System for raising coal economizer outlet flue gas temperature

The invention belongs to the field of boiler wide load denitration and particularly relates to a system for raising the coal economizer outlet flue gas temperature. According to the novel system for raising the coal economizer outlet flue gas temperature, when the system is applied during the low-load period of a boiler, coal economizer fed water enters a tee joint through a water feeding main pipe and then is divided into two branches; water of one branch directly enters an inner ring sleeve through a bypass pipe and then enters an outer ring sleeve through a first through hole in the inner ring sleeve, and water of the other branch enters a first coal economizer inlet collection box through a main loop pipe and enters a first coal economizer pipe bundle through the first coal economizerinlet collection box; and after heat exchange is conducted between a working medium in the first coal economizer pipe bundle and high-temperature flue gas flowing through the outside of the first coaleconomizer pipe bundle, t