Carbon deposition of coal tar is the main factor that restricts the long term efficient and safe operation of the ascension-pipe heat exchanger for recovering sensible heat of raw coke oven gas (COG). It is an effective measure to prevent carbon deposition of coal tar by controlling temperatures of raw COG and inner wall of ascension pipe. Based on local non-thermal equilibrium idea of porous media, a one-dimensional unsteady heat transfer model was established for the ascension-pipe heat exchanger with embedded spiral coils and porous fillers for sensible heat recovery of raw gas. Based on the instantaneous data of raw gas flow and temperature during the coking cycle, the dynamic characteristics of temperatures of raw COG, wall of ascension pipe, packing layer and molten salt were obtained. The effects of the heat capacity of filler layer, effective thermal conductivity of filler layer, and molten salt flow rate on its dynamic changes were analyzed. Moreover, a method was proposed to effectively control temperatures of raw COG and wall of ascension pipe. The results show that the coal tar precipitation mainly occur in the late coking period when raw COG output will decrease quickly. The thermal conductivity of packing layer is an important parameter to be considered in the design of the ascension-pipe heat exchanger. Increasing the conductivity of packing layer can improve the heat recovery efficiency, but also make the temperature drops of raw COG and wall of ascension pipe increased. The thermal conductivity of the packing layer should be increased as far as possible under the premise of ensuring that the tar vapor does not condense. In the later stage of coking, the temperature control of the rising pipe wall can be realized by cutting off the molten salt to get heat, and reasonably designing the thermal conductivity of packing layer, the heat capacity of packing layer and the inlet temperature of molten salt, so as to avoid the coal tar precipitation.