Portable ground thawing system and method

Abstract

A portable ground thawing system for excavating Shovel Test Pits (STPs) includes a cylindrical heat chamber having an open bottom and a closed top. A charging inlet is disposed on one side and a flue is on the other. An adjustable baffle is stationed in the flue. A salamander style heater is positioned to emit a stream of hot gas through the charging inlet, creating a swirling internal current of hot gas that loops through an internal heat loft. The heat loft provides both radiant heat properties as well as supports convection via the gas current that sweep across the frozen ground before exiting the flue. Electricity to power the heater is supplied by a generator. The method of use includes orienting the heat chamber so that its charging inlet is leeward and its flue is windward relative to the prevailing wind direction.

What is claimed is: 
     
         1 . A portable ground thawing system comprising:
 a heat chamber having an open bottom surrounded by a sidewall and a closed top, a charging inlet disposed in said sidewall, an exhaust flue disposed in said sidewall,   a heater having a discharge nozzle configured to emit a stream of hot gas along a discharge vector, said heater disposed proximate to said heat chamber with said discharge vector passing through said charging inlet, and   said flue being located generally opposite said charging inlet.   
     
     
         2 . The system of  claim 1  wherein said heat chamber is a generally cylindrical volume as defined by a generally cylindrical said sidewall and a generally circular said top and a generally circular said bottom, said flue being diametrically opposed to said charging inlet. 
     
     
         3 . The system of  claim 1  wherein said charging inlet has an upper extremity and a lower extremity, said lower extremity being axially spaced from bottom by a lower extremity distance (IL), said flue having a first edge adjacent said bottom and a second edge adjacent said top, said second edge being axially spaced from bottom by a second flue distance (F 2 ), said second flue distance (F 2 ) being less than or equal to said lower extremity distance (IL). 
     
     
         4 . The system of  claim 1  wherein said charging inlet has an upper extremity and a lower extremity, said upper extremity being axially spaced within 10% of a midline between said bottom and said top of said heat chamber. 
     
     
         5 . The system of  claim 1  further including a baffle moveably connected to said flue. 
     
     
         6 . The system of  claim 5  further including a moveable interface supporting said baffle for sliding movement relative to said flue. 
     
     
         7 . The system of  claim 5  wherein said baffle has at least one directional fin. 
     
     
         8 . The system of  claim 7  wherein said baffle is invertible in said flue so as to turn said directional fin upside down in use. 
     
     
         9 . The system of  claim 1  further including a mounting base supporting said heater at an incline so that said discharge vector passes through said charging inlet in a downward trajectory. 
     
     
         10 . The system of  claim 1  wherein said heat chamber is a generally cylindrical volume as defined by a generally cylindrical said sidewall and a generally circular said top and a generally circular said bottom, said flue being diametrically opposed to said charging inlet, further including a pair of handle loops attached to heat chamber, said handle loops being diametrically arranged from one another on said sidewall. 
     
     
         11 . The system of  claim 1  wherein said heat chamber is a generally cylindrical volume as defined by a generally cylindrical said sidewall and a generally circular said top and a generally circular said bottom, said flue being diametrically opposed to said charging inlet, and at least one of said charging inlet and said flue being generally rectangular. 
     
     
         12 . The system of  claim 11  wherein said flue having first edge adjacent said bottom and a second edge adjacent said top, said first edge of said flue being axially spaced from bottom by a first flue distance (F 1 ), further including a baffle moveably connected to said flue, said baffle has at least one directional fin, said baffle being invertible in said flue so as to turn said directional fin upside down in use, and a moveable interface supporting said baffle for sliding movement relative to said flue. 
     
     
         13 . The system of  claim 1  further including an electricity generator for supplying electrical power to said heater. 
     
     
         14 . The system of  claim 1  further including a fuel source for supply combustible fuel to said heater, said fuel source comprising a propane tank. 
     
     
         15 . A portable ground thawing system comprising:
 a heat chamber having an open bottom surrounded by a sidewall and a closed top, said heat chamber being a generally cylindrical volume as defined by a generally cylindrical said sidewall and a generally circular said top and a generally circular said bottom, a pair of handles attached to heat chamber, each said handle comprising a loop extending from said sidewall adjacent said top, said handles being diametrically arranged from one another on said cylindrical sidewall, a charging inlet disposed in said sidewall, said charging inlet having an upper extremity and a lower extremity, said lower extremity being axially spaced from bottom by an lower extremity distance (IL), said upper extremity being axially spaced generally midway between said bottom and said top of said heat chamber, said charging inlet being generally rectangular, an exhaust flue disposed in said sidewall, said flue being diametrically opposed to said charging inlet, said flue having first edge adjacent said bottom and a second edge adjacent said top, said first edge of said flue being axially spaced from bottom by an first flue distance (F 1 ), said second edge of said flue being axially spaced from bottom by a second flue distance (F 2 ), said second flue distance (F 2 ) being less than or equal to said lower extremity distance (IL), said flue being generally rectangular, a baffle moveably connected to said flue, said baffle having at least one directional fin, said baffle being invertible in said flue, a moveable interface supporting said baffle for sliding movement relative to said flue,   a heater having a discharge nozzle configured to emit a stream of hot gas along a discharge vector, said heater disposed proximate to said heat chamber with said discharge vector passing through said charging inlet,   a mounting base supporting said heater at an incline so that said discharge vector passes through said charging inlet in a downward trajectory, said mounting base including a generally flat sub-base, said mounting base including a plurality of shims disposed between said sub-base and said heater,   a electricity generator for supplying electrical power to said heater, and   a fuel source for supply combustible fuel to said heater.   
     
     
         16 . A method for placing a Shovel Test Pit (STP) in frozen ground comprising the steps of:
 preparing a test area by clearing debris and removing snow accumulations above a threshold limit,   positioning a heat chamber having an open bottom on the test area,   orienting the heat chamber so that a charging inlet thereof is leeward and an exhaust flue thereof is windward relative to the prevailing wind direction,   directing a stream of hot gas from a heater along a discharge vector passing through the charging inlet, and   circulating hot gases through a heat loft within the heat chamber above the charging inlet prior to exiting through the flue.   
     
     
         17 . The method of  claim 16  further including the step of pointing the discharge vector in a downward trajectory as it passes through the charging inlet. 
     
     
         18 . The method of  claim 16  further including the step of inverting a baffle in the flue to manipulate the flow of exhaust gases through the flue. 
     
     
         19 . The method of  claim 16  further including the step of moving a baffle relative to flue to constrict the exit flow rate of exhaust gases through the flue. 
     
     
         20 . The method of  claim 16  further including the steps of: removing the heat chamber from the test area when the underlying ground is thawed, digging a hole in the thawed ground, transferring soil excavated from the hole to a screen mesh, sifting the excavated soil through the screen mesh, removing any artifacts captured by the screen mesh, and returning the sifted soil to the hole.