Abstract: The present invention relates to a pulverized coal ignition burner apparatus for use with a pulverized coal boiler or the like for a thermal power plant. The apparatus is so constructed that the pulverized coal is directly burned without generation of a large amount of NOx and without using auxiliary fuel such as light oil, heavy oil and gas that are needed in the conventional apparatus. In the pulverized coal burner apparatus, an ignition region (39) in which a density of the pulverized coal of the mixture of the air and the pulverized coal supplied from a pulverized coal supply source (18) to a pulverized coal burner (4 to 9) by means of a delivery system (23, 50) is enhanced and the flow rate of the mixture flow is low is formed within the pulverized coal burner. The pulverized coal within this region is ignited by an igniter (41).

Abstract: A boiler tube having a double-tube structure constituted by an inner tube and an outer tube integrated with each other. The inner tube is made of an alloy consisting essentially of, by weight, 0.02 to 0.15% of C, 0.5 to 3.5% of Si, not greater than 2% of Mn, 25 to 40% of Ni, 20.5 to 27% of Cr, 0.5 to 3% of Mo, not greater than 1% of Nb and the balance Fe and having a substantially fully austenite structure. The outer tube is made of an alloy consisting essentially of, by weight, 0.02 to 0.2% of C, not greater than 3.5% of Si, not greater than 2% of Mn, 33 to 45% of Ni, 30 to 40% of Cr and the balance Fe and having a substantially fully austenite structure. The inner tube made of the alloy having the composition specified above exhibits a high resistance to steam oxidation without any reduction in high-temperature strength even at elevated steam temperature, while the outer tube made of the alloy having the composition specified above exhibits a superior resistance to corrosion by coal combustion gas.