A BOILER, A METHOD OF CONTROLLING THE COMBUSTION IN A BOILER AND A HEAT EXCHANGER TUBE FOR USE IN A BOILER

摘要

A boiler comprising a furnace chamber, a passage extending through an aperture 9 in a bottom wall of the chamber and defined by an exterior truncated cone 18 tapering towards a boundary interface 19 with an interior truncated cone 17 also tapering towards the interface, the exterior and interior truncated cones having a substantially common axis, a burner lance 21 extending along the axis through the passage, a burner nozzle 23 mounted at the interior end of said lance, and a substantially circular flame stabilizing disc 24 mounted on the interior end of the lance coaxially with the truncated cones and interiorly of the nozzle and having a central aperture 34 in register with the nozzle for allowing combustion fuel from the nozzle to enter the chamber, the lance being arranged axially displaceable between a first , innermost, position and a second, outermost, position such that the stabilizing disc is located at a distance B from the boundary 19 in a position between the largest and the smallest diameter of the interior truncated cone when the lance is displaced axially to an intermediate position between the innermost position and the outermost position.