Device and process of snow removal

Abstract

The device includes a first reservoir equipped with a mobile dynamic compacting device, water injection nozzles above and below chopping and/or mixing devices capable of forcing the snow downwards and ultrasound generating devices positioned below the water injection nozzles. The first reservoir is connected to a storage basin with two fluid transfer lines.

Claims

1. A snow volume-reducing and fluidisation device comprising: a first fixed reservoir equipped with a fluidizer configured to fluidise and reduce the volume of snow; at least one second reservoir forming a storage basin of larger volume than the first reservoir, the volume of said storage basin being at least 20 times the volume of the first reservoir, and said storage basin being at least partly filled with water, said water being at ambient temperature; at least one first fluid transfer conduit between an evacuation orifice at the lower end of said first reservoir and said storage basin, said evacuation orifice enabling evacuation of a fluidised snow mixture in a lower part of the first reservoir; and at least one second transfer conduit between said storage basin and said first reservoir; said fluidizer comprising: a snow compactor comprising a mobile dynamic compactor; and a mechanical snow breaker comprising a chopper and/or a mixer arranged below said snow compactor, said mechanical snow breaker being configured to force the snow to move downwards; and at least one water injector inside and/or above the first reservoir and supplied with water from the storage basin via said second transfer conduit, said water injector being positioned at least above said chopper and/or mixer; and an ultrasound generator comprising ultrasound emitters supported by a rigid structure inside the first reservoir, arranged below said chopper and/or mixer and below said water injector.

2. The device according to claim 1 wherein said first reservoir is partly pre-filled with water in a lower part of the first reservoir as far as above said ultrasound emitters and below said mechanical snow breaker.

3. The device according to claim 1 wherein said rigid structure is a lattice structure defining orifices allowing the passing of fluidised snow and flowing of the snow downwards in the first reservoir, said rigid structure extending over substantially entirely a horizontal cross-section of the first reservoir and supporting a plurality of said ultrasound emitters distributed at several points.

4. The device according to claim 1 wherein said ultrasound emitters are in the form of cylindrical bars secured on top of solid parts of said rigid structure and distributed over said rigid structure so that said ultrasounds are diffused in substantially homogeneous manner over the entire cross section of said first reservoir, at least in a lower part of the first reservoir.

5. The device according to claim 1 wherein said mobile dynamic compactor comprise an assembly of pivoting plates, the assembly of said pivoting plates substantially covering an entire surface of a horizontal cross-section of said first reservoir above said chopper and/or mixer, said pivoting plates being secured to side walls of the first reservoir, said pivoting plates being hinged in rotation relative to said side walls of said first reservoir on a horizontal rotation shaft.

6. The device according to claim 1 wherein the first reservoir further comprises a filter for filtering solid objects contained in the snow, arranged upstream of said evacuation orifice and downstream of said ultrasound generator.

7. The device according to claim 1 wherein the first reservoir further comprises static compactor consisting in that the first reservoir has: a height that is of larger dimension than width thereof; and side walls comprising a funnel-forming part forming a funnel of smaller horizontal cross section than an upper opening thereof, said funnel-forming part being arranged at least below said chopper and/or mixer.

8. The device according to claim 1 wherein said mechanical snow breaker comprises toothed rotating discs and/or fingers in the form of angled blades mounted on at least a horizontal transverse shaft or drum, configured to break up and force downwards pieces of ice and/or compacted snow.

9. The device according to claim 1 wherein said first reservoir comprises or cooperates with aid dynamic snow evacuator to evacuate a fluidised snow at a lower end of the first reservoir, downstream of said evacuation orifice and below said ultrasound generator.

10. The device according to claim 1 wherein the reservoir further comprises first means to transfer fluidised snow comprising the first transfer conduit and a first pump to circulate a mixture obtained from said first reservoir towards a said storage basin, and second means to transfer water between the storage basin and water injector inside the first reservoir, comprising a second transfer conduit and a second fluid circulation pump.

11. The device according to claim 1 wherein the first reservoir is an open-top tank having a lower part of side walls buried in the ground.

12. The device according to claim 1 wherein said first reservoir is arranged on a truck or trailer.

13. The device according to claim 1 wherein said storage basin is an open storage basin having at least a lower part of side walls buried in the ground.

14. A site snow-clearing method using a device according to claim 1 wherein the following steps are carried out comprising: tipping snow into the first reservoir; actuating said chopper and/or mixer, said water injector, said dynamic compactor and said ultrasound generator; and evacuating fluidised snow from said evacuation orifice towards said storage basin.

15. The method according to claim 14 wherein said first reservoir and said storage basin are partly pre-filled with water, and water circulates in a closed circuit between said storage basin and said first reservoir, said storage basin comprising or cooperating with water filter and conducts and pumps allowing stored water to be transferred to a water supply network or into an environment.

16. The device according to claim 5 wherein said pivoting plates are open plates or first pivoting grids.

17. The device according to claim 5 wherein pivoting of said pivoting plates is assisted by hydraulic actuators.

18. The device according to claim 6 wherein the first reservoir further comprises evacuator to evacuate said objects out of said first reservoir, said evacuator being of scraper type actuated by a cylindric actuator or Archimedes screw.

19. The device according to claim 8 wherein said toothed rotating discs and/or fingers are mounted on a plurality of parallel shafts or drums so as substantially to cover an entire horizontal cross-section of said first reservoir.

20. The device according to claim 9 wherein said dynamic snow evacuator comprises a transfer pump and/or motorized worm screw.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an overall illustration of the device with the reservoir 1 and storage basin 11 giving a vertical, longitudinal section view of the reservoir;

(2) FIG. 2 is a vertical cross-sectional view of the reservoir in a buried pit;

(3) FIG. 3 is an overhead view of the reservoir showing the openwork compacting plates in bottom closed position;

(4) FIG. 4 is an overhead view of the assembly of chopping and mixing devices 2;

(5) FIG. 5A is an overhead view of the first lattice structure 5 supporting the ultrasound generating means;

(6) FIG. 5B is a vertical cross-sectional view of the first lattice structure 5 showing transducers 5a in homogeneous arrangement; and

(7) FIG. 6 is an overhead view of a filtration grid 6.

DETAILED DESCRIPTION OF THE INVENTION

(8) FIG. 1 illustrates a device of the invention allowing a volume of snow to be reduced by fluidisation for easy evacuation thereof. The volume-reducing, fluidisation and storage device of the invention illustrated in the Figures comprises a first reservoir 1 arranged below ground level in a pit 17 which can be partly buried in the vicinity of the site to be cleared of snow, and connected to a second reservoir called storage basin 11 of larger volume and also preferably buried and located further away from the site to be cleared. The reservoir and storage basin are open at the top.

(9) The first reservoir 1 comprises a horizontal cross-section of rectangular shape and has an upper part 1a with flared side walls including two parallel, opposite side walls equipped with compacting means 4. The compacting means are formed of two rectangular, openwork plates 4a each pivot-mounted on a horizontal shaft 4b arranged at one of said lateral walls and capable of being pivoted by a cylinder 4c between: a lower closed, substantially horizontal position in which the two openwork plates 4a substantially cover the entire surface of the horizontal cross-section of the first reservoir, said cylinder 4c being in extended position; and an open upper position in which the openwork plates 4a are substantially in vertical position against said side walls 1a. Initially, the openwork plates are therefore in the upper open position when a loader or dump truck (not illustrated) drops snow into the first reservoir. Then, at a first stage of the treatment method according to the invention the openwork plates are pivoted to lower position to compact the snow between said plates 4a and the mixing means 2 positioned underneath as described below. It is preferred here that the openwork plates 4a should not descend lower than the horizontal position to avoid excessive compacting of the snow and jamming actuation of the chopping and mixing means 2 described below.

(10) The compacting means also contribute towards pushing the snow downwards in the first reservoir 1 in the direction of the chopping and mixing means 2.

(11) In FIG. 3, the plates 4a are formed of parallel slats 4.sub.2 separated by voids 4.sub.1 forming combs or rakes.

(12) The orifices 4.sub.1 in the openwork plates 4 allow evacuation of the air contained in the snow at the time compacting. Compacting of the snow preferably allows a first volume reduction to be obtained of at least 30% (v=70% of v0). In addition a further objective of compacting is to optimise the efficacy of the snow break-up means via ultrasound treatment described below.

(13) The compacted snow in the intermediate compartment 1b between the openwork plates 4a in lower position and the chopping and mixing means 2 (described below) is treated by injecting water at ambient temperature by the first water spray nozzles 3a mounted on the side walls of the intermediate part 1b of the reservoir. The water is drawn from the water 12 stored in the storage basin 11, the latter being initially filled with an amount that is at least 20%, here 50%, of its volume. The water 12 is pumped at the bottom 11a of the storage basin 11 and transferred via said second transfer line 10 and second circulation pump 10a to the spray nozzles 3a and 3b. The spray nozzles 3a and 3b allow sprinkling of the snow with water to contribute towards fluidisation thereof since the sprayed water is at ambient temperature. In this respect, it is pointed out that if the outside weather conditions are very cold and the surface of the basin 12 is frozen, the water underneath the surface is liquid and remains at a sufficient temperature to heat and start fluidising the snow. The water injected into the compacted snow therefore allows initial fluidisation.

(14) The snow is then chopped and mixed by chopping and mixing means 2 comprising a plurality of chopping and mixing devices 2 arranged horizontally and parallel. Each chopping and mixing device 2 comprises a plurality of discs with toothed periphery and/or with fingers or projections in the form of blades 2a, tilted in relation to the vertical in a regularly spaced and parallel arrangement, and mounted around and along a horizontal shaft 2b able to be set in rotation by a motor 2c. The rotating toothed discs and/or blades 2a create the triple technical effect of chopping, mixing and forced downward movement of the compacted snow to a lower part 1c of the reservoir arranged below the chopping and mixing means 2.

(15) In the lower part 1c, the side walls of the first reservoir are of pyramidal of funneled shape. At this level, the compacted snow has been partly fluidised and is in the form of a mixture. Any pieces of ice contained therein have been crushed and any blocks of highly compacted snow have been chopped. The chopped, mixed snow is also subjected to water injection treatment by second lower water spray nozzles 3b arranged underneath the chopping and mixing devices 2 and supplied by the same second conduit 10 and second pump 10a. With this fluidisation treatment the snow undergoes a volume reduction by a factor of at least 2 to 5 when it is useful to apply an additional compacting treatment resulting from the funnel shape of the reservoir side walls in said lower part 1b.

(16) In FIG. 4, nine chopping and mixing devices 2 have been arranged 9 parallel and side by side so as substantially to cover the entire surface of a horizontal cross-section of the first reservoir, two successive devices being regularly spaced part with their rotation shaft rotating in reverse direction relative to the other.

(17) In the lower part 1c, the snow is subjected to ultrasound treatment to complete snow break-up and fluidisation. This lower part 1c of the first reservoir is initially pre-filled with water and represents a volume of about 6 m3 for example. The surface 6 of the water being about 6 m.sup.2 for example over a height H2 higher than 1 m due to the funnel shape of this lower part 1c.

(18) Part 1b of the reservoir containing the chopping and mixing devices 2 and water injection nozzles 3 above the rigid structure 5, extends over a height H1 higher than H2.

(19) In FIGS. 5A and 5B, the ultrasound treatment means comprise a rigid lattice structure 5 formed by crossed profiles or rigid frame members 5a having a thickness and width of 5 to 10 cm on which ultrasound-emitting sonotrodes or transducers 5b are secured distributed at multiple points in the horizontal cross-section of the first reservoir. The meshing of the lattice structure 5 creates orifices 5.sub.1 having sides d=5 to 25 cm, in particular d=10 to 20 cm, allowing the downward flow of the broken down water/snow mixture. The sonotrodes are in the form of substantially cylindrical bars of diameter about 5 to 10 cm and height of about 50 to 150 cm. Ultrasound emitters of this type in the form of bars are known to persons skilled in the art and commercially available. This embodiment is advantageous since it creates a vibrating contact surface and hence the generation of ultrasounds within the water/snow mixture in the first reservoir and substantially over the entire cross-section thereof. For example 20 to 40 ultrasound emitting bars 5b of this type of 20 kHz to 2 kW power are regularly distributed over the entire lattice structure 5a.

(20) The initial pre-filling of the lower part 1c of the first reservoir with water allows said ultrasound-emitting bars to be fully immersed, in particular to promote diffusion of ultrasound waves within the entire water/snow mixture.

(21) Underneath the break-up means via ultrasound generation 5, a filtration grid 7 is arranged as illustrated in FIG. 6 of smaller mesh size 7.sub.1 intended to collect pieces of waste or various objects initially contained in the collected snow and that can be periodically evacuated from the grid by a scraper 7a actuated by a hydraulic cylinder 7b towards outside the reservoir 1 which comprises an evacuation hatch (not illustrated) in the direction of the associated storage basin 11. The grid 7 particularly retains any metallic or mineral elements such as stones contained in the snow.

(22) It is advantageous to arrange this grid 7 underneath the fluidisation means 2-6 of the first reservoir since if this grid 7 were to be arranged in the upper part its smaller mesh size 7.sub.1 could prevent the passing of non-fluidised snow through the filtering grid.

(23) The open lower end 1e of the lower part 1d of the reservoir arranged below the grid 7 is funnel-shaped to accompany the reducing of snow volume in fluidised form. The lower end 1e communicates with means 8 to evacuate fluidised snow. These evacuation means 8 comprise a transfer pump 9ab and conduit 9 optionally completed by a motorised worm screw 8a or Archimedes screw inside a cylindrical nozzle 8c actuated by a motor 8b to push the fluidised snow inside the first transfer conduit 9 assisted by the circulation pump 9a thereby feeding the storage basin 11 and setting up closed loop circulation between the first reservoir and the storage basin.

(24) The storage basin 11 can be equipped with a third transfer conduit 13 transferring water from its bottom part 11a, assisted by a circulation pump 14 integrating water filtration means, towards a water supply network 15.

(25) The third transfer conduit 15 may also allow evacuation of water 12 stored in the storage basin 11 towards a secondary storage point such as a lake, river or other.

(26) Conducted tests provided the demonstration that the ultrasound waves have an effect on snow fluidisation without the need to apply heat under the following conditions. The ultrasound waves have the effect of initially reducing the volume of snow when the snow retracts and of fluidising the snow to obtain a mixture easily transferable by conventional pump and conduits.

(27) This effect is improved by 30% in terms of rapidity if the volume of snow mass is initially reduced by 30% via compacting.

(28) For a large-size international airport, the amount of snow to be evacuated with a coverage thickness of 10 cm would be 200,000 to 600,000 m3 with weight varying between 200 and 500 kg/m3; the equivalent amount of water to be evacuated is therefore 22,000 to 300,000 m3.