/or known concentrations of combustible gases.
To this end, for calibration, valves 32, 38, 71, 68 are closed, whereas self- calibration valves 42a and 56, valve 39 and valve 73 are open, as illustrated in Figure 5. Valve opening/closing occurs by means of the control unit 41.
The suction unit 19 is activated, so as to suction air from outside via inlet piping 72; air enters the collecting tank 17 and the filtration device 22, as well as entering in the connecting ducts 42 and 46, so as to be detected by the detection devices 47 and 52. Outside air entrance path is denoted by reference number 223 in Figure 5.
Then, when ducts 42 and 46 are filled with air, self- calibration valves 42a and 56 are closed in order to perform detection.
Likewise, calibration of first and second combustible material detection device 40, 44 takes place by setting the inlet piping 72 in communication, rather than with environment air, with atmospheres having known concentrations of combustible material.
Then, the suction apparatus 10 is operated, and to this end, by the control unit 41, valve 32 and self- calibration valves 42a and 56 are opened, whereas valve 73 is closed. The suction path 23 of a mixture of air and combustible material therefore corresponds to that indicated in Figures 2, 6 and 7.
Specifically, the suction unit 19 is activated for suctioning, via the suction pipe 15, combustible material from an area to be decontaminated. Therefore, in the suction path 23 it is introduced a mixture of air and said combustible material. More specifically, in each section of the suction path 23 it is generated a given atmosphere of certain pressure, comprising oxygen and combustible material.
By first and second combustible material detection device 40, 44, and first and second oxygen detection device 47 and 52, there can be determined, in a manner as correct as possible and substantially continuously or at close intervals, the concentration of oxygen and combustible material in the suction path 23.
In the example, detected concentrations of oxygen and combustible material essentially correspond to an average between concentrations in the collecting tank 17 and in the filtration device 22, or mainly to concentrations of the collecting tank 17, this depending on the mutual sizes of the two devices.
As aforementioned, it has to be pointed out that the presence of the connecting duct 43 between first and second combustible material detection device 40, 44, first oxygen detection device 47 and filtration device 22, allows to obtain a fluid circuit between collecting tank 17 and filtration device 22, this ensuring an accurate pressure measurement, which might also be altered by any load losses in the suction path 23.
If the detected values of oxygen and combustible material concentration fall within a certain flammability range, the control unit 41 acts on the suction unit 19, increasing the vacuum, to a first vacuum value.
If the detected values of oxygen and combustible material concentration do not fall anymore within the flammability range, the suction apparatus 10 lies in a condition of safety from fire or explosion hazard. The suction apparatus 10 can continue the suctioning operation.
If values of oxygen and combustible material concentration still fall within the flammability range, it is convenient to choose between two alternative options.
A first option lies in a further action on the suction unit 19, further increasing vacuum in the suction path 23.
A second option lies in an injection of carbon dioxide or of Nitrogen from inert gas containers 60, 61, or of other inert gas.
To this end, referring to Figure 6, by means of control unit 41, valve 68 is opened so that inert gas contained in inert gas containers 60, 61 enters the collecting tank 17, as indicated by broken line 123. Thus, it is attained a sort of dilution of the atmosphere in the suction path 23.
If the inert gas of containers 60, 61 is not sufficient, it is convenient to open valve 67 and directly connect the collecting tank 17 with the inert gas generator.
Thus, if values of oxygen and combustible material concentration do not fall anymore within the flammability range, the suction apparatus 10 lies in a condition of safety from fire or explosion hazard. Then, valves 67 and/or 68 are closed again, and the apparatus can continue the suctioning operation as illustrated in Figure 3. Of course, when valves 67 and/or 68 are open, suction ability is reduced by the injection of inert gas, increasing the pressure in the suction path 23.
On the contrary, if values of oxygen and combustible material concentration still fall within the flammability range, by means of the control unit 41 valve 73 is opened keeping valves 67 and/or 68 closed, to set in communication the suction path 23 with the external environment and allow environment-air to predominantly enter the suction path 23, thereby causing a substantial cancellation of the suctioning from the inlet mouth 26 in the suction pipe 15. Environment-air entrance path of is denoted by 223 in Figure 5, substantially equal to that of air entrance at calibration of detection devices 40,44,47,52.
It is attained a sort of rarefaction of the flammable mixture, i.e., the volume concentration of combustible material in the apparatus 10 is kept, with an adequate safety coefficient, below the LEL of the substance/s under treatment.
Therefore, operation of the suction apparatus provides a constant and continuous monitoring of oxygen and combustible material concentrations, and an action on each atmosphere modifier consistent with detected concentrations, to optionally modify the atmosphere in the suction path 23, and guaranteeing exiting from the flammability range.
At a certain step of the suction process, to further make safe the suction apparatus 10, the process provides the performing of a recovery, or cleaning, of any dusts or alike combustible material held in the filtration device 22, as illustrated in Figure 7.
In fact any preferably solid residues of combustible material held below the bottom region 35 of the filtration device 22, at a vertical pipe piece 35a connecting the bottom region 35 with the first connection pipe 30 at the elbow union 30a, might cause the formation of an explosive mixture below the same filtration device 22.
In particular, to perform the cleaning, keeping the suction unit 19 in operation, it is closed a valve (non illustrated in the drawings), lying below the bottom region 35 at a vertical pipe piece 35a. Such a valve partitions the bottom region 35 from the elbow union 30a and is usually open during the suctioning step of the apparatus 10, so that the dusts or liquids held in the filtration device 22 deposit on said elbow union 30a.
At the same time valve 71 is opened, and concomitantly valve 38 of first connection pipe 30 is opened.
Under the action of vacuum existing inside of the suction apparatus, a flow in counter-current to the travel direction of the suction path 23 is generated in the vertical pipe piece 35a below the filtration device 22, as denoted in Figure 7 by reference number 323, directed to the collecting tank 17.
Likewise, under the action of vacuum existing inside the suction apparatus 10 and of a pressure existing in the inert gas container 60, a flow of inert gas 423 transits from the inert gas container 60 into the elbow union 30a.
Thus, a flow of air rich in any combustible material coming from the vertical pipe piece 35a admixes with inert gas, transiting into the first connection pipe 30 so as to form a non-explosive mixture, which enters the collecting tank 17.
Also said non-explosive mixture, which enters the collecting tank 17, is constantly monitored by detection devices 40, 44, 47, 52.
To the embodiment of the present disclosure described and illustrated hereto, optional variants and/or additions may be effected by those skilled in the art without departing from the scope of the following claims.

Claims

A suction apparatus (10) for suctioning a combustible material, potentially at risk of fire and/or explosion, said apparatus comprising a suction path (23), extending between an inlet mouth (26) of a mixture of air and of said combustible material, and an outlet mouth (28), said mixture forming, at least in one given section (15, 17, 22, 45) of said suction path (23), an atmosphere comprising a concentration of oxygen and a concentration of said combustible material, said apparatus further comprising, in communication with said at least one section of said suction path (23), at least one first oxygen detection device (47, 52) apt to detect oxygen concentration in said atmosphere, at least one first combustible material detection device (40, 44) apt to detect the concentration of said combustible material in said atmosphere, at least one device (48) for detecting the pressure of said atmosphere and at least one modifier device (41, 60, 61, 62, 63, 64, 72) of said atmosphere, said modifier device (41, 60, 61, 62, 63, 64, 72) being operatively connected to said first oxygen detection device (47, 52), to said first combustible material detection device (40, 44) and to said pressure detection device (48) for modifying said atmosphere when said oxygen concentration and said concentration of combustible material are in a determined relationship with respective reference concentrations.
The suction apparatus (10) according to claim 1, wherein said modifier device comprises an actuator member (41) operatively connected, on the one side, to the first oxygen detection device (47, 52), to the first combustible material detection device (40, 44), and to the pressure detection device (48) and, on the other side, to a suction unit (19), in order to operate the suction unit (19) depending on the detected concentrations of oxygen and combustible material.
The suction apparatus (10) according to claim 1 or 2, wherein said modifier device comprises a device (60, 61, 62, 63, 64) for introducing inert gas, set in communication with said suction path (23).
The suction apparatus (10) according to claim 3, wherein said device for introducing inert gas comprises an inert gas storage container (60, 61).
The suction apparatus (10) according to the preceding claim, characterised in that it comprises a pair of inert gas storage containers (60, 61).
The suction apparatus (10) according to any one of the claims 3, 4 or 5, wherein the device (60, 61, 62, 63, 64) for introducing inert gas is operatively connected to an inert gas generator.
The suction apparatus (10) according to any one of the preceding claims, wherein said atmosphere modifier comprises at least one inlet port (72) that sets in communication the suction path (23) with an environment external to the suction apparatus (10) for introducing environment-air.
The suction apparatus (10) according to any one of the claims 3 to 6, and according to claim 7, wherein said inlet port comprises an inlet piping (72) connected to said suction path (23), and wherein said device (60, 61, 62, 63, 64) for introducing inert gas is jointed to said inlet piping (72).
The suction apparatus (10) according to any one of the preceding claims, comprising a plurality of said modifier devices (41, 60, 61, 62, 63, 64, 72) of said atmosphere, each apt to be operated depending on detected values of oxygen and combustible material concentrations, and on said determined relationship with the respective reference values.
The suction apparatus (10) according to any one of the preceding claims, comprising a second combustible material detection device (44) set in communication with said suction path (23).
The suction apparatus (10) according to any one of the preceding claims, comprising a collecting tank (17) set along the suction path (23), wherein said at least one first oxygen detection device (47, 52), said at least one first combustible material detection device (40, 44), and said pressure detection device (48) are set in communication with said collecting tank (17).
The suction apparatus (10) according to any one of the claims 3, 4 or 5 and according to claim 11, wherein said device for introducing inert gas is set in connection with said collecting tank (17).
The suction apparatus (10) according to claim 7 and claim 11, wherein said inlet port (72) is set in communication with said collecting tank (17).
The suction apparatus (10) according to any one of the preceding claims, comprising a filtration device (22) set along the suction path (23), wherein said at least one first oxygen detection device (47, 52), said at least one first combustible material detection device (40, 44), and said pressure detection device (48) are set in communication with said filtration device (22).
The suction apparatus (10) according to claim 14, comprising a second oxygen detection device (52) set in communication with a section (45) of the suction path (23) set between said filtration device (22) and a suction unit (19).
The apparatus according to claim 4 or 5, claim 11 and claim 14 or 15, comprising a fluid communication between said inert gas container (60, 61) and a connection pipe (30) interposed between a bottom portion (35, 35a) of said filtration device (22) and said collecting tank (17).
The suction apparatus (10) according to any one of the preceding claims, comprising a suction pipe (15) arranged along said suction path (23) at the inlet mouth (26) side, and a throttling device (59) set on said suction pipe (15), serving to vary the section of the suction pipe (15).
A motor vehicle comprising a suction apparatus (10) according to any one of the preceding claims.
A process for suctioning a combustible material, potentially at risk of fire and/or explosion, the process comprising the following steps of
- suctioning a mixture of air and of said combustible material into a suction path (23) extending between an inlet mouth (26) and an outlet mouth (28),

- forming, at least in a given section (15, 17, 22, 45) of said suction path (23), an atmosphere comprising a concentration of oxygen and a concentration of said combustible material,

- detecting the concentration of oxygen and the concentration of said combustible material in said atmosphere,

- detecting the pressure of said atmosphere in said suction path (23);

- modifying said atmosphere when said concentration of oxygen and said concentration of combustible material are in a determined relationship with respective reference concentrations.
The process according to claim 19, wherein said atmosphere is modified by increasing a suction power in the suction path (23), so as to increase a vacuum value in said suction path (23).
The process according to claim 20, wherein said atmosphere is modified by a progressive increase, in at least two subsequent steps, of said suction power.
The process according to claim 19, 20, or 21, wherein said atmosphere is modified by introducing an inert gas.
The process according to any one of the preceding claims 19 to 22, wherein said atmosphere is modified by setting in fluid communication the suction path (23) with an environment external to the suction path, for introducing environment-air into the suction path (23).
The process according to claims 20 or 21 and claim 22, wherein the introducing of inert gas is performed only after an increase of suction power, on the basis of the relationship of the detected concentrations with the reference concentrations.
The process according to claim 22 and claim 23, wherein the communication with the external environment for the introducing of environment-air is performed only after the introducing of inert gas, on the basis of the relationship of the detected concentrations with the reference concentrations.
The process according to any one of the claims 19 to 25, comprising the steps of
- providing, along the suction path (23), a collecting tank (17) and a filtration device (22) set downstream of the collecting tank (17),

- connecting said collecting tank (17) and a bottom portion (35, 35a) of the filtration device (22) by a connection pipe (30);

- providing at least one inert gas container (60, 61),

- connecting by fluid connection said inert gas container (60, 61) with said connection pipe (30);

- causing a first flow (323) in counter-current to a suction flow (23), said first flow (323) transiting from the bottom portion (35, 35a) of said filtration device (22) to said collecting tank (17);

- causing a second flow (423) coming from said inert gas container (60, 61) into the connection pipe (30), said second flow (423) admixing to said first flow (323).