Key Features of Four-Pass Single Cross Drum Water Tube Steam Boiler

• 4 Pass design, ensures better heat utilization & ultimate thermal efficiency.
• Fluidized Bed Combustion furnace ensures very high combustion efficiency, up to 95% even with fuel, having very high ash & fine contents and having very low calorific value.
• Instead of furnace imbed cooling coil, straight imbed cooling tubes- having opening in the box header out side the furnace brick wall with individual access door caps on both sides of each tube - are provided. These tubes are roller expanded in box header, and not welded. Hence, boiler down time cost is almost nil.
• Straight tube in generating bank enables manual cleaning & easy inspection.
• The headers are of welded type box headers with individual opening against each tube at both ends of generating bank. Hence, for cleaning & maintenance of any single tube only single door cap, weighing just 1.5 kg has to be opened.
• Larger tube diameter in generating bank, i.e. 76.2 mm OD, enables easy manual cleaning.
• Intermediate tube supports in the generating bank, which prevents tube sagging contributes to higher boiler life.
• Wide gap in tube spacing i e. 160 mm pitch, prevents inter tube space plugging by soot deposition, which permits trouble free operation without external cleaning as clogging of tube space with soot does not take place.
• Free floating front header takes care of longitudinal thermal expansion. Hence, thermal stresses are not developed during heating. This design enhances boiler life too.
• Man hole opening at both sides of the drum for easier access to drum internals.
• Larger diameter drum coupled with drum internal steam separators ensures dry steam even at full main steam valve opening.
• Moderately larger furnace area and higher free board height, above grate, makes the boiler capable to burn low grade, high volatill3 & ash contained solid fuel efficiently without reducing rated steam generating capacity.
• No inventory of spares, since nothing special is employed which is necessary to be procured urgently from the company or which is not available in the free market.