Ground warming heater and method and system relating thereto

Abstract

A ground heater includes an insulated housing enclosing a primary fuel line within the insulation, an ambiently aspirated hollow tube running the length of the housing and extending substantially entirely through a cavity defined by an inner surface of the housing and wherein the cavity defines an opening into the housing, a torch head mounted in a torch head housing and having a fuel line thereto branched from the primary fuel line and mounted in fluid communication with an upstream end of the tube, the opposite downstream end venting to atmosphere so that a flame from the torch head extends along the interior of the tube to heat the cavity and a ground surface in registry with the opening.

1 . A ground heater for warming the ground comprising:
 an insulated housing having a cavity extending along substantially an entire length thereof, a bottom of said housing having an opening along substantially said entire length thereof for registry of said cavity with a ground surface to be warmed when said housing is placed thereon,   a hollow heating tube extending through said cavity along said entire length and so as to extend through opposite end walls of said housing, said tube having an upstream end and an opposite downstream end, a torch head housing mounted to said upstream end of said heating tube in fluid communication therewith,   a primary fuel line mounted in and extending along a sidewall of said housing so as to extend from an upstream end wall of said opposite end walls to a downstream end wall of said opposite end walls, a branch fuel line extending from said primary fuel line to an upstream end of said torch head housing,   a torch head having a fuel metering orifice and a bore extending through said torch head downstream of said fuel metering orifice, and at least one aspirating aperture downstream of said metering orifice in a sidewall of said torch head in fluid communication with said bore, said torch head mounted substantially concentrically in, so as to be supported by, said torch head housing, said torch head housing having opposite upstream and downstream ends and a perforated support at said downstream end of said torch head housing, a flame holder end of said torch head mounted to said support and adjacent said downstream end of said torch head housing so as to dispose a flame seated in said flame holder end downstream along said heating tube towards said downstream end of said heating tube to thereby discharge exhaust gases of combustion therefrom and to draw an ambient airflow into said upstream end of said torch head housing, over said torch head and through said at least one aspirating aperture and said perforated support,   wherein said perforated support comprises at least one rigid member on which said torch head is mounted within said torch head housing, said rigid member defining at least one breathing aperture which extends substantially entirely around said downstream end of said torch head in a plane substantially orthogonal to a direction of flow of said ambient air through said torch head housing, said torch head housing and said torch head defining a substantially annular breathing channel therebetween extending in said direction of flow and in registry with said at least one breathing aperture.   
   
   
       2 . The apparatus of  claim 1  wherein an outside diameter of said breathing channel is substantially equivalent to an inside diameter of said heating tube. 
   
   
       3 . The apparatus of  claim 1  wherein said torch head housing is cylindrical. 
   
   
       4 . The apparatus of  claim 3  wherein said torch head housing comprises a concentrically nested pair of cylinders, and wherein said torch head is mounted concentrically within an inner cylinder of said pair of cylinders. 
   
   
       5 . The apparatus of  claim 4  wherein said upstream end of said heating tube is of greater diameter than a mid-section of said heating tube extending between said upstream and downstream ends of said heating tube, and wherein an outer cylinder of said pair of cylinders mates telescopically into said upstream end of said heating tube. 
   
   
       6 . The apparatus of  claim 1  wherein said at least one aspirating aperture comprises a radially spaced apart array of apertures around said torch head for aspirating air radially into said bore to mix with fuel flowing under pressure through said metering orifice and into said bore, and wherein a perforated flame holder plate is mounted across a downstream end of said bore in the flow of said mixture of fuel and air exiting said bore into said upstream end of said heating tube. 
   
   
       7 . The apparatus of  claim 6  wherein igniter is mounted adjacent downstream of said flame holder end of said torch head. 
   
   
       8 . A system of ground heaters comprising a plurality of ground heaters according to  claim 1  in series along said primary fuel line. 
   
   
       9 . The system of  claim 8  wherein said plurality of heaters includes a first plurality of said heaters mounted in series along a first primary fuel line, and a second plurality of heaters mounted in series along a second primary fuel line, wherein said first and second primary fuel lines are in parallel fluid communication for operating in parallel said first and second plurality of said heaters. 
   
   
       10 . The apparatus of  claim 1  wherein said at least one breathing aperture includes a pair of breathing apertures oppositely disposed on opposite sides of said downstream end of said torch head. 
   
   
       11 . The apparatus of  claim 10  wherein said at least one breathing aperture consists solely of said pair of breathing apertures. 
   
   
       12 . The apparatus of  claim 10  wherein said pair of breathing apertures includes a pair of opposed facing substantially semi-circular slots disposed substantially symmetrically on said opposite sides of said downstream end of said torch head. 
   
   
       13 . The apparatus of  claim 11  wherein said pair of breathing apertures includes a pair of opposed facing substantially semi-circular slots disposed substantially symmetrically on said opposite sides of said downstream end of said torch head. 
   
   
       14 . A method for warming the ground comprising the steps of:
 a) providing an insulated housing having a cavity extending along substantially an entire length thereof, a bottom of said housing having an opening along substantially said entire length thereof and placing said housing on a ground surface to be warmed so as to register said cavity with the ground surface to be warmed by positioning said opening adjacent the ground surface to be warmed,   b) providing a hollow heating tube extending through said cavity along said entire length and so as to extend through opposite end walls of said housing, said tube having an upstream end and an opposite downstream end, a tubular torch head housing mounted to said upstream end of said heating tube in fluid communication therewith,   c) providing a primary fuel line mounted in and extending along a sidewall of said housing so as to extend from an upstream end wall of said opposite end walls to a downstream end wall of said opposite end walls, and a branch fuel line extending from said primary fuel line to said upstream end of said heating tube,   d) providing a torch head having a fuel metering orifice and a bore extending through said torch head downstream of said fuel metering orifice, and at least one aspirating aperture downstream of said metering orifice in a sidewall of said torch head in fluid communication with said bore, wherein said torch head is mounted substantially concentrically in, so as to be supported by, said torch head housing, said torch head housing having opposite upstream and downstream ends and a perforated support at said downstream end of said torch head housing, a flame holder end of said torch head mounted to said support and adjacent said downstream end of said torch head housing so as to dispose a flame seated in said flame holder end downstream along said heating tube towards said downstream end of said heating tube to thereby discharge exhaust gases of combustion therefrom and to draw an ambient airflow into said upstream end of said torch head housing, over said torch head and through said at least one aspirating aperture and said perforated support, wherein said perforated support comprises at least one rigid member on which said torch head is mounted within said torch head housing, said rigid member defining at least one breathing aperture which extends substantially entirely around said downstream end of said torch head in a plane substantially orthogonal to a direction of flow of said ambient air through said torch head housing, and wherein said torch head housing and said torch head define a substantially annular breathing channel therebetween extending in said direction of flow and in registry with said at least one breathing aperture,   e) supplying fuel under pressure to said fuel metering orifice in said torch head so as to mix metered fuel from said orifice and ambient air from said at least one aspirating aperture in said bore as said mixture flows downstream through said bore so as to exit said downstream end of said torch head, and   f) igniting said mixture exiting said downstream end of said torch head by an igniter mounted adjacent said flame holder end of said torch head.   
   
   
       15 . The method of  claim 14  further including adapting an outside diameter of said breathing channel so as to be substantially equivalent to an inside diameter of said heating tube. 
   
   
       16 . The method of  claim 14  further comprising the steps of adapting said torch head housing so as to include a concentrically nested pair of cylinders, and mounting said torch head concentrically within an inner cylinder of said pair of cylinders. 
   
   
       17 . The method of  claim 16  further including adapting said upstream end of said heating tube so as to be of greater diameter than a mid-section of said heating tube extending between said upstream and downstream ends of said heating tube, and adapting an outer cylinder of said pair of cylinders so as to mate telescopically into said upstream end of said heating tube. 
   
   
       18 . The method of  claim 14  further including adapting said at least one aspirating aperture to include a radially spaced apart array of apertures around said torch head for aspirating air radially into said bore to mix with the fuel flowing under pressure through said metering orifice and into said bore, and further including mounting a perforated flame holder plate across a downstream end of said bore in the flow of the mixture of fuel and air exiting said bore into said upstream end of said heating tube. 
   
   
       19 . The method of  claim 14  further comprising the step of providing a plurality of ground heaters according to  claim 14  in series along said primary fuel line. 
   
   
       20 . The method of  claim 19  further including adapting said plurality of heaters to include a first plurality of said heaters mounted in series along a first primary fuel line, and a second plurality of heaters mounted in series along a second primary fuel line, wherein said first and second primary fuel lines are in parallel fluid communication for operating in parallel said first and second plurality of said heaters.