The Effect of the Ratio of the Secondary and Tertiary Air on the Outlet Velocity Field of the New Swirling Pulverized Coal Burner

ABSTRACT

The outlet velocity field of the pulverized coal burner is one of the important factors affecting its operating characteristics. In this article, cold tests were carried out for a new swirl burner with a pre-combustion chamber, and the influence of the air ratio on the outlet velocity field of the burner was studied. Through the cold single-phase test on the 1:3 model test bench, the burner outlet cold air velocities were obtained. The results shown that the formation of the central recirculation zone was mainly affected by the secondary air, a stable central recirculation zone could not be formed when the velocity of secondary air was too low. When the total air of the burner was fixed, the secondary air increased, the length of the central recirculation zone increased, and the mixing speed between different flows increased. When the ratio of the mass flow of the secondary air to tertiary air increased from 26:74 to 85:15, the reflux rate increases 5.5 times, which helped to keep the combustion stable.

KEYWORDS:

• Industrial pulverized coal boiler
• swirl burner
• cold velocity field
• recirculation zone
• pre-combustion chamber

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Key Research and Development Program of China [Grant No. 2017YFC0212500].