A pulverized fuel combustion burner and furnace arrangement has a plurality of air nozzles arranged on a side wall of the furnace for injecting a mixed flow of pulverized fuel and carrier air to establish a flame into the furnace. The plurality of nozzles includes a primary nozzle for injecting the mixed flow into the furnace and a secondary nozzle positioned around the primary nozzle for feeding combustion auxiliary air around the primary nozzle. A pulverized fuel supply pipe feeds the mixed flow to the primary nozzle. The primary nozzle and the pulverized fuel supply pipe are joined at a jointed portion at which the primary nozzle can be pivoted to change a direction for injecting the mixed flow into the furnace. The pulverized fuel supply pipe extends through a windbox, the windbox forming a combustion auxiliary air supply passage around the pulverized fuel supply pipe. A rich/lean flow separator is disposed in a middle portion of the pulverized fuel supply pipe spaced from opposite inner walls of the pulverized fuel supply pipe such that when the mixed flow flows around the rich/lean flow separator, a rich/lean flow concentration distribution is established in which a fuel-rich flow is created at an outer part inside of the pulverized fuel supply pipe and adjacent to the opposite inner walls and a fuel-lean flow is created at an inner part inside of the rich flow and along a center line of the pulverized fuel supply pipe. Flow straightening plates are disposed and positioned in the primary nozzle and the pulverized fuel supply pipe downstream of the rich/lean flow separator so as to maintain the rich/lean flow concentration distribution established by the rich/lean flow separator to the exit of the primary nozzle.