Babcock and Wilcox Boiler

Figure 3.5 shows a stationary type Babcock and Wilcox boiler. It consists of a large number of parallel tubes inclined at an angle which varies from 5° to 15° to the horizontal which connect the uptake header with the downtake header. These are connected to the shell having a substantial quantity of water in it. The uptake header is connected to the shell, through a short tube, whereas a long tube is employed to connect the downtake header with the shell. The coal is fed through the fire hole on to the chain grate stoker. The velocity of the chain is adjusted so as to ensure complete combustion of coal by the time it reaches the other end of the grate. The flue gases first rise up, move down, and rise up again due to the presence of the baffles. The hot water and steam moisture rise up through the uptake header into the boiler shell, where steam separates from water and collects in the steam space. The cold water flows down into the tubes through the downtake header. Hence, a continuous circulation of water is maintained by the convection currents set up.