Q. Combustion Chamber and Radiant Section?
The combustion chamber and the radiant heat transfer section of the Steam Generators shall be a horizontal, multiple pass arrangement, straight tube design, with tubes transposed around the inner diameter of a refractory lined, cylindrical combustion chamber. The passes of tubing shall remain side-by-side through the radiant section.
Radiant tubes shall be arranged in a 1-2-3-4-5, etc., etc. 5-4-3-2-1 configuration to allow for even heat distribution while still allowing the units to be fully drainable.
The volumetric heat release in the Steam Generators shall be limited to 26,090 Btu/ft3/h (972 MJ/m3/h), and the average heat flux in the radiant section based on total circumferential heating surface, shall not exceed 18,000 Btu/ft2/h (56.8 kW/m2).
All radiant tube paths shall enter and leave the generators at the bottom, underneath the economizer support structure (hog trough).
The dimensions of the combustion chamber, tube arrangement, and spacing shall be selected for optimum heat transfer. The length to diameter ratio of the combustion chamber shall not exceed 3.0. The "L" is defined as the straight length of the tubes excluding the return bends, and the "D" is defined as the diameter of the circle drawn by connecting the centres of the circles formed by the tubes. Care shall be taken to minimize the maldistribution of radiant heat flux in the furnace.
The tube circle diameter, length of the furnace, and the shape of the flame selected for this application shall ensure there shall be no flame impingement on convective, radiant, or refractory surfaces under any operating condition.