Abstract:
A process for snow melting but useful elsewhere, accomplished by an air/water interface and a water/snow interface. Water is sprayed into a stream of hot air, which is blown onto the snow. The small particles of water are intimately involved with the air molecules and the heat of the air is absorbed by the water droplets, the air giving up its heat to a very large extent. Next, the droplets are combined into larger drops, and then allowed to drop onto the snow. Water, being much heavier than air is much better at absorbing and carrying heat. The heat of the hot air is thus transferred to the snow causing it to melt by using hot water as a heat transfer medium. If the some of the water turns to steam and condenses back into water the effect is further enhanced by about ten times.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The invention relates to snow melting machines. More particularly, the invention relates to machines in which a snow melting operation is accomplished by an air/water interface and a water/ice (snow particle) interface.  
         [0003]     2. Discussion of the Background  
         [0004]     Winter weather in Northern climes brings with it snow and ice, with subsequent inconvenience to road users, users of sports stadia and others. Large amounts of snow need to be removed to make roads passable, parking lots usable and sports fields playable. In intermediate latitudes, it may be possible to simply move snow aside, but in areas where snow fall is heavier and temperatures colder, such as for example in areas prone to lake effect snow, this is not necessarily possible, as the previous snowfall may not have melted. One solution to this problem is to move the snow to a central location and melt it, running the resulting water off to a drain. If you have a pile of snow to melt and you blow hot air or fire on the snow, not much happens, because the hot air will not penetrate directly into the snow, which is a very good insulator, and the air just runs over the surface and dissipates. The invention is directed to an improved solution to this problem.  
         [0005]     In the background art, the best known apparatus for melting large amounts of snow is the type of show melting machine manufactured by Trecan. These are believed to be substantially similar in operation to the apparatus shown in  FIG. 2 . In this arrangement, snow (not shown) to be melted is added to water  430  in a tank  420 , the tank  420  having tubes  480  at each corner. The detailed structure of only one tube  480  is shown for clarity. Each tube  480  includes an inner tube  440  and an outer tube  450 , as well as a burner  490 . The outer tube  450  is provided with lower holes  460  and upper holes  470 . Air is blown into each tube  480  by a blower  410  driven by a large diesel engine  400 . The air is heated by burner  490  and forced down inner tube  440  into outer tube  450 . Water  430  from the tank  420  is admitted into the outer tube  450  via lower holes  460 , and a heated mixture of air and water is expelled via upper holes  470  onto the surface of the water  430 , so as to melt the snow. A drain  485  is also provided to prevent overflow.  
         [0006]     The above-described machine requires a very powerful blower driven by a large engine. This is because the air pressure generated has to overcome the water pressure at the bottom of the tank. Water pressure increases with depth, so the bottom of the tank is where the pressure is greatest. The larger the blower the larger the engine, and the larger the engine the more diesel fuel is consumed by the snow melter. The size of the blower and of the engine also contribute to the size, weight and cost of the snow melter. In addition, the heat transfer is very inefficient, because the time of exposure of the water is limited to that required for the hot air to ascend to the surface of the water bath. This increases the size of the burner as well as the blower and the engine. These and other difficulties of the background art snow melter are overcome by the present invention, as will be described below in relation to the several views, in which like numerals denote like elements.  
       SUMMARY  
       [0007]     This is a description of the advantage of my process devised to use in snow melting machines but useful elsewhere. The operation is accomplished by an air/water interface and a water/ice (snow particle) interface.  
         [0008]     In a preferred embodiment of the invention, hot air or fire is incidentally blown on the snow, but water is also sprayed into the stream of hot air/fire. The small particles of water are intimately involved with the air molecules and highly effective heat transfer takes place with the heat of the air being absorbed by an almost infinite number of water droplets. So, then you have lots of hot water droplets and a flow of air that has given up its heat to a very large extent. Next, the droplets are allowed to be combined into large drops or clumps of hot water. The hot water is then allowed to drop onto the snow pile or into a water bath in which the snow has been placed after removal. The water cuts through the snow like a hot knife through butter. The water, being much heavier than air will naturally be much better at absorbing and carrying heat. The heat of the hot air/fire has just been transferred to the snow and caused it to melt by using hot water as a heat transfer medium. The applicant has found that if some of the water turns to steam and condenses back into water the effect is about ten times as good at transmitting the heat as hot water alone would be. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is a view of a snow melter according to a preferred embodiment of the invention.  
         [0010]      FIG. 2  is an end view of a fuel nozzle disc and fuel delivery pipe according to a preferred embodiment of the invention.  
         [0011]      FIG. 3  is a detailed view of part of the snow melter according to  FIG. 1 .  
         [0012]      FIG. 4  is a view of a snow melter according to the background art.  
         [0013]      FIG. 5  is a view of a movable snow melting boom according to a preferred embodiment of the invention.  
         [0014]      FIG. 6  is a further view of a movable boom and tank according to a preferred embodiment of the invention.  
         [0015]      FIG. 7A  and  FIG. 7B  are views of a backflushing filter screen according to a preferred embodiment of the invention.  
         [0016]      FIG. 8  is a view of a square ‘snail’ according to a preferred embodiment of the invention.  
         [0017]      FIG. 9  is a view of a round ‘snail’ according to a preferred embodiment of the invention.  
         [0018]      FIG. 10  is a view of a zig-zag ‘snail’ according to a preferred embodiment of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0019]      FIG. 1  shows a side view of a snow melting machine according to a preferred embodiment of the invention. In a non-limiting example, the snow melter has a tank  120  that may optionally be provided with wheels  125  to make it easier to move and a hitch  115  for attaching it to a vehicle (not shown) for towing. Tank  120  may be prefilled with water  430 , to which snow  135  to be melted is added. A fan  110  draws a flow of air into a conduit  100  and past a fuel jet  180  and an igniter  190 . Igniter  190  may, for example, be a common spark plug. Fan  110  may be driven by any suitable means known in the art, such as a diesel engine, electric motor, or the like. The means for driving the fan  110  is not shown. In an alternative embodiment, fuel jet  180  and igniter  190  may be collectively replaced with any suitable commercially available burner. Next, the air passes a water jet  170  which introduces droplets of water to be entrained into the hot air. Water may be supplied to the water jet  170  by any suitable means, such as from the mains water supply, or from the water in the tank by means of a pump (not shown), or by any other suitable means.  
         [0020]     Following that the hot air/water mixture passes through a section of conduit  100  provided with baffles  105 . Preferably the conduit  100  is round in cross section and the baffles  105  are semi-circular, although this is not apparent from a side view. Other cross-sectional shapes may alternatively be employed without departing from the scope of the invention, for example square or rectangular, although a circular cross section has been found to be preferable. The baffles  105  are shown mounted alternately at the top and bottom of the conduit  100 , although they might just as easily be mounted alternately on the right and left sides thereof, for example. The baffles  105  are preferably arranged to overlap slightly at the middle of the conduit  100 , sufficiently that no direct path through conduit  100  exists for the mixture without impinging on the baffles  105 . Alternatively, leaving a direct path at the center of conduit  100  can reduce back pressure on the fan  110  with only a small loss in heating ability. It will be appreciated by those skilled in the art that other arrangements of baffles are possible without departing from the scope of the invention. The baffles  105  increase the distance to be travelled by the mixture, and slow it down. This gives more time and distance for heat to be exchanged between the water droplets and the air. Not only that, but by impinging on the baffles  105 , the water droplets are broken into smaller drops which present more total surface area and so are more effective in melting the snow.  
         [0021]     After passing through the baffles  105 , the air/water mixture passes from conduit  100  into vertical tube  150 . A portion of the mixture goes down the vertical tube or chute  150  to be applied to the surface of the water  430 , and a portion is discharged through outlet  160  to be blown onto the surface of the water  430  and onto the snow  135 . Both of these portions help to melt the snow  135 , the former by raising the temperature and providing agitation of the water  430 , and the latter also by spraying hot air and hot water droplets onto the snow  135  to be melted. Note that because vertical tube  150  extends down only to the surface of water  430 , instead of almost to the bottom of the tank as in the background art, the water pressure to be overcome is much less, and therefore a small fan  110  can be used in place of the large blower  410  employed in the background art, with concomitant savings in fuel and weight. The level of water  430  in the tank  120  may be controlled, in a non-limiting example, by allowing the water  430  to overflow through drain  145 .  
         [0022]     The apparatus inside conduit  100  will now be discussed in greater detail in relation to  FIG. 2  and  FIG. 3 . A portion of conduit  100  is shown on a larger scale in  FIG. 3 , including water jet  170 , fuel jet  180  and igniter  190  as shown in  FIG. 1 . A fuel/air mixture is supplied to fuel jet  180  and is entrained into air drawn into conduit  100  by fan  110 . Fuel jet  180  comprises a fuel nozzle disc  200  and a fuel delivery pipe  220 , as shown more clearly in  FIG. 2 . A fuel/air mixture is introduced into fuel nozzle disc  200  via fuel delivery pipe  220 , and discharged via exit holes  250 .  
         [0023]     As shown in  FIG. 3 , this mixture is then ignited by igniter  190  to create flame zone  320 , thereby producing a flow of hot air.  330  is an optional turbine wheel or stationary propellor. Water is introduced into water nozzle  170  via tube  340  and discharged into the stream of hot air at outlet  360 . Air is admitted into outlet  360  via holes  350 , so as to break the water into droplets. Hot air with entrained water droplets is therefore carried to the next stage of conduit  100  including baffles  105 , as described above.  
         [0024]     In an alternative embodiment of the invention, as shown in  FIG. 5  and  FIG. 6 , a system embodying the invention is configured to be used to melt a pile of snow  610  in the back of a truck  600  without having to dump the snow into a separate tank. In this arrangement, melt water from the truck  600  is collected in a small tank  520  positioned beneath the tailgate  620  of the truck and pumped by water pump  510  into the base of an water jacket  660  surrounding a vertical column  550 . The small tank  520  is provided with a drain tap  530  to drain excess water. Hot air from a conventional oil gun burner  590  as known in the art is supplied to the base of the column  550 . At the upper end of the column  550  the water from the water jacket  660  is fed through a water nozzle  670 , which may be similar to water nozzle  170  in  FIG. 1 , and the resulting droplets of water are entrained in the hot air and passed through conduit  500  to outlet  630  which may be directed by hydraulic cylinder  540  to align with the back of the truck  600  to melt the snow. It will be appreciated by those skilled in the art that in place of hydraulic cylinder  540  a pneumatic cylinder or any equivalent means could be employed. Conduit  500  may include baffles similar to the baffles  105  in conduit  100  shown in  FIG. 1 . The vertical column  550  is supported by rings  640  attached to bearings  680  on mast  650 , in turn attached to trailer  560 . Optionally, vertical column  550  may also be directed by one or more hydraulic cylinders (not shown). The small tank  520  may be attached to the trailer  560  for convenience.  
         [0025]      FIG. 7A  and  FIG. 7B  are views of a backflushing filter screen according to a preferred embodiment of the invention, which may be used, for example, with melt water tank  520  and water pump  510  in the embodiment of  FIG. 5  and  FIG. 6 .  FIG. 7A  shows the position of the filter during pumping, and  FIG. 7B  shows the position of the filter during backflushing. Whenever the rate of flow appears to be reduced, the slide ring  700  and screen  710  are raised, thereby opening ports  720  in pipe  750  and allowing water to exit through screen sleeve  710  when pump  510  is reversed, blowing away trash. Bottom blocker  730  keeps the bottom of screen  710  from sucking in trash when pumping. Blocker  730  is hung from the end of pipe  750  on long bolts  760 . Any suitable means may be employed to raise and lower the slide ring  700  and the screen  710 , as will be apparent to those skilled in the art.  
         [0026]      FIG. 8 ,  FIG. 9  and  FIG. 10  show alternative structures that may be used, for example, in place of conduit  100  with baffles  105  in  FIG. 1 . These are meandering structures or ‘snails’ of various shapes, each including a wall  800  provided with projections or ‘speed bumps’  850  to assist in mixing the heated air and the water. In each ‘snail’ air is introduced at air intake  810  by a fan or blower (not shown) and a burner  890  creates a flame front  820  that heats the air. Water is then introduced through water nozzle  870 , and the water is discharged through discharge port  830 . The air also exits the same way, except in the embodiment of  FIG. 10 , where the air exits to the sky through vent  840 .  FIG. 8  shows a square ‘snail’,  FIG. 9 a  round ‘snail’ and  FIG. 10 a  ‘zig-zag snail’. It will, however, be appreciated by those skilled in the art that other shapes are possible without departing from the scope of the invention, as each of these shapes is designed to lengthen the heat exchange path and reduce drop size by mechanical interference.  
         [0027]     As can be seen from the foregoing description, each of the embodiments described differ particularly from known snow melters in that water is added to the heated air before it is brought into the tank, truck body, or other vessel or reservoir containing the snow to be melted. Further, in the present invention the water is added to the heated air in the form of droplets from a nozzle, which gives far better heat transfer and residence time than forcing the air up through water, as well as requiring less energy.  
         [0028]     As will readily be appreciated by those skilled in the art, numerous modifications and variations of the above embodiments of the present invention are possible without departing from the scope of the invention.