Snow melting system and method with direct-contact water heater

Abstract

A snow melting system and a method is comprised of a snow melting housing defining a snow melting chamber therein. The housing has an opening to load snow in the snow melting chamber. A support is provided across the snow melting chamber to support snow therein elevated from a bottom wall of the snow melting chamber and to permit the passage of water therethrough to be collected in a water holding portion of the housing. A plurality of water spray nozzles are mounted in the housing about the snow melting chamber. A direct-contact water heater is provided for heating water to produce a supply of hot water to be fed at a constant pressure to the water spray nozzles for injection into the snow placed in the snow melting chamber for melting the snow. The direct-contact water heater is supplied water to be heated from the water holding portion of the housing. Excess water in the water holding portion is discharged and disposed of in the city drainage system.

1 . A snow melting system comprising a snow melting housing defining therein a snow melting chamber, an opening in said housing to load snow in said snow melting chamber, support means across said snow melting chamber to support snow therein elevated from a bottom wall of said snow melting chamber and permitting the passage of water therethrough to be collected in a water holding portion of said housing, a plurality of water spray nozzles mounted in said housing about said snow melting chamber, a direct-contact water heater for heating water to produce a supply of hot water to be fed at a constant pressure to said water spray nozzles for injection into snow placed in said snow melting chamber for melting said snow, said direct-contact water heater being supplied water to be heated from said water holding portion of said housing, and water evacuation means to discharge excess water from said water holding portion. 
     
     
         2 . A snow melting system as claimed in  claim 1  wherein said support means is a filter screen for removing debris from snow melted in said snow melting chamber. 
     
     
         3 . A snow melting system as claimed in  claim 1  wherein there are multiple vertical rows of said water spray nozzles mounted about said snow melting chamber. 
     
     
         4 . A snow melting system as claimed in  claim 1  wherein said water spray nozzles are angulated in an upward direction in said snow melting chamber and wherein a supply of snow is maintained to at least cover said water spray nozzles to reduce the production of vapour from said hot water injected in said snow in said snow melting chamber. 
     
     
         5 . A snow melting system as claimed in  claim 1  wherein said direct-contact water heater is comprised of a heating housing having one or more spray nozzles at a top end thereof spaced above a packing of heat exchange bodies, said one or more spray nozzles spraying said water to be heated over said packing in water droplets to cause said water droplets to percolate through said heat exchange bodies to extract heat therefrom, a burner spaced below said packing exteriorly of said heating housing and adapted to introduce a hot flame in said heating housing spaced below said packing to generate a heating air flow for heating said heat exchange bodies and further heating said water droplets released from underneath said packing, and a hot water collecting reservoir at a bottom end of said heating chamber constituting said supply of hot water. 
     
     
         6 . A snow melting system as claimed in  claim 5  wherein said burner is one of a natural gas, propane gas or oil burner being supplied by a supply source. 
     
     
         7 . A snow melting system as claimed in  claim 5  wherein said supply of hot water is fed under substantially constant pressure to said water spray nozzle by a transfer pump, and valve means to connect selected groups of said water spray nozzles to said transfer pump. 
     
     
         8 . A snow melting system as claimed in  claim 5  wherein said one or more spray nozzles are fed said water to be heated from said water holding portion of said housing by a water re-circulation pump. 
     
     
         9 . A snow melting system as claimed in  claim 8  wherein a further filter is connected in an outlet conduit of said water holding portion of said housing upstream of said water re-circulation pump. 
     
     
         10 . A snow melting system as claimed in  claim 5  wherein said supply of hot water is at a temperature of from about 40° C. to 50° C., said water to be heated in said water holding portion of said housing being at a temperature of about 3° C. to 4° C. 
     
     
         11 . A snow melting system as claimed in  claim 1  wherein said apparatus is one of a stationary or a mobile snow melting housing. 
     
     
         12 . A snow melting system as claimed in  claim 1  wherein said water evacuation means is an overflow conduit connected to said housing in a top portion of said water holding portion to direct excess water therefrom for disposal in a drainage system. 
     
     
         13 . A method of melting snow for disposal thereof comprising the steps of:
 i) discharging snow to be melted into a snow melting chamber of a snow melting housing, said snow being supported therein elevated from a bottom wall of said housing by support means permitting the passage of water therethrough,   ii) injecting hot water by water spray nozzles secured all about said snow melting chamber in said snow and at a constant pressure whereby to melt said snow at a substantially constant rate,   iii) collecting water from said melted snow in a lower water holding portion of said housing,   iv) evacuating excess water from said lower water holding portion for disposal,   v) recirculating water from said lower water holding portion through a direct-contact water heater to heat said water therein to produce a source of said hot water to supply said water spray nozzles.   
     
     
         14 . A method as claimed in  claim 13  wherein said support means is a screen and wherein there is further provided the step of separating debris from said snow by said screen as said snow is being melted in said snow melting chamber, and removing said debris from said screen. 
     
     
         15 . A method as claimed in  claim 13  wherein said step (v) comprises pumping said water from said lower water holding portion to one or more spray nozzles at a top end of said direct-contact water heater, spraying said water by said spray nozzles over a packing of heat exchange bodies to form water droplets for heat exchange therewith to heat said water droplets percolating therethrough, injecting a flame from a burner below said packing to generate a hot air flow through said packing to heat said heat exchange bodies and further heat water droplets released from underneath said packing, and collecting said heated water droplets in a collecting reservoir therebelow. 
     
     
         16 . A method as claimed in  claim 13  wherein said step (iv) comprises evacuating an overflow of water from said lower holding portion and feeding same into a drainage system. 
     
     
         17 . A method as claimed in  claim 13  wherein said water spray nozzles are equidistantly spaced about said snow melting chamber in at least two horizontal rows and wherein said step (ii) further comprises the step of connecting one or both of said at least two horizontal rows of water spray nozzles to a constant pressure pump to inject said hot water through said one or both horizontal rows of water spray nozzles, said water spray nozzles being oriented to inject said hot water directly into said snow to minimize the formation of vapour above said snow.