Optimization recovery system for reduction tail gas heat energy in polycrystalline silicon production

The invention relates to the technical field of chemical engineering, in particular to an optimization recovery system for reduction tail gas heat energy in the polycrystalline silicon production, which is characterized in that reduction tail gas is firstly introduced into a reducing tail gas inlet of an afterheat boiler to be used as an evaporation heat source of the afterheat boiler, reduction tail gas after the heat exchange through the afterheat boiler enters a tail gas heat exchanger for carrying out heat exchange with water, the water becomes hot water of 80 to 115 DEG C after the heat exchange by the tail gas heat exchanger and is then divided into two paths to be respectively input into a water inlet of the afterheat boiler and a water inlet of a furnace tube water flash drum of areducing furnace, and reduction tail gas after the heat exchange by the tail gas heat exchanger enters a tail gas cooler to carry out heat exchange with the cyclic water from a cyclic water pipe network and is then sent into