A set of comprehensive on-site experiments was conducted to assess the performance of the louver-type primary air (PA) concentrators on anthracite ignition and combustion in a 600 MW supercritical arch-fired boiler (AFB) equipped with slot burners. The temperature profiles along the PA stream from fuel-rich and fuel-lean streams were measured tinder various conditions. The separation efficiency of the PA concentrators of two selected burners was also measured and its effect on the ignition of the PA streams was studied. Experimental results revealed that separation performance of some louver concentrators was even opposite to design setting. The ignitability of PA stream, however, was more profoundly depended on the configuration of burner, the position of the nozzle and the SA distribution than the separation performance of the louver concentrators. On the other hand, confirmed by numerical simulation, the unsatisfied separation performance of the louver-type concentrators could result in overall poor ignition of PA, causing over-shooting of the flame penetration length, and high loss of ignition and difficulties for combustion organization. Some suggestions are given to the retrofit and new design of combustion system. (C) 2017 Elsevier B.V. All rights reserved.