Heat recovery arrangement

A heat recovery system comprising:

• a rover configured to move in a forward direction;
• a preheat contact element configured to contact and preheat granular soil;
• a heating gap between the preheat contact element and a heat recovery sled;
• a primary heat source configured to heat a region of the preheated granular soil in the gap, the heat recovery sled configured to collect at least a portion of the heat from the region when the rover moves the heat recovery sled in contact with the region;
• a gas collecting shield covering at least the gap, wherein the gas collecting shield is configured to contain gas liberated from the granular soil when heated by the primary heat source;
• and
• a heat exchange tube comprising:
• a feed line configured to carry warmed medium from a heat collecting coil in the preheat contact element to a heat emitting coil in the heat recovery sled, and
• a return line configured to carry cooled medium from the heat emitting coil to the heat collecting coil,
• the gas collecting shield, the preheat contact element and the heat recovery sled are located on an under side of the rover.

A method for using a heat recovery system, the method comprising:

• heating a first region of granular soil in a gap between a preheat contact element and a heat recovery sled with a primary heat source;
• moving the heat recovery sled in contact with the first region of granular soil;
• warming a medium circulating through a heat collecting coil that is embedded in the heat recovery sled while the heat recovery sled is in contact with the first region of granular soil;
• preheating a second region of granular soil by circulating the warmed medium through a heat emitting coil embedded in the preheat contact element;
• and
• moving the gap over the preheated second region of granular soil and heating the preheated second region of granular soil via the primary heat source.