A review on low-load stable combustion technology for boiler in deep peak shaving of coal-fired power units

Boiler low-load stable combustion technology is a key means to solve the problem of unstable combustion in boiler during the deep peak shaving of coal-fired power units. This study provides a systematic review of boiler low-load stable combustion technology, including 1) low load stable combustion mechanism, 2) low load stable combustion methods for coal-fired boiler and 3) future development direction of technology. In essence, the boiler low-load stable combustion is to reduce the ignition heat of pulverized coal, provide sufficient ignition supply heat for pulverized coal, ensure the match between the speed of the pulverized coal gas flow and the flame propagation speed, and create a reasonable flame organization, so that the pulverized coal can be reliably ignited, propagated, and ultimately form a stable flame near the burner nozzle. The low load stable combustion methods mainly involve: fine operation adjustment of the boiler system itself and external auxiliary stable combustion methods. The former achieves stable combustion of the boiler at low load by optimizing air and coal parameters, as well as the structure and arrangement of the burner. The latter achieves stable combustion of the boiler at low load by enhancing the ignition supply heat provided by the external heat source involving combustion-supporting fuel, plasma, microwave, and electric induction heating. In the future, in-depth exploration of the mechanism is the cornerstone of the innovative development of low-load stable combustion technology. Meanwhile, its innovative development also lies in the multi-technology integration, policy-driven, and economic and environmental impact assessments. The review aims to assist researchers and engineers to gain fundamental understandings and critical view of boiler low-load stable combustion technology, and hopefully with the knowledge it could bring new opportunities for the future development of deep peak shaving of coal-fired power units. • Boiler low load stable combustion technology in deep peak shaving is reviewed. • Boiler low load stable combustion mechanism is summarized. • Technology methods are classified and discussed based on stable combustion mechanism. • Development directions for boiler low load stable combustion technology are given.