EP3981475B1

EP3981475B1 - High-pressure atomiser nozzle, lance including this nozzle and fire extinguishing system including this lance

Info

Publication number: EP3981475B1
Application number: EP21198311.9A
Authority: EP
Inventors: Adolfo Cristanini
Original assignee: Cristanini SpA
Current assignee: Cristanini SpA
Priority date: 2020-10-07
Filing date: 2021-09-22
Publication date: 2023-11-08
Anticipated expiration: 2041-09-22
Also published as: EP3981475C0; IT202000023587A1; EP3981475A1; ES2968338T3

Description

Field of the invention

The present invention is generally relates to the technical field of hydraulic installations, and it particularly relates to a nozzle for atomising liquids at high pressure, that is at least 90 bar.
The invention also relates to a firefighting lance which includes such a nozzle, as well as a fire extinguishing system which includes such lance.

Definition

In the present document, the expression "high pressure" or derivatives is used to indicate an absolute pressure of at least 90 bar, and preferably of at least 150 bar.

State of the Art

Low-pressure fire extinguishing systems which provide for the use of foams or retardants. are known. Such systems have various disadvantages, in particular as relates to the harmful effects of additives on human beings and on the environment. Document EP1175248 discloses such system, which operates under low pressure (maximum 12 bar).
In order to overcome such disadvantages, systems which use high-pressure water which is atomised (so-called water mist) and directed toward the fire, have been developed. Such systems provide for a high-pressure water generator, a connection pipe and a spray lance with an atomisation nozzle.
As known, the extinguishing effectiveness of the atomised spray increases as the" degree "of atomisation increases, that is the effectiveness increases as the amount of water drops increases and the size of the drops decreases.
Known atomiser nozzles comprise a large number of small holes. The degree of atomisation may be higher, that is the size of the smaller drops, as the number of holes increases. A high number of sprays flowing out from the plurality of holes allows to obtain a sufficient extinguishing effectiveness without the need to use additives, foams or retardants.
Though having a sufficient extinguishing effectiveness, such known multi-hole atomiser nozzles, can be improved, both as regards the efficacy of the atomised spray and as regards the water and energy consumption.
As a matter fact, the spray flowing out from such nozzles, tends to be poorly uniform, and therefore to disperse on a relatively large surface.
As a matter fact, drag force is the main force which prevents the advancement of an atomised water spray in the air, and this friction increases as the size of the drops decreases.
Furthermore, such known multi-hole atomisation nozzles are expensive and difficult to manufacture.
Document EP0536529 discloses an atomisation nozzle for low-pressure liquids having all the features of the preamble of the independent claim 1.

Summary of the invention

An object of the present invention is to at least partly overcome the aforementioned drawbacks, by providing an atomiser nozzle that is highly functional and cost-effective.
Another object of the invention is to provide an atomiser nozzle capable of allowing to generate a spray that is particularly effective for extinguishing a fire.
Another object of the invention is to provide an atomiser nozzle capable of allowing to generate an atomised spray with low water consumption.
Another object of the invention is to provide an atomiser nozzle that is particularly durable over time.
Another object of the invention is to provide an atomiser nozzle which, in case of impact with the atomised spray, does not damage property or people.
These and other objects that will be more apparent hereinafter, are attained by an atomisation nozzle, a firefighting lance and a fire extinguishing system respectively according to claim 1, 9 and 12.
Advantageous embodiments of the invention are defined according to the dependent claims.

Brief description of the drawings

Further characteristics and advantages of the invention will be more apparent in light of the detailed description of some preferred but non-exclusive embodiments of the invention, illustrated by way of non-limiting example with reference to the attached drawings, wherein:

FIG. 1 is a lateral view of a nozzle 1;
FIG. 2 is an exploded axonometric view of the nozzle 1;
FIG. 3 is a cross-sectional view of the nozzle 1 with in FIG. 4 an exploded cross-sectional view of the nozzle 1;
FIG. 5 shows some schematic views of a system 100 comprising a lance 120 with different nozzles 1, 1', 1";
FIG. 6 is an axonometric view of a lance 120 with the nozzle 1;
FIGS. 7 and 8 are two charts indicating the velocities and the dimensions of the drops inside a spray flowing out from the nozzle 1 according to the invention and from a multi-hole nozzle of the state of the art.

Detailed description of some preferred embodiments

With reference to the mentioned figures, herein described is an atomiser nozzle 1. The nozzle 1 may be supplied with a liquid L, preferably water, at high pressure and it may be configured so that the jet flowing out from the nozzle 1 is a spray of atomised liquid (so-called water mist). By way of example, the pressure of the liquid L may be comprised between 90 bar and 500 bar, and preferably comprised between 150 bar and 500 bar.
Suitably, the nozzle 1 may be particularly suitable to be used in a fire extinguishing system 100, comprising means 110 for supplying high-pressure water and a lance 120 comprising the nozzle 1. However, it is clear that the nozzle 1 may be used in any system suitable to spray an atomised liquid spray, just like - although hereinafter reference will be made to water for the sake of simplicity - the nozzle 1 may be used with any liquid.
The nozzle 1 comprises an inlet 11, an outlet 17 and a fluidic connection line 10 extending between the inlet 11 and the outlet 17.
The fluidic connection line 10 may therefore comprise - in succession - a duct 12, whose inlet may be defined by the inlet 11, and a duct 14 fluidically connected by means of one or more openings 13. Furthermore, the fluidic connection line 10 comprises an operating chamber 16, whose outlet is defined by the outlet 17, which is fluidically connected with the duct 14 by means of one or more longitudinal openings or slots 15.
Suitably, the duct 12 may have a cross-section substantially smaller than the duct 14 so that the water flow has a higher velocity in the duct 14 with respect to the duct 12.
Advantageously, the ducts 12, 14, the operating chamber 16 and the openings 13, 15 may be mutually dimensioned and configured, that is they may have suitable through-flow cross-sections and dimensions, so that the water increases the velocity when flowing from the duct 12 to the duct 14 and then to the chamber 16, with ensuing pressure variations given that the flow rate is substantially constant.
In particular, as better explained hereinafter, the openings 15 may be configured so as to modify the direction and velocity of the flow of the water flowing into the operating chamber 16, giving rise to a swirling-like motion.
In this manner, flowing into the operating chamber 16, the water may increase the velocity, passing from laminar motion to turbulent motion. This effect, which - as known - entails an increase in the Reynolds number flow (Re > 4000), may be facilitated by the mutual configuration of the openings 15 and of the operating chamber 16.
In these conditions, there may therefore be formed a plurality of water vapour bubbles and a plurality of droplets with particularly small diameter, which may then flow from the operating chamber 16 through the outlet 17, which may preferably be the only outlet opening of the nozzle 1.
For example, the single opening 17 may be substantially circular or elliptical and it may have a diameter in the order of 1-3mm, preferably of about 1.2-2 mm. It is clear that the section of the opening 17 may vary depending on the flow rate and on the pressure.
The table below shows some examples of the diameter of a single circular opening 17 as a function of the flow rate and pressure.

Pressure (bar) Flow rate (l/m) Diameter (mm)

500 30 1.4

200 20 1.5

300 30 1.6

300 42 2

150 30 2
The through-flow section of the fluid defining the single outlet 17 may be significantly smaller than the diameter of the operating chamber 16, for example 3 to 6 times smaller.
Furthermore, as better explained hereinafter, the particular configuration of the edge of the outlet 17 may allow a breaking of the spray and as a result the formation of a large number of droplets.
According to a preferred but not exclusive embodiment of the invention, the nozzle 1 may comprise a main body having a substantially longitudinal extension along an axis X, which may also define the single opening 17. Preferably, but not exclusively, the main body may be substantially cylindrical-shaped and be made of steel.
Advantageously, the main body may be made of two parts or half- bodies 20, 30, which may be mutually removably coupled, for example mutually screwed.
The part 30 of the body may be substantially cylindrical-shaped and internally comprise a blind hole 32, preferably coaxial with the axis X, which may define the duct 12.
In particular, the hole 32 may comprise a bottom opening 321 which may define the inlet 11, an opposite wall 322 and the peripheral openings 13, which may be arranged in proximity of the bottom wall 322. For example, such openings 13 may be four equally spaced circular holes.
The body 30 may comprise a substantially cylindrical portion 33 which includes the inlet 11 and a portion 34 which is also substantially cylindrical with a smaller outer diameter and which includes the openings 13.
The difference between the diameters of the portions 33 and 34 may be defined by an annular relief 342 of the outer surface having the height h.
The portion 34 may internally comprise a blind hole 35, which may be opposite to and preferably coaxial with the blind hole 32. The blind hole 35 may comprise the peripheral openings 15, which may have a substantially longitudinal extension coaxial to the axis X.
The openings 15 define slots in the side wall 351 of the hole 35, extending substantially over the entire height and through the entire thickness of the latter.
In greater detail, the openings or slots 15 substantially radially extend through the thickness of the wall 351, or are inclined with respect to the radius of the hole 35 as illustrated in FIG. 2. Furthermore, the openings or slots 15 may have a substantially constant cross-section through the wall 351, or the cross-section thereof may be radially narrowed, that is it may decrease along the wall 351 as it approaches the axis X.
In this manner, the flow flowing through the openings or slots 15 may advantageously rotate inside the chamber 16 around the axis X, to create, as mentioned above, the vortex around the axis X and the high degree of atomisation of the spray flowing out from the nozzle 1.
The chamber 16 may be defined by the hole 35 and by the upper portion 20' of the part 20 of the main body, which comprises a substantially flat area 21 which includes the outlet 17. In greater detail, the substantially flat area 21 may press against the hole 35 to act as an upper wall of the operating chamber 16, which may be opposite to the bottom wall 21' of the latter, which may be defined by the blind wall of the hole 35.
The single outlet 17 has a sharp edge 235. In particular, the angle between the lateral surface 17' of the single outlet 17 and the substantially flat area 21 may be substantially right angle.
Thanks to this characteristic, the water flow L may be broken into a large number of droplets, so as to obtain a spray with a high degree of atomisation. As mentioned above, this also slows down the velocity of the spray, so that the latter is not harmful in the case of impacts against objects or operators during use.
Furthermore, in this manner the spray flowing out from the nozzle 1 may meet the atomisation characteristics of the spray of class 1 of the United States fire protection regulation NFPA-750. In other words, a high-pressure system 100 with the nozzle 1 may have a spray in which at the distance of 1 m from the nozzle 10% of the drops have an average diameter of <100 µm and 90% have an average diameter of <200 µm (NFPA 750 US class 1).
Preferably, the atomised spray flowing out from the nozzle 1 may have at the distance of 1 metre from the same nozzle 1 about 30% of drops with an average diameter of less than 50 µm and about 45% with an average diameter comprised between 50 µm and 100 µm.
On the other hand, the atomised spray flowing out from the nozzle 1 may have an average diameter of the drops of less than 30 µm, preferably of about 10 µm - 30 µm.
The atomised spray flowing out from the nozzle 1 may have a flow rate of 5 - 100 l/min, preferably of 6 - 80 l/min, even more preferably of about 20 - 30 l/min.
The spray flow flowing out from nozzle 1 may have an outflow velocity of 130 m/s - 300 m/s.
Suitably, the part 20 of the main body of the nozzle 1 may be made of steel, so that the sharp edge 235 is also made of steel. However, in a preferred but non-exclusive embodiment of the invention, the part 20 of the main body of the nozzle 1 at the upper portion 20' thereof, may comprise a shaped seat 22' for a plate 22 having a hole or opening 23 arranged at the opening 17 and a front surface defining the substantially flat area 21.
For example, the plate 22 may have a disc-like shape with a predetermined thickness, and the hole 23 may be substantially cylindrical-shaped, with a lateral surface 231 substantially parallel to the axis X.
The plate 22 may have an outer diameter substantially larger than the inner diameter of the hole 35. In this manner, once the parts 20 and 30 have been coupled, the plate 22 may have an inner area 221 of the surface defining the substantially flat area 21 designed to close the hole 35 and an outer area 222 of the surface abutting against edge 352 of the side wall 351 of the hole 35; defining the shaped seat of the plate 22.
The hole 23 may preferably but not exclusively be central and coaxial with the axis X. For example, the central hole 23 may be circular-shaped or it may have different shapes depending on the needs, for example it may be elliptical-shaped.
Suitably, the plate 22 may be made of a material different from that of the main body, and preferably harder than the latter. This material may comprise or consist of particular forms of aluminium oxides, for example corundum (ruby or sapphire), or diamond.
Preferably, the material of the plate 22 may have a hardness according to the Mohs scale equal to 8 or higher, preferably equal to 9 or higher.
This material may be natural or may be made synthetically.
It is clear that these examples of materials described above are not exclusive. For example, other known materials having a high hardness and resistance to abrasion may be used.
Suitably, the plate 22 may comprise a basic matrix and powder of such hard material, for example diamond. Possibly, the plate 22 may be treated with such material only on the surface or there may be provided for a layer of such a hard material arranged in proximity of the surface 221 of the plate 22. On the other hand, the plate 22 may be entirely made of such material, for example the plate 22 may be made of synthetic ruby.
In any case, the plate 22 or the parts thereof designed to come into contact with water may be made of such material.
Thanks to these characteristics, the plate 22 may withstand the action of the water L and it may guarantee a high durability over time for the nozzle 1. Furthermore, this may allow to avoid the wear of the sharp edge 235, therefore the nozzle 1 maintains high atomisation efficiency over time.
The body 20 may further comprise an area 25 having an inner surface 251 designed to remain facing the outer surface 341 of the portion 34 of the body 30 and spaced from the latter so as to define an interspace. In greater detail, the annular relief 342, the flat area 21, the outer surface 341 and the inner surface 251 may define the interspace 14.
The height h of the relief 342 may define the width of the interspace. In other words, the inner surface 251 may have the same shape as the outer surface 341 and they may be spaced by the distance h. Possibly, the distance h may be defined by the discharge of the threading for coupling the parts 20 and 30 of the main body.
Preferably, the inner surface 251 and the outer surface 341 may be cylindrical and coaxial with the axis X.
This interspace may define the duct 14. The openings 13 and the openings 15 may therefore be mutually spaced so as to place the duct 14 in fluid communication with, respectively, the hole 32 and therefore the duct 12 and with the hole 35 and therefore the operating chamber 16.
The openings 13 and 15 may therefore respectively define the inlet and the outlet of the duct 14.
According to a particular aspect of the invention, the nozzle 1 may be particularly suitable for use in high-pressure water spraying systems such as washing systems, fire-fighting systems, decontaminants or the like.
For example, the nozzle 1 may be used in a system 100, for example a fire-fighting system, which may comprise means for supplying high-pressure liquid, for example a high-pressure pump 110, and a lance 120 fluidically connected with the pump 110 to spray the pressurised liquid.
Possibly, the system 100 may be suitable to carry out both the function of cutting a wall by spraying water and abrasive (cutting extinguisher) and the function of extinguishing the fire by spraying atomised liquid (water mist) from the external of the previously perforated wall, for example as disclosed by the Italian patent IT1424494 on behalf of the Applicant in question.
To this end, as schematically illustrated in FIG. 5, the lance 120 of the system 100 may be configured to alternatively spray the atomised liquid alone or the liquid and abrasive.
In particular, the lance 120 may be configured according to the teachings disclosed by the aforementioned Italian patent, with a first duct 121 for the water with a respective control valve and a second duct 122 for the abrasive with a respective control valve.
Suitably, there may be provided for a particular nozzle 1' configured to allow the mixing of water and abrasive contained in a container 123 and therefore the spraying of such mixture to carry out the cutting step.
Once such step has been completed, the operator may disassemble the nozzle 1' and assemble the nozzle 1 on the first duct 121 of the lance 120 to carry out the step for spraying the atomised water from the external of the previously perforated wall, with the advantages described above.
Preferably, the nozzle 1 may be coupled with the snap-coupling lance 120. In this manner, the assembly and disassembly operations may be particularly simple and quick.
According to a different embodiment not shown in the figures, the fire-fighting system 100 may comprise a lance configured to spray both a conventional spray and a spray of atomised water, for example according to the teachings disclosed by the Italian patent IT1414835 , or a spray lance with a single duct configured to spray atomised water.
Possibly, there may be provided for a system 100 comprising a plurality of atomiser nozzles configured so as to form different atomising sprays, for example sprays having a concentrated or dispersed radius of action, or sprays having a long or reduced operating range, or sprays configured to allow the supply of additives and/or abrasives.
For example, there may be provided for the nozzle 1, a multi-hole nozzle so as to have an outflowing multi-spray, a concentrated nozzle or other nozzles of the per se known type.
The invention may be clearer in light of following example, provided by way of non-limiting example.

Example

Indicated hereinafter is an experiment aimed at measuring the atomisation efficacy of the nozzle 1 with respect to a known multi-hole nozzle.
This experiment uses the known laser anemometry technique called phase Doppler, which, at a selected collimation point of two laser beams, allows to analyse diameters of droplets comprised between 0.5 µm and a few mm, so as to define the following parameters: number of drops passing through, diameter and velocity.
This experiment was carried out considering the same high-pressure system 100 with a lance 120 of the WJFE type marketed by the Applicant in question, on which there was assembled a multi-hole nebuliser nozzle of the known type and subsequently the nozzle 1 according to the invention.
In both cases the flow rate is 22 l/m, the operating pressure 300 bar and the passage section of the nozzle outlet is comparable.
Such measurements were taken 1 metre away from the nozzle of the lance (according to NFPA 750 standard).
The charts shown in FIG. 7 relate to the known nozzle, while the charts shown in FIG. 8 relate to the nozzle 1 according to the invention. In both cases, the readings of the velocities are taken at a distance of 100 cm from the outlet orifice or opening of the water spray.
Some data extracted from these charts are schematically shown in the following table.

Drop diameter d≤50µm Drop diameter 50≤d≤100µm Velocity(U=m/s)

Known nozzle 15% 54.0% 6 - 60 m/s

Nozzle 1 27% 46.5% 4 - 18 m/s
These data show both the high atomisation efficacy of the nozzle 1 (large number of drops with reduced diameter) and the substantial improvements in the performance of the nozzle 1 with respect to the known nozzle.
In particular, the percentage of drops produced by the spray of the nozzle 1 with a diameter d≤50≤µm is significantly higher than that of the known nozzle. Therefore, the spray flowing out from the nozzle 1 has a large number of small droplets, that is the nozzle 1 atomises the water spray better than the known multi-hole nozzle.
Furthermore, the velocity of the droplets of the nozzle 1 (4-18 m/s) is lower than that of the known nozzle (6-60 m/s) and the dispersion of the velocity values detected by the spray flowing out from the nozzle 1 is lower than the dispersion of the velocity values of the known nozzle.
As a matter of fact, as reported above the drag force is the main force which prevents the advancement of an atomised water spray in the air, and this friction increases as the size of the drops decreases.
Therefore, a lower velocity is the result of greater friction. Given that, the drag force of the spray coming from the nozzle 1 is greater than that of the known nozzle, the drops of the nozzle 1 are less dispersed and smaller in size with respect to the ones of the known nozzle. Furthermore, given that the values of the spray of the nozzle 1 are less dispersed than those of the known nozzle, the diameters of the drops of the spray of the nozzle 1 have a greater uniformity with respect to the diameters of the spray of the known nozzle.

Claims

A high-pressure atomiser nozzle, comprising:
- an inlet (11) which can be fluidically connected with means for supplying a high-pressure liquid (L);

- an outlet (17) for the spray of atomised liquid;

- a fluidic connection line (10) extending between said inlet (11) and said outlet (17) comprising:
- at least one first duct (14) defining an axis (X) fluidically connected with said inlet (11);

- an operating chamber (16) arranged downstream of said at least one first duct (14);

- a plurality of first openings (15) for fluidically connecting said at least one first duct (14) and said operating chamber (16) configured so that the liquid (L) flows from the first duct (14) into the operating chamber (16);

wherein said at least one first duct (14), operating chamber (16) and first openings (15) are mutually configured so that the flow of the high-pressure liquid (L) in said operating chamber (16) is of turbulent type;

characterized in that said operating chamber (16) comprises a single outlet opening (17) with small section so that the high-pressure liquid (L) flowing out therefrom is atomised liquid, said operating chamber (16) having a side wall (351) which includes said first openings (15), the latter extending parallel or slightly inclined with respect to said axis (X) in order to have a slot configuration, so that the liquid flow flows into said operating chamber (16) transversely with respect to said axis (X); and further

characterized in that said operating chamber (16) comprises a first substantially flat area (21) perpendicular to said axis (X) which includes said single opening (17), the latter and said first substantially flat area (21) defining a sharp edge (235), said single opening (17) preferably comprising a lateral surface (17') coaxial with said axis (X) which forms a substantially right angle with said fist substantially flat area (21).
Atomiser nozzle according to claim 1, wherein said operating chamber (16) is generally cylindrical-shaped, said single outlet opening (17) having a considerably smaller cross-section with respect to the diameter of said operating chamber (16).
Atomiser nozzle according to claim 1 or 2, wherein said first slot-like openings (15) are substantially inclined with respect to a radial direction passing therethrough, so as to facilitate a swirling motion around said axis (X) of the pressurised liquid (L) entering into said operating chamber (16).
Atomiser nozzle according to one or more of the preceding claims, wherein said fluidic connection line (10) further comprises at least a second duct (12) which includes said inlet (11) substantially coaxial with said axis (X) and a plurality of second openings (13) so as to fluidically connect it with said at least one first duct (14), the latter (14) having a first section, said second duct (12) having a respective second section substantially larger than said first section.
Atomiser nozzle according to any one of the preceding claims, wherein said first substantially flat area (21) is made of a material having a hardness according to the Mohs scale equal to 8 or higher, preferably equal to 9 or higher, said material being preferably an aluminium oxide, for example corundum, or diamond.
Atomiser nozzle according to one or more of the preceding claims, comprising a main body (20, 30) consisting of a first elongated half-body (30) defining said axis (X) and a second half-body (20) which can be mutually removably coupled with said first half-body (30), the latter (30) comprising a first substantially cylindrical portion (34) which includes a first blind hole (35) defining said operating chamber (16), said second half-body (20) comprising an upper portion (20') designed to press against said first blind hole (35) to close - at the upper part - said operating chamber (16) and an inner surface (251) defining said at least one first duct (14) designed to remain facing the outer surface (341) of said first blind hole (35), the latter comprising said first openings (15).
Atomiser nozzle according to claims 1, 5 and 6, wherein the upper portion (20') of said second half-body (20) comprises a substantially disc-shaped plate (22) which includes a central hole (23) at least partially defining said single opening (17), said substantially disc-shaped plate (22) comprising a lower surface (221) defining said first substantially flat area (21), said lower surface (221) defining - with said central hole (23) - said sharp edge (235), said plate (22) being made of said material having a hardness according to the Mohs scale equal to 8 or higher, preferably equal to 9 or higher.
Atomiser nozzle according to claims 6 or 7 when dependent on claim 4, wherein said first cylindrical portion (34) of said first half-body (30) further comprises said plurality of second openings (13), said first half-body (30) further comprising a second blind hole (32) substantially coaxial with said axis (X) and opposite with respect to said first blind hole (35) to define said second duct (12), said second blind hole (32) having a first open end (321) defining said inlet (11) and a second opposite end (322), said plurality of second openings (13) being arranged at said second opposite end (322).
A lance (120) which can be fluidically connected with means for supplying a high-pressure (110) liquid (L) comprising at least one duct (121) which includes at least one atomiser nozzle (1) according to one or more of the preceding claims.
Lance according to the preceding claim, further comprising at least a second nozzle (1'), said atomiser nozzle (1) and said second nozzle (1') being suitable to be selectively and removably connected with said at least one duct (121).
Lance according to the preceding claim, further comprising a second duct (122) which can be fluidically connected or is connected with means (123) for the storage of an abrasive additive, said second nozzle (1') being suitable to be fluidically connected to said first and second duct (121, 122) so as to allow an operator to drill a wall with a mixture of high-pressure liquid and abrasive additive.
Fire extinguishing system comprising:
- means for supplying a high-pressure (110) liquid (L);

- a lance (120) fluidically connected with said supply means (110);
wherein said lance (120) is a lance according to claim 9, 10 or 11.