Disclosed is an external gas heating device of a coal pyrolyzing furnace. The external gas heating device is positioned on the middle part of a coal pyrolyzing furnace body and around the outer wall of a carbonizing chamber and comprises more than one group of first gas heater and second gas heater that have the same structure and a gas reversing device. The gas reversing device supplies air and purified gas into a combustion chamber of the first gas heater to be combusted and meanwhile sucks hot waste gas from a combustion chamber of the second gas heater. In the same way, the gas reversing device supplies air and purified gas into the combustion chamber of the second gas heater to be combusted and meanwhile sucks hot waste gas from the combustion chamber of the first gas heater.

Disclosed is an external gas heating device of a coal pyrolyzing furnace. The external gas heating device is positioned on the middle part of a coal pyrolyzing furnace body and around the outer wall of a carbonizing chamber and comprises more than one group of first gas heater and second gas heater that have the same structure and a gas reversing device. The gas reversing device supplies air and purified gas into a combustion chamber of the first gas heater to be combusted and meanwhile sucks hot waste gas from a combustion chamber of the second gas heater. In the same way, the gas reversing device supplies air and purified gas into the combustion chamber of the second gas heater to be combusted and meanwhile sucks hot waste gas from the combustion chamber of the first gas heater.