Technology and system for upgrading low-rank coal through high-heating-value gas heat carrier

The invention discloses a technology and a system for upgrading low-rank coal through a high-heating-value gas heat carrier, and solves the problems that the conventional technology for upgrading low-rank coal through the high-heating-value gas heat carrier cannot directly utilize a great amount of low-heat-value pyrolysis gas, and the operation cost is high. The technical scheme comprises the following steps: conveying raw coal to a drying furnace for drying; then conveying the raw coal to a pyrolysis furnace for pyrolysis; obtaining semicoke and crude pyrolysis gas after water and most volatile components are removed; performing dust removing, washing and cooling on the crude pyrolysis gas, wherein the pyrolysis gas subjected to dust removing, washing and cooling can be divided into at least two parts, the first part of pyrolysis gas is conveyed to the pyrolysis heating furnace as fuel, the generated high-temperature fume is used for indirectly heating the second part of pyrolysis gas which is conveyed to t