GGH system

The invention discloses a GGH system. The GGH system comprises an air pre-heater and a desulfurization and dust removal device, a smoke outlet of the air pre-heater communicates with a smoke inlet ofthe desulfurization and dust removal device through a smoke conveying pipeline, a coal gas heat exchanger and a GGH smoke heat exchanger are sequentially connected to the smoke conveying pipeline in the direction of smoke conveying, a smoke outlet of the desulfurization and dust removal device communicates with a smoke inlet of the GGH smoke heat exchanger through a cold clean smoke conveying pipeline, and the caol gas heat exchanger correspondingly communicates with a coal gas conveying pipeline. The GGH system comprises two heat exchanging systems, on the one hand, the gradient utilization of high temperature smoke and medium-low temperature smoke is achieved, according to the gradient utilization process, temperature reduction of the smoke in the inlet of an induced draft fan is achieved, the power consumption