Two typical inherent characteristics of boilers are summarized

and the correlation between these characteristics and the existing air and flue gas system and common problems of coal-fired boiler is analyzed. In order to improve the inherent characteristics of the boiler

a new boiler flue gas dual circulation system is proposed. This paper mainly introduces the location and main purpose of the internal circulation flue gas in the boiler flue gas dual system at different boiler loads

as well as its role in improving the inherent characteristics and solving the common problems of the boiler. The results show that

the inherent characteristics and common problems of boilers are difficult to improve in the modern conventional air and flue gas system. The flue gas dual circulation system can effectively improve the inherent characteristics of modern boilers and solve the common problems at various loads of the boiler

and its economy and environmental protection are better than the existing air and flue gas system. The flue gas dual circulation system is able to be applied directly in engineering.