Forced-draft fans speed, adjustment

Consider a forced-draft boiler producing 600-psig steam as shown in Fig. 20.2. The fuel rate on this boiler is fixed and we are going to optimize the oxygen (02) content of the flue gas by adjusting the speed of the forced-draft fan. Do we simply adjust the forced-draft (FD) fan to give 2 percent 02 in the stack because someone once said that 2 percent 02 in the stack was a good number ... 

Air is circulated by multiblade propeller-type ns that provide forced or induced drafts. Fans can be supplied with either adjustable-speed or variable-pitch blades. The fen blade pitch can be changed to vary the air-flow rate to compensate for rising or falling air temperatures. Air coolers supplied with multiple fens may be operated with some of the fens shut down. Dampers, baffles, and bypasses can also be tised to further control liquid outlet temperature. For elevated installations, platforms are generally furnished for access to header boxes and motors. 

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See also in sourсe #XX -- [ ]

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